/src/mhd2/src/include/microhttpd2.h

Source
/* SPDX-License-Identifier: LGPL-2.1-or-later OR (GPL-2.0-or-later WITH eCos-exception-2.0) */
/*
  This file is part of GNU libmicrohttpd.
  Copyright (C) 2006-2026 Christian Grothoff, Karlson2k (Evgeny Grin)
  (and other contributing authors)

  GNU libmicrohttpd is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  GNU libmicrohttpd is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  Alternatively, you can redistribute GNU libmicrohttpd and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of
  the License, or (at your option) any later version, together
  with the eCos exception, as follows:

    As a special exception, if other files instantiate templates or
    use macros or inline functions from this file, or you compile this
    file and link it with other works to produce a work based on this
    file, this file does not by itself cause the resulting work to be
    covered by the GNU General Public License. However the source code
    for this file must still be made available in accordance with
    section (3) of the GNU General Public License v2.

    This exception does not invalidate any other reasons why a work
    based on this file might be covered by the GNU General Public
    License.

  You should have received copies of the GNU Lesser General Public
  License and the GNU General Public License along with this library;
  if not, see <https://www.gnu.org/licenses/>.
*/

/*
  Main goals for the libmicrohttpd 2.0 API:

  - simplify application callbacks by splitting header/upload/post
    functionality currently provided by calling the same
    MHD_AccessHandlerCallback 3+ times into separate callbacks.
  - keep the API very simple for simple requests, but allow
    more complex logic to be incrementally introduced
    (via new struct MHD_Action construction)
  - avoid repeated scans for URL matches via the new
    struct MHD_Action construction
  - better types, in particular avoid varargs for options
  - make it harder to pass inconsistent options
  - combine options and flags into more uniform API (at least
    exterally!)
  - simplify API use by using sane defaults (benefiting from
    breaking backwards compatibility) and making all options
    really optional, and where applicable avoid having options
    where the default works if nothing is specified
  - simplify API by moving rarely used http_version into
    MHD_request_get_info_fixed()
  - avoid 'int' for MHD_YES/MHD_NO by introducing `enum MHD_Bool`
  - improve terminology by eliminating confusion between
    'request' and 'connection'; add 'session' for HTTP2/3;
    use clear separation between connection and request. Do not mix the kind
    data in the callbacks.  Currently we are mixing things in
    MHD_AccessHandlerCallback and MHD_RequestCompletedCallback. Instead of
    pointers to struct MHD_Connection we should use pointers to (new) struct
    MHD_Request.
  - prepare API for having multiple TLS backends
  - use more consistent prefixes for related functions
    by using MHD_subject_verb_object naming convention, also
    at the same time avoid symbol conflict with legacy names
    (so we can have one binary implementing old and new
    library API at the same time via compatibility layer).
  - make it impossible to queue a response at the wrong time
  - make it impossible to suspend a connection/request at the
    wrong time (improves thread-safety)
  - make it clear which response status codes are "properly"
    supported (include the descriptive string) by using an enum;
  - simplify API for common-case of one-shot responses by
    eliminating need for destroy response in most cases;
  - avoid fixed types, like uint32_t. They may not exist on some
    platforms. Instead use uint_fast32_t.
    It is also better for future-proof.
  - check portability for embedded platforms. Some of them support
    64 bits, but 'int' could be just 16 bits resulting of silently
    dropping enum values higher than 65535.
    => in general, more functions, fewer enums for setup
  - Avoid returning pointers to internal members. It is not thread-safe and
    even in single thread the value could change over the time. Prefer pointers to
    app-allocated memory with the size, like MHD_daemon_get_static_info(enum
    MHD_enum_name info_type, void *buf, size_t buf_size).
    => Except in cases where zero-copy matters.
  - Use separate app calls/functions for data the will not change for the
    lifetime of the object and dynamic data. The only difference should be the
    name. Like MHD_daemon_get_static_info(enum MHD_enum_name info_type, void *buf,
    size_t buf_size) MHD_daemon_get_dynamic_info(enum MHD_enum_name info_type,
    void *buf, size_t buf_size) Examples of static data: listen socket, number of
    workers, daemon flags.  Examples of dynamic data: number of connections,
    quiesce status.  It should give a clear idea whether the data could be changed
    over the time (could be not obvious for some data) and thus may change the
    approach how to use the data in app.  The same for: library, daemon,
    connection, request. Not sure that dynamic data makes sense for the library.
  - Define response code in response object. There are a very little
    chance that response body designed for 404 or 403 codes will be used with
    200 code. However, the responses body for 307 and 308 could be the same. So:
    Add default response code in response object.
  - Make responses unmodifiable after first use. It is not thread-safe.
    MHD-generated headers (Date, Connection/Keep-Alive) are again
    part of the *request* and do not count as part of the "response" here.
  - Remove "footers" from responses. With unmodifiable responses everything should
    be "headers". Add footers to *requests* instead.
  - Add API for adding request-specific response headers and footers. To
    simplify the things it should just copy the strings (to avoid dealing with
    complicated deinit of possible dynamic strings).  After this change it should
    be possible to simplify DAuth handling as response could be reused (currently
    403 responses are modified for each reply).
  - Control response behaviour mainly by response flags, not by additional
    headers (like MHD_RF_FORCE_CLOSE instead of "Connection: close").
    It is easier&faster for both: app and MHD.
  - Move response codes from MHD_HTTP_xxx namespace to MHD_HTTP_CODE_xxx
    namespace. It already may clash with other HTTP values.
  - Postprocessor is unusable night-mare when doing "stream processing"
    for tiny values where the application basically has to copy together
    the stream back into a single compact heap value, just making the
    parsing highly more complicated (see examples in Challenger)
  - non-stream processing variant for request bodies, give apps a
    way to request the full body in one buffer; give apps a way
    to request a 'large new allocation' for such buffers; give apps
    a way to specify a global quota for large allocations to ensure
    memory usage has a hard bound

  - Internals: carefully check where locking is really required. Probably
    separate locks. Check out-of-thread value reading. Currently code assumes
    atomic reading of values used in other threads, which mostly true on x86,
    but not OK on other arches. Probably use read/write locking to minimize
    the threads interference.
  - Internals: figure out how to do portable variant of cork/uncork
  - Internals: remove request data from memory pool when response is queued
    (IF no callbacks and thus data cannot be used anymore, or IF
     application permits explicitly per daemon) to get more space
    for building response;
  - Internals: Fix TCP FIN graceful closure issue for upgraded
    connections (API implications?)

*/

#ifndef MICROHTTPD2_H
#define MICROHTTPD2_H

#ifndef __cplusplus
#  define MHD_C_DECLARATIONS_START_HERE_   /* Empty */
#  define MHD_C_DECLARATIONS_FINISH_HERE_  /* Empty */
#else  /* __cplusplus */
/* *INDENT-OFF* */
#  define MHD_C_DECLARATIONS_START_HERE_   extern "C" {
#  define MHD_C_DECLARATIONS_FINISH_HERE_  }
/* *INDENT-ON* */
#endif /* __cplusplus */

MHD_C_DECLARATIONS_START_HERE_

/**
 * Current version of the library in packed BCD form.
 * (For example, version 1.9.30-1 would be 0x01093001)
 */
#define MHD_VERSION 0x01990001

#include "microhttpd2_portability.h"

/* If generic headers do not work on your platform, include headers that
   define 'va_list', 'size_t', 'uint_least16_t', 'uint_fast32_t',
   'uint_fast64_t', and 'struct sockaddr', and then
   add "#define MHD_HAVE_SYS_HEADERS_INCLUDED" before including "microhttpd2.h".
   When 'MHD_HAVE_SYS_HEADERS_INCLUDED' is defined, the following "standard"
   includes will not be used (which might be a good idea, especially on
   platforms where they do not exist).
   */
#ifndef MHD_HAVE_SYS_HEADERS_INCLUDED
#  include <stdarg.h>
#  ifndef MHD_SYS_BASE_TYPES_H
/* Headers for uint_fastXX_t, size_t */
#    include <stdint.h>
#    include <stddef.h>
#    include <sys/types.h> /* This header is actually optional */
#  endif
#  ifndef MHD_SYS_SOCKET_TYPES_H
/* Headers for 'struct sockaddr' */
#    if !defined(_WIN32) || defined(__CYGWIN__)
#      include <sys/socket.h>
#    else
/* Prevent conflict of <winsock.h> and <winsock2.h> */
#      if !defined(_WINSOCK2API_) && !defined(_WINSOCKAPI_)
#        ifndef WIN32_LEAN_AND_MEAN
/* Do not use unneeded parts of W32 headers. */
#          define WIN32_LEAN_AND_MEAN 1
#        endif /* !WIN32_LEAN_AND_MEAN */
#        include <winsock2.h>
#      endif
#    endif
#  endif
#endif

#ifndef MHD_BOOL_DEFINED

/**
 * Representation of 'bool' in the public API as stdbool.h may not
 * always be available and presence of 'bool' keyword may depend on
 * used C version.
 * It is always safe to cast 'MHD_Bool' variable to 'bool' and vice versa.
 * Note: it may be UNSAFE to cast pointers 'MHD_Bool*' to 'bool*' and
 *       vice versa.
 */
enum MHD_Bool
{

  /**
   * MHD-internal return code for "NO".
   */
  MHD_NO = 0
  ,
  /**
   * MHD-internal return code for "YES".  All non-zero values
   * will be interpreted as "YES", but MHD will only ever
   * return #MHD_YES or #MHD_NO.
   */
  MHD_YES = 1
};


#  define MHD_BOOL_DEFINED 1
#endif /* ! MHD_BOOL_DEFINED */

#ifndef MHD_STRINGS_DEFINED


/**
 * String with length data.
 * This type should always have valid @a cstr pointer.
 */
struct MHD_String
{
  /**
   * Number of characters in @e str, not counting 0-termination.
   */
  size_t len;

  /**
   * 0-terminated C-string.
   * Must not be NULL.
   */
  const char *cstr;
};

/**
 * String with length data.
 * This type of data may have NULL as the @a cstr pointer.
 */
struct MHD_StringNullable
{
  /**
   * Number of characters in @e cstr, not counting 0-termination.
   * If @a cstr is NULL, it must be zero.
   */
  size_t len;

  /**
   * 0-terminated C-string.
   * In some cases it could be NULL.
   */
  const char *cstr;
};

#  define MHD_STRINGS_DEFINED 1
#endif /* ! MHD_STRINGS_DEFINED */


#ifndef MHD_INVALID_SOCKET
#  if !defined(_WIN32) || defined(_SYS_TYPES_FD_SET)
#    define MHD_SOCKETS_KIND_POSIX 1
/**
 * MHD_Socket is a type for socket FDs
 */
typedef int MHD_Socket;
#    define MHD_INVALID_SOCKET (-1)
#  else /* !defined(_WIN32) || defined(_SYS_TYPES_FD_SET) */
#    define MHD_SOCKETS_KIND_WINSOCK 1
/**
 * MHD_Socket is a type for socket FDs
 */
typedef SOCKET MHD_Socket;
#    define MHD_INVALID_SOCKET (INVALID_SOCKET)
#  endif /* !defined(_WIN32) || defined(_SYS_TYPES_FD_SET) */
#endif /* MHD_INVALID_SOCKET */


/**
 * Constant used to indicate unknown size (use when creating a response).
 * Any possible larger sizes are interpreted as the same value.
 */
#ifdef UINT64_MAX
#  define MHD_SIZE_UNKNOWN UINT64_MAX
#else
#  define MHD_SIZE_UNKNOWN \
          MHD_STATIC_CAST_ (uint_fast64_t,0xffffffffffffffffU)
#endif


/**
 * Constant used to indicate unlimited wait time.
 * Any possible larger values are interpreted as this value.
 */
#ifdef UINT64_MAX
#  define MHD_WAIT_INDEFINITELY UINT64_MAX
#else
#  define MHD_WAIT_INDEFINITELY \
          MHD_STATIC_CAST_ (uint_fast64_t,0xffffffffffffffffU)
#endif


/* ********** (a) Core HTTP Processing ************ */


/**
 * @brief Handle for a daemon that listens for requests.
 *
 * Manages the listen socket, event loop, optional threads and server
 * settings.
 *
 * @defgroup daemon HTTP server handling client connections
 */
struct MHD_Daemon;


/**
 * @brief Handle/identifier of a network connection abstraction.
 *
 * A single network (i.e. TCP) connection can be used for
 * a single (in HTTP/1.1) data stream.
 *
 * @defgroup connection client connection with streams
 */
struct MHD_Connection;


/**
 * @brief Handle/identifier of a data stream over network
 * connection.
 *
 * A data stream may be used for multiple requests, which
 * in HTTP/1.1 must be processed sequentially.
 *
 * @defgroup stream stream of HTTP requests
 */
struct MHD_Stream;

/**
 * @brief Handle representing an HTTP request.
 *
 * With HTTP/1.1, multiple requests can be run over the same
 * stream.  However, MHD will only show one request per data
 * stream to the client at any given time.
 *
 * Replaces `struct MHD_Connection` in the API prior to version 2.0.0,
 * renamed to better reflect what this object truly represents to
 * the application using MHD.
 *
 * @defgroup request HTTP requests
 */
struct MHD_Request;


/**
 * @brief Actions are returned by the application when processed client header
 * to drive the request handling of MHD.
 *
 * @defgroup action Request actions
 */
struct MHD_Action;


/**
 * @brief Actions are returned by the application when processing client upload
 * to drive the request handling of MHD.
 *
 * @defgroup action Request actions
 */
struct MHD_UploadAction;

/**
 * @defgroup general Primary MHD functions and data
 */

/**
 * @defgroup specialized Introspection and other special control
 */

/**
 * @defgroup authentication Digest and other HTTP authentications
 */


/**
 * Status codes returned by API functions, also used for logging.
 *
 * As a return value, zero (#MHD_SC_OK) always indicates success.
 * Values 00001-09999 must be handled explicitly by the application.
 * Values 10000-19999 are informational events.
 * Values 20000-29999 indicate successful operations.
 * Values 30000-39999 indicate unsuccessful but normal operations.
 * Values 40000-49999 indicate client (or network) errors.
 * Values 50000-59999 indicate MHD-internal (or platform) errors.
 * Values 60000-65535 indicate application errors.
 *
 * @ingroup general
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_StatusCode
{

  /* 00000-level codes are return values the application must handle.
     The zero code always means success. */

  /**
   * Successful operation (not used for logging).
   * The code is guaranteed to be always zero.
   */
  MHD_SC_OK = 0
  ,

  /* 10000-level codes are purely informational events. */

  /**
   * Informational event, MHD started.
   */
  MHD_SC_DAEMON_STARTED = 10000
  ,
  /**
   * Informational event, we accepted a connection.
   */
  MHD_SC_CONNECTION_ACCEPTED = 10001
  ,
  /**
   * Informational event, thread processing connection terminates.
   */
  MHD_SC_THREAD_TERMINATING = 10002
  ,
  /**
   * Informational event, state machine status for a connection.
   */
  MHD_SC_STATE_MACHINE_STATUS_REPORT = 10003
  ,
  /**
   * accept() returned transient error.
   */
  MHD_SC_ACCEPT_FAILED_EAGAIN = 10004
  ,
  /**
   * Accepted socket is unknown type (probably non-IP).
   */
  MHD_SC_ACCEPTED_UNKNOWN_TYPE = 10040
  ,
  /**
   * The sockaddr for the accepted socket does not fit the buffer.
   * (Strange)
   */
  MHD_SC_ACCEPTED_SOCKADDR_TOO_LARGE = 10041
  ,

  /* 20000-level codes indicate successful operations. */
  /* Examples: a connection has been closed normally, the response data
     generation has been completed. */

  /**
   * MHD is closing a connection after the client closed it
   * (perfectly normal end).
   */
  MHD_SC_CONNECTION_CLOSED = 20000
  ,
  /**
   * MHD is closing a connection because the application
   * logic to generate the response data completed.
   */
  MHD_SC_APPLICATION_DATA_GENERATION_FINISHED = 20001
  ,
  /**
   * The request does not contain a particular type of Authentication
   * credentials
   */
  MHD_SC_AUTH_ABSENT = 20060
  ,

  /* 30000-level codes indicate unsuccessful but normal operations. */
  /* Examples: a connections limit has been reached, the accept policy
     callback has rejected a connection, a memory pool is exhausted. */


  /**
   * Resource limit in terms of number of parallel connections
   * hit.
   */
  MHD_SC_LIMIT_CONNECTIONS_REACHED = 30000
  ,
  /**
   * The operation failed because the respective
   * daemon is already too deep inside of the shutdown
   * activity.
   */
  MHD_SC_DAEMON_ALREADY_SHUTDOWN = 30020
  ,
  /**
   * Failed to start new thread because of system limits.
   */
  MHD_SC_CONNECTION_THREAD_SYS_LIMITS_REACHED = 30030
  ,
  /**
   * Failed to start a thread.
   */
  MHD_SC_CONNECTION_THREAD_LAUNCH_FAILURE = 30031
  ,
  /**
   * The operation failed because we either have no
   * listen socket or were already quiesced.
   */
  MHD_SC_DAEMON_ALREADY_QUIESCED = 30040
  ,
  /**
   * The operation failed because client disconnected
   * faster than we could accept().
   */
  MHD_SC_ACCEPT_FAST_DISCONNECT = 30050
  ,
  /**
   * Operating resource limits hit on accept().
   */
  MHD_SC_ACCEPT_SYSTEM_LIMIT_REACHED = 30060
  ,
  /**
   * Connection was refused by accept policy callback.
   */
  MHD_SC_ACCEPT_POLICY_REJECTED = 30070
  ,
  /**
   * Failed to allocate memory for the daemon resources.
   * TODO: combine similar error codes for daemon
   */
  MHD_SC_DAEMON_MEM_ALLOC_FAILURE = 30081
  ,
  /**
   * We failed to allocate memory for the connection.
   * (May be transient.)
   */
  MHD_SC_CONNECTION_MEM_ALLOC_FAILURE = 30082
  ,
  /**
   * We failed to allocate memory for the connection's memory pool.
   * (May be transient.)
   */
  MHD_SC_POOL_MEM_ALLOC_FAILURE = 30083
  ,
  /**
   * We failed to allocate memory for the HTTP/2 connection's resources.
   * (May be transient.)
   */
  MHD_SC_H2_CONN_MEM_ALLOC_FAILURE = 30084
  ,
  /**
   * We failed to forward data from a Web socket to the
   * application to the remote side due to the socket
   * being closed prematurely. (May be transient.)
   */
  MHD_SC_UPGRADE_FORWARD_INCOMPLETE = 30100
  ,
  /**
   * Failed to allocate memory from our memory pool for processing
   * the request.  Likely the request fields are too large to leave
   * enough room.
   */
  MHD_SC_CONNECTION_POOL_NO_MEM_REQ = 30130
  ,
  /**
   * Failed to allocate memory from our memory pool to store GET parameter.
   * Likely the request URI or header fields are too large to leave enough room.
   */
  MHD_SC_CONNECTION_POOL_NO_MEM_GET_PARAM = 30131
  ,
  /**
   * Failed to allocate memory from our memory pool to store parsed cookie.
   */
  MHD_SC_CONNECTION_POOL_NO_MEM_COOKIE = 30132
  ,
  /**
   * Failed to allocate memory from connection memory pool to store
   * parsed Authentication data.
   */
  MHD_SC_CONNECTION_POOL_NO_MEM_AUTH_DATA = 30133
  ,
  /**
   * Detected jump back of system clock
   */
  MHD_SC_SYS_CLOCK_JUMP_BACK_LARGE = 30140
  ,
  /**
   * Detected correctable jump back of system clock
   */
  MHD_SC_SYS_CLOCK_JUMP_BACK_CORRECTED = 30141
  ,
  /**
   * Timeout waiting for communication operation for HTTP-Upgraded connection
   */
  MHD_SC_UPGRADED_NET_TIMEOUT = 30161
  ,
  /**
   * Not enough system resources
   */
  MHD_SC_NO_SYS_RESOURCES = 30180
  ,

  /* 40000-level errors are caused by the HTTP client or the network. */

  /**
   * MHD is closing a connection because parsing the
   * request failed.
   */
  MHD_SC_CONNECTION_PARSE_FAIL_CLOSED = 40000
  ,
  /**
   * MHD is returning an error because the header provided
   * by the client is too big.
   */
  MHD_SC_CLIENT_HEADER_TOO_BIG = 40020
  ,
  /**
   * An HTTP/1.1 request was sent without the "Host:" header.
   */
  MHD_SC_HOST_HEADER_MISSING = 40060
  ,
  /**
   * Request has more than one "Host:" header.
   */
  MHD_SC_HOST_HEADER_SEVERAL = 40061
  ,
  /**
   * The value of the "Host:" header is invalid.
   */
  MHD_SC_HOST_HEADER_MALFORMED = 40062
  ,
  /**
   * The given content length was not a number.
   */
  MHD_SC_CONTENT_LENGTH_MALFORMED = 40065
  ,
  /**
   * Request has more than one "Content-Length:" header with the same value.
   */
  MHD_SC_CONTENT_LENGTH_SEVERAL_SAME = 40066
  ,
  /**
   * Request has more than one "Content-Length:" header with the different
   * values.
   */
  MHD_SC_CONTENT_LENGTH_SEVERAL_DIFFERENT = 40067
  ,
  /**
   * The BOTH Content-Length and Transfer-Encoding headers are used.
   */
  MHD_SC_CONTENT_LENGTH_AND_TR_ENC = 40068
  ,
  /**
   * The Content-Length is too large to be handled.
   */
  MHD_SC_CONTENT_LENGTH_TOO_LARGE = 40069
  ,
  /**
   * Transfer encoding in request is unsupported or invalid.
   */
  MHD_SC_TRANSFER_ENCODING_UNSUPPORTED = 40075
  ,
  /**
   * "Expect:" value in request is unsupported or invalid.
   */
  MHD_SC_EXPECT_HEADER_VALUE_UNSUPPORTED = 40076
  ,
  /**
   * The given uploaded, chunked-encoded body was malformed.
   */
  MHD_SC_CHUNKED_ENCODING_MALFORMED = 40080
  ,
  /**
   * The first header line has whitespace at the start
   */
  MHD_SC_REQ_FIRST_HEADER_LINE_SPACE_PREFIXED = 40100
  ,
  /**
   * The request target (URI) has whitespace character
   */
  MHD_SC_REQ_TARGET_HAS_WHITESPACE = 40101
  ,
  /**
   * Wrong bare CR characters has been replaced with space.
   */
  MHD_SC_REQ_HEADER_CR_REPLACED = 40120
  ,
  /**
   * Header line has not colon and skipped.
   */
  MHD_SC_REQ_HEADER_LINE_NO_COLON = 40121
  ,
  /**
   * Wrong bare CR characters has been replaced with space.
   */
  MHD_SC_REQ_FOOTER_CR_REPLACED = 40140
  ,
  /**
   * Footer line has not colon and skipped.
   */
  MHD_SC_REQ_FOOTER_LINE_NO_COLON = 40141
  ,
  /**
   * The request is malformed.
   */
  MHD_SC_REQ_MALFORMED = 40155
  ,
  /**
   * The cookie string has been parsed, but it is not fully compliant with
   * specifications
   */
  MHD_SC_REQ_COOKIE_PARSED_NOT_COMPLIANT = 40160
  ,
  /**
   * The cookie string has been parsed only partially
   */
  MHD_SC_REQ_COOKIE_PARSED_PARTIALLY = 40161
  ,
  /**
   * The cookie string is ignored, as it is not fully compliant with
   * specifications
   */
  MHD_SC_REQ_COOKIE_IGNORED_NOT_COMPLIANT = 40162
  ,
  /**
   * The cookie string has been ignored as it is invalid
   */
  MHD_SC_REQ_COOKIE_INVALID = 40163
  ,
  /**
   * The POST data parsed successfully, but has missing or incorrect
   * termination.
   * The last parsed field may have incorrect data.
   */
  MHD_SC_REQ_POST_PARSE_OK_BAD_TERMINATION = 40202
  ,
  /**
   * Parsing of the POST data is incomplete because client used incorrect
   * format of POST encoding.
   * Some POST data is available or has been provided via callback.
   */
  MHD_SC_REQ_POST_PARSE_PARTIAL_INVALID_POST_FORMAT = 40203
  ,
  /**
   * The request does not have "Content-Type:" header and POST data cannot
   * be parsed
   */
  MHD_SC_REQ_POST_PARSE_FAILED_NO_CNTN_TYPE = 40280
  ,
  /**
   * The request has unknown POST encoding specified by "Content-Type:" header
   */
  MHD_SC_REQ_POST_PARSE_FAILED_UNKNOWN_CNTN_TYPE = 40281
  ,
  /**
   * The request has "Content-Type: multipart/form-data" header without
   * "boundary" parameter
   */
  MHD_SC_REQ_POST_PARSE_FAILED_HEADER_NO_BOUNDARY = 40282
  ,
  /**
   * The request has "Content-Type: multipart/form-data" header with misformed
   * data
   */
  MHD_SC_REQ_POST_PARSE_FAILED_HEADER_MISFORMED = 40283
  ,
  /**
   * The POST data cannot be parsed because client used incorrect format
   * of POST encoding.
   */
  MHD_SC_REQ_POST_PARSE_FAILED_INVALID_POST_FORMAT = 40290
  ,
  /**
   * The data in Auth request header has invalid format.
   * For example, for Basic Authentication base64 decoding failed.
   */
  MHD_SC_REQ_AUTH_DATA_BROKEN = 40320
  ,
  /**
   * The request cannot be processed. Sending error reply.
   */
  MHD_SC_REQ_PROCESSING_ERR_REPLY = 41000
  ,
  /**
   * MHD is closing a connection because of timeout.
   */
  MHD_SC_CONNECTION_TIMEOUT = 42000
  ,
  /**
   * MHD is closing a connection because receiving the
   * request failed.
   */
  MHD_SC_CONNECTION_RECV_FAIL_CLOSED = 42020
  ,
  /**
   * MHD is closing a connection because sending the response failed.
   */
  MHD_SC_CONNECTION_SEND_FAIL_CLOSED = 42021
  ,
  /**
   * MHD is closing a connection because remote client shut down its sending
   * side before full request was sent.
   */
  MHD_SC_CLIENT_SHUTDOWN_EARLY = 42040
  ,
  /**
   * MHD is closing a connection because remote client closed connection
   * early.
   */
  MHD_SC_CLIENT_CLOSED_CONN_EARLY = 42041
  ,
  /**
   * MHD is closing a connection connection has been (remotely) aborted.
   */
  MHD_SC_CONNECTION_ABORTED = 42042
  ,
  /**
   * MHD is closing a connection because it was reset.
   */
  MHD_SC_CONNECTION_RESET = 42060
  ,
  /**
   * MHD is closing a connection connection (or connection socket) has
   * been broken.
   */
  MHD_SC_CONNECTION_BROKEN = 42061
  ,
  /**
   * ALPN in TLS connection selected HTTP/2 (as advertised by the client),
   * but the client did not send a valid HTTP/2 connection preface.
   */
  MHD_SC_ALPN_H2_NO_PREFACE = 43001
  ,

  /* 50000-level errors are internal MHD or platform failures,
     not caused by the application (see 60000-level). */
  /* Examples: a socket error on a broken connection, a read failure for
     a file-backed response, an unexpected accept() error. */

  /**
   * This build of MHD does not support TLS, but the application
   * requested TLS.
   */
  MHD_SC_TLS_DISABLED = 50000
  ,
  /**
   * The selected TLS backend does not yet support this operation.
   */
  MHD_SC_TLS_BACKEND_OPERATION_UNSUPPORTED = 50004
  ,
  /**
   * Failed to setup ITC channel.
   */
  MHD_SC_ITC_INITIALIZATION_FAILED = 50005
  ,
  /**
   * File descriptor for ITC cannot be used because the FD number is higher
   * than the limit set by FD_SETSIZE (if internal polling with select is used)
   * or by application.
   */
  MHD_SC_ITC_FD_OUTSIDE_OF_SET_RANGE = 50006
  ,
  /**
   * The specified value for the NC length is way too large
   * for this platform (integer overflow on `size_t`).
   */
  MHD_SC_DIGEST_AUTH_NC_LENGTH_TOO_BIG = 50010
  ,
  /**
   * We failed to allocate memory for the specified nonce
   * counter array.  The option was not set.
   */
  MHD_SC_DIGEST_AUTH_NC_ALLOCATION_FAILURE = 50011
  ,
  /**
   * This build of the library does not support
   * digest authentication.
   */
  MHD_SC_DIGEST_AUTH_NOT_SUPPORTED_BY_BUILD = 50012
  ,
  /**
   * IPv6 requested but not supported by this build.
   * @sa #MHD_SC_AF_NOT_SUPPORTED_BY_BUILD
   */
  MHD_SC_IPV6_NOT_SUPPORTED_BY_BUILD = 50020
  ,
  /**
   * Specified address/protocol family is not supported by this build.
   * @sa MHD_SC_IPV6_NOT_SUPPORTED_BY_BUILD
   */
  MHD_SC_AF_NOT_SUPPORTED_BY_BUILD = 50021
  ,
  /**
   * The requested address/protocol family is rejected by the OS.
   * @sa #MHD_SC_AF_NOT_SUPPORTED_BY_BUILD
   */
  MHD_SC_AF_NOT_AVAILABLE = 50022
  ,
  /**
   * We failed to open the listen socket.
   */
  MHD_SC_FAILED_TO_OPEN_LISTEN_SOCKET = 50040
  ,
  /**
   * Failed to enable listen port reuse.
   */
  MHD_SC_LISTEN_PORT_REUSE_ENABLE_FAILED = 50041
  ,
  /**
   * Failed to enable listen port reuse.
   */
  MHD_SC_LISTEN_PORT_REUSE_ENABLE_NOT_SUPPORTED = 50042
  ,
  /**
   * Failed to enable listen address reuse.
   */
  MHD_SC_LISTEN_ADDRESS_REUSE_ENABLE_FAILED = 50043
  ,
  /**
   * Enabling listen address reuse is not supported by this platform.
   */
  MHD_SC_LISTEN_ADDRESS_REUSE_ENABLE_NOT_SUPPORTED = 50044
  ,
  /**
   * Failed to enable exclusive use of listen address.
   */
  MHD_SC_LISTEN_ADDRESS_EXCLUSIVE_ENABLE_FAILED = 50045
  ,
  /**
   * Dual stack configuration is not possible for provided sockaddr.
   */
  MHD_SC_LISTEN_DUAL_STACK_NOT_SUITABLE = 50046
  ,
  /**
   * Failed to enable or disable dual stack for the IPv6 listen socket.
   * The OS default dual-stack setting is different from what is requested.
   */
  MHD_SC_LISTEN_DUAL_STACK_CONFIGURATION_REJECTED = 50047
  ,
  /**
   * Failed to enable or disable dual stack for the IPv6 listen socket.
   * The socket will be used in whatever the default is the OS uses.
   */
  MHD_SC_LISTEN_DUAL_STACK_CONFIGURATION_UNKNOWN = 50048
  ,
  /**
   * On this platform, MHD does not support explicitly configuring
   * dual stack behaviour.
   */
  MHD_SC_LISTEN_DUAL_STACK_CONFIGURATION_NOT_SUPPORTED = 50049
  ,
  /**
   * Failed to enable TCP FAST OPEN option.
   */
  MHD_SC_LISTEN_FAST_OPEN_FAILURE = 50050
  ,
  /**
   * TCP FAST OPEN is not supported by the platform or by this MHD build.
   */
  MHD_SC_FAST_OPEN_NOT_SUPPORTED = 50051
  ,
  /**
   * We failed to set the listen socket to non-blocking.
   */
  MHD_SC_LISTEN_SOCKET_NONBLOCKING_FAILURE = 50052
  ,
  /**
   * Failed to configure listen socket to be non-inheritable.
   */
  MHD_SC_LISTEN_SOCKET_NOINHERIT_FAILED = 50053
  ,
  /**
   * Listen socket FD cannot be used because the FD number is higher than
   * the limit set by FD_SETSIZE (if internal polling with select is used) or
   * by application.
   */
  MHD_SC_LISTEN_FD_OUTSIDE_OF_SET_RANGE = 50054
  ,
  /**
   * We failed to bind the listen socket.
   */
  MHD_SC_LISTEN_SOCKET_BIND_FAILED = 50055
  ,
  /**
   * Failed to start listening on listen socket.
   */
  MHD_SC_LISTEN_FAILURE = 50056
  ,
  /**
   * Failed to detect the port number on the listening socket
   */
  MHD_SC_LISTEN_PORT_DETECT_FAILURE = 50057
  ,
  /**
   * We failed to create control socket for the epoll().
   */
  MHD_SC_EPOLL_CTL_CREATE_FAILED = 50060
  ,
  /**
   * We failed to configure control socket for the epoll()
   * to be non-inheritable.
   */
  MHD_SC_EPOLL_CTL_CONFIGURE_NOINHERIT_FAILED = 50061
  ,
  /**
   * The epoll() control FD cannot be used because the FD number is higher
   * than the limit set by application.
   */
  MHD_SC_EPOLL_CTL_OUTSIDE_OF_SET_RANGE = 50062
  ,
  /**
   * Failed to allocate memory for daemon's events data, like fd_sets,
   * poll, epoll or kqueue structures.
   */
  MHD_SC_EVENTS_MEMORY_ALLOCATE_FAILURE = 50063
  ,
  /**
   * Failed to add daemon's FDs (ITC and/or listening) to the internal events
   * monitoring
   */
  MHD_SC_EVENTS_REG_DAEMON_FDS_FAILURE = 50065
  ,
  /**
   * Failed to register daemon's FDs (ITC or listening) in the application
   * (external event) monitoring
   */
  MHD_SC_EXT_EVENT_REG_DAEMON_FDS_FAILURE = 50066
  ,
  /**
   * Failed to create kqueue FD
   */
  MHD_SC_KQUEUE_FD_CREATE_FAILED = 50067
  ,
  /**
   * Failed to configure kqueue FD to be non-inheritable.
   */
  MHD_SC_KQUEUE_FD_SET_NOINHERIT_FAILED = 50068
  ,
  /**
   * The kqueue FD cannot be used because the FD number is higher
   * than the limit set by application.
   */
  MHD_SC_KQUEUE_FD_OUTSIDE_OF_SET_RANGE = 50069
  ,
  /**
   * The select() syscall is not available on this platform or in this MHD
   * build.
   */
  MHD_SC_SELECT_SYSCALL_NOT_AVAILABLE = 50070
  ,
  /**
   * The poll() syscall is not available on this platform or in this MHD
   * build.
   */
  MHD_SC_POLL_SYSCALL_NOT_AVAILABLE = 50071
  ,
  /**
   * The epoll syscalls are not available on this platform or in this MHD
   * build.
   */
  MHD_SC_EPOLL_SYSCALL_NOT_AVAILABLE = 50072
  ,
  /**
   * The kqueue syscalls are not available on this platform or in this MHD
   * build.
   */
  MHD_SC_KQUEUE_SYSCALL_NOT_AVAILABLE = 50073
  ,
  /**
   * Failed to obtain our listen port via introspection.
   * FIXME: remove?
   */
  MHD_SC_LISTEN_PORT_INTROSPECTION_FAILURE = 50080
  ,
  /**
   * Failed to obtain our listen port via introspection
   * due to unsupported address family being used.
   */
  MHD_SC_LISTEN_PORT_INTROSPECTION_UNKNOWN_AF = 50081
  ,
  /**
   * Failed to initialise mutex.
   */
  MHD_SC_MUTEX_INIT_FAILURE = 50085
  ,
  /**
   * Failed to allocate memory for the thread pool.
   */
  MHD_SC_THREAD_POOL_MEM_ALLOC_FAILURE = 50090
  ,
  /**
   * We failed to allocate mutex for thread pool worker.
   */
  MHD_SC_THREAD_POOL_CREATE_MUTEX_FAILURE = 50093
  ,
  /**
   * Failed to start the main daemon thread.
   */
  MHD_SC_THREAD_MAIN_LAUNCH_FAILURE = 50095
  ,
  /**
   * Failed to start the daemon thread for listening.
   */
  MHD_SC_THREAD_LISTENING_LAUNCH_FAILURE = 50096
  ,
  /**
   * Failed to start the worker thread for the thread pool.
   */
  MHD_SC_THREAD_WORKER_LAUNCH_FAILURE = 50097
  ,
  /**
   * There was an attempt to upgrade a connection on
   * a daemon where upgrades are disallowed.
   */
  MHD_SC_UPGRADE_ON_DAEMON_WITH_UPGRADE_DISALLOWED = 50100
  ,
  /**
   * Failed to signal via ITC channel.
   */
  MHD_SC_ITC_USE_FAILED = 50101
  ,
  /**
   * Failed to check for the signal on the ITC channel.
   */
  MHD_SC_ITC_CHECK_FAILED = 50102
  ,
  /**
   * System reported error conditions on the ITC FD.
   */
  MHD_SC_ITC_STATUS_ERROR = 50104
  ,
  /**
   * Failed to add a socket to the epoll set.
   */
  MHD_SC_EPOLL_CTL_ADD_FAILED = 50110
  ,
  /**
   * Socket FD cannot be used because the FD number is higher than the limit set
   * by FD_SETSIZE (if internal polling with select is used) or by application.
   */
  MHD_SC_SOCKET_OUTSIDE_OF_SET_RANGE = 50111
  ,
  /**
   * The daemon cannot be started with the specified settings as no space
   * left for the connections sockets within limits set by FD_SETSIZE.
   * Consider use another sockets polling syscall (only select() has such
   * limitations)
   */
  MHD_SC_SYS_FD_SETSIZE_TOO_STRICT = 50112
  ,
  /**
   * This daemon was not configured with options that
   * would allow us to obtain a meaningful timeout.
   */
  MHD_SC_CONFIGURATION_MISMATCH_FOR_GET_TIMEOUT = 50113
  ,
  /**
   * This daemon was not configured with options that
   * would allow us to run with select() data.
   */
  MHD_SC_CONFIGURATION_MISMATCH_FOR_RUN_SELECT = 50114
  ,
  /**
   * This daemon was not configured to run with an
   * external event loop.
   */
  MHD_SC_CONFIGURATION_MISMATCH_FOR_RUN_EXTERNAL = 50115
  ,
  /**
   * Encountered an unexpected error from select()
   * (should never happen).
   */
  MHD_SC_UNEXPECTED_SELECT_ERROR = 50116
  ,
  /**
   * Failed to remove a connection socket to the epoll or kqueue monitoring.
   */
  MHD_SC_EVENTS_CONN_REMOVE_FAILED = 50117
  ,
  /**
   * poll() is not supported.
   */
  MHD_SC_POLL_NOT_SUPPORTED = 50120
  ,
  /**
   * Encountered a (potentially) recoverable error from poll().
   */
  MHD_SC_POLL_SOFT_ERROR = 50121
  ,
  /**
   * Encountered an unrecoverable error from poll().
   */
  MHD_SC_POLL_HARD_ERROR = 50122
  ,
  /**
   * Encountered a (potentially) recoverable error from select().
   */
  MHD_SC_SELECT_SOFT_ERROR = 50123
  ,
  /**
   * Encountered an unrecoverable error from select().
   */
  MHD_SC_SELECT_HARD_ERROR = 50124
  ,
  /**
   * System reported error conditions on the listening socket.
   */
  MHD_SC_LISTEN_STATUS_ERROR = 50129
  ,
  /**
   * Encountered an unrecoverable error from epoll function.
   */
  MHD_SC_EPOLL_HARD_ERROR = 50130
  ,
  /**
   * Encountered an unrecoverable error from kevent() function.
   */
  MHD_SC_KQUEUE_HARD_ERROR = 50131
  ,
  /**
   * We failed to configure accepted socket
   * to not use a SIGPIPE.
   */
  MHD_SC_ACCEPT_CONFIGURE_NOSIGPIPE_FAILED = 50140
  ,
  /**
   * We failed to configure accepted socket
   * to be non-inheritable.
   */
  MHD_SC_ACCEPT_CONFIGURE_NOINHERIT_FAILED = 50141
  ,
  /**
   * We failed to configure accepted socket
   * to be non-blocking.
   */
  MHD_SC_ACCEPT_CONFIGURE_NONBLOCKING_FAILED = 50142
  ,
  /**
   * The accepted socket FD value is too large.
   */
  MHD_SC_ACCEPT_OUTSIDE_OF_SET_RANGE = 50143
  ,
  /**
   * accept() returned unexpected error.
   */
  MHD_SC_ACCEPT_FAILED_UNEXPECTEDLY = 50144
  ,
  /**
   * Operating resource limits hit on accept() while
   * zero connections are active. Oopsie.
   */
  MHD_SC_ACCEPT_SYSTEM_LIMIT_REACHED_INSTANTLY = 50145
  ,
  /**
   * The daemon sockets polling mode requires non-blocking sockets.
   */
  MHD_SC_NONBLOCKING_REQUIRED = 50146
  ,
  /**
   * Encountered an unexpected error from epoll_wait()
   * (should never happen).
   */
  MHD_SC_UNEXPECTED_EPOLL_WAIT_ERROR = 50150
  ,
  /**
   * epoll file descriptor is invalid (strange)
   */
  MHD_SC_EPOLL_FD_INVALID = 50151
  ,
  /**
   * Unexpected socket error (strange)
   */
  MHD_SC_UNEXPECTED_SOCKET_ERROR = 50152
  ,
  /**
   * Failed to add IP address to per-IP counter for
   * some reason.
   */
  MHD_SC_IP_COUNTER_FAILURE = 50160
  ,
  /**
   * Application violated our API by calling shutdown
   * while having an upgrade connection still open.
   */
  MHD_SC_SHUTDOWN_WITH_OPEN_UPGRADED_CONNECTION = 50180
  ,
  /**
   * Due to an unexpected internal error with the
   * state machine, we closed the connection.
   */
  MHD_SC_STATEMACHINE_FAILURE_CONNECTION_CLOSED = 50200
  ,
  /**
   * Failed to allocate memory in connection's pool
   * to parse the cookie header.
   */
  MHD_SC_COOKIE_POOL_ALLOCATION_FAILURE = 50220
  ,
  /**
   * MHD failed to build the reply header.
   */
  MHD_SC_REPLY_HEADER_GENERATION_FAILED = 50230
  ,
  /**
   * Failed to allocate memory in connection's pool for the reply.
   */
  MHD_SC_REPLY_POOL_ALLOCATION_FAILURE = 50231
  ,
  /**
   * Failed to read the file for file-backed response.
   */
  MHD_SC_REPLY_FILE_READ_ERROR = 50232
  ,
  /**
   * Failed to generate the nonce for the Digest Auth.
   */
  MHD_SC_REPLY_NONCE_ERROR = 50233
  ,
  /**
   * Failed to allocate memory in connection's pool for the reply.
   */
  MHD_SC_REPLY_ALLOCATION_FAILED = 50250
  ,
  /**
   * The request POST data cannot be parsed because stream has not enough
   * pool memory free.
   */
  MHD_SC_REQ_POST_PARSE_FAILED_NO_POOL_MEM = 50260
  ,
  /**
   * The POST data cannot be parsed completely because no "large shared buffer"
   * space is available.
   * Some POST data may be parsed.
   */
  MHD_SC_REQ_POST_PARSE_FAILED_NO_LARGE_BUF_MEM = 50261
  ,
  /**
   * The application set POST encoding to "multipart/form-data", but the request
   * has no "Content-Type: multipart/form-data" header which is required
   * to find "boundary" used in this encoding
   */
  MHD_SC_REQ_POST_PARSE_FAILED_HEADER_NOT_MPART = 50284
  ,
  /**
   * The feature is not supported by this MHD build (either
   * disabled by configure parameters or build platform
   * did not support it, because headers are missing or
   * so kernel does not have such feature).
   * The feature will not be enabled if the same MHD binary
   * will be run on another kernel, computer or system
   * configuration.
   */
  MHD_SC_FEATURE_DISABLED = 50300
  ,
  /**
   * The feature is not supported by this platform, while
   * supported by MHD build.
   * The feature can be enabled by changing the kernel or
   * running on another computer or with other system
   * configuration.
   */
  MHD_SC_FEATURE_NOT_AVAILABLE = 50320
  ,
  /**
   * Failed to stop the thread
   */
  MHD_SC_DAEMON_THREAD_STOP_ERROR = 50350
  ,
  /**
   * Unexpected reasons for thread stop
   */
  MHD_SC_DAEMON_THREAD_STOP_UNEXPECTED = 50351
  ,
  /**
   * Daemon system data is broken (like listen socket was unexpectedly closed).
   * The daemon needs to be closed.
   * A new daemon can be started as a replacement after closing the current
   * daemon.
   */
  MHD_SC_DAEMON_SYS_DATA_BROKEN = 50370
  ,
  /**
   * Failed to acquire response mutex lock
   */
  MHD_SC_RESP_MUTEX_LOCK_FAILED = 50500
  ,
  /**
   * Failed to initialise response mutex
   */
  MHD_SC_RESP_MUTEX_INIT_FAILED = 50501
  ,
  /**
   * Unable to allocate memory for the response header
   */
  MHD_SC_RESP_HEADER_MEM_ALLOC_FAILED = 50540
  ,
  /**
   * Failed to switch TCP_NODELAY option for the socket
   */
  MHD_SC_SOCKET_TCP_NODELAY_FAILED = 50600
  ,
  /**
   * Failed to switch TCP_CORK or TCP_NOPUSH option for the socket
   */
  MHD_SC_SOCKET_TCP_CORK_NOPUSH_FAILED = 50601
  ,
  /**
   * Failed to force flush the last part of the response header or
   * the response content
   */
  MHD_SC_SOCKET_FLUSH_LAST_PART_FAILED = 50620
  ,
  /**
   * Failed to push buffered data by zero-sized send()
   */
  MHD_SC_SOCKET_ZERO_SEND_FAILED = 50621
  ,
  /**
   * The HTTP-Upgraded network connection has been closed / disconnected
   */
  MHD_SC_UPGRADED_NET_CONN_CLOSED = 50800
  ,
  /**
   * The HTTP-Upgraded network connection has been broken
   */
  MHD_SC_UPGRADED_NET_CONN_BROKEN = 50801
  ,
  /**
   * The TLS communication error on HTTP-Upgraded connection
   */
  MHD_SC_UPGRADED_TLS_ERROR = 50802
  ,
  /**
   * Unrecoverable sockets communication error on HTTP-Upgraded connection
   */
  MHD_SC_UPGRADED_NET_HARD_ERROR = 50840
  ,
  /**
   * MHD cannot wait for the data on the HTTP-Upgraded connection, because
   * current build or the platform does not support required functionality.
   * Communication with zero timeout is fully supported.
   */
  MHD_SC_UPGRADED_WAITING_NOT_SUPPORTED = 50860
  ,
  /**
   * Global initialisation of MHD library failed
   */
  MHD_SC_LIB_INIT_GLOBAL_FAILED = 51000
  ,
  /**
   * Failed to initialise TLS context for the daemon
   */
  MHD_SC_TLS_DAEMON_INIT_FAILED = 51200
  ,
  /**
   * Failed to initialise TLS context for the new connection
   */
  MHD_SC_TLS_CONNECTION_INIT_FAILED = 51201
  ,
  /**
   * Warning about TLS backend configuration
   */
  MHD_SC_TLS_LIB_CONF_WARNING = 51202
  ,
  /**
   * Failed to perform TLS handshake
   */
  MHD_SC_TLS_CONNECTION_HANDSHAKED_FAILED = 51220
  ,
  /**
   * Hashing failed.
   * Internal hashing function can never fail (and this code is never returned
   * for them). External hashing function (like TLS backend-based) may fail
   * for various reasons, like failure of hardware acccelerated hashing.
   */
  MHD_SC_HASH_FAILED = 51260
  ,
  /**
   * Something wrong in the internal MHD logic.
   * This error should be never returned if MHD works as expected.
   * If this code is ever returned, please report to MHD maintainers.
   */
  MHD_SC_INTERNAL_ERROR = 59900
  ,

  /* 60000-level errors are caused by the application
     (callbacks, settings or API misuse). */

  /**
   * The application called function too early.
   * For example, a header value was requested before the headers
   * had been received.
   */
  MHD_SC_TOO_EARLY = 60000
  ,
  /**
   * The application called this function too late.
   * For example, MHD has already started sending reply.
   */
  MHD_SC_TOO_LATE = 60001
  ,
  /**
   * MHD does not support the requested combination of
   * the sockets polling syscall and the work mode.
   */
  MHD_SC_SYSCALL_WORK_MODE_COMBINATION_INVALID = 60010
  ,
  /**
   * MHD does not support quiescing if ITC was disabled
   * and threads are used.
   */
  MHD_SC_SYSCALL_QUIESCE_REQUIRES_ITC = 60011
  ,
  /**
   * The option provided or function called can be used only with "external
   * events" modes.
   */
  MHD_SC_EXTERNAL_EVENT_ONLY = 60012
  ,
  /**
   * MHD is closing a connection because the application
   * logic to generate the response data failed.
   */
  MHD_SC_APPLICATION_DATA_GENERATION_FAILURE_CLOSED = 60015
  ,
  /**
   * MHD is closing a connection because the application
   * callback told it to do so.
   */
  MHD_SC_APPLICATION_CALLBACK_ABORT_ACTION = 60016
  ,
  /**
   * Application only partially processed upload and did
   * not suspend connection. This may result in a hung
   * connection.
   */
  MHD_SC_APPLICATION_HUNG_CONNECTION = 60017
  ,
  /**
   * Application only partially processed upload and did
   * not suspend connection and the read buffer was maxxed
   * out, so MHD closed the connection.
   */
  MHD_SC_APPLICATION_HUNG_CONNECTION_CLOSED = 60018
  ,
  /**
   * Attempted to set an option that conflicts with another option
   * already set.
   */
  MHD_SC_OPTIONS_CONFLICT = 60020
  ,
  /**
   * Attempted to set an option that not recognised by MHD.
   */
  MHD_SC_OPTION_UNKNOWN = 60021
  ,
  /**
   * Parameter specified unknown work mode.
   */
  MHD_SC_CONFIGURATION_UNEXPECTED_WM = 60022
  ,
  /**
   * Parameter specified unknown Sockets Polling Syscall (SPS).
   */
  MHD_SC_CONFIGURATION_UNEXPECTED_SPS = 60023
  ,
  /**
   * The size of the provided sockaddr does not match address family.
   */
  MHD_SC_CONFIGURATION_WRONG_SA_SIZE = 60024
  ,
  /**
   * The number set by #MHD_D_O_FD_NUMBER_LIMIT is too strict to run
   * the daemon
   */
  MHD_SC_MAX_FD_NUMBER_LIMIT_TOO_STRICT = 60025
  ,
  /**
   * The number set by #MHD_D_O_GLOBAL_CONNECTION_LIMIT is too for the daemon
   * configuration
   */
  MHD_SC_CONFIGURATION_CONN_LIMIT_TOO_SMALL = 60026
  ,
  /**
   * The provided configuration parameter is NULL, but it must be non-NULL
   */
  MHD_SC_CONFIGURATION_PARAM_NULL = 60027
  ,
  /**
   * The size of the provided configuration parameter is too large
   */
  MHD_SC_CONFIGURATION_PARAM_TOO_LARGE = 60028
  ,
  /**
   * The application requested an unsupported TLS backend to be used.
   */
  MHD_SC_TLS_BACKEND_UNSUPPORTED = 60030
  ,
  /**
   * The application attempted to setup TLS parameters before
   * enabling TLS.
   */
  MHD_SC_TLS_BACKEND_UNINITIALIZED = 60031
  ,
  /**
   * The application requested a TLS backend which cannot be used due
   * to missing TLS dynamic library or backend initialisation problem.
   */
  MHD_SC_TLS_BACKEND_UNAVAILABLE = 60032
  ,
  /**
   * Provided TLS certificate and/or private key are incorrect
   */
  MHD_SC_TLS_CONF_BAD_CERT = 60033
  ,
  /**
   * The application requested a daemon setting that cannot be used with
   * selected TLS backend
   */
  MHD_SC_TLS_BACKEND_DAEMON_INCOMPATIBLE_SETTINGS = 60034
  ,
  /**
   * The pointer to the response object is NULL
   */
  MHD_SC_RESP_POINTER_NULL = 60060
  ,
  /**
   * The response HTTP status code is not suitable
   */
  MHD_SC_RESP_HTTP_CODE_NOT_SUITABLE = 60061
  ,
  /**
   * The provided MHD_Action is invalid
   */
  MHD_SC_ACTION_INVALID = 60080
  ,
  /**
   * The provided MHD_UploadAction is invalid
   */
  MHD_SC_UPLOAD_ACTION_INVALID = 60081
  ,
  /**
   * The provided Dynamic Content Creator action is invalid
   */
  MHD_SC_DCC_ACTION_INVALID = 60082
  ,
  /**
   * The response must be empty
   */
  MHD_SC_REPLY_NOT_EMPTY_RESPONSE = 60101
  ,
  /**
   * The "Content-Length" header is not allowed in the reply
   */
  MHD_SC_REPLY_CONTENT_LENGTH_NOT_ALLOWED = 60102
  ,
  /**
   * The provided reply headers do not fit the connection buffer
   */
  MHD_SC_REPLY_HEADERS_TOO_LARGE = 60103
  ,
  /**
   * Specified offset in file-backed response is too large and not supported
   * by the platform
   */
  MHD_SC_REPLY_FILE_OFFSET_TOO_LARGE = 60104
  ,
  /**
   * File-backed response has file smaller than specified combination of
   * the file offset and the response size.
   */
  MHD_SC_REPLY_FILE_TOO_SHORT = 60105
  ,
  /**
   * The new connection cannot be used because the FD number is higher than
   * the limit set by FD_SETSIZE (if internal polling with select is used) or
   * by application.
   */
  MHD_SC_NEW_CONN_FD_OUTSIDE_OF_SET_RANGE = 60140
  ,
  /**
   * The daemon is being destroyed, while not all HTTP-Upgraded connections
   * has been closed.
   */
  MHD_SC_DAEMON_DESTROYED_WITH_UNCLOSED_UPGRADED = 60160
  ,
  /**
   * The provided pointer to 'struct MHD_UpgradedHandle' is invalid
   */
  MHD_SC_UPGRADED_HANDLE_INVALID = 60161
  ,
  /**
   * The provided output buffer is too small.
   */
  MHD_SC_OUT_BUFF_TOO_SMALL = 60180
  ,
  /**
   * The requested type of information is not recognised.
   */
  MHD_SC_INFO_GET_TYPE_UNKNOWN = 60200
  ,
  /**
   * The information of the requested type is too large to fit into
   * the provided buffer.
   */
  MHD_SC_INFO_GET_BUFF_TOO_SMALL = 60201
  ,
  /**
   * The type of the information is not supported by this MHD build.
   * It can be information not supported on the current platform or related
   * to feature disabled for this build.
   */
  MHD_SC_INFO_GET_TYPE_NOT_SUPP_BY_BUILD = 60202
  ,
  /**
   * The type of the information is not available due to configuration
   * or state of the object.
   */
  MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE = 60203
  ,
  /**
   * The type of the information should be available for the object, but
   * cannot be provided due to some error or other reasons.
   */
  MHD_SC_INFO_GET_TYPE_UNOBTAINABLE = 60204
  ,
  /**
   * The type of the Digest Auth algorithm is unknown or not supported.
   */
  MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED = 60240
  ,
  /**
   * The Digest Auth QOP value is unknown or not supported.
   */
  MHD_SC_AUTH_DIGEST_QOP_NOT_SUPPORTED = 60241
  ,
  /**
   * The Digest Auth is not supported due to configuration
   */
  MHD_SC_AUTH_DIGEST_UNSUPPORTED = 60242
  ,
  /**
   * The application failed to register FD for the external events monitoring
   */
  MHD_SC_EXTR_EVENT_REG_FAILED = 60243
  ,
  /**
   * The application failed to de-register FD for the external events monitoring
   */
  MHD_SC_EXTR_EVENT_DEREG_FAILED = 60244
  ,
  /**
   * The application called #MHD_daemon_event_update() with broken data
   */
  MHD_SC_EXTR_EVENT_BROKEN_DATA = 60250
  ,
  /**
   * The application called #MHD_daemon_event_update() with status that
   * has not been requested
   */
  MHD_SC_EXTR_EVENT_UNEXPECTED_STATUS = 60251
  ,
  /**
   * Unable to clear "reusable" flag.
   * Once this flag is set, it cannot be removed for the response lifetime.
   */
  MHD_SC_RESP_REUSABLE_CANNOT_CLEAR = 60300
  ,
  /**
   * The response header name has forbidden characters or token
   */
  MHD_SC_RESP_HEADER_NAME_INVALID = 60320
  ,
  /**
   * The response header value has forbidden characters or token
   */
  MHD_SC_RESP_HEADER_VALUE_INVALID = 60321
  ,
  /**
   * An attempt to add header conflicting with other response header
   */
  MHD_SC_RESP_HEADERS_CONFLICT = 60330
  ,
  /**
   * The application tried to add second DATE header.
   */
  MHD_SC_RESP_HEADER_DATE_DUPLICATE = 60340
  ,
  /**
   * The application tried to add second CONNECTION header.
   */
  MHD_SC_RESP_HEADER_CONNECTION_DUPLICATE = 60341
};

/**
 * Get text description for the MHD error code.
 *
 * This function works for @b MHD error codes, not for @b HTTP status codes.
 * @param code the MHD code to get description for
 * @return the pointer to the text description,
 *         NULL if MHD code in not known.
 *
 * @ingroup general
 */
MHD_EXTERN_ const struct MHD_String *
MHD_status_code_to_string (enum MHD_StatusCode code)
MHD_FN_CONST_;

/**
 * Get the pointer to the C string for the MHD error code, never NULL.
 */
#define MHD_status_code_to_string_lazy(code) \
        (MHD_status_code_to_string ((code)) ? \
         ((MHD_status_code_to_string (code))->cstr) : ("[No code]") )

#ifndef MHD_HTTP_METHOD_DEFINED

/**
 * @brief HTTP request methods
 *
 * @defgroup methods HTTP methods
 *
 * See: https://www.iana.org/assignments/http-methods/http-methods.xml
 * Registry export date: 2023-10-02
 * @{
 */

/**
 * HTTP methods explicitly supported by MHD.  Note that for non-canonical
 * methods, MHD will return #MHD_HTTP_METHOD_OTHER and you can use
 * #MHD_REQUEST_INFO_FIXED_HTTP_METHOD to get the original string.
 *
 * However, applications must check for #MHD_HTTP_METHOD_OTHER *or* any enum-value
 * above those in this list, as future versions of MHD may add additional
 * methods (as per IANA registry), thus even if the API returns
 * #MHD_HTTP_METHOD_OTHER today, it may return a method-specific header in the
 * future!
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_HTTP_Method
{

  /**
   * Method did not match any of the methods given below.
   */
  MHD_HTTP_METHOD_OTHER = 255
  ,
  /* Main HTTP methods. */

  /**
   * "GET"
   * Safe.     Idempotent.     RFC9110, Section 9.3.1.
   */
  MHD_HTTP_METHOD_GET = 1
  ,
  /**
   * "HEAD"
   * Safe.     Idempotent.     RFC9110, Section 9.3.2.
   */
  MHD_HTTP_METHOD_HEAD = 2
  ,
  /**
   * "POST"
   * Not safe. Not idempotent. RFC9110, Section 9.3.3.
   */
  MHD_HTTP_METHOD_POST = 3
  ,
  /**
   * "PUT"
   * Not safe. Idempotent.     RFC9110, Section 9.3.4.
   */
  MHD_HTTP_METHOD_PUT = 4
  ,
  /**
   * "DELETE"
   * Not safe. Idempotent.     RFC9110, Section 9.3.5.
   */
  MHD_HTTP_METHOD_DELETE = 5
  ,
  /**
   * "CONNECT"
   * Not safe. Not idempotent. RFC9110, Section 9.3.6.
   */
  MHD_HTTP_METHOD_CONNECT = 6
  ,
  /**
   * "OPTIONS"
   * Safe.     Idempotent.     RFC9110, Section 9.3.7.
   */
  MHD_HTTP_METHOD_OPTIONS = 7
  ,
  /**
   * "TRACE"
   * Safe.     Idempotent.     RFC9110, Section 9.3.8.
   */
  MHD_HTTP_METHOD_TRACE = 8
  ,
  /**
   * "*"
   * Not safe. Not idempotent. RFC9110, Section 18.2.
   */
  MHD_HTTP_METHOD_ASTERISK = 9
};

#  define MHD_HTTP_METHOD_DEFINED 1
#endif /* ! MHD_HTTP_METHOD_DEFINED */

/**
 * Get text version of the method name.
 * @param method the method to get the text version
 * @return the pointer to the text version,
 *         NULL if method is MHD_HTTP_METHOD_OTHER
 *         or not known.
 */
MHD_EXTERN_ const struct MHD_String *
MHD_http_method_to_string (enum MHD_HTTP_Method method)
MHD_FN_CONST_;


/* Main HTTP methods. */
/* Safe.     Idempotent.     RFC9110, Section 9.3.1. */
#define MHD_HTTP_METHOD_STR_GET      "GET"
/* Safe.     Idempotent.     RFC9110, Section 9.3.2. */
#define MHD_HTTP_METHOD_STR_HEAD     "HEAD"
/* Not safe. Not idempotent. RFC9110, Section 9.3.3. */
#define MHD_HTTP_METHOD_STR_POST     "POST"
/* Not safe. Idempotent.     RFC9110, Section 9.3.4. */
#define MHD_HTTP_METHOD_STR_PUT      "PUT"
/* Not safe. Idempotent.     RFC9110, Section 9.3.5. */
#define MHD_HTTP_METHOD_STR_DELETE   "DELETE"
/* Not safe. Not idempotent. RFC9110, Section 9.3.6. */
#define MHD_HTTP_METHOD_STR_CONNECT  "CONNECT"
/* Safe.     Idempotent.     RFC9110, Section 9.3.7. */
#define MHD_HTTP_METHOD_STR_OPTIONS  "OPTIONS"
/* Safe.     Idempotent.     RFC9110, Section 9.3.8. */
#define MHD_HTTP_METHOD_STR_TRACE    "TRACE"
/* Not safe. Not idempotent. RFC9110, Section 18.2. */
#define MHD_HTTP_METHOD_STR_ASTERISK  "*"

/* Additional HTTP methods. */
/* Not safe. Idempotent.     RFC3744, Section 8.1. */
#define MHD_HTTP_METHOD_STR_ACL            "ACL"
/* Not safe. Idempotent.     RFC3253, Section 12.6. */
#define MHD_HTTP_METHOD_STR_BASELINE_CONTROL "BASELINE-CONTROL"
/* Not safe. Idempotent.     RFC5842, Section 4. */
#define MHD_HTTP_METHOD_STR_BIND           "BIND"
/* Not safe. Idempotent.     RFC3253, Section 4.4, Section 9.4. */
#define MHD_HTTP_METHOD_STR_CHECKIN        "CHECKIN"
/* Not safe. Idempotent.     RFC3253, Section 4.3, Section 8.8. */
#define MHD_HTTP_METHOD_STR_CHECKOUT       "CHECKOUT"
/* Not safe. Idempotent.     RFC4918, Section 9.8. */
#define MHD_HTTP_METHOD_STR_COPY           "COPY"
/* Not safe. Idempotent.     RFC3253, Section 8.2. */
#define MHD_HTTP_METHOD_STR_LABEL          "LABEL"
/* Not safe. Idempotent.     RFC2068, Section 19.6.1.2. */
#define MHD_HTTP_METHOD_STR_LINK           "LINK"
/* Not safe. Not idempotent. RFC4918, Section 9.10. */
#define MHD_HTTP_METHOD_STR_LOCK           "LOCK"
/* Not safe. Idempotent.     RFC3253, Section 11.2. */
#define MHD_HTTP_METHOD_STR_MERGE          "MERGE"
/* Not safe. Idempotent.     RFC3253, Section 13.5. */
#define MHD_HTTP_METHOD_STR_MKACTIVITY     "MKACTIVITY"
/* Not safe. Idempotent.     RFC4791, Section 5.3.1; RFC8144, Section 2.3. */
#define MHD_HTTP_METHOD_STR_MKCALENDAR     "MKCALENDAR"
/* Not safe. Idempotent.     RFC4918, Section 9.3; RFC5689, Section 3; RFC8144, Section 2.3. */
#define MHD_HTTP_METHOD_STR_MKCOL          "MKCOL"
/* Not safe. Idempotent.     RFC4437, Section 6. */
#define MHD_HTTP_METHOD_STR_MKREDIRECTREF  "MKREDIRECTREF"
/* Not safe. Idempotent.     RFC3253, Section 6.3. */
#define MHD_HTTP_METHOD_STR_MKWORKSPACE    "MKWORKSPACE"
/* Not safe. Idempotent.     RFC4918, Section 9.9. */
#define MHD_HTTP_METHOD_STR_MOVE           "MOVE"
/* Not safe. Idempotent.     RFC3648, Section 7. */
#define MHD_HTTP_METHOD_STR_ORDERPATCH     "ORDERPATCH"
/* Not safe. Not idempotent. RFC5789, Section 2. */
#define MHD_HTTP_METHOD_STR_PATCH          "PATCH"
/* Safe.     Idempotent.     RFC9113, Section 3.4. */
#define MHD_HTTP_METHOD_STR_PRI            "PRI"
/* Safe.     Idempotent.     RFC4918, Section 9.1; RFC8144, Section 2.1. */
#define MHD_HTTP_METHOD_STR_PROPFIND       "PROPFIND"
/* Not safe. Idempotent.     RFC4918, Section 9.2; RFC8144, Section 2.2. */
#define MHD_HTTP_METHOD_STR_PROPPATCH      "PROPPATCH"
/* Not safe. Idempotent.     RFC5842, Section 6. */
#define MHD_HTTP_METHOD_STR_REBIND         "REBIND"
/* Safe.     Idempotent.     RFC3253, Section 3.6; RFC8144, Section 2.1. */
#define MHD_HTTP_METHOD_STR_REPORT         "REPORT"
/* Safe.     Idempotent.     RFC5323, Section 2. */
#define MHD_HTTP_METHOD_STR_SEARCH         "SEARCH"
/* Not safe. Idempotent.     RFC5842, Section 5. */
#define MHD_HTTP_METHOD_STR_UNBIND         "UNBIND"
/* Not safe. Idempotent.     RFC3253, Section 4.5. */
#define MHD_HTTP_METHOD_STR_UNCHECKOUT     "UNCHECKOUT"
/* Not safe. Idempotent.     RFC2068, Section 19.6.1.3. */
#define MHD_HTTP_METHOD_STR_UNLINK         "UNLINK"
/* Not safe. Idempotent.     RFC4918, Section 9.11. */
#define MHD_HTTP_METHOD_STR_UNLOCK         "UNLOCK"
/* Not safe. Idempotent.     RFC3253, Section 7.1. */
#define MHD_HTTP_METHOD_STR_UPDATE         "UPDATE"
/* Not safe. Idempotent.     RFC4437, Section 7. */
#define MHD_HTTP_METHOD_STR_UPDATEREDIRECTREF "UPDATEREDIRECTREF"
/* Not safe. Idempotent.     RFC3253, Section 3.5. */
#define MHD_HTTP_METHOD_STR_VERSION_CONTROL "VERSION-CONTROL"

/** @} */ /* end of group methods */

#ifndef MHD_HTTP_POSTENCODING_DEFINED


/**
 * @brief Possible encodings for HTML forms submitted as HTTP POST requests
 *
 * @defgroup postenc HTTP POST encodings
 * See also: https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#form-submission-2
 * @{
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_HTTP_PostEncoding
{
  /**
   * No post encoding / broken data / unknown encoding
   */
  MHD_HTTP_POST_ENCODING_OTHER = 0
  ,
  /**
   * "application/x-www-form-urlencoded"
   * See https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#url-encoded-form-data
   * See https://url.spec.whatwg.org/#application/x-www-form-urlencoded
   * See https://datatracker.ietf.org/doc/html/rfc3986#section-2
   */
  MHD_HTTP_POST_ENCODING_FORM_URLENCODED = 1
  ,
  /**
   * "multipart/form-data"
   * See https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data
   * See https://www.rfc-editor.org/rfc/rfc7578.html
   */
  MHD_HTTP_POST_ENCODING_MULTIPART_FORMDATA = 2
  ,
  /**
   * "text/plain"
   * Introduced by HTML5
   * See https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#plain-text-form-data
   * @warning Format is ambiguous. Do not use unless there is a very strong reason.
   */
  MHD_HTTP_POST_ENCODING_TEXT_PLAIN = 3
};


/** @} */ /* end of group postenc */

#  define MHD_HTTP_POSTENCODING_DEFINED 1
#endif /* ! MHD_HTTP_POSTENCODING_DEFINED */


/**
 * @brief Standard headers found in HTTP requests and responses.
 *
 * See: https://www.iana.org/assignments/http-fields/http-fields.xhtml
 *
 * @defgroup headers HTTP headers
 * Registry export date: 2023-10-02
 * @{
 */

/* Main HTTP headers. */
/* Permanent.     RFC9110, Section 12.5.1: HTTP Semantics */
#define MHD_HTTP_HEADER_ACCEPT       "Accept"
/* Deprecated.    RFC9110, Section 12.5.2: HTTP Semantics */
#define MHD_HTTP_HEADER_ACCEPT_CHARSET "Accept-Charset"
/* Permanent.     RFC9110, Section 12.5.3: HTTP Semantics */
#define MHD_HTTP_HEADER_ACCEPT_ENCODING "Accept-Encoding"
/* Permanent.     RFC9110, Section 12.5.4: HTTP Semantics */
#define MHD_HTTP_HEADER_ACCEPT_LANGUAGE "Accept-Language"
/* Permanent.     RFC9110, Section 14.3: HTTP Semantics */
#define MHD_HTTP_HEADER_ACCEPT_RANGES "Accept-Ranges"
/* Permanent.     RFC9111, Section 5.1: HTTP Caching */
#define MHD_HTTP_HEADER_AGE          "Age"
/* Permanent.     RFC9110, Section 10.2.1: HTTP Semantics */
#define MHD_HTTP_HEADER_ALLOW        "Allow"
/* Permanent.     RFC9110, Section 11.6.3: HTTP Semantics */
#define MHD_HTTP_HEADER_AUTHENTICATION_INFO "Authentication-Info"
/* Permanent.     RFC9110, Section 11.6.2: HTTP Semantics */
#define MHD_HTTP_HEADER_AUTHORIZATION "Authorization"
/* Permanent.     RFC9111, Section 5.2 */
#define MHD_HTTP_HEADER_CACHE_CONTROL "Cache-Control"
/* Permanent.     RFC9112, Section 9.6: HTTP/1.1 */
#define MHD_HTTP_HEADER_CLOSE        "Close"
/* Permanent.     RFC9110, Section 7.6.1: HTTP Semantics */
#define MHD_HTTP_HEADER_CONNECTION   "Connection"
/* Permanent.     RFC9110, Section 8.4: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_ENCODING "Content-Encoding"
/* Permanent.     RFC9110, Section 8.5: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_LANGUAGE "Content-Language"
/* Permanent.     RFC9110, Section 8.6: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_LENGTH "Content-Length"
/* Permanent.     RFC9110, Section 8.7: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_LOCATION "Content-Location"
/* Permanent.     RFC9110, Section 14.4: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_RANGE "Content-Range"
/* Permanent.     RFC9110, Section 8.3: HTTP Semantics */
#define MHD_HTTP_HEADER_CONTENT_TYPE "Content-Type"
/* Permanent.     RFC9110, Section 6.6.1: HTTP Semantics */
#define MHD_HTTP_HEADER_DATE         "Date"
/* Permanent.     RFC9110, Section 8.8.3: HTTP Semantics */
#define MHD_HTTP_HEADER_ETAG         "ETag"
/* Permanent.     RFC9110, Section 10.1.1: HTTP Semantics */
#define MHD_HTTP_HEADER_EXPECT       "Expect"
/* Permanent.     RFC9111, Section 5.3: HTTP Caching */
#define MHD_HTTP_HEADER_EXPIRES      "Expires"
/* Permanent.     RFC9110, Section 10.1.2: HTTP Semantics */
#define MHD_HTTP_HEADER_FROM         "From"
/* Permanent.     RFC9110, Section 7.2: HTTP Semantics */
#define MHD_HTTP_HEADER_HOST         "Host"
/* Permanent.     RFC9110, Section 13.1.1: HTTP Semantics */
#define MHD_HTTP_HEADER_IF_MATCH     "If-Match"
/* Permanent.     RFC9110, Section 13.1.3: HTTP Semantics */
#define MHD_HTTP_HEADER_IF_MODIFIED_SINCE "If-Modified-Since"
/* Permanent.     RFC9110, Section 13.1.2: HTTP Semantics */
#define MHD_HTTP_HEADER_IF_NONE_MATCH "If-None-Match"
/* Permanent.     RFC9110, Section 13.1.5: HTTP Semantics */
#define MHD_HTTP_HEADER_IF_RANGE     "If-Range"
/* Permanent.     RFC9110, Section 13.1.4: HTTP Semantics */
#define MHD_HTTP_HEADER_IF_UNMODIFIED_SINCE "If-Unmodified-Since"
/* Permanent.     RFC9110, Section 8.8.2: HTTP Semantics */
#define MHD_HTTP_HEADER_LAST_MODIFIED "Last-Modified"
/* Permanent.     RFC9110, Section 10.2.2: HTTP Semantics */
#define MHD_HTTP_HEADER_LOCATION     "Location"
/* Permanent.     RFC9110, Section 7.6.2: HTTP Semantics */
#define MHD_HTTP_HEADER_MAX_FORWARDS "Max-Forwards"
/* Permanent.     RFC9112, Appendix B.1: HTTP/1.1 */
#define MHD_HTTP_HEADER_MIME_VERSION "MIME-Version"
/* Deprecated.    RFC9111, Section 5.4: HTTP Caching */
#define MHD_HTTP_HEADER_PRAGMA       "Pragma"
/* Permanent.     RFC9110, Section 11.7.1: HTTP Semantics */
#define MHD_HTTP_HEADER_PROXY_AUTHENTICATE "Proxy-Authenticate"
/* Permanent.     RFC9110, Section 11.7.3: HTTP Semantics */
#define MHD_HTTP_HEADER_PROXY_AUTHENTICATION_INFO "Proxy-Authentication-Info"
/* Permanent.     RFC9110, Section 11.7.2: HTTP Semantics */
#define MHD_HTTP_HEADER_PROXY_AUTHORIZATION "Proxy-Authorization"
/* Permanent.     RFC9110, Section 14.2: HTTP Semantics */
#define MHD_HTTP_HEADER_RANGE        "Range"
/* Permanent.     RFC9110, Section 10.1.3: HTTP Semantics */
#define MHD_HTTP_HEADER_REFERER      "Referer"
/* Permanent.     RFC9110, Section 10.2.3: HTTP Semantics */
#define MHD_HTTP_HEADER_RETRY_AFTER  "Retry-After"
/* Permanent.     RFC9110, Section 10.2.4: HTTP Semantics */
#define MHD_HTTP_HEADER_SERVER       "Server"
/* Permanent.     RFC9110, Section 10.1.4: HTTP Semantics */
#define MHD_HTTP_HEADER_TE           "TE"
/* Permanent.     RFC9110, Section 6.6.2: HTTP Semantics */
#define MHD_HTTP_HEADER_TRAILER      "Trailer"
/* Permanent.     RFC9112, Section 6.1: HTTP Semantics */
#define MHD_HTTP_HEADER_TRANSFER_ENCODING "Transfer-Encoding"
/* Permanent.     RFC9110, Section 7.8: HTTP Semantics */
#define MHD_HTTP_HEADER_UPGRADE      "Upgrade"
/* Permanent.     RFC9110, Section 10.1.5: HTTP Semantics */
#define MHD_HTTP_HEADER_USER_AGENT   "User-Agent"
/* Permanent.     RFC9110, Section 12.5.5: HTTP Semantics */
#define MHD_HTTP_HEADER_VARY         "Vary"
/* Permanent.     RFC9110, Section 7.6.3: HTTP Semantics */
#define MHD_HTTP_HEADER_VIA          "Via"
/* Permanent.     RFC9110, Section 11.6.1: HTTP Semantics */
#define MHD_HTTP_HEADER_WWW_AUTHENTICATE "WWW-Authenticate"
/* Permanent.     RFC9110, Section 12.5.5: HTTP Semantics */
#define MHD_HTTP_HEADER_ASTERISK     "*"

/* Additional HTTP headers. */
/* Permanent.     RFC 3229: Delta encoding in HTTP */
#define MHD_HTTP_HEADER_A_IM         "A-IM"
/* Permanent.     RFC 2324: Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0) */
#define MHD_HTTP_HEADER_ACCEPT_ADDITIONS "Accept-Additions"
/* Permanent.     RFC 8942, Section 3.1: HTTP Client Hints */
#define MHD_HTTP_HEADER_ACCEPT_CH    "Accept-CH"
/* Permanent.     RFC 7089: HTTP Framework for Time-Based Access to Resource States -- Memento */
#define MHD_HTTP_HEADER_ACCEPT_DATETIME "Accept-Datetime"
/* Permanent.     RFC 2295: Transparent Content Negotiation in HTTP */
#define MHD_HTTP_HEADER_ACCEPT_FEATURES "Accept-Features"
/* Permanent.     RFC 5789: PATCH Method for HTTP */
#define MHD_HTTP_HEADER_ACCEPT_PATCH "Accept-Patch"
/* Permanent.     Linked Data Platform 1.0 */
#define MHD_HTTP_HEADER_ACCEPT_POST  "Accept-Post"
/* Permanent.     RFC-ietf-httpbis-message-signatures-19, Section 5.1: HTTP Message Signatures */
#define MHD_HTTP_HEADER_ACCEPT_SIGNATURE "Accept-Signature"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_ALLOW_CREDENTIALS \
        "Access-Control-Allow-Credentials"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_ALLOW_HEADERS \
        "Access-Control-Allow-Headers"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_ALLOW_METHODS \
        "Access-Control-Allow-Methods"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN \
        "Access-Control-Allow-Origin"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_EXPOSE_HEADERS \
        "Access-Control-Expose-Headers"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_MAX_AGE "Access-Control-Max-Age"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_REQUEST_HEADERS \
        "Access-Control-Request-Headers"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_ACCESS_CONTROL_REQUEST_METHOD \
        "Access-Control-Request-Method"
/* Permanent.     RFC 7639, Section 2: The ALPN HTTP Header Field */
#define MHD_HTTP_HEADER_ALPN         "ALPN"
/* Permanent.     RFC 7838: HTTP Alternative Services */
#define MHD_HTTP_HEADER_ALT_SVC      "Alt-Svc"
/* Permanent.     RFC 7838: HTTP Alternative Services */
#define MHD_HTTP_HEADER_ALT_USED     "Alt-Used"
/* Permanent.     RFC 2295: Transparent Content Negotiation in HTTP */
#define MHD_HTTP_HEADER_ALTERNATES   "Alternates"
/* Permanent.     RFC 4437: Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources */
#define MHD_HTTP_HEADER_APPLY_TO_REDIRECT_REF "Apply-To-Redirect-Ref"
/* Permanent.     RFC 8053, Section 4: HTTP Authentication Extensions for Interactive Clients */
#define MHD_HTTP_HEADER_AUTHENTICATION_CONTROL "Authentication-Control"
/* Permanent.     RFC9211: The Cache-Status HTTP Response Header Field */
#define MHD_HTTP_HEADER_CACHE_STATUS "Cache-Status"
/* Permanent.     RFC 8607, Section 5.1: Calendaring Extensions to WebDAV (CalDAV): Managed Attachments */
#define MHD_HTTP_HEADER_CAL_MANAGED_ID "Cal-Managed-ID"
/* Permanent.     RFC 7809, Section 7.1: Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference */
#define MHD_HTTP_HEADER_CALDAV_TIMEZONES "CalDAV-Timezones"
/* Permanent.     RFC9297 */
#define MHD_HTTP_HEADER_CAPSULE_PROTOCOL "Capsule-Protocol"
/* Permanent.     RFC9213: Targeted HTTP Cache Control */
#define MHD_HTTP_HEADER_CDN_CACHE_CONTROL "CDN-Cache-Control"
/* Permanent.     RFC 8586: Loop Detection in Content Delivery Networks (CDNs) */
#define MHD_HTTP_HEADER_CDN_LOOP     "CDN-Loop"
/* Permanent.     RFC 8739, Section 3.3: Support for Short-Term, Automatically Renewed (STAR) Certificates in the Automated Certificate Management Environment (ACME) */
#define MHD_HTTP_HEADER_CERT_NOT_AFTER "Cert-Not-After"
/* Permanent.     RFC 8739, Section 3.3: Support for Short-Term, Automatically Renewed (STAR) Certificates in the Automated Certificate Management Environment (ACME) */
#define MHD_HTTP_HEADER_CERT_NOT_BEFORE "Cert-Not-Before"
/* Permanent.     Clear Site Data */
#define MHD_HTTP_HEADER_CLEAR_SITE_DATA "Clear-Site-Data"
/* Permanent.     RFC9440, Section 2: Client-Cert HTTP Header Field */
#define MHD_HTTP_HEADER_CLIENT_CERT  "Client-Cert"
/* Permanent.     RFC9440, Section 2: Client-Cert HTTP Header Field */
#define MHD_HTTP_HEADER_CLIENT_CERT_CHAIN "Client-Cert-Chain"
/* Permanent.     RFC-ietf-httpbis-digest-headers-13, Section 2: Digest Fields */
#define MHD_HTTP_HEADER_CONTENT_DIGEST "Content-Digest"
/* Permanent.     RFC 6266: Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP) */
#define MHD_HTTP_HEADER_CONTENT_DISPOSITION "Content-Disposition"
/* Permanent.     The HTTP Distribution and Replication Protocol */
#define MHD_HTTP_HEADER_CONTENT_ID   "Content-ID"
/* Permanent.     Content Security Policy Level 3 */
#define MHD_HTTP_HEADER_CONTENT_SECURITY_POLICY "Content-Security-Policy"
/* Permanent.     Content Security Policy Level 3 */
#define MHD_HTTP_HEADER_CONTENT_SECURITY_POLICY_REPORT_ONLY \
        "Content-Security-Policy-Report-Only"
/* Permanent.     RFC 6265: HTTP State Management Mechanism */
#define MHD_HTTP_HEADER_COOKIE       "Cookie"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_CROSS_ORIGIN_EMBEDDER_POLICY \
        "Cross-Origin-Embedder-Policy"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_CROSS_ORIGIN_EMBEDDER_POLICY_REPORT_ONLY \
        "Cross-Origin-Embedder-Policy-Report-Only"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_CROSS_ORIGIN_OPENER_POLICY "Cross-Origin-Opener-Policy"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_CROSS_ORIGIN_OPENER_POLICY_REPORT_ONLY \
        "Cross-Origin-Opener-Policy-Report-Only"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_CROSS_ORIGIN_RESOURCE_POLICY \
        "Cross-Origin-Resource-Policy"
/* Permanent.     RFC 5323: Web Distributed Authoring and Versioning (WebDAV) SEARCH */
#define MHD_HTTP_HEADER_DASL         "DASL"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_DAV          "DAV"
/* Permanent.     RFC 3229: Delta encoding in HTTP */
#define MHD_HTTP_HEADER_DELTA_BASE   "Delta-Base"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_DEPTH        "Depth"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_DESTINATION  "Destination"
/* Permanent.     The HTTP Distribution and Replication Protocol */
#define MHD_HTTP_HEADER_DIFFERENTIAL_ID "Differential-ID"
/* Permanent.     RFC9449: OAuth 2.0 Demonstrating Proof of Possession (DPoP) */
#define MHD_HTTP_HEADER_DPOP         "DPoP"
/* Permanent.     RFC9449: OAuth 2.0 Demonstrating Proof of Possession (DPoP) */
#define MHD_HTTP_HEADER_DPOP_NONCE   "DPoP-Nonce"
/* Permanent.     RFC 8470: Using Early Data in HTTP */
#define MHD_HTTP_HEADER_EARLY_DATA   "Early-Data"
/* Permanent.     RFC9163: Expect-CT Extension for HTTP */
#define MHD_HTTP_HEADER_EXPECT_CT    "Expect-CT"
/* Permanent.     RFC 7239: Forwarded HTTP Extension */
#define MHD_HTTP_HEADER_FORWARDED    "Forwarded"
/* Permanent.     RFC 7486, Section 6.1.1: HTTP Origin-Bound Authentication (HOBA) */
#define MHD_HTTP_HEADER_HOBAREG      "Hobareg"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_IF           "If"
/* Permanent.      RFC 6338: Scheduling Extensions to CalDAV */
#define MHD_HTTP_HEADER_IF_SCHEDULE_TAG_MATCH "If-Schedule-Tag-Match"
/* Permanent.     RFC 3229: Delta encoding in HTTP */
#define MHD_HTTP_HEADER_IM           "IM"
/* Permanent.     RFC 8473: Token Binding over HTTP */
#define MHD_HTTP_HEADER_INCLUDE_REFERRED_TOKEN_BINDING_ID \
        "Include-Referred-Token-Binding-ID"
/* Permanent.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_KEEP_ALIVE   "Keep-Alive"
/* Permanent.     RFC 3253: Versioning Extensions to WebDAV: (Web Distributed Authoring and Versioning) */
#define MHD_HTTP_HEADER_LABEL        "Label"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_LAST_EVENT_ID "Last-Event-ID"
/* Permanent.     RFC 8288: Web Linking */
#define MHD_HTTP_HEADER_LINK         "Link"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_LOCK_TOKEN   "Lock-Token"
/* Permanent.     RFC 7089: HTTP Framework for Time-Based Access to Resource States -- Memento */
#define MHD_HTTP_HEADER_MEMENTO_DATETIME "Memento-Datetime"
/* Permanent.     RFC 2227: Simple Hit-Metering and Usage-Limiting for HTTP */
#define MHD_HTTP_HEADER_METER        "Meter"
/* Permanent.     RFC 2295: Transparent Content Negotiation in HTTP */
#define MHD_HTTP_HEADER_NEGOTIATE    "Negotiate"
/* Permanent.     Network Error Logging */
#define MHD_HTTP_HEADER_NEL          "NEL"
/* Permanent.     OData Version 4.01 Part 1: Protocol; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_ODATA_ENTITYID "OData-EntityId"
/* Permanent.     OData Version 4.01 Part 1: Protocol; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_ODATA_ISOLATION "OData-Isolation"
/* Permanent.     OData Version 4.01 Part 1: Protocol; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_ODATA_MAXVERSION "OData-MaxVersion"
/* Permanent.     OData Version 4.01 Part 1: Protocol; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_ODATA_VERSION "OData-Version"
/* Permanent.     RFC 8053, Section 3: HTTP Authentication Extensions for Interactive Clients */
#define MHD_HTTP_HEADER_OPTIONAL_WWW_AUTHENTICATE "Optional-WWW-Authenticate"
/* Permanent.     RFC 3648: Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol */
#define MHD_HTTP_HEADER_ORDERING_TYPE "Ordering-Type"
/* Permanent.     RFC 6454: The Web Origin Concept */
#define MHD_HTTP_HEADER_ORIGIN       "Origin"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_ORIGIN_AGENT_CLUSTER "Origin-Agent-Cluster"
/* Permanent.     RFC 8613, Section 11.1: Object Security for Constrained RESTful Environments (OSCORE) */
#define MHD_HTTP_HEADER_OSCORE       "OSCORE"
/* Permanent.     OASIS Project Specification 01; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_OSLC_CORE_VERSION "OSLC-Core-Version"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_OVERWRITE    "Overwrite"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_PING_FROM    "Ping-From"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_PING_TO      "Ping-To"
/* Permanent.     RFC 3648: Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol */
#define MHD_HTTP_HEADER_POSITION     "Position"
/* Permanent.     RFC 7240: Prefer Header for HTTP */
#define MHD_HTTP_HEADER_PREFER       "Prefer"
/* Permanent.     RFC 7240: Prefer Header for HTTP */
#define MHD_HTTP_HEADER_PREFERENCE_APPLIED "Preference-Applied"
/* Permanent.     RFC9218: Extensible Prioritization Scheme for HTTP */
#define MHD_HTTP_HEADER_PRIORITY     "Priority"
/* Permanent.     RFC9209: The Proxy-Status HTTP Response Header Field */
#define MHD_HTTP_HEADER_PROXY_STATUS "Proxy-Status"
/* Permanent.     RFC 7469: Public Key Pinning Extension for HTTP */
#define MHD_HTTP_HEADER_PUBLIC_KEY_PINS "Public-Key-Pins"
/* Permanent.     RFC 7469: Public Key Pinning Extension for HTTP */
#define MHD_HTTP_HEADER_PUBLIC_KEY_PINS_REPORT_ONLY \
        "Public-Key-Pins-Report-Only"
/* Permanent.     RFC 4437: Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources */
#define MHD_HTTP_HEADER_REDIRECT_REF "Redirect-Ref"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_REFRESH      "Refresh"
/* Permanent.     RFC 8555, Section 6.5.1: Automatic Certificate Management Environment (ACME) */
#define MHD_HTTP_HEADER_REPLAY_NONCE "Replay-Nonce"
/* Permanent.     RFC-ietf-httpbis-digest-headers-13, Section 3: Digest Fields */
#define MHD_HTTP_HEADER_REPR_DIGEST  "Repr-Digest"
/* Permanent.     RFC 6638: Scheduling Extensions to CalDAV */
#define MHD_HTTP_HEADER_SCHEDULE_REPLY "Schedule-Reply"
/* Permanent.     RFC 6338: Scheduling Extensions to CalDAV */
#define MHD_HTTP_HEADER_SCHEDULE_TAG "Schedule-Tag"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_SEC_PURPOSE  "Sec-Purpose"
/* Permanent.     RFC 8473: Token Binding over HTTP */
#define MHD_HTTP_HEADER_SEC_TOKEN_BINDING "Sec-Token-Binding"
/* Permanent.     RFC 6455: The WebSocket Protocol */
#define MHD_HTTP_HEADER_SEC_WEBSOCKET_ACCEPT "Sec-WebSocket-Accept"
/* Permanent.     RFC 6455: The WebSocket Protocol */
#define MHD_HTTP_HEADER_SEC_WEBSOCKET_EXTENSIONS "Sec-WebSocket-Extensions"
/* Permanent.     RFC 6455: The WebSocket Protocol */
#define MHD_HTTP_HEADER_SEC_WEBSOCKET_KEY "Sec-WebSocket-Key"
/* Permanent.     RFC 6455: The WebSocket Protocol */
#define MHD_HTTP_HEADER_SEC_WEBSOCKET_PROTOCOL "Sec-WebSocket-Protocol"
/* Permanent.     RFC 6455: The WebSocket Protocol */
#define MHD_HTTP_HEADER_SEC_WEBSOCKET_VERSION "Sec-WebSocket-Version"
/* Permanent.     Server Timing */
#define MHD_HTTP_HEADER_SERVER_TIMING "Server-Timing"
/* Permanent.     RFC 6265: HTTP State Management Mechanism */
#define MHD_HTTP_HEADER_SET_COOKIE   "Set-Cookie"
/* Permanent.     RFC-ietf-httpbis-message-signatures-19, Section 4.2: HTTP Message Signatures */
#define MHD_HTTP_HEADER_SIGNATURE    "Signature"
/* Permanent.     RFC-ietf-httpbis-message-signatures-19, Section 4.1: HTTP Message Signatures */
#define MHD_HTTP_HEADER_SIGNATURE_INPUT "Signature-Input"
/* Permanent.     RFC 5023: The Atom Publishing Protocol */
#define MHD_HTTP_HEADER_SLUG         "SLUG"
/* Permanent.     Simple Object Access Protocol (SOAP) 1.1 */
#define MHD_HTTP_HEADER_SOAPACTION   "SoapAction"
/* Permanent.     RFC 2518: HTTP Extensions for Distributed Authoring -- WEBDAV */
#define MHD_HTTP_HEADER_STATUS_URI   "Status-URI"
/* Permanent.     RFC 6797: HTTP Strict Transport Security (HSTS) */
#define MHD_HTTP_HEADER_STRICT_TRANSPORT_SECURITY "Strict-Transport-Security"
/* Permanent.     RFC 8594: The Sunset HTTP Header Field */
#define MHD_HTTP_HEADER_SUNSET       "Sunset"
/* Permanent.     Edge Architecture Specification */
#define MHD_HTTP_HEADER_SURROGATE_CAPABILITY "Surrogate-Capability"
/* Permanent.     Edge Architecture Specification */
#define MHD_HTTP_HEADER_SURROGATE_CONTROL "Surrogate-Control"
/* Permanent.     RFC 2295: Transparent Content Negotiation in HTTP */
#define MHD_HTTP_HEADER_TCN          "TCN"
/* Permanent.     RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) */
#define MHD_HTTP_HEADER_TIMEOUT      "Timeout"
/* Permanent.     RFC 8030, Section 5.4: Generic Event Delivery Using HTTP Push */
#define MHD_HTTP_HEADER_TOPIC        "Topic"
/* Permanent.     Trace Context */
#define MHD_HTTP_HEADER_TRACEPARENT  "Traceparent"
/* Permanent.     Trace Context */
#define MHD_HTTP_HEADER_TRACESTATE   "Tracestate"
/* Permanent.     RFC 8030, Section 5.2: Generic Event Delivery Using HTTP Push */
#define MHD_HTTP_HEADER_TTL          "TTL"
/* Permanent.     RFC 8030, Section 5.3: Generic Event Delivery Using HTTP Push */
#define MHD_HTTP_HEADER_URGENCY      "Urgency"
/* Permanent.     RFC 2295: Transparent Content Negotiation in HTTP */
#define MHD_HTTP_HEADER_VARIANT_VARY "Variant-Vary"
/* Permanent.     RFC-ietf-httpbis-digest-headers-13, Section 4: Digest Fields */
#define MHD_HTTP_HEADER_WANT_CONTENT_DIGEST "Want-Content-Digest"
/* Permanent.     RFC-ietf-httpbis-digest-headers-13, Section 4: Digest Fields */
#define MHD_HTTP_HEADER_WANT_REPR_DIGEST "Want-Repr-Digest"
/* Permanent.     Fetch */
#define MHD_HTTP_HEADER_X_CONTENT_TYPE_OPTIONS "X-Content-Type-Options"
/* Permanent.     HTML */
#define MHD_HTTP_HEADER_X_FRAME_OPTIONS "X-Frame-Options"
/* Provisional.   AMP-Cache-Transform HTTP request header */
#define MHD_HTTP_HEADER_AMP_CACHE_TRANSFORM "AMP-Cache-Transform"
/* Provisional.   OSLC Configuration Management Version 1.0. Part 3: Configuration Specification */
#define MHD_HTTP_HEADER_CONFIGURATION_CONTEXT "Configuration-Context"
/* Provisional.   RFC 6017: Electronic Data Interchange - Internet Integration (EDIINT) Features Header Field */
#define MHD_HTTP_HEADER_EDIINT_FEATURES "EDIINT-Features"
/* Provisional.   OData Version 4.01 Part 1: Protocol; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_ISOLATION    "Isolation"
/* Provisional.   Permissions Policy */
#define MHD_HTTP_HEADER_PERMISSIONS_POLICY "Permissions-Policy"
/* Provisional.   Repeatable Requests Version 1.0; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_REPEATABILITY_CLIENT_ID "Repeatability-Client-ID"
/* Provisional.   Repeatable Requests Version 1.0; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_REPEATABILITY_FIRST_SENT "Repeatability-First-Sent"
/* Provisional.   Repeatable Requests Version 1.0; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_REPEATABILITY_REQUEST_ID "Repeatability-Request-ID"
/* Provisional.   Repeatable Requests Version 1.0; OASIS; Chet_Ensign */
#define MHD_HTTP_HEADER_REPEATABILITY_RESULT "Repeatability-Result"
/* Provisional.   Reporting API */
#define MHD_HTTP_HEADER_REPORTING_ENDPOINTS "Reporting-Endpoints"
/* Provisional.   Global Privacy Control (GPC) */
#define MHD_HTTP_HEADER_SEC_GPC      "Sec-GPC"
/* Provisional.   Resource Timing Level 1 */
#define MHD_HTTP_HEADER_TIMING_ALLOW_ORIGIN "Timing-Allow-Origin"
/* Deprecated.    PEP - an Extension Mechanism for HTTP; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_C_PEP_INFO   "C-PEP-Info"
/* Deprecated.    White Paper: Joint Electronic Payment Initiative */
#define MHD_HTTP_HEADER_PROTOCOL_INFO "Protocol-Info"
/* Deprecated.    White Paper: Joint Electronic Payment Initiative */
#define MHD_HTTP_HEADER_PROTOCOL_QUERY "Protocol-Query"
/* Obsoleted.     Access Control for Cross-site Requests */
#define MHD_HTTP_HEADER_ACCESS_CONTROL "Access-Control"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_C_EXT        "C-Ext"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_C_MAN        "C-Man"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_C_OPT        "C-Opt"
/* Obsoleted.     PEP - an Extension Mechanism for HTTP; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_C_PEP        "C-PEP"
/* Obsoleted.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1; RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_CONTENT_BASE "Content-Base"
/* Obsoleted.     RFC 2616, Section 14.15: Hypertext Transfer Protocol -- HTTP/1.1; RFC 7231, Appendix B: Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content */
#define MHD_HTTP_HEADER_CONTENT_MD5  "Content-MD5"
/* Obsoleted.     HTML 4.01 Specification */
#define MHD_HTTP_HEADER_CONTENT_SCRIPT_TYPE "Content-Script-Type"
/* Obsoleted.     HTML 4.01 Specification */
#define MHD_HTTP_HEADER_CONTENT_STYLE_TYPE "Content-Style-Type"
/* Obsoleted.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_CONTENT_VERSION "Content-Version"
/* Obsoleted.     RFC 2965: HTTP State Management Mechanism; RFC 6265: HTTP State Management Mechanism */
#define MHD_HTTP_HEADER_COOKIE2      "Cookie2"
/* Obsoleted.     HTML 4.01 Specification */
#define MHD_HTTP_HEADER_DEFAULT_STYLE "Default-Style"
/* Obsoleted.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_DERIVED_FROM "Derived-From"
/* Obsoleted.     RFC 3230: Instance Digests in HTTP; RFC-ietf-httpbis-digest-headers-13, Section 1.3: Digest Fields */
#define MHD_HTTP_HEADER_DIGEST       "Digest"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_EXT          "Ext"
/* Obsoleted.     Implementation of OPS Over HTTP */
#define MHD_HTTP_HEADER_GETPROFILE   "GetProfile"
/* Obsoleted.     RFC 7540, Section 3.2.1: Hypertext Transfer Protocol Version 2 (HTTP/2) */
#define MHD_HTTP_HEADER_HTTP2_SETTINGS "HTTP2-Settings"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_MAN          "Man"
/* Obsoleted.     Access Control for Cross-site Requests */
#define MHD_HTTP_HEADER_METHOD_CHECK "Method-Check"
/* Obsoleted.     Access Control for Cross-site Requests */
#define MHD_HTTP_HEADER_METHOD_CHECK_EXPIRES "Method-Check-Expires"
/* Obsoleted.     RFC 2774: An HTTP Extension Framework; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_OPT          "Opt"
/* Obsoleted.     The Platform for Privacy Preferences 1.0 (P3P1.0) Specification */
#define MHD_HTTP_HEADER_P3P          "P3P"
/* Obsoleted.     PEP - an Extension Mechanism for HTTP */
#define MHD_HTTP_HEADER_PEP          "PEP"
/* Obsoleted.     PEP - an Extension Mechanism for HTTP */
#define MHD_HTTP_HEADER_PEP_INFO     "Pep-Info"
/* Obsoleted.     PICS Label Distribution Label Syntax and Communication Protocols */
#define MHD_HTTP_HEADER_PICS_LABEL   "PICS-Label"
/* Obsoleted.     Implementation of OPS Over HTTP */
#define MHD_HTTP_HEADER_PROFILEOBJECT "ProfileObject"
/* Obsoleted.     PICS Label Distribution Label Syntax and Communication Protocols */
#define MHD_HTTP_HEADER_PROTOCOL     "Protocol"
/* Obsoleted.     PICS Label Distribution Label Syntax and Communication Protocols */
#define MHD_HTTP_HEADER_PROTOCOL_REQUEST "Protocol-Request"
/* Obsoleted.     Notification for Proxy Caches */
#define MHD_HTTP_HEADER_PROXY_FEATURES "Proxy-Features"
/* Obsoleted.     Notification for Proxy Caches */
#define MHD_HTTP_HEADER_PROXY_INSTRUCTION "Proxy-Instruction"
/* Obsoleted.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_PUBLIC       "Public"
/* Obsoleted.     Access Control for Cross-site Requests */
#define MHD_HTTP_HEADER_REFERER_ROOT "Referer-Root"
/* Obsoleted.     RFC 2310: The Safe Response Header Field; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_SAFE         "Safe"
/* Obsoleted.     RFC 2660: The Secure HyperText Transfer Protocol; status-change-http-experiments-to-historic */
#define MHD_HTTP_HEADER_SECURITY_SCHEME "Security-Scheme"
/* Obsoleted.     RFC 2965: HTTP State Management Mechanism; RFC 6265: HTTP State Management Mechanism */
#define MHD_HTTP_HEADER_SET_COOKIE2  "Set-Cookie2"
/* Obsoleted.     Implementation of OPS Over HTTP */
#define MHD_HTTP_HEADER_SETPROFILE   "SetProfile"
/* Obsoleted.     RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1 */
#define MHD_HTTP_HEADER_URI          "URI"
/* Obsoleted.     RFC 3230: Instance Digests in HTTP; RFC-ietf-httpbis-digest-headers-13, Section 1.3: Digest Fields */
#define MHD_HTTP_HEADER_WANT_DIGEST  "Want-Digest"
/* Obsoleted.     RFC9111, Section 5.5: HTTP Caching */
#define MHD_HTTP_HEADER_WARNING      "Warning"

/* Headers removed from the registry. Do not use! */
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_COMPLIANCE   "Compliance"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_CONTENT_TRANSFER_ENCODING "Content-Transfer-Encoding"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_COST         "Cost"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_MESSAGE_ID   "Message-ID"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_NON_COMPLIANCE "Non-Compliance"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_OPTIONAL     "Optional"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_RESOLUTION_HINT "Resolution-Hint"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_RESOLVER_LOCATION "Resolver-Location"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_SUBOK        "SubOK"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_SUBST        "Subst"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_TITLE        "Title"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_UA_COLOR     "UA-Color"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_UA_MEDIA     "UA-Media"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_UA_PIXELS    "UA-Pixels"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_UA_RESOLUTION "UA-Resolution"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_UA_WINDOWPIXELS "UA-Windowpixels"
/* Obsoleted.     RFC4229 */
#define MHD_HTTP_HEADER_VERSION      "Version"
/* Obsoleted.     W3C Mobile Web Best Practices Working Group */
#define MHD_HTTP_HEADER_X_DEVICE_ACCEPT "X-Device-Accept"
/* Obsoleted.     W3C Mobile Web Best Practices Working Group */
#define MHD_HTTP_HEADER_X_DEVICE_ACCEPT_CHARSET "X-Device-Accept-Charset"
/* Obsoleted.     W3C Mobile Web Best Practices Working Group */
#define MHD_HTTP_HEADER_X_DEVICE_ACCEPT_ENCODING "X-Device-Accept-Encoding"
/* Obsoleted.     W3C Mobile Web Best Practices Working Group */
#define MHD_HTTP_HEADER_X_DEVICE_ACCEPT_LANGUAGE "X-Device-Accept-Language"
/* Obsoleted.     W3C Mobile Web Best Practices Working Group */
#define MHD_HTTP_HEADER_X_DEVICE_USER_AGENT "X-Device-User-Agent"


/**
 * Predefined list of headers
 * To be filled with HPACK static data
 */
enum MHD_PredefinedHeader
{
  MHD_PREDEF_ACCEPT_CHARSET = 15,
  MHD_PREDEF_ACCEPT_LANGUAGE = 17
};


/** @} */ /* end of group headers */

/**
 * A client has requested the given url using the given method
 * (#MHD_HTTP_METHOD_GET, #MHD_HTTP_METHOD_PUT,
 * #MHD_HTTP_METHOD_DELETE, #MHD_HTTP_METHOD_POST, etc).
 * If @a upload_size is not zero and response action is provided by this
 * callback, then upload will be discarded and the stream (the connection for
 * HTTP/1.1) will be closed after sending the response.
 *
 * @param cls argument given together with the function
 *        pointer when the handler was registered with MHD
 * @param request the request object
 * @param path the requested uri (without arguments after "?")
 * @param method the HTTP method used (#MHD_HTTP_METHOD_GET,
 *        #MHD_HTTP_METHOD_PUT, etc.)
 * @param upload_size the size of the message upload content payload,
 *                    #MHD_SIZE_UNKNOWN for chunked uploads (if the
 *                    final chunk has not been processed yet)
 * @return action how to proceed, NULL
 *         if the request must be aborted due to a serious
 *         error while handling the request (implies closure
 *         of underling data stream, for HTTP/1.1 it means
 *         socket closure).
 */
typedef const struct MHD_Action *
(MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_NONNULL_ (3)
 *MHD_RequestCallback)(void *cls,
                       struct MHD_Request *MHD_RESTRICT request,
                       const struct MHD_String *MHD_RESTRICT path,
                       enum MHD_HTTP_Method method,
                       uint_fast64_t upload_size);


/**
 * Create (but do not yet start) an MHD daemon.
 * Usually, various options are set before
 * starting the daemon with #MHD_daemon_start().
 *
 * @param req_cb the function to be called for incoming requests
 * @param req_cb_cls the closure for @a cb
 * @return the pointer to the new object on success,
 *         NULL on error (like out-of-memory)
 */
MHD_EXTERN_ struct MHD_Daemon *
MHD_daemon_create (MHD_RequestCallback req_cb,
                   void *req_cb_cls)
MHD_FN_MUST_CHECK_RESULT_;


/**
 * Start a webserver.
 * This function:
 * + checks the combination of set options,
 * + initialises the TLS library (if TLS is requested),
 * + creates the listen socket (if not provided and if allowed),
 * + starts the daemon internal threads (if allowed)
 *
 * @param[in,out] daemon daemon to start; you can no longer set
 *        options on this daemon after this call!
 * @return #MHD_SC_OK on success
 * @ingroup daemon
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_start (struct MHD_Daemon *daemon)
MHD_FN_PAR_NONNULL_ (1) MHD_FN_MUST_CHECK_RESULT_;


/**
 * Stop accepting connections from the listening socket.  Allows
 * clients to continue processing, but stops accepting new
 * connections.  Note that the caller is responsible for closing the
 * returned socket; however, if MHD is run using threads (anything but
 * external select mode), it must not be closed until AFTER
 * #MHD_daemon_destroy() has been called (as it is theoretically possible
 * that an existing thread is still using it).
 *
 * @param[in,out] daemon the daemon to stop accepting new connections for
 * @return the old listen socket on success, #MHD_INVALID_SOCKET if
 *         the daemon was already not listening anymore, or
 *         was never started, or has no listen socket.
 * @ingroup daemon
 */
MHD_EXTERN_ MHD_Socket
MHD_daemon_quiesce (struct MHD_Daemon *daemon)
MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_INOUT_ (1);


/**
 * Shutdown and destroy an HTTP daemon.
 *
 * @param[in] daemon daemon to stop
 * @ingroup daemon
 */
MHD_EXTERN_ void
MHD_daemon_destroy (struct MHD_Daemon *daemon)
MHD_FN_PAR_NONNULL_ALL_;

/* ******************* External event loop ************************ */

/**
 * @defgroup event External network events processing
 */

/**
 * The network status of the socket.
 * When set by MHD (by #MHD_SocketRegistrationUpdateCallback or
 * similar) it indicates a request to watch for specific socket state:
 * watch for readiness for receiving the data, watch for readiness for sending
 * the data and/or watch for exception state of the socket.
 * When set by application (and provided for #MHD_daemon_event_update() and
 * similar) it must indicate the actual status of the socket.
 *
 * Any actual state is a bitwise OR combination of #MHD_FD_STATE_RECV,
 * #MHD_FD_STATE_SEND, #MHD_FD_STATE_EXCEPT.
 * @ingroup event
 */
enum MHD_FIXED_ENUM_ MHD_FdState
{
  /**
   * The socket is not ready for receiving or sending and
   * does not have any exceptional state.
   * The state never set by MHD, except de-registration of the sockets
   * in a #MHD_SocketRegistrationUpdateCallback.
   */
  MHD_FD_STATE_NONE = 0
  ,
  /* ** Three bit-flags ** */

  /**
   * Indicates that socket should be watched for incoming data
   * (when set by #MHD_SocketRegistrationUpdateCallback)
   * / socket has incoming data ready to read (when used for
   * #MHD_daemon_event_update())
   */
  MHD_FD_STATE_RECV = 1 << 0
  ,
  /**
   * Indicates that socket should be watched for availability for sending
   * (when set by #MHD_SocketRegistrationUpdateCallback)
   * / socket has ability to send data (when used for
   * #MHD_daemon_event_update())
   */
  MHD_FD_STATE_SEND = 1 << 1
  ,
  /**
   * Indicates that socket should be watched for disconnect, out-of-band
   * data available or high priority data available (when set by
   * #MHD_SocketRegistrationUpdateCallback)
   * / socket has been disconnected, has out-of-band data available or
   * has high priority data available (when used for
   * #MHD_daemon_event_update()). This status must not include "remote
   * peer shut down writing" status.
   * Note: #MHD_SocketRegistrationUpdateCallback() always set it as exceptions
   * must be always watched.
   */
  MHD_FD_STATE_EXCEPT = 1 << 2
  ,

  /* The rest of the list is a bit-wise combination of three main
   * states. Application may use three main states directly as
   * a bit-mask instead of using of the following values
   */

  /**
   * Combination of #MHD_FD_STATE_RECV and #MHD_FD_STATE_SEND states.
   */
  MHD_FD_STATE_RECV_SEND = MHD_FD_STATE_RECV | MHD_FD_STATE_SEND
  ,
  /**
   * Combination of #MHD_FD_STATE_RECV and #MHD_FD_STATE_EXCEPT states.
   */
  MHD_FD_STATE_RECV_EXCEPT = MHD_FD_STATE_RECV | MHD_FD_STATE_EXCEPT
  ,
  /**
   * Combination of #MHD_FD_STATE_RECV and #MHD_FD_STATE_EXCEPT states.
   */
  MHD_FD_STATE_SEND_EXCEPT = MHD_FD_STATE_RECV | MHD_FD_STATE_EXCEPT
  ,
  /**
   * Combination of #MHD_FD_STATE_RECV, #MHD_FD_STATE_SEND and
   * #MHD_FD_STATE_EXCEPT states.
   */
  MHD_FD_STATE_RECV_SEND_EXCEPT = \
    MHD_FD_STATE_RECV | MHD_FD_STATE_SEND | MHD_FD_STATE_EXCEPT
};

/**
 * Checks whether specific @a state is enabled/set in the @a var
 */
#define MHD_FD_STATE_IS_SET(var, state)              \
        (MHD_FD_STATE_NONE !=                        \
         ((enum MHD_FdState) (((unsigned int) (var)) \
                              & ((unsigned int) (state)))))

/**
 * Checks whether RECV is enabled/set in the @a var
 */
#define MHD_FD_STATE_IS_SET_RECV(var) \
        MHD_FD_STATE_IS_SET ((var),MHD_FD_STATE_RECV)
/**
 * Checks whether SEND is enabled/set in the @a var
 */
#define MHD_FD_STATE_IS_SET_SEND(var) \
        MHD_FD_STATE_IS_SET ((var),MHD_FD_STATE_SEND)
/**
 * Checks whether EXCEPT is enabled/set in the @a var
 */
#define MHD_FD_STATE_IS_SET_EXCEPT(var) \
        MHD_FD_STATE_IS_SET ((var),MHD_FD_STATE_EXCEPT)


/**
 * Set/enable specific @a state in the @a var
 */
#define MHD_FD_STATE_SET(var, state) \
        ((var) =                     \
           (enum MHD_FdState) (((unsigned int) var) | ((unsigned int) state)))
/**
 * Set/enable RECV state in the @a var
 */
#define MHD_FD_STATE_SET_RECV(var) MHD_FD_STATE_SET ((var),MHD_FD_STATE_RECV)
/**
 * Set/enable SEND state in the @a var
 */
#define MHD_FD_STATE_SET_SEND(var) MHD_FD_STATE_SET ((var),MHD_FD_STATE_SEND)
/**
 * Set/enable EXCEPT state in the @a var
 */
#define MHD_FD_STATE_SET_EXCEPT(var) \
        MHD_FD_STATE_SET ((var),MHD_FD_STATE_EXCEPT)

/**
 * Clear/disable specific @a state in the @a var
 */
#define MHD_FD_STATE_CLEAR(var, state) \
        ( (var) =                      \
            (enum MHD_FdState)         \
            (((unsigned int) var)      \
             & ((enum MHD_FdState) (~((unsigned int) state)))) \
        )
/**
 * Clear/disable RECV state in the @a var
 */
#define MHD_FD_STATE_CLEAR_RECV(var) \
        MHD_FD_STATE_CLEAR ((var),MHD_FD_STATE_RECV)
/**
 * Clear/disable SEND state in the @a var
 */
#define MHD_FD_STATE_CLEAR_SEND(var) \
        MHD_FD_STATE_CLEAR ((var),MHD_FD_STATE_SEND)
/**
 * Clear/disable EXCEPT state in the @a var
 */
#define MHD_FD_STATE_CLEAR_EXCEPT(var) \
        MHD_FD_STATE_CLEAR ((var),MHD_FD_STATE_EXCEPT)


/**
 * The context data to be used for updates of the socket state
 */
struct MHD_EventUpdateContext;


/* Define MHD_APP_SOCKET_CNTX_TYPE to the socket context type before
 * including this header.
 * This is optional, but improves the types safety.
 * For example:
 * #define MHD_APP_SOCKET_CNTX_TYPE struct my_structure
 */
#ifndef MHD_APP_SOCKET_CNTX_TYPE
#  define MHD_APP_SOCKET_CNTX_TYPE void
#endif

/**
 * The callback for registration/de-registration of the sockets to watch.
 *
 * This callback must not call #MHD_daemon_destroy(), #MHD_daemon_quiesce(),
 * #MHD_daemon_add_connection().
 *
 * @param cls the closure
 * @param fd the socket to watch
 * @param watch_for the states of the @a fd to watch, if set to
 *                  #MHD_FD_STATE_NONE the socket must be de-registred
 * @param app_cntx_old the old application defined context for the socket,
 *                     NULL if @a fd socket was not registered before
 * @param ecb_cntx the context handle to be used
 *                 with #MHD_daemon_event_update()
 * @return must be NULL for the removed (de-registred) sockets,
 *         for new and updated sockets: NULL in case of error (the connection
 *         will be aborted or daemon failed to start if FD does not belong to
 *         connection)
 *         or the new socket context (opaque for MHD, must be non-NULL)
 * @sa #MHD_D_OPTION_REREGISTER_ALL
 * @ingroup event
 */
typedef MHD_APP_SOCKET_CNTX_TYPE *
(MHD_FN_PAR_NONNULL_ (5)
 *MHD_SocketRegistrationUpdateCallback)(
  void *cls,
  MHD_Socket fd,
  enum MHD_FdState watch_for,
  MHD_APP_SOCKET_CNTX_TYPE *app_cntx_old,
  struct MHD_EventUpdateContext *ecb_cntx);


/**
 * Update the sockets state.
 * Must be called for every socket that got state updated.
 * For #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL() mode
 * this function must be called for each socket between any two calls of
 * #MHD_daemon_process_reg_events() function.
 * Available only for daemons started in
 * #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL or
 * #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_EDGE modes.
 * @param daemon the daemon handle
 * @param ecb_cntx the context handle provided
 *                 for #MHD_SocketRegistrationUpdateCallback
 * @param fd_current_state the current state of the socket
 * @ingroup event
 */
MHD_EXTERN_ void
MHD_daemon_event_update (
  struct MHD_Daemon *MHD_RESTRICT daemon,
  struct MHD_EventUpdateContext *MHD_RESTRICT ecb_cntx,
  enum MHD_FdState fd_current_state)
MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (2);


/**
 * Perform all daemon activities based on FDs events provided earlier by
 * application via #MHD_daemon_event_update().
 *
 * This function accepts new connections (if any), performs HTTP communications
 * on all active connections, closes connections as needed and performs FDs
 * registration updates by calling #MHD_SocketRegistrationUpdateCallback
 * callback for every socket that needs to be added/updated/removed.
 *
 * Available only for daemons started in #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL or
 * #MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE modes.
 *
 * When used in #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL mode, application must
 * provide all updates by calling #MHD_daemon_event_update() for every
 * registered FD between any two calls of this function.
 *
 * @param daemon the daemon handle
 * @param[out] next_max_wait_milsec the optional pointer to receive the
                                    next maximum wait time in milliseconds
                                    to be used for the sockets polling
                                    function, can be NULL
 * @return #MHD_SC_OK on success,
 *         error code otherwise
 * @sa #MHD_D_OPTION_REREGISTER_ALL
 * @ingroup event
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_process_reg_events (
  struct MHD_Daemon *MHD_RESTRICT daemon,
  uint_fast64_t *MHD_RESTRICT next_max_wait_milsec)
MHD_FN_PAR_NONNULL_ (1);

/* ********************* daemon options ************** */


/**
 * Which threading and polling mode should be used by MHD?
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_WorkMode
{
  /**
   * Work mode with no internal threads.
   * The application periodically calls #MHD_daemon_process_blocking(), where
   * MHD internally checks all sockets automatically.
   * This is the default mode.
   * Use helper macro #MHD_D_OPTION_WM_EXTERNAL_PERIODIC() to enable
   * this mode.
   */
  MHD_WM_EXTERNAL_PERIODIC = 0
  ,
  /**
   * Work mode with an external event loop with level triggers.
   * MHD provides registration of all FDs to be monitored by using
   * #MHD_SocketRegistrationUpdateCallback, application performs level triggered
   * FDs polling (like select() or poll()), calls function
   * #MHD_daemon_event_update() for every registered FD and then calls main
   * function MHD_daemon_process_reg_events() to process the data.
   * Use helper macro #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL() to enable
   * this mode.
   * @sa #MHD_D_OPTION_REREGISTER_ALL
   */
  MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL = 8
  ,
  /**
   * Work mode with an external event loop with edge triggers.
   * MHD provides registration of all FDs to be monitored by using
   * #MHD_SocketRegistrationUpdateCallback, application performs edge triggered
   * sockets polling (like epoll with EPOLLET), calls function
   * #MHD_daemon_event_update() for FDs with updated states and then calls main
   * function MHD_daemon_process_reg_events() to process the data.
   * Use helper macro #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_EDGE() to enable
   * this mode.
   * @sa #MHD_D_OPTION_REREGISTER_ALL
   */
  MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE = 9
  ,
  /**
   * Work mode with no internal threads and aggregate watch FD.
   * Application uses #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD to get single FD
   * that gets triggered by any MHD event.
   * This FD can be watched as an aggregate indicator for all MHD events.
   * This mode is available only on selected platforms (currently
   * GNU/Linux and OpenIndiana only), see #MHD_LIB_INFO_FIXED_HAS_AGGREGATE_FD.
   * When the FD is triggered, #MHD_daemon_process_nonblocking() should
   * be called.
   * Use helper macro #MHD_D_OPTION_WM_EXTERNAL_SINGLE_FD_WATCH() to enable
   * this mode.
   */
  MHD_WM_EXTERNAL_SINGLE_FD_WATCH = 16
  ,
  /**
   * Work mode with one or more worker threads.
   * If specified number of threads is one, then daemon starts with single
   * worker thread that handles all connections.
   * If number of threads is larger than one, then that number of worker
   * threads, and handling of connection is distributed among the workers.
   * Use helper macro #MHD_D_OPTION_WM_WORKER_THREADS() to enable
   * this mode.
   */
  MHD_WM_WORKER_THREADS = 24
  ,
  /**
   * Work mode with one internal thread for listening and additional threads
   * per every connection.  Use this if handling requests is CPU-intensive or
   * blocking, your application is thread-safe and you have plenty of
   * memory (per connection).
   * Use helper macro #MHD_D_OPTION_WM_THREAD_PER_CONNECTION() to enable
   * this mode.
   */
  MHD_WM_THREAD_PER_CONNECTION = 32
};

/**
 * Work mode parameters for #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL and
 * #MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE modes
 */
struct MHD_WorkModeExternalEventLoopCBParam
{
  /**
   * Socket registration callback
   */
  MHD_SocketRegistrationUpdateCallback reg_cb;
  /**
   * Closure for the @a reg_cb
   */
  void *reg_cb_cls;
};

/**
 * MHD work mode parameters
 */
union MHD_WorkModeParam
{
  /**
   * Work mode parameters for #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL and
   * #MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE modes
   */
  struct MHD_WorkModeExternalEventLoopCBParam v_external_event_loop_cb;
  /**
   * Number of worker threads for #MHD_WM_WORKER_THREADS.
   * If set to one, then daemon starts with single worker thread that process
   * all connections.
   * If set to value larger than one, then that number of worker threads
   * and distributed handling of requests among the workers.
   * Zero is treated as one.
   */
  unsigned int num_worker_threads;
};

/**
 * Parameter for #MHD_D_O_WORK_MODE().
 * Not recommended to be used directly, better use macro/functions to create it:
 * #MHD_WM_OPTION_EXTERNAL_PERIODIC(),
 * #MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL(),
 * #MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE(),
 * #MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH(),
 * #MHD_WM_OPTION_WORKER_THREADS(),
 * #MHD_WM_OPTION_THREAD_PER_CONNECTION()
 */
struct MHD_WorkModeWithParam
{
  /**
   * The work mode for MHD
   */
  enum MHD_WorkMode mode;
  /**
   * The parameters used for specified work mode
   */
  union MHD_WorkModeParam params;
};


#if defined(MHD_USE_COMPOUND_LITERALS) && defined(MHD_USE_DESIG_NEST_INIT)
/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * no internal threads.
 * The application periodically calls #MHD_daemon_process_blocking(), where
 * MHD internally checks all sockets automatically.
 * This is the default mode.
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_EXTERNAL_PERIODIC()      \
          MHD_NOWARN_COMPOUND_LITERALS_          \
            (const struct MHD_WorkModeWithParam) \
          {                                      \
            .mode = (MHD_WM_EXTERNAL_PERIODIC)   \
          }                                      \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * an external event loop with level triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, level triggered
 * sockets polling (like select() or poll()) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL(cb_val, cb_cls_val) \
          MHD_NOWARN_COMPOUND_LITERALS_                                  \
            (const struct MHD_WorkModeWithParam)                         \
          {                                                              \
            .mode = (MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL),               \
            .params.v_external_event_loop_cb.reg_cb = (cb_val),          \
            .params.v_external_event_loop_cb.reg_cb_cls = (cb_cls_val)   \
          }                                                              \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * an external event loop with edge triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, edge triggered
 * sockets polling (like epoll with EPOLLET) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE(cb_val, cb_cls_val) \
          MHD_NOWARN_COMPOUND_LITERALS_                                 \
            (const struct MHD_WorkModeWithParam)                        \
          {                                                             \
            .mode = (MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE),               \
            .params.v_external_event_loop_cb.reg_cb = (cb_val),         \
            .params.v_external_event_loop_cb.reg_cb_cls = (cb_cls_val)  \
          }                                                             \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * no internal threads and aggregate watch FD.
 * Application uses #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD to get single FD
 * that gets triggered by any MHD event.
 * This FD can be watched as an aggregate indicator for all MHD events.
 * This mode is available only on selected platforms (currently
 * GNU/Linux only), see #MHD_LIB_INFO_FIXED_HAS_AGGREGATE_FD.
 * When the FD is triggered, #MHD_daemon_process_nonblocking() should
 * be called.
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH()    \
          MHD_NOWARN_COMPOUND_LITERALS_               \
            (const struct MHD_WorkModeWithParam)      \
          {                                           \
            .mode = (MHD_WM_EXTERNAL_SINGLE_FD_WATCH) \
          }                                           \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * one or more worker threads.
 * If number of threads is one, then daemon starts with single worker thread
 * that handles all connections.
 * If number of threads is larger than one, then that number of worker threads,
 * and handling of connection is distributed among the workers.
 * @param num_workers the number of worker threads, zero is treated as one
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_WORKER_THREADS(num_workers)    \
          MHD_NOWARN_COMPOUND_LITERALS_                \
            (const struct MHD_WorkModeWithParam)       \
          {                                            \
            .mode = (MHD_WM_WORKER_THREADS),           \
            .params.num_worker_threads = (num_workers) \
          }                                            \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * one internal thread for listening and additional threads per every
 * connection.  Use this if handling requests is CPU-intensive or blocking,
 * your application is thread-safe and you have plenty of memory (per
 * connection).
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
#  define MHD_WM_OPTION_THREAD_PER_CONNECTION()    \
          MHD_NOWARN_COMPOUND_LITERALS_            \
            (const struct MHD_WorkModeWithParam)   \
          {                                        \
            .mode = (MHD_WM_THREAD_PER_CONNECTION) \
          }                                        \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

#else  /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */
MHD_NOWARN_UNUSED_FUNC_

/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * no internal threads.
 * The application periodically calls #MHD_daemon_process_blocking(), where
 * MHD internally checks all sockets automatically.
 * This is the default mode.
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_EXTERNAL_PERIODIC (void)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_EXTERNAL_PERIODIC;

  return wm_val;
}


/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * an external event loop with level triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, level triggered
 * sockets polling (like select() or poll()) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL (
  MHD_SocketRegistrationUpdateCallback cb_val,
  void *cb_cls_val)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL;
  wm_val.params.v_external_event_loop_cb.reg_cb = cb_val;
  wm_val.params.v_external_event_loop_cb.reg_cb_cls = cb_cls_val;

  return wm_val;
}


/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * an external event loop with edge triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, edge triggered
 * sockets polling (like epoll with EPOLLET) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE (
  MHD_SocketRegistrationUpdateCallback cb_val,
  void *cb_cls_val)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE;
  wm_val.params.v_external_event_loop_cb.reg_cb = cb_val;
  wm_val.params.v_external_event_loop_cb.reg_cb_cls = cb_cls_val;

  return wm_val;
}


/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * no internal threads and aggregate watch FD.
 * Application uses #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD to get single FD
 * that gets triggered by any MHD event.
 * This FD can be watched as an aggregate indicator for all MHD events.
 * This mode is available only on selected platforms (currently
 * GNU/Linux only), see #MHD_LIB_INFO_FIXED_HAS_AGGREGATE_FD.
 * When the FD is triggered, #MHD_daemon_process_nonblocking() should
 * be called.
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH (void)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_EXTERNAL_SINGLE_FD_WATCH;

  return wm_val;
}


/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * one or more worker threads.
 * If number of threads is one, then daemon starts with single worker thread
 * that handles all connections.
 * If number of threads is larger than one, then that number of worker threads,
 * and handling of connection is distributed among the workers.
 * @param num_workers the number of worker threads, zero is treated as one
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_WORKER_THREADS (unsigned int num_workers)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_WORKER_THREADS;
  wm_val.params.num_worker_threads = num_workers;

  return wm_val;
}


/**
 * Create parameter for #MHD_D_O_WORK_MODE() for work mode with
 * one internal thread for listening and additional threads per every
 * connection.  Use this if handling requests is CPU-intensive or blocking,
 * your application is thread-safe and you have plenty of memory (per
 * connection).
 * @return the object of struct MHD_WorkModeWithParam with requested values
 */
static MHD_INLINE struct MHD_WorkModeWithParam
MHD_WM_OPTION_THREAD_PER_CONNECTION (void)
{
  struct MHD_WorkModeWithParam wm_val;

  wm_val.mode = MHD_WM_THREAD_PER_CONNECTION;

  return wm_val;
}


MHD_RESTORE_WARN_UNUSED_FUNC_
#endif /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */

/**
 * @defgroup logging Log events and control
 */


/**
 * Type of a callback function used for logging by MHD.
 *
 * @param cls closure
 * @param sc status code of the event
 * @param fm format string (`printf()`-style)
 * @param ap arguments to @a fm
 * @ingroup logging
 */
typedef void
(MHD_FN_PAR_NONNULL_ (3)
 MHD_FN_PAR_CSTR_ (3)
 *MHD_LoggingCallback)(void *cls,
                       enum MHD_StatusCode sc,
                       const char *fm,
                       va_list ap);

/**
 * Parameter for listen socket binding type
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_DaemonOptionBindType
{
  /**
   * The listen socket bind to the networks address with sharing the address.
   * Several sockets can bind to the same address.
   */
  MHD_D_OPTION_BIND_TYPE_SHARED = -1
  ,
  /**
   * The listen socket bind to the networks address without sharing the address,
   * except allowing binding to port/address which has TIME_WAIT state (the
   * state after closing connection).
   * On some platforms it may also allow to bind to specific address if other
   * socket already bond to the same port of wildcard address (or bind to
   * wildcard address when other socket already bond to specific address
   * with the same port).
   * Typically achieved by enabling 'SO_REUSEADDR' socket option.
   * Default.
   */
  MHD_D_OPTION_BIND_TYPE_NOT_SHARED = 0
  ,
  /**
   * The listen socket bind to the networks address without sharing the address.
   * The daemon way fail to start when any sockets still in "TIME_WAIT" state
   * on the same port, which effectively prevents quick restart of the daemon
   * on the same port.
   * On W32 systems it works like #MHD_D_OPTION_BIND_TYPE_NOT_SHARED due to
   * the OS limitations.
   */
  MHD_D_OPTION_BIND_TYPE_NOT_SHARED_STRICTER = 1
  ,
  /**
   * The list socket bind to the networks address in explicit exclusive mode.
   * Works as #MHD_D_OPTION_BIND_TYPE_NOT_SHARED_STRICTER on platforms without
   * support for the explicit exclusive socket use.
   */
  MHD_D_OPTION_BIND_TYPE_EXCLUSIVE = 2
};


/**
 * Possible levels of enforcement for TCP_FASTOPEN.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_TCPFastOpenType
{
  /**
   * Disable use of TCP_FASTOPEN.
   */
  MHD_FOM_DISABLE = -1
  ,
  /**
   * Enable TCP_FASTOPEN where supported.
   * On GNU/Linux it works with a kernel >= 3.6.
   * This is the default.
   */
  MHD_FOM_AUTO = 0
  ,
  /**
   * Require TCP_FASTOPEN.
   * Also causes #MHD_daemon_start() to fail if TCP_FASTOPEN cannot be enabled.
   */
  MHD_FOM_REQUIRE = 1
};


/**
 * Address family to be used by MHD.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_AddressFamily
{
  /**
   * Option not given, do not listen at all
   * (unless listen socket or address specified by
   * other means).
   */
  MHD_AF_NONE = 0
  ,
  /**
   * Pick "best" available method automatically.
   */
  MHD_AF_AUTO = 1
  ,
  /**
   * Use IPv4 only.
   */
  MHD_AF_INET4 = 2
  ,
  /**
   * Use IPv6 only.
   */
  MHD_AF_INET6 = 3
  ,
  /**
   * Use dual stack (IPv4 and IPv6 on the same socket).
   */
  MHD_AF_DUAL = 4
  ,
  /**
   * Use dual stack (IPv4 and IPv6 on the same socket),
   * fallback to pure IPv6 if dual stack is not possible.
   */
  MHD_AF_DUAL_v4_OPTIONAL = 5
  ,
  /**
   * Use dual stack (IPv4 and IPv6 on the same socket),
   * fallback to pure IPv4 if dual stack is not possible.
   */
  MHD_AF_DUAL_v6_OPTIONAL = 6

};


/**
 * Sockets polling internal syscalls used by MHD.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_SockPollSyscall
{
  /**
   * Automatic selection of best-available method. This is also the
   * default.
   */
  MHD_SPS_AUTO = 0
  ,
  /**
   * Use select().
   */
  MHD_SPS_SELECT = 1
  ,
  /**
   * Use poll().
   */
  MHD_SPS_POLL = 2
  ,
  /**
   * Use epoll.
   */
  MHD_SPS_EPOLL = 3
  ,
  /**
   * Use kqueue.
   */
  MHD_SPS_KQUEUE = 4
};


/**
 * Protocol strictness levels enforced by MHD on clients.
 * Each level applies different parsing settings for HTTP headers and other
 * protocol elements.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_ProtocolStrictLevel
{

  /* * Basic levels * */
  /**
   * A sane default level of protocol enforcement for production use.
   * Provides a balance between enhanced security and broader compatibility,
   * as permitted by RFCs for HTTP servers.
   */
  MHD_PSL_DEFAULT = 0
  ,
  /**
   * Apply stricter protocol interpretation while remaining within
   * RFC-defined limits for HTTP servers.
   *
   * At this level (and stricter), using a bare LF instead of CRLF is forbidden,
   * and requests that include both a "Transfer-Encoding:" and
   * a "Content-Length:" headers are rejected.
   *
   * Suitable for public servers.
   */
  MHD_PSL_STRICT = 1
  ,
  /**
   * Be more permissive in interpreting the protocol, while still
   * operating within the RFC-defined limits for HTTP servers.
   */
  MHD_PSL_PERMISSIVE = -1
  ,
  /* * Special levels * */
  /**
   * A stricter protocol interpretation than what is allowed by RFCs for HTTP
   * servers. However, it should remain fully compatible with clients correctly
   * following all RFC "MUST" requirements for HTTP clients.
   *
   * For chunked encoding, this level (and more restrictive ones) forbids
   * whitespace in chunk extensions.
   * For cookie parsing, this level (and more restrictive ones) rejects
   * the entire cookie if even a single value within it is incorrectly encoded.
   *
   * Recommended for testing clients against MHD. Can also be used for
   * security-centric applications, though doing so slightly violates
   * relevant RFC requirements for HTTP servers.
   */
  MHD_PSL_VERY_STRICT = 2
  ,
  /**
   * The strictest interpretation of the HTTP protocol, even stricter than
   * allowed by RFCs for HTTP servers.
   * However, it should remain fully compatible with clients complying with both
   * RFC "SHOULD" and "MUST" requirements for HTTP clients.
   *
   * This level can be used for testing clients against MHD.
   * It is not recommended for public services, as it may reject legitimate
   * clients that do not follow RFC "SHOULD" requirements.
   */
  MHD_PSL_EXTRA_STRICT = 3
  ,
  /**
   * A more relaxed protocol interpretation that violates some RFC "SHOULD"
   * restrictions for HTTP servers.
   * For cookie parsing, this level (and more permissive levels) allows
   * whitespace in cookie values.
   *
   * This level may be used in isolated environments.
   */
  MHD_PSL_VERY_PERMISSIVE = -2
  ,
  /**
   * The most flexible protocol interpretation, going beyond RFC "MUST"
   * requirements for HTTP servers.
   *
   * This level allows HTTP/1.1 requests without a "Host:" header.
   * For cookie parsing, whitespace is allowed before and after
   * the '=' character.
   *
   * Not recommended unless absolutely necessary to communicate with clients
   * that have severely broken HTTP implementations.
   */
  MHD_PSL_EXTRA_PERMISSIVE = -3
};

/**
 * The way Strict Level is enforced.
 * MHD can be compiled with limited set of strictness levels.
 * These values instructs MHD how to apply the request level.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_UseStictLevel
{
  /**
   * Use requested level if available or the nearest stricter
   * level.
   * Fail if only more permissive levels available.
   * Recommended value.
   */
  MHD_USL_THIS_OR_STRICTER = 0
  ,
  /**
   * Use requested level only.
   * Fail if this level is not available.
   */
  MHD_USL_PRECISE = 1
  ,
  /**
   * Use requested level if available or the nearest level (stricter
   * or more permissive).
   */
  MHD_USL_NEAREST = 2
};


/**
 * Connection memory buffer zeroing mode.
 * Works as a hardening measure.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_ConnBufferZeroingMode
{
  /**
   * Do not perform zeroing of connection memory buffer.
   * Default mode.
   */
  MHD_CONN_BUFFER_ZEROING_DISABLED = 0
  ,
  /**
   * Perform connection memory buffer zeroing before processing request.
   */
  MHD_CONN_BUFFER_ZEROING_BASIC = 1
  ,
  /**
   * Perform connection memory buffer zeroing before processing request and
   * when reusing buffer memory areas during processing request.
   */
  MHD_CONN_BUFFER_ZEROING_HEAVY = 2
};


/* ********************** (d) TLS support ********************** */

/**
 * The TLS backend choice
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_TlsBackend
{
  /**
   * Disable TLS, use plain TCP connections (default)
   */
  MHD_TLS_BACKEND_NONE = 0
  ,
  /**
   * Use best available TLS backend.
   */
  MHD_TLS_BACKEND_ANY = 1
  ,
  /**
   * Use GnuTLS as TLS backend.
   */
  MHD_TLS_BACKEND_GNUTLS = 2
  ,
  /**
   * Use OpenSSL as TLS backend.
   */
  MHD_TLS_BACKEND_OPENSSL = 3
  ,
  /**
   * Use MbedTLS as TLS backend.
   */
  MHD_TLS_BACKEND_MBEDTLS = 4
};

/**
 * Values for #MHD_D_O_DAUTH_NONCE_BIND_TYPE.
 *
 * These values can limit the scope of validity of MHD-generated nonces.
 * Values can be combined with bitwise OR.
 * Any value, except #MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_NONE, enforce function
 * #MHD_digest_auth_check() (and similar functions) to check nonce by
 * re-generating it again with the same parameters, which is CPU-intensive
 * operation.
 */
enum MHD_FIXED_FLAGS_ENUM_APP_SET_ MHD_DaemonOptionValueDAuthBindNonce
{
  /**
   * Generated nonces are valid for any request from any client until expired.
   * This is default and recommended value.
   * #MHD_digest_auth_check() (and similar functions) would check only whether
   * the nonce value that is used by client has been generated by MHD and not
   * expired yet.
   * It is recommended because RFC 7616 allows clients to use the same nonce
   * for any request in the same "protection space".
   * When checking client's authorisation requests CPU is loaded less if this
   * value is used.
   * This mode gives MHD maximum flexibility for nonces generation and can
   * prevent possible nonce collisions (and corresponding log warning messages)
   * when clients' requests are intensive.
   * This value cannot be biwise-OR combined with other values.
   */
  MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_NONE = 0
  ,
  /**
   * Generated nonces are valid only for the same realm.
   */
  MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_REALM = (1 << 0)
  ,
  /**
   * Generated nonces are valid only for the same URI (excluding parameters
   * after '?' in URI) and request method (GET, POST etc).
   * Not recommended unless "protection space" is limited to a single URI as
   * RFC 7616 allows clients to reuse server-generated nonces for any URI
   * in the same "protection space" which by default consists of all server
   * URIs.
   */
  MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_URI = (1 << 1)
  ,

  /**
   * Generated nonces are valid only for the same URI including URI parameters
   * and request method (GET, POST etc).
   * This value implies #MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_URI.
   * Not recommended for that same reasons as
   * #MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_URI.
   */
  MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_URI_PARAMS = (1 << 2)
  ,

  /**
   * Generated nonces are valid only for the single client's IP.
   * While it looks like security improvement, in practice the same client may
   * jump from one IP to another (mobile or Wi-Fi handover, DHCP re-assignment,
   * Multi-NAT, different proxy chain and other reasons), while IP address
   * spoofing could be used relatively easily.
   */
  MHD_D_OPTION_VALUE_DAUTH_BIND_NONCE_CLIENT_IP = (1 << 3)
};


struct MHD_ServerCredentialsContext;


/**
 * Context required to provide a pre-shared key to the
 * server.
 *
 * @param mscc the context
 * @param psk_size the number of bytes in @a psk
 * @param psk the pre-shared-key; should be allocated with malloc(),
 *                 will be freed by MHD
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_connection_set_psk (
  struct MHD_ServerCredentialsContext *mscc,
  size_t psk_size,
  const /*void? */ char psk[MHD_FN_PAR_DYN_ARR_SIZE_ (psk_size)]);

#define MHD_connection_set_psk_unavailable(mscc) \
        MHD_connection_set_psk (mscc, 0, NULL)


/**
 * Function called to lookup the pre-shared key (PSK) for a given
 * HTTP connection based on the @a username.  MHD will suspend handling of
 * the @a connection until the application calls #MHD_connection_set_psk().
 * If looking up the PSK fails, the application must still call
 * #MHD_connection_set_psk_unavailable().
 *
 * @param cls closure
 * @param connection the HTTPS connection
 * @param username the user name claimed by the other side
 * @param mscc context to pass to #MHD_connection_set_psk().
 */
typedef void
(*MHD_PskServerCredentialsCallback)(
  void *cls,
  const struct MHD_Connection *MHD_RESTRICT connection,
  const struct MHD_String *MHD_RESTRICT username,
  struct MHD_ServerCredentialsContext *mscc);


/**
 * The specified callback will be called one time,
 * after network initialisation, TLS pre-initialisation, but before
 * the start of the internal threads (if allowed).
 *
 * This callback may use introspection call to retrieve and adjust
 * some of the daemon aspects. For example, TLS backend handler can be used
 * to configure some TLS aspects.
 * @param cls the callback closure
 */
typedef void
(*MHD_DaemonReadyCallback)(void *cls);


/**
 * Allow or deny a client to connect.
 *
 * @param cls closure
 * @param addr_len length of @a addr
 * @param addr address information from the client
 * @see #MHD_D_OPTION_ACCEPT_POLICY()
 * @return #MHD_YES if connection is allowed, #MHD_NO if not
 */
typedef enum MHD_Bool
(*MHD_AcceptPolicyCallback)(void *cls,
                            size_t addr_len,
                            const struct sockaddr *addr);


/**
 * The data for the #MHD_EarlyUriLogCallback
 */
struct MHD_EarlyUriCbData
{
  /**
   * The request handle.
   * Headers are not yet available.
   */
  struct MHD_Request *request;

  /**
   * The full URI ("request target") from the HTTP request, including URI
   * parameters (the part after '?')
   */
  struct MHD_String full_uri;

  /**
   * The request HTTP method
   */
  enum MHD_HTTP_Method method;
};

/**
 * Function called by MHD to allow the application to log the @a full_uri
 * of the new request.
 * This is the only moment when unmodified URI is provided.
 * After this callback MHD parses the URI and modifies it by extracting
 * GET parameters in-place.
 *
 * If this callback is set then it is the first application function called
 * for the new request.
 *
 * If #MHD_RequestEndedCallback is also set then it is guaranteed that
 * #MHD_RequestEndedCallback is called for the same request. Application
 * may allocate request specific data in this callback and de-allocate
 * the data in #MHD_RequestEndedCallback.
 *
 * @param cls client-defined closure
 * @param req_data the request data
 * @param request_app_context_ptr the pointer to variable that can be set to
 *                                the application context for the request;
 *                                initially the variable set to NULL
 */
typedef void
(MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_INOUT_ (3)
 *MHD_EarlyUriLogCallback)(void *cls,
                           const struct MHD_EarlyUriCbData *req_data,
                           void **request_app_context_ptr);


/**
 * The `enum MHD_ConnectionNotificationCode` specifies types
 * of connection notifications.
 * @ingroup request
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_ConnectionNotificationCode
{

  /**
   * A new connection has been started.
   * @ingroup request
   */
  MHD_CONNECTION_NOTIFY_STARTED = 0
  ,
  /**
   * A connection is closed.
   * @ingroup request
   */
  MHD_CONNECTION_NOTIFY_CLOSED = 1

};

/**
 * Extra details for connection notifications.
 * Currently not used
 */
union MHD_ConnectionNotificationDetails
{
  /**
   * Unused
   */
  int reserved1;
};


/**
 * The connection notification data structure
 */
struct MHD_ConnectionNotificationData
{
  /**
   * The connection handle
   */
  struct MHD_Connection *connection;
  /**
   * The connection-specific application context data (opaque for MHD).
   * Initially set to NULL (for connections added by MHD) or set by
   * @a connection_cntx parameter for connections added by
   * #MHD_daemon_add_connection().
   */
  void *application_context;
  /**
   * The code of the event
   */
  enum MHD_ConnectionNotificationCode code;
  /**
   * Event details
   */
  union MHD_ConnectionNotificationDetails details;
};


/**
 * Signature of the callback used by MHD to notify the
 * application about started/stopped network connections
 *
 * @param cls client-defined closure
 * @param[in,out]  data the details about the event
 * @see #MHD_D_OPTION_NOTIFY_CONNECTION()
 * @ingroup request
 */
typedef void
(MHD_FN_PAR_NONNULL_ (2)
 *MHD_NotifyConnectionCallback)(void *cls,
                                struct MHD_ConnectionNotificationData *data);


/**
 * The type of stream notifications.
 * @ingroup request
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_StreamNotificationCode
{
  /**
   * A new stream has been started.
   * @ingroup request
   */
  MHD_STREAM_NOTIFY_STARTED = 0
  ,
  /**
   * A stream is closed.
   * @ingroup request
   */
  MHD_STREAM_NOTIFY_CLOSED = 1
};

/**
 * Additional information about stream started event
 */
struct MHD_StreamNotificationDetailStarted
{
  /**
   * Set to #MHD_YES of the stream was started by client
   */
  enum MHD_Bool by_client;
};

/**
 * Additional information about stream events
 */
union MHD_StreamNotificationDetail
{
  /**
   * Information for event #MHD_STREAM_NOTIFY_STARTED
   */
  struct MHD_StreamNotificationDetailStarted started;
};

/**
 * Stream notification data structure
 */
struct MHD_StreamNotificationData
{
  /**
   * The handle of the stream
   */
  struct MHD_Stream *stream;
  /**
   * The code of the event
   */
  enum MHD_StreamNotificationCode code;
  /**
   * Detailed information about notification event
   */
  union MHD_StreamNotificationDetail details;
};


/**
 * Signature of the callback used by MHD to notify the
 * application about started/stopped data stream
 * For HTTP/1.1 it is the same like network connection
 * with 1:1 match.
 *
 * @param cls client-defined closure
 * @param data the details about the event
 * @see #MHD_D_OPTION_NOTIFY_STREAM()
 * @ingroup request
 */
typedef void
(MHD_FN_PAR_NONNULL_ (2)
 *MHD_NotifyStreamCallback)(
  void *cls,
  const struct MHD_StreamNotificationData *data);

#include "microhttpd2_generated_daemon_options.h"


/**
 * The `enum MHD_RequestEndedCode` specifies reasons
 * why a request has been ended.
 * @ingroup request
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_RequestEndedCode
{

  /**
   * The response was successfully sent.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_COMPLETED_OK = 0
  ,
  /**
   * The response was successfully sent and connection is being switched
   * to another protocol.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_COMPLETED_OK_UPGRADE = 1
  ,
  /**
   * No activity on the connection for the number of seconds specified using
   * #MHD_C_OPTION_TIMEOUT().
   * @ingroup request
   */
  MHD_REQUEST_ENDED_TIMEOUT_REACHED = 10
  ,
  /**
   * The connection was broken or TLS protocol error.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_CONNECTION_ERROR = 20
  ,
  /**
   * The client terminated the connection by closing the socket either
   * completely or for writing (TCP half-closed) before sending complete
   * request.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_CLIENT_ABORT = 30
  ,
  /**
   * The request is not valid according to HTTP specifications.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_HTTP_PROTOCOL_ERROR = 31
  ,
  /**
   * The application aborted request without response.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_BY_APP_ABORT = 40
  ,
  /**
   * The request was aborted due to the application failed to provide a valid
   * response.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_BY_APP_ERROR = 41
  ,
  /**
   * The request was aborted due to the application failed to register external
   * event monitoring for the connection.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_BY_EXT_EVENT_ERROR = 42
  ,
  /**
   * Error handling the connection due to resources exhausted.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_NO_RESOURCES = 50
  ,
  /**
   * The request was aborted due to error reading file for file-backed response
   * @ingroup request
   */
  MHD_REQUEST_ENDED_FILE_ERROR = 51
  ,
  /**
   * The request was aborted due to error generating valid nonce for Digest Auth
   * @ingroup request
   */
  MHD_REQUEST_ENDED_NONCE_ERROR = 52
  ,
  /**
   * Closing the session since MHD is being shut down.
   * @ingroup request
   */
  MHD_REQUEST_ENDED_DAEMON_SHUTDOWN = 60
};

/**
 * Additional information about request ending
 */
union MHD_RequestEndedDetail
{
  /**
   * Reserved member.
   * Do not use.
   */
  void *reserved;
};

/**
 * Request termination data structure
 */
struct MHD_RequestEndedData
{
  /**
   * The request handle.
   * Note that most of the request data may be already unvailable.
   */
  struct MHD_Request *req;
  /**
   * The code of the event
   */
  enum MHD_RequestEndedCode code;
  /**
   * Detailed information about the event
   */
  union MHD_RequestEndedDetail details;
};


/**
 * Signature of the callback used by MHD to notify the application
 * about completed requests.
 *
 * This is the last callback called for any request (if provided by
 * the application).
 *
 * @param cls client-defined closure
 * @param data the details about the event
 * @param request_app_context the application request context, as possibly set
                              by the #MHD_EarlyUriLogCallback
 * @see #MHD_R_OPTION_TERMINATION_CALLBACK()
 * @ingroup request
 */
typedef void
(*MHD_RequestEndedCallback)(void *cls,
                            const struct MHD_RequestEndedData *data,
                            void *request_app_context);


#include "microhttpd2_generated_response_options.h"
/* Beginning of generated code documenting how to use options.
   You should treat the following functions *as if* they were
   part of the header/API. The actual declarations are more
   complex, so these here are just for documentation!
   We do not actually *build* this code... */
#if 0

/**
 * Set MHD work (threading and polling) mode.
 * Consider use of #MHD_D_OPTION_WM_EXTERNAL_PERIODIC(), #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL(), #MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_EDGE(), #MHD_D_OPTION_WM_EXTERNAL_SINGLE_FD_WATCH(), #MHD_D_OPTION_WM_WORKER_THREADS() or #MHD_D_OPTION_WM_THREAD_PER_CONNECTION() instead of direct use of this parameter.
 * @param wmp the object created by one of the next functions/macros: #MHD_WM_OPTION_EXTERNAL_PERIODIC(), #MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL(), #MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE(), #MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH(), #MHD_WM_OPTION_WORKER_THREADS(), #MHD_WM_OPTION_THREAD_PER_CONNECTION()
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_WORK_MODE (
  struct MHD_WorkModeWithParam wmp
  );

/**
 * Select a sockets watch system call used for internal polling.
 * @param els FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_POLL_SYSCALL (
  enum MHD_SockPollSyscall els
  );

/**
 * Instruct MHD to register all sockets every processing round.
 *
By default (this options is not enabled) every processing round (every time
 * when #MHD_daemon_event_update() is called) MHD calls
 * #MHD_SocketRegistrationUpdateCallback only for the new sockets, for
 * the removed sockets and for the updated sockets.
 * Some sockets are registered when #MHD_daemon_start() is called.
 *
If this options is enabled, then #MHD_SocketRegistrationUpdateCallback is
 * called for every socket each processing round. No sockets are registered when
 * the daemon is being started.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_REREGISTER_ALL (
  enum MHD_Bool value
  );

/**
 * Set a callback to use for logging
 * @param log_cb the callback to use for logging,
 *   NULL to disable logging.
 *   The logging to stderr is enabled by default.
 * @param log_cb_cls the closure for the logging callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_LOG_CALLBACK (
  MHD_LoggingCallback log_cb,
  void *log_cb_cls
  );

/**
 * Bind to the given TCP port and address family.
 *
Does not work with #MHD_D_OPTION_BIND_SA() or #MHD_D_OPTION_LISTEN_SOCKET().
 *
If no listen socket optins (#MHD_D_OPTION_BIND_PORT(), #MHD_D_OPTION_BIND_SA(), #MHD_D_OPTION_LISTEN_SOCKET()) are used, MHD does not listen for incoming connection.
 * @param af the address family to use,
 *   the #MHD_AF_NONE to disable listen socket (the same effect as if this option is not used)
 * @param port port to use, 0 to let system assign any free port,
 *   ignored if @a af is #MHD_AF_NONE
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_BIND_PORT (
  enum MHD_AddressFamily af,
  uint_least16_t port
  );

/**
 * Bind to the given socket address.
 *
Does not work with #MHD_D_OPTION_BIND_PORT() or #MHD_D_OPTION_LISTEN_SOCKET().
 *
If no listen socket optins (#MHD_D_OPTION_BIND_PORT(), #MHD_D_OPTION_BIND_SA(), #MHD_D_OPTION_LISTEN_SOCKET()) are used, MHD does not listen for incoming connection.
 * @param sa_len the size of the socket address pointed by @a sa.
 * @param sa the address to bind to; can be IPv4 (AF_INET), IPv6 (AF_INET6) or even a UNIX domain socket (AF_UNIX)
 * @param dual When a previous version of the protocol exist (like IPv4 when @a v_sa is IPv6) bind to both protocols (IPv6 and IPv4).
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_BIND_SA (
  size_t sa_len,
  /* const */ struct sockaddr *sa,
  enum MHD_Bool dual
  );

/**
 * Accept connections from the given socket.  Socket
 * must be a TCP or UNIX domain (SOCK_STREAM) socket.
 *
Does not work with #MHD_D_OPTION_BIND_PORT() or #MHD_D_OPTION_BIND_SA().
 *
If no listen socket optins (#MHD_D_OPTION_BIND_PORT(), #MHD_D_OPTION_BIND_SA(), #MHD_D_OPTION_LISTEN_SOCKET()) are used, MHD does not listen for incoming connection.
 * @param listen_fd the listen socket to use, ignored if set to #MHD_INVALID_SOCKET
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_LISTEN_SOCKET (
  MHD_Socket listen_fd
  );

/**
 * Select mode of reusing address:port listen address.
 *
Works only when #MHD_D_OPTION_BIND_PORT() or #MHD_D_OPTION_BIND_SA() are used.
 * @param reuse_type FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_LISTEN_ADDR_REUSE (
  enum MHD_DaemonOptionBindType reuse_type
  );

/**
 * Configure TCP_FASTOPEN option, including setting a
 * custom @a queue_length.
 *
Note that having a larger queue size can cause resource exhaustion
 * attack as the TCP stack has to now allocate resources for the SYN
 * packet along with its DATA.
 *
Works only when #MHD_D_OPTION_BIND_PORT() or #MHD_D_OPTION_BIND_SA() are used.
 * @param option the type use of of TCP FastOpen
 * @param queue_length the length of the queue, zero to use system or MHD default,
 *   silently ignored on platforms without support for custom queue size
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TCP_FASTOPEN (
  enum MHD_TCPFastOpenType option,
  unsigned int queue_length
  );

/**
 * Use the given backlog for the listen() call.
 *
Works only when #MHD_D_OPTION_BIND_PORT() or #MHD_D_OPTION_BIND_SA() are used.
 * Zero parameter treated as MHD/system default.
 * @param backlog_size FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_LISTEN_BACKLOG (
  unsigned int backlog_size
  );

/**
 * Inform that SIGPIPE is suppressed or handled by application.
 * If suppressed/handled, MHD uses network functions that could generate SIGPIPE, like `sendfile()`.
 * Silently ignored when MHD creates internal threads as for them SIGPIPE is suppressed automatically.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_SIGPIPE_SUPPRESSED (
  enum MHD_Bool value
  );

/**
 * Enable TLS (HTTPS) and select TLS backend
 * @param backend the TLS backend to use,
 *   #MHD_TLS_BACKEND_NONE for non-TLS (plain TCP) connections
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS (
  enum MHD_TlsBackend backend
  );

/**
 * Provide TLS key and certificate data in-memory.
 * Works only if TLS mode is enabled.
 * @param mem_cert The X.509 certificates chain in PEM format loaded into memory (not a filename).
 *   The first certificate must be the server certificate, following by the chain of signing
 *   certificates up to (but not including) CA root certificate.
 * @param mem_key the private key in PEM format loaded into memory (not a filename)
 * @param mem_pass the option passphrase phrase to decrypt the private key,
 *   could be NULL if private key does not need a password
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS_CERT_KEY (
  /* const */ char *mem_cert,
  const char *mem_key,
  const char *mem_pass
  );

/**
 * Provide the certificate of the certificate authority (CA) to be used by the MHD daemon for client authentication.
 * Works only if TLS mode is enabled.
 * @param mem_client_ca the CA certificate in memory (not a filename)
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS_CLIENT_CA (
  const char *mem_client_ca
  );

/**
 * Configure PSK to use for the TLS key exchange.
 * @param psk_cb the function to call to obtain pre-shared key
 * @param psk_cb_cls the closure for @a psk_cb
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS_PSK_CALLBACK (
  MHD_PskServerCredentialsCallback psk_cb,
  void *psk_cb_cls
  );

/**
 * Control ALPN for TLS connection.
 * Silently ignored for non-TLS.
 * By default ALPN is automatically used for TLS connections.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_NO_ALPN (
  enum MHD_Bool value
  );

/**
 * Provide application name to load dedicated section in TLS backend's configuration file.
 * Search for "System-wide configuration of the library" for GnuTLS documentation or
 * for "config, OPENSSL LIBRARY CONFIGURATION" for OpenSSL documentation.
 * If not specified the default backend configuration is used:
 * "@LIBMICROHTTPD" (if available), then "@SYSTEM" (if available) then default priorities, then "NORMAL" for GnuTLS;
 * "libmicrohttpd" (if available), then default name ("openssl_conf") for OpenSSL.
 * Ignored when MbedTLS is used as daemon's TLS backend.
 * @param app_name the name of the application, used as converted to
 *   uppercase (with '@'-prefixed) for GnuTLS and as converted to
 *   lowercase for OpenSSL; must not be longer than 127 characters
 * @param disable_fallback forbid use fallback/default configuration if specified
 *   configuration is not found; also forbid ignoring errors in the
 *   configuration on TLS backends, which may ignoring configuration
 *   errors
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS_APP_NAME (
  char *app_name,
  enum MHD_Bool disable_fallback
  );

/**
 * Set the configuration pathname for OpenSSL configuration file
 * Ignored OpenSSL is not used as daemon's TLS backend.
 * @param pathname the path and the name of the OpenSSL configuration file,
 *   if only the name is provided then standard path for
 *   configuration files is used,
 *   could be NULL to use default configuration file pathname
 *   or an empty (zero-size) string to disable file loading
 * @param disable_fallback forbid use of fallback/default location and name of
 *   the OpenSSL configuration file; also forbid initialisation without
 *   configuration file
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TLS_OPENSSL_DEF_FILE (
  char *pathname,
  enum MHD_Bool disable_fallback
  );

/**
 * Specify the inactivity timeout for a connection in milliseconds.
 * If a connection remains idle (no activity) for this many
 * milliseconds, it is closed automatically.
 * Use zero for no timeout; this is also the (unsafe!)
 * default.
 * Values larger than 1209600000 (two weeks) are silently
 * clamped to 1209600000.
 * Precise closing time is not guaranteed and depends on
 * system clock granularity and amount of time spent on
 * processing other connections. Typical precision is
 * within +/- 30 milliseconds, while the worst case could
 * be greater than +/- 1 second.
 * Values below 1500 milliseconds are risky as they
 * may cause valid connections to be aborted and may
 * increase load the server load due to clients' repetitive
 * automatic retries.
 * @param timeout the timeout in milliseconds, zero for no timeout
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DEFAULT_TIMEOUT_MILSEC (
  uint_fast32_t timeout
  );

/**
 * Maximum number of (concurrent) network connections served by daemon.
 * @note The real maximum number of network connections could be smaller
 *       than requested due to the system limitations, like FD_SETSIZE when
 *       polling by select() is used.
 * @param glob_limit FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_GLOBAL_CONNECTION_LIMIT (
  unsigned int glob_limit
  );

/**
 * Limit on the number of (concurrent) network connections made to the server from the same IP address.
 * Can be used to prevent one IP from taking over all of the allowed connections. If the same IP tries to establish more than the specified number of connections, they will be immediately rejected.
 * @param limit FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_PER_IP_LIMIT (
  unsigned int limit
  );

/**
 * Set a policy callback that accepts/rejects connections based on the client's IP address.  The callbeck function will be called before servicing any new incoming connection.
 * @param apc the accept policy callback
 * @param apc_cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_ACCEPT_POLICY (
  MHD_AcceptPolicyCallback apc,
  void *apc_cls
  );

/**
 * Set mode of connection memory buffer zeroing
 * @param buff_zeroing buffer zeroing mode
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_CONN_BUFF_ZEROING (
  enum MHD_ConnBufferZeroingMode buff_zeroing
  );

/**
 * Set how strictly MHD will enforce the HTTP protocol.
 * @param sl the level of strictness
 * @param how the way how to use the requested level
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_PROTOCOL_STRICT_LEVEL (
  enum MHD_ProtocolStrictLevel sl,
  enum MHD_UseStictLevel how
  );

/**
 * Set a callback to be called first for every request when the request line is received (before any parsing of the header).
 * This callback is the only way to get raw (unmodified) request URI as URI is parsed and modified by MHD in-place.
 * Mandatory URI modification may apply before this call, like binary zero replacement, as required by RFCs.
 * @param cb the early URI callback
 * @param cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_EARLY_URI_LOGGER (
  MHD_EarlyUriLogCallback cb,
  void *cls
  );

/**
 * Disable converting plus ('+') character to space in GET parameters (URI part after '?').
 * Plus conversion is not required by HTTP RFCs, however it required by HTML specifications, see https://url.spec.whatwg.org/#application/x-www-form-urlencoded for details.
 * By default plus is converted to space in the query part of URI.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DISABLE_URI_QUERY_PLUS_AS_SPACE (
  enum MHD_Bool value
  );

/**
 * Suppresse use of 'Date:' header.
 * According to RFC should be suppressed only if the system has no RTC.
 * The 'Date:' is not suppressed (the header is enabled) by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_SUPPRESS_DATE_HEADER (
  enum MHD_Bool value
  );

/**
 * Use SHOUTcast for responses.
 * This will cause *all* responses to begin with the SHOUTcast 'ICY' line instead of 'HTTP'.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_ENABLE_SHOUTCAST (
  enum MHD_Bool value
  );

/**
 * Maximum memory size per connection.
 * Default is 32kb.
 * Values above 128kb are unlikely to result in much performance benefit, as half of the memory will be typically used for IO, and TCP buffers are unlikely to support window sizes above 64k on most systems.
 * The size should be large enough to fit all request headers (together with internal parsing information).
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_CONN_MEMORY_LIMIT (
  size_t value
  );

/**
 * The size of the shared memory pool for accamulated upload processing.
 * The same large pool is shared for all connections server by MHD and used when application requests avoiding of incremental upload processing to accamulate complete content upload before giving it to the application.
 * Default is 8Mb.
 * Can be set to zero to disable share pool.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_LARGE_POOL_SIZE (
  size_t value
  );

/**
 * Desired size of the stack for the threads started by MHD.
 * Use 0 for system default, which is also MHD default.
 * Works only with #MHD_D_OPTION_WM_WORKER_THREADS() or #MHD_D_OPTION_WM_THREAD_PER_CONNECTION().
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_STACK_SIZE (
  size_t value
  );

/**
 * The the maximum FD value.
 * The limit is applied to all sockets used by MHD.
 * If listen socket FD is equal or higher that specified value, the daemon fail to start.
 * If new connection FD is equal or higher that specified value, the connection is rejected.
 * Useful if application uses select() for polling the sockets, system FD_SETSIZE is good value for this option in such case.
 * Silently ignored on W32 (WinSock sockets).
 * @param max_fd FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_FD_NUMBER_LIMIT (
  MHD_Socket max_fd
  );

/**
 * Enable `turbo`.
 * Disables certain calls to `shutdown()`, enables aggressive non-blocking optimistic reads and other potentially unsafe optimisations.
 * Most effects only happen with internal threads with epoll.
 * The 'turbo' mode is not enabled (mode is disabled) by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_TURBO (
  enum MHD_Bool value
  );

/**
 * Disable some internal thread safety.
 * Indicates that MHD daemon will be used by application in single-threaded mode only.  When this flag is set then application must call any MHD function only within a single thread.
 * This flag turns off some internal thread-safety and allows MHD making some of the internal optimisations suitable only for single-threaded environment.
 * Not compatible with any internal threads modes.
 * If MHD is compiled with custom configuration for embedded projects without threads support, this option is mandatory.
 * Thread safety is not disabled (safety is enabled) by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DISABLE_THREAD_SAFETY (
  enum MHD_Bool value
  );

/**
 * You need to set this option if you want to disable use of HTTP Upgrade.
 * Upgrade may require usage of additional internal resources, which we can avoid providing if they will not be used.
 * You should only use this option if you do not use upgrade functionality and need a generally minor boost in performance and resources saving.
 * The upgrade is not disallowed (upgrade is allowed) by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DISALLOW_UPGRADE (
  enum MHD_Bool value
  );

/**
 * Disable #MHD_action_suspend() functionality.
 *
You should only use this function if you do not use suspend functionality and need a generally minor boost in performance.
 * The suspend is not disallowed (suspend is allowed) by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DISALLOW_SUSPEND_RESUME (
  enum MHD_Bool value
  );

/**
 * Disable cookies parsing.
 *
Disable automatic cookies processing if cookies are not used.
 * Cookies are automatically parsed by default.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DISABLE_COOKIES (
  enum MHD_Bool value
  );

/**
 * Set a callback to be called for pre-start finalisation.
 *
The specified callback will be called one time, after network initialisation, TLS pre-initialisation, but before the start of the internal threads (if allowed)
 * @param cb the pre-start callback
 * @param cb_cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_DAEMON_READY_CALLBACK (
  MHD_DaemonReadyCallback cb,
  void *cb_cls
  );

/**
 * Set a function that should be called whenever a connection is started or closed.
 * @param ncc the callback for notifications
 * @param cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_NOTIFY_CONNECTION (
  MHD_NotifyConnectionCallback ncc,
  void *cls
  );

/**
 * Register a function that should be called whenever a stream is started or closed.
 * For HTTP/1.1 this callback is called one time for every connection.
 * @param nsc the callback for notifications
 * @param cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_NOTIFY_STREAM (
  MHD_NotifyStreamCallback nsc,
  void *cls
  );

/**
 * Set strong random data to be used by MHD.
 * Currently the data is only needed for Digest Auth module.
 * Daemon support for Digest Auth is enabled automatically if this option is used.
 * The recommended size is between 8 and 32 bytes. Security can be lower for sizes less or equal four.
 * Sizes larger then 32 (or, probably, larger than 16 - debatable) will not increase the security.
 * @param buf_size the size of the buffer
 * @param buf the buffer with strong random data, the content will be copied by MHD
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_RANDOM_ENTROPY (
  size_t buf_size,
  /* const */ void *buf
  );

/**
 * Specify the size of the internal hash map array that tracks generated digest nonces usage.
 * When the size of the map is too small then need to handle concurrent DAuth requests, a lot of stale nonce results will be produced.
 * By default the size is 1000 entries.
 * @param size the size of the map array
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_AUTH_DIGEST_MAP_SIZE (
  size_t size
  );

/**
 * Nonce validity time (in seconds) used for Digest Auth.
 * If followed by zero value the value is silently ignored.
 * @see #MHD_digest_auth_check(), MHD_digest_auth_check_digest()
 * @param timeout FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_AUTH_DIGEST_NONCE_TIMEOUT (
  unsigned int timeout
  );

/**
 * Default maximum nc (nonce count) value used for Digest Auth.
 * If followed by zero value the value is silently ignored.
 * @see #MHD_digest_auth_check(), MHD_digest_auth_check_digest()
 * @param max_nc FIXME
 * @return structure with the requested setting
 */
struct MHD_DaemonOptionAndValue
MHD_D_OPTION_AUTH_DIGEST_DEF_MAX_NC (
  uint_fast32_t max_nc
  );

/* End of generated code documenting how to use options */
#endif

/* Beginning of generated code documenting how to use options.
   You should treat the following functions *as if* they were
   part of the header/API. The actual declarations are more
   complex, so these here are just for documentation!
   We do not actually *build* this code... */
#if 0

/**
 * Make the response object re-usable.
 * The response will not be consumed by MHD_action_from_response() and must be destroyed by MHD_response_destroy().
 * Useful if the same response is often used to reply.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_REUSABLE (
  enum MHD_Bool value
  );

/**
 * Enable special processing of the response as body-less (with undefined body size). No automatic 'Content-Length' or 'Transfer-Encoding: chunked' headers are added when the response is used with #MHD_HTTP_STATUS_NOT_MODIFIED code or to respond to HEAD request.
 * The flag also allow to set arbitrary 'Content-Length' by #MHD_response_add_header() function.
 * This flag value can be used only with responses created without body (zero-size body).
 * Responses with this flag enabled cannot be used in situations where reply body must be sent to the client.
 * This flag is primarily intended to be used when automatic 'Content-Length' header is undesirable in response to HEAD requests.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_HEAD_ONLY_RESPONSE (
  enum MHD_Bool value
  );

/**
 * Force use of chunked encoding even if the response content size is known.
 * Ignored when the reply cannot have body/content.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_CHUNKED_ENC (
  enum MHD_Bool value
  );

/**
 * Force close connection after sending the response, prevents keep-alive connections and adds 'Connection: close' header.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_CONN_CLOSE (
  enum MHD_Bool value
  );

/**
 * Only respond in conservative (dumb) HTTP/1.0-compatible mode.
 * Response still use HTTP/1.1 version in header, but always close the connection after sending the response and do not use chunked encoding for the response.
 * You can also set the #MHD_R_O_HTTP_1_0_SERVER flag to force HTTP/1.0 version in the response.
 * Responses are still compatible with HTTP/1.1.
 * Summary:
 * + declared reply version: HTTP/1.1
 * + keep-alive: no
 * + chunked: no
 *
This option can be used to communicate with some broken client, which does not implement HTTP/1.1 features, but advertises HTTP/1.1 support.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_HTTP_1_0_COMPATIBLE_STRICT (
  enum MHD_Bool value
  );

/**
 * Only respond in HTTP/1.0-mode.
 * Contrary to the #MHD_R_O_HTTP_1_0_COMPATIBLE_STRICT flag, the response's HTTP version will always be set to 1.0 and keep-alive connections will be used if explicitly requested by the client.
 * The 'Connection:' header will be added for both 'close' and 'keep-alive' connections.
 * Chunked encoding will not be used for the response.
 * Due to backward compatibility, responses still can be used with HTTP/1.1 clients.
 * This option can be used to emulate HTTP/1.0 server (for response part only as chunked encoding in requests (if any) is processed by MHD).
 * Summary:
 * + declared reply version: HTTP/1.0
 * + keep-alive: possible
 * + chunked: no
 *
With this option HTTP/1.0 server is emulated (with support for 'keep-alive' connections).
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_HTTP_1_0_SERVER (
  enum MHD_Bool value
  );

/**
 * Disable sanity check preventing clients from manually setting the HTTP content length option.
 * Allow to set several 'Content-Length' headers. These headers will be used even with replies without body.
 * @param value the value of the parameter * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_INSANITY_HEADER_CONTENT_LENGTH (
  enum MHD_Bool value
  );

/**
 * Set a function to be called once MHD is finished with the request.
 * @param ended_cb the function to call,
 *   NULL to not use the callback
 * @param ended_cb_cls the closure for the callback
 * @return structure with the requested setting
 */
struct MHD_ResponseOptionAndValue
MHD_R_OPTION_TERMINATION_CALLBACK (
  MHD_RequestEndedCallback ended_cb,
  void *ended_cb_cls
  );

/* End of generated code documenting how to use options */
#endif

/**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * no internal threads.
 * The application periodically calls #MHD_daemon_process_blocking(), where
 * MHD internally checks all sockets automatically.
 * This is the default mode.
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
#define MHD_D_OPTION_WM_EXTERNAL_PERIODIC() \
        MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_EXTERNAL_PERIODIC ())

/**
* Create parameter for #MHD_daemon_set_options() for work mode with
* an external event loop with level triggers.
* Application uses #MHD_SocketRegistrationUpdateCallback, level triggered
* sockets polling (like select() or poll()) and #MHD_daemon_event_update().
* @param cb_val the callback for sockets registration
* @param cb_cls_val the closure for the @a cv_val callback
* @return the object of struct MHD_DaemonOptionAndValue with requested values
*/
#define MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL(cb_val, cb_cls_val) \
        MHD_D_OPTION_WORK_MODE ( \
          MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL ((cb_val),(cb_cls_val)))

/**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * an external event loop with edge triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, edge triggered
 * sockets polling (like epoll with EPOLLET) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
#define MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_EDGE(cb_val, cb_cls_val) \
        MHD_D_OPTION_WORK_MODE ( \
          MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE ((cb_val),(cb_cls_val)))

/**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * no internal threads and aggregate watch FD.
 * Application uses #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD to get single FD
 * that gets triggered by any MHD event.
 * This FD can be watched as an aggregate indicator for all MHD events.
 * This mode is available only on selected platforms (currently
 * GNU/Linux only), see #MHD_LIB_INFO_FIXED_HAS_AGGREGATE_FD.
 * When the FD is triggered, #MHD_daemon_process_nonblocking() should
 * be called.
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
#define MHD_D_OPTION_WM_EXTERNAL_SINGLE_FD_WATCH() \
        MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH ())

/**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * one or more worker threads.
 * If number of threads is one, then daemon starts with single worker thread
 * that handles all connections.
 * If number of threads is larger than one, then that number of worker threads,
 * and handling of connection is distributed among the workers.
 * @param num_workers the number of worker threads, zero is treated as one
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
#define MHD_D_OPTION_WM_WORKER_THREADS(num_workers) \
        MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_WORKER_THREADS (num_workers))

/**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * one internal thread for listening and additional threads per every
 * connection.  Use this if handling requests is CPU-intensive or blocking,
 * your application is thread-safe and you have plenty of memory (per
 * connection).
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
#define MHD_D_OPTION_WM_THREAD_PER_CONNECTION() \
        MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_THREAD_PER_CONNECTION ())

/**
 * Set the requested options for the daemon.
 *
 * If any option fail other options may be or may be not applied.
 * @param daemon the daemon to set the options
 * @param[in] options the pointer to the array with the options;
 *                    the array processing stops at the first ::MHD_D_O_END
 *                    option, but not later than after processing
 *                    @a options_max_num entries
 * @param options_max_num the maximum number of entries in the @a options,
 *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
 *                        must stop only at zero-termination option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_set_options (
  struct MHD_Daemon *MHD_RESTRICT daemon,
  const struct MHD_DaemonOptionAndValue *MHD_RESTRICT options,
  size_t options_max_num)
MHD_FN_PAR_NONNULL_ALL_;


/**
 * Set the requested single option for the daemon.
 *
 * @param daemon the daemon to set the option
 * @param[in] option_ptr the pointer to the option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#define MHD_daemon_set_option(daemon, option_ptr) \
        MHD_daemon_set_options (daemon, option_ptr, 1)


/* *INDENT-OFF* */
#ifdef MHD_USE_VARARG_MACROS
MHD_NOWARN_VARIADIC_MACROS_
#  if defined(MHD_USE_COMPOUND_LITERALS) && \
  defined(MHD_USE_COMP_LIT_FUNC_PARAMS)
/**
 * Set the requested options for the daemon.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_DAEMON_SET_OPTIONS(d, MHD_D_OPTION_SUPPRESS_DATE_HEADER(MHD_YES),
 *                        MHD_D_OPTION_SOCK_ADDR(sa_len, sa))
 *
 * @param daemon the daemon to set the options
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_D_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_DAEMON_SET_OPTIONS(daemon,...)          \
            MHD_NOWARN_COMPOUND_LITERALS_                   \
            MHD_NOWARN_AGGR_DYN_INIT_                       \
            MHD_daemon_set_options (                        \
              daemon,                                       \
              ((const struct MHD_DaemonOptionAndValue[])    \
               {__VA_ARGS__, MHD_D_OPTION_TERMINATE ()}),   \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                   \
            MHD_RESTORE_WARN_AGGR_DYN_INIT_                 \
            MHD_RESTORE_WARN_COMPOUND_LITERALS_
#  elif defined(MHD_USE_CPP_INIT_LIST)
MHD_C_DECLARATIONS_FINISH_HERE_
#    include <vector>
MHD_C_DECLARATIONS_START_HERE_
/**
 * Set the requested options for the daemon.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_DAEMON_SET_OPTIONS(d, MHD_D_OPTION_SUPPRESS_DATE_HEADER(MHD_YES),
 *                        MHD_D_OPTION_SOCK_ADDR(sa_len, sa))
 *
 * @param daemon the daemon to set the options
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_D_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_DAEMON_SET_OPTIONS(daemon,...)                  \
            MHD_NOWARN_CPP_INIT_LIST_                               \
            MHD_daemon_set_options (                                \
              daemon,                                               \
              (std::vector<struct MHD_DaemonOptionAndValue>         \
               {__VA_ARGS__,MHD_D_OPTION_TERMINATE ()}).data (),    \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
            MHD_RESTORE_WARN_CPP_INIT_LIST_
#  endif
MHD_RESTORE_WARN_VARIADIC_MACROS_
#endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
/* *INDENT-ON* */


/* ******************* Event loop ************************ */


/**
 * Run websever operation with possible blocking.
 *
 * Supported only in #MHD_WM_EXTERNAL_PERIODIC and
 * #MHD_WM_EXTERNAL_SINGLE_FD_WATCH modes.
 *
 * This function does the following: waits for any network event not more than
 * specified number of microseconds, processes all incoming and outgoing data,
 * processes new connections, processes any timed-out connection, and does
 * other things required to run webserver.
 * Once all connections are processed, function returns.
 *
 * This function is useful for quick and simple (lazy) webserver implementation
 * if application needs to run a single thread only and does not have any other
 * network activity.
 *
 * In #MHD_WM_EXTERNAL_PERIODIC mode if @a microsec parameter is not zero
 * this function determines the internal daemon timeout and use returned value
 * as maximum wait time if it less than value of @a microsec parameter.
 *
 * @param daemon the daemon to run
 * @param microsec the maximum time in microseconds to wait for network and
 *                 other events. Note: there is no guarantee that function
 *                 blocks for the specified amount of time. The real processing
 *                 time can be shorter (if some data or connection timeout
 *                 comes earlier) or longer (if data processing requires more
 *                 time, especially in user callbacks).
 *                 If set to '0' then function does not block and processes
 *                 only already available data (if any). Zero value is
 *                 recommended when used in #MHD_WM_EXTERNAL_SINGLE_FD_WATCH
 *                 and the watched FD has been triggered.
 *                 If set to #MHD_WAIT_INDEFINITELY then function waits
 *                 for events indefinitely (blocks until next network activity
 *                 or connection timeout).
 *                 Always used as zero value in
 *                 #MHD_WM_EXTERNAL_SINGLE_FD_WATCH mode.
 * @return #MHD_SC_OK on success, otherwise
 *         an error code
 * @ingroup event
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_process_blocking (struct MHD_Daemon *daemon,
                             uint_fast64_t microsec)
MHD_FN_PAR_NONNULL_ (1);

/**
 * Run webserver operations (without blocking unless in client
 * callbacks).
 *
 * Supported only in #MHD_WM_EXTERNAL_SINGLE_FD_WATCH mode.
 *
 * This function does the following: processes all incoming and outgoing data,
 * processes new connections, processes any timed-out connection, and does
 * other things required to run webserver.
 * Once all connections are processed, function returns.
 *
 * @param daemon the daemon to run
 * @return #MHD_SC_OK on success, otherwise
 *         an error code
 * @ingroup event
 */
#define MHD_daemon_process_nonblocking(daemon) \
        MHD_daemon_process_blocking (daemon, 0)


/**
 * Add another client connection to the set of connections managed by
 * MHD.  This API is usually not needed (since MHD will accept inbound
 * connections on the server socket).  Use this API in special cases,
 * for example if your HTTP server is behind NAT and needs to connect
 * out to the HTTP client, or if you are building a proxy.
 *
 * The given client socket will be managed (and closed!) by MHD after
 * this call and must no longer be used directly by the application
 * afterwards.
 * The client socket will be closed by MHD even if error returned.
 *
 * @param daemon daemon that manages the connection
 * @param new_socket socket to manage (MHD will expect to receive an
                     HTTP request from this socket next).
 * @param addr_size number of bytes in @a addr
 * @param addr IP address of the client, ignored when @a addrlen is zero
 * @param connection_cntx meta data the application wants to
 *        associate with the new connection object
 * @return #MHD_SC_OK on success,
 *         error on failure (the @a new_socket is closed)
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_add_connection (struct MHD_Daemon *MHD_RESTRICT daemon,
                           MHD_Socket new_socket,
                           size_t addr_size,
                           const struct sockaddr *MHD_RESTRICT addr,
                           void *connection_cntx)
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_IN_ (4);


/* ********************* connection options ************** */

enum MHD_FIXED_ENUM_APP_SET_ MHD_ConnectionOption
{
  /**
   * Not a real option.
   * Should not be used directly.
   * This value indicates the end of the list of the options.
   */
  MHD_C_O_END = 0
  ,
  /**
   * Set custom timeout for the given connection.
   * Specified as the number of seconds.  Use zero for no timeout.
   * Setting this option resets connection timeout timer.
   */
  MHD_C_O_TIMEOUT = 1
  ,


  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_C_O_SENTINEL = 65535
};


/**
 * Dummy-struct for space allocation.
 * Do not use in application logic.
 */
struct MHD_ReservedStruct
{
  uint_fast64_t reserved1;
  void *reserved2;
};


/**
 * Parameters for MHD connection options
 */
union MHD_ConnectionOptionValue
{
  /**
   * Value for #MHD_C_O_TIMEOUT
   */
  unsigned int v_timeout;
  /**
   * Reserved member. Do not use.
   */
  struct MHD_ReservedStruct reserved;
};

/**
 * Combination of MHD connection option with parameters values
 */
struct MHD_ConnectionOptionAndValue
{
  /**
   * The connection configuration option
   */
  enum MHD_ConnectionOption opt;
  /**
   * The value for the @a opt option
   */
  union MHD_ConnectionOptionValue val;
};

#if defined(MHD_USE_COMPOUND_LITERALS) && defined(MHD_USE_DESIG_NEST_INIT)
/**
 * Set custom timeout for the given connection.
 * Specified as the number of seconds.  Use zero for no timeout.
 * Setting this option resets connection timeout timer.
 * @param timeout the in seconds, zero for no timeout
 * @return the object of struct MHD_ConnectionOptionAndValue with the requested
 *         values
 */
#  define MHD_C_OPTION_TIMEOUT(timeout)         \
          MHD_NOWARN_COMPOUND_LITERALS_                 \
            (const struct MHD_ConnectionOptionAndValue) \
          {                                             \
            .opt = (MHD_C_O_TIMEOUT),                   \
            .val.v_timeout = (timeout)                  \
          }                                             \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

/**
 * Terminate the list of the options
 * @return the terminating object of struct MHD_ConnectionOptionAndValue
 */
#  define MHD_C_OPTION_TERMINATE()              \
          MHD_NOWARN_COMPOUND_LITERALS_                 \
            (const struct MHD_ConnectionOptionAndValue) \
          {                                             \
            .opt = (MHD_C_O_END)                        \
          }                                             \
          MHD_RESTORE_WARN_COMPOUND_LITERALS_

#else  /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */
MHD_NOWARN_UNUSED_FUNC_

/**
 * Set custom timeout for the given connection.
 * Specified as the number of seconds.  Use zero for no timeout.
 * Setting this option resets connection timeout timer.
 * @param timeout the in seconds, zero for no timeout
 * @return the object of struct MHD_ConnectionOptionAndValue with the requested
 *         values
 */
static MHD_INLINE struct MHD_ConnectionOptionAndValue
MHD_C_OPTION_TIMEOUT (unsigned int timeout)
{
  struct MHD_ConnectionOptionAndValue opt_val;

  opt_val.opt = MHD_C_O_TIMEOUT;
  opt_val.val.v_timeout = timeout;

  return opt_val;
}


/**
 * Terminate the list of the options
 * @return the terminating object of struct MHD_ConnectionOptionAndValue
 */
static MHD_INLINE struct MHD_ConnectionOptionAndValue
MHD_C_OPTION_TERMINATE (void)
{
  struct MHD_ConnectionOptionAndValue opt_val;

  opt_val.opt = MHD_C_O_END;

  return opt_val;
}


MHD_RESTORE_WARN_UNUSED_FUNC_
#endif /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */

/**
 * Set the requested options for the connection.
 *
 * If any option fail other options may be or may be not applied.
 * @param connection the connection to set the options
 * @param[in] options the pointer to the array with the options;
 *                    the array processing stops at the first ::MHD_D_O_END
 *                    option, but not later than after processing
 *                    @a options_max_num entries
 * @param options_max_num the maximum number of entries in the @a options,
 *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
 *                        must stop only at zero-termination option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_connection_set_options (
  struct MHD_Connection *MHD_RESTRICT connection,
  const struct MHD_ConnectionOptionAndValue *MHD_RESTRICT options,
  size_t options_max_num)
MHD_FN_PAR_NONNULL_ALL_;


/**
 * Set the requested single option for the connection.
 *
 * @param connection the connection to set the options
 * @param[in] option_ptr the pointer to the option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#define MHD_connection_set_option(connection, option_ptr) \
        MHD_connection_set_options (connection, options_ptr, 1)


/* *INDENT-OFF* */
#ifdef MHD_USE_VARARG_MACROS
MHD_NOWARN_VARIADIC_MACROS_
#  if defined(MHD_USE_COMPOUND_LITERALS) && defined(MHD_USE_COMP_LIT_FUNC_PARAMS \
                                                    )
/**
 * Set the requested options for the connection.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_CONNECTION_SET_OPTIONS(d, MHD_C_OPTION_TIMEOUT(30))
 *
 * @param connection the connection to set the options
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_C_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_CONNECTION_SET_OPTIONS(connection,...)          \
            MHD_NOWARN_COMPOUND_LITERALS_                           \
            MHD_connection_set_options (                            \
              daemon,                                               \
              ((const struct MHD_ConnectionOptionAndValue [])       \
               {__VA_ARGS__, MHD_C_OPTION_TERMINATE ()}),           \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
            MHD_RESTORE_WARN_COMPOUND_LITERALS_
#  elif defined(MHD_USE_CPP_INIT_LIST)
MHD_C_DECLARATIONS_FINISH_HERE_
#    include <vector>
MHD_C_DECLARATIONS_START_HERE_
/**
 * Set the requested options for the connection.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_CONNECTION_SET_OPTIONS(d, MHD_C_OPTION_TIMEOUT(30))
 *
 * @param connection the connection to set the options
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_C_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_CONNECTION_SET_OPTIONS(daemon,...)              \
            MHD_NOWARN_CPP_INIT_LIST_                               \
            MHD_daemon_set_options (                                \
              daemon,                                               \
              (std::vector<struct MHD_ConnectionOptionAndValue>     \
               {__VA_ARGS__,MHD_C_OPTION_TERMINATE ()}).data (),    \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
            MHD_RESTORE_WARN_CPP_INIT_LIST_
#  endif
MHD_RESTORE_WARN_VARIADIC_MACROS_
#endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
/* *INDENT-ON* */


/* **************** Request handling functions ***************** */


/**
 * The `enum MHD_ValueKind` specifies the source of
 * the name-value pairs in the HTTP protocol.
 */
enum MHD_FLAGS_ENUM_ MHD_ValueKind
{

  /**
   * HTTP header.
   * The 'value' for this kind is mandatory.
   */
  MHD_VK_HEADER = (1u << 0)
  ,
  /**
   * Cookies.  Note that the original HTTP header containing
   * the cookie(s) will still be available and intact.
   * The 'value' for this kind is optional.
   */
  MHD_VK_COOKIE = (1u << 1)
  ,
  /**
   * URI query parameter.
   * The 'value' for this kind is optional.
   */
  MHD_VK_URI_QUERY_PARAM = (1u << 2)
  ,
  /**
   * POST data.
   * This is available only if #MHD_action_parse_post() action is used,
   * a content encoding is supported by MHD, and only if the posted content
   * fits within the specified memory buffers.
   *
   * @warning The encoding "multipart/form-data" has more fields than just
   * "name" and "value". See #MHD_request_get_post_data_cb() and
   * #MHD_request_get_post_data_list(). In particular it could be important
   * to check used "Transfer-Encoding". While it is deprecated and not used
   * by modern clients, formally it can be used.
   */
  MHD_VK_POSTDATA = (1u << 3)
  ,
  /**
   * HTTP trailer (only for HTTP 1.1 chunked encodings, "footer").
   * The 'value' for this kind is mandatory.
   */
  MHD_VK_TRAILER = (1u << 4)
  ,
  /**
   * Header and trailer values.
   */
  MHD_VK_HEADER_TRAILER = MHD_VK_HEADER | MHD_VK_TRAILER
  ,
  /**
   * Values from URI query parameters or post data.
   */
  MHD_VK_URI_QUERY_POST = MHD_VK_POSTDATA | MHD_VK_URI_QUERY_PARAM
};

/**
 * Name with value pair
 */
struct MHD_NameAndValue
{
  /**
   * The name (key) of the field.
   * The pointer to the C string must never be NULL.
   * Some types (kinds) allow empty strings.
   */
  struct MHD_String name;
  /**
   * The value of the field.
   * Some types (kinds) allow absence of the value. The absence is indicated
   * by NULL pointer to the C string.
   */
  struct MHD_StringNullable value;
};

/**
 * Name, value and kind (type) of data
 */
struct MHD_NameValueKind
{
  /**
   * The name and the value of the field
   */
  struct MHD_NameAndValue nv;
  /**
   * The kind (type) of the field
   */
  enum MHD_ValueKind kind;
};

/**
 * Iterator over name-value pairs.  This iterator can be used to
 * iterate over all of the cookies, headers, footers or POST-data fields
 * of a request.
 *
 * The @a nv pointer is valid only until return from this function.
 *
 * The strings in @a nv are valid until any MHD_Action or MHD_UploadAction
 * is provided.
 * If the data is needed beyond this point, it should be copied.
 *
 * @param cls closure
 * @param nv the name and the value of the element, the pointer is valid only until
 *           return from this function
 * @param kind the type (kind) of the element
 * @return #MHD_YES to continue iterating,
 *         #MHD_NO to abort the iteration
 * @ingroup request
 */
typedef enum MHD_Bool
(MHD_FN_PAR_NONNULL_ (3)
 *MHD_NameValueIterator)(void *cls,
                         enum MHD_ValueKind kind,
                         const struct MHD_NameAndValue *nv);


/**
 * Get all of the headers (or other kind of request data) via callback.
 *
 * @param[in,out] request request to get values from
 * @param kind types of values to iterate over, can be a bitmask
 * @param iterator callback to call on each header;
 *        maybe NULL (then just count headers)
 * @param iterator_cls extra argument to @a iterator
 * @return number of entries iterated over
 * @ingroup request
 */
MHD_EXTERN_ size_t
MHD_request_get_values_cb (struct MHD_Request *request,
                           enum MHD_ValueKind kind,
                           MHD_NameValueIterator iterator,
                           void *iterator_cls)
MHD_FN_PAR_NONNULL_ (1);


/**
 * Get all of the headers (or other kind of request data) from the request.
 *
 * The pointers to the strings in @a elements are valid until any
 * MHD_Action or MHD_UploadAction is provided. If the data is needed beyond
 * this point, it should be copied.
 *
 * @param[in] request request to get values from
 * @param kind the types of values to get, can be a bitmask
 * @param num_elements the number of elements in @a elements array
 * @param[out] elements the array of @a num_elements strings to be filled with
 *                      the key-value pairs; if @a request has more elements
 *                      than @a num_elements than any @a num_elements are
 *                      stored
 * @return the number of elements stored in @a elements, the
 *         number cannot be larger then @a num_elements,
 *         zero if there is no such values or any error occurs
 */
MHD_EXTERN_ size_t
MHD_request_get_values_list (
  struct MHD_Request *request,
  enum MHD_ValueKind kind,
  size_t num_elements,
  struct MHD_NameValueKind elements[MHD_FN_PAR_DYN_ARR_SIZE_ (num_elements)])
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (4) MHD_FN_PAR_OUT_SIZE_ (4, 3);


/**
 * Get a particular header (or other kind of request data) value.
 * If multiple values match the kind, return any one of them.
 *
 * The data in the @a value_out is valid until any MHD_Action or
 * MHD_UploadAction is provided. If the data is needed beyond this point,
 * it should be copied.
 *
 * @param request request to get values from
 * @param kind what kind of value are we looking for
 * @param key the name of the value looking for (used for case-insensetive
 *            match), empty to lookup 'trailing' value without a key
 * @param[out] value_out set to the value of the header if succeed,
 *                       the @a cstr pointer could be NULL even if succeed
 *                       if the requested item found, but has no value
 * @return #MHD_YES if succeed, the @a value_out is set;
 *         #MHD_NO if no such item was found, the @a value_out string pointer
 *                 set to NULL
 * @ingroup request
 */
MHD_EXTERN_ enum MHD_Bool
MHD_request_get_value (struct MHD_Request *MHD_RESTRICT request,
                       enum MHD_ValueKind kind,
                       const char *MHD_RESTRICT key,
                       struct MHD_StringNullable *MHD_RESTRICT value_out)
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3)
MHD_FN_PAR_OUT_ (4);


/**
 * @brief Status codes defined for HTTP responses.
 *
 * @defgroup httpcode HTTP response codes
 * @{
 */
/* Registry export date: 2023-09-29 */
/* See http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml */
enum MHD_FIXED_ENUM_APP_SET_ MHD_HTTP_StatusCode
{
  /* 100 "Continue".            RFC9110, Section 15.2.1. */
  MHD_HTTP_STATUS_CONTINUE =                    100
  ,
  /* 101 "Switching Protocols". RFC9110, Section 15.2.2. */
  MHD_HTTP_STATUS_SWITCHING_PROTOCOLS =         101
  ,
  /* 102 "Processing".          RFC2518. */
  MHD_HTTP_STATUS_PROCESSING =                  102
  ,
  /* 103 "Early Hints".         RFC8297. */
  MHD_HTTP_STATUS_EARLY_HINTS =                 103
  ,

  /* 200 "OK".                  RFC9110, Section 15.3.1. */
  MHD_HTTP_STATUS_OK =                          200
  ,
  /* 201 "Created".             RFC9110, Section 15.3.2. */
  MHD_HTTP_STATUS_CREATED =                     201
  ,
  /* 202 "Accepted".            RFC9110, Section 15.3.3. */
  MHD_HTTP_STATUS_ACCEPTED =                    202
  ,
  /* 203 "Non-Authoritative Information". RFC9110, Section 15.3.4. */
  MHD_HTTP_STATUS_NON_AUTHORITATIVE_INFORMATION = 203
  ,
  /* 204 "No Content".          RFC9110, Section 15.3.5. */
  MHD_HTTP_STATUS_NO_CONTENT =                  204
  ,
  /* 205 "Reset Content".       RFC9110, Section 15.3.6. */
  MHD_HTTP_STATUS_RESET_CONTENT =               205
  ,
  /* 206 "Partial Content".     RFC9110, Section 15.3.7. */
  MHD_HTTP_STATUS_PARTIAL_CONTENT =             206
  ,
  /* 207 "Multi-Status".        RFC4918. */
  MHD_HTTP_STATUS_MULTI_STATUS =                207
  ,
  /* 208 "Already Reported".    RFC5842. */
  MHD_HTTP_STATUS_ALREADY_REPORTED =            208
  ,

  /* 226 "IM Used".             RFC3229. */
  MHD_HTTP_STATUS_IM_USED =                     226
  ,

  /* 300 "Multiple Choices".    RFC9110, Section 15.4.1. */
  MHD_HTTP_STATUS_MULTIPLE_CHOICES =            300
  ,
  /* 301 "Moved Permanently".   RFC9110, Section 15.4.2. */
  MHD_HTTP_STATUS_MOVED_PERMANENTLY =           301
  ,
  /* 302 "Found".               RFC9110, Section 15.4.3. */
  MHD_HTTP_STATUS_FOUND =                       302
  ,
  /* 303 "See Other".           RFC9110, Section 15.4.4. */
  MHD_HTTP_STATUS_SEE_OTHER =                   303
  ,
  /* 304 "Not Modified".        RFC9110, Section 15.4.5. */
  MHD_HTTP_STATUS_NOT_MODIFIED =                304
  ,
  /* 305 "Use Proxy".           RFC9110, Section 15.4.6. */
  MHD_HTTP_STATUS_USE_PROXY =                   305
  ,
  /* 306 "Switch Proxy".        Not used! RFC9110, Section 15.4.7. */
  MHD_HTTP_STATUS_SWITCH_PROXY =                306
  ,
  /* 307 "Temporary Redirect".  RFC9110, Section 15.4.8. */
  MHD_HTTP_STATUS_TEMPORARY_REDIRECT =          307
  ,
  /* 308 "Permanent Redirect".  RFC9110, Section 15.4.9. */
  MHD_HTTP_STATUS_PERMANENT_REDIRECT =          308
  ,

  /* 400 "Bad Request".         RFC9110, Section 15.5.1. */
  MHD_HTTP_STATUS_BAD_REQUEST =                 400
  ,
  /* 401 "Unauthorized".        RFC9110, Section 15.5.2. */
  MHD_HTTP_STATUS_UNAUTHORIZED =                401
  ,
  /* 402 "Payment Required".    RFC9110, Section 15.5.3. */
  MHD_HTTP_STATUS_PAYMENT_REQUIRED =            402
  ,
  /* 403 "Forbidden".           RFC9110, Section 15.5.4. */
  MHD_HTTP_STATUS_FORBIDDEN =                   403
  ,
  /* 404 "Not Found".           RFC9110, Section 15.5.5. */
  MHD_HTTP_STATUS_NOT_FOUND =                   404
  ,
  /* 405 "Method Not Allowed".  RFC9110, Section 15.5.6. */
  MHD_HTTP_STATUS_METHOD_NOT_ALLOWED =          405
  ,
  /* 406 "Not Acceptable".      RFC9110, Section 15.5.7. */
  MHD_HTTP_STATUS_NOT_ACCEPTABLE =              406
  ,
  /* 407 "Proxy Authentication Required". RFC9110, Section 15.5.8. */
  MHD_HTTP_STATUS_PROXY_AUTHENTICATION_REQUIRED = 407
  ,
  /* 408 "Request Timeout".     RFC9110, Section 15.5.9. */
  MHD_HTTP_STATUS_REQUEST_TIMEOUT =             408
  ,
  /* 409 "Conflict".            RFC9110, Section 15.5.10. */
  MHD_HTTP_STATUS_CONFLICT =                    409
  ,
  /* 410 "Gone".                RFC9110, Section 15.5.11. */
  MHD_HTTP_STATUS_GONE =                        410
  ,
  /* 411 "Length Required".     RFC9110, Section 15.5.12. */
  MHD_HTTP_STATUS_LENGTH_REQUIRED =             411
  ,
  /* 412 "Precondition Failed". RFC9110, Section 15.5.13. */
  MHD_HTTP_STATUS_PRECONDITION_FAILED =         412
  ,
  /* 413 "Content Too Large".   RFC9110, Section 15.5.14. */
  MHD_HTTP_STATUS_CONTENT_TOO_LARGE =           413
  ,
  /* 414 "URI Too Long".        RFC9110, Section 15.5.15. */
  MHD_HTTP_STATUS_URI_TOO_LONG =                414
  ,
  /* 415 "Unsupported Media Type". RFC9110, Section 15.5.16. */
  MHD_HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE =      415
  ,
  /* 416 "Range Not Satisfiable". RFC9110, Section 15.5.17. */
  MHD_HTTP_STATUS_RANGE_NOT_SATISFIABLE =       416
  ,
  /* 417 "Expectation Failed".  RFC9110, Section 15.5.18. */
  MHD_HTTP_STATUS_EXPECTATION_FAILED =          417
  ,


  /* 421 "Misdirected Request". RFC9110, Section 15.5.20. */
  MHD_HTTP_STATUS_MISDIRECTED_REQUEST =         421
  ,
  /* 422 "Unprocessable Content". RFC9110, Section 15.5.21. */
  MHD_HTTP_STATUS_UNPROCESSABLE_CONTENT =       422
  ,
  /* 423 "Locked".              RFC4918. */
  MHD_HTTP_STATUS_LOCKED =                      423
  ,
  /* 424 "Failed Dependency".   RFC4918. */
  MHD_HTTP_STATUS_FAILED_DEPENDENCY =           424
  ,
  /* 425 "Too Early".           RFC8470. */
  MHD_HTTP_STATUS_TOO_EARLY =                   425
  ,
  /* 426 "Upgrade Required".    RFC9110, Section 15.5.22. */
  MHD_HTTP_STATUS_UPGRADE_REQUIRED =            426
  ,

  /* 428 "Precondition Required". RFC6585. */
  MHD_HTTP_STATUS_PRECONDITION_REQUIRED =       428
  ,
  /* 429 "Too Many Requests".   RFC6585. */
  MHD_HTTP_STATUS_TOO_MANY_REQUESTS =           429
  ,

  /* 431 "Request Header Fields Too Large". RFC6585. */
  MHD_HTTP_STATUS_REQUEST_HEADER_FIELDS_TOO_LARGE = 431
  ,

  /* 451 "Unavailable For Legal Reasons". RFC7725. */
  MHD_HTTP_STATUS_UNAVAILABLE_FOR_LEGAL_REASONS = 451
  ,

  /* 500 "Internal Server Error". RFC9110, Section 15.6.1. */
  MHD_HTTP_STATUS_INTERNAL_SERVER_ERROR =       500
  ,
  /* 501 "Not Implemented".     RFC9110, Section 15.6.2. */
  MHD_HTTP_STATUS_NOT_IMPLEMENTED =             501
  ,
  /* 502 "Bad Gateway".         RFC9110, Section 15.6.3. */
  MHD_HTTP_STATUS_BAD_GATEWAY =                 502
  ,
  /* 503 "Service Unavailable". RFC9110, Section 15.6.4. */
  MHD_HTTP_STATUS_SERVICE_UNAVAILABLE =         503
  ,
  /* 504 "Gateway Timeout".     RFC9110, Section 15.6.5. */
  MHD_HTTP_STATUS_GATEWAY_TIMEOUT =             504
  ,
  /* 505 "HTTP Version Not Supported". RFC9110, Section 15.6.6. */
  MHD_HTTP_STATUS_HTTP_VERSION_NOT_SUPPORTED =  505
  ,
  /* 506 "Variant Also Negotiates". RFC2295. */
  MHD_HTTP_STATUS_VARIANT_ALSO_NEGOTIATES =     506
  ,
  /* 507 "Insufficient Storage". RFC4918. */
  MHD_HTTP_STATUS_INSUFFICIENT_STORAGE =        507
  ,
  /* 508 "Loop Detected".       RFC5842. */
  MHD_HTTP_STATUS_LOOP_DETECTED =               508
  ,

  /* 510 "Not Extended".        (OBSOLETED) RFC2774; status-change-http-experiments-to-historic. */
  MHD_HTTP_STATUS_NOT_EXTENDED =                510
  ,
  /* 511 "Network Authentication Required". RFC6585. */
  MHD_HTTP_STATUS_NETWORK_AUTHENTICATION_REQUIRED = 511
  ,


  /* Not registered non-standard codes */
  /* 449 "Reply With".          MS IIS extension. */
  MHD_HTTP_STATUS_RETRY_WITH =                  449
  ,

  /* 450 "Blocked by Windows Parental Controls". MS extension. */
  MHD_HTTP_STATUS_BLOCKED_BY_WINDOWS_PARENTAL_CONTROLS = 450
  ,

  /* 509 "Bandwidth Limit Exceeded". Apache extension. */
  MHD_HTTP_STATUS_BANDWIDTH_LIMIT_EXCEEDED =    509
};


/**
 * Returns the string status for a response code.
 *
 * This function works for @b HTTP status code, not for @b MHD error codes/
 * @param code the HTTP code to get text representation for
 * @return the pointer to the text representation,
 *         NULL if HTTP status code in not known.
 */
MHD_EXTERN_ const struct MHD_String *
MHD_HTTP_status_code_to_string (enum MHD_HTTP_StatusCode code)
MHD_FN_CONST_;

/**
 * Get the pointer to the C string for the HTTP response code, never NULL.
 */
#define MHD_HTTP_status_code_to_string_lazy(code) \
        (MHD_HTTP_status_code_to_string ((code)) ? \
         ((MHD_HTTP_status_code_to_string (code))->cstr) : ("[No status]") )


/** @} */ /* end of group httpcode */

#ifndef MHD_HTTP_PROTOCOL_VER_DEFINED

/**
 * @brief HTTP protocol versions
 * @defgroup versions HTTP versions
 * @{
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_HTTP_ProtocolVersion
{
  MHD_HTTP_VERSION_INVALID = 0  /**< Invalid/unrecognised HTTP version */
  ,
  MHD_HTTP_VERSION_1_0 = 10     /**< HTTP/1.0 */
  ,
  MHD_HTTP_VERSION_1_1 = 11     /**< HTTP/1.1 */
  ,
  MHD_HTTP_VERSION_1_2P = 19    /**< HTTP/1.2 - HTTP/1.9 */
  ,
  MHD_HTTP_VERSION_2 = 20       /**< HTTP/2 */
  ,
  MHD_HTTP_VERSION_3 = 30       /**< HTTP/3 */
  ,
  MHD_HTTP_VERSION_FUTURE = 255 /**< Future HTTP version */
};

#  define MHD_HTTP_PROTOCOL_VER_DEFINED 1
#endif /* ! MHD_HTTP_PROTOCOL_VER_DEFINED */

/**
 * Return the string representation of the requested HTTP version.
 * Note: this is suitable mainly for logging and similar purposes as
 * HTTP/2 (and later) is not used inside the HTTP protocol.
 * @param pv the protocol version
 * @return the string representation of the protocol version,
 *         NULL for invalid values
 */
MHD_EXTERN_ const struct MHD_String *
MHD_protocol_version_to_string (enum MHD_HTTP_ProtocolVersion pv)
MHD_FN_CONST_;

/**
 * HTTP/1.0 identification string
 */
#define MHD_HTTP_VERSION_1_0_STR "HTTP/1.0"
/**
 * HTTP/1.1 identification string
 */
#define MHD_HTTP_VERSION_1_1_STR "HTTP/1.1"
/**
 * Identification string for clients claiming HTTP/1.2 - HTTP/1.9
 * Not used by the HTTP protocol, useful for logs and similar purposes.
 */
#define MHD_HTTP_VERSION_1_2P_STR "HTTP/1.2+"
/**
 * HTTP/2 identification string.
 * Not used by the HTTP protocol (except non-TLS handshake), useful for logs and
 * similar purposes.
 */
#define MHD_HTTP_VERSION_2_STR "HTTP/2"
/**
 * HTTP/3 identification string.
 * Not used by the HTTP protocol, useful for logs and similar purposes.
 */
#define MHD_HTTP_VERSION_3_STR "HTTP/3"

/** @} */ /* end of group versions */


/**
 * Resume handling of network data for suspended request.
 * It is safe to resume a suspended request at any time.
 * Calling this function on a request that was not previously suspended will
 * result in undefined behaviour.
 *
 * @param[in,out] request the request to resume
 */
MHD_EXTERN_ void
MHD_request_resume (struct MHD_Request *request)
MHD_FN_PAR_NONNULL_ALL_;


/* ************** Action and Response manipulation functions **************** */

/**
 * @defgroup response Response objects control
 */


/**
 * Name with value pair as C strings
 */
struct MHD_NameValueCStr
{
  /**
   * The name (key) of the field.
   * Must never be NULL.
   * Some types (kinds) allow empty strings.
   */
  const char *name;
  /**
   * The value of the field.
   * Some types (kinds) allow absence of the value. The absence is indicated
   * by NULL pointer.
   */
  const char *value;
};

/**
 * Data transmitted in response to an HTTP request.
 * Usually the final action taken in response to
 * receiving a request.
 */
struct MHD_Response;


/**
 * Suspend handling of network data for a given request.  This can
 * be used to dequeue a request from MHD's event loop for a while.
 *
 * Suspended requests continue to count against the total number of
 * requests allowed (per daemon, as well as per IP, if such limits
 * are set).  Suspended requests will NOT time out; timeouts will
 * restart when the request handling is resumed.  While a
 * request is suspended, MHD may not detect disconnects by the
 * client.
 *
 * At most one action can be created for any request.
 *
 * @param[in,out] request the request for which the action is generated
 * @return action to cause a request to be suspended,
 *         NULL if any action has been already created for the @a request
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_Action *
MHD_action_suspend (struct MHD_Request *request)
MHD_FN_PAR_NONNULL_ALL_;


/**
 * Converts a @a response to an action.  If #MHD_R_O_REUSABLE
 * is not set, the reference to the @a response is consumed
 * by the conversion. If #MHD_R_O_REUSABLE is #MHD_YES,
 * then the @a response can be used again to create actions in
 * the future.
 * However, the @a response is frozen by this step and
 * must no longer be modified (i.e. by setting headers).
 *
 * At most one action can be created for any request.
 *
 * @param request the request to create the action for
 * @param[in] response the response to convert,
 *                     if NULL then this function is equivalent to
 *                     #MHD_action_abort_connection() call
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed (no memory) or if any action has been already
 *         created for the @a request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_Action *
MHD_action_from_response (struct MHD_Request *MHD_RESTRICT request,
                          struct MHD_Response *MHD_RESTRICT response)
MHD_FN_PAR_NONNULL_ (1);


/**
 * Action telling MHD to close the connection hard
 * (kind-of breaking HTTP specification).
 *
 * @param req the request to make an action
 * @return action operation, always NULL
 * @ingroup action
 */
#define MHD_action_abort_request(req) \
        MHD_STATIC_CAST_ (const struct MHD_Action *, NULL)


/**
 * Set the requested options for the response.
 *
 * If any option fail other options may be or may be not applied.
 * @param response the response to set the options
 * @param[in] options the pointer to the array with the options;
 *                    the array processing stops at the first ::MHD_D_O_END
 *                    option, but not later than after processing
 *                    @a options_max_num entries
 * @param options_max_num the maximum number of entries in the @a options,
 *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
 *                        must stop only at zero-termination option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_response_set_options (
  struct MHD_Response *MHD_RESTRICT response,
  const struct MHD_ResponseOptionAndValue *MHD_RESTRICT options,
  size_t options_max_num)
MHD_FN_PAR_NONNULL_ALL_;


/**
 * Set the requested single option for the response.
 *
 * @param response the response to set the option
 * @param[in] option_ptr the pointer to the option
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 * @ingroup response
 */
#define MHD_response_set_option(response, option_ptr) \
        MHD_response_set_options (response,option_ptr,1)


/* *INDENT-OFF* */
#ifdef MHD_USE_VARARG_MACROS
MHD_NOWARN_VARIADIC_MACROS_
#  if defined(MHD_USE_COMPOUND_LITERALS) && \
  defined(MHD_USE_COMP_LIT_FUNC_PARAMS)
/**
 * Set the requested options for the response.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_RESPONSE_SET_OPTIONS(r, MHD_R_OPTION_REUSABLE(MHD_YES),
 *                          MHD_R_OPTION_TERMINATION_CALLBACK(func, cls))
 *
 * @param response the response to set the option
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_RESPONSE_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_RESPONSE_SET_OPTIONS(response,...)              \
            MHD_NOWARN_COMPOUND_LITERALS_                           \
            MHD_response_set_options (                              \
              response,                                             \
              ((const struct MHD_ResponseOptionAndValue[])          \
               {__VA_ARGS__, MHD_R_OPTION_TERMINATE ()}),           \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
            MHD_RESTORE_WARN_COMPOUND_LITERALS_
#  elif defined(MHD_USE_CPP_INIT_LIST)
MHD_C_DECLARATIONS_FINISH_HERE_
#    include <vector>
MHD_C_DECLARATIONS_START_HERE_
/**
 * Set the requested options for the response.
 *
 * If any option fail other options may be or may be not applied.
 *
 * It should be used with helpers that creates required options, for example:
 *
 * MHD_RESPONSE_SET_OPTIONS(r, MHD_R_OPTION_REUSABLE(MHD_YES),
 *                          MHD_R_OPTION_TERMINATION_CALLBACK(func, cls))
 *
 * @param response the response to set the option
 * @param ... the list of the options, each option must be created
 *            by helpers MHD_RESPONSE_OPTION_NameOfOption(option_value)
 * @return ::MHD_SC_OK on success,
 *         error code otherwise
 */
#    define MHD_RESPONSE_SET_OPTIONS(response,...)              \
            MHD_NOWARN_CPP_INIT_LIST_                               \
            MHD_response_set_options (                              \
              response,                                             \
              (std::vector<struct MHD_ResponseOptionAndValue>       \
               {__VA_ARGS__,MHD_R_OPTION_TERMINATE ()}).data (),    \
              MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
            MHD_RESTORE_WARN_CPP_INIT_LIST_
#  endif
MHD_RESTORE_WARN_VARIADIC_MACROS_
#endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
/* *INDENT-ON* */

#ifndef MHD_FREECALLBACK_DEFINED

/**
 * This method is called by libmicrohttpd when response with dynamic content
 * is being destroyed.  It should be used to free resources associated
 * with the dynamic content.
 *
 * @param[in] free_cls closure
 * @ingroup response
 */
typedef void
(*MHD_FreeCallback)(void *free_cls);

#  define MHD_FREECALLBACK_DEFINED 1
#endif /* ! MHD_FREECALLBACK_DEFINED */
#ifndef MHD_DYNCONTENTZCIOVEC_DEFINED


/**
 * Structure for iov type of the response.
 * Used for zero-copy response content data.
 */
struct MHD_DynContentZCIoVec
{
  /**
   * The number of elements in @a iov
   */
  unsigned int iov_count;
  /**
   * The pointer to the array with @a iov_count elements.
   */
  const struct MHD_IoVec *iov;
  /**
   * The callback to free resources.
   * It is called once the full array of iov elements is sent.
   * No callback is called if NULL.
   */
  MHD_FreeCallback iov_fcb;
  /**
   * The parameter for @a iov_fcb
   */
  void *iov_fcb_cls;
};

#  define MHD_DYNCONTENTZCIOVEC_DEFINED 1
#endif /* ! MHD_DYNCONTENTZCIOVEC_DEFINED */

/**
 * The action type returned by Dynamic Content Creator callback
 */
struct MHD_DynamicContentCreatorAction;

/**
 * The context used for Dynamic Content Creator callback
 */
struct MHD_DynamicContentCreatorContext;


/**
 * Create "continue processing" action with optional chunk-extension.
 * The data is provided in the buffer and/or in the zero-copy @a iov_data.
 *
 * If data is provided both in the buffer and @a ivo_data then
 * data in the buffer sent first, following the iov data.
 * The total size of the data in the buffer and in @a iov_data must
 * be non-zero.
 * If response content size is known and total size of content provided earlier
 * for this request combined with the size provided by this action is larger
 * then known response content size, then NULL is returned.
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @param data_size the amount of the data placed to the provided buffer,
 *                  cannot be larger than provided buffer size,
 *                  must be non-zero if @a iov_data is NULL or has no data,
 * @param iov_data the optional pointer to the iov data,
 *                 must not be NULL and have non-zero size data if @a data_size
 *                 is zero,
 * @param chunk_ext the optional pointer to chunk extension string,
 *                  can be NULL to not use chunk extension,
 *                  ignored if chunked encoding is not used
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
MHD_DCC_action_continue_zc (
  struct MHD_DynamicContentCreatorContext *ctx,
  size_t data_size,
  const struct MHD_DynContentZCIoVec *iov_data,
  const char *MHD_RESTRICT chunk_ext)
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_CSTR_ (4);


/**
 * Create "continue processing" action with optional chunk-extension.
 * The data is provided in the buffer.
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @param data_size the amount of the data placed to the provided buffer (not @a iov_data),
 *                  cannot be larger than provided buffer size,
 *                  must be non-zero.
 * @param chunk_ext the optional pointer to chunk extension string,
 *                  can be NULL to not use chunk extension,
 *                  ignored if chunked encoding is not used
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
#define MHD_DCC_action_continue_ce(ctx, data_size, chunk_ext) \
        MHD_DCC_action_continue_zc ((ctx), (data_size), NULL, (chunk_ext))


/**
 * Create "continue processing" action, the data is provided in the buffer.
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @param data_size the amount of the data placed to the provided buffer;
 *                  cannot be larger than provided buffer size,
 *                  must be non-zero.
 *
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
#define MHD_DCC_action_continue(ctx, data_size) \
        MHD_DCC_action_continue_ce ((ctx), (data_size), NULL)


/**
 * Create "finished" action with optional footers.
 * If function failed for any reason, the action is automatically
 * set to "stop with error".
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @param num_footers number of elements in the @a footers array,
 *                    must be zero if @a footers is NULL
 * @param footers the optional pointer to the array of the footers (the strings
 *                are copied and does not need to be valid after return from
 *                this function),
 *                can be NULL if @a num_footers is zero
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
MHD_DCC_action_finish_with_footer (
  struct MHD_DynamicContentCreatorContext *ctx,
  size_t num_footers,
  const struct MHD_NameValueCStr *MHD_RESTRICT footers)
MHD_FN_PAR_NONNULL_ (1);


/**
 * Create "finished" action.
 * If function failed for any reason, the action is automatically
 * set to "stop with error".
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
#define MHD_DCC_action_finish(ctx) \
        MHD_DCC_action_finish_with_footer ((ctx), 0, NULL)


/**
 * Create "suspend" action.
 * If function failed for any reason, the action is automatically
 * set to "stop with error".
 *
 * At most one DCC action can be created for one content callback.
 *
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @return the pointer to the action if succeed,
 *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
 */
MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
MHD_DCC_action_suspend (struct MHD_DynamicContentCreatorContext *ctx)
MHD_FN_PAR_NONNULL_ (1);

/**
 * Create "stop with error" action.
 * @param[in,out] ctx the pointer the context as provided to the callback
 * @return always NULL (the action "stop with error")
 */
#define MHD_DCC_action_abort(ctx) \
        MHD_STATIC_CAST_ (const struct MHD_DynamicContentCreatorAction *, NULL)

/**
 * Callback used by libmicrohttpd in order to obtain content.  The
 * callback is to copy at most @a max bytes of content into @a buf or
 * provide zero-copy data for #MHD_DCC_action_continue_zc().
 *
 * @param dyn_cont_cls closure argument to the callback
 * @param ctx the context to produce the action to return,
 *            the pointer is only valid until the callback returns
 * @param pos position in the datastream to access;
 *        note that if a `struct MHD_Response` object is re-used,
 *        it is possible for the same content reader to
 *        be queried multiple times for the same data;
 *        however, if a `struct MHD_Response` is not re-used,
 *        libmicrohttpd guarantees that "pos" will be
 *        the sum of all data sizes provided by this callback
 * @param[out] buf where to copy the data
 * @param max maximum number of bytes to copy to @a buf (size of @a buf),
              if the size of the content of the response is known then size
              of the buffer is never larger than amount of the content left
 * @return action to use,
 *         NULL in case of any error (the response will be aborted)
 */
typedef const struct MHD_DynamicContentCreatorAction *
(MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_NONNULL_ (4)
 *MHD_DynamicContentCreator)(void *dyn_cont_cls,
                             struct MHD_DynamicContentCreatorContext *ctx,
                             uint_fast64_t pos,
                             void *buf,
                             size_t max);


/**
 * Create a response.  The response object can be extended with
 * header information.
 *
 * @param sc status code to return
 * @param size size of the data portion of the response, #MHD_SIZE_UNKNOWN for unknown
 * @param dyn_cont callback to use to obtain response data
 * @param dyn_cont_cls extra argument to @a crc
 * @param dyn_cont_fc callback to call to free @a dyn_cont_cls resources
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * FIXME: Call free callback on error?
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_callback (enum MHD_HTTP_StatusCode sc,
                            uint_fast64_t size,
                            MHD_DynamicContentCreator dyn_cont,
                            void *dyn_cont_cls,
                            MHD_FreeCallback dyn_cont_fc);


/**
 * Create a response object.  The response object can be extended with
 * header information.
 *
 * @param sc status code to use for the response;
 *           #MHD_HTTP_STATUS_NO_CONTENT is only valid if @a size is 0;
 * @param buffer_size the size of the data portion of the response
 * @param buffer the @a size bytes containing the response's data portion,
 *               needs to be valid while the response is used
 * @param free_cb the callback to free any allocated data, called
 *                when response is being destroyed, can be NULL
 *                to skip the free/cleanup callback;
 * @param free_cb_cls the parameter for @a free_cb
 * @return NULL on error (i.e. invalid arguments, out of memory)
 *   on error, @a free_cb is NOT called
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_buffer (
  enum MHD_HTTP_StatusCode sc,
  size_t buffer_size,
  const char *buffer,
  MHD_FreeCallback free_cb,
  void *free_cb_cls)
MHD_FN_PAR_IN_SIZE_ (3, 2);


/**
 * Create a response object with body that is a
 * statically allocated buffer that never needs to
 * be freed as its lifetime exceeds that of the
 * daemon.
 *
 * The response object can be extended with header information and then be used
 * any number of times.
 * @param sc status code to use for the response
 * @param len number of bytes in @a buf
 * @param buf buffer with response payload
 */
#define MHD_response_from_buffer_static(sc, len, buf)       \
        MHD_response_from_buffer (sc, len, buf, NULL, NULL)


/**
 * Create a response object with empty (zero size) body.
 *
 * The response object can be extended with header information and then be used
 * any number of times.
 * @param sc status code to use for the response
 */
#define MHD_response_from_empty(sc) \
        MHD_response_from_buffer_static (sc, 0, "")


/**
 * Create a response object.  The response object can be extended with
 * header information.
 *
 * @param sc status code to use for the response
 * @param buffer_size the size of the data portion of the response
 * @param buffer the @a size bytes containing the response's data portion,
 *               an internal copy will be made, there is no need to
 *               keep this data after return from this function
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * FIXME: Call free callback on error?
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_buffer_copy (
  enum MHD_HTTP_StatusCode sc,
  size_t buffer_size,
  const char buffer[MHD_FN_PAR_DYN_ARR_SIZE_ (buffer_size)])
MHD_FN_PAR_IN_SIZE_ (3, 2);


/**
 * I/O vector type. Provided for use with #MHD_response_from_iovec().
 * @ingroup response
 */
struct MHD_IoVec
{
  /**
   * The pointer to the memory region for I/O.
   */
  const void *iov_base;

  /**
   * The size in bytes of the memory region for I/O.
   */
  size_t iov_len;
};


/**
 * Create a response object with an array of memory buffers
 * used as the response body.
 *
 * The response object can be extended with header information.
 *
 * If response object is used to answer HEAD request then the body
 * of the response is not used, while all headers (including automatic
 * headers) are used.
 *
 * @param sc status code to use for the response
 * @param iov_count the number of elements in @a iov
 * @param iov the array for response data buffers, an internal copy of this
 *        will be made
 * @param free_cb the callback to clean up any data associated with @a iov when
 *        the response is destroyed.
 * @param free_cb_cls the argument passed to @a free_cb
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * FIXME: Call free callback on error?
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_iovec (
  enum MHD_HTTP_StatusCode sc,
  unsigned int iov_count,
  const struct MHD_IoVec iov[MHD_FN_PAR_DYN_ARR_SIZE_ (iov_count)],
  MHD_FreeCallback free_cb,
  void *free_cb_cls);


/**
 * Create a response object based on an @a fd from which
 * data is read.  The response object can be extended with
 * header information.
 *
 * @param sc status code to return
 * @param fd file descriptor referring to a file on disk with the
 *        data; will be closed when response is destroyed;
 *        fd should be in 'blocking' mode
 * @param offset offset to start reading from in the file;
 *        reading file beyond 2 GiB may be not supported by OS or
 *        MHD build; see #MHD_LIB_INFO_FIXED_HAS_LARGE_FILE
 * @param size size of the data portion of the response;
 *        sizes larger than 2 GiB may be not supported by OS or
 *        MHD build; see #MHD_LIB_INFO_FIXED_HAS_LARGE_FILE
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * FIXME: Close FD on error?
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_fd (enum MHD_HTTP_StatusCode sc,
                      int fd,
                      uint_fast64_t offset,
                      uint_fast64_t size)
MHD_FN_PAR_FD_READ_ (2);

/**
 * Create a response object with the response body created by reading
 * the provided pipe.
 *
 * The response object can be extended with header information and
 * then be used ONLY ONCE.
 *
 * If response object is used to answer HEAD request then the body
 * of the response is not used, while all headers (including automatic
 * headers) are used.
 *
 * @param sc status code to use for the response
 * @param fd file descriptor referring to a read-end of a pipe with the
 *        data; will be closed when response is destroyed;
 *        fd should be in 'blocking' mode
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * FIXME: Close pipe FD on error?
 * @ingroup response
 */
MHD_EXTERN_ struct MHD_Response *
MHD_response_from_pipe (enum MHD_HTTP_StatusCode sc,
                        int fd)
MHD_FN_PAR_FD_READ_ (2);


/**
 * Destroy response.
 * Should be called if response was created but not consumed.
 * Also must be called if response has #MHD_R_O_REUSABLE set.
 * The actual destroy can be happen later, if the response
 * is still being used in any request.
 * The function does not block.
 *
 * @param[in] response the response to destroy
 * @ingroup response
 */
MHD_EXTERN_ void
MHD_response_destroy (struct MHD_Response *response)
MHD_FN_PAR_NONNULL_ (1);


/**
 * Add a header line to the response.
 *
 * @param response response to add a header to, NULL is tolerated
 * @param name the name of the header to add,
 *             an internal copy of the string will be made
 * @param value the value of the header to add,
 *              an internal copy of the string will be made
 * @return #MHD_SC_OK on success,
 *         error code otherwise
 * @ingroup response
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_response_add_header (struct MHD_Response *MHD_RESTRICT response,
                         const char *MHD_RESTRICT name,
                         const char *MHD_RESTRICT value)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3);


/**
 * Add a header with predefined (standard) name to the response.
 *
 * @param response response to add a header to
 * @param stk the code of the predefined header
 * @param content the value of the header to add,
 *              an internal copy of the string will be made
 * @return #MHD_SC_OK on success,
 *         error code otherwise
 * @ingroup response
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_response_add_predef_header (struct MHD_Response *MHD_RESTRICT response,
                                enum MHD_PredefinedHeader stk,
                                const char *MHD_RESTRICT content)
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3);


/* ************ (b) Upload and PostProcessor functions ********************** */


/**
 * Suspend handling of network data for a given request.  This can
 * be used to dequeue a request from MHD's event loop for a while.
 *
 * Suspended requests continue to count against the total number of
 * requests allowed (per daemon, as well as per IP, if such limits
 * are set).  Suspended requests will NOT time out; timeouts will
 * restart when the request handling is resumed.  While a
 * request is suspended, MHD may not detect disconnects by the
 * client.
 *
 * At most one upload action can be created for one upload callback.
 *
 * @param[in,out] request the request for which the action is generated
 * @return action to cause a request to be suspended,
 *         NULL if any action has been already created for the @a request
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_UploadAction *
MHD_upload_action_suspend (struct MHD_Request *request)
MHD_FN_PAR_NONNULL_ALL_;

/**
 * Converts a @a response to an action.  If #MHD_R_O_REUSABLE
 * is not set, the reference to the @a response is consumed
 * by the conversion. If #MHD_R_O_REUSABLE is #MHD_YES,
 * then the @a response can be used again to create actions in
 * the future.
 * However, the @a response is frozen by this step and
 * must no longer be modified (i.e. by setting headers).
 *
 * At most one upload action can be created for one upload callback.
 *
 * @param request the request to create the action for
 * @param[in] response the response to convert,
 *                     if NULL then this function is equivalent to
 *                     #MHD_upload_action_abort_request() call
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed (no memory) or if any action has been already
 *         created for the @a request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_UploadAction *
MHD_upload_action_from_response (struct MHD_Request *MHD_RESTRICT request,
                                 struct MHD_Response *MHD_RESTRICT response)
MHD_FN_PAR_NONNULL_ (1);

/**
 * Action telling MHD to continue processing the upload.
 * Valid only for incremental upload processing.
 * Works as #MHD_upload_action_abort_request() if used for full upload callback
 * or for the final (with zero data) incremental callback.
 *
 * At most one upload action can be created for one upload callback.
 *
 * @param request the request to make an action
 * @return action operation,
 *         NULL if any action has been already created for the @a request
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_UploadAction *
MHD_upload_action_continue (struct MHD_Request *request)
MHD_FN_PAR_NONNULL_ (1);


/**
 * Action telling MHD to close the connection hard
 * (kind-of breaking HTTP specification).
 *
 * @param req the request to make an action
 * @return action operation, always NULL
 * @ingroup action
 */
#define MHD_upload_action_abort_request(req) \
        MHD_STATIC_CAST_ (const struct MHD_UploadAction *, NULL)

#ifndef MHD_UPLOADCALLBACK_DEFINED

/**
 * Function to process data uploaded by a client.
 *
 * @param upload_cls the argument given together with the function
 *                   pointer when the handler was registered with MHD
 * @param request the request is being processed
 * @param content_data_size the size of the @a content_data,
 *                          zero when all data have been processed
 * @param[in] content_data the uploaded content data,
 *                         may be modified in the callback,
 *                         valid only until return from the callback,
 *                         NULL when all data have been processed
 * @return action specifying how to proceed:
 *         #MHD_upload_action_continue() to continue upload (for incremental
 *         upload processing only),
 *         #MHD_upload_action_suspend() to stop reading the upload until
 *         the request is resumed,
 *         #MHD_upload_action_abort_request() to close the socket,
 *         or a response to discard the rest of the upload and transmit
 *         the response
 * @ingroup action
 */
typedef const struct MHD_UploadAction *
(MHD_FN_PAR_NONNULL_ (2)  MHD_FN_PAR_INOUT_SIZE_ (4, 3)
 *MHD_UploadCallback)(void *upload_cls,
                      struct MHD_Request *request,
                      size_t content_data_size,
                      void *content_data);

#  define MHD_UPLOADCALLBACK_DEFINED 1
#endif /* ! MHD_UPLOADCALLBACK_DEFINED */

/**
 * Create an action that handles an upload.
 *
 * If @a uc_inc is NULL and upload cannot fit the allocated buffer
 * then request is aborted without response.
 *
 * At most one action can be created for any request.
 *
 * @param request the request to create action for
 * @param large_buffer_size how large should the upload buffer be.
 *                          May allocate memory from the shared "large"
 *                          memory pool if necessary and non-zero is given.
 *                          Must be zero if @a uc_full is NULL.
 * @param uc_full the function to call when complete upload
 *                is received (only if fit @a upload_buffer_size),
 *                can be NULL if uc_inc is not NULL,
 *                must be NULL is @a upload_buffer_size is zero.
 * @param uc_full_cls closure for @a uc_full
 * @param uc_inc the function to incrementally process the upload data
 *               if the upload if larger than @a upload_buffer_size or
 *               @a upload_buffer_size cannot be allocated or
 *               @a uc_full is NULL,
 *               can be NULL if uc_full is not NULL
 * @param uc_inc_cls closure for @a uc_inc
 * @return NULL on error (out of memory, invalid parameters)
 * @return pointer to the action,
 *         NULL if failed (no memory) or if any action has been already
 *         created for the @a request.
 * @sa #MHD_D_OPTION_LARGE_POOL_SIZE()
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_Action *
MHD_action_process_upload (
  struct MHD_Request *request,
  size_t large_buffer_size,
  MHD_UploadCallback uc_full,
  void *uc_full_cls,
  MHD_UploadCallback uc_inc,
  void *uc_inc_cls)
MHD_FN_PAR_NONNULL_ (1);

/**
 * Create an action that handles an upload as full upload data.
 *
 * @param request the request to create action for
 * @param buff_size how large should the upload buffer be. May allocate memory
 *                  from the large memory pool if necessary. Must not be zero.
 * @param uc the function to call when complete upload
 *           is received (only if fit @a upload_buffer_size)
 * @param uc_cls closure for @a uc
 * @return NULL on error (out of memory. both @a uc is NULL)
 * @ingroup action
 */
#define MHD_action_process_upload_full(request, buff_size, uc, uc_cls) \
        MHD_action_process_upload (request, buff_size, uc, uc_cls, NULL, NULL)

/**
 * Create an action that handles an upload incrementally.
 *
 * @param request the request to create action for
 * @param uc the function to incrementally process the upload data
 * @param uc_cls closure for @a uc
 * @return NULL on error (out of memory. both @a uc is NULL)
 * @ingroup action
 */
#define MHD_action_process_upload_inc(request, uc, uc_cls) \
        MHD_action_process_upload (request, 0, NULL, NULL, uc, uc_cls)

#ifndef MHD_POST_PARSE_RESULT_DEFINED

/**
 * The result of POST data parsing
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_PostParseResult
{
  /**
   * The POST data parsed successfully and completely.
   */
  MHD_POST_PARSE_RES_OK = 0
  ,
  /**
   * The POST request has no content or zero-length content.
   */
  MHD_POST_PARSE_RES_REQUEST_EMPTY = 1
  ,
  /**
   * The POST data parsed successfully, but has missing or incorrect
   * termination.
   * The last parsed field may have incorrect data.
   */
  MHD_POST_PARSE_RES_OK_BAD_TERMINATION = 2
  ,
  /**
   * Parsing of the POST data is incomplete because client used incorrect
   * format of POST encoding.
   * The last parsed field may have incorrect data.
   * Some POST data is available or has been provided via callback.
   */
  MHD_POST_PARSE_RES_PARTIAL_INVALID_POST_FORMAT = 3
  ,
  /**
   * The POST data cannot be parsed completely because the stream has
   * no free pool memory.
   * Some POST data may be parsed.
   */
  MHD_POST_PARSE_RES_FAILED_NO_POOL_MEM = 60
  ,
  /**
   * The POST data cannot be parsed completely because no "large shared buffer"
   * space is available.
   * Some POST data may be parsed.
   */
  MHD_POST_PARSE_RES_FAILED_NO_LARGE_BUF_MEM = 61
  ,
  /**
   * The POST data cannot be parsed because 'Content-Type:' is unknown.
   */
  MHD_POST_PARSE_RES_FAILED_UNKNOWN_CNTN_TYPE = 80
  ,
  /**
   * The POST data cannot be parsed because 'Content-Type:' header is not set.
   */
  MHD_POST_PARSE_RES_FAILED_NO_CNTN_TYPE = 81
  ,
  /**
   * The POST data cannot be parsed because "Content-Type:" request header has
   * no "boundary" parameter for "multipart/form-data"
   */
  MHD_POST_PARSE_RES_FAILED_HEADER_NO_BOUNDARY = 82
  ,
  /**
   * The POST data cannot be parsed because "Content-Type: multipart/form-data"
   * request header is misformed
   */
  MHD_POST_PARSE_RES_FAILED_HEADER_MISFORMED = 83
  ,
  /**
   * The application set POST encoding to "multipart/form-data", but the request
   * has no "Content-Type: multipart/form-data" header which is required
   * to find "boundary" used in this encoding
   */
  MHD_POST_PARSE_RES_FAILED_HEADER_NOT_MPART = 84
  ,
  /**
   * The POST data cannot be parsed because client used incorrect format
   * of POST encoding.
   */
  MHD_POST_PARSE_RES_FAILED_INVALID_POST_FORMAT = 90

};

#  define MHD_POST_PARSE_RESULT_DEFINED 1
#endif /* ! MHD_POST_PARSE_RESULT_DEFINED */

#ifndef MHD_POST_DATA_READER_DEFINED

/**
 * "Stream" reader for POST data.
 * This callback is called to incrementally process parsed POST data sent by
 * the client.
 * The pointers to the MHD_String and MHD_StringNullable are valid only until
 * return from this callback.
 * The pointers to the strings and the @a data are valid only until return from
 * this callback.
 *
 * @param req the request
 * @param cls user-specified closure
 * @param name the name of the POST field
 * @param filename the name of the uploaded file, @a cstr member is NULL if not
 *                 known / not provided
 * @param content_type the mime-type of the data, cstr member is NULL if not
 *                     known / not provided
 * @param encoding the encoding of the data, cstr member is NULL if not known /
 *                 not provided
 * @param size the number of bytes in @a data available, may be zero if
 *             the @a final_data is #MHD_YES
 * @param data the pointer to @a size bytes of data at the specified
 *             @a off offset, NOT zero-terminated
 * @param off the offset of @a data in the overall value, always equal to
 *            the sum of sizes of previous calls for the same field / file;
 *            client may provide more than one field with the same name and
 *            the same filename, the new filed (or file) is indicated by zero
 *            value of @a off (and the end is indicated by @a final_data)
 * @param final_data if set to #MHD_YES then full field data is provided,
 *                   if set to #MHD_NO then more field data may be provided
 * @return action specifying how to proceed:
 *         #MHD_upload_action_continue() if all is well,
 *         #MHD_upload_action_suspend() to stop reading the upload until
 *         the request is resumed,
 *         #MHD_upload_action_abort_request() to close the socket,
 *         or a response to discard the rest of the upload and transmit
 *         the response
 * @ingroup action
 */
typedef const struct MHD_UploadAction *
(MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_NONNULL_ (4)
 MHD_FN_PAR_NONNULL_ (5) MHD_FN_PAR_NONNULL_ (6)
 *MHD_PostDataReader) (struct MHD_Request *req,
                       void *cls,
                       const struct MHD_String *name,
                       const struct MHD_StringNullable *filename,
                       const struct MHD_StringNullable *content_type,
                       const struct MHD_StringNullable *encoding,
                       size_t size,
                       const void *data,
                       uint_fast64_t off,
                       enum MHD_Bool final_data);


/**
 * The callback to be called when finished with processing
 * of the postprocessor upload data.
 * @param req the request
 * @param cls the closure
 * @param parsing_result the result of POST data parsing
 * @return the action to proceed
 */
typedef const struct MHD_UploadAction *
(MHD_FN_PAR_NONNULL_ (1)
 *MHD_PostDataFinished) (struct MHD_Request *req,
                         void *cls,
                         enum MHD_PostParseResult parsing_result);

#  define MHD_POST_DATA_READER_DEFINED 1
#endif /* ! MHD_POST_DATA_READER_DEFINED */

/**
 * Create an action to parse the POSTed content from the client.
 *
 * The action starts parsing of the POST data. Any value that does not fit
 * @a buffer_size or larger that @a auto_stream_size is given to
 * @a stream_reader (if it is not NULL).
 *
 * If @a buffer_size is zero, then buffers will be limited to the connection's
 * memory pool. To force all POST data process via @a stream_reader
 * set @a auto_stream_size to zero.
 *
 * At most one action can be created for any request.
 *
 * @param request the request to create action for
 * @param buffer_size the maximum size allowed for the buffers to parse this
 *                    request POST data. Within the set limit the buffer is
 *                    allocated automatically from the "large" shared memory
 *                    pool if necessary.
 * @param max_nonstream_size the size of the field (in encoded form) above which
 *                           values are not buffered and provided for
 *                           the @a steam_reader automatically;
 *                           useful to have large data (like file uploads)
 *                           processed incrementally, while keeping buffer space
 *                           for small fields only;
 *                           ignored if @a stream_reader is NULL
 * @param enc the data encoding to use,
 *            use #MHD_HTTP_POST_ENCODING_OTHER to detect automatically
 * @param stream_reader the function to call for "oversize" values in
 *                      the stream; can be NULL if @a auto_stream_size is
 *                      not zero
 * @param reader_cls the closure for the @a stream_reader
 * @param done_cb called once all data has been processed for
 *   the final action; values smaller than @a auto_stream_size that
 *   fit into @a buffer_size will be available via
 *   #MHD_request_get_values_cb(), #MHD_request_get_values_list() and
 *   #MHD_request_get_post_data_cb(), #MHD_request_get_post_data_list()
 * @param done_cb_cls the closure for the @a done_cb
 * @return pointer to the action,
 *         NULL if failed (no memory) or if any action has been already
 *         created for the @a request.
 * @sa #MHD_D_OPTION_LARGE_POOL_SIZE()
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_Action *
MHD_action_parse_post (struct MHD_Request *request,
                       size_t buffer_size,
                       size_t max_nonstream_size,
                       enum MHD_HTTP_PostEncoding enc,
                       MHD_PostDataReader stream_reader,
                       void *reader_cls,
                       MHD_PostDataFinished done_cb,
                       void *done_cb_cls)
MHD_FN_PAR_NONNULL_ (1);


#ifndef MHD_POSTFILED_DEFINED

/**
 * Post data element.
 * If any member is not provided/set then pointer to C string is NULL.
 * If any member is set to empty string then pointer to C string not NULL,
 * but the length is zero.
 */
struct MHD_PostField
{
  /**
   * The name of the field
   */
  struct MHD_String name;
  /**
   * The field data
   * If not set or defined then to C string is NULL.
   * If set to empty string then pointer to C string not NULL,
   * but the length is zero.
   */
  struct MHD_StringNullable value;
  /**
   * The filename if provided (only for "multipart/form-data")
   * If not set or defined then to C string is NULL.
   * If set to empty string then pointer to C string not NULL,
   * but the length is zero.
   */
  struct MHD_StringNullable filename;
  /**
   * The Content-Type if provided (only for "multipart/form-data")
   * If not set or defined then to C string is NULL.
   * If set to empty string then pointer to C string not NULL,
   * but the length is zero.
   */
  struct MHD_StringNullable content_type;
  /**
   * The Transfer-Encoding if provided (only for "multipart/form-data")
   * If not set or defined then to C string is NULL.
   * If set to empty string then pointer to C string not NULL,
   * but the length is zero.
   */
  struct MHD_StringNullable transfer_encoding;
};

#  define MHD_POSTFILED_DEFINED 1
#endif /* ! MHD_POSTFILED_DEFINED */


/**
 * Iterator over POST data.
 *
 * The @a data pointer is valid only until return from this function.
 *
 * The pointers to the strings in @a data are valid until any MHD_UploadAction
 * is provided. If the data is needed beyond this point, it should be copied.
 *
 * @param cls closure
 * @param data the element of the post data, the pointer is valid only until
 *             return from this function
 * @return #MHD_YES to continue iterating,
 *         #MHD_NO to abort the iteration
 * @ingroup request
 */
typedef enum MHD_Bool
(MHD_FN_PAR_NONNULL_ (2)
 *MHD_PostDataIterator)(void *cls,
                        const struct MHD_PostField *data);

/**
 * Get all of the post data from the request via request.
 *
 * @param request the request to get data for
 * @param iterator callback to call on each header;
 *        maybe NULL (then just count headers)
 * @param iterator_cls extra argument to @a iterator
 * @return number of entries iterated over
 * @ingroup request
 */
MHD_EXTERN_ size_t
MHD_request_get_post_data_cb (struct MHD_Request *request,
                              MHD_PostDataIterator iterator,
                              void *iterator_cls)
MHD_FN_PAR_NONNULL_ (1);

/**
 * Get all of the post data from the request.
 *
 * The pointers to the strings in @a elements are valid until any
 * MHD_UploadAction is provided. If the data is needed beyond this point,
 * it should be copied.
 * @param request the request to get data for
 * @param num_elements the number of elements in @a elements array
 * @param[out] elements the array of @a num_elements to get the data
 * @return the number of elements stored in @a elements,
 *         zero if no data or postprocessor was not used.
 * @ingroup request
 */
MHD_EXTERN_ size_t
MHD_request_get_post_data_list (
  struct MHD_Request *request,
  size_t num_elements,
  struct MHD_PostField elements[MHD_FN_PAR_DYN_ARR_SIZE_ (num_elements)])
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_SIZE_ (3, 2);

/* ***************** (c) WebSocket support ********** */

/**
 * Handle given to the application to manage special
 * actions relating to MHD responses that "upgrade"
 * the HTTP protocol (i.e. to WebSockets).
 */
struct MHD_UpgradedHandle;


#ifndef MHD_UPGRADEHANDLER_DEFINED

/**
 * Function called after a protocol "upgrade" response was sent successfully
 * and the connection is being switched to other protocol.
 *
 * The newly provided handle @a urh can be used to send and receive the data
 * by #MHD_upgraded_send() and #MHD_upgraded_recv(). The handle must be closed
 * by #MHD_upgraded_close() before destroying the daemon.
 *
 * "Upgraded" connection will not time out, but still counted for daemon
 * global connections limit and for per-IP limit (if set).
 *
 * Except when in 'thread-per-connection' mode, implementations
 * of this function should never block (as it will still be called
 * from within the main event loop).
 *
 * @param cls closure, whatever was given to #MHD_action_upgrade().
 * @param request original HTTP request handle,
 *                giving the function a last chance
 *                to inspect the original HTTP request
 * @param urh argument for #MHD_upgrade_operation() on this @a response.
 *        Applications must eventually use this callback to (indirectly)
 *        perform the close() action on the @a sock.
 */
typedef void
(MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_NONNULL_ (3)
 *MHD_UpgradeHandler)(void *cls,
                      struct MHD_Request *MHD_RESTRICT request,
                      struct MHD_UpgradedHandle *MHD_RESTRICT urh);

#  define MHD_UPGRADEHANDLER_DEFINED 1
#endif /* ! MHD_UPGRADEHANDLER_DEFINED */


/**
 * Create a action object that can be used for 101 Upgrade
 * responses, for example to implement WebSockets.  After sending the
 * response, control over the data stream is given to the callback (which
 * can then, for example, start some bi-directional communication).
 * The callback will ONLY be called after the response header was successfully
 * passed to the OS; if there are communication errors before, the usual MHD
 * connection error handling code will be performed.
 *
 * At most one action can be created for any request.
 *
 * @param request the request to create action for
 * @param upgrade_hdr_value the value of the "Upgrade:" header, mandatory
                            string
 * @param upgrade_handler function to call with the "upgraded" socket
 * @param upgrade_handler_cls closure for @a upgrade_handler
 * @param num_headers number of elements in the @a headers array,
 *                    must be zero if @a headers is NULL
 * @param headers the optional pointer to the array of the headers (the strings
 *                are copied and does not need to be valid after return from
 *                this function),
 *                can be NULL if @a num_headers is zero
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_Action *
MHD_action_upgrade (struct MHD_Request *MHD_RESTRICT request,
                    const char *MHD_RESTRICT upgrade_hdr_value,
                    MHD_UpgradeHandler upgrade_handler,
                    void *upgrade_handler_cls,
                    size_t num_headers,
                    const struct MHD_NameValueCStr *MHD_RESTRICT headers)
MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_IN_SIZE_ (6, 5);


/**
 * Create a action object that can be used for 101 Upgrade
 * responses, for example to implement WebSockets.  After sending the
 * response, control over the data stream is given to the callback (which
 * can then, for example, start some bi-directional communication).
 * The callback will ONLY be called after the response header was successfully
 * passed to the OS; if there are communication errors before, the usual MHD
 * connection error handling code will be performed.
 *
 * At most one action can be created for any request.
 *
 * @param request the request to create action for
 * @param upgrade_hdr_value the value of the "Upgrade:" header, mandatory
                            string
 * @param upgrade_handler function to call with the "upgraded" socket
 * @param upgrade_handler_cls closure for @a upgrade_handler
 * @param num_headers number of elements in the @a headers array,
 *                    must be zero if @a headers is NULL
 * @param headers the optional pointer to the array of the headers (the strings
 *                are copied and does not need to be valid after return from
 *                this function),
 *                can be NULL if @a num_headers is zero
 * @return NULL on error (i.e. invalid arguments, out of memory)
 * @ingroup action
 */
MHD_EXTERN_ const struct MHD_UploadAction *
MHD_upload_action_upgrade (
  struct MHD_Request *MHD_RESTRICT request,
  const char *MHD_RESTRICT upgrade_hdr_value,
  MHD_UpgradeHandler upgrade_handler,
  void *upgrade_handler_cls,
  size_t num_headers,
  const struct MHD_NameValueCStr *MHD_RESTRICT headers)
MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_IN_SIZE_ (6, 5);


/**
 * Receive data on the HTTP-Upgraded connection.
 *
 * The function finished if one of the following happens:
 * + ANY amount of data has been received,
 * + timeout reached,
 * + network error occurs
 *
 * @param urh the HTTP-Upgraded handle
 * @param recv_buf_size the size of the @a recv_buf
 * @param recv_buf the buffer to receive the data
 * @param received_size the pointer to variable to get amount of received data
 * @param max_wait_millisec the maximum wait time for the data,
 *                          non-blocking operation if set to zero,
 *                          wait indefinitely if larger or equal to
 *                          #MHD_WAIT_INDEFINITELY,
 *                          the function may return earlier if waiting is
 *                          interrupted or by other reasons
 * @return #MHD_SC_OK if ANY data received (check the @a received_size) or
 *                    remote shut down send side (indicated by @a received_size
 *                    set to zero),
 *         #MHD_SC_UPGRADED_NET_TIMEOUT if NO data received but timeout expired,
 *         #MHD_SC_UPGRADED_NET_CONN_CLOSED if network connection has been
 *                                          closed,
 *         #MHD_SC_UPGRADED_NET_CONN_BROKEN if broken network connection has
 *                                          been detected,
 *         #MHD_SC_UPGRADED_TLS_ERROR if TLS error occurs (only for TLS),
 *         #MHD_SC_UPGRADED_NET_HARD_ERROR if any other network or sockets
 *                                         unrecoverable error occurs,
 *         #MHD_SC_UPGRADED_HANDLE_INVALID if @a urh is invalid,
 *         #MHD_SC_UPGRADED_WAITING_NOT_SUPPORTED if timed wait is not supported
 *                                                by this MHD build or platform
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_upgraded_recv (struct MHD_UpgradedHandle *MHD_RESTRICT urh,
                   size_t recv_buf_size,
                   void *MHD_RESTRICT recv_buf,
                   size_t *MHD_RESTRICT received_size,
                   uint_fast64_t max_wait_millisec)
MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_OUT_SIZE_ (3, 2)
MHD_FN_PAR_OUT_ (4);


/**
 * Send data on the HTTP-Upgraded connection.
 *
 * The function finished if one of the following happens:
 * + ALL provided data has been sent,
 * + timeout reached,
 * + network error occurs
 *
 * Parameter @a more_data_to_come controls network buffering. When set to
 * #MHD_YES, the OS waits shortly for additional data and tries to use
 * the network more effeciently delaying the last network packet, if it is
 * incomplete, to combine it with the next data provided.
 *
 * @param urh the HTTP-Upgraded handle
 * @param send_buf_size the amount of data in the @a send_buf
 * @param send_buf the buffer with the data to send
 * @param sent_size the pointer to get the amout of sent data
 * @param max_wait_millisec the maximum wait time for the data,
 *                          non-blocking operation if set to zero,
 *                          wait indefinitely if larger or equal to
 *                          #MHD_WAIT_INDEFINITELY
 * @param more_data_to_come set to #MHD_YES if the provided data in
 *                          the @a send_buf is part of a larger data package,
 *                          like an incomplete message or streamed
 *                          (not the final) part of some file, and more data
 *                          expected to be sent soon over the same connection,
 *                          set to #MHD_NO the data in the @a send_buf is
 *                          the complete message or the final part of
 *                          the message (or file) and it should be pushed
 *                          to the network (and to the client) as soon
 *                          as possible
 * @return #MHD_SC_OK if ANY data sent (check the @a sent_size),
 *         #MHD_SC_UPGRADED_NET_TIMEOUT if NO data sent but timeout expired,
 *         #MHD_SC_UPGRADED_NET_CONN_CLOSED if network connection has been
 *                                          closed,
 *         #MHD_SC_UPGRADED_NET_CONN_BROKEN if broken network connection has
 *                                          been detected,
 *         #MHD_SC_UPGRADED_TLS_ERROR if TLS error occurs (only for TLS),
 *         #MHD_SC_UPGRADED_NET_HARD_ERROR if any other network or sockets
 *                                         unrecoverable error occurs,
 *         #MHD_SC_UPGRADED_HANDLE_INVALID if @a urh is invalid,
 *         #MHD_SC_UPGRADED_WAITING_NOT_SUPPORTED if timed wait is not supported
 *                                                by this MHD build or platform
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_upgraded_send (struct MHD_UpgradedHandle *MHD_RESTRICT urh,
                   size_t send_buf_size,
                   const void *MHD_RESTRICT send_buf,
                   size_t *MHD_RESTRICT sent_size,
                   uint_fast64_t max_wait_millisec,
                   enum MHD_Bool more_data_to_come)
MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_IN_SIZE_ (3, 2)
MHD_FN_PAR_OUT_ (4);


/**
 * Close HTTP-Upgraded connection handle.
 *
 * The handle cannot be used after successful return from this function.
 *
 * The function cannot fail if called correctly (the daemon is not destroyed
 * and the upgraded connection has not been closed yet).
 *
 * @param urh the handle to close
 * @return #MHD_SC_OK on success,
 *         error code otherwise
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_upgraded_close (struct MHD_UpgradedHandle *urh)
MHD_FN_PAR_NONNULL_ (1);


/* ********************** (e) Client auth ********************** */


/**
 * Length of the binary output of the MD5 hash function.
 * @sa #MHD_digest_get_hash_size()
 * @ingroup authentication
 */
#define MHD_MD5_DIGEST_SIZE 16

/**
 * Length of the binary output of the SHA-256 hash function.
 * @sa #MHD_digest_get_hash_size()
 * @ingroup authentication
 */
#define MHD_SHA256_DIGEST_SIZE 32

/**
 * Length of the binary output of the SHA-512/256 hash function.
 * @warning While this value is the same as the #MHD_SHA256_DIGEST_SIZE,
 *          the calculated digests for SHA-256 and SHA-512/256 are different.
 * @sa #MHD_digest_get_hash_size()
 * @ingroup authentication
 */
#define MHD_SHA512_256_DIGEST_SIZE 32

/**
 * Base type of hash calculation.
 * Used as part of #MHD_DigestAuthAlgo values.
 *
 * @warning Not used directly by MHD API.
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestBaseAlgo
{
  /**
   * Invalid hash algorithm value
   */
  MHD_DIGEST_BASE_ALGO_INVALID = 0
  ,
  /**
   * MD5 hash algorithm.
   * As specified by RFC1321
   */
  MHD_DIGEST_BASE_ALGO_MD5 = (1u << 0)
  ,
  /**
   * SHA-256 hash algorithm.
   * As specified by FIPS PUB 180-4
   */
  MHD_DIGEST_BASE_ALGO_SHA256 = (1u << 1)
  ,
  /**
   * SHA-512/256 hash algorithm.
   * As specified by FIPS PUB 180-4
   */
  MHD_DIGEST_BASE_ALGO_SHA512_256 = (1u << 2)
};

/**
 * The flag indicating non-session algorithm types,
 * like 'MD5', 'SHA-256' or 'SHA-512-256'.
 */
#define MHD_DIGEST_AUTH_ALGO_NON_SESSION    (1u << 6)

/**
 * The flag indicating session algorithm types,
 * like 'MD5-sess', 'SHA-256-sess' or 'SHA-512-256-sess'.
 */
#define MHD_DIGEST_AUTH_ALGO_SESSION        (1u << 7)

/**
 * Digest algorithm identification
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthAlgo
{
  /**
   * Unknown or wrong algorithm type.
   * Used in struct MHD_AuthDigestInfo to indicate client value that
   * cannot by identified.
   */
  MHD_DIGEST_AUTH_ALGO_INVALID = 0
  ,
  /**
   * The 'MD5' algorithm, non-session version.
   */
  MHD_DIGEST_AUTH_ALGO_MD5 =
    MHD_DIGEST_BASE_ALGO_MD5 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
  ,
  /**
   * The 'MD5-sess' algorithm.
   * Not supported by MHD for authentication.
   */
  MHD_DIGEST_AUTH_ALGO_MD5_SESSION =
    MHD_DIGEST_BASE_ALGO_MD5 | MHD_DIGEST_AUTH_ALGO_SESSION
  ,
  /**
   * The 'SHA-256' algorithm, non-session version.
   */
  MHD_DIGEST_AUTH_ALGO_SHA256 =
    MHD_DIGEST_BASE_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
  ,
  /**
   * The 'SHA-256-sess' algorithm.
   * Not supported by MHD for authentication.
   */
  MHD_DIGEST_AUTH_ALGO_SHA256_SESSION =
    MHD_DIGEST_BASE_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_SESSION
  ,
  /**
   * The 'SHA-512-256' (SHA-512/256) algorithm.
   */
  MHD_DIGEST_AUTH_ALGO_SHA512_256 =
    MHD_DIGEST_BASE_ALGO_SHA512_256 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
  ,
  /**
   * The 'SHA-512-256-sess' (SHA-512/256 session) algorithm.
   * Not supported by MHD for authentication.
   */
  MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION =
    MHD_DIGEST_BASE_ALGO_SHA512_256 | MHD_DIGEST_AUTH_ALGO_SESSION
};


/**
 * Get digest size in bytes for specified algorithm.
 *
 * The size of the digest specifies the size of the userhash, userdigest
 * and other parameters which size depends on used hash algorithm.
 * @param algo the algorithm to check
 * @return the size (in bytes) of the digest (either #MHD_MD5_DIGEST_SIZE or
 *         #MHD_SHA256_DIGEST_SIZE/MHD_SHA512_256_DIGEST_SIZE)
 *         or zero if the input value is not supported or not valid
 * @sa #MHD_digest_auth_calc_userdigest()
 * @sa #MHD_digest_auth_calc_userhash(), #MHD_digest_auth_calc_userhash_hex()
 * @ingroup authentication
 */
MHD_EXTERN_ size_t
MHD_digest_get_hash_size (enum MHD_DigestAuthAlgo algo)
MHD_FN_CONST_;

/**
 * Digest algorithm identification, allow multiple selection.
 *
 * #MHD_DigestAuthAlgo always can be casted to #MHD_DigestAuthMultiAlgo, but
 * not vice versa.
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthMultiAlgo
{
  /**
   * Unknown or wrong algorithm type.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_INVALID = MHD_DIGEST_AUTH_ALGO_INVALID
  ,
  /**
   * The 'MD5' algorithm, non-session version.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_MD5 = MHD_DIGEST_AUTH_ALGO_MD5
  ,
  /**
   * The 'MD5-sess' algorithm.
   * Not supported by MHD for authentication.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_MD5_SESSION = MHD_DIGEST_AUTH_ALGO_MD5_SESSION
  ,
  /**
   * The 'SHA-256' algorithm, non-session version.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA256 = MHD_DIGEST_AUTH_ALGO_SHA256
  ,
  /**
   * The 'SHA-256-sess' algorithm.
   * Not supported by MHD for authentication.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA256_SESSION =
    MHD_DIGEST_AUTH_ALGO_SHA256_SESSION
  ,
  /**
   * The 'SHA-512-256' (SHA-512/256) algorithm, non-session version.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256 = MHD_DIGEST_AUTH_ALGO_SHA512_256
  ,
  /**
   * The 'SHA-512-256-sess' (SHA-512/256 session) algorithm.
   * Not supported by MHD for authentication.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_SESSION =
    MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION
  ,
  /**
   * SHA-256 or SHA-512/256 non-session algorithm, MHD will choose
   * the preferred or the matching one.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_NON_SESSION =
    MHD_DIGEST_AUTH_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_SHA512_256
  ,
  /**
   * Any non-session algorithm, MHD will choose the preferred or
   * the matching one.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_ANY_NON_SESSION =
    (0x3F) | MHD_DIGEST_AUTH_ALGO_NON_SESSION
  ,
  /**
   * The SHA-256 or SHA-512/256 session algorithm.
   * Not supported by MHD.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_SESSION =
    MHD_DIGEST_AUTH_ALGO_SHA256_SESSION
    | MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION
  ,
  /**
   * Any session algorithm.
   * Not supported by MHD.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_ANY_SESSION =
    (0x3F) | MHD_DIGEST_AUTH_ALGO_SESSION
  ,
  /**
   * The MD5 algorithm, session or non-session.
   * Currently supported as non-session only.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_MD5_ANY =
    MHD_DIGEST_AUTH_MULT_ALGO_MD5 | MHD_DIGEST_AUTH_MULT_ALGO_MD5_SESSION
  ,
  /**
   * The SHA-256 algorithm, session or non-session.
   * Currently supported as non-session only.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA256_ANY =
    MHD_DIGEST_AUTH_MULT_ALGO_SHA256
    | MHD_DIGEST_AUTH_MULT_ALGO_SHA256_SESSION
  ,
  /**
   * The SHA-512/256 algorithm, session or non-session.
   * Currently supported as non-session only.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_ANY =
    MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256
    | MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_SESSION
  ,
  /**
   * The SHA-256 or SHA-512/256 algorithm, session or non-session.
   * Currently supported as non-session only.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_ANY =
    MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_NON_SESSION
    | MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_SESSION
  ,
  /**
   * Any algorithm, MHD will choose the preferred or the matching one.
   */
  MHD_DIGEST_AUTH_MULT_ALGO_ANY =
    (0x3F) | MHD_DIGEST_AUTH_ALGO_NON_SESSION | MHD_DIGEST_AUTH_ALGO_SESSION
};


/**
 * Calculate "userhash", return it as binary data.
 *
 * The "userhash" is the hash of the string "username:realm".
 *
 * The "userhash" could be used to avoid sending username in cleartext in Digest
 * Authorization client's header.
 *
 * Userhash is not designed to hide the username in local database or files,
 * as username in cleartext is required for #MHD_digest_auth_check() function
 * to check the response, but it can be used to hide username in HTTP headers.
 *
 * This function could be used when the new username is added to the username
 * database to save the "userhash" alongside with the username (preferably) or
 * when loading list of the usernames to generate the userhash for every loaded
 * username (this will cause delays at the start with the long lists).
 *
 * Once "userhash" is generated it could be used to identify users by clients
 * with "userhash" support.
 * Avoid repetitive usage of this function for the same username/realm
 * combination as it will cause excessive CPU load; save and reuse the result
 * instead.
 *
 * @param algo the algorithm for userhash calculations
 * @param username the username
 * @param realm the realm
 * @param[out] userhash_bin the output buffer for userhash as binary data;
 *                          if this function succeeds, then this buffer has
 *                          #MHD_digest_get_hash_size() bytes of userhash
 *                          upon return
 * @param bin_buf_size the size of the @a userhash_bin buffer, must be
 *                     at least #MHD_digest_get_hash_size() bytes long
 * @return #MHD_SC_OK on success,
 *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
 *         #MHD_SC_HASH_FAILED if hashing failed,
 *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
 *                                                unknown or unsupported.
 * @sa #MHD_digest_auth_calc_userhash_hex()
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_digest_auth_calc_userhash (enum MHD_DigestAuthAlgo algo,
                               const char *MHD_RESTRICT username,
                               const char *MHD_RESTRICT realm,
                               size_t bin_buf_size,
                               void *MHD_RESTRICT userhash_bin)
MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_OUT_SIZE_ (5, 4);


/**
 * Calculate "userhash", return it as hexadecimal string.
 *
 * The "userhash" is the hash of the string "username:realm".
 *
 * The "userhash" could be used to avoid sending username in cleartext in Digest
 * Authorization client's header.
 *
 * Userhash is not designed to hide the username in local database or files,
 * as username in cleartext is required for #MHD_digest_auth_check() function
 * to check the response, but it can be used to hide username in HTTP headers.
 *
 * This function could be used when the new username is added to the username
 * database to save the "userhash" alongside with the username (preferably) or
 * when loading list of the usernames to generate the userhash for every loaded
 * username (this will cause delays at the start with the long lists).
 *
 * Once "userhash" is generated it could be used to identify users by clients
 * with "userhash" support.
 * Avoid repetitive usage of this function for the same username/realm
 * combination as it will cause excessive CPU load; save and reuse the result
 * instead.
 *
 * @param algo the algorithm for userhash calculations
 * @param username the username
 * @param realm the realm
 * @param hex_buf_size the size of the @a userhash_hex buffer, must be
 *                     at least #MHD_digest_get_hash_size()*2+1 chars long
 * @param[out] userhash_hex the output buffer for userhash as hex string;
 *                          if this function succeeds, then this buffer has
 *                          #MHD_digest_get_hash_size()*2 chars long
 *                          userhash string plus one zero-termination char
 * @return #MHD_SC_OK on success,
 *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
 *         #MHD_SC_HASH_FAILED if hashing failed,
 *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
 *                                                unknown or unsupported.
 * @sa #MHD_digest_auth_calc_userhash()
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_digest_auth_calc_userhash_hex (
  enum MHD_DigestAuthAlgo algo,
  const char *MHD_RESTRICT username,
  const char *MHD_RESTRICT realm,
  size_t hex_buf_size,
  char userhash_hex[MHD_FN_PAR_DYN_ARR_SIZE_ (hex_buf_size)])
MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_OUT_SIZE_ (5, 4);


/**
 * The type of username used by client in Digest Authorization header
 *
 * Values are sorted so simplified checks could be used.
 * For example:
 * * (value <= MHD_DIGEST_AUTH_UNAME_TYPE_INVALID) is true if no valid username
 *   is provided by the client (not used currently)
 * * (value >= MHD_DIGEST_AUTH_UNAME_TYPE_USERHASH) is true if username is
 *   provided in any form
 * * (value >= MHD_DIGEST_AUTH_UNAME_TYPE_STANDARD) is true if username is
 *   provided in clear text (no userhash matching is needed)
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthUsernameType
{
  /**
   * No username parameter is in Digest Authorization header.
   * Not used currently. Value #MHD_SC_REQ_AUTH_DATA_BROKEN is returned
   * by #MHD_request_get_info_dynamic_sz() if the request has no username.
   */
  MHD_DIGEST_AUTH_UNAME_TYPE_MISSING = 0
  ,
  /**
   * The 'username' parameter is used to specify the username.
   */
  MHD_DIGEST_AUTH_UNAME_TYPE_STANDARD = (1u << 2)
  ,
  /**
   * The username is specified by 'username*' parameter with
   * the extended notation (see RFC 5987, section-3.2.1).
   * The only difference between standard and extended types is
   * the way how username value is encoded in the header.
   */
  MHD_DIGEST_AUTH_UNAME_TYPE_EXTENDED = (1u << 3)
  ,
  /**
   * The username provided in form of 'userhash' as
   * specified by RFC 7616, section-3.4.4.
   * @sa #MHD_digest_auth_calc_userhash_hex(), #MHD_digest_auth_calc_userhash()
   */
  MHD_DIGEST_AUTH_UNAME_TYPE_USERHASH = (1u << 1)
  ,
  /**
   * The invalid combination of username parameters are used by client.
   * Either:
   * + both 'username' and 'username*' are used
   * + 'username*' is used with 'userhash=true'
   * + 'username*' used with invalid extended notation
   * + 'username' is not hexadecimal string, while 'userhash' set to 'true'
   * Not used currently. Value #MHD_SC_REQ_AUTH_DATA_BROKEN is returned
   * by #MHD_request_get_info_dynamic_sz() if the request has broken username.
   */
  MHD_DIGEST_AUTH_UNAME_TYPE_INVALID = (1u << 0)
};

/**
 * The QOP ('quality of protection') types.
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthQOP
{
  /**
   * Invalid/unknown QOP.
   * Used in struct MHD_AuthDigestInfo to indicate client value that
   * cannot by identified.
   */
  MHD_DIGEST_AUTH_QOP_INVALID = 0
  ,
  /**
   * No QOP parameter.
   * As described in old RFC 2069 original specification.
   * This mode is not allowed by latest RFCs and should be used only to
   * communicate with clients that do not support more modern modes (with QOP
   * parameter).
   * This mode is less secure than other modes and inefficient.
   */
  MHD_DIGEST_AUTH_QOP_NONE = (1u << 0)
  ,
  /**
   * The 'auth' QOP type.
   */
  MHD_DIGEST_AUTH_QOP_AUTH = (1u << 1)
  ,
  /**
   * The 'auth-int' QOP type.
   * Not supported by MHD for authentication.
   */
  MHD_DIGEST_AUTH_QOP_AUTH_INT = (1u << 2)
};

/**
 * The QOP ('quality of protection') types, multiple selection.
 *
 * #MHD_DigestAuthQOP always can be casted to #MHD_DigestAuthMultiQOP, but
 * not vice versa.
 */
enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthMultiQOP
{
  /**
   * Invalid/unknown QOP.
   */
  MHD_DIGEST_AUTH_MULT_QOP_INVALID = MHD_DIGEST_AUTH_QOP_INVALID
  ,
  /**
   * No QOP parameter.
   * As described in old RFC 2069 original specification.
   * This mode is not allowed by latest RFCs and should be used only to
   * communicate with clients that do not support more modern modes (with QOP
   * parameter).
   * This mode is less secure than other modes and inefficient.
   */
  MHD_DIGEST_AUTH_MULT_QOP_NONE = MHD_DIGEST_AUTH_QOP_NONE
  ,
  /**
   * The 'auth' QOP type.
   */
  MHD_DIGEST_AUTH_MULT_QOP_AUTH = MHD_DIGEST_AUTH_QOP_AUTH
  ,
  /**
   * The 'auth-int' QOP type.
   * Not supported by MHD.
   * Reserved value.
   */
  MHD_DIGEST_AUTH_MULT_QOP_AUTH_INT = MHD_DIGEST_AUTH_QOP_AUTH_INT
  ,
  /**
   * The 'auth' QOP type OR the old RFC2069 (no QOP) type.
   * In other words: any types except 'auth-int'.
   * RFC2069-compatible mode is allowed, thus this value should be used only
   * when it is really necessary.
   */
  MHD_DIGEST_AUTH_MULT_QOP_ANY_NON_INT =
    MHD_DIGEST_AUTH_QOP_NONE | MHD_DIGEST_AUTH_QOP_AUTH
  ,
  /**
   * Any 'auth' QOP type ('auth' or 'auth-int').
   * Currently supported as 'auth' QOP type only.
   */
  MHD_DIGEST_AUTH_MULT_QOP_AUTH_ANY =
    MHD_DIGEST_AUTH_QOP_AUTH | MHD_DIGEST_AUTH_QOP_AUTH_INT
};

/**
 * The type of 'nc' (nonce count) value provided in the request
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthNC
{
  /**
   * Readable hexdecimal non-zero number.
   * The decoded value is placed in @a nc member of struct MHD_AuthDigestInfo
   */
  MHD_DIGEST_AUTH_NC_NUMBER = 1
  ,
  /**
   * Readable zero number.
   * Compliant clients should not use such values.
   * Can be treated as invalid request.
   */
  MHD_DIGEST_AUTH_NC_ZERO = 2
  ,
  /**
   * 'nc' value is not provided by the client.
   * Unless old RFC 2069 mode is allowed, this should be treated as invalid
   * request.
   */
  MHD_DIGEST_AUTH_NC_NONE = 3
  ,
  /**
   * 'nc' value is too long to be decoded.
   * Compliant clients should not use such values.
   * Can be treated as invalid request.
   */
  MHD_DIGEST_AUTH_NC_TOO_LONG = 4
  ,
  /**
   * 'nc' value is too large for uint32_t.
   * Compliant clients should not use such values.
   * Can be treated as request with a stale nonce or as invalid request.
   */
  MHD_DIGEST_AUTH_NC_TOO_LARGE = 5
};


/**
 * Information from Digest Authorization client's header.
 *
 * @see #MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO
 */
struct MHD_AuthDigestInfo
{
  /**
   * The algorithm as defined by client.
   * Set automatically to MD5 if not specified by client.
   */
  enum MHD_DigestAuthAlgo algo;

  /**
   * The type of username used by client.
   */
  enum MHD_DigestAuthUsernameType uname_type;

  /**
   * The username string.
   * Used only if username type is standard or extended, always NULL otherwise.
   * If extended notation is used, this string is pct-decoded string
   * with charset and language tag removed (i.e. it is original username
   * extracted from the extended notation).
   * When userhash is used by the client, the string pointer is NULL and
   * @a userhash_hex and @a userhash_bin are set.
   */
  struct MHD_StringNullable username;

  /**
   * The userhash string.
   * Valid only if username type is userhash.
   * This is unqoted string without decoding of the hexadecimal
   * digits (as provided by the client).
   * @sa #MHD_digest_auth_calc_userhash_hex()
   */
  struct MHD_StringNullable userhash_hex;

  /**
   * The userhash decoded to binary form.
   * Used only if username type is userhash, always NULL otherwise.
   * When not NULL, this points to binary sequence @a userhash_bin_size bytes
   * long.
   * The valid size should be #MHD_digest_get_hash_size() bytes.
   * @warning This is a binary data, no zero termination.
   * @warning To avoid buffer overruns, always check the size of the data before
   *          use, because @a userhash_bin can point even to zero-sized
   *          data.
   * @sa #MHD_digest_auth_calc_userhash()
   */
  const uint8_t *userhash_bin;

  /**
   * The size of the data pointed by @a userhash_bin.
   * Always zero when @a userhash_bin is NULL.
   */
  size_t userhash_bin_size;

  /**
   * The 'opaque' parameter value, as specified by client.
   * If not specified by client then string pointer is NULL.
   */
  struct MHD_StringNullable opaque;

  /**
   * The 'realm' parameter value, as specified by client.
   * If not specified by client then string pointer is NULL.
   */
  struct MHD_StringNullable realm;

  /**
   * The 'qop' parameter value.
   */
  enum MHD_DigestAuthQOP qop;

  /**
   * The length of the 'cnonce' parameter value, including possible
   * backslash-escape characters.
   * 'cnonce' is used in hash calculation, which is CPU-intensive procedure.
   * An application may want to reject too large cnonces to limit the CPU load.
   * A few kilobytes is a reasonable limit, typically cnonce is just 32-160
   * characters long.
   */
  size_t cnonce_len;

  /**
   * The type of 'nc' (nonce count) value provided in the request.
   */
  enum MHD_DigestAuthNC nc_type;

  /**
   * The nc (nonce count) parameter value.
   * Can be used by application to limit the number of nonce re-uses. If @a nc
   * is higher than application wants to allow, then "auth required" response
   * with 'stale=true' could be used to force client to retry with the fresh
   * 'nonce'.
   * Set to zero when @a nc_type is not set to #MHD_DIGEST_AUTH_NC_NUMBER.
   */
  uint_fast32_t nc;
};

/**
 * The result of digest authentication of the client.
 *
 * All error values are zero or negative.
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthResult
{
  /**
   * Authentication OK.
   */
  MHD_DAUTH_OK = 1
  ,
  /**
   * General error, like "out of memory".
   * Authentication may be valid, but cannot be checked.
   */
  MHD_DAUTH_ERROR = 0
  ,
  /**
   * No "Authorization" header for Digest Authentication.
   */
  MHD_DAUTH_HEADER_MISSING = -1
  ,
  /**
   * Wrong format of the header.
   * Also returned if required parameters in Authorization header are missing
   * or broken (in invalid format).
   */
  MHD_DAUTH_HEADER_BROKEN = -9
  ,
  /**
   * Unsupported algorithm.
   */
  MHD_DAUTH_UNSUPPORTED_ALGO = -10
  ,
  /**
   * Unsupported 'qop'.
   */
  MHD_DAUTH_UNSUPPORTED_QOP = -11
  ,
  /**
   * Incorrect userdigest size.
   */
  MHD_DAUTH_INVALID_USERDIGEST_SIZE = -15
  ,
  /**
   * Wrong 'username'.
   */
  MHD_DAUTH_WRONG_USERNAME = -17
  ,
  /**
   * Wrong 'realm'.
   */
  MHD_DAUTH_WRONG_REALM = -18
  ,
  /**
   * Wrong 'URI' (or URI parameters).
   */
  MHD_DAUTH_WRONG_URI = -19
  ,
  /**
   * Wrong 'qop'.
   */
  MHD_DAUTH_WRONG_QOP = -20
  ,
  /**
   * Wrong 'algorithm'.
   */
  MHD_DAUTH_WRONG_ALGO = -21
  ,
  /**
   * Too large (>64 KiB) Authorization parameter value.
   */
  MHD_DAUTH_TOO_LARGE = -22
  ,
  /* The different form of naming is intentionally used for the results below,
   * as they are more important */

  /**
   * The 'nonce' is too old. Suggest the client to retry with the same
   * username and password to get the fresh 'nonce'.
   * The validity of the 'nonce' may be not checked.
   */
  MHD_DAUTH_NONCE_STALE = -25
  ,
  /**
   * The 'nonce' is wrong. May indicate an attack attempt.
   */
  MHD_DAUTH_NONCE_WRONG = -33
  ,
  /**
   * The 'response' is wrong. May indicate a wrong password used or
   * an attack attempt.
   */
  MHD_DAUTH_RESPONSE_WRONG = -34
};


/**
 * Authenticates the authorization header sent by the client.
 *
 * If RFC2069 mode is allowed by setting bit #MHD_DIGEST_AUTH_QOP_NONE in
 * @a mqop and the client uses this mode, then server generated nonces are
 * used as one-time nonces because nonce-count is not supported in this old RFC.
 * Communication in this mode is very inefficient, especially if the client
 * requests several resources one-by-one as for every request a new nonce must
 * be generated and client repeats all requests twice (first time to get a new
 * nonce and second time to perform an authorised request).
 *
 * @param request the request
 * @param realm the realm for authorization of the client
 * @param username the username to be authenticated, must be in clear text
 *                 even if userhash is used by the client
 * @param password the password matching the @a username (and the @a realm)
 * @param max_nc the maximum allowed nc (Nonce Count) value, if client's nc
 *               exceeds the specified value then MHD_DAUTH_NONCE_STALE is
 *               returned;
 *               if zero is specified then daemon default value is used.
 * @param mqop the QOP to use
 * @param malgo digest algorithms allowed to use, fail if algorithm used
 *               by the client is not allowed by this parameter
 * @return #MHD_DAUTH_OK if authenticated,
 *         the error code otherwise
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_DigestAuthResult
MHD_digest_auth_check (struct MHD_Request *MHD_RESTRICT request,
                       const char *MHD_RESTRICT realm,
                       const char *MHD_RESTRICT username,
                       const char *MHD_RESTRICT password,
                       uint_fast32_t max_nc,
                       enum MHD_DigestAuthMultiQOP mqop,
                       enum MHD_DigestAuthMultiAlgo malgo)
MHD_FN_PAR_NONNULL_ALL_
MHD_FN_PAR_CSTR_ (2) MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_CSTR_ (4);


/**
 * Calculate userdigest, return it as a binary data.
 *
 * The "userdigest" is the hash of the "username:realm:password" string.
 *
 * The "userdigest" can be used to avoid storing the password in clear text
 * in database/files
 *
 * This function is designed to improve security of stored credentials,
 * the "userdigest" does not improve security of the authentication process.
 *
 * The results can be used to store username & userdigest pairs instead of
 * username & password pairs. To further improve security, application may
 * store username & userhash & userdigest triplets.
 *
 * @param algo the digest algorithm
 * @param username the username
 * @param realm the realm
 * @param password the password
 * @param bin_buf_size the size of the @a userdigest_bin buffer, must be
 *                     at least #MHD_digest_get_hash_size() bytes long
 * @param[out] userdigest_bin the output buffer for userdigest;
 *                            if this function succeeds, then this buffer has
 *                            #MHD_digest_get_hash_size() bytes of
 *                            userdigest upon return
 * @return #MHD_SC_OK on success,
 *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
 *         #MHD_SC_HASH_FAILED if hashing failed,
 *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
 *                                                unknown or unsupported.
 * @sa #MHD_digest_auth_check_digest()
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_digest_auth_calc_userdigest (enum MHD_DigestAuthAlgo algo,
                                 const char *MHD_RESTRICT username,
                                 const char *MHD_RESTRICT realm,
                                 const char *MHD_RESTRICT password,
                                 size_t bin_buf_size,
                                 void *MHD_RESTRICT userdigest_bin)
MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_
MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_CSTR_ (3)
MHD_FN_PAR_CSTR_ (4)
MHD_FN_PAR_OUT_SIZE_ (6, 5);


/**
 * Authenticates the authorization header sent by the client by using
 * hash of "username:realm:password".
 *
 * If RFC2069 mode is allowed by setting bit #MHD_DIGEST_AUTH_QOP_NONE in
 * @a mqop and the client uses this mode, then server generated nonces are
 * used as one-time nonces because nonce-count is not supported in this old RFC.
 * Communication in this mode is very inefficient, especially if the client
 * requests several resources one-by-one as for every request a new nonce must
 * be generated and client repeats all requests twice (first time to get a new
 * nonce and second time to perform an authorised request).
 *
 * @param request the request
 * @param realm the realm for authorization of the client
 * @param username the username to be authenticated, must be in clear text
 *                 even if userhash is used by the client
 * @param userdigest_size the size of the @a userdigest in bytes, must match the
 *                        hashing algorithm (see #MHD_MD5_DIGEST_SIZE,
 *                        #MHD_SHA256_DIGEST_SIZE, #MHD_SHA512_256_DIGEST_SIZE,
 *                        #MHD_digest_get_hash_size())
 * @param userdigest the precalculated binary hash of the string
 *                   "username:realm:password",
 *                   see #MHD_digest_auth_calc_userdigest()
 * @param max_nc the maximum allowed nc (Nonce Count) value, if client's nc
 *               exceeds the specified value then MHD_DAUTH_NONCE_STALE is
 *               returned;
 *               if zero is specified then daemon default value is used.
 * @param mqop the QOP to use
 * @param malgo digest algorithms allowed to use, fail if algorithm used
 *              by the client is not allowed by this parameter;
 *              more than one base algorithms (MD5, SHA-256, SHA-512/256)
 *              cannot be used at the same time for this function
 *              as @a userdigest must match specified algorithm
 * @return #MHD_DAUTH_OK if authenticated,
 *         the error code otherwise
 * @sa #MHD_digest_auth_calc_userdigest()
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_DigestAuthResult
MHD_digest_auth_check_digest (struct MHD_Request *MHD_RESTRICT request,
                              const char *MHD_RESTRICT realm,
                              const char *MHD_RESTRICT username,
                              size_t userdigest_size,
                              const void *MHD_RESTRICT userdigest,
                              uint_fast32_t max_nc,
                              enum MHD_DigestAuthMultiQOP mqop,
                              enum MHD_DigestAuthMultiAlgo malgo)
MHD_FN_PAR_NONNULL_ALL_
MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_CSTR_ (3)
MHD_FN_PAR_IN_SIZE_ (5, 4);


/**
 * Add Digest Authentication "challenge" to the response.
 *
 * The response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If @a mqop allows both RFC 2069 (#MHD_DIGEST_AUTH_QOP_NONE) and other QOP
 * values, then the "challenge" is formed like if MHD_DIGEST_AUTH_QOP_NONE bit
 * was not set, because such "challenge" should be backward-compatible with
 * RFC 2069.
 *
 * If @a mqop allows only MHD_DIGEST_AUTH_MULT_QOP_NONE, then the response is
 * formed in strict accordance with RFC 2069 (no 'qop', no 'userhash', no
 * 'charset'). For better compatibility with clients, it is recommended (but
 * not required) to set @a domain to NULL in this mode.
 *
 * New nonces are generated each time when the resulting response is used.
 *
 * See RFC 7616, section 3.3 for details.
 *
 * @param response the response to update; should contain the "access denied"
 *                 body;
 *                 note: this function sets the "WWW Authenticate" header and
 *                 the caller should not set this header;
 *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *                 code;
 *                 the NULL is tolerated (the result is
 *                 #MHD_SC_RESP_POINTER_NULL)
 * @param realm the realm presented to the client
 * @param opaque the string for opaque value, can be NULL, but NULL is
 *               not recommended for better compatibility with clients;
 *               the recommended format is hex or Base64 encoded string
 * @param domain the optional space-separated list of URIs for which the
 *               same authorisation could be used, URIs can be in form
 *               "path-absolute" (the path for the same host with initial slash)
 *               or in form "absolute-URI" (the full path with protocol), in
 *               any case client may assume that URI is in the same "protection
 *               space" if it starts with any of values specified here;
 *               could be NULL (clients typically assume that the same
 *               credentials could be used for any URI on the same host);
 *               this list provides information for the client only and does
 *               not actually restrict anything on the server side
 * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
 *                       in the client's request is indicated by adding
 *                       'stale=true' to the authentication header, this
 *                       instructs the client to retry immediately with the new
 *                       nonce and the same credentials, without asking user
 *                       for the new password
 * @param mqop the QOP to use
 * @param malgo digest algorithm to use; if several algorithms are allowed
 *              then one challenge for each allowed algorithm is added
 * @param userhash_support if set to #MHD_YES then support of userhash is
 *                         indicated, allowing client to provide
 *                         hash("username:realm") instead of the username in
 *                         clear text;
 *                         note that clients are allowed to provide the username
 *                         in cleartext even if this parameter set to non-zero;
 *                         when userhash is used, application must be ready to
 *                         identify users by provided userhash value instead of
 *                         username; see #MHD_digest_auth_calc_userhash() and
 *                         #MHD_digest_auth_calc_userhash_hex()
 * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
 *                    added, indicating for the client that UTF-8 encoding for
 *                    the username is preferred
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_LATE if the response has been already "frozen" (used to
 *         create an action),
 *         #MHD_SC_RESP_HEADERS_CONFLICT if Digest Authentication "challenge"
 *         has been added already,
 *         #MHD_SC_RESP_POINTER_NULL if @a response is NULL,
 *         #MHD_SC_RESP_HTTP_CODE_NOT_SUITABLE is response status code is wrong,
 *         #MHD_SC_RESP_HEADER_VALUE_INVALID if @a realm, @a opaque or @a domain
 *         have wrong characters or zero length (for @a realm),
 *         #MHD_SC_RESP_HEADER_MEM_ALLOC_FAILED if memory allocation failed,
 *         or other error code if failed
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_response_add_auth_digest_challenge (
  struct MHD_Response *MHD_RESTRICT response,
  const char *MHD_RESTRICT realm,
  const char *MHD_RESTRICT opaque,
  const char *MHD_RESTRICT domain,
  enum MHD_Bool indicate_stale,
  enum MHD_DigestAuthMultiQOP mqop,
  enum MHD_DigestAuthMultiAlgo malgo,
  enum MHD_Bool userhash_support,
  enum MHD_Bool prefer_utf8)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_CSTR_ (4);


/* Application may define MHD_NO_STATIC_INLINE macro before including
   libmicrohttpd headers to disable static inline functions in the headers. */
#ifndef MHD_NO_STATIC_INLINE

/**
 * Create action to reply with Digest Authentication "challenge".
 *
 * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * See RFC 7616, section 3.3 for details.
 *
 * @param request the request to create the action for
 * @param realm the realm presented to the client
 * @param opaque the string for opaque value, can be NULL, but NULL is
 *               not recommended for better compatibility with clients;
 *               the recommended format is hex or Base64 encoded string
 * @param domain the optional space-separated list of URIs for which the
 *               same authorisation could be used, URIs can be in form
 *               "path-absolute" (the path for the same host with initial slash)
 *               or in form "absolute-URI" (the full path with protocol), in
 *               any case client may assume that URI is in the same "protection
 *               space" if it starts with any of values specified here;
 *               could be NULL (clients typically assume that the same
 *               credentials could be used for any URI on the same host);
 *               this list provides information for the client only and does
 *               not actually restrict anything on the server side
 * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
 *                       in the client's request is indicated by adding
 *                       'stale=true' to the authentication header, this
 *                       instructs the client to retry immediately with the new
 *                       nonce and the same credentials, without asking user
 *                       for the new password
 * @param mqop the QOP to use
 * @param malgo digest algorithm to use; if several algorithms are allowed
 *              then one challenge for each allowed algorithm is added
 * @param userhash_support if set to #MHD_YES then support of userhash is
 *                         indicated, allowing client to provide
 *                         hash("username:realm") instead of the username in
 *                         clear text;
 *                         note that clients are allowed to provide the username
 *                         in cleartext even if this parameter set to non-zero;
 *                         when userhash is used, application must be ready to
 *                         identify users by provided userhash value instead of
 *                         username; see #MHD_digest_auth_calc_userhash() and
 *                         #MHD_digest_auth_calc_userhash_hex()
 * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
 *                    added, indicating for the client that UTF-8 encoding for
 *                    the username is preferred
 * @param response the response to update; should contain the "access denied"
 *                 body;
 *                 note: this function sets the "WWW Authenticate" header and
 *                 the caller should not set this header;
 *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *                 code;
 *                 the NULL is tolerated (the result is
 *                 #MHD_SC_RESP_POINTER_NULL)
 * @param abort_if_failed if set to #MHD_NO the response will be used even if
 *                        failed to add Basic Authentication "challenge",
 *                        if not set to #MHD_NO the request will be aborted
 *                        if the "challenge" could not be added.
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
MHD_STATIC_INLINE_
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
const struct MHD_Action *
MHD_action_digest_auth_challenge (struct MHD_Request *MHD_RESTRICT request,
                                  const char *MHD_RESTRICT realm,
                                  const char *MHD_RESTRICT opaque,
                                  const char *MHD_RESTRICT domain,
                                  enum MHD_Bool indicate_stale,
                                  enum MHD_DigestAuthMultiQOP mqop,
                                  enum MHD_DigestAuthMultiAlgo malgo,
                                  enum MHD_Bool userhash_support,
                                  enum MHD_Bool prefer_utf8,
                                  struct MHD_Response *MHD_RESTRICT response,
                                  enum MHD_Bool abort_if_failed)
{
  if ((MHD_SC_OK !=
       MHD_response_add_auth_digest_challenge (response, realm, opaque, domain,
                                               indicate_stale, mqop, malgo,
                                               userhash_support, prefer_utf8))
      && (MHD_NO != abort_if_failed))
  {
    MHD_response_destroy (response);
    return MHD_action_abort_request (request);
  }
  return MHD_action_from_response (request, response);
}


MHD_STATIC_INLINE_END_

/**
 * Create action to reply with Digest Authentication "challenge".
 *
 * The @a r response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If the @a r response object cannot be extended with the "challenge",
 * the @a r response is used to reply without the "challenge".
 *
 * @param rq the request to create the action for
 * @param l the realm presented to the client
 * @param o the string for opaque value, can be NULL, but NULL is
 *          not recommended for better compatibility with clients;
 *          the recommended format is hex or Base64 encoded string
 * @param d the optional space-separated list of URIs for which the
 *          same authorisation could be used, URIs can be in form
 *          "path-absolute" (the path for the same host with initial slash)
 *          or in form "absolute-URI" (the full path with protocol), in
 *          any case client may assume that URI is in the same "protection
 *          space" if it starts with any of values specified here;
 *          could be NULL (clients typically assume that the same
 *          credentials could be used for any URI on the same host);
 *          this list provides information for the client only and does
 *          not actually restrict anything on the server side
 * @param s if set to #MHD_YES then indication of stale nonce used
 *          in the client's request is indicated by adding
 *          'stale=true' to the authentication header, this
 *          instructs the client to retry immediately with the new
 *          nonce and the same credentials, without asking user
 *          for the new password
 * @param q the QOP to use
 * @param a digest algorithm to use; if several algorithms are allowed
 *          then one challenge for each allowed algorithm is added
 * @param h if set to #MHD_YES then support of userhash is
 *          indicated, allowing client to provide
 *          hash("username:realm") instead of the username in
 *          clear text;
 *          note that clients are allowed to provide the username
 *          in cleartext even if this parameter set to non-zero;
 *          when userhash is used, application must be ready to
 *          identify users by provided userhash value instead of
 *          username; see #MHD_digest_auth_calc_userhash() and
 *          #MHD_digest_auth_calc_userhash_hex()
 * @param u if not set to #MHD_NO, parameter 'charset=UTF-8' is
 *          added, indicating for the client that UTF-8 encoding for
 *          the username is preferred
 * @param r the response to update; should contain the "access denied"
 *          body;
 *          note: this function sets the "WWW Authenticate" header and
 *          the caller should not set this header;
 *          the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *          code;
 *          the NULL is tolerated (the result is
 *          #MHD_SC_RESP_POINTER_NULL)
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a rq request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
#  define MHD_action_digest_auth_challenge_p(rq, l, o, d, s, q, a, h, u, r) \
          MHD_action_digest_auth_challenge ((rq),(l),(o),(d),(s),(q), \
                                            (a),(h),(u),(r),MHD_NO)


/**
 * Create action to reply with Digest Authentication "challenge".
 *
 * The @a r response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If the @a r response object cannot be extended with the "challenge",
 * the @a r response is aborted.
 *
 * @param rq the request to create the action for
 * @param l the realm presented to the client
 * @param o the string for opaque value, can be NULL, but NULL is
 *          not recommended for better compatibility with clients;
 *          the recommended format is hex or Base64 encoded string
 * @param d the optional space-separated list of URIs for which the
 *          same authorisation could be used, URIs can be in form
 *          "path-absolute" (the path for the same host with initial slash)
 *          or in form "absolute-URI" (the full path with protocol), in
 *          any case client may assume that URI is in the same "protection
 *          space" if it starts with any of values specified here;
 *          could be NULL (clients typically assume that the same
 *          credentials could be used for any URI on the same host);
 *          this list provides information for the client only and does
 *          not actually restrict anything on the server side
 * @param s if set to #MHD_YES then indication of stale nonce used
 *          in the client's request is indicated by adding
 *          'stale=true' to the authentication header, this
 *          instructs the client to retry immediately with the new
 *          nonce and the same credentials, without asking user
 *          for the new password
 * @param q the QOP to use
 * @param a digest algorithm to use; if several algorithms are allowed
 *          then one challenge for each allowed algorithm is added
 * @param h if set to #MHD_YES then support of userhash is
 *          indicated, allowing client to provide
 *          hash("username:realm") instead of the username in
 *          clear text;
 *          note that clients are allowed to provide the username
 *          in cleartext even if this parameter set to non-zero;
 *          when userhash is used, application must be ready to
 *          identify users by provided userhash value instead of
 *          username; see #MHD_digest_auth_calc_userhash() and
 *          #MHD_digest_auth_calc_userhash_hex()
 * @param u if not set to #MHD_NO, parameter 'charset=UTF-8' is
 *          added, indicating for the client that UTF-8 encoding for
 *          the username is preferred
 * @param r the response to update; should contain the "access denied"
 *          body;
 *          note: this function sets the "WWW Authenticate" header and
 *          the caller should not set this header;
 *          the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *          code;
 *          the NULL is tolerated (the result is
 *          #MHD_SC_RESP_POINTER_NULL)
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a rq request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
#  define MHD_action_digest_auth_challenge_a(rq, l, o, d, s, q, a, h, u, r) \
          MHD_action_digest_auth_challenge ((rq),(l),(o),(d),(s),(q), \
                                            (a),(h),(u),(r),MHD_YES)

#endif /* ! MHD_NO_STATIC_INLINE */


/**
 * Add Basic Authentication "challenge" to the response.
 *
 * The response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If access to any resource should be limited to specific users, authenticated
 * by Basic Authentication mechanism, and the request for this resource does not
 * have Basic Authentication information (see #MHD_AuthBasicCreds), then response
 * with Basic Authentication "challenge" should be sent. This works as
 * an indication that Basic Authentication should be used for the access.
 *
 * See RFC 7617, section-2 for details.
 *
 * @param response the reply to send; should contain the "access denied"
 *                 body;
 *                 note: this function sets the "WWW Authenticate" header and
 *                 the caller should not set this header;
 *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *                 code;
 *                 the NULL is tolerated (the result is
 *                 #MHD_SC_RESP_POINTER_NULL)
 * @param realm the realm presented to the client
 * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
 *                    be added, indicating for client that UTF-8 encoding
 *                    is preferred
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_LATE if the response has been already "frozen" (used to
 *         create an action),
 *         #MHD_SC_RESP_HEADERS_CONFLICT if Basic Authentication "challenge"
 *         has been added already,
 *         #MHD_SC_RESP_POINTER_NULL if @a response is NULL,
 *         #MHD_SC_RESP_HTTP_CODE_NOT_SUITABLE is response status code is wrong,
 *         #MHD_SC_RESP_HEADER_VALUE_INVALID if realm is zero-length or has CR
 *         or LF characters,
 *         #MHD_SC_RESP_HEADER_MEM_ALLOC_FAILED if memory allocation failed,
 *         or other error code if failed
 * @ingroup authentication
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_response_add_auth_basic_challenge (
  struct MHD_Response *MHD_RESTRICT response,
  const char *MHD_RESTRICT realm,
  enum MHD_Bool prefer_utf8)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2);

/* Application may define MHD_NO_STATIC_INLINE macro before including
   libmicrohttpd headers to disable static inline functions in the headers. */
#ifndef MHD_NO_STATIC_INLINE

/**
 * Create action to reply with Basic Authentication "challenge".
 *
 * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If access to any resource should be limited to specific users, authenticated
 * by Basic Authentication mechanism, and the request for this resource does not
 * have Basic Authentication information (see #MHD_AuthBasicCreds), then response
 * with Basic Authentication "challenge" should be sent. This works as
 * an indication that Basic Authentication should be used for the access.
 *
 * See RFC 7617, section-2 for details.
 *
 * @param request the request to create the action for
 * @param realm the realm presented to the client
 * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
 *                    be added, indicating for client that UTF-8 encoding
 *                    is preferred
 * @param response the reply to send; should contain the "access denied"
 *                 body;
 *                 note: this function adds the "WWW Authenticate" header in
 *                 the response and the caller should not set this header;
 *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *                 code;
 *                 the NULL is tolerated (the result is
 *                 #MHD_action_abort_request())
 * @param abort_if_failed if set to #MHD_NO the response will be used even if
 *                        failed to add Basic Authentication "challenge",
 *                        if not set to #MHD_NO the request will be aborted
 *                        if the "challenge" could not be added.
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
MHD_STATIC_INLINE_
MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
const struct MHD_Action *
MHD_action_basic_auth_challenge (struct MHD_Request *MHD_RESTRICT request,
                                 const char *MHD_RESTRICT realm,
                                 enum MHD_Bool prefer_utf8,
                                 struct MHD_Response *MHD_RESTRICT response,
                                 enum MHD_Bool abort_if_failed)
{
  if ((MHD_SC_OK !=
       MHD_response_add_auth_basic_challenge (response, realm, prefer_utf8))
      && (MHD_NO != abort_if_failed))
  {
    MHD_response_destroy (response);
    return MHD_action_abort_request (request);
  }
  return MHD_action_from_response (request, response);
}


MHD_STATIC_INLINE_END_


/**
 * Create action to reply with Basic Authentication "challenge".
 *
 * The @a r response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If the @a r response object cannot be extended with the "challenge",
 * the @a r response will be used to reply without the "challenge".
 *
 * @param rq the request to create the action for
 * @param l the realm presented to the client
 * @param u if not set to #MHD_NO, parameter'charset="UTF-8"' will
 *          be added, indicating for client that UTF-8 encoding
 *          is preferred
 * @param r the reply to send; should contain the "access denied"
 *          body;
 *          note: this function adds the "WWW Authenticate" header in
 *          the response and the caller should not set this header;
 *          the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *          code;
 *          the NULL is tolerated (the result is
 *          #MHD_action_abort_request())
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a rq request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
#  define MHD_action_basic_auth_challenge_p(rq, l, u, r) \
          MHD_action_basic_auth_challenge ((rq), (l), (u), (r), MHD_NO)

/**
 * Create action to reply with Basic Authentication "challenge".
 *
 * The @a r response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
 *
 * If the @a r response object cannot be extended with the "challenge",
 * the request will be aborted.
 *
 * @param rq the request to create the action for
 * @param l the realm presented to the client
 * @param u if not set to #MHD_NO, parameter'charset="UTF-8"' will
 *          be added, indicating for client that UTF-8 encoding
 *          is preferred
 * @param r the reply to send; should contain the "access denied"
 *          body;
 *          note: this function adds the "WWW Authenticate" header in
 *          the response and the caller should not set this header;
 *          the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
 *          code;
 *          the NULL is tolerated (the result is
 *          #MHD_action_abort_request())
 * @return pointer to the action, the action must be consumed
 *         otherwise response object may leak;
 *         NULL if failed or if any action has been already created for
 *         the @a rq request;
 *         when failed the response object is consumed and need not
 *         to be "destroyed"
 * @ingroup authentication
 */
#  define MHD_action_basic_auth_challenge_a(rq, l, u, r) \
          MHD_action_basic_auth_challenge ((rq), (l), (u), (r), MHD_YES)

#endif /* ! MHD_NO_STATIC_INLINE */


/**
 * Information decoded from Basic Authentication client's header.
 *
 * @see #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS
 */
struct MHD_AuthBasicCreds
{
  /**
   * The username
   */
  struct MHD_String username;

  /**
   * The password, string pointer may be NULL if password is not encoded
   * by the client.
   */
  struct MHD_StringNullable password;
};

/* ********************** (f) Introspection ********************** */


/**
 * Types of information about MHD, used by #MHD_lib_get_info_fixed_sz().
 * This information is not changed at run-time.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_LibInfoFixed
{
  /* * Basic MHD information * */

  /**
   * Get the MHD version as a number.
   * The result is placed in @a v_version_num_uint32 member.
   */
  MHD_LIB_INFO_FIXED_VERSION_NUM = 0
  ,
  /**
   * Get the MHD version as a string.
   * The result is placed in @a v_version_string member.
   */
  MHD_LIB_INFO_FIXED_VERSION_STRING = 1
  ,

  /* * Basic MHD features, buid-time configurable * */
  /* These features should be always available unless the library was
   * not compiled specifically for some embedded project.
   * Exceptions are marked explicitly in the description. */

  /**
   * Get whether messages are supported. If supported then messages can be
   * printed to stderr or to an external logger.
   * The result is placed in @a v_support_log_messages_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_LOG_MESSAGES = 11
  ,
  /**
   * Get whether detailed automatic HTTP reply messages are supported.
   * If supported then automatic responses have bodies with text explaining
   * the error details.
   * Automatic responses are sent by MHD automatically when client is violating
   * HTTP specification, for example, the request header has whitespace in
   * header name or request's "Content-Length" header has non-number value.
   * The result is placed in @a v_support_auto_replies_bodies_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_AUTO_REPLIES_BODIES = 12
  ,
  /**
   * Get whether MHD was built with debug asserts disabled.
   * These asserts enabled only on special debug builds.
   * For debug builds the error log is always enabled.
   * The result is placed in @a v_is_non_debug_bool member.
   */
  MHD_LIB_INFO_FIXED_IS_NON_DEBUG = 13
  ,
  /**
   * Get whether MHD supports threads.
   * The result is placed in @a v_support_threads_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_THREADS = 14
  ,
  /**
   * Get whether automatic parsing of HTTP Cookie header is supported.
   * If disabled, no #MHD_VK_COOKIE will be generated by MHD.
   * The result is placed in @a v_support_cookie_parser_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_COOKIE_PARSER = 15
  ,
  /**
   * Get whether postprocessor is supported. If supported then
   * #MHD_action_post_processor() can be used.
   * The result is placed in @a v_support_post_parser_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_POST_PARSER = 16
  ,
  /**
   * Get whether HTTP "Upgrade" is supported.
   * If supported then #MHD_action_upgrade() can be used.
   * The result is placed in @a v_support_upgrade_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_UPGRADE = 17
  ,
  /**
   * Get whether HTTP Basic authorization is supported. If supported
   * then functions #MHD_action_basic_auth_required_response ()
   * and #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS can be used.
   * The result is placed in @a v_support_auth_basic_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_AUTH_BASIC = 20
  ,
  /**
   * Get whether HTTP Digest authorization is supported. If
   * supported then options #MHD_D_O_RANDOM_ENTROPY,
   * #MHD_D_O_DAUTH_MAP_SIZE and functions
   * #MHD_action_digest_auth_required_response () and
   * #MHD_digest_auth_check() can be used.
   * The result is placed in @a v_support_auth_digest_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_AUTH_DIGEST = 21
  ,
  /**
   * Get whether the early version the Digest Authorization (RFC 2069) is
   * supported (digest authorisation without QOP parameter).
   * Currently it is always supported if Digest Auth module is built.
   * The result is placed in @a v_support_digest_auth_rfc2069_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_RFC2069 = 22
  ,
  /**
   * Get whether the MD5-based hashing algorithms are supported for Digest
   * Authorization and the type of the implementation if supported.
   * Currently it is always supported if Digest Auth module is built
   * unless manually disabled in a custom build.
   * The result is placed in @a v_type_digest_auth_md5_algo_type member.
   */
  MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_MD5 = 23
  ,
  /**
   * Get whether the SHA-256-based hashing algorithms are supported for Digest
   * Authorization and the type of the implementation if supported.
   * Currently it is always supported if Digest Auth module is built
   * unless manually disabled in a custom build.
   * The result is placed in @a v_type_digest_auth_sha256_algo_type member.
   */
  MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA256 = 24
  ,
  /**
   * Get whether the SHA-512/256-based hashing algorithms are supported
   * Authorization and the type of the implementation if supported.
   * Currently it is always supported if Digest Auth module is built
   * unless manually disabled in a custom build.
   * The result is placed in @a v_type_digest_auth_sha512_256_algo_type member.
   */
  MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA512_256 = 25
  ,
  /**
   * Get whether QOP with value 'auth-int' (authentication with integrity
   * protection) is supported for Digest Authorization.
   * Currently it is always not supported.
   * The result is placed in @a v_support_digest_auth_auth_int_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_AUTH_INT = 28
  ,
  /**
   * Get whether 'session' algorithms (like 'MD5-sess') are supported for Digest
   * Authorization.
   * Currently it is always not supported.
   * The result is placed in @a v_support_digest_auth_algo_session_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_ALGO_SESSION = 29
  ,
  /**
   * Get whether 'userhash' is supported for Digest Authorization.
   * Currently it is always supported if Digest Auth module is built.
   * The result is placed in @a v_support_digest_auth_userhash_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_USERHASH = 30
  ,

  /* * Platform-dependent features, some are configurable at build-time * */
  /* These features depends on the platform, third-party libraries and
   * the toolchain.
   * Some of the features can be disabled or selected at build-time. */
  /**
   * Get sockets polling functions/techniques supported by this MHD build.
   * Some functions can be disabled (like epoll) in kernel, this is not
   * checked.
   * The result is placed in @a v_types_sockets_polling member.
   */
  MHD_LIB_INFO_FIXED_TYPES_SOCKETS_POLLING = 60
  ,
  /**
   * Get whether aggregate FD external polling is supported.
   * The result is placed in @a v_support_aggregate_fd_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_AGGREGATE_FD = 61
  ,
  /**
   * Get whether IPv6 is supported on the platform and IPv6-only listen socket
   * can be used.
   * The result is placed in @a v_ipv6 member.
   * @note The platform may have disabled IPv6 at run-time, it is not checked
   *       by this information type.
   */
  MHD_LIB_INFO_FIXED_TYPE_IPV6 = 62
  ,
  /**
   * Get whether TCP Fast Open is supported by MHD build.
   * If supported then option #MHD_D_O_TCP_FASTOPEN can be used.
   * The result is placed in @a v_support_tcp_fastopen_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_TCP_FASTOPEN = 64
  ,
  /**
   * Get whether MHD support automatic detection of bind port number.
   * @sa #MHD_D_O_BIND_PORT
   * The result is placed in @a v_has_autodetect_bind_port_bool member.
   */
  MHD_LIB_INFO_FIXED_HAS_AUTODETECT_BIND_PORT = 65
  ,
  /**
   * Get whether MHD use system's sendfile() function to send
   * file-FD based responses over non-TLS connections.
   * The result is placed in @a v_has_sendfile_bool member.
   */
  MHD_LIB_INFO_FIXED_HAS_SENDFILE = 66
  ,
  /**
   * Get whether MHD supports automatic SIGPIPE suppression within internal
   * events loop (MHD's managed threads).
   * If SIGPIPE suppression is not supported, application must handle
   * SIGPIPE signal by itself whem using MHD with internal events loop.
   * If the platform does not have SIGPIPE the result is #MHD_YES.
   * The result is placed in @a v_has_autosuppress_sigpipe_int_bool member.
   */
  MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_INT = 80
  ,
  /**
   * Get whether MHD supports automatic SIGPIPE suppression when used with
   * extenal events loop (in application thread).
   * If SIGPIPE suppression is not supported, application must handle
   * SIGPIPE signal by itself whem using MHD with external events loop.
   * If the platform does not have SIGPIPE the result is #MHD_YES.
   * The result is placed in @a v_has_autosuppress_sigpipe_ext_bool member.
   */
  MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_EXT = 81
  ,
  /**
   * Get whether MHD sets names on generated threads.
   * The result is placed in @a v_has_thread_names_bool member.
   */
  MHD_LIB_INFO_FIXED_HAS_THREAD_NAMES = 82
  ,
  /**
   * Get the type of supported inter-thread communication.
   * The result is placed in @a v_type_itc member.
   */
  MHD_LIB_INFO_FIXED_TYPE_ITC = 83
  ,
  /**
   * Get whether reading files beyond 2 GiB boundary is supported.
   * If supported then #MHD_response_from_fd() can be used with sizes and
   * offsets larger than 2 GiB. If not supported value of size+offset could be
   * limited to 2 GiB.
   * The result is placed in @a v_support_large_file_bool member.
   */
  MHD_LIB_INFO_FIXED_SUPPORT_LARGE_FILE = 84
  ,

  /* * Platform-dependent features, some set on startup and some are
   *   configurable at build-time * */
  /* These features depends on the platform, third-party libraries availability
   * and configuration. The features can be enabled/disabled during startup
   * of the library depending on conditions.
   * Some of the features can be disabled or selected at build-time. */
  /**
   * Get whether HTTPS and which types of TLS backend(s) supported by
   * this build.
   * The result is placed in @a v_tls_backends member.
   */
  MHD_LIB_INFO_FIXED_TLS_BACKENDS = 100
  ,
  /**
  * Get whether password encrypted private key for HTTPS daemon is
  * supported by TLS backends.
  * If supported then option #MHD_D_OPTION_TLS_KEY_CERT can be used with
  * non-NULL @a mem_pass.
  * The result is placed in @a v_tls_key_password_backends member.
  */
  MHD_LIB_INFO_FIXED_TLS_KEY_PASSWORD_BACKENDS = 102
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_LIB_INFO_FIXED_SENTINEL = 65535
};

/**
 * The type of the data for digest algorithm implementations.
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedDigestAlgoType
{
  /**
   * The algorithm is not implemented or disabled at the build time.
   */
  MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_NOT_AVAILABLE = 0
  ,
  /**
   * The algorithm is implemented by MHD internal code.
   * MHD implementation of hashing can never fail.
   */
  MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_BUILT_IN = 1
  ,
  /**
   * The algorithm is implemented by external code that never fails.
   */
  MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_EXTERNAL_NEVER_FAIL = 2
  ,
  /**
   * The algorithm is implemented by external code that may hypothetically fail.
   */
  MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_EXTERNAL_MAY_FAIL = 3
};

/**
 * The types of the sockets polling functions/techniques supported
 */
struct MHD_LibInfoFixedPollingFunc
{
  /**
   * select() function for sockets polling
   */
  enum MHD_Bool func_select;
  /**
   * poll() function for sockets polling
   */
  enum MHD_Bool func_poll;
  /**
   * epoll technique for sockets polling
   */
  enum MHD_Bool tech_epoll;
  /**
   * kqueue technique for sockets polling
   */
  enum MHD_Bool tech_kqueue;
};

/**
 * The types of IPv6 supported
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedIPv6Type
{
  /**
   * IPv6 is not supported by this MHD build
   */
  MHD_LIB_INFO_FIXED_IPV6_TYPE_NONE = 0
  ,
  /**
   * IPv6 is supported only as "dual stack".
   * IPv4 connections can be received by IPv6 listen socket.
   */
  MHD_LIB_INFO_FIXED_IPV6_TYPE_DUAL_ONLY = 1
  ,
  /**
   * IPv6 can be used as IPv6-only (without getting IPv4 incoming connections).
   * The platform may support "dual stack" too.
   */
  MHD_LIB_INFO_FIXED_IPV6_TYPE_IPV6_PURE = 2
};

/**
 * The types of inter-thread communication
 * @note the enum can be extended in future versions with new values
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedITCType
{
  /**
   * No ITC used.
   * This value is returned if MHD is built without threads support
   */
  MHD_LIB_INFO_FIXED_ITC_TYPE_NONE = 0
  ,
  /**
   * The pair of sockets are used as inter-thread communication.
   * The is the least efficient method of communication.
   */
  MHD_LIB_INFO_FIXED_ITC_TYPE_SOCKETPAIR = 1
  ,
  /**
   * The pipe is used as inter-thread communication.
   */
  MHD_LIB_INFO_FIXED_ITC_TYPE_PIPE = 2
  ,
  /**
   * The EventFD is used as inter-thread communication.
   * This is the most efficient method of communication.
   */
  MHD_LIB_INFO_FIXED_ITC_TYPE_EVENTFD = 3
};


/**
 * The types of the TLS (or TLS feature) backend supported/available/enabled
 * @note the enum can be extended in future versions with new members
 */
struct MHD_LibInfoTLSType
{
  /**
   * The TLS (or TLS feature) is supported/enabled.
   * Set to #MHD_YES if any other member is #MHD_YES.
   */
  enum MHD_Bool tls_supported;
  /**
   * The GnuTLS backend is supported/available/enabled.
   */
  enum MHD_Bool backend_gnutls;
  /**
   * The OpenSSL backend is supported/available/enabled.
   */
  enum MHD_Bool backend_openssl;
  /**
   * The MbedTLS backend is supported/available/enabled.
   */
  enum MHD_Bool backend_mbedtls;
};

/**
 * The data provided by #MHD_lib_get_info_fixed_sz()
 */
union MHD_LibInfoFixedData
{
  /**
   * The data for the #MHD_LIB_INFO_FIXED_VERSION_NUM query
   */
  uint_fast32_t v_version_num_uint32;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_VERSION_STR query
   */
  struct MHD_String v_version_string;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_LOG_MESSAGES query
   */
  enum MHD_Bool v_support_log_messages_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTO_REPLIES_BODIES query
   */
  enum MHD_Bool v_support_auto_replies_bodies_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_IS_NON_DEBUG query
   */
  enum MHD_Bool v_is_non_debug_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_THREADS query
   */
  enum MHD_Bool v_support_threads_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_COOKIE_PARSER query
   */
  enum MHD_Bool v_support_cookie_parser_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_POST_PARSER query
   */
  enum MHD_Bool v_support_post_parser_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_UPGRADE query
   */
  enum MHD_Bool v_support_upgrade_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTH_BASIC query
   */
  enum MHD_Bool v_support_auth_basic_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTH_DIGEST query
   */
  enum MHD_Bool v_support_auth_digest_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_RFC2069 query
   */
  enum MHD_Bool v_support_digest_auth_rfc2069_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_MD5 query
   */
  enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_md5_algo_type;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA256 query
   */
  enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_sha256_algo_type;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA512_256 query
   */
  enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_sha512_256_algo_type;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_AUTH_INT query
   */
  enum MHD_Bool v_support_digest_auth_auth_int_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_ALGO_SESSION query
   */
  enum MHD_Bool v_support_digest_auth_algo_session_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_USERHASH query
   */
  enum MHD_Bool v_support_digest_auth_userhash_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPES_SOCKETS_POLLING query
   */
  struct MHD_LibInfoFixedPollingFunc v_types_sockets_polling;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AGGREGATE_FD query
   */
  enum MHD_Bool v_support_aggregate_fd_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPE_IPV6 query
   */
  enum MHD_LibInfoFixedIPv6Type v_ipv6;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_TCP_FASTOPEN query
   */
  enum MHD_Bool v_support_tcp_fastopen_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTODETECT_BIND_PORT query
   */
  enum MHD_Bool v_has_autodetect_bind_port_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_HAS_SENDFILE query
   */
  enum MHD_Bool v_has_sendfile_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_INT query
   */
  enum MHD_Bool v_has_autosuppress_sigpipe_int_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_EXT query
   */
  enum MHD_Bool v_has_autosuppress_sigpipe_ext_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_HAS_THREAD_NAMES query
   */
  enum MHD_Bool v_has_thread_names_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TYPE_ITC query
   */
  enum MHD_LibInfoFixedITCType v_type_itc;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_LARGE_FILE query
   */
  enum MHD_Bool v_support_large_file_bool;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TLS_BACKENDS query
   */
  struct MHD_LibInfoTLSType v_tls_backends;
  /**
   * The data for the #MHD_LIB_INFO_FIXED_TLS_KEY_PASSWORD_BACKENDS query
   */
  struct MHD_LibInfoTLSType v_tls_key_password_backends;
};

/**
 * Get fixed information about MHD that is not changed at run-time.
 * The returned information can be cached by application as it will be not
 * changed at run-time.
 *
 * For any valid @a info_type the only possible returned error value is
 * #MHD_SC_INFO_GET_BUFF_TOO_SMALL. If the buffer is large enough and
 * the requested type of information is valid, the function always succeeds
 * and returns #MHD_SC_OK.
 *
 * The wrapper macro #MHD_lib_get_info_fixed() may be more convenient.
 *
 * @param info_type the type of requested information
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_lib_get_info_fixed_sz (enum MHD_LibInfoFixed info_type,
                           union MHD_LibInfoFixedData *MHD_RESTRICT output_buf,
                           size_t output_buf_size)
MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_OUT_ (2);

/**
 * Get fixed information about MHD that is not changed at run-time.
 * The returned information can be cached by application as it will be not
 * changed at run-time.
 *
 * @param info the type of requested information
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         or other error code
 * @ingroup specialized
 */
#define MHD_lib_get_info_fixed(info, output_buf) \
        MHD_lib_get_info_fixed_sz ((info),(output_buf),sizeof(*(output_buf)))

/* Application may define MHD_NO_STATIC_INLINE macro before including
   libmicrohttpd headers to disable static inline functions in the headers. */
#ifndef MHD_NO_STATIC_INLINE

/*
 * A helper below can be used in a simple check preventing use of downgraded
 * library version.
 * As new library version may introduce new functionality, and the application
 * may detect some functionality available at application build-time, use of
 * previous versions may lead to run-time failures.
 * To prevent run-time failures, application may use a check like:

 if (MHD_lib_get_info_ver_num() < ((uint_fast32_t) MHD_VERSION))
   handle_init_failure();

 */
/**
 * Get the library version number.
 * @return the library version number.
 */
MHD_STATIC_INLINE_ MHD_FN_PURE_ uint_fast32_t
MHD_lib_get_info_ver_num (void)
{
  union MHD_LibInfoFixedData data;
  data.v_version_num_uint32 = 0; /* Not really necessary */
  (void)MHD_lib_get_info_fixed (MHD_LIB_INFO_FIXED_VERSION_NUM, \
                                &data);  /* Never fail */
  return data.v_version_num_uint32;
}


MHD_STATIC_INLINE_END_

#endif /* ! MHD_NO_STATIC_INLINE */

/**
 * Types of information about MHD, used by #MHD_lib_get_info_dynamic_sz().
 * This information may vary over time.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_LibInfoDynamic
{
  /* * Basic MHD information * */

  /**
   * Get whether MHD has been successfully fully initialised.
   * MHD uses lazy initialisation: a minimal initialisation is performed at
   * startup, complete initialisation is performed when any daemon is created
   * (or when called some function which requires full initialisation).
   * The result is #MHD_NO when the library has been not yet initialised
   * completely since startup.
   * The result is placed in @a v_inited_fully_once_bool member.
   */
  MHD_LIB_INFO_DYNAMIC_INITED_FULLY_ONCE = 0
  ,
  /**
   * Get whether MHD is fully initialised.
   * MHD uses lazy initialisation: a minimal initialisation is performed at
   * startup, complete initialisation is perfromed when any daemon is created
   * (or when called some function which requires full initialisation).
   * The result is #MHD_YES if library is initialised state now (meaning
   * that at least one daemon is created and not destroyed or some function
   * required full initialisation is running).
   * The result is placed in @a v_inited_fully_now_bool member.
   */
  MHD_LIB_INFO_DYNAMIC_INITED_FULLY_NOW = 1
  ,

  /**
   * Get whether HTTPS and which types of TLS backend(s) currently available.
   * If any MHD daemons active (created and not destroyed, not necessary
   * running) the result reflects the current backends availability.
   * If no MHD daemon is active, then this function would try to temporarily
   * enable backends to check for their availability.
   * If global library initialisation failed, the function returns
   * #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE error code.
   * The result is placed in @a v_tls_backends member.
   */
  MHD_LIB_INFO_DYNAMIC_TYPE_TLS = 100
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_LIB_INFO_DYNAMIC_SENTINEL = 65535
};


/**
 * The data provided by #MHD_lib_get_info_dynamic_sz().
 * The resulting value may vary over time.
 */
union MHD_LibInfoDynamicData
{
  /**
   * The data for the #MHD_LIB_INFO_DYNAMIC_INITED_FULLY_ONCE query
   */
  enum MHD_Bool v_inited_fully_once_bool;

  /**
   * The data for the #MHD_LIB_INFO_DYNAMIC_INITED_FULLY_NOW query
   */
  enum MHD_Bool v_inited_fully_now_bool;

  /**
   * The data for the #MHD_LIB_INFO_DYNAMIC_TYPE_TLS query
   */
  struct MHD_LibInfoTLSType v_tls_backends;

  /**
   * Unused member.
   * Help enforcing future-proof alignment of the union.
   * Do not use.
   */
  void *reserved;
};

/**
 * Get dynamic information about MHD that may be changed at run-time.
 * The wrapper macro #MHD_lib_get_info_dynamic() could be more convenient.
 *
 * @param info_type the type of requested information
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         or other error code
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_lib_get_info_dynamic_sz (
  enum MHD_LibInfoDynamic info_type,
  union MHD_LibInfoDynamicData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_OUT_ (2);

/**
 * Get dynamic information about MHD that may be changed at run-time.
 *
 * @param info the type of requested information
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         or other error code
 * @ingroup specialized
 */
#define MHD_lib_get_info_dynamic(info, output_buf) \
        MHD_lib_get_info_dynamic_sz ((info),(output_buf),sizeof(*(output_buf)))


/**
 * Values of this enum are used to specify what information about a daemon is
 * requested.
 * These types of information do not change after the start of the daemon
 * until the daemon is destroyed.
 */
enum MHD_DaemonInfoFixedType
{

  /**
   * Get the type of system call used for sockets polling.
   * The value #MHD_SPS_AUTO is never set in the returned data.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * does not use internal sockets polling.
   * The result is placed in @a v_poll_syscall member.
   */
  MHD_DAEMON_INFO_FIXED_POLL_SYSCALL = 41
  ,
  /**
   * Get the file descriptor for the single FD that triggered when
   * any MHD event happens.
   * This FD can be watched as aggregate indicator for all MHD events.
   * The provided socket must be used as 'read-only': only select() or similar
   * functions should be used. Any modifications (changing socket attributes,
   * calling accept(), closing it etc.) will lead to undefined behaviour.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_SUPP_BY_BUILD if the library
   * does not support mode with agregate FD.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * is not configured to use this mode.
   * The result is placed in @a v_aggreagate_fd member.
   */
  MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD = 46
  ,
  /**
   * Get the number of worker threads when used in MHD_WM_WORKER_THREADS mode.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * does not use worker threads mode.
   * The result is placed in @a v_num_work_threads_uint member.
   */
  MHD_DAEMON_INFO_FIXED_NUM_WORK_THREADS = 47
  ,
  /**
   * Get the port number of daemon's listen socket.
   * Note: if port '0' (auto port) was specified for #MHD_D_OPTION_BIND_PORT(),
   * returned value will be the real port number.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * does not have listening socket or if listening socket is non-IP.
   * The function returns #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the port number
   * detection failed or not supported by the platform.
   * If the function succeed, the returned port number is never zero.
   * The result is placed in @a v_bind_port_uint16 member.
   */
  MHD_DAEMON_INFO_FIXED_BIND_PORT = 80
  ,
  /**
   * Get the file descriptor for the listening socket.
   * The provided socket must be used as 'read-only': only select() or similar
   * functions should be used. Any modifications (changing socket attributes,
   * calling accept(), closing it etc.) will lead to undefined behaviour.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * does not have listening socket.
   * The result is placed in @a v_listen_socket member.
   */
  MHD_DAEMON_INFO_FIXED_LISTEN_SOCKET = 82
  ,
  /**
   * Get the TLS backend used by the daemon.
   * The value #MHD_TLS_BACKEND_ANY is never set in the returned data.
   * The value #MHD_TLS_BACKEND_NONE is set if the daemon does not use TLS.
   * If MHD built without TLS support then #MHD_TLS_BACKEND_NONE is always set.
   * The result is placed in @a v_tls_backend member.
   */
  MHD_DAEMON_INFO_FIXED_TLS_BACKEND = 120
  ,
  /**
   * Get the default inactivity timeout for connections in milliseconds.
   * The result is placed in @a v_default_timeout_milsec_uint32 member.
   */
  MHD_DAEMON_INFO_FIXED_DEFAULT_TIMEOUT_MILSEC = 160
  ,
  /**
   * Get the limit of number of simutaneous network connections served by
   * the daemon.
   * The result is placed in @a v_global_connection_limit_uint member.
   */
  MHD_DAEMON_INFO_FIXED_GLOBAL_CONNECTION_LIMIT = 161
  ,
  /**
   * Get the limit of number of simutaneous network connections served by
   * the daemon for any single IP address.
   * The result is placed in @a v_per_ip_limit_uint member.
   */
  MHD_DAEMON_INFO_FIXED_PER_IP_LIMIT = 162
  ,
  /**
   * Get the setting for suppression of the 'Date:' header in replies.
   * The result is placed in @a v_suppress_date_header_bool member.
   */
  MHD_DAEMON_INFO_FIXED_SUPPRESS_DATE_HEADER = 240
  ,
  /**
   * Get the size of buffer unsed per connection.
   * The result is placed in @a v_conn_memory_limit_sizet member.
   */
  MHD_DAEMON_INFO_FIXED_CONN_MEMORY_LIMIT = 280
  ,
  /**
   * Get the limit of maximum FD value for the daemon.
   * The daemon rejects (closes) any sockets with FD equal or higher
   * the resulting number.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
   * is built for W32.
   * The result is placed in @a v_fd_number_limit_uint member.
   */
  MHD_DAEMON_INFO_FIXED_FD_NUMBER_LIMIT = 283
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_DAEMON_INFO_FIXED_SENTINEL = 65535

};


/**
 * Information about an MHD daemon.
 */
union MHD_DaemonInfoFixedData
{
  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_POLL_SYSCALL query
   */
  enum MHD_SockPollSyscall v_poll_syscall;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_NUM_WORK_THREADS query
   */
  unsigned int v_num_work_threads_uint;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_BIND_PORT query
   */
  uint_least16_t v_bind_port_uint16;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_LISTEN_SOCKET query
   */
  MHD_Socket v_listen_socket;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD query
   */
  int v_aggreagate_fd;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_TLS_BACKEND query
   */
  enum MHD_TlsBackend v_tls_backend;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_DEFAULT_TIMEOUT_MILSEC query
   */
  uint_fast32_t v_default_timeout_milsec_uint32;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_GLOBAL_CONNECTION_LIMIT query
   */
  unsigned int v_global_connection_limit_uint;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_PER_IP_LIMIT query
   */
  unsigned int v_per_ip_limit_uint;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_SUPPRESS_DATE_HEADER query
   */
  enum MHD_Bool v_suppress_date_header_bool;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_CONN_MEMORY_LIMIT query
   */
  size_t v_conn_memory_limit_sizet;

  /**
   * The data for the #MHD_DAEMON_INFO_FIXED_FD_NUMBER_LIMIT query
   */
  MHD_Socket v_fd_number_limit_socket;

  /**
   * Unused member.
   * Help enforcing future-proof alignment of the union.
   * Do not use.
   */
  void *reserved;
};


/**
 * Obtain fixed information about the given daemon.
 * This information is not changed at after start of the daemon until
 * the daemon is destroyed.
 * The wrapper macro #MHD_daemon_get_info_fixed() may be more convenient.
 *
 * @param daemon the daemon to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf pointer to union where requested information will
 *                        be stored
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
 *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              daemon due to the daemon
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the daemon, but cannot be provided
 *                                            due to some error or other
 *                                            reasons,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_get_info_fixed_sz (
  struct MHD_Daemon *MHD_RESTRICT daemon,
  enum MHD_DaemonInfoFixedType info_type,
  union MHD_DaemonInfoFixedData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);

/**
 * Obtain fixed information about the given daemon.
 * This types of information are not changed at after start of the daemon until
 * the daemon is destroyed.
 *
 * @param daemon the daemon to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf pointer to union where requested information will
 *                          be stored
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
 *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              daemon due to the daemon
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the daemon, but cannot be provided
 *                                            due to some error or other
 *                                            reasons,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_daemon_get_info_fixed(daemon, info_type, output_buf) \
        MHD_daemon_get_info_fixed_sz ((daemon), (info_type), (output_buf), \
                                      sizeof(*(output_buf)))


/**
 * Values of this enum are used to specify what
 * information about a daemon is desired.
 * This types of information may be changed after the start of the daemon.
 */
enum MHD_DaemonInfoDynamicType
{
  /**
   * The the maximum number of millisecond from the current moment until
   * the mandatory call of the daemon data processing function (like
   * #MHD_daemon_process_reg_events(), #MHD_daemon_process_blocking()).
   * If resulting value is zero then daemon data processing function should be
   * called as soon as possible as some data processing is already pending.
   * The data processing function can also be called earlier as well.
   * Available only for daemons stated in #MHD_WM_EXTERNAL_PERIODIC,
   * #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL, #MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE
   * or #MHD_WM_EXTERNAL_SINGLE_FD_WATCH modes.
   * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon has
   * internal handling of events (internal threads).
   * The result is placed in @a v_max_time_to_wait_uint64 member.
   */
  MHD_DAEMON_INFO_DYNAMIC_MAX_TIME_TO_WAIT = 1
  ,
  /**
   * Check whether the daemon has any connected network clients.
   * The result is placed in @a v_has_connections_bool member.
   */
  MHD_DAEMON_INFO_DYNAMIC_HAS_CONNECTIONS = 20
  ,
  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_DAEMON_INFO_DYNAMIC_SENTINEL = 65535
};


/**
 * Information about an MHD daemon.
 */
union MHD_DaemonInfoDynamicData
{
  /**
   * The data for the #MHD_DAEMON_INFO_DYNAMIC_MAX_TIME_TO_WAIT query
   */
  uint_fast64_t v_max_time_to_wait_uint64;

  /**
   * The data for the #MHD_DAEMON_INFO_DYNAMIC_HAS_CONNECTIONS query
   */
  enum MHD_Bool v_has_connections_bool;

  /**
   * Unused member.
   * Help enforcing future-proof alignment of the union.
   * Do not use.
   */
  void *reserved;
};


/**
 * Obtain dynamic information about the given daemon.
 * This information may be changed after the start of the daemon.
 * The wrapper macro #MHD_daemon_get_info_dynamic() could be more convenient.
 *
 * @param daemon the daemon to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
 *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              daemon due to the daemon
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the daemon, but cannot be provided
 *                                            due to some error or other
 *                                            reasons,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_daemon_get_info_dynamic_sz (
  struct MHD_Daemon *MHD_RESTRICT daemon,
  enum MHD_DaemonInfoDynamicType info_type,
  union MHD_DaemonInfoDynamicData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);

/**
 * Obtain dynamic information about the given daemon.
 * This types of information may be changed after the start of the daemon.
 *
 * @param daemon the daemon to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
 *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              daemon due to the daemon
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the daemon, but cannot be provided
 *                                            due to some error or other
 *                                            reasons,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_daemon_get_info_dynamic(daemon, info_type, output_buf) \
        MHD_daemon_get_info_dynamic_sz ((daemon), (info_type), (output_buf), \
                                        sizeof(*(output_buf)))


/**
 * Select which fixed information about connection is desired.
 * This information is not changed during the lifetime of the connection.
 */
enum MHD_ConnectionInfoFixedType
{
  /**
   * Get the network address of the client.
   * If the connection does not have known remote address (was not provided
   * by the system or by the application in case of externally added
   * connection) then error code #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE is
   * returned if connection is IP type or unknown type or error code
   * #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if connection type is non-IP.
   * The @a sa pointer is never NULL if the function succeed (#MHD_SC_OK
   * returned).
   * The result is placed in @a v_client_address_sa_info member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_FIXED_CLIENT_ADDRESS = 1
  ,
  /**
   * Get the file descriptor for the connection socket.
   * The provided socket must be used as 'read-only': only select() or similar
   * functions should be used. Any modifications (changing socket attributes,
   * calling send() or recv(), closing it etc.) will lead to undefined
   * behaviour.
   * The result is placed in @a v_connection_socket member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_FIXED_CONNECTION_SOCKET = 2
  ,
  /**
   * Get the `struct MHD_Daemon *` responsible for managing this connection.
   * The result is placed in @a v_daemon member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_FIXED_DAEMON = 20
  ,
  /**
   * Returns the pointer to a variable pointing to connection-specific
   * application context data that was (possibly) set during
   * a #MHD_NotifyConnectionCallback or provided via @a connection_cntx
   * parameter of #MHD_daemon_add_connection().
   * By using provided pointer application may get or set the pointer to
   * any data specific for the particular connection.
   * Note: resulting data is NOT the context pointer itself.
   * The result is placed in @a v_app_context_ppvoid member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_FIXED_APP_CONTEXT = 30
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_CONNECTION_INFO_FIXED_SENTINEL = 65535
};

/**
 * Socket address information data
 */
struct MHD_ConnInfoFixedSockAddr
{
  /**
   * The size of the @a sa
   */
  size_t sa_size;

  /**
   * Socket Address type
   */
  const struct sockaddr *sa;
};

/**
 * Information about a connection.
 */
union MHD_ConnectionInfoFixedData
{

  /**
   * The data for the #MHD_CONNECTION_INFO_FIXED_CLIENT_ADDRESS query
   */
  struct MHD_ConnInfoFixedSockAddr v_client_address_sa_info;

  /**
   * The data for the #MHD_CONNECTION_INFO_FIXED_CONNECTION_SOCKET query
   */
  MHD_Socket v_connection_socket;

  /**
   * The data for the #MHD_CONNECTION_INFO_FIXED_DAEMON query
   */
  struct MHD_Daemon *v_daemon;

  /**
   * The data for the #MHD_CONNECTION_INFO_FIXED_APP_CONTEXT query
   */
  void **v_app_context_ppvoid;
};


/**
 * Obtain fixed information about the given connection.
 * This information is not changed for the lifetime of the connection.
 * The wrapper macro #MHD_connection_get_info_fixed() may be more convenient.
 *
 * @param connection the connection to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              connection due to the connection
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the connection, but cannot be
 *                                            provided due to some error or
 *                                            other reasons,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_connection_get_info_fixed_sz (
  struct MHD_Connection *MHD_RESTRICT connection,
  enum MHD_ConnectionInfoFixedType info_type,
  union MHD_ConnectionInfoFixedData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain fixed information about the given connection.
 * This information is not changed for the lifetime of the connection.
 *
 * @param connection the connection to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              connection due to the connection
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the connection, but cannot be
 *                                            provided due to some error or
 *                                            other reasons,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_connection_get_info_fixed(connection, info_type, output_buf) \
        MHD_connection_get_info_fixed_sz ((connection),(info_type), \
                                          (output_buf), sizeof(*(output_buf)))


/**
 * Select which dynamic information about connection is desired.
 * This information may be changed during the lifetime of the connection.
 */
enum MHD_ConnectionInfoDynamicType
{
  /**
   * Get current version of HTTP protocol used for connection.
   * If connection is handling HTTP/1.x requests the function may return
   * error code #MHD_SC_TOO_EARLY if the full request line has not been received
   * yet for the current request.
   * The result is placed in @a v_http_ver member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_DYNAMIC_HTTP_VER = 1
  ,
  /**
   * Get connection timeout value.
   * This is the total number of milliseconds after which the idle
   * connection is automatically disconnected.
   * Note: the value set is NOT the number of milliseconds left before
   * automatic disconnection.
   * The result is placed in @a v_connection_timeout_uint32 member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_TIMEOUT_MILSEC = 10
  ,
  /**
   * Check whether the connection is suspended.
   * The result is placed in @a v_connection_suspended_bool member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED = 11
  ,
  /**
   * Get current version of TLS transport protocol used for connection
   * If plain TCP connection is used then #MHD_TLS_VERSION_NO_TLS set in
   * the data.
   * It TLS handshake is not yet finished then error code #MHD_SC_TOO_EARLY is
   * returned. If TLS has failed or being closed then #MHD_SC_TOO_LATE error
   * code is returned.
   * If TLS version cannot be detected for any reason then error code
   * #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE is returned.
   * The result is placed in @a v_tls_ver member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_DYNAMIC_TLS_VER = 105
  ,
  /**
   * Get the TLS backend session handle.
   * If plain TCP connection is used then the function returns error code
   * #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE.
   * The resulting union has only one valid member.
   * The result is placed in @a v_tls_session member.
   * @ingroup request
   */
  MHD_CONNECTION_INFO_DYNAMIC_TLS_SESSION = 140
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_CONNECTION_INFO_DYNAMIC_SENTINEL = 65535
};


/**
 * The versions of TLS protocol
 */
enum MHD_FIXED_ENUM_MHD_SET_ MHD_TlsVersion
{

  /**
   * No TLS / plain socket connection
   */
  MHD_TLS_VERSION_NO_TLS = 0
  ,
  /**
   * Not supported/failed to negotiate/failed to handshake TLS
   */
  MHD_TLS_VERSION_BROKEN = 1
  ,
  /**
   * TLS version 1.0
   */
  MHD_TLS_VERSION_1_0 = 2
  ,
  /**
   * TLS version 1.1
   */
  MHD_TLS_VERSION_1_1 = 3
  ,
  /**
   * TLS version 1.2
   */
  MHD_TLS_VERSION_1_2 = 4
  ,
  /**
   * TLS version 1.3
   */
  MHD_TLS_VERSION_1_3 = 5
  ,
  /**
   * Some unknown TLS version.
   * The TLS version is supported by TLS backend, but unknown to MHD.
   */
  MHD_TLS_VERSION_UNKNOWN = 1999
};

/**
 * Connection TLS session information.
 * Only one member is valid. Use #MHD_DAEMON_INFO_FIXED_TLS_TYPE to find out
 * which member should be used.
 */
union MHD_ConnInfoDynamicTlsSess
{
  /* Include <gnutls/gnutls.h> before this header to get a better type safety */
  /**
   * GnuTLS session handle, of type "gnutls_session_t".
   */
#if defined(GNUTLS_VERSION_MAJOR) && GNUTLS_VERSION_MAJOR >= 3
  gnutls_session_t v_gnutls_session;
#else
  void * /* gnutls_session_t */ v_gnutls_session;
#endif

  /* Include <openssl/types.h> or <openssl/crypto.h> before this header to get
     a better type safety */
  /**
   * OpenSSL session handle, of type "SSL*".
   */
#if defined(OPENSSL_TYPES_H) && OPENSSL_VERSION_MAJOR >= 3
  SSL *v_openssl_session;
#else
  void /* SSL */ *v_openssl_session;
#endif

  /* Include <mbedtls/ssl.h> before this header to get a better type safety */
  /**
   * MbedTLS session handle, of type "mbedtls_ssl_context*".
   */
#if defined(MBEDTLS_SSL_H)
  mbedtls_ssl_context *v_mbedtls_session;
#else
  void /* mbedtls_ssl_context */ *v_mbedtls_session;
#endif
};

/**
 * Information about a connection.
 */
union MHD_ConnectionInfoDynamicData
{
  /**
   * The data for the #MHD_CONNECTION_INFO_DYNAMIC_HTTP_VER query
   */
  enum MHD_HTTP_ProtocolVersion v_http_ver;

  /**
   * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_TIMEOUT_MILSEC
   * query
   */
  uint_fast32_t v_connection_timeout_uint32;

  /**
   * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED query
   */
  enum MHD_Bool v_connection_suspended_bool;

  /**
   * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED query
   */
  enum MHD_TlsVersion v_tls_ver;

  /**
   * Connection TLS session information.
   * Only one member is valid. Use #MHD_DAEMON_INFO_FIXED_TLS_TYPE to find out
   * which member should be used.
   */
  union MHD_ConnInfoDynamicTlsSess v_tls_session;
};

/**
 * Obtain dynamic information about the given connection.
 * This information may be changed during the lifetime of the connection.
 *
 * The wrapper macro #MHD_connection_get_info_dynamic() may be more convenient.
 *
 * @param connection the connection to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the connection has not reached yet required
 *                           state,
 *         #MHD_SC_TOO_LATE if the connection is already in state where
 *                          the requested information is not available,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              connection due to the connection
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the connection, but cannot be
 *                                            provided due to some error or
 *                                            other reasons,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_connection_get_info_dynamic_sz (
  struct MHD_Connection *MHD_RESTRICT connection,
  enum MHD_ConnectionInfoDynamicType info_type,
  union MHD_ConnectionInfoDynamicData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain dynamic information about the given connection.
 * This information may be changed during the lifetime of the connection.
 *
 * @param connection the connection to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the connection has not reached yet required
 *                           state,
 *         #MHD_SC_TOO_LATE if the connection is already in state where
 *                          the requested information is not available,
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
 *                                              is not available for this
 *                                              connection due to the connection
 *                                              configuration/mode,
 *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
 *                                            should be available for
 *                                            the connection, but cannot be
 *                                            provided due to some error or
 *                                            other reasons,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_connection_get_info_dynamic(connection, info_type, output_buf) \
        MHD_connection_get_info_dynamic_sz ((connection),(info_type), \
                                            (output_buf),sizeof(*(output_buf)))


/**
 * Select which fixed information about stream is desired.
 * This information is not changed during the lifetime of the connection.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_StreamInfoFixedType
{
  /**
   * Get the `struct MHD_Daemon *` responsible for managing connection which
   * is responsible for this stream.
   * The result is placed in @a v_daemon member.
   * @ingroup request
   */
  MHD_STREAM_INFO_FIXED_DAEMON = 20
  ,
  /**
   * Get the `struct MHD_Connection *` responsible for managing this stream.
   * The result is placed in @a v_connection member.
   * @ingroup request
   */
  MHD_STREAM_INFO_FIXED_CONNECTION = 21
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_STREAM_INFO_FIXED_SENTINEL = 65535
};


/**
 * Fixed information about a stream.
 */
union MHD_StreamInfoFixedData
{
  /**
   * The data for the #MHD_STREAM_INFO_FIXED_DAEMON query
   */
  struct MHD_Daemon *v_daemon;
  /**
   * The data for the #MHD_STREAM_INFO_FIXED_CONNECTION query
   */
  struct MHD_Connection *v_connection;
};


/**
 * Obtain fixed information about the given stream.
 * This information is not changed for the lifetime of the stream.
 *
 * The wrapper macro #MHD_stream_get_info_fixed() may be more convenient.
 *
 * @param stream the stream to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_stream_get_info_fixed_sz (
  struct MHD_Stream *MHD_RESTRICT stream,
  enum MHD_StreamInfoFixedType info_type,
  union MHD_StreamInfoFixedData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain fixed information about the given stream.
 * This information is not changed for the lifetime of the tream.
 *
 * @param stream the stream to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_stream_get_info_fixed(stream, info_type, output_buf) \
        MHD_stream_get_info_fixed_sz ((stream),(info_type),(output_buf), \
                                      sizeof(*(output_buf)))


/**
 * Select which fixed information about stream is desired.
 * This information may be changed during the lifetime of the stream.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_StreamInfoDynamicType
{
  /**
   * Get the `struct MHD_Request *` for current request processed by the stream.
   * If no request is being processed, the error code #MHD_SC_TOO_EARLY is
   * returned.
   * The result is placed in @a v_request member.
   * @ingroup request
   */
  MHD_STREAM_INFO_DYNAMIC_REQUEST = 20
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_STREAM_INFO_DYNAMIC_SENTINEL = 65535
};


/**
 * Dynamic information about stream.
 * This information may be changed during the lifetime of the connection.
 */
union MHD_StreamInfoDynamicData
{
  /**
   * The data for the #MHD_STREAM_INFO_DYNAMIC_REQUEST query
   */
  struct MHD_Request *v_request;
};

/**
 * Obtain dynamic information about the given stream.
 * This information may be changed during the lifetime of the stream.
 *
 * The wrapper macro #MHD_stream_get_info_dynamic() may be more convenient.
 *
 * @param stream the stream to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the stream has not reached yet required state,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_stream_get_info_dynamic_sz (
  struct MHD_Stream *MHD_RESTRICT stream,
  enum MHD_StreamInfoDynamicType info_type,
  union MHD_StreamInfoDynamicData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain dynamic information about the given stream.
 * This information may be changed during the lifetime of the stream.
 *
 * @param stream the stream to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the stream has not reached yet required state,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_stream_get_info_dynamic(stream, info_type, output_buf) \
        MHD_stream_get_info_dynamic_sz ((stream),(info_type),(output_buf), \
                                        sizeof(*(output_buf)))


/**
 * Select which fixed information about request is desired.
 * This information is not changed during the lifetime of the request.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_RequestInfoFixedType
{
  /**
   * Get the version of HTTP protocol used for the request.
   * If request line has not been fully received yet then #MHD_SC_TOO_EARLY
   * error code is returned.
   * The result is placed in @a v_http_ver member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_FIXED_HTTP_VER = 1
  ,
  /**
   * Get the HTTP method used for the request (as a enum).
   * The result is placed in @a v_http_method member.
   * @sa #MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STR
   * @ingroup request
   */
  MHD_REQUEST_INFO_FIXED_HTTP_METHOD = 2
  ,
  /**
   * Return MHD daemon to which the request belongs to.
   * The result is placed in @a v_daemon member.
   */
  MHD_REQUEST_INFO_FIXED_DAEMON = 20
  ,
  /**
   * Return which connection is associated with the stream which is associated
   * with the request.
   * The result is placed in @a v_connection member.
   */
  MHD_REQUEST_INFO_FIXED_CONNECTION = 21
  ,
  /**
   * Return which stream the request is associated with.
   * The result is placed in @a v_stream member.
   */
  MHD_REQUEST_INFO_FIXED_STREAM = 22
  ,
  /**
   * Returns the pointer to a variable pointing to request-specific
   * application context data. The same data is provided for
   * #MHD_EarlyUriLogCallback and #MHD_RequestTerminationCallback.
   * By using provided pointer application may get or set the pointer to
   * any data specific for the particular request.
   * Note: resulting data is NOT the context pointer itself.
   * The result is placed in @a v_app_context_ppvoid member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_FIXED_APP_CONTEXT = 30
  ,

  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_REQUEST_INFO_FIXED_SENTINEL = 65535
};


/**
 * Fixed information about a request.
 */
union MHD_RequestInfoFixedData
{

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_HTTP_VER query
   */
  enum MHD_HTTP_ProtocolVersion v_http_ver;

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_HTTP_METHOD query
   */
  enum MHD_HTTP_Method v_http_method;

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_DAEMON query
   */
  struct MHD_Daemon *v_daemon;

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_CONNECTION query
   */
  struct MHD_Connection *v_connection;

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_STREAM query
   */
  struct MHD_Stream *v_stream;

  /**
   * The data for the #MHD_REQUEST_INFO_FIXED_APP_CONTEXT query
   */
  void **v_app_context_ppvoid;
};

/**
 * Obtain fixed information about the given request.
 * This information is not changed for the lifetime of the request.
 *
 * The wrapper macro #MHD_request_get_info_fixed() may be more convenient.
 *
 * @param request the request to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the request processing has not reached yet
 *                           the required state,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_request_get_info_fixed_sz (
  struct MHD_Request *MHD_RESTRICT request,
  enum MHD_RequestInfoFixedType info_type,
  union MHD_RequestInfoFixedData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain fixed information about the given request.
 * This information is not changed for the lifetime of the request.
 *
 * @param request the request to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
 *         #MHD_SC_TOO_EARLY if the request processing has not reached yet
 *                           the required state,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_request_get_info_fixed(request, info_type, output_buf) \
        MHD_request_get_info_fixed_sz ((request), (info_type), (output_buf), \
                                       sizeof(*(output_buf)))


/**
 * Select which dynamic information about request is desired.
 * This information may be changed during the lifetime of the request.
 * Any returned string pointers are valid only until a response is provided.
 */
enum MHD_FIXED_ENUM_APP_SET_ MHD_RequestInfoDynamicType
{
  /**
   * Get the HTTP method used for the request (as a MHD_String).
   * The resulting string pointer in valid only until a response is provided.
   * The result is placed in @a v_http_method_string member.
   * @sa #MHD_REQUEST_INFO_FIXED_HTTP_METHOD
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STRING = 1
  ,
  /**
   * Get the URI used for the request (as a MHD_String), excluding
   * the parameter part (anything after '?').
   * The resulting string pointer in valid only until a response is provided.
   * The result is placed in @a v_uri_string member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_URI = 2
  ,
  /**
   * Get the number of URI parameters (the decoded part of the original
   * URI string after '?'). Sometimes it is called "GET parameters".
   * The result is placed in @a v_number_uri_params_sizet member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_NUMBER_URI_PARAMS = 3
  ,
  /**
   * Get the number of cookies in the request.
   * The result is placed in @a v_number_cookies_sizet member.
   * If cookies parsing is disabled in MHD build then the function returns
   * error code #MHD_SC_FEATURE_DISABLED.
   * If cookies parsing is disabled this daemon then the function returns
   * error code #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_NUMBER_COOKIES = 4
  ,
  /**
   * Return length of the client's HTTP request header.
   * This is a total raw size of the header (after TLS decipher if any)
   * The result is placed in @a v_header_size_sizet member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_HEADER_SIZE = 5
  ,
  /**
   * Get the number of decoded POST entries in the request.
   * The result is placed in @a v_number_post_params_sizet member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_NUMBER_POST_PARAMS = 6
  ,
  /**
   * Get whether the upload content is present in the request.
   * The result is #MHD_YES if any upload content is present, even
   * if the upload content size is zero.
   * The result is placed in @a v_upload_present_bool member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_PRESENT = 10
  ,
  /**
   * Get whether the chunked upload content is present in the request.
   * The result is #MHD_YES if chunked upload content is present.
   * The result is placed in @a v_upload_chunked_bool member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_CHUNKED = 11
  ,
  /**
   * Get the total content upload size.
   * Resulted in zero if no content upload or upload content size is zero,
   * #MHD_SIZE_UNKNOWN if size is not known (chunked upload).
   * The result is placed in @a v_upload_size_total_uint64 member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TOTAL = 12
  ,
  /**
   * Get the total size of the content upload already received from the client.
   * This is the total size received, could be not yet fully processed by the
   * application.
   * The result is placed in @a v_upload_size_recieved_uint64 member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_RECIEVED = 13
  ,
  /**
   * Get the total size of the content upload left to be received from
   * the client.
   * Resulted in #MHD_SIZE_UNKNOWN if total size is not known (chunked upload).
   * The result is placed in @a v_upload_size_to_recieve_uint64 member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_RECIEVE = 14
  ,
  /**
   * Get the total size of the content upload already processed (upload callback
   * called and completed (if any)).
   * If the value is requested from #MHD_UploadCallback, then result does NOT
   * include the current data being processed by the callback.
   * The result is placed in @a v_upload_size_processed_uint64 member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_PROCESSED = 15
  ,
  /**
   * Get the total size of the content upload left to be processed.
   * The resulting value includes the size of the data not yet received from
   * the client.
   * If the value is requested from #MHD_UploadCallback, then result includes
   * the current data being processed by the callback.
   * Resulted in #MHD_SIZE_UNKNOWN if total size is not known (chunked upload).
   * The result is placed in @a v_upload_size_to_process_uint64 member.
   * @ingroup request
   */
  MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_PROCESS = 16
  ,
  /**
   * Returns pointer to information about digest auth in client request.
   * The resulting pointer is NULL if no digest auth header is set by
   * the client or the format of the digest auth header is broken.
   * Pointers in the returned structure (if any) are valid until response
   * is provided for the request.
   * The result is placed in @a v_auth_digest_info member.
   */
  MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO = 42
  ,
  /**
   * Returns information about Basic Authentication credentials in the request.
   * Pointers in the returned structure (if any) are valid until any MHD_Action
   * or MHD_UploadAction is provided. If the data is needed beyond this point,
   * it should be copied.
   * If #MHD_request_get_info_dynamic_sz() returns #MHD_SC_OK then
   * @a v_auth_basic_creds is NOT NULL and at least the username data
   * is provided.
   * The result is placed in @a v_auth_basic_creds member.
   */
  MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS = 51
  ,
  /* * Sentinel * */
  /**
   * The sentinel value.
   * This value enforces specific underlying integer type for the enum.
   * Do not use.
   */
  MHD_REQUEST_INFO_DYNAMIC_SENTINEL = 65535
};


/**
 * Dynamic information about a request.
 */
union MHD_RequestInfoDynamicData
{

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STRING query
   */
  struct MHD_String v_http_method_string;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_URI query
   */
  struct MHD_String v_uri_string;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_URI_PARAMS query
   */
  size_t v_number_uri_params_sizet;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_COOKIES query
   */
  size_t v_number_cookies_sizet;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_HEADER_SIZE query
   */
  size_t v_header_size_sizet;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_POST_PARAMS query
   */
  size_t v_number_post_params_sizet;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_PRESENT query
   */
  enum MHD_Bool v_upload_present_bool;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_CHUNKED query
   */
  enum MHD_Bool v_upload_chunked_bool;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TOTAL query
   */
  uint_fast64_t v_upload_size_total_uint64;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_RECIEVED query
   */
  uint_fast64_t v_upload_size_recieved_uint64;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_RECIEVE query
   */
  uint_fast64_t v_upload_size_to_recieve_uint64;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_PROCESSED query
   */
  uint_fast64_t v_upload_size_processed_uint64;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_PROCESS query
   */
  uint_fast64_t v_upload_size_to_process_uint64;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO query
   */
  const struct MHD_AuthDigestInfo *v_auth_digest_info;

  /**
   * The data for the #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS query
   */
  const struct MHD_AuthBasicCreds *v_auth_basic_creds;
};


/**
 * Obtain dynamic information about the given request.
 * This information may be changed during the lifetime of the request.
 * Most of the data provided is available only when the request line or complete
 * request headers are processed and not available if responding has been
 * started.
 *
 * The wrapper macro #MHD_request_get_info_dynamic() may be more convenient.
 *
 * Any pointers in the returned data are valid until any MHD_Action or
 * MHD_UploadAction is provided. If the data is needed beyond this point,
 * it should be copied.
 *
 * @param request the request to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @param output_buf_size the size of the memory area pointed by @a output_buf
 *                        (provided by the caller for storing the requested
 *                        information), in bytes
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if requested information type is
 *                                       not recognized by MHD,
 *         #MHD_SC_TOO_LATE if request is already being closed or the response
 *                          is being sent
 *         #MHD_SC_TOO_EARLY if requested data is not yet ready (for example,
 *                           headers are not yet received),
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information is
 *                                              not available for this request
 *                                              due to used configuration/mode,
 *         #MHD_SC_FEATURE_DISABLED if requested functionality is not supported
 *                                  by this MHD build,
 *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
 *         #MHD_SC_AUTH_ABSENT if request does not have particular Auth data,
 *         #MHD_SC_CONNECTION_POOL_NO_MEM_AUTH_DATA if connection memory pool
 *                                                  has no space to put decoded
 *                                                  authentication data,
 *         #MHD_SC_REQ_AUTH_DATA_BROKEN if the format of authentication data is
 *                                      incorrect or broken,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
MHD_EXTERN_ enum MHD_StatusCode
MHD_request_get_info_dynamic_sz (
  struct MHD_Request *MHD_RESTRICT request,
  enum MHD_RequestInfoDynamicType info_type,
  union MHD_RequestInfoDynamicData *MHD_RESTRICT output_buf,
  size_t output_buf_size)
MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);


/**
 * Obtain dynamic information about the given request.
 * This information may be changed during the lifetime of the request.
 * Most of the data provided is available only when the request line or complete
 * request headers are processed and not available if responding has been
 * started.
 *
 * Any pointers in the returned data are valid until any MHD_Action or
 * MHD_UploadAction is provided. If the data is needed beyond this point,
 * it should be copied.
 *
 * @param request the request to get information about
 * @param info_type the type of information requested
 * @param[out] output_buf the pointer to union to be set to the requested
 *                        information
 * @return #MHD_SC_OK if succeed,
 *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if requested information type is
 *                                       not recognized by MHD,
 *         #MHD_SC_TOO_LATE if request is already being closed or the response
 *                          is being sent
 *         #MHD_SC_TOO_EARLY if requested data is not yet ready (for example,
 *                           headers are not yet received),
 *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information is
 *                                              not available for this request
 *                                              due to used configuration/mode,
 *         #MHD_SC_FEATURE_DISABLED if requested functionality is not supported
 *                                  by this MHD build,
 *         #MHD_SC_AUTH_ABSENT if request does not have particular Auth data,
 *         #MHD_SC_CONNECTION_POOL_NO_MEM_AUTH_DATA if connection memory pool
 *                                                  has no space to put decoded
 *                                                  authentication data,
 *         #MHD_SC_REQ_AUTH_DATA_BROKEN if the format of authentication data is
 *                                      incorrect or broken,
 *         other error codes in case of other errors
 * @ingroup specialized
 */
#define MHD_request_get_info_dynamic(request, info_type, output_buf) \
        MHD_request_get_info_dynamic_sz ((request), (info_type), \
                                         (output_buf), \
                                         sizeof(*(output_buf)))

/**
 * Callback for serious error condition. The default action is to print
 * an error message and `abort()`.
 * The callback should not return.
 * Some parameters could be empty strings (the strings with zero-termination at
 * zero position) if MHD built without log messages (only for embedded
 * projects).
 *
 * @param cls user specified value
 * @param file where the error occurred, could be empty
 * @param func the name of the function, where the error occurred, may be empty
 * @param line where the error occurred
 * @param message the error details, could be empty
 * @ingroup logging
 */
typedef void
(*MHD_PanicCallback)(void *cls,
                     const char *file,
                     const char *func,
                     unsigned int line,
                     const char *message);


/**
 * Sets the global error handler to a different implementation.
 * The @a cb will only be called in the case of typically fatal, serious
 * internal consistency issues.
 * These issues should only arise in the case of serious memory corruption or
 * similar problems with the architecture.
 * The @a cb should not return.
 *
 * The default implementation that is used if no panic function is set
 * simply prints an error message and calls `abort()`.  Alternative
 * implementations might call `exit()` or other similar functions.
 *
 * @param cb new error handler, NULL to reset to default handler
 * @param cls passed to @a cb
 * @ingroup logging
 */
MHD_EXTERN_ void
MHD_lib_set_panic_func (MHD_PanicCallback cb,
                        void *cls);

#define MHD_lib_set_panic_func_default() \
        MHD_lib_set_panic_func (MHD_STATIC_CAST_ (MHD_PanicCallback,NULL),NULL)
MHD_C_DECLARATIONS_FINISH_HERE_

#endif /* ! MICROHTTPD2_H */

Coverage Report

Created: 2026-07-16 07:09