/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) 2022, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

#include "curl_setup.h"

#include "urldata.h"

#include "strdup.h"

#include "strcase.h"

#include "headers.h"

/* The last 3 #include files should be in this order */

#include "curl_printf.h"

#include "curl_memory.h"

#include "memdebug.h"

#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_HEADERS_API)

/* Generate the curl_header struct for the user. This function MUST assign all

   struct fields in the output struct. */

static void copy_header_external(struct Curl_easy *data,

                                 struct Curl_header_store *hs,

                                 size_t index,

                                 size_t amount,

                                 struct Curl_llist_element *e,

                                 struct curl_header **hout)

{

  struct curl_header *h = *hout = &data->state.headerout;

  h->name = hs->name;

  h->value = hs->value;

  h->amount = amount;

  h->index = index;

  /* this will randomly OR a reserved bit for the sole purpose of making it

     impossible for applications to do == comparisons, as that would otherwise

     be very tempting and then lead to the reserved bits not being reserved

     anymore. */

  h->origin = hs->type | (1<<27);

  h->anchor = e;

}

/* public API */

CURLHcode curl_easy_header(CURL *easy,

                           const char *name,

                           size_t nameindex,

                           unsigned int type,

                           int request,

                           struct curl_header **hout)

{

  struct Curl_llist_element *e;

  struct Curl_llist_element *e_pick = NULL;

  struct Curl_easy *data = easy;

  size_t match = 0;

  size_t amount = 0;

  struct Curl_header_store *hs = NULL;

  struct Curl_header_store *pick = NULL;

  if(!name || !hout || !data ||

     (type > (CURLH_HEADER|CURLH_TRAILER|CURLH_CONNECT|CURLH_1XX|

              CURLH_PSEUDO)) || !type || (request < -1))

    return CURLHE_BAD_ARGUMENT;

  if(!Curl_llist_count(&data->state.httphdrs))

    return CURLHE_NOHEADERS; /* no headers available */

  if(request > data->state.requests)

    return CURLHE_NOREQUEST;

  if(request == -1)

    request = data->state.requests;

  /* we need a first round to count amount of this header */

  for(e = data->state.httphdrs.head; e; e = e->next) {

    hs = e->ptr;

    if(strcasecompare(hs->name, name) &&

       (hs->type & type) &&

       (hs->request == request)) {

      amount++;

      pick = hs;

      e_pick = e;

    }

  }

  if(!amount)

    return CURLHE_MISSING;

  else if(nameindex >= amount)

    return CURLHE_BADINDEX;

  if(nameindex == amount - 1)

    /* if the last or only occurrence is what's asked for, then we know it */

    hs = pick;

  else {

    for(e = data->state.httphdrs.head; e; e = e->next) {

      hs = e->ptr;

      if(strcasecompare(hs->name, name) &&

         (hs->type & type) &&

         (hs->request == request) &&

         (match++ == nameindex)) {

        e_pick = e;

        break;

      }

    }

    if(!e) /* this shouldn't happen */

      return CURLHE_MISSING;

  }

  /* this is the name we want */

  copy_header_external(data, hs, nameindex, amount, e_pick, hout);

  return CURLHE_OK;

}

/* public API */

struct curl_header *curl_easy_nextheader(CURL *easy,

                                         unsigned int type,

                                         int request,

                                         struct curl_header *prev)

{

  struct Curl_easy *data = easy;

  struct Curl_llist_element *pick;

  struct Curl_llist_element *e;

  struct Curl_header_store *hs;

  struct curl_header *hout;

  size_t amount = 0;

  size_t index = 0;

  if(request > data->state.requests)

    return NULL;

  if(request == -1)

    request = data->state.requests;

  if(prev) {

    pick = prev->anchor;

    if(!pick)

      /* something is wrong */

      return NULL;

    pick = pick->next;

  }

  else

    pick = data->state.httphdrs.head;

  if(pick) {

    /* make sure it is the next header of the desired type */

    do {

      hs = pick->ptr;

      if((hs->type & type) && (hs->request == request))

        break;

      pick = pick->next;

    } while(pick);

  }

  if(!pick)

    /* no more headers available */

    return NULL;

  hs = pick->ptr;

  /* count number of occurrences of this name within the mask and figure out

     the index for the currently selected entry */

  for(e = data->state.httphdrs.head; e; e = e->next) {

    struct Curl_header_store *check = e->ptr;

    if(strcasecompare(hs->name, check->name) &&

       (check->request == request) &&

       (check->type & type))

      amount++;

    if(e == pick)

      index = amount - 1;

  }

  copy_header_external(data, hs, index, amount, pick, &hout);

  return hout;

}

static CURLcode namevalue(char *header, size_t hlen, unsigned int type,

                           char **name, char **value)

{

  char *end = header + hlen - 1; /* point to the last byte */

  DEBUGASSERT(hlen);

  *name = header;

  if(type == CURLH_PSEUDO) {

    if(*header != ':')

      return CURLE_BAD_FUNCTION_ARGUMENT;

    header++;

  }

  /* Find the end of the header name */

  while(*header && (*header != ':'))

    ++header;

  if(*header)

    /* Skip over colon, null it */

    *header++ = 0;

  else

    return CURLE_BAD_FUNCTION_ARGUMENT;

  /* skip all leading space letters */

  while(*header && ISBLANK(*header))

    header++;

  *value = header;

  /* skip all trailing space letters */

  while((end > header) && ISSPACE(*end))

    *end-- = 0; /* nul terminate */

  return CURLE_OK;

}

static CURLcode unfold_value(struct Curl_easy *data, const char *value,

                             size_t vlen)  /* length of the incoming header */

{

  struct Curl_header_store *hs;

  struct Curl_header_store *newhs;

  size_t olen; /* length of the old value */

  size_t oalloc; /* length of the old name + value + separator */

  size_t offset;

  DEBUGASSERT(data->state.prevhead);

  hs = data->state.prevhead;

  olen = strlen(hs->value);

  offset = hs->value - hs->buffer;

  oalloc = olen + offset + 1;

  /* skip all trailing space letters */

  while(vlen && ISSPACE(value[vlen - 1]))

    vlen--;

  /* save only one leading space */

  while((vlen > 1) && ISBLANK(value[0]) && ISBLANK(value[1])) {

    vlen--;

    value++;

  }

  /* since this header block might move in the realloc below, it needs to

     first be unlinked from the list and then re-added again after the

     realloc */

  Curl_llist_remove(&data->state.httphdrs, &hs->node, NULL);

  /* new size = struct + new value length + old name+value length */

  newhs = Curl_saferealloc(hs, sizeof(*hs) + vlen + oalloc + 1);

  if(!newhs)

    return CURLE_OUT_OF_MEMORY;

  /* ->name' and ->value point into ->buffer (to keep the header allocation

     in a single memory block), which now potentially have moved. Adjust

     them. */

  newhs->name = newhs->buffer;

  newhs->value = &newhs->buffer[offset];

  /* put the data at the end of the previous data, not the newline */

  memcpy(&newhs->value[olen], value, vlen);

  newhs->value[olen + vlen] = 0; /* null-terminate at newline */

  /* insert this node into the list of headers */

  Curl_llist_insert_next(&data->state.httphdrs, data->state.httphdrs.tail,

                         newhs, &newhs->node);

  data->state.prevhead = newhs;

  return CURLE_OK;

}

/*

 * Curl_headers_push() gets passed a full HTTP header to store. It gets called

 * immediately before the header callback. The header is CRLF terminated.

 */

CURLcode Curl_headers_push(struct Curl_easy *data, const char *header,

                           unsigned char type)

{

  char *value = NULL;

  char *name = NULL;

  char *end;

  size_t hlen; /* length of the incoming header */

  struct Curl_header_store *hs;

  CURLcode result = CURLE_OUT_OF_MEMORY;

  if((header[0] == '\r') || (header[0] == '\n'))

    /* ignore the body separator */

    return CURLE_OK;

  end = strchr(header, '\r');

  if(!end) {

    end = strchr(header, '\n');

    if(!end)

      return CURLE_BAD_FUNCTION_ARGUMENT;

  }

  hlen = end - header + 1;

  if((header[0] == ' ') || (header[0] == '\t')) {

    if(data->state.prevhead)

      /* line folding, append value to the previous header's value */

      return unfold_value(data, header, hlen);

    else

      /* can't unfold without a previous header */

      return CURLE_BAD_FUNCTION_ARGUMENT;

  }

  hs = calloc(1, sizeof(*hs) + hlen);

  if(!hs)

    return CURLE_OUT_OF_MEMORY;

  memcpy(hs->buffer, header, hlen);

  hs->buffer[hlen] = 0; /* nul terminate */

  result = namevalue(hs->buffer, hlen, type, &name, &value);

  if(result)

    goto fail;

  hs->name = name;

  hs->value = value;

  hs->type = type;

  hs->request = data->state.requests;

  /* insert this node into the list of headers */

  Curl_llist_insert_next(&data->state.httphdrs, data->state.httphdrs.tail,

                         hs, &hs->node);

  data->state.prevhead = hs;

  return CURLE_OK;

  fail:

  free(hs);

  return result;

}

/*

 * Curl_headers_init(). Init the headers subsystem.

 */

static void headers_init(struct Curl_easy *data)

{

  Curl_llist_init(&data->state.httphdrs, NULL);

}

/*

 * Curl_headers_cleanup(). Free all stored headers and associated memory.

 */

CURLcode Curl_headers_cleanup(struct Curl_easy *data)

{

  struct Curl_llist_element *e;

  struct Curl_llist_element *n;

  for(e = data->state.httphdrs.head; e; e = n) {

    struct Curl_header_store *hs = e->ptr;

    n = e->next;

    free(hs);

  }

  headers_init(data);

  return CURLE_OK;

}

#else /* HTTP-disabled builds below */

CURLHcode curl_easy_header(CURL *easy,

                           const char *name,

                           size_t index,

                           unsigned int origin,

                           int request,

                           struct curl_header **hout)

{

  (void)easy;

  (void)name;

  (void)index;

  (void)origin;

  (void)request;

  (void)hout;

  return CURLHE_NOT_BUILT_IN;

}

struct curl_header *curl_easy_nextheader(CURL *easy,

                                         unsigned int type,

                                         int request,

                                         struct curl_header *prev)

{

  (void)easy;

  (void)type;

  (void)request;

  (void)prev;

  return NULL;

}

#endif