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

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

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

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

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

 *

 * Copyright (C) 2017 - 2022, Max Dymond, <cmeister2@gmail.com>, 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.

 *

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

#include <stdlib.h>

#include <signal.h>

#include <string.h>

#include <unistd.h>

#include <curl/curl.h>

#include "curl_fuzzer.h"

/**

 * Fuzzing entry point. This function is passed a buffer containing a test

 * case.  This test case should drive the CURL API into making a request.

 */

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)

{

  int rc = 0;

  int tlv_rc;

  FUZZ_DATA fuzz;

  TLV tlv;

  /* Ignore SIGPIPE errors. We'll handle the errors ourselves. */

  signal(SIGPIPE, SIG_IGN);

  /* Have to set all fields to zero before getting to the terminate function */

  memset(&fuzz, 0, sizeof(FUZZ_DATA));

  if(size < sizeof(TLV_RAW)) {

    /* Not enough data for a single TLV - don't continue */

    goto EXIT_LABEL;

  }

  /* Try to initialize the fuzz data */

  FTRY(fuzz_initialize_fuzz_data(&fuzz, data, size));

  for(tlv_rc = fuzz_get_first_tlv(&fuzz, &tlv);

      tlv_rc == 0;

      tlv_rc = fuzz_get_next_tlv(&fuzz, &tlv)) {

    /* Have the TLV in hand. Parse the TLV. */

    rc = fuzz_parse_tlv(&fuzz, &tlv);

    if(rc != 0) {

      /* Failed to parse the TLV. Can't continue. */

      goto EXIT_LABEL;

    }

  }

  if(tlv_rc != TLV_RC_NO_MORE_TLVS) {

    /* A TLV call failed. Can't continue. */

    goto EXIT_LABEL;

  }

  /* Set up the standard easy options. */

  FTRY(fuzz_set_easy_options(&fuzz));

  /**

   * Add in more curl options that have been accumulated over possibly

   * multiple TLVs.

   */

  if(fuzz.header_list != NULL) {

    curl_easy_setopt(fuzz.easy, CURLOPT_HTTPHEADER, fuzz.header_list);

  }

  if(fuzz.mail_recipients_list != NULL) {

    curl_easy_setopt(fuzz.easy, CURLOPT_MAIL_RCPT, fuzz.mail_recipients_list);

  }

  if(fuzz.mime != NULL) {

    curl_easy_setopt(fuzz.easy, CURLOPT_MIMEPOST, fuzz.mime);

  }

  if (fuzz.httppost != NULL) {

    curl_easy_setopt(fuzz.easy, CURLOPT_HTTPPOST, fuzz.httppost);

  }

  /* Run the transfer. */

  fuzz_handle_transfer(&fuzz);

EXIT_LABEL:

  fuzz_terminate_fuzz_data(&fuzz);

  /* This function must always return 0. Non-zero codes are reserved. */

  return 0;

}

/**

 * Utility function to convert 4 bytes to a u32 predictably.

 */

uint32_t to_u32(const uint8_t b[4])

{

  uint32_t u;

  u = (b[0] << 24) + (b[1] << 16) + (b[2] << 8) + b[3];

  return u;

}

/**

 * Utility function to convert 2 bytes to a u16 predictably.

 */

uint16_t to_u16(const uint8_t b[2])

{

  uint16_t u;

  u = (b[0] << 8) + b[1];

  return u;

}

/**

 * Initialize the local fuzz data structure.

 */

int fuzz_initialize_fuzz_data(FUZZ_DATA *fuzz,

                              const uint8_t *data,

                              size_t data_len)

{

  int rc = 0;

  int ii;

  /* Initialize the fuzz data. */

  memset(fuzz, 0, sizeof(FUZZ_DATA));

  /* Create an easy handle. This will have all of the settings configured on

     it. */

  fuzz->easy = curl_easy_init();

  FCHECK(fuzz->easy != NULL);

  /* Set up the state parser */

  fuzz->state.data = data;

  fuzz->state.data_len = data_len;

  /* Set up the state of the server sockets. */

  for(ii = 0; ii < FUZZ_NUM_CONNECTIONS; ii++) {

    fuzz->sockman[ii].index = ii;

    fuzz->sockman[ii].fd_state = FUZZ_SOCK_CLOSED;

  }

  /* Check for verbose mode. */

  fuzz->verbose = (getenv("FUZZ_VERBOSE") != NULL);

  FCHECK(setenv("CURL_HSTS_HTTP", "1", 0) == 0);

  FCHECK(setenv("CURL_ALTSVC_HTTP", "1", 0) == 0);

EXIT_LABEL:

  return rc;

}

/**

 * Set standard options on the curl easy.

 */

int fuzz_set_easy_options(FUZZ_DATA *fuzz)

{

  int rc = 0;

  unsigned long allowed_protocols;

  /* Set some standard options on the CURL easy handle. We need to override the

     socket function so that we create our own sockets to present to CURL. */

  FTRY(curl_easy_setopt(fuzz->easy,

                        CURLOPT_OPENSOCKETFUNCTION,

                        fuzz_open_socket));

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_OPENSOCKETDATA, fuzz));

  /* In case something tries to set a socket option, intercept this. */

  FTRY(curl_easy_setopt(fuzz->easy,

                        CURLOPT_SOCKOPTFUNCTION,

                        fuzz_sockopt_callback));

  /* Set the standard read function callback. */

  FTRY(curl_easy_setopt(fuzz->easy,

                        CURLOPT_READFUNCTION,

                        fuzz_read_callback));

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_READDATA, fuzz));

  /* Set the standard write function callback. */

  FTRY(curl_easy_setopt(fuzz->easy,

                        CURLOPT_WRITEFUNCTION,

                        fuzz_write_callback));

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_WRITEDATA, fuzz));

  /* Set the writable cookie jar path so cookies are tested. */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_COOKIEJAR, FUZZ_COOKIE_JAR_PATH));

  /* Set the RO cookie file path so cookies are tested. */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_COOKIEFILE, FUZZ_RO_COOKIE_FILE_PATH));

  /* Set altsvc header cache filepath so that it can be fuzzed. */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_ALTSVC, FUZZ_ALT_SVC_HEADER_CACHE_PATH));

  /* Set the hsts header cache filepath so that it can be fuzzed. */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_HSTS, FUZZ_HSTS_HEADER_CACHE_PATH));

  /* Set the Certificate Revocation List file path so it can be fuzzed */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_CRLFILE, FUZZ_CRL_FILE_PATH));

  /* Set the .netrc file path so it can be fuzzed */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_NETRC_FILE, FUZZ_NETRC_FILE_PATH));

  /* Time out requests quickly. */

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_TIMEOUT_MS, 200L));

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_SERVER_RESPONSE_TIMEOUT, 1L));

  /* Can enable verbose mode by having the environment variable FUZZ_VERBOSE. */

  if(fuzz->verbose) {

    FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_VERBOSE, 1L));

  }

  /* Force resolution of all addresses to a specific IP address. */

  fuzz->connect_to_list = curl_slist_append(NULL, "::127.0.1.127:");

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_CONNECT_TO, fuzz->connect_to_list));

  /* Limit the protocols in use by this fuzzer. */

  FTRY(fuzz_set_allowed_protocols(fuzz));

EXIT_LABEL:

  return rc;

}

/**

 * Terminate the fuzz data structure, including freeing any allocated memory.

 */

void fuzz_terminate_fuzz_data(FUZZ_DATA *fuzz)

{

  int ii;

  fuzz_free((void **)&fuzz->postfields);

  for(ii = 0; ii < FUZZ_NUM_CONNECTIONS; ii++) {

    if(fuzz->sockman[ii].fd_state != FUZZ_SOCK_CLOSED) {

      close(fuzz->sockman[ii].fd);

      fuzz->sockman[ii].fd_state = FUZZ_SOCK_CLOSED;

    }

  }

  if(fuzz->connect_to_list != NULL) {

    curl_slist_free_all(fuzz->connect_to_list);

    fuzz->connect_to_list = NULL;

  }

  if(fuzz->header_list != NULL) {

    curl_slist_free_all(fuzz->header_list);

    fuzz->header_list = NULL;

  }

  if(fuzz->mail_recipients_list != NULL) {

    curl_slist_free_all(fuzz->mail_recipients_list);

    fuzz->mail_recipients_list = NULL;

  }

  if(fuzz->mime != NULL) {

    curl_mime_free(fuzz->mime);

    fuzz->mime = NULL;

  }

  if(fuzz->easy != NULL) {

    curl_easy_cleanup(fuzz->easy);

    fuzz->easy = NULL;

  }

  /* When you have passed the struct curl_httppost pointer to curl_easy_setopt

   * (using the CURLOPT_HTTPPOST option), you must not free the list until after

   *  you have called curl_easy_cleanup for the curl handle.

   *  https://curl.se/libcurl/c/curl_formadd.html */

  if (fuzz->httppost != NULL) {

    curl_formfree(fuzz->httppost);

    fuzz->httppost = NULL;

  }

  // free after httppost and last_post_part.

  if (fuzz->post_body != NULL) {

    fuzz_free((void **)&fuzz->post_body);

  }

}

/**

 * If a pointer has been allocated, free that pointer.

 */

void fuzz_free(void **ptr)

{

  if(*ptr != NULL) {

    free(*ptr);

    *ptr = NULL;

  }

}

/**

 * Function for handling the fuzz transfer, including sending responses to

 * requests.

 */

int fuzz_handle_transfer(FUZZ_DATA *fuzz)

{

  int rc = 0;

  CURLM *multi_handle;

  int still_running; /* keep number of running handles */

  CURLMsg *msg; /* for picking up messages with the transfer status */

  int msgs_left; /* how many messages are left */

  int double_timeout = 0;

  fd_set fdread;

  fd_set fdwrite;

  fd_set fdexcep;

  struct timeval timeout;

  int select_rc;

  CURLMcode mc;

  int maxfd = -1;

  long curl_timeo = -1;

  int ii;

  FUZZ_SOCKET_MANAGER *sman[FUZZ_NUM_CONNECTIONS];

  for(ii = 0; ii < FUZZ_NUM_CONNECTIONS; ii++) {

    sman[ii] = &fuzz->sockman[ii];

    /* Set up the starting index for responses. */

    sman[ii]->response_index = 1;

  }

  /* init a multi stack */

  multi_handle = curl_multi_init();

  /* add the individual transfers */

  curl_multi_add_handle(multi_handle, fuzz->easy);

  /* Do an initial process. This might end the transfer immediately. */

  curl_multi_perform(multi_handle, &still_running);

  FV_PRINTF(fuzz,

            "FUZZ: Initial perform; still running? %d \n",

            still_running);

  while(still_running) {

    /* Reset the sets of file descriptors. */

    FD_ZERO(&fdread);

    FD_ZERO(&fdwrite);

    FD_ZERO(&fdexcep);

    /* Set a timeout of 10ms. This is lower than recommended by the multi guide

       but we're not going to any remote servers, so everything should complete

       very quickly. */

    timeout.tv_sec = 0;

    timeout.tv_usec = 10000;

    /* get file descriptors from the transfers */

    mc = curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);

    if(mc != CURLM_OK) {

      fprintf(stderr, "curl_multi_fdset() failed, code %d.\n", mc);

      rc = -1;

      break;

    }

    for(ii = 0; ii < FUZZ_NUM_CONNECTIONS; ii++) {

      /* Add the socket FD into the readable set if connected. */

      if(sman[ii]->fd_state == FUZZ_SOCK_OPEN) {

        FD_SET(sman[ii]->fd, &fdread);

        /* Work out the maximum FD between the cURL file descriptors and the

           server FD. */

        maxfd = FUZZ_MAX(sman[ii]->fd, maxfd);

      }

    }

    /* Work out what file descriptors need work. */

    rc = fuzz_select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);

    if(rc == -1) {

      /* Had an issue while selecting a file descriptor. Let's just exit. */

      FV_PRINTF(fuzz, "FUZZ: select failed, exiting \n");

      break;

    }

    else if(rc == 0) {

      FV_PRINTF(fuzz,

                "FUZZ: Timed out; double timeout? %d \n",

                double_timeout);

      /* Timed out. */

      if(double_timeout == 1) {

        /* We don't expect multiple timeouts in a row. If there are double

           timeouts then exit. */

        break;

      }

      else {

        /* Set the timeout flag for the next time we select(). */

        double_timeout = 1;

      }

    }

    else {

      /* There's an active file descriptor. Reset the timeout flag. */

      double_timeout = 0;

    }

    /* Check to see if a server file descriptor is readable. If it is,

       then send the next response from the fuzzing data. */

    for(ii = 0; ii < FUZZ_NUM_CONNECTIONS; ii++) {

      if(sman[ii]->fd_state == FUZZ_SOCK_OPEN &&

         FD_ISSET(sman[ii]->fd, &fdread)) {

        rc = fuzz_send_next_response(fuzz, sman[ii]);

        if(rc != 0) {

          /* Failed to send a response. Break out here. */

          break;

        }

      }

    }

    curl_multi_perform(multi_handle, &still_running);

  }

  /* Remove the easy handle from the multi stack. */

  curl_multi_remove_handle(multi_handle, fuzz->easy);

  /* Clean up the multi handle - the top level function will handle the easy

     handle. */

  curl_multi_cleanup(multi_handle);

  return(rc);

}

/**

 * Sends the next fuzzing response to the server file descriptor.

 */

int fuzz_send_next_response(FUZZ_DATA *fuzz, FUZZ_SOCKET_MANAGER *sman)

{

  int rc = 0;

  ssize_t ret_in;

  ssize_t ret_out;

  char buffer[8192];

  const uint8_t *data;

  size_t data_len;

  /* Need to read all data sent by the client so the file descriptor becomes

     unreadable. Because the file descriptor is non-blocking we won't just

     hang here. */

  do {

    ret_in = read(sman->fd, buffer, sizeof(buffer));

    if(fuzz->verbose && ret_in > 0) {

      printf("FUZZ[%d]: Received %zu bytes \n==>\n", sman->index, ret_in);

      fwrite(buffer, ret_in, 1, stdout);

      printf("\n<==\n");

    }

  } while (ret_in > 0);

  /* Now send a response to the request that the client just made. */

  FV_PRINTF(fuzz,

            "FUZZ[%d]: Sending next response: %d \n",

            sman->index,

            sman->response_index);

  data = sman->responses[sman->response_index].data;

  data_len = sman->responses[sman->response_index].data_len;

  if(data != NULL) {

    if(write(sman->fd, data, data_len) != (ssize_t)data_len) {

      /* Failed to write the data back to the client. Prevent any further

         testing. */

      rc = -1;

    }

  }

  /* Work out if there are any more responses. If not, then shut down the

     server. */

  sman->response_index++;

  if(sman->response_index >= TLV_MAX_NUM_RESPONSES ||

     sman->responses[sman->response_index].data == NULL) {

    FV_PRINTF(fuzz,

              "FUZZ[%d]: Shutting down server socket: %d \n",

              sman->index,

              sman->fd);

    shutdown(sman->fd, SHUT_WR);

    sman->fd_state = FUZZ_SOCK_SHUTDOWN;

  }

  return(rc);

}

/**

 * Wrapper for select() so profiling can track it.

 */

int fuzz_select(int nfds,

                fd_set *readfds,

                fd_set *writefds,

                fd_set *exceptfds,

                struct timeval *timeout) {

  return select(nfds, readfds, writefds, exceptfds, timeout);

}

/**

 * Set allowed protocols based on the compile options.

 *

 * Note that it can only use ONE of the FUZZ_PROTOCOLS_* defines.a

 */

int fuzz_set_allowed_protocols(FUZZ_DATA *fuzz)

{

  int rc = 0;

  const char *allowed_protocols = "";

#ifdef FUZZ_PROTOCOLS_ALL

  /* Do not allow telnet currently as it accepts input from stdin. */

  allowed_protocols =

    "dict,file,ftp,ftps,gopher,gophers,http,https,imap,imaps,"

    "mqtt,pop3,pop3s,"

    "rtsp,smb,smbs,smtp,smtps,tftp";

#endif

#ifdef FUZZ_PROTOCOLS_DICT

  allowed_protocols = "dict";

#endif

#ifdef FUZZ_PROTOCOLS_FILE

  allowed_protocols = "file";

#endif

#ifdef FUZZ_PROTOCOLS_FTP

  allowed_protocols = "ftp,ftps";

#endif

#ifdef FUZZ_PROTOCOLS_GOPHER

  allowed_protocols = "gopher,gophers";

#endif

#ifdef FUZZ_PROTOCOLS_HTTP

  allowed_protocols = "http";

#endif

#ifdef FUZZ_PROTOCOLS_HTTPS

  allowed_protocols = "https";

#endif

#ifdef FUZZ_PROTOCOLS_IMAP

  allowed_protocols = "imap,imaps";

#endif

#ifdef FUZZ_PROTOCOLS_LDAP

  allowed_protocols = "ldap,ldaps";

#endif

#ifdef FUZZ_PROTOCOLS_MQTT

  allowed_protocols = "mqtt";

#endif

#ifdef FUZZ_PROTOCOLS_POP3

  allowed_protocols = "pop3,pop3s";

#endif

#ifdef FUZZ_PROTOCOLS_RTMP

  allowed_protocols = "rtmp,rtmpe,rtmps,rtmpt,rtmpte,rtmpts";

#endif

#ifdef FUZZ_PROTOCOLS_RTSP

  allowed_protocols = "rtsp";

#endif

#ifdef FUZZ_PROTOCOLS_SCP

  allowed_protocols = "scp";

#endif

#ifdef FUZZ_PROTOCOLS_SFTP

  allowed_protocols = "sftp";

#endif

#ifdef FUZZ_PROTOCOLS_SMB

  allowed_protocols = "smb,smbs";

#endif

#ifdef FUZZ_PROTOCOLS_SMTP

  allowed_protocols = "smtp,smtps";

#endif

#ifdef FUZZ_PROTOCOLS_TFTP

  allowed_protocols = "tftp";

#endif

#ifdef FUZZ_PROTOCOLS_WS

  allowed_protocols = "ws,wss";

#endif

  FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_PROTOCOLS_STR, allowed_protocols));

EXIT_LABEL:

  return rc;

}