text: /***************************************************************************
   *                                  _   _ ____  _
   *  Project                     ___| | | |  _ \| |
   *                             / __| | | | |_) | |
   *                            | (__| |_| |  _ <| |___
   *                             \___|\___/|_| \_\_____|
   *
   * Copyright (C) 1998 - 2017, 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.haxx.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.
   *
   ***************************************************************************/
  /* <DESC>
   * HTTP/2 server push
   * </DESC>
   */
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  /* somewhat unix-specific */
  #include <sys/time.h>
  #include <unistd.h>
  
  /* curl stuff */
  #include <curl/curl.h>
  
  #ifndef CURLPIPE_MULTIPLEX
  #error "too old libcurl, can't do HTTP/2 server push!"
  #endif
  
  static
  void dump(const char *text, unsigned char *ptr, size_t size,
            char nohex)
  {
    size_t i;
    size_t c;
  
    unsigned int width = 0x10;
  
    if(nohex)
      /* without the hex output, we can fit more on screen */
      width = 0x40;
  
    fprintf(stderr, "%s, %lu bytes (0x%lx)\n",
            text, (unsigned long)size, (unsigned long)size);
  
    for(i = 0; i<size; i += width) {
  
      fprintf(stderr, "%4.4lx: ", (unsigned long)i);
  
      if(!nohex) {
        /* hex not disabled, show it */
        for(c = 0; c < width; c++)
          if(i + c < size)
            fprintf(stderr, "%02x ", ptr[i + c]);
          else
            fputs("   ", stderr);
      }
  
      for(c = 0; (c < width) && (i + c < size); c++) {
        /* check for 0D0A; if found, skip past and start a new line of output */
        if(nohex && (i + c + 1 < size) && ptr[i + c] == 0x0D &&
           ptr[i + c + 1] == 0x0A) {
          i += (c + 2 - width);
          break;
        }
        fprintf(stderr, "%c",
                (ptr[i + c] >= 0x20) && (ptr[i + c]<0x80)?ptr[i + c]:'.');
        /* check again for 0D0A, to avoid an extra \n if it's at width */
        if(nohex && (i + c + 2 < size) && ptr[i + c + 1] == 0x0D &&
           ptr[i + c + 2] == 0x0A) {
          i += (c + 3 - width);
          break;
        }
      }
      fputc('\n', stderr); /* newline */
    }
  }
  
  static
  int my_trace(CURL *handle, curl_infotype type,
               char *data, size_t size,
               void *userp)
  {
    const char *text;
    (void)handle; /* prevent compiler warning */
    (void)userp;
    switch(type) {
    case CURLINFO_TEXT:
      fprintf(stderr, "== Info: %s", data);
      /* FALLTHROUGH */
    default: /* in case a new one is introduced to shock us */
      return 0;
  
    case CURLINFO_HEADER_OUT:
      text = "=> Send header";
      break;
    case CURLINFO_DATA_OUT:
      text = "=> Send data";
      break;
    case CURLINFO_SSL_DATA_OUT:
      text = "=> Send SSL data";
      break;
    case CURLINFO_HEADER_IN:
      text = "<= Recv header";
      break;
    case CURLINFO_DATA_IN:
      text = "<= Recv data";
      break;
    case CURLINFO_SSL_DATA_IN:
      text = "<= Recv SSL data";
      break;
    }
  
    dump(text, (unsigned char *)data, size, 1);
    return 0;
  }
  
  #define OUTPUTFILE "dl"
  
  static void setup(CURL *hnd)
  {
    FILE *out = fopen(OUTPUTFILE, "wb");
  
    /* write to this file */
    curl_easy_setopt(hnd, CURLOPT_WRITEDATA, out);
  
    /* set the same URL */
    curl_easy_setopt(hnd, CURLOPT_URL, "https://localhost:8443/index.html");
  
    /* please be verbose */
    curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
    curl_easy_setopt(hnd, CURLOPT_DEBUGFUNCTION, my_trace);
  
    /* HTTP/2 please */
    curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
  
    /* we use a self-signed test server, skip verification during debugging */
    curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYPEER, 0L);
    curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYHOST, 0L);
  
  #if (CURLPIPE_MULTIPLEX > 0)
    /* wait for pipe connection to confirm */
    curl_easy_setopt(hnd, CURLOPT_PIPEWAIT, 1L);
  #endif
  
  }
  
  /* called when there's an incoming push */
  static int server_push_callback(CURL *parent,
                                  CURL *easy,
                                  size_t num_headers,
                                  struct curl_pushheaders *headers,
                                  void *userp)
  {
    char *headp;
    size_t i;
    int *transfers = (int *)userp;
    char filename[128];
    FILE *out;
    static unsigned int count = 0;
  
    (void)parent; /* we have no use for this */
  
    snprintf(filename, 128, "push%u", count++);
  
    /* here's a new stream, save it in a new file for each new push */
    out = fopen(filename, "wb");
  
    /* write to this file */
    curl_easy_setopt(easy, CURLOPT_WRITEDATA, out);
  
    fprintf(stderr, "**** push callback approves stream %u, got %lu headers!\n",
            count, (unsigned long)num_headers);
  
    for(i = 0; i<num_headers; i++) {
      headp = curl_pushheader_bynum(headers, i);
      fprintf(stderr, "**** header %lu: %s\n", (unsigned long)i, headp);
    }
  
    headp = curl_pushheader_byname(headers, ":path");
    if(headp) {
      fprintf(stderr, "**** The PATH is %s\n", headp /* skip :path + colon */);
    }
  
    (*transfers)++; /* one more */
    return CURL_PUSH_OK;
  }
  
  
  /*
   * Download a file over HTTP/2, take care of server push.
   */
  int main(void)
  {
    CURL *easy;
    CURLM *multi_handle;
    int still_running; /* keep number of running handles */
    int transfers = 1; /* we start with one */
    struct CURLMsg *m;
  
    /* init a multi stack */
    multi_handle = curl_multi_init();
  
    easy = curl_easy_init();
  
    /* set options */
    setup(easy);
  
    /* add the easy transfer */
    curl_multi_add_handle(multi_handle, easy);
  
    curl_multi_setopt(multi_handle, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
    curl_multi_setopt(multi_handle, CURLMOPT_PUSHFUNCTION, server_push_callback);
    curl_multi_setopt(multi_handle, CURLMOPT_PUSHDATA, &transfers);
  
    /* we start some action by calling perform right away */
    curl_multi_perform(multi_handle, &still_running);
  
    do {
      struct timeval timeout;
      int rc; /* select() return code */
      CURLMcode mc; /* curl_multi_fdset() return code */
  
      fd_set fdread;
      fd_set fdwrite;
      fd_set fdexcep;
      int maxfd = -1;
  
      long curl_timeo = -1;
  
      FD_ZERO(&fdread);
      FD_ZERO(&fdwrite);
      FD_ZERO(&fdexcep);
  
      /* set a suitable timeout to play around with */
      timeout.tv_sec = 1;
      timeout.tv_usec = 0;
  
      curl_multi_timeout(multi_handle, &curl_timeo);
      if(curl_timeo >= 0) {
        timeout.tv_sec = curl_timeo / 1000;
        if(timeout.tv_sec > 1)
          timeout.tv_sec = 1;
        else
          timeout.tv_usec = (curl_timeo % 1000) * 1000;
      }
  
      /* 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);
        break;
      }
  
      /* On success the value of maxfd is guaranteed to be >= -1. We call
         select(maxfd + 1, ...); specially in case of (maxfd == -1) there are
         no fds ready yet so we call select(0, ...) --or Sleep() on Windows--
         to sleep 100ms, which is the minimum suggested value in the
         curl_multi_fdset() doc. */
  
      if(maxfd == -1) {
  #ifdef _WIN32
        Sleep(100);
        rc = 0;
  #else
        /* Portable sleep for platforms other than Windows. */
        struct timeval wait = { 0, 100 * 1000 }; /* 100ms */
        rc = select(0, NULL, NULL, NULL, &wait);
  #endif
      }
      else {
        /* Note that on some platforms 'timeout' may be modified by select().
           If you need access to the original value save a copy beforehand. */
        rc = select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
      }
  
      switch(rc) {
      case -1:
        /* select error */
        break;
      case 0:
      default:
        /* timeout or readable/writable sockets */
        curl_multi_perform(multi_handle, &still_running);
        break;
      }
  
      /*
       * A little caution when doing server push is that libcurl itself has
       * created and added one or more easy handles but we need to clean them up
       * when we are done.
       */
  
      do {
        int msgq = 0;;
        m = curl_multi_info_read(multi_handle, &msgq);
        if(m && (m->msg == CURLMSG_DONE)) {
          CURL *e = m->easy_handle;
          transfers--;
          curl_multi_remove_handle(multi_handle, e);
          curl_easy_cleanup(e);
        }
      } while(m);
  
    } while(transfers); /* as long as we have transfers going */
  
    curl_multi_cleanup(multi_handle);
  
  
    return 0;
  }
  