curl / libcurl / API / Examples / http2-serverpush.c

http2-serverpush.c

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/***************************************************************************
 *                                  _   _ ____  _
 *  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, %ld bytes (0x%lx)\n",
          text, (long)size, (long)size);
 
  for(i=0; i<size; i+= width) {
 
    fprintf(stderr, "%4.4lx: ", (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);
  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 %d headers!\n",
          count, (int)num_headers);
 
  for(i=0; i<num_headers; i++) {
    headp = curl_pushheader_bynum(headers, i);
    fprintf(stderr, "**** header %u: %s\n", (int)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;
}