Attempt to reproduce https://github.com/curl/curl/issues/4043

4043.c

/***************************************************************************
 Attempt to reproduce https://github.com/curl/curl/issues/4043
 ***************************************************************************/

#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>

#define NUM_HANDLES 1000

void *curl_hnd[NUM_HANDLES];
int num_transfers;

/* a handle to number lookup, highly ineffective when we do many
   transfers... */
static int hnd2num(CURL *hnd)
{
  int i;
  for(i=0; i< num_transfers; i++) {
    if(curl_hnd[i] == hnd)
      return i;
  }
  return 0; /* weird, but just a fail-safe */
}

static
void dump(CURL *handle,
          const char *text, int num, 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, "[%p] %d %s, %ld bytes (0x%lx)\n",
          handle, num, text, (long)size, (long)size);
#if 0
  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 */
  }
#endif
}

static
int my_trace(CURL *handle, curl_infotype type,
             char *data, size_t size,
             void *userp)
{
  const char *text;
  int num = hnd2num(handle);
  (void)userp;
  switch (type) {
  case CURLINFO_TEXT:
    fprintf(stderr, "== %d Info: %s", num, 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:
    return 0;
  case CURLINFO_HEADER_IN:
    text = "<= Recv header";
    break;
  case CURLINFO_DATA_IN:
    text = "<= Recv data";
    break;
  case CURLINFO_SSL_DATA_IN:
    return 0;
  }

  dump(handle, text, num, (unsigned char *)data, size, 1);
  return 0;
}

static size_t write_cb(char *d, size_t n, size_t l, void *p)
{
  /* take care of the data here, ignored in this example */
  (void)d;
  (void)p;
  return n*l;
}

static void setup(CURL *hnd, int num)
{
  curl_easy_setopt(hnd, CURLOPT_WRITEFUNCTION, write_cb);

  /* set the same URL */
  curl_easy_setopt(hnd, CURLOPT_URL, "https://127.0.0.1:8443/4KB");
  curl_easy_setopt(hnd, CURLOPT_POSTFIELDS, "BBBBBBBBBBBBBBBBBBBBBB");

  /* send it verbose for max debuggaility */
  curl_easy_setopt(hnd, CURLOPT_VERBOSE, 0L);
#if 0
  curl_easy_setopt(hnd, CURLOPT_DEBUGFUNCTION, my_trace);
#endif
  /* HTTP/2 please */
  curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);

  /* timeout! */
  curl_easy_setopt(hnd, CURLOPT_TIMEOUT_MS, 1000L);

  /* 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);

  /* wait for pipe connection to confirm */
  curl_easy_setopt(hnd, CURLOPT_PIPEWAIT, 1L);
}

/*
 * Simply download two files over HTTP/2, using the same physical connection!
 */
int main(int argc, char **argv)
{
  CURL *easy[NUM_HANDLES];
  CURLM *multi_handle;
  int i;
  int still_running; /* keep number of running handles */
  CURLMsg* msg = NULL;
  int msgs_left = 0;

  if(argc > 1)
    /* if given a number, do that many transfers */
    num_transfers = atoi(argv[1]);

  if(!num_transfers || (num_transfers > NUM_HANDLES))
    num_transfers = 3; /* a suitable low default */

  /* init a multi stack */
  multi_handle = curl_multi_init();

  for(i=0; i<num_transfers; i++) {
    easy[i] = curl_easy_init();
    /* set options */
    setup(easy[i], i);

    /* add the individual transfer */
    curl_multi_add_handle(multi_handle, easy[i]);
  }

  curl_multi_setopt(multi_handle, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
  curl_multi_setopt(multi_handle, CURLMOPT_MAX_HOST_CONNECTIONS, 4L);

  /* 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;
    }
  } while(still_running);

  while ((msg = curl_multi_info_read(multi_handle, &msgs_left))) {
    if(msg->data.result)
      printf("Client code: %d\n", msg->data.result);
    curl_multi_remove_handle(multi_handle, msg->easy_handle);
  }

  curl_multi_cleanup(multi_handle);

  for(i=0; i<num_transfers; i++)
    curl_easy_cleanup(easy[i]);

  return 0;
}