curl/lib/asyn-base.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 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"

/***********************************************************************
 * Only for builds using asynchronous name resolves
 **********************************************************************/
#ifdef CURLRES_ASYNCH

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef __VMS
#include <in.h>
#include <inet.h>
#endif

#ifdef USE_ARES
#include <ares.h>
#include <ares_version.h> /* really old c-ares did not include this by
                             itself */
#endif

#include "urldata.h"
#include "asyn.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "multiif.h"
#include "select.h"
#include "share.h"
#include "url.h"
#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"


#ifdef USE_ARES
/* common functions for c-ares and threaded resolver with HTTPSRR */

#ifdef USE_HTTPSRR
/* 1.28.0 and later have ares_query_dnsrec */
#if ARES_VERSION < 0x011c00
#error "requires c-ares 1.28.0 or newer for HTTPSRR"
#endif
#define HTTPSRR_WORKS
#else
#if ARES_VERSION < 0x010600
#error "requires c-ares 1.6.0 or newer"
#endif
#endif

/*
 * Curl_ares_getsock() is called when the outside world (using
 * curl_multi_fdset()) wants to get our fd_set setup and we are talking with
 * ares. The caller must make sure that this function is only called when we
 * have a working ares channel.
 *
 * Returns: sockets-in-use-bitmap
 */

int Curl_ares_getsock(struct Curl_easy *data,
                      ares_channel channel,
                      curl_socket_t *socks)
{
  struct timeval maxtime = { CURL_TIMEOUT_RESOLVE, 0 };
  struct timeval timebuf;
  int max = ares_getsock(channel,
                         (ares_socket_t *)socks, MAX_SOCKSPEREASYHANDLE);
  struct timeval *timeout = ares_timeout(channel, &maxtime, &timebuf);
  timediff_t milli = curlx_tvtoms(timeout);
  Curl_expire(data, milli, EXPIRE_ASYNC_NAME);
  return max;
}

/*
 * Curl_ares_perform()
 *
 * 1) Ask ares what sockets it currently plays with, then
 * 2) wait for the timeout period to check for action on ares' sockets.
 * 3) tell ares to act on all the sockets marked as "with action"
 *
 * return number of sockets it worked on, or -1 on error
 */
int Curl_ares_perform(ares_channel channel,
                      timediff_t timeout_ms)
{
  int nfds;
  int bitmask;
  ares_socket_t socks[ARES_GETSOCK_MAXNUM];
  struct pollfd pfd[ARES_GETSOCK_MAXNUM];
  int i;
  int num = 0;

  if(!channel)
    return 0;

  bitmask = ares_getsock(channel, socks, ARES_GETSOCK_MAXNUM);

  for(i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
    pfd[i].events = 0;
    pfd[i].revents = 0;
    if(ARES_GETSOCK_READABLE(bitmask, i)) {
      pfd[i].fd = socks[i];
      pfd[i].events |= POLLRDNORM|POLLIN;
    }
    if(ARES_GETSOCK_WRITABLE(bitmask, i)) {
      pfd[i].fd = socks[i];
      pfd[i].events |= POLLWRNORM|POLLOUT;
    }
    if(pfd[i].events)
      num++;
    else
      break;
  }

  if(num) {
    nfds = Curl_poll(pfd, (unsigned int)num, timeout_ms);
    if(nfds < 0)
      return -1;
  }
  else
    nfds = 0;

  if(!nfds)
    /* Call ares_process() unconditionally here, even if we simply timed out
       above, as otherwise the ares name resolve will not timeout! */
    ares_process_fd(channel, ARES_SOCKET_BAD, ARES_SOCKET_BAD);
  else {
    /* move through the descriptors and ask for processing on them */
    for(i = 0; i < num; i++)
      ares_process_fd(channel,
                      (pfd[i].revents & (POLLRDNORM|POLLIN)) ?
                      pfd[i].fd : ARES_SOCKET_BAD,
                      (pfd[i].revents & (POLLWRNORM|POLLOUT)) ?
                      pfd[i].fd : ARES_SOCKET_BAD);
  }
  return nfds;
}

#endif

#endif /* CURLRES_ASYNCH */