ares_getsock.c

/* Copyright (C) 2005 - 2010, Daniel Stenberg
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  M.I.T. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

#include "ares_setup.h"

#include "ares.h"
#include "ares_private.h"

int ares_getsock(ares_channel channel,
                 ares_socket_t *socks,
                 int numsocks) /* size of the 'socks' array */
{
  struct server_state *server;
  int i;
  int sockindex=0;
  int bitmap = 0;
  unsigned int setbits = 0xffffffff;

  /* Are there any active queries? */
  int active_queries = !ares__is_list_empty(&(channel->all_queries));

  for (i = 0;
       (i < channel->nservers) && (sockindex < ARES_GETSOCK_MAXNUM);
       i++)
    {
      server = &channel->servers[i];
      /* We only need to register interest in UDP sockets if we have
       * outstanding queries.
       */
      if (active_queries && server->udp_socket != ARES_SOCKET_BAD)
        {
          if(sockindex >= numsocks)
            break;
          socks[sockindex] = server->udp_socket;
          bitmap |= ARES_GETSOCK_READABLE(setbits, sockindex);
          sockindex++;
        }
      /* We always register for TCP events, because we want to know
       * when the other side closes the connection, so we don't waste
       * time trying to use a broken connection.
       */
      if (server->tcp_socket != ARES_SOCKET_BAD)
       {
         if(sockindex >= numsocks)
           break;
         socks[sockindex] = server->tcp_socket;
         bitmap |= ARES_GETSOCK_READABLE(setbits, sockindex);

         if (server->qhead && active_queries)
           /* then the tcp socket is also writable! */
           bitmap |= ARES_GETSOCK_WRITABLE(setbits, sockindex);

         sockindex++;
       }
    }
  return bitmap;
}