Commit 2a614871 authored by Yang Tse's avatar Yang Tse
Browse files

Functionality only possible if recvfrom() is available.

parent 5ca692fc

ares/ares_process.c

+9 −6
Original line number Diff line number Diff line
@@ -429,8 +429,10 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, 
  int i;

  ssize_t count;

  unsigned char buf[PACKETSZ + 1];

#ifdef HAVE_RECVFROM

  struct sockaddr_in from;

  socklen_t fromlen;

#endif



  if(!read_fds && (read_fd == ARES_SOCKET_BAD))

    /* no possible action */
@@ -464,23 +466,24 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, 
      /* To reduce event loop overhead, read and process as many

       * packets as we can. */

      do {

        /* Must memset 'from' to 0 as recvfrom() on some systems may

         * not use 'from' at all if it doesn't support receiving the

         * source address of the response */

        memset(&from, 0, sizeof(from));

#ifdef HAVE_RECVFROM

        fromlen = sizeof(from);

        count = (ssize_t)recvfrom(server->udp_socket, (void *)buf, sizeof(buf),

                                  0, (struct sockaddr *)&from, &fromlen);

#else

        count = sread(server->udp_socket, buf, sizeof(buf));

#endif

        if (count == -1 && try_again(SOCKERRNO))

          continue;

        else if (count <= 0)

          handle_error(channel, i, now);

        else if (fromlen && from.sin_addr.s_addr != 0 &&

                 from.sin_addr.s_addr != server->addr.s_addr)

#ifdef HAVE_RECVFROM

        else if (from.sin_addr.s_addr != server->addr.s_addr)

          /* Address response came from did not match the address

           * we sent the request to.  Someone may be attempting

           * to perform a cache poisoning attack */

          break;

#endif

        else

          process_answer(channel, buf, (int)count, i, 0, now);

       } while (count > 0);