zz40-xc-ovr.m4: fix variable assignment of subshell output bashism

[platform/upstream/c-ares.git] / ares_fds.c

diff --git a/ares_fds.c b/ares_fds.c
index 67bf313..f405fc0 100644 (file)
--- a/ares_fds.c
+++ b/ares_fds.c
@@ -1,4 +1,3 @@
-/* $Id$ */
 
 /* Copyright 1998 by the Massachusetts Institute of Technology.
  *
@@ -15,14 +14,10 @@
  * without express or implied warranty.
  */
 
-#include "setup.h"
-#include <sys/types.h>
-
-#ifdef HAVE_SYS_TIME_H
-#include <sys/time.h>
-#endif
+#include "ares_setup.h"
 
 #include "ares.h"
+#include "ares_nowarn.h"
 #include "ares_private.h"
 
 int ares_fds(ares_channel channel, fd_set *read_fds, fd_set *write_fds)
@@ -31,20 +26,26 @@ int ares_fds(ares_channel channel, fd_set *read_fds, fd_set *write_fds)
   ares_socket_t nfds;
   int i;
 
-  /* No queries, no file descriptors. */
-  if (!channel->queries)
-    return 0;
+  /* Are there any active queries? */
+  int active_queries = !ares__is_list_empty(&(channel->all_queries));
 
   nfds = 0;
   for (i = 0; i < channel->nservers; i++)
     {
       server = &channel->servers[i];
-      if (server->udp_socket != ARES_SOCKET_BAD)
+      /* We only need to register interest in UDP sockets if we have
+       * outstanding queries.
+       */
+      if (active_queries && server->udp_socket != ARES_SOCKET_BAD)
         {
           FD_SET(server->udp_socket, read_fds);
           if (server->udp_socket >= nfds)
             nfds = server->udp_socket + 1;
         }
+      /* 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)
        {
          FD_SET(server->tcp_socket, read_fds);