Steinar H. Gunderson fixed: Correctly clear sockets from the fd_set on in

several functions (write_tcp_data, read_tcp_data, read_udp_packets) so that
if it fails and the socket is closed the following code doesn't try to use
the file descriptor.

1 files changed, 21 insertions, 0 deletions

diff --git a/ares/ares_process.c b/ares/ares_process.c
index 66007f0fb..082fb4d84 100644
--- a/ares/ares_process.c
+++ b/ares/ares_process.c
@@ -167,6 +167,13 @@ static void write_tcp_data(ares_channel channel,
           continue;
       }
 
+      /* If there's an error and we close this socket, then open
+       * another with the same fd to talk to another server, then we
+       * don't want to think that it was the new socket that was
+       * ready. This is not disastrous, but is likely to result in
+       * extra system calls and confusion. */
+      FD_CLR(server->tcp_socket, write_fds);
+
       /* Count the number of send queue items. */
       n = 0;
       for (sendreq = server->qhead; sendreq; sendreq = sendreq->next)
@@ -280,6 +287,13 @@ static void read_tcp_data(ares_channel channel, fd_set *read_fds,
           continue;
       }
 
+      /* If there's an error and we close this socket, then open
+       * another with the same fd to talk to another server, then we
+       * don't want to think that it was the new socket that was
+       * ready. This is not disastrous, but is likely to result in
+       * extra system calls and confusion. */
+      FD_CLR(server->tcp_socket, read_fds);
+
       if (server->tcp_lenbuf_pos != 2)
         {
           /* We haven't yet read a length word, so read that (or
@@ -370,6 +384,13 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds,
           continue;
       }
 
+      /* If there's an error and we close this socket, then open
+       * another with the same fd to talk to another server, then we
+       * don't want to think that it was the new socket that was
+       * ready. This is not disastrous, but is likely to result in
+       * extra system calls and confusion. */
+      FD_CLR(server->udp_socket, read_fds);
+
       count = sread(server->udp_socket, buf, sizeof(buf));
       if (count == -1 && try_again(SOCKERRNO))
         continue;