1 files changed, 40 insertions, 5 deletions

diff --git a/clientloop.c b/clientloop.c
index d8def78bd..d445230e5 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -317,10 +317,14 @@ client_check_window_change(void)
  * one of the file descriptors).
  */
 
-static void
+static int
 client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
     int *maxfdp, int *nallocp, int rekeying)
 {
+        struct timeval tv, *tvp;
+        int n;
+        extern Options options;
+
         /* Add any selections by the channel mechanism. */
         channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, rekeying);
 
@@ -349,7 +353,7 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
                         /* clear mask since we did not call select() */
                         memset(*readsetp, 0, *nallocp);
                         memset(*writesetp, 0, *nallocp);
-                        return;
+                        return 0;
                 } else {
                         FD_SET(connection_in, *readsetp);
                 }
@@ -368,7 +372,21 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
          * SSH_MSG_IGNORE packet when the timeout expires.
          */
 
-        if (select((*maxfdp)+1, *readsetp, *writesetp, NULL, NULL) < 0) {
+        /*
+         * We don't do the 'random' bit, but we want periodic ignored
+         * message anyway, so as to notice when the other ends TCP
+         * has given up during an outage.
+         */
+
+        if (options.protocolkeepalives > 0) {
+                tvp = &tv;
+                tv.tv_sec = options.protocolkeepalives;
+                tv.tv_usec = 0;
+        } else
+                tvp = 0;
+
+        n = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
+        if (n < 0) {
                 char buf[100];
 
                 /*
@@ -380,12 +398,13 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
                 memset(*writesetp, 0, *nallocp);
 
                 if (errno == EINTR)
-                        return;
+                        return 0;
                 /* Note: we might still have data in the buffers. */
                 snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
                 buffer_append(&stderr_buffer, buf, strlen(buf));
                 quit_pending = 1;
         }
+        return n == 0;
 }
 
 static void
@@ -860,6 +879,7 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 {
         fd_set *readset = NULL, *writeset = NULL;
         double start_time, total_time;
+        int timed_out;
         int max_fd = 0, max_fd2 = 0, len, rekeying = 0, nalloc = 0;
         char buf[100];
 
@@ -973,7 +993,7 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
                  * available on one of the descriptors).
                  */
                 max_fd2 = max_fd;
-                client_wait_until_can_do_something(&readset, &writeset,
+                timed_out = client_wait_until_can_do_something(&readset, &writeset,
                     &max_fd2, &nalloc, rekeying);
 
                 if (quit_pending)
@@ -996,6 +1016,21 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
                 if (quit_pending)
                         break;
 
+                if(timed_out) {
+                        /*
+                         * Nothing is happening, so synthesize some
+                         * bogus activity
+                         */
+                        packet_start(compat20
+                                     ? SSH2_MSG_IGNORE
+                                     : SSH_MSG_IGNORE);
+                        packet_put_cstring("");
+                        packet_send();
+                        if (FD_ISSET(connection_out, writeset))
+                                packet_write_poll();
+                        continue;
+                }
+
                 if (!compat20) {
                         /* Buffer data from stdin */
                         client_process_input(readset);