1 files changed, 60 insertions, 4 deletions

diff --git a/serverloop.c b/serverloop.c
index d6b360d9a..5a5b1e37f 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -35,7 +35,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: serverloop.c,v 1.60 2001/04/05 23:39:20 markus Exp $");
+RCSID("$OpenBSD: serverloop.c,v 1.61 2001/04/13 22:46:54 beck Exp $");
 
 #include "xmalloc.h"
 #include "packet.h"
@@ -91,6 +91,8 @@ static volatile int child_wait_status;	/* Status from wait(). */
 
 void    server_init_dispatch(void);
 
+int client_alive_timeouts = 0;
+
 void
 sigchld_handler(int sig)
 {
@@ -190,6 +192,21 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 {
         struct timeval tv, *tvp;
         int ret;
+        int client_alive_scheduled = 0;
+
+        /*
+         * if using client_alive, set the max timeout accordingly, 
+         * and indicate that this particular timeout was for client
+         * alive by setting the client_alive_scheduled flag.
+         *
+         * this could be randomized somewhat to make traffic
+         * analysis more difficult, but we're not doing it yet.  
+         */
+        if (max_time_milliseconds == 0 && options.client_alive_interval) {
+                client_alive_scheduled = 1;
+                max_time_milliseconds = options.client_alive_interval * 1000;
+        } else 
+                client_alive_scheduled = 0;
 
         /* When select fails we restart from here. */
 retry_select:
@@ -239,7 +256,7 @@ retry_select:
          * from it, then read as much as is available and exit.
          */
         if (child_terminated && packet_not_very_much_data_to_write())
-                if (max_time_milliseconds == 0)
+                if (max_time_milliseconds == 0 || client_alive_scheduled)
                         max_time_milliseconds = 100;
 
         if (max_time_milliseconds == 0)
@@ -255,12 +272,36 @@ retry_select:
         /* Wait for something to happen, or the timeout to expire. */
         ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
 
-        if (ret < 0) {
+        if (ret == -1) {
                 if (errno != EINTR)
                         error("select: %.100s", strerror(errno));
                 else
                         goto retry_select;
         }
+        if (ret == 0 && client_alive_scheduled) {
+                /* timeout, check to see how many we have had */
+                client_alive_timeouts++;
+
+                if (client_alive_timeouts > options.client_alive_count_max ) {
+                        packet_disconnect(
+                                "Timeout, your session not responding.");
+                } else {
+                        /*
+                         * send a bogus channel request with "wantreply" 
+                         * we should get back a failure
+                         */
+                        int id;
+                        
+                        id = channel_find_open();
+                        if (id != -1) {
+                                channel_request_start(id,
+                                  "keepalive@openssh.com", 1);
+                                packet_send();
+                        } else 
+                                packet_disconnect(
+                                        "No open channels after timeout!");
+                }
+        } 
 }
 
 /*
@@ -701,6 +742,19 @@ server_loop2(void)
 }
 
 void
+server_input_channel_failure(int type, int plen, void *ctxt)
+{
+        debug("Got CHANNEL_FAILURE for keepalive");
+        /* 
+         * reset timeout, since we got a sane answer from the client.
+         * even if this was generated by something other than
+         * the bogus CHANNEL_REQUEST we send for keepalives.
+         */
+        client_alive_timeouts = 0; 
+}
+
+
+void
 server_input_stdin_data(int type, int plen, void *ctxt)
 {
         char *data;
@@ -912,7 +966,8 @@ server_init_dispatch_20(void)
         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
         dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
-
+        /* client_alive */
+        dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure);
         /* rekeying */
         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
 }
@@ -949,3 +1004,4 @@ server_init_dispatch(void)
         else
                 server_init_dispatch_15();
 }
+