1 files changed, 22 insertions, 16 deletions

diff --git a/clientloop.c b/clientloop.c
index 42ace7789..2cebea29f 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.344 2020/04/24 02:19:40 dtucker Exp $ */
+/* $OpenBSD: clientloop.c,v 1.346 2020/09/16 03:07:31 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -166,6 +166,7 @@ static int connection_out;	/* Connection to server (output). */
 static int need_rekeying;       /* Set to non-zero if rekeying is requested. */
 static int session_closed;      /* In SSH2: login session closed. */
 static u_int x11_refuse_time;   /* If >0, refuse x11 opens after this time. */
+static time_t server_alive_time;        /* Time to do server_alive_check */
 
 static void client_init_dispatch(struct ssh *ssh);
 int     session_ident = -1;
@@ -471,6 +472,13 @@ client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 static void
+schedule_server_alive_check(void)
+{
+        if (options.server_alive_interval > 0)
+                server_alive_time = monotime() + options.server_alive_interval;
+}
+
+static void
 server_alive_check(struct ssh *ssh)
 {
         int r;
@@ -486,6 +494,7 @@ server_alive_check(struct ssh *ssh)
                 fatal("%s: send packet: %s", __func__, ssh_err(r));
         /* Insert an empty placeholder to maintain ordering */
         client_register_global_confirm(NULL, NULL);
+        schedule_server_alive_check();
 }
 
 /*
@@ -499,7 +508,7 @@ client_wait_until_can_do_something(struct ssh *ssh,
 {
         struct timeval tv, *tvp;
         int timeout_secs;
-        time_t minwait_secs = 0, server_alive_time = 0, now = monotime();
+        time_t minwait_secs = 0, now = monotime();
         int r, ret;
 
         /* Add any selections by the channel mechanism. */
@@ -528,10 +537,8 @@ client_wait_until_can_do_something(struct ssh *ssh,
          */
 
         timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */
-        if (options.server_alive_interval > 0) {
-                timeout_secs = options.server_alive_interval;
-                server_alive_time = now + options.server_alive_interval;
-        }
+        if (options.server_alive_interval > 0)
+                timeout_secs = MAXIMUM(server_alive_time - now, 0);
         if (options.rekey_interval > 0 && !rekeying)
                 timeout_secs = MINIMUM(timeout_secs,
                     ssh_packet_get_rekey_timeout(ssh));
@@ -561,7 +568,6 @@ client_wait_until_can_do_something(struct ssh *ssh,
                  */
                 memset(*readsetp, 0, *nallocp);
                 memset(*writesetp, 0, *nallocp);
-
                 if (errno == EINTR)
                         return;
                 /* Note: we might still have data in the buffers. */
@@ -569,15 +575,14 @@ client_wait_until_can_do_something(struct ssh *ssh,
                     "select: %s\r\n", strerror(errno))) != 0)
                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
                 quit_pending = 1;
-        } else if (ret == 0) {
+        } else if (options.server_alive_interval > 0 && !FD_ISSET(connection_in,
+             *readsetp) && monotime() >= server_alive_time)
                 /*
-                 * Timeout.  Could have been either keepalive or rekeying.
-                 * Keepalive we check here, rekeying is checked in clientloop.
+                 * ServerAlive check is needed. We can't rely on the select
+                 * timing out since traffic on the client side such as port
+                 * forwards can keep waking it up.
                  */
-                if (server_alive_time != 0 && server_alive_time <= monotime())
-                        server_alive_check(ssh);
-        }
-
+                server_alive_check(ssh);
 }
 
 static void
@@ -617,6 +622,7 @@ client_process_net_input(struct ssh *ssh, fd_set *readset)
          * the packet subsystem.
          */
         if (FD_ISSET(connection_in, readset)) {
+                schedule_server_alive_check();
                 /* Read as much as possible. */
                 len = read(connection_in, buf, sizeof(buf));
                 if (len == 0) {
@@ -1236,7 +1242,6 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
         int r, max_fd = 0, max_fd2 = 0, len;
         u_int64_t ibytes, obytes;
         u_int nalloc = 0;
-        char buf[100];
 
         debug("Entering interactive session.");
 
@@ -1318,6 +1323,8 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
                     client_channel_closed, 0);
         }
 
+        schedule_server_alive_check();
+
         /* Main loop of the client for the interactive session mode. */
         while (!quit_pending) {
 
@@ -1472,7 +1479,6 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
         }
 
         /* Clear and free any buffers. */
-        explicit_bzero(buf, sizeof(buf));
         sshbuf_free(stderr_buffer);
 
         /* Report bytes transferred, and transfer rates. */