- djm@cvs.openbsd.org 2010/01/26 01:28:35

     [channels.c channels.h clientloop.c clientloop.h mux.c nchan.c ssh.c]
     rewrite ssh(1) multiplexing code to a more sensible protocol.

     The new multiplexing code uses channels for the listener and
     accepted control sockets to make the mux master non-blocking, so
     no stalls when processing messages from a slave.

     avoid use of fatal() in mux master protocol parsing so an errant slave
     process cannot take down a running master.

     implement requesting of port-forwards over multiplexed sessions. Any
     port forwards requested by the slave are added to those the master has
     established.

     add support for stdio forwarding ("ssh -W host:port ...") in mux slaves.

     document master/slave mux protocol so that other tools can use it to
     control a running ssh(1). Note: there are no guarantees that this
     protocol won't be incompatibly changed (though it is versioned).

     feedback Salvador Fandino, dtucker@
     channel changes ok markus@

1 files changed, 19 insertions, 3 deletions

diff --git a/ssh.c b/ssh.c
index b86a764f6..97afdcfee 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.331 2010/01/11 01:39:46 dtucker Exp $ */
+/* $OpenBSD: ssh.c,v 1.332 2010/01/26 01:28:35 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -319,6 +319,11 @@ main(int ac, char **av)
                         options.gateway_ports = 1;
                         break;
                 case 'O':
+                        if (stdio_forward_host != NULL)
+                                fatal("Cannot specify multiplexing "
+                                    "command with -W");
+                        else if (muxclient_command != 0)
+                                fatal("Multiplexing command already specified");
                         if (strcmp(optarg, "check") == 0)
                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
                         else if (strcmp(optarg, "exit") == 0)
@@ -395,6 +400,10 @@ main(int ac, char **av)
                         }
                         break;
                 case 'W':
+                        if (stdio_forward_host != NULL)
+                                fatal("stdio forward already specified");
+                        if (muxclient_command != 0)
+                                fatal("Cannot specify stdio forward with -O");
                         if (parse_forward(&fwd, optarg, 1, 0)) {
                                 stdio_forward_host = fwd.listen_host;
                                 stdio_forward_port = fwd.listen_port;
@@ -902,11 +911,18 @@ static int
 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
 {
         Channel *c;
+        int in, out;
 
         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
             port_to_connect);
-        if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect))
-            == NULL)
+
+        in = dup(STDIN_FILENO);
+        out = dup(STDOUT_FILENO);
+        if (in < 0 || out < 0)
+                fatal("channel_connect_stdio_fwd: dup() in/out failed");
+
+        if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
+            in, out)) == NULL)
                 return 0;
         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
         return 1;