- 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, 12 insertions, 23 deletions

diff --git a/clientloop.c b/clientloop.c
index 5793a6e91..05f4720a1 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.216 2010/01/09 05:04:24 djm Exp $ */
+/* $OpenBSD: clientloop.c,v 1.217 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
@@ -121,7 +121,7 @@ extern int stdin_null_flag;
 extern int no_shell_flag;
 
 /* Control socket */
-extern int muxserver_sock;
+extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
 
 /*
  * Name of the host we are connecting to.  This is the name given on the
@@ -146,7 +146,7 @@ static volatile sig_atomic_t received_signal = 0;
 static int in_non_blocking_mode = 0;
 
 /* Common data for the client loop code. */
-static volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
+volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
 static int escape_char1;        /* Escape character. (proto1 only) */
 static int escape_pending1;     /* Last character was an escape (proto1 only) */
 static int last_was_cr;         /* Last character was a newline. */
@@ -564,9 +564,6 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
         if (packet_have_data_to_write())
                 FD_SET(connection_out, *writesetp);
 
-        if (muxserver_sock != -1)
-                FD_SET(muxserver_sock, *readsetp);
-
         /*
          * Wait for something to happen.  This will suspend the process until
          * some selected descriptor can be read, written, or has some other
@@ -695,7 +692,7 @@ client_status_confirm(int type, Channel *c, void *ctx)
 
         /* XXX supress on mux _client_ quietmode */
         tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
-            c->ctl_fd != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
+            c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
 
         if (type == SSH2_MSG_CHANNEL_SUCCESS) {
                 debug2("%s request accepted on channel %d",
@@ -839,6 +836,7 @@ process_cmdline(void)
         while (isspace(*++s))
                 ;
 
+        /* XXX update list of forwards in options */
         if (delete) {
                 cancel_port = 0;
                 cancel_host = hpdelim(&s);      /* may be NULL */
@@ -936,7 +934,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
                                     escape_char);
                                 buffer_append(berr, string, strlen(string));
 
-                                if (c && c->ctl_fd != -1) {
+                                if (c && c->ctl_chan != -1) {
                                         chan_read_failed(c);
                                         chan_write_failed(c);
                                         return 0;
@@ -946,7 +944,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 
                         case 'Z' - 64:
                                 /* XXX support this for mux clients */
-                                if (c && c->ctl_fd != -1) {
+                                if (c && c->ctl_chan != -1) {
  noescape:
                                         snprintf(string, sizeof string,
                                             "%c%c escape not available to "
@@ -991,7 +989,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
                                 continue;
 
                         case '&':
-                                if (c && c->ctl_fd != -1)
+                                if (c && c->ctl_chan != -1)
                                         goto noescape;
                                 /*
                                  * Detach the program (continue to serve
@@ -1042,7 +1040,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
                                 continue;
 
                         case '?':
-                                if (c && c->ctl_fd != -1) {
+                                if (c && c->ctl_chan != -1) {
                                         snprintf(string, sizeof string,
 "%c?\r\n\
 Supported escape sequences:\r\n\
@@ -1091,7 +1089,7 @@ Supported escape sequences:\r\n\
                                 continue;
 
                         case 'C':
-                                if (c && c->ctl_fd != -1)
+                                if (c && c->ctl_chan != -1)
                                         goto noescape;
                                 process_cmdline();
                                 continue;
@@ -1327,8 +1325,6 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
         connection_in = packet_get_connection_in();
         connection_out = packet_get_connection_out();
         max_fd = MAX(connection_in, connection_out);
-        if (muxserver_sock != -1)
-                max_fd = MAX(max_fd, muxserver_sock);
 
         if (!compat20) {
                 /* enable nonblocking unless tty */
@@ -1446,12 +1442,6 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
                 /* Buffer input from the connection.  */
                 client_process_net_input(readset);
 
-                /* Accept control connections.  */
-                if (muxserver_sock != -1 &&FD_ISSET(muxserver_sock, readset)) {
-                        if (muxserver_accept_control())
-                                quit_pending = 1;
-                }
-
                 if (quit_pending)
                         break;
 
@@ -1859,9 +1849,8 @@ client_input_channel_req(int type, u_int32_t seq, void *ctxt)
                 chan_rcvd_eow(c);
         } else if (strcmp(rtype, "exit-status") == 0) {
                 exitval = packet_get_int();
-                if (c->ctl_fd != -1) {
-                        /* Dispatch to mux client */
-                        atomicio(vwrite, c->ctl_fd, &exitval, sizeof(exitval));
+                if (c->ctl_chan != -1) {
+                        mux_exit_message(c, exitval);
                         success = 1;
                 } else if (id == session_ident) {
                         /* Record exit value of local session */