- djm@cvs.openbsd.org 2008/06/12 03:40:52

     [clientloop.h mux.c channels.c clientloop.c channels.h]
     Enable ~ escapes for multiplex slave sessions; give each channel
     its own escape state and hook the escape filters up to muxed
     channels. bz #1331
     Mux slaves do not currently support the ~^Z and ~& escapes.
     NB. this change cranks the mux protocol version, so a new ssh
     mux client will not be able to connect to a running old ssh
     mux master.
     ok dtucker@

1 files changed, 62 insertions, 31 deletions

diff --git a/mux.c b/mux.c
index 8b9105b04..efc3840cb 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.1 2008/05/09 14:18:44 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.2 2008/06/12 03:40:52 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -19,6 +19,20 @@
 
 #include "includes.h"
 
+/*
+ * TODO:
+ *   1. partial reads in muxserver_accept_control (maybe make channels
+ *      from accepted connections)
+ *   2. Better signalling from master to slave, especially passing of
+ *      error messages
+ *   3. Better fall-back from mux slave error to new connection.
+ *   3. Add/delete forwardings via slave
+ *   4. ExitOnForwardingFailure (after #3 obviously)
+ *   5. Maybe extension mechanisms for multi-X11/multi-agent forwarding
+ *   6. Document the mux mini-protocol somewhere.
+ *   6. Support ~^Z in mux slaves.
+ */
+
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/stat.h>
@@ -71,6 +85,18 @@ extern char *host;
 int subsystem_flag;
 extern Buffer command;
 
+/* Context for session open confirmation callback */
+struct mux_session_confirm_ctx {
+        int want_tty;
+        int want_subsys;
+        int want_x_fwd;
+        int want_agent_fwd;
+        Buffer cmd;
+        char *term;
+        struct termios tio;
+        char **env;
+};
+
 /* fd to control socket */
 int muxserver_sock = -1;
 
@@ -131,7 +157,7 @@ muxserver_listen(void)
 
 /* Callback on open confirmation in mux master for a mux client session. */
 static void
-client_extra_session2_setup(int id, void *arg)
+mux_session_confirm(int id, void *arg)
 {
         struct mux_session_confirm_ctx *cctx = arg;
         const char *display;
@@ -190,7 +216,7 @@ muxserver_accept_control(void)
         struct sockaddr_storage addr;
         struct mux_session_confirm_ctx *cctx;
         char *cmd;
-        u_int i, j, len, env_len, mux_command, flags;
+        u_int i, j, len, env_len, mux_command, flags, escape_char;
         uid_t euid;
         gid_t egid;
         int start_close = 0;
@@ -317,6 +343,7 @@ muxserver_accept_control(void)
         cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
         cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
         cctx->term = buffer_get_string(&m, &len);
+        escape_char = buffer_get_int(&m);
 
         cmd = buffer_get_string(&m, &len);
         buffer_init(&cctx->cmd);
@@ -402,14 +429,17 @@ muxserver_accept_control(void)
             new_fd[0], new_fd[1], new_fd[2], window, packetmax,
             CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
 
-        /* XXX */
         c->ctl_fd = client_fd;
+        if (cctx->want_tty && escape_char != 0xffffffff) {
+                channel_register_filter(c->self,
+                    client_simple_escape_filter, NULL,
+                    client_new_escape_filter_ctx((int)escape_char));
+        }
 
         debug3("%s: channel_new: %d", __func__, c->self);
 
         channel_send_open(c->self);
-        channel_register_open_confirm(c->self,
-            client_extra_session2_setup, cctx);
+        channel_register_open_confirm(c->self, mux_session_confirm, cctx);
         return 0;
 }
 
@@ -561,33 +591,34 @@ muxclient(const char *path)
                 fprintf(stderr, "Exit request sent.\r\n");
                 exit(0);
         case SSHMUX_COMMAND_OPEN:
-                /* continue below */
+                buffer_put_cstring(&m, term ? term : "");
+                if (options.escape_char == SSH_ESCAPECHAR_NONE)
+                        buffer_put_int(&m, 0xffffffff);
+                else
+                        buffer_put_int(&m, options.escape_char);
+                buffer_append(&command, "\0", 1);
+                buffer_put_cstring(&m, buffer_ptr(&command));
+
+                if (options.num_send_env == 0 || environ == NULL) {
+                        buffer_put_int(&m, 0);
+                } else {
+                        /* Pass environment */
+                        num_env = 0;
+                        for (i = 0; environ[i] != NULL; i++) {
+                                if (env_permitted(environ[i]))
+                                        num_env++; /* Count */
+                        }
+                        buffer_put_int(&m, num_env);
+                for (i = 0; environ[i] != NULL && num_env >= 0; i++) {
+                                if (env_permitted(environ[i])) {
+                                        num_env--;
+                                        buffer_put_cstring(&m, environ[i]);
+                                }
+                        }
+                }
                 break;
         default:
-                fatal("silly muxclient_command %d", muxclient_command);
-        }
-
-        /* SSHMUX_COMMAND_OPEN */
-        buffer_put_cstring(&m, term ? term : "");
-        buffer_append(&command, "\0", 1);
-        buffer_put_cstring(&m, buffer_ptr(&command));
-
-        if (options.num_send_env == 0 || environ == NULL) {
-                buffer_put_int(&m, 0);
-        } else {
-                /* Pass environment */
-                num_env = 0;
-                for (i = 0; environ[i] != NULL; i++)
-                        if (env_permitted(environ[i]))
-                                num_env++; /* Count */
-
-                buffer_put_int(&m, num_env);
-
-                for (i = 0; environ[i] != NULL && num_env >= 0; i++)
-                        if (env_permitted(environ[i])) {
-                                num_env--;
-                                buffer_put_cstring(&m, environ[i]);
-                        }
+                fatal("unrecognised muxclient_command %d", muxclient_command);
         }
 
         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)