- 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@

6 files changed, 202 insertions, 89 deletions

diff --git a/ChangeLog b/ChangeLog
index 27a2a7abc..ca0d8ea57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -68,6 +68,16 @@
      [key.c]
      use an odd number of rows and columns and a separate start marker, looks
      better; ok grunk@
+   - 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@
 
 20080611
  - (djm) [channels.c configure.ac]
@@ -4230,4 +4240,4 @@
    OpenServer 6 and add osr5bigcrypt support so when someone migrates
    passwords between UnixWare and OpenServer they will still work. OK dtucker@
 
-$Id: ChangeLog,v 1.4976 2008/06/12 18:48:11 dtucker Exp $
+$Id: ChangeLog,v 1.4977 2008/06/12 18:49:33 dtucker Exp $
diff --git a/channels.c b/channels.c
index 233c2247b..c539990f6 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.278 2008/06/10 04:50:25 dtucker Exp $ */
+/* $OpenBSD: channels.c,v 1.279 2008/06/12 03:40:52 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -731,7 +731,7 @@ channel_cancel_cleanup(int id)
 
 void
 channel_register_filter(int id, channel_infilter_fn *ifn,
-    channel_outfilter_fn *ofn)
+    channel_outfilter_fn *ofn, void *ctx)
 {
         Channel *c = channel_lookup(id);
 
@@ -741,6 +741,7 @@ channel_register_filter(int id, channel_infilter_fn *ifn,
         }
         c->input_filter = ifn;
         c->output_filter = ofn;
+        c->filter_ctx = ctx;
 }
 
 void
diff --git a/channels.h b/channels.h
index dc1f483ed..450321d43 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.93 2008/06/10 04:50:25 dtucker Exp $ */
+/* $OpenBSD: channels.h,v 1.94 2008/06/12 03:40:52 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -131,6 +131,7 @@ struct Channel {
         /* filter */
         channel_infilter_fn     *input_filter;
         channel_outfilter_fn    *output_filter;
+        void                    *filter_ctx;
 
         /* keep boundaries */
         int                     datagram;
@@ -195,7 +196,7 @@ void	 channel_request_start(int, char *, int);
 void     channel_register_cleanup(int, channel_callback_fn *, int);
 void     channel_register_open_confirm(int, channel_callback_fn *, void *);
 void     channel_register_filter(int, channel_infilter_fn *,
-    channel_outfilter_fn *);
+    channel_outfilter_fn *, void *);
 void     channel_register_status_confirm(int, channel_confirm_cb *,
     channel_confirm_abandon_cb *, void *);
 void     channel_cancel_cleanup(int);
diff --git a/clientloop.c b/clientloop.c
index 3bc8bb8d0..b45e7298a 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.194 2008/05/19 20:53:52 djm Exp $ */
+/* $OpenBSD: clientloop.c,v 1.195 2008/06/12 03:40:52 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -144,8 +144,8 @@ 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. */
-static int escape_char;         /* Escape character. */
-static int escape_pending;      /* Last character was the escape character */
+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. */
 static int exit_status;         /* Used to store the exit status of the command. */
 static int stdin_eof;           /* EOF has been encountered on standard error. */
@@ -162,6 +162,13 @@ static int session_closed = 0;	/* In SSH2: login session closed. */
 static void client_init_dispatch(void);
 int     session_ident = -1;
 
+/* Track escape per proto2 channel */
+struct escape_filter_ctx {
+        int escape_pending;
+        int escape_char;
+};
+
+/* Context for channel confirmation replies */
 struct channel_reply_ctx {
         const char *request_type;
         int id, do_close;
@@ -385,8 +392,8 @@ client_check_initial_eof_on_stdin(void)
                          * and also process it as an escape character if
                          * appropriate.
                          */
-                        if ((u_char) buf[0] == escape_char)
-                                escape_pending = 1;
+                        if ((u_char) buf[0] == escape_char1)
+                                escape_pending1 = 1;
                         else
                                 buffer_append(&stdin_buffer, buf, 1);
                 }
@@ -813,9 +820,12 @@ out:
                 xfree(fwd.connect_host);
 }
 
-/* process the characters one by one */
+/* 
+ * Process the characters one by one, call with c==NULL for proto1 case.
+ */
 static int
-process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
+process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
+    char *buf, int len)
 {
         char string[1024];
         pid_t pid;
@@ -823,7 +833,20 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
         u_int i;
         u_char ch;
         char *s;
+        int *escape_pendingp, escape_char;
+        struct escape_filter_ctx *efc;
 
+        if (c == NULL) {
+                escape_pendingp = &escape_pending1;
+                escape_char = escape_char1;
+        } else {
+                if (c->filter_ctx == NULL)
+                        return 0;
+                efc = (struct escape_filter_ctx *)c->filter_ctx;
+                escape_pendingp = &efc->escape_pending;
+                escape_char = efc->escape_char;
+        }
+        
         if (len <= 0)
                 return (0);
 
@@ -831,25 +854,43 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
                 /* Get one character at a time. */
                 ch = buf[i];
 
-                if (escape_pending) {
+                if (*escape_pendingp) {
                         /* We have previously seen an escape character. */
                         /* Clear the flag now. */
-                        escape_pending = 0;
+                        *escape_pendingp = 0;
 
                         /* Process the escaped character. */
                         switch (ch) {
                         case '.':
                                 /* Terminate the connection. */
-                                snprintf(string, sizeof string, "%c.\r\n", escape_char);
+                                snprintf(string, sizeof string, "%c.\r\n",
+                                    escape_char);
                                 buffer_append(berr, string, strlen(string));
 
-                                quit_pending = 1;
+                                if (c && c->ctl_fd != -1) {
+                                        chan_read_failed(c);
+                                        chan_write_failed(c);
+                                        return 0;
+                                } else
+                                        quit_pending = 1;
                                 return -1;
 
                         case 'Z' - 64:
+                                /* XXX support this for mux clients */
+                                if (c && c->ctl_fd != -1) {
+ noescape:
+                                        snprintf(string, sizeof string,
+                                            "%c%c escape not available to "
+                                            "multiplexed sessions\r\n",
+                                            escape_char, ch);
+                                        buffer_append(berr, string,
+                                            strlen(string));
+                                        continue;
+                                }
                                 /* Suspend the program. */
                                 /* Print a message to that effect to the user. */
-                                snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
+                                snprintf(string, sizeof string,
+                                    "%c^Z [suspend ssh]\r\n", escape_char);
                                 buffer_append(berr, string, strlen(string));
 
                                 /* Restore terminal modes and suspend. */
@@ -881,6 +922,8 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
                                 continue;
 
                         case '&':
+                                if (c && c->ctl_fd != -1)
+                                        goto noescape;
                                 /*
                                  * Detach the program (continue to serve connections,
                                  * but put in background and no more new connections).
@@ -929,27 +972,50 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
                                 continue;
 
                         case '?':
-                                snprintf(string, sizeof string,
+                                if (c && c->ctl_fd != -1) {
+                                        snprintf(string, sizeof string,
 "%c?\r\n\
 Supported escape sequences:\r\n\
-%c.  - terminate connection\r\n\
-%cB  - send a BREAK to the remote system\r\n\
-%cC  - open a command line\r\n\
-%cR  - Request rekey (SSH protocol 2 only)\r\n\
-%c^Z - suspend ssh\r\n\
-%c#  - list forwarded connections\r\n\
-%c&  - background ssh (when waiting for connections to terminate)\r\n\
-%c?  - this message\r\n\
-%c%c  - send the escape character by typing it twice\r\n\
+  %c.  - terminate session\r\n\
+  %cB  - send a BREAK to the remote system\r\n\
+  %cC  - open a command line\r\n\
+  %cR  - Request rekey (SSH protocol 2 only)\r\n\
+  %c#  - list forwarded connections\r\n\
+  %c?  - this message\r\n\
+  %c%c  - send the escape character by typing it twice\r\n\
 (Note that escapes are only recognized immediately after newline.)\r\n",
-                                    escape_char, escape_char, escape_char, escape_char,
-                                    escape_char, escape_char, escape_char, escape_char,
-                                    escape_char, escape_char, escape_char);
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char);
+                                } else {
+                                        snprintf(string, sizeof string,
+"%c?\r\n\
+Supported escape sequences:\r\n\
+  %c.  - terminate connection (and any multiplexed sessions)\r\n\
+  %cB  - send a BREAK to the remote system\r\n\
+  %cC  - open a command line\r\n\
+  %cR  - Request rekey (SSH protocol 2 only)\r\n\
+  %c^Z - suspend ssh\r\n\
+  %c#  - list forwarded connections\r\n\
+  %c&  - background ssh (when waiting for connections to terminate)\r\n\
+  %c?  - this message\r\n\
+  %c%c  - send the escape character by typing it twice\r\n\
+(Note that escapes are only recognized immediately after newline.)\r\n",
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char, escape_char,
+                                            escape_char);
+                                }
                                 buffer_append(berr, string, strlen(string));
                                 continue;
 
                         case '#':
-                                snprintf(string, sizeof string, "%c#\r\n", escape_char);
+                                snprintf(string, sizeof string, "%c#\r\n",
+                                    escape_char);
                                 buffer_append(berr, string, strlen(string));
                                 s = channel_open_message();
                                 buffer_append(berr, s, strlen(s));
@@ -975,7 +1041,7 @@ Supported escape sequences:\r\n\
                          */
                         if (last_was_cr && ch == escape_char) {
                                 /* It is. Set the flag and continue to next character. */
-                                escape_pending = 1;
+                                *escape_pendingp = 1;
                                 continue;
                         }
                 }
@@ -1026,7 +1092,7 @@ client_process_input(fd_set *readset)
                                 packet_start(SSH_CMSG_EOF);
                                 packet_send();
                         }
-                } else if (escape_char == SSH_ESCAPECHAR_NONE) {
+                } else if (escape_char1 == SSH_ESCAPECHAR_NONE) {
                         /*
                          * Normal successful read, and no escape character.
                          * Just append the data to buffer.
@@ -1037,8 +1103,8 @@ client_process_input(fd_set *readset)
                          * Normal, successful read.  But we have an escape character
                          * and have to process the characters one by one.
                          */
-                        if (process_escapes(&stdin_buffer, &stdout_buffer,
-                            &stderr_buffer, buf, len) == -1)
+                        if (process_escapes(NULL, &stdin_buffer,
+                            &stdout_buffer, &stderr_buffer, buf, len) == -1)
                                 return;
                 }
         }
@@ -1113,13 +1179,26 @@ client_process_buffered_input_packets(void)
 
 /* scan buf[] for '~' before sending data to the peer */
 
-static int
-simple_escape_filter(Channel *c, char *buf, int len)
+/* Helper: allocate a new escape_filter_ctx and fill in its escape char */
+void *
+client_new_escape_filter_ctx(int escape_char)
+{
+        struct escape_filter_ctx *ret;
+
+        ret = xmalloc(sizeof(*ret));
+        ret->escape_pending = 0;
+        ret->escape_char = escape_char;
+        return (void *)ret;
+}
+
+int
+client_simple_escape_filter(Channel *c, char *buf, int len)
 {
         if (c->extended_usage != CHAN_EXTENDED_WRITE)
                 return 0;
 
-        return process_escapes(&c->input, &c->output, &c->extended, buf, len);
+        return process_escapes(c, &c->input, &c->output, &c->extended,
+            buf, len);
 }
 
 static void
@@ -1151,7 +1230,7 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
         start_time = get_current_time();
 
         /* Initialize variables. */
-        escape_pending = 0;
+        escape_pending1 = 0;
         last_was_cr = 1;
         exit_status = -1;
         stdin_eof = 0;
@@ -1178,7 +1257,7 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
         stdout_bytes = 0;
         stderr_bytes = 0;
         quit_pending = 0;
-        escape_char = escape_char_arg;
+        escape_char1 = escape_char_arg;
 
         /* Initialize buffers. */
         buffer_init(&stdin_buffer);
@@ -1206,9 +1285,10 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 
         if (compat20) {
                 session_ident = ssh2_chan_id;
-                if (escape_char != SSH_ESCAPECHAR_NONE)
+                if (escape_char_arg != SSH_ESCAPECHAR_NONE)
                         channel_register_filter(session_ident,
-                            simple_escape_filter, NULL);
+                            client_simple_escape_filter, NULL,
+                            client_new_escape_filter_ctx(escape_char_arg));
                 if (session_ident != -1)
                         channel_register_cleanup(session_ident,
                             client_channel_closed, 0);
diff --git a/clientloop.h b/clientloop.h
index 6f8e70123..cecbfb1a8 100644
--- a/clientloop.h
+++ b/clientloop.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.h,v 1.19 2008/05/09 14:18:44 djm Exp $ */
+/* $OpenBSD: clientloop.h,v 1.20 2008/06/12 03:40:52 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -46,8 +46,12 @@ void	 client_session2_setup(int, int, int, const char *, struct termios *,
             int, Buffer *, char **);
 int      client_request_tun_fwd(int, int, int);
 
+/* Escape filter for protocol 2 sessions */
+void    *client_new_escape_filter_ctx(int);
+int      client_simple_escape_filter(Channel *, char *, int);
+
 /* Multiplexing protocol version */
-#define SSHMUX_VER                      1
+#define SSHMUX_VER                      2
 
 /* Multiplexing control protocol flags */
 #define SSHMUX_COMMAND_OPEN             1       /* Open new connection */
@@ -59,20 +63,6 @@ int	 client_request_tun_fwd(int, int, int);
 #define SSHMUX_FLAG_X11_FWD             (1<<2)  /* Request X11 forwarding */
 #define SSHMUX_FLAG_AGENT_FWD           (1<<3)  /* Request agent forwarding */
 
-/* Multiplexing routines */
-
-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;
-};
-
-/* mux.c */
 void    muxserver_listen(void);
 int     muxserver_accept_control(void);
 void    muxclient(const char *);
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)