From ca19bfe2546f280f10795bae5e0ec296623de880 Mon Sep 17 00:00:00 2001
From: Darren Tucker <dtucker@zip.com.au>
Date: Fri, 13 Jun 2008 10:24:03 +1000
Subject: [PATCH]    - djm@cvs.openbsd.org 2008/06/13 00:16:49      [mux.c]    
  fall back to creating a new TCP connection on most multiplexing errors     
 (socket connect fail, invalid version, refused permittion, corrupted     
 messages, etc.); bz #1329 ok dtucker@

---
 ChangeLog |  7 +++++-
 mux.c     | 72 +++++++++++++++++++++++++++++++++++++++++--------------
 2 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 75f6246ca..052b15bd9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -143,6 +143,11 @@
      [sftp.h log.h]
      replace __dead with __attribute__((noreturn)), makes things
      a little easier to port.  Also, add it to sigdie().  ok djm@
+   - djm@cvs.openbsd.org 2008/06/13 00:16:49
+     [mux.c]
+     fall back to creating a new TCP connection on most multiplexing errors
+     (socket connect fail, invalid version, refused permittion, corrupted
+     messages, etc.); bz #1329 ok dtucker@
   - (dtucker) [clientloop.c serverloop.c]  channel_register_filter now
     takes 2 more args.  with djm@
 
@@ -4307,4 +4312,4 @@
    OpenServer 6 and add osr5bigcrypt support so when someone migrates
    passwords between UnixWare and OpenServer they will still work. OK dtucker@
 
-$Id: ChangeLog,v 1.4994 2008/06/13 00:22:54 dtucker Exp $
+$Id: ChangeLog,v 1.4995 2008/06/13 00:24:03 dtucker Exp $
diff --git a/mux.c b/mux.c
index 8f7bfb793..aaa3a4ee2 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.4 2008/06/12 15:19:17 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.5 2008/06/13 00:16:49 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -144,10 +144,16 @@ muxserver_listen(void)
 	old_umask = umask(0177);
 	if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
 		muxserver_sock = -1;
-		if (errno == EINVAL || errno == EADDRINUSE)
-			fatal("ControlSocket %s already exists",
-			    options.control_path);
-		else
+		if (errno == EINVAL || errno == EADDRINUSE) {
+			error("ControlSocket %s already exists, "
+			    "disabling multiplexing", options.control_path);
+			close(muxserver_sock);
+			muxserver_sock = -1;
+			xfree(options.control_path);
+			options.control_path = NULL;
+			options.control_master = SSHCTL_MASTER_NO;
+			return;
+		} else
 			fatal("%s bind(): %s", __func__, strerror(errno));
 	}
 	umask(old_umask);
@@ -500,7 +506,7 @@ muxclient(const char *path)
 	Buffer m;
 	char *term;
 	extern char **environ;
-	u_int  flags;
+	u_int allowed, flags;
 
 	if (muxclient_command == 0)
 		muxclient_command = SSHMUX_COMMAND_OPEN;
@@ -571,17 +577,38 @@ muxclient(const char *path)
 	/* Send our command to server */
 	buffer_put_int(&m, muxclient_command);
 	buffer_put_int(&m, flags);
-	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
-		fatal("%s: msg_send", __func__);
+	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) {
+		error("%s: msg_send", __func__);
+ muxerr:
+		close(sock);
+		buffer_free(&m);
+		if (muxclient_command != SSHMUX_COMMAND_OPEN)
+			cleanup_exit(255);
+		logit("Falling back to non-multiplexed connection");
+		xfree(options.control_path);
+		options.control_path = NULL;
+		options.control_master = SSHCTL_MASTER_NO;
+		return;
+	}
 	buffer_clear(&m);
 
 	/* Get authorisation status and PID of controlee */
-	if (ssh_msg_recv(sock, &m) == -1)
-		fatal("%s: msg_recv", __func__);
-	if (buffer_get_char(&m) != SSHMUX_VER)
-		fatal("%s: wrong version", __func__);
-	if (buffer_get_int(&m) != 1)
-		fatal("Connection to master denied");
+	if (ssh_msg_recv(sock, &m) == -1) {
+		error("%s: msg_recv", __func__);
+		goto muxerr;
+	}
+	if (buffer_get_char(&m) != SSHMUX_VER) {
+		error("%s: wrong version", __func__);
+		goto muxerr;
+	}
+	if (buffer_get_int_ret(&allowed, &m) != 0) {
+		error("%s: bad server reply", __func__);
+		goto muxerr;
+	}
+	if (allowed != 1) {
+		error("Connection to master denied");
+		goto muxerr;
+	}
 	muxserver_pid = buffer_get_int(&m);
 
 	buffer_clear(&m);
@@ -625,13 +652,22 @@ muxclient(const char *path)
 		fatal("unrecognised muxclient_command %d", muxclient_command);
 	}
 
-	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
-		fatal("%s: msg_send", __func__);
+	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) {
+		error("%s: msg_send", __func__);
+		goto muxerr;
+	}
 
 	if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
 	    mm_send_fd(sock, STDOUT_FILENO) == -1 ||
-	    mm_send_fd(sock, STDERR_FILENO) == -1)
-		fatal("%s: send fds failed", __func__);
+	    mm_send_fd(sock, STDERR_FILENO) == -1) {
+		error("%s: send fds failed", __func__);
+		goto muxerr;
+	}
+
+	/*
+	 * Mux errors are non-recoverable from this point as the master
+	 * has ownership of the session now.
+	 */
 
 	/* Wait for reply, so master has a chance to gather ttymodes */
 	buffer_clear(&m);