From: djm <djm@openbsd.org>
Date: Fri, 9 Jun 2017 06:47:13 +0000 (+0000)
Subject: return failure rather than fatal() for more cases during mux
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c3f3d768a4eac19e672fe90df8a3ac0b253b5814;p=openbsd

return failure rather than fatal() for more cases during mux
negotiations. Causes the session to fall back to a non-mux connection
if they occur. bz#2707 ok dtucker@
---

diff --git a/usr.bin/ssh/mux.c b/usr.bin/ssh/mux.c
index 745526385f7..6bbd90ec039 100644
--- a/usr.bin/ssh/mux.c
+++ b/usr.bin/ssh/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.64 2017/01/21 11:32:04 guenther Exp $ */
+/* $OpenBSD: mux.c,v 1.65 2017/06/09 06:47:13 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -1551,31 +1551,38 @@ mux_client_hello_exchange(int fd)
 {
 	Buffer m;
 	u_int type, ver;
+	int ret = -1;
 
 	buffer_init(&m);
 	buffer_put_int(&m, MUX_MSG_HELLO);
 	buffer_put_int(&m, SSHMUX_VER);
 	/* no extensions */
 
-	if (mux_client_write_packet(fd, &m) != 0)
-		fatal("%s: write packet: %s", __func__, strerror(errno));
+	if (mux_client_write_packet(fd, &m) != 0) {
+		debug("%s: write packet: %s", __func__, strerror(errno));
+		goto out;
+	}
 
 	buffer_clear(&m);
 
 	/* Read their HELLO */
 	if (mux_client_read_packet(fd, &m) != 0) {
-		buffer_free(&m);
-		return -1;
+		debug("%s: read packet failed", __func__);
+		goto out;
 	}
 
 	type = buffer_get_int(&m);
-	if (type != MUX_MSG_HELLO)
-		fatal("%s: expected HELLO (%u) received %u",
+	if (type != MUX_MSG_HELLO) {
+		error("%s: expected HELLO (%u) received %u",
 		    __func__, MUX_MSG_HELLO, type);
+		goto out;
+	}
 	ver = buffer_get_int(&m);
-	if (ver != SSHMUX_VER)
-		fatal("Unsupported multiplexing protocol version %d "
+	if (ver != SSHMUX_VER) {
+		error("Unsupported multiplexing protocol version %d "
 		    "(expected %d)", ver, SSHMUX_VER);
+		goto out;
+	}
 	debug2("%s: master version %u", __func__, ver);
 	/* No extensions are presently defined */
 	while (buffer_len(&m) > 0) {
@@ -1586,8 +1593,11 @@ mux_client_hello_exchange(int fd)
 		free(name);
 		free(value);
 	}
+	/* success */
+	ret = 0;
+ out:
 	buffer_free(&m);
-	return 0;
+	return ret;
 }
 
 static u_int