From 287527a176b470b77cc85d37a7898da3ac9a4304 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Wed, 8 Aug 2018 18:40:44 +0200
Subject: [PATCH] BUG/MEDIUM: connection/mux: take care of serverless proxies

Commit 7ce0c89 ("MEDIUM: mux: Use the mux protocol specified on
bind/server lines") assumed a bit too strongly that we could only have
servers on the connect side :-) It segfaults under this config :

    defaults
        contimeout      5s
        clitimeout      5s
        srvtimeout      5s
        mode http

    listen test1
        bind :8001
        dispatch 127.0.0.1:8002

    frontend test2
        mode http
        bind :8002
        redirect location /

No backport needed.
---
 include/proto/connection.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/proto/connection.h b/include/proto/connection.h
index 3b25fc5c6..8261d5760 100644
--- a/include/proto/connection.h
+++ b/include/proto/connection.h
@@ -1068,14 +1068,21 @@ static inline int conn_install_mux_fe(struct connection *conn, void *ctx)
 static inline int conn_install_mux_be(struct connection *conn, void *ctx)
 {
 	struct server *srv = objt_server(conn->target);
+	struct proxy  *prx = objt_proxy(conn->target);
 	const struct mux_ops *mux_ops;
 
-	if (srv->mux_proto)
+	if (srv)
+		prx = srv->proxy;
+
+	if (!prx) // target must be either proxy or server
+		return -1;
+
+	if (srv && srv->mux_proto)
 		mux_ops = srv->mux_proto->mux;
 	else {
 		int mode;
 
-		mode = (1 << (srv->proxy->mode == PR_MODE_HTTP));
+		mode = (1 << (prx->mode == PR_MODE_HTTP));
 		mux_ops = conn_get_best_mux(conn, ist(NULL), PROTO_SIDE_BE, mode);
 		if (!mux_ops)
 			return -1;