Fix changing proto via force_send_socket().

If the RURI does not request any protocol, use the proto of the forced socket (if any).
Related to #420

(cherry picked from commit ac8c2e6)

modules/tm/t_funcs.c

@@ -208,7 +208,9 @@ int t_relay_to( struct sip_msg  *p_msg , struct proxy_l *proxy, int flags)
 		LM_DBG("forwarding ACK\n");
 		/* send it out */
 		if (proxy==0) {
-			proxy=uri2proxy(GET_NEXT_HOP(p_msg), PROTO_NONE);
+			proxy=uri2proxy(GET_NEXT_HOP(p_msg),
+				p_msg->force_send_socket ?
+				p_msg->force_send_socket->proto : PROTO_NONE );
 			if (proxy==0) {
 					ret=E_BAD_ADDRESS;
 					goto done;

modules/tm/t_fwd.c

@@ -374,7 +374,9 @@ static int add_uac( struct cell *t, struct sip_msg *request, str *uri,
 		do_free_proxy = 0;
 	}else {
 		proxy=uri2proxy( request->dst_uri.len ?
-			&request->dst_uri:&request->new_uri, PROTO_NONE );
+			&request->dst_uri:&request->new_uri,
+			request->force_send_socket ?
+				request->force_send_socket->proto : PROTO_NONE );
 		if (proxy==0)  {
 			ret=E_BAD_ADDRESS;
 			goto error01;

modules/tm/uac.c

@@ -198,7 +198,8 @@ int t_uac(str* method, str* headers, str* body, dlg_t* dialog,
 			dialog->hooks.next_hop->s);
 
 	/* calculate the socket corresponding to next hop */
-	proxy = uri2proxy( dialog->hooks.next_hop, PROTO_NONE );
+	proxy = uri2proxy( dialog->hooks.next_hop,
+		dialog->send_sock ? dialog->send_sock->proto : PROTO_NONE );
 	if (proxy==0)  {
 		ret=E_BAD_ADDRESS;
 		goto error3;