rtsp-server: fixed segfault in gst_rtsp_server_create_socket

Do not assume that *error is set in g_socket_address_enumerator_next.
Added test_bind_already_in_use unit-test.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=681914

gst/rtsp-server/rtsp-server.c

@@ -594,7 +594,10 @@ gst_rtsp_server_create_socket (GstRTSPServer * server,
     sockaddr =
         g_socket_address_enumerator_next (enumerator, cancellable, error);
     if (!sockaddr) {
-      GST_DEBUG_OBJECT (server, "no more addresses %s", (*error)->message);
+      if (!*error)
+        GST_DEBUG_OBJECT (server, "no more addresses %s", *error ? (*error)->message : "");
+      else
+        GST_DEBUG_OBJECT (server, "failed to retrieve next address %s", (*error)->message);
       break;
     }
 
@@ -696,7 +699,7 @@ gst_rtsp_server_create_socket (GstRTSPServer * server,
         g_error_free (sock_error);
     }
     if (bind_error) {
-      if (error == NULL)
+      if ((error == NULL) || (*error == NULL))
         g_propagate_error (error, bind_error);
       else
         g_error_free (bind_error);

tests/check/gst/rtspserver.c

@@ -688,6 +688,39 @@ GST_START_TEST (test_play_without_session)
 
 GST_END_TEST;
 
+GST_START_TEST (test_bind_already_in_use)
+{
+  GstRTSPServer *serv;
+  GSocketService *service;
+  GError *error = NULL;
+  guint16 port;
+  gchar *port_str;
+
+  serv = gst_rtsp_server_new ();
+  service = g_socket_service_new ();
+
+  /* bind service to port */
+  port = g_socket_listener_add_any_inet_port (G_SOCKET_LISTENER (service), NULL, &error);
+  g_assert_no_error (error);
+
+  port_str = g_strdup_printf ("%d\n", port);
+
+  /* try to bind server to the same port */
+  g_object_set (serv, "service", port_str, NULL);
+  g_free (port_str);
+
+  /* attach to default main context */
+  fail_unless (gst_rtsp_server_attach (serv, NULL) == 0);
+
+  /* cleanup */
+  g_object_unref (serv);
+  g_socket_listener_close (G_SOCKET_LISTENER (service));
+  g_object_unref (service);
+}
+
+GST_END_TEST;
+
+
 static Suite *
 rtspserver_suite (void)
 {
@@ -704,6 +737,7 @@ rtspserver_suite (void)
   tcase_add_test (tc, test_setup_non_existing_stream);
   tcase_add_test (tc, test_play);
   tcase_add_test (tc, test_play_without_session);
+  tcase_add_test (tc, test_bind_already_in_use);
 
   return s;
 }