bluetooth: don't send unsolicted replies to the endpoint Release() call

It was reported that PulseAudio causes error messages in syslog from
dbus-daemon:

Jan 14 04:51:32 gentoo dbus-daemon[2492]: [system] Rejected send message, 2 matched rules; type="error", sender=":1.15" (uid=1000 pid=2864 comm="/usr/bin/pulseaudio --start --log-target=syslog ") interface="(unset)" member="(unset)" error name="org.bluez.MediaEndpoint1.Error.NotImplemented" requested_reply="0" destination=":1.1" (uid=0 pid=2670 comm="/usr/libexec/bluetooth/bluetoothd ")

The default policy on the system bus is to not let any method call
replies through if they have not been requested, and apparently
bluetoothd doesn't want replies to the Release() call.

This also changes the reply type from error to normal reply. The "not
implemented" error didn't make sense to me. We don't do any cleanup in
the Release() handler, probably because there's nothing to do. If there
is some cleanup that we should do, then it's a serious bug not to do it.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=104646

diff --git a/src/modules/bluetooth/bluez5-util.c b/src/modules/bluetooth/bluez5-util.c
index cc8d87f..2d83373 100644 (file)
--- a/src/modules/bluetooth/bluez5-util.c
+++ b/src/modules/bluetooth/bluez5-util.c
@@ -1641,10 +1641,25 @@ fail:
 }
 
 static DBusMessage *endpoint_release(DBusConnection *conn, DBusMessage *m, void *userdata) {
-    DBusMessage *r;
+    DBusMessage *r = NULL;
 
-    pa_assert_se(r = dbus_message_new_error(m, BLUEZ_MEDIA_ENDPOINT_INTERFACE ".Error.NotImplemented",
-                                            "Method not implemented"));
+    /* From doc/media-api.txt in bluez:
+     *
+     *    This method gets called when the service daemon
+     *    unregisters the endpoint. An endpoint can use it to do
+     *    cleanup tasks. There is no need to unregister the
+     *    endpoint, because when this method gets called it has
+     *    already been unregistered.
+     *
+     * We don't have any cleanup to do. */
+
+    /* Reply only if requested. Generally bluetoothd doesn't request a reply
+     * to the Release() call. Sending replies when not requested on the system
+     * bus tends to cause errors in syslog from dbus-daemon, because it
+     * doesn't let unexpected replies through, so it's important to have this
+     * check here. */
+    if (!dbus_message_get_no_reply(m))
+        pa_assert_se(r = dbus_message_new_method_return(m));
 
     return r;
 }