Handle get_subscribed_rooms call from mod_muc_room pid

Previously sometimes we tried to post message to all online rooms, and
if that was called from muc room pid, we were not able to process that
message for that room and send response, and this did lead to timeout.

src/mod_muc.erl

@@ -758,6 +758,10 @@ get_subscribed_rooms(Host, User) ->
     ServerHost = ejabberd_router:host_of_route(Host),
     get_subscribed_rooms(ServerHost, Host, User).
 
+-record(subscriber, {jid :: jid(),
+		     nick = <<>> :: binary(),
+		     nodes = [] :: [binary()]}).
+
 -spec get_subscribed_rooms(binary(), binary(), jid()) ->
 			   {ok, [{jid(), [binary()]}]} | {error, any()}.
 get_subscribed_rooms(ServerHost, Host, From) ->
@@ -768,7 +772,15 @@ get_subscribed_rooms(ServerHost, Host, From) ->
 	false ->
 	    Rooms = get_online_rooms(ServerHost, Host),
 	    {ok, lists:flatmap(
-		   fun({Name, _, Pid}) ->
+		   fun({Name, _, Pid}) when Pid == self() ->
+		       USR = jid:split(BareFrom),
+		       case erlang:get(muc_subscribers) of
+			   #{USR := #subscriber{nodes = Nodes}} ->
+			       [{jid:make(Name, Host), Nodes}];
+			   _ ->
+			       []
+		       end;
+		       ({Name, _, Pid}) ->
 			   case p1_fsm:sync_send_all_state_event(
 				  Pid, {is_subscribed, BareFrom}) of
 			       {true, Nodes} ->

src/mod_muc_room.erl

@@ -538,6 +538,7 @@ handle_sync_event({change_config, Config}, _From,
     {reply, {ok, NSD#state.config}, StateName, NSD};
 handle_sync_event({change_state, NewStateData}, _From,
 		  StateName, _StateData) ->
+    erlang:put(muc_subscribers, NewStateData#state.subscribers),
     {reply, {ok, NewStateData}, StateName, NewStateData};
 handle_sync_event({process_item_change, Item, UJID}, _From, StateName, StateData) ->
     case process_item_change(Item, StateData, UJID) of
@@ -4373,6 +4374,7 @@ store_room(StateData) ->
     store_room(StateData, []).
 store_room(StateData, ChangesHints) ->
     % Let store persistent rooms or on those backends that have get_subscribed_rooms
+    erlang:put(muc_subscribers, StateData#state.subscribers),
     ShouldStore = case (StateData#state.config)#config.persistent of
 		      true ->
 			  true;