From 3d8711f708bbd7bb25b2b8b5a1714d775199a026 Mon Sep 17 00:00:00 2001
From: Evgeny Khramtsov <ekhramtsov@process-one.net>
Date: Sat, 11 May 2019 19:27:56 +0300
Subject: [PATCH] Avoid late arrival of get_disco_item response

---
 src/mod_muc.erl      | 26 +++++++++++++++-----------
 src/mod_muc_room.erl | 13 ++++++++++---
 2 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/src/mod_muc.erl b/src/mod_muc.erl
index edc570eed..a3447b281 100644
--- a/src/mod_muc.erl
+++ b/src/mod_muc.erl
@@ -740,17 +740,21 @@ iq_disco_items(_ServerHost, _Host, _From, Lang, _MaxRoomsDiscoItems, _Node, _RSM
 -spec get_room_disco_item({binary(), binary(), pid()},
 			  term()) -> {ok, disco_item()} |
 				     {error, timeout | notfound}.
-get_room_disco_item({Name, Host, Pid}, Query) ->
-	    RoomJID = jid:make(Name, Host),
-	    try p1_fsm:sync_send_all_state_event(Pid, Query, 100) of
-		{item, Desc} ->
-		    {ok, #disco_item{jid = RoomJID, name = Desc}};
-		false ->
-		    {error, notfound}
-	    catch _:{timeout, {p1_fsm, _, _}} ->
-		    {error, timeout};
-		  _:{_, {p1_fsm, _, _}} ->
-		    {error, notfound}
+get_room_disco_item({Name, Host, Pid},
+		    {get_disco_item, Filter, JID, Lang}) ->
+    RoomJID = jid:make(Name, Host),
+    Timeout = 100,
+    Time = erlang:monotonic_time(millisecond),
+    Query1 = {get_disco_item, Filter, JID, Lang, Time+Timeout},
+    try p1_fsm:sync_send_all_state_event(Pid, Query1, Timeout) of
+	{item, Desc} ->
+	    {ok, #disco_item{jid = RoomJID, name = Desc}};
+	false ->
+	    {error, notfound}
+    catch _:{timeout, {p1_fsm, _, _}} ->
+	    {error, timeout};
+	  _:{_, {p1_fsm, _, _}} ->
+	    {error, notfound}
     end.
 
 -spec get_subscribed_rooms(binary(), jid()) -> {ok, [{jid(), [binary()]}]} | {error, any()}.
diff --git a/src/mod_muc_room.erl b/src/mod_muc_room.erl
index 94c430197..2d3865120 100644
--- a/src/mod_muc_room.erl
+++ b/src/mod_muc_room.erl
@@ -512,7 +512,7 @@ handle_event({set_affiliations, Affiliations},
 handle_event(_Event, StateName, StateData) ->
     {next_state, StateName, StateData}.
 
-handle_sync_event({get_disco_item, Filter, JID, Lang}, _From, StateName, StateData) ->
+handle_sync_event({get_disco_item, Filter, JID, Lang, Time}, _From, StateName, StateData) ->
     Len = maps:size(StateData#state.nicks),
     Reply = case (Filter == all) or (Filter == Len) or ((Filter /= 0) and (Len /= 0)) of
 	true ->
@@ -521,10 +521,17 @@ handle_sync_event({get_disco_item, Filter, JID, Lang}, _From, StateName, StateDa
 	false ->
 	    false
     end,
-    {reply, Reply, StateName, StateData};
-%% This clause is only for backwards compatibility
+    CurrentTime = erlang:monotonic_time(millisecond),
+    if CurrentTime < Time ->
+	    {reply, Reply, StateName, StateData};
+       true ->
+	    {next_state, StateName, StateData}
+    end;
+%% These two clauses are only for backward compatibility with nodes running old code
 handle_sync_event({get_disco_item, JID, Lang}, From, StateName, StateData) ->
     handle_sync_event({get_disco_item, any, JID, Lang}, From, StateName, StateData);
+handle_sync_event({get_disco_item, Filter, JID, Lang}, From, StateName, StateData) ->
+    handle_sync_event({get_disco_item, Filter, JID, Lang, infinity}, From, StateName, StateData);
 handle_sync_event(get_config, _From, StateName,
 		  StateData) ->
     {reply, {ok, StateData#state.config}, StateName,