feat: Avoids joining participants before jicofo is in the room. (#12923)

* feat: Avoids joining participants before jicofo is in the room.

* squash: Move away from global hook to be able to use it per muc component.

resources/prosody-plugins/mod_muc_meeting_id.lua

@@ -1,5 +1,10 @@
+local queue = require "util.queue";
 local uuid_gen = require "util.uuid".generate;
-local is_healthcheck_room = module:require "util".is_healthcheck_room;
+local main_util = module:require "util";
+local ends_with = main_util.ends_with;
+local is_healthcheck_room = main_util.is_healthcheck_room;
+
+local QUEUE_MAX_SIZE = 100;
 
 -- Module that generates a unique meetingId, attaches it to the room
 -- and adds it to all disco info form data (when room is queried or in the
@@ -46,3 +51,51 @@ end, 99);
 module:hook("muc-config-submitted/muc#roomconfig_presencebroadcast", function()
     return true;
 end, 99);
+
+--- Avoids any participant joining the room in the interval between creating the room
+--- and jicofo entering the room
+module:hook('muc-occupant-pre-join', function (event)
+    local room, stanza = event.room, event.stanza;
+
+    -- we skip processing only if jicofo_lock is set to false
+    if room.jicofo_lock == false or is_healthcheck_room(stanza.attr.from) then
+        return;
+    end
+
+    local occupant = event.occupant;
+    if ends_with(occupant.nick, '/focus') then
+        module:fire_event('jicofo-unlock-room', { room = room; });
+    else
+        room.jicofo_lock = true;
+        if not room.pre_join_queue then
+            room.pre_join_queue = queue.new(QUEUE_MAX_SIZE);
+        end
+
+        if not room.pre_join_queue:push(event) then
+            module:log('error', 'Error enqueuing occupant event for: %s', occupant.nick);
+            return true;
+        end
+        module:log('info', 'Occupant pushed to prejoin queue %s', occupant.nick);
+
+        -- stop processing
+        return true;
+    end
+end, 8); -- just after the rate limit
+
+function handle_jicofo_unlock(event)
+    local room = event.room;
+
+    room.jicofo_lock = false;
+    if not room.pre_join_queue then
+        return;
+    end
+
+    -- and now let's handle all pre_join_queue events
+    for _, ev in room.pre_join_queue:items() do
+        module:log('info', 'Occupant processed from queue %s', ev.occupant.nick);
+        room:handle_normal_presence(ev.origin, ev.stanza);
+    end
+    room.pre_join_queue = nil;
+end
+
+module:hook('jicofo-unlock-room', handle_jicofo_unlock);