jiti-meet/resources/prosody-plugins/mod_muc_rate_limit.lua

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-- enable under the main muc component
local queue = require "util.queue";
local new_throttle = require "util.throttle".create;
local timer = require "util.timer";
-- we max to 500 participants per meeting so this should be enough, we are not suppose to handle all
-- participants in one meeting
local PRESENCE_QUEUE_MAX_SIZE = 1000;
-- default to 5 participants per second
local join_rate_per_conference = module:get_option_number("muc_rate_joins", 5);
-- Measure/monitor the room rate limiting queue
local measure = require "core.statsmanager".measure;
local measure_longest_queue = measure("distribution",
"/mod_" .. module.name .. "/longest_queue");
local measure_rooms_with_queue = measure("rate",
"/mod_" .. module.name .. "/rooms_with_queue");
-- throws a stat that the queue was full, counts the total number of times we hit it
local measure_full_queue = measure("rate",
"/mod_" .. module.name .. "/full_queue");
-- keeps track of the total times we had an error processing the queue
local measure_errors_processing_queue = measure("rate",
"/mod_" .. module.name .. "/errors_processing_queue");
-- we keep track here what was the longest queue we have seen
local stat_longest_queue = 0;
-- Adds item to the queue
-- @returns false if queue is full and item was not added, true otherwise
local function add_item_to_queue(joining_queue, item, room, from)
if not joining_queue:push(item) then
module:log('error', 'Error pushing presence in queue for %s in %s', from, room.jid);
measure_full_queue();
return false;
else
-- check is this the longest queue and if so throws a stat
if joining_queue:count() > stat_longest_queue then
stat_longest_queue = joining_queue:count();
measure_longest_queue(stat_longest_queue);
end
return true;
end
end
-- process join_rate_presence_queue in the room and pops element passing them to handle_normal_presence
-- returns 1 if we want to reschedule it after 1 second
local function timer_process_queue_elements (room)
local presence_queue = room.join_rate_presence_queue;
if not presence_queue or presence_queue:count() == 0 then
return;
end
for _ = 1, join_rate_per_conference do
local ev = presence_queue:pop();
if ev then
-- we mark what we pass here so we can skip it on the next muc-occupant-pre-join event
ev.stanza.delayed_join_skip = true;
room:handle_normal_presence(ev.origin, ev.stanza);
end
end
-- if there are elements left, schedule an execution in a second
if presence_queue:count() > 0 then
return 1;
else
room.join_rate_queue_timer = false;
end
end
-- we check join rate before occupant joins. If rate is exceeded we queue the events and start a timer
-- that will run every second processing the events passing them to the room handling function handle_normal_presence
-- from where those arrived, this way we keep a maximum rate of joining
module:hook("muc-occupant-pre-join", function (event)
local room, stanza = event.room, event.stanza;
-- skipping events we had produced and clear our flag
if stanza.delayed_join_skip == true then
event.stanza.delayed_join_skip = nil;
return false;
end
local throttle = room.join_rate_throttle;
if not room.join_rate_throttle then
throttle = new_throttle(join_rate_per_conference, 1); -- rate per one second
room.join_rate_throttle = throttle;
end
if not throttle:poll(1) then
if not room.join_rate_presence_queue then
-- if this is the first item for a room we increment the stat for rooms with queues
measure_rooms_with_queue();
room.join_rate_presence_queue = queue.new(PRESENCE_QUEUE_MAX_SIZE);
end
if not add_item_to_queue(room.join_rate_presence_queue, event, room, stanza.attr.from) then
-- let's not stop processing the event
return false;
end
if not room.join_rate_queue_timer then
timer.add_task(1, function ()
local status, result = pcall(timer_process_queue_elements, room);
if not status then
-- there was an error in the timer function
module:log('error', 'Error processing queue: %s', result);
measure_errors_processing_queue();
-- let's re-schedule timer so we do not lose the queue
return 1;
end
return result;
end);
room.join_rate_queue_timer = true;
end
return true; -- we stop execution, so we do not process this join at the moment
end
if room.join_rate_queue_timer then
-- there is timer so we need to order the presences, put it in the queue
-- if add fails as queue is full we return false and the event will continue processing, we risk re-order
-- but not losing it
return add_item_to_queue(room.join_rate_presence_queue, event, room, stanza.attr.from);
end
end, 9); -- as we will rate limit joins we need to be the first to execute
-- we ran it after muc_max_occupants which is with priority 10, there is nothing to rate limit
-- if max number of occupants is reached
-- clear queue on room destroy so timer will skip next run if any
module:hook('muc-room-destroyed',function(event)
event.room.join_rate_presence_queue = nil;
end);