view mod_muc_limits/mod_muc_limits.lua @ 3965:2b10e51d85a6

mod_muc_limits: Add config option to limit to join stanzas only This is a bit more limited in pre-0.11 MUC modules, because it just detects stanzas sent to full JIDs (which would include all presence and nick changes). This option is useful for setups where users are typically unaffiliated, but trusted (e.g. if access to the room is gated through some other means such as password/token auth).
author Matthew Wild <mwild1@gmail.com>
date Fri, 03 Apr 2020 12:26:56 +0100
parents 15355caf4553
children
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local mod_muc = module:depends"muc";
local rooms = rawget(mod_muc, "rooms"); -- Old MUC API

local jid_split, jid_bare = require "util.jid".split, require "util.jid".bare;
local st = require "util.stanza";
local new_throttle = require "util.throttle".create;
local t_insert, t_concat = table.insert, table.concat;

local xmlns_muc = "http://jabber.org/protocol/muc";

local period = math.max(module:get_option_number("muc_event_rate", 0.5), 0);
local burst = math.max(module:get_option_number("muc_burst_factor", 6), 1);

local max_nick_length = module:get_option_number("muc_max_nick_length", 23); -- Default chosen through scientific methods
local join_only = module:get_option_boolean("muc_limit_joins_only", false);
local dropped_count = 0;
local dropped_jids;

local function log_dropped()
	module:log("warn", "Dropped %d stanzas from %d JIDs: %s", dropped_count, #dropped_jids, t_concat(dropped_jids, ", "));
	dropped_count = 0;
	dropped_jids = nil;
end

local function handle_stanza(event)
	local origin, stanza = event.origin, event.stanza;
	if stanza.name == "presence" and stanza.attr.type == "unavailable" then -- Don't limit room leaving
		return;
	end
	local dest_room, dest_host, dest_nick = jid_split(stanza.attr.to);
	local room = event.room or rooms[dest_room.."@"..dest_host];
	if not room then return; end
	local from_jid = stanza.attr.from;
	if room:get_affiliation(jid_bare(from_jid)) then
		module:log("debug", "Skipping stanza from affiliated user...");
		return;
	elseif dest_nick and max_nick_length and stanza.name == "presence" and not room._occupants[stanza.attr.to] and #dest_nick > max_nick_length then
		module:log("debug", "Forbidding long (%d bytes) nick in %s", #dest_nick, dest_room)
		origin.send(st.error_reply(stanza, "modify", "policy-violation", "Your nick name is too long, please use a shorter one")
			:up():tag("x", { xmlns = xmlns_muc }));
		return true;
	end
	local throttle = room.throttle;
	if not room.throttle then
		throttle = new_throttle(period*burst, burst);
		room.throttle = throttle;
	end
	if not throttle:poll(1) then
		module:log("debug", "Dropping stanza for %s@%s from %s, over rate limit", dest_room, dest_host, from_jid);
		if not dropped_jids then
			dropped_jids = { [from_jid] = true, from_jid };
			module:add_timer(5, log_dropped);
		elseif not dropped_jids[from_jid] then
			dropped_jids[from_jid] = true;
			t_insert(dropped_jids, from_jid);
		end
		dropped_count = dropped_count + 1;
		if stanza.attr.type == "error" then -- We don't want to bounce errors
			return true;
		end
		local reply = st.error_reply(stanza, "wait", "policy-violation", "The room is currently overactive, please try again later");
		local body = stanza:get_child_text("body");
		if body then
			reply:up():tag("body"):text(body):up();
		end
		local x = stanza:get_child("x", xmlns_muc);
		if x then
			reply:add_child(st.clone(x));
		end
		origin.send(reply);
		return true;
	end
end

if rooms then
	function module.unload()
		for room_jid, room in pairs(rooms) do --luacheck: ignore 213/room_jid
			room.throttle = nil;
		end
	end

	module:hook("presence/full", handle_stanza, 501);
	if not join_only then
		module:hook("message/bare", handle_stanza, 501);
		module:hook("message/full", handle_stanza, 501);
		module:hook("presence/bare", handle_stanza, 501);
	end
else
	module:hook("muc-occupant-pre-join", handle_stanza);
	if not join_only then
		module:hook("muc-occupant-pre-change", handle_stanza);
		module:hook("muc-occupant-groupchat", handle_stanza);
	end
end