view mod_muc_rtbl/mod_muc_rtbl.lua @ 5173:460f78654864

mod_muc_rtbl: also filter messages This was a bit tricky because we don't want to run the JIDs through SHA256 on each message. Took a while to come up with this simple plan of just caching the SHA256 of the JIDs on the occupants. This will leave some dirt in the occupants after unloading the module, but that should be ok; once they cycle the room, the hashes will be gone. This is direly needed, otherwise, there is a tight race between the moderation activities and the actors joining the room.
author Jonas Schäfer <jonas@wielicki.name>
date Tue, 21 Feb 2023 21:37:27 +0100
parents 0a257d1402c3
children 354832098f2f
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local array = require "util.array";
local it = require "util.iterators";
local jid = require "util.jid";
local sha256 = require "util.hashes".sha256;
local set = require "util.set";
local st = require "util.stanza";

local rtbl_service_jid = assert(module:get_option_string("muc_rtbl_jid"), "No RTBL JID supplied");
local rtbl_node = module:get_option_string("muc_rtbl_node", "muc_bans_sha256");

local banned_hashes = module:shared("banned_hashes");

module:depends("pubsub_subscription");

module:add_item("pubsub-subscription", {
	service = rtbl_service_jid;
	node = rtbl_node;

	-- Callbacks:
	on_subscribed = function()
		module:log("info", "RTBL active");
	end;

	on_error = function(err)
		module:log("error", "Failed to subscribe to RTBL: %s::%s:  %s", err.type, err.condition, err.text);
	end;

	on_item = function(event)
		local hash = event.item.attr.id;
		if not hash then return; end
		module:log("debug", "Received new hash: %s", hash);
		banned_hashes[hash] = true;
	end;

	on_retract = function (event)
		local hash = event.item.attr.id;
		if not hash then return; end
		module:log("debug", "Retracted hash: %s", hash);
		banned_hashes[hash] = nil;
	end;
});

function request_list()
	local items_request = st.iq({ to = rtbl_service_jid, from = module.host, type = "get", id = "rtbl-request" })
		:tag("pubsub", { xmlns = "http://jabber.org/protocol/pubsub" })
			:tag("items", { node = rtbl_node }):up()
		:up();

	module:send(items_request);
end

function update_list(event)
	local from_jid = event.stanza.attr.from;
	if from_jid ~= rtbl_service_jid then
		module:log("debug", "Ignoring RTBL response from unknown sender");
		return;
	end
	local items_el = event.stanza:find("{http://jabber.org/protocol/pubsub}pubsub/items");
	if not items_el then
		module:log("warn", "Invalid items response from RTBL service");
		return;
	end

	local old_entries = set.new(array.collect(it.keys(banned_hashes)));

	local n_added, n_removed, n_total = 0, 0, 0;
	for item in items_el:childtags("item") do
		local hash = item.attr.id;
		if hash then
			n_total = n_total + 1;
			if not old_entries:contains(hash) then
				-- New entry
				n_added = n_added + 1;
				banned_hashes[hash] = true;
			else
				-- Entry already existed
				old_entries:remove(hash);
			end
		end
	end

	-- Remove old entries that weren't in the received list
	for hash in old_entries do
		n_removed = n_removed + 1;
		banned_hashes[hash] = nil;
	end

	module:log("info", "%d RTBL entries received from %s (%d added, %d removed)", n_total, from_jid, n_added, n_removed);
	return true;
end

module:hook("iq-result/host/rtbl-request", update_list);

function update_hashes(occupant)
	if not occupant.mod_muc_rtbl_bare_hash then
		local bare_hash = sha256(jid.bare(event.stanza.attr.from), true);
		occupant.mod_muc_rtbl_bare_hash = bare_hash;
	end
	if not occupant.mod_muc_rtbl_host_hash then
		local host_hash = sha256(jid.host(event.stanza.attr.from), true);
		event.occupant.mod_muc_rtbl_host_hash = host_hash;
	end
end

module:hook("muc-occupant-pre-join", function (event)
	if next(banned_hashes) == nil then return end

	local from_bare = jid.bare(event.stanza.attr.from);

	local affiliation = event.room:get_affiliation(from_bare);
	if affiliation and affiliation ~= "none" then
		-- Skip check for affiliated users
		return;
	end

	update_hashes(event.occupant);
	if banned_hashes[event.occupant.mod_muc_rtbl_bare_hash] or banned_hashes[event.occupant.mod_muc_rtbl_host_hash] then
		module:log("info", "Blocked user <%s> from room <%s> due to RTBL match", from_bare, event.stanza.attr.to);
		local error_reply = st.error_reply(event.stanza, "cancel", "forbidden", "You are banned from this service", event.room.jid);
		event.origin.send(error_reply);
		return true;
	end
end);

module:hook("muc-occupant-groupchat", function(event)
	update_hashes(event.occupant);
	if banned_hashes[event.occupant.mod_muc_rtbl_bare_hash] or banned_hashes[event.occupant.mod_muc_rtbl_host_hash] then
		module:log("debug", "Blocked message from user <%s> to room <%s> due to RTBL match", event.stanza.attr.from, event.stanza.attr.to);
		local error_reply = st.error_reply(event.stanza, "cancel", "forbidden", "You are banned from this service", event.room.jid);
		event.origin.send(error_reply);
		return true;
	end
end);

module:hook("muc-private-message", function(event)
	local occupant = event.room:get_occupant_by_nick(event.stanza.attr.from);
	update_hashes(occupant);
	if banned_hashes[occupant.mod_muc_rtbl_bare_hash] or banned_hashes[occupant.mod_muc_rtbl_host_hash] then
		module:log("debug", "Blocked private message from user <%s> from room <%s> due to RTBL match", occupant.bare_jid, event.stanza.attr.to);
		local error_reply = st.error_reply(event.stanza, "cancel", "forbidden", "You are banned from this service", event.room.jid);
		event.origin.send(error_reply);
		return true;
	end
end);

if prosody.start_time then
	request_list();
else
	module:hook_global("server-started", function ()
		request_list();
	end);
end