File

plugins/muc/occupant_id.lib.lua @ 12206:77ac0d96ac24

mod_s2s: Enable outgoing Direct TLS connections Makes it faster by cutting out the roundtrips involved in <starttls/>, at the cost of making an additional SRV lookup. Since we already ignore a missing <starttls/> offer and try anyway there is not much difference in security. The fact that XMPP is used and the hostnames involved might still be visible until the future Encrypted ClientHello extension allows hiding those too.
author Kim Alvefur <zash@zash.se>
date Fri, 21 Jan 2022 17:59:19 +0100
parent 12108:e9882c4c397f
child 12977:74b9e05af71e
line wrap: on
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-- Implementation of https://xmpp.org/extensions/inbox/occupant-id.html
-- XEP-0421: Anonymous unique occupant identifiers for MUCs

-- (C) 2020 Maxime “pep” Buquet <pep@bouah.net>
-- (C) 2020 Matthew Wild <mwild1@gmail.com>

local uuid = require "util.uuid";
local hmac_sha256 = require "util.hashes".hmac_sha256;
local b64encode = require "util.encodings".base64.encode;

local xmlns_occupant_id = "urn:xmpp:occupant-id:0";

local function get_room_salt(room)
	local salt = room._data.occupant_id_salt;
	if not salt then
		salt = uuid.generate();
		room._data.occupant_id_salt = salt;
	end
	return salt;
end

local function get_occupant_id(room, occupant)
	if occupant.stable_id then
		return occupant.stable_id;
	end

	local salt = get_room_salt(room)

	occupant.stable_id = b64encode(hmac_sha256(occupant.bare_jid, salt));

	return occupant.stable_id;
end

local function update_occupant(event)
	local stanza, room, occupant, dest_occupant = event.stanza, event.room, event.occupant, event.dest_occupant;

	-- "muc-occupant-pre-change" provides "dest_occupant" but not "occupant".
	if dest_occupant ~= nil then
		occupant = dest_occupant;
	end

	-- strip any existing <occupant-id/> tags to avoid forgery
	stanza:remove_children("occupant-id", xmlns_occupant_id);

	local unique_id = get_occupant_id(room, occupant);
	stanza:tag("occupant-id", { xmlns = xmlns_occupant_id, id = unique_id }):up();
end

local function muc_private(event)
	local stanza, room = event.stanza, event.room;
	local occupant = room._occupants[stanza.attr.from];

	update_occupant({
		stanza = stanza,
		room = room,
		occupant = occupant,
	});
end

if module:get_option_boolean("muc_occupant_id", true) then
	module:add_feature(xmlns_occupant_id);
	module:hook("muc-disco#info", function (event)
		event.reply:tag("feature", { var = xmlns_occupant_id }):up();
	end);

	module:hook("muc-broadcast-presence", update_occupant);
	module:hook("muc-occupant-pre-join", update_occupant);
	module:hook("muc-occupant-pre-change", update_occupant);
	module:hook("muc-occupant-groupchat", update_occupant);
	module:hook("muc-private-message", muc_private);
end

return {
	get_room_salt = get_room_salt;
	get_occupant_id = get_occupant_id;
};