plugins/mod_message.lua
author Jonas Schäfer <jonas@wielicki.name>
Mon, 10 Jan 2022 18:23:54 +0100
branch0.11
changeset 12185 783056b4e448
parent 8731 41c959c5c84b
child 11486 671f6b867e0d
permissions -rw-r--r--
util.xml: Do not allow doctypes, comments or processing instructions Yes. This is as bad as it sounds. CVE pending. In Prosody itself, this only affects mod_websocket, which uses util.xml to parse the <open/> frame, thus allowing unauthenticated remote DoS using Billion Laughs. However, third-party modules using util.xml may also be affected by this. This commit installs handlers which disallow the use of doctype declarations and processing instructions without any escape hatch. It, by default, also introduces such a handler for comments, however, there is a way to enable comments nontheless. This is because util.xml is used to parse human-facing data, where comments are generally a desirable feature, and also because comments are generally harmless.

-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--


local full_sessions = prosody.full_sessions;
local bare_sessions = prosody.bare_sessions;

local st = require "util.stanza";
local jid_bare = require "util.jid".bare;
local jid_split = require "util.jid".split;
local user_exists = require "core.usermanager".user_exists;

local function process_to_bare(bare, origin, stanza)
	local user = bare_sessions[bare];

	local t = stanza.attr.type;
	if t == "error" then
		return true; -- discard
	elseif t == "groupchat" then
		origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));
	elseif t == "headline" then
		if user and stanza.attr.to == bare then
			for _, session in pairs(user.sessions) do
				if session.presence and session.priority >= 0 then
					session.send(stanza);
				end
			end
		end  -- current policy is to discard headlines if no recipient is available
	else -- chat or normal message
		if user then -- some resources are connected
			local recipients = user.top_resources;
			if recipients then
				local sent;
				for i=1,#recipients do
					sent = recipients[i].send(stanza) or sent;
				end
				if sent then
					return true;
				end
			end
		end
		-- no resources are online
		local node, host = jid_split(bare);
		local ok
		if user_exists(node, host) then
			ok = module:fire_event('message/offline/handle', {
				username = node;
				origin = origin,
				stanza = stanza,
			});
		end

		if not ok then
			origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));
		end
	end
	return true;
end

module:hook("message/full", function(data)
	-- message to full JID received
	local origin, stanza = data.origin, data.stanza;

	local session = full_sessions[stanza.attr.to];
	if session and session.send(stanza) then
		return true;
	else -- resource not online
		return process_to_bare(jid_bare(stanza.attr.to), origin, stanza);
	end
end, -1);

module:hook("message/bare", function(data)
	-- message to bare JID received
	local origin, stanza = data.origin, data.stanza;

	return process_to_bare(stanza.attr.to or (origin.username..'@'..origin.host), origin, stanza);
end, -1);

module:add_feature("msgoffline");