File

util/jid.lua @ 12180:53e0ae770917

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.
author Jonas Schäfer <jonas@wielicki.name>
date Mon, 10 Jan 2022 18:23:54 +0100
parent 11056:0b0a42542456
child 12190:3616128cd2e3
line wrap: on
line source

-- 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 select = select;
local match, sub = string.match, string.sub;
local nodeprep = require "util.encodings".stringprep.nodeprep;
local nameprep = require "util.encodings".stringprep.nameprep;
local resourceprep = require "util.encodings".stringprep.resourceprep;

local escapes = {
	[" "] = "\\20"; ['"'] = "\\22";
	["&"] = "\\26"; ["'"] = "\\27";
	["/"] = "\\2f"; [":"] = "\\3a";
	["<"] = "\\3c"; [">"] = "\\3e";
	["@"] = "\\40"; ["\\"] = "\\5c";
};
local unescapes = {};
local backslash_escapes = {};
for k,v in pairs(escapes) do
	unescapes[v] = k;
	backslash_escapes[v] = v:gsub("\\", escapes)
end

local _ENV = nil;
-- luacheck: std none

local function split(jid)
	if not jid then return; end
	local node, nodepos = match(jid, "^([^@/]+)@()");
	local host, hostpos = match(jid, "^([^@/]+)()", nodepos);
	if node and not host then return nil, nil, nil; end
	local resource = match(jid, "^/(.+)$", hostpos);
	if (not host) or ((not resource) and #jid >= hostpos) then return nil, nil, nil; end
	return node, host, resource;
end

local function bare(jid)
	local node, host = split(jid);
	if node and host then
		return node.."@"..host;
	end
	return host;
end

local function prepped_split(jid, strict)
	local node, host, resource = split(jid);
	if host and host ~= "." then
		if sub(host, -1, -1) == "." then -- Strip empty root label
			host = sub(host, 1, -2);
		end
		host = nameprep(host, strict);
		if not host then return; end
		if node then
			node = nodeprep(node, strict);
			if not node then return; end
		end
		if resource then
			resource = resourceprep(resource, strict);
			if not resource then return; end
		end
		return node, host, resource;
	end
end

local function join(node, host, resource)
	if not host then return end
	if node and resource then
		return node.."@"..host.."/"..resource;
	elseif node then
		return node.."@"..host;
	elseif resource then
		return host.."/"..resource;
	end
	return host;
end

local function prep(jid, strict)
	local node, host, resource = prepped_split(jid, strict);
	return join(node, host, resource);
end

local function compare(jid, acl)
	-- compare jid to single acl rule
	-- TODO compare to table of rules?
	local jid_node, jid_host, jid_resource = split(jid);
	local acl_node, acl_host, acl_resource = split(acl);
	if ((acl_node ~= nil and acl_node == jid_node) or acl_node == nil) and
		((acl_host ~= nil and acl_host == jid_host) or acl_host == nil) and
		((acl_resource ~= nil and acl_resource == jid_resource) or acl_resource == nil) then
		return true
	end
	return false
end

local function node(jid)
	return (select(1, split(jid)));
end

local function host(jid)
	return (select(2, split(jid)));
end

local function resource(jid)
	return (select(3, split(jid)));
end

local function escape(s) return s and (s:gsub("\\%x%x", backslash_escapes):gsub("[\"&'/:<>@ ]", escapes)); end
local function unescape(s) return s and (s:gsub("\\%x%x", unescapes)); end

return {
	split = split;
	bare = bare;
	prepped_split = prepped_split;
	join = join;
	prep = prep;
	compare = compare;
	node = node;
	host = host;
	resource = resource;
	escape = escape;
	unescape = unescape;
};