-- Copyright (C) 2009 Thilo Cestonaro

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

--[[

* to restart the proxy in the console: e.g.

module:unload("proxy65");

> server.removeserver(<proxy65_port>);

module:load("proxy65", <proxy65_jid>);

]]--

if module:get_host_type() ~= "component" then

	error("proxy65 should be loaded as a component, please see http://prosody.im/doc/components", 0);

end

local jid_split = require "util.jid".split;

local st = require "util.stanza";

local componentmanager = require "core.componentmanager";

local config_get = require "core.configmanager".get;

local connlisteners = require "net.connlisteners";

local sha1 = require "util.hashes".sha1;

local host, name = module:get_host(), "SOCKS5 Bytestreams Service";

local sessions, transfers, component, replies_cache = {}, {}, nil, {};

local proxy_port = config_get(host, "core", "proxy65_port") or 5000;

local proxy_interface = config_get(host, "core", "proxy65_interface") or "*";

local proxy_address = config_get(host, "core", "proxy65_address") or (proxy_interface ~= "*" and proxy_interface) or host;

local proxy_acl = config_get(host, "core", "proxy65_acl");

local connlistener = { default_port = proxy_port, default_interface = proxy_interface, default_mode = "*a" };

function connlistener.listener(conn, data)

	local session = sessions[conn] or {};

	if session.setup == nil and data ~= nil and data:sub(1):byte() == 0x05 and data:len() > 2 then

		local nmethods = data:sub(2):byte();

		local methods = data:sub(3);

		local supported = false;

		for i=1, nmethods, 1 do

			if(methods:sub(i):byte() == 0x00) then -- 0x00 == method: NO AUTH

				supported = true;

				break;

			end

		end

		if(supported) then

			module:log("debug", "new session found ... ")

			session.setup = true;

			sessions[conn] = session;

			conn.write(string.char(5, 0));

		end

		return;

	end

	if session.setup then

		if session.sha ~= nil and transfers[session.sha] ~= nil then

			local sha = session.sha;

			if transfers[sha].activated == true and transfers[sha].initiator == conn and transfers[sha].target ~= nil then

				transfers[sha].target.write(data);

				return;

			end

		end

		if data ~= nil and data:len() == 0x2F and  -- 40 == length of SHA1 HASH, and 7 other bytes => 47 => 0x2F

			data:sub(1):byte() == 0x05 and -- SOCKS5 has 5 in first byte

			data:sub(2):byte() == 0x01 and -- CMD must be 1

			data:sub(3):byte() == 0x00 and -- RSV must be 0

			data:sub(4):byte() == 0x03 and -- ATYP must be 3

			data:sub(5):byte() == 40 and -- SHA1 HASH length must be 40 (0x28)

			data:sub(-2):byte() == 0x00 and -- PORT must be 0, size 2 byte

			data:sub(-1):byte() == 0x00 		

		then

			local sha = data:sub(6, 45); -- second param is not count! it's the ending index (included!)

			if transfers[sha] == nil then

				transfers[sha] = {};

				transfers[sha].activated = false;

				transfers[sha].target = conn;

				session.sha = sha;

				module:log("debug", "target connected ... ");

			elseif transfers[sha].target ~= nil then

				transfers[sha].initiator = conn;

				session.sha = sha;

				module:log("debug", "initiator connected ... ");

			end

			conn.write(string.char(5, 0, 0, 3, sha:len()) .. sha .. string.char(0, 0)); -- VER, REP, RSV, ATYP, BND.ADDR (sha), BND.PORT (2 Byte)

		else

			log:module("warn", "Neither data transfer nor initial connect of a participator of a transfer.")

			conn.close();

		end

	else

		if data ~= nil then

			module:log("warn", "unknown connection with no authentication data -> closing it");

			conn.close();

		end

	end

end

function connlistener.disconnect(conn, err)

	local session = sessions[conn];

	if session then

		if session.sha and transfers[session.sha] then

			local initiator, target = transfers[session.sha].initiator, transfers[session.sha].target;

			if initiator == conn and target ~= nil then

				target.close();

			elseif target == conn and initiator ~= nil then

			 	initiator.close();

			end

			transfers[session.sha] = nil;

		end

		-- Clean up any session-related stuff here

		sessions[conn] = nil;

	end

end

local function get_disco_info(stanza)

	local reply = replies_cache.disco_info;

	if reply == nil then

	 	reply = st.iq({type='result', from=host}):query("http://jabber.org/protocol/disco#info")

			:tag("identity", {category='proxy', type='bytestreams', name=name}):up()

			:tag("feature", {var="http://jabber.org/protocol/bytestreams"});

		replies_cache.disco_info = reply;

	end

	reply.attr.id = stanza.attr.id;

	reply.attr.to = stanza.attr.from;

	return reply;

end

local function get_disco_items(stanza)

	local reply = replies_cache.disco_items;

	if reply == nil then

	 	reply = st.iq({type='result', from=host}):query("http://jabber.org/protocol/disco#items");

		replies_cache.disco_items = reply;

	end

	reply.attr.id = stanza.attr.id;

	reply.attr.to = stanza.attr.from;

	return reply;

end

local function _jid_join(node, host, resource)

	local ret = host;

	if ret then

		if node then

			ret = node .. "@" .. ret;

		end

		if resource then

			ret = ret .. "/" .. resource;

		end

	end

	return ret;

end

local function get_stream_host(origin, stanza)

	local reply = replies_cache.stream_host;

	local err_reply = replies_cache.stream_host_err;

	local sid = stanza.tags[1].attr.sid;

	local allow = false;

	local jid_node, jid_host, jid_resource = jid_split(stanza.attr.from);

	if stanza.attr.from == nil then

		jid_node = origin.username;

		jid_host = origin.host;

		jid_resource = origin.resource;

	end

	if proxy_acl and #proxy_acl > 0 then

		if host ~= nil then -- at least a domain is needed.

			for _, acl in ipairs(proxy_acl) do

				local acl_node, acl_host, acl_resource = jid_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

					allow = true;

				end

			end

		end

	else

		allow = true;

	end

	if allow == true then

		if reply == nil then

			reply = st.iq({type="result", from=host})

				:query("http://jabber.org/protocol/bytestreams")

				:tag("streamhost", {jid=host, host=proxy_address, port=proxy_port});

			replies_cache.stream_host = reply;

		end

	else

		module:log("warn", "Denying use of proxy for %s", tostring(_jid_join(jid_node, jid_host, jid_resource)));

		if err_reply == nil then

			err_reply = st.iq({type="error", from=host})

				:query("http://jabber.org/protocol/bytestreams")

				:tag("error", {code='403', type='auth'})

				:tag("forbidden", {xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'});

			replies_cache.stream_host_err = err_reply;

		end

		reply = err_reply;

	end

	reply.attr.id = stanza.attr.id;

	reply.attr.to = stanza.attr.from;

	reply.tags[1].attr.sid = sid;

	return reply;

end

module.unload = function()

	componentmanager.deregister_component(host);

	connlisteners.deregister(module.host .. ':proxy65');

end

local function set_activation(stanza)

	local from, to, sid, reply = nil;

	from = stanza.attr.from;

	if stanza.tags[1] ~= nil and tostring(stanza.tags[1].name) == "query" then

		if stanza.tags[1].attr ~= nil then

			sid = stanza.tags[1].attr.sid;

		end

		if stanza.tags[1].tags[1] ~= nil and tostring(stanza.tags[1].tags[1].name) == "activate" then

			to = stanza.tags[1].tags[1][1];

		end

	end

	if from ~= nil and to ~= nil and sid ~= nil then

		reply = st.iq({type="result", from=host, to=from});

		reply.attr.id = stanza.attr.id;

	end

	return reply, from, to, sid;

end

function handle_to_domain(origin, stanza)

	local to_node, to_host, to_resource = jid_split(stanza.attr.to);

	if to_node == nil then

		local type = stanza.attr.type;

		if type == "error" or type == "result" then return; end

		if stanza.name == "iq" and type == "get" then

			local xmlns = stanza.tags[1].attr.xmlns

			if xmlns == "http://jabber.org/protocol/disco#info" then

				origin.send(get_disco_info(stanza));

				return true;

			elseif xmlns == "http://jabber.org/protocol/disco#items" then

				origin.send(get_disco_items(stanza));

				return true;

			elseif xmlns == "http://jabber.org/protocol/bytestreams" then

				origin.send(get_stream_host(origin, stanza));

				return true;

			end

		elseif stanza.name == "iq" and type == "set" then

			local reply, from, to, sid = set_activation(stanza);

			if reply ~= nil and from ~= nil and to ~= nil and sid ~= nil then

				local sha = sha1(sid .. from .. to, true);

				if transfers[sha] == nil then

				elseif(transfers[sha] ~= nil and transfers[sha].initiator ~= nil and transfers[sha].target ~= nil) then

					origin.send(reply);

					transfers[sha].activated = true;

				end

			else

				module:log("error", "activation failed: sid: %s, initiator: %s, target: %s", tostring(sid), tostring(from), tostring(to));

			end

		end

	end

	return;

end

if not connlisteners.register(module.host .. ':proxy65', connlistener) then

	error("mod_proxy65: Could not establish a connection listener. Check your configuration please.");

	error(" one possible cause for this would be that two proxy65 components share the same port.");

end

connlisteners.start(module.host .. ':proxy65');

component = componentmanager.register_component(host, handle_to_domain);