-- 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, jid_join, jid_compare = require "util.jid".split, require "util.jid".join, require "util.jid".compare;

local st = require "util.stanza";

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

local connlisteners = require "net.connlisteners";

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

local server = require "net.server";

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 max_buffer_size = 4096;

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

function connlistener.onincoming(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].target ~= nil then

				if  transfers[sha].initiator == conn then

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

				else

					transfers[sha].initiator:write(data);

				end

				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 ... ");

				server.link(conn, transfers[sha].target, max_buffer_size);

				server.link(transfers[sha].target, conn, max_buffer_size);

			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)

			conn:lock_read(true)

		else

			module:log("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.ondisconnect(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 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 = stanza.attr.from;

	if proxy_acl and #proxy_acl > 0 then

		for _, acl in ipairs(proxy_acl) do

			if jid_compare(jid, acl) then allow = true; 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));

		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()

	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(event)

	local origin, stanza = event.origin, event.stanza;

	if stanza.attr.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;

		else

			origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));

			return true;

		end

	else -- stanza.attr.type == "set"

		module:log("debug", "Received activation request from %s", stanza.attr.from);

		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

				module:log("error", "transfers[sha]: nil");

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

				origin.send(reply);

				transfers[sha].activated = true;

				transfers[sha].target:lock_read(false);

				transfers[sha].initiator:lock_read(false);

			else

				module:log("debug", "Both parties were not yet connected");

				local message = "Neither party is connected to the proxy";

				if transfers[sha].initiator then

					message = "The recipient is not connected to the proxy";

				elseif transfers[sha].target then

					message = "The sender (you) is not connected to the proxy";

				end

				origin.send(st.error_reply(stanza, "cancel", "not-allowed", message));

			end

			return true;

		else

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

		end

	end

end

module:hook("iq/host", handle_to_domain);

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

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

	module:log("error", "Possibly two proxy65 components are configured to share the same port.");

end

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