-- Prosody IM

-- Copyright (C) 2008-2011 Matthew Wild

-- Copyright (C) 2008-2011 Waqas Hussain

-- Copyright (C) 2009 Thilo Cestonaro

-- 

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

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

--

module:set_global();

local jid_compare, jid_prep = require "util.jid".compare, require "util.jid".prep;

local st = require "util.stanza";

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

local b64 = require "util.encodings".base64.encode;

local server = require "net.server";

local sessions, transfers = module:shared("sessions", "transfers");

local max_buffer_size = 4096;

local listener = {};

function listener.onincoming(conn, data)

	local session = sessions[conn] or {};

	local transfer = transfers[session.sha];

	if transfer and transfer.activated then -- copy data between initiator and target

		local initiator, target = transfer.initiator, transfer.target;

		(conn == initiator and target or initiator):write(data);

		return;

	end -- FIXME server.link should be doing this?

	if not session.greeting_done then

		local nmethods = data:byte(2) or 0;

		if data:byte(1) == 0x05 and nmethods > 0 and #data == 2 + nmethods then -- check if we have all the data

			if data:find("%z") then -- 0x00 = 'No authentication' is supported

				session.greeting_done = true;

				sessions[conn] = session;

				conn:write("\5\0"); -- send (SOCKS version 5, No authentication)

				module:log("debug", "SOCKS5 greeting complete");

				return;

			end

		end -- else error, unexpected input

		conn:write("\5\255"); -- send (SOCKS version 5, no acceptable method)

		conn:close();

		module:log("debug", "Invalid SOCKS5 greeting recieved: '%s'", b64(data));

	else -- connection request

		--local head = string.char( 0x05, 0x01, 0x00, 0x03, 40 ); -- ( VER=5=SOCKS5, CMD=1=CONNECT, RSV=0=RESERVED, ATYP=3=DOMAIMNAME, SHA-1 size )

		if #data == 47 and data:sub(1,5) == "\5\1\0\3\40" and data:sub(-2) == "\0\0" then

			local sha = data:sub(6, 45);

			conn:pause();

			conn:write("\5\0\0\3\40" .. sha .. "\0\0"); -- VER, REP, RSV, ATYP, BND.ADDR (sha), BND.PORT (2 Byte)

			if not transfers[sha] then

				transfers[sha] = {};

				transfers[sha].target = conn;

				session.sha = sha;

				module:log("debug", "SOCKS5 target connected for session %s", sha);

			else -- transfers[sha].target ~= nil

				transfers[sha].initiator = conn;

				session.sha = sha;

				module:log("debug", "SOCKS5 initiator connected for session %s", sha);

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

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

			end

		else -- error, unexpected input

			conn:write("\5\1\0\3\0\0\0"); -- VER, REP, RSV, ATYP, BND.ADDR (sha), BND.PORT (2 Byte)

			conn:close();

			module:log("debug", "Invalid SOCKS5 negotiation recieved: '%s'", b64(data));

		end

	end

end

function listener.ondisconnect(conn, err)

	local session = sessions[conn];

	if session then

		if 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

function module.add_host(module)

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

	local proxy_address = module:get_option("proxy65_address", host);

	local proxy_acl = module:get_option("proxy65_acl");

	module:add_identity("proxy", "bytestreams", name);

	module:add_feature("http://jabber.org/protocol/bytestreams");

	module:hook("iq-get/host/http://jabber.org/protocol/disco#info:query", function(event)

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

		origin.send(st.reply(stanza):query("http://jabber.org/protocol/disco#info")

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

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

		return true;

	end, -1);

	module:hook("iq-get/host/http://jabber.org/protocol/disco#items:query", function(event)

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

		origin.send(st.reply(stanza):query("http://jabber.org/protocol/disco#items"));

		return true;

	end, -1);

	module:hook("iq-get/host/http://jabber.org/protocol/bytestreams:query", function(event)

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

		-- check ACL

		while proxy_acl and #proxy_acl > 0 do -- using 'while' instead of 'if' so we can break out of it

			local jid = stanza.attr.from;

			for _, acl in ipairs(proxy_acl) do

				if jid_compare(jid, acl) then break; end

			end

			module:log("warn", "Denying use of proxy for %s", tostring(stanza.attr.from));

			origin.send(st.error_reply(stanza, "auth", "forbidden"));

			return true;

		end

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

		origin.send(st.reply(stanza):tag("query", {xmlns="http://jabber.org/protocol/bytestreams", sid=sid})

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

		return true;

	end);

	module:hook("iq-set/host/http://jabber.org/protocol/bytestreams:query", function(event)

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

		local query = stanza.tags[1];

		local sid = query.attr.sid;

		local from = stanza.attr.from;

		local to = query:get_child_text("activate");

		local prepped_to = jid_prep(to);

		local info = "sid: "..tostring(sid)..", initiator: "..tostring(from)..", target: "..tostring(prepped_to or to);

		if prepped_to and sid then

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

			if not transfers[sha] then

				module:log("debug", "Activation request has unknown session id; activation failed (%s)", info);

				origin.send(st.error_reply(stanza, "modify", "item-not-found"));

			elseif not transfers[sha].initiator then

				module:log("debug", "The sender was not connected to the proxy; activation failed (%s)", info);

				origin.send(st.error_reply(stanza, "cancel", "not-allowed", "The sender (you) is not connected to the proxy"));

			--elseif not transfers[sha].target then -- can't happen, as target is set when a transfer object is created

			--	module:log("debug", "The recipient was not connected to the proxy; activation failed (%s)", info);

			--	origin.send(st.error_reply(stanza, "cancel", "not-allowed", "The recipient is not connected to the proxy"));

			else -- if transfers[sha].initiator ~= nil and transfers[sha].target ~= nil then

				module:log("debug", "Transfer activated (%s)", info);

				transfers[sha].activated = true;

				transfers[sha].target:resume();

				transfers[sha].initiator:resume();

				origin.send(st.reply(stanza));

			end

		elseif to and sid then

			module:log("debug", "Malformed activation jid; activation failed (%s)", info);

			origin.send(st.error_reply(stanza, "modify", "jid-malformed"));

		else

			module:log("debug", "Bad request; activation failed (%s)", info);

			origin.send(st.error_reply(stanza, "modify", "bad-request"));

		end

		return true;

	end);

end

module:provides("net", {

	default_port = 5000;

	listener = listener;

	multiplex = {

		pattern = "^\5";

	};

});