-- * Metronome IM *
--
-- This file is part of the Metronome XMPP server and is released under the
-- ISC License, please see the LICENSE file in this source package for more
-- information about copyright and licensing.
--
-- As per the sublicensing clause, this file is also MIT/X11 Licensed.
-- ** Copyright (c) 2009-2012, Kim Alvefur, Matthew Wild, Sjoerd Simons, Waqas Hussain

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 portmanager = require "core.portmanager";

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_port = next(portmanager.get_active_services():search("proxy65", nil)[1] or {});
	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;
		if not stanza.tags[1].attr.node then
			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"}) );
		else
			origin.send(st.error_reply(stanza, "cancel", "item-not-found"))
		end

		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;
			local allow;
			for _, acl in ipairs(proxy_acl) do
				if jid_compare(jid, acl) then allow = true; break; end
			end
			if allow then break; 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"));
			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:add_item("net-provider", {
	name = "proxy65",
	default_port = 5000,
	listener = listener,
	multiplex = {
		pattern = "^\5"
	}
});
