-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- Copyright (C) 2012 Florian Zeitz

--

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

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

--

module:set_global();

local add_task = require "util.timer".add_task;

local new_xmpp_stream = require "util.xmppstream".new;

local nameprep = require "util.encodings".stringprep.nameprep;

local sessionmanager = require "core.sessionmanager";

local st = require "util.stanza";

local sm_new_session, sm_destroy_session = sessionmanager.new_session, sessionmanager.destroy_session;

local uuid_generate = require "util.uuid".generate;

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

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

local band = require "bit".band;

local bxor = require "bit".bxor;

local tohex = require "bit".tohex;

local xpcall, tostring, type = xpcall, tostring, type;

local traceback = debug.traceback;

local xmlns_xmpp_streams = "urn:ietf:params:xml:ns:xmpp-streams";

local log = module._log;

local c2s_timeout = module:get_option_number("c2s_timeout");

local opt_keepalives = module:get_option_boolean("tcp_keepalives", false);

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

local stream_callbacks = { default_ns = "jabber:client", handlestanza = core_process_stanza };

local listener = {};

-- Websocket helpers

local function parse_frame(frame)

	local result = {};

	local pos = 1;

	local length_bytes = 0;

	local counter = 0;

	local tmp_byte;

	tmp_byte = string.byte(frame, pos);

	result.FIN = band(tmp_byte, 0x80) > 0;

	result.RSV1 = band(tmp_byte, 0x40) > 0;

	result.RSV2 = band(tmp_byte, 0x20) > 0;

	result.RSV3 = band(tmp_byte, 0x10) > 0;

	result.opcode = band(tmp_byte, 0x0F) > 0;

	pos = pos + 1;

	tmp_byte = string.byte(frame, pos);

	result.MASK = band(tmp_byte, 0x80) > 0;

	result.length = band(tmp_byte, 0x7F);

	if result.length == 126 then

		length_bytes = 2;

		result.length = 0;

	elseif result.length == 127 then

		length_bytes = 8;

		result.length = 0;

	end

	for i = 1, length_bytes do

		pos = pos + 1;

		result.length = result.length * 255 + string.byte(frame, pos);

	end

	if result.MASK then

		result.key = {string.byte(frame, pos+1), string.byte(frame, pos+2),

				string.byte(frame, pos+3), string.byte(frame, pos+4)}

		pos = pos + 5;

		result.data = "";

		for i = pos, pos + result.length - 1 do

			result.data = result.data .. string.char(bxor(result.key[counter+1], string.byte(frame, i)));

			counter = (counter + 1) % 4;

		end

	else

		result.data = frame:sub(pos + 1, pos + result.length);

	end

	return result;

end

local function build_frame(desc)

	local length;

	local result = "";

	result = result .. string.char(0x80 * (desc.FIN and 1 or 0) + desc.opcode);

	length = #desc.data;

	if length <= 125 then -- 7-bit length

		result = result .. string.char(length);

	elseif length <= 0xFFFF then -- 2-byte length

		result = result .. string.char(126);

		result = result .. string.char(length/0x100) .. string.char(length%0x100);

	else -- 8-byte length

		result = result .. string.char(127);

		for i = 7, 0, -1 do

			result = result .. string.char(( length / (2^(8*i)) ) % 0x100);

		end

	end

	result = result .. desc.data;

	return result;

end

--- Stream events handlers

local stream_xmlns_attr = {xmlns='urn:ietf:params:xml:ns:xmpp-streams'};

local default_stream_attr = { ["xmlns:stream"] = "http://etherx.jabber.org/streams", xmlns = stream_callbacks.default_ns, version = "1.0", id = "" };

function stream_callbacks.streamopened(session, attr)

	local send = session.send;

	session.host = nameprep(attr.to);

	if not session.host then

		session:close{ condition = "improper-addressing",

			text = "A valid 'to' attribute is required on stream headers" };

		return;

	end

	session.version = tonumber(attr.version) or 0;

	session.streamid = uuid_generate();

	(session.log or session)("debug", "Client sent opening <stream:stream> to %s", session.host);

	if not hosts[session.host] then

		-- We don't serve this host...

		session:close{ condition = "host-unknown", text = "This server does not serve "..tostring(session.host)};

		return;

	end

	-- COMPAT: Current client implementations need this to be self-closing

	send("<?xml version='1.0'?>"..(tostring(st.stanza("stream:stream", {

		xmlns = 'jabber:client', ["xmlns:stream"] = 'http://etherx.jabber.org/streams';

		id = session.streamid, from = session.host, version = '1.0', ["xml:lang"] = 'en' }):top_tag()):gsub(">", "/>")));

	(session.log or log)("debug", "Sent reply <stream:stream> to client");

	session.notopen = nil;

	-- If session.secure is *false* (not nil) then it means we /were/ encrypting

	-- since we now have a new stream header, session is secured

	if session.secure == false then

		session.secure = true;

	end

	local features = st.stanza("stream:features");

	hosts[session.host].events.fire_event("stream-features", { origin = session, features = features });

	module:fire_event("stream-features", session, features);

	send(features);

end

function stream_callbacks.streamclosed(session)

	session.log("debug", "Received </stream:stream>");

	session:close();

end

function stream_callbacks.error(session, error, data)

	if error == "no-stream" then

		session.log("debug", "Invalid opening stream header");

		session:close("invalid-namespace");

	elseif error == "parse-error" then

		(session.log or log)("debug", "Client XML parse error: %s", tostring(data));

		session:close("not-well-formed");

	elseif error == "stream-error" then

		local condition, text = "undefined-condition";

		for child in data:children() do

			if child.attr.xmlns == xmlns_xmpp_streams then

				if child.name ~= "text" then

					condition = child.name;

				else

					text = child:get_text();

				end

				if condition ~= "undefined-condition" and text then

					break;

				end

			end

		end

		text = condition .. (text and (" ("..text..")") or "");

		session.log("info", "Session closed by remote with error: %s", text);

		session:close(nil, text);

	end

end

local function handleerr(err) log("error", "Traceback[c2s]: %s: %s", tostring(err), traceback()); end

function stream_callbacks.handlestanza(session, stanza)

	stanza = session.filter("stanzas/in", stanza);

	if stanza then

		return xpcall(function () return core_process_stanza(session, stanza) end, handleerr);

	end

end

--- Session methods

local function session_close(session, reason)

	local log = session.log or log;

	if session.conn then

		if session.notopen then

			session.send("<?xml version='1.0'?>");

			session.send(st.stanza("stream:stream", default_stream_attr):top_tag());

		end

		if reason then

			if type(reason) == "string" then -- assume stream error

				log("info", "Disconnecting client, <stream:error> is: %s", reason);

				session.send(st.stanza("stream:error"):tag(reason, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' }));

			elseif type(reason) == "table" then

				if reason.condition then

					local stanza = st.stanza("stream:error"):tag(reason.condition, stream_xmlns_attr):up();

					if reason.text then

						stanza:tag("text", stream_xmlns_attr):text(reason.text):up();

					end

					if reason.extra then

						stanza:add_child(reason.extra);

					end

					log("info", "Disconnecting client, <stream:error> is: %s", tostring(stanza));

					session.send(stanza);

				elseif reason.name then -- a stanza

					log("info", "Disconnecting client, <stream:error> is: %s", tostring(reason));

					session.send(reason);

				end

			end

		end

		session.send("</stream:stream>");

		session.conn:close();

		listener.ondisconnect(session.conn, (reason and (reason.text or reason.condition)) or reason or "session closed");

	end

end

--- Port listener

function listener.onconnect(conn)

	local session = sm_new_session(conn);

	sessions[conn] = session;

	session.log("info", "Client connected");

	-- Client is using legacy SSL (otherwise mod_tls sets this flag)

	if conn:ssl() then

		session.secure = true;

	end

	if opt_keepalives then

		conn:setoption("keepalive", opt_keepalives);

	end

	session.close = session_close;

	local stream = new_xmpp_stream(session, stream_callbacks);

	session.stream = stream;

	session.notopen = true;

	function session.reset_stream()

		session.notopen = true;

		session.stream:reset();

	end

	local filter = session.filter;

	function session.data(data)

		data = parse_frame(data).data;

		module:log("debug", "Websocket received: %s %i", data, #data)

		-- COMPAT: Current client implementations send a self-closing <stream:stream>

		data = data:gsub("/>$", ">");

		data = filter("bytes/in", data);

		if data then

			local ok, err = stream:feed(data);

			if ok then return; end

			log("debug", "Received invalid XML (%s) %d bytes: %s", tostring(err), #data, data:sub(1, 300):gsub("[\r\n]+", " "):gsub("[%z\1-\31]", "_"));

			session:close("not-well-formed");

		end

	end

	function session.send(s)

		conn:write(build_frame({ FIN = true, opcode = 0x01, data = tostring(s)}));

	end

	if c2s_timeout then

		add_task(c2s_timeout, function ()

			if session.type == "c2s_unauthed" then

				session:close("connection-timeout");

			end

		end);

	end

	session.dispatch_stanza = stream_callbacks.handlestanza;

end

function listener.onincoming(conn, data)

	local session = sessions[conn];

	if session then

		session.data(data);

	else

		listener.onconnect(conn, data);

		session = sessions[conn];

		session.data(data);

	end

end

function listener.ondisconnect(conn, err)

	local session = sessions[conn];

	if session then

		(session.log or log)("info", "Client disconnected: %s", err);

		sm_destroy_session(session, err);

		sessions[conn]  = nil;

		session = nil;

	end

end

function listener.associate_session(conn, session)

	sessions[conn] = session;

end

function handle_request(event, path)

	local request, response = event.request, event.response;

	response.conn:setlistener(listener);

	response.status = "101 Switching Protocols";

	response.headers.Upgrade = "websocket";

	response.headers.Connection = "Upgrade";

	response.headers.Sec_WebSocket_Accept = base64(sha1(request.headers.sec_websocket_key .. "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));

	response.headers.Sec_WebSocket_Protocol = "xmpp";

	return "";

end

function module.add_host(module)

	module:depends("http");

	module:provides("http", {

		name = "xmpp-websocket";

		route = {

			["GET /*"] = handle_request;

		};

	});

end