-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

--

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

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

--

module:set_global(); -- Global module

local hosts = _G.hosts;

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

local sm = require "core.sessionmanager";

local sm_destroy_session = sm.destroy_session;

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

local core_process_stanza = prosody.core_process_stanza;

local st = require "util.stanza";

local logger = require "util.logger";

local log = logger.init("mod_bosh");

local initialize_filters = require "util.filters".initialize;

local math_min = math.min;

local tostring, type = tostring, type;

local traceback = debug.traceback;

local runner = require"util.async".runner;

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

local xmlns_streams = "http://etherx.jabber.org/streams";

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

local xmlns_bosh = "http://jabber.org/protocol/httpbind"; -- (hard-coded into a literal in session.send)

local stream_callbacks = {

	stream_ns = xmlns_bosh, stream_tag = "body", default_ns = "jabber:client" };

-- These constants are implicitly assumed within the code, and cannot be changed

local BOSH_HOLD = 1;

local BOSH_MAX_REQUESTS = 2;

-- The number of seconds a BOSH session should remain open with no requests

local bosh_max_inactivity = module:get_option_number("bosh_max_inactivity", 60);

-- The minimum amount of time between requests with no payload

local bosh_max_polling = module:get_option_number("bosh_max_polling", 5);

-- The maximum amount of time that the server will hold onto a request before replying

-- (the client can set this to a lower value when it connects, if it chooses)

local bosh_max_wait = module:get_option_number("bosh_max_wait", 120);

local consider_bosh_secure = module:get_option_boolean("consider_bosh_secure");

local cross_domain = module:get_option("cross_domain_bosh", false);

if cross_domain == true then cross_domain = "*"; end

if type(cross_domain) == "table" then cross_domain = table.concat(cross_domain, ", "); end

local trusted_proxies = module:get_option_set("trusted_proxies", { "127.0.0.1", "::1" })._items;

local function get_ip_from_request(request)

	local ip = request.conn:ip();

	local forwarded_for = request.headers.x_forwarded_for;

	if forwarded_for then

		forwarded_for = forwarded_for..", "..ip;

		for forwarded_ip in forwarded_for:gmatch("[^%s,]+") do

			if not trusted_proxies[forwarded_ip] then

				ip = forwarded_ip;

			end

		end

	end

	return ip;

end

local t_insert, t_remove, t_concat = table.insert, table.remove, table.concat;

-- All sessions, and sessions that have no requests open

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

-- Used to respond to idle sessions (those with waiting requests)

function on_destroy_request(request)

	log("debug", "Request destroyed: %s", tostring(request));

	local session = sessions[request.context.sid];

	if session then

		local requests = session.requests;

		for i, r in ipairs(requests) do

			if r == request then

				t_remove(requests, i);

				break;

			end

		end

		-- If this session now has no requests open, mark it as inactive

		local max_inactive = session.bosh_max_inactive;

		if max_inactive and #requests == 0 then

			if session.inactive_timer then

				session.inactive_timer:stop();

			end

			session.inactive_timer = module:add_timer(max_inactive, check_inactive, session, request.context,

				"BOSH client silent for over "..max_inactive.." seconds");

			(session.log or log)("debug", "BOSH session marked as inactive (for %ds)", max_inactive);

		end

		if session.bosh_wait_timer then

			session.bosh_wait_timer:stop();

			session.bosh_wait_timer = nil;

		end

	end

end

function check_inactive(now, session, context, reason) -- luacheck: ignore 212/now

	if not session.destroyed then

		sessions[context.sid] = nil;

		sm_destroy_session(session, reason);

	end

end

local function set_cross_domain_headers(response)

	local headers = response.headers;

	headers.access_control_allow_methods = "GET, POST, OPTIONS";

	headers.access_control_allow_headers = "Content-Type";

	headers.access_control_max_age = "7200";

	headers.access_control_allow_origin = cross_domain;

	return response;

end

function handle_OPTIONS(event)

	if cross_domain and event.request.headers.origin then

		set_cross_domain_headers(event.response);

	end

	return "";

end

function handle_POST(event)

	log("debug", "Handling new request %s: %s\n----------", tostring(event.request), tostring(event.request.body));

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

	response.on_destroy = on_destroy_request;

	local body = request.body;

	local context = { request = request, response = response, notopen = true };

	local stream = new_xmpp_stream(context, stream_callbacks);

	response.context = context;

	local headers = response.headers;

	headers.content_type = "text/xml; charset=utf-8";

	if cross_domain and request.headers.origin then

		set_cross_domain_headers(response);

	end

	-- stream:feed() calls the stream_callbacks, so all stanzas in

	-- the body are processed in this next line before it returns.

	-- In particular, the streamopened() stream callback is where

	-- much of the session logic happens, because it's where we first

	-- get to see the 'sid' of this request.

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

	if not ok then

		module:log("warn", "Error parsing BOSH payload; %s", err)

		local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

			["xmlns:stream"] = xmlns_streams, condition = "bad-request" });

		return tostring(close_reply);

	end

	-- Stanzas (if any) in the request have now been processed, and

	-- we take care of the high-level BOSH logic here, including

	-- giving a response or putting the request "on hold".

	local session = sessions[context.sid];

	if session then

		-- Session was marked as inactive, since we have

		-- a request open now, unmark it

		if session.inactive_timer and #session.requests > 0 then

			session.inactive_timer:stop();

			session.inactive_timer = nil;

		end

		if session.bosh_wait_timer then

			session.bosh_wait_timer:stop();

			session.bosh_wait_timer = nil;

		end

		local r = session.requests;

		log("debug", "Session %s has %d out of %d requests open", context.sid, #r, BOSH_HOLD);

		log("debug", "and there are %d things in the send_buffer:", #session.send_buffer);

		if #r > BOSH_HOLD then

			-- We are holding too many requests, send what's in the buffer,

			log("debug", "We are holding too many requests, so...");

			if #session.send_buffer > 0 then

				log("debug", "...sending what is in the buffer")

				session.send(t_concat(session.send_buffer));

				session.send_buffer = {};

			else

				-- or an empty response

				log("debug", "...sending an empty response");

				session.send("");

			end

		elseif #session.send_buffer > 0 then

			log("debug", "Session has data in the send buffer, will send now..");

			local resp = t_concat(session.send_buffer);

			session.send_buffer = {};

			session.send(resp);

		end

		if not response.finished then

			-- We're keeping this request open, to respond later

			log("debug", "Have nothing to say, so leaving request unanswered for now");

		end

		if session.bosh_terminate then

			session.log("debug", "Closing session with %d requests open", #session.requests);

			session:close();

			return nil;

		else

			if session.bosh_wait and #session.requests > 0 then

				session.bosh_wait_timer = module:add_timer(session.bosh_wait, after_bosh_wait, session.requests[1], session)

			end

			return true; -- Inform http server we shall reply later

		end

	elseif response.finished then

		return; -- A response has been sent already

	end

	module:log("warn", "Unable to associate request with a session (incomplete request?)");

	local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

		["xmlns:stream"] = xmlns_streams, condition = "item-not-found" });

	return tostring(close_reply) .. "\n";

end

function after_bosh_wait(now, request, session) -- luacheck: ignore 212

	if request.conn then

		session.send("");

	end

end

local function bosh_reset_stream(session) session.notopen = true; end

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

local function bosh_close_stream(session, reason)

	(session.log or log)("info", "BOSH client disconnected");

	local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

		["xmlns:stream"] = xmlns_streams });

	if reason then

		close_reply.attr.condition = "remote-stream-error";

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

			close_reply:tag("stream:error")

				:tag(reason, {xmlns = xmlns_xmpp_streams});

		elseif type(reason) == "table" then

			if reason.condition then

				close_reply:tag("stream:error")

					:tag(reason.condition, stream_xmlns_attr):up();

				if reason.text then

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

				end

				if reason.extra then

					close_reply:add_child(reason.extra);

				end

			elseif reason.name then -- a stanza

				close_reply = reason;

			end

		end

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

	end

	local response_body = tostring(close_reply);

	for _, held_request in ipairs(session.requests) do

		held_request:send(response_body);

	end

	sessions[session.sid] = nil;

	sm_destroy_session(session);

end

local runner_callbacks = { };

-- Handle the <body> tag in the request payload.

function stream_callbacks.streamopened(context, attr)

	local request, response = context.request, context.response;

	local sid = attr.sid;

	log("debug", "BOSH body open (sid: %s)", sid or "<none>");

	if not sid then

		-- New session request

		context.notopen = nil; -- Signals that we accept this opening tag

		local to_host = nameprep(attr.to);

		local rid = tonumber(attr.rid);

		local wait = tonumber(attr.wait);

		if not to_host then

			log("debug", "BOSH client tried to connect to invalid host: %s", tostring(attr.to));

			local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

				["xmlns:stream"] = xmlns_streams, condition = "improper-addressing" });

			response:send(tostring(close_reply));

			return;

		elseif not hosts[to_host] then

			-- Unknown host

			log("debug", "BOSH client tried to connect to unknown host: %s", tostring(attr.to));

			local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

				["xmlns:stream"] = xmlns_streams, condition = "host-unknown" });

			response:send(tostring(close_reply));

			return;

		end

		if not rid or (not wait and attr.wait or wait < 0 or wait % 1 ~= 0) then

			log("debug", "BOSH client sent invalid rid or wait attributes: rid=%s, wait=%s", tostring(attr.rid), tostring(attr.wait));

			local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",

				["xmlns:stream"] = xmlns_streams, condition = "bad-request" });

			response:send(tostring(close_reply));

			return;

		end

		rid = rid - 1;

		wait = math_min(wait, bosh_max_wait);

		-- New session

		sid = new_uuid();

		local session = {

			type = "c2s_unauthed", conn = request.conn, sid = sid, rid = rid, host = attr.to,

			bosh_version = attr.ver, bosh_wait = wait, streamid = sid,

			bosh_max_inactive = bosh_max_inactivity,

			requests = { }, send_buffer = {}, reset_stream = bosh_reset_stream,

			close = bosh_close_stream, dispatch_stanza = core_process_stanza, notopen = true,

			log = logger.init("bosh"..sid),	secure = consider_bosh_secure or request.secure,

			ip = get_ip_from_request(request);

		};

		sessions[sid] = session;

		session.thread = runner(function (stanza)

			session:dispatch_stanza(stanza);

		end, runner_callbacks, session);

		local filter = initialize_filters(session);

		session.log("debug", "BOSH session created for request from %s", session.ip);

		log("info", "New BOSH session, assigned it sid '%s'", sid);

		hosts[session.host].events.fire_event("bosh-session", { session = session, request = request });

		-- Send creation response

		local creating_session = true;

		local r = session.requests;

		function session.send(s)

			-- We need to ensure that outgoing stanzas have the jabber:client xmlns

			if s.attr and not s.attr.xmlns then

				s = st.clone(s);

				s.attr.xmlns = "jabber:client";

			end

			s = filter("stanzas/out", s);

			--log("debug", "Sending BOSH data: %s", tostring(s));

			if not s then return true end

			t_insert(session.send_buffer, tostring(s));

			local oldest_request = r[1];

			if oldest_request and not session.bosh_processing then

				log("debug", "We have an open request, so sending on that");

				local body_attr = { xmlns = "http://jabber.org/protocol/httpbind",

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

					type = session.bosh_terminate and "terminate" or nil;

					sid = sid;

				};

				if creating_session then

					creating_session = nil;

					body_attr.requests = tostring(BOSH_MAX_REQUESTS);

					body_attr.hold = tostring(BOSH_HOLD);

					body_attr.inactivity = tostring(bosh_max_inactivity);

					body_attr.polling = tostring(bosh_max_polling);

					body_attr.wait = tostring(session.bosh_wait);

					body_attr.authid = sid;

					body_attr.secure = "true";