-- 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();

local prosody = prosody;

local hosts = prosody.hosts;

local core_process_stanza = core_process_stanza;

local tostring, type = tostring, type;

local t_insert = table.insert;

local xpcall, traceback = xpcall, debug.traceback;

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

local st = require "util.stanza";

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

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

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

local s2s_new_incoming = require "core.s2smanager".new_incoming;

local s2s_new_outgoing = require "core.s2smanager".new_outgoing;

local s2s_destroy_session = require "core.s2smanager".destroy_session;

local s2s_mark_connected = require "core.s2smanager".mark_connected;

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

local cert_verify_identity = require "util.x509".verify_identity;

local s2sout = module:require("s2sout");

local connect_timeout = module:get_option_number("s2s_timeout", 60);

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

local log = module._log;

--- Handle stanzas to remote domains

local bouncy_stanzas = { message = true, presence = true, iq = true };

local function bounce_sendq(session, reason)

	local sendq = session.sendq;

	if not sendq then return; end

	session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));

	local dummy = {

		type = "s2sin";

		send = function(s)

			(session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", traceback());

		end;

		dummy = true;

	};

	for i, data in ipairs(sendq) do

		local reply = data[2];

		if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then

			reply.attr.type = "error";

			reply:tag("error", {type = "cancel"})

				:tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();

			if reason then

				reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"})

					:text("Server-to-server connection failed: "..reason):up();

			end

			core_process_stanza(dummy, reply);

		end

		sendq[i] = nil;

	end

	session.sendq = nil;

end

-- Handles stanzas to existing s2s sessions

function route_to_existing_session(event)

	local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;

	if not hosts[from_host] then

		log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);

		return false;

	end

	local host = hosts[from_host].s2sout[to_host];

	if host then

		-- We have a connection to this host already

		if host.type == "s2sout_unauthed" and (stanza.name ~= "db:verify" or not host.dialback_key) then

			(host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);

			-- Queue stanza until we are able to send it

			if host.sendq then t_insert(host.sendq, {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)});

			else host.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} }; end

			host.log("debug", "stanza [%s] queued ", stanza.name);

			return true;

		elseif host.type == "local" or host.type == "component" then

			log("error", "Trying to send a stanza to ourselves??")

			log("error", "Traceback: %s", traceback());

			log("error", "Stanza: %s", tostring(stanza));

			return false;

		else

			(host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);

			-- FIXME

			if host.from_host ~= from_host then

				log("error", "WARNING! This might, possibly, be a bug, but it might not...");

				log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));

			end

		end

	end

end

-- Create a new outgoing session for a stanza

function route_to_new_session(event)

	local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;

	log("debug", "opening a new outgoing connection for this stanza");

	local host_session = s2s_new_outgoing(from_host, to_host);

	-- Store in buffer

	host_session.bounce_sendq = bounce_sendq;

	host_session.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} };

	log("debug", "stanza [%s] queued until connection complete", tostring(stanza.name));

	s2sout.initiate_connection(host_session);

	if (not host_session.connecting) and (not host_session.conn) then

		log("warn", "Connection to %s failed already, destroying session...", to_host);

		s2s_destroy_session(host_session, "Connection failed");

		return false;

	end

	return true;

end

function module.add_host(module)

	if module:get_option_boolean("disallow_s2s", false) then

		module:log("warn", "The 'disallow_s2s' config option is deprecated, please see http://prosody.im/doc/s2s#disabling");

		return nil, "This host has disallow_s2s set";

	end

	module:hook("route/remote", route_to_existing_session, 200);

	module:hook("route/remote", route_to_new_session, 100);

end

--- Helper to check that a session peer's certificate is valid

local function check_cert_status(session)

	local conn = session.conn:socket()

	local cert

	if conn.getpeercertificate then

		cert = conn:getpeercertificate()

	end

	if cert then

		local chain_valid, errors = conn:getpeerverification()

		-- Is there any interest in printing out all/the number of errors here?

		if not chain_valid then

			(session.log or log)("debug", "certificate chain validation result: invalid");

			for depth, t in ipairs(errors) do

				(session.log or log)("debug", "certificate error(s) at depth %d: %s", depth-1, table.concat(t, ", "))

			end

			session.cert_chain_status = "invalid";

		else

			(session.log or log)("debug", "certificate chain validation result: valid");

			session.cert_chain_status = "valid";

			local host = session.direction == "incoming" and session.from_host or session.to_host

			-- We'll go ahead and verify the asserted identity if the

			-- connecting server specified one.

			if host then

				if cert_verify_identity(host, "xmpp-server", cert) then

					session.cert_identity_status = "valid"

				else

					session.cert_identity_status = "invalid"

				end

			end

		end

	end

end

--- XMPP stream event handlers

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

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

function stream_callbacks.streamopened(session, attr)

	local send = session.sends2s;

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

	-- TODO: Rename session.secure to session.encrypted

	if session.secure == false then

		session.secure = true;

	end

	if session.direction == "incoming" then

		-- Send a reply stream header

		-- Validate to/from

		local to, from = nameprep(attr.to), nameprep(attr.from);

		if not to and attr.to then -- COMPAT: Some servers do not reliably set 'to' (especially on stream restarts)

			session:close({ condition = "improper-addressing", text = "Invalid 'to' address" });

			return;

		end

		if not from and attr.from then -- COMPAT: Some servers do not reliably set 'from' (especially on stream restarts)

			session:close({ condition = "improper-addressing", text = "Invalid 'from' address" });

			return;

		end

		-- Set session.[from/to]_host if they have not been set already and if

		-- this session isn't already authenticated

		if session.type == "s2sin_unauthed" and from and not session.from_host then

			session.from_host = from;

		elseif from ~= session.from_host then

			session:close({ condition = "improper-addressing", text = "New stream 'from' attribute does not match original" });

			return;

		end

		if session.type == "s2sin_unauthed" and to and not session.to_host then

			session.to_host = to;

		elseif to ~= session.to_host then

			session:close({ condition = "improper-addressing", text = "New stream 'to' attribute does not match original" });

			return;

		end

		-- For convenience we'll put the sanitised values into these variables

		to, from = session.to_host, session.from_host;

		session.streamid = uuid_gen();

		(session.log or log)("debug", "Incoming s2s received %s", st.stanza("stream:stream", attr):top_tag());

		if to then

			if not hosts[to] then

				-- Attempting to connect to a host we don't serve

				session:close({

					condition = "host-unknown";

					text = "This host does not serve "..to

				});

				return;

			elseif not hosts[to].modules.s2s then

				-- Attempting to connect to a host that disallows s2s

				session:close({

					condition = "policy-violation";

					text = "Server-to-server communication is disabled for this host";

				});

				return;

			end

		end

		if session.secure and not session.cert_chain_status then check_cert_status(session); end

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

		send(st.stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',

				["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=to, to=from, version=(session.version > 0 and "1.0" or nil) }):top_tag());

		if session.version >= 1.0 then

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

			if to then

				hosts[to].events.fire_event("s2s-stream-features", { origin = session, features = features });

			else

				(session.log or log)("warn", "No 'to' on stream header from %s means we can't offer any features", from or "unknown host");

			end

			log("debug", "Sending stream features: %s", tostring(features));

			send(features);

		end

	elseif session.direction == "outgoing" then

		-- If we are just using the connection for verifying dialback keys, we won't try and auth it

		if not attr.id then error("stream response did not give us a streamid!!!"); end

		session.streamid = attr.id;

		if session.secure and not session.cert_chain_status then check_cert_status(session); end

		-- Send unauthed buffer

		-- (stanzas which are fine to send before dialback)

		-- Note that this is *not* the stanza queue (which

		-- we can only send if auth succeeds) :)

		local send_buffer = session.send_buffer;

		if send_buffer and #send_buffer > 0 then

			log("debug", "Sending s2s send_buffer now...");

			for i, data in ipairs(send_buffer) do

				session.sends2s(tostring(data));

				send_buffer[i] = nil;

			end

		end

		session.send_buffer = nil;

		-- If server is pre-1.0, don't wait for features, just do dialback

		if session.version < 1.0 then

			if not session.dialback_verifying then

				hosts[session.from_host].events.fire_event("s2s-authenticate-legacy", { origin = session });

			else

				s2s_mark_connected(session);

			end

		end

	end

	session.notopen = nil;

end

function stream_callbacks.streamclosed(session)

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

	session:close();

end

function stream_callbacks.streamdisconnected(session, err)

	if err and err ~= "closed" and session.direction == "outgoing" and session.notopen then

		(session.log or log)("debug", "s2s connection attempt failed: %s", err);

		if s2sout.attempt_connection(session, err) then

			(session.log or log)("debug", "...so we're going to try another target");

			return true; -- Session lives for now

		end

	end

	(session.log or log)("info", "s2s disconnected: %s->%s (%s)", tostring(session.from_host), tostring(session.to_host), tostring(err or "closed"));

	s2s_destroy_session(session, err);

end

function stream_callbacks.error(session, error, data)

	if error == "no-stream" then

		session:close("invalid-namespace");

	elseif error == "parse-error" then

		session.log("debug", "Server-to-server XML parse error: %s", tostring(error));

		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[s2s]: %s: %s", tostring(err), traceback()); end

function stream_callbacks.handlestanza(session, stanza)

	if stanza.attr.xmlns == "jabber:client" then --COMPAT: Prosody pre-0.6.2 may send jabber:client

		stanza.attr.xmlns = nil;

	end

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

	if stanza then

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

	end

end

local listener = {};

--- Session methods

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 = "" };

local function session_close(session, reason, remote_reason)

	local log = session.log or log;

	if session.conn then

		if session.notopen then

			session.sends2s("<?xml version='1.0'?>");

			session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());

		end

		if reason then

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

				log("info", "Disconnecting %s[%s], <stream:error> is: %s", session.host or "(unknown host)", session.type, reason);

				session.sends2s(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 %s[%s], <stream:error> is: %s", session.host or "(unknown host)", session.type, tostring(stanza));

					session.sends2s(stanza);