-- Bidirectional Server-to-Server Connections

-- http://xmpp.org/extensions/xep-0288.html

-- Copyright (C) 2013 Kim Alvefur

--

-- This file is MIT/X11 licensed.

--

local add_filter = require "util.filters".add_filter;

local st = require "util.stanza";

local jid_split = require"util.jid".prepped_split;

local core_process_stanza = prosody.core_process_stanza;

local traceback = debug.traceback;

local hosts = hosts;

local xmlns_bidi_feature = "urn:xmpp:features:bidi"

local xmlns_bidi = "urn:xmpp:bidi";

local secure_only = module:get_option_boolean("secure_bidi_only", true);

local bidi_sessions = module:shared"sessions";

local function handleerr(err) log("error", "Traceback[s2s]: %s: %s", tostring(err), traceback()); end

local function 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 function new_bidi(origin)

	if origin.type == "s2sin" then -- then we create an "outgoing" bidirectional session

		local conflicting_session = hosts[origin.to_host].s2sout[origin.from_host]

		if conflicting_session then

			conflicting_session.log("info", "We already have an outgoing connection to %s, closing it...", origin.from_host);

			conflicting_session:close{ condition = "conflict", text = "Replaced by bidirectional stream" }

		end

		bidi_sessions[origin.from_host] = origin;

	elseif origin.type == "s2sout" then -- handle incoming stanzas correctly

		local bidi_session = {

			type = "s2sin"; direction = "incoming";

			is_bidi = true; orig_session = origin;

			to_host = origin.from_host;

			from_host = origin.to_host;

			hosts = {};

		}

		origin.bidi_session = bidi_session;

		setmetatable(bidi_session, { __index = origin });

		module:fire_event("s2s-authenticated", { session = bidi_session, host = origin.to_host });

		add_filter(origin, "stanzas/in", function(stanza)

			if stanza.attr.xmlns ~= nil then return stanza end

			local _, host = jid_split(stanza.attr.from);

			if host ~= remote_host then return stanza end

			handlestanza(bidi_session, stanza);

		end, 1);

	end

end

module:hook("route/remote", function(event)

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

	if from_host ~= module.host then return end

	local to_session = bidi_sessions[to_host]

	if not to_session then return end

	return to_session.sends2s(stanza);

end, -2);

-- Incoming s2s

module:hook("s2s-stream-features", function(event)

	local origin, features = event.origin, event.features;

	if not origin.is_bidi and not hosts[module.host].s2sout[origin.from_host]

	and (not secure_only or origin.cert_chain_status == "valid"

	and origin.cert_identity_status == "valid") then

		module:log("debug", "Announcing support for bidirectional streams");

		features:tag("bidi", { xmlns = xmlns_bidi_feature }):up();

	end

end);

module:hook("stanza/urn:xmpp:bidi:bidi", function(event)

	local origin = event.session or event.origin;

	if not origin.is_bidi and not origin.bidi_session

	and (not secure_only or origin.cert_chain_status == "valid"

	and origin.cert_identity_status == "valid") then

		module:log("debug", "%s requested bidirectional stream", origin.from_host);

		origin.do_bidi = true;

		return true;

	end

end);

-- Outgoing s2s

module:hook("stanza/http://etherx.jabber.org/streams:features", function(event)

	local origin = event.session or event.origin;

	if not ( origin.bidi_session or origin.is_bidi or origin.do_bidi)

	and event.stanza:get_child("bidi", xmlns_bidi_feature)

	and (not secure_only or origin.cert_chain_status == "valid"

	and origin.cert_identity_status == "valid") then

		module:log("debug", "%s supports bidirectional streams", origin.to_host);

		origin.sends2s(st.stanza("bidi", { xmlns = xmlns_bidi }));

		origin.do_bidi = true;

	end

end, 160);

function enable_bidi(event)

	local session = event.session;

	if session.do_bidi and not ( session.is_bidi or session.bidi_session ) then

		session.do_bidi = nil;

		new_bidi(session);

	end

end

module:hook("s2sin-established", enable_bidi);

module:hook("s2sout-established", enable_bidi);

function disable_bidi(event)

	local session = event.session;

	if session.type == "s2sin" then

		bidi_sessions[session.from_host] = nil;

	end

end

module:hook("s2sin-destroyed", disable_bidi);

module:hook("s2sout-destroyed", disable_bidi);