-- 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 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 statsmanager = require "core.statsmanager";

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 async = require "util.async";

local runner = async.runner;

local tostring, type = tostring, type;

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

local log = module._log;

local c2s_timeout = module:get_option_number("c2s_timeout", 300);

local stream_close_timeout = module:get_option_number("c2s_close_timeout", 5);

local opt_keepalives = module:get_option_boolean("c2s_tcp_keepalives", module:get_option_boolean("tcp_keepalives", true));

local stanza_size_limit = module:get_option_number("c2s_stanza_size_limit", 1024*256);

local measure_connections = module:metric("gauge", "connections", "", "Established c2s connections", {"host", "type", "ip_family"});

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

local core_process_stanza = prosody.core_process_stanza;

local hosts = prosody.hosts;

local stream_callbacks = { default_ns = "jabber:client" };

local listener = {};

local runner_callbacks = {};

local m_tls_params = module:metric(

	"counter", "encrypted", "",

	"Encrypted connections",

	{"protocol"; "cipher"}

);

module:hook("stats-update", function ()

	-- for push backends, avoid sending out updates for each increment of

	-- the metric below.

	statsmanager.cork()

	measure_connections:clear()

	for _, session in pairs(sessions) do

		local host = session.host or ""

		local type_ = session.type or "other"

		-- we want to expose both v4 and v6 counters in all cases to make

		-- queries smoother

		local is_ipv6 = session.ip and session.ip:match(":") and 1 or 0

		local is_ipv4 = 1 - is_ipv6

		measure_connections:with_labels(host, type_, "ipv4"):add(is_ipv4)

		measure_connections:with_labels(host, type_, "ipv6"):add(is_ipv6)

	end

	statsmanager.uncork()

end);

--- Stream events handlers

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

function stream_callbacks.streamopened(session, attr)

	-- run _streamopened in async context

	session.thread:run({ stream = "opened", attr = attr });

end

function stream_callbacks._streamopened(session, attr)

	local send = session.send;

	if not attr.to then

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

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

		return;

	end

	local host = nameprep(attr.to);

	if not host then

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

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

		return;

	end

	if not session.host then

		session.host = host;

	elseif session.host ~= host then

		session:close{ condition = "not-authorized",

			text = "The 'to' attribute must remain the same across stream restarts" };

		return;

	end

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

	session.streamid = uuid_generate();

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

	if not hosts[session.host] or not hosts[session.host].modules.c2s then

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

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

		return;

	end

	session:open_stream(host, attr.from);

	-- Opening the stream can cause the stream to be closed

	if session.destroyed then return end

	(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;

		session.encrypted = true;

		local info = session.conn:ssl_info();

		if type(info) == "table" then

			(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);

			session.compressed = info.compression;

			m_tls_params:with_labels(info.protocol, info.cipher):add(1)

		else

			(session.log or log)("info", "Stream encrypted");

		end

	end

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

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

	if features.tags[1] or session.full_jid then

		send(features);

	else

		if session.secure then

			-- Here SASL should be offered

			(session.log or log)("warn", "No stream features to offer on secure session. Check authentication settings.");

		else

			-- Normally STARTTLS would be offered

			(session.log or log)("warn", "No stream features to offer on insecure session. Check encryption and security settings.");

		end

		session:close{ condition = "undefined-condition", text = "No stream features to proceed with" };

	end

end

function stream_callbacks.streamclosed(session, attr)

	-- run _streamclosed in async context

	session.thread:run({ stream = "closed", attr = attr });

end

function stream_callbacks._streamclosed(session)

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

	session:close(false);

end

function stream_callbacks.error(session, error, data)

	if error == "no-stream" then

		session.log("debug", "Invalid opening stream header (%s)", (data:gsub("^([^\1]+)\1", "{%1}")));

		session:close("invalid-namespace");

	elseif error == "parse-error" then

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

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

	elseif error == "stream-error" then

		local condition, text = "undefined-condition";

		for child in data:childtags(nil, xmlns_xmpp_streams) do

			if child.name ~= "text" then

				condition = child.name;

			else

				text = child:get_text();

			end

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

				break;

			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

function stream_callbacks.handlestanza(session, stanza)

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

	session.thread:run(stanza);

end

--- Session methods

local function session_close(session, reason)

	local log = session.log or log;

	local close_event_payload = { session = session, reason = reason };

	module:context(session.host):fire_event("pre-session-close", close_event_payload);

	reason = close_event_payload.reason;

	if session.conn then

		if session.notopen then

			session:open_stream();

		end

		if reason then -- nil == no err, initiated by us, false == initiated by client

			local stream_error = st.stanza("stream:error");

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

				stream_error:tag(reason, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' });

			elseif st.is_stanza(reason) then

				stream_error = reason;

			elseif type(reason) == "table" then

				if reason.condition then

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

					if reason.text then

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

					end

					if reason.extra then

						stream_error:add_child(reason.extra);

					end

				end

			end

			stream_error = tostring(stream_error);

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

			session.send(stream_error);

		end

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

		function session.send() return false; end

		local reason_text = (reason and (reason.name or reason.text or reason.condition)) or reason;

		session.log("debug", "c2s stream for %s closed: %s", session.full_jid or session.ip or "<unknown>", reason_text or "session closed");

		-- Authenticated incoming stream may still be sending us stanzas, so wait for </stream:stream> from remote

		local conn = session.conn;

		if reason_text == nil and not session.notopen and session.type == "c2s" then

			-- Grace time to process data from authenticated cleanly-closed stream

			add_task(stream_close_timeout, function ()

				if not session.destroyed then

					session.log("warn", "Failed to receive a stream close response, closing connection anyway...");

					sm_destroy_session(session, reason_text);

					if conn then conn:close(); end

				end

			end);

		else

			sm_destroy_session(session, reason_text);

			if conn then conn:close(); end

		end

	else

		local reason_text = (reason and (reason.name or reason.text or reason.condition)) or reason;

		sm_destroy_session(session, reason_text);

	end

end

-- Close all user sessions with the specified reason. If leave_resource is

-- true, the resource named by event.resource will not be closed.

local function disconnect_user_sessions(reason, leave_resource)

	return function (event)

		local username, host, resource = event.username, event.host, event.resource;

		local user = hosts[host].sessions[username];

		if user and user.sessions then

			for r, session in pairs(user.sessions) do

				if not leave_resource or r ~= resource then

					session:close(reason);

				end

			end

		end

	end

end

module:hook_global("user-password-changed", disconnect_user_sessions({ condition = "reset", text = "Password changed" }, true), 200);

module:hook_global("user-role-changed", disconnect_user_sessions({ condition = "reset", text = "Role changed" }), 200);

module:hook_global("user-deleted", disconnect_user_sessions({ condition = "not-authorized", text = "Account deleted" }), 200);

module:hook_global("c2s-session-updated", function (event)

	sessions[event.session.conn] = event.session;

	local replaced_conn = event.replaced_conn;

	if replaced_conn then

		sessions[replaced_conn] = nil;

	end

end);

function runner_callbacks:ready()

	if self.data.conn then

		self.data.conn:resume();

	else

		(self.data.log or log)("debug", "Session has no connection to resume");

	end

end

function runner_callbacks:waiting()

	if self.data.conn then

		self.data.conn:pause();

	else

		(self.data.log or log)("debug", "Session has no connection to pause while waiting");

	end

end

function runner_callbacks:error(err)

	(self.data.log or log)("error", "Traceback[c2s]: %s", err);

end

--- Port listener

function listener.onconnect(conn)

	local session = sm_new_session(conn);

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

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

	if conn:ssl() then

		session.secure = true;

		session.encrypted = true;

		-- Check if TLS compression is used

		local info = conn:ssl_info();

		if type(info) == "table" then

			(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);

			session.compressed = info.compression;

			m_tls_params:with_labels(info.protocol, info.cipher):add(1)

		else

			(session.log or log)("info", "Stream encrypted");

		end

	end

	if opt_keepalives then

		conn:setoption("keepalive", opt_keepalives);

	end

	session.close = session_close;

	local stream = new_xmpp_stream(session, stream_callbacks, stanza_size_limit);

	session.stream = stream;

	session.notopen = true;

	function session.reset_stream()

		session.notopen = true;

		session.stream:reset();

	end

	session.thread = runner(function (stanza)

		if st.is_stanza(stanza) then

			core_process_stanza(session, stanza);

		elseif stanza.stream == "opened" then

			stream_callbacks._streamopened(session, stanza.attr);

		elseif stanza.stream == "closed" then

			stream_callbacks._streamclosed(session, stanza.attr);

		end

	end, runner_callbacks, session);

	local filter = session.filter;

	function session.data(data)

		-- Parse the data, which will store stanzas in session.pending_stanzas

		if data then

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

			if data then

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

				if not ok then

					log("debug", "Received invalid XML (%s) %d bytes: %q", err, #data, data:sub(1, 300));

					if err == "stanza-too-large" then

						session:close({

							condition = "policy-violation",

							text = "XML stanza is too big",

							extra = st.stanza("stanza-too-big", { xmlns = 'urn:xmpp:errors' }),

						});

					else

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

					end

				end

			end

		end

	end