-- 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 t_concat = table.concat;

local tostring, type = tostring, type;

local xpcall = require "prosody.util.xpcall".xpcall;

local traceback = debug.traceback;

local logger = require "prosody.util.logger";

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

local st = require "prosody.util.stanza";

local jid_host = require "prosody.util.jid".host;

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

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

local core_process_stanza = prosody.core_process_stanza;

local hosts = prosody.hosts;

local log = module._log;

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

local stanza_size_limit = module:get_option_integer("component_stanza_size_limit",

	module:get_option_integer("s2s_stanza_size_limit", 1024 * 512, 10000), 10000);

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

local function keepalive(event)

	local session = event.session;

	if not session.notopen then

		return event.session.send(' ');

	end

end

function module.add_host(module)

	if module:get_host_type() ~= "component" then

		error("Don't load mod_component manually, it should be for a component, please see https://prosody.im/doc/components", 0);

	end

	local env = module.environment;

	env.connected = false;

	env.session = false;

	local send;

	local function on_destroy(session, err) --luacheck: ignore 212/err

		module:set_status("warn", err and ("Disconnected: "..err) or "Disconnected");

		env.connected = false;

		env.session = false;

		send = nil;

		session.on_destroy = nil;

	end

	-- Handle authentication attempts by component

	local function handle_component_auth(event)

		local session, stanza = event.origin, event.stanza;

		if session.type ~= "component_unauthed" then return; end

		if (not session.host) or #stanza.tags > 0 then

			(session.log or log)("warn", "Invalid component handshake for host: %s", session.host);

			session:close("not-authorized");

			return true;

		end

		local secret = module:get_option_string("component_secret");

		if not secret then

			(session.log or log)("warn", "Component attempted to identify as %s, but component_secret is not set", session.host);

			session:close("not-authorized");

			return true;

		end

		local supplied_token = t_concat(stanza);

		local calculated_token = sha1(session.streamid..secret, true);

		if supplied_token:lower() ~= calculated_token:lower() then

			module:log("info", "Component authentication failed for %s", session.host);

			session:close{ condition = "not-authorized", text = "Given token does not match calculated token" };

			return true;

		end

		if env.connected then

			local policy = module:get_option_enum("component_conflict_resolve", "kick_new", "kick_old");

			if policy == "kick_old" then

				env.session:close{ condition = "conflict", text = "Replaced by a new connection" };

			else -- kick_new

				module:log("error", "Second component attempted to connect, denying connection");

				session:close{ condition = "conflict", text = "Component already connected" };

				return true;

			end

		end

		env.connected = true;

		env.session = session;

		send = session.send;

		session.on_destroy = on_destroy;

		session.component_validate_from = module:get_option_boolean("validate_from_addresses", true);

		session.type = "component";

		module:log("info", "External component successfully authenticated");

		session.send(st.stanza("handshake"));

		module:fire_event("component-authenticated", { session = session });

		module:set_status("info", "Connected");

		return true;

	end

	module:hook("stanza/jabber:component:accept:handshake", handle_component_auth, -1);

	-- Handle stanzas addressed to this component

	local function handle_stanza(event)

		local stanza = event.stanza;

		if send then

			stanza.attr.xmlns = nil;

			send(stanza);

		else

			if stanza.name == "iq" and stanza.attr.type == "get" and stanza.attr.to == module.host then

				local query = stanza.tags[1];

				local node = query.attr.node;

				if query.name == "query" and query.attr.xmlns == "http://jabber.org/protocol/disco#info" and (not node or node == "") then

					local name = module:get_option_string("name");

					if name then

						local reply = st.reply(stanza):tag("query", { xmlns = "http://jabber.org/protocol/disco#info" })

							:tag("identity", { category = "component", type = "generic", name = module:get_option_string("name", "Prosody") }):up()

							:tag("feature", { var = "http://jabber.org/protocol/disco#info" }):up();

						event.origin.send(reply);

						return true;

					end

				end

			end

			module:log("warn", "Component not connected, bouncing error for: %s", stanza:top_tag());

			if stanza.attr.type ~= "error" and stanza.attr.type ~= "result" then

				event.origin.send(st.error_reply(stanza, "wait", "remote-server-timeout", "Component unavailable", module.host)

					:tag("not-connected", { xmlns = "xmpp:prosody.im/protocol/component" }));

			end

		end

		return true;

	end

	module:hook("iq/bare", handle_stanza, -1);

	module:hook("message/bare", handle_stanza, -1);

	module:hook("presence/bare", handle_stanza, -1);

	module:hook("iq/full", handle_stanza, -1);

	module:hook("message/full", handle_stanza, -1);

	module:hook("presence/full", handle_stanza, -1);

	module:hook("iq/host", handle_stanza, -1);

	module:hook("message/host", handle_stanza, -1);

	module:hook("presence/host", handle_stanza, -1);

	module:hook("component-read-timeout", keepalive, -1);

end

module:hook("component-read-timeout", keepalive, -1);

--- Network and stream part ---

local xmlns_component = 'jabber:component:accept';

local listener = {};

--- Callbacks/data for xmppstream to handle streams for us ---

local stream_callbacks = { default_ns = xmlns_component };

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

function stream_callbacks.error(session, error, data)

	if session.destroyed then return; end

	module:log("warn", "Error processing component stream: %s", error);

	if error == "no-stream" then

		session:close("invalid-namespace");

	elseif error == "parse-error" then

		session.log("warn", "External component %s XML parse error: %s", session.host, 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.streamopened(session, attr)

	if not attr.to then

		session:close{ condition = "improper-addressing", text = "A 'to' attribute is required on stream headers" };

		return;

	end

	if not hosts[attr.to] or not hosts[attr.to].modules.component then

		session:close{ condition = "host-unknown", text = tostring(attr.to).." does not match any configured external components" };

		return;

	end

	session.host = attr.to;

	session.streamid = uuid_gen();

	session.notopen = nil;

	-- Return stream header

	session:open_stream();

end

function stream_callbacks.streamclosed(session)

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

	session:close();

end

local function handleerr(err) log("error", "Traceback[component]: %s", traceback(err, 2)); end

function stream_callbacks.handlestanza(session, stanza)

	-- Namespaces are icky.

	if not stanza.attr.xmlns and stanza.name == "handshake" then

		stanza.attr.xmlns = xmlns_component;

	end

	if not stanza.attr.xmlns or stanza.attr.xmlns == "jabber:client" then

		local from = stanza.attr.from;

		if session.component_validate_from then

			if not from or (jid_host(from) ~= session.host) then

				-- Return error

				session.log("warn", "Component sent stanza with missing or invalid 'from' address");

				session:close{

					condition = "invalid-from";

					text = "Component tried to send from address <"..(from or "< [missing 'from' attribute] >")

						   .."> which is not in domain <"..tostring(session.host)..">";

				};

				return;

			end

		elseif not from then

			stanza.attr.from = session.host;

		end

		if not stanza.attr.to then

			session.log("warn", "Rejecting stanza with no 'to' address");

			session.send(st.error_reply(stanza, "modify", "bad-request", "Components MUST specify a 'to' address on stanzas"));

			return;

		end

	end

	if stanza then

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

	end

end

--- Closing a component connection

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)

	if session.destroyed then return; end

	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

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

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

			elseif st.is_stanza(reason) then

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

				session.send(reason);

			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

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

					session.send(stanza);

				end

			end

		end

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

		session.conn:close();

		listener.ondisconnect(session.conn, "stream error");

	end

end

--- Component connlistener

function listener.onconnect(conn)

	local _send = conn.write;

	local session = { type = "component_unauthed", conn = conn, send = function (data) return _send(conn, tostring(data)); end };

	-- Logging functions --

	local conn_name = "jcp"..tostring(session):match("[a-f0-9]+$");

	session.log = logger.init(conn_name);

	session.close = session_close;

	if opt_keepalives then

		conn:setoption("keepalive", opt_keepalives);

	end

	session.log("info", "Incoming Jabber component connection");

	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

	function session.data(_, data)

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

		if ok then return; end

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

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

	end

	session.dispatch_stanza = stream_callbacks.handlestanza;

	sessions[conn] = session;

end

function listener.onincoming(conn, data)

	local session = sessions[conn];

	session.data(conn, data);

end

function listener.ondisconnect(conn, err)

	local session = sessions[conn];

	if session then

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

		if session.host then

			module:context(session.host):fire_event("component-disconnected", { session = session, reason = err });

		end

		if session.on_destroy then session:on_destroy(err); end

		sessions[conn] = nil;

		for k in pairs(session) do

			if k ~= "log" and k ~= "close" then

				session[k] = nil;

			end

		end

		session.destroyed = true;

	end

end

function listener.ondetach(conn)

	sessions[conn] = nil;

end

function listener.onreadtimeout(conn)

	local session = sessions[conn];

	if session then

		return (hosts[session.host] or prosody).events.fire_event("component-read-timeout", { session = session });