-- * Metronome IM *
--
-- This file is part of the Metronome XMPP server and is released under the
-- ISC License, please see the LICENSE file in this source package for more
-- information about copyright and licensing.
--
-- As per the sublicensing clause, this file is also MIT/X11 Licensed.
-- ** Copyright (c) 2009-2013, Kim Alvefur, Marco Cirillo, Matthew Wild, Waqas Hussain

module:set_global();

local ipairs, t_concat, t_insert = ipairs, table.concat, table.insert;

local logger = require "util.logger";
local sha1 = require "util.hashes".sha1;
local st = require "util.stanza";

local jid_section = require "util.jid".section;
local new_xmpp_stream = require "util.xmppstream".new;
local uuid_gen = require "util.uuid".generate;

local log = module._log;
local fire_event = metronome.events.fire_event;

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

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.", 0);
	end
	
	local env = module.environment;
	env.connected = false;
	env.stanza_queue = module:get_option_boolean("component_stanza_queue", true) and {};

	local send;

	local function on_destroy(session, err)
		env.connected = 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("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
			module:log("error", "Second component attempted to connect, denying connection");
			session:close{ condition = "conflict", text = "Component already connected" };
			return true;
		end
		
		env.connected = true;
		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 });
		if env.stanza_queue and #env.stanza_queue > 0 then
			module:log("debug", "flushing component stanza queue...");
			for _, stanza in ipairs(env.stanza_queue) do
				log("debug", "sent queued stanza: %s\n", stanza:top_tag());
				send(stanza);
			end
			env.stanza_queue = {};
		end
		return true;
	end
	module:hook("stanza/jabber:component:accept:handshake", handle_component_auth);

	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
						event.origin.send(st.reply(stanza):tag("query", { xmlns = "http://jabber.org/protocol/disco#info" })
							:tag("identity", { category = "component", type = "generic", name = module:get_option_string("name", "Metronome") }))
						return true;
					end
				end
			end
			if env.stanza_queue then
				t_insert(env.stanza_queue, stanza);
			else
				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", "service-unavailable", "Component unavailable"));
				end
			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);
end

--- 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, data2)
	if session.destroyed then return; end
	module:log("warn", "Error processing component stream: %s", tostring(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", tostring(session.host), tostring(data));
		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

function stream_callbacks.streamopened(session, attr)
	if not module:host_is_component(attr.to) 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;
	session.send("<?xml version='1.0'?>");
	session.send(st.stanza("stream:stream", { xmlns = xmlns_component,
			["xmlns:stream"] = "http://etherx.jabber.org/streams", id = session.streamid, from = session.host }):top_tag());
end

function stream_callbacks.streamclosed(session)
	session.log("debug", "Received </stream:stream>");
	session:close();
end

function stream_callbacks.handlestanza(session, stanza)
	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
		if stanza.attr.xmlns then stanza.attr.xmlns = nil; end -- reset

		local from = stanza.attr.from;
		if from then
			if session.component_validate_from then
				local domain = jid_section(stanza.attr.from, "host");
				if domain ~= 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 <"..tostring(from)
							   .."> which is not in domain <"..tostring(session.host)..">";
					};
					return;
				end
			end
		else
			stanza.attr.from = session.host; -- COMPAT: Strictly we shouldn't allow this
		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
	return fire_event("route/process", session, stanza);
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 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", tostring(stanza));
					session.send(stanza);
				elseif reason.name then -- a stanza
					module:log("info", "Disconnecting component, <stream:error> is: %s", tostring(reason));
					session.send(reason);
				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(conn):match("[a-f0-9]+$");
	session.log = logger.init(conn_name);
	session.close = session_close;
	
	session.log("info", "Incoming Jabber component connection");
	
	local stream = new_xmpp_stream(session, stream_callbacks);
	session.stream = stream;
	
	session.notopen = true;
	
	function session.reset_stream()
		session.notopen = true;
		session.stream:reset();
	end

	function session.data(conn, data)
		local ok, err = stream:feed(data);
		if ok then return; end
		module:log("debug", "Received invalid XML (%s) %d bytes: %s", tostring(err), #data, data:sub(1, 300):gsub("[\r\n]+", " "):gsub("[%z\1-\31]", "_"));
		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)", tostring(session.host), tostring(err));
		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;
		session = nil;
	end
end

module:add_item("net-provider", {
	name = "component",
	listener = listener,
	default_port = 5347,
	multiplex = {
		pattern = "^<.*:stream.*%sxmlns%s*=%s*(['\"])jabber:component%1.*>"
	}
});

module:add_item("net-provider", {
	name = "component_secure",
	listener = listener,
	encryption = "ssl"
});
