-- Prosody IM v0.4

-- Copyright (C) 2008-2009 Matthew Wild

-- Copyright (C) 2008-2009 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local st = require "util.stanza";

local sm_bind_resource = require "core.sessionmanager".bind_resource;

local base64 = require "util.encodings".base64;

local usermanager_validate_credentials = require "core.usermanager".validate_credentials;

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

local tostring = tostring;

local jid_split = require "util.jid".split

local md5 = require "util.hashes".md5;

local config = require "core.configmanager";

local log = require "util.logger".init("mod_saslauth");

local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';

local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';

local xmlns_stanzas ='urn:ietf:params:xml:ns:xmpp-stanzas';

local new_sasl = require "util.sasl".new;

local function build_reply(status, ret, err_msg)

	local reply = st.stanza(status, {xmlns = xmlns_sasl});

	if status == "challenge" then

		log("debug", ret or "");

		reply:text(base64.encode(ret or ""));

	elseif status == "failure" then

		reply:tag(ret):up();

		if err_msg then reply:tag("text"):text(err_msg); end

	elseif status == "success" then

		log("debug", ret or "");

		reply:text(base64.encode(ret or ""));

	else

		error("Unknown sasl status: "..status);

	end

	return reply;

end

local function handle_status(session, status)

	if status == "failure" then

		session.sasl_handler = nil;

	elseif status == "success" then

		if not session.sasl_handler.username then error("SASL succeeded but we didn't get a username!"); end -- TODO move this to sessionmanager

		sessionmanager.make_authenticated(session, session.sasl_handler.username);

		session.sasl_handler = nil;

		session:reset_stream();

	end

end

local function password_callback(node, host, mechanism, decoder)

	local password = (datamanager.load(node, host, "accounts") or {}).password; -- FIXME handle hashed passwords

	local func = function(x) return x; end;

	if password then

		if mechanism == "PLAIN" then

			return func, password;

		elseif mechanism == "DIGEST-MD5" then

			if decoder then node, host, password = decoder(node), decoder(host), decoder(password); end

			return func, md5(node..":"..host..":"..password);

		end

	end

	return func, nil;

end

local function sasl_handler(session, stanza)

	if stanza.name == "auth" then

		-- FIXME ignoring duplicates because ejabberd does

		if config.get(session.host or "*", "core", "anonymous_login") and stanza.attr.mechanism ~= "ANONYMOUS" then

			return session.send(build_reply("failure", "invalid-mechanism"));

		elseif stanza.attr.mechanism == "ANONYMOUS" then

			return session.send(build_reply("failure", "mechanism-too-weak"));

		end

		session.sasl_handler = new_sasl(stanza.attr.mechanism, session.host, password_callback);

		if not session.sasl_handler then

			return session.send(build_reply("failure", "invalid-mechanism"));

		end

	elseif not session.sasl_handler then

		return; -- FIXME ignoring out of order stanzas because ejabberd does

	end

	local text = stanza[1];

	if text then

		text = base64.decode(text);

		log("debug", text);

		if not text then

			session.sasl_handler = nil;

			session.send(build_reply("failure", "incorrect-encoding"));

			return;

		end

	end

	local status, ret, err_msg = session.sasl_handler:feed(text);

	handle_status(session, status);

	local s = build_reply(status, ret, err_msg); 

	log("debug", "sasl reply: "..tostring(s));

	session.send(s);

end

module:add_handler("c2s_unauthed", "auth", xmlns_sasl, sasl_handler);

module:add_handler("c2s_unauthed", "abort", xmlns_sasl, sasl_handler);

module:add_handler("c2s_unauthed", "response", xmlns_sasl, sasl_handler);

local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };

local bind_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-bind' };

local xmpp_session_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-session' };

module:add_event_hook("stream-features", 

		function (session, features)												

			if not session.username then

				features:tag("mechanisms", mechanisms_attr);

				-- TODO: Provide PLAIN only if TLS is active, this is a SHOULD from the introduction of RFC 4616. This behavior could be overridden via configuration but will issuing a warning or so.

					if config.get(session.host or "*", "core", "anonymous_login") then

						features:tag("mechanism"):text("ANONYMOUS"):up();

					else

						features:tag("mechanism"):text("DIGEST-MD5"):up();

						features:tag("mechanism"):text("PLAIN"):up();

					end

				features:up();

			else

				features:tag("bind", bind_attr):tag("required"):up():up();

				features:tag("session", xmpp_session_attr):up();

			end

		end);

module:add_iq_handler("c2s", "urn:ietf:params:xml:ns:xmpp-bind", 

		function (session, stanza)

			log("debug", "Client tried to bind to a resource");

			local resource;

			if stanza.attr.type == "set" then

				local bind = stanza.tags[1];

				if bind and bind.attr.xmlns == xmlns_bind then

					resource = bind:child_with_name("resource");

					if resource then

						resource = resource[1];

					end

				end

			end

			local success, err_type, err, err_msg = sm_bind_resource(session, resource);

			if not success then

				session.send(st.error_reply(stanza, err_type, err, err_msg));

			else

				session.send(st.reply(stanza)

					:tag("bind", { xmlns = xmlns_bind})

					:tag("jid"):text(session.full_jid));

			end

		end);

module:add_iq_handler("c2s", "urn:ietf:params:xml:ns:xmpp-session", 

		function (session, stanza)

			log("debug", "Client tried to bind to a resource");

			session.send(st.reply(stanza));

		end);