-- Prosody IM

-- 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 sm_make_authenticated = require "core.sessionmanager".make_authenticated;

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

local nodeprep = require "util.encodings".stringprep.nodeprep;

local datamanager_load = require "util.datamanager".load;

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

local usermanager_get_supported_methods = require "core.usermanager".get_supported_methods;

local usermanager_user_exists = require "core.usermanager".user_exists;

local usermanager_get_password = require "core.usermanager".get_password;

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 secure_auth_only = config.get(module:get_host(), "core", "c2s_require_encryption") or config.get(module:get_host(), "core", "require_encryption");

local log = module._log;

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", "CHALLENGE: %s", 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", "SUCCESS: %s", ret or "");

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

	else

		module:log("error", "Unknown sasl status: %s", status);

	end

	return reply;

end

local function handle_status(session, status)

	if status == "failure" then

		session.sasl_handler = nil;

	elseif status == "success" then

		local username = nodeprep(session.sasl_handler.username);

		session.sasl_handler = nil;

		if not username then -- TODO move this to sessionmanager

			module:log("warn", "SASL succeeded but we didn't get a username!");

			session.sasl_handler = nil;

			session:reset_stream();

			return;

		end 

		sm_make_authenticated(session, username);

		session:reset_stream();

	end

end

local function credentials_callback(mechanism, ...)

	if mechanism == "PLAIN" then

		local username, hostname, password = ...;

		username = nodeprep(username);

		if not username then

			return false;

		end

		local response = usermanager_validate_credentials(hostname, username, password, mechanism);

		if response == nil then

			return false;

		else

			return response;

		end

	elseif mechanism == "DIGEST-MD5" then

		local function func(x) return x; end

		local node, domain, realm, decoder = ...;

		local prepped_node = nodeprep(node);

		if not prepped_node then

			return func, nil;

		end

		local password = usermanager_get_password(prepped_node, domain);

		if password then

			if decoder then

				node, realm, password = decoder(node), decoder(realm), decoder(password);

			end

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

		else

			return func, nil;

		end

	end

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") then

			if stanza.attr.mechanism ~= "ANONYMOUS" then

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

			end

		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, credentials_callback);

		if not session.sasl_handler then

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

		end

		if secure_auth_only and not session.secure then

			return session.send(build_reply("failure", "encryption-required"));

		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", "AUTH: %s", text:gsub("[%z\001-\008\011\012\014-\031]", " "));

		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: %s", 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

				if secure_auth_only and not session.secure then

					return;

				end

				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

						local mechanisms = usermanager_get_supported_methods(session.host or "*");

						for k, v in pairs(mechanisms) do

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

						end

					end

				features:up();

			else

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

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

			end

		end);

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

		function (session, stanza)

			log("debug", "Client requesting a resource bind");

			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 requesting a session");

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

		end);