--

-- Prosody IM

-- Copyright (C) 2010 Waqas Hussain

-- Copyright (C) 2010 Jeff Mitchell

-- Copyright (C) 2013 Mikael Nordfeldth

-- Copyright (C) 2013 Matthew Wild, finally came to fix it all

--

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

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

--

local lpty = assert(require "lpty", "mod_auth_external requires lpty: https://modules.prosody.im/mod_auth_external.html#installation");

local usermanager = require "core.usermanager";

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

local server = require "net.server";

local have_async, async = pcall(require, "util.async");

local log = module._log;

local host = module.host;

local script_type = module:get_option_string("external_auth_protocol", "generic");

local command = module:get_option_string("external_auth_command", "");

local read_timeout = module:get_option_number("external_auth_timeout", 5);

local blocking = module:get_option_boolean("external_auth_blocking", true); -- non-blocking is very experimental

local auth_processes = module:get_option_number("external_auth_processes", 1);

assert(script_type == "ejabberd" or script_type == "generic",

	"Config error: external_auth_protocol must be 'ejabberd' or 'generic'");

assert(not host:find(":"), "Invalid hostname");

if not blocking then

	assert(server.event, "External auth non-blocking mode requires libevent installed and enabled");

	log("debug", "External auth in non-blocking mode, yay!")

	waiter, guard = async.waiter, async.guarder();

elseif auth_processes > 1 then

	log("warn", "external_auth_processes is greater than 1, but we are in blocking mode - reducing to 1");

	auth_processes = 1;

end

local ptys = {};

local pty_options = { throw_errors = false, no_local_echo = true, use_path = false };

for i = 1, auth_processes do

	ptys[i] = lpty.new(pty_options);

end

function module.unload()

	for i = 1, auth_processes do

		ptys[i]:endproc();

	end

end

module:hook_global("server-cleanup", module.unload);

local curr_process = 0;

function send_query(text)

	curr_process = (curr_process%auth_processes)+1;

	local pty = ptys[curr_process];

	local finished_with_pty

	if not blocking then

		finished_with_pty = guard(pty); -- Prevent others from crossing this line while we're busy

	end

	if not pty:hasproc() then

		local status, ret = pty:exitstatus();

		if status and (status ~= "exit" or ret ~= 0) then

			log("warn", "Auth process exited unexpectedly with %s %d, restarting", status, ret or 0);

			return nil;

		end

		local ok, err = pty:startproc(command);

		if not ok then

			log("error", "Failed to start auth process '%s': %s", command, err);

			return nil;

		end

		log("debug", "Started auth process");

	end

	pty:send(text);

	if blocking then

		return pty:read(read_timeout);

	else

		local response;

		local wait, done = waiter();

		server.addevent(pty:getfd(), server.event.EV_READ, function ()

			response = pty:read();

			done();

			return -1;

		end);

		wait();

		finished_with_pty();

		return response;

	end

end

function do_query(kind, username, password)

	if not username then return nil, "not-acceptable"; end

	local query = (password and "%s:%s:%s:%s" or "%s:%s:%s"):format(kind, username, host, password);

	local len = #query

	if len > 1000 then return nil, "policy-violation"; end

	if script_type == "ejabberd" then

		local lo = len % 256;

		local hi = (len - lo) / 256;

		query = string.char(hi, lo)..query;

	elseif script_type == "generic" then

		query = query..'\n';

	end

	local response, err = send_query(query);

	if not response then

		log("warn", "Error while waiting for result from auth process: %s", err or "unknown error");

	elseif (script_type == "ejabberd" and response == "\0\2\0\0") or

		(script_type == "generic" and response:gsub("\r?\n$", "") == "0") then

			return nil, "not-authorized";

	elseif (script_type == "ejabberd" and response == "\0\2\0\1") or

		(script_type == "generic" and response:gsub("\r?\n$", "") == "1") then

			return true;

	else

		log("warn", "Unable to interpret data from auth process, %s",

			(response:match("^error:") and response) or ("["..#response.." bytes]"));

		return nil, "internal-server-error";

	end

end

local provider = {};

function provider.test_password(username, password)

	return do_query("auth", username, password);

end

function provider.set_password(username, password)

	return do_query("setpass", username, password);

end

function provider.user_exists(username)

	return do_query("isuser", username);

end

function provider.create_user(username, password) -- luacheck: ignore 212

	return nil, "Account creation/modification not available.";

end

function provider.get_sasl_handler()

	local testpass_authentication_profile = {

		plain_test = function(sasl, username, password, realm)

			return usermanager.test_password(username, realm, password), true;

		end,

	};

	return new_sasl(host, testpass_authentication_profile);

end

module:provides("auth", provider);