-- mod_auth_ldap

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

local lualdap = require "lualdap";

local function ldap_filter_escape(s)

	return (s:gsub("[*()\\%z]", function(c) return ("\\%02x"):format(c:byte()) end));

end

-- Config options

local ldap_server = module:get_option_string("ldap_server", "localhost");

local ldap_rootdn = module:get_option_string("ldap_rootdn", "");

local ldap_password = module:get_option_string("ldap_password", "");

local ldap_tls = module:get_option_boolean("ldap_tls");

local ldap_scope = module:get_option_string("ldap_scope", "subtree");

local ldap_filter = module:get_option_string("ldap_filter", "(uid=$user)"):gsub("%%s", "$user", 1);

local ldap_base = assert(module:get_option_string("ldap_base"), "ldap_base is a required option for ldap");

local ldap_mode = module:get_option_string("ldap_mode", "bind");

local ldap_admins = module:get_option_string("ldap_admin_filter",

	module:get_option_string("ldap_admins")); -- COMPAT with mistake in documentation

local host = ldap_filter_escape(module:get_option_string("realm", module.host));

-- Initiate connection

local ld = nil;

module.unload = function() if ld then pcall(ld, ld.close); end end

function ldap_do_once(method, ...)

	if ld == nil then

		local err;

		ld, err = lualdap.open_simple(ldap_server, ldap_rootdn, ldap_password, ldap_tls);

		if not ld then return nil, err, "reconnect"; end

	end

	-- luacheck: ignore 411/success

	local success, iterator, invariant, initial = pcall(ld[method], ld, ...);

	if not success then ld = nil; return nil, iterator, "search"; end

	local success, dn, attr = pcall(iterator, invariant, initial);

	if not success then ld = nil; return success, dn, "iter"; end

	return dn, attr, "return";

end

function ldap_do(method, retry_count, ...)

	local dn, attr, where;

	for _=1,1+retry_count do

		dn, attr, where = ldap_do_once(method, ...);

		if dn or not(attr) then break; end -- nothing or something found

		module:log("warn", "LDAP: %s %s (in %s)", tostring(dn), tostring(attr), where);

		-- otherwise retry

	end

	if not dn and attr then

		module:log("error", "LDAP: %s", tostring(attr));

	end

	return dn, attr;

end

function get_user(username)

	module:log("debug", "get_user(%q)", username);

	return ldap_do("search", 2, {

		base = ldap_base;

		scope = ldap_scope;

		sizelimit = 1;

		filter = ldap_filter:gsub("%$(%a+)", {

			user = ldap_filter_escape(username);

			host = host;

		});

	});

end

local provider = {};

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

	return nil, "Account creation not available with LDAP.";

end

function provider.user_exists(username)

	return not not get_user(username);

end

function provider.set_password(username, password)

	local dn, attr = get_user(username);

	if not dn then return nil, attr end

	if attr.userPassword == password then return true end

	return ldap_do("modify", 2, dn, { '=', userPassword = password });

end

if ldap_mode == "getpasswd" then

	function provider.get_password(username)

		local dn, attr = get_user(username);

		if dn and attr then

			return attr.userPassword;

		end

	end

	function provider.test_password(username, password)

		return provider.get_password(username) == password;

	end

	function provider.get_sasl_handler()

		return new_sasl(module.host, {

			plain = function(sasl, username) -- luacheck: ignore 212/sasl

				local password = provider.get_password(username);

				if not password then return "", nil; end

				return password, true;

			end

		});

	end

elseif ldap_mode == "bind" then

	local function test_password(userdn, password)

		local ok, err = lualdap.open_simple(ldap_server, userdn, password, ldap_tls);

		if not ok then

			module:log("debug", "ldap open_simple error: %s", err);

		end

		return not not ok;

	end

	function provider.test_password(username, password)

		local dn = get_user(username);

		if not dn then return end

		return test_password(dn, password)

	end

	function provider.get_sasl_handler()

		return new_sasl(module.host, {

			plain_test = function(sasl, username, password) -- luacheck: ignore 212/sasl

				return provider.test_password(username, password), true;

			end

		});

	end

else

	module:log("error", "Unsupported ldap_mode %s", tostring(ldap_mode));

end

module:provides("auth", provider);