Here is how to tell if an Active Directory user account expired:
define('LDAP_OPT_DIAGNOSTIC_MESSAGE', 0x0032);
ldap_set_option($conn, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_set_option($conn, LDAP_OPT_REFERRALS, 0);
$bind = ldap_bind($conn, $user, $pass);
ldap_get_option($conn, LDAP_OPT_DIAGNOSTIC_MESSAGE, $extended_error);
if (!empty($extended_error))
{
$errno = explode(',', $extended_error)[2];
$errno = explode(' ', $errno)[2];
$errno = intval($errno);
if ($errno == 532)
$err = 'Unable to login: Password expired.';
}
