if ((isset($_POST['pass']) && (isset($_POST['login'])))) {
  $pass = stripslashes($_POST['pass']);
  $login = stripslashes($_POST['login']);
  $username_check = $db->query("SELECT name, pass FROM ".PREFIX."_users WHERE name='".$db->safesql($login)."' LIMIT 1");
  list($sqllogin,$sqlpass) = $db->get_array($username_check);
  if (!(($sqllogin == $login) && ($sqlpass == $pass))) {
   echo 'error and etc';
  }
  else {
   $_SESSION["fb_login"] = $login;
   $_SESSION["fb_pass"] = $pass;
   echo 'it's ok';
  }
}