PHP Reffers detection

Reffers detection

<?
if(isset($_SERVER['HTTP_REFERER'])) {
  $refer = $_SERVER['HTTP_REFERER'];

  if (($refer)) {
    $date = date("d F Y");
    $fail = fopen("refer.txt", "a");
    fputs($fail, "$refer|$date\");
    fclose($fail);
  }
}
?>