protected function buildCookieHeader()
  {
    $cookie_string = "";
    
    @reset($this->cookie_array);
    while(list($key, $value) = @each($this->cookie_array))
    {
      $cookie_string .= "; ".$key."=".$value."";
    }
    
    if ($cookie_string != "")
    {
      return "Cookie: ".substr($cookie_string, 2)."\r\n";
    }
    else
    {
      return null;
    }
  }