private function curl($url, $post_param = null)
    {
      $ch = curl_init();
      $fh = fopen('curl.txt', 'a+'); 
      curl_setopt($ch, CURLOPT_STDERR, $fh);
      curl_setopt($ch, CURLOPT_VERBOSE, 1);

      if($post_param != null)
      {
        curl_setopt($ch, CURLOPT_HTTPHEADER, array
        (
          'Host'             => 'tld.com',
          'User-Agent'       => 'Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1',
          'Accept'           => 'application/json, text/javascript, */*; q=0.01',
          'Accept-Language'  => 'en-us,en;q=0.5',
          'Accept-Encoding'  => 'gzip, deflate',
          'Accept-Charset'   => 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
          'Keep-Alive'       => '115',
          'Connection'       => 'keep-alive',
          'X-Requested-With' => 'XMLHttpRequest',
          'Referer'          => 'http://tld.com/sendlogin.php'
        ));
      }
      else
      	curl_setopt($ch, CURLOPT_COOKIE, 'hellobar_current=1300711502; hellobar_1300711502_variation=11462');

      curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
      curl_setopt($ch, CURLOPT_COOKIEJAR, dirname(__FILE__) . '/cookie.txt');
      curl_setopt($ch, CURLOPT_COOKIEFILE, dirname(__FILE__) . '/cookie.txt');
      curl_setopt($ch, CURLOPT_URL, $url.'?'.$post_param);
      $html = curl_exec($ch);
      curl_close($ch);
      fclose($fh);
      return $html;
    }