$ip = $_SERVER['REMOTE_ADDR'];
  // In case of "too long" ipv6 address, we take only the 15 first chars.
  //
  // It would be "cleaner" to increase length of history.IP to 50 chars, but
  // the alter table is very long on such a big table. We should plan this
  // for a future version, once history table is kept "smaller".
  if (strpos($ip,':') !== false and strlen($ip) > 15)
  {
    $ip = substr($ip, 0, 15);
  }