function get_remote_IP ($socket) {
  $status = socket_getpeerinfo($socket, $result);
  if (!$status) return false;
  return $result;
}

function socket_accept_nbl ($listener, $blacklist) {
  $newsocket = socket_accept($listener);
  if ($newsocket === false) return false;
  $ip = get_remote_IP($newsocket);
  if (array_search($ip, $blacklist) !== false) {
    socket_close($newsocket);
    return false;
  }
  return $newsocket;
}