소켓 상태

function socket_state($sock)
{
  if(!is_resource($sock)) return;

  $ss = array($sock);
  $sr = @socket_select($ss,$w=NULL,$e=NULL,0);
  $sw = @socket_select($r=NULL,$ss,$e=NULL,0);
  $se = @socket_select($r=NULL,$w=NULL,$ss,0);

  unset($ss);

  return $sr.$sw.$se; // string
}