php 生成唯一的散列

function create_unique() {     $data = $_SERVER['HTTP_USER_AGENT'] . $_SERVER['REMOTE_ADDR']      .time() . rand();     return sha1($data);     }

//生成的散列if(isset($_COOKIE["userunique"])&&strlen($_COOKIE["userunique"])>10){ $userunique=$_COOKIE["userunique"]; setcookie("userunique",$userunique,time()+365*3600,"/");}else{   $userunique = create_unique();   setcookie("userunique",$userunique,time()+365*3600,"/",);}

//cook的保存$from_ip=$_SERVER['REMOTE_ADDR'];echo $userunique;echo "<br>";echo $from_ip;

//$_SERVER服务器变量列表