tp5如何防止cc攻击

PHP
//防cc攻击
sheli_cc();
function sheli_cc(){
//代理IP直接退出
empty($_SERVER['Http_VIA']) or exit('Access Denied');
//防止快速刷新
session_start();
$seconds = '60'; //时间段[秒]
$refresh = '12'; //刷新次数
//设置监控变量
$cur_time = time();
if(isset($_SESSION['last_time'])){
$_SESSION['refresh_times'] += 1;
}else{
$_SESSION['refresh_times'] = 1;
$_SESSION['last_time'] = $cur_time;
}
//处理监控结果
if($cur_time - $_SESSION['last_time'] < $seconds){
if($_SESSION['refresh_times'] >= $refresh){
//跳转至攻击者服务器地址
//header(sprintf('Location:%s', 'http://127.0.0.1')); 
exit('请求频率太快，稍候'.$seconds.'秒后再访问！'); 
}
}else{
$_SESSION['refresh_times'] = 0;
$_SESSION['last_time'] = $cur_time;
}
}
?>