PHP防CC拦截代码，拦截率60%

<?php
empty($_SERVER['HTTP_VIA']) or exit('Access Denied');
$seconds = 10; //时间段[秒]
$refresh = 5; //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){
//跳转验证
$url='http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$msg=mb_convert_encoding("<title>安全检查</title><h3>检测到CC攻击，正在进行浏览器安全检查！</h3>","UTF-8","GBK");
exit($msg."<meta http-equiv='refresh' content='5;url={$url}'>");//5是定时跳转的时间，后期可以根据时间段调整跳转时间
}
}else{
$_SESSION['refresh_times'] = 0;
$_SESSION['last_time'] = $cur_time;
}
?>