php防止DDos攻击

<?php  
//查询禁止IP  
$ip =$_SERVER['REMOTE_ADDR'];  
$fileht=".htaccess2";  
if(!file_exists($fileht))file_put_contents($fileht,"");  
$filehtarr=@file($fileht);  
if(in_array($ip."
",$filehtarr))die("Warning:"."<br>"."Your IP address are forbided by some reason, IF you have any question Pls emill to shop@mydalle.com!");  

//加入禁止IP  
$time=time();  
$fileforbid="log/forbidchk.dat";  
if(file_exists($fileforbid))  
{ if($time-filemtime($fileforbid)>60)unlink($fileforbid);  
else{  
$fileforbidarr=@file($fileforbid);  
if($ip==substr($fileforbidarr[0],0,strlen($ip)))  
{  
if($time-substr($fileforbidarr[1],0,strlen($time))>600)unlink($fileforbid);  
elseif($fileforbidarr[2]>600){file_put_contents($fileht,$ip."
",FILE_APPEND);unlink($fileforbid);}  
else{$fileforbidarr[2]++;file_put_contents($fileforbid,$fileforbidarr);}  
}  
}  
}  
//防刷新  
$str="";  
$file="log/ipdate.dat";  
if(!file_exists("log")&&!is_dir("log"))mkdir("log",0777);  
if(!file_exists($file))file_put_contents($file,"");  
$allowTime = 120;//防刷新时间  
$allowNum=10;//防刷新次数  
$uri=$_SERVER['REQUEST_URI'];  
$checkip=md5($ip);  
$checkuri=md5($uri);  
$yesno=true;  
$ipdate=@file($file);  
foreach($ipdate as $k=>$v)  
{ $iptem=substr($v,0,32);  
$uritem=substr($v,32,32);  
$timetem=substr($v,64,10);  
$numtem=substr($v,74);  
if($time-$timetem<$allowTime){  
if($iptem!=$checkip)$str.=$v;  
else{  
$yesno=false;  
if($uritem!=$checkuri)$str.=$iptem.$checkuri.$time."1
";  
elseif($numtem<$allowNum)$str.=$iptem.$uritem.$timetem.($numtem+1)."
";  
else  
{  
if(!file_exists($fileforbid)){$addforbidarr=array($ip."
",time()."
",1);file_put_contents($fileforbid,$addforbidarr);}  
file_put_contents("log/forbided_ip.log",$ip."--".date("Y-m-d H:i:s",time())."--".$uri."
",FILE_APPEND);  
$timepass=$timetem+$allowTime-$time;  
die("Warning:"."<br>"."Sorry,you are forbided by refreshing frequently too much, Pls wait for ".$timepass." seconds to continue!");  
}  
}  
}  
}  
if($yesno) $str.=$checkip.$checkuri.$time."1
";  
file_put_contents($file,$str);  
?>