php预防XSS攻击，ajax跨域攻击的方法

对网站发动XSS攻击的方式有很多种，仅仅使用php的一些内置过滤函数是对付不了的，即使你将filter_var,mysql_real_escape_string,htmlentities,htmlspecialchars,strip_tags这些函数都使用上了也不一定能保证绝对的安全。

现在有很多php开发框架都提供关于防XSS攻击的过滤方法，下面和大家分享一个预防XSS攻击和ajax跨域攻击的函数，摘自某开发框架，相比于仅仅使用内置函数应该还是够强了的吧。

function xss_clean($data){

// Fix &entityn;

$data=str_replace(array('&','<','>'),array('&','<','>'),$data);

$data=preg_replace('/(&#*w+)[x00-x20]+;/u','$1;',$data);

$data=preg_replace('/(&#x*[0-9A-F]+);*/iu','$1;',$data);

$data=html_entity_decode($data,ENT_COMPAT,'UTF-8');

// Remove any attribute starting with "on" or xmlns

$data=preg_replace('#(<[^>]+?[x00-x20"'])(?:onxmlns)[^>]*+>#iu','$1>',$data);

// Remove javascript: and vbscript: protocols

$data=preg_replace('#([a-z]*)[x00-x20]*=[x00-x20]*([`'"]*)[x00-x20]*j[x00-x20]*a[x00-x20]*v[x00-x20]*a[x00-x20]*s[x00-x20]*c[x00-x20]*r[x00-x20]*i[x00-x20]*p[x00-x20]*t[x00-x20]*:#iu','$1=$2nojavascript...',$data);

$data=preg_replace('#([a-z]*)[x00-x20]*=(['"]*)[x00-x20]*v[x00-x20]*b[x00-x20]*s[x00-x20]*c[x00-x20]*r[x00-x20]*i[x00-x20]*p[x00-x20]*t[x00-x20]*:#iu','$1=$2novbscript...',$data);

$data=preg_replace('#([a-z]*)[x00-x20]*=(['"]*)[x00-x20]*-moz-binding[x00-x20]*:#u','$1=$2nomozbinding...',$data);

// Only works in IE:

$data=preg_replace('#(<[^>]+?)style[x00-x20]*=[x00-x20]*[`'"]*.*?expression[x00-x20]*([^>]*+>#i','$1>',$data);

$data=preg_replace('#(<[^>]+?)style[x00-x20]*=[x00-x20]*[`'"]*.*?behaviour[x00-x20]*([^>]*+>#i','$1>',$data);

$data=preg_replace('#(<[^>]+?)style[x00-x20]*=[x00-x20]*[`'"]*.*?s[x00-x20]*c[x00-x20]*r[x00-x20]*i[x00-x20]*p[x00-x20]*t[x00-x20]*:*[^>]*+>#iu','$1>',$data);

// Remove namespaced elements (we do not need them)

$data=preg_replace('#]*+>#i','',$data);

// http://www.Alixixi.com/

do{// Remove really unwanted tags

$old_data=$data;

$data=preg_replace('#]*+>#i','',$data);

}while($old_data!==$data);

// we are done...

return $data;

}