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。

01        function xss_clean($data){
02        // Fix &entityn;
03        $data=str_replace(array('&','<','>'),array('&','<','>'),$data);
04        $data=preg_replace('/(&#*w+)[x00-x20]+;/u','$1;',$data);
05        $data=preg_replace('/(&#x*[0-9A-F]+);*/iu','$1;',$data);
06        $data=html_entity_decode($data,ENT_COMPAT,'UTF-8');
07        // Remove any attribute starting with "on" or xmlns
08        $data=preg_replace('#(<[^>]+?[x00-x20"'])(?:on|xmlns)[^>]*+>#iu','$1>',$data);
09        // Remove javascript: and vbscript: protocols
10        $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);
11        $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);
12        $data=preg_replace('#([a-z]*)[x00-x20]*=(['"]*)[x00-x20]*-moz-binding[x00-x20]*:#u','$1=$2nomozbinding...',$data);
13        // Only works in IE: <span style="width:expression(alert('Ping!'));"></span> 14        $data=preg_replace('#(<[^>]+?)style[x00-x20]*=[x00-x20]*[`'"]*.*?expression[x00-x20]*([^>]*+>#i','$1>',$data);
15        $data=preg_replace('#(<[^>]+?)style[x00-x20]*=[x00-x20]*[`'"]*.*?behaviour[x00-x20]*([^>]*+>#i','$1>',$data);
16        $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);
17        // Remove namespaced elements (we do not need them)
18        $data=preg_replace('#</*w+:w[^>]*+>#i','',$data);
19        // http://www.phpernote.com/
20        do{// Remove really unwanted tags
21        $old_data=$data;
22        $data=preg_replace('#</*(?:applet|b(?:ase|gsound|link)|embed|frame(?:set)?|i(?:frame|layer)|l(?:ayer|ink)|meta|object|s(?:cript|tyle)|title|xml)[^>]*+>#i','',$data);
23        }while($old_data!==$data);
24        // we are done...
25        return $data;
26        }