對網站發動XSS攻擊的方式有很多種，僅僅使用php的一些內置過濾函數是對付不了的，即使你將filter_var,mysql_real_escape_string,htmlentities,htmlspecialchars,strip_tags這些函數都使用上了也不一定能保證絕對的安全。

現在有很多php開發框架都提供關于防XSS攻擊的過濾方法，下面和大家分享一個預防XSS攻擊和ajax跨域攻擊的函數，摘自某開發框架，相比于僅僅使用內置函數應該還是夠強了的吧。

function xss_clean($data){
	// Fix &entity\n;
	$data=str_replace(array('&','<','>'),array('&','<','>'),$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: <span style="width: expression(alert('Ping!'));"></span>
	$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)
	$data=preg_replace('#</*\w+:\w[^>]*+>#i','',$data);
	// http://www.Alixixi.com/
	do{// Remove really unwanted tags
		$old_data=$data;
		$data=preg_replace('#</*(?:appletb(?:asegsoundlink)embedframe(?:set)?i(?:framelayer)l(?:ayerink)metaobjects(?:cripttyle)titlexml)[^>]*+>#i','',$data);
	}while($old_data!==$data);
	// we are done...
	return $data;
}

關鍵字：php、XSS、攻擊、ajax