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xsshtml.class.php
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xsshtml.class.php
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<?php
/**
* PHP 富文本XSS过滤类
*
* @package XssHtml
*
*/
#
# Usage:
# <?php
# require('xsshtml.class.php');
# $html = '<html code>';
# $xss = new XssHtml($html);
# $html = $xss->getHtml();
# ?\>
#
# 需求：
# PHP Version > 5.0
# 浏览器版本：IE7+ 或其他浏览器，无法防御IE6及以下版本浏览器中的XSS
# 更多使用选项见 http://phith0n.github.io/XssHtml
class XssHtml {
private $m_dom;
private $m_xss;
private $m_ok;
private $m_AllowAttr = array('title', 'src', 'href', 'id', 'class', 'style', 'width', 'height', 'alt', 'target', 'align');
private $m_AllowTag = array('a', 'img', 'br', 'strong', 'b', 'code', 'pre', 'p', 'div', 'em', 'span', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'table', 'ul', 'ol', 'tr', 'th', 'td', 'hr', 'li', 'u');
/**
* 构造函数
*
* @param string $html 待过滤的文本
* @param string $charset 文本编码，默认utf-8
* @param array $AllowTag 允许的标签，如果不清楚请保持默认，默认已涵盖大部分功能，不要增加危险标签
*/
public function __construct($html, $charset = 'utf-8', $AllowTag = array()){
$this->m_AllowTag = empty($AllowTag) ? $this->m_AllowTag : $AllowTag;
$this->m_xss = strip_tags($html, '<' . implode('><', $this->m_AllowTag) . '>');
if (empty($this->m_xss)) {
$this->m_ok = FALSE;
return ;
}
$this->m_xss = "<meta http-equiv=\"Content-Type\" content=\"text/html;charset={$charset}\">" . $this->m_xss;
$this->m_dom = new DOMDocument();
$this->m_dom->strictErrorChecking = FALSE;
$this->m_ok = @$this->m_dom->loadHTML($this->m_xss);
}
/**
* 获得过滤后的内容
*/
public function getHtml()
{
if (!$this->m_ok) {
return '';
}
$nodeList = $this->m_dom->getElementsByTagName('*');
for ($i = 0; $i < $nodeList->length; $i++){
$node = $nodeList->item($i);
if (in_array($node->nodeName, $this->m_AllowTag)) {
if (method_exists($this, "__node_{$node->nodeName}")) {
call_user_func(array($this, "__node_{$node->nodeName}"), $node);
}else{
call_user_func(array($this, '__node_default'), $node);
}
}
}
return strip_tags($this->m_dom->saveHTML(), '<' . implode('><', $this->m_AllowTag) . '>');
}
private function __true_url($url){
if (preg_match('#^https?://.+#is', $url)) {
return $url;
}else{
return 'http://' . $url;
}
}
private function __get_style($node){
if ($node->attributes->getNamedItem('style')) {
$style = $node->attributes->getNamedItem('style')->nodeValue;
$style = str_replace('\\', ' ', $style);
$style = str_replace(array('&#', '/*', '*/'), ' ', $style);
$style = preg_replace('#e.*x.*p.*r.*e.*s.*s.*i.*o.*n#Uis', ' ', $style);
return $style;
}else{
return '';
}
}
private function __get_link($node, $att){
$link = $node->attributes->getNamedItem($att);
if ($link) {
return $this->__true_url($link->nodeValue);
}else{
return '';
}
}
private function __setAttr($dom, $attr, $val){
if (!empty($val)) {
$dom->setAttribute($attr, $val);
}
}
private function __set_default_attr($node, $attr, $default = '')
{
$o = $node->attributes->getNamedItem($attr);
if ($o) {
$this->__setAttr($node, $attr, $o->nodeValue);
}else{
$this->__setAttr($node, $attr, $default);
}
}
private function __common_attr($node)
{
$list = array();
foreach ($node->attributes as $attr) {
if (!in_array($attr->nodeName,
$this->m_AllowAttr)) {
$list[] = $attr->nodeName;
}
}
foreach ($list as $attr) {
$node->removeAttribute($attr);
}
$style = $this->__get_style($node);
$this->__setAttr($node, 'style', $style);
$this->__set_default_attr($node, 'title');
$this->__set_default_attr($node, 'id');
$this->__set_default_attr($node, 'class');
}
private function __node_img($node){
$this->__common_attr($node);
$this->__set_default_attr($node, 'src');
$this->__set_default_attr($node, 'width');
$this->__set_default_attr($node, 'height');
$this->__set_default_attr($node, 'alt');
$this->__set_default_attr($node, 'align');
}
private function __node_a($node){
$this->__common_attr($node);
$href = $this->__get_link($node, 'href');
$this->__setAttr($node, 'href', $href);
$this->__set_default_attr($node, 'target', '_blank');
}
private function __node_embed($node){
$this->__common_attr($node);
$link = $this->__get_link($node, 'src');
$this->__setAttr($node, 'src', $link);
$this->__setAttr($node, 'allowscriptaccess', 'never');
$this->__set_default_attr($node, 'width');
$this->__set_default_attr($node, 'height');
}
private function __node_default($node){
$this->__common_attr($node);
}
}
?>