mirror of
https://github.com/silverstripe/silverstripe-framework
synced 2024-08-26 20:45:47 +02:00
306 lines
9.8 KiB
PHP
306 lines
9.8 KiB
PHP
<?php
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/**
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* Sanitises an HTMLValue so it's contents are the elements and attributes that are whitelisted
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* using the same configuration as TinyMCE
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*
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* See www.tinymce.com/wiki.php/configuration:valid_elements for details on the spec of TinyMCE's
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* whitelist configuration
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*
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* @package forms
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* @subpackage fields-formattedinput
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*/
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class HtmlEditorSanitiser {
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/** @var [stdClass] - $element => $rule hash for whitelist element rules where the element name isn't a pattern */
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protected $elements = array();
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/** @var [stdClass] - Sequential list of whitelist element rules where the element name is a pattern */
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protected $elementPatterns = array();
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/** @var [stdClass] - The list of attributes that apply to all further whitelisted elements added */
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protected $globalAttributes = array();
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/**
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* Construct a sanitiser from a given HtmlEditorConfig
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*
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* Note that we build data structures from the current state of HtmlEditorConfig - later changes to
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* the passed instance won't cause this instance to update it's whitelist
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*
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* @param HtmlEditorConfig $config
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*/
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public function __construct(HtmlEditorConfig $config) {
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$valid = $config->getOption('valid_elements');
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if ($valid) $this->addValidElements($valid);
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$valid = $config->getOption('extended_valid_elements');
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if ($valid) $this->addValidElements($valid);
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}
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/**
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* Given a TinyMCE pattern (close to unix glob style), create a regex that does the match
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*
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* @param $str - The TinyMCE pattern
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* @return string - The equivalent regex
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*/
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protected function patternToRegex($str) {
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return '/^' . preg_replace('/([?+*])/', '.$1', $str) . '$/';
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}
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/**
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* Given a valid_elements string, parse out the actual element and attribute rules and add to the
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* internal whitelist
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*
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* Logic based heavily on javascript version from tiny_mce_src.js
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*
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* @param string $validElements - The valid_elements or extended_valid_elements string to add to the whitelist
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*/
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protected function addValidElements($validElements) {
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$elementRuleRegExp = '/^([#+\-])?([^\[\/]+)(?:\/([^\[]+))?(?:\[([^\]]+)\])?$/';
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$attrRuleRegExp = '/^([!\-])?(\w+::\w+|[^=:<]+)?(?:([=:<])(.*))?$/';
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$hasPatternsRegExp = '/[*?+]/';
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foreach(explode(',', $validElements) as $validElement) {
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if(preg_match($elementRuleRegExp, $validElement, $matches)) {
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$prefix = isset($matches[1]) ? $matches[1] : null;
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$elementName = isset($matches[2]) ? $matches[2] : null;
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$outputName = isset($matches[3]) ? $matches[3] : null;
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$attrData = isset($matches[4]) ? $matches[4] : null;
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// Create the new element
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$element = new stdClass();
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$element->attributes = array();
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$element->attributePatterns = array();
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$element->attributesRequired = array();
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$element->attributesDefault = array();
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$element->attributesForced = array();
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foreach(array('#' => 'paddEmpty', '-' => 'removeEmpty') as $match => $means) {
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$element->$means = ($prefix === $match);
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}
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// Copy attributes from global rule into current rule
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if($this->globalAttributes) {
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$element->attributes = array_merge($element->attributes, $this->globalAttributes);
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}
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// Attributes defined
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if($attrData) {
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foreach(explode('|', $attrData) as $attr) {
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if(preg_match($attrRuleRegExp, $attr, $matches)) {
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$attr = new stdClass();
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$attrType = isset($matches[1]) ? $matches[1] : null;
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$attrName = isset($matches[2]) ? str_replace('::', ':', $matches[2]) : null;
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$prefix = isset($matches[3]) ? $matches[3] : null;
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$value = isset($matches[4]) ? $matches[4] : null;
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// Required
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if($attrType === '!') {
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$element->attributesRequired[] = $attrName;
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$attr->required = true;
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}
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// Denied from global
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else if($attrType === '-') {
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unset($element->attributes[$attrName]);
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continue;
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}
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// Default value
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if($prefix) {
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// Default value
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if($prefix === '=') {
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$element->attributesDefault[$attrName] = $value;
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$attr->defaultValue = $value;
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}
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// Forced value
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else if($prefix === ':') {
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$element->attributesForced[$attrName] = $value;
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$attr->forcedValue = $value;
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}
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// Required values
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else if($prefix === '<') {
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$attr->validValues = explode('?', $value);
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}
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}
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// Check for attribute patterns
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if(preg_match($hasPatternsRegExp, $attrName)) {
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$attr->pattern = $this->patternToRegex($attrName);
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$element->attributePatterns[] = $attr;
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}
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else {
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$element->attributes[$attrName] = $attr;
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}
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}
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}
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}
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// Global rule, store away these for later usage
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if(!$this->globalAttributes && $elementName == '@') {
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$this->globalAttributes = $element->attributes;
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}
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// Handle substitute elements such as b/strong
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if($outputName) {
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$element->outputName = $elementName;
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$this->elements[$outputName] = $element;
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}
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// Add pattern or exact element
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if(preg_match($hasPatternsRegExp, $elementName)) {
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$element->pattern = $this->patternToRegex($elementName);
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$this->elementPatterns[] = $element;
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}
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else {
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$this->elements[$elementName] = $element;
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}
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}
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}
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}
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/**
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* Given an element tag, return the rule structure for that element
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* @param string $tag - The element tag
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* @return stdClass - The element rule
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*/
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protected function getRuleForElement($tag) {
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if(isset($this->elements[$tag])) {
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return $this->elements[$tag];
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}
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else foreach($this->elementPatterns as $element) {
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if(preg_match($element->pattern, $tag)) return $element;
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}
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}
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/**
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* Given an attribute name, return the rule structure for that attribute
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* @param string $name - The attribute name
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* @return stdClass - The attribute rule
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*/
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protected function getRuleForAttribute($elementRule, $name) {
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if(isset($elementRule->attributes[$name])) {
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return $elementRule->attributes[$name];
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}
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else foreach($elementRule->attributePatterns as $attribute) {
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if(preg_match($attribute->pattern, $name)) return $attribute;
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}
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}
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/**
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* Given a DOMElement and an element rule, check if that element passes the rule
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* @param DOMElement $element - the element to check
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* @param stdClass $rule - the rule to check against
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* @return bool - true if the element passes (and so can be kept), false if it fails (and so needs stripping)
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*/
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protected function elementMatchesRule($element, $rule = null) {
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// If the rule doesn't exist at all, the element isn't allowed
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if(!$rule) return false;
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// If the rule has attributes required, check them to see if this element has at least one
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if($rule->attributesRequired) {
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$hasMatch = false;
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foreach($rule->attributesRequired as $attr) {
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if($element->getAttribute($attr)) {
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$hasMatch = true;
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break;
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}
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}
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if(!$hasMatch) return false;
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}
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// If the rule says to remove empty elements, and this element is empty, remove it
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if($rule->removeEmpty && !$element->firstChild) return false;
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// No further tests required, element passes
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return true;
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}
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/**
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* Given a DOMAttr and an attribute rule, check if that attribute passes the rule
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* @param DOMAttr $attr - the attribute to check
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* @param stdClass $rule - the rule to check against
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* @return bool - true if the attribute passes (and so can be kept), false if it fails (and so needs stripping)
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*/
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protected function attributeMatchesRule($attr, $rule = null) {
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// If the rule doesn't exist at all, the attribute isn't allowed
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if(!$rule) return false;
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// If the rule has a set of valid values, check them to see if this attribute is one
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if(isset($rule->validValues) && !in_array($attr->value, $rule->validValues)) return false;
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// No further tests required, attribute passes
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return true;
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}
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/**
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* Given an SS_HTMLValue instance, will remove and elements and attributes that are
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* not explicitly included in the whitelist passed to __construct on instance creation
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*
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* @param SS_HTMLValue $html - The HTMLValue to remove any non-whitelisted elements & attributes from
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*/
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public function sanitise (SS_HTMLValue $html) {
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if(!$this->elements && !$this->elementPatterns) return;
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$doc = $html->getDocument();
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foreach($html->query('//body//*') as $el) {
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$elementRule = $this->getRuleForElement($el->tagName);
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// If this element isn't allowed, strip it
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if(!$this->elementMatchesRule($el, $elementRule)) {
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// If it's a script or style, we don't keep contents
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if($el->tagName === 'script' || $el->tagName === 'style') {
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$el->parentNode->removeChild($el);
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}
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// Otherwise we replace this node with all it's children
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else {
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// First, create a new fragment with all of $el's children moved into it
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$frag = $doc->createDocumentFragment();
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while($el->firstChild) $frag->appendChild($el->firstChild);
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// Then replace $el with the frags contents (which used to be it's children)
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$el->parentNode->replaceChild($frag, $el);
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}
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}
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// Otherwise tidy the element
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else {
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// First, if we're supposed to pad & this element is empty, fix that
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if($elementRule->paddEmpty && !$el->firstChild) {
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$el->nodeValue = ' ';
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}
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// Then filter out any non-whitelisted attributes
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$children = $el->attributes;
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$i = $children->length;
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while($i--) {
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$attr = $children->item($i);
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$attributeRule = $this->getRuleForAttribute($elementRule, $attr->name);
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// If this attribute isn't allowed, strip it
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if(!$this->attributeMatchesRule($attr, $attributeRule)) {
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$el->removeAttributeNode($attr);
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}
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}
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// Then enforce any default attributes
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foreach($elementRule->attributesDefault as $attr => $default) {
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if(!$el->getAttribute($attr)) $el->setAttribute($attr, $default);
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}
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// And any forced attributes
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foreach($elementRule->attributesForced as $attr => $forced) {
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$el->setAttribute($attr, $forced);
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}
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}
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}
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}
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}
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