164 lines
3.7 KiB
PHP
164 lines
3.7 KiB
PHP
<?php
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namespace PicoFeed;
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use DomDocument;
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use SimpleXmlElement;
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/**
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* XML parser class
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*
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* Checks for XML eXternal Entity (XXE) and XML Entity Expansion (XEE) attacks on XML documents
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*
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* @author Frederic Guillot
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* @package picofeed
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*/
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class XmlParser
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{
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/**
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* Get a SimpleXmlElement instance or return false
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*
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* @static
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* @access public
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* @param string $input XML content
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* @return mixed
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*/
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public static function getSimpleXml($input)
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{
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$dom = self::getDomDocument($input);
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if ($dom !== false) {
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$simplexml = simplexml_import_dom($dom);
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if (! $simplexml instanceof SimpleXmlElement) {
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return false;
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}
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return $simplexml;
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}
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return false;
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}
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/**
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* Get a DomDocument instance or return false
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*
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* @static
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* @access public
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* @param string $input XML content
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* @return mixed
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*/
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public static function getDomDocument($input)
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{
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if (substr(php_sapi_name(), 0, 3) === 'fpm') {
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// If running with PHP-FPM and an entity is detected we refuse to parse the feed
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// @see https://bugs.php.net/bug.php?id=64938
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if (strpos($input, '<!ENTITY') !== false) {
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return false;
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}
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}
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else {
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libxml_disable_entity_loader(true);
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}
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libxml_use_internal_errors(true);
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$dom = new DomDocument;
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$dom->loadXml($input, LIBXML_NONET);
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// The document is empty, there is probably some parsing errors
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if ($dom->childNodes->length === 0) {
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return false;
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}
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// Scan for potential XEE attacks using ENTITY
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foreach ($dom->childNodes as $child) {
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if ($child->nodeType === XML_DOCUMENT_TYPE_NODE) {
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if ($child->entities->length > 0) {
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return false;
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}
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}
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}
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return $dom;
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}
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/**
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* Load HTML document by using a DomDocument instance or return false on failure
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*
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* @static
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* @access public
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* @param string $input XML content
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* @return mixed
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*/
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public static function getHtmlDocument($input)
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{
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libxml_use_internal_errors(true);
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$dom = new DomDocument;
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if (version_compare(PHP_VERSION, '5.4.0', '>=')) {
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$dom->loadHTML($input, LIBXML_NONET);
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}
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else {
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$dom->loadHTML($input);
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}
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return $dom;
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}
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/**
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* Get XML parser errors
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*
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* @static
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* @access public
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* @return string
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*/
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public static function getErrors()
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{
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$errors = array();
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foreach(libxml_get_errors() as $error) {
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$errors[] = sprintf('XML error: %s (Line: %d - Column: %d - Code: %d)',
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$error->message,
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$error->line,
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$error->column,
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$error->code
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);
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}
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return implode(', ', $errors);
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}
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/**
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* Get the encoding from a xml tag
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*
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* @static
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* @access public
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* @param string $data Input data
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* @return string
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*/
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public static function getEncodingFromXmlTag($data)
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{
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$encoding = '';
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if (strpos($data, '<?xml') !== false) {
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$data = substr($data, 0, strrpos($data, '?>'));
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$data = str_replace("'", '"', $data);
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$p1 = strpos($data, 'encoding=');
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$p2 = strpos($data, '"', $p1 + 10);
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$encoding = substr($data, $p1 + 10, $p2 - $p1 - 10);
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$encoding = strtolower($encoding);
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}
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return $encoding;
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}
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}
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