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<?php
namespace PicoFeed\Parser;
use DomDocument;
use DOMXPath;
use SimpleXmlElement;
/**
* XML parser class
*
* Checks for XML eXternal Entity (XXE) and XML Entity Expansion (XEE) attacks on XML documents
*
* @author Frederic Guillot
* @package Parser
*/
class XmlParser
{
/**
* Get a SimpleXmlElement instance or return false
*
* @static
* @access public
* @param string $input XML content
* @return mixed
*/
public static function getSimpleXml($input)
{
$dom = self::getDomDocument($input);
if ($dom !== false) {
$simplexml = simplexml_import_dom($dom);
if (! $simplexml instanceof SimpleXmlElement) {
return false;
}
return $simplexml;
}
return false;
}
/**
* Get a DomDocument instance or return false
*
* @static
* @access public
* @param string $input XML content
* @return mixed
*/
public static function getDomDocument($input)
{
if (substr(php_sapi_name(), 0, 3) === 'fpm') {
// If running with PHP-FPM and an entity is detected we refuse to parse the feed
// @see https://bugs.php.net/bug.php?id=64938
if (strpos($input, '<!ENTITY') !== false) {
return false;
}
}
else {
libxml_disable_entity_loader(true);
}
libxml_use_internal_errors(true);
$dom = new DomDocument;
$dom->loadXml($input, LIBXML_NONET);
// The document is empty, there is probably some parsing errors
if ($dom->childNodes->length === 0) {
return false;
}
// Scan for potential XEE attacks using ENTITY
foreach ($dom->childNodes as $child) {
if ($child->nodeType === XML_DOCUMENT_TYPE_NODE) {
if ($child->entities->length > 0) {
return false;
}
}
}
return $dom;
}
/**
* Load HTML document by using a DomDocument instance or return false on failure
*
* @static
* @access public
* @param string $input XML content
* @return mixed
*/
public static function getHtmlDocument($input)
{
libxml_use_internal_errors(true);
$dom = new DomDocument;
if (version_compare(PHP_VERSION, '5.4.0', '>=')) {
$dom->loadHTML($input, LIBXML_NONET);
}
else {
$dom->loadHTML($input);
}
return $dom;
}
/**
* Convert a HTML document to XML
*
* @static
* @access public
* @param string $html HTML document
* @return string
*/
public static function HtmlToXml($html)
{
$dom = self::getHtmlDocument('<?xml version="1.0" encoding="UTF-8">'.$html);
return $dom->saveXML($dom->getElementsByTagName('body')->item(0));
}
/**
* Get XML parser errors
*
* @static
* @access public
* @return string
*/
public static function getErrors()
{
$errors = array();
foreach(libxml_get_errors() as $error) {
$errors[] = sprintf('XML error: %s (Line: %d - Column: %d - Code: %d)',
$error->message,
$error->line,
$error->column,
$error->code
);
}
return implode(', ', $errors);
}
/**
* Get the encoding from a xml tag
*
* @static
* @access public
* @param string $data Input data
* @return string
*/
public static function getEncodingFromXmlTag($data)
{
$encoding = '';
if (strpos($data, '<?xml') !== false) {
$data = substr($data, 0, strrpos($data, '?>'));
$data = str_replace("'", '"', $data);
$p1 = strpos($data, 'encoding=');
$p2 = strpos($data, '"', $p1 + 10);
$encoding = substr($data, $p1 + 10, $p2 - $p1 - 10);
$encoding = strtolower($encoding);
}
return $encoding;
}
/**
* Get xml:lang value
*
* @static
* @access public
* @param string $xml XML string
* @return string Language
*/
public static function getXmlLang($xml)
{
$dom = self::getDomDocument($xml);
if ($dom === false) {
return '';
}
$xpath = new DOMXPath($dom);
return $xpath->evaluate('string(//@xml:lang[1])') ?: '';
}
/**
* Get a value from a XML namespace
*
* @static
* @access public
* @param SimpleXMLElement $xml XML element
* @param array $namespaces XML namespaces
* @param string $property XML tag name
* @param string $attribute XML attribute name
* @return string
*/
public static function getNamespaceValue(SimpleXMLElement $xml, array $namespaces, $property, $attribute = '')
{
foreach ($namespaces as $name => $url) {
$namespace = $xml->children($namespaces[$name]);
if ($namespace->$property->count() > 0) {
if ($attribute) {
foreach ($namespace->$property->attributes() as $xml_attribute => $xml_value) {
if ($xml_attribute === $attribute && $xml_value) {
return (string) $xml_value;
}
}
}
return (string) $namespace->$property;
}
}
return '';
}
}
|
