private function validateDTD(DOMDocument $document)
{
if (is_null($document->doctype)) {
return true;
}
// Do not validate external DTDs if the loadFromNet option is disabled:
$systemId = $document->doctype->systemId;
if (filter_var($systemId, FILTER_VALIDATE_URL) && !$this->loadFromNet) {
return true;
}
return $document->validate();
}