Merge pull request #160 from Jason-elkins/ignore_dtds

add EntityResolver to ignore externally referenced dtd files

Author: jhursty

src/KM_xml.cpp

@@ -988,6 +988,15 @@ Kumu::XMLElement::ParseString(const char* document, ui32_t doc_len)
   return errorCount > 0 ? false : true;
 }
 
+
+class IgnoreDTDResolver : public xercesc::EntityResolver {
+public:
+    InputSource* resolveEntity(const XMLCh* const, const XMLCh* const) override {
+        static const XMLByte dummy[] = "";
+        return new xercesc::MemBufInputSource(dummy, 0, "dummy-dtd", false);
+    }
+};
+
 //
 bool
 Kumu::XMLElement::ParseFirstFromString(const char* document, ui32_t doc_len)
@@ -1002,14 +1011,18 @@ Kumu::XMLElement::ParseFirstFromString(const char* document, ui32_t doc_len)
   int errorCount = 0;
   SAXParser* parser = new SAXParser();
 
-  parser->setValidationScheme(SAXParser::Val_Always);
+  parser->setValidationScheme(SAXParser::Val_Never);
   parser->setDoNamespaces(true);    // optional
 
   MyTreeHandler* docHandler = new MyTreeHandler(this);
   parser->setDocumentHandler(docHandler);
   parser->setErrorHandler(docHandler);
   XMLPScanToken token;
 
+  // Ignore references to DTD files
+  IgnoreDTDResolver resolver;
+  parser->setEntityResolver(&resolver);
+
   try
     {
       MemBufInputSource xmlSource(reinterpret_cast<const XMLByte*>(document),