How to fetch ExternalID, SystemID and InternalSubset from an xmlNodePtr that has type=XML_DOCUMENT_TYPE_NODE or XML_DTD_NODE

Question

I need 3 values (ExternalID, SystemID, InternalSubset) from xmlNodePtr when it is of type XML_DOCUMENT_TYPE_NODE or XML_DTD_NODE.

I noticed that XML_DOCUMENT_TYPE_NODE is deprecated and that you recommend using XML_DTD_NODE. Given, an xmlNodePtr which has type=XML_DOCUMENT_TYPE_NODE or XML_DTD_NODE, how can fetch those 3 values.

I also noticed that in Android Open Source Code here they have directly typecasted xmlNodePtr to xmlDtdPtr. Is this possible? If yes, we can get ExternalID and SystemID from xmlDtdPtr.