private Tuple <PDUHeader, byte[], AuthData> ReadPDU(int frag_count)
        {
            byte[] buffer = ReadFragment(_max_recv_fragment);
            RpcUtils.DumpBuffer(true, $"{GetType().Name} Receive Buffer - Fragment {frag_count}", buffer);
            MemoryStream stm    = new MemoryStream(buffer);
            BinaryReader reader = new BinaryReader(stm);
            PDUHeader    header = PDUHeader.Read(reader);

            NdrUnmarshalBuffer.CheckDataRepresentation(header.DataRep);
            AuthData auth_data            = new AuthData();
            int      auth_trailing_length = header.AuthLength > 0 ? header.AuthLength + AuthData.PDU_AUTH_DATA_HEADER_SIZE : 0;

            byte[] data = reader.ReadAllBytes(header.FragmentLength - PDUHeader.PDU_HEADER_SIZE - auth_trailing_length);
            if (auth_trailing_length > 0)
            {
                stm.Seek(header.FragmentLength - auth_trailing_length, SeekOrigin.Begin);
                auth_data = AuthData.Read(reader, header.AuthLength);
            }
            return(Tuple.Create(header, data, auth_data));
        }