Winscard Dll with WCF

Question

My Project structure

 myApp 
  -->WCFSerLibrary 
  -->ClassLib1
  -->ClassLib2  // This one uses winscard.dll 

I wanted to communicate with a Smartcard reaer attached.

Four steps I follow for that are

1. SCardEstablishContext
2. Get the reader name via SCardListReaders
3. SCardConnect
4. Read with SCardTransmit

The first three steps execute succesfully but when i try to do a SCardTransmit it gives back me response code of 87.

Second side, The above mentioned scenario is when I call it from WCF service. Now I use the same ClassLib2 in a Windows FOrm application it communicates properly.

 retCode =  ModWinsCard.SCardTransmit(hCard, ref pioSendRequest, ref SendBuff[0], sendLen, ref pioSendRequest, ref RecvBuff[0], ref recvLen);

where as in ModWinsCard class

   [DllImport("winscard.dll"l)]
    public static extern Int64 SCardTransmit(UInt64 hCard, ref SCARD_IO_REQUEST pioSendRequest, ref byte SendBuff, int SendBuffLen, ref SCARD_IO_REQUEST pioRecvRequest, ref byte RecvBuff, ref int RecvBuffLen);

Answer 1

87 is invalid parameter. The method returns an int not a long. Also you are passing in only the first item in the in and out buffers. Should use IntPtr for the card handle.

LONG WINAPI SCardTransmit(
  _In_         SCARDHANDLE hCard,
  _In_         LPCSCARD_IO_REQUEST pioSendPci,
  _In_         LPCBYTE pbSendBuffer,
  _In_         DWORD cbSendLength,
  _Inout_opt_  LPSCARD_IO_REQUEST pioRecvPci,
  _Out_        LPBYTE pbRecvBuffer,
  _Inout_      LPDWORD pcbRecvLength
);

Maybe try the pinvoke signature below instead?

[DllImport("winscard.dll"l)]
        public static extern int SCardTransmit(
            IntPtr hCard, 
            ref SCARD_IO_REQUEST pioSendRequest, 
            byte[] SendBuff, 
            int SendBuffLen, 
            ref SCARD_IO_REQUEST pioRecvRequest, 
            IntPtr RecvBuff,    // Copy with marshal.copy to a managed array after call.
            ref int RecvBuffLen);