T0/T1 marshaling confusion about pyscard HOT 20 CLOSED

A bit more research... The '1' in dwProtocol for T0 is is clearly correct. The question is why 0 is sent from that piece of C-code, because that seems to be why the C code works.... Here is the same snippet of gdb from stepping through pcscd when calling the C program:

03558356 winscard_svc.c:351:ContextThread() Received command: TRANSMIT from client 14
353                     switch (header.command)
(gdb) 
621                                     READ_BODY(trStr)
(gdb) 
623                                     if (MSGCheckHandleAssociation(trStr.hCard, threadContext))
(gdb) p trStr
$1 = {hCard = 781293158, ioSendPciProtocol = 0, ioSendPciLength = 6299704, cbSendLength = 6, ioRecvPciProtocol = 3, ioRecvPciLength = 16, 
  pcbRecvLength = 266, rv = 0}

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Why don't you use the value returned by SCardConnect() in dwActiveProtocol to use it in SCardTransmit() ?

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You are using SCARD_SHARE_DIRECT. This imply a different protocol negotiation.
But that does not explain why the C code "works".

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Sure but the case statement in _Transmit in scard.i makes that impossible

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Yes but I use SCARD_SHARE_DIRECT in the pyscard code too - I just left that out for brevity

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dwActiveProtocol is 0 btw which hits the default case in _Transmit and causes an Invalid Parameter exception. This seems inconsistent with the behaviour of the C library where passing 0 while using DIRECT triggers the desired behavior in the driver

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Here is a patch that "fixes" this. Review pls...

diff --git a/smartcard/scard/scard.i b/smartcard/scard/scard.i
index 76f63ad..87f38fa 100644
--- a/smartcard/scard/scard.i
+++ b/smartcard/scard/scard.i
@@ -672,8 +672,12 @@ static SCARDRETCODE _Transmit(
 )
 {
     PSCARD_IO_REQUEST piorequest=NULL;
+    SCARD_IO_REQUEST unknown;
     long ret;

+    unknown.dwProtocol = 0;
+    unknown.cbPciLength = 0;
+
     pblRecvBuffer->ab = (unsigned char*)mem_Malloc(MAX_BUFFER_SIZE_EXTENDED*sizeof(unsigned char));
     pblRecvBuffer->cBytes = MAX_BUFFER_SIZE_EXTENDED;

@@ -692,6 +696,10 @@ static SCARDRETCODE _Transmit(
             piorequest=(PSCARD_IO_REQUEST)myg_prgSCardRawPci;
             break;

+        case 0x00:
+            piorequest = &unknown;
+            break;
+
         default:
             return SCARD_E_INVALID_PARAMETER

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I guess your C code works because you go in the default case and pioSendPci is not initialized.
With luck you have pioSendPci.dwProtocol = 0 and 0 is SCARD_PROTOCOL_UNDEFINED.

What is the value of dwActiveProtocolafter the SCardConnect()?

If you add a the line pioSendPci.dwProtocol = SCARD_PROTOCOL_T0 before the switch(dwActiveProtocol) the C program should also fail. Do you confirm?

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Skickat från min iPhone

21 okt. 2016 kl. 21:28 skrev Ludovic Rousseau [email protected]:

I guess your C code works because you go in the default case and pioSendPci is not initialized.
With luck you have pioSendPci.dwProtocol = 0 and 0 is SCARD_PROTOCOL_UNDEFINED.

What is the value of dwActiveProtocolafter the SCardConnect()?

If you add a the line pioSendPci.dwProtocol = SCARD_PROTOCOL_T0 before the switch(dwActiveProtocol) the C program should also fail. Do you confirm?

Oh I'm absolutely sure you're right!

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What is the value of dwActiveProtocol after the SCardConnect()?

You forgot to answer this question.

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I got no answer?
I need to understand the problem in order to fix it correctly.

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On 2016-11-07 20:28, Ludovic Rousseau wrote:

I got no answer?
I need to understand the problem in order to fix it correctly.

sorry, got several NMIs

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Really sorry for the delay!

repr(dwActiveProtocol) == 0L after ScardConnect

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It should be fixed with fa3addb

Please confirm it works for you.

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Can you please confirm the fix works for you?
The idea is to close this issue and release a new version of PySCard.

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Actually it doesn't. I still needed my patch to make it work.

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Your patch should not apply without modifications on the latest version.

• Are you really using the latest PySCard git version?
• If yes can you send me your updated patch for review?

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OK. You PR can apply cleanly.
But your patch should have NO effect since the case 0 (or SCARD_PROTOCOL_UNDEFINED) is already managed by the current code.

I also note that your repository at https://github.com/SUNET/pyscard/commits/master is NOT up to date.

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This bug should be fixed upstream.
If your problem is still present then please open a new issue with details and traces.

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