NDIS IM - problems with NdisSend

Hi,
I am developing application to encypt / decrypt TCP/IP packets data. I
know that the fastest way is to change date in a driver, but one of the
requirements is to make it possible to change cryptographic algorithm
in an easy way. I decided to change PassThru driver extended by Thomas
F. Divine (part 2 of his article) and I pass interesting packets to my
application and block them in the driver. Then I want to change the
data there and resend packets as a new ones (from a driver's point of
view). And here is my problem. When I create a new NDIS_PACKET and try
to send it with NdisSend (or even NdisSendPackets, as in NDISPROT DDK
example) I've got bluescreen. Here is a piece of my code (without any
debug and other additional lines), please tell me where is my
misunderstanding of this subject.

FltDevIoControl(){
(...)
PNDIS_PACKET pNdisPacket;
PNDIS_BUFFER pNdisBuffer;
(...)
ioBuffer = pIrp->AssociatedIrp.SystemBuffer;
inputBufferLength =
pIrpSp->Parameters.DeviceIoControl.InputBufferLength;
(...)
case MY_IOCTL_CODE:

pNdisPacket = NULL;
pNdisBuffer = NULL;

NdisAcquireSpinLock(&(pFilterContext->PacketListSpinLock));
NdisAllocatePacket(&Status, &pNdisPacket,
pAdapt->SendPacketPoolHandle);
NdisAllocateBuffer(&Status, &pNdisBuffer,
pAdapt->SendBufferPoolHandle, ioBuffer, inputBufferLength );
NdisChainBufferAtFront(pNdisPacket, pNdisBuffer);
NdisSend(&Status, pAdapt->BindingHandle, pNdisPacket );
if (Status != NDIS_STATUS_PENDING){
NdisFreeBuffer(pNdisBuffer);
NdisFreePacket(pNdisPacket);
}
NdisReleaseSpinLock(&(pFilterContext->PacketListSpinLock));
break;
}

It seems to me that there is nothing to go wrong. Maybe I can't see
some important issues. Thank you for any advice in advance.
Arek

Arek,

If you are writing a device driver, saying "I've got a bluescreen" is
unacceptable. You must have a debugger attached then you will know more
about the crash.

In code below, don't hold spinlock while calling NdisSend.

What happens if NdisSend returns STATUS_PENDING? Will the data from
user-mode go away while NDIS is using it?

Do you understand that ProtocolSendComplete will be called eventually? Do
you realize that ProtocolSendComplete must do somethings differently for
packets that you send this way?

Please use a debugger.

Thomas F. Divine

<> wrote in message
news: oups.com...
> Hi,
> I am developing application to encypt / decrypt TCP/IP packets data. I
> know that the fastest way is to change date in a driver, but one of the
> requirements is to make it possible to change cryptographic algorithm
> in an easy way. I decided to change PassThru driver extended by Thomas
> F. Divine (part 2 of his article) and I pass interesting packets to my
> application and block them in the driver. Then I want to change the
> data there and resend packets as a new ones (from a driver's point of
> view). And here is my problem. When I create a new NDIS_PACKET and try
> to send it with NdisSend (or even NdisSendPackets, as in NDISPROT DDK
> example) I've got bluescreen. Here is a piece of my code (without any
> debug and other additional lines), please tell me where is my
> misunderstanding of this subject.
>
> FltDevIoControl(){
> (...)
> PNDIS_PACKET pNdisPacket;
> PNDIS_BUFFER pNdisBuffer;
> (...)
> ioBuffer = pIrp->AssociatedIrp.SystemBuffer;
> inputBufferLength =
> pIrpSp->Parameters.DeviceIoControl.InputBufferLength;
> (...)
> case MY_IOCTL_CODE:
>
> pNdisPacket = NULL;
> pNdisBuffer = NULL;
>
> NdisAcquireSpinLock(&(pFilterContext->PacketListSpinLock));
> NdisAllocatePacket(&Status, &pNdisPacket,
> pAdapt->SendPacketPoolHandle);
> NdisAllocateBuffer(&Status, &pNdisBuffer,
> pAdapt->SendBufferPoolHandle, ioBuffer, inputBufferLength );
> NdisChainBufferAtFront(pNdisPacket, pNdisBuffer);
> NdisSend(&Status, pAdapt->BindingHandle, pNdisPacket );
> if (Status != NDIS_STATUS_PENDING){
> NdisFreeBuffer(pNdisBuffer);
> NdisFreePacket(pNdisPacket);
> }
> NdisReleaseSpinLock(&(pFilterContext->PacketListSpinLock));
> break;
> }
>
> It seems to me that there is nothing to go wrong. Maybe I can't see
> some important issues. Thank you for any advice in advance.
> Arek
>

Thomas,

First of all thank you for such an impressively fast reply.

To be honest I must admit (but I am sure that it's quite obvious
that I am a newbie in drivers' subject.

Your remarks gave me a lot to think. I've changed my code, added my own
packets and buffers pools, so that I can tell apart which packets are
mine and which are not (in PTSendComplete).
Moreover I implemented solution from NDISPROT example, so now I suspend
irp call and keep it with packet and after all I can complete it in
PTSendComplete.
Now it seems like it works fine for me.

In short, my code now looks like below (again I overlooked some extra
code):

filter.c:

NdisAcquireSpinLock(&(pFilterContext->PacketListSpinLock));
NdisAllocatePacket(&Status, &pNdisPacket, pAdapt->OutPacketPoolHandle
);
NdisAllocateBuffer(&Status, &pNdisBuffer, pAdapt->OutBufferPoolHandle,
ioBuffer, inputBufferLength );
NdisChainBufferAtFront(pNdisPacket, pNdisBuffer);
NdisReleaseSpinLock(&(pFilterContext->PacketListSpinLock));

NdisInterlockedIncrement( &pAdapt->RefCount );
IoMarkIrpPending(pIrp);
InsertTailList(&(pAdapt->OutPendedListHead),
&pIrp->Tail.Overlay.ListEntry);
IoSetCancelRoutine(pIrp, CancelOutIrp);
NPROT_IRP_FROM_SEND_PKT(pNdisPacket) = pIrp;

NdisSend(&Status, pAdapt->BindingHandle, pNdisPacket );
if (Status == NDIS_STATUS_PENDING){
NtStatus = STATUS_PENDING;
}
break;

protocol.c:

if (PoolHandle == pAdapt->OutPacketPoolHandle) {
PIRP pIrp;
PIO_STACK_LOCATION pIrpSp;
UINT nBufferCount;
PNDIS_BUFFER pCurrentBuffer;
UINT TotalPacketLength;

pIrp = NPROT_IRP_FROM_SEND_PKT(Packet);
NdisAcquireSpinLock(&pAdapt->Lock);
RemoveEntryList(&pIrp->Tail.Overlay.ListEntry);
NdisReleaseSpinLock(&pAdapt->Lock);
IoSetCancelRoutine(pIrp, NULL);

pIrpSp = IoGetCurrentIrpStackLocation(pIrp);
if (Status == NDIS_STATUS_SUCCESS) {
pIrp->IoStatus.Information = pIrpSp->Parameters.Write.Length;
pIrp->IoStatus.Status = STATUS_SUCCESS;
} else {
pIrp->IoStatus.Information = 0;
pIrp->IoStatus.Status = STATUS_UNSUCCESSFUL;
}

NdisQueryPacket( (PNDIS_PACKET )Packet, NULL, (PUINT)&nBufferCount,
&pCurrentBuffer, &TotalPacketLength );
// my packets always have only one buffer
if (pCurrentBuffer)
NdisFreeBuffer(pCurrentBuffer);
NdisFreePacket(Packet);

IoCompleteRequest(pIrp, IO_NO_INCREMENT);
NdisInterlockedDecrement( &pAdapt->RefCount );
}

Thanks again for Your help and I'll apreciate it if you have any
further comments.
Arek