On USB Driver Coding #7

Hi,

In the previous post we have seen how to completely Dump an URB but as you should remember exists a particular structure _URB_CONTROL_TRANSFER, that USB client drivers sets up to transfer data to or from a control pipe. So we need to implement two external Dump Functions, DumpPipeHandle and DumpTransferBuffer.

void DumpPipeHandle(
in struct Buffer *b,const char *s,
in USBD_PIPE_HANDLE inPipeHandle
)
{
unsigned char ep;

if (GetEndpointInfo(inPipeHandle,&ep))
KPrintf(b,”%s = %p [endpoint 0x%x]\n”,s,inPipeHandle,ep);
else
KPrintf(b,”%s = %p\n”,s,inPipeHandle);
}

As you should remember it’s necessary for any PipeHandle to know the Endpoint. This can be accomplished by tracing the USBD_PIPE_HANDLE for each Endpoint (the number of Endpoints is declared at our choise (use for example MAXEP = 50).

Now is time to rip the TransferBuffer with DumpTransferBuffer:

void DumpTransferBuffer(
struct Buffer *b,
PUCHAR pBuffer,
PMDL pMdl,
ULONG uBufferSize,
in BOOLEAN bPrintHeader,
ULONG uBufferOffset = 0
)

if(pMdl)
{
DumpBuffer(b,pBuffer+uBufferOffset,uBufferSize);

else if(pMdl)
{
PUCHAR pMDLBuf = (PUCHAR)MmGetSystemAddressForMdlSafe(pMdl,NormalPagePriority);
if(pMDLBuf)
DumpBuffer(b,pMDLBuf+uBufferOffset,uBufferSize);
}
}

Here ends the USB Coding Series (source code I’ve used is taken from SniffUSB 2.0), but surely i’ll come back with other arguments related to USB..

See you to the next post.. 🙂