Hi all,

I am a fledging in NDIS driver. Currently, I try to get the packet buffer
via the function
VOID
NdisGetFirstBufferFromPacket(
IN PNDIS_PACKET Packet,
OUT PNDIS_BUFFER *FirstBuffer,
OUT PVOID *FirstBufferVA,
OUT PUINT FirstBufferLength,
OUT PUINT TotalBufferLength
);

However, if the offset I want to get is out of the current buffer, for
example, the IP header, how can I get the pointer? Access FirstBufferVA[
sizeof( MAC_HEADER ) ] directly or go through the buffer list one by one?

And what should be considerated when I access virtual address and physical
address>

Many thanks!

-Liang

NdisQueryBuffer can help.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

Or better, NdisQueryBufferSafe if you don't care 9x.

--
Calvin Guan Windows DDK MVP
Staff SW Engineer, NetXtreme MINIPORT
Enterprise Network Controller Engineering
Broadcom Corporation www.broadcom.com


"Maxim S. Shatskih" <maxim@storagecraft.com> wrote in message
news:uyk13T$bFHA.3320@TK2MSFTNGP10.phx.gbl...

Thank for your immediate replies.

Actually, I get the first block buffer of a packet by
NdisGetFirstBufferFromPacketSafe( pNdisPacket, pNdisBuffer, &pEthHeader,
&BufLen, &TotalBufLen );

When I find the present buffer block is insufficient for the ip header by
NdisBufferLength(), how can I update the pointer to the next buffer in the
linked list?

NdisGetNextBuffer( pNdisBuffer, &pNdisNextBuffer );
or
NdisGetNextBuffer( (PNDIS_BUFFER) pEthHeader, &pNdisNextBuffer );

Thanks!

-Liang
"Calvin Guan" wrote:

Liang Chen wrote:
Since the actual packet (frame) data of each NDIS_PACKET is an
NDIS_BUFFER list, the first method is correct, i.e.

NdisGetNextBuffer( pNdisBuffer, &pNdisNextBuffer );

[Note that a packet can also consist of just one single NDIS_BUFFER,
usually true for received packets.]

Stephan