From: Chema Gonzalez <redacted>
Date: Fri, 2 May 2014 17:53:01 -0700

On Fri, May 2, 2014 at 2:49 PM, David Miller [off-list ref] wrote:

quoted

We can probably add an extension to AF_PACKET which provides the flow
key at the end of the tpacket3_hdr if a certain socket option is set.

That would provide the transport header as well as a side effect, and
be much more powerful and efficient than this particular BPF
instruction.

Once you get the L3 proto and noff/toff, you get everything. The
rationale of adding toff/noff is that it's very similar to poff, which
we already have.

But you're implementation is calling a function to do all of that work
already, just to get only the transport header and then throwing away
all of the other useful bits that function is calculating, so you'll
end up doing it twice which is wasted work.