nft: allow stacking vlan header on top of ethernet

currently 'vlan id 42' or even 'vlan type ip' doesn't work since
we expect ethernet header but get vlan.

So if we want to add another protocol header to the same base, we
attempt to figure out if the new header can fit on top of the existing
one (i.e. proto_find_num gives a protocol number when asking to find
link between the two).

We also annotate protocol description for eth and vlan with the full
header size and track the offset from the current base.

Otherwise, 'vlan type ip' fetches the protocol field from mac header
offset 0, which is some mac address.

Instead, we must consider full size of ethernet header.

Signed-off-by: Florian Westphal <fw@strlen.de>

0 files changed, 0 insertions, 0 deletions