Re: [PATCH nft] proto: fix VLAN header definition

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Mon, Nov 30, 2015 at 02:53:22PM +0100, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > On Sun, Nov 29, 2015 at 11:37:43PM +0100, Florian Westphal wrote:
> > > Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > > On Sun, Nov 29, 2015 at 01:09:29AM +0100, Florian Westphal wrote:
> > > > > Thanks for looking at this.  I'll take a closer look tomorrow,
> > > > > your patch works fine for ip version/hdrlength but seems it messes
> > > > > with endianess somewhere.
> > > > 
> > > > I forgot to update payload_shift_value() too, to skip the shift when
> > > > not needed, sorry, new patch attached.
> > > 
> > > Almost there. Again, with Patricks patch to fix VLAN header:
> > > 
> > > # src/nft --debug=netlink add rule bridge raw prerouting ether type vlan vlan type ip vlan id 4094 ip version 4 counter 
> > > bridge raw prerouting
> > 
> > OK, new try, the idea behind is to calculate this shift through:
> > 
> >         x = offset % BITS_PER_BYTE
> >         y = len % BITS_PER_BYTE
> > 
> > to get both offset and length at byte level.
> > 
> > Then calculate the shift based on this:
> > 
> >         shift = BITS_PER_BYTE - (x + y)
> > 
> > Does this look good to you?
> 
> Sorry, that patch doesn't apply for me to master branch,
> neither standalone nor on top of your previous patch.

I see, sorry. Anyway, let me revisit these arithmetics again, they
still don't correctly cover all cases as we need.