[ovs-dev] [PATCH 11/15] ofproto-dpif-xlate: Add IPv6 ND support for XC_TNL_ARP

[Thadeu Lima de Souza Cascardo]

On Tue, Nov 10, 2015 at 04:03:13PM -0800, Ben Pfaff wrote:
> On Thu, Oct 22, 2015 at 03:29:04PM -0200, Thadeu Lima de Souza Cascardo wrote:
> > Use IPv4-mapped addresses and use either tnl_arp_lookup or tnl_nd_lookup.
> > 
> > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at redhat.com>
> 
> ...
> 
> > @@ -5348,8 +5349,13 @@ xlate_push_stats(struct xlate_cache *xcache,
> >              break;
> >          case XC_TNL_ARP:
> >              /* Lookup arp to avoid arp timeout. */
> > -            tnl_arp_lookup(entry->u.tnl_arp_cache.br_name,
> > -                           entry->u.tnl_arp_cache.d_ip, &dmac);
> > +            d_ip = in6_addr_get_mapped_ipv4(&entry->u.tnl_arp_cache.d_ipv6);
> > +            if (d_ip) {
> > +                tnl_arp_lookup(entry->u.tnl_arp_cache.br_name, d_ip, &dmac);
> > +            } else {
> > +                tnl_nd_lookup(entry->u.tnl_arp_cache.br_name,
> > +                               &entry->u.tnl_arp_cache.d_ipv6, &dmac);
> > +            }
> 
> This code seems a little silly to me, because it is going to some
> trouble to distinguish IPv4 from IPv6 and pick the correct
> tnl_*_lookup() function, and either function it picks is going to
> convert that right back to do the lookup.  I think it would be more
> sensible to export tnl_arp_lookup__() so that the double conversion
> isn't needed.
> 
> Thanks,
> 
> Ben.

Urgh. Well, I could just use tnl_nd_lookup here with an extra comment about
that. Exporting tnl_arp_lookup__ would require exporting struct tnl_arp_entry.
But I see your point. The only bad point for me in using tnl_nd_lookup directly
would be the naming. But since we already have an IPv6 address in our hands, why
not just add a comment assuring this will work on IPv4-mapped addresses as well?

I will send something like that.

Thanks.
Cascardo.