kern: ether_gen_addr: randomize on default hostuuid, too

[kevans]

Summary

Currently, this will still hash the default (all zero) hostuuid and
potentially arrive at a MAC address that has a high chance of collision
if another interface of the same name appears in the same broadcast
domain on another host without a hostuuid, e.g., some virtual machine
setups.

Instead of using the default hostuuid, just treat it as a failure and
generate a random LA unicast MAC address.

[donner]

sys/net/if_ethersubr.c

1480

return;

[gbe]

LGTM from manpages.

[bz]

Don't forget to bump .Dd on the man page when committing.

[bcr]

In D29788#668512, @bz wrote:

Don't forget to bump .Dd on the man page when committing.

You took the words right out of my mouth. :)

[melifaro]

sys/net/if_ethersubr.c

1476

Maybe it's worth having this logic as a separate function instead of the goto block?

[kevans]

sys/net/if_ethersubr.c

1476

I'd tend to prefer not... this is really just a failure path, and we shouldn't expose a "random mac address" KPI since we're somewhat trying to reduce the # LA addresses we're randomly generating.

[kbowling]

LGTM still will you push it?

[kevans]

In D29788#687333, @kbowling wrote:

LGTM still will you push it?

Yeah, sorry; $life interfered, but I'll round up some time ~tonight