Re: [HACKERS] Linux.conf.au 2003 Report

On Thu, Jan 30, 2003 at 08:13:30PM -0500, Tom Lane wrote:
> Kurt Roeckx <Q(at)ping(dot)be> writes:
> > On Thu, Jan 30, 2003 at 11:28:41AM -0500, Tom Lane wrote:
> >> We have to work out what the semantics should be. I don't know anything
> >> about v6, but I'd imagine v4 addresses form a defined subset of the v6
> >> address space ... if so the semantics seem pretty straightforward.
>
> > You have a "ipv4 mapped ipv6 address". The ipv4 address 1.2.3.4 becomes
> > ::ffff:1.2.3.4. But I'm not really in favour of automatically
> > changing an ipv4 address to an ipv6 address. And you really
> > shouldn't return an ipv4 address as an ipv6 address.
>
> No, we should keep the distinction for purposes of storage and display.
> The question was about what the semantics should be when comparing v4
> and v6 addresses in operations like network_sub. It seems perfectly
> reasonable to convert the v4 address to the mapped v6 equivalent and then
> do a v6 comparison in that situation. Do we have any operators where
> this would not be a sensible definition?

broadcast() doesn't make sense for ipv6. There is no such thing.
network() might be useful, but mean something a little bit
different.

Ipv6 calls the mask length the prefix length ...

abbrev() might also need some tweaking, specially in combination
with the compressed format. Not sure if abbrev() is really
useful.

There seems to be no documentation on network_sub, but I assume
it's the same as "<<". It shouldn't be a problem converting it
to the ipv6 address, and adding 96 to the mask.

Kurt