dhcpcd-discuss

On 29/04/2014 14:56, Jouke Witteveen wrote:
> On Tue, Apr 29, 2014 at 1:09 AM, Roy Marples <roy@xxxxxxxxxxxx> wrote:
> > On 28/04/2014 22:03, Jouke Witteveen wrote:
> > > In netctl, IPv4 and IPv6 are configured separately. In principle,
> > > users could choose to use a different dhcp client for both versions 
> > > of
> > > the IP. When netctl goes through the IPv4 configuration stage, it
> > > might start dhcpcd for IPv4. Later, in the IPv6 stage, it might want
> > > to start dhcpcd for IPv6. If the client would have been dhclient in
> > > both cases, this means there will be two instances of dhclient
> > > running. One for the IPv4 address and one for the IPv6 address. These
> > > instances can be tinkered with independently. For dhcpcd, it would be
> > > nice if there was some form of introspection possible to allow IPv6 
> > > to
> > > be added to the responsibilities of a running IPv4 instance.
> > >
> > > If you find this approach is flawed to begin with, that is okay.
> >
> >
> > It's a perfectly valid approach if you like a daemon per interface per
> > protocol.
> > I personally find that a little bloated, one daemon to manage all 
> > interfaces
> > and protocols :)
>
> The profile-based nature of netctl is actually quite nice and you can
> hardly call its source bloated :-).

I was referring to it running seperated daemons per protocol, not netctl 
itself.
I've never seen its code, so I don't have an opinion if it's bloated or 
not and will have to take your word for it.

> > > However, dhcpcd itself has a rather clean separation of the
> > > implementation on both protocols, so my request might not be too hard
> > > to implement (although I couldn't see a trivial fix).
> >
> > Yes, it's clean and it's fairly trivial to implement via enabling the
> > control socket per interface,
> > but lets consider the command line.
> >
> > dhcpcd -4 == IPv4 only
> > dhcpcd -6 == IPv6 only
> >
> > So, if dhcpcd starts with -4 and is then later called with -6, what is 
> > the
> > expectation?
> > My expectation is that IPv4 is stopped and IPv6 is started. If you 
> > want to
> > run both protocols then you should use dhcpcd -46.
> > This keeps consistency with the current control socket implementation.
>
> I was thinking of something like '--extend-functionality-with=ipv6' as
> a new parameter.
> I believe -46 doesn't work (not tested, just from reading the source),
> which is in line with what the man page tells.

You are correct in that -46 doesn't currently work.

> > Another approach would be to add another option to instruct dhcpcd to 
> > use a
> > different pidfile per protocol.
> > This is infact the better solution currently because when dhcpcd 
> > writes to
> > it's control socket it returns immediately instead of waiting for the
> > protocol to be configured.
>
> Or just un-hardcode the pidfile in general. I don't know if dhcpcd
> will play nice with multiple instances of itself on the same
> interface, but I don't immediately see why it wouldn't.

Yes it will play nice, but then nothing stops you from accidentally 
launching N copies of itself.
Would netctl be happy with this?

dhcpcd --per-protocol -4 eth0
dhcpcd --per-protocol -6 eth0

dhcpcd --per-protocol -4 -x eth0
dhcpcd --per-protocol -6 -x eth0

Would create the pidfiles:
/var/run/dhcpcd-eth0.pid
/var/run/dhcpcd-eth0.6.pid

That would be fairly trivial to implement.
Let me know

Thanks

Roy