[libvirt] [PATCH] remote: fix systemd IP socket activation with virtproxyd

[Daniel P. Berrangé]

On Wed, Sep 25, 2019 at 09:42:57AM +0200, Erik Skultety wrote:
> On Tue, Sep 24, 2019 at 04:07:17PM +0100, Daniel P. Berrangé wrote:
> > We recently forbid the use of --listen with socket activation:
> >
> >   commit 3a6a725b8f575890ee6c151ad1f46ea0ceea1f3b
> >   Author: Daniel P. Berrangé <berrange at redhat.com>
> >   Date:   Thu Aug 22 14:52:16 2019 +0100
> >
> >       remote: forbid the --listen arg when systemd socket activation
> >
> > In this change we forgot that virtproxyd doesn't have a --listen
> > parameter, and instead behaves as if it was always present. Thus
> > when systemd socket activation is present, we must disable this
> > built-in default
> >
> > Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> > ---
> >  src/remote/remote_daemon.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/src/remote/remote_daemon.c b/src/remote/remote_daemon.c
> > index 7195ac9218..43409edd24 100644
> > --- a/src/remote/remote_daemon.c
> > +++ b/src/remote/remote_daemon.c
> > @@ -423,11 +423,20 @@ daemonSetupNetworking(virNetServerPtr srv,
> >          return -1;
> >
> >  #ifdef WITH_IP
> > +# ifdef (LIBVIRTD
> 
> ^fails to compile:
> s/(//

Sigh, clearly I didn't test :-(

> 
> >      if (act && ipsock) {
> >          VIR_ERROR(_("--listen parameter not permitted with systemd activation "
> >                      "sockets, see 'man libvirtd' for further guidance"));
> >          return -1;
> >      }
> > +# else /* ! LIBVIRTD */
> > +    /* We don't have a --listen arg with virtproxyd, we're just
> > +     * hardcoded to assume --listen. Thus with systemd we must
> > +     * change that default
> > +     */
> > +    if (act)
> > +        ipsock = 0;
> 
> I'm a bit confused with this bit wrt to what actually happens later in the
> code. Basically this @ipsock is only relevant up until the point where we start
> registering services listening for traffic e.g.virNetServerAddServiceTCP (this
> is one is easier as an example). If I look at the condition:
> 
> if (((ipsock && config->listen_tcp) || act) ...
> 
> why does it even matter that we clear ipsock when socket activation is enabled?
> The condition is true regardless of @ipsock and it's also not populated further
> into the function being called unlike @act, so this bit is making me confused,
> so what exactly is happening if we don't clear @ipsock with virtproxyd?

Currently there are *no* ill effects if we don't clear @ipsock. The
important bit of the patch is simply avoiding the VIR_ERROR in the
first part of the ifdef.  I chose to clear @ipsock, to reduce chance
of suprises later if we refactor again.

Regards,
Daniel
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