Re: [nft PATCH 1/2] monitor: Rewrite SETELEM callback

[Phil Sutter <phil@nwl.cc>]

On Mon, Jul 17, 2017 at 06:30:18PM +0200, Pablo Neira Ayuso wrote:
> On Mon, Jul 17, 2017 at 05:06:05PM +0200, Phil Sutter wrote:
> [...]
> > +static int netlink_events_setelem_newgen_cb(const struct nlmsghdr *nlh,
> > +					    int type,
> > +					    struct netlink_mon_handler *monh)
> > +{
> > +	setelem_cache_print_default(monh);
> > +
> > +	return MNL_CB_OK;
> >  }
> 
> I would really like we don't rely on newgen for this. If there is no
> way to catch a case with the existing way we represent this, then we
> probably need to fix things from the kernel.
> 
> Before we follow that patch, I would like to understand what corner
> case is pushing us to use the newgen event.

It is required for half-open ranges occurring at the end of the
transaction: For those, we only get a single element without
EXPR_F_INTERVAL_END flag set. Since this could also be the first part of
a regular range, monitor has to wait for what's next - which is in doubt
only the NEWGEN message.

Maybe we could introduce a new flag to mark these?

Cheers, Phil