Re: [PATCH v5 2/2] netfilter: nft_meta: support for time matching

[Jones Desougi <jones.desougi+netfilter@gmail.com>]

On Sun, Aug 18, 2019 at 8:22 PM Ander Juaristi <a@juaristi.eus> wrote:
>
> On 17/8/19 15:43, Jones Desougi wrote:
> >> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> >> index 82abaa183fc3..b83b62eb4b01 100644
> >> --- a/include/uapi/linux/netfilter/nf_tables.h
> >> +++ b/include/uapi/linux/netfilter/nf_tables.h
> >> @@ -799,6 +799,9 @@ enum nft_exthdr_attributes {
> >>   * @NFT_META_OIFKIND: packet output interface kind name (dev->rtnl_link_ops->kind)
> >>   * @NFT_META_BRI_IIFPVID: packet input bridge port pvid
> >>   * @NFT_META_BRI_IIFVPROTO: packet input bridge vlan proto
> >> + * @NFT_META_TIME_NS: time since epoch (in nanoseconds)
> >> + * @NFT_META_TIME_DAY: day of week (from 0 = Sunday to 6 = Saturday)
> >
> > This would be clearer as NFT_META_TIME_WEEKDAY. Just day can mean a
> > lot of things.
> > Matches nicely with the added nft_meta_weekday function too.
>
> I agree with you here. Seems to me WEEKDAY is clearer.
>
> >
> >> + * @NFT_META_TIME_HOUR: hour of day (in seconds)
> >
> > This isn't really an hour, so why call it that (confuses unit at least)?
> > Something like NFT_META_TIME_TIMEOFDAY? Alternatively TIMEINDAY.
> > Presumably the added nft_meta_hour function also derives its name from
> > this, but otherwise has nothing to do with hours.
> >
>
> But not so sure on this one. TIMEOFDAY sounds to me equivalent to HOUR,
> though less explicit (more ambiguous).

HOUR is a unit, much like NS, but its use is quite different with no
clear hint as to how. Unlike the latter it's also not the unit of the
value. From that perspective the name comes up empty of meaning. If
you already know what it means, the name can be put in context, but
that's not explicit at all.

That said, weekday is more important.


>
> >>   */
> >>  enum nft_meta_keys {
> >>         NFT_META_LEN,
> > ...
> >
>
>