[LEAPSECS] stale leap second information

[Steffen Nurpmeso]

"Poul-Henning Kamp" <phk at phk.freebsd.dk> wrote:
 |--------
 |In message <20150114180119.qsYo2BoZ%sdaoden at yandex.com>, Steffen \
 |Nurpmeso write
 |s:
 |>|NTP is a much more specialized protocol than DNS and it is blocked
 |>|a lot of places.
 |>
 |>So i apologize, such a thing would indeed even be a great idea,
 |>fetchable via a simple getaddrinfo(3) / dig(1) call and
 |>automatically replicated from the DNS root servers down to the
 |>last zone!
 |
 |Bingo.
 |
 |Plenty of space for the data we need in an IPv4 'A' record, and
 |a human readable TXT record could supplement that.

Well who am i.
Of course an A record that points into some private range, say
192.168.X.Y, where "X & 0x80" would indicate the sign (fwiw),
would offer enough room.
If administrators would agree to offer
a (utcoffset|leapseconds).MYDOMAIN DNS entry, iana.org as the home
of the TZ database comes to mind as the master, ietf.org as
a penalty for doing it all wrong, and some BSD projects could
follow as well as some large Linux companies, then this could be
true tomorrow morning.
And not unlikely that the next TZ release happens pretty soon and
could also and already ship the necessary information along.

I am obviously the completely wrong person to cause any member of
that group of people to only raise a finger for that :-).

And permit nonetheless that i hope for a simple (UDP) time
protocol that distributes TAI plus the current leap second count
so to allow receivers to compute UTC themselves.
That however will take many years, in the best case.  Instead.

 |>(Of course DNSSEC is horrible, in my humble opinion.  And your
 |>scheme will have problems at and after the days which actually
 |>introduce leap seconds.  But just as is today for those computers
 |>which get their leap information only via the TZ database.)
 |
 |There is no problem if the message is "Next leap second is #N at
 |YYYY-MM" and after that changes to "Next leapsecond is #{N+1} at
 |unknown future date".

Well, if you ask me i would say two A records would be better, via
the subdomains leapcurrent. and leapnext., the latter of which
could now already point to the announced leap in June, and would
have simply aliased the former before and will do so thereafter.

 |I've seriously been contemplating offering such a service myself
 |in order to get reliable leap-second info in Ntimed...

I think your idea would be a real improvement.  Easy to have
almost for free today, and automatically maintainable, especially
if IANA (or even IERS) would agree in being the master provider.
And usable from all systems that i know of, internet access
provided.

--steffen