[LEAPSECS] stale leap second information

[Poul-Henning Kamp]

--------
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.

>(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".

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

>Iirc NTP will get storage overflow problems in the mid (20)30s,

Handling of that has been documented since at least NTPv3 a
couple of decades ago.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.