> On Jan 17, 2015, at 7:33 PM, Rob Seaman <[email protected]> wrote: > > On Jan 17, 2015, at 4:12 PM, Poul-Henning Kamp <[email protected]> wrote: > >> If you need the historical information, you can afford the TCP >> connection to IERS. > > There's also value in implementing a single ICD for all use cases, but point > taken.
So long as the file is signed (not just check-summed) that would work. Not all applications can do this, but many can. >> I'm focused on how NTP/PTP clients will be able to get/validate leapsecond >> information efficiently and reliably. > > The python script tests the encoded values: > > % ./leap.py > YYYY MM before after encoded crc IP Decoded > ------------------------------------------------------------------------- > 1972 1 9 10 f0002500 fb 240.0.37.251 -> OK 1972 1 +9 +1 > 1972 7 10 11 f0182900 b1 240.24.41.177 -> OK 1972 7 +10 +1 > 1973 1 11 12 f0302d00 45 240.48.45.69 -> OK 1973 1 +11 +1 > > but doesn't pair them with string addresses. Were you thinking like Warner > suggested, requesting feedback for a specific month/year? So a client would > poll at startup / reset / etc, but would need to understand the June/December > convention (and ignore the other technically legal months)? I think he’s looking to get just the current value as an IPv4 address. My notion was to tunnel the info over DNS, but I’m starting to think that’s a cool idea, but one that’s perhaps not as valuable in practice as one might hope. >>> Unless there is an overriding value in efficient encoding, >> >> There is. getaddrinfo(3) is almost always available and works >> about as well as any protocol on the internet can work. > > Doesn't getaddrinfo support IPv6, too? Parsing the longer string won't be > dramatically slower. Even at this late date, IPv6 isn’t universally supported. And many IPv4 only machines specifically compile out the IPv6 support and/or filter IPv6 replies. Warner
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