Re: [Doh] [Ext] DNS Camel thoughts: TC and message size
Ray Bellis <ray@bellis.me.uk> Fri, 08 June 2018 10:27 UTC
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From: Ray Bellis <ray@bellis.me.uk>
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Date: Fri, 08 Jun 2018 11:27:17 +0100
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Subject: Re: [Doh] [Ext] DNS Camel thoughts: TC and message size
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On 08/06/2018 10:34, Patrick McManus wrote: > Even for that I would appreciate a citation of where the problem lays > - there isn't agreement that wireformat actually has such a limit > (though its existing transports do and maybe that's what should be > noted), and no particular implementation choices, much less widely > deployed and hard to upgrade implementations, have been cited (again > - I'm not saying they don't exist.). There are likely numerous existing DNS implementations that currently assume that a 64kB buffer is large enough for any possible DNS message. I know I've written code that does that, because notwithstanding it's a limitation of UDP and a limitation of the chosen framing mechanism used when carried in TCP (but not of TCP itself, mind), it *is* the defacto limit on the size of a DNS message. I can allocate a buffer of 64kB, even on the stack, safe in the knowledge that it's "big enough". It's a trivial amount of RAM by today's standards but it avoids a lot of dynamic buffer allocation and/or re-sizing. I would also be unsurprised to find DNS server software with enforced 64kB limits on the total size of an RRset. Whilst I believe AXFR does permit RRsets to be split across message boundaries, the QUERY opcode does not (they have to be treated as a single atomic unit) so RRsets that exceed that size are effectively useless. I would be OK with special case treatment for AXFR in DOH, but *please* don't mess with the normal message size constraints for standard queries. Ray
- Re: [Doh] Are we missing an architecture? (was Re… Patrick McManus
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Puneet Sood
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Ted Lemon
- Re: [Doh] [Ext] Are we missing an architecture? (… Ted Lemon
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Ted Lemon
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Mateusz Jończyk
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Sara Dickinson
- Re: [Doh] [Ext] Are we missing an architecture? (… Daniel Stenberg
- Re: [Doh] [Ext] Are we missing an architecture? (… Sara Dickinson
- Re: [Doh] [Ext] Are we missing an architecture? (… Daniel Stenberg
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Ray Bellis
- Re: [Doh] [Ext] Are we missing an architecture? (… Patrick McManus
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Ben Schwartz
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Mukund Sivaraman
- Re: [Doh] [Ext] Are we missing an architecture? (… Ben Schwartz
- Re: [Doh] [Ext] Are we missing an architecture? (… Petr Špaček
- Re: [Doh] [Ext] Are we missing an architecture? (… Ray Bellis
- Re: [Doh] [Ext] Are we missing an architecture? (… bert hubert
- Re: [Doh] [Ext] Are we missing an architecture? (… Ray Bellis
- Re: [Doh] [Ext] Are we missing an architecture? (… Dave Lawrence
- Re: [Doh] [Ext] Are we missing an architecture? (… Dave Lawrence
- Re: [Doh] [Ext] Are we missing an architecture? (… Paul Hoffman
- Re: [Doh] [Ext] Are we missing an architecture? (… Tom Pusateri
- [Doh] DNS Camel thoughts: TC and message size bert hubert
- Re: [Doh] DNS Camel thoughts: TC and message size Petr Špaček
- Re: [Doh] DNS Camel thoughts: TC and message size Tony Finch
- Re: [Doh] DNS Camel thoughts: TC and message size Hewitt, Rory
- Re: [Doh] DNS Camel thoughts: TC and message size Benno Overeinder
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… George Michaelson
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Paul Hoffman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Tony Finch
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… bert hubert
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Paul Hoffman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Martin J. Dürst
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Paul Hoffman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Tony Finch
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Ray Bellis
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Ray Bellis
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… bert hubert
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Robert Edmonds
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Mateusz Jończyk
- [Doh] AXFR as several messages Re: [Ext] DNS Came… bert hubert
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… John Dickinson
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Ray Bellis
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Mukund Sivaraman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Mukund Sivaraman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Tony Finch
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Martin Thomson
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Mark Nottingham
- [Doh] DNS Camel thoughts: TC and message size Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Ólafur Guðmundsson
- [Doh] Are we missing an architecture? (was Re: DN… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… bert hubert
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] Are we missing an architecture? (was Re… Mark Nottingham
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Mukund Sivaraman
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] Are we missing an architecture? (was Re… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Andrew Sullivan
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Patrick McManus
- Re: [Doh] [Ext] DNS Camel thoughts: TC and messag… Dave Lawrence
- Re: [Doh] Are we missing an architecture? (was Re… Dave Lawrence
- Re: [Doh] Are we missing an architecture? (was Re… bert hubert
- Re: [Doh] Are we missing an architecture? (was Re… Dave Lawrence
- Re: [Doh] [Ext] Are we missing an architecture? (… Ray Bellis