Re: [Doh] [Ext] DNS Camel thoughts: TC and message size

Andrew Sullivan <ajs@anvilwalrusden.com> Thu, 07 June 2018 21:48 UTC

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From: Andrew Sullivan <ajs@anvilwalrusden.com>
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Subject: Re: [Doh] [Ext] DNS Camel thoughts: TC and message size
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On Thu, Jun 07, 2018 at 01:21:23PM -0400, Dave Lawrence wrote:
> 
> "Sort of".  Wire format itself does not have the limitation.  Its use
> on certain transports does.  This distinction needs to keep being
> made.

That sounds like a foot-gun loaded for bear, to me.  Wire format on
every transport so far has this limitation.  Even if you break that
limitation (and I'm still not fully convinced you can), the mere fact
that this is called the "wire format" will lead people to expect that
they can pop in the very same parsing code they already use for the
"traditional" wire format, and it'll work fine.  So, if the document
is not going to set the limit in concrete, it had better have a Big
Giant Warning section that points out that a completely reasonable
assumption is not true and that the competent implementer will have to
do a bunch of additional work to be safe in a corner condition that is
incredibly rare right now.

What will actually happen, of course, is that some programmer will
say, "Aw, nobody's going to do that," fail to check the bounds
carefully, and create some festering large problem somewhere down the
road.

Best regards,

A

-- 
Andrew Sullivan
ajs@anvilwalrusden.com