> On Nov 2, 2024, at 8:35 PM, Paul Vixie <paul=40redbarn....@dmarc.ietf.org>
> wrote:
>
> The version number in the initiation is the one that the initiator is
> expecting in the response. Probably should have made that an array.
>
>
> On Nov 2, 2024 19:54, Dave Lawrence <t...@dd.org> wrote:
> I agree with your reading. 6.1.3 seems quite clear that request = 0
> and response = 0-255 is legit.
(Responding to both messages above...)
So with the following text:
If a responder does not implement the VERSION level of the
request, then it MUST respond with RCODE=BADVERS. All responses
MUST be limited in format to the VERSION level of the request, but
the VERSION of each response SHOULD be the highest implementation
level of the responder. In this way, a requestor will learn the
implementation level of a responder as a side effect of every
response, including error responses and including RCODE=BADVERS.
If requestor sends VERSION 0, responder can send VERSION 0 - 255. Got it.
But when is RCODE=BADVERS expected from the responder? Two scenarios to
consider:
1. Requestor sends VERSION n, responder sends VERSION < n
2. Requestor sends VERSION n, responder sends VERSION > n
It seems to me that in case 1, RCODE=BADVERS is always expected.
In case 2, it depends on your reading. If a responder implements level n, does
it implement all versions < n? If so, then RCODE=BADVERS never makes sense.
Otherwise, the responder's RCODE depends on whether or not they implement
VERSION n; thus, the RCODE cannot be definitively predicted by the requestor.
My reading of the spec seems to imply the former, but Paul's response seems to
imply the latter.
Casey_______________________________________________
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