On 2/1/2024 8:34 PM, John Levine wrote:
I can see that you have strong opinions about what a DKIM verifier
should do with those non-5322 blobs, but I don't see what the basis
for that is, and for that matter, I don't really understand what you
expect code to do with them. Why is "stop and report failure" any
less valid than anything else?
I thought I supplied the key point in my response to Jon:
A 5322 processor gets to decide what is a valid message. That's not
DKIM's job. And DKIM has no inherent reason to care about CR or LF on
their own, as distinct from any other character on its own.
You moved things to the concept of layering, which wasn't quite the
concern I was raising, but is probably reasonable as an encompassing
construct.
You claimed DKIM has never conformed to layering and I asked you to
explain. I explained why there is no obvious basis for your assessment,
especially since the example you gave appears to have nothing to do with
layering, given that what you cited is something entirely internal to DKIM.
I didn't see a clarification from you, about this.
But since these foundational points aren't sufficient for you, I'll
elaborate, although having to discuss the benefits of design and coding
discipline is a bit surprising. It made sense 40 or 50 years ago, when
software engineering was an emerging discipline, but I'd thought the
industry was a bit more mature than that by now.
Having a DKIM module check for one aspect of RFC5322 conformance --
raises a need to make it a full RFC5322 compliance engine.
If it doesn't, then the attention to compliance is a random walk
through whatever concerns are fashionable at the moment. That is, is
sprinkles stray bits of compliance code in a place that won't be -- and
shouldn't be -- expected to have it.
As maintenance nightmares go, over the long term, this is a pretty
classic example. As things related to RFC5322 change over time, and
personnel changes remove specialized knowledge, it will not be obvious
to check whether this module needs changing.
When a DKIM module is invoked, it should be invoked with necessary input
validation checking already done. If it hasn't been, then there are
larger system problems that stray bits of code in the DKIM module won't fix.
d/
ps. Yes, I do have strong feelings about thoughtful design discipline.
It usually produces cleaner, simpler, clearer results.
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net
mast:@dcrocker@mastodon.social
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