[Curdle] Ben Campbell's Discuss on draft-ietf-curdle-ssh-ext-info-12: (with DISCUSS and COMMENT)

[Ben Campbell <[e-mail]>]

Ben Campbell has entered the following ballot position for
draft-ietf-curdle-ssh-ext-info-12: Discuss

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DISCUSS:
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I plan to ballot "yes", but I want to discuss one point first. Alexey mentioned
this in his comments, but I think it's discuss worthy. Hopefully it's an easy
fix, and it may well be because I've missed something obvious. If people think
it really, really needs to be this way, I will clear--but I want to discuss it
first:

- 2.5: The relative order in which extensions appear in an
  EXT_INFO message MUST be ignored by default; but an extension MAY
  specify that the order matters for that extension, in a specific way.

I don't think allowing specific extensions to add ordering requirement works.
It opens up the possibility of incompatible ordering requirements across
extensions. As far as I can tell, the only control over this is the "IETF
Consensus" requirement for adding new extensions. I'm open to arguments that
this is good enough, but my knee-jerk response is that it puts an undue burden
on the consensus process for little return.


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COMMENT:
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Substantive:

-2.3: "This message is sent immediately after SSH_MSG_NEWKEYS, without delay."
That seems to be contradicted in section 2.4, which talks about two other
potential times.

-2.4, last paragraph (asterisk note): "The message MUST be sent at this point
for the following reasons:" That's a confusing use of MUST. Do you mean that
the message MUST NOT be sent unless the reasons are true? Or that if the
reasons are true, the message MUST be sent? Or is this just a statement of
fact, in which case the 2119 keyword is not appropriate?

-2.5, 2nd paragraph: "or it MAY be sufficient that only one party includes it"
That seems like a statement of fact rather than a grant of permission. If so,
the 2119 MAY is not appropriate.

Editorial:

-2.1, first paragraph: "Applications implementing this mechanism MUST add to
the field
  "kex_algorithms", in their KEXINIT packet sent for the first key
  exchange, one of the following indicator names:"

That's hard to parse.  Suggestion:
"Applications implementing this mechanism MUST add one of the
 following indicator names to the "kex_algorithms" field for the first
 key exchange:"

-2.5, 2nd to last paragraph: "... applications MUST
  tolerate any sequence of bytes; including null bytes at any position;
  in an unknown extension’s extension-value."

Redundant to similar normative statement in 2.3.