Re: [Iot-directorate] [Last-Call] Iotdir telechat review of draft-ietf-core-dev-urn-09

Russ Housley <housley@vigilsec.com> Thu, 07 January 2021 13:06 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Thu, 07 Jan 2021 08:06:34 -0500
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To: Barry Leiba <barryleiba@computer.org>
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Subject: Re: [Iot-directorate] [Last-Call] Iotdir telechat review of draft-ietf-core-dev-urn-09
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Barry:

You are, of course, correct.  RFC 5234 says:

      ABNF strings are case insensitive and the character set for these
      strings is US-ASCII.

However, that raises a different issue:

   The DEV URN syntax allows both upper and lower case characters.  The
   URN-equivalence of the DEV URNs is defined per [RFC8141] Section 3.1,
   i.e,. two URNs are URN-equivalent if their assigned-name portions are
   octet-by-octet equal after applying case normalization to the URI
   scheme ("urn") and namespace identifier ("dev").

So, the ABNF should be changed so that the "mac:", "ow:", "org:", "os:", and "ops:" are required to be lowercase.  I guess that means replacing each letter with the appropriate value in the %x61-7A range.  That will not be as easy to read...

Russ


> On Jan 6, 2021, at 4:49 PM, Barry Leiba <barryleiba@computer.org> wrote:
> 
> Thanks for the quick review, Russ, and good catches here.
> 
> On one item, though:
> 
> > If both cases are to be supported, the upper case letters need to be
> > added to the ABNF to permit them.
> 
> 
> Actually not: quoted letters in ABNF are case-insensitive, so “a” matches both lowercase a and uppercase A.
> 
> Barry
> 
> On Wed, Jan 6, 2021 at 4:41 PM Russ Housley via Datatracker <noreply@ietf.org <mailto:noreply@ietf.org>> wrote:
> Reviewer: Russ Housley
> Review result: Almost Ready
> 
> I reviewed this document as part of the IoT Directorate's effort to
> IoT-related IETF documents being processed by the IESG.  These comments
> were written primarily for the benefit of the Internet Area Directors.
> Document authors, document editors, and WG chairs should treat these
> comments just like any other IETF Last Call comments.
> 
> Document: draft-ietf-core-dev-urn-09
> Reviewer: Russ Housley
> Review Date: 2021-01-06
> IETF LC End Date: 2020-12-02
> IESG Telechat date: 2021-01-21
> 
> 
> A review from the IoT Directorate was requested on 2021-01-05, which is
> after the IETF Last Call ended.  I assume that the Internet ADs want
> this review to help inform them during IESG Evaluation.
> 
> 
> Summary: Almost Ready
> 
> 
> Major Concerns:
> 
> Section 3.2 says:
> 
>    The optional underscore-separated components following the hexstring
>    are strings depicting individual aspects of a device.
> 
> Not all of the DEV URN forms contain a hexstring; however, all of them
> are allowed to end with underscore-separated components.  I suggest:
> 
>    The optional underscore-separated components at the end of the
>    DEV URN depict individual aspects of a device.
> 
> Section 3.2.1 says:
> 
>    ... and a MAC address could be represented either with
>    uppercase or lowercase hexadecimal digits.
> 
> This is not allowed by the ABNF:
> 
>    hexstring = 1*(hexdigit hexdigit)
>    hexdigit = DIGIT / "a" / "b" / "c" / "d" / "e" / "f"
> 
> If both cases are to be supported, the upper case letters need to be
> added to the ABNF to permit them.
> 
> Section 4.2 says:
> 
>    ... 
>    64-bit identifier that consists of 8 byte family code, 48 bit
>    identifier unique within a family, and 8 bit CRC code [OW].
> 
> The math does not work.  I suspect: s/8 byte/8 bit/
> 
> Section 6 says:
> 
>    ... An implementation of the DEV URN MUST NOT
>    change these properties from what they were intended.
> 
> It is not clear to me the meaning of "they" in this sentence.
> Please clarify.
> 
> 
> Minor Concerns:
> 
> Section 3.2 says:
> 
>    DEV URNs do not use r-, q-, or f-components.
> 
> I would have liked a bit more context here.  I suggest:
> 
>    DEV URNs do not use r-, q-, or f-components as defined in [RFC8141].
> 
> Section 3.2.1 refers to "BASE64".  Please add an informative reference
> to RFC 4648 to be clear.
> 
> Section 4.1 uses the term "Ethernet" in two places.  I think both of
> them should be replaced by "MAC-48".
> 
> 
> Nits:
> 
> Section 3.2 says:
> 
>    However, due to the SenML RFC 8428 Section 4.5.1 rules, DEV URNs
>    do not support percent-encoding.
> 
> This does not seem like a "however" statement to me.  Perhaps, it is
> a "Note that" statement.  Or, just drop "However".
> 
> Section 4.1: s/rests within the IEEE/
>               /rests with the IEEE Registration Authority/
> 
> Section 7 includes: "publicly available specification that can
> be pointed to."  It is sufficient to say: ""publicly available
> specification."
> 
> 
> 
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