Last Call Review of draft-ietf-6man-uri-zoneid-05

Request Review of draft-ietf-6man-uri-zoneid
Requested rev. no specific revision (document currently at 06)
Type Last Call Review
Team Security Area Directorate (secdir)
Deadline 2012-11-26
Requested 2012-11-18
Authors Brian Carpenter, Stuart Cheshire, Bob Hinden
Draft last updated 2012-11-29
Completed reviews Genart Last Call review of -05 by Martin Thomson (diff)
Genart Telechat review of -?? by Martin Thomson
Secdir Last Call review of -05 by Radia Perlman (diff)
Assignment Reviewer Radia Perlman
State Completed
Review review-ietf-6man-uri-zoneid-05-secdir-lc-perlman-2012-11-29
Reviewed rev. 05 (document currently at 06)
Review result Has Nits
Review completed: 2012-11-29


I have reviewed this document as part of the security directorate's 

ongoing effort to review all IETF documents being processed by the 

IESG.  These comments were written primarily for the benefit of the 

security area directors.  Document editors and WG chairs should treat 

these comments just like any other last call comments.


This document provides syntax for specifying a port within a URI for an IPv6 link-local address.

I find no security-specific issues with this draft, but I do think the clarity of the draft

could be improved a lot, and also, I think that the draft allows options of what is or is not allowed,

which could cause confusion for a human using this, since some strings will work sometimes.  I think it would

be better to lock down what is and is not allowed. 


I'm not fond of the term "zone identifier" (I had to do some Internet searching to figure out what it was). It would

only take a sentence to explain it in this draft.  Admittedly, not many people will be reading this draft out of

context (like me).


An example of where the wording is needlessly hard to read, and where I think the rule should be a MUST:


" A <zone_id> SHOULD contain only ASCII characters classified


RFC 3986

 as "unreserved", which conveniently excludes "]" in order

   to simplify parsing."


That wording could mean that ] is reserved or it could mean that it is not reserved.

Turns out (by referring to RFC 3986) "]" is actually reserved.

And also, with my preference for specifying mandatory behavior rather than recommendation...

perhaps saying something like


" A <zone_id> MUST NOT contain ASCII characters classified


RFC 3986

 as "reserved".  The character  "]" is reserved, so MUST NOT

  be used in the zone ID.





    "The rules in [


] SHOULD be applied in producing URIs."

Why not MUST be applied?



"we recommend that URI parsers accept bare "%" signs...make it easy for a user to copy and

paste a string..."


again, I'd think it would be better to specify what parsers MUST do, rather than saying some parsers

can be more lenient, so that the same string will create the same behavior regardless of the implementation

parsing it.





"To limit this risk, implementations SHOULD NOT allow use of this

   format except for well-defined usages such as sending to link local

   addresses under prefix fe80::/10."


I'd think it would be better to say MUST NOT, and also, to specify what it should

do if it receives such a thing.