[codec] Barry Leiba's No Objection on draft-ietf-codec-oggopus-13: (with COMMENT)

["Barry Leiba" <[e-mail]>]

Barry Leiba has entered the following ballot position for
draft-ietf-codec-oggopus-13: No Objection

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COMMENT:
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-- Section 3 --

   A demuxer SHOULD NOT attempt to decode the data for the
   first packet on a page with the 'continued packet' flag set if the
   previous page with packet data does not end in a continued packet
   (i.e., did not end with a lacing value of 255) or if the page
   sequence numbers are not consecutive, unless the demuxer has some
   special knowledge that would allow it to interpret this data despite
   the missing pieces.

This "SHOULD NOT" requirement is in a very long sentence with a few "ifs"
and "buts", which make it hard to see what's really being required. 
Rewording to put the conditions up front might help.  It'd also be good
to explain why it's SHOULD NOT, rather than, say, MUST NOT.  Under what
conditions might I want to decode the first packet anyway, and what are
the consequences of my doing that?  It looks like the "unless" clause is
there to explain that, in which case "MUST NOT ... unless" seems right.

For the rewording, maybe this?:

NEW
If a page has the "continued packet" flag set and one of the following
conditions is also true:
- the previous page with packet data does not end in a continued packet
(a lacing value of 255) OR
- the page sequence numbers are not consecutive,
then the demuxer SHOULD NOT attempt to decode the data for the first
packet on the page unless the demuxer has some special knowledge that
would allow it to interpret this data despite the missing pieces.
END

...and then consider whether it really should be "MUST NOT ... unless".

You should take similar action with the "SHOULD NOT" sentence in the next
paragraph as well, as it has the same convolution problem.

-- Section 5.2 --
In bullet 4, might it not be clearer to call it "User Comment List
Count", rather than "Length"?

In the list in general, I think it'd be clearer and more accurate to
group all the "MUST NOT indicate that there are so many..." sorts of
things into one one-sentence pargraph that says that the Vendor String
and all the User Comments, together, MUST fit into the packet.  No?

-- Section 9 --

   Malicious payloads MUST NOT cause an implementation to overrun its
   allocated memory or to take an excessive amount of resources to
   decode.
...
   Malicious audio input streams
   MUST NOT cause an implementation to overrun its allocated memory or
   consume excessive resources

It's a small thing, rather at the nit level, but it doesn't make much
sense to levy normative requirements on malicious actors.  These would be
much better if worded as requirements on the implementation, somewhat
like this:

NEW
Malicious payloads and/or input streams can be used to attack codec
implementations.  Implementations MUST NOT overrun their allocated memory
nor take an excessive amount of resources when decoding payloads or
processing input streams.
END

-- Section 11 --

   Modifications to this registry follow the "Specification
   Required with Expert Review" registration policy as defined in
   [RFC5226].

RFC 5226 does not define a policy with that name.  The name is just
"Specification Required"; please change this.  And thanks for the
paragraph giving guidance to the designated expert.