Re: [Int-dir] Review of draft-ietf-6man-rdnss-rfc6106bis-14

["Mr. Jaehoon Paul Jeong" <[e-mail]>]

Hi Bob Halley,
Thanks for your technical review on our draft.

Your suggested padding with 0xff may make some confusion.
According to RFC 1035 (Domain Names - Implementations and Specification),
https://www.ietf.org/rfc/rfc1035.txt,
the compression scheme in Section 4.1.4 uses a pointer in the form of a two
octect
sequence of 2-bit "11" and 14-bit "Offset" where Offset specifies an offset
from
the start of the pointed domain name in the message.

I prefer to use the current padding with 0x00.
Though a one octet of 0x00 indicates the root domain, the root domain is
usually not
announced by a DNS search list.
Therefore, the octets of 0x00 can be regarded as padding.

Thanks.

Best Regards,
Paul

On Thu, Oct 13, 2016 at 8:32 PM, Bob Halley <[e-mail]> wrote:

> I am an assigned INT directorate reviewer for
> draft-ietf-6man-rdnss-rfc6106bis-14.  These comments were written
> primarily for the benefit of the Internet Area Directors. Document editors
> and shepherd(s) should treat these comments just like they would treat
> comments from any other IETF contributors and resolve them along with any
> other Last Call comments that have been received. For more details on the
> INT Directorate, see http://www.ietf.org/iesg/directorate.html.
>
> I read the document and I didn’t find any significant issues.
>
> My only quibble is with the description of the “Domain Names of DNS Search
> List” in section 5.2, where the padding is done with zero octets.  The text
> neglects the meaning of the zero octet at the end of domain names, namely
> that it is the root label.  The root label is, by itself, also a valid
> domain name.  So it’s wrong to say
>
> “Because the size of this field MUST be a multiple of 8 octets, for the
> minimum multiple including the domain name representations, the remaining
> octets other than the encoding parts of the domain name representations
> MUST be padded with zeros.”
>
> because both the search list values and the pad values are domain name
> representations.  What you’re really doing here is “padding with the root
> name”, with the understanding that the root name would not be part of a
> search list.  I think that’s a reasonable restriction, as I’ve never heard
> of anyone using the root name on a search list.
>
> I’m ok with this padding method, but I’ll point out another alternative,
> which is to pad with 0xff, which cannot be the start of a domain name.  (In
> theory domain names could be extended to use those bits, but experience
> with “binary labels” showed this doesn’t work in the real world; there’s no
> good way to do the transition.)
>
> /Bob
>
>
>
>
>


-- 
===========================
Mr. Jaehoon (Paul) Jeong, Ph.D.
Assistant Professor
Department of Software
Sungkyunkwan University
Office: [phone]
Email: [e-mail], [e-mail]
Personal Homepage: http://iotlab.skku.edu/people-jaehoon-jeong.php
<http://cpslab.skku.edu/people-jaehoon-jeong.php>