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Re: [Ltru] Issue #62: (AD #14) DoS potential



[hats on]

I have counted five people (this includes Randy, who commented on the general agreement with the need of doing something here in private) in favor of adding the two text pieces below, and nobody against.

I would like to ask the editors to integrate these texts into the newest version of their draft, and Randy to close this issue.

Regards,    Martin.

On 2009/06/10 1:51, Phillips, Addison wrote:
(as contributor)

+1.

Addison Phillips
Globalization Architect -- Lab126

Internationalization is not a feature.
It is an architecture.

From: mark.edward.davis at gmail.com [mailto:mark.edward.davis at gmail.com] On Behalf Of Mark Davis
Sent: Tuesday, June 09, 2009 9:27 AM
To: Peter Constable
Cc: "Martin J. Dürst"; Phillips, Addison; Alexey Melnikov; LTRU Working Group
Subject: Re: [Ltru] Issue #62: (AD #14) DoS potential (was: Re: AD issue #14 (DoS potential) Additional issues with 4646bis raised by an Apps Review Team review)

I agree with Peter.

Mark

On Tue, Jun 9, 2009 at 09:20, Peter Constable<petercon at microsoft.com<mailto:petercon at microsoft.com>>  wrote:
From: ltru-bounces at ietf.org<mailto:ltru-bounces at ietf.org>  [mailto:ltru-bounces at ietf.org<mailto:ltru-bounces at ietf.org>] On Behalf Of "Martin J. Dürst"

Although the specification of valid subtags for an extension (see
Section 3.7 (Extensions and the Extensions Registry)) MUST be
available over the Internet, implementations SHOULD NOT mechanically
depend on it being always accessible, to prevent denial-of-service
attacks.
--

This should also address the IANA registry. I think that's an
oversight. I actually thought it said both.
Okay. Here is proposed text for insertion just before the currently
last paragraph in section 6:

Although the Language Subtag Registry and the Language Tag Extensions
Registry are available over the Internet, applications SHOULD NOT
mechanically depend on it being always accessible, to prevent
denial-of-service attacks.
That text looks OK to me.



I agree that there is no evidence that a language tag implementation
currently does frequent downloads. But there is evidence for other cases
of frequent downloads, where the frequency of changes is way smaller or
non-existent.

I therefore suggest to continue the text I proposed above as follows:

The registries specified in this document are not suitable for frequent
or real-time access to, or retrieval, of the full registry contents.
Most applications do not need registry data at all. For the others,
being able to validate or canonicalize language tags as of a particular
registry date will be sufficient. Also, the registry contents changes
only occasionally. Changes are announced to
ietf-languages-announcements at iana.org<mailto:ietf-languages-announcements at iana.org>. Changes, or the absence thereof,
can also easily be detected by looking at the File-Date record at the
start of the registry, or by using features of the protocol used for
downloading, without having to download the full registry.
That also looks OK to me.


It might also be worth discussing how the registry format
facilitates "diffing" 2 versions of the registry.
It's possible, although once you've parsed the new registry,
the diff doesn't matter so much. Note that stability rules
generally prevent breaking changes.

I think what Alex means is that the diff would significantly reduce the
amount of data that needs to be downloaded to update the registry to a
new version.
But if we're directing implementations not to do real-time automated downloads, then it seems that the amount of data shouldn't be that much of an issue.


Overall, I agree that we have discussed this issue before, but I also
understand that Alex is concerned, probably not only by himself, but
also about the fact that his fellow IESG members might easily bring up
this issue as a "discuss". So I think it's better to have it clearly
documented in the security section.
That seems reasonable, and I think the text you suggested covers the key issues.



Peter

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--
#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-# http://www.sw.it.aoyama.ac.jp   mailto:duerst at it.aoyama.ac.jp

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