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On 11/02/2012 06:17 AM, Jasper Bongertz wrote:
> On 02.11.2012 04:23, Guy Harris wrote:
>
>>> Is it legal to have a pcap-ng file that contains a block with options
>>> that does not contain an opt_endofopt option?
>
>> My inclination would be to say "yes", to indicate that option processing
>> must stop when you reach the end of the block even if no opt_endofopt
>> option is seen, but also indicate that option processing should stop when
>> an opt_endofopt block is seen, even if there is more data remaining in
>> the block. So my inclination would be to say:
>
>> option processing MUST stop when you run out of data in the block;
>
>> option processing MUST stop when you see an opt_endofopt block;
>
>> option lists that contain at least one non-opt_endofopt option SHOULD
>> also have an opt_endofopt option at the end;
>
>> and possibly change the last SHOULD to MUST in order not to upset code
>> that *doesn't* check for the end of the block, even if that code is
>> insecure.
>
> I agree. The opt_endofopt is a nice-to-have in my eyes, because - as Guy
> said - you need to check that your code is not running past the end of a
> block anyway, and that requires keeping track of where you are.
>
> I think we can go for a "MUST" on the last one as well; code that reads
> pcap-ng still has to expect that there is no opt_endofopt because of the
> first rule.
>
Thanks everybody for your answers, I now know what to do.
But I think that this kind of redundancy, that can only create
interoperability issues or security vulnerabilities, should not appear in a
newly designed file format. Is there a process existing to evolve this
format? The spec has been written with IETF tools, but I cannot find a
submission for it. I can help navigate the IETF process if there is an
interest in pushing this spec as a standard. I think that this is typically
the kind of thing that can be improved by the reviews from IETF members, and
IANA is a good place for the various registries required.
- --
Marc Petit-Huguenin
Email: marc@xxxxxxxxxxxxxxxxxx
Blog: http://blog.marc.petit-huguenin.org
Profile: http://www.linkedin.com/in/petithug
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