Wireshark-dev: Re: [Wireshark-dev] sigcomp - accessing state with a partial state id >6 bytes
From: cco <[email protected]>
Date: Wed, 29 Nov 2006 09:50:21 +0100
On Tue, Nov 28, 2006 at 02:46:01PM +0100, Anders Broman (AL/EAB) wrote:
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of cco
> Sent: den 28 november 2006 11:56
> To: Developer support list for Wireshark
> Subject: [Wireshark-dev] sigcomp - accessing state with a partial state
> id >6 bytes
> >hi!
> >
> >it seems that wireshark fails to access a previous saved state when the
> specified psi is longer than 6 bytes. and yes, >the state was saved at
> END-MESSAGE(); at least this is what the debug message reports.
> >
> >here is the scenario:
> >1. sigcomp pkt with bytecode is recv. sucessful decompression,
> END-MESSAGE makes a state create request. state is saved >(it seems that
> only the first six bytes of the state id are kept; no idea why) 2.
> sigcomp packet tries to access prev. >saved state with a partial state
> id. partial state id is longer than 6 bytes and wireshark fails. since
> one of the 
> >peers is able to decompress it I suspect there is a problem in
> wireshark.
> >
> >thanks!
> >bye now!
> >cristian
> Hi,
> Wireshark will save the state id with the minimum access length in it's
> hash table.
> I guess that later when that state of 6 bytes is compareth with a state
> of 8 bytes the comparison fails.
> I think that ought to be changed to save the full 20 bytes state id and
> the minimum access length
> And the comparisson should then be made on the actual state id length
> used, if greater then minimum length.

cristian: yes, this would be "Signaling Compression (RFC 3320)" compliant.

> I currently have little time to work on this you might want to file a
> bugzilla report on this 
> preferably with an example trace.

cristian: o.k. I will try that.

bye now!