Wireshark-dev: Re: [Wireshark-dev] sigcomp - accessing state with a partial state id >6 bytes
From: "Anders Broman \(AL/EAB\)" <[email protected]>
Date: Tue, 28 Nov 2006 14:46:01 +0100
 

-----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.

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