Re: Acp 142 checksum algorithm

[Jaap Keuter <jaap.keuter () xs4all nl>]

Hi,

Reading the document [3], section Evolution (105 and 106) suggest that a whole
lot more was done to the protocol. I'm not sure if this has influenced the PDU's
themselves (apart from the checksum as you indicated), a more rigorous analysis
of the document would be required since no delta is described.

The best way to get attention to this is to collect relevant sample capture
files of the new protocol and open an enhancement bug in the Wireshark bugzilla
(https://bugs.wireshark.org) and attach this description and the sample capture
files there.

If someone picks up this bug (s)he then has all the info they need to get
started. However, the volunteer nature of this project does not provide
guarantees if and when this is going to be done (although Stig might not be able
to hold himself back ;) ).

Thanks,
Jaap


On 12/10/2014 10:10 PM, Ricardo Cristian Ramirez wrote:
> ACP 142 (PMul) protocol has two versions. The first one [1] was
> released at 2001 and the second one [2] was released at 2008. The
> first version suggests to use 8-bit Fletcher's algorithm, which
> produces 16 bit checksum. And, an implementation of this algorithm is
> provided in the specification. Current PMul dissector [3] of the
> Wireshark uses this provided algorithm.
>
> The checksum description in the second version was changed: Provided
> algorithm was removed and below statement is given without an
> algorithm:
> " The checksum field is the 16 bit one's complement of the one's
> complement sum of all 16 bit words in the header. "
>
> As far as I know, this statement decribes the TCP/IP checksum and an
> update is needed for PMul dissector.
>
>
> [1] jcs.dtic.mil/j6/cceb/acps/acp142/ACP142.pdf
> [2] jcs.dtic.mil/j6/cceb/acps/acp142/ACP142A.pdf
> [3] 
> https://code.wireshark.org/review/gitweb?p=wireshark.git;a=blob;f=epan/dissectors/packet-p_mul.c;h=a03e69f10825e6dacb82f3aacb33b465adeb721a;hb=HEAD


___________________________________________________________________________
Sent via:    Wireshark-users mailing list <wireshark-users () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-users
Unsubscribe: https://wireshark.org/mailman/options/wireshark-users
             mailto:wireshark-users-request () wireshark org?subject=unsubscribe