Re: SVN revision 36640 and heuristic dissectors

[Thomas Boehne <TBoehne () ADwin de>]

On 10/25/2010 05:05 PM, Pascal Quantin wrote:
> since revision 34640, none of UDP heuristic dissectors I use (LTE-MAC,
> LTE-RLC or LTE-PDCP) work: all the frames are decoded as ADwin
> configuration protocol.
>
> When looking at the code in function dissect_adwin_config() (file
> packet-adwin-config.c), the heuristic seems a bit weak:
> [...]
>     length = tvb_reported_length(tvb);
>
>     if (pinfo->ipproto == IP_PROTO_UDP &&
>         ! (length == UDPStatusLENGTH
>            || length == UDPExtStatusLENGTH
>            || length == UDPMessageLENGTH
>            || length == UDPMessageLENGTH_wrong
>            || length == UDPInitAckLENGTH
>            || length == UDPIXP425FlashUpdateLENGTH
>            || length == UDPOutLENGTH))
>         return (0);
> [...]
>
> Could it be possible to do something more robust ?

As discussed in https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5324
I will improve the heuristic using MAC address filtering (the protocol
is almost exclusively used with the embedded device we built, and we
have two MAC address ranges used for those devices).

Can/should regressions like this one be automatically detected using
test.sh?

Best regards
Thomas Böhne

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