Wireshark-dev: Re: [Wireshark-dev] Checksum filterable fields

From: Alexis La Goutte <alexis.lagoutte@xxxxxxxxx>
Date: Tue, 2 Jul 2013 21:03:12 +0200
Hi Michael,

Good topic !
I thought the same thing when I changed the vrrp dissector (about checksum).
I looked all dissectors and as you say every dissector is different about checksum...


my idea is to create a proto_tree_add_checksum and pass in arg : checksum, chucksum_computed, hf_..._cheskum, hf_..._good, hf_..._bad, ei_...checksum...)

Regards,


On Thu, Jun 27, 2013 at 10:13 PM, <mmann78@xxxxxxxxxxxx> wrote:
I logged something into Bugzilla for now (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=8859) if anyone has any other thoughts.  I have too many other half-completed "ideas" resulting in too many changed files to tackle this now in one swoop. 
 
As for the coloring rule, thanks for the heads up, but I think I should be able to update them accordingly, possibly using the "expert info" (display) filter instead of the pure dissector display filter.
-----Original Message-----
From: Christopher Maynard <Christopher.Maynard@xxxxxxxxx>
To: wireshark-dev <wireshark-dev@xxxxxxxxxxxxx>
Sent: Thu, Jun 27, 2013 3:38 pm
Subject: Re: [Wireshark-dev] Checksum filterable fields

 <mmann78@...> writes:

> Perhaps all checksum validations could be an enumeration of 
> "-1" (or "2"?) - unknown/disabled
> "0" - good
> "1" - bad

The TCP dissector does something similar for the window scaling factor.  If
the 3-way handshake isn't captured, then the scaling factor is unknown and
set to -1.  So, there is some precedence at indicating unknown values using
-1, and if changes are to be made, then -1 would be my vote.

> If we're already going to take a hit with changed display filter names in
the name of consistency, why not go all the way?

I like consistency, so it's fine by me.  Just my 2 cents though.

Removing the bad_checksums does have at least 1 drawback though, and that's
that several of them are used in default coloring rules, so if they're
removed, users will likely end up with several warnings of the form:

Warn Could not compile color filter "Checksum Errors" from saved filters:
"<protocol>.checksum_bad" is neither a field nor a protocol name.



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