Wireshark-dev: Re: [Wireshark-dev] Regarding display filter- how to redesign code to incorporat
From: Ateeth Kumar Thirukkovulur <athirukkovulur@xxxxxx>
Date: Sat, 19 Apr 2014 13:58:58 -0500

Not exactly.

Suppose I want to include a NOT operator in the display filter. Say "! tcp". Which code must I change? I know it already exists. Where do I include the symbols n expressions for newly added terms.

Do you get what I am saying?

On Apr 18, 2014 4:38 PM, "Guy Harris" <guy@xxxxxxxxxxxx> wrote:

On Apr 18, 2014, at 2:13 PM, Ateeth Kumar Thirukkovulur <athirukkovulur@xxxxxx> wrote:

> I want to know if there is any way to redesign the wireshark filter to incorporate algebraic expressions instead of filtering using protocols?

Filtering *already* uses more than just protocols - it uses fields from protocols, for example, "ip.src == 127.0.0.1" or "ip.len == 1024".

An algebraic _expression_, in order to be a *useful* filter, would have to incorporate variables of some sort; neither "(5 + 3)*2 == 16" nor "(5 + 3)*2 == 17" are particularly interesting filters (the first one would match all packets, the second one would match no packets).

So you'd need some sort of variables; if the variables are fields from protocols, adding support for arithmetic operators, for example, "foo.len1 - foo.len2 == 30", isn't really a "redesign", it's just an enhancement.

Is that what you're talking about?
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