Ethereal-dev: [Ethereal-dev] Re: recursive taps

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From: "Pia Sahlberg" <piabar@xxxxxxxxxxx>
Date: Wed, 30 Oct 2002 02:41:40 +0000
From: Jason House Subject: recursive taps
Date: Tue, 29 Oct 2002 16:54:44 -0500

One example of how to use this would be generation of the traffic summary...
Say for instance the top level summary tap is called.
It looks at the first item in proto_tree and finds the entry who's filter
field/protocol is "frame"...
so it looks to see if it has a sub-tap for "frame" and creates it if it
doesn't already have one...
Then it calls that tap and passes in a pointer to the "frame" entry in
proto_tree.
    The next tap looks for the next top level entry and finds "ip"
    (optionally creates "ip" sub-tap)
    then calls the "ip" tap with a pointer to the "ip" entry in proto_tree
        This next tap sees "udp"
            The next one sees "rtp"
                ...


This example does not need recursive taps. It is sufficient to just tap on "frame" and build/maintain a linked tree in the tap extension. To find out the relation of protocols, ie which protocols are carried ontop of which other, just inspect the edt variable and update the state variables to the tap extension accordingly. There is no need to tap from anything else than "frame" for this type of extension.

In fact, it would be dead simple to do an extension like this and I can provide one in the next few days.


(in reply to other post)
Yes, multiple -z arguments are possible and have always been.
I use it daily and documented it in the manpages.


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