Re: Getting data from pinfo

[Guy Harris <guy () alum mit edu>]

On Apr 14, 2010, at 6:07 PM, Shawn Mayer wrote:

> I'm trying to get the IPs from an aim_messaging packet to pass to my 
> tap.

Presumably the AIM dissector is setting up the call to your tap.  If so, it should put the IP addresses into a data 
structure and pass that to the tap as private data; that's how other taps work.

> What exactly is pinfo

It's a (pointer to a) katamari:

        http://en.wikipedia.org/wiki/Katamari

"The game's plot concerns a diminutive prince on a mission to rebuild the stars, constellations, and Moon, which were 
accidentally destroyed by his father, the King of All Cosmos. This is achieved by rolling a magical, highly adhesive 
ball called a katamari around various locations, collecting increasingly greater objects, ranging from thumbtacks to 
people to mountains, until the ball has grown great enough to become a star."

The pinfo katamari has rolled around Ethereal/Wireshark for years, picking up various random bits of information to be 
passed between dissectors. :-)

If all of those were passed to dissectors as separate arguments, then

        1) the argument list to a dissector would change every time something else became part of the katamari

and

        2) a call to a dissector would probably take half a page of code just to pass the arguments.

> and what does it contain?

Everything that somebody's decided would be useful to put into it.  (Yes, that's a serious description.  There's 
nothing very systematic about it.)

> Should I avoid using it?

You should avoid just adding things if only your dissector and any taps for it would use them; it's for passing stuff 
between dissectors.  (And, yes, it probably should be cleaned up, with some more cleanly extensible mechanism for 
information-passing between dissectors.)
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