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Wireshark-dev: Re: [Wireshark-dev] Modbus/TCP hookup for subdissector

From: Chris Maynard <chris.maynard@xxxxxxxxx>
Date: Fri, 25 Mar 2011 16:05:42 +0000 (UTC)
Roland Knall <rknall@...> writes:

> 1. Is there a way to provide additional information to the
> subdissector? Someone could use private_data, but that field I need
> somewhere else, therefore can not be used here.

I haven't looked at the patch or anything, but I just wanted to comment on this
part.  If you want/need to use the private data, you can do what several
dissectors do and save a pointer to the current private_data before replacing
the pinfo->private_data with your own, then restore the original afterwards. 
One example is packet-http.c, but there are others.  (search for
"save_private_data")