Wireshark-dev: Re: [Wireshark-dev] Decode As Option

From: Jeff Morriss <jeff.morriss.ws@xxxxxxxxx>
Date: Thu, 18 Nov 2010 12:37:09 -0500
Will Barker wrote:
I�m trying to determine why the �Decode As� context menu option

1)       is sometimes grayed out

My guess is that you don't have a field (or protocol layer) selected which has something (e.g., a TCP port field) that can be used to as a filter/selector for Decode-As.

2)       does not present all the available protocols in its list

Not all protocols are registered by name (i.e., not all dissectors call register_dissector()).

Is there an override possible somehow?

Not by a user; for the 2nd issue someone would have to add the relevant call to the dissector (and recompile, etc.).

If the user is certain that protocol FOO starts at offset X then it would be good to have a way of forcing that protocol decode at that point (regardless of the selected position in the packet etc.). Of course, as with the existing �Decode As� support, if the user got it wrong then the decode won�t work but this fallback approach (without the need for code change) does cater for those occasions where the required dissection is not implemented or is wrong etc. What would we need to change/be extended to enable this?

You might want to check out:

http://wiki.wireshark.org/HowToDissectAnything