Sorry to drag up an old topic, but I've been thinking about this:
Message: 5
Date: Sat, 29 May 2021 09:32:29 +0200
From: Anders Broman <a.broma...@gmail.com>
To: Developer support list for Wireshark <wireshark-dev@wireshark.org>
Subject: Re: [Wireshark-dev] Calling a dissector: Type for data
parameter
Message-ID:
<CAOpyz=zdycm33pxuwtbctew7gttecslij-f8shw0l-863q5...@mail.gmail.com>
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Hi,
Yes the method is fragile. At the time of development I think it was
proposed to pass a struct containing a string and the void pointer where
the string could be used as a identifier. But that was voted down.
Regards
Anders
I wasn't around for that discussion so I don't know the reasons, but how
does this sound as a refined approach?:
* Define a `dissector_data_t` that has a `guint32` identifier field, and
a `void *` data field.
* Replace the `void *data` parameter to dissectors with a pointer to a
`dissector_data_t`.
* Either:
* Easy way: maintain a static list of identifiers that map to
expected data types, or
* Have dissector X request an identifier in its registration
function for the type of data it expects, and have dissector Y (which
will call X) request, in its handoff function, the identifier of the
type of data it needs to pass to X.
* Dissectors check for the right identifier in their `dissector_data_t`
parameter and don't try to use it if it's wrong.
Thoughts?
David
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