Re: Calling a dissector: Type for data parameter

[Hardening <rdp.effort () gmail com>]

Le 16/06/2021 à 16:36, David Perry a écrit :
> 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.broman58 () gmail com>
[...]
> 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.

Hi,

I have that example with the SSL dissector: in almost all cases when we 
call this dissector from another one, we know exactly what is the next 
dissector to call on decoded content anyway AFAICT a heuristic is the 
only way to have things work as expected, or did I missed something ?

Best regards.
--
David FORT
website: https://www.hardening-consulting.com/

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