Re: [Ethereal-dev] Fields and protocols relationships

[Guy Harris <gharris@xxxxxxxxx>]

Stefano Pettini wrote:

> Ok. This means that I can't let the user choose the dissectors for a 
> stack of 2 protocol over UDP.

Not without adding new code to the "Decode As" dialog.

> The problem is it's difficult, for dissector A, to understand what's the 
> upper layer protocol.

It *HAS* to understand, in some sense, what the upper layer protocol is 
- otherwise it can't call the dissector for that protocol!

It doesn't have to be able to determine that from the contents of the 
packet, although if it can, that's obviously preferable.  If it has to 
be done by the user, then it has to be done by the user - but, even in 
that case, it has to set something that dissector A uses to determine 
what protocol dissector to call.