[Guy Harris <guy@xxxxxxxxxx>]

> > Is it possible to have two dissectors for one 
> > conversation (maybe using conversation.old_d, 
> > conversation.new_d)?
> 
> Maybe. It depends upon what you are using for the 'port' 
> value.  The word port is not a very good one because you
> can use any 32 bit integer here.

Perhaps we should replace it with "selector"?

> If your conversation are 
> based upon TCP ports, as I suspect, you have a problem.

Perhaps conversations should, instead of having a single dissector
attached to them, have a list of dissectors attached to them, with
protocol IDs for the protocol that's supposed to hand off to that
dissector, especially given your suggestion that, when a port is
matched, at least for TCP and UDP, the conversation have the appropriate
dissector attached to it, as that'll increase the chances that a given
conversation already has a dissector attached to it to be called by the
TCP or UDP dissector.

Perhaps the same should be done for the data pointer as well.