Ethereal-dev: Re: [Ethereal-dev] How to use dissector_add
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Stefano Pettini wrote:
My protocol (ALC, RFC 3450) is based on UDP, but the rfc doesn't define
a default port. Indeed, the protocol seems to use a set of consecutive
UDP ports, starting from a base one, which is not specified and is left
to the user discretion.
...so one possibility would be to make it a preference setting, as per
one of Luis Ontanon's suggestions. You'd have to pick a default port,
though - although you could make a port number of 0 mean "don't register
it", and make that the default.
I've left proto_ref_handoff_xxx empty, but my dissector becomes
invisible (I can't choose it manually in the "decode as..." window).
Maybe it's not possible to automatically decode, after a brief
inspection, an unknown UDP packet as an ALC one,
That'd be a heuristic dissector (as Luis mentioned) - a very quick look
at RFC 3450 doesn't suggest a good heuristic.
but do I have to call
dissect_add with a fake default UDP port, even if that default isn't
specified?
No - you could call "dissector_add_handle()" to add it to the list of
dissectors that could be dissected based on the UDP port; it takes no
port number, so it doesn't cause any particular port to be dissected
with the dissector in question, but it does arrange that "Decode As" can
be used with a UDP port number.
