> Could you tell me from which file does the function
> "dissect_ptp" is being called?
> I've looked everywhere in the source code but can't
> find the submodule that invokes it.
Hi,
I'm not an expert, but the way it works is approximately this:
Inside packet-ptp.c, you've got proto_reg_handoff_ptp. There the code
registers itself as a dissector that applies to udp ports EVENT_PORT_PTP
and GENERAL_PORT_PTP. When the packet is recognized as udp, packet-udp dissector
is called. Once this has read the udp ports, it tries with dissectors that
have registered for those ports -it also tries other methods, not every protocol
is directly associated to a port-. That's probably around decode_udp_ports. So
you don't have any explicit call to dissect_ptp that you can find in the code,
it will be something like dissector_try_port where the arguments have been
set in execution time to the appropiate values.
Of course, packet-udp is called because packet-ip recognized this was an UDP
packet, packet-ip because... and so on.
Anyway, this question probably belongs to the development list. People there
will probably be able to give you further information.
Regards,
Francisco