Wireshark · Wireshark-dev: [Wireshark-dev] Calling dissector with proto_tree==NULL

[Fabrizio Bertocci <fabrizio@xxxxxxx>]

All,
I am working on a newer version of the RTPS packet dissector (real- 
time publisher/subscriber).
I have noticed that my packet dissector gets called every time with  
the proto_tree parameter not NULL, including when the packets are  
loaded in memory.
Unfortunately there are some complex packets that require some heavy  
computation that should not be necessary unless the packet is  
selected. As result of this, loading a file (with those packets)  
takes quite a long time...

The documentation said that wireshark calls the packet dissector with  
proto_tree != NULL only when the entire tree is needed.
Any idea why? Is it something that has changed over the time? Is it  
something I'm doing wrong?

I'm registering the protocol on top of UDP with a simple call to:
heur_dissector_add("udp", dissect_rtps, proto_rtps);

Thanks for any help provided!
Fabrizio