Wireshark · Wireshark-dev: Re: [Wireshark-dev] Adding a dissector for "Analyze->Decode As" only

[Guy Harris <guy@xxxxxxxxxxxx>]

On Feb 16, 2007, at 3:28 PM, Ravi Kondamuru wrote:

> I am trying to write a dissector for a non-standard rpc protocol.
> Writing a heuristic to automatically identify the protocol is  
> getting too complicated. So, I was wondering if I could add a  
> dissector that can be used when I select a connection and explictly  
> say Decode As.
>
> Is it possible to do that?

If your protocol runs directly on top of UDP or TCP, yes.  (If it runs  
on top of some other RPC protocol - i.e., if by "rpc protocol" you  
mean a protocol that is implemented using some RPC mechanism such as  
ONC RPC or DCE RPC - then, no, you can't, and you *shouldn't*; there's  
already a mechanism for registering dissectors for ONC RPC-based and  
DCE RPC-based protocols.)

> If it is, any pointers to notes on how can it be done?

If your protocol runs on top of UDP, so that you'd want to use "Decode  
As" to indicate that a particular UDP port should be used for your  
protocol, then call

	dissector_add_handle("udp.port", {the handle for your dissector});

If your protocol runs on top of TCP, so that you'd want to use "Decode  
As" to indicate that a particular TCP port should be used for your  
protocol, then call

	dissector_add_handle("tcp.port", {the handle for your dissector});