Wireshark-dev: Re: [Wireshark-dev] Wireshark Dissector
From: Guy Harris <[email protected]>
Date: Tue, 25 Jun 2013 18:07:58 -0700
On Jun 25, 2013, at 12:31 AM, suraj mukade <[email protected]> wrote:

> How to call your own dissector based on type field in Ethernet? After getting Type value from Ethernet frame,I want to dissect the custom Ethernet frame with some added fields and then proceed the normal dissection.

The answer to your question depends on how your protocol works.

If the data in a packet using your protocol looks something like:

	Ethernet destination
	Ethernet source
	The type field value you've registered with the IEEE for your protocol
	Fields for your protocol, including something to indicate what protocol comes after it
	Those protocols

then you would have your dissector do

	 dissector_add_uint("ethertype", {your ethertype value}, {a handle for your dissector});

where {your ethertype value} is the Ethernet type value registered for your protocol and {a handle for your dissector} is, well, a handle for your dissector, created with, for example, register_dissector() or new_register_dissector() or create_dissector_handle() or new_create_dissector_handle().

Your dissector would then either define a dissector table for the field that indicates what protocol comes after (and you'd have to change other dissectors to register in that table) or, if the field is a protocol type field that already exists, such as an Ethernet type value, you could just do something such as

	ethertype_dissector_table = find_dissector_table("ethertype");

in your reg_handoff routine and then call dissector_try_uint() with the Ethernet type field's value when it's time to dissect the payload.