Re: Retrieving dissection result from another dissector

[Michael Mann via Wireshark-dev <wireshark-dev () wireshark org>]

My objection to using p_proto_add_data in the particular case (passing data between dissectors) is that it makes the 
code/flow much harder to read and mistakes can result (usually found through fuzztesting) because the data flow isn't 
obvious.  I think the most "common" case is still a dissector using p_proto_add_data to remember data "for itself" 
(which would include some interaction with GUI like Decode As).  Just because you can exchange data between dissectors 
this way, doesn't mean you should.  I think it's more understandable if there are multiple layers/protocols between the 
setting of data and it's retrieval, but if you are only going a single layer, the data parameter of 
call_dissector_with_data should be used and a "shared structure" should be defined that includes the input/output 
parameters.
 
 
-----Original Message-----
From: Dario Lombardo <lomato () gmail com>
To: Developer support list for Wireshark <wireshark-dev () wireshark org>
Sent: Wed, Jul 4, 2018 5:28 am
Subject: Re: [Wireshark-dev] Retrieving dissection result from another dissector






On Tue, Jul 3, 2018 at 8:49 PM Guy Harris <guy () alum mit edu> wrote:


Should we, instead, get rid of the scope arguments to those functions and, instead, have separate functions, one of 
which serves the original purpose, using file scope, and one of which serves this new purpose, using pinfo->pool scope?




It looks neat, but I see 2 issues:


1) grep -r  "p_\(add\|get\|remove\)_proto_data" ../epan/dissectors/* | wc -l gives me 881 calls to those functions. It 
could be harsh to change all of them as well as breaking compatibility with existing code outside wireshark (plugins?).


2) are we sure that a call to (eg.) p_proto_add_data_with_file_scope_or_another_name() is more meaningful than 
p_proto_add_data(wmem_file_scope(), ...)? How could those 2 functions be named to recall the actual goal?


___________________________________________________________________________Sent via:    Wireshark-dev mailing list 
<wireshark-dev () wireshark org>Archives:    https://www.wireshark.org/lists/wireshark-devUnsubscribe: 
https://www.wireshark.org/mailman/options/wireshark-dev             mailto:wireshark-dev-request () wireshark 
org?subject=unsubscribe

___________________________________________________________________________
Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    https://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe