Wireshark-dev: Re: [Wireshark-dev] tools/check[hf|APIs|filtername].pl need updating?
From: Alexis La Goutte <alexis.lagoutte@xxxxxxxxx>
Date: Tue, 18 Sep 2018 18:22:46 +0200
Thanks Jakub for historic

I think a good idea is revert to use "standard" API
or write a tools for convert old dissector to new API...

Cheers

On Tue, Sep 18, 2018 at 6:05 PM Jakub Zawadzki <darkjames-ws@xxxxxxxxxxxx> wrote:
Hi,

W dniu 2018-09-18 16:56, Maynard, Chris napisał(a):
> While investigating the transum-related crash, I had suspected some
> unregistered hf's and ran the various tools like checkhf.pl.  I then
> noticed that a number of dissectors seemed to have changed a bit from
> what I was used to before (...)

These changes are quite old. For udp I did it in Aug 2013
(88eaebaedf2e19c493ea696f633463e4f2a9a757).

some wireshark-dev threads:
  - https://www.wireshark.org/lists/wireshark-dev/201307/msg00222.html
  - thread continuation:
https://www.wireshark.org/lists/wireshark-dev/201308/msg00035.html

Nobody stopped me that time.

> And I guess I missed the reasoning behind the restructuring, but what
> is the purpose/benefit of this restructuring

To sum up:

Restructuring idea was to remove usage of int hf_foo, so you would need
only to declare header_field_info hfi_foo (unfortunate, you still need
to do it on top of file).

Benefit is no more ints, so:
  - proto_tree_ api checks if you passed header_field_info structure,
  - You don't need to declare int hf_foo = -1; (bonus: binary size
smaller 4 bytes per hf),
  - no need for table lookup in proto_tree_add_*

> and use of HAVE_HFI_SECTION_INIT?

Idea was that HFI_INIT(proto_bar) would put all protocol hfi's into
single binary section. This way wireshark could auto-register these
fields
without need of some indirect array (bonus: binary size smaller by
sizeof(void *) per hfi).


After 5 years simple grep shows that only 36 dissectors are using
NEW_PROTO_TREE_API, so it seems that this API is not well known or not
liked.
If it makes problem I would suggest to drop it.

Alexis suggested the same in 2015:
https://www.wireshark.org/lists/wireshark-dev/201508/msg00087.html


Jakub.
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