Wireshark · Wireshark-dev: Re: [Wireshark-dev] Capture filename not available at plugin init time

[Paul Offord <Paul.Offord@xxxxxxxxxxxx>]

No it’s called when you open a capture file.

 

From: Wireshark-dev [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Anders Broman
Sent: 03 November 2017 14:00
To: Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>
Subject: Re: [Wireshark-dev] Capture filename not available at plugin init time

 

Isn't the init function called at startup of wireshark? At which point a file may not yet have been selected.

Regards 

Anders

 

Den 3 nov. 2017 2:54 em skrev "Roland Knall" <rknall@xxxxxxxxx>:

Hi Paul

 

As far as I know, cf_open can still fail after calling the init-functions. In that case you would get the filename, but the capture is already closed.

 

My question is, why do you need the filename in the first place?

 

Also, you could set the filename at a later point. If you implement a tap-interface, you could set the filename in the first tap-print callback. Makes sense, 'cause you normally only have data at this point anyway.

 

You can raise this as an improvement (do not think it is a bug) if you want to, not really sure though, if it should be changed

 

cheers

 

 

On Fri, Nov 3, 2017 at 2:49 PM, Paul Offord <Paul.Offord@xxxxxxxxxxxx> wrote:

I have a dissector that needs the capture file name at the time my dissector’s init function is called.  I attempt to get the name with plugin_if_get_ws_info(…), not an unreasonable request I think you’ll agree, but unfortunately the filename comes back as a NULL pointer.

 

I’ve traced through the code and this is what happens:

 

• We pass through the MainWindow signal and slot stuff and eventually call cf_open(…) in file.c with the filename as one of the parameters
• cf_open(…) opens the file to test the validity of the filename and then closes with cf_close(cf)
• cf_close(cf) frees the memory holding the filename and NULLs the filename pointer in the cf structure
• cf_open then creates a new epan session with ws_epan_new(cf)
• ws_epan_new(cf) calls epan_new() which calls init_dissection() and this is where eventually my dissector’s init function gets called
• My dissector calls plugin_if_get_ws_info(…) which attempts to get the filename info from the cf structure, which due to the above returns a NULL filename pointer
• Eventually we return back to cf_open(…) and a little later we set up the file name in the cf structure – all too late for my dissector’s init function

 

So my questions are:

 

• Can I raise this as a bug?
• If not, would a solution that made the filename available to plugin_if_get_ws_info(…) at init time be accepted?
• What would be an acceptable solution?

 

Thanks and regards…Paul

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