Wireshark · Wireshark-dev: Re: [Wireshark-dev] When is the preference variable updated?

[Paul Offord <Paul.Offord@xxxxxxxxxxxx>]

Hi Pascal,

 

You are right – it got called twice without the preference value being set and then the third time it was.  Thanks to you both for your help, it’s saved me a lot of time.

 

Best regards…Paul

 

From: wireshark-dev-bounces@xxxxxxxxxxxxx [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Pascal Quantin
Sent: 12 November 2015 14:53
To: Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>
Subject: Re: [Wireshark-dev] When is the preference variable updated?

 

 

 

2015-11-12 15:48 GMT+01:00 Paul Offord <Paul.Offord@xxxxxxxxxxxx>:

Hi Pascal,

 

I wondered if that would be the case but it doesn’t seem to be set when I enter the handoff code.  My handoff looks like this:

 

proto_reg_handoff_tmsvc(void)

{

               dissector_handle_t dissect_tmsvc_handle;

               HANDLE h_thread;

 

               if (tmsvc_port > 0) {

                              dissect_tmsvc_handle = create_dissector_handle(dissect_tmsvc, proto_tmsvc);

 

                              register_postdissector(dissect_tmsvc_handle);

 

                              h_thread = create_service_thread();

               }

 

               return;

}

 

I’ve checked the value of tmsvc_port with a breakpoint set on the if statement and it’s still 0 at this point.  It is set to the saved preference 8989 by the time of the first call to my dissector.

 

I notice that Anders has given me a slightly different solution and so I’ll take a look at that next.

 

Anders' solution should be the same as mine (or maybe I was not clear): proto_reg_handoff_tmsvc should be given as parameter to perfs_register_protocol and you will see that this function starts being called several times (so you should probably ensure that your code is called only once).
 

 

Thanks and regards…Paul

 

 

 

From: wireshark-dev-bounces@xxxxxxxxxxxxx [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Pascal Quantin
Sent: 12 November 2015 14:15
To: Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>
Subject: Re: [Wireshark-dev] When is the preference variable updated?

 

 

 

2015-11-12 15:07 GMT+01:00 Paul Offord <Paul.Offord@xxxxxxxxxxxx>:

Hi,

 

Frankly I feel a bit stupid asking this but I've been trying to figure it out for about 6 hours and I think I need help.  I have a dissector which I register like this:

 

static int tmsvc_port = 0;

 

void

proto_register_tmsvc(void)

{

    module_t *tmsvc_module;

 

    proto_tmsvc = proto_register_protocol("TM Syncro Service",

                                          "TmSyncro",

                                          "tmsvc");

 

    tmsvc_module = prefs_register_protocol(proto_tmsvc, NULL);

 

    prefs_register_uint_preference(tmsvc_module, "port",

                                   "TmSyncro service port",

                                   "When set to a value greater than 0 the TmSyncro service is started and accessible via the port number"

                                   10,

                                   &tmsvc_port);

 

}

 

Immediately after the prefs_register_uint_preference call I check the tmsvc_port value and its still 0 (and I've tried other initialisation values and they remain unchanged).  I was expecting tmsvc_port to be set to the value I last set by editing the preferences through the Wireshark menu system.

 

If I check with Menu -> Edit -> Preferences -> Protocols -> TmSyncro sure enough the value I last set is there.

 

When does my variable get updated?  Or alternatively, how can I retrieve the saved preference value?

 

Thanks and regards...Paul

 

Hi Paul,

the variable should be set according to the preference content when the  proto_reg_handoff_tmsvc function (that you register thanks to the prefs_register_protocol function) is called. Alternatively (if you do not need the reg_handoff function at all) the variable should be set when your dissector code is called.

Best regards,

Pascal.

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