Re: Is this a bug in display filter engine or something I have done wrong?

[Richard Sharpe <realrichardsharpe () gmail com>]

On Tue, Aug 18, 2015 at 6:00 AM, Alexis La Goutte
<alexis.lagoutte () gmail com> wrote:
> On Tue, Aug 18, 2015 at 3:51 AM, Richard Sharpe
> <realrichardsharpe () gmail com> wrote:
> > Hi folks,
> >
> > I have the following definition (someone else wrote this piece):
> >
> >    {&hf_ieee80211_ff_dmg_params_bss,
> >      {"BSS Type", "wlan.dmg_params.bss",
> >       FT_UINT8, BASE_DEC, VALS(bss_type), 0x03,
> >       NULL, HFILL }},
> >
> > and am dissecting this for Probe Response frames depending on whether
> > or not it is a DMG STA or not (based on the frequency of the STA:
> > 70,000 MHz):
> >
> >   gboolean     *p_isDMG =
> > ((gboolean*)(p_get_proto_data(wmem_file_scope(), pinfo, proto_wlan,
> > IS_DMG_KEY)));
> > ...
> >   if (p_isDMG && *p_isDMG) {
> >     add_ff_dmg_params(cap_tree, tvb, pinfo, offset);
> > ...
> >
> > This displays correctly, but if we specify a display filter of
> > wlan.dmg_params.bss == 1 nothing is found.
> >
> > What do I need to do here to make this work?
> Hi,
>
> Or *p_isDMG is not initial for the first pass ?

Yes, this looks like the problem. I think I need to hoist the test and
setting to the top of the ieee802.11 dissector so that it is available
early for all dissections.

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)
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