Why not aging the BSS in use?

Holger Schurig holgerschurig at gmail.com
Mon Apr 15 07:02:20 EDT 2013

Hi Matthieu,

I hope that Intel won't sell such buggy chips :-)

Also, I personally think that wpa_supplicant should be optimized for
working hardware. What you propose is a work-around for a buggy hardware. I
have not looked at the source code yet, but I have something in the back of
my head: the bss list enty of the current AP isn't aged, so that it doesn't
get deleted accidentally. If it would be deleted, you'd get dangling
pointers, e.g. pointers pointing into unallocated memory.

For your situation, you should probably a) fix the driver/chip, b) use some
of the background scan methods that are part of wpa_supplicant.

2013/4/12 Mauger, MatthieuX <matthieux.mauger at intel.com>

> Hello,
> We are currently facing a tricky problem, we are using a WiFi chip that is
> sometime not so reliable and we not always receive a deauth or beacon loss
> from the chip when leaving the range of a network.
> In such situation, we can trust that we are still connected even at
> kilometers from the BSS!
> As a workaround we are considering to use the aging mechanism in order to
> not keep such BSS in the scan list.
> However we saw in function "wpa_bss_update_end" in bss.c that the aging is
> voluntary not applied to the current BSS.
> We are wondering if is there a good reason to skip it? What could be the
> risk to apply aging on the BSS in use?
> Any help or comment is welcome,
> Thanks and regards,
> Matthieu
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