Hi Johannes,
On 05/22/2018 03:40 PM, Johannes Berg wrote:
Hi,
So I need to absorb all of this some more, but I'm still wondering why
we are seeing two separate scan entries (with hidden & plain ssid) when
we requested a flush? Is there a way to force the kernel to only show
us the probe responses.
Oh. I didn't even think about this part, but that's just a consequence
of having a hidden SSID. We need one entry to track the beacon, and then
we add another entry for each hidden SSID it may have. Some APs
implement multiple SSIDs that way (old Cisco equipment, IIRC, though
then with zero-length SSID instead of zero-bytes), so you can't lump
them together into a single BSS entry.
It would seem that even with the flush flag set, there could still be
spurious beacons getting in causing these results to appear in the scan
result set, right?
In general anything can, there's no filtering. So you might do a flush
scan for a specific SSID and still get 20 (different) results, if 20
beacons happened to be received while you were scanning.
Okay, so we need to use NL80211_BSS_PRESP_DATA if we want to filter out
scan results that are coming from beacons, right?
So what's the practical use of the flush flag? Or is that something
that was meant to be 'for-testing-only'?
Regards,
-Denis
