On 5/18/2018 9:00 PM, Denis Kenzior wrote:
Hi Arend,
On 05/18/2018 01:54 PM, Arend van Spriel wrote:
On 5/18/2018 6:47 PM, Denis Kenzior wrote:
Hi Johannes,
On 05/18/2018 03:13 AM, Johannes Berg wrote:
On Fri, 2018-05-11 at 09:48 -0700, Tim Kourt wrote:
__cfg80211_bss_expire function was incorrectly used to flush the BSS
entries from the previous scan results, causing
NL80211_SCAN_FLAG_FLUSH
flag to have no effect.
Hmm. I guess I'm not convinced - what's the bug?
We flush anything that's older than our start, so that should work just
fine?
Just FYI, there's definitely something funny with the scanning code:
denkenz@iwd-test ~ $ sudo iw dev wlp2s0 scan flush
BSS 10:c3:7b:54:74:d4(on wlp2s0)
last seen: 274.815s [boottime]
freq: 5765
beacon interval: 100 TUs
signal: -35.00 dBm
last seen: 349 ms ago
Information elements from Probe Response frame:
SSID: \x00\x00\x00\x00\x00\x00\x00\x00\x00
Then if I try:
denkenz@iwd-test ~ $ sudo iw dev wlp2s0 scan flush ssid myssid
BSS 10:c3:7b:54:74:d4(on wlp2s0)
last seen: 319.667s [boottime]
freq: 5765
beacon interval: 100 TUs
signal: -42.00 dBm
last seen: 350 ms ago
Information elements from Probe Response frame:
SSID: \x00\x00\x00\x00\x00\x00\x00\x00\x00
....
BSS 10:c3:7b:54:74:d4(on wlp2s0)
last seen: 319.662s [boottime]
freq: 5765
beacon interval: 100 TUs
signal: -37.00 dBm
last seen: 355 ms ago
Information elements from Probe Response frame:
SSID: myssid
Shouldn't the second scan give a single result from that one BSS?
Looking at the 'last seen' values it does look ok. Both results have
the same BSSID, but the first one shows the broadcast ssid (or so it
seems).
Are you saying the first result is from the Beacon and the other is from
the Probe Response? Then why are the 'Information elements from Probe
Response frame' the way they are?
Nope. I am not saying that. I am saying that there are two probe
requests being sent. One with broadcast ssid, ie. ssid_len == 0, and
with ssid 'myssid'. But it is speculation without a sniffer capture.
Neither iw nor nl80211 on the kernel side add the broadcast ssid. So
question is what device are you using and does it use mac80211 software
Intel 7260. We're seeing the same results with hwsim as well though.
This was just a quick test to illustrate.
That seems to point to mac80211 although I am not very familiar with
neither mac80211_hwsim nor iwlwifi.
scanning or hardware scanning. I did not dive into mac80211 to see if
the broadcast ssid is added there.
By the way, if you're interested. The same tests with a Broadcom based
device wouldn't even find the hidden network. It would always come back
with a single 'x00' SSID regardless of whether I added 'ssid myssid' at
the end.
Interesting. So that means firmware does not honor the ssids passed or
brcmfmac does something wrong. Need to look into that.
Thanks,
Arend
