On Tue, 2019-10-29 at 09:54 +0100, Krzysztof Hałasa wrote:
> The problem I can see is that the dialog_tokens are 8-bit, way too small
> to eliminate conflicts.
Well, they're also per station, we could just randomize the start and
then we'd delete the old session and start a new one, on the receiver.
So that would improve robustness somewhat (down to a 1/256 chance to hit
this problem).
> > Really what I think probably happened is that one of your stations lost
> > the connection to the other, and didn't tell it about it in any way - so
> > the other kept all the status alive.
>
> You must have missed my previous mail - I simply rebooted that station,
> and alternatively rmmoded/modprobed ath9k. But the problem originated in
> a station going out of and back in range, in fact.
I was on vacation, so yeah, quite possible I missed it.
Sounds like we need not just
4b08d1b6a994 ("mac80211: IBSS: send deauth when expiring inactive STAs")
but also send a deauth when we disconnect. Surprising we don't do that,
actually.
> > I suspect to make all this work well we need to not only have the fixes
> > I made recently to actually send and parse deauth frames, but also to
> > even send an auth and reset the state when we receive that, so if we
> > move out of range and even the deauth frame is lost, we can still reset
> > properly.
>
> That's one thing. The other is a station trying ADDBA for the first time
> after boot (while the local station has seen it before that reboot).
That's the situation though - the local station needs to know that it
has in fact *not* seen the same instance of the station, but that the
station has reset and needs to be removed & re-added.
> I guess we need to identify "new connection" reliably. Otherwise,
> the new connections are treated as old ones and it doesn't work.
Right. But we can implement the (optional) authentication (which you
actually already get when you implement [encrypted] IBSS with wpa_s),
and reset the station state when we get an authentication frame.
johannes
