[RFC] nl80211: set NLMODE correctly for AP interface

[Avinash Patil]

Hi Jouni,

Did you get a chance to look into logs?
Are these logs OK?

Thanks,
-Avinash
On May 14, 2014 10:07 AM, "Avinash Patil" <avinashapatil at gmail.com> wrote:

> Hi Jouni,
>
> Please find attached logs for failure case without these changes.
>
> Also my comments inline.
>
> Thanks,
> Avinash
> On Tue, May 13, 2014 at 7:36 PM, Jouni Malinen <j at w1.fi> wrote:
> > On Tue, May 13, 2014 at 03:46:05PM +0530, Avinash Patil wrote:
> >> We add interface manually by "iw dev interface wlan0 add uap0 type
> >> __ap" and then we start AP operations using supplicant.
> >> Typical configuration file would be like this:
> >>
> >> network={
> >>          ssid="supplicant_ap"
> >>          key_mgmt=NONE
> >>          mode=2
> >>          frequency=2432
> >> }
> >>
> >> #wpa_supplicant -Dnl80211 -i uap0 -c ap.conf
> >
> > Does this fail for you without the change? If so, could you please share
> > a wpa_supplicant debug log showing the failure?
> >
> >> >> diff --git a/src/drivers/driver_nl80211.c
> b/src/drivers/driver_nl80211.c
> >> >> @@ -4698,7 +4698,7 @@ wpa_driver_nl80211_finish_drv_init(struct
> >> >> -       if (drv->hostapd)
> >> >> +       if (drv->hostapd || nl80211_get_ifmode(bss) ==
> NL80211_IFTYPE_AP)
> >> >>                 nlmode = NL80211_IFTYPE_AP;
> >> >
> >> > This breaks the case of something first setting wlan0 to non-station
> >> > mode (e.g., "iw wlan0 set type __ap") followed by wpa_supplicant
> started
> >> > on wlan0. The expectation there is that wpa_supplicant runs operations
> >> > in station mode until requested to something else (e.g., start AP
> mode).
> >>
> >> I did not fully understand this scenario but I think you are referring
> >> to similar situation as I described earlier except while I am adding
> >> interface, in this case interface type is changed.
> >
> > I'm talking about the exact same way of adding the vif, but different
> > wpa_supplicant configuration, i.e., a configuration that does not enable
> > AP mode operations.
> >
> >> > Why would this change be needed in the first place? Doesn't
> >> > wpa_supplicant set the interface to AP mode when the AP mode network
> is
> >> > being configured?
> >>
> >> This handles a case where AP<=>STA change_virtual_interface is not
> >> supported but we know that interface on which supplicant is started is
> >> AP interface.
> >> To ensure that this check applies only to statically created
> >> interface, we can add one more check:
> >>
> >>       if (drv->hostapd || (nl80211_get_ifmode(bss) ==
> >> NL80211_IFTYPE_AP && !bss->if_dynamic))
> >>                  nlmode = NL80211_IFTYPE_AP;
> >
> > The problem here is that this function does not know what wpa_supplicant
> > will do next. In the example I described, the new operation would not be
> > AP mode and as such, changing to AP mode here would not be correct. In
> > the example you are describing, the next operation is AP mode, but the
> > code here has no way of knowing that and as such, I don't think it
> > should use the current iftype of the interface to try to guess what
> > might be happening next.
>
> Maybe we can have another config file parameter (e.g. static_ap=1) to
> indicate changing to default NL_IFTYPE type STATATION is not supported
> and supplicant should set iftype as AP during initialization.
>
> > --
> > Jouni Malinen                                            PGP id EFC895FA
>
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