Network device ifindex will change when the interface is re-inserted.
driver_nl80211.c will need to accept netlink events from "unknown" (based
on ifindex) interfaces when a previously used card was removed earlier. If
the previously removed interface is added back, the driver_wext data need
to be updated to match with the new ifindex value. In addition, the initial
setup tasks for the card (set interface up, update ifindex, set mode, etc.)
from wpa_driver_nl80211_init() need to be run again.
This is the changes from commit 3fbda8f943
(driver_wext.c) ported for driver_nl80211.c.
When scan results got moved from wpa_scan_result -> wpa_scan_res, the
'maxrate' member was dropped from wpa_scan_res. The D-Bus interface
used 'maxrate', which was replaced with wpa_scan_get_max_rate().
Unfortunately, wpa_scan_get_max_rate() returns 802.11 rate values
directly from the IE, where 'maxrate' was the rate in bits/second. The
supplicant internally fakes an IE for wpa_scan_res from the value of
wpa_scan_result->maxrate, but interprets ->maxrate as an 802.11 rate
index.
As a side-effect, this fixes a soft-break of the D-Bus control API since
the wpa_scan_res change was introduced.
driver_nl80211.c is based on driver_wext.c and it is still using Linux
wireless extensions for many functions. Over time, the new driver interface
code should be modified to use nl80211/cfg80211 for everything.