I've exported the methods wpsPbc, wpsReg and wpsPin (patch attached),
so wpa_supplicant should be able to connect with WPS using the dbus
interface. I couldn't test it well because the problem seems to be in
my wireless card, a Broadcom BCM4328. At least it seems to do the same
using both interfaces. With ndiswrapper driver the "wpsie" entry
(thanks Dan!) didn't appear, and with the Broadcom wl driver it
appears but I cannot associate using WPS.
The wps_cred_process option can be used to configure wpa_supplicant to
send received Credential attributes for external processing over
ctrl_iface and dbus. This allows external programs to update their
configuration when WPS is used to provision new networks.
