Comment 17 for bug 1446584

Examining output of "dbus-monitor --system" shows that URfkill is actually emitting signals that can be used by push-client to track the status of the radio devices, for instance:

signal sender=:1.3 -> dest=(null destination) serial=85 path=/org/freedesktop/URfkill/WLAN; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.freedesktop.URfkill.Killswitch"
   array [
      dict entry(
         string "state"
         variant int32 1
      )
   ]
   array [
   ]

These signals are emitted per device category (aka "Killswitch"): WWAN, WLAN, and BLUETOOTH.

The possible values of "state" are:

KILLSWITCH_STATE_UNBLOCKED = 0
KILLSWITCH_STATE_SOFT_BLOCKED = 1
KILLSWITCH_STATE_HARD_BLOCKED = 2

Radio is ON if the state is unblocked, OFF otherwise.