auto-t: hostapd: add set_address/group_neighbors

This adds a few utilities for setting up an FT environment. All the
roaming tests basically copy/paste the same code for setting up the
hostapd instances and this can cause problems if not done correctly.

set_address() sets the MAC address on the device, and restarts hostapd
group_neighbors() takes a list of HostapdCLI objects and makes each a
    neighbor to the others.

The neighbor report element requires the operating class which isn't
advertised by hostapd. For this we assume operating class 81 but this
can be set explicitly if it differs. Currently no roaming tests use
5/6GHz frequencies, and just in case an exception will be thrown if
the channel is greater than 14 and the op_class didn't change.

autotests/util/hostapd.py

@@ -281,3 +281,34 @@ class HostapdCLI(object):
     @property
     def enabled(self):
         return self._get_status()['state'] == 'ENABLED'
+
+    def set_address(self, mac):
+        os.system('ip link set dev %s down' % self.ifname)
+        os.system('ip link set dev %s addr %s up' % (self.ifname, mac))
+
+        self.reload()
+        self.wait_for_event("AP-ENABLED")
+
+    def _add_neighbors(self, *args, op_class=81):
+        for hapd in args:
+            status = hapd._get_status()
+
+            ssid = status['ssid[0]']
+            bssid = status['bssid[0]']
+            channel = int(status['channel'])
+
+            if (channel > 14 and op_class == 81):
+                raise Exception("default add_neighbors assumes opclass 0x51!")
+
+            channel = '{:02x}'.format(channel)
+            oper_class = '{:02x}'.format(op_class)
+
+            self.set_neighbor(bssid, ssid, '%s8f000000%s%s060603000000' %
+                                (bssid.replace(':', ''), oper_class, channel))
+
+    @classmethod
+    def group_neighbors(cls, *args):
+        for hapd in args:
+            others = [h for h in args if h != hapd]
+
+            hapd._add_neighbors(*others)