auto-t: require a complete hostapd default config

In many tests the hostapd configuration does not include all the
values that a test uses. Its expected that each individual test
will add the values required. In many cases its required each test
slightly alter the configuration for each change every other test
has to set the value back to either a default or its own setting.
This results in a ton of duplicated code mainly setting things
back to defaults.

To help with this problem the hostapd configuration is read in
initially and stored as the default. Tests can then simply call
.default() to set everything back. This significantly reduces or
completely removes a ton of set_value() calls.

This does require that each hostapd configuration file includes all
values any of the subtests will set, which is a small price for the
convenience.

autotests/util/hostapd.py

@@ -64,7 +64,16 @@ class HostapdCLI(object):
         hapd = ctx.get_hapd_instance(config)
 
         self.interface = hapd.intf
-        self.config = hapd.config
+        self._config_path = "/tmp/" + hapd.config
+        self._default_config = self._get_config(self._config_path)
+
+        # The vendor_elements is somewhat of a special case because you can't
+        # set it to 'nothing' within the hostapd config. In most cases tests do
+        # not use this and we don't want to require they unset this value
+        # during initialization. Default this to '' so set_value won't throw
+        # an exception.
+        if self._default_config.get('vendor_elements', None) == None:
+            self._default_config['vendor_elements'] = ''
 
         if not self.interface:
             raise Exception('config %s not found' % config)
@@ -89,6 +98,12 @@ class HostapdCLI(object):
 
         ctrl_count = ctrl_count + 1
 
+    def _get_config(self, path):
+        f = open(path)
+        lines = f.readlines()
+        f.close()
+        return dict([[v.strip() for v in kv] for kv in [l.split('#', 1)[0].split('=', 1) for l in lines] if len(kv) == 2])
+
     def _handle_data_in(self, sock, *args):
         newdata = sock.recv(4096)
 
@@ -151,6 +166,10 @@ class HostapdCLI(object):
             pass
 
     def set_value(self, key, value):
+        # Don't allow new settings, defaults should always be in hostapd config
+        if self._default_config.get(key, None) == None:
+            raise Exception("Untracked setting '%s'! Please set default in hostapd config" % key)
+
         cmd = self.cmdline + ['set', key, value]
         ctx.start_process(cmd).wait()
 
@@ -179,6 +198,12 @@ class HostapdCLI(object):
         ctx.start_process(self.cmdline + ['disable']).wait()
         ctx.start_process(self.cmdline + ['enable']).wait()
 
+    def default(self):
+        for k, v in self._default_config.items():
+            self.set_value(k, v)
+
+        self.reload()
+
     def disable(self):
         ctx.start_process(self.cmdline + ['disable']).wait()