Don't support wireless networks with '\x00' in the ESSID

gtk/netentry.py

@@ -861,7 +861,11 @@ class WirelessNetworkEntry(NetworkEntry):
         self.show_all()
         self.advanced_dialog = WirelessSettingsDialog(networkID)
         self.wifides = self.connect("destroy", self.destroy_called)
-    
+
+        # Disable widget if the ESSID contains one (or more) NULL byte
+        if '<NULL>' in self.essid:
+            self.set_sensitive(False)
+
     def _escape(self, val):
         """ Escapes special characters so they're displayed correctly. """
         return val.replace("&", "&amp;").replace("<", "&lt;").\