More messagetypes hardening

- only load modules at program start

src/messagetypes/__init__.py

@@ -3,6 +3,7 @@ from os import path, listdir
 from string import lower
 
 from debug import logger
+import messagetypes
 import paths
 
 class MsgBase(object):
@@ -15,9 +16,8 @@ def constructObject(data):
     if data[""] not in whitelist:
         return None
     try:
-        m = import_module("messagetypes." + data[""])
-        classBase = getattr(m, data[""].title())
-    except (NameError, ImportError):
+        classBase = getattr(getattr(messagetypes, data[""]), data[""].title())
+    except (NameError, AttributeError):
         logger.error("Don't know how to handle message type: \"%s\"", data[""], exc_info=True)
         return None
     try:
@@ -43,7 +43,7 @@ else:
         if splitted[1] != ".py":
             continue
         try:
-            import_module("." + splitted[0], "messagetypes")
+            import_module(".{}".format(splitted[0]), "messagetypes")
         except ImportError:
             logger.error("Error importing %s", mod, exc_info=True)
         else: