Move message checksum logic to crypto.py

lib/tfw/crypto.py

@@ -4,6 +4,7 @@
 from functools import wraps
 from base64 import b64encode, b64decode
 from copy import deepcopy
+from hashlib import md5
 
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives.hashes import SHA256
@@ -13,6 +14,10 @@ from cryptography.exceptions import InvalidSignature
 from tfw.networking import message_bytes
 
 
+def message_checksum(message):
+    return md5(message_bytes(message)).hexdigest()
+
+
 def sign_message(key, message):
     signature = HMAC(key, message_bytes(message)).signature
     message['signature'] = b64encode(signature).decode()

lib/tfw/event_handler_base.py

@@ -2,10 +2,9 @@
 # All Rights Reserved. See LICENSE file for details.
 
 from abc import ABC, abstractmethod
-from json import dumps
-from hashlib import md5
 
 from tfw.networking.event_handlers import ServerConnector
+from tfw.crypto import message_checksum
 from tfw.config.logs import logging
 
 LOG = logging.getLogger(__name__)
@@ -82,7 +81,7 @@ class EventHandlerBase(ABC):
         Note that you can subscribe to the same key several times in which
         case you will need to unsubscribe multiple times in order to stop
         receiving events.
-        
+
         :param keys: list of keys to subscribe to
         """
         for key in keys:
@@ -152,7 +151,7 @@ class BroadcastingEventHandler(EventHandlerBase, ABC):
         self.own_message_hashes = []
 
     def event_handler_callback(self, message):
-        message_hash = self.hash_message(message)
+        message_hash = message_checksum(message)
 
         if message_hash in self.own_message_hashes:
             self.own_message_hashes.remove(message_hash)
@@ -160,10 +159,5 @@ class BroadcastingEventHandler(EventHandlerBase, ABC):
 
         response = self.dispatch_handling(message)
         if response:
-            self.own_message_hashes.append(self.hash_message(response))
+            self.own_message_hashes.append(message_checksum(response))
             self.server_connector.broadcast(response)
-
-    @staticmethod
-    def hash_message(message):
-        message_bytes = dumps(message, sort_keys=True).encode()
-        return md5(message_bytes).hexdigest()