From 17b24377ddb3b038944a7a0cc6c0b4d091be571c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krist=C3=B3f=20T=C3=B3th?= <kristof.toth@avatao.com>
Date: Thu, 12 Jul 2018 15:17:39 +0200
Subject: [PATCH] Implement a ZMQ prefix-match countermeasure in EHBase

---
 lib/tfw/event_handler_base.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/tfw/event_handler_base.py b/lib/tfw/event_handler_base.py
index aee4b93..81b1ead 100644
--- a/lib/tfw/event_handler_base.py
+++ b/lib/tfw/event_handler_base.py
@@ -31,10 +31,25 @@ class EventHandlerBase(ABC):
         a response back in case the handler returned something.
         This is subscribed in __init__().
         """
+        if not self.check_key(message):
+            return
+
         response = self.dispatch_handling(message)
         if response:
             self.server_connector.send(response)
 
+    def check_key(self, message):
+        """
+        Checks whether the message is intended for this
+        EventHandler.
+
+        This is necessary because ZMQ handles PUB - SUB
+        connetions with pattern matching (e.g. someone
+        subscribed to 'fsm' will receive 'fsm_update'
+        messages as well.
+        """
+        return self.key == message['key']
+
     def dispatch_handling(self, message):
         """
         Used to dispatch messages to their specific handlers.