fix(pubsub): fix order of SecurityHeader and ExtendedNetworkMessageHe…

…ader (#5979)

In the PubSub specification the SecurityHeader is before the
ExtendedNetworkMessageHeader, thus the headers must be decoded in this
order.

src/pubsub/ua_pubsub_networkmessage.c

@@ -803,14 +803,14 @@ UA_NetworkMessage_decodeHeaders(const UA_ByteString *src, size_t *offset, UA_Net
         UA_CHECK_STATUS(rv, return rv);
     }
 
+    rv = UA_ExtendedNetworkMessageHeader_decodeBinary(src, offset, dst);
+    UA_CHECK_STATUS(rv, return rv);
+
     if (dst->securityEnabled) {
         rv = UA_SecurityHeader_decodeBinary(src, offset, dst);
         UA_CHECK_STATUS(rv, return rv);
     }
 
-    rv = UA_ExtendedNetworkMessageHeader_decodeBinary(src, offset, dst);
-    UA_CHECK_STATUS(rv, return rv);
-
     return UA_STATUSCODE_GOOD;
 }