[execution][messagehandlers] Do not systematically decode incoming zmq parts

Under some circumstances the decoding may fail as the binary
data may contain values outside the utf-8 "visible" range.

Fixes #26

beat/backend/python/execution/messagehandlers.py

@@ -143,9 +143,9 @@ class MessageHandler(threading.Thread):
                 more = True
                 parts = []
                 while more:
-                    parts.append(self.socket.recv().decode("utf-8"))
+                    parts.append(self.socket.recv())
                     more = self.socket.getsockopt(zmq.RCVMORE)
-                command = parts[0]
+                command = parts[0].decode("utf-8")
 
                 if command in self.callbacks:
                     try:  # to handle command
@@ -176,7 +176,8 @@ class MessageHandler(threading.Thread):
                         import traceback
 
                         def parser(s):
-                            return s if len(s) < 20 else s[:20] + "..."
+                            parsed = s if len(s) < 20 else s[:20] + b"..."
+                            return parsed.decode("utf-8")
 
                         parsed_parts = " ".join([parser(k) for k in parts])
                         message = (
@@ -229,6 +230,9 @@ class MessageHandler(threading.Thread):
     def error(self, t, msg):
         """Syntax: err type message"""
 
+        t = t.decode("utf-8")
+        msg = msg.decode("utf-8")
+
         logger.debug("recv: err %s <msg> (size=%d)", t, len(msg))
 
         if t == "usr":
@@ -242,6 +246,7 @@ class MessageHandler(threading.Thread):
     def infos(self, name):
         """Syntax: ifo name"""
 
+        name = name.decode("utf-8")
         logger.debug("recv: ifo %s", name)
 
         if self.data_sources is None:
@@ -268,6 +273,9 @@ class MessageHandler(threading.Thread):
     def get_data(self, name, index):
         """Syntax: get name index"""
 
+        name = name.decode("utf-8")
+        index = index.decode("utf-8")
+
         logger.debug("recv: get %s %s", name, index)
 
         if self.data_sources is None:
@@ -393,12 +401,11 @@ class LoopMessageHandler(MessageHandler):
               Result to be validated.
         """
 
-        result = result.encode("utf-8")
-        logger.debug("recv: val %s", result)
-
         data = self.request_data_format.type()
         data.unpack(result)
 
+        logger.debug("recv: val %s", data)
+
         is_valid, answer = self.executor.validate(data)
 
         data = make_data_format(answer, self.answer_data_format)