add autodoc comments and clean code encode/decode method

git-svn-id: https://redmine.imt-atlantique.fr/svn/xaal/code/Python/trunk@1336 b32b6428-25c9-4566-ad07-03861ab6144f

xaal-lib/src/xAAL/message.py

@@ -69,7 +69,12 @@ class MessageFactory():
     # Message Serialization: Json encoding / decoding  
     #####################################################        
     def encodeMSG(self,msg):
-        """ Apply security layer and return encode MSG in Json """
+        """Apply security layer and return encode MSG in Json
+        :param msg: xAAL msg instance
+        :type msg: Message
+        :return: return an xAAL msg ciphered and serialized in json
+        :rtype: json
+        """
         result={}
 
         # Format data msg to send
@@ -79,24 +84,29 @@ class MessageFactory():
 
         # Format payload before ciphering
         if msg.getBody():
-            payloadBeforeCiph=json.dumps({"header":msg.getHeader(),"body":msg.getBody()})
+            payload = json.dumps({"header":msg.getHeader(),"body":msg.getBody()})
         else:
-            payloadBeforeCiph=json.dumps({"header":msg.getHeader()})
+            payload = json.dumps({"header":msg.getHeader()})
         
-        # Payload Ciphering
+        # Payload Ciphering: ciph
         ad = json.dumps(msg.getTargets()) # Additionnal Data == json serialization of the targets array
         nonce = buildNonce(msg.getTimestamp()) 
         key = self.getCipherKey()
-        payloadCiph=pysodium.crypto_aead_chacha20poly1305_encrypt(payloadBeforeCiph,ad,nonce,key)
+        ciph = pysodium.crypto_aead_chacha20poly1305_encrypt(payload,ad,nonce,key)
 
-        # Add payload: base64 encoded of payloadCiph to data msg to send
-        result['payload'] = base64.b64encode(payloadCiph)
+        # Add payload: base64 encoded of payload cipher
+        result['payload'] = base64.b64encode(ciph)
 
         # Json serialization
         return json.dumps(result)
         
     def decodeMSG(self,data):
-        """ decode incoming Json data and De-Ciphering """
+        """Decode incoming Json data and De-Ciphering
+        :param data: data received from the multicast bus
+        :type data: json
+        :return: xAAL msg
+        :rtype: Message
+        """
         # Decode json incoming data
         try:
             dataRx = json.loads(data)
@@ -105,6 +115,7 @@ class MessageFactory():
 
         # Instanciate Message
         msg=Message()
+
         if 'targets'in dataRx:
             targets = json.loads(dataRx['targets'])
             msg.setTargets(targets)
@@ -118,6 +129,7 @@ class MessageFactory():
         # Replay attack, window fixed to CIPHER_WINDOW in seconds
         now = buildTimestamp()[0] # test done only on seconds ...
         msgTime = dataRx['timestamp'][0]
+
         if msgTime < (now - CIPHER_WINDOW):
             raise MessageFactoryParserError("Potential replay attack, message too old")
 
@@ -128,19 +140,20 @@ class MessageFactory():
         ad = dataRx['targets'].encode("utf8") # Additional Data
         nonce = buildNonce(dataRx['timestamp'])
         key = self.getCipherKey()
+
         if 'payload' in dataRx:
-            payloadCiph=base64.b64decode(dataRx['payload'])
+            ciph = base64.b64decode(dataRx['payload'])
         else:
             raise MessageFactoryParserError("Bad Message, no payload found!")
 
         try:
-            payloadDeCiph=pysodium.crypto_aead_chacha20poly1305_decrypt(payloadCiph,ad,nonce,key)
+            pJson=pysodium.crypto_aead_chacha20poly1305_decrypt(ciph,ad,nonce,key)
         except:
             raise MessageFactoryParserError("Unable to decrypt msg")
         
         # Decode Json after deciphering
         try:
-            payload=json.loads(payloadDeCiph)
+            payload = json.loads(pJson)
         except:
             raise MessageFactoryParserError("Unable to parse JSON data in payload after decrypt")