FediChordMessage: last part has falg instead of parts number in each msg

Motivation: Including the number of parts in each message part requires
the total number of parts to be known in advance, making dynamic
responses based on the received data difficult

FediChord.asn1

@@ -4,14 +4,16 @@ NodeID ::= INTEGER (0..115792089237316195423570985008687907853269984665640564039
 
 Domain ::= VisibleString
 
+Partnum ::= INTEGER (0..150)
+
 Action ::= ENUMERATED {queryID, join, leave, stabilise, ping}
 
 Request ::= SEQUENCE {
 	action			Action,
 	requestID		INTEGER (0..4294967295),	-- arbitrarily restricting to an unsigned 32bit integer
 	sender			NodeState,
-	parts			INTEGER (1..150),	-- number of message parts
-	part			INTEGER (1..150),	-- part number of this message, starts at 1
+	part			Partnum,	-- part number of this message, starts at 1
+	finalPart		BOOLEAN,	-- flag indicating this `part` to be the last of this reuest
 	actionPayload	CHOICE {
 		queryIDRequestPayload		QueryIDRequestPayload,
 		joinRequestPayload			JoinRequestPayload,
@@ -27,8 +29,8 @@ Request ::= SEQUENCE {
 Response ::= SEQUENCE {
 	responseTo		INTEGER (0..4294967295),	-- arbitrarily restricting to an unsigned 32bit integer
 	senderID		NodeID,
-	parts			INTEGER (0..150),
-	part			INTEGER (0..150),
+	part			Partnum,
+	finalPart		BOOLEAN,	-- flag indicating this `part` to be the last of this response
 	action			Action,
 	actionPayload	CHOICE {
 		queryIDResponsePayload	QueryIDResponsePayload,

src/Hash2Pub/ASN1Coding.hs

@@ -103,7 +103,7 @@ serialiseMessage maxBytesLength msg =
         modifyMessage i (partNum, pl) pls = (partNum, msg {
                 part = partNum
               , payload = Just pl
-              , parts = fromIntegral i
+              , isFinalPart = partNum == fromIntegral i
                            }):pls
         -- part starts at 1
         payloadParts :: Int -> Maybe [(Integer, ActionPayload)]
@@ -216,23 +216,22 @@ encodeQueryResult FORWARD{} = Enumerated 1
 encodeMessage :: FediChordMessage   -- ^ the 'FediChordMessage to be encoded
               -> [ASN1]
 encodeMessage
-    (Request requestID sender parts part action requestPayload) =
+    (Request requestID sender part isFinalPart action requestPayload) =
         Start Sequence
       : (Enumerated . fromIntegral . fromEnum $ action)
       : IntVal requestID
       : encodeNodeState sender
-      <> [
-        IntVal parts
-      , IntVal part ]
+      <> [IntVal part
+        , Boolean isFinalPart]
       <> maybe [] encodePayload requestPayload
       <> [End Sequence]
 encodeMessage
-    (Response responseTo senderID parts part action responsePayload) = [
+    (Response responseTo senderID part isFinalPart action responsePayload) = [
         Start Sequence
       , IntVal responseTo
       , IntVal . getNodeID $ senderID
-      , IntVal parts
       , IntVal part
+      , Boolean isFinalPart
       , Enumerated . fromIntegral . fromEnum $ action]
       <> maybe [] encodePayload responsePayload
       <> [End Sequence]
@@ -265,8 +264,8 @@ parseRequest :: Action -> ParseASN1 FediChordMessage
 parseRequest action = do
     requestID <- parseInteger
     sender <- parseNodeState
-    parts <- parseInteger
     part <- parseInteger
+    isFinalPart <- parseBool
     hasPayload <- hasNext
     payload <- if not hasPayload then pure Nothing else Just <$> case action of
                  QueryID   -> parseQueryIDRequest
@@ -275,13 +274,13 @@ parseRequest action = do
                  Stabilise -> parseStabiliseRequest
                  Ping      -> parsePingRequest
 
-    pure $ Request requestID sender parts part action payload
+    pure $ Request requestID sender part isFinalPart action payload
 
 parseResponse :: Integer -> ParseASN1 FediChordMessage
 parseResponse responseTo = do
     senderID <- fromInteger <$> parseInteger :: ParseASN1 NodeID
-    parts <- parseInteger
     part <- parseInteger
+    isFinalPart <- parseBool
     action <- parseEnum :: ParseASN1 Action
     hasPayload <- hasNext
     payload <- if not hasPayload then pure Nothing else Just <$> case action of
@@ -291,7 +290,14 @@ parseResponse responseTo = do
                  Stabilise -> parseStabiliseResponse
                  Ping      -> parsePingResponse
 
-    pure $ Response responseTo senderID parts part action payload
+    pure $ Response responseTo senderID part isFinalPart action payload
+
+parseBool :: ParseASN1 Bool
+parseBool = do
+    i <- getNext
+    case i of
+      Boolean parsed -> pure parsed
+      x -> throwParseError $ "Expected Boolean but got " <> show x
 
 parseInteger :: ParseASN1 Integer
 parseInteger = do

src/Hash2Pub/ProtocolTypes.hs

@@ -21,8 +21,8 @@ data Action = QueryID
 data FediChordMessage = Request
     { requestID :: Integer
     , sender    :: RemoteNodeState
-    , parts     :: Integer
     , part      :: Integer
+    , isFinalPart :: Bool
     -- ^ part starts at 1
     , action    :: Action
     , payload   :: Maybe ActionPayload
@@ -30,8 +30,8 @@ data FediChordMessage = Request
     | Response
     { responseTo :: Integer
     , senderID   :: NodeID
-    , parts      :: Integer
     , part       :: Integer
+    , isFinalPart :: Bool
     , action     :: Action
     , payload    :: Maybe ActionPayload
     }