fix off-by-one error in message splitting

Hash2Pub/FediChord.asn1

@@ -11,7 +11,7 @@ Request ::= SEQUENCE {
 	requestID		INTEGER,
 	sender			NodeState,
 	parts			INTEGER,	-- number of message parts
-	part			INTEGER,	-- part number of this message
+	part			INTEGER,	-- part number of this message, starts at 1
 	actionPayload	CHOICE {
 		queryIDRequestPayload		QueryIDRequestPayload,
 		joinRequestPayload			JoinRequestPayload,

Hash2Pub/src/Hash2Pub/ASN1Coding.hs

@@ -20,6 +20,9 @@ import Hash2Pub.FediChord
 import Hash2Pub.Utils
 import Hash2Pub.DHTProtocol
 
+import Debug.Trace
+
+-- TODO: make this splitting function more intelligent, currently it creates many parts that are smaller than they could be
 -- | Try splitting a payload into multiple parts to be able to reduce size of
 -- individual messages.
 -- Only some kinds of payloads can be split, and only to a limited number of parts.
@@ -30,29 +33,29 @@ splitPayload :: Int                 -- number of parts to split payload into
              -> [ActionPayload]     -- list of smaller payloads
 splitPayload numParts pl@LeaveRequestPayload{} = [
     LeaveRequestPayload {
-        leaveSuccessors = fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ leaveSuccessors pl
-      , leavePredecessors = fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ leavePredecessors pl
-                        } | thisPart <- [0..numParts] ]
+        leaveSuccessors = atDef []  (listInto numParts $ leaveSuccessors pl) (thisPart-1)
+      , leavePredecessors = atDef  [] (listInto numParts $ leavePredecessors pl) (thisPart-1)
+                        } | thisPart <- [1..numParts] ]
 splitPayload numParts pl@StabiliseResponsePayload{} = [
     StabiliseResponsePayload {
-        stabiliseSuccessors =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ stabiliseSuccessors pl
-      , stabilisePredecessors =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ stabilisePredecessors pl
-                        } | thisPart <- [0..numParts] ]
+        stabiliseSuccessors =  atDef [] (listInto numParts $ stabiliseSuccessors pl) (thisPart-1)
+      , stabilisePredecessors =  atDef [] (listInto numParts $ stabilisePredecessors pl) (thisPart-1)
+                        } | thisPart <- [1..numParts] ]
 splitPayload numParts pl@PingResponsePayload{} = [
     PingResponsePayload {
-        pingNodeStates =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ pingNodeStates pl
-                        } | thisPart <- [0..numParts] ]
+        pingNodeStates =  atDef [] (listInto numParts $ pingNodeStates pl) (thisPart-1)
+                        } | thisPart <- [1..numParts] ]
 splitPayload numParts pl@JoinResponsePayload{} = [
     JoinResponsePayload {
-        joinSuccessors =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ joinSuccessors pl
-      , joinPredecessors =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ joinPredecessors pl
-      , joinCache =  fromMaybe [] $ headMay . drop thisPart $ listInto numParts $ joinCache pl
-                        } | thisPart <- [0..numParts] ]
+        joinSuccessors =  atDef [] (listInto numParts $ joinSuccessors pl) $ thisPart-1
+      , joinPredecessors =  atDef [] (listInto numParts $ joinPredecessors pl) $ thisPart-1
+      , joinCache =  atDef [] (listInto numParts $ joinCache pl) $ thisPart-1
+                        } | thisPart <- [1..numParts] ]
 splitPayload _ pl@(QueryIDResponsePayload FOUND{}) = [pl]
 splitPayload numParts pl@(QueryIDResponsePayload (FORWARD resSet)) = [
     QueryIDResponsePayload {
-        queryResult = maybe (FORWARD Set.empty) FORWARD $ headMay . drop thisPart $ setInto numParts resSet
-                           } | thisPart <- [0..numParts] ]
+        queryResult = FORWARD $ atDef Set.empty (setInto numParts resSet) $ thisPart-1
+                           } | thisPart <- [1..numParts] ]
 -- pass all other payloads as-is
 splitPayload _ somePayload = [somePayload]
 
@@ -94,9 +97,9 @@ serialiseMessage maxBytesLength msg =
               , payload = pl
               , parts = fromIntegral i
                            }):pls
-        -- part starts at 0
+        -- part starts at 1
         payloadParts :: Int -> [(Integer, ActionPayload)]
-        payloadParts i = zip [0..] (splitPayload i actionPayload)
+        payloadParts i = zip [1..] (splitPayload i actionPayload)
         actionPayload = payload msg
         encodedMsgs i = map (encodeASN1' DER . encodeMessage) $ messageParts i
         maxMsgLength msgs = maximum $ map BS.length msgs

Hash2Pub/test/FediChordSpec.hs

@@ -200,7 +200,7 @@ spec = do
                 requestID = 2342
               , sender = exampleNodeState
               , parts = 1
-              , part = 0
+              , part = 1
               , action = undefined
               , payload = undefined
                                       }
@@ -208,7 +208,7 @@ spec = do
                 responseTo = 2342
               , senderID = nid exampleNodeState
               , parts = 1
-              , part = 0
+              , part = 1
               , action = undefined
               , payload = undefined
                                       }