type CorrelationId -> newtype CorrId (to avoid incorrect order in tuple)

src/Simplex/Messaging/Server.hs

@@ -51,7 +51,7 @@ runSMPServer cfg@ServerConfig {tcpPort} = do
       (rId, clnt) <- readTBQueue subscribedQ
       cs <- readTVar subscribers
       case M.lookup rId cs of
-        Just Client {rcvQ} -> writeTBQueue rcvQ (B.empty, rId, Cmd SBroker END)
+        Just Client {rcvQ} -> writeTBQueue rcvQ (CorrId B.empty, rId, Cmd SBroker END)
         Nothing -> return ()
       writeTVar subscribers $ M.insert rId clnt cs
 
@@ -86,7 +86,7 @@ send h Client {sndQ} = forever $ do
   signed <- atomically $ readTBQueue sndQ
   tPut h (B.empty, signed)
 
-mkResp :: CorrelationId -> QueueId -> Command 'Broker -> Signed
+mkResp :: CorrId -> QueueId -> Command 'Broker -> Signed
 mkResp corrId queueId command = (corrId, queueId, Cmd SBroker command)
 
 verifyTransmission :: forall m. (MonadUnliftIO m, MonadReader Env m) => Transmission -> m Signed
@@ -231,7 +231,7 @@ client clnt@Client {subscriptions, rcvQ, sndQ} Server {subscribedQ} =
             subscriber :: MsgQueue -> m ()
             subscriber q = atomically $ do
               msg <- peekMsg q
-              writeTBQueue sndQ $ mkResp B.empty rId (msgCmd msg)
+              writeTBQueue sndQ $ mkResp (CorrId B.empty) rId (msgCmd msg)
               setSub (\s -> s {subThread = NoSub})
               void setDelivered
 

src/Simplex/Messaging/Server/Transmission.hs

@@ -18,6 +18,7 @@ import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.Char (ord)
 import Data.Kind
+import Data.String
 import Data.Time.Clock
 import Data.Time.ISO8601
 import Simplex.Messaging.Transport
@@ -39,11 +40,11 @@ data Cmd where
 
 deriving instance Show Cmd
 
-type Signed = (CorrelationId, QueueId, Cmd)
+type Signed = (CorrId, QueueId, Cmd)
 
 type Transmission = (Signature, Signed)
 
-type SignedOrError = (CorrelationId, QueueId, Either ErrorType Cmd)
+type SignedOrError = (CorrId, QueueId, Either ErrorType Cmd)
 
 type TransmissionOrError = (Signature, SignedOrError)
 
@@ -143,7 +144,11 @@ serializeCommand = \case
 
 type Encoded = ByteString
 
-type CorrelationId = ByteString
+-- newtype to avoid accidentally changing order of transmission parts
+newtype CorrId = CorrId {bs :: ByteString} deriving (Eq)
+
+instance IsString CorrId where
+  fromString = CorrId . fromString
 
 type PublicKey = Encoded
 
@@ -199,7 +204,7 @@ tGetRaw h = do
   return (signature, corrId, queueId, command)
 
 tPut :: MonadIO m => Handle -> Transmission -> m ()
-tPut h (signature, (corrId, queueId, command)) = tPutRaw h (encode signature, corrId, encode queueId, serializeCommand command)
+tPut h (signature, (corrId, queueId, command)) = tPutRaw h (encode signature, bs corrId, encode queueId, serializeCommand command)
 
 fromClient :: Cmd -> Either ErrorType Cmd
 fromClient = \case
@@ -220,13 +225,13 @@ tGet fromParty h = do
   either (const $ tError corrId) tParseLoadBody decodedTransmission
   where
     tError :: ByteString -> m TransmissionOrError
-    tError corrId = return (B.empty, (corrId, B.empty, Left $ SYNTAX errBadTransmission))
+    tError corrId = return (B.empty, (CorrId corrId, B.empty, Left $ SYNTAX errBadTransmission))
 
     tParseLoadBody :: RawTransmission -> m TransmissionOrError
     tParseLoadBody t@(signature, corrId, queueId, command) = do
       let cmd = parseCommand command >>= fromParty >>= tCredentials t
       fullCmd <- either (return . Left) cmdWithMsgBody cmd
-      return (signature, (corrId, queueId, fullCmd))
+      return (signature, (CorrId corrId, queueId, fullCmd))
 
     tCredentials :: RawTransmission -> Cmd -> Either ErrorType Cmd
     tCredentials (signature, _, queueId, _) cmd = case cmd of

tests/Test.hs

@@ -25,7 +25,7 @@ main = hspec do
     describe "duplex communication over 2 SMP connections" testDuplex
     describe "switch subscription to another SMP queue" testSwitchSub
 
-pattern Resp :: CorrelationId -> QueueId -> Command 'Broker -> TransmissionOrError
+pattern Resp :: CorrId -> QueueId -> Command 'Broker -> TransmissionOrError
 pattern Resp corrId queueId command <- ("", (corrId, queueId, Right (Cmd SBroker command)))
 
 sendRecv :: Handle -> (ByteString, ByteString, ByteString, ByteString) -> IO TransmissionOrError