ntf protocol version negotiation (#467)

src/Simplex/Messaging/Notifications/Transport.hs

@@ -1,7 +1,13 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
 module Simplex.Messaging.Notifications.Transport where
 
 import Control.Monad.Except
 import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
 import Simplex.Messaging.Transport
 import Simplex.Messaging.Version
 
@@ -11,13 +17,56 @@ ntfBlockSize = 512
 supportedNTFServerVRange :: VersionRange
 supportedNTFServerVRange = mkVersionRange 1 1
 
+data NtfServerHandshake = NtfServerHandshake
+  { ntfVersionRange :: VersionRange,
+    sessionId :: SessionId
+  }
+
+data NtfClientHandshake = NtfClientHandshake
+  { -- | agreed SMP notifications server protocol version
+    ntfVersion :: Version,
+    -- | server identity - CA certificate fingerprint
+    keyHash :: C.KeyHash
+  }
+
+instance Encoding NtfServerHandshake where
+  smpEncode NtfServerHandshake {ntfVersionRange, sessionId} =
+    smpEncode (ntfVersionRange, sessionId)
+  smpP = do
+    (ntfVersionRange, sessionId) <- smpP
+    pure NtfServerHandshake {ntfVersionRange, sessionId}
+
+instance Encoding NtfClientHandshake where
+  smpEncode NtfClientHandshake {ntfVersion, keyHash} = smpEncode (ntfVersion, keyHash)
+  smpP = do
+    (ntfVersion, keyHash) <- smpP
+    pure NtfClientHandshake {ntfVersion, keyHash}
+
 -- | Notifcations server transport handshake.
-ntfServerHandshake :: Transport c => c -> C.KeyHash -> VersionRange -> ExceptT TransportError IO (THandle c)
-ntfServerHandshake c _ _ = pure $ ntfTHandle c
+ntfServerHandshake :: forall c. Transport c => c -> C.KeyHash -> VersionRange -> ExceptT TransportError IO (THandle c)
+ntfServerHandshake c kh ntfVRange = do
+  let th@THandle {sessionId} = ntfTHandle c
+  sendHandshake th $ NtfServerHandshake {sessionId, ntfVersionRange = ntfVRange}
+  getHandshake th >>= \case
+    NtfClientHandshake {ntfVersion, keyHash}
+      | keyHash /= kh ->
+        throwError $ TEHandshake IDENTITY
+      | ntfVersion `isCompatible` ntfVRange -> do
+        pure (th :: THandle c) {thVersion = ntfVersion}
+      | otherwise -> throwError $ TEHandshake VERSION
 
 -- | Notifcations server client transport handshake.
-ntfClientHandshake :: Transport c => c -> C.KeyHash -> VersionRange -> ExceptT TransportError IO (THandle c)
-ntfClientHandshake c _ _ = pure $ ntfTHandle c
+ntfClientHandshake :: forall c. Transport c => c -> C.KeyHash -> VersionRange -> ExceptT TransportError IO (THandle c)
+ntfClientHandshake c keyHash ntfVRange = do
+  let th@THandle {sessionId} = ntfTHandle c
+  NtfServerHandshake {sessionId = sessId, ntfVersionRange} <- getHandshake th
+  if sessionId /= sessId
+    then throwError TEBadSession
+    else case ntfVersionRange `compatibleVersion` ntfVRange of
+      Just (Compatible ntfVersion) -> do
+        sendHandshake th $ NtfClientHandshake {ntfVersion, keyHash}
+        pure (th :: THandle c) {thVersion = ntfVersion}
+      Nothing -> throwError $ TEHandshake VERSION
 
 ntfTHandle :: Transport c => c -> THandle c
 ntfTHandle c = THandle {connection = c, sessionId = tlsUnique c, blockSize = ntfBlockSize, thVersion = 0}

src/Simplex/Messaging/Transport.hs

@@ -46,12 +46,15 @@ module Simplex.Messaging.Transport
     -- * SMP transport
     THandle (..),
     TransportError (..),
+    HandshakeError (..),
     smpServerHandshake,
     smpClientHandshake,
     tPutBlock,
     tGetBlock,
     serializeTransportError,
     transportErrorP,
+    sendHandshake,
+    getHandshake,
 
     -- * Trim trailing CR
     trimCR,