servers: better socket leak prevention during TLS handshake, add NetworkError type to better diagnose connection errors (#1619)

* servers: better socket leak prevention during TLS handshake

* log tcp connection errors

* more detailed network error

* log full address

* rename error

* add encodings for NetworkError

* refactor

* comment

* bind

* style

* remove parameters of NETWORK error from encoding

src/Simplex/FileTransfer/Client.hs

@@ -59,6 +59,8 @@ import Simplex.Messaging.Protocol
     RecipientId,
     SenderId,
     pattern NoEntity,
+    NetworkError (..),
+    toNetworkError,
   )
 import Simplex.Messaging.Transport (ALPN, CertChainPubKey (..), HandshakeError (..), THandleAuth (..), THandleParams (..), TransportError (..), TransportPeer (..), defaultSupportedParams)
 import Simplex.Messaging.Transport.Client (TransportClientConfig (..), TransportHost)
@@ -191,7 +193,7 @@ xftpHTTP2Config transportConfig XFTPClientConfig {xftpNetworkConfig = NetworkCon
 xftpClientError :: HTTP2ClientError -> XFTPClientError
 xftpClientError = \case
   HCResponseTimeout -> PCEResponseTimeout
-  HCNetworkError -> PCENetworkError
+  HCNetworkError e -> PCENetworkError e
   HCIOError e -> PCEIOError e
 
 sendXFTPCommand :: forall p. FilePartyI p => XFTPClient -> C.APrivateAuthKey -> XFTPFileId -> FileCommand p -> Maybe XFTPChunkSpec -> ExceptT XFTPClientError IO (FileResponse, HTTP2Body)
@@ -261,9 +263,9 @@ downloadXFTPChunk g c@XFTPClient {config} rpKey fId chunkSpec@XFTPRcvChunkSpec {
         ExceptT (sequence <$> (t `timeout` (download cbState `catches` errors))) >>= maybe (throwE PCEResponseTimeout) pure
         where
           errors =
-            [ Handler $ \(_e :: H.HTTP2Error) -> pure $ Left PCENetworkError,
-              Handler $ \(e :: IOException) -> pure $ Left (PCEIOError e),
-              Handler $ \(_e :: SomeException) -> pure $ Left PCENetworkError
+            [ Handler $ \(e :: H.HTTP2Error) -> pure $ Left $ PCENetworkError $ NEConnectError $ displayException e,
+              Handler $ \(e :: IOException) -> pure $ Left $ PCEIOError e,
+              Handler $ \(e :: SomeException) -> pure $ Left $ PCENetworkError $ toNetworkError e
             ]
           download cbState =
             runExceptT . withExceptT PCEResponseError $

src/Simplex/Messaging/Agent/Client.hs

@@ -250,6 +250,7 @@ import Simplex.Messaging.Protocol
     EntityId (..),
     ServiceId,
     ErrorType,
+    NetworkError (..),
     MsgFlags (..),
     MsgId,
     NtfServer,
@@ -1199,12 +1200,12 @@ protocolClientError protocolError_ host = \case
   PCEResponseError e -> BROKER host $ RESPONSE $ B.unpack $ smpEncode e
   PCEUnexpectedResponse e -> BROKER host $ UNEXPECTED $ B.unpack e
   PCEResponseTimeout -> BROKER host TIMEOUT
-  PCENetworkError -> BROKER host NETWORK
+  PCENetworkError e -> BROKER host $ NETWORK e
   PCEIncompatibleHost -> BROKER host HOST
   PCETransportError e -> BROKER host $ TRANSPORT e
   e@PCECryptoError {} -> INTERNAL $ show e
   PCEServiceUnavailable {} -> BROKER host NO_SERVICE
-  PCEIOError {} -> BROKER host NETWORK
+  PCEIOError e -> BROKER host $ NETWORK $ NEConnectError $ E.displayException e
 
 data ProtocolTestStep
   = TSConnect
@@ -1478,7 +1479,7 @@ temporaryAgentError = \case
   _ -> False
   where
     tempBrokerError = \case
-      NETWORK -> True
+      NETWORK _ -> True
       TIMEOUT -> True
       _ -> False
 
@@ -1518,7 +1519,7 @@ subscribeQueues c qs = do
     subscribeQueues_ env session smp qs' = do
       let (userId, srv, _) = transportSession' smp
       atomically $ incSMPServerStat' c userId srv connSubAttempts $ length qs'
-      rs <- sendBatch (\smp' _ -> subscribeSMPQueues smp')  smp NRMBackground qs'
+      rs <- sendBatch (\smp' _ -> subscribeSMPQueues smp') smp NRMBackground qs'
       active <-
         atomically $
           ifM
@@ -1529,7 +1530,8 @@ subscribeQueues c qs = do
         then when (hasTempErrors rs) resubscribe $> rs
         else do
           logWarn "subcription batch result for replaced SMP client, resubscribing"
-          resubscribe $> L.map (second $ \_ -> Left PCENetworkError) rs
+          -- TODO we probably use PCENetworkError here instead of the original error, so it becomes temporary.
+          resubscribe $> L.map (second $ Left . PCENetworkError . NESubscribeError . show) rs
       where
         tSess = transportSession' smp
         sessId = sessionId $ thParams smp

src/Simplex/Messaging/Client.hs

@@ -597,12 +597,14 @@ getProtocolClient g nm transportSession@(_, srv, _) cfg@ProtocolClientConfig {qS
           socksCreds = clientSocksCredentials networkConfig proxySessTs transportSession
       tId <-
         runTransportClient tcConfig socksCreds useHost port' (Just $ keyHash srv) (client t c cVar)
-          `forkFinally` \_ -> void (atomically . tryPutTMVar cVar $ Left PCENetworkError)
+          `forkFinally` \r ->
+            let err = either toNetworkError (const NEFailedError) r
+             in void $ atomically $ tryPutTMVar cVar $ Left $ PCENetworkError err
       c_ <- netTimeoutInt tcpConnectTimeout nm `timeout` atomically (takeTMVar cVar)
       case c_ of
         Just (Right c') -> mkWeakThreadId tId >>= \tId' -> pure $ Right c' {action = Just tId'}
         Just (Left e) -> pure $ Left e
-        Nothing -> killThread tId $> Left PCENetworkError
+        Nothing -> killThread tId $> Left (PCENetworkError NETimeoutError)
 
     useTransport :: (ServiceName, ATransport 'TClient)
     useTransport = case port srv of
@@ -743,7 +745,7 @@ data ProtocolClientError err
     PCEResponseTimeout
   | -- | Failure to establish TCP connection.
     -- Forwarded to the agent client as `ERR BROKER NETWORK`.
-    PCENetworkError
+    PCENetworkError NetworkError
   | -- | No host compatible with network configuration
     PCEIncompatibleHost
   | -- | Service is unavailable for command that requires service connection
@@ -761,7 +763,7 @@ type SMPClientError = ProtocolClientError ErrorType
 
 temporaryClientError :: ProtocolClientError err -> Bool
 temporaryClientError = \case
-  PCENetworkError -> True
+  PCENetworkError _ -> True
   PCEResponseTimeout -> True
   PCEIOError _ -> True
   _ -> False
@@ -782,7 +784,7 @@ smpProxyError = \case
   PCEResponseError e -> PROXY $ BROKER $ RESPONSE $ B.unpack $ strEncode e
   PCEUnexpectedResponse e -> PROXY $ BROKER $ UNEXPECTED $ B.unpack e
   PCEResponseTimeout -> PROXY $ BROKER TIMEOUT
-  PCENetworkError -> PROXY $ BROKER NETWORK
+  PCENetworkError e -> PROXY $ BROKER $ NETWORK e
   PCEIncompatibleHost -> PROXY $ BROKER HOST
   PCEServiceUnavailable -> PROXY $ BROKER $ NO_SERVICE -- for completeness, it cannot happen.
   PCETransportError t -> PROXY $ BROKER $ TRANSPORT t

src/Simplex/Messaging/Client/Agent.hs

@@ -391,7 +391,7 @@ withSMP ca srv action = (getSMPServerClient' ca srv >>= action) `catchE` logSMPE
   where
     logSMPError :: SMPClientError -> ExceptT SMPClientError IO a
     logSMPError e = do
-      logInfo $ "SMP error (" <> safeDecodeUtf8 (strEncode $ host srv) <> "): " <> tshow e
+      logInfo $ "SMP error (" <> safeDecodeUtf8 (strEncode srv) <> "): " <> tshow e
       throwE e
 
 subscribeQueuesNtfs :: SMPClientAgent 'NotifierService -> SMPServer -> NonEmpty (NotifierId, NtfPrivateAuthKey) -> IO ()

src/Simplex/Messaging/Notifications/Server.hs

@@ -613,7 +613,7 @@ ntfSubscriber NtfSubscriber {smpAgent = ca@SMPClientAgent {msgQ, agentQ}} =
       PCEIncompatibleHost -> Just $ NSErr "IncompatibleHost"
       PCEServiceUnavailable -> Just NSService -- this error should not happen on individual subscriptions
       PCEResponseTimeout -> Nothing
-      PCENetworkError -> Nothing
+      PCENetworkError _ -> Nothing
       PCEIOError _ -> Nothing
       where
         -- Note on moving to PostgreSQL: the idea of logging errors without e is removed here

src/Simplex/Messaging/Protocol.hs

@@ -81,6 +81,7 @@ module Simplex.Messaging.Protocol
     CommandError (..),
     ProxyError (..),
     BrokerErrorType (..),
+    NetworkError (..),
     BlockingInfo (..),
     BlockingReason (..),
     RawTransmission,
@@ -168,6 +169,7 @@ module Simplex.Messaging.Protocol
     noMsgFlags,
     messageId,
     messageTs,
+    toNetworkError,
 
     -- * Parse and serialize
     ProtocolMsgTag (..),
@@ -212,7 +214,7 @@ module Simplex.Messaging.Protocol
 where
 
 import Control.Applicative (optional, (<|>))
-import Control.Exception (Exception)
+import Control.Exception (Exception, SomeException, displayException, fromException)
 import Control.Monad.Except
 import Data.Aeson (FromJSON (..), ToJSON (..))
 import qualified Data.Aeson.TH as J
@@ -241,6 +243,7 @@ import GHC.TypeLits (ErrorMessage (..), TypeError, type (+))
 import qualified GHC.TypeLits as TE
 import qualified GHC.TypeLits as Type
 import Network.Socket (ServiceName)
+import qualified Network.TLS as TLS
 import Simplex.Messaging.Agent.Store.DB (Binary (..), FromField (..), ToField (..))
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
@@ -1555,7 +1558,7 @@ data BrokerErrorType
   | -- | unexpected response
     UNEXPECTED {respErr :: String}
   | -- | network error
-    NETWORK
+    NETWORK {networkError :: NetworkError}
   | -- | no compatible server host (e.g. onion when public is required, or vice versa)
     HOST
   | -- | service unavailable client-side - used in agent errors
@@ -1566,6 +1569,24 @@ data BrokerErrorType
     TIMEOUT
   deriving (Eq, Read, Show, Exception)
 
+data NetworkError
+  = NEConnectError {connectError :: String}
+  | NETLSError {tlsError :: String}
+  | NEUnknownCAError
+  | NEFailedError
+  | NETimeoutError
+  | NESubscribeError {subscribeError :: String}
+  deriving (Eq, Read, Show)
+
+toNetworkError :: SomeException -> NetworkError
+toNetworkError e = maybe (NEConnectError err) fromTLSError (fromException e)
+  where
+    err = displayException e
+    fromTLSError :: TLS.TLSException -> NetworkError
+    fromTLSError = \case
+      TLS.HandshakeFailed (TLS.Error_Protocol _ TLS.UnknownCa) -> NEUnknownCAError
+      _ -> NETLSError err
+
 data BlockingInfo = BlockingInfo
   { reason :: BlockingReason
   }
@@ -2001,7 +2022,7 @@ instance Encoding BrokerErrorType where
     RESPONSE e -> "RESPONSE " <> smpEncode e
     UNEXPECTED e -> "UNEXPECTED " <> smpEncode e
     TRANSPORT e -> "TRANSPORT " <> smpEncode e
-    NETWORK -> "NETWORK"
+    NETWORK e -> "NETWORK" -- TODO once all upgrade: "NETWORK " <> smpEncode e
     TIMEOUT -> "TIMEOUT"
     HOST -> "HOST"
     NO_SERVICE -> "NO_SERVICE"
@@ -2010,7 +2031,7 @@ instance Encoding BrokerErrorType where
       "RESPONSE" -> RESPONSE <$> _smpP
       "UNEXPECTED" -> UNEXPECTED <$> _smpP
       "TRANSPORT" -> TRANSPORT <$> _smpP
-      "NETWORK" -> pure NETWORK
+      "NETWORK" -> NETWORK <$> (_smpP <|> pure NEFailedError)
       "TIMEOUT" -> pure TIMEOUT
       "HOST" -> pure HOST
       "NO_SERVICE" -> pure NO_SERVICE
@@ -2021,7 +2042,7 @@ instance StrEncoding BrokerErrorType where
     RESPONSE e -> "RESPONSE " <> encodeUtf8 (T.pack e)
     UNEXPECTED e -> "UNEXPECTED " <> encodeUtf8 (T.pack e)
     TRANSPORT e -> "TRANSPORT " <> smpEncode e
-    NETWORK -> "NETWORK"
+    NETWORK e -> "NETWORK" -- TODO once all upgrade: "NETWORK " <> strEncode e
     TIMEOUT -> "TIMEOUT"
     HOST -> "HOST"
     NO_SERVICE -> "NO_SERVICE"
@@ -2030,13 +2051,50 @@ instance StrEncoding BrokerErrorType where
       "RESPONSE" -> RESPONSE <$> _textP
       "UNEXPECTED" -> UNEXPECTED <$> _textP
       "TRANSPORT" -> TRANSPORT <$> _smpP
-      "NETWORK" -> pure NETWORK
+      "NETWORK" -> NETWORK <$> (_strP <|> pure NEFailedError)
       "TIMEOUT" -> pure TIMEOUT
       "HOST" -> pure HOST
       "NO_SERVICE" -> pure NO_SERVICE
       _ -> fail "bad BrokerErrorType"
-    where
-      _textP = A.space *> (T.unpack . safeDecodeUtf8 <$> A.takeByteString)
+
+instance Encoding NetworkError where
+  smpEncode = \case
+    NEConnectError e -> "CONNECT " <> smpEncode e
+    NETLSError e -> "TLS " <> smpEncode e
+    NEUnknownCAError -> "UNKNOWNCA"
+    NEFailedError -> "FAILED"
+    NETimeoutError -> "TIMEOUT"
+    NESubscribeError e -> "SUBSCRIBE " <> smpEncode e
+  smpP =
+    A.takeTill (== ' ') >>= \case
+      "CONNECT" -> NEConnectError <$> _smpP
+      "TLS" -> NETLSError <$> _smpP
+      "UNKNOWNCA" -> pure NEUnknownCAError
+      "FAILED" -> pure NEFailedError
+      "TIMEOUT" -> pure NETimeoutError
+      "SUBSCRIBE" -> NESubscribeError <$> _smpP
+      _ -> fail "bad NetworkError"
+
+instance StrEncoding NetworkError where
+  strEncode = \case
+    NEConnectError e -> "CONNECT " <> encodeUtf8 (T.pack e)
+    NETLSError e -> "TLS " <> encodeUtf8 (T.pack e)
+    NEUnknownCAError -> "UNKNOWNCA"
+    NEFailedError -> "FAILED"
+    NETimeoutError -> "TIMEOUT"
+    NESubscribeError e -> "SUBSCRIBE " <> encodeUtf8 (T.pack e)
+  strP =
+    A.takeTill (== ' ') >>= \case
+      "CONNECT" -> NEConnectError <$> _textP
+      "TLS" -> NETLSError <$> _textP
+      "UNKNOWNCA" -> pure NEUnknownCAError
+      "FAILED" -> pure NEFailedError
+      "TIMEOUT" -> pure NETimeoutError
+      "SUBSCRIBE" -> NESubscribeError <$> _textP
+      _ -> fail "bad NetworkError"
+
+_textP :: Parser String
+_textP = A.space *> (T.unpack . safeDecodeUtf8 <$> A.takeByteString)
 
 -- | Send signed SMP transmission to TCP transport.
 tPut :: Transport c => THandle v c p -> NonEmpty (Either TransportError SentRawTransmission) -> IO [Either TransportError ()]
@@ -2200,6 +2258,8 @@ $(J.deriveJSON defaultJSON ''MsgFlags)
 
 $(J.deriveJSON (sumTypeJSON id) ''CommandError)
 
+$(J.deriveJSON (sumTypeJSON $ dropPrefix "NE") ''NetworkError)
+
 $(J.deriveJSON (sumTypeJSON id) ''BrokerErrorType)
 
 $(J.deriveJSON defaultJSON ''BlockingInfo)

src/Simplex/Messaging/Server/Information.hs

@@ -14,7 +14,7 @@ import qualified Data.Attoparsec.ByteString.Char8 as A
 import Data.Int (Int64)
 import Data.Maybe (isJust)
 import Data.Text (Text)
-import Simplex.Messaging.Agent.Protocol (ConnectionLink, ConnectionMode (..), ConnectionRequestUri)
+import Simplex.Messaging.Agent.Protocol (ConnectionLink, ConnectionMode (..))
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Parsers (defaultJSON, dropPrefix, enumJSON)
 

src/Simplex/Messaging/Transport/Client.hs

@@ -30,12 +30,14 @@ where
 
 import Control.Applicative (optional, (<|>))
 import Control.Logger.Simple (logError)
+import Control.Monad
 import Data.Aeson (FromJSON (..), ToJSON (..))
 import qualified Data.Attoparsec.ByteString.Char8 as A
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.Char (isAsciiLower, isDigit, isHexDigit)
 import Data.Default (def)
+import Data.Functor (($>))
 import Data.IORef
 import Data.IP
 import Data.List.NonEmpty (NonEmpty (..))
@@ -58,7 +60,7 @@ import Simplex.Messaging.Parsers (parseAll, parseString)
 import Simplex.Messaging.Transport
 import Simplex.Messaging.Transport.KeepAlive
 import Simplex.Messaging.Transport.Shared
-import Simplex.Messaging.Util (bshow, catchAll, tshow, (<$?>))
+import Simplex.Messaging.Util (bshow, catchAll, catchAll_, tshow, (<$?>))
 import System.IO.Error
 import Text.Read (readMaybe)
 import UnliftIO.Exception (IOException)
@@ -156,6 +158,11 @@ clientTransportConfig TransportClientConfig {logTLSErrors} =
 runTransportClient :: Transport c => TransportClientConfig -> Maybe SocksCredentials -> TransportHost -> ServiceName -> Maybe C.KeyHash -> (c 'TClient -> IO a) -> IO a
 runTransportClient = runTLSTransportClient defaultSupportedParams Nothing
 
+data ConnectionHandle c
+  = CHSocket Socket
+  | CHContext T.Context
+  | CHTransport (c 'TClient)
+
 runTLSTransportClient :: Transport c => T.Supported -> Maybe XS.CertificateStore -> TransportClientConfig -> Maybe SocksCredentials -> TransportHost -> ServiceName -> Maybe C.KeyHash -> (c 'TClient -> IO a) -> IO a
 runTLSTransportClient tlsParams caStore_ cfg@TransportClientConfig {socksProxy, tcpKeepAlive, clientCredentials, clientALPN, useSNI} socksCreds host port keyHash client = do
   serverCert <- newEmptyTMVarIO
@@ -165,17 +172,22 @@ runTLSTransportClient tlsParams caStore_ cfg@TransportClientConfig {socksProxy,
       connectTCP = case socksProxy of
         Just proxy -> connectSocksClient proxy socksCreds (hostAddr host)
         _ -> connectTCPClient hostName
-  c <- do
-    sock <- connectTCP port
-    mapM_ (setSocketKeepAlive sock) tcpKeepAlive `catchAll` \e -> logError ("Error setting TCP keep-alive" <> tshow e)
+  h <- newIORef Nothing
+  let set hc = (>>= \c -> writeIORef h (Just $ hc c) $> c)
+  E.bracket (set CHSocket $ connectTCP port) (\_ -> closeConn h) $ \sock -> do
+    mapM_ (setSocketKeepAlive sock) tcpKeepAlive `catchAll` \e -> logError ("Error setting TCP keep-alive " <> tshow e)
     let tCfg = clientTransportConfig cfg
     -- No TLS timeout to avoid failing connections via SOCKS
-    tls <- connectTLS (Just hostName) tCfg clientParams sock
-    chain <- takePeerCertChain serverCert `E.onException` closeTLS tls
+    tls <- set CHContext $ connectTLS (Just hostName) tCfg clientParams sock
+    chain <- takePeerCertChain serverCert
     sent <- readIORef clientCredsSent
-    getTransportConnection tCfg sent chain tls
-  client c `E.finally` closeConnection c
+    client =<< set CHTransport (getTransportConnection tCfg sent chain tls)
   where
+    closeConn = readIORef >=> mapM_ (\c -> E.uninterruptibleMask_ $ closeConn_ c `catchAll_` pure ())
+    closeConn_ = \case
+      CHSocket sock -> close sock
+      CHContext tls -> closeTLS tls
+      CHTransport c -> closeConnection c
     hostAddr = \case
       THIPv4 addr -> SocksAddrIPV4 $ tupleToHostAddress addr
       THIPv6 addr -> SocksAddrIPV6 addr
@@ -199,10 +211,11 @@ connectTCPClient host port = withSocketsDo $ resolve >>= tryOpen err
       E.try (open addr) >>= either (`tryOpen` as) pure
 
     open :: AddrInfo -> IO Socket
-    open addr = do
-      sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
-      connect sock $ addrAddress addr
-      pure sock
+    open addr =
+      E.bracketOnError
+        (socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr))
+        close
+        (\sock -> connect sock (addrAddress addr) $> sock)
 
 defaultSMPPort :: PortNumber
 defaultSMPPort = 5223

src/Simplex/Messaging/Transport/HTTP2/Client.hs

@@ -27,6 +27,7 @@ import qualified Network.TLS as T
 import Numeric.Natural (Natural)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Protocol (NetworkError (..), toNetworkError)
 import Simplex.Messaging.Transport (ALPN, STransportPeer (..), SessionId, TLS (tlsALPN, tlsPeerCert, tlsUniq), TransportPeer (..), TransportPeerI (..), getServerVerifyKey)
 import Simplex.Messaging.Transport.Client (TransportClientConfig (..), TransportHost (..), defaultTcpConnectTimeout, runTLSTransportClient)
 import Simplex.Messaging.Transport.HTTP2
@@ -89,7 +90,7 @@ defaultHTTP2ClientConfig =
       suportedTLSParams = http2TLSParams
     }
 
-data HTTP2ClientError = HCResponseTimeout | HCNetworkError | HCIOError IOException
+data HTTP2ClientError = HCResponseTimeout | HCNetworkError NetworkError | HCIOError IOException
   deriving (Show)
 
 getHTTP2Client :: HostName -> ServiceName -> Maybe XS.CertificateStore -> HTTP2ClientConfig -> IO () -> IO (Either HTTP2ClientError HTTP2Client)
@@ -121,12 +122,15 @@ getVerifiedHTTP2ClientWith config host port disconnected setup =
     runClient :: HClient -> IO (Either HTTP2ClientError HTTP2Client)
     runClient c = do
       cVar <- newEmptyTMVarIO
-      action <- async $ setup (client c cVar) `E.finally` atomically (putTMVar cVar $ Left HCNetworkError)
+      action <-
+        async $ setup (client c cVar) `E.catch` \e -> do
+          atomically $ putTMVar cVar $ Left $ HCNetworkError $ toNetworkError e
+          E.throwIO e
       c_ <- connTimeout config `timeout` atomically (takeTMVar cVar)
       case c_ of
         Just (Right c') -> pure $ Right c' {action = Just action}
         Just (Left e) -> pure $ Left e
-        Nothing -> cancel action $> Left HCNetworkError
+        Nothing -> cancel action $> Left (HCNetworkError NETimeoutError)
 
     client :: HClient -> TMVar (Either HTTP2ClientError HTTP2Client) -> TLS p -> H.Client HTTP2Response
     client c cVar tls sendReq = do
@@ -176,7 +180,7 @@ sendRequestDirect HTTP2Client {client_ = HClient {config, disconnected}, sendReq
   reqTimeout `timeout` try (sendReq req process) >>= \case
     Just (Right r) -> pure $ Right r
     Just (Left e) -> disconnected $> Left (HCIOError e)
-    Nothing -> pure $ Left HCNetworkError
+    Nothing -> pure $ Left HCResponseTimeout
   where
     process r = do
       respBody <- getHTTP2Body r $ bodyHeadSize config