implement p2p protocol for Handle
This is most of the way to having the p2p protocol working over tor hidden services, at least enough to do git push/pull. The free monad was split into two, one for network operations and the other for local (Annex) operations. This will allow git-remote-tor-annex to run only an IO action, not needing the Annex monad. This commit was sponsored by Remy van Elst on Patreon.
This commit is contained in:
Joey Hess
parent
0eaad7ca3a
commit
d50b0f3bb3
3 changed files with 455 additions and 277 deletions
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@ -7,20 +7,7 @@
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{-# LANGUAGE DeriveFunctor, TemplateHaskell, FlexibleContexts, RankNTypes #-}
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module Remote.Helper.P2P (
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AuthToken(..),
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ProtoF(..),
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runPure,
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protoDump,
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auth,
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checkPresent,
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lockContentWhile,
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remove,
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get,
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put,
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connect,
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serve,
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) where
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module Remote.Helper.P2P where
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import qualified Utility.SimpleProtocol as Proto
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import Types.Key
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@ -33,7 +20,7 @@ import Control.Monad.Free
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import Control.Monad.Free.TH
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import Control.Monad.Catch
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import System.Exit (ExitCode(..))
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import System.IO (Handle)
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import System.IO
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import qualified Data.ByteString.Lazy as L
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newtype AuthToken = AuthToken String
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@ -49,10 +36,6 @@ newtype Len = Len Integer
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data Service = UploadPack | ReceivePack
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deriving (Show)
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data RelayData
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= RelayData L.ByteString
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| RelayMessage Message
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-- | Messages in the protocol. The peer that makes the connection
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-- always initiates requests, and the other peer makes responses to them.
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data Message
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@ -75,264 +58,6 @@ data Message
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| ERROR String
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deriving (Show)
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-- | Free monad for implementing actions that use the protocol.
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data ProtoF next
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= SendMessage Message next
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| ReceiveMessage (Message -> next)
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| SendBytes Len L.ByteString next
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| ReceiveBytes Len (L.ByteString -> next)
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-- ^ Lazily reads bytes from peer. Stops once Len are read,
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-- or if connection is lost, and in either case returns the bytes
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-- that were read. This allows resuming interrupted transfers.
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| KeyFileSize Key (Len -> next)
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-- ^ Checks size of key file (dne = 0)
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| ReadKeyFile Key Offset (L.ByteString -> next)
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| WriteKeyFile Key Offset Len L.ByteString (Bool -> next)
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-- ^ Writes to key file starting at an offset. Returns True
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-- once the whole content of the key is stored in the key file.
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--
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-- Note: The ByteString may not contain the entire remaining content
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-- of the key. Only once the key file size == Len has the whole
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-- content been transferred.
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| CheckAuthToken UUID AuthToken (Bool -> next)
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| SetPresent Key UUID next
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| CheckContentPresent Key (Bool -> next)
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-- ^ Checks if the whole content of the key is locally present.
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| RemoveKeyFile Key (Bool -> next)
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-- ^ If the key file is not present, still succeeds.
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-- May fail if not enough copies to safely drop, etc.
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| TryLockContent Key (Bool -> Proto ()) next
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| WriteHandle Handle L.ByteString next
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-- ^ Try to lock the content of a key, preventing it
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-- from being deleted, and run the provided protocol action.
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| Relay Handle (RelayData -> Proto (Maybe ExitCode)) (ExitCode -> next)
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-- ^ Waits for data to be written to the Handle, and for messages
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-- to be received from the peer, and passes the data to the
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-- callback, continuing until it returns an ExitCode.
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| RelayService Service
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(Handle -> RelayData -> Proto (Maybe ExitCode))
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(ExitCode -> next)
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-- ^ Runs a service, and waits for it to output to stdout,
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-- and for messages to be received from the peer, and passes
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-- the data to the callback (which is also passed the service's
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-- stdin Handle), continuing uniil the service exits.
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deriving (Functor)
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type Proto = Free ProtoF
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$(makeFree ''ProtoF)
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-- | Running Proto actions purely, to see what they do.
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runPure :: Show r => Proto r -> [Message] -> [(String, Maybe Message)]
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runPure (Pure r) _ = [("result: " ++ show r, Nothing)]
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runPure (Free (SendMessage m next)) ms = (">", Just m):runPure next ms
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runPure (Free (ReceiveMessage _)) [] = [("not enough Messages provided", Nothing)]
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runPure (Free (ReceiveMessage next)) (m:ms) = ("<", Just m):runPure (next m) ms
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runPure (Free (SendBytes _ _ next)) ms = ("> bytes", Nothing):runPure next ms
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runPure (Free (ReceiveBytes _ next)) ms = ("< bytes", Nothing):runPure (next L.empty) ms
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runPure (Free (KeyFileSize _ next)) ms = runPure (next (Len 100)) ms
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runPure (Free (ReadKeyFile _ _ next)) ms = runPure (next L.empty) ms
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runPure (Free (WriteKeyFile _ _ _ _ next)) ms = runPure (next True) ms
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runPure (Free (CheckAuthToken _ _ next)) ms = runPure (next True) ms
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runPure (Free (SetPresent _ _ next)) ms = runPure next ms
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runPure (Free (CheckContentPresent _ next)) ms = runPure (next False) ms
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runPure (Free (RemoveKeyFile _ next)) ms = runPure (next True) ms
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runPure (Free (TryLockContent _ p next)) ms = runPure (p True >> next) ms
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runPure (Free (WriteHandle _ _ next)) ms = runPure next ms
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runPure (Free (Relay _ _ next)) ms = runPure (next ExitSuccess) ms
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runPure (Free (RelayService _ _ next)) ms = runPure (next ExitSuccess) ms
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protoDump :: [(String, Maybe Message)] -> String
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protoDump = unlines . map protoDump'
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protoDump' :: (String, Maybe Message) -> String
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protoDump' (s, Nothing) = s
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protoDump' (s, Just m) = s ++ " " ++ unwords (Proto.formatMessage m)
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auth :: UUID -> AuthToken -> Proto (Maybe UUID)
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auth myuuid t = do
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sendMessage (AUTH myuuid t)
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r <- receiveMessage
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case r of
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AUTH_SUCCESS theiruuid -> return $ Just theiruuid
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AUTH_FAILURE -> return Nothing
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_ -> do
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sendMessage (ERROR "auth failed")
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return Nothing
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checkPresent :: Key -> Proto Bool
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checkPresent key = do
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sendMessage (CHECKPRESENT key)
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checkSuccess
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{- Locks content to prevent it from being dropped, while running an action.
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-
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- Note that this only guarantees that the content is locked as long as the
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- connection to the peer remains up. If the connection is unexpectededly
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- dropped, the peer will then unlock the content.
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-}
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lockContentWhile
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:: MonadMask m
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=> (forall r. Proto r -> m r)
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-> Key
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-> (Bool -> m ())
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-> m ()
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lockContentWhile runproto key a = bracket setup cleanup a
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where
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setup = runproto $ do
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sendMessage (LOCKCONTENT key)
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checkSuccess
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cleanup True = runproto $ sendMessage UNLOCKCONTENT
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cleanup False = return ()
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remove :: Key -> Proto Bool
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remove key = do
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sendMessage (REMOVE key)
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checkSuccess
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get :: Key -> Proto Bool
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get key = receiveContent key (`GET` key)
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put :: Key -> Proto Bool
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put key = do
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sendMessage (PUT key)
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r <- receiveMessage
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case r of
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PUT_FROM offset -> sendContent key offset
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ALREADY_HAVE -> return True
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_ -> do
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sendMessage (ERROR "expected PUT_FROM")
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return False
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connect :: Service -> Handle -> Handle -> Proto ExitCode
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connect service hin hout = do
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sendMessage (CONNECT service)
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relay hin (relayCallback hout)
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relayCallback :: Handle -> RelayData -> Proto (Maybe ExitCode)
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relayCallback hout (RelayMessage (DATA len)) = do
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writeHandle hout =<< receiveBytes len
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return Nothing
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relayCallback _ (RelayMessage (CONNECTDONE exitcode)) =
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return (Just exitcode)
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relayCallback _ (RelayMessage _) = do
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sendMessage (ERROR "expected DATA or CONNECTDONE")
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return (Just (ExitFailure 1))
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relayCallback _ (RelayData b) = do
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let len = Len $ fromIntegral $ L.length b
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sendMessage (DATA len)
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sendBytes len b
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return Nothing
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-- | Serve the protocol.
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--
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-- Note that if the client sends an unexpected message, the server will
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-- respond with PTOTO_ERROR, and always continues processing messages.
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-- Since the protocol is not versioned, this is necessary to handle
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-- protocol changes robustly, since the client can detect when it's
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-- talking to a server that does not support some new feature, and fall
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-- back.
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--
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-- When the client sends ERROR to the server, the server gives up,
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-- since it's not clear what state the client is is, and so not possible to
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-- recover.
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serve :: UUID -> Proto ()
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serve myuuid = go Nothing
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where
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go autheduuid = do
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r <- receiveMessage
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case r of
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AUTH theiruuid authtoken -> do
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ok <- checkAuthToken theiruuid authtoken
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if ok
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then do
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sendMessage (AUTH_SUCCESS myuuid)
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go (Just theiruuid)
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else do
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sendMessage AUTH_FAILURE
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go autheduuid
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ERROR _ -> return ()
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_ -> do
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case autheduuid of
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Just theiruuid -> authed theiruuid r
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Nothing -> sendMessage (ERROR "must AUTH first")
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go autheduuid
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authed _theiruuid r = case r of
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LOCKCONTENT key -> tryLockContent key $ \locked -> do
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sendSuccess locked
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when locked $ do
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r' <- receiveMessage
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case r' of
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UNLOCKCONTENT -> return ()
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_ -> sendMessage (ERROR "expected UNLOCKCONTENT")
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CHECKPRESENT key -> sendSuccess =<< checkContentPresent key
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REMOVE key -> sendSuccess =<< removeKeyFile key
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PUT key -> do
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have <- checkContentPresent key
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if have
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then sendMessage ALREADY_HAVE
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else do
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ok <- receiveContent key PUT_FROM
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when ok $
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setPresent key myuuid
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-- setPresent not called because the peer may have
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-- requested the data but not permanatly stored it.
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GET offset key -> void $ sendContent key offset
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CONNECT service -> do
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exitcode <- relayService service relayCallback
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sendMessage (CONNECTDONE exitcode)
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_ -> sendMessage (ERROR "unexpected command")
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sendContent :: Key -> Offset -> Proto Bool
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sendContent key offset = do
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(len, content) <- readKeyFileLen key offset
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sendMessage (DATA len)
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sendBytes len content
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checkSuccess
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receiveContent :: Key -> (Offset -> Message) -> Proto Bool
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receiveContent key mkmsg = do
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Len n <- keyFileSize key
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let offset = Offset n
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sendMessage (mkmsg offset)
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r <- receiveMessage
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case r of
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DATA len -> do
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ok <- writeKeyFile key offset len =<< receiveBytes len
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sendSuccess ok
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return ok
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_ -> do
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sendMessage (ERROR "expected DATA")
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return False
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checkSuccess :: Proto Bool
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checkSuccess = do
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ack <- receiveMessage
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case ack of
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SUCCESS -> return True
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FAILURE -> return False
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_ -> do
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sendMessage (ERROR "expected SUCCESS or FAILURE")
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return False
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sendSuccess :: Bool -> Proto ()
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sendSuccess True = sendMessage SUCCESS
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sendSuccess False = sendMessage FAILURE
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-- Reads key file from an offset. The Len should correspond to
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-- the length of the ByteString, but to avoid buffering the content
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-- in memory, is gotten using keyFileSize.
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readKeyFileLen :: Key -> Offset -> Proto (Len, L.ByteString)
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readKeyFileLen key (Offset offset) = do
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(Len totallen) <- keyFileSize key
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let len = totallen - offset
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if len <= 0
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then return (Len 0, L.empty)
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else do
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content <- readKeyFile key (Offset offset)
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return (Len len, content)
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instance Proto.Sendable Message where
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formatMessage (AUTH uuid authtoken) = ["AUTH", Proto.serialize uuid, Proto.serialize authtoken]
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formatMessage (AUTH_SUCCESS uuid) = ["AUTH-SUCCESS", Proto.serialize uuid]
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@ -390,3 +115,296 @@ instance Proto.Serializable Service where
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deserialize "git-upload-pack" = Just UploadPack
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deserialize "git-receive-pack" = Just ReceivePack
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deserialize _ = Nothing
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-- | Free monad for the protocol, combining net communication,
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-- and local actions.
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data ProtoF c = Net (NetF c) | Local (LocalF c)
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deriving (Functor)
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type Proto = Free ProtoF
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net :: Net a -> Proto a
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net = hoistFree Net
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local :: Local a -> Proto a
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local = hoistFree Local
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data NetF c
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= SendMessage Message c
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| ReceiveMessage (Message -> c)
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| SendBytes Len L.ByteString c
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| ReceiveBytes Len (L.ByteString -> c)
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| Relay RelayHandle
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(RelayData -> Net (Maybe ExitCode))
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(ExitCode -> c)
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-- ^ Waits for data to be written to the RelayHandle, and for messages
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-- to be received from the peer, and passes the data to the
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-- callback, continuing until it returns an ExitCode.
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| RelayService Service
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(RelayHandle -> RelayData -> Net (Maybe ExitCode))
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(ExitCode -> c)
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-- ^ Runs a service, and waits for it to output to stdout,
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-- and for messages to be received from the peer, and passes
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-- the data to the callback (which is also passed the service's
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-- stdin RelayHandle), continuing uniil the service exits.
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| WriteRelay RelayHandle L.ByteString c
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-- ^ Write data to a relay's handle, flushing it immediately.
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deriving (Functor)
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type Net = Free NetF
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data RelayData
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= RelayData L.ByteString
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| RelayMessage Message
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newtype RelayHandle = RelayHandle Handle
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data LocalF c
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-- ^ Lazily reads bytes from peer. Stops once Len are read,
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-- or if connection is lost, and in either case returns the bytes
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-- that were read. This allows resuming interrupted transfers.
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= KeyFileSize Key (Len -> c)
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-- ^ Checks size of key file (dne = 0)
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| ReadKeyFile Key Offset (L.ByteString -> c)
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| WriteKeyFile Key Offset Len L.ByteString (Bool -> c)
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-- ^ Writes to key file starting at an offset. Returns True
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-- once the whole content of the key is stored in the key file.
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--
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-- Note: The ByteString may not contain the entire remaining content
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-- of the key. Only once the key file size == Len has the whole
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-- content been transferred.
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| CheckAuthToken UUID AuthToken (Bool -> c)
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| SetPresent Key UUID c
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| CheckContentPresent Key (Bool -> c)
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-- ^ Checks if the whole content of the key is locally present.
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| RemoveKeyFile Key (Bool -> c)
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-- ^ If the key file is not present, still succeeds.
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-- May fail if not enough copies to safely drop, etc.
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| TryLockContent Key (Bool -> Proto ()) c
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-- ^ Try to lock the content of a key, preventing it
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-- from being deleted, and run the provided protocol action.
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deriving (Functor)
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type Local = Free LocalF
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-- Generate sendMessage etc functions for all free monad constructors.
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$(makeFree ''NetF)
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$(makeFree ''LocalF)
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-- | Running Proto actions purely, to see what they do.
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runPure :: Show r => Proto r -> [Message] -> [(String, Maybe Message)]
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runPure (Pure r) _ = [("result: " ++ show r, Nothing)]
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runPure (Free (Net n)) ms = runNet n ms
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runPure (Free (Local n)) ms = runLocal n ms
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runNet :: Show r => NetF (Proto r) -> [Message] -> [(String, Maybe Message)]
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runNet (SendMessage m next) ms = (">", Just m):runPure next ms
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runNet (ReceiveMessage _) [] = [("not enough Messages provided", Nothing)]
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runNet (ReceiveMessage next) (m:ms) = ("<", Just m):runPure (next m) ms
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runNet (SendBytes _ _ next) ms = ("> bytes", Nothing):runPure next ms
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runNet (ReceiveBytes _ next) ms = ("< bytes", Nothing):runPure (next L.empty) ms
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runNet (Relay _ _ next) ms = runPure (next ExitSuccess) ms
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runNet (RelayService _ _ next) ms = runPure (next ExitSuccess) ms
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runNet (WriteRelay _ _ next) ms = runPure next ms
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runLocal :: Show r => LocalF (Proto r) -> [Message] -> [(String, Maybe Message)]
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runLocal (KeyFileSize _ next) ms = runPure (next (Len 100)) ms
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runLocal (ReadKeyFile _ _ next) ms = runPure (next L.empty) ms
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runLocal (WriteKeyFile _ _ _ _ next) ms = runPure (next True) ms
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runLocal (CheckAuthToken _ _ next) ms = runPure (next True) ms
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runLocal (SetPresent _ _ next) ms = runPure next ms
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runLocal (CheckContentPresent _ next) ms = runPure (next False) ms
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runLocal (RemoveKeyFile _ next) ms = runPure (next True) ms
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runLocal (TryLockContent _ p next) ms = runPure (p True >> next) ms
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protoDump :: [(String, Maybe Message)] -> String
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protoDump = unlines . map protoDump'
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protoDump' :: (String, Maybe Message) -> String
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protoDump' (s, Nothing) = s
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protoDump' (s, Just m) = s ++ " " ++ unwords (Proto.formatMessage m)
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auth :: UUID -> AuthToken -> Proto (Maybe UUID)
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auth myuuid t = do
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net $ sendMessage (AUTH myuuid t)
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r <- net receiveMessage
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case r of
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AUTH_SUCCESS theiruuid -> return $ Just theiruuid
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AUTH_FAILURE -> return Nothing
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_ -> do
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net $ sendMessage (ERROR "auth failed")
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return Nothing
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checkPresent :: Key -> Proto Bool
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checkPresent key = do
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net $ sendMessage (CHECKPRESENT key)
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checkSuccess
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{- Locks content to prevent it from being dropped, while running an action.
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-
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- Note that this only guarantees that the content is locked as long as the
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- connection to the peer remains up. If the connection is unexpectededly
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- dropped, the peer will then unlock the content.
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-}
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lockContentWhile
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:: MonadMask m
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=> (forall r. Proto r -> m r)
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-> Key
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-> (Bool -> m ())
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-> m ()
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lockContentWhile runproto key a = bracket setup cleanup a
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where
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||||
setup = runproto $ do
|
||||
net $ sendMessage (LOCKCONTENT key)
|
||||
checkSuccess
|
||||
cleanup True = runproto $ net $ sendMessage UNLOCKCONTENT
|
||||
cleanup False = return ()
|
||||
|
||||
remove :: Key -> Proto Bool
|
||||
remove key = do
|
||||
net $ sendMessage (REMOVE key)
|
||||
checkSuccess
|
||||
|
||||
get :: Key -> Proto Bool
|
||||
get key = receiveContent key (`GET` key)
|
||||
|
||||
put :: Key -> Proto Bool
|
||||
put key = do
|
||||
net $ sendMessage (PUT key)
|
||||
r <- net receiveMessage
|
||||
case r of
|
||||
PUT_FROM offset -> sendContent key offset
|
||||
ALREADY_HAVE -> return True
|
||||
_ -> do
|
||||
net $ sendMessage (ERROR "expected PUT_FROM")
|
||||
return False
|
||||
|
||||
-- | Serve the protocol.
|
||||
--
|
||||
-- Note that if the client sends an unexpected message, the server will
|
||||
-- respond with PTOTO_ERROR, and always continues processing messages.
|
||||
-- Since the protocol is not versioned, this is necessary to handle
|
||||
-- protocol changes robustly, since the client can detect when it's
|
||||
-- talking to a server that does not support some new feature, and fall
|
||||
-- back.
|
||||
--
|
||||
-- When the client sends ERROR to the server, the server gives up,
|
||||
-- since it's not clear what state the client is is, and so not possible to
|
||||
-- recover.
|
||||
serve :: UUID -> Proto ()
|
||||
serve myuuid = go Nothing
|
||||
where
|
||||
go autheduuid = do
|
||||
r <- net receiveMessage
|
||||
case r of
|
||||
AUTH theiruuid authtoken -> do
|
||||
ok <- local $ checkAuthToken theiruuid authtoken
|
||||
if ok
|
||||
then do
|
||||
net $ sendMessage (AUTH_SUCCESS myuuid)
|
||||
go (Just theiruuid)
|
||||
else do
|
||||
net $ sendMessage AUTH_FAILURE
|
||||
go autheduuid
|
||||
ERROR _ -> return ()
|
||||
_ -> do
|
||||
case autheduuid of
|
||||
Just theiruuid -> authed theiruuid r
|
||||
Nothing -> net $ sendMessage (ERROR "must AUTH first")
|
||||
go autheduuid
|
||||
|
||||
authed _theiruuid r = case r of
|
||||
LOCKCONTENT key -> local $ tryLockContent key $ \locked -> do
|
||||
sendSuccess locked
|
||||
when locked $ do
|
||||
r' <- net receiveMessage
|
||||
case r' of
|
||||
UNLOCKCONTENT -> return ()
|
||||
_ -> net $ sendMessage (ERROR "expected UNLOCKCONTENT")
|
||||
CHECKPRESENT key -> sendSuccess =<< local (checkContentPresent key)
|
||||
REMOVE key -> sendSuccess =<< local (removeKeyFile key)
|
||||
PUT key -> do
|
||||
have <- local $ checkContentPresent key
|
||||
if have
|
||||
then net $ sendMessage ALREADY_HAVE
|
||||
else do
|
||||
ok <- receiveContent key PUT_FROM
|
||||
when ok $
|
||||
local $ setPresent key myuuid
|
||||
-- setPresent not called because the peer may have
|
||||
-- requested the data but not permanatly stored it.
|
||||
GET offset key -> void $ sendContent key offset
|
||||
CONNECT service -> do
|
||||
exitcode <- net $ relayService service relayCallback
|
||||
net $ sendMessage (CONNECTDONE exitcode)
|
||||
_ -> net $ sendMessage (ERROR "unexpected command")
|
||||
|
||||
sendContent :: Key -> Offset -> Proto Bool
|
||||
sendContent key offset = do
|
||||
(len, content) <- readKeyFileLen key offset
|
||||
net $ sendMessage (DATA len)
|
||||
net $ sendBytes len content
|
||||
checkSuccess
|
||||
|
||||
receiveContent :: Key -> (Offset -> Message) -> Proto Bool
|
||||
receiveContent key mkmsg = do
|
||||
Len n <- local $ keyFileSize key
|
||||
let offset = Offset n
|
||||
net $ sendMessage (mkmsg offset)
|
||||
r <- net receiveMessage
|
||||
case r of
|
||||
DATA len -> do
|
||||
ok <- local . writeKeyFile key offset len
|
||||
=<< net (receiveBytes len)
|
||||
sendSuccess ok
|
||||
return ok
|
||||
_ -> do
|
||||
net $ sendMessage (ERROR "expected DATA")
|
||||
return False
|
||||
|
||||
checkSuccess :: Proto Bool
|
||||
checkSuccess = do
|
||||
ack <- net receiveMessage
|
||||
case ack of
|
||||
SUCCESS -> return True
|
||||
FAILURE -> return False
|
||||
_ -> do
|
||||
net $ sendMessage (ERROR "expected SUCCESS or FAILURE")
|
||||
return False
|
||||
|
||||
sendSuccess :: Bool -> Proto ()
|
||||
sendSuccess True = net $ sendMessage SUCCESS
|
||||
sendSuccess False = net $ sendMessage FAILURE
|
||||
|
||||
-- Reads key file from an offset. The Len should correspond to
|
||||
-- the length of the ByteString, but to avoid buffering the content
|
||||
-- in memory, is gotten using keyFileSize.
|
||||
readKeyFileLen :: Key -> Offset -> Proto (Len, L.ByteString)
|
||||
readKeyFileLen key (Offset offset) = do
|
||||
(Len totallen) <- local $ keyFileSize key
|
||||
let len = totallen - offset
|
||||
if len <= 0
|
||||
then return (Len 0, L.empty)
|
||||
else do
|
||||
content <- local $ readKeyFile key (Offset offset)
|
||||
return (Len len, content)
|
||||
|
||||
connect :: Service -> Handle -> Handle -> Proto ExitCode
|
||||
connect service hin hout = do
|
||||
net $ sendMessage (CONNECT service)
|
||||
net $ relay (RelayHandle hin) (relayCallback (RelayHandle hout))
|
||||
|
||||
relayCallback :: RelayHandle -> RelayData -> Net (Maybe ExitCode)
|
||||
relayCallback hout (RelayMessage (DATA len)) = do
|
||||
writeRelay hout =<< receiveBytes len
|
||||
return Nothing
|
||||
relayCallback _ (RelayMessage (CONNECTDONE exitcode)) =
|
||||
return (Just exitcode)
|
||||
relayCallback _ (RelayMessage _) = do
|
||||
sendMessage (ERROR "expected DATA or CONNECTDONE")
|
||||
return (Just (ExitFailure 1))
|
||||
relayCallback _ (RelayData b) = do
|
||||
let len = Len $ fromIntegral $ L.length b
|
||||
sendMessage (DATA len)
|
||||
sendBytes len b
|
||||
return Nothing
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue