408 lines
13 KiB
Haskell
408 lines
13 KiB
Haskell
{- P2P protocol
|
|
-
|
|
- Copyright 2016 Joey Hess <id@joeyh.name>
|
|
-
|
|
- Licensed under the GNU GPL version 3 or higher.
|
|
-}
|
|
|
|
{-# LANGUAGE DeriveFunctor, TemplateHaskell, FlexibleContexts, RankNTypes #-}
|
|
|
|
module P2P.Protocol where
|
|
|
|
import qualified Utility.SimpleProtocol as Proto
|
|
import Types.Key
|
|
import Types.UUID
|
|
import Utility.AuthToken
|
|
import Utility.Applicative
|
|
import Utility.PartialPrelude
|
|
|
|
import Control.Monad
|
|
import Control.Monad.Free
|
|
import Control.Monad.Free.TH
|
|
import Control.Monad.Catch
|
|
import System.Exit (ExitCode(..))
|
|
import System.IO
|
|
import qualified Data.ByteString.Lazy as L
|
|
|
|
newtype Offset = Offset Integer
|
|
deriving (Show)
|
|
|
|
newtype Len = Len Integer
|
|
deriving (Show)
|
|
|
|
-- | Service as used by the connect message is gitremote-helpers(1)
|
|
data Service = UploadPack | ReceivePack
|
|
deriving (Show)
|
|
|
|
-- | Messages in the protocol. The peer that makes the connection
|
|
-- always initiates requests, and the other peer makes responses to them.
|
|
data Message
|
|
= AUTH UUID AuthToken -- uuid of the peer that is authenticating
|
|
| AUTH_SUCCESS UUID -- uuid of the remote peer
|
|
| AUTH_FAILURE
|
|
| CONNECT Service
|
|
| CONNECTDONE ExitCode
|
|
| CHECKPRESENT Key
|
|
| LOCKCONTENT Key
|
|
| UNLOCKCONTENT
|
|
| REMOVE Key
|
|
| GET Offset Key
|
|
| PUT Key
|
|
| PUT_FROM Offset
|
|
| ALREADY_HAVE
|
|
| SUCCESS
|
|
| FAILURE
|
|
| DATA Len -- followed by bytes of data
|
|
| ERROR String
|
|
deriving (Show)
|
|
|
|
instance Proto.Sendable Message where
|
|
formatMessage (AUTH uuid authtoken) = ["AUTH", Proto.serialize uuid, Proto.serialize authtoken]
|
|
formatMessage (AUTH_SUCCESS uuid) = ["AUTH-SUCCESS", Proto.serialize uuid]
|
|
formatMessage AUTH_FAILURE = ["AUTH-FAILURE"]
|
|
formatMessage (CONNECT service) = ["CONNECT", Proto.serialize service]
|
|
formatMessage (CONNECTDONE exitcode) = ["CONNECTDONE", Proto.serialize exitcode]
|
|
formatMessage (CHECKPRESENT key) = ["CHECKPRESENT", Proto.serialize key]
|
|
formatMessage (LOCKCONTENT key) = ["LOCKCONTENT", Proto.serialize key]
|
|
formatMessage UNLOCKCONTENT = ["UNLOCKCONTENT"]
|
|
formatMessage (REMOVE key) = ["REMOVE", Proto.serialize key]
|
|
formatMessage (GET offset key) = ["GET", Proto.serialize offset, Proto.serialize key]
|
|
formatMessage (PUT key) = ["PUT", Proto.serialize key]
|
|
formatMessage (PUT_FROM offset) = ["PUT-FROM", Proto.serialize offset]
|
|
formatMessage ALREADY_HAVE = ["ALREADY-HAVE"]
|
|
formatMessage SUCCESS = ["SUCCESS"]
|
|
formatMessage FAILURE = ["FAILURE"]
|
|
formatMessage (DATA len) = ["DATA", Proto.serialize len]
|
|
formatMessage (ERROR err) = ["ERROR", Proto.serialize err]
|
|
|
|
instance Proto.Receivable Message where
|
|
parseCommand "AUTH" = Proto.parse2 AUTH
|
|
parseCommand "AUTH-SUCCESS" = Proto.parse1 AUTH_SUCCESS
|
|
parseCommand "AUTH-FAILURE" = Proto.parse0 AUTH_FAILURE
|
|
parseCommand "CONNECT" = Proto.parse1 CONNECT
|
|
parseCommand "CONNECTDONE" = Proto.parse1 CONNECTDONE
|
|
parseCommand "CHECKPRESENT" = Proto.parse1 CHECKPRESENT
|
|
parseCommand "LOCKCONTENT" = Proto.parse1 LOCKCONTENT
|
|
parseCommand "UNLOCKCONTENT" = Proto.parse0 UNLOCKCONTENT
|
|
parseCommand "REMOVE" = Proto.parse1 REMOVE
|
|
parseCommand "GET" = Proto.parse2 GET
|
|
parseCommand "PUT" = Proto.parse1 PUT
|
|
parseCommand "PUT-FROM" = Proto.parse1 PUT_FROM
|
|
parseCommand "ALREADY-HAVE" = Proto.parse0 ALREADY_HAVE
|
|
parseCommand "SUCCESS" = Proto.parse0 SUCCESS
|
|
parseCommand "FAILURE" = Proto.parse0 FAILURE
|
|
parseCommand "DATA" = Proto.parse1 DATA
|
|
parseCommand "ERROR" = Proto.parse1 ERROR
|
|
parseCommand _ = Proto.parseFail
|
|
|
|
instance Proto.Serializable Offset where
|
|
serialize (Offset n) = show n
|
|
deserialize = Offset <$$> readish
|
|
|
|
instance Proto.Serializable Len where
|
|
serialize (Len n) = show n
|
|
deserialize = Len <$$> readish
|
|
|
|
instance Proto.Serializable Service where
|
|
serialize UploadPack = "git-upload-pack"
|
|
serialize ReceivePack = "git-receive-pack"
|
|
deserialize "git-upload-pack" = Just UploadPack
|
|
deserialize "git-receive-pack" = Just ReceivePack
|
|
deserialize _ = Nothing
|
|
|
|
-- | Free monad for the protocol, combining net communication,
|
|
-- and local actions.
|
|
data ProtoF c = Net (NetF c) | Local (LocalF c)
|
|
deriving (Functor)
|
|
|
|
type Proto = Free ProtoF
|
|
|
|
net :: Net a -> Proto a
|
|
net = hoistFree Net
|
|
|
|
local :: Local a -> Proto a
|
|
local = hoistFree Local
|
|
|
|
data NetF c
|
|
= SendMessage Message c
|
|
| ReceiveMessage (Message -> c)
|
|
| SendBytes Len L.ByteString c
|
|
-- ^ Sends exactly Len bytes of data. (Any more or less will
|
|
-- confuse the receiver.)
|
|
| ReceiveBytes Len (L.ByteString -> c)
|
|
-- ^ Lazily reads bytes from peer. Stops once Len are read,
|
|
-- or if connection is lost, and in either case returns the bytes
|
|
-- that were read. This allows resuming interrupted transfers.
|
|
| CheckAuthToken UUID AuthToken (Bool -> c)
|
|
| RelayService Service c
|
|
-- ^ Runs a service, relays its output to the peer, and data
|
|
-- from the peer to it.
|
|
| Relay RelayHandle RelayHandle (ExitCode -> c)
|
|
-- ^ Reads from the first RelayHandle, and sends the data to a
|
|
-- peer, while at the same time accepting input from the peer
|
|
-- which is sent the the second RelayHandle. Continues until
|
|
-- the peer sends an ExitCode.
|
|
deriving (Functor)
|
|
|
|
type Net = Free NetF
|
|
|
|
newtype RelayHandle = RelayHandle Handle
|
|
|
|
data LocalF c
|
|
= TmpContentSize Key (Len -> c)
|
|
-- ^ Gets size of the temp file where received content may have
|
|
-- been stored. If not present, returns 0.
|
|
| ContentSize Key (Maybe Len -> c)
|
|
-- ^ Gets size of the content of a key, when the full content is
|
|
-- present.
|
|
| ReadContent Key Offset (L.ByteString -> c)
|
|
-- ^ Lazily reads the content of a key. Note that the content
|
|
-- may change while it's being sent.
|
|
| WriteContent Key Offset Len L.ByteString (Bool -> c)
|
|
-- ^ Writes content to temp file starting at an offset.
|
|
-- Once the whole content of the key has been stored, moves the
|
|
-- temp file into place and returns True.
|
|
--
|
|
-- Note: The ByteString may not contain the entire remaining content
|
|
-- of the key. Only once the temp file size == Len has the whole
|
|
-- content been transferred.
|
|
| SetPresent Key UUID c
|
|
| CheckContentPresent Key (Bool -> c)
|
|
-- ^ Checks if the whole content of the key is locally present.
|
|
| RemoveContent Key (Bool -> c)
|
|
-- ^ If the content is not present, still succeeds.
|
|
-- May fail if not enough copies to safely drop, etc.
|
|
| TryLockContent Key (Bool -> Proto ()) c
|
|
-- ^ Try to lock the content of a key, preventing it
|
|
-- from being deleted, while running the provided protocol
|
|
-- action. If unable to lock the content, runs the protocol action
|
|
-- with False.
|
|
deriving (Functor)
|
|
|
|
type Local = Free LocalF
|
|
|
|
-- Generate sendMessage etc functions for all free monad constructors.
|
|
$(makeFree ''NetF)
|
|
$(makeFree ''LocalF)
|
|
|
|
auth :: UUID -> AuthToken -> Proto (Maybe UUID)
|
|
auth myuuid t = do
|
|
net $ sendMessage (AUTH myuuid t)
|
|
r <- net receiveMessage
|
|
case r of
|
|
AUTH_SUCCESS theiruuid -> return $ Just theiruuid
|
|
AUTH_FAILURE -> return Nothing
|
|
_ -> do
|
|
net $ sendMessage (ERROR "auth failed")
|
|
return Nothing
|
|
|
|
checkPresent :: Key -> Proto Bool
|
|
checkPresent key = do
|
|
net $ sendMessage (CHECKPRESENT key)
|
|
checkSuccess
|
|
|
|
{- Locks content to prevent it from being dropped, while running an action.
|
|
-
|
|
- Note that this only guarantees that the content is locked as long as the
|
|
- connection to the peer remains up. If the connection is unexpectededly
|
|
- dropped, the peer will then unlock the content.
|
|
-}
|
|
lockContentWhile
|
|
:: MonadMask m
|
|
=> (forall r. Proto r -> m r)
|
|
-> Key
|
|
-> (Bool -> m ())
|
|
-> m ()
|
|
lockContentWhile runproto key a = bracket setup cleanup a
|
|
where
|
|
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
|
|
|
|
data ServerHandler a
|
|
= ServerGot a
|
|
| ServerContinue
|
|
| ServerUnexpected
|
|
|
|
-- Server loop, getting messages from the client and handling them
|
|
serverLoop :: (Message -> Proto (ServerHandler a)) -> Proto (Maybe a)
|
|
serverLoop a = do
|
|
cmd <- net receiveMessage
|
|
case cmd of
|
|
-- When the client sends ERROR to the server, the server
|
|
-- gives up, since it's not clear what state the client
|
|
-- is in, and so not possible to recover.
|
|
ERROR _ -> return Nothing
|
|
_ -> do
|
|
v <- a cmd
|
|
case v of
|
|
ServerGot r -> return (Just r)
|
|
ServerContinue -> serverLoop a
|
|
-- If the client sends an unexpected message,
|
|
-- the server will respond with 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.
|
|
ServerUnexpected -> do
|
|
net $ sendMessage (ERROR "unexpected command")
|
|
serverLoop a
|
|
|
|
-- | Serve the protocol, with an unauthenticated peer. Once the peer
|
|
-- successfully authenticates, returns their UUID.
|
|
serveAuth :: UUID -> Proto (Maybe UUID)
|
|
serveAuth myuuid = serverLoop handler
|
|
where
|
|
handler (AUTH theiruuid authtoken) = do
|
|
ok <- net $ checkAuthToken theiruuid authtoken
|
|
if ok
|
|
then do
|
|
net $ sendMessage (AUTH_SUCCESS myuuid)
|
|
return (ServerGot theiruuid)
|
|
else do
|
|
net $ sendMessage AUTH_FAILURE
|
|
return ServerContinue
|
|
handler _ = return ServerUnexpected
|
|
|
|
-- | Serve the protocol, with a peer that has authenticated.
|
|
serveAuthed :: UUID -> Proto ()
|
|
serveAuthed myuuid = void $ serverLoop handler
|
|
where
|
|
handler (LOCKCONTENT key) = do
|
|
local $ tryLockContent key $ \locked -> do
|
|
sendSuccess locked
|
|
when locked $ do
|
|
r' <- net receiveMessage
|
|
case r' of
|
|
UNLOCKCONTENT -> return ()
|
|
_ -> net $ sendMessage (ERROR "expected UNLOCKCONTENT")
|
|
return ServerContinue
|
|
handler (CHECKPRESENT key) = do
|
|
sendSuccess =<< local (checkContentPresent key)
|
|
return ServerContinue
|
|
handler (REMOVE key) = do
|
|
sendSuccess =<< local (removeContent key)
|
|
return ServerContinue
|
|
handler (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
|
|
return ServerContinue
|
|
handler (GET offset key) = do
|
|
void $ sendContent key offset
|
|
-- setPresent not called because the peer may have
|
|
-- requested the data but not permanently stored it.
|
|
return ServerContinue
|
|
handler (CONNECT service) = do
|
|
net $ relayService service
|
|
return ServerContinue
|
|
handler _ = return ServerUnexpected
|
|
|
|
sendContent :: Key -> Offset -> Proto Bool
|
|
sendContent key offset = do
|
|
(len, content) <- readContentLen key offset
|
|
net $ sendMessage (DATA len)
|
|
net $ sendBytes len content
|
|
checkSuccess
|
|
|
|
receiveContent :: Key -> (Offset -> Message) -> Proto Bool
|
|
receiveContent key mkmsg = do
|
|
Len n <- local $ tmpContentSize key
|
|
let offset = Offset n
|
|
net $ sendMessage (mkmsg offset)
|
|
r <- net receiveMessage
|
|
case r of
|
|
DATA len -> do
|
|
ok <- local . writeContent 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 content from an offset. The Len should correspond to
|
|
-- the length of the ByteString, but to avoid buffering the content
|
|
-- in memory, is gotten using contentSize.
|
|
readContentLen :: Key -> Offset -> Proto (Len, L.ByteString)
|
|
readContentLen key (Offset offset) = go =<< local (contentSize key)
|
|
where
|
|
go Nothing = return (Len 0, L.empty)
|
|
go (Just (Len totallen)) = do
|
|
let len = totallen - offset
|
|
if len <= 0
|
|
then return (Len 0, L.empty)
|
|
else do
|
|
content <- local $ readContent 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) (RelayHandle hout)
|
|
|
|
data RelayData
|
|
= RelayToPeer L.ByteString
|
|
| RelayFromPeer L.ByteString
|
|
| RelayDone ExitCode
|
|
deriving (Show)
|
|
|
|
relayFromPeer :: Net RelayData
|
|
relayFromPeer = do
|
|
r <- receiveMessage
|
|
case r of
|
|
CONNECTDONE exitcode -> return $ RelayDone exitcode
|
|
DATA len -> RelayFromPeer <$> receiveBytes len
|
|
_ -> do
|
|
sendMessage $ ERROR "expected DATA or CONNECTDONE"
|
|
return $ RelayDone $ ExitFailure 1
|
|
|
|
relayToPeer :: RelayData -> Net ()
|
|
relayToPeer (RelayDone exitcode) = sendMessage (CONNECTDONE exitcode)
|
|
relayToPeer (RelayToPeer b) = do
|
|
let len = Len $ fromIntegral $ L.length b
|
|
sendMessage (DATA len)
|
|
sendBytes len b
|
|
relayToPeer (RelayFromPeer _) = return ()
|