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{- P2P protocol, IO implementation
-
- Copyright 2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE RankNTypes, FlexibleContexts, BangPatterns, CPP #-}
module P2P.IO
( RunProto
, RunEnv(..)
, runNetProto
, runNet
) where
import P2P.Protocol
import Utility.Process
import Git
import Git.Command
import Utility.AuthToken
import Utility.SafeCommand
import Utility.SimpleProtocol
import Utility.Exception
import Control.Monad
import Control.Monad.Free
import Control.Monad.IO.Class
import System.Exit (ExitCode(..))
import System.IO
import Control.Concurrent
import Control.Concurrent.Async
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
-- Type of interpreters of the Proto free monad.
type RunProto m = forall a. (MonadIO m, MonadMask m) => Proto a -> m (Maybe a)
data RunEnv = RunEnv
{ runRepo :: Repo
, runCheckAuth :: (AuthToken -> Bool)
, runIhdl :: Handle
, runOhdl :: Handle
}
-- Purposefully incomplete interpreter of Proto.
--
-- This only runs Net actions. No Local actions will be run
-- (those need the Annex monad) -- if the interpreter reaches any,
-- it returns Nothing.
runNetProto :: RunEnv -> Proto a -> IO (Maybe a)
runNetProto runenv = go
where
go :: RunProto IO
go (Pure v) = pure (Just v)
go (Free (Net n)) = runNet runenv go n
go (Free (Local _)) = return Nothing
-- Interpreter of the Net part of Proto.
--
-- An interpreter of Proto has to be provided, to handle the rest of Proto
-- actions.
runNet :: (MonadIO m, MonadMask m) => RunEnv -> RunProto m -> NetF (Proto a) -> m (Maybe a)
runNet runenv runner f = case f of
SendMessage m next -> do
v <- liftIO $ tryNonAsync $ do
hPutStrLn (runOhdl runenv) (unwords (formatMessage m))
hFlush (runOhdl runenv)
case v of
Left _e -> return Nothing
Right () -> runner next
ReceiveMessage next -> do
v <- liftIO $ tryNonAsync $ hGetLine (runIhdl runenv)
case v of
Left _e -> return Nothing
Right l -> case parseMessage l of
Just m -> runner (next m)
Nothing -> runner $ do
let e = ERROR $ "protocol parse error: " ++ show l
net $ sendMessage e
next e
SendBytes len b next -> do
v <- liftIO $ tryNonAsync $ do
ok <- sendExactly len b (runOhdl runenv)
hFlush (runOhdl runenv)
return ok
case v of
Right True -> runner next
_ -> return Nothing
ReceiveBytes (Len n) next -> do
v <- liftIO $ tryNonAsync $ L.hGet (runIhdl runenv) (fromIntegral n)
case v of
Left _e -> return Nothing
Right b -> runner (next b)
CheckAuthToken _u t next -> do
let authed = runCheckAuth runenv t
runner (next authed)
Relay hin hout next -> do
v <- liftIO $ runRelay runnerio hin hout
case v of
Nothing -> return Nothing
Just exitcode -> runner (next exitcode)
RelayService service next -> do
v <- liftIO $ runRelayService runenv runnerio service
case v of
Nothing -> return Nothing
Just () -> runner next
where
-- This is only used for running Net actions when relaying,
-- so it's ok to use runNetProto, despite it not supporting
-- all Proto actions.
runnerio = runNetProto runenv
-- Send exactly the specified number of bytes or returns False.
--
-- The ByteString can be larger or smaller than the specified length.
-- For example, it can be lazily streaming from a file that gets
-- appended to, or truncated.
--
-- Must avoid sending too many bytes as it would confuse the other end.
-- This is easily dealt with by truncating it.
--
-- If too few bytes are sent, the only option is to give up on this
-- connection. False is returned to indicate this problem.
--
-- We can't check the length of the whole lazy bytestring without buffering
-- it in memory. Instead, process it one chunk at a time, and sum the length
-- of the chunks.
sendExactly :: Len -> L.ByteString -> Handle -> IO Bool
sendExactly (Len l) lb h = go 0 $ L.toChunks $ L.take (fromIntegral l) lb
where
go n [] = return (toInteger n == l)
go n (b:bs) = do
B.hPut h b
let !n' = n + B.length b
go n' bs
runRelay :: RunProto IO -> RelayHandle -> RelayHandle -> IO (Maybe ExitCode)
runRelay runner (RelayHandle hout) (RelayHandle hin) = bracket setup cleanup go
where
setup = do
v <- newEmptyMVar
void $ async $ relayFeeder runner v
void $ async $ relayReader v hout
return v
cleanup _ = do
hClose hin
hClose hout
go v = relayHelper runner v hin
runRelayService :: RunEnv -> RunProto IO -> Service -> IO (Maybe ())
runRelayService runenv runner service = bracket setup cleanup go
where
cmd = case service of
UploadPack -> "upload-pack"
ReceivePack -> "receive-pack"
serviceproc = gitCreateProcess
[ Param cmd
, File (repoPath (runRepo runenv))
] (runRepo runenv)
setup = do
(Just hin, Just hout, _, pid) <- createProcess serviceproc
{ std_out = CreatePipe
, std_in = CreatePipe
}
v <- newEmptyMVar
void $ async $ relayFeeder runner v
void $ async $ relayReader v hout
waiter <- async $ waitexit v pid
return (v, waiter, hin, hout, pid)
cleanup (_, waiter, hin, hout, pid) = do
hClose hin
hClose hout
cancel waiter
void $ waitForProcess pid
go (v, _, hin, _, _) = do
r <- relayHelper runner v hin
case r of
Nothing -> return Nothing
Just exitcode -> runner $ net $ relayToPeer (RelayDone exitcode)
waitexit v pid = putMVar v . RelayDone =<< waitForProcess pid
-- Processes RelayData as it is put into the MVar.
relayHelper :: RunProto IO -> MVar RelayData -> Handle -> IO (Maybe ExitCode)
relayHelper runner v hin = loop
where
loop = do
d <- takeMVar v
case d of
RelayFromPeer b -> do
L.hPut hin b
hFlush hin
loop
RelayToPeer b -> do
r <- runner $ net $ relayToPeer (RelayToPeer b)
case r of
Nothing -> return Nothing
Just () -> loop
RelayDone exitcode -> do
_ <- runner $ net $ relayToPeer (RelayDone exitcode)
return (Just exitcode)
-- Takes input from the peer, and puts it into the MVar for processing.
-- Repeats until the peer tells it it's done or hangs up.
relayFeeder :: RunProto IO -> MVar RelayData -> IO ()
relayFeeder runner v = loop
where
loop = do
mrd <- runner $ net relayFromPeer
case mrd of
Nothing -> putMVar v (RelayDone (ExitFailure 1))
Just rd -> do
putMVar v rd
case rd of
RelayDone _ -> return ()
_ -> loop
-- Reads input from the Handle and puts it into the MVar for relaying to
-- the peer. Continues until EOF on the Handle.
relayReader :: MVar RelayData -> Handle -> IO ()
relayReader v hout = loop
where
loop = do
bs <- getsome []
case bs of
[] -> return ()
_ -> do
putMVar v $ RelayToPeer (L.fromChunks bs)
loop
-- Waiit for the first available chunk. Then, without blocking,
-- try to get more chunks, in case a stream of chunks is being
-- written in close succession.
--
-- On Windows, hGetNonBlocking is broken, so avoid using it there.
getsome [] = do
b <- B.hGetSome hout chunk
if B.null b
then return []
#ifndef mingw32_HOST_OS
else getsome [b]
#else
else return [b]
#endif
getsome bs = do
b <- B.hGetNonBlocking hout chunk
if B.null b
then return (reverse bs)
else getsome (b:bs)
chunk = 65536
|