SSH server library, fork of Hackage one but hoping to get patches upstream
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Tags
TODO
Channel.hs
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{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-}
module Network.SSH.Internal.Channel
( ChannelT ()
, runChannelT
, getChannelState
, getChannelStateS
, modifyChannelState
, askAuthDetails
, AuthDetails (..)
, ChannelState (..)
, ChannelMessage (..)
, ChannelConfig (..)
, ChannelRequest (..)
, Process (..)
, defaultChannelConfig
, newChannel
, chanLoop
, channelError
, channelMessage
, channelFail
, channelSuccess
, channelDone
, sendChunks
, redirectHandle
, spawnProcess
, spawnProcessWait
)
where
import Control.Concurrent (ThreadId, Chan, newChan, readChan, writeChan, forkIO, killThread)
import Control.Concurrent.MVar (MVar, newEmptyMVar, readMVar, putMVar)
import Control.Exception (catch, IOException, finally)
import Control.Monad (when, void)
import Control.Monad.Base
import Control.Monad.Fail
import Control.Monad.Fix (MonadFix)
import Control.Monad.IO.Class
import Control.Monad.IO.Unlift
import Control.Monad.Trans.Class
import Control.Monad.Trans.Control
import Data.Binary.Put (Put)
import Data.IORef
import Data.Word (Word32)
import System.Exit (ExitCode(..))
import System.IO (Handle, hFlush, hClose, hIsEOF, hGetChar, hReady, hSetBinaryMode)
import System.Process (ProcessHandle, runInteractiveCommand,
terminateProcess, waitForProcess,)
import qualified Data.ByteString.Lazy as LBS
import qualified Control.Monad.Trans.Reader as R
import Network.SSH.Internal.Debug (dump)
import Network.SSH.Internal.NetPut
import Network.SSH.Internal.Sender
import Network.SSH.Internal.Util (io)
newtype ChannelT i m a = ChannelT
{ unChannelT :: R.ReaderT (IORef (ChannelState m i)) m a
}
deriving (Functor, Applicative, Monad, MonadFail, MonadFix, MonadIO)
instance MonadUnliftIO m => MonadUnliftIO (ChannelT i m) where
withRunInIO = wrappedWithRunInIO ChannelT unChannelT
instance MonadBase b m => MonadBase b (ChannelT i m) where
liftBase = ChannelT . liftBase
instance MonadBaseControl b m => MonadBaseControl b (ChannelT i m) where
type StM (ChannelT i m) a = StM (R.ReaderT (IORef (ChannelState m i)) m) a
liftBaseWith f = ChannelT $ liftBaseWith $ \ g -> f $ g . unChannelT
restoreM = ChannelT . restoreM
instance MonadTrans (ChannelT i) where
lift = ChannelT . lift
runChannelT :: MonadIO m => ChannelT i m a -> ChannelState m i -> m a
runChannelT a s = do
ref <- liftIO $ newIORef s
R.runReaderT (unChannelT a) ref
getChannelState :: MonadIO m => ChannelT i m (ChannelState m i)
getChannelState = ChannelT R.ask >>= liftIO . readIORef
getChannelStateS :: MonadIO m => (ChannelState m i -> a) -> ChannelT i m a
getChannelStateS f = do
ref <- ChannelT $ R.ask
liftIO $ f <$> readIORef ref
modifyChannelState
:: MonadIO m
=> (ChannelState m i -> ChannelState m i)
-> ChannelT i m ()
modifyChannelState f = do
ref <- ChannelT R.ask
liftIO $ modifyIORef' ref f
askAuthDetails :: MonadIO m => ChannelT i m (AuthDetails i)
askAuthDetails = getChannelStateS csAuth
data AuthDetails i = AuthDetails
{ authUser :: String
, authId :: i
}
data ChannelState m i =
ChannelState
{ csConfig :: ChannelConfig m i
, csID :: Word32
, csTheirID :: Word32
, csSend :: SenderMessage -> IO ()
, csDataReceived :: Word32
, csMaxPacket :: Word32
, csWindowSize :: Word32
, csTheirWindowSize :: Word32
, csAuth :: AuthDetails i
, csProcess :: Maybe Process
, csRedirector :: Maybe ThreadId
}
data ChannelMessage
= Request Bool ChannelRequest
| Data LBS.ByteString
| EOF
| Interrupt
deriving Show
data ChannelConfig m i =
ChannelConfig
{ ccRequestHandler :: Bool -> ChannelRequest -> ChannelT i m ()
, ccRunBaseMonad :: m () -> IO ()
}
data ChannelRequest
= Shell
| Execute String
| Subsystem String
| X11Forwarding
| Environment String String
| PseudoTerminal String Word32 Word32 Word32 Word32 String
| WindowChange Word32 Word32 Word32 Word32
| Signal String
| ExitStatus Word32
| ExitSignal String Bool String String
| FlowControl Bool
| Unknown String
deriving Show
data Process =
Process
{ pHandle :: ProcessHandle
, pIn :: Handle
, pOut :: Handle
, pError :: Handle
}
instance MonadIO m => Sender (ChannelT i m) where
send m = getChannelStateS csSend >>= io . ($ m)
defaultChannelConfig :: ChannelConfig IO i
defaultChannelConfig =
ChannelConfig
{ ccRequestHandler = \wr req ->
case req of
Execute cmd -> do
spawnProcess (runInteractiveCommand cmd)
when wr channelSuccess
_ -> do
channelError "accepting 'exec' requests only"
when wr channelFail
, ccRunBaseMonad = id
}
newChannel
:: MonadIO m
=> ChannelConfig m i
-> (SenderMessage -> IO ())
-> Word32
-> Word32
-> Word32
-> Word32
-> AuthDetails i
-> IO (Chan ChannelMessage)
newChannel config csend us them winSize maxPacket auth = do
chan <- newChan
dump ("new channel", winSize, maxPacket)
let chanState = ChannelState
{ csConfig = config
, csID = us
, csTheirID = them
, csSend = csend
, csDataReceived = 0
, csMaxPacket = maxPacket
, csWindowSize = 32768 * 64
, csTheirWindowSize = winSize
, csAuth = auth
, csProcess = Nothing
, csRedirector = Nothing
}
forkIO $ ccRunBaseMonad config $ flip runChannelT chanState $ do
sendPacket $ do
byte 91
long them
long us
long (32768 * 64)
long 32768
chanLoop chan
return chan
chanLoop :: MonadIO m => Chan ChannelMessage -> ChannelT i m ()
chanLoop c = do
msg <- io (readChan c)
dump ("got channel message", msg)
chanid <- getChannelStateS csID
case msg of
Request wr cr -> do
handler <- getChannelStateS (ccRequestHandler . csConfig)
handler wr cr
chanLoop c
Data datum -> do
modifyChannelState $ \cs -> cs
{ csDataReceived =
csDataReceived cs + fromIntegral (LBS.length datum)
}
-- Adjust window size if needed
rcvd <- getChannelStateS csDataReceived
maxp <- getChannelStateS csMaxPacket
winSize <- getChannelStateS csTheirWindowSize
when (rcvd + (maxp * 4) >= winSize && winSize + (maxp * 4) <= 2^(32 :: Integer) - 1) $ do
modifyChannelState $ \cs -> cs { csTheirWindowSize = winSize + (maxp * 4) }
sendPacket $ do
byte 93
long chanid
long (maxp * 4)
-- Direct input to process's stdin
cproc <- getChannelStateS csProcess
case cproc of
Nothing -> dump ("got unhandled data", chanid)
Just (Process _ pin _ _) -> do
dump ("redirecting data", chanid, LBS.length datum)
io $ LBS.hPut pin datum
io $ hFlush pin
chanLoop c
EOF -> do
modifyChannelState $ \cs -> cs { csDataReceived = 0 }
-- Close process's stdin to indicate EOF
cproc <- getChannelStateS csProcess
case cproc of
Nothing -> dump ("got unhandled eof")
Just (Process _ pin _ _) -> do
dump ("redirecting eof", chanid)
io $ hClose pin
chanLoop c
Interrupt -> do
-- shut down the i/o redirecting process
redir <- getChannelStateS csRedirector
case redir of
Nothing -> return ()
Just tid -> io (killThread tid)
cproc <- getChannelStateS csProcess
case cproc of
Nothing -> return ()
Just (Process phdl pin _ _) -> do
-- NOTE: this doesn't necessarily guarantee termination
-- see System.Process docs
-- nb closing stdin seems necessary, or process won't die
io (hClose pin >> terminateProcess phdl)
channelError :: MonadIO m => String -> ChannelT i m ()
channelError msg = do
target <- getChannelStateS csTheirID
sendPacket $ do
byte 95
long target
long 1
string (msg ++ "\r\n")
channelMessage :: MonadIO m => String -> ChannelT i m ()
channelMessage msg = do
target <- getChannelStateS csTheirID
sendPacket $ do
byte 94
long target
string (msg ++ "\r\n")
channelFail :: MonadIO m => ChannelT i m ()
channelFail = do
target <- getChannelStateS csTheirID
sendPacket $ do
byte 100
long target
channelSuccess :: MonadIO m => ChannelT i m ()
channelSuccess = do
target <- getChannelStateS csTheirID
sendPacket $ do
byte 99
long target
channelDone :: MonadIO m => ChannelT i m ()
channelDone = do
target <- getChannelStateS csTheirID
sendPacket (byte 96 >> long target) -- eof
sendPacket (byte 97 >> long target) -- close
sendChunks
:: (MonadIO m, Integral a) => a -> Put -> String -> ChannelT i m ()
sendChunks _ _ "" = return ()
sendChunks n p s = do
sendPacket (p >> string chunk)
sendChunks n p rest
where
(chunk, rest) = splitAt (fromIntegral n - packetLength p) s
redirectHandle :: MonadIO m => Chan () -> Put -> Handle -> ChannelT i m ()
redirectHandle f d h = do
s <- getChannelState
let runBase = ccRunBaseMonad $ csConfig s
r <- io . forkIO . runBase . runChannelT redirectLoop $ s
modifyChannelState $ \cs -> cs { csRedirector = Just r }
where
redirectLoop = do
maxLen <- getChannelStateS csMaxPacket
dump "reading..."
l <- io $ getAvailable
dump ("read data from handle", l)
if not (null l)
then sendChunks maxLen d l
else return ()
done <- io $ hIsEOF h
dump ("eof handle?", done)
if done
then io $ writeChan f ()
else redirectLoop
getAvailable :: IO String
getAvailable = do
ready <- hReady h `Control.Exception.catch` (const (return False) :: IOException -> IO Bool)
if not ready
then return ""
else do
c <- hGetChar h
cs <- getAvailable
return (c:cs)
spawnProcess
:: MonadIO m
=> IO (Handle, Handle, Handle, ProcessHandle)
-> ChannelT i m ()
spawnProcess cmd = void $ spawnProcess' cmd
spawnProcessWait
:: MonadIO m
=> IO (Handle, Handle, Handle, ProcessHandle)
-> ChannelT i m ()
spawnProcessWait cmd = do
mvar <- spawnProcess' cmd
io $ readMVar mvar
spawnProcess'
:: MonadIO m
=> IO (Handle, Handle, Handle, ProcessHandle)
-> ChannelT i m (MVar ())
spawnProcess' cmd = do
target <- getChannelStateS csTheirID
(pin, pout, perr, phdl) <- io cmd
modifyChannelState $
\s -> s { csProcess = Just $ Process phdl pin pout perr }
dump ("command spawned")
-- redirect stdout and stderr, using a channel to signal completion
done <- io newChan
io $ hSetBinaryMode pout True
io $ hSetBinaryMode perr True
redirectHandle done (byte 94 >> long target) pout
redirectHandle done (byte 95 >> long target >> long 1) perr
s <- getChannelState
-- spawn a thread to wait for the process to terminate
mvar <- io newEmptyMVar
io . forkIO $ flip finally (putMVar mvar ()) $ do
-- wait until both are done
readChan done
readChan done
dump "done reading output! waiting for process..."
exit <- io $ waitForProcess phdl
dump ("process exited", exit)
ccRunBaseMonad (csConfig s) $ flip runChannelT s $ do
sendPacket $ do
byte 98
long target
string "exit-status"
byte 0
long (statusCode exit)
channelDone
return mvar
where
statusCode ExitSuccess = 0
statusCode (ExitFailure n) = fromIntegral n
|