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|
-- |
--
-- Message flow
-- Duplex channell
-- This module control /integrity/ of data send and received.
--
{-# LANGUAGE DeriveDataTypeable #-}
module Network.BitTorrent.Exchange.Wire
( -- * Exception
ProtocolError (..)
, WireFailure (..)
, isWireFailure
-- * Wire
, Connection (..)
, Wire
, runWire
, connectWire
, acceptWire
) where
import Control.Exception
import Control.Monad.Reader
import Data.ByteString as BS
import Data.Conduit
import Data.Conduit.Cereal as S
import Data.Conduit.Network
import Data.Default
import Data.Maybe
import Data.Monoid
import Data.Serialize as S
import Data.Typeable
import Network
import Network.Socket
import Network.Socket.ByteString as BS
import Text.PrettyPrint as PP hiding (($$), (<>))
import Text.PrettyPrint.Class
import Data.Torrent.InfoHash
import Network.BitTorrent.Core.PeerId
import Network.BitTorrent.Core.PeerAddr
import Network.BitTorrent.Exchange.Message
{-----------------------------------------------------------------------
-- Exceptions
-----------------------------------------------------------------------}
data ChannelSide
= ThisPeer
| RemotePeer
deriving (Show, Eq, Enum)
-- | Errors occur when a remote peer violates protocol specification.
data ProtocolError
= UnexpectedTopic InfoHash -- ^ peer replied with unexpected infohash.
| UnexpectedPeerId PeerId -- ^ peer replied with unexpected peer id.
| UnknownTopic InfoHash -- ^ peer requested unknown torrent.
| InvalidMessage
{ violentSender :: ChannelSide -- ^ endpoint sent invalid message
, extensionRequired :: Extension -- ^
}
deriving Show
instance Pretty ProtocolError where
pretty = PP.text . show
-- | Exceptions used to interrupt the current P2P session.
data WireFailure
= PeerDisconnected -- ^ A peer not responding.
| DisconnectPeer -- ^
| ProtocolError ProtocolError
deriving (Show, Typeable)
instance Exception WireFailure
instance Pretty WireFailure where
pretty = PP.text . show
-- | Do nothing with exception, used with 'handle' or 'try'.
isWireFailure :: Monad m => WireFailure -> m ()
isWireFailure _ = return ()
{-----------------------------------------------------------------------
-- Connection
-----------------------------------------------------------------------}
data Connection = Connection
{ connCaps :: !Caps
, connExtCaps :: !ExtendedCaps -- TODO caps can be enabled during communication
, connTopic :: !InfoHash
, connRemotePeerId :: !PeerId
, connThisPeerId :: !PeerId
} deriving Show
instance Pretty Connection where
pretty Connection {..} = "Connection"
isAllowed :: Connection -> Message -> Bool
isAllowed Connection {..} msg
| Just ext <- requires msg = allowed connCaps ext
| otherwise = True
{-----------------------------------------------------------------------
-- Hanshaking
-----------------------------------------------------------------------}
-- | TODO remove socket stuff to corresponding module
sendHandshake :: Socket -> Handshake -> IO ()
sendHandshake sock hs = sendAll sock (S.encode hs)
recvHandshake :: Socket -> IO Handshake
recvHandshake sock = do
header <- BS.recv sock 1
unless (BS.length header == 1) $
throw $ userError "Unable to receive handshake header."
let protocolLen = BS.head header
let restLen = handshakeSize protocolLen - 1
body <- BS.recv sock restLen
let resp = BS.cons protocolLen body
either (throwIO . userError) return $ S.decode resp
-- | Handshaking with a peer specified by the second argument.
--
-- It's important to send handshake first because /accepting/ peer
-- do not know handshake topic and will wait until /connecting/ peer
-- will send handshake.
--
initiateHandshake :: Socket -> Handshake -> IO Handshake
initiateHandshake sock hs = do
sendHandshake sock hs
recvHandshake sock
-- | Tries to connect to peer using reasonable default parameters.
connectToPeer :: PeerAddr -> IO Socket
connectToPeer p = do
sock <- socket AF_INET Stream Network.Socket.defaultProtocol
connect sock (peerSockAddr p)
return sock
{-----------------------------------------------------------------------
-- Wire
-----------------------------------------------------------------------}
type Wire = ConduitM Message Message (ReaderT Connection IO)
validate :: Wire ()
validate = do
mmsg <- await
case mmsg of
Nothing -> return ()
Just msg -> do
valid <- lift $ asks (`isAllowed` msg)
if valid then yield msg else error "TODO"
runWire :: Wire () -> Socket -> Connection -> IO ()
runWire action sock = runReaderT $
sourceSocket sock $=
S.conduitGet S.get $=
action $=
S.conduitPut S.put $$
sinkSocket sock
sendMessage :: PeerMessage msg => msg -> Wire ()
sendMessage msg = do
ecaps <- lift $ asks connExtCaps
yield $ envelop ecaps msg
recvMessage :: Wire Message
recvMessage = undefined
extendedHandshake :: Wire ()
extendedHandshake = undefined
connectWire :: Handshake -> PeerAddr -> ExtendedCaps -> Wire () -> IO ()
connectWire hs addr caps wire =
bracket (connectToPeer addr) close $ \ sock -> do
hs' <- initiateHandshake sock hs
unless (hsInfoHash hs == hsInfoHash hs') $ do
throwIO $ ProtocolError $ UnexpectedTopic (hsInfoHash hs')
unless (hsPeerId hs' == fromMaybe (hsPeerId hs') (peerID addr)) $ do
throwIO $ ProtocolError $ UnexpectedPeerId (hsPeerId hs')
let caps = hsReserved hs <> hsReserved hs'
if allowed caps ExtExtended
then return () else return ()
runWire wire sock $ Connection
{ connCaps = caps
, connExtCaps = def
, connTopic = hsInfoHash hs
, connRemotePeerId = hsPeerId hs'
, connThisPeerId = hsPeerId hs
}
acceptWire :: Wire () -> Socket -> IO ()
acceptWire = undefined
|
