5 files changed, 210 insertions, 99 deletions

diff --git a/src/Network/BitTorrent/Core/PeerAddr.hs b/src/Network/BitTorrent/Core/PeerAddr.hs
index ed2dc672..81754e5e 100644
--- a/src/Network/BitTorrent/Core/PeerAddr.hs
+++ b/src/Network/BitTorrent/Core/PeerAddr.hs
@@ -18,7 +18,6 @@ module Network.BitTorrent.Core.PeerAddr
          PeerAddr(..)
        , defaultPorts
        , peerSockAddr
-       , connectToPeer
        ) where
 
 import Control.Applicative
@@ -116,10 +115,3 @@ peerSockAddr = SockAddrInet <$> (g . peerPort) <*> (htonl . peerIP)
 
     g :: PortNumber -> PortNumber
     g = id
-
--- | 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
diff --git a/src/Network/BitTorrent/Exchange.hs b/src/Network/BitTorrent/Exchange.hs
index 57b2c81f..c1377449 100644
--- a/src/Network/BitTorrent/Exchange.hs
+++ b/src/Network/BitTorrent/Exchange.hs
@@ -84,7 +84,6 @@ import Control.Monad.Trans.Resource
 import Data.IORef
 import Data.Conduit as C
 import Data.Conduit.Cereal as S
---import Data.Conduit.Serialization.Binary as B
 import Data.Conduit.Network
 import Data.Serialize as S
 import Text.PrettyPrint as PP hiding (($$))
diff --git a/src/Network/BitTorrent/Exchange/Bus.hs b/src/Network/BitTorrent/Exchange/Bus.hs
deleted file mode 100644
index 7de91180..00000000
--- a/src/Network/BitTorrent/Exchange/Bus.hs
+++ /dev/null
@@ -1,66 +0,0 @@
-module Network.BitTorrent.Exchange.Bus ( ) where
-
-type PeerWire = ConduitM Message Message IO
-
-runPeerWire :: Socket -> PeerWire () -> IO ()
-runPeerWire sock action =
-  sourceSocket sock     $=
-    S.conduitGet S.get  $=
---    B.conduitDecode     $=
-      action            $=
-    S.conduitPut S.put  $$
---    B.conduitEncode     $$
-  sinkSocket sock
-
-awaitMessage :: P2P Message
-awaitMessage = P2P $ ReaderT $ const $ {-# SCC awaitMessage #-} go
-  where
-    go = await >>= maybe (monadThrow PeerDisconnected) return
-{-# INLINE awaitMessage #-}
-
-yieldMessage :: Message -> P2P ()
-yieldMessage msg = P2P $ ReaderT $ const $ {-# SCC yieldMessage #-} do
-  C.yield msg
-{-# INLINE yieldMessage #-}
-
--- TODO send vectored
-flushPending :: P2P ()
-flushPending = {-# SCC flushPending #-} do
-  session <- ask
-  queue   <- liftIO (getPending session)
-  mapM_ yieldMessage queue
-
-{-----------------------------------------------------------------------
-    P2P monad
------------------------------------------------------------------------}
-
-filterMeaninless :: P2P Message Message
-filterMeaninless = undefined
-
--- |
---   Exceptions:
---
---     * SessionException: is visible only within one peer
---     session. Use this exception to terminate P2P session, but not
---     the swarm session.
---
-newtype P2P a = P2P {
-    unP2P :: ReaderT PeerSession PeerWire a
-  } deriving ( Functor, Applicative, Monad
-             , MonadIO, MonadThrow, MonadActive
-             , MonadReader PeerSession
-             )
-
-instance MonadState SessionState P2P where
-  get    = asks sessionState >>= liftIO . readIORef
-  {-# INLINE get #-}
-  put !s = asks sessionState >>= \ref -> liftIO $ writeIORef ref s
-  {-# INLINE put #-}
-
-runP2P :: (Socket, PeerSession) -> P2P () -> IO ()
-runP2P (sock, ses) action =
-  handle isIOException $
-    runPeerWire sock (runReaderT (unP2P action) ses)
-  where
-    isIOException :: IOException -> IO ()
-    isIOException _ = return ()
diff --git a/src/Network/BitTorrent/Exchange/Session.hs b/src/Network/BitTorrent/Exchange/Session.hs
index ffc7816e..d2a9aaaf 100644
--- a/src/Network/BitTorrent/Exchange/Session.hs
+++ b/src/Network/BitTorrent/Exchange/Session.hs
@@ -22,6 +22,11 @@ import Network.BitTorrent.Exchange.Status
 
 type Extension = ()
 
+data ExchangeError
+  = InvalidPieceIx PieceIx
+  | InvalidBlock   BlockIx
+  | CorruptedPiece PieceIx
+
 -- | Peer session contain all data necessary for peer to peer
 -- communication.
 data ExchangeSession = ExchangeSession
@@ -69,30 +74,6 @@ $(makeLenses ''SessionState)
 --getSessionState :: PeerSession -> IO SessionState
 --getSessionState PeerSession {..} = readIORef sessionState
 
-{-----------------------------------------------------------------------
---  Exceptions
------------------------------------------------------------------------}
-
--- | Exceptions used to interrupt the current P2P session. This
--- exceptions will NOT affect other P2P sessions, DHT, peer <->
--- tracker, or any other session.
---
-data ExchangeFailure
-  = PeerDisconnected
-  | ProtocolError  Doc
-  | UnknownTorrent InfoHash
-    deriving (Show, Typeable)
-
-instance Exception ExchangeFailure
-
--- | Do nothing with exception, used with 'handle' or 'try'.
-isSessionException :: Monad m => ExchangeFailure -> m ()
-isSessionException _ = return ()
-
--- | The same as 'isSessionException' but output to stdout the catched
--- exception, for debugging purposes only.
-putSessionException :: ExchangeFailure -> IO ()
-putSessionException = print
 {-
 {-----------------------------------------------------------------------
 --  Broadcasting: Have, Cancel, Bitfield, SuggestPiece
diff --git a/src/Network/BitTorrent/Exchange/Wire.hs b/src/Network/BitTorrent/Exchange/Wire.hs
new file mode 100644
index 00000000..dd77a915
--- /dev/null
+++ b/src/Network/BitTorrent/Exchange/Wire.hs
@@ -0,0 +1,205 @@
+-- |
+--
+--   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