1 files changed, 138 insertions, 0 deletions

diff --git a/src/Network/Tox/Session.hs b/src/Network/Tox/Session.hs
new file mode 100644
index 00000000..a52e9478
--- /dev/null
+++ b/src/Network/Tox/Session.hs
@@ -0,0 +1,138 @@
+{-# LANGUAGE TupleSections #-}
+module Network.Tox.Session where
+
+import Control.Concurrent.STM
+import Control.Monad
+import Data.Functor.Identity
+import Data.Word
+import Network.Socket
+
+import Crypto.Tox
+import Data.PacketBuffer            (PacketInboundEvent (..))
+import Data.Tox.Message
+import Network.Lossless
+import Network.QueryResponse
+import Network.SessionTransports
+import Network.Tox.Crypto.Transport
+import Network.Tox.DHT.Transport    (Cookie)
+import Network.Tox.Handshake
+
+type SessionKey = SecretKey
+
+data SessionParams = SessionParams
+    { spCrypto           :: TransportCrypto
+    , spSessions         :: Sessions (CryptoPacket Encrypted)
+    , spGetSentHandshake :: SecretKey -> SockAddr
+                                      -> Cookie Identity
+                                      -> Cookie Encrypted
+                                      -> IO (Maybe (SessionKey, HandshakeData))
+    , spOnNewSession     :: Session -> IO ()
+    }
+
+data Session = Session
+    { sOurKey            :: SecretKey
+    , sTheirAddr         :: SockAddr
+    , sSentHandshake     :: HandshakeData
+    , sReceivedHandshake :: Handshake Identity
+    , sResendPackets     :: [Word32] -> IO ()
+      -- ^ If they request that we re-send certain packets, this method is how
+      -- that is accomplished.
+    , sMissingInbound    :: IO ([Word32],Word32)
+      -- ^ This list of sequence numbers should be periodically polled and if
+      -- it is not empty, we should request they re-send these packets.  For
+      -- convenience, a lower bound for the numbers in the list is also
+      -- returned.  Suggested polling interval: a few seconds.
+    , sTransport         :: Transport String () CryptoMessage
+    }
+
+handshakeH :: SessionParams
+              -> SockAddr
+              -> Handshake Encrypted
+              -> IO (Maybe a)
+handshakeH sp saddr handshake = do
+    decryptHandshake (spCrypto sp) handshake
+        >>= either (\err -> return ())
+                   (uncurry $ plainHandshakeH sp saddr)
+    return Nothing
+
+
+plainHandshakeH :: SessionParams
+                   -> SockAddr
+                   -> SecretKey
+                   -> Handshake Identity
+                   -> IO ()
+plainHandshakeH sp saddr skey handshake = do
+    let hd = runIdentity $ handshakeData handshake
+    sent <- spGetSentHandshake sp skey saddr (handshakeCookie handshake) (otherCookie hd)
+    forM_ sent $ \(hd_skey,hd_sent) -> do
+    sk <- SessionKeys (spCrypto sp)
+                      hd_skey
+                      (sessionKey hd)
+                      <$> atomically (newTVar $ baseNonce hd)
+                      <*> atomically (newTVar $ baseNonce hd_sent)
+    m <- newSession (spSessions sp) (\() p -> return p) (decryptPacket sk) saddr
+    forM_ m $ \t -> do
+        (t2,resend,getMissing)
+            <- lossless (\cp a -> return $ fmap (,a) $ checkLossless $ runIdentity $ pktData cp)
+                        (\seqno p _ -> encryptPacket sk $ bookKeeping seqno p)
+                        ()
+                        t
+        let _ = t :: TransportA String () (CryptoPacket Identity) (CryptoPacket Encrypted)
+            _ = t2 :: Transport String () CryptoMessage
+        spOnNewSession sp Session
+            { sOurKey            = skey
+            , sTheirAddr         = saddr
+            , sSentHandshake     = hd_sent
+            , sReceivedHandshake = handshake
+            , sResendPackets     = resend
+            , sMissingInbound    = getMissing
+            , sTransport         = t2
+            }
+    return ()
+
+decryptPacket :: SessionKeys -> SockAddr -> CryptoPacket Encrypted -> IO (Maybe (CryptoPacket Identity, ()))
+decryptPacket sk saddr (CryptoPacket n16 ciphered) = do
+    (n,δ) <- atomically $ do
+        n <- readTVar (skNonceIncoming sk)
+        let δ = n16 - nonce24ToWord16 n
+        return ( n `addtoNonce24` fromIntegral δ, δ )
+    secret <- lookupSharedSecret (skCrypto sk) (skMe sk) (skThem sk) n
+    case decodePlain =<< decrypt secret ciphered of
+        Left e  -> return Nothing
+        Right x -> do
+            when ( δ  > 43690 )
+                $ atomically $ writeTVar (skNonceIncoming sk) (n `addtoNonce24` 21845)
+            return $ Just ( CryptoPacket n16 (pure x), () )
+
+encryptPacket :: SessionKeys -> CryptoData -> IO (CryptoPacket Encrypted)
+encryptPacket sk plain = do
+    n24 <- atomically $ do
+        n24 <- readTVar (skNonceOutgoing sk)
+        modifyTVar' (skNonceOutgoing sk) incrementNonce24
+        return n24
+    secret <- lookupSharedSecret (skCrypto sk) (skMe sk) (skThem sk) n24
+    let ciphered = encrypt secret $ encodePlain $ plain
+    return $ CryptoPacket (nonce24ToWord16 n24) ciphered
+
+data SessionKeys = SessionKeys
+    { skCrypto        :: TransportCrypto
+    , skMe            :: SecretKey
+    , skThem          :: PublicKey
+    , skNonceIncoming :: TVar Nonce24 -- +21845 when a threshold is reached.
+    , skNonceOutgoing :: TVar Nonce24 -- +1 on every packet
+    }
+
+bookKeeping :: SequenceInfo -> CryptoMessage -> CryptoData
+bookKeeping (SequenceInfo seqno ack) m = CryptoData
+    { bufferStart = seqno :: Word32
+    , bufferEnd   = ack   :: Word32
+    , bufferData  = m
+    }
+
+checkLossless :: CryptoData -> PacketInboundEvent CryptoMessage
+checkLossless CryptoData{ bufferStart = ack
+                        , bufferEnd   = no
+                        , bufferData  = x   } = tag no x ack
+ where
+    tag = case lossyness (msgID x) of Lossy -> PacketReceivedLossy
+                                      _     -> PacketReceived