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{-# LANGUAGE DoAndIfThenElse #-}
module Network.Torrent.PWP
( Message(..), Block(..), BlockIx(..),
) where
import Control.Applicative
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import Data.Serialize
data BlockIx = BlockIx {
ixPiece :: {-# UNPACK #-} !Int -- ^ Zero-based piece index.
, ixOffset :: {-# UNPACK #-} !Int -- ^ Zero-based byte offset within the piece.
, ixLength :: {-# UNPACK #-} !Int -- ^ Block size starting from offset.
} deriving (Show, Eq)
data Block = Block {
blkPiece :: Int -- ^ Zero-based piece index.
, blkOffset :: Int -- ^ Zero-based byte offset within the piece.
, blkData :: ByteString -- ^ Payload.
} deriving (Show, Eq)
-- TODO comment message constructors
data Message = KeepAlive
| Choke
| Unchoke
| Interested
| NotInterested
| Have Int
| Bitfield ByteString
| Request BlockIx
| Piece Block
| Cancel BlockIx
| Port Int
deriving (Show, Eq)
getInt :: Get Int
getInt = fromIntegral <$> getWord32be
{-# INLINE getInt #-}
putInt :: Putter Int
putInt = putWord32be . fromIntegral
{-# INLINE putInt #-}
instance Serialize BlockIx where
{-# SPECIALIZE instance Serialize BlockIx #-}
get = BlockIx <$> getInt <*> getInt <*> getInt
{-# INLINE get #-}
put ix = do putInt (ixPiece ix)
putInt (ixOffset ix)
putInt (ixLength ix)
{-# INLINE put #-}
instance Serialize Message where
get = do
len <- getInt
lookAhead $ ensure len
if len == 0 then return KeepAlive
else do
mid <- getWord8
case mid of
0 -> return Choke
1 -> return Unchoke
2 -> return Interested
3 -> return NotInterested
4 -> Have <$> getInt
5 -> Bitfield <$> getBytes (pred len)
6 -> Request <$> get
7 -> Piece <$> getBlock (len - 9)
8 -> Cancel <$> get
9 -> (Port . fromIntegral) <$> getWord16be
_ -> fail $ "unknown message ID: " ++ show mid
where
getBlock :: Int -> Get Block
getBlock len = Block <$> getInt <*> getInt <*> getBytes len
{-# INLINE getBlock #-}
put KeepAlive = putInt 0
put Choke = putInt 1 >> putWord8 0
put Unchoke = putInt 1 >> putWord8 1
put Interested = putInt 1 >> putWord8 2
put NotInterested = putInt 1 >> putWord8 3
put (Have i) = putInt 5 >> putWord8 4 >> putInt i
put (Bitfield b) = putInt l >> putWord8 5 >> putByteString b
where l = succ (B.length b)
{-# INLINE l #-}
put (Request blk) = putInt 13 >> putWord8 6 >> put blk
put (Piece blk) = putInt l >> putWord8 7 >> putBlock
where l = 9 + B.length (blkData blk)
{-# INLINE l #-}
putBlock = do putInt (blkPiece blk)
putInt (blkOffset blk)
putByteString (blkData blk)
{-# INLINE putBlock #-}
put (Cancel blk) = putInt 13 >> putWord8 8 >> put blk
put (Port p ) = putInt 3 >> putWord8 9 >> putWord16be (fromIntegral p)
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