1 {-# LANGUAGE OverloadedStrings #-}
2 module FuncTorrent.Peer
7 import Prelude hiding (lookup, concat, replicate, splitAt, take)
9 import System.IO (Handle, BufferMode(..), hSetBuffering)
10 import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, empty)
11 import qualified Data.ByteString.Char8 as BC (length)
12 import Network (connectTo, PortID(..))
13 import Control.Monad.State
15 import Data.Word (Word8)
16 import Data.Map (Map, fromList, toList, (!), mapWithKey, adjust)
17 import qualified Crypto.Hash.SHA1 as SHA1 (hash)
19 import FuncTorrent.Metainfo (Info(..), Metainfo(..))
20 import FuncTorrent.Utils (splitN, splitNum)
21 import FuncTorrent.Fileops (createDummyFile, writeFileAtOffset)
22 import FuncTorrent.PeerMsgs (Peer(..), PeerMsg(..), sendMsg, getMsg, genHandshakeMsg)
24 data PState = PState { handle :: Handle
27 , meInterested :: Bool
29 , heInterested :: Bool}
31 type PeerState = State PState
33 data PieceDlState = Pending
38 -- todo - map with index to a new data structure (peers who have that piece amd state)
39 data PieceData = PieceData { peers :: [Peer] -- ^ list of peers who have this piece
40 , dlstate :: PieceDlState -- ^ state of the piece from download perspective.
41 , hash :: ByteString -- ^ piece hash
42 , len :: Integer } -- ^ piece length
44 -- which piece is with which peers
45 type PieceMap = Map Integer PieceData
48 -- Make the initial Piece map, with the assumption that no peer has the
49 -- piece and that every piece is pending download.
50 mkPieceMap :: Integer -> ByteString -> [Integer] -> PieceMap
51 mkPieceMap numPieces pieceHash pLengths = fromList kvs
52 where kvs = [(i, PieceData { peers = []
56 | (i, h, pLen) <- zip3 [0..numPieces] hashes pLengths]
57 hashes = splitN 20 pieceHash
59 havePiece :: PieceMap -> Integer -> Bool
61 dlstate (pm ! index) == Have
63 connectToPeer :: Peer -> IO Handle
64 connectToPeer (Peer _ ip port) = do
65 h <- connectTo ip (PortNumber (fromIntegral port))
66 hSetBuffering h LineBuffering
69 doHandshake :: Handle -> Peer -> ByteString -> String -> IO ()
70 doHandshake h peer infoHash peerid = do
71 let hs = genHandshakeMsg infoHash peerid
73 putStrLn $ "--> handhake to peer: " ++ show peer
74 _ <- hGet h (length (unpack hs))
75 putStrLn $ "<-- handshake from peer: " ++ show peer
78 bitfieldToList :: [Word8] -> [Integer]
79 bitfieldToList bs = go bs 0
82 let setBits = [pos*8 + toInteger i | i <- [0..8], testBit b i]
84 setBits ++ go bs' (pos + 1)
86 -- helper functions to manipulate PeerState
87 toPeerState :: Handle -> Peer -> Bool -> Bool -> Bool -> Bool -> PState
88 toPeerState h p meCh meIn heCh heIn =
94 , meInterested = meIn }
96 -- -- recvMsg :: Peer -> Handle -> Msg
97 -- msgLoop :: PeerState -> PieceMap -> FilePath -> IO ()
98 -- msgLoop pState@(PeerState { meInterested = False, heChoking = True }) pieceStatus file = do
99 -- -- if me NOT Interested and she is Choking, tell her that
100 -- -- I am interested.
101 -- let h = handle pState
102 -- sendMsg h InterestedMsg
103 -- putStrLn $ "--> InterestedMsg to peer: " ++ show (peer pState)
104 -- msgLoop (pState { meInterested = True }) pieceStatus file
105 -- msgLoop pState@(PeerState { meInterested = True, heChoking = False }) pieceStatus file =
106 -- -- if me Interested and she not Choking, send her a request
108 -- case pickPiece pieceStatus of
109 -- Nothing -> putStrLn "Nothing to download"
110 -- Just workPiece -> do
111 -- let pLen = len (pieceStatus ! workPiece)
112 -- putStrLn $ "piece length = " ++ show pLen
113 -- pBS <- downloadPiece (handle pState) workPiece pLen
114 -- if not $ verifyHash pBS (hash (pieceStatus ! workPiece))
116 -- putStrLn $ "Hash mismatch: " ++ show (hash (pieceStatus ! workPiece)) ++ " vs " ++ show (take 20 (SHA1.hash pBS))
118 -- let fileOffset = if workPiece == 0 then 0 else workPiece * len (pieceStatus ! (workPiece - 1))
119 -- putStrLn $ "Write into file at offset: " ++ show fileOffset
120 -- writeFileAtOffset file fileOffset pBS
121 -- msgLoop pState (adjust (\pieceData -> pieceData { state = Have }) workPiece pieceStatus) file
122 -- msgLoop pState pieceStatus file = do
123 -- msg <- getMsg (handle pState)
124 -- putStrLn $ "<-- " ++ show msg ++ "from peer: " ++ show (peer pState)
126 -- KeepAliveMsg -> do
127 -- sendMsg (handle pState) KeepAliveMsg
128 -- putStrLn $ "--> " ++ "KeepAliveMsg to peer: " ++ show (peer pState)
129 -- msgLoop pState pieceStatus file
130 -- BitFieldMsg bss -> do
131 -- let pieceList = bitfieldToList (unpack bss)
132 -- pieceStatus' = updatePieceAvailability pieceStatus (peer pState) pieceList
133 -- putStrLn $ show (length pieceList) ++ " Pieces"
134 -- -- for each pieceIndex in pieceList, make an entry in the pieceStatus
135 -- -- map with pieceIndex as the key and modify the value to add the peer.
136 -- -- download each of the piece in order
137 -- msgLoop pState pieceStatus' file
139 -- msgLoop (pState { heChoking = False }) pieceStatus file
141 -- msgLoop pState pieceStatus file
143 -- simple algorithm to pick piece.
144 -- pick the first piece from 0 that is not downloaded yet.
145 pickPiece :: PieceMap -> Maybe Integer
147 let pieceList = toList m
148 allPending = filter (\(_, v) -> dlstate v == Pending) pieceList
154 updatePieceAvailability :: PieceMap -> Peer -> [Integer] -> PieceMap
155 updatePieceAvailability pieceStatus p pieceList =
156 mapWithKey (\k pd -> if k `elem` pieceList
157 then (pd { peers = p : peers pd })
160 handlePeerMsgs :: Peer -> Metainfo -> String -> IO ()
161 handlePeerMsgs p m peerId = do
163 doHandshake h p (infoHash m) peerId
164 let pstate = toPeerState h p False True False True
165 pieceHash = pieces (info m)
166 numPieces = (toInteger . (`quot` 20) . BC.length) pieceHash
167 pLen = pieceLength (info m)
168 fileLen = lengthInBytes (info m)
169 fileName = name (info m)
170 pieceStatus = mkPieceMap numPieces pieceHash (splitNum fileLen pLen)
171 createDummyFile fileName (fromIntegral fileLen)
172 (r, _) <- runStateT (msgLoop pieceStatus fileName) pstate
175 msgLoop :: PieceMap -> FilePath -> StateT PState IO ()
176 msgLoop pieceStatus file =
178 let h = handle pState
180 liftIO $ putStrLn $ "<-- " ++ show msg ++ "from peer: " ++ show (peer pState)
183 sendMsg h KeepAliveMsg
184 liftIO $ putStrLn $ "--> " ++ "KeepAliveMsg to peer: " ++ show (peer pState)
185 runStateT (msgLoop pieceStatus file) pState)
187 downloadPiece :: Handle -> Integer -> Integer -> IO ByteString
188 downloadPiece h index pieceLength = do
189 let chunks = splitNum pieceLength 16384
190 liftM concat $ forM (zip [0..] chunks) (\(i, pLen) -> do
191 sendMsg h (RequestMsg index (i*pLen) pLen)
192 putStrLn $ "--> " ++ "RequestMsg for Piece "
193 ++ show index ++ ", part: " ++ show i ++ " of length: "
197 PieceMsg index begin block -> do
198 putStrLn $ " <-- PieceMsg for Piece: "
204 putStrLn "ignoring irrelevant msg"
207 verifyHash :: ByteString -> ByteString -> Bool
208 verifyHash bs pieceHash =
209 take 20 (SHA1.hash bs) == pieceHash