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
89 -> Bool -- ^ meChoking
90 -> Bool -- ^ meInterested
91 -> Bool -- ^ heChoking
92 -> Bool -- ^ heInterested
94 toPeerState h p meCh meIn heCh heIn =
100 , meInterested = meIn }
102 -- -- recvMsg :: Peer -> Handle -> Msg
103 -- msgLoop :: PeerState -> PieceMap -> FilePath -> IO ()
104 -- msgLoop pState@(PeerState { meInterested = False, heChoking = True }) pieceStatus file = do
105 -- -- if me NOT Interested and she is Choking, tell her that
106 -- -- I am interested.
107 -- let h = handle pState
108 -- sendMsg h InterestedMsg
109 -- putStrLn $ "--> InterestedMsg to peer: " ++ show (peer pState)
110 -- msgLoop (pState { meInterested = True }) pieceStatus file
111 -- msgLoop pState@(PeerState { meInterested = True, heChoking = False }) pieceStatus file =
112 -- -- if me Interested and she not Choking, send her a request
114 -- case pickPiece pieceStatus of
115 -- Nothing -> putStrLn "Nothing to download"
116 -- Just workPiece -> do
117 -- let pLen = len (pieceStatus ! workPiece)
118 -- putStrLn $ "piece length = " ++ show pLen
119 -- pBS <- downloadPiece (handle pState) workPiece pLen
120 -- if not $ verifyHash pBS (hash (pieceStatus ! workPiece))
122 -- putStrLn $ "Hash mismatch: " ++ show (hash (pieceStatus ! workPiece)) ++ " vs " ++ show (take 20 (SHA1.hash pBS))
124 -- let fileOffset = if workPiece == 0 then 0 else workPiece * len (pieceStatus ! (workPiece - 1))
125 -- putStrLn $ "Write into file at offset: " ++ show fileOffset
126 -- writeFileAtOffset file fileOffset pBS
127 -- msgLoop pState (adjust (\pieceData -> pieceData { state = Have }) workPiece pieceStatus) file
128 -- msgLoop pState pieceStatus file = do
129 -- msg <- getMsg (handle pState)
130 -- putStrLn $ "<-- " ++ show msg ++ "from peer: " ++ show (peer pState)
132 -- KeepAliveMsg -> do
133 -- sendMsg (handle pState) KeepAliveMsg
134 -- putStrLn $ "--> " ++ "KeepAliveMsg to peer: " ++ show (peer pState)
135 -- msgLoop pState pieceStatus file
136 -- BitFieldMsg bss -> do
137 -- let pieceList = bitfieldToList (unpack bss)
138 -- pieceStatus' = updatePieceAvailability pieceStatus (peer pState) pieceList
139 -- putStrLn $ show (length pieceList) ++ " Pieces"
140 -- -- for each pieceIndex in pieceList, make an entry in the pieceStatus
141 -- -- map with pieceIndex as the key and modify the value to add the peer.
142 -- -- download each of the piece in order
143 -- msgLoop pState pieceStatus' file
145 -- msgLoop (pState { heChoking = False }) pieceStatus file
147 -- msgLoop pState pieceStatus file
149 -- simple algorithm to pick piece.
150 -- pick the first piece from 0 that is not downloaded yet.
151 pickPiece :: PieceMap -> Maybe Integer
153 let pieceList = toList m
154 allPending = filter (\(_, v) -> dlstate v == Pending) pieceList
160 updatePieceAvailability :: PieceMap -> Peer -> [Integer] -> PieceMap
161 updatePieceAvailability pieceStatus p pieceList =
162 mapWithKey (\k pd -> if k `elem` pieceList
163 then (pd { peers = p : peers pd })
166 handlePeerMsgs :: Peer -> Metainfo -> String -> IO ()
167 handlePeerMsgs p m peerId = do
169 doHandshake h p (infoHash m) peerId
170 let pstate = toPeerState h p False True False True
171 pieceHash = pieces (info m)
172 numPieces = (toInteger . (`quot` 20) . BC.length) pieceHash
173 pLen = pieceLength (info m)
174 fileLen = lengthInBytes (info m)
175 fileName = name (info m)
176 pieceStatus = mkPieceMap numPieces pieceHash (splitNum fileLen pLen)
177 createDummyFile fileName (fromIntegral fileLen)
178 (r, _) <- runStateT (msgLoop pieceStatus fileName) pstate
181 msgLoop :: PieceMap -> FilePath -> StateT PState IO ()
182 msgLoop pieceStatus file = do
184 msg <- liftIO $ getMsg h
185 gets peer >>= (\p -> liftIO $ putStrLn $ "<-- " ++ show msg ++ "from peer: " ++ show p)
188 liftIO $ sendMsg h KeepAliveMsg
189 gets peer >>= (\p -> liftIO $ putStrLn $ "--> " ++ "KeepAliveMsg to peer: " ++ show p)
190 msgLoop pieceStatus file
192 downloadPiece :: Handle -> Integer -> Integer -> IO ByteString
193 downloadPiece h index pieceLength = do
194 let chunks = splitNum pieceLength 16384
195 liftM concat $ forM (zip [0..] chunks) (\(i, pLen) -> do
196 sendMsg h (RequestMsg index (i*pLen) pLen)
197 putStrLn $ "--> " ++ "RequestMsg for Piece "
198 ++ show index ++ ", part: " ++ show i ++ " of length: "
202 PieceMsg index begin block -> do
203 putStrLn $ " <-- PieceMsg for Piece: "
209 putStrLn "ignoring irrelevant msg"
212 verifyHash :: ByteString -> ByteString -> Bool
213 verifyHash bs pieceHash =
214 take 20 (SHA1.hash bs) == pieceHash