+{-
+ - Copyright (C) 2015-2016 Ramakrishnan Muthukrishnan <ram@rkrishnan.org>
+ -
+ - This file is part of FuncTorrent.
+ -
+ - FuncTorrent is free software; you can redistribute it and/or modify
+ - it under the terms of the GNU General Public License as published by
+ - the Free Software Foundation; either version 3 of the License, or
+ - (at your option) any later version.
+ -
+ - FuncTorrent is distributed in the hope that it will be useful,
+ - but WITHOUT ANY WARRANTY; without even the implied warranty of
+ - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ - GNU General Public License for more details.
+ -
+ - You should have received a copy of the GNU General Public License
+ - along with FuncTorrent; if not, see <http://www.gnu.org/licenses/>
+ -}
+
{-# LANGUAGE OverloadedStrings #-}
+
module FuncTorrent.Peer
- (Peer(..),
- handShake,
- msgLoop
+ (handlePeerMsgs
) where
-import Prelude hiding (lookup, concat, replicate, splitAt, empty)
+import Prelude hiding (lookup, concat, replicate, splitAt, take, drop)
-import System.IO
-import Data.ByteString (ByteString, pack, unpack, concat, hGet, hPut, singleton)
-import Data.ByteString.Lazy (fromStrict, fromChunks)
-import qualified Data.ByteString.Char8 as BC (replicate, pack, length)
-import Network (connectTo, PortID(..))
-import Data.Binary (Binary(..), decode)
-import Data.Binary.Put (putWord32be, putWord16be, putWord8)
-import Data.Binary.Get (getWord32be, getWord16be, getWord8, runGet)
-import Control.Monad (replicateM, liftM, forever)
-import Control.Applicative ((<$>), liftA3)
+import Control.Concurrent.MVar (MVar, newEmptyMVar, readMVar, putMVar, takeMVar)
+import Control.Monad.State
+import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, drop, empty, singleton)
import Data.Bits
import Data.Word (Word8)
+import Data.Map (Map, (!), adjust, fromList, insert)
+import Network (connectTo, PortID(..))
+import System.IO (Handle, BufferMode(..), hSetBuffering, hClose)
+
+import FuncTorrent.Bencode(BVal(..), encode, decode, decodeWithLeftOvers)
+import FuncTorrent.Metainfo (Metainfo(..))
+import FuncTorrent.PeerMsgs (Peer(..), PeerMsg(..), sendMsg, getMsg, genHandshakeMsg)
+import FuncTorrent.Utils (splitNum, verifyHash)
+import FuncTorrent.PieceManager (PieceDlState(..), PieceData(..), PieceMap, pickPiece, updatePieceAvailability)
+import qualified FuncTorrent.FileSystem as FS (MsgChannel, writePieceToDisk)
+
+data PState = PState { handle :: Handle
+ , peer :: Peer
+ , meChoking :: Bool
+ , meInterested :: Bool
+ , heChoking :: Bool
+ , heInterested :: Bool}
-type ID = String
-type IP = String
-type Port = Integer
-
-data PeerState = PeerState { handle :: Handle
- , am_choking :: Bool
- , am_interested :: Bool
- , peer_choking :: Bool
- , peer_interested :: Bool}
-
--- Maintain info on every piece and the current state of it.
--- should probably be a TVar.
-type Pieces = [PieceData]
-
-data PieceState = Pending
- | InProgress
- | Have
- deriving (Show)
-
-data PieceData = PieceData { index :: Int -- ^ Piece number
- , peers :: [Peer] -- ^ list of peers who have this piece
- , state :: PieceState } -- ^ state of the piece from download perspective.
-
--- | Peer is a PeerID, IP address, port tuple
-data Peer = Peer ID IP Port
- deriving (Show, Eq)
-
-data PeerMsg = KeepAliveMsg
- | ChokeMsg
- | UnChokeMsg
- | InterestedMsg
- | NotInterestedMsg
- | HaveMsg Integer
- | BitFieldMsg ByteString
- | RequestMsg Integer Integer Integer
- | PieceMsg Integer Integer ByteString
- | CancelMsg Integer Integer Integer
- | PortMsg Port
- deriving (Show)
-
-genHandShakeMsg :: ByteString -> String -> ByteString
-genHandShakeMsg infoHash peer_id = concat [pstrlen, pstr, reserved, infoHash, peerID]
- where pstrlen = singleton 19
- pstr = BC.pack "BitTorrent protocol"
- reserved = BC.replicate 8 '\0'
- peerID = BC.pack peer_id
-
-handShake :: Peer -> ByteString -> String -> IO Handle
-handShake (Peer _ ip port) infoHash peerid = do
- let hs = genHandShakeMsg infoHash peerid
+data InfoPieceMap = InfoPieceMap { infoLength :: Integer
+ , infoMap :: Map Integer (Maybe ByteString) }
+
+newtype InfoState = InfoState (MVar InfoPieceMap)
+
+havePiece :: PieceMap -> Integer -> Bool
+havePiece pm index =
+ dlstate (pm ! index) == Have
+
+connectToPeer :: Peer -> IO Handle
+connectToPeer (Peer ip port) = do
h <- connectTo ip (PortNumber (fromIntegral port))
hSetBuffering h LineBuffering
- hPut h hs
- rlenBS <- hGet h (length (unpack hs))
- putStrLn $ "got handshake from peer: " ++ show rlenBS
return h
-instance Binary PeerMsg where
- put msg = case msg of
- KeepAliveMsg -> putWord32be 0
- ChokeMsg -> do putWord32be 1
- putWord8 0
- UnChokeMsg -> do putWord32be 1
- putWord8 1
- InterestedMsg -> do putWord32be 1
- putWord8 2
- NotInterestedMsg -> do putWord32be 1
- putWord8 3
- HaveMsg i -> do putWord32be 5
- putWord8 4
- putWord32be (fromIntegral i)
- BitFieldMsg bf -> do putWord32be $ fromIntegral (1 + bfListLen)
- putWord8 5
- mapM_ putWord8 bfList
- where bfList = unpack bf
- bfListLen = length bfList
- RequestMsg i o l -> do putWord32be 13
- putWord8 6
- putWord32be (fromIntegral i)
- putWord32be (fromIntegral o)
- putWord32be (fromIntegral l)
- PieceMsg i o b -> do putWord32be $ fromIntegral (9 + blocklen)
- putWord8 7
- putWord32be (fromIntegral i)
- putWord32be (fromIntegral o)
- mapM_ putWord8 blockList
- where blockList = unpack b
- blocklen = length blockList
- CancelMsg i o l -> do putWord32be 13
- putWord8 8
- putWord32be (fromIntegral i)
- putWord32be (fromIntegral o)
- putWord32be (fromIntegral l)
- PortMsg p -> do putWord32be 3
- putWord8 9
- putWord16be (fromIntegral p)
- get = do
- l <- getWord32be
- msgid <- getWord8
- case msgid of
- 0 -> return ChokeMsg
- 1 -> return UnChokeMsg
- 2 -> return InterestedMsg
- 3 -> return NotInterestedMsg
- 4 -> liftM (HaveMsg . fromIntegral) getWord32be
- 5 -> liftM (BitFieldMsg . pack) (replicateM (fromIntegral l - 1) getWord8)
- 6 -> liftA3 RequestMsg getInteger getInteger getInteger
- where getInteger = fromIntegral <$> getWord32be
- 7 -> liftA3 PieceMsg getInteger getInteger (pack <$> replicateM (fromIntegral l - 9) getWord8)
- where getInteger = fromIntegral <$> getWord32be
- 8 -> liftA3 CancelMsg getInteger getInteger getInteger
- where getInteger = fromIntegral <$> getWord32be
- 9 -> liftM (PortMsg . fromIntegral) getWord16be
- _ -> error ("unknown message ID: " ++ show msgid)
-
-getMsg :: Handle -> IO PeerMsg
-getMsg h = do
- lBS <- hGet h 4
- let l = bsToInt lBS
- if l == 0
- then return KeepAliveMsg
+
+doHandshake :: Bool -> Handle -> Peer -> ByteString -> String -> IO ()
+doHandshake True h p infohash peerid = do
+ let hs = genHandshakeMsg infohash peerid
+ hPut h hs
+ putStrLn $ "--> handhake to peer: " ++ show p
+ hsMsg <- hGet h (length (unpack hs))
+ putStrLn $ "<-- handshake from peer: " ++ show p
+ infoPieceMap <- newEmptyMVar
+ metadataMsgLoop h $ InfoState infoPieceMap
+ return ()
+ -- if doesPeerSupportExtendedMsg hsMsg
+ -- then
+ -- return doExtendedHandshake h
+ -- else
+ -- return Nothing
+doHandshake False h p infohash peerid = do
+ let hs = genHandshakeMsg infohash peerid
+ putStrLn "waiting for a handshake"
+ -- read 28 bytes. '19' ++ 'BitTorrent Protocol' ++ 8 reserved bytes
+ hsMsg <- hGet h 28
+ putStrLn $ "<-- handshake from peer: " ++ show p
+ let rxInfoHash = take 20 $ drop 28 hsMsg
+ if rxInfoHash /= infohash
+ then do
+ putStrLn "infoHashes does not match"
+ hClose h
+ return ()
else do
- msg <- hGet h l
- return $ decode $ fromStrict $ concat [lBS, msg]
-
-bsToInt :: ByteString -> Int
-bsToInt x = fromIntegral (runGet getWord32be (fromChunks (return x)))
-
-bitfieldToList :: [Word8] -> Integer -> [Integer]
-bitfieldToList [] pos = []
-bitfieldToList (b:bs) pos =
- let setBits = [pos*8 + (toInteger i) | i <- [0..8], testBit b i]
- in
- setBits ++ (bitfieldToList bs (pos + 1))
-
--- loop1 :: shake hands with all peers, find out the pieces they have, form PieceData.
--- recvMsg :: Peer -> Handle -> Msg
-
-msgLoop :: Handle -> ByteString -> IO ()
-msgLoop h pieceHash =
- let numPieces = (toInteger . (`quot` 20) . BC.length) pieceHash
- in
- forever $ do
- msg <- getMsg h
- putStrLn $ "got a " ++ show msg
- case msg of
- BitFieldMsg bss -> do
- let pieceList = bitfieldToList (unpack bss) 0
- putStrLn (show pieceList)
- -- doenload each of the piece
- _ -> putStrLn (show msg)
+ _ <- hPut h hs
+ putStrLn $ "--> handhake to peer: " ++ show p
+ -- if doesPeerSupportExtendedMsg hsMsg
+ -- then do
+ -- doExtendedHandshake h
+ -- else
+ -- return Nothing
+
+
+bitfieldToList :: [Word8] -> [Integer]
+bitfieldToList bs = go bs 0
+ where go [] _ = []
+ go (b:bs') pos =
+ let setBits = [pos*8 + toInteger i | i <- [0..8], testBit b i]
+ in
+ setBits ++ go bs' (pos + 1)
+
+-- helper functions to manipulate PeerState
+toPeerState :: Handle
+ -> Peer
+ -> Bool -- ^ meChoking
+ -> Bool -- ^ meInterested
+ -> Bool -- ^ heChoking
+ -> Bool -- ^ heInterested
+ -> PState
+toPeerState h p meCh meIn heCh heIn =
+ PState { handle = h
+ , peer = p
+ , heChoking = heCh
+ , heInterested = heIn
+ , meChoking = meCh
+ , meInterested = meIn }
+
+handlePeerMsgs :: Peer -> String -> Metainfo -> PieceMap -> Bool -> FS.MsgChannel -> IO ()
+handlePeerMsgs p peerId m pieceMap isClient c = do
+ h <- connectToPeer p
+ doHandshake isClient h p (infoHash m) peerId
+ let pstate = toPeerState h p False False True True
+ _ <- runStateT (msgLoop pieceMap c) pstate
+ return ()
+
+msgLoop :: PieceMap -> FS.MsgChannel -> StateT PState IO ()
+msgLoop pieceStatus msgchannel = do
+ h <- gets handle
+ st <- get
+ case st of
+ PState { meInterested = False, heChoking = True } -> do
+ liftIO $ sendMsg h InterestedMsg
+ gets peer >>= (\p -> liftIO $ putStrLn $ "--> InterestedMsg to peer: " ++ show p)
+ modify (\st' -> st' { meInterested = True })
+ msgLoop pieceStatus msgchannel
+ PState { meInterested = True, heChoking = False } ->
+ case pickPiece pieceStatus of
+ Nothing -> liftIO $ putStrLn "Nothing to download"
+ Just workPiece -> do
+ let pLen = len (pieceStatus ! workPiece)
+ liftIO $ putStrLn $ "piece length = " ++ show pLen
+ pBS <- liftIO $ downloadPiece h workPiece pLen
+ if not $ verifyHash pBS (hash (pieceStatus ! workPiece))
+ then
+ liftIO $ putStrLn "Hash mismatch"
+ else do
+ liftIO $ putStrLn $ "Write piece: " ++ show workPiece
+ liftIO $ FS.writePieceToDisk msgchannel workPiece pBS
+ msgLoop (adjust (\pieceData -> pieceData { dlstate = Have }) workPiece pieceStatus) msgchannel
+ _ -> do
+ msg <- liftIO $ getMsg h
+ gets peer >>= (\p -> liftIO $ putStrLn $ "<-- " ++ show msg ++ " from peer: " ++ show p)
+ case msg of
+ KeepAliveMsg -> do
+ liftIO $ sendMsg h KeepAliveMsg
+ gets peer >>= (\p -> liftIO $ putStrLn $ "--> " ++ "KeepAliveMsg to peer: " ++ show p)
+ msgLoop pieceStatus msgchannel
+ BitFieldMsg bss -> do
+ p <- gets peer
+ let pieceList = bitfieldToList (unpack bss)
+ pieceStatus' = updatePieceAvailability pieceStatus p pieceList
+ liftIO $ putStrLn $ show (length pieceList) ++ " Pieces"
+ -- for each pieceIndex in pieceList, make an entry in the pieceStatus
+ -- map with pieceIndex as the key and modify the value to add the peer.
+ -- download each of the piece in order
+ msgLoop pieceStatus' msgchannel
+ UnChokeMsg -> do
+ modify (\st' -> st' {heChoking = False })
+ msgLoop pieceStatus msgchannel
+ ChokeMsg -> do
+ modify (\st' -> st' {heChoking = True })
+ msgLoop pieceStatus msgchannel
+ InterestedMsg -> do
+ modify (\st' -> st' {heInterested = True})
+ msgLoop pieceStatus msgchannel
+ NotInterestedMsg -> do
+ modify (\st' -> st' {heInterested = False})
+ msgLoop pieceStatus msgchannel
+ CancelMsg {} -> -- check if valid index, begin, length
+ msgLoop pieceStatus msgchannel
+ PortMsg _ ->
+ msgLoop pieceStatus msgchannel
+ HaveMsg idx -> do
+ p <- gets peer
+ let pieceStatus' = updatePieceAvailability pieceStatus p [idx]
+ msgLoop pieceStatus' msgchannel
+ _ -> do
+ liftIO $ putStrLn ".. not doing anything with the msg"
+ msgLoop pieceStatus msgchannel
+ -- No need to handle PieceMsg and RequestMsg here.
+
+
+downloadPiece :: Handle -> Integer -> Integer -> IO ByteString
+downloadPiece h index pieceLength = do
+ let chunks = splitNum pieceLength 16384
+ concat `liftM` forM (zip [0..] chunks) (\(i, pLen) -> do
+ sendMsg h (RequestMsg index (i*pLen) pLen)
+ putStrLn $ "--> " ++ "RequestMsg for Piece "
+ ++ show index ++ ", part: " ++ show i ++ " of length: "
+ ++ show pLen
+ msg <- getMsg h
+ case msg of
+ PieceMsg index begin block -> do
+ putStrLn $ " <-- PieceMsg for Piece: "
+ ++ show index
+ ++ ", offset: "
+ ++ show begin
+ return block
+ _ -> do
+ putStrLn $ "ignoring irrelevant msg: " ++ show msg
+ return empty)
+
+
+{-
+ -- Extension messages support (BEP-0010) --
+
+
+ In the regular peer handshake, adventise support for extension protocol. Protocol
+ extensions are done via the reserved bytes (8 of them) in the handshake message
+ as detailed in BEP-0003. For this particular "Extension Protocol" extension, we use
+ 20th bit (counted from the right, from 0) is set to 1.
+
+ Once support for the extension protocol is established by the peer, the Peer is supposed
+ to support one message with the ID 20. This is sent like a regular message with 4-byte
+ length prefix and the msg id (20) in this case.
+
+ First byte of the payload of this message is either 0, which means it is a handshake
+ msg.
+
+ The rest of the payload is a dictionary with various keys. All of them are optional. The
+ one of interest at the moment for me is the one with key 'm' whose value is another
+ dictionary of all supported extensions.
+
+ Here is where it gets interesting for us (to support magneturi. When the torrent client
+ has only got a magneturi to look at, it has only got the list of trackers with it (we
+ are not looking at the DHT case for the time being). So, it somehow needs to get the info
+ dictionary. It gets this by talking to another peer in the network. To do that, the client
+ needs to talk tracker protocol, get the list of peers and talk to peers using the above
+ extension protocol to get the infodict as payload. Let us see how we can do that now.
+
+ If a peer already has the full infodict, then, the handshake message sent by that peer
+ is something like this:
+
+ {'m': {'ut_metadata', 3}, 'metadata_size': 31235}
+
+ Note that the 'metadata_size' is not part of the value of the key 'm'.
+ If we are a new client and are requesting the handshake to a peer, then we don't have
+ the infodict yet, in which case, we only send the first part:
+
+ {'m': {'ut_metadata', 3}}
+
+ This is bencoded and sent across the wire. The value "3" (integer) against the key
+ 'ut_metadata" is an ordered integer within a client that identifies the extention.
+ No two extension supported by the same client shares the same value. If the value is
+ '0', then the extension is unsupported.
+
+ Here we use the BEP-0009, the metadata extension protocol. The metadata in this case
+ is the infodict. The infodict itself is divided into 16KB sized pieces.
+
+ Here is a possible interaction between two peers:
+
+ 1. Peer Pn comes up, gets the ip/ports of other peers, P0, P1.... Pn does not have the
+ size of the infodict. Pn has advertised itself as supporting the extension protocol.
+ It sends the handshake msg to other peers with this bit on in the reserved bytes.
+ 2. Let us say, P1 replied with a handshake. We check if it also supports the extension
+ mechanism.
+ 3. Now we get into the extension message passing so that we have the info dict.
+ To do that, we send the extension handshake (ut_metadata) m dict without the
+ metadata_size. We get back the extension handshake with metadata_size. We take
+ note of the size.
+ 4. We calculate the number of 16384 chunks in the total size of the metadata. That
+ gives us the number of pieces the metadata has.
+ 5. We send a "request" extension msg:
+ {'msg_type': 0, 'piece': 0}
+ 6. We recieve the "data" message.
+ {'msg_type': 1, 'piece': 0, 'total_size': 3425} in bencoded format, followed by
+ total_size bytes. total_size is 16KiB except perhaps for the last piece.
+ 7. If the peer does not have the requested piece, it sends the "reject" message.
+ {'msg_type': 2, 'piece': 0}
+ 8. Repeat 5, 6/7 for every piece.
+
+ At this point, we have the infodict.
+
+-}
+
+{-
+data InfoPieceMap = { infoLength :: Integer
+ , infoMap :: Map Integer (Maybe ByteString)
+ }
+
+newtype InfoState = InfoState (MVar InfoPieceMap)
+
+-}
+
+
+metadataMsgLoop :: Handle -> InfoState -> IO ()
+metadataMsgLoop h (InfoState st) = do
+ infoState <- readMVar st
+ let metadataLen = infoLength infoState
+ -- send the handshake msg
+ metadata = encode (metadataMsg metadataLen)
+ sendMsg h (ExtendedMsg 0 metadata)
+ -- recv return msg from the peer. Will have 'metadata_size'
+ msg <- getMsg h
+ case msg of
+ ExtendedMsg 0 rBs -> do
+ -- decode rBs
+ let (Right (Bdict msgMap)) = decode rBs
+ (Bdict mVal) = msgMap ! "m" -- which is another dict
+ (Bint metadata_msgID) = mVal ! "ut_metadata"
+ (Bint metadata_size) = msgMap ! "metadata_size"
+ -- divide metadata_size into 16384 sized pieces, find number of pieces
+ (q, r) = metadata_size `divMod` 16384
+ -- pNumLengthPairs = zip [0..q-1] (take q (repeat 16384)) ++ (q, r)
+ -- TODO: corner case where infodict size is a multiple of 16384
+ -- and start sending request msg for each.
+ if metadataLen == 0
+ then -- We don't have any piece. Send request msg for all pieces.
+ mapM_ (\n -> do
+ sendMsg h (ExtendedMsg metadata_msgID (encode (requestMsg n)))
+ dataOrRejectMsg <- getMsg h
+ case dataOrRejectMsg of
+ ExtendedMsg 3 payload -> do
+ -- bencoded dict followed by XXXXXX
+ infoState <- takeMVar st
+ let (Right (Bdict bval, pieceData)) = decodeWithLeftOvers payload
+ (Bint pieceIndex) = bval ! "piece"
+ payloadLen = length (unpack pieceData)
+ infoMapVal = infoMap infoState
+ putMVar st infoState {
+ infoMap = insert pieceIndex (Just payload) infoMapVal }
+ )
+ [0..q]
+ else
+ return () -- TODO: reject for now
+ where
+ metadataMsg 0 = Bdict (fromList [("m", Bdict (fromList [("ut_metadata", (Bint 3))]))])
+ metadataMsg l = Bdict (fromList [("m", Bdict (fromList [("ut_metadata", (Bint 3))])),
+ ("metadata_size", (Bint l))])
+ requestMsg i = Bdict (fromList [("msg_type", (Bint 0)), ("piece", (Bint i))])
+ rejectmsg i = Bdict (fromList [("msg_type", (Bint 2)), ("piece", (Bint i))])
+
+doesPeerSupportExtendedMsg :: ByteString -> Bool
+doesPeerSupportExtendedMsg bs = take 1 (drop 5 bs) == singleton 0x10
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