{-# LANGUAGE OverloadedStrings #-}
module FuncTorrent.Peer
- (PieceMap,
- handlePeerMsgs
+ (handlePeerMsgs
) where
import Prelude hiding (lookup, concat, replicate, splitAt, take, drop)
+import Control.Concurrent.MVar (MVar, newEmptyMVar, readMVar, putMVar, takeMVar)
import Control.Monad.State
-import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, drop, empty)
+import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, drop, empty, singleton)
import Data.Bits
import Data.Word (Word8)
-import Data.Map ((!), adjust)
+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)
, heChoking :: Bool
, heInterested :: Bool}
+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
hSetBuffering h LineBuffering
return h
+
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
- _ <- hGet h (length (unpack hs))
+ 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"
- hsMsg <- hGet h (length (unpack hs))
+ -- 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
else do
_ <- hPut h hs
putStrLn $ "--> handhake to peer: " ++ show p
- return ()
+ -- if doesPeerSupportExtendedMsg hsMsg
+ -- then do
+ -- doExtendedHandshake h
+ -- else
+ -- return Nothing
+
bitfieldToList :: [Word8] -> [Integer]
bitfieldToList bs = go bs 0
NotInterestedMsg -> do
modify (\st' -> st' {heInterested = False})
msgLoop pieceStatus msgchannel
- CancelMsg _ _ _ -> -- check if valid index, begin, length
+ CancelMsg {} -> -- check if valid index, begin, length
msgLoop pieceStatus msgchannel
PortMsg _ ->
msgLoop pieceStatus msgchannel
let pieceStatus' = updatePieceAvailability pieceStatus p [idx]
msgLoop pieceStatus' msgchannel
_ -> do
- liftIO $ putStrLn $ ".. not doing anything with the msg"
+ liftIO $ putStrLn ".. not doing anything with the msg"
msgLoop pieceStatus msgchannel
-- No need to handle PieceMsg and RequestMsg here.
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
projects / functorrent.git / blobdiff