From 72f029586552ffb94c0a8811be9fe3e7c20865cd Mon Sep 17 00:00:00 2001
From: Ramakrishnan Muthukrishnan <ram@rkrishnan.org>
Date: Mon, 4 May 2015 22:29:58 +0530
Subject: [PATCH] WIP: Peer protocol message marshalling

---
 src/FuncTorrent/Peer.hs | 83 +++++++++++++++++++++++++++++++++--------
 1 file changed, 67 insertions(+), 16 deletions(-)

diff --git a/src/FuncTorrent/Peer.hs b/src/FuncTorrent/Peer.hs
index 798f60a..6b2ec72 100644
--- a/src/FuncTorrent/Peer.hs
+++ b/src/FuncTorrent/Peer.hs
@@ -10,33 +10,48 @@ import System.IO
 import Data.ByteString (ByteString, unpack, concat, hGet, hPut, singleton)
 import Data.ByteString.Char8 (replicate, pack)
 import Network (connectTo, PortID(..))
+import Data.Binary (Binary(..))
+import Data.Binary.Put (putWord32be, putWord8)
 
 type ID = String
 type IP = String
 type Port = Integer
 
-data PeerState = PeerState { am_choking :: Bool
+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 Msg = HandShakeMsg ByteString ID
-         | KeepAliveMsg
-         | ChokeMsg
-         | UnChokeMsg
-         | InterestedMsg
-         | NotInterestedMsg
-         | HaveMsg Integer
-         | BitFieldMsg Integer
-         | RequestMsg Integer Integer Integer
-         | PieceMsg Integer Integer Integer
-         | CancelMsg Integer Integer Integer
-         | PortMsg Port
-         deriving (Show)
+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]
@@ -45,7 +60,7 @@ genHandShakeMsg infoHash peer_id = concat [pstrlen, pstr, reserved, infoHash, pe
         reserved = replicate 8 '\0'
         peerID = pack peer_id
 
-handShake :: Peer -> ByteString -> String -> IO ByteString
+handShake :: Peer -> ByteString -> String -> IO Handle
 handShake (Peer _ ip port) infoHash peerid = do
   let hs = genHandShakeMsg infoHash peerid
   handle <- connectTo ip (PortNumber (fromIntegral port))
@@ -54,6 +69,42 @@ handShake (Peer _ ip port) infoHash peerid = do
   rlenBS <- hGet handle 1
   let rlen = fromIntegral $ (unpack rlenBS) !! 0
   hGet handle rlen
+  return handle
+
+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 index -> do putWord32be 5
+                                 putWord8 4
+                                 putWord32be (fromIntegral index)
+             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 -> undefined
+             PortMsg p -> undefined
+  get = undefined
 
--- sendMsg :: Peer -> Handle -> PeerMsg -> IO ()
+-- loop1 :: shake hands with all peers, find out the pieces they have, form PieceData.
 -- recvMsg :: Peer -> Handle -> Msg
-- 
2.37.2