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[functorrent.git] / src / FuncTorrent / Peer.hs

diff --git a/src/FuncTorrent/Peer.hs b/src/FuncTorrent/Peer.hs
index 61b5112c7811d43e765a4d59e01bb8d68e546999..2b9ff5ffd2264d26c311407d697ed4a0f7e6418e 100644 (file)
--- a/src/FuncTorrent/Peer.hs
+++ b/src/FuncTorrent/Peer.hs
@@ -8,19 +8,20 @@ module FuncTorrent.Peer
 import Prelude hiding (lookup, concat, replicate, splitAt, take, filter)
 
 import System.IO (Handle, BufferMode(..), hSetBuffering)
+import System.Directory (doesFileExist)
 import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, empty)
 import qualified Data.ByteString.Char8 as BC (length)
 import Network (connectTo, PortID(..))
 import Control.Monad.State
 import Data.Bits
 import Data.Word (Word8)
-import Data.Map (Map, fromList, toList, (!), mapWithKey, adjust, filter)
+import Data.Map (Map, fromList, toList, (!), mapWithKey, traverseWithKey, adjust, filter)
 import qualified Crypto.Hash.SHA1 as SHA1 (hash)
 import Safe (headMay)
 
 import FuncTorrent.Metainfo (Info(..), Metainfo(..))
 import FuncTorrent.Utils (splitN, splitNum)
-import FuncTorrent.Fileops (createDummyFile, writeFileAtOffset)
+import FuncTorrent.Fileops (createDummyFile, writeFileAtOffset, readFileAtOffset)
 import FuncTorrent.PeerMsgs (Peer(..), PeerMsg(..), sendMsg, getMsg, genHandshakeMsg)
 
 data PState = PState { handle :: Handle
@@ -61,6 +62,25 @@ initPieceMap pieceHash fileLen pieceLen = fromList kvs
     hashes = splitN 20 pieceHash
     pLengths = (splitNum fileLen pieceLen)
 
+updatePieceMap :: FilePath -> PieceMap -> IO PieceMap
+updatePieceMap filePath pieceMap = do
+  dfe <- doesFileExist filePath
+  -- TODO: this is not enough, file should have the same size as well
+  if dfe
+    then pieceMapFromFile filePath pieceMap
+    else return pieceMap
+
+pieceMapFromFile :: FilePath -> PieceMap -> IO PieceMap
+pieceMapFromFile filePath pieceMap = do
+  traverseWithKey f pieceMap
+    where
+      f k v = do
+        let offset = if k == 0 then 0 else k * len (pieceMap ! (k - 1))
+        isHashValid <- (flip verifyHash) (hash v) <$> (readFileAtOffset filePath offset (len v))
+        if isHashValid
+          then return $ v { dlstate = Have }
+          else return $ v
+
 havePiece :: PieceMap -> Integer -> Bool
 havePiece pm index =
   dlstate (pm ! index) == Have
@@ -130,8 +150,9 @@ handlePeerMsgs p peerId m = do
       fileLen = lengthInBytes (info m)
       fileName = name (info m)
       pieceStatus = initPieceMap pieceHash fileLen pLen
+  pieceStatus' <- updatePieceMap fileName pieceStatus
   createDummyFile fileName (fromIntegral fileLen)
-  _ <- runStateT (msgLoop pieceStatus fileName) pstate
+  _ <- runStateT (msgLoop pieceStatus' fileName) pstate
   return ()
 
 msgLoop :: PieceMap -> FilePath -> StateT PState IO ()