+{-# LANGUAGE OverloadedStrings #-}
module FuncTorrent.Tracker
- (connect,
- infoHash,
- prepareRequest,
+ (TrackerResponse(..),
+ mkArgs,
+ getTrackerResponse,
urlEncodeHash
) where
-import Prelude hiding (lookup)
-import Crypto.Hash.SHA1 (hash)
-import Data.ByteString.Char8 (ByteString, pack, unpack)
+import Prelude hiding (lookup, splitAt)
+
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Reader (ReaderT, ask, runReaderT)
+import Data.ByteString (ByteString)
+import Data.ByteString.Char8 as BC (pack, unpack, splitAt)
import Data.Char (chr)
import Data.List (intercalate)
-import Data.Maybe (fromJust)
-import Data.Map as M (Map, (!))
-import Network.HTTP (simpleHTTP, defaultGETRequest_, getResponseBody)
+import Data.Map as M (lookup)
import Network.HTTP.Base (urlEncode)
-import Network.URI (parseURI)
import qualified Data.ByteString.Base16 as B16 (encode)
-import FuncTorrent.Bencode (BVal(..), InfoDict, encode)
+import FuncTorrent.Bencode (BVal(..), decode)
+import FuncTorrent.Metainfo (Info(..), Metainfo(..))
+import FuncTorrent.Network (get)
+import FuncTorrent.Peer (Peer(..))
import FuncTorrent.Utils (splitN)
-type Url = String
+-- | Tracker response
+data TrackerResponse = TrackerResponse {
+ interval :: Maybe Integer
+ , peers :: [Peer]
+ , complete :: Maybe Integer
+ , incomplete :: Maybe Integer
+ } deriving (Show, Eq)
+
+-- | Deserialize tracker response
+mkTrackerResponse :: BVal -> Either ByteString TrackerResponse
+mkTrackerResponse resp =
+ case lookup "failure reason" body of
+ Just (Bstr err) -> Left err
+ Just _ -> Left "Unknown failure"
+ Nothing ->
+ let (Just (Bint i)) = lookup "interval" body
+ (Just (Bstr peersBS)) = lookup "peers" body
+ pl = map makePeer (splitN 6 peersBS)
+ in Right TrackerResponse {
+ interval = Just i
+ , peers = pl
+ , complete = Nothing
+ , incomplete = Nothing
+ }
+ where
+ (Bdict body) = resp
+
+ toInt :: String -> Integer
+ toInt = read
+
+ toPort :: ByteString -> Integer
+ toPort = read . ("0x" ++) . unpack . B16.encode
+
+ toIP :: ByteString -> String
+ toIP = Data.List.intercalate "." .
+ map (show . toInt . ("0x" ++) . unpack) .
+ splitN 2 . B16.encode
--- | urlEncodeHash
---
--- >>> urlEncodeHash $ pack "123456789abcdef123456789abcdef123456789a"
--- "%124Vx%9a%bc%de%f1%23Eg%89%ab%cd%ef%124Vx%9a"
+ makePeer :: ByteString -> Peer
+ makePeer peer = Peer "" (toIP ip') (toPort port')
+ where (ip', port') = splitAt 4 peer
+
+-- | Connect to a tracker and get peer info
+tracker :: String -> ReaderT Metainfo IO ByteString
+tracker peer_id = do
+ m <- ask
+ let args = mkArgs peer_id m
+ liftIO $ get (head . announceList $ m) $ args
+
+getTrackerResponse :: String -> ReaderT Metainfo IO (Either ByteString TrackerResponse)
+getTrackerResponse peerId = do
+ m <- ask
+ resp <- liftIO $ runReaderT (tracker peerId) m
+ case decode resp of
+ Right trackerInfo -> liftIO $ return $ mkTrackerResponse trackerInfo
+ Left e -> return $ Left (pack (show e))
+
+--- | URL encode hash as per RFC1738
+--- TODO: Add tests
+--- REVIEW: Why is this not written in terms of `Network.HTTP.Base.urlEncode` or
+--- equivalent library function?
urlEncodeHash :: ByteString -> String
urlEncodeHash bs = concatMap (encode' . unpack) (splitN 2 bs)
where encode' b@[c1, c2] = let c = chr (read ("0x" ++ b))
nonSpecialChars = ['A'..'Z'] ++ ['a'..'z'] ++ ['0'..'9'] ++ "-_.~"
-infoHash :: Map BVal BVal -> ByteString
-infoHash m = let info = m ! Bstr (pack "info")
- in (hash . pack . encode) info
-
-prepareRequest :: InfoDict -> String -> Integer -> String
-prepareRequest d peer_id len =
- let p = [("info_hash", urlEncodeHash ((B16.encode . infoHash) d)),
- ("peer_id", urlEncode peer_id),
- ("port", "6881"),
- ("uploaded", "0"),
- ("downloaded", "0"),
- ("left", show len),
- ("compact", "1"),
- ("event", "started")]
- in intercalate "&" [f ++ "=" ++ s | (f,s) <- p]
-
-connect :: Url -> String -> IO ByteString
-connect baseurl qstr = simpleHTTP (defaultGETRequest_ url) >>= getResponseBody
- where url = fromJust . parseURI $ (baseurl ++ "?" ++ qstr)
+-- | Make arguments that should be posted to tracker.
+-- This is a separate pure function for testability.
+mkArgs :: String -> Metainfo -> [(String, ByteString)]
+mkArgs peer_id m = [("info_hash", pack . urlEncodeHash . B16.encode . infoHash $ m),
+ ("peer_id", pack . urlEncode $ peer_id),
+ ("port", "6881"),
+ ("uploaded", "0"),
+ ("downloaded", "0"),
+ ("left", pack . show . lengthInBytes $ info m),
+ ("compact", "1"),
+ ("event", "started")]
+
+