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|
-- |
-- Copyright : (c) Sam Truzjan 2013
-- License : BSD3
-- Maintainer : pxqr.sta@gmail.com
-- Stability : provisional
-- Portability : portable
--
-- Infohash is a unique identifier of torrent.
--
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE DeriveDataTypeable #-}
module Data.Torrent.InfoHash
( InfoHash
-- * Parsing
, textToInfoHash
-- * Rendering
, longHex
, shortHex
) where
import Control.Applicative
import Control.Monad
import Data.Aeson
import Data.BEncode
import Data.ByteString as BS
import Data.ByteString.Char8 as BC
import Data.ByteString.Base16 as Base16
import Data.ByteString.Base32 as Base32
import Data.ByteString.Base64 as Base64
import Data.Char
import Data.Convertible.Base
import Data.Default
import Data.List as L
import Data.Hashable as Hashable
import Data.Serialize
import Data.String
import Data.Text as T
import Data.Text.Encoding as T
import Data.Typeable
import Network.HTTP.Types.QueryLike
import Text.ParserCombinators.ReadP as P
import Text.PrettyPrint
import Text.PrettyPrint.Class
-- TODO
--
-- data Word160 = Word160 {-# UNPACK #-} !Word64
-- {-# UNPACK #-} !Word64
-- {-# UNPACK #-} !Word32
--
-- newtype InfoHash = InfoHash Word160
--
-- reason: bytestring have overhead = 8 words, while infohash have length 20 bytes
-- | Exactly 20 bytes long SHA1 hash of the info part of torrent file.
newtype InfoHash = InfoHash { getInfoHash :: BS.ByteString }
deriving (Eq, Ord, Typeable)
infoHashLen :: Int
infoHashLen = 20
-- | Meaningless placeholder value.
instance Default InfoHash where
def = "0123456789012345678901234567890123456789"
-- | Hash raw bytes. (no encoding)
instance Hashable InfoHash where
hash (InfoHash ih) = Hashable.hash ih
{-# INLINE hash #-}
-- | Convert to\/from raw bencoded string. (no encoding)
instance BEncode InfoHash where
toBEncode = toBEncode . getInfoHash
fromBEncode be = InfoHash <$> fromBEncode be
-- | Convert to\/from raw bytestring. (no encoding)
instance Serialize InfoHash where
put (InfoHash ih) = putByteString ih
{-# INLINE put #-}
get = InfoHash <$> getBytes infoHashLen
{-# INLINE get #-}
-- | Convert to raw query value. (no encoding)
instance QueryValueLike InfoHash where
toQueryValue (InfoHash ih) = Just ih
{-# INLINE toQueryValue #-}
-- | Convert to base16 encoded string.
instance Show InfoHash where
show (InfoHash ih) = BC.unpack (Base16.encode ih)
-- | Convert to base16 encoded Doc string.
instance Pretty InfoHash where
pretty = text . show
-- | Read base16 encoded string.
instance Read InfoHash where
readsPrec _ = readP_to_S $ do
str <- replicateM (infoHashLen * 2) (satisfy isHexDigit)
return $ InfoHash $ decodeIH str
where
decodeIH = BS.pack . L.map fromHex . pair
fromHex (a, b) = read $ '0' : 'x' : a : b : []
pair (a : b : xs) = (a, b) : pair xs
pair _ = []
-- | Convert raw bytes to info hash.
instance Convertible BS.ByteString InfoHash where
safeConvert bs
| BS.length bs == infoHashLen = pure (InfoHash bs)
| otherwise = convError "invalid length" bs
-- | Parse infohash from base16\/base32\/base64 encoded string.
instance Convertible Text InfoHash where
safeConvert t
| 26 <= hashLen && hashLen <= 28 =
case Base64.decode hashStr of
Left msg -> convError ("invalid base64 encoding " ++ msg) t
Right ihStr -> safeConvert ihStr
| hashLen == 32 =
case Base32.decode hashStr of
Left msg -> convError msg t
Right ihStr -> safeConvert ihStr
| hashLen == 40 =
let (ihStr, inv) = Base16.decode hashStr
in if BS.length inv /= 0
then convError "invalid base16 encoding" t
else safeConvert ihStr
| otherwise = convError "invalid length" t
where
hashLen = BS.length hashStr
hashStr = T.encodeUtf8 t
-- | Decode from base16\/base32\/base64 encoded string.
instance IsString InfoHash where
fromString = either (error . prettyConvertError) id . safeConvert . T.pack
-- | Convert to base16 encoded JSON string.
instance ToJSON InfoHash where
toJSON (InfoHash ih) = String $ T.decodeUtf8 $ Base16.encode ih
-- | Convert from base16\/base32\/base64 encoded JSON string.
instance FromJSON InfoHash where
parseJSON = withText "InfoHash" $
either (fail . prettyConvertError) pure . safeConvert
ignoreErrorMsg :: Either a b -> Maybe b
ignoreErrorMsg = either (const Nothing) Just
-- | Tries both base16 and base32 while decoding info hash.
--
-- Use 'safeConvert' for detailed error messages.
--
textToInfoHash :: Text -> Maybe InfoHash
textToInfoHash = ignoreErrorMsg . safeConvert
-- | Hex encode infohash to text, full length.
longHex :: InfoHash -> Text
longHex = T.decodeUtf8 . Base16.encode . getInfoHash
-- | The same as 'longHex', but only first 7 characters.
shortHex :: InfoHash -> Text
shortHex = T.take 7 . longHex
|
