src/FuncTorrent/Metainfo.hs

   1 module FuncTorrent.Metainfo
   2     (Info(..),
   3      Metainfo(..),
   4      infoHash,
   5      mkInfo,
   6      mkMetaInfo
   7     ) where
   8
   9 import Prelude hiding (lookup)
  10 import Data.ByteString.Char8 (ByteString, unpack)
  11 import Data.Map as M ((!), lookup)
  12 import Crypto.Hash.SHA1 (hash)
  13 import Data.Maybe (maybeToList)
  14
  15 import FuncTorrent.Bencode (BVal(..), InfoDict, encode, bstrToString)
  16
  17 -- only single file mode supported for the time being.
  18 data Info = Info { pieceLength :: !Integer
  19                  , pieces :: !ByteString
  20                  , private :: !(Maybe Integer)
  21                  , name :: !String
  22                  , lengthInBytes :: !Integer
  23                  , md5sum :: !(Maybe String)
  24                  } deriving (Eq, Show)
  25
  26 data Metainfo = Metainfo { info :: !Info
  27                          , announceList :: ![String]
  28                          , creationDate :: !(Maybe String)
  29                          , comment :: !(Maybe String)
  30                          , createdBy :: !(Maybe String)
  31                          , encoding :: !(Maybe String)
  32                          } deriving (Eq, Show)
  33
  34 mkInfo :: BVal -> Maybe Info
  35 mkInfo (Bdict m) = let (Bint pieceLength') = m ! "piece length"
  36                        (Bstr pieces') = m ! "pieces"
  37                        private' = Nothing
  38                        (Bstr name') = m ! "name"
  39                        (Bint length') = m ! "length"
  40                        md5sum' = Nothing
  41                    in Just Info { pieceLength = pieceLength'
  42                                 , pieces = pieces'
  43                                 , private = private'
  44                                 , name = unpack name'
  45                                 , lengthInBytes = length'
  46                                 , md5sum = md5sum'}
  47 mkInfo _ = Nothing
  48
  49 maybeBstrToString :: Maybe BVal -> Maybe String
  50 maybeBstrToString (Just (Bstr bs)) = Just $ unpack bs
  51 maybeBstrToString _ = Nothing
  52
  53 mkMetaInfo :: BVal -> Maybe Metainfo
  54 mkMetaInfo (Bdict m) = let (Just info') = mkInfo $ m ! "info"
  55                            announce' = lookup "announce" m
  56                            announceList' = lookup "announce-list" m
  57                            -- creationDate = lookup (Bstr (pack "creation date")) m
  58                            creationDate' = Nothing
  59                            comment' = lookup "comment" m
  60                            createdBy' = lookup "created by" m
  61                            encoding' = lookup "encoding" m
  62                        in Just Metainfo { info = info'
  63                                         , announceList = maybeToList (announce' >>= bstrToString)
  64                                                          ++ getAnnounceList announceList'
  65                                         , creationDate = creationDate'
  66                                         , comment = maybeBstrToString comment'
  67                                         , createdBy = maybeBstrToString createdBy'
  68                                         , encoding = maybeBstrToString encoding'
  69                                         }
  70 mkMetaInfo _ = Nothing
  71
  72 getAnnounceList :: Maybe BVal -> [String]
  73 getAnnounceList Nothing = []
  74 getAnnounceList (Just (Bint _)) = []
  75 getAnnounceList (Just (Bstr _)) = []
  76 getAnnounceList (Just (Blist l)) = map (\s -> case s of
  77                                                (Bstr s') ->  unpack s'
  78                                                (Blist s') -> case s' of
  79                                                               [Bstr s''] -> unpack s''
  80                                                               _ -> ""
  81                                                _ -> "") l
  82
  83 getAnnounceList (Just (Bdict _)) = []
  84
  85 -- | Info hash is urlencoded 20 byte SHA1 hash of the value of the info key from
  86 -- the Metainfo file. Note that the value will be a bencoded dictionary, given
  87 -- the definition of the info key above. TODO: `Metainfo -> ByteString`
  88 infoHash :: InfoDict -> ByteString
  89 infoHash m = hash . encode $ (m ! "info")