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 Integer)
  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 maybeBstrToInteger :: Maybe BVal -> Maybe Integer
  54 maybeBstrToInteger (Just (Bint bs)) = Just  bs
  55 maybeBstrToInteger _ = Nothing
  56
  57 mkMetaInfo :: BVal -> Maybe Metainfo
  58 mkMetaInfo (Bdict m) = let (Just info') = mkInfo $ m ! "info"
  59                            announce' = lookup "announce" m
  60                            announceList' = lookup "announce-list" m
  61                            creationDate' = lookup "creation date" m
  62                            comment' = lookup "comment" m
  63                            createdBy' = lookup "created by" m
  64                            encoding' = lookup "encoding" m
  65                        in Just Metainfo { info = info'
  66                                         , announceList = maybeToList (announce' >>= bstrToString)
  67                                                          ++ getAnnounceList announceList'
  68                                         , creationDate = maybeBstrToInteger creationDate'
  69                                         , comment = maybeBstrToString comment'
  70                                         , createdBy = maybeBstrToString createdBy'
  71                                         , encoding = maybeBstrToString encoding'
  72                                         }
  73 mkMetaInfo _ = Nothing
  74
  75 getAnnounceList :: Maybe BVal -> [String]
  76 getAnnounceList Nothing = []
  77 getAnnounceList (Just (Bint _)) = []
  78 getAnnounceList (Just (Bstr _)) = []
  79 getAnnounceList (Just (Blist l)) = map (\s -> case s of
  80                                                (Bstr s') ->  unpack s'
  81                                                (Blist s') -> case s' of
  82                                                               [Bstr s''] -> unpack s''
  83                                                               _ -> ""
  84                                                _ -> "") l
  85
  86 getAnnounceList (Just (Bdict _)) = []
  87
  88 -- | Info hash is urlencoded 20 byte SHA1 hash of the value of the info key from
  89 -- the Metainfo file. Note that the value will be a bencoded dictionary, given
  90 -- the definition of the info key above. TODO: `Metainfo -> ByteString`
  91 infoHash :: InfoDict -> ByteString
  92 infoHash m = hash . encode $ (m ! "info")