src/FuncTorrent/Metainfo.hs

   1 {-
   2  - Copyright (C) 2015-2016 Ramakrishnan Muthukrishnan <ram@rkrishnan.org>
   3  -
   4  - This file is part of FuncTorrent.
   5  -
   6  - FuncTorrent is free software; you can redistribute it and/or modify
   7  - it under the terms of the GNU General Public License as published by
   8  - the Free Software Foundation; either version 3 of the License, or
   9  - (at your option) any later version.
  10  -
  11  - FuncTorrent is distributed in the hope that it will be useful,
  12  - but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  - GNU General Public License for more details.
  15  -
  16  - You should have received a copy of the GNU General Public License
  17  - along with FuncTorrent; if not,  see <http://www.gnu.org/licenses/>
  18  -}
  19
  20 {-# LANGUAGE OverloadedStrings #-}
  21 module FuncTorrent.Metainfo
  22     (Info(..),
  23      Metainfo(..),
  24      torrentToMetainfo
  25     ) where
  26
  27 import Prelude hiding (lookup)
  28 import Data.ByteString.Char8 (ByteString, unpack)
  29 import Data.Map as M ((!), lookup)
  30 import Data.List (intersperse)
  31 import Crypto.Hash.SHA1 (hash)
  32 import Data.Maybe (maybeToList)
  33
  34 import FuncTorrent.Bencode (BVal(..), encode, decode, bstrToString, bValToInteger)
  35
  36 data FileMeta = FileMeta { lengthInBytes :: !Integer
  37                          , md5sum :: !(Maybe String)
  38                          , path :: String
  39                          } deriving (Eq, Show)
  40
  41 data Info = Info { pieceLength :: !Integer
  42                  , pieces :: !ByteString
  43                  , private :: !(Maybe Integer)
  44                  , name :: !String
  45                  , filemeta :: [FileMeta]
  46                  } deriving (Eq, Show)
  47
  48 data Metainfo = Metainfo { info :: !(Maybe Info)
  49                          , announceList :: ![String]
  50                          , creationDate :: !(Maybe Integer)
  51                          , comment :: !(Maybe String)
  52                          , createdBy :: !(Maybe String)
  53                          , encoding :: !(Maybe String)
  54                          , infoHash :: !ByteString
  55                          } deriving (Eq, Show)
  56
  57 bvalToInfo :: BVal -> Maybe Info
  58 bvalToInfo (Bdict minfo) = let (Bint pieceLength') = minfo ! "piece length"
  59                                (Bstr pieces') = minfo ! "pieces"
  60                                private' = Nothing
  61                                (Bstr name') = minfo ! "name"
  62                                -- is the key "files" present? If so, it is a multi-file torrent
  63                                -- if not, it is a single file torrent.
  64                                filesIfMulti = lookup "files" minfo
  65                                partialInfo = Info { pieceLength = pieceLength'
  66                                                   , pieces = pieces'
  67                                                   , private = private'
  68                                                   , name = unpack name'
  69                                                   , filemeta = []
  70                                                   }
  71                            in
  72                              case filesIfMulti of
  73                                Nothing -> let (Bint length') = minfo ! "length"
  74                                               filemeta' = FileMeta { lengthInBytes = length'
  75                                                                    , md5sum = Nothing
  76                                                                    , path = unpack name' }
  77                                           in Just (partialInfo { filemeta = [filemeta'] })
  78                                Just (Blist files) -> mapM toFileMeta files >>=
  79                                                      \filemeta' ->
  80                                                        Just partialInfo { filemeta = filemeta' }
  81                                Just _ -> Nothing
  82 bvalToInfo _ = Nothing
  83
  84 toFileMeta :: BVal -> Maybe FileMeta
  85 toFileMeta (Bdict fm) = let (Bint length') = fm ! "length"
  86                             (Blist pathElems) = fm ! "path"
  87                             pathStrings = fmap bstrToString pathElems
  88                         in
  89                           sequence pathStrings >>=
  90                           \pathList -> let path' = concat $ intersperse "/" pathList
  91                                        in Just (FileMeta { lengthInBytes = length'
  92                                                          , md5sum = Nothing
  93                                                          , path = path' })
  94 toFileMeta _ = Nothing
  95
  96 mkMetaInfo :: BVal   -> Either String Metainfo
  97 mkMetaInfo (Bdict minfo)  =
  98     let info'         = bvalToInfo $ minfo ! "info"
  99         announce'     = lookup "announce" minfo
 100         announceList' = lookup "announce-list" minfo
 101         creationDate' = lookup "creation date" minfo
 102         comment'      = lookup "comment" minfo
 103         createdBy'    = lookup "created by" minfo
 104         encoding'     = lookup "encoding" minfo
 105     in Right Metainfo {
 106                info         = info'
 107              , announceList = maybeToList (announce' >>= bstrToString)
 108                               ++ getAnnounceList announceList'
 109              , creationDate = bValToInteger =<< creationDate'
 110              , comment      = bstrToString  =<< comment'
 111              , createdBy    = bstrToString  =<< createdBy'
 112              , encoding     = bstrToString  =<< encoding'
 113              , infoHash     = hash . encode $ (minfo ! "info")
 114              }
 115 mkMetaInfo _ = Left "mkMetaInfo: expect an input dict"
 116
 117 getAnnounceList :: Maybe BVal -> [String]
 118 getAnnounceList Nothing = []
 119 getAnnounceList (Just (Bint _)) = []
 120 getAnnounceList (Just (Bstr _)) = []
 121 getAnnounceList (Just (Blist l)) = map (\s -> case s of
 122                                                (Bstr s') ->  unpack s'
 123                                                (Blist s') -> case s' of
 124                                                               [Bstr s''] -> unpack s''
 125                                                               _ -> ""
 126                                                _ -> "") l
 127 getAnnounceList (Just (Bdict _)) = []
 128
 129 torrentToMetainfo :: ByteString -> Either String Metainfo
 130 torrentToMetainfo s =
 131   case decode s of
 132     Right d -> mkMetaInfo d
 133     Left e -> Left ("Cannot parse the torrent file: " ++ show e)
 134