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 m) = let (Bint pieceLength') = m ! "piece length"
  59                            (Bstr pieces') = m ! "pieces"
  60                            private' = Nothing
  61                            (Bstr name') = m ! "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" m
  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') = m ! "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 bvalToInfo _ = Nothing
  82
  83 toFileMeta :: BVal -> Maybe FileMeta
  84 toFileMeta (Bdict fm) = let (Bint length) = fm ! "length"
  85                             (Blist pathElems) = fm ! "path"
  86                             pathStrings = fmap bstrToString pathElems
  87                         in
  88                           sequence pathStrings >>=
  89                           \pathList -> let path' = concat $ intersperse "/" pathList
  90                                        in Just (FileMeta { lengthInBytes = length
  91                                                          , md5sum = Nothing
  92                                                          , path = path' })
  93 toFileMeta _ = Nothing
  94
  95 mkMetaInfo :: BVal   -> Either String Metainfo
  96 mkMetaInfo (Bdict m)  =
  97     let info'         = bvalToInfo $ m ! "info"
  98         announce'     = lookup "announce" m
  99         announceList' = lookup "announce-list" m
 100         creationDate' = lookup "creation date" m
 101         comment'      = lookup "comment" m
 102         createdBy'    = lookup "created by" m
 103         encoding'     = lookup "encoding" m
 104     in Right Metainfo {
 105                info         = info'
 106              , announceList = maybeToList (announce' >>= bstrToString)
 107                               ++ getAnnounceList announceList'
 108              , creationDate = bValToInteger =<< creationDate'
 109              , comment      = bstrToString  =<< comment'
 110              , createdBy    = bstrToString  =<< createdBy'
 111              , encoding     = bstrToString  =<< encoding'
 112              , infoHash     = hash . encode $ (m ! "info")
 113              }
 114 mkMetaInfo _ = Left "mkMetaInfo: expect an input dict"
 115
 116 getAnnounceList :: Maybe BVal -> [String]
 117 getAnnounceList Nothing = []
 118 getAnnounceList (Just (Bint _)) = []
 119 getAnnounceList (Just (Bstr _)) = []
 120 getAnnounceList (Just (Blist l)) = map (\s -> case s of
 121                                                (Bstr s') ->  unpack s'
 122                                                (Blist s') -> case s' of
 123                                                               [Bstr s''] -> unpack s''
 124                                                               _ -> ""
 125                                                _ -> "") l
 126 getAnnounceList (Just (Bdict _)) = []
 127
 128 torrentToMetainfo :: ByteString -> Either String Metainfo
 129 torrentToMetainfo s =
 130   case decode s of
 131    Right d -> mkMetaInfo d
 132    Left e -> Left $ show e