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 DuplicateRecordFields #-}
  21
  22 module FuncTorrent.Metainfo
  23     (Info(..)
  24     , Metainfo(..)
  25     , FileInfo(..)
  26     , torrentToMetainfo
  27     ) where
  28
  29 import Prelude hiding (lookup)
  30 import Data.ByteString.Char8 (ByteString, unpack)
  31 import Data.Map as M ((!), lookup)
  32 import Data.List (intercalate)
  33 import Crypto.Hash.SHA1 (hash)
  34 import Data.Maybe (maybeToList)
  35
  36 import FuncTorrent.Bencode (BVal(..), encode, decode, bstrToString, bValToInteger)
  37
  38 -- only single file mode supported for the time being.
  39 data Info = Info { pieceLength :: !Integer
  40                  , pieces :: !ByteString
  41                  , private :: !(Maybe Integer)
  42                  , files :: ![FileInfo]
  43                  } deriving (Eq, Show)
  44
  45 data FileInfo = FileInfo { lengthInBytes :: Integer
  46                          , md5sum :: Maybe String
  47                          , path :: String
  48                          } deriving (Eq, Show)
  49
  50 data Metainfo = Metainfo { info :: !Info
  51                          , announceList :: ![String]
  52                          , creationDate :: !(Maybe Integer)
  53                          , comment :: !(Maybe String)
  54                          , createdBy :: !(Maybe String)
  55                          , encoding :: !(Maybe String)
  56                          , infoHash :: !ByteString
  57                          } deriving (Eq, Show)
  58
  59 mkPath :: String -> [BVal] -> String
  60 mkPath base xs = base ++ "/" ++ (intercalate "/" $ map (\b -> let (Just s) = bstrToString b in s) xs)
  61
  62 mkInfo :: BVal -> Maybe Info
  63 mkInfo (Bdict m) = let (Bint pieceLength') = m ! "piece length"
  64                        (Bstr pieces') = m ! "pieces"
  65                        private' = Nothing
  66                        bdictfiles = lookup "files" m
  67                    in
  68                      case bdictfiles of
  69                        Just fs -> let (Blist files') = fs
  70                                       (Bstr name') = m ! "name"
  71                                       dname' = unpack name'
  72                                   in
  73                                     Just Info { pieceLength = pieceLength'
  74                                               , pieces = pieces'
  75                                               , private = private'
  76                                               , files =
  77                                                   map (\(Bdict f) ->
  78                                                         let (Just len') = bValToInteger (f ! "length")
  79                                                             (Blist ds) = f ! "path"
  80                                                             path' = mkPath dname' ds
  81                                                         in
  82                                                           FileInfo { lengthInBytes = len',
  83                                                                      md5sum = Nothing,
  84                                                                      path = path'
  85                                                                    })
  86                                                   files' }
  87                        Nothing -> let (Bstr name') = m ! "name"
  88                                       (Bint length') = m ! "length"
  89                                       md5sum' = Nothing
  90                                   in
  91                                     Just Info { pieceLength = pieceLength'
  92                                               , pieces = pieces'
  93                                               , private = private'
  94                                               , files = [ FileInfo {
  95                                                             path = unpack name',
  96                                                             lengthInBytes = length',
  97                                                             md5sum = md5sum'
  98                                                             }
  99                                                         ]
 100                                               }
 101
 102 mkInfo _ = Nothing
 103
 104 mkMetaInfo :: BVal   -> Either String Metainfo
 105 mkMetaInfo (Bdict m)  =
 106     let (Just info')  = mkInfo $ m ! "info"
 107         announce'     = lookup "announce" m
 108         announceList' = lookup "announce-list" m
 109         creationDate' = lookup "creation date" m
 110         comment'      = lookup "comment" m
 111         createdBy'    = lookup "created by" m
 112         encoding'     = lookup "encoding" m
 113     in Right Metainfo {
 114                info         = info'
 115              , announceList = maybeToList (announce' >>= bstrToString)
 116                               ++ getAnnounceList announceList'
 117              , creationDate = bValToInteger =<< creationDate'
 118              , comment      = bstrToString  =<< comment'
 119              , createdBy    = bstrToString  =<< createdBy'
 120              , encoding     = bstrToString  =<< encoding'
 121              , infoHash     = hash . encode $ (m ! "info")
 122              }
 123 mkMetaInfo _ = Left "mkMetaInfo: expect an input dict"
 124
 125 getAnnounceList :: Maybe BVal -> [String]
 126 getAnnounceList Nothing          = []
 127 getAnnounceList (Just (Bint _))  = []
 128 getAnnounceList (Just (Bstr _))  = []
 129 getAnnounceList (Just (Blist l)) = map (\s -> case s of
 130                                                (Bstr s') ->  unpack s'
 131                                                (Blist s') -> case s' of
 132                                                               [Bstr s''] -> unpack s''
 133                                                               _ -> ""
 134                                                _ -> "") l
 135 getAnnounceList (Just (Bdict _)) = []
 136
 137 torrentToMetainfo :: ByteString -> Either String Metainfo
 138 torrentToMetainfo s =
 139   case decode s of
 140    Right d -> mkMetaInfo d
 141    Left e -> Left $ show e