metainfo/metainfo.go

   1 package metainfo
   2
   3 import (
   4         "crypto/sha1"
   5         "errors"
   6         "github.com/nsf/libtorgo/bencode"
   7         "io"
   8         "os"
   9         "time"
  10 )
  11
  12 // Information specific to a single file inside the MetaInfo structure..
  13 type FileInfo struct {
  14         Length int64    `bencode:"length"`
  15         Path   []string `bencode:"path"`
  16 }
  17
  18 // MetaInfo is the type you should use when reading torrent files. See Load and
  19 // LoadFromFile functions. All the fields are intended to be read-only. If
  20 // 'len(Files) == 1', then the FileInfo.Path is nil in that entry.
  21 type MetaInfo struct {
  22         Info
  23         InfoHash     []byte
  24         AnnounceList [][]string
  25         CreationDate time.Time
  26         Comment      string
  27         CreatedBy    string
  28         Encoding     string
  29         WebSeedURLs  []string
  30         InfoBytes    []byte
  31 }
  32
  33 // Load a MetaInfo from an io.Reader. Returns a non-nil error in case of
  34 // failure.
  35 func Load(r io.Reader) (*MetaInfo, error) {
  36         var mi MetaInfo
  37         var data torrent_data
  38         d := bencode.NewDecoder(r)
  39         err := d.Decode(&data)
  40         if err != nil {
  41                 return nil, err
  42         }
  43
  44         mi.Info = data.Info.Info
  45         mi.InfoBytes = data.Info.Bytes
  46         mi.InfoHash = data.Info.Hash
  47         if len(data.AnnounceList) > 0 {
  48                 mi.AnnounceList = data.AnnounceList
  49         } else {
  50                 mi.AnnounceList = [][]string{[]string{data.Announce}}
  51         }
  52         mi.CreationDate = time.Unix(data.CreationDate, 0)
  53         mi.Comment = data.Comment
  54         mi.CreatedBy = data.CreatedBy
  55         mi.Encoding = data.Encoding
  56         if data.URLList != nil {
  57                 switch v := data.URLList.(type) {
  58                 case string:
  59                         mi.WebSeedURLs = []string{v}
  60                 case []interface{}:
  61                         var ok bool
  62                         ss := make([]string, len(v))
  63                         for i, s := range v {
  64                                 ss[i], ok = s.(string)
  65                                 if !ok {
  66                                         return nil, errors.New("bad url-list data type")
  67                                 }
  68                         }
  69                         mi.WebSeedURLs = ss
  70                 default:
  71                         return nil, errors.New("bad url-list data type")
  72                 }
  73         }
  74         return &mi, nil
  75 }
  76
  77 // Convenience function for loading a MetaInfo from a file.
  78 func LoadFromFile(filename string) (*MetaInfo, error) {
  79         f, err := os.Open(filename)
  80         if err != nil {
  81                 return nil, err
  82         }
  83         defer f.Close()
  84         return Load(f)
  85 }
  86
  87 type Info struct {
  88         PieceLength int64      `bencode:"piece length"`
  89         Pieces      []byte     `bencode:"pieces"`
  90         Name        string     `bencode:"name"`
  91         Length      int64      `bencode:"length,omitempty"`
  92         Private     bool       `bencode:"private,omitempty"`
  93         Files       []FileInfo `bencode:"files,omitempty"`
  94 }
  95
  96 //----------------------------------------------------------------------------
  97 // unmarshal structures
  98 //----------------------------------------------------------------------------
  99
 100 type torrent_info_ex struct {
 101         Info
 102         Hash  []byte
 103         Bytes []byte
 104 }
 105
 106 func (this *torrent_info_ex) UnmarshalBencode(data []byte) error {
 107         this.Bytes = make([]byte, 0, len(data))
 108         this.Bytes = append(this.Bytes, data...)
 109         h := sha1.New()
 110         h.Write(this.Bytes)
 111         this.Hash = h.Sum(this.Hash)
 112         return bencode.Unmarshal(data, &this.Info)
 113 }
 114
 115 func (this *torrent_info_ex) MarshalBencode() ([]byte, error) {
 116         return bencode.Marshal(&this.Info)
 117 }
 118
 119 type torrent_data struct {
 120         Info         torrent_info_ex `bencode:"info"`
 121         Announce     string          `bencode:"announce"`
 122         AnnounceList [][]string      `bencode:"announce-list,omitempty"`
 123         CreationDate int64           `bencode:"creation date,omitempty"`
 124         Comment      string          `bencode:"comment,omitempty"`
 125         CreatedBy    string          `bencode:"created by,omitempty"`
 126         Encoding     string          `bencode:"encoding,omitempty"`
 127         URLList      interface{}     `bencode:"url-list,omitempty"`
 128 }