package main import ( "bytes" "crypto/sha1" "fmt" "io" "net/http" "os" "path" "time" "github.com/zeebo/bencode" "github.com/zenazn/goji/web" ) const ( TORRENT_PIECE_LENGTH = 262144 ) type TorrentInfo struct { PieceLength int `bencode:"piece length"` Pieces string `bencode:"pieces"` Name string `bencode:"name"` Length int `bencode:"length"` } type Torrent struct { Encoding string `bencode:"encoding"` Info TorrentInfo `bencode:"info"` UrlList []string `bencode:"url-list"` } func hashPiece(piece []byte) []byte { h := sha1.New() h.Write(piece) return h.Sum(nil) } func createTorrent(fileName string, filePath string) ([]byte, error) { chunk := make([]byte, TORRENT_PIECE_LENGTH) torrent := Torrent{ Encoding: "UTF-8", Info: TorrentInfo{ PieceLength: TORRENT_PIECE_LENGTH, Name: fileName, }, UrlList: []string{fmt.Sprintf("%sselif/%s", Config.siteURL, fileName)}, } f, err := os.Open(filePath) if err != nil { return []byte{}, err } for { n, err := f.Read(chunk) if err == io.EOF { break } else if err != nil { return []byte{}, err } torrent.Info.Length += n torrent.Info.Pieces += string(hashPiece(chunk[:n])) } f.Close() data, err := bencode.EncodeBytes(&torrent) if err != nil { return []byte{}, err } return data, nil } func fileTorrentHandler(c web.C, w http.ResponseWriter, r *http.Request) { fileName := c.URLParams["name"] filePath := path.Join(Config.filesDir, fileName) if !fileExistsAndNotExpired(fileName) { notFoundHandler(c, w, r) return } encoded, err := createTorrent(fileName, filePath) if err != nil { oopsHandler(c, w, r) // 500 - creating torrent failed return } w.Header().Set(`Content-Disposition`, fmt.Sprintf(`attachment; filename="%s.torrent"`, fileName)) http.ServeContent(w, r, "", time.Now(), bytes.NewReader(encoded)) } // vim:set ts=8 sw=8 noet: