130 lines
3.4 KiB
Go
130 lines
3.4 KiB
Go
package torrent
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import (
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"crypto/sha1"
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)
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// https://wiki.theory.org/BitTorrentSpecification#Metainfo_File_Structure
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type File struct {
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// URL of a main tracker
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Announce string `bencode:"announce"`
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// List of additional trackers
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AnnounceList []string `bencode:"announce-list"`
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// Epoch of the creation of this torrent
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CreationDate int64 `bencode:"creation date,omitempty"`
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// Dictionary about this torrent, including files to be tracked
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Info InfoSection `bencode:"info,omitempty"`
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// free-form textual comments of the author
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Comment string `bencode:"comment,omitempty"`
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// name and version of the program used to create the .torrent
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CreatedBy string `bencode:"created by,omitempty"`
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// string encoding used to generate the `pieces` and `info` fields
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Encoding string `bencode:"encoding"`
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}
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type InfoSection struct {
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// suggested file/directory name where the file(s) are to be saved
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Name string `bencode:"name,omitempty"`
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// hash list of joined SHA1 sums (160-bit length)
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Pieces string `bencode:"pieces"`
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// number of bytes per piece
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PieceLength int64 `bencode:"piece length"`
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// size of the file in bytes (only if this torrent is for a single file)
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Length int64 `bencode:"length,omitempty"`
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// 32-char hexadecimal string corresponding to the MD5 sum of the file (only if this torrent is for a single file)
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MD5 string `bencode:"md5sum,omitempty"`
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// list of information about the files
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Files []FileInfo `bencode:"files"`
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}
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func (is InfoSection) PiecesList() []string {
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pieces := []string{}
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for i := 0; i < (len(is.Pieces) / sha1.Size); i++ {
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pieces = append(pieces, is.Pieces[i*sha1.Size:(i+1)*sha1.Size])
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}
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return pieces
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}
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type FileInfo struct {
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// size of file in bytes
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Length int64 `bencode:"length"`
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// list of strings corresponding to subdirectory names, the last of which is the actual file name
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Path []string `bencode:"path"`
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// 32-char hexadecimal string corresponding to the MD5 sum of the file (only if this torrent is for a single file)
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MD5 string `bencode:"md5sum,omitempty"`
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}
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type torrentError struct {
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Msg string
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}
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func (te torrentError) Error() string {
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return te.Msg
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}
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var (
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ErrNotProperDataInterface = torrentError{"data does not look like map[string]interface{}"}
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)
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func DecocdeTorrentData(data interface{}) (*File, error) {
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m, ok := data.(map[string]interface{})
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if !ok {
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return nil, ErrNotProperDataInterface
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}
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announce := m["announce"].(string)
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creationDate := m["creation date"].(int64)
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info := m["info"].(map[string]interface{})
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pieceLength := info["piece length"].(int64)
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pieces := info["pieces"].(string)
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infoName := info["name"].(string)
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isSingleFileTorrent := true
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infoFiles, ok := info["files"].([]interface{})
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if ok {
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isSingleFileTorrent = false
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}
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infoLength := int64(0)
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if isSingleFileTorrent {
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infoLength = info["length"].(int64)
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}
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files := []FileInfo{}
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if !isSingleFileTorrent {
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for _, fileInterface := range infoFiles {
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fileInfo := fileInterface.(map[string]interface{})
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paths := []string{}
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for _, path := range fileInfo["path"].([]interface{}) {
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paths = append(paths, path.(string))
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}
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files = append(files, FileInfo{
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Length: fileInfo["length"].(int64),
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Path: paths,
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})
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}
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}
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return &File{
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Announce: announce,
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CreationDate: creationDate,
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Info: InfoSection{
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Name: infoName,
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Length: infoLength,
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Pieces: pieces,
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PieceLength: pieceLength,
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Files: files,
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},
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}, nil
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}
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