package torrent import ( "errors" "github.com/anacrolix/torrent/metainfo" pp "github.com/anacrolix/torrent/peer_protocol" ) type chunkSpec struct { Begin, Length pp.Integer } type request struct { Index pp.Integer chunkSpec } func newRequest(index, begin, length pp.Integer) request { return request{index, chunkSpec{begin, length}} } // The size in bytes of a metadata extension piece. func metadataPieceSize(totalSize int, piece int) int { ret := totalSize - piece*(1<<14) if ret > 1<<14 { ret = 1 << 14 } return ret } // Return the request that would include the given offset into the torrent data. func torrentOffsetRequest(torrentLength, pieceSize, chunkSize, offset int64) ( r request, ok bool) { if offset < 0 || offset >= torrentLength { return } r.Index = pp.Integer(offset / pieceSize) r.Begin = pp.Integer(offset % pieceSize / chunkSize * chunkSize) r.Length = pp.Integer(chunkSize) pieceLeft := pp.Integer(pieceSize - int64(r.Begin)) if r.Length > pieceLeft { r.Length = pieceLeft } torrentLeft := torrentLength - int64(r.Index)*pieceSize - int64(r.Begin) if int64(r.Length) > torrentLeft { r.Length = pp.Integer(torrentLeft) } ok = true return } func torrentRequestOffset(torrentLength, pieceSize int64, r request) (off int64) { off = int64(r.Index)*pieceSize + int64(r.Begin) if off < 0 || off >= torrentLength { panic("invalid request") } return } func validateInfo(info *metainfo.Info) error { if len(info.Pieces)%20 != 0 { return errors.New("pieces has invalid length") } if info.PieceLength == 0 { if info.TotalLength() != 0 { return errors.New("zero piece length") } } else { if int((info.TotalLength()+info.PieceLength-1)/info.PieceLength) != info.NumPieces() { return errors.New("piece count and file lengths are at odds") } } return nil } func chunkIndexSpec(index int, pieceLength, chunkSize pp.Integer) chunkSpec { ret := chunkSpec{pp.Integer(index) * chunkSize, chunkSize} if ret.Begin+ret.Length > pieceLength { ret.Length = pieceLength - ret.Begin } return ret } func connLessTrusted(l, r *connection) bool { return l.netGoodPiecesDirtied() < r.netGoodPiecesDirtied() }