package torrent import ( "crypto" "errors" "fmt" "time" "github.com/anacrolix/torrent/peer_protocol" ) const ( pieceHash = crypto.SHA1 maxRequests = 250 // Maximum pending requests we allow peers to send us. chunkSize = 0x4000 // 16KiB bep20 = "-GT0000-" // Peer ID client identifier prefix nominalDialTimeout = time.Second * 30 minDialTimeout = 5 * time.Second ) type ( InfoHash [20]byte pieceSum [20]byte ) func (ih *InfoHash) AsString() string { return string(ih[:]) } func (ih *InfoHash) HexString() string { return fmt.Sprintf("%x", ih[:]) } func lastChunkSpec(pieceLength peer_protocol.Integer) (cs chunkSpec) { cs.Begin = (pieceLength - 1) / chunkSize * chunkSize cs.Length = pieceLength - cs.Begin return } type chunkSpec struct { Begin, Length peer_protocol.Integer } type request struct { Index peer_protocol.Integer chunkSpec } func newRequest(index, begin, length peer_protocol.Integer) request { return request{index, chunkSpec{begin, length}} } var ( // Requested data not yet available. errDataNotReady = errors.New("data not ready") ) // 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 } type superer interface { Super() interface{} } // Returns ok if there's a parent, and it's not nil. func super(child interface{}) (parent interface{}, ok bool) { s, ok := child.(superer) if !ok { return } parent = s.Super() ok = parent != nil return }