126 lines
3.0 KiB
Go
126 lines
3.0 KiB
Go
package torrent
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import (
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"errors"
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"net"
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"github.com/anacrolix/torrent/metainfo"
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pp "github.com/anacrolix/torrent/peer_protocol"
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)
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type chunkSpec struct {
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Begin, Length pp.Integer
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}
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type request struct {
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Index pp.Integer
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chunkSpec
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}
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func (r request) ToMsg(mt pp.MessageType) pp.Message {
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return pp.Message{
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Type: mt,
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Index: r.Index,
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Begin: r.Begin,
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Length: r.Length,
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}
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}
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func newRequest(index, begin, length pp.Integer) request {
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return request{index, chunkSpec{begin, length}}
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}
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func newRequestFromMessage(msg *pp.Message) request {
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switch msg.Type {
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case pp.Request, pp.Cancel, pp.Reject:
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return newRequest(msg.Index, msg.Begin, msg.Length)
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case pp.Piece:
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return newRequest(msg.Index, msg.Begin, pp.Integer(len(msg.Piece)))
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default:
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panic(msg.Type)
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}
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}
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// The size in bytes of a metadata extension piece.
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func metadataPieceSize(totalSize int, piece int) int {
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ret := totalSize - piece*(1<<14)
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if ret > 1<<14 {
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ret = 1 << 14
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}
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return ret
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}
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// Return the request that would include the given offset into the torrent data.
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func torrentOffsetRequest(torrentLength, pieceSize, chunkSize, offset int64) (
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r request, ok bool) {
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if offset < 0 || offset >= torrentLength {
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return
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}
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r.Index = pp.Integer(offset / pieceSize)
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r.Begin = pp.Integer(offset % pieceSize / chunkSize * chunkSize)
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r.Length = pp.Integer(chunkSize)
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pieceLeft := pp.Integer(pieceSize - int64(r.Begin))
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if r.Length > pieceLeft {
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r.Length = pieceLeft
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}
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torrentLeft := torrentLength - int64(r.Index)*pieceSize - int64(r.Begin)
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if int64(r.Length) > torrentLeft {
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r.Length = pp.Integer(torrentLeft)
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}
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ok = true
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return
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}
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func torrentRequestOffset(torrentLength, pieceSize int64, r request) (off int64) {
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off = int64(r.Index)*pieceSize + int64(r.Begin)
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if off < 0 || off >= torrentLength {
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panic("invalid request")
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}
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return
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}
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func validateInfo(info *metainfo.Info) error {
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if len(info.Pieces)%20 != 0 {
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return errors.New("pieces has invalid length")
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}
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if info.PieceLength == 0 {
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if info.TotalLength() != 0 {
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return errors.New("zero piece length")
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}
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} else {
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if int((info.TotalLength()+info.PieceLength-1)/info.PieceLength) != info.NumPieces() {
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return errors.New("piece count and file lengths are at odds")
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}
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}
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return nil
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}
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func chunkIndexSpec(index int, pieceLength, chunkSize pp.Integer) chunkSpec {
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ret := chunkSpec{pp.Integer(index) * chunkSize, chunkSize}
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if ret.Begin+ret.Length > pieceLength {
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ret.Length = pieceLength - ret.Begin
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}
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return ret
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}
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func connLessTrusted(l, r *connection) bool {
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return l.netGoodPiecesDirtied() < r.netGoodPiecesDirtied()
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}
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// Convert a net.Addr to its compact IP representation. Either 4 or 16 bytes
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// per "yourip" field of http://www.bittorrent.org/beps/bep_0010.html.
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func addrCompactIP(addr net.Addr) (string, error) {
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host, _, err := net.SplitHostPort(addr.String())
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if err != nil {
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return "", err
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}
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ip := net.ParseIP(host)
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if v4 := ip.To4(); v4 != nil {
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if len(v4) != 4 {
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panic(v4)
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}
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return string(v4), nil
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}
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return string(ip.To16()), nil
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}
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