16 "github.com/anacrolix/log"
17 "github.com/anacrolix/missinggo"
18 "github.com/anacrolix/missinggo/iter"
19 "github.com/anacrolix/missinggo/v2/bitmap"
20 "github.com/anacrolix/missinggo/v2/prioritybitmap"
21 "github.com/anacrolix/multiless"
22 "github.com/anacrolix/torrent/metainfo"
24 "github.com/anacrolix/torrent/bencode"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
29 type PeerSource string
32 PeerSourceTracker = "Tr"
33 PeerSourceIncoming = "I"
34 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
35 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
37 // The peer was given directly, such as through a magnet link.
38 PeerSourceDirect = "M"
41 type peerRequestState struct {
45 type PeerRemoteAddr interface {
50 // First to ensure 64-bit alignment for atomics. See #262.
60 RemoteAddr PeerRemoteAddr
61 // True if the connection is operating over MSE obfuscation.
63 cryptoMethod mse.CryptoMethod
66 closed missinggo.Event
67 // Set true after we've added our ConnStats generated during handshake to
68 // other ConnStat instances as determined when the *Torrent became known.
69 reconciledHandshakeStats bool
71 lastMessageReceived time.Time
72 completedHandshake time.Time
73 lastUsefulChunkReceived time.Time
74 lastChunkSent time.Time
76 // Stuff controlled by the local peer.
78 lastBecameInterested time.Time
79 priorInterest time.Duration
81 lastStartedExpectingToReceiveChunks time.Time
82 cumulativeExpectedToReceiveChunks time.Duration
83 _chunksReceivedWhileExpecting int64
86 requests map[Request]struct{}
88 // Chunks that we might reasonably expect to receive from the peer. Due to
89 // latency, buffering, and implementation differences, we may receive
90 // chunks that are no longer in the set of requests actually want.
91 validReceiveChunks map[Request]int
92 // Indexed by metadata piece, set to true if posted and pending a
94 metadataRequests []bool
95 sentHaves bitmap.Bitmap
97 // Stuff controlled by the remote peer.
100 peerRequests map[Request]*peerRequestState
101 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
103 // The pieces the peer has claimed to have.
104 _peerPieces bitmap.Bitmap
105 // The peer has everything. This can occur due to a special message, when
106 // we may not even know the number of pieces in the torrent yet.
108 // The highest possible number of pieces the torrent could have based on
109 // communication with the peer. Generally only useful until we have the
111 peerMinPieces pieceIndex
112 // Pieces we've accepted chunks for from the peer.
113 peerTouchedPieces map[pieceIndex]struct{}
114 peerAllowedFast bitmap.Bitmap
116 PeerMaxRequests int // Maximum pending requests the peer allows.
117 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
118 PeerClientName string
120 pieceInclination []int
121 _pieceRequestOrder prioritybitmap.PriorityBitmap
126 // Maintains the state of a BitTorrent-protocol based connection with a peer.
127 type PeerConn struct {
130 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
131 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
136 PeerExtensionBytes pp.PeerExtensionBits
138 // The actual Conn, used for closing, and setting socket options.
140 // The Reader and Writer for this Conn, with hooks installed for stats,
141 // limiting, deadlines etc.
145 writeBuffer *bytes.Buffer
146 uploadTimer *time.Timer
152 func (cn *PeerConn) connStatusString() string {
153 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
156 func (cn *Peer) updateExpectingChunks() {
157 if cn.expectingChunks() {
158 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
159 cn.lastStartedExpectingToReceiveChunks = time.Now()
162 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
163 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
164 cn.lastStartedExpectingToReceiveChunks = time.Time{}
169 func (cn *Peer) expectingChunks() bool {
170 if len(cn.requests) == 0 {
176 for r := range cn.requests {
177 if !cn.remoteChokingPiece(r.Index.Int()) {
184 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
185 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
188 // Returns true if the connection is over IPv6.
189 func (cn *PeerConn) ipv6() bool {
194 return len(ip) == net.IPv6len
197 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
198 // specification for this.
199 func (cn *PeerConn) isPreferredDirection() bool {
200 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
203 // Returns whether the left connection should be preferred over the right one,
204 // considering only their networking properties. If ok is false, we can't
206 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
208 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
209 ml.NextBool(!l.utp(), !r.utp())
210 ml.NextBool(l.ipv6(), r.ipv6())
214 func (cn *Peer) cumInterest() time.Duration {
215 ret := cn.priorInterest
217 ret += time.Since(cn.lastBecameInterested)
222 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
223 if cn.peerSentHaveAll {
226 if !cn.t.haveInfo() {
229 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
232 func (cn *PeerConn) locker() *lockWithDeferreds {
233 return cn.t.cl.locker()
236 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
237 _, ok := cn.PeerExtensionIDs[ext]
241 // The best guess at number of pieces in the torrent for this peer.
242 func (cn *Peer) bestPeerNumPieces() pieceIndex {
244 return cn.t.numPieces()
246 return cn.peerMinPieces
249 func (cn *Peer) completedString() string {
250 have := pieceIndex(cn._peerPieces.Len())
251 if cn.peerSentHaveAll {
252 have = cn.bestPeerNumPieces()
254 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
257 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
258 cn.setNumPieces(info.NumPieces())
261 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
262 // receiving badly sized BITFIELD, or invalid HAVE messages.
263 func (cn *PeerConn) setNumPieces(num pieceIndex) {
264 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
265 cn.peerPiecesChanged()
268 func eventAgeString(t time.Time) string {
272 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
275 func (cn *PeerConn) connectionFlags() (ret string) {
277 ret += string([]byte{b})
279 if cn.cryptoMethod == mse.CryptoMethodRC4 {
281 } else if cn.headerEncrypted {
284 ret += string(cn.Discovery)
291 func (cn *PeerConn) utp() bool {
292 return parseNetworkString(cn.Network).Udp
295 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
296 func (cn *Peer) statusFlags() (ret string) {
298 ret += string([]byte{b})
307 ret += cn.connectionFlags()
309 if cn.peerInterested {
318 func (cn *Peer) downloadRate() float64 {
319 num := cn._stats.BytesReadUsefulData.Int64()
323 return float64(num) / cn.totalExpectingTime().Seconds()
326 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
327 ret = make(map[pieceIndex]int)
328 for r := range cn.requests {
329 ret[pieceIndex(r.Index)]++
334 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
335 // \t isn't preserved in <pre> blocks?
336 if cn.closed.IsSet() {
337 fmt.Fprint(w, "CLOSED: ")
339 fmt.Fprintln(w, cn.connStatusString())
340 prio, err := cn.peerPriority()
341 prioStr := fmt.Sprintf("%08x", prio)
343 prioStr += ": " + err.Error()
345 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
346 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
347 eventAgeString(cn.lastMessageReceived),
348 eventAgeString(cn.completedHandshake),
349 eventAgeString(cn.lastHelpful()),
351 cn.totalExpectingTime(),
354 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
355 cn.completedString(),
356 len(cn.peerTouchedPieces),
357 &cn._stats.ChunksReadUseful,
358 &cn._stats.ChunksRead,
359 &cn._stats.ChunksWritten,
360 cn.numLocalRequests(),
361 cn.nominalMaxRequests(),
363 len(cn.peerRequests),
366 cn.downloadRate()/(1<<10),
368 fmt.Fprintf(w, " requested pieces:")
369 for piece, count := range cn.numRequestsByPiece() {
370 fmt.Fprintf(w, " %v (%v)", piece, count)
375 func (p *Peer) close() {
379 p.discardPieceInclination()
380 p._pieceRequestOrder.Clear()
382 p.t.decPeerPieceAvailability(p)
383 for _, f := range p.callbacks.PeerClosed {
388 func (cn *PeerConn) onClose() {
389 if cn.pex.IsEnabled() {
396 if cb := cn.callbacks.PeerConnClosed; cb != nil {
401 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
402 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
405 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
406 // https://github.com/pion/datachannel/issues/59 is fixed.
407 const writeBufferHighWaterLen = 1 << 15
409 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
410 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
411 func (cn *PeerConn) write(msg pp.Message) bool {
412 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
413 // We don't need to track bytes here because a connection.w Writer wrapper takes care of that
414 // (although there's some delay between us recording the message, and the connection writer
415 // flushing it out.).
416 cn.writeBuffer.Write(msg.MustMarshalBinary())
417 // Last I checked only Piece messages affect stats, and we don't write those.
420 return !cn.writeBufferFull()
423 func (cn *PeerConn) writeBufferFull() bool {
424 return cn.writeBuffer.Len() >= writeBufferHighWaterLen
427 func (cn *PeerConn) requestMetadataPiece(index int) {
428 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
432 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
435 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
439 ExtendedPayload: func() []byte {
440 b, err := bencode.Marshal(map[string]int{
441 "msg_type": pp.RequestMetadataExtensionMsgType,
450 for index >= len(cn.metadataRequests) {
451 cn.metadataRequests = append(cn.metadataRequests, false)
453 cn.metadataRequests[index] = true
456 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
457 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
460 // The actual value to use as the maximum outbound requests.
461 func (cn *Peer) nominalMaxRequests() (ret int) {
462 return int(clamp(1, int64(cn.PeerMaxRequests), 64))
465 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
466 ret = cn.cumulativeExpectedToReceiveChunks
467 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
468 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
474 func (cn *PeerConn) onPeerSentCancel(r Request) {
475 if _, ok := cn.peerRequests[r]; !ok {
476 torrent.Add("unexpected cancels received", 1)
479 if cn.fastEnabled() {
482 delete(cn.peerRequests, r)
486 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
491 more = msg(pp.Message{
494 if cn.fastEnabled() {
495 for r := range cn.peerRequests {
496 // TODO: Don't reject pieces in allowed fast set.
500 cn.peerRequests = nil
505 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
510 return msg(pp.Message{
515 func (cn *Peer) setInterested(interested bool) bool {
516 if cn.interested == interested {
519 cn.interested = interested
521 cn.lastBecameInterested = time.Now()
522 } else if !cn.lastBecameInterested.IsZero() {
523 cn.priorInterest += time.Since(cn.lastBecameInterested)
525 cn.updateExpectingChunks()
526 // log.Printf("%p: setting interest: %v", cn, interested)
527 return cn.writeInterested(interested)
530 func (pc *PeerConn) writeInterested(interested bool) bool {
531 return pc.write(pp.Message{
532 Type: func() pp.MessageType {
536 return pp.NotInterested
542 // The function takes a message to be sent, and returns true if more messages
544 type messageWriter func(pp.Message) bool
546 func (cn *Peer) shouldRequest(r Request) error {
547 if !cn.peerHasPiece(pieceIndex(r.Index)) {
548 return errors.New("requesting piece peer doesn't have")
550 if !cn.t.peerIsActive(cn) {
551 panic("requesting but not in active conns")
553 if cn.closed.IsSet() {
554 panic("requesting when connection is closed")
556 if cn.t.hashingPiece(pieceIndex(r.Index)) {
557 panic("piece is being hashed")
559 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
560 panic("piece is queued for hash")
565 func (cn *Peer) request(r Request) error {
566 if err := cn.shouldRequest(r); err != nil {
569 if _, ok := cn.requests[r]; ok {
572 if cn.numLocalRequests() >= cn.nominalMaxRequests() {
573 return errors.New("too many outstanding requests")
575 if cn.requests == nil {
576 cn.requests = make(map[Request]struct{})
578 cn.requests[r] = struct{}{}
579 if cn.validReceiveChunks == nil {
580 cn.validReceiveChunks = make(map[Request]int)
582 cn.validReceiveChunks[r]++
583 cn.t.pendingRequests[r]++
584 cn.updateExpectingChunks()
585 for _, f := range cn.callbacks.SentRequest {
586 f(PeerRequestEvent{cn, r})
588 cn.peerImpl._request(r)
592 func (me *PeerConn) _request(r Request) {
601 func (me *Peer) cancel(r Request) {
602 if me.deleteRequest(r) {
603 me.peerImpl._cancel(r)
607 func (me *PeerConn) _cancel(r Request) {
608 me.write(makeCancelMessage(r))
611 func (cn *PeerConn) fillWriteBuffer() {
612 if cn.pex.IsEnabled() {
613 if flow := cn.pex.Share(cn.write); !flow {
620 // Routine that writes to the peer. Some of what to write is buffered by
621 // activity elsewhere in the Client, and some is determined locally when the
622 // connection is writable.
623 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
625 lastWrite time.Time = time.Now()
626 keepAliveTimer *time.Timer
628 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
630 defer cn.locker().Unlock()
631 if time.Since(lastWrite) >= keepAliveTimeout {
634 keepAliveTimer.Reset(keepAliveTimeout)
637 defer cn.locker().Unlock()
639 defer keepAliveTimer.Stop()
640 frontBuf := new(bytes.Buffer)
642 if cn.closed.IsSet() {
645 if cn.writeBuffer.Len() == 0 {
648 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.useful() {
649 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
650 torrent.Add("written keepalives", 1)
652 if cn.writeBuffer.Len() == 0 {
653 // TODO: Minimize wakeups....
658 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
660 n, err := cn.w.Write(frontBuf.Bytes())
663 lastWrite = time.Now()
664 keepAliveTimer.Reset(keepAliveTimeout)
667 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
670 if n != frontBuf.Len() {
677 func (cn *PeerConn) have(piece pieceIndex) {
678 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
683 Index: pp.Integer(piece),
685 cn.sentHaves.Add(bitmap.BitIndex(piece))
688 func (cn *PeerConn) postBitfield() {
689 if cn.sentHaves.Len() != 0 {
690 panic("bitfield must be first have-related message sent")
692 if !cn.t.haveAnyPieces() {
697 Bitfield: cn.t.bitfield(),
699 cn.sentHaves = cn.t._completedPieces.Copy()
702 func (cn *PeerConn) updateRequests() {
703 // log.Print("update requests")
707 // Emits the indices in the Bitmaps bms in order, never repeating any index.
708 // skip is mutated during execution, and its initial values will never be
710 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
711 return func(cb iter.Callback) {
712 for _, bm := range bms {
714 func(_i interface{}) bool {
716 if skip.Contains(i) {
730 // check callers updaterequests
731 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
732 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
735 // This is distinct from Torrent piece priority, which is the user's
736 // preference. Connection piece priority is specific to a connection and is
737 // used to pseudorandomly avoid connections always requesting the same pieces
738 // and thus wasting effort.
739 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
740 tpp := cn.t.piecePriority(piece)
741 if !cn.peerHasPiece(piece) {
742 tpp = PiecePriorityNone
744 if tpp == PiecePriorityNone {
745 return cn.stopRequestingPiece(piece)
747 prio := cn.getPieceInclination()[piece]
748 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio)
751 func (cn *Peer) getPieceInclination() []int {
752 if cn.pieceInclination == nil {
753 cn.pieceInclination = cn.t.getConnPieceInclination()
755 return cn.pieceInclination
758 func (cn *Peer) discardPieceInclination() {
759 if cn.pieceInclination == nil {
762 cn.t.putPieceInclination(cn.pieceInclination)
763 cn.pieceInclination = nil
766 func (cn *Peer) peerPiecesChanged() {
768 prioritiesChanged := false
769 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
770 if cn.updatePiecePriority(i) {
771 prioritiesChanged = true
774 if prioritiesChanged {
778 cn.t.maybeDropMutuallyCompletePeer(cn)
781 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
782 if newMin > cn.peerMinPieces {
783 cn.peerMinPieces = newMin
787 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
788 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
789 return errors.New("invalid piece")
791 if cn.peerHasPiece(piece) {
794 cn.raisePeerMinPieces(piece + 1)
795 if !cn.peerHasPiece(piece) {
796 cn.t.incPieceAvailability(piece)
798 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
799 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
800 if cn.updatePiecePriority(piece) {
806 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
808 panic("expected bitfield length divisible by 8")
810 // We know that the last byte means that at most the last 7 bits are wasted.
811 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
812 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
813 // Ignore known excess pieces.
814 bf = bf[:cn.t.numPieces()]
816 pp := cn.newPeerPieces()
817 cn.peerSentHaveAll = false
818 for i, have := range bf {
820 cn.raisePeerMinPieces(pieceIndex(i) + 1)
822 cn.t.incPieceAvailability(i)
826 cn.t.decPieceAvailability(i)
829 cn._peerPieces.Set(i, have)
831 cn.peerPiecesChanged()
835 func (cn *Peer) onPeerHasAllPieces() {
838 pp := cn.newPeerPieces()
839 for i := range iter.N(t.numPieces()) {
841 t.incPieceAvailability(i)
845 cn.peerSentHaveAll = true
846 cn._peerPieces.Clear()
847 cn.peerPiecesChanged()
850 func (cn *PeerConn) onPeerSentHaveAll() error {
851 cn.onPeerHasAllPieces()
855 func (cn *PeerConn) peerSentHaveNone() error {
856 cn.t.decPeerPieceAvailability(&cn.Peer)
857 cn._peerPieces.Clear()
858 cn.peerSentHaveAll = false
859 cn.peerPiecesChanged()
863 func (c *PeerConn) requestPendingMetadata() {
867 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
868 // Peer doesn't support this.
871 // Request metadata pieces that we don't have in a random order.
873 for index := 0; index < c.t.metadataPieceCount(); index++ {
874 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
875 pending = append(pending, index)
878 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
879 for _, i := range pending {
880 c.requestMetadataPiece(i)
884 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
885 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
886 if msg.Type == pp.Extended {
887 for name, id := range cn.PeerExtensionIDs {
888 if id != msg.ExtendedID {
891 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
894 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
897 func (cn *PeerConn) readMsg(msg *pp.Message) {
898 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
901 // After handshake, we know what Torrent and Client stats to include for a
903 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
909 // All ConnStats that include this connection. Some objects are not known
910 // until the handshake is complete, after which it's expected to reconcile the
912 func (cn *Peer) allStats(f func(*ConnStats)) {
914 if cn.reconciledHandshakeStats {
915 cn.postHandshakeStats(f)
919 func (cn *PeerConn) wroteBytes(n int64) {
920 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
923 func (cn *PeerConn) readBytes(n int64) {
924 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
927 // Returns whether the connection could be useful to us. We're seeding and
928 // they want data, we don't have metainfo and they can provide it, etc.
929 func (c *Peer) useful() bool {
931 if c.closed.IsSet() {
935 return c.supportsExtension("ut_metadata")
937 if t.seeding() && c.peerInterested {
940 if c.peerHasWantedPieces() {
946 func (c *Peer) lastHelpful() (ret time.Time) {
947 ret = c.lastUsefulChunkReceived
948 if c.t.seeding() && c.lastChunkSent.After(ret) {
949 ret = c.lastChunkSent
954 func (c *PeerConn) fastEnabled() bool {
955 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
958 func (c *PeerConn) reject(r Request) {
959 if !c.fastEnabled() {
960 panic("fast not enabled")
962 c.write(r.ToMsg(pp.Reject))
963 delete(c.peerRequests, r)
966 func (c *PeerConn) onReadRequest(r Request) error {
967 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
968 if _, ok := c.peerRequests[r]; ok {
969 torrent.Add("duplicate requests received", 1)
973 torrent.Add("requests received while choking", 1)
975 torrent.Add("requests rejected while choking", 1)
980 if len(c.peerRequests) >= maxRequests {
981 torrent.Add("requests received while queue full", 1)
985 // BEP 6 says we may close here if we choose.
988 if !c.t.havePiece(pieceIndex(r.Index)) {
989 // This isn't necessarily them screwing up. We can drop pieces
990 // from our storage, and can't communicate this to peers
991 // except by reconnecting.
992 requestsReceivedForMissingPieces.Add(1)
993 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
995 // Check this after we know we have the piece, so that the piece length will be known.
996 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
997 torrent.Add("bad requests received", 1)
998 return errors.New("bad Request")
1000 if c.peerRequests == nil {
1001 c.peerRequests = make(map[Request]*peerRequestState, maxRequests)
1003 value := &peerRequestState{}
1004 c.peerRequests[r] = value
1005 go c.peerRequestDataReader(r, value)
1010 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
1011 b, err := readPeerRequestData(r, c)
1013 defer c.locker().Unlock()
1015 c.peerRequestDataReadFailed(err, r)
1018 panic("data must be non-nil to trigger send")
1025 // If this is maintained correctly, we might be able to support optional synchronous reading for
1026 // chunk sending, the way it used to work.
1027 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
1028 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
1029 i := pieceIndex(r.Index)
1030 if c.t.pieceComplete(i) {
1031 // There used to be more code here that just duplicated the following break. Piece
1032 // completions are currently cached, so I'm not sure how helpful this update is, except to
1033 // pull any completion changes pushed to the storage backend in failed reads that got us
1035 c.t.updatePieceCompletion(i)
1037 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
1038 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
1039 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1040 // next connect. TODO: Support rejecting here too.
1042 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1047 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1048 b := make([]byte, r.Length)
1049 p := c.t.info.Piece(int(r.Index))
1050 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1057 panic("expected error")
1063 func runSafeExtraneous(f func()) {
1071 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1072 // exit. Returning will end the connection.
1073 func (c *PeerConn) mainReadLoop() (err error) {
1076 torrent.Add("connection.mainReadLoop returned with error", 1)
1078 torrent.Add("connection.mainReadLoop returned with no error", 1)
1084 decoder := pp.Decoder{
1085 R: bufio.NewReaderSize(c.r, 1<<17),
1086 MaxLength: 256 * 1024,
1094 err = decoder.Decode(&msg)
1096 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1099 if t.closed.IsSet() || c.closed.IsSet() {
1106 c.lastMessageReceived = time.Now()
1108 receivedKeepalives.Add(1)
1111 messageTypesReceived.Add(msg.Type.String(), 1)
1112 if msg.Type.FastExtension() && !c.fastEnabled() {
1113 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1114 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1118 c.peerChoking = true
1119 if !c.fastEnabled() {
1120 c.deleteAllRequests()
1122 // We can then reset our interest.
1124 c.updateExpectingChunks()
1126 c.peerChoking = false
1128 c.updateExpectingChunks()
1130 c.peerInterested = true
1132 case pp.NotInterested:
1133 c.peerInterested = false
1134 // We don't clear their requests since it isn't clear in the spec.
1135 // We'll probably choke them for this, which will clear them if
1136 // appropriate, and is clearly specified.
1138 err = c.peerSentHave(pieceIndex(msg.Index))
1140 err = c.peerSentBitfield(msg.Bitfield)
1142 r := newRequestFromMessage(&msg)
1143 err = c.onReadRequest(r)
1145 err = c.receiveChunk(&msg)
1146 if len(msg.Piece) == int(t.chunkSize) {
1147 t.chunkPool.Put(&msg.Piece)
1150 err = fmt.Errorf("receiving chunk: %s", err)
1153 req := newRequestFromMessage(&msg)
1154 c.onPeerSentCancel(req)
1156 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1160 pingAddr := net.UDPAddr{
1165 pingAddr.Port = int(msg.Port)
1167 cl.eachDhtServer(func(s DhtServer) {
1168 go s.Ping(&pingAddr)
1171 torrent.Add("suggests received", 1)
1172 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1175 err = c.onPeerSentHaveAll()
1177 err = c.peerSentHaveNone()
1179 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1180 case pp.AllowedFast:
1181 torrent.Add("allowed fasts received", 1)
1182 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1183 c.peerAllowedFast.Add(int(msg.Index))
1186 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1188 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1196 func (c *Peer) remoteRejectedRequest(r Request) {
1197 if c.deleteRequest(r) {
1198 c.decExpectedChunkReceive(r)
1202 func (c *Peer) decExpectedChunkReceive(r Request) {
1203 count := c.validReceiveChunks[r]
1205 delete(c.validReceiveChunks, r)
1206 } else if count > 1 {
1207 c.validReceiveChunks[r] = count - 1
1213 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1215 // TODO: Should we still do this?
1217 // These clients use their own extension IDs for outgoing message
1218 // types, which is incorrect.
1219 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1227 case pp.HandshakeExtendedID:
1228 var d pp.ExtendedHandshakeMessage
1229 if err := bencode.Unmarshal(payload, &d); err != nil {
1230 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1231 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1233 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1236 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1238 c.PeerMaxRequests = d.Reqq
1240 c.PeerClientName = d.V
1241 if c.PeerExtensionIDs == nil {
1242 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1244 c.PeerListenPort = d.Port
1245 c.PeerPrefersEncryption = d.Encryption
1246 for name, id := range d.M {
1247 if _, ok := c.PeerExtensionIDs[name]; !ok {
1248 peersSupportingExtension.Add(string(name), 1)
1250 c.PeerExtensionIDs[name] = id
1252 if d.MetadataSize != 0 {
1253 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1254 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1257 c.requestPendingMetadata()
1258 if !t.cl.config.DisablePEX {
1259 t.pex.Add(c) // we learnt enough now
1263 case metadataExtendedId:
1264 err := cl.gotMetadataExtensionMsg(payload, t, c)
1266 return fmt.Errorf("handling metadata extension message: %w", err)
1270 if !c.pex.IsEnabled() {
1271 return nil // or hang-up maybe?
1273 return c.pex.Recv(payload)
1275 return fmt.Errorf("unexpected extended message ID: %v", id)
1279 // Set both the Reader and Writer for the connection from a single ReadWriter.
1280 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1285 // Returns the Reader and Writer as a combined ReadWriter.
1286 func (cn *PeerConn) rw() io.ReadWriter {
1293 // Handle a received chunk from a peer.
1294 func (c *Peer) receiveChunk(msg *pp.Message) error {
1297 chunksReceived.Add("total", 1)
1299 req := newRequestFromMessage(msg)
1302 chunksReceived.Add("while choked", 1)
1305 if c.validReceiveChunks[req] <= 0 {
1306 chunksReceived.Add("unexpected", 1)
1307 return errors.New("received unexpected chunk")
1309 c.decExpectedChunkReceive(req)
1311 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1312 chunksReceived.Add("due to allowed fast", 1)
1315 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1316 // have actually already received the piece, while we have the Client unlocked to write the data
1318 deletedRequest := false
1320 if _, ok := c.requests[req]; ok {
1321 for _, f := range c.callbacks.ReceivedRequested {
1322 f(PeerMessageEvent{c, msg})
1325 // Request has been satisfied.
1326 if c.deleteRequest(req) {
1327 deletedRequest = true
1329 c._chunksReceivedWhileExpecting++
1332 chunksReceived.Add("unwanted", 1)
1336 // Do we actually want this chunk?
1337 if t.haveChunk(req) {
1338 chunksReceived.Add("wasted", 1)
1339 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1343 piece := &t.pieces[req.Index]
1345 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1346 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1348 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1350 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1351 f(ReceivedUsefulDataEvent{c, msg})
1353 c.lastUsefulChunkReceived = time.Now()
1355 // Need to record that it hasn't been written yet, before we attempt to do
1356 // anything with it.
1357 piece.incrementPendingWrites()
1358 // Record that we have the chunk, so we aren't trying to download it while
1359 // waiting for it to be written to storage.
1360 piece.unpendChunkIndex(chunkIndex(req.ChunkSpec, t.chunkSize))
1362 // Cancel pending requests for this chunk from *other* peers.
1363 t.iterPeers(func(p *Peer) {
1370 err := func() error {
1373 concurrentChunkWrites.Add(1)
1374 defer concurrentChunkWrites.Add(-1)
1375 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1376 // number of connections. We write inline with receiving the chunk (with this lock dance),
1377 // because we want to handle errors synchronously and I haven't thought of a nice way to
1378 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1380 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1383 piece.decrementPendingWrites()
1386 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1388 //t.updatePieceCompletion(pieceIndex(msg.Index))
1389 t.onWriteChunkErr(err)
1393 c.onDirtiedPiece(pieceIndex(req.Index))
1395 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1396 if t.pieceAllDirty(pieceIndex(req.Index)) && piece.pendingWrites == 0 {
1397 t.queuePieceCheck(pieceIndex(req.Index))
1398 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1399 // chunk status (such as the haveChunk call above) to have to check all the various other
1400 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1401 // that chunk pieces are pended at an appropriate time later however.
1404 cl.event.Broadcast()
1405 // We do this because we've written a chunk, and may change PieceState.Partial.
1406 t.publishPieceChange(pieceIndex(req.Index))
1411 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1412 if c.peerTouchedPieces == nil {
1413 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1415 c.peerTouchedPieces[piece] = struct{}{}
1416 ds := &c.t.pieces[piece].dirtiers
1418 *ds = make(map[*Peer]struct{})
1420 (*ds)[c] = struct{}{}
1423 func (c *PeerConn) uploadAllowed() bool {
1424 if c.t.cl.config.NoUpload {
1427 if c.t.dataUploadDisallowed {
1433 if !c.peerHasWantedPieces() {
1436 // Don't upload more than 100 KiB more than we download.
1437 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1443 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1444 if c.uploadTimer == nil {
1445 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1447 c.uploadTimer.Reset(delay)
1451 // Also handles choking and unchoking of the remote peer.
1452 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1453 // Breaking or completing this loop means we don't want to upload to the
1454 // peer anymore, and we choke them.
1456 for c.uploadAllowed() {
1457 // We want to upload to the peer.
1458 if !c.unchoke(msg) {
1461 for r, state := range c.peerRequests {
1462 if state.data == nil {
1465 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1467 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1469 delay := res.Delay()
1472 c.setRetryUploadTimer(delay)
1473 // Hard to say what to return here.
1476 more := c.sendChunk(r, msg, state)
1477 delete(c.peerRequests, r)
1488 func (cn *PeerConn) drop() {
1489 cn.t.dropConnection(cn)
1492 func (cn *Peer) netGoodPiecesDirtied() int64 {
1493 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1496 func (c *Peer) peerHasWantedPieces() bool {
1497 return !c._pieceRequestOrder.IsEmpty()
1500 func (c *Peer) numLocalRequests() int {
1501 return len(c.requests)
1504 func (c *Peer) deleteRequest(r Request) bool {
1505 if _, ok := c.requests[r]; !ok {
1508 delete(c.requests, r)
1509 for _, f := range c.callbacks.DeletedRequest {
1510 f(PeerRequestEvent{c, r})
1512 c.updateExpectingChunks()
1513 pr := c.t.pendingRequests
1525 func (c *Peer) deleteAllRequests() {
1526 for r := range c.requests {
1529 if len(c.requests) != 0 {
1530 panic(len(c.requests))
1532 // for c := range c.t.conns {
1537 // This is called when something has changed that should wake the writer, such as putting stuff into
1538 // the writeBuffer, or changing some state that the writer can act on.
1539 func (c *PeerConn) tickleWriter() {
1540 c.writerCond.Broadcast()
1543 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1544 c.lastChunkSent = time.Now()
1545 return msg(pp.Message{
1553 func (c *PeerConn) setTorrent(t *Torrent) {
1555 panic("connection already associated with a torrent")
1558 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1559 t.reconcileHandshakeStats(c)
1562 func (c *Peer) peerPriority() (peerPriority, error) {
1563 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1566 func (c *Peer) remoteIp() net.IP {
1567 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1568 return net.ParseIP(host)
1571 func (c *Peer) remoteIpPort() IpPort {
1572 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1573 return IpPort{ipa.IP, uint16(ipa.Port)}
1576 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1577 f := pp.PexPeerFlags(0)
1578 if c.PeerPrefersEncryption {
1579 f |= pp.PexPrefersEncryption
1582 f |= pp.PexOutgoingConn
1585 f |= pp.PexSupportsUtp
1590 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1591 // advertised listen port.
1592 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1593 if !c.outgoing && c.PeerListenPort != 0 {
1594 switch addr := c.RemoteAddr.(type) {
1597 dialAddr.Port = c.PeerListenPort
1601 dialAddr.Port = c.PeerListenPort
1608 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1609 f := c.pexPeerFlags()
1610 addr := c.dialAddr()
1611 return pexEvent{t, addr, f}
1614 func (c *PeerConn) String() string {
1615 return fmt.Sprintf("connection %p", c)
1618 func (c *Peer) trust() connectionTrust {
1619 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1622 type connectionTrust struct {
1624 NetGoodPiecesDirted int64
1627 func (l connectionTrust) Less(r connectionTrust) bool {
1628 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1631 func (cn *Peer) peerMaxRequests() int {
1632 return cn.PeerMaxRequests
1635 // Returns the pieces the peer has claimed to have.
1636 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1638 defer cn.locker().RUnlock()
1639 return cn.newPeerPieces()
1642 // Returns a new Bitmap that includes bits for all pieces we have.
1643 func (cn *Peer) newPeerPieces() bitmap.Bitmap {
1644 ret := cn._peerPieces.Copy()
1645 if cn.peerSentHaveAll {
1646 ret.AddRange(0, cn.t.numPieces())
1651 func (cn *Peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1652 return &cn._pieceRequestOrder
1655 func (cn *Peer) stats() *ConnStats {
1659 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1660 pc, ok := p.peerImpl.(*PeerConn)