17 "github.com/RoaringBitmap/roaring"
18 "github.com/anacrolix/log"
19 "github.com/anacrolix/missinggo/iter"
20 "github.com/anacrolix/missinggo/v2/bitmap"
21 "github.com/anacrolix/multiless"
23 "github.com/anacrolix/chansync"
24 "github.com/anacrolix/torrent/bencode"
25 "github.com/anacrolix/torrent/metainfo"
26 "github.com/anacrolix/torrent/mse"
27 pp "github.com/anacrolix/torrent/peer_protocol"
28 request_strategy "github.com/anacrolix/torrent/request-strategy"
31 type PeerSource string
34 PeerSourceTracker = "Tr"
35 PeerSourceIncoming = "I"
36 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
37 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
39 // The peer was given directly, such as through a magnet link.
40 PeerSourceDirect = "M"
43 type peerRequestState struct {
47 type PeerRemoteAddr interface {
51 // Since we have to store all the requests in memory, we can't reasonably exceed what would be
52 // indexable with the memory space available.
55 requestState = request_strategy.PeerRequestState
59 // First to ensure 64-bit alignment for atomics. See #262.
69 RemoteAddr PeerRemoteAddr
70 // True if the connection is operating over MSE obfuscation.
72 cryptoMethod mse.CryptoMethod
75 closed chansync.SetOnce
76 // Set true after we've added our ConnStats generated during handshake to
77 // other ConnStat instances as determined when the *Torrent became known.
78 reconciledHandshakeStats bool
80 lastMessageReceived time.Time
81 completedHandshake time.Time
82 lastUsefulChunkReceived time.Time
83 lastChunkSent time.Time
85 // Stuff controlled by the local peer.
86 needRequestUpdate string
87 requestState requestState
88 updateRequestsTimer *time.Timer
89 lastBecameInterested time.Time
90 priorInterest time.Duration
92 lastStartedExpectingToReceiveChunks time.Time
93 cumulativeExpectedToReceiveChunks time.Duration
94 _chunksReceivedWhileExpecting int64
97 piecesReceivedSinceLastRequestUpdate maxRequests
98 maxPiecesReceivedBetweenRequestUpdates maxRequests
99 // Chunks that we might reasonably expect to receive from the peer. Due to latency, buffering,
100 // and implementation differences, we may receive chunks that are no longer in the set of
101 // requests actually want. This could use a roaring.BSI if the memory use becomes noticeable.
102 validReceiveChunks map[RequestIndex]int
103 // Indexed by metadata piece, set to true if posted and pending a
105 metadataRequests []bool
106 sentHaves bitmap.Bitmap
108 // Stuff controlled by the remote peer.
111 peerRequests map[Request]*peerRequestState
112 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
114 // The highest possible number of pieces the torrent could have based on
115 // communication with the peer. Generally only useful until we have the
117 peerMinPieces pieceIndex
118 // Pieces we've accepted chunks for from the peer.
119 peerTouchedPieces map[pieceIndex]struct{}
120 peerAllowedFast roaring.Bitmap
122 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
123 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
124 PeerClientName atomic.Value
129 // Maintains the state of a BitTorrent-protocol based connection with a peer.
130 type PeerConn struct {
133 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
134 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
139 PeerExtensionBytes pp.PeerExtensionBits
141 // The actual Conn, used for closing, and setting socket options. Do not use methods on this
142 // while holding any mutexes.
144 // The Reader and Writer for this Conn, with hooks installed for stats,
145 // limiting, deadlines etc.
149 messageWriter peerConnMsgWriter
151 uploadTimer *time.Timer
154 // The pieces the peer has claimed to have.
155 _peerPieces roaring.Bitmap
156 // The peer has everything. This can occur due to a special message, when
157 // we may not even know the number of pieces in the torrent yet.
161 func (cn *PeerConn) connStatusString() string {
162 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
165 func (cn *Peer) updateExpectingChunks() {
166 if cn.expectingChunks() {
167 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
168 cn.lastStartedExpectingToReceiveChunks = time.Now()
171 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
172 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
173 cn.lastStartedExpectingToReceiveChunks = time.Time{}
178 func (cn *Peer) expectingChunks() bool {
179 if cn.requestState.Requests.IsEmpty() {
182 if !cn.requestState.Interested {
188 haveAllowedFastRequests := false
189 cn.peerAllowedFast.Iterate(func(i uint32) bool {
190 haveAllowedFastRequests = roaringBitmapRangeCardinality(
191 &cn.requestState.Requests,
192 cn.t.pieceRequestIndexOffset(pieceIndex(i)),
193 cn.t.pieceRequestIndexOffset(pieceIndex(i+1)),
195 return !haveAllowedFastRequests
197 return haveAllowedFastRequests
200 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
201 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
204 // Returns true if the connection is over IPv6.
205 func (cn *PeerConn) ipv6() bool {
210 return len(ip) == net.IPv6len
213 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
214 // specification for this.
215 func (cn *PeerConn) isPreferredDirection() bool {
216 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
219 // Returns whether the left connection should be preferred over the right one,
220 // considering only their networking properties. If ok is false, we can't
222 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
224 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
225 ml.NextBool(!l.utp(), !r.utp())
226 ml.NextBool(l.ipv6(), r.ipv6())
230 func (cn *Peer) cumInterest() time.Duration {
231 ret := cn.priorInterest
232 if cn.requestState.Interested {
233 ret += time.Since(cn.lastBecameInterested)
238 func (cn *PeerConn) peerHasAllPieces() (all bool, known bool) {
239 if cn.peerSentHaveAll {
242 if !cn.t.haveInfo() {
245 return cn._peerPieces.GetCardinality() == uint64(cn.t.numPieces()), true
248 func (cn *Peer) locker() *lockWithDeferreds {
249 return cn.t.cl.locker()
252 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
253 _, ok := cn.PeerExtensionIDs[ext]
257 // The best guess at number of pieces in the torrent for this peer.
258 func (cn *Peer) bestPeerNumPieces() pieceIndex {
260 return cn.t.numPieces()
262 return cn.peerMinPieces
265 func (cn *Peer) completedString() string {
266 have := pieceIndex(cn.peerPieces().GetCardinality())
267 if all, _ := cn.peerHasAllPieces(); all {
268 have = cn.bestPeerNumPieces()
270 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
273 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
274 cn.setNumPieces(info.NumPieces())
277 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
278 // receiving badly sized BITFIELD, or invalid HAVE messages.
279 func (cn *PeerConn) setNumPieces(num pieceIndex) {
280 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
281 cn.peerPiecesChanged()
284 func (cn *PeerConn) peerPieces() *roaring.Bitmap {
285 return &cn._peerPieces
288 func eventAgeString(t time.Time) string {
292 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
295 func (cn *PeerConn) connectionFlags() (ret string) {
297 ret += string([]byte{b})
299 if cn.cryptoMethod == mse.CryptoMethodRC4 {
301 } else if cn.headerEncrypted {
304 ret += string(cn.Discovery)
311 func (cn *PeerConn) utp() bool {
312 return parseNetworkString(cn.Network).Udp
315 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
316 func (cn *Peer) statusFlags() (ret string) {
318 ret += string([]byte{b})
320 if cn.requestState.Interested {
327 ret += cn.connectionFlags()
329 if cn.peerInterested {
338 func (cn *Peer) downloadRate() float64 {
339 num := cn._stats.BytesReadUsefulData.Int64()
343 return float64(num) / cn.totalExpectingTime().Seconds()
346 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
347 ret = make(map[pieceIndex]int)
348 cn.requestState.Requests.Iterate(func(x uint32) bool {
349 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
355 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
356 // \t isn't preserved in <pre> blocks?
357 if cn.closed.IsSet() {
358 fmt.Fprint(w, "CLOSED: ")
360 fmt.Fprintln(w, cn.connStatusString())
361 prio, err := cn.peerPriority()
362 prioStr := fmt.Sprintf("%08x", prio)
364 prioStr += ": " + err.Error()
366 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
367 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
368 eventAgeString(cn.lastMessageReceived),
369 eventAgeString(cn.completedHandshake),
370 eventAgeString(cn.lastHelpful()),
372 cn.totalExpectingTime(),
375 " %s completed, %d pieces touched, good chunks: %v/%v:%v reqq: %d+%v/(%d/%d):%d/%d, flags: %s, dr: %.1f KiB/s\n",
376 cn.completedString(),
377 len(cn.peerTouchedPieces),
378 &cn._stats.ChunksReadUseful,
379 &cn._stats.ChunksRead,
380 &cn._stats.ChunksWritten,
381 cn.requestState.Requests.GetCardinality(),
382 cn.requestState.Cancelled.GetCardinality(),
383 cn.nominalMaxRequests(),
385 len(cn.peerRequests),
388 cn.downloadRate()/(1<<10),
390 fmt.Fprintf(w, " requested pieces:")
391 type pieceNumRequestsType struct {
395 var pieceNumRequests []pieceNumRequestsType
396 for piece, count := range cn.numRequestsByPiece() {
397 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
399 sort.Slice(pieceNumRequests, func(i, j int) bool {
400 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
402 for _, elem := range pieceNumRequests {
403 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
408 func (p *Peer) close() {
412 if p.updateRequestsTimer != nil {
413 p.updateRequestsTimer.Stop()
417 p.t.decPeerPieceAvailability(p)
419 for _, f := range p.callbacks.PeerClosed {
424 func (cn *PeerConn) onClose() {
425 if cn.pex.IsEnabled() {
432 if cb := cn.callbacks.PeerConnClosed; cb != nil {
437 // Peer definitely has a piece, for purposes of requesting. So it's not sufficient that we think
438 // they do (known=true).
439 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
440 if all, known := cn.peerHasAllPieces(); all && known {
443 return cn.peerPieces().ContainsInt(piece)
446 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
447 // https://github.com/pion/datachannel/issues/59 is fixed.
448 const writeBufferHighWaterLen = 1 << 15
450 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
451 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
452 func (cn *PeerConn) write(msg pp.Message) bool {
453 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
454 // We don't need to track bytes here because the connection's Writer has that behaviour injected
455 // (although there's some delay between us buffering the message, and the connection writer
456 // flushing it out.).
457 notFull := cn.messageWriter.write(msg)
458 // Last I checked only Piece messages affect stats, and we don't write those.
464 func (cn *PeerConn) requestMetadataPiece(index int) {
465 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
466 if eID == pp.ExtensionDeleteNumber {
469 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
472 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
473 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
474 for index >= len(cn.metadataRequests) {
475 cn.metadataRequests = append(cn.metadataRequests, false)
477 cn.metadataRequests[index] = true
480 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
481 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
484 // The actual value to use as the maximum outbound requests.
485 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
486 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 2048))
489 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
490 ret = cn.cumulativeExpectedToReceiveChunks
491 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
492 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
497 func (cn *PeerConn) onPeerSentCancel(r Request) {
498 if _, ok := cn.peerRequests[r]; !ok {
499 torrent.Add("unexpected cancels received", 1)
502 if cn.fastEnabled() {
505 delete(cn.peerRequests, r)
509 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
514 more = msg(pp.Message{
517 if cn.fastEnabled() {
518 for r := range cn.peerRequests {
519 // TODO: Don't reject pieces in allowed fast set.
523 cn.peerRequests = nil
528 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
533 return msg(pp.Message{
538 func (cn *Peer) setInterested(interested bool) bool {
539 if cn.requestState.Interested == interested {
542 cn.requestState.Interested = interested
544 cn.lastBecameInterested = time.Now()
545 } else if !cn.lastBecameInterested.IsZero() {
546 cn.priorInterest += time.Since(cn.lastBecameInterested)
548 cn.updateExpectingChunks()
549 // log.Printf("%p: setting interest: %v", cn, interested)
550 return cn.writeInterested(interested)
553 func (pc *PeerConn) writeInterested(interested bool) bool {
554 return pc.write(pp.Message{
555 Type: func() pp.MessageType {
559 return pp.NotInterested
565 // The function takes a message to be sent, and returns true if more messages
567 type messageWriter func(pp.Message) bool
569 // This function seems to only used by Peer.request. It's all logic checks, so maybe we can no-op it
570 // when we want to go fast.
571 func (cn *Peer) shouldRequest(r RequestIndex) error {
572 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
573 if !cn.peerHasPiece(pi) {
574 return errors.New("requesting piece peer doesn't have")
576 if !cn.t.peerIsActive(cn) {
577 panic("requesting but not in active conns")
579 if cn.closed.IsSet() {
580 panic("requesting when connection is closed")
582 if cn.t.hashingPiece(pi) {
583 panic("piece is being hashed")
585 if cn.t.pieceQueuedForHash(pi) {
586 panic("piece is queued for hash")
588 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
589 // This could occur if we made a request with the fast extension, and then got choked and
590 // haven't had the request rejected yet.
591 if !cn.requestState.Requests.Contains(r) {
592 panic("peer choking and piece not allowed fast")
598 func (cn *Peer) mustRequest(r RequestIndex) bool {
599 more, err := cn.request(r)
606 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
607 if err := cn.shouldRequest(r); err != nil {
610 if cn.requestState.Requests.Contains(r) {
613 if maxRequests(cn.requestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
614 return true, errors.New("too many outstanding requests")
616 cn.requestState.Requests.Add(r)
617 if cn.validReceiveChunks == nil {
618 cn.validReceiveChunks = make(map[RequestIndex]int)
620 cn.validReceiveChunks[r]++
621 cn.t.pendingRequests[r] = cn
622 cn.t.lastRequested[r] = time.Now()
623 cn.updateExpectingChunks()
624 ppReq := cn.t.requestIndexToRequest(r)
625 for _, f := range cn.callbacks.SentRequest {
626 f(PeerRequestEvent{cn, ppReq})
628 return cn.peerImpl._request(ppReq), nil
631 func (me *PeerConn) _request(r Request) bool {
632 return me.write(pp.Message{
640 func (me *Peer) cancel(r RequestIndex) {
641 if !me.deleteRequest(r) {
642 panic("request not existing should have been guarded")
645 if !me.requestState.Cancelled.CheckedAdd(r) {
646 panic("request already cancelled")
649 if me.isLowOnRequests() {
650 me.updateRequests("Peer.cancel")
654 func (me *PeerConn) _cancel(r RequestIndex) bool {
655 me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
656 // Transmission does not send rejects for received cancels. See
657 // https://github.com/transmission/transmission/pull/2275.
658 return me.fastEnabled() && !me.remoteIsTransmission()
661 func (cn *PeerConn) fillWriteBuffer() {
662 if !cn.maybeUpdateActualRequestState() {
665 if cn.pex.IsEnabled() {
666 if flow := cn.pex.Share(cn.write); !flow {
673 func (cn *PeerConn) have(piece pieceIndex) {
674 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
679 Index: pp.Integer(piece),
681 cn.sentHaves.Add(bitmap.BitIndex(piece))
684 func (cn *PeerConn) postBitfield() {
685 if cn.sentHaves.Len() != 0 {
686 panic("bitfield must be first have-related message sent")
688 if !cn.t.haveAnyPieces() {
693 Bitfield: cn.t.bitfield(),
695 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
698 // Sets a reason to update requests, and if there wasn't already one, handle it.
699 func (cn *Peer) updateRequests(reason string) {
700 if cn.needRequestUpdate != "" {
703 cn.needRequestUpdate = reason
704 cn.handleUpdateRequests()
707 func (cn *PeerConn) handleUpdateRequests() {
708 // The writer determines the request state as needed when it can write.
712 // Emits the indices in the Bitmaps bms in order, never repeating any index.
713 // skip is mutated during execution, and its initial values will never be
715 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
716 return func(cb iter.Callback) {
717 for _, bm := range bms {
719 func(_i interface{}) bool {
721 if skip.Contains(bitmap.BitIndex(i)) {
724 skip.Add(bitmap.BitIndex(i))
735 func (cn *Peer) peerPiecesChanged() {
736 cn.t.maybeDropMutuallyCompletePeer(cn)
739 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
740 if newMin > cn.peerMinPieces {
741 cn.peerMinPieces = newMin
745 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
746 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
747 return errors.New("invalid piece")
749 if cn.peerHasPiece(piece) {
752 cn.raisePeerMinPieces(piece + 1)
753 if !cn.peerHasPiece(piece) {
754 cn.t.incPieceAvailability(piece)
756 cn._peerPieces.Add(uint32(piece))
757 if cn.t.wantPieceIndex(piece) {
758 cn.updateRequests("have")
760 cn.peerPiecesChanged()
764 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
766 panic("expected bitfield length divisible by 8")
768 // We know that the last byte means that at most the last 7 bits are wasted.
769 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
770 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
771 // Ignore known excess pieces.
772 bf = bf[:cn.t.numPieces()]
774 pp := cn.newPeerPieces()
775 cn.peerSentHaveAll = false
776 for i, have := range bf {
778 cn.raisePeerMinPieces(pieceIndex(i) + 1)
779 if !pp.Contains(bitmap.BitIndex(i)) {
780 cn.t.incPieceAvailability(i)
783 if pp.Contains(bitmap.BitIndex(i)) {
784 cn.t.decPieceAvailability(i)
788 cn._peerPieces.Add(uint32(i))
789 if cn.t.wantPieceIndex(i) {
790 cn.updateRequests("bitfield")
793 cn._peerPieces.Remove(uint32(i))
796 cn.peerPiecesChanged()
800 func (cn *PeerConn) onPeerHasAllPieces() {
803 npp, pc := cn.newPeerPieces(), t.numPieces()
804 for i := 0; i < pc; i += 1 {
805 if !npp.Contains(bitmap.BitIndex(i)) {
806 t.incPieceAvailability(i)
810 cn.peerSentHaveAll = true
811 cn._peerPieces.Clear()
812 if !cn.t._pendingPieces.IsEmpty() {
813 cn.updateRequests("Peer.onPeerHasAllPieces")
815 cn.peerPiecesChanged()
818 func (cn *PeerConn) onPeerSentHaveAll() error {
819 cn.onPeerHasAllPieces()
823 func (cn *PeerConn) peerSentHaveNone() error {
824 cn.t.decPeerPieceAvailability(&cn.Peer)
825 cn._peerPieces.Clear()
826 cn.peerSentHaveAll = false
827 cn.peerPiecesChanged()
831 func (c *PeerConn) requestPendingMetadata() {
835 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
836 // Peer doesn't support this.
839 // Request metadata pieces that we don't have in a random order.
841 for index := 0; index < c.t.metadataPieceCount(); index++ {
842 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
843 pending = append(pending, index)
846 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
847 for _, i := range pending {
848 c.requestMetadataPiece(i)
852 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
853 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
854 if msg.Type == pp.Extended {
855 for name, id := range cn.PeerExtensionIDs {
856 if id != msg.ExtendedID {
859 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
862 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
865 // After handshake, we know what Torrent and Client stats to include for a
867 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
873 // All ConnStats that include this connection. Some objects are not known
874 // until the handshake is complete, after which it's expected to reconcile the
876 func (cn *Peer) allStats(f func(*ConnStats)) {
878 if cn.reconciledHandshakeStats {
879 cn.postHandshakeStats(f)
883 func (cn *PeerConn) wroteBytes(n int64) {
884 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
887 func (cn *Peer) readBytes(n int64) {
888 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
891 // Returns whether the connection could be useful to us. We're seeding and
892 // they want data, we don't have metainfo and they can provide it, etc.
893 func (c *Peer) useful() bool {
895 if c.closed.IsSet() {
899 return c.supportsExtension("ut_metadata")
901 if t.seeding() && c.peerInterested {
904 if c.peerHasWantedPieces() {
910 func (c *Peer) lastHelpful() (ret time.Time) {
911 ret = c.lastUsefulChunkReceived
912 if c.t.seeding() && c.lastChunkSent.After(ret) {
913 ret = c.lastChunkSent
918 func (c *PeerConn) fastEnabled() bool {
919 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
922 func (c *PeerConn) reject(r Request) {
923 if !c.fastEnabled() {
924 panic("fast not enabled")
926 c.write(r.ToMsg(pp.Reject))
927 delete(c.peerRequests, r)
930 func (c *PeerConn) onReadRequest(r Request) error {
931 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
932 if _, ok := c.peerRequests[r]; ok {
933 torrent.Add("duplicate requests received", 1)
937 torrent.Add("requests received while choking", 1)
939 torrent.Add("requests rejected while choking", 1)
944 // TODO: What if they've already requested this?
945 if len(c.peerRequests) >= localClientReqq {
946 torrent.Add("requests received while queue full", 1)
950 // BEP 6 says we may close here if we choose.
953 if !c.t.havePiece(pieceIndex(r.Index)) {
954 // This isn't necessarily them screwing up. We can drop pieces
955 // from our storage, and can't communicate this to peers
956 // except by reconnecting.
957 requestsReceivedForMissingPieces.Add(1)
958 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
960 // Check this after we know we have the piece, so that the piece length will be known.
961 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
962 torrent.Add("bad requests received", 1)
963 return errors.New("bad Request")
965 if c.peerRequests == nil {
966 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
968 value := &peerRequestState{}
969 c.peerRequests[r] = value
970 go c.peerRequestDataReader(r, value)
975 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
976 b, err := readPeerRequestData(r, c)
978 defer c.locker().Unlock()
980 c.peerRequestDataReadFailed(err, r)
983 panic("data must be non-nil to trigger send")
990 // If this is maintained correctly, we might be able to support optional synchronous reading for
991 // chunk sending, the way it used to work.
992 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
993 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
994 if c.t.closed.IsSet() {
997 i := pieceIndex(r.Index)
998 if c.t.pieceComplete(i) {
999 // There used to be more code here that just duplicated the following break. Piece
1000 // completions are currently cached, so I'm not sure how helpful this update is, except to
1001 // pull any completion changes pushed to the storage backend in failed reads that got us
1003 c.t.updatePieceCompletion(i)
1005 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
1006 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
1007 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1008 // next connect. TODO: Support rejecting here too.
1010 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1015 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1016 b := make([]byte, r.Length)
1017 p := c.t.info.Piece(int(r.Index))
1018 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1025 panic("expected error")
1031 func runSafeExtraneous(f func()) {
1039 func (c *PeerConn) logProtocolBehaviour(level log.Level, format string, arg ...interface{}) {
1040 c.logger.WithLevel(level).WithContextText(fmt.Sprintf(
1041 "peer id %q, ext v %q", c.PeerID, c.PeerClientName.Load(),
1042 )).SkipCallers(1).Printf(format, arg...)
1045 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1046 // exit. Returning will end the connection.
1047 func (c *PeerConn) mainReadLoop() (err error) {
1050 torrent.Add("connection.mainReadLoop returned with error", 1)
1052 torrent.Add("connection.mainReadLoop returned with no error", 1)
1058 decoder := pp.Decoder{
1059 R: bufio.NewReaderSize(c.r, 1<<17),
1060 MaxLength: 256 * 1024,
1068 err = decoder.Decode(&msg)
1070 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1073 if t.closed.IsSet() || c.closed.IsSet() {
1079 c.lastMessageReceived = time.Now()
1081 receivedKeepalives.Add(1)
1084 messageTypesReceived.Add(msg.Type.String(), 1)
1085 if msg.Type.FastExtension() && !c.fastEnabled() {
1086 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1087 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1094 if !c.fastEnabled() {
1095 c.deleteAllRequests()
1097 // We don't decrement pending requests here, let's wait for the peer to either
1098 // reject or satisfy the outstanding requests. Additionally, some peers may unchoke
1099 // us and resume where they left off, we don't want to have piled on to those chunks
1100 // in the meanwhile. I think a peer's ability to abuse this should be limited: they
1101 // could let us request a lot of stuff, then choke us and never reject, but they're
1102 // only a single peer, our chunk balancing should smooth over this abuse.
1104 c.peerChoking = true
1105 c.updateExpectingChunks()
1108 // Some clients do this for some reason. Transmission doesn't error on this, so we
1109 // won't for consistency.
1110 c.logProtocolBehaviour(log.Debug, "received unchoke when already unchoked")
1113 c.peerChoking = false
1115 c.requestState.Requests.Iterate(func(x uint32) bool {
1116 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1121 if preservedCount != 0 {
1122 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
1124 c.logger.WithLevel(log.Debug).Printf(
1125 "%v requests were preserved while being choked (fast=%v)",
1128 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
1130 if !c.t._pendingPieces.IsEmpty() {
1131 c.updateRequests("unchoked")
1133 c.updateExpectingChunks()
1135 c.peerInterested = true
1137 case pp.NotInterested:
1138 c.peerInterested = false
1139 // We don't clear their requests since it isn't clear in the spec.
1140 // We'll probably choke them for this, which will clear them if
1141 // appropriate, and is clearly specified.
1143 err = c.peerSentHave(pieceIndex(msg.Index))
1145 err = c.peerSentBitfield(msg.Bitfield)
1147 r := newRequestFromMessage(&msg)
1148 err = c.onReadRequest(r)
1150 c.doChunkReadStats(int64(len(msg.Piece)))
1151 err = c.receiveChunk(&msg)
1152 if len(msg.Piece) == int(t.chunkSize) {
1153 t.chunkPool.Put(&msg.Piece)
1156 err = fmt.Errorf("receiving chunk: %w", err)
1159 req := newRequestFromMessage(&msg)
1160 c.onPeerSentCancel(req)
1162 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1166 pingAddr := net.UDPAddr{
1171 pingAddr.Port = int(msg.Port)
1173 cl.eachDhtServer(func(s DhtServer) {
1174 go s.Ping(&pingAddr)
1177 torrent.Add("suggests received", 1)
1178 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1179 c.updateRequests("suggested")
1181 err = c.onPeerSentHaveAll()
1183 err = c.peerSentHaveNone()
1185 req := newRequestFromMessage(&msg)
1186 if !c.remoteRejectedRequest(c.t.requestIndexFromRequest(req)) {
1187 log.Printf("received invalid reject [request=%v, peer=%v]", req, c)
1188 err = fmt.Errorf("received invalid reject [request=%v]", req)
1190 case pp.AllowedFast:
1191 torrent.Add("allowed fasts received", 1)
1192 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1193 c.updateRequests("PeerConn.mainReadLoop allowed fast")
1195 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1197 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1205 // Returns true if it was valid to reject the request.
1206 func (c *Peer) remoteRejectedRequest(r RequestIndex) bool {
1207 if !c.deleteRequest(r) && !c.requestState.Cancelled.CheckedRemove(r) {
1210 if c.isLowOnRequests() {
1211 c.updateRequests("Peer.remoteRejectedRequest")
1213 c.decExpectedChunkReceive(r)
1217 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1218 count := c.validReceiveChunks[r]
1220 delete(c.validReceiveChunks, r)
1221 } else if count > 1 {
1222 c.validReceiveChunks[r] = count - 1
1228 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1230 // TODO: Should we still do this?
1232 // These clients use their own extension IDs for outgoing message
1233 // types, which is incorrect.
1234 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1242 case pp.HandshakeExtendedID:
1243 var d pp.ExtendedHandshakeMessage
1244 if err := bencode.Unmarshal(payload, &d); err != nil {
1245 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1246 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1248 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1251 // c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1253 c.PeerMaxRequests = d.Reqq
1255 c.PeerClientName.Store(d.V)
1256 if c.PeerExtensionIDs == nil {
1257 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1259 c.PeerListenPort = d.Port
1260 c.PeerPrefersEncryption = d.Encryption
1261 for name, id := range d.M {
1262 if _, ok := c.PeerExtensionIDs[name]; !ok {
1263 peersSupportingExtension.Add(
1264 // expvar.Var.String must produce valid JSON. "ut_payme\xeet_address" was being
1265 // entered here which caused problems later when unmarshalling.
1266 strconv.Quote(string(name)),
1269 c.PeerExtensionIDs[name] = id
1271 if d.MetadataSize != 0 {
1272 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1273 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1276 c.requestPendingMetadata()
1277 if !t.cl.config.DisablePEX {
1278 t.pex.Add(c) // we learnt enough now
1282 case metadataExtendedId:
1283 err := cl.gotMetadataExtensionMsg(payload, t, c)
1285 return fmt.Errorf("handling metadata extension message: %w", err)
1289 if !c.pex.IsEnabled() {
1290 return nil // or hang-up maybe?
1292 return c.pex.Recv(payload)
1294 return fmt.Errorf("unexpected extended message ID: %v", id)
1298 // Set both the Reader and Writer for the connection from a single ReadWriter.
1299 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1304 // Returns the Reader and Writer as a combined ReadWriter.
1305 func (cn *PeerConn) rw() io.ReadWriter {
1312 func (c *Peer) doChunkReadStats(size int64) {
1313 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1316 // Handle a received chunk from a peer.
1317 func (c *Peer) receiveChunk(msg *pp.Message) error {
1318 chunksReceived.Add("total", 1)
1320 ppReq := newRequestFromMessage(msg)
1321 req := c.t.requestIndexFromRequest(ppReq)
1324 chunksReceived.Add("while choked", 1)
1327 if c.validReceiveChunks[req] <= 0 {
1328 chunksReceived.Add("unexpected", 1)
1329 return errors.New("received unexpected chunk")
1331 c.decExpectedChunkReceive(req)
1333 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1334 chunksReceived.Add("due to allowed fast", 1)
1337 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1338 // have actually already received the piece, while we have the Client unlocked to write the data
1342 if c.requestState.Requests.Contains(req) {
1343 for _, f := range c.callbacks.ReceivedRequested {
1344 f(PeerMessageEvent{c, msg})
1347 // Request has been satisfied.
1348 if c.deleteRequest(req) || c.requestState.Cancelled.CheckedRemove(req) {
1351 c._chunksReceivedWhileExpecting++
1353 if c.isLowOnRequests() {
1354 c.updateRequests("Peer.receiveChunk deleted request")
1357 chunksReceived.Add("unintended", 1)
1364 // Do we actually want this chunk?
1365 if t.haveChunk(ppReq) {
1366 // panic(fmt.Sprintf("%+v", ppReq))
1367 chunksReceived.Add("redundant", 1)
1368 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1372 piece := &t.pieces[ppReq.Index]
1374 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1375 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1377 c.piecesReceivedSinceLastRequestUpdate++
1378 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1380 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1381 f(ReceivedUsefulDataEvent{c, msg})
1383 c.lastUsefulChunkReceived = time.Now()
1385 // Need to record that it hasn't been written yet, before we attempt to do
1386 // anything with it.
1387 piece.incrementPendingWrites()
1388 // Record that we have the chunk, so we aren't trying to download it while
1389 // waiting for it to be written to storage.
1390 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1392 // Cancel pending requests for this chunk from *other* peers.
1393 if p := t.pendingRequests[req]; p != nil {
1395 panic("should not be pending request from conn that just received it")
1400 err := func() error {
1403 concurrentChunkWrites.Add(1)
1404 defer concurrentChunkWrites.Add(-1)
1405 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1406 // number of connections. We write inline with receiving the chunk (with this lock dance),
1407 // because we want to handle errors synchronously and I haven't thought of a nice way to
1408 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1410 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1413 piece.decrementPendingWrites()
1416 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1418 // Necessary to pass TestReceiveChunkStorageFailureSeederFastExtensionDisabled. I think a
1419 // request update runs while we're writing the chunk that just failed. Then we never do a
1420 // fresh update after pending the failed request.
1421 c.updateRequests("Peer.receiveChunk error writing chunk")
1422 t.onWriteChunkErr(err)
1426 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1428 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1429 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1430 t.queuePieceCheck(pieceIndex(ppReq.Index))
1431 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1432 // chunk status (such as the haveChunk call above) to have to check all the various other
1433 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1434 // that chunk pieces are pended at an appropriate time later however.
1437 cl.event.Broadcast()
1438 // We do this because we've written a chunk, and may change PieceState.Partial.
1439 t.publishPieceChange(pieceIndex(ppReq.Index))
1444 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1445 if c.peerTouchedPieces == nil {
1446 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1448 c.peerTouchedPieces[piece] = struct{}{}
1449 ds := &c.t.pieces[piece].dirtiers
1451 *ds = make(map[*Peer]struct{})
1453 (*ds)[c] = struct{}{}
1456 func (c *PeerConn) uploadAllowed() bool {
1457 if c.t.cl.config.NoUpload {
1460 if c.t.dataUploadDisallowed {
1466 if !c.peerHasWantedPieces() {
1469 // Don't upload more than 100 KiB more than we download.
1470 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1476 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1477 if c.uploadTimer == nil {
1478 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1480 c.uploadTimer.Reset(delay)
1484 // Also handles choking and unchoking of the remote peer.
1485 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1486 // Breaking or completing this loop means we don't want to upload to the
1487 // peer anymore, and we choke them.
1489 for c.uploadAllowed() {
1490 // We want to upload to the peer.
1491 if !c.unchoke(msg) {
1494 for r, state := range c.peerRequests {
1495 if state.data == nil {
1498 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1500 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1502 delay := res.Delay()
1505 c.setRetryUploadTimer(delay)
1506 // Hard to say what to return here.
1509 more := c.sendChunk(r, msg, state)
1510 delete(c.peerRequests, r)
1521 func (cn *PeerConn) drop() {
1522 cn.t.dropConnection(cn)
1525 func (cn *Peer) netGoodPiecesDirtied() int64 {
1526 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1529 func (c *Peer) peerHasWantedPieces() bool {
1530 if all, _ := c.peerHasAllPieces(); all {
1531 return !c.t.haveAllPieces() && !c.t._pendingPieces.IsEmpty()
1533 if !c.t.haveInfo() {
1534 return !c.peerPieces().IsEmpty()
1536 return c.peerPieces().Intersects(&c.t._pendingPieces)
1539 // Returns true if an outstanding request is removed. Cancelled requests should be handled
1541 func (c *Peer) deleteRequest(r RequestIndex) bool {
1542 if !c.requestState.Requests.CheckedRemove(r) {
1545 for _, f := range c.callbacks.DeletedRequest {
1546 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1548 c.updateExpectingChunks()
1549 if c.t.requestingPeer(r) != c {
1550 panic("only one peer should have a given request at a time")
1552 delete(c.t.pendingRequests, r)
1553 delete(c.t.lastRequested, r)
1557 func (c *Peer) deleteAllRequests() {
1558 c.requestState.Requests.Clone().Iterate(func(x uint32) bool {
1559 if !c.deleteRequest(x) {
1560 panic("request should exist")
1564 if !c.requestState.Requests.IsEmpty() {
1565 panic(c.requestState.Requests.GetCardinality())
1569 // This is called when something has changed that should wake the writer, such as putting stuff into
1570 // the writeBuffer, or changing some state that the writer can act on.
1571 func (c *PeerConn) tickleWriter() {
1572 c.messageWriter.writeCond.Broadcast()
1575 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1576 c.lastChunkSent = time.Now()
1577 return msg(pp.Message{
1585 func (c *PeerConn) setTorrent(t *Torrent) {
1587 panic("connection already associated with a torrent")
1590 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1591 t.reconcileHandshakeStats(c)
1594 func (c *Peer) peerPriority() (peerPriority, error) {
1595 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1598 func (c *Peer) remoteIp() net.IP {
1599 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1600 return net.ParseIP(host)
1603 func (c *Peer) remoteIpPort() IpPort {
1604 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1605 return IpPort{ipa.IP, uint16(ipa.Port)}
1608 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1609 f := pp.PexPeerFlags(0)
1610 if c.PeerPrefersEncryption {
1611 f |= pp.PexPrefersEncryption
1614 f |= pp.PexOutgoingConn
1617 f |= pp.PexSupportsUtp
1622 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1623 // advertised listen port.
1624 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1625 if !c.outgoing && c.PeerListenPort != 0 {
1626 switch addr := c.RemoteAddr.(type) {
1629 dialAddr.Port = c.PeerListenPort
1633 dialAddr.Port = c.PeerListenPort
1640 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1641 f := c.pexPeerFlags()
1642 addr := c.dialAddr()
1643 return pexEvent{t, addr, f, nil}
1646 func (c *PeerConn) String() string {
1647 return fmt.Sprintf("%T %p [id=%q, exts=%v, v=%q]", c, c, c.PeerID, c.PeerExtensionBytes, c.PeerClientName.Load())
1650 func (c *Peer) trust() connectionTrust {
1651 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1654 type connectionTrust struct {
1656 NetGoodPiecesDirted int64
1659 func (l connectionTrust) Less(r connectionTrust) bool {
1660 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1663 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1664 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1665 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1667 defer cn.locker().RUnlock()
1668 return cn.newPeerPieces()
1671 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1672 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1673 // TODO: Can we use copy on write?
1674 ret := cn.peerPieces().Clone()
1675 if all, _ := cn.peerHasAllPieces(); all {
1676 if cn.t.haveInfo() {
1677 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1679 ret.AddRange(0, bitmap.ToEnd)
1685 func (cn *Peer) stats() *ConnStats {
1689 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1690 pc, ok := p.peerImpl.(*PeerConn)
1694 func (pc *PeerConn) isLowOnRequests() bool {
1695 return pc.requestState.Requests.IsEmpty() && pc.requestState.Cancelled.IsEmpty()
1698 func (p *Peer) uncancelledRequests() uint64 {
1699 return p.requestState.Requests.GetCardinality()
1702 func (pc *PeerConn) remoteIsTransmission() bool {
1703 return bytes.HasPrefix(pc.PeerID[:], []byte("-TR")) && pc.PeerID[7] == '-'