16 "github.com/RoaringBitmap/roaring"
17 "github.com/anacrolix/log"
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"
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.PeerNextRequestState
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 nextRequestState requestState
87 actualRequestState requestState
88 lastBecameInterested time.Time
89 priorInterest time.Duration
91 lastStartedExpectingToReceiveChunks time.Time
92 cumulativeExpectedToReceiveChunks time.Duration
93 _chunksReceivedWhileExpecting int64
96 piecesReceivedSinceLastRequestUpdate maxRequests
97 maxPiecesReceivedBetweenRequestUpdates maxRequests
98 // Chunks that we might reasonably expect to receive from the peer. Due to
99 // latency, buffering, and implementation differences, we may receive
100 // chunks that are no longer in the set of requests actually want.
101 validReceiveChunks map[RequestIndex]int
102 // Indexed by metadata piece, set to true if posted and pending a
104 metadataRequests []bool
105 sentHaves bitmap.Bitmap
107 // Stuff controlled by the remote peer.
110 peerRequests map[Request]*peerRequestState
111 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
113 // The pieces the peer has claimed to have.
114 _peerPieces roaring.Bitmap
115 // The peer has everything. This can occur due to a special message, when
116 // we may not even know the number of pieces in the torrent yet.
118 // The highest possible number of pieces the torrent could have based on
119 // communication with the peer. Generally only useful until we have the
121 peerMinPieces pieceIndex
122 // Pieces we've accepted chunks for from the peer.
123 peerTouchedPieces map[pieceIndex]struct{}
124 peerAllowedFast roaring.Bitmap
126 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
127 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
128 PeerClientName string
130 pieceInclination []int
131 _pieceRequestOrder prioritybitmap.PriorityBitmap
136 // Maintains the state of a BitTorrent-protocol based connection with a peer.
137 type PeerConn struct {
140 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
141 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
146 PeerExtensionBytes pp.PeerExtensionBits
148 // The actual Conn, used for closing, and setting socket options.
150 // The Reader and Writer for this Conn, with hooks installed for stats,
151 // limiting, deadlines etc.
155 messageWriter peerConnMsgWriter
157 uploadTimer *time.Timer
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.actualRequestState.Requests.IsEmpty() {
182 if !cn.actualRequestState.Interested {
188 haveAllowedFastRequests := false
189 cn.peerAllowedFast.Iterate(func(i uint32) bool {
190 haveAllowedFastRequests = roaringBitmapRangeCardinality(
191 &cn.actualRequestState.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.actualRequestState.Interested {
233 ret += time.Since(cn.lastBecameInterested)
238 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
239 if cn.peerSentHaveAll {
242 if !cn.t.haveInfo() {
245 return roaring.Flip(&cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
248 func (cn *PeerConn) 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 cn.peerSentHaveAll {
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 eventAgeString(t time.Time) string {
288 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
291 func (cn *PeerConn) connectionFlags() (ret string) {
293 ret += string([]byte{b})
295 if cn.cryptoMethod == mse.CryptoMethodRC4 {
297 } else if cn.headerEncrypted {
300 ret += string(cn.Discovery)
307 func (cn *PeerConn) utp() bool {
308 return parseNetworkString(cn.Network).Udp
311 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
312 func (cn *Peer) statusFlags() (ret string) {
314 ret += string([]byte{b})
316 if cn.actualRequestState.Interested {
323 ret += cn.connectionFlags()
325 if cn.peerInterested {
334 func (cn *Peer) downloadRate() float64 {
335 num := cn._stats.BytesReadUsefulData.Int64()
339 return float64(num) / cn.totalExpectingTime().Seconds()
342 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
343 ret = make(map[pieceIndex]int)
344 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
345 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
351 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
352 // \t isn't preserved in <pre> blocks?
353 if cn.closed.IsSet() {
354 fmt.Fprint(w, "CLOSED: ")
356 fmt.Fprintln(w, cn.connStatusString())
357 prio, err := cn.peerPriority()
358 prioStr := fmt.Sprintf("%08x", prio)
360 prioStr += ": " + err.Error()
362 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
363 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
364 eventAgeString(cn.lastMessageReceived),
365 eventAgeString(cn.completedHandshake),
366 eventAgeString(cn.lastHelpful()),
368 cn.totalExpectingTime(),
371 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
372 cn.completedString(),
373 len(cn.peerTouchedPieces),
374 &cn._stats.ChunksReadUseful,
375 &cn._stats.ChunksRead,
376 &cn._stats.ChunksWritten,
377 cn.actualRequestState.Requests.GetCardinality(),
378 cn.nominalMaxRequests(),
380 len(cn.peerRequests),
383 cn.downloadRate()/(1<<10),
385 fmt.Fprintf(w, " requested pieces:")
386 type pieceNumRequestsType struct {
390 var pieceNumRequests []pieceNumRequestsType
391 for piece, count := range cn.numRequestsByPiece() {
392 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
394 sort.Slice(pieceNumRequests, func(i, j int) bool {
395 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
397 for _, elem := range pieceNumRequests {
398 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
403 func (p *Peer) close() {
407 p.discardPieceInclination()
408 p._pieceRequestOrder.Clear()
411 p.t.decPeerPieceAvailability(p)
413 for _, f := range p.callbacks.PeerClosed {
418 func (cn *PeerConn) onClose() {
419 if cn.pex.IsEnabled() {
426 if cb := cn.callbacks.PeerConnClosed; cb != nil {
431 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
432 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
435 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
436 // https://github.com/pion/datachannel/issues/59 is fixed.
437 const writeBufferHighWaterLen = 1 << 15
439 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
440 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
441 func (cn *PeerConn) write(msg pp.Message) bool {
442 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
443 // We don't need to track bytes here because the connection's Writer has that behaviour injected
444 // (although there's some delay between us buffering the message, and the connection writer
445 // flushing it out.).
446 notFull := cn.messageWriter.write(msg)
447 // Last I checked only Piece messages affect stats, and we don't write those.
453 func (cn *PeerConn) requestMetadataPiece(index int) {
454 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
455 if eID == pp.ExtensionDeleteNumber {
458 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
461 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
462 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
463 for index >= len(cn.metadataRequests) {
464 cn.metadataRequests = append(cn.metadataRequests, false)
466 cn.metadataRequests[index] = true
469 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
470 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
473 // The actual value to use as the maximum outbound requests.
474 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
475 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 128))
478 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
479 ret = cn.cumulativeExpectedToReceiveChunks
480 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
481 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
487 func (cn *PeerConn) onPeerSentCancel(r Request) {
488 if _, ok := cn.peerRequests[r]; !ok {
489 torrent.Add("unexpected cancels received", 1)
492 if cn.fastEnabled() {
495 delete(cn.peerRequests, r)
499 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
504 more = msg(pp.Message{
507 if cn.fastEnabled() {
508 for r := range cn.peerRequests {
509 // TODO: Don't reject pieces in allowed fast set.
513 cn.peerRequests = nil
518 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
523 return msg(pp.Message{
528 func (cn *Peer) setInterested(interested bool) bool {
529 if cn.actualRequestState.Interested == interested {
532 cn.actualRequestState.Interested = interested
534 cn.lastBecameInterested = time.Now()
535 } else if !cn.lastBecameInterested.IsZero() {
536 cn.priorInterest += time.Since(cn.lastBecameInterested)
538 cn.updateExpectingChunks()
539 // log.Printf("%p: setting interest: %v", cn, interested)
540 return cn.writeInterested(interested)
543 func (pc *PeerConn) writeInterested(interested bool) bool {
544 return pc.write(pp.Message{
545 Type: func() pp.MessageType {
549 return pp.NotInterested
555 // The function takes a message to be sent, and returns true if more messages
557 type messageWriter func(pp.Message) bool
559 func (cn *Peer) shouldRequest(r RequestIndex) error {
560 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
561 if !cn.peerHasPiece(pi) {
562 return errors.New("requesting piece peer doesn't have")
564 if !cn.t.peerIsActive(cn) {
565 panic("requesting but not in active conns")
567 if cn.closed.IsSet() {
568 panic("requesting when connection is closed")
570 if cn.t.hashingPiece(pi) {
571 panic("piece is being hashed")
573 if cn.t.pieceQueuedForHash(pi) {
574 panic("piece is queued for hash")
576 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
577 panic("peer choking and piece not allowed fast")
582 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
583 if err := cn.shouldRequest(r); err != nil {
586 if cn.actualRequestState.Requests.Contains(r) {
589 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
590 return true, errors.New("too many outstanding requests")
592 cn.actualRequestState.Requests.Add(r)
593 if cn.validReceiveChunks == nil {
594 cn.validReceiveChunks = make(map[RequestIndex]int)
596 cn.validReceiveChunks[r]++
597 cn.t.pendingRequests[r]++
598 cn.updateExpectingChunks()
599 ppReq := cn.t.requestIndexToRequest(r)
600 for _, f := range cn.callbacks.SentRequest {
601 f(PeerRequestEvent{cn, ppReq})
603 return cn.peerImpl._request(ppReq), nil
606 func (me *PeerConn) _request(r Request) bool {
607 return me.write(pp.Message{
615 func (me *Peer) cancel(r RequestIndex) bool {
616 if me.deleteRequest(r) {
617 return me.peerImpl._cancel(me.t.requestIndexToRequest(r))
622 func (me *PeerConn) _cancel(r Request) bool {
623 return me.write(makeCancelMessage(r))
626 func (cn *PeerConn) fillWriteBuffer() {
627 if !cn.applyNextRequestState() {
630 if cn.pex.IsEnabled() {
631 if flow := cn.pex.Share(cn.write); !flow {
638 func (cn *PeerConn) have(piece pieceIndex) {
639 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
644 Index: pp.Integer(piece),
646 cn.sentHaves.Add(bitmap.BitIndex(piece))
649 func (cn *PeerConn) postBitfield() {
650 if cn.sentHaves.Len() != 0 {
651 panic("bitfield must be first have-related message sent")
653 if !cn.t.haveAnyPieces() {
658 Bitfield: cn.t.bitfield(),
660 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
663 func (cn *PeerConn) updateRequests() {
665 if cn.actualRequestState.Requests.GetCardinality() != 0 {
671 cn.t.cl.tickleRequester()
674 // Emits the indices in the Bitmaps bms in order, never repeating any index.
675 // skip is mutated during execution, and its initial values will never be
677 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
678 return func(cb iter.Callback) {
679 for _, bm := range bms {
681 func(_i interface{}) bool {
683 if skip.Contains(bitmap.BitIndex(i)) {
686 skip.Add(bitmap.BitIndex(i))
697 // check callers updaterequests
698 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
699 return cn._pieceRequestOrder.Remove(piece)
702 // This is distinct from Torrent piece priority, which is the user's
703 // preference. Connection piece priority is specific to a connection and is
704 // used to pseudorandomly avoid connections always requesting the same pieces
705 // and thus wasting effort.
706 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
707 tpp := cn.t.piecePriority(piece)
708 if !cn.peerHasPiece(piece) {
709 tpp = PiecePriorityNone
711 if tpp == PiecePriorityNone {
712 return cn.stopRequestingPiece(piece)
714 prio := cn.getPieceInclination()[piece]
715 return cn._pieceRequestOrder.Set(piece, prio)
718 func (cn *Peer) getPieceInclination() []int {
719 if cn.pieceInclination == nil {
720 cn.pieceInclination = cn.t.getConnPieceInclination()
722 return cn.pieceInclination
725 func (cn *Peer) discardPieceInclination() {
726 if cn.pieceInclination == nil {
729 cn.t.putPieceInclination(cn.pieceInclination)
730 cn.pieceInclination = nil
733 func (cn *Peer) peerPiecesChanged() {
735 prioritiesChanged := false
736 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
737 if cn.updatePiecePriority(i) {
738 prioritiesChanged = true
741 if prioritiesChanged {
745 cn.t.maybeDropMutuallyCompletePeer(cn)
748 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
749 if newMin > cn.peerMinPieces {
750 cn.peerMinPieces = newMin
754 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
755 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
756 return errors.New("invalid piece")
758 if cn.peerHasPiece(piece) {
761 cn.raisePeerMinPieces(piece + 1)
762 if !cn.peerHasPiece(piece) {
763 cn.t.incPieceAvailability(piece)
765 cn._peerPieces.Add(uint32(piece))
766 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
767 if cn.updatePiecePriority(piece) {
773 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
775 panic("expected bitfield length divisible by 8")
777 // We know that the last byte means that at most the last 7 bits are wasted.
778 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
779 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
780 // Ignore known excess pieces.
781 bf = bf[:cn.t.numPieces()]
783 pp := cn.newPeerPieces()
784 cn.peerSentHaveAll = false
785 for i, have := range bf {
787 cn.raisePeerMinPieces(pieceIndex(i) + 1)
788 if !pp.Contains(bitmap.BitIndex(i)) {
789 cn.t.incPieceAvailability(i)
792 if pp.Contains(bitmap.BitIndex(i)) {
793 cn.t.decPieceAvailability(i)
797 cn._peerPieces.Add(uint32(i))
799 cn._peerPieces.Remove(uint32(i))
802 cn.peerPiecesChanged()
806 func (cn *Peer) onPeerHasAllPieces() {
809 npp, pc := cn.newPeerPieces(), t.numPieces()
810 for i := 0; i < pc; i += 1 {
811 if !npp.Contains(bitmap.BitIndex(i)) {
812 t.incPieceAvailability(i)
816 cn.peerSentHaveAll = true
817 cn._peerPieces.Clear()
818 cn.peerPiecesChanged()
821 func (cn *PeerConn) onPeerSentHaveAll() error {
822 cn.onPeerHasAllPieces()
826 func (cn *PeerConn) peerSentHaveNone() error {
827 cn.t.decPeerPieceAvailability(&cn.Peer)
828 cn._peerPieces.Clear()
829 cn.peerSentHaveAll = false
830 cn.peerPiecesChanged()
834 func (c *PeerConn) requestPendingMetadata() {
838 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
839 // Peer doesn't support this.
842 // Request metadata pieces that we don't have in a random order.
844 for index := 0; index < c.t.metadataPieceCount(); index++ {
845 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
846 pending = append(pending, index)
849 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
850 for _, i := range pending {
851 c.requestMetadataPiece(i)
855 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
856 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
857 if msg.Type == pp.Extended {
858 for name, id := range cn.PeerExtensionIDs {
859 if id != msg.ExtendedID {
862 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
865 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
868 // After handshake, we know what Torrent and Client stats to include for a
870 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
876 // All ConnStats that include this connection. Some objects are not known
877 // until the handshake is complete, after which it's expected to reconcile the
879 func (cn *Peer) allStats(f func(*ConnStats)) {
881 if cn.reconciledHandshakeStats {
882 cn.postHandshakeStats(f)
886 func (cn *PeerConn) wroteBytes(n int64) {
887 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
890 func (cn *PeerConn) readBytes(n int64) {
891 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
894 // Returns whether the connection could be useful to us. We're seeding and
895 // they want data, we don't have metainfo and they can provide it, etc.
896 func (c *Peer) useful() bool {
898 if c.closed.IsSet() {
902 return c.supportsExtension("ut_metadata")
904 if t.seeding() && c.peerInterested {
907 if c.peerHasWantedPieces() {
913 func (c *Peer) lastHelpful() (ret time.Time) {
914 ret = c.lastUsefulChunkReceived
915 if c.t.seeding() && c.lastChunkSent.After(ret) {
916 ret = c.lastChunkSent
921 func (c *PeerConn) fastEnabled() bool {
922 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
925 func (c *PeerConn) reject(r Request) {
926 if !c.fastEnabled() {
927 panic("fast not enabled")
929 c.write(r.ToMsg(pp.Reject))
930 delete(c.peerRequests, r)
933 func (c *PeerConn) onReadRequest(r Request) error {
934 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
935 if _, ok := c.peerRequests[r]; ok {
936 torrent.Add("duplicate requests received", 1)
940 torrent.Add("requests received while choking", 1)
942 torrent.Add("requests rejected while choking", 1)
947 // TODO: What if they've already requested this?
948 if len(c.peerRequests) >= localClientReqq {
949 torrent.Add("requests received while queue full", 1)
953 // BEP 6 says we may close here if we choose.
956 if !c.t.havePiece(pieceIndex(r.Index)) {
957 // This isn't necessarily them screwing up. We can drop pieces
958 // from our storage, and can't communicate this to peers
959 // except by reconnecting.
960 requestsReceivedForMissingPieces.Add(1)
961 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
963 // Check this after we know we have the piece, so that the piece length will be known.
964 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
965 torrent.Add("bad requests received", 1)
966 return errors.New("bad Request")
968 if c.peerRequests == nil {
969 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
971 value := &peerRequestState{}
972 c.peerRequests[r] = value
973 go c.peerRequestDataReader(r, value)
978 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
979 b, err := readPeerRequestData(r, c)
981 defer c.locker().Unlock()
983 c.peerRequestDataReadFailed(err, r)
986 panic("data must be non-nil to trigger send")
993 // If this is maintained correctly, we might be able to support optional synchronous reading for
994 // chunk sending, the way it used to work.
995 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
996 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
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 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1040 // exit. Returning will end the connection.
1041 func (c *PeerConn) mainReadLoop() (err error) {
1044 torrent.Add("connection.mainReadLoop returned with error", 1)
1046 torrent.Add("connection.mainReadLoop returned with no error", 1)
1052 decoder := pp.Decoder{
1053 R: bufio.NewReaderSize(c.r, 1<<17),
1054 MaxLength: 256 * 1024,
1062 err = decoder.Decode(&msg)
1064 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1067 if t.closed.IsSet() || c.closed.IsSet() {
1073 c.lastMessageReceived = time.Now()
1075 receivedKeepalives.Add(1)
1078 messageTypesReceived.Add(msg.Type.String(), 1)
1079 if msg.Type.FastExtension() && !c.fastEnabled() {
1080 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1081 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1085 c.peerChoking = true
1086 if !c.fastEnabled() {
1087 c.deleteAllRequests()
1089 // We can then reset our interest.
1091 c.updateExpectingChunks()
1093 c.peerChoking = false
1095 c.updateExpectingChunks()
1097 c.peerInterested = true
1099 case pp.NotInterested:
1100 c.peerInterested = false
1101 // We don't clear their requests since it isn't clear in the spec.
1102 // We'll probably choke them for this, which will clear them if
1103 // appropriate, and is clearly specified.
1105 err = c.peerSentHave(pieceIndex(msg.Index))
1107 err = c.peerSentBitfield(msg.Bitfield)
1109 r := newRequestFromMessage(&msg)
1110 err = c.onReadRequest(r)
1112 c.doChunkReadStats(int64(len(msg.Piece)))
1113 err = c.receiveChunk(&msg)
1114 if len(msg.Piece) == int(t.chunkSize) {
1115 t.chunkPool.Put(&msg.Piece)
1118 err = fmt.Errorf("receiving chunk: %w", err)
1121 req := newRequestFromMessage(&msg)
1122 c.onPeerSentCancel(req)
1124 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1128 pingAddr := net.UDPAddr{
1133 pingAddr.Port = int(msg.Port)
1135 cl.eachDhtServer(func(s DhtServer) {
1136 go s.Ping(&pingAddr)
1139 torrent.Add("suggests received", 1)
1140 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1143 err = c.onPeerSentHaveAll()
1145 err = c.peerSentHaveNone()
1147 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1148 case pp.AllowedFast:
1149 torrent.Add("allowed fasts received", 1)
1150 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1151 c.peerAllowedFast.Add(bitmap.BitIndex(msg.Index))
1154 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1156 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1164 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1165 if c.deleteRequest(r) {
1166 c.decExpectedChunkReceive(r)
1170 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1171 count := c.validReceiveChunks[r]
1173 delete(c.validReceiveChunks, r)
1174 } else if count > 1 {
1175 c.validReceiveChunks[r] = count - 1
1181 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1183 // TODO: Should we still do this?
1185 // These clients use their own extension IDs for outgoing message
1186 // types, which is incorrect.
1187 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1195 case pp.HandshakeExtendedID:
1196 var d pp.ExtendedHandshakeMessage
1197 if err := bencode.Unmarshal(payload, &d); err != nil {
1198 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1199 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1201 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1204 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1206 c.PeerMaxRequests = d.Reqq
1208 c.PeerClientName = d.V
1209 if c.PeerExtensionIDs == nil {
1210 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1212 c.PeerListenPort = d.Port
1213 c.PeerPrefersEncryption = d.Encryption
1214 for name, id := range d.M {
1215 if _, ok := c.PeerExtensionIDs[name]; !ok {
1216 peersSupportingExtension.Add(string(name), 1)
1218 c.PeerExtensionIDs[name] = id
1220 if d.MetadataSize != 0 {
1221 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1222 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1225 c.requestPendingMetadata()
1226 if !t.cl.config.DisablePEX {
1227 t.pex.Add(c) // we learnt enough now
1231 case metadataExtendedId:
1232 err := cl.gotMetadataExtensionMsg(payload, t, c)
1234 return fmt.Errorf("handling metadata extension message: %w", err)
1238 if !c.pex.IsEnabled() {
1239 return nil // or hang-up maybe?
1241 return c.pex.Recv(payload)
1243 return fmt.Errorf("unexpected extended message ID: %v", id)
1247 // Set both the Reader and Writer for the connection from a single ReadWriter.
1248 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1253 // Returns the Reader and Writer as a combined ReadWriter.
1254 func (cn *PeerConn) rw() io.ReadWriter {
1261 func (c *Peer) doChunkReadStats(size int64) {
1262 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1265 // Handle a received chunk from a peer.
1266 func (c *Peer) receiveChunk(msg *pp.Message) error {
1267 chunksReceived.Add("total", 1)
1269 ppReq := newRequestFromMessage(msg)
1270 req := c.t.requestIndexFromRequest(ppReq)
1273 chunksReceived.Add("while choked", 1)
1276 if c.validReceiveChunks[req] <= 0 {
1277 chunksReceived.Add("unexpected", 1)
1278 return errors.New("received unexpected chunk")
1280 c.decExpectedChunkReceive(req)
1282 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1283 chunksReceived.Add("due to allowed fast", 1)
1286 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1287 // have actually already received the piece, while we have the Client unlocked to write the data
1289 deletedRequest := false
1291 if c.actualRequestState.Requests.Contains(req) {
1292 for _, f := range c.callbacks.ReceivedRequested {
1293 f(PeerMessageEvent{c, msg})
1296 // Request has been satisfied.
1297 if c.deleteRequest(req) {
1298 deletedRequest = true
1300 c._chunksReceivedWhileExpecting++
1303 chunksReceived.Add("unwanted", 1)
1310 // Do we actually want this chunk?
1311 if t.haveChunk(ppReq) {
1312 chunksReceived.Add("wasted", 1)
1313 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1317 piece := &t.pieces[ppReq.Index]
1319 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1320 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1322 c.piecesReceivedSinceLastRequestUpdate++
1324 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1326 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1327 f(ReceivedUsefulDataEvent{c, msg})
1329 c.lastUsefulChunkReceived = time.Now()
1331 // Need to record that it hasn't been written yet, before we attempt to do
1332 // anything with it.
1333 piece.incrementPendingWrites()
1334 // Record that we have the chunk, so we aren't trying to download it while
1335 // waiting for it to be written to storage.
1336 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1338 // Cancel pending requests for this chunk from *other* peers.
1339 t.iterPeers(func(p *Peer) {
1346 err := func() error {
1349 concurrentChunkWrites.Add(1)
1350 defer concurrentChunkWrites.Add(-1)
1351 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1352 // number of connections. We write inline with receiving the chunk (with this lock dance),
1353 // because we want to handle errors synchronously and I haven't thought of a nice way to
1354 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1356 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1359 piece.decrementPendingWrites()
1362 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1364 //t.updatePieceCompletion(pieceIndex(msg.Index))
1365 t.onWriteChunkErr(err)
1369 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1371 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1372 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1373 t.queuePieceCheck(pieceIndex(ppReq.Index))
1374 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1375 // chunk status (such as the haveChunk call above) to have to check all the various other
1376 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1377 // that chunk pieces are pended at an appropriate time later however.
1380 cl.event.Broadcast()
1381 // We do this because we've written a chunk, and may change PieceState.Partial.
1382 t.publishPieceChange(pieceIndex(ppReq.Index))
1387 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1388 if c.peerTouchedPieces == nil {
1389 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1391 c.peerTouchedPieces[piece] = struct{}{}
1392 ds := &c.t.pieces[piece].dirtiers
1394 *ds = make(map[*Peer]struct{})
1396 (*ds)[c] = struct{}{}
1399 func (c *PeerConn) uploadAllowed() bool {
1400 if c.t.cl.config.NoUpload {
1403 if c.t.dataUploadDisallowed {
1409 if !c.peerHasWantedPieces() {
1412 // Don't upload more than 100 KiB more than we download.
1413 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1419 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1420 if c.uploadTimer == nil {
1421 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1423 c.uploadTimer.Reset(delay)
1427 // Also handles choking and unchoking of the remote peer.
1428 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1429 // Breaking or completing this loop means we don't want to upload to the
1430 // peer anymore, and we choke them.
1432 for c.uploadAllowed() {
1433 // We want to upload to the peer.
1434 if !c.unchoke(msg) {
1437 for r, state := range c.peerRequests {
1438 if state.data == nil {
1441 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1443 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1445 delay := res.Delay()
1448 c.setRetryUploadTimer(delay)
1449 // Hard to say what to return here.
1452 more := c.sendChunk(r, msg, state)
1453 delete(c.peerRequests, r)
1464 func (cn *PeerConn) drop() {
1465 cn.t.dropConnection(cn)
1468 func (cn *Peer) netGoodPiecesDirtied() int64 {
1469 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1472 func (c *Peer) peerHasWantedPieces() bool {
1473 return !c._pieceRequestOrder.IsEmpty()
1476 func (c *Peer) deleteRequest(r RequestIndex) bool {
1477 c.nextRequestState.Requests.Remove(r)
1478 if !c.actualRequestState.Requests.CheckedRemove(r) {
1481 for _, f := range c.callbacks.DeletedRequest {
1482 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1484 c.updateExpectingChunks()
1485 pr := c.t.pendingRequests
1497 func (c *Peer) deleteAllRequests() {
1498 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1502 if !c.actualRequestState.Requests.IsEmpty() {
1503 panic(c.actualRequestState.Requests.GetCardinality())
1505 c.nextRequestState.Requests.Clear()
1506 // for c := range c.t.conns {
1511 // This is called when something has changed that should wake the writer, such as putting stuff into
1512 // the writeBuffer, or changing some state that the writer can act on.
1513 func (c *PeerConn) tickleWriter() {
1514 c.messageWriter.writeCond.Broadcast()
1517 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1518 c.lastChunkSent = time.Now()
1519 return msg(pp.Message{
1527 func (c *PeerConn) setTorrent(t *Torrent) {
1529 panic("connection already associated with a torrent")
1532 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1533 t.reconcileHandshakeStats(c)
1536 func (c *Peer) peerPriority() (peerPriority, error) {
1537 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1540 func (c *Peer) remoteIp() net.IP {
1541 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1542 return net.ParseIP(host)
1545 func (c *Peer) remoteIpPort() IpPort {
1546 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1547 return IpPort{ipa.IP, uint16(ipa.Port)}
1550 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1551 f := pp.PexPeerFlags(0)
1552 if c.PeerPrefersEncryption {
1553 f |= pp.PexPrefersEncryption
1556 f |= pp.PexOutgoingConn
1559 f |= pp.PexSupportsUtp
1564 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1565 // advertised listen port.
1566 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1567 if !c.outgoing && c.PeerListenPort != 0 {
1568 switch addr := c.RemoteAddr.(type) {
1571 dialAddr.Port = c.PeerListenPort
1575 dialAddr.Port = c.PeerListenPort
1582 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1583 f := c.pexPeerFlags()
1584 addr := c.dialAddr()
1585 return pexEvent{t, addr, f}
1588 func (c *PeerConn) String() string {
1589 return fmt.Sprintf("connection %p", c)
1592 func (c *Peer) trust() connectionTrust {
1593 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1596 type connectionTrust struct {
1598 NetGoodPiecesDirted int64
1601 func (l connectionTrust) Less(r connectionTrust) bool {
1602 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1605 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1606 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1607 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1609 defer cn.locker().RUnlock()
1610 return cn.newPeerPieces()
1613 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1614 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1615 // TODO: Can we use copy on write?
1616 ret := cn._peerPieces.Clone()
1617 if cn.peerSentHaveAll {
1618 if cn.t.haveInfo() {
1619 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1621 ret.AddRange(0, bitmap.ToEnd)
1627 func (cn *Peer) stats() *ConnStats {
1631 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1632 pc, ok := p.peerImpl.(*PeerConn)
1636 func (p *PeerConn) onNextRequestStateChanged() {