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/multiless"
22 "github.com/anacrolix/chansync"
23 "github.com/anacrolix/torrent/bencode"
24 "github.com/anacrolix/torrent/metainfo"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
27 request_strategy "github.com/anacrolix/torrent/request-strategy"
30 type PeerSource string
33 PeerSourceTracker = "Tr"
34 PeerSourceIncoming = "I"
35 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
36 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
38 // The peer was given directly, such as through a magnet link.
39 PeerSourceDirect = "M"
42 type peerRequestState struct {
46 type PeerRemoteAddr interface {
50 // Since we have to store all the requests in memory, we can't reasonably exceed what would be
51 // indexable with the memory space available.
54 requestState = request_strategy.PeerNextRequestState
58 // First to ensure 64-bit alignment for atomics. See #262.
68 RemoteAddr PeerRemoteAddr
69 // True if the connection is operating over MSE obfuscation.
71 cryptoMethod mse.CryptoMethod
74 closed chansync.SetOnce
75 // Set true after we've added our ConnStats generated during handshake to
76 // other ConnStat instances as determined when the *Torrent became known.
77 reconciledHandshakeStats bool
79 lastMessageReceived time.Time
80 completedHandshake time.Time
81 lastUsefulChunkReceived time.Time
82 lastChunkSent time.Time
84 // Stuff controlled by the local peer.
85 needRequestUpdate string
86 actualRequestState requestState
87 updateRequestsTimer *time.Timer
88 cancelledRequests roaring.Bitmap
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
100 // latency, buffering, and implementation differences, we may receive
101 // chunks that are no longer in the set of requests actually want.
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 string
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.
143 // The Reader and Writer for this Conn, with hooks installed for stats,
144 // limiting, deadlines etc.
148 messageWriter peerConnMsgWriter
150 uploadTimer *time.Timer
153 // The pieces the peer has claimed to have.
154 _peerPieces roaring.Bitmap
155 // The peer has everything. This can occur due to a special message, when
156 // we may not even know the number of pieces in the torrent yet.
160 func (cn *PeerConn) connStatusString() string {
161 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
164 func (cn *Peer) updateExpectingChunks() {
165 if cn.expectingChunks() {
166 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
167 cn.lastStartedExpectingToReceiveChunks = time.Now()
170 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
171 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
172 cn.lastStartedExpectingToReceiveChunks = time.Time{}
177 func (cn *Peer) expectingChunks() bool {
178 if cn.actualRequestState.Requests.IsEmpty() {
181 if !cn.actualRequestState.Interested {
187 haveAllowedFastRequests := false
188 cn.peerAllowedFast.Iterate(func(i uint32) bool {
189 haveAllowedFastRequests = roaringBitmapRangeCardinality(
190 &cn.actualRequestState.Requests,
191 cn.t.pieceRequestIndexOffset(pieceIndex(i)),
192 cn.t.pieceRequestIndexOffset(pieceIndex(i+1)),
194 return !haveAllowedFastRequests
196 return haveAllowedFastRequests
199 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
200 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
203 // Returns true if the connection is over IPv6.
204 func (cn *PeerConn) ipv6() bool {
209 return len(ip) == net.IPv6len
212 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
213 // specification for this.
214 func (cn *PeerConn) isPreferredDirection() bool {
215 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
218 // Returns whether the left connection should be preferred over the right one,
219 // considering only their networking properties. If ok is false, we can't
221 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
223 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
224 ml.NextBool(!l.utp(), !r.utp())
225 ml.NextBool(l.ipv6(), r.ipv6())
229 func (cn *Peer) cumInterest() time.Duration {
230 ret := cn.priorInterest
231 if cn.actualRequestState.Interested {
232 ret += time.Since(cn.lastBecameInterested)
237 func (cn *PeerConn) peerHasAllPieces() (all bool, known bool) {
238 if cn.peerSentHaveAll {
241 if !cn.t.haveInfo() {
244 return roaring.Flip(&cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
247 func (cn *Peer) locker() *lockWithDeferreds {
248 return cn.t.cl.locker()
251 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
252 _, ok := cn.PeerExtensionIDs[ext]
256 // The best guess at number of pieces in the torrent for this peer.
257 func (cn *Peer) bestPeerNumPieces() pieceIndex {
259 return cn.t.numPieces()
261 return cn.peerMinPieces
264 func (cn *Peer) completedString() string {
265 have := pieceIndex(cn.peerPieces().GetCardinality())
266 if all, _ := cn.peerHasAllPieces(); all {
267 have = cn.bestPeerNumPieces()
269 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
272 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
273 cn.setNumPieces(info.NumPieces())
276 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
277 // receiving badly sized BITFIELD, or invalid HAVE messages.
278 func (cn *PeerConn) setNumPieces(num pieceIndex) {
279 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
280 cn.peerPiecesChanged()
283 func (cn *PeerConn) peerPieces() *roaring.Bitmap {
284 return &cn._peerPieces
287 func eventAgeString(t time.Time) string {
291 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
294 func (cn *PeerConn) connectionFlags() (ret string) {
296 ret += string([]byte{b})
298 if cn.cryptoMethod == mse.CryptoMethodRC4 {
300 } else if cn.headerEncrypted {
303 ret += string(cn.Discovery)
310 func (cn *PeerConn) utp() bool {
311 return parseNetworkString(cn.Network).Udp
314 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
315 func (cn *Peer) statusFlags() (ret string) {
317 ret += string([]byte{b})
319 if cn.actualRequestState.Interested {
326 ret += cn.connectionFlags()
328 if cn.peerInterested {
337 func (cn *Peer) downloadRate() float64 {
338 num := cn._stats.BytesReadUsefulData.Int64()
342 return float64(num) / cn.totalExpectingTime().Seconds()
345 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
346 ret = make(map[pieceIndex]int)
347 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
348 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
354 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
355 // \t isn't preserved in <pre> blocks?
356 if cn.closed.IsSet() {
357 fmt.Fprint(w, "CLOSED: ")
359 fmt.Fprintln(w, cn.connStatusString())
360 prio, err := cn.peerPriority()
361 prioStr := fmt.Sprintf("%08x", prio)
363 prioStr += ": " + err.Error()
365 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
366 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
367 eventAgeString(cn.lastMessageReceived),
368 eventAgeString(cn.completedHandshake),
369 eventAgeString(cn.lastHelpful()),
371 cn.totalExpectingTime(),
374 " %s completed, %d pieces touched, good chunks: %v/%v:%v reqq: %d-%v/(%d/%d):%d/%d, flags: %s, dr: %.1f KiB/s\n",
375 cn.completedString(),
376 len(cn.peerTouchedPieces),
377 &cn._stats.ChunksReadUseful,
378 &cn._stats.ChunksRead,
379 &cn._stats.ChunksWritten,
380 cn.actualRequestState.Requests.GetCardinality(),
381 cn.cancelledRequests.GetCardinality(),
382 cn.nominalMaxRequests(),
384 len(cn.peerRequests),
387 cn.downloadRate()/(1<<10),
389 fmt.Fprintf(w, " requested pieces:")
390 type pieceNumRequestsType struct {
394 var pieceNumRequests []pieceNumRequestsType
395 for piece, count := range cn.numRequestsByPiece() {
396 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
398 sort.Slice(pieceNumRequests, func(i, j int) bool {
399 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
401 for _, elem := range pieceNumRequests {
402 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
407 func (p *Peer) close() {
411 if p.updateRequestsTimer != nil {
412 p.updateRequestsTimer.Stop()
416 p.t.decPeerPieceAvailability(p)
418 for _, f := range p.callbacks.PeerClosed {
423 func (cn *PeerConn) onClose() {
424 if cn.pex.IsEnabled() {
431 if cb := cn.callbacks.PeerConnClosed; cb != nil {
436 // Peer definitely has a piece, for purposes of requesting. So it's not sufficient that we think
437 // they do (known=true).
438 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
439 if all, known := cn.peerHasAllPieces(); all && known {
442 return cn.peerPieces().ContainsInt(piece)
445 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
446 // https://github.com/pion/datachannel/issues/59 is fixed.
447 const writeBufferHighWaterLen = 1 << 15
449 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
450 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
451 func (cn *PeerConn) write(msg pp.Message) bool {
452 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
453 // We don't need to track bytes here because the connection's Writer has that behaviour injected
454 // (although there's some delay between us buffering the message, and the connection writer
455 // flushing it out.).
456 notFull := cn.messageWriter.write(msg)
457 // Last I checked only Piece messages affect stats, and we don't write those.
463 func (cn *PeerConn) requestMetadataPiece(index int) {
464 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
465 if eID == pp.ExtensionDeleteNumber {
468 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
471 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
472 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
473 for index >= len(cn.metadataRequests) {
474 cn.metadataRequests = append(cn.metadataRequests, false)
476 cn.metadataRequests[index] = true
479 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
480 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
483 // The actual value to use as the maximum outbound requests.
484 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
485 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 2048))
488 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
489 ret = cn.cumulativeExpectedToReceiveChunks
490 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
491 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
496 func (cn *PeerConn) onPeerSentCancel(r Request) {
497 if _, ok := cn.peerRequests[r]; !ok {
498 torrent.Add("unexpected cancels received", 1)
501 if cn.fastEnabled() {
504 delete(cn.peerRequests, r)
508 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
513 more = msg(pp.Message{
516 if cn.fastEnabled() {
517 for r := range cn.peerRequests {
518 // TODO: Don't reject pieces in allowed fast set.
522 cn.peerRequests = nil
527 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
532 return msg(pp.Message{
537 func (cn *Peer) setInterested(interested bool) bool {
538 if cn.actualRequestState.Interested == interested {
541 cn.actualRequestState.Interested = interested
543 cn.lastBecameInterested = time.Now()
544 } else if !cn.lastBecameInterested.IsZero() {
545 cn.priorInterest += time.Since(cn.lastBecameInterested)
547 cn.updateExpectingChunks()
548 // log.Printf("%p: setting interest: %v", cn, interested)
549 return cn.writeInterested(interested)
552 func (pc *PeerConn) writeInterested(interested bool) bool {
553 return pc.write(pp.Message{
554 Type: func() pp.MessageType {
558 return pp.NotInterested
564 // The function takes a message to be sent, and returns true if more messages
566 type messageWriter func(pp.Message) bool
568 // This function seems to only used by Peer.request. It's all logic checks, so maybe we can no-op it
569 // when we want to go fast.
570 func (cn *Peer) shouldRequest(r RequestIndex) error {
571 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
572 if !cn.peerHasPiece(pi) {
573 return errors.New("requesting piece peer doesn't have")
575 if !cn.t.peerIsActive(cn) {
576 panic("requesting but not in active conns")
578 if cn.closed.IsSet() {
579 panic("requesting when connection is closed")
581 if cn.t.hashingPiece(pi) {
582 panic("piece is being hashed")
584 if cn.t.pieceQueuedForHash(pi) {
585 panic("piece is queued for hash")
587 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
588 // This could occur if we made a request with the fast extension, and then got choked and
589 // haven't had the request rejected yet.
590 if !cn.actualRequestState.Requests.Contains(r) {
591 panic("peer choking and piece not allowed fast")
597 func (cn *Peer) mustRequest(r RequestIndex) bool {
598 more, err := cn.request(r)
605 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
606 if err := cn.shouldRequest(r); err != nil {
609 if cn.actualRequestState.Requests.Contains(r) {
612 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
613 return true, errors.New("too many outstanding requests")
615 cn.actualRequestState.Requests.Add(r)
616 if cn.validReceiveChunks == nil {
617 cn.validReceiveChunks = make(map[RequestIndex]int)
619 cn.validReceiveChunks[r]++
620 cn.t.pendingRequests.Inc(r)
621 cn.updateExpectingChunks()
622 ppReq := cn.t.requestIndexToRequest(r)
623 for _, f := range cn.callbacks.SentRequest {
624 f(PeerRequestEvent{cn, ppReq})
626 return cn.peerImpl._request(ppReq), nil
629 func (me *PeerConn) _request(r Request) bool {
630 return me.write(pp.Message{
638 func (me *Peer) cancel(r RequestIndex) bool {
639 if !me.actualRequestState.Requests.Contains(r) {
645 func (me *PeerConn) _cancel(r RequestIndex) bool {
646 if me.cancelledRequests.Contains(r) {
647 // Already cancelled and waiting for a response.
650 if me.fastEnabled() {
651 me.cancelledRequests.Add(r)
653 if !me.deleteRequest(r) {
654 panic("request not existing should have been guarded")
656 if me.isLowOnRequests() {
657 me.updateRequests("Peer.cancel")
660 return me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
663 func (cn *PeerConn) fillWriteBuffer() {
664 if !cn.maybeUpdateActualRequestState() {
667 if cn.pex.IsEnabled() {
668 if flow := cn.pex.Share(cn.write); !flow {
675 func (cn *PeerConn) have(piece pieceIndex) {
676 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
681 Index: pp.Integer(piece),
683 cn.sentHaves.Add(bitmap.BitIndex(piece))
686 func (cn *PeerConn) postBitfield() {
687 if cn.sentHaves.Len() != 0 {
688 panic("bitfield must be first have-related message sent")
690 if !cn.t.haveAnyPieces() {
695 Bitfield: cn.t.bitfield(),
697 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
700 // Sets a reason to update requests, and if there wasn't already one, handle it.
701 func (cn *Peer) updateRequests(reason string) {
702 if cn.needRequestUpdate != "" {
705 cn.needRequestUpdate = reason
706 cn.handleUpdateRequests()
709 func (cn *PeerConn) handleUpdateRequests() {
710 // The writer determines the request state as needed when it can write.
714 // Emits the indices in the Bitmaps bms in order, never repeating any index.
715 // skip is mutated during execution, and its initial values will never be
717 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
718 return func(cb iter.Callback) {
719 for _, bm := range bms {
721 func(_i interface{}) bool {
723 if skip.Contains(bitmap.BitIndex(i)) {
726 skip.Add(bitmap.BitIndex(i))
737 func (cn *Peer) peerPiecesChanged() {
738 cn.t.maybeDropMutuallyCompletePeer(cn)
741 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
742 if newMin > cn.peerMinPieces {
743 cn.peerMinPieces = newMin
747 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
748 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
749 return errors.New("invalid piece")
751 if cn.peerHasPiece(piece) {
754 cn.raisePeerMinPieces(piece + 1)
755 if !cn.peerHasPiece(piece) {
756 cn.t.incPieceAvailability(piece)
758 cn._peerPieces.Add(uint32(piece))
759 if cn.t.wantPieceIndex(piece) {
760 cn.updateRequests("have")
762 cn.peerPiecesChanged()
766 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
768 panic("expected bitfield length divisible by 8")
770 // We know that the last byte means that at most the last 7 bits are wasted.
771 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
772 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
773 // Ignore known excess pieces.
774 bf = bf[:cn.t.numPieces()]
776 pp := cn.newPeerPieces()
777 cn.peerSentHaveAll = false
778 for i, have := range bf {
780 cn.raisePeerMinPieces(pieceIndex(i) + 1)
781 if !pp.Contains(bitmap.BitIndex(i)) {
782 cn.t.incPieceAvailability(i)
785 if pp.Contains(bitmap.BitIndex(i)) {
786 cn.t.decPieceAvailability(i)
790 cn._peerPieces.Add(uint32(i))
791 if cn.t.wantPieceIndex(i) {
792 cn.updateRequests("bitfield")
795 cn._peerPieces.Remove(uint32(i))
798 cn.peerPiecesChanged()
802 func (cn *PeerConn) onPeerHasAllPieces() {
805 npp, pc := cn.newPeerPieces(), t.numPieces()
806 for i := 0; i < pc; i += 1 {
807 if !npp.Contains(bitmap.BitIndex(i)) {
808 t.incPieceAvailability(i)
812 cn.peerSentHaveAll = true
813 cn._peerPieces.Clear()
814 if !cn.t._pendingPieces.IsEmpty() {
815 cn.updateRequests("Peer.onPeerHasAllPieces")
817 cn.peerPiecesChanged()
820 func (cn *PeerConn) onPeerSentHaveAll() error {
821 cn.onPeerHasAllPieces()
825 func (cn *PeerConn) peerSentHaveNone() error {
826 cn.t.decPeerPieceAvailability(&cn.Peer)
827 cn._peerPieces.Clear()
828 cn.peerSentHaveAll = false
829 cn.peerPiecesChanged()
833 func (c *PeerConn) requestPendingMetadata() {
837 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
838 // Peer doesn't support this.
841 // Request metadata pieces that we don't have in a random order.
843 for index := 0; index < c.t.metadataPieceCount(); index++ {
844 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
845 pending = append(pending, index)
848 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
849 for _, i := range pending {
850 c.requestMetadataPiece(i)
854 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
855 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
856 if msg.Type == pp.Extended {
857 for name, id := range cn.PeerExtensionIDs {
858 if id != msg.ExtendedID {
861 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
864 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
867 // After handshake, we know what Torrent and Client stats to include for a
869 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
875 // All ConnStats that include this connection. Some objects are not known
876 // until the handshake is complete, after which it's expected to reconcile the
878 func (cn *Peer) allStats(f func(*ConnStats)) {
880 if cn.reconciledHandshakeStats {
881 cn.postHandshakeStats(f)
885 func (cn *PeerConn) wroteBytes(n int64) {
886 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
889 func (cn *Peer) readBytes(n int64) {
890 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
893 // Returns whether the connection could be useful to us. We're seeding and
894 // they want data, we don't have metainfo and they can provide it, etc.
895 func (c *Peer) useful() bool {
897 if c.closed.IsSet() {
901 return c.supportsExtension("ut_metadata")
903 if t.seeding() && c.peerInterested {
906 if c.peerHasWantedPieces() {
912 func (c *Peer) lastHelpful() (ret time.Time) {
913 ret = c.lastUsefulChunkReceived
914 if c.t.seeding() && c.lastChunkSent.After(ret) {
915 ret = c.lastChunkSent
920 func (c *PeerConn) fastEnabled() bool {
921 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
924 func (c *PeerConn) reject(r Request) {
925 if !c.fastEnabled() {
926 panic("fast not enabled")
928 c.write(r.ToMsg(pp.Reject))
929 delete(c.peerRequests, r)
932 func (c *PeerConn) onReadRequest(r Request) error {
933 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
934 if _, ok := c.peerRequests[r]; ok {
935 torrent.Add("duplicate requests received", 1)
939 torrent.Add("requests received while choking", 1)
941 torrent.Add("requests rejected while choking", 1)
946 // TODO: What if they've already requested this?
947 if len(c.peerRequests) >= localClientReqq {
948 torrent.Add("requests received while queue full", 1)
952 // BEP 6 says we may close here if we choose.
955 if !c.t.havePiece(pieceIndex(r.Index)) {
956 // This isn't necessarily them screwing up. We can drop pieces
957 // from our storage, and can't communicate this to peers
958 // except by reconnecting.
959 requestsReceivedForMissingPieces.Add(1)
960 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
962 // Check this after we know we have the piece, so that the piece length will be known.
963 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
964 torrent.Add("bad requests received", 1)
965 return errors.New("bad Request")
967 if c.peerRequests == nil {
968 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
970 value := &peerRequestState{}
971 c.peerRequests[r] = value
972 go c.peerRequestDataReader(r, value)
977 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
978 b, err := readPeerRequestData(r, c)
980 defer c.locker().Unlock()
982 c.peerRequestDataReadFailed(err, r)
985 panic("data must be non-nil to trigger send")
992 // If this is maintained correctly, we might be able to support optional synchronous reading for
993 // chunk sending, the way it used to work.
994 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
995 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
996 if c.t.closed.IsSet() {
999 i := pieceIndex(r.Index)
1000 if c.t.pieceComplete(i) {
1001 // There used to be more code here that just duplicated the following break. Piece
1002 // completions are currently cached, so I'm not sure how helpful this update is, except to
1003 // pull any completion changes pushed to the storage backend in failed reads that got us
1005 c.t.updatePieceCompletion(i)
1007 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
1008 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
1009 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1010 // next connect. TODO: Support rejecting here too.
1012 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1017 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1018 b := make([]byte, r.Length)
1019 p := c.t.info.Piece(int(r.Index))
1020 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1027 panic("expected error")
1033 func runSafeExtraneous(f func()) {
1041 func (c *PeerConn) logProtocolBehaviour(level log.Level, format string, arg ...interface{}) {
1042 c.logger.WithLevel(level).WithContextText(fmt.Sprintf(
1043 "peer id %q, ext v %q", c.PeerID, c.PeerClientName,
1044 )).SkipCallers(1).Printf(format, arg...)
1047 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1048 // exit. Returning will end the connection.
1049 func (c *PeerConn) mainReadLoop() (err error) {
1052 torrent.Add("connection.mainReadLoop returned with error", 1)
1054 torrent.Add("connection.mainReadLoop returned with no error", 1)
1060 decoder := pp.Decoder{
1061 R: bufio.NewReaderSize(c.r, 1<<17),
1062 MaxLength: 256 * 1024,
1070 err = decoder.Decode(&msg)
1072 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1075 if t.closed.IsSet() || c.closed.IsSet() {
1081 c.lastMessageReceived = time.Now()
1083 receivedKeepalives.Add(1)
1086 messageTypesReceived.Add(msg.Type.String(), 1)
1087 if msg.Type.FastExtension() && !c.fastEnabled() {
1088 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1089 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1096 if !c.fastEnabled() {
1097 c.deleteAllRequests()
1099 // We don't decrement pending requests here, let's wait for the peer to either
1100 // reject or satisfy the outstanding requests. Additionally some peers may unchoke
1101 // us and resume where they left off, we don't want to have piled on to those chunks
1102 // in the meanwhile. I think a peers ability to abuse this should be limited: they
1103 // could let us request a lot of stuff, then choke us and never reject, but they're
1104 // only a single peer, our chunk balancing should smooth over this abuse.
1106 c.peerChoking = true
1107 // We can now reset our interest. I think we do this after setting the flag in case the
1108 // peerImpl updates synchronously (webseeds?).
1109 c.updateRequests("choked")
1110 c.updateExpectingChunks()
1113 // Some clients do this for some reason. Transmission doesn't error on this, so we
1114 // won't for consistency.
1115 c.logProtocolBehaviour(log.Debug, "received unchoke when already unchoked")
1118 c.peerChoking = false
1120 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1121 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1126 if preservedCount != 0 {
1127 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
1129 c.logger.WithLevel(log.Debug).Printf(
1130 "%v requests were preserved while being choked (fast=%v)",
1133 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
1135 c.updateRequests("unchoked")
1136 c.updateExpectingChunks()
1138 c.peerInterested = true
1140 case pp.NotInterested:
1141 c.peerInterested = false
1142 // We don't clear their requests since it isn't clear in the spec.
1143 // We'll probably choke them for this, which will clear them if
1144 // appropriate, and is clearly specified.
1146 err = c.peerSentHave(pieceIndex(msg.Index))
1148 err = c.peerSentBitfield(msg.Bitfield)
1150 r := newRequestFromMessage(&msg)
1151 err = c.onReadRequest(r)
1153 c.doChunkReadStats(int64(len(msg.Piece)))
1154 err = c.receiveChunk(&msg)
1155 if len(msg.Piece) == int(t.chunkSize) {
1156 t.chunkPool.Put(&msg.Piece)
1159 err = fmt.Errorf("receiving chunk: %w", err)
1162 req := newRequestFromMessage(&msg)
1163 c.onPeerSentCancel(req)
1165 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1169 pingAddr := net.UDPAddr{
1174 pingAddr.Port = int(msg.Port)
1176 cl.eachDhtServer(func(s DhtServer) {
1177 go s.Ping(&pingAddr)
1180 torrent.Add("suggests received", 1)
1181 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1182 c.updateRequests("suggested")
1184 err = c.onPeerSentHaveAll()
1186 err = c.peerSentHaveNone()
1188 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1189 case pp.AllowedFast:
1190 torrent.Add("allowed fasts received", 1)
1191 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1192 c.updateRequests("PeerConn.mainReadLoop allowed fast")
1194 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1196 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1204 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1205 if c.deleteRequest(r) {
1206 if c.isLowOnRequests() {
1207 c.updateRequests("Peer.remoteRejectedRequest")
1209 c.decExpectedChunkReceive(r)
1213 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1214 count := c.validReceiveChunks[r]
1216 delete(c.validReceiveChunks, r)
1217 } else if count > 1 {
1218 c.validReceiveChunks[r] = count - 1
1224 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1226 // TODO: Should we still do this?
1228 // These clients use their own extension IDs for outgoing message
1229 // types, which is incorrect.
1230 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1238 case pp.HandshakeExtendedID:
1239 var d pp.ExtendedHandshakeMessage
1240 if err := bencode.Unmarshal(payload, &d); err != nil {
1241 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1242 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1244 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1247 // c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1249 c.PeerMaxRequests = d.Reqq
1251 c.PeerClientName = d.V
1252 if c.PeerExtensionIDs == nil {
1253 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1255 c.PeerListenPort = d.Port
1256 c.PeerPrefersEncryption = d.Encryption
1257 for name, id := range d.M {
1258 if _, ok := c.PeerExtensionIDs[name]; !ok {
1259 peersSupportingExtension.Add(string(name), 1)
1261 c.PeerExtensionIDs[name] = id
1263 if d.MetadataSize != 0 {
1264 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1265 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1268 c.requestPendingMetadata()
1269 if !t.cl.config.DisablePEX {
1270 t.pex.Add(c) // we learnt enough now
1274 case metadataExtendedId:
1275 err := cl.gotMetadataExtensionMsg(payload, t, c)
1277 return fmt.Errorf("handling metadata extension message: %w", err)
1281 if !c.pex.IsEnabled() {
1282 return nil // or hang-up maybe?
1284 return c.pex.Recv(payload)
1286 return fmt.Errorf("unexpected extended message ID: %v", id)
1290 // Set both the Reader and Writer for the connection from a single ReadWriter.
1291 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1296 // Returns the Reader and Writer as a combined ReadWriter.
1297 func (cn *PeerConn) rw() io.ReadWriter {
1304 func (c *Peer) doChunkReadStats(size int64) {
1305 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1308 // Handle a received chunk from a peer.
1309 func (c *Peer) receiveChunk(msg *pp.Message) error {
1310 chunksReceived.Add("total", 1)
1312 ppReq := newRequestFromMessage(msg)
1313 req := c.t.requestIndexFromRequest(ppReq)
1316 chunksReceived.Add("while choked", 1)
1319 if c.validReceiveChunks[req] <= 0 {
1320 chunksReceived.Add("unexpected", 1)
1321 return errors.New("received unexpected chunk")
1323 c.decExpectedChunkReceive(req)
1325 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1326 chunksReceived.Add("due to allowed fast", 1)
1329 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1330 // have actually already received the piece, while we have the Client unlocked to write the data
1332 deletedRequest := false
1334 if c.actualRequestState.Requests.Contains(req) {
1335 for _, f := range c.callbacks.ReceivedRequested {
1336 f(PeerMessageEvent{c, msg})
1339 // Request has been satisfied.
1340 if c.deleteRequest(req) {
1341 deletedRequest = true
1343 c._chunksReceivedWhileExpecting++
1345 if c.isLowOnRequests() {
1346 c.updateRequests("Peer.receiveChunk deleted request")
1349 chunksReceived.Add("unwanted", 1)
1356 // Do we actually want this chunk?
1357 if t.haveChunk(ppReq) {
1358 // panic(fmt.Sprintf("%+v", ppReq))
1359 chunksReceived.Add("wasted", 1)
1360 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1364 piece := &t.pieces[ppReq.Index]
1366 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1367 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1369 c.piecesReceivedSinceLastRequestUpdate++
1370 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1372 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1373 f(ReceivedUsefulDataEvent{c, msg})
1375 c.lastUsefulChunkReceived = time.Now()
1377 // Need to record that it hasn't been written yet, before we attempt to do
1378 // anything with it.
1379 piece.incrementPendingWrites()
1380 // Record that we have the chunk, so we aren't trying to download it while
1381 // waiting for it to be written to storage.
1382 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1384 // Cancel pending requests for this chunk from *other* peers.
1385 t.iterPeers(func(p *Peer) {
1392 err := func() error {
1395 concurrentChunkWrites.Add(1)
1396 defer concurrentChunkWrites.Add(-1)
1397 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1398 // number of connections. We write inline with receiving the chunk (with this lock dance),
1399 // because we want to handle errors synchronously and I haven't thought of a nice way to
1400 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1402 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1405 piece.decrementPendingWrites()
1408 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1410 // Necessary to pass TestReceiveChunkStorageFailureSeederFastExtensionDisabled. I think a
1411 // request update runs while we're writing the chunk that just failed. Then we never do a
1412 // fresh update after pending the failed request.
1413 c.updateRequests("Peer.receiveChunk error writing chunk")
1414 t.onWriteChunkErr(err)
1418 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1420 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1421 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1422 t.queuePieceCheck(pieceIndex(ppReq.Index))
1423 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1424 // chunk status (such as the haveChunk call above) to have to check all the various other
1425 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1426 // that chunk pieces are pended at an appropriate time later however.
1429 cl.event.Broadcast()
1430 // We do this because we've written a chunk, and may change PieceState.Partial.
1431 t.publishPieceChange(pieceIndex(ppReq.Index))
1436 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1437 if c.peerTouchedPieces == nil {
1438 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1440 c.peerTouchedPieces[piece] = struct{}{}
1441 ds := &c.t.pieces[piece].dirtiers
1443 *ds = make(map[*Peer]struct{})
1445 (*ds)[c] = struct{}{}
1448 func (c *PeerConn) uploadAllowed() bool {
1449 if c.t.cl.config.NoUpload {
1452 if c.t.dataUploadDisallowed {
1458 if !c.peerHasWantedPieces() {
1461 // Don't upload more than 100 KiB more than we download.
1462 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1468 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1469 if c.uploadTimer == nil {
1470 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1472 c.uploadTimer.Reset(delay)
1476 // Also handles choking and unchoking of the remote peer.
1477 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1478 // Breaking or completing this loop means we don't want to upload to the
1479 // peer anymore, and we choke them.
1481 for c.uploadAllowed() {
1482 // We want to upload to the peer.
1483 if !c.unchoke(msg) {
1486 for r, state := range c.peerRequests {
1487 if state.data == nil {
1490 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1492 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1494 delay := res.Delay()
1497 c.setRetryUploadTimer(delay)
1498 // Hard to say what to return here.
1501 more := c.sendChunk(r, msg, state)
1502 delete(c.peerRequests, r)
1513 func (cn *PeerConn) drop() {
1514 cn.t.dropConnection(cn)
1517 func (cn *Peer) netGoodPiecesDirtied() int64 {
1518 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1521 func (c *Peer) peerHasWantedPieces() bool {
1522 if all, _ := c.peerHasAllPieces(); all {
1523 return !c.t.haveAllPieces()
1525 if !c.t.haveInfo() {
1526 return !c.peerPieces().IsEmpty()
1528 return c.peerPieces().Intersects(&c.t._pendingPieces)
1531 func (c *Peer) deleteRequest(r RequestIndex) bool {
1532 if !c.actualRequestState.Requests.CheckedRemove(r) {
1535 c.cancelledRequests.Remove(r)
1536 for _, f := range c.callbacks.DeletedRequest {
1537 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1539 c.updateExpectingChunks()
1540 c.t.pendingRequests.Dec(r)
1544 func (c *Peer) deleteAllRequests() {
1545 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1549 if !c.actualRequestState.Requests.IsEmpty() {
1550 panic(c.actualRequestState.Requests.GetCardinality())
1554 // This is called when something has changed that should wake the writer, such as putting stuff into
1555 // the writeBuffer, or changing some state that the writer can act on.
1556 func (c *PeerConn) tickleWriter() {
1557 c.messageWriter.writeCond.Broadcast()
1560 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1561 c.lastChunkSent = time.Now()
1562 return msg(pp.Message{
1570 func (c *PeerConn) setTorrent(t *Torrent) {
1572 panic("connection already associated with a torrent")
1575 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1576 t.reconcileHandshakeStats(c)
1579 func (c *Peer) peerPriority() (peerPriority, error) {
1580 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1583 func (c *Peer) remoteIp() net.IP {
1584 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1585 return net.ParseIP(host)
1588 func (c *Peer) remoteIpPort() IpPort {
1589 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1590 return IpPort{ipa.IP, uint16(ipa.Port)}
1593 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1594 f := pp.PexPeerFlags(0)
1595 if c.PeerPrefersEncryption {
1596 f |= pp.PexPrefersEncryption
1599 f |= pp.PexOutgoingConn
1602 f |= pp.PexSupportsUtp
1607 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1608 // advertised listen port.
1609 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1610 if !c.outgoing && c.PeerListenPort != 0 {
1611 switch addr := c.RemoteAddr.(type) {
1614 dialAddr.Port = c.PeerListenPort
1618 dialAddr.Port = c.PeerListenPort
1625 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1626 f := c.pexPeerFlags()
1627 addr := c.dialAddr()
1628 return pexEvent{t, addr, f}
1631 func (c *PeerConn) String() string {
1632 return fmt.Sprintf("connection %p", c)
1635 func (c *Peer) trust() connectionTrust {
1636 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1639 type connectionTrust struct {
1641 NetGoodPiecesDirted int64
1644 func (l connectionTrust) Less(r connectionTrust) bool {
1645 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1648 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1649 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1650 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1652 defer cn.locker().RUnlock()
1653 return cn.newPeerPieces()
1656 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1657 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1658 // TODO: Can we use copy on write?
1659 ret := cn.peerPieces().Clone()
1660 if all, _ := cn.peerHasAllPieces(); all {
1661 if cn.t.haveInfo() {
1662 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1664 ret.AddRange(0, bitmap.ToEnd)
1670 func (cn *Peer) stats() *ConnStats {
1674 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1675 pc, ok := p.peerImpl.(*PeerConn)
1679 func (pc *PeerConn) isLowOnRequests() bool {
1680 return pc.actualRequestState.Requests.IsEmpty()