16 "github.com/anacrolix/log"
17 "github.com/anacrolix/missinggo/iter"
18 "github.com/anacrolix/missinggo/v2/bitmap"
19 "github.com/anacrolix/missinggo/v2/prioritybitmap"
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 nextRequestState requestState
86 actualRequestState requestState
87 lastBecameInterested time.Time
88 priorInterest time.Duration
90 lastStartedExpectingToReceiveChunks time.Time
91 cumulativeExpectedToReceiveChunks time.Duration
92 _chunksReceivedWhileExpecting int64
95 piecesReceivedSinceLastRequestUpdate maxRequests
96 maxPiecesReceivedBetweenRequestUpdates maxRequests
97 // Chunks that we might reasonably expect to receive from the peer. Due to
98 // latency, buffering, and implementation differences, we may receive
99 // chunks that are no longer in the set of requests actually want.
100 validReceiveChunks map[RequestIndex]int
101 // Indexed by metadata piece, set to true if posted and pending a
103 metadataRequests []bool
104 sentHaves bitmap.Bitmap
106 // Stuff controlled by the remote peer.
109 peerRequests map[Request]*peerRequestState
110 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
112 // The pieces the peer has claimed to have.
113 _peerPieces bitmap.Bitmap
114 // The peer has everything. This can occur due to a special message, when
115 // we may not even know the number of pieces in the torrent yet.
117 // The highest possible number of pieces the torrent could have based on
118 // communication with the peer. Generally only useful until we have the
120 peerMinPieces pieceIndex
121 // Pieces we've accepted chunks for from the peer.
122 peerTouchedPieces map[pieceIndex]struct{}
123 peerAllowedFast bitmap.Bitmap
125 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
126 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
127 PeerClientName string
129 pieceInclination []int
130 _pieceRequestOrder prioritybitmap.PriorityBitmap
135 // Maintains the state of a BitTorrent-protocol based connection with a peer.
136 type PeerConn struct {
139 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
140 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
145 PeerExtensionBytes pp.PeerExtensionBits
147 // The actual Conn, used for closing, and setting socket options.
149 // The Reader and Writer for this Conn, with hooks installed for stats,
150 // limiting, deadlines etc.
154 messageWriter peerConnMsgWriter
156 uploadTimer *time.Timer
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 {
184 if cn.peerAllowedFast.IterTyped(func(i int) bool {
185 return roaringBitmapRangeCardinality(
186 &cn.actualRequestState.Requests,
187 cn.t.pieceRequestIndexOffset(i),
188 cn.t.pieceRequestIndexOffset(i+1),
193 return !cn.peerChoking
196 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
197 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
200 // Returns true if the connection is over IPv6.
201 func (cn *PeerConn) ipv6() bool {
206 return len(ip) == net.IPv6len
209 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
210 // specification for this.
211 func (cn *PeerConn) isPreferredDirection() bool {
212 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
215 // Returns whether the left connection should be preferred over the right one,
216 // considering only their networking properties. If ok is false, we can't
218 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
220 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
221 ml.NextBool(!l.utp(), !r.utp())
222 ml.NextBool(l.ipv6(), r.ipv6())
226 func (cn *Peer) cumInterest() time.Duration {
227 ret := cn.priorInterest
228 if cn.actualRequestState.Interested {
229 ret += time.Since(cn.lastBecameInterested)
234 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
235 if cn.peerSentHaveAll {
238 if !cn.t.haveInfo() {
241 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
244 func (cn *PeerConn) locker() *lockWithDeferreds {
245 return cn.t.cl.locker()
248 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
249 _, ok := cn.PeerExtensionIDs[ext]
253 // The best guess at number of pieces in the torrent for this peer.
254 func (cn *Peer) bestPeerNumPieces() pieceIndex {
256 return cn.t.numPieces()
258 return cn.peerMinPieces
261 func (cn *Peer) completedString() string {
262 have := pieceIndex(cn._peerPieces.Len())
263 if cn.peerSentHaveAll {
264 have = cn.bestPeerNumPieces()
266 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
269 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
270 cn.setNumPieces(info.NumPieces())
273 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
274 // receiving badly sized BITFIELD, or invalid HAVE messages.
275 func (cn *PeerConn) setNumPieces(num pieceIndex) {
276 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
277 cn.peerPiecesChanged()
280 func eventAgeString(t time.Time) string {
284 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
287 func (cn *PeerConn) connectionFlags() (ret string) {
289 ret += string([]byte{b})
291 if cn.cryptoMethod == mse.CryptoMethodRC4 {
293 } else if cn.headerEncrypted {
296 ret += string(cn.Discovery)
303 func (cn *PeerConn) utp() bool {
304 return parseNetworkString(cn.Network).Udp
307 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
308 func (cn *Peer) statusFlags() (ret string) {
310 ret += string([]byte{b})
312 if cn.actualRequestState.Interested {
319 ret += cn.connectionFlags()
321 if cn.peerInterested {
330 func (cn *Peer) downloadRate() float64 {
331 num := cn._stats.BytesReadUsefulData.Int64()
335 return float64(num) / cn.totalExpectingTime().Seconds()
338 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
339 ret = make(map[pieceIndex]int)
340 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
341 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
347 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
348 // \t isn't preserved in <pre> blocks?
349 if cn.closed.IsSet() {
350 fmt.Fprint(w, "CLOSED: ")
352 fmt.Fprintln(w, cn.connStatusString())
353 prio, err := cn.peerPriority()
354 prioStr := fmt.Sprintf("%08x", prio)
356 prioStr += ": " + err.Error()
358 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
359 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
360 eventAgeString(cn.lastMessageReceived),
361 eventAgeString(cn.completedHandshake),
362 eventAgeString(cn.lastHelpful()),
364 cn.totalExpectingTime(),
367 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
368 cn.completedString(),
369 len(cn.peerTouchedPieces),
370 &cn._stats.ChunksReadUseful,
371 &cn._stats.ChunksRead,
372 &cn._stats.ChunksWritten,
373 cn.actualRequestState.Requests.GetCardinality(),
374 cn.nominalMaxRequests(),
376 len(cn.peerRequests),
379 cn.downloadRate()/(1<<10),
381 fmt.Fprintf(w, " requested pieces:")
382 type pieceNumRequestsType struct {
386 var pieceNumRequests []pieceNumRequestsType
387 for piece, count := range cn.numRequestsByPiece() {
388 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
390 sort.Slice(pieceNumRequests, func(i, j int) bool {
391 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
393 for _, elem := range pieceNumRequests {
394 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
399 func (p *Peer) close() {
403 p.discardPieceInclination()
404 p._pieceRequestOrder.Clear()
407 p.t.decPeerPieceAvailability(p)
409 for _, f := range p.callbacks.PeerClosed {
414 func (cn *PeerConn) onClose() {
415 if cn.pex.IsEnabled() {
422 if cb := cn.callbacks.PeerConnClosed; cb != nil {
427 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
428 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
431 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
432 // https://github.com/pion/datachannel/issues/59 is fixed.
433 const writeBufferHighWaterLen = 1 << 15
435 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
436 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
437 func (cn *PeerConn) write(msg pp.Message) bool {
438 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
439 // We don't need to track bytes here because the connection's Writer has that behaviour injected
440 // (although there's some delay between us buffering the message, and the connection writer
441 // flushing it out.).
442 notFull := cn.messageWriter.write(msg)
443 // Last I checked only Piece messages affect stats, and we don't write those.
449 func (cn *PeerConn) requestMetadataPiece(index int) {
450 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
451 if eID == pp.ExtensionDeleteNumber {
454 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
457 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
458 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
459 for index >= len(cn.metadataRequests) {
460 cn.metadataRequests = append(cn.metadataRequests, false)
462 cn.metadataRequests[index] = true
465 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
466 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
469 // The actual value to use as the maximum outbound requests.
470 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
471 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 128))
474 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
475 ret = cn.cumulativeExpectedToReceiveChunks
476 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
477 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
483 func (cn *PeerConn) onPeerSentCancel(r Request) {
484 if _, ok := cn.peerRequests[r]; !ok {
485 torrent.Add("unexpected cancels received", 1)
488 if cn.fastEnabled() {
491 delete(cn.peerRequests, r)
495 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
500 more = msg(pp.Message{
503 if cn.fastEnabled() {
504 for r := range cn.peerRequests {
505 // TODO: Don't reject pieces in allowed fast set.
509 cn.peerRequests = nil
514 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
519 return msg(pp.Message{
524 func (cn *Peer) setInterested(interested bool) bool {
525 if cn.actualRequestState.Interested == interested {
528 cn.actualRequestState.Interested = interested
530 cn.lastBecameInterested = time.Now()
531 } else if !cn.lastBecameInterested.IsZero() {
532 cn.priorInterest += time.Since(cn.lastBecameInterested)
534 cn.updateExpectingChunks()
535 // log.Printf("%p: setting interest: %v", cn, interested)
536 return cn.writeInterested(interested)
539 func (pc *PeerConn) writeInterested(interested bool) bool {
540 return pc.write(pp.Message{
541 Type: func() pp.MessageType {
545 return pp.NotInterested
551 // The function takes a message to be sent, and returns true if more messages
553 type messageWriter func(pp.Message) bool
555 func (cn *Peer) shouldRequest(r RequestIndex) error {
556 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
557 if !cn.peerHasPiece(pi) {
558 return errors.New("requesting piece peer doesn't have")
560 if !cn.t.peerIsActive(cn) {
561 panic("requesting but not in active conns")
563 if cn.closed.IsSet() {
564 panic("requesting when connection is closed")
566 if cn.t.hashingPiece(pi) {
567 panic("piece is being hashed")
569 if cn.t.pieceQueuedForHash(pi) {
570 panic("piece is queued for hash")
572 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
573 panic("peer choking and piece not allowed fast")
578 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
579 if err := cn.shouldRequest(r); err != nil {
582 if cn.actualRequestState.Requests.Contains(r) {
585 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
586 return true, errors.New("too many outstanding requests")
588 cn.actualRequestState.Requests.Add(r)
589 if cn.validReceiveChunks == nil {
590 cn.validReceiveChunks = make(map[RequestIndex]int)
592 cn.validReceiveChunks[r]++
593 cn.t.pendingRequests[r]++
594 cn.updateExpectingChunks()
595 ppReq := cn.t.requestIndexToRequest(r)
596 for _, f := range cn.callbacks.SentRequest {
597 f(PeerRequestEvent{cn, ppReq})
599 return cn.peerImpl._request(ppReq), nil
602 func (me *PeerConn) _request(r Request) bool {
603 return me.write(pp.Message{
611 func (me *Peer) cancel(r RequestIndex) bool {
612 if me.deleteRequest(r) {
613 return me.peerImpl._cancel(me.t.requestIndexToRequest(r))
618 func (me *PeerConn) _cancel(r Request) bool {
619 return me.write(makeCancelMessage(r))
622 func (cn *PeerConn) fillWriteBuffer() {
623 if !cn.applyNextRequestState() {
626 if cn.pex.IsEnabled() {
627 if flow := cn.pex.Share(cn.write); !flow {
634 func (cn *PeerConn) have(piece pieceIndex) {
635 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
640 Index: pp.Integer(piece),
642 cn.sentHaves.Add(bitmap.BitIndex(piece))
645 func (cn *PeerConn) postBitfield() {
646 if cn.sentHaves.Len() != 0 {
647 panic("bitfield must be first have-related message sent")
649 if !cn.t.haveAnyPieces() {
654 Bitfield: cn.t.bitfield(),
656 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
659 func (cn *PeerConn) updateRequests() {
661 if cn.actualRequestState.Requests.GetCardinality() != 0 {
667 cn.t.cl.tickleRequester()
670 // Emits the indices in the Bitmaps bms in order, never repeating any index.
671 // skip is mutated during execution, and its initial values will never be
673 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
674 return func(cb iter.Callback) {
675 for _, bm := range bms {
677 func(_i interface{}) bool {
679 if skip.Contains(bitmap.BitIndex(i)) {
682 skip.Add(bitmap.BitIndex(i))
693 // check callers updaterequests
694 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
695 return cn._pieceRequestOrder.Remove(piece)
698 // This is distinct from Torrent piece priority, which is the user's
699 // preference. Connection piece priority is specific to a connection and is
700 // used to pseudorandomly avoid connections always requesting the same pieces
701 // and thus wasting effort.
702 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
703 tpp := cn.t.piecePriority(piece)
704 if !cn.peerHasPiece(piece) {
705 tpp = PiecePriorityNone
707 if tpp == PiecePriorityNone {
708 return cn.stopRequestingPiece(piece)
710 prio := cn.getPieceInclination()[piece]
711 return cn._pieceRequestOrder.Set(piece, prio)
714 func (cn *Peer) getPieceInclination() []int {
715 if cn.pieceInclination == nil {
716 cn.pieceInclination = cn.t.getConnPieceInclination()
718 return cn.pieceInclination
721 func (cn *Peer) discardPieceInclination() {
722 if cn.pieceInclination == nil {
725 cn.t.putPieceInclination(cn.pieceInclination)
726 cn.pieceInclination = nil
729 func (cn *Peer) peerPiecesChanged() {
731 prioritiesChanged := false
732 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
733 if cn.updatePiecePriority(i) {
734 prioritiesChanged = true
737 if prioritiesChanged {
741 cn.t.maybeDropMutuallyCompletePeer(cn)
744 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
745 if newMin > cn.peerMinPieces {
746 cn.peerMinPieces = newMin
750 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
751 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
752 return errors.New("invalid piece")
754 if cn.peerHasPiece(piece) {
757 cn.raisePeerMinPieces(piece + 1)
758 if !cn.peerHasPiece(piece) {
759 cn.t.incPieceAvailability(piece)
761 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
762 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
763 if cn.updatePiecePriority(piece) {
769 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
771 panic("expected bitfield length divisible by 8")
773 // We know that the last byte means that at most the last 7 bits are wasted.
774 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
775 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
776 // Ignore known excess pieces.
777 bf = bf[:cn.t.numPieces()]
779 pp := cn.newPeerPieces()
780 cn.peerSentHaveAll = false
781 for i, have := range bf {
783 cn.raisePeerMinPieces(pieceIndex(i) + 1)
784 if !pp.Contains(bitmap.BitIndex(i)) {
785 cn.t.incPieceAvailability(i)
788 if pp.Contains(bitmap.BitIndex(i)) {
789 cn.t.decPieceAvailability(i)
792 cn._peerPieces.Set(bitmap.BitIndex(i), have)
794 cn.peerPiecesChanged()
798 func (cn *Peer) onPeerHasAllPieces() {
801 npp, pc := cn.newPeerPieces(), t.numPieces()
802 for i := 0; i < pc; i += 1 {
803 if !npp.Contains(bitmap.BitIndex(i)) {
804 t.incPieceAvailability(i)
808 cn.peerSentHaveAll = true
809 cn._peerPieces.Clear()
810 cn.peerPiecesChanged()
813 func (cn *PeerConn) onPeerSentHaveAll() error {
814 cn.onPeerHasAllPieces()
818 func (cn *PeerConn) peerSentHaveNone() error {
819 cn.t.decPeerPieceAvailability(&cn.Peer)
820 cn._peerPieces.Clear()
821 cn.peerSentHaveAll = false
822 cn.peerPiecesChanged()
826 func (c *PeerConn) requestPendingMetadata() {
830 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
831 // Peer doesn't support this.
834 // Request metadata pieces that we don't have in a random order.
836 for index := 0; index < c.t.metadataPieceCount(); index++ {
837 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
838 pending = append(pending, index)
841 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
842 for _, i := range pending {
843 c.requestMetadataPiece(i)
847 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
848 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
849 if msg.Type == pp.Extended {
850 for name, id := range cn.PeerExtensionIDs {
851 if id != msg.ExtendedID {
854 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
857 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
860 // After handshake, we know what Torrent and Client stats to include for a
862 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
868 // All ConnStats that include this connection. Some objects are not known
869 // until the handshake is complete, after which it's expected to reconcile the
871 func (cn *Peer) allStats(f func(*ConnStats)) {
873 if cn.reconciledHandshakeStats {
874 cn.postHandshakeStats(f)
878 func (cn *PeerConn) wroteBytes(n int64) {
879 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
882 func (cn *PeerConn) readBytes(n int64) {
883 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
886 // Returns whether the connection could be useful to us. We're seeding and
887 // they want data, we don't have metainfo and they can provide it, etc.
888 func (c *Peer) useful() bool {
890 if c.closed.IsSet() {
894 return c.supportsExtension("ut_metadata")
896 if t.seeding() && c.peerInterested {
899 if c.peerHasWantedPieces() {
905 func (c *Peer) lastHelpful() (ret time.Time) {
906 ret = c.lastUsefulChunkReceived
907 if c.t.seeding() && c.lastChunkSent.After(ret) {
908 ret = c.lastChunkSent
913 func (c *PeerConn) fastEnabled() bool {
914 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
917 func (c *PeerConn) reject(r Request) {
918 if !c.fastEnabled() {
919 panic("fast not enabled")
921 c.write(r.ToMsg(pp.Reject))
922 delete(c.peerRequests, r)
925 func (c *PeerConn) onReadRequest(r Request) error {
926 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
927 if _, ok := c.peerRequests[r]; ok {
928 torrent.Add("duplicate requests received", 1)
932 torrent.Add("requests received while choking", 1)
934 torrent.Add("requests rejected while choking", 1)
939 // TODO: What if they've already requested this?
940 if len(c.peerRequests) >= localClientReqq {
941 torrent.Add("requests received while queue full", 1)
945 // BEP 6 says we may close here if we choose.
948 if !c.t.havePiece(pieceIndex(r.Index)) {
949 // This isn't necessarily them screwing up. We can drop pieces
950 // from our storage, and can't communicate this to peers
951 // except by reconnecting.
952 requestsReceivedForMissingPieces.Add(1)
953 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
955 // Check this after we know we have the piece, so that the piece length will be known.
956 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
957 torrent.Add("bad requests received", 1)
958 return errors.New("bad Request")
960 if c.peerRequests == nil {
961 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
963 value := &peerRequestState{}
964 c.peerRequests[r] = value
965 go c.peerRequestDataReader(r, value)
970 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
971 b, err := readPeerRequestData(r, c)
973 defer c.locker().Unlock()
975 c.peerRequestDataReadFailed(err, r)
978 panic("data must be non-nil to trigger send")
985 // If this is maintained correctly, we might be able to support optional synchronous reading for
986 // chunk sending, the way it used to work.
987 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
988 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
989 i := pieceIndex(r.Index)
990 if c.t.pieceComplete(i) {
991 // There used to be more code here that just duplicated the following break. Piece
992 // completions are currently cached, so I'm not sure how helpful this update is, except to
993 // pull any completion changes pushed to the storage backend in failed reads that got us
995 c.t.updatePieceCompletion(i)
997 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
998 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
999 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1000 // next connect. TODO: Support rejecting here too.
1002 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1007 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1008 b := make([]byte, r.Length)
1009 p := c.t.info.Piece(int(r.Index))
1010 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1017 panic("expected error")
1023 func runSafeExtraneous(f func()) {
1031 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1032 // exit. Returning will end the connection.
1033 func (c *PeerConn) mainReadLoop() (err error) {
1036 torrent.Add("connection.mainReadLoop returned with error", 1)
1038 torrent.Add("connection.mainReadLoop returned with no error", 1)
1044 decoder := pp.Decoder{
1045 R: bufio.NewReaderSize(c.r, 1<<17),
1046 MaxLength: 256 * 1024,
1054 err = decoder.Decode(&msg)
1056 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1059 if t.closed.IsSet() || c.closed.IsSet() {
1065 c.lastMessageReceived = time.Now()
1067 receivedKeepalives.Add(1)
1070 messageTypesReceived.Add(msg.Type.String(), 1)
1071 if msg.Type.FastExtension() && !c.fastEnabled() {
1072 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1073 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1077 c.peerChoking = true
1078 if !c.fastEnabled() {
1079 c.deleteAllRequests()
1081 // We can then reset our interest.
1083 c.updateExpectingChunks()
1085 c.peerChoking = false
1087 c.updateExpectingChunks()
1089 c.peerInterested = true
1091 case pp.NotInterested:
1092 c.peerInterested = false
1093 // We don't clear their requests since it isn't clear in the spec.
1094 // We'll probably choke them for this, which will clear them if
1095 // appropriate, and is clearly specified.
1097 err = c.peerSentHave(pieceIndex(msg.Index))
1099 err = c.peerSentBitfield(msg.Bitfield)
1101 r := newRequestFromMessage(&msg)
1102 err = c.onReadRequest(r)
1104 c.doChunkReadStats(int64(len(msg.Piece)))
1105 err = c.receiveChunk(&msg)
1106 if len(msg.Piece) == int(t.chunkSize) {
1107 t.chunkPool.Put(&msg.Piece)
1110 err = fmt.Errorf("receiving chunk: %w", err)
1113 req := newRequestFromMessage(&msg)
1114 c.onPeerSentCancel(req)
1116 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1120 pingAddr := net.UDPAddr{
1125 pingAddr.Port = int(msg.Port)
1127 cl.eachDhtServer(func(s DhtServer) {
1128 go s.Ping(&pingAddr)
1131 torrent.Add("suggests received", 1)
1132 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1135 err = c.onPeerSentHaveAll()
1137 err = c.peerSentHaveNone()
1139 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1140 case pp.AllowedFast:
1141 torrent.Add("allowed fasts received", 1)
1142 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1143 c.peerAllowedFast.Add(bitmap.BitIndex(msg.Index))
1146 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1148 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1156 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1157 if c.deleteRequest(r) {
1158 c.decExpectedChunkReceive(r)
1162 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1163 count := c.validReceiveChunks[r]
1165 delete(c.validReceiveChunks, r)
1166 } else if count > 1 {
1167 c.validReceiveChunks[r] = count - 1
1173 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1175 // TODO: Should we still do this?
1177 // These clients use their own extension IDs for outgoing message
1178 // types, which is incorrect.
1179 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1187 case pp.HandshakeExtendedID:
1188 var d pp.ExtendedHandshakeMessage
1189 if err := bencode.Unmarshal(payload, &d); err != nil {
1190 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1191 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1193 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1196 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1198 c.PeerMaxRequests = d.Reqq
1200 c.PeerClientName = d.V
1201 if c.PeerExtensionIDs == nil {
1202 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1204 c.PeerListenPort = d.Port
1205 c.PeerPrefersEncryption = d.Encryption
1206 for name, id := range d.M {
1207 if _, ok := c.PeerExtensionIDs[name]; !ok {
1208 peersSupportingExtension.Add(string(name), 1)
1210 c.PeerExtensionIDs[name] = id
1212 if d.MetadataSize != 0 {
1213 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1214 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1217 c.requestPendingMetadata()
1218 if !t.cl.config.DisablePEX {
1219 t.pex.Add(c) // we learnt enough now
1223 case metadataExtendedId:
1224 err := cl.gotMetadataExtensionMsg(payload, t, c)
1226 return fmt.Errorf("handling metadata extension message: %w", err)
1230 if !c.pex.IsEnabled() {
1231 return nil // or hang-up maybe?
1233 return c.pex.Recv(payload)
1235 return fmt.Errorf("unexpected extended message ID: %v", id)
1239 // Set both the Reader and Writer for the connection from a single ReadWriter.
1240 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1245 // Returns the Reader and Writer as a combined ReadWriter.
1246 func (cn *PeerConn) rw() io.ReadWriter {
1253 func (c *Peer) doChunkReadStats(size int64) {
1254 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1257 // Handle a received chunk from a peer.
1258 func (c *Peer) receiveChunk(msg *pp.Message) error {
1259 chunksReceived.Add("total", 1)
1261 ppReq := newRequestFromMessage(msg)
1262 req := c.t.requestIndexFromRequest(ppReq)
1265 chunksReceived.Add("while choked", 1)
1268 if c.validReceiveChunks[req] <= 0 {
1269 chunksReceived.Add("unexpected", 1)
1270 return errors.New("received unexpected chunk")
1272 c.decExpectedChunkReceive(req)
1274 if c.peerChoking && c.peerAllowedFast.Get(bitmap.BitIndex(ppReq.Index)) {
1275 chunksReceived.Add("due to allowed fast", 1)
1278 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1279 // have actually already received the piece, while we have the Client unlocked to write the data
1281 deletedRequest := false
1283 if c.actualRequestState.Requests.Contains(req) {
1284 for _, f := range c.callbacks.ReceivedRequested {
1285 f(PeerMessageEvent{c, msg})
1288 // Request has been satisfied.
1289 if c.deleteRequest(req) {
1290 deletedRequest = true
1292 c._chunksReceivedWhileExpecting++
1295 chunksReceived.Add("unwanted", 1)
1302 // Do we actually want this chunk?
1303 if t.haveChunk(ppReq) {
1304 chunksReceived.Add("wasted", 1)
1305 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1309 piece := &t.pieces[ppReq.Index]
1311 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1312 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1314 c.piecesReceivedSinceLastRequestUpdate++
1316 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1318 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1319 f(ReceivedUsefulDataEvent{c, msg})
1321 c.lastUsefulChunkReceived = time.Now()
1323 // Need to record that it hasn't been written yet, before we attempt to do
1324 // anything with it.
1325 piece.incrementPendingWrites()
1326 // Record that we have the chunk, so we aren't trying to download it while
1327 // waiting for it to be written to storage.
1328 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1330 // Cancel pending requests for this chunk from *other* peers.
1331 t.iterPeers(func(p *Peer) {
1338 err := func() error {
1341 concurrentChunkWrites.Add(1)
1342 defer concurrentChunkWrites.Add(-1)
1343 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1344 // number of connections. We write inline with receiving the chunk (with this lock dance),
1345 // because we want to handle errors synchronously and I haven't thought of a nice way to
1346 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1348 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1351 piece.decrementPendingWrites()
1354 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1356 //t.updatePieceCompletion(pieceIndex(msg.Index))
1357 t.onWriteChunkErr(err)
1361 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1363 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1364 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1365 t.queuePieceCheck(pieceIndex(ppReq.Index))
1366 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1367 // chunk status (such as the haveChunk call above) to have to check all the various other
1368 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1369 // that chunk pieces are pended at an appropriate time later however.
1372 cl.event.Broadcast()
1373 // We do this because we've written a chunk, and may change PieceState.Partial.
1374 t.publishPieceChange(pieceIndex(ppReq.Index))
1379 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1380 if c.peerTouchedPieces == nil {
1381 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1383 c.peerTouchedPieces[piece] = struct{}{}
1384 ds := &c.t.pieces[piece].dirtiers
1386 *ds = make(map[*Peer]struct{})
1388 (*ds)[c] = struct{}{}
1391 func (c *PeerConn) uploadAllowed() bool {
1392 if c.t.cl.config.NoUpload {
1395 if c.t.dataUploadDisallowed {
1401 if !c.peerHasWantedPieces() {
1404 // Don't upload more than 100 KiB more than we download.
1405 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1411 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1412 if c.uploadTimer == nil {
1413 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1415 c.uploadTimer.Reset(delay)
1419 // Also handles choking and unchoking of the remote peer.
1420 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1421 // Breaking or completing this loop means we don't want to upload to the
1422 // peer anymore, and we choke them.
1424 for c.uploadAllowed() {
1425 // We want to upload to the peer.
1426 if !c.unchoke(msg) {
1429 for r, state := range c.peerRequests {
1430 if state.data == nil {
1433 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1435 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1437 delay := res.Delay()
1440 c.setRetryUploadTimer(delay)
1441 // Hard to say what to return here.
1444 more := c.sendChunk(r, msg, state)
1445 delete(c.peerRequests, r)
1456 func (cn *PeerConn) drop() {
1457 cn.t.dropConnection(cn)
1460 func (cn *Peer) netGoodPiecesDirtied() int64 {
1461 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1464 func (c *Peer) peerHasWantedPieces() bool {
1465 return !c._pieceRequestOrder.IsEmpty()
1468 func (c *Peer) deleteRequest(r RequestIndex) bool {
1469 c.nextRequestState.Requests.Remove(r)
1470 if !c.actualRequestState.Requests.CheckedRemove(r) {
1473 for _, f := range c.callbacks.DeletedRequest {
1474 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1476 c.updateExpectingChunks()
1477 pr := c.t.pendingRequests
1489 func (c *Peer) deleteAllRequests() {
1490 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1494 if !c.actualRequestState.Requests.IsEmpty() {
1495 panic(c.actualRequestState.Requests.GetCardinality())
1497 c.nextRequestState.Requests.Clear()
1498 // for c := range c.t.conns {
1503 // This is called when something has changed that should wake the writer, such as putting stuff into
1504 // the writeBuffer, or changing some state that the writer can act on.
1505 func (c *PeerConn) tickleWriter() {
1506 c.messageWriter.writeCond.Broadcast()
1509 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1510 c.lastChunkSent = time.Now()
1511 return msg(pp.Message{
1519 func (c *PeerConn) setTorrent(t *Torrent) {
1521 panic("connection already associated with a torrent")
1524 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1525 t.reconcileHandshakeStats(c)
1528 func (c *Peer) peerPriority() (peerPriority, error) {
1529 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1532 func (c *Peer) remoteIp() net.IP {
1533 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1534 return net.ParseIP(host)
1537 func (c *Peer) remoteIpPort() IpPort {
1538 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1539 return IpPort{ipa.IP, uint16(ipa.Port)}
1542 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1543 f := pp.PexPeerFlags(0)
1544 if c.PeerPrefersEncryption {
1545 f |= pp.PexPrefersEncryption
1548 f |= pp.PexOutgoingConn
1551 f |= pp.PexSupportsUtp
1556 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1557 // advertised listen port.
1558 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1559 if !c.outgoing && c.PeerListenPort != 0 {
1560 switch addr := c.RemoteAddr.(type) {
1563 dialAddr.Port = c.PeerListenPort
1567 dialAddr.Port = c.PeerListenPort
1574 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1575 f := c.pexPeerFlags()
1576 addr := c.dialAddr()
1577 return pexEvent{t, addr, f}
1580 func (c *PeerConn) String() string {
1581 return fmt.Sprintf("connection %p", c)
1584 func (c *Peer) trust() connectionTrust {
1585 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1588 type connectionTrust struct {
1590 NetGoodPiecesDirted int64
1593 func (l connectionTrust) Less(r connectionTrust) bool {
1594 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1597 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1598 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1599 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1601 defer cn.locker().RUnlock()
1602 return cn.newPeerPieces()
1605 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1606 func (cn *Peer) newPeerPieces() bitmap.Bitmap {
1607 ret := cn._peerPieces.Copy()
1608 if cn.peerSentHaveAll {
1609 if cn.t.haveInfo() {
1610 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1612 ret.AddRange(0, bitmap.ToEnd)
1618 func (cn *Peer) stats() *ConnStats {
1622 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1623 pc, ok := p.peerImpl.(*PeerConn)
1627 func (p *PeerConn) onNextRequestStateChanged() {