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[Request]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 len(cn.actualRequestState.Requests) == 0 {
181 if !cn.actualRequestState.Interested {
184 for r := range cn.actualRequestState.Requests {
185 if !cn.remoteChokingPiece(r.Index.Int()) {
192 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
193 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
196 // Returns true if the connection is over IPv6.
197 func (cn *PeerConn) ipv6() bool {
202 return len(ip) == net.IPv6len
205 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
206 // specification for this.
207 func (cn *PeerConn) isPreferredDirection() bool {
208 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
211 // Returns whether the left connection should be preferred over the right one,
212 // considering only their networking properties. If ok is false, we can't
214 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
216 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
217 ml.NextBool(!l.utp(), !r.utp())
218 ml.NextBool(l.ipv6(), r.ipv6())
222 func (cn *Peer) cumInterest() time.Duration {
223 ret := cn.priorInterest
224 if cn.actualRequestState.Interested {
225 ret += time.Since(cn.lastBecameInterested)
230 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
231 if cn.peerSentHaveAll {
234 if !cn.t.haveInfo() {
237 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
240 func (cn *PeerConn) locker() *lockWithDeferreds {
241 return cn.t.cl.locker()
244 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
245 _, ok := cn.PeerExtensionIDs[ext]
249 // The best guess at number of pieces in the torrent for this peer.
250 func (cn *Peer) bestPeerNumPieces() pieceIndex {
252 return cn.t.numPieces()
254 return cn.peerMinPieces
257 func (cn *Peer) completedString() string {
258 have := pieceIndex(cn._peerPieces.Len())
259 if cn.peerSentHaveAll {
260 have = cn.bestPeerNumPieces()
262 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
265 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
266 cn.setNumPieces(info.NumPieces())
269 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
270 // receiving badly sized BITFIELD, or invalid HAVE messages.
271 func (cn *PeerConn) setNumPieces(num pieceIndex) {
272 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
273 cn.peerPiecesChanged()
276 func eventAgeString(t time.Time) string {
280 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
283 func (cn *PeerConn) connectionFlags() (ret string) {
285 ret += string([]byte{b})
287 if cn.cryptoMethod == mse.CryptoMethodRC4 {
289 } else if cn.headerEncrypted {
292 ret += string(cn.Discovery)
299 func (cn *PeerConn) utp() bool {
300 return parseNetworkString(cn.Network).Udp
303 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
304 func (cn *Peer) statusFlags() (ret string) {
306 ret += string([]byte{b})
308 if cn.actualRequestState.Interested {
315 ret += cn.connectionFlags()
317 if cn.peerInterested {
326 func (cn *Peer) downloadRate() float64 {
327 num := cn._stats.BytesReadUsefulData.Int64()
331 return float64(num) / cn.totalExpectingTime().Seconds()
334 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
335 ret = make(map[pieceIndex]int)
336 for r := range cn.actualRequestState.Requests {
337 ret[pieceIndex(r.Index)]++
342 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
343 // \t isn't preserved in <pre> blocks?
344 if cn.closed.IsSet() {
345 fmt.Fprint(w, "CLOSED: ")
347 fmt.Fprintln(w, cn.connStatusString())
348 prio, err := cn.peerPriority()
349 prioStr := fmt.Sprintf("%08x", prio)
351 prioStr += ": " + err.Error()
353 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
354 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
355 eventAgeString(cn.lastMessageReceived),
356 eventAgeString(cn.completedHandshake),
357 eventAgeString(cn.lastHelpful()),
359 cn.totalExpectingTime(),
362 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
363 cn.completedString(),
364 len(cn.peerTouchedPieces),
365 &cn._stats.ChunksReadUseful,
366 &cn._stats.ChunksRead,
367 &cn._stats.ChunksWritten,
368 len(cn.actualRequestState.Requests),
369 cn.nominalMaxRequests(),
371 len(cn.peerRequests),
374 cn.downloadRate()/(1<<10),
376 fmt.Fprintf(w, " requested pieces:")
377 type pieceNumRequestsType struct {
381 var pieceNumRequests []pieceNumRequestsType
382 for piece, count := range cn.numRequestsByPiece() {
383 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
385 sort.Slice(pieceNumRequests, func(i, j int) bool {
386 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
388 for _, elem := range pieceNumRequests {
389 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
394 func (p *Peer) close() {
398 p.discardPieceInclination()
399 p._pieceRequestOrder.Clear()
402 p.t.decPeerPieceAvailability(p)
404 for _, f := range p.callbacks.PeerClosed {
409 func (cn *PeerConn) onClose() {
410 if cn.pex.IsEnabled() {
417 if cb := cn.callbacks.PeerConnClosed; cb != nil {
422 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
423 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
426 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
427 // https://github.com/pion/datachannel/issues/59 is fixed.
428 const writeBufferHighWaterLen = 1 << 15
430 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
431 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
432 func (cn *PeerConn) write(msg pp.Message) bool {
433 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
434 // We don't need to track bytes here because the connection's Writer has that behaviour injected
435 // (although there's some delay between us buffering the message, and the connection writer
436 // flushing it out.).
437 notFull := cn.messageWriter.write(msg)
438 // Last I checked only Piece messages affect stats, and we don't write those.
444 func (cn *PeerConn) requestMetadataPiece(index int) {
445 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
446 if eID == pp.ExtensionDeleteNumber {
449 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
452 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
453 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
454 for index >= len(cn.metadataRequests) {
455 cn.metadataRequests = append(cn.metadataRequests, false)
457 cn.metadataRequests[index] = true
460 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
461 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
464 // The actual value to use as the maximum outbound requests.
465 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
466 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 128))
469 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
470 ret = cn.cumulativeExpectedToReceiveChunks
471 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
472 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
478 func (cn *PeerConn) onPeerSentCancel(r Request) {
479 if _, ok := cn.peerRequests[r]; !ok {
480 torrent.Add("unexpected cancels received", 1)
483 if cn.fastEnabled() {
486 delete(cn.peerRequests, r)
490 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
495 more = msg(pp.Message{
498 if cn.fastEnabled() {
499 for r := range cn.peerRequests {
500 // TODO: Don't reject pieces in allowed fast set.
504 cn.peerRequests = nil
509 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
514 return msg(pp.Message{
519 func (cn *Peer) setInterested(interested bool) bool {
520 if cn.actualRequestState.Interested == interested {
523 cn.actualRequestState.Interested = interested
525 cn.lastBecameInterested = time.Now()
526 } else if !cn.lastBecameInterested.IsZero() {
527 cn.priorInterest += time.Since(cn.lastBecameInterested)
529 cn.updateExpectingChunks()
530 // log.Printf("%p: setting interest: %v", cn, interested)
531 return cn.writeInterested(interested)
534 func (pc *PeerConn) writeInterested(interested bool) bool {
535 return pc.write(pp.Message{
536 Type: func() pp.MessageType {
540 return pp.NotInterested
546 // The function takes a message to be sent, and returns true if more messages
548 type messageWriter func(pp.Message) bool
550 func (cn *Peer) shouldRequest(r Request) error {
551 if !cn.peerHasPiece(pieceIndex(r.Index)) {
552 return errors.New("requesting piece peer doesn't have")
554 if !cn.t.peerIsActive(cn) {
555 panic("requesting but not in active conns")
557 if cn.closed.IsSet() {
558 panic("requesting when connection is closed")
560 if cn.t.hashingPiece(pieceIndex(r.Index)) {
561 panic("piece is being hashed")
563 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
564 panic("piece is queued for hash")
566 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(r.Index)) {
567 panic("peer choking and piece not allowed fast")
572 func (cn *Peer) request(r Request) (more bool, err error) {
573 if err := cn.shouldRequest(r); err != nil {
576 if _, ok := cn.actualRequestState.Requests[r]; ok {
579 if len(cn.actualRequestState.Requests) >= cn.nominalMaxRequests() {
580 return true, errors.New("too many outstanding requests")
582 if cn.actualRequestState.Requests == nil {
583 cn.actualRequestState.Requests = make(map[Request]struct{})
585 cn.actualRequestState.Requests[r] = struct{}{}
586 if cn.validReceiveChunks == nil {
587 cn.validReceiveChunks = make(map[Request]int)
589 cn.validReceiveChunks[r]++
590 cn.t.pendingRequests[r]++
591 cn.updateExpectingChunks()
592 for _, f := range cn.callbacks.SentRequest {
593 f(PeerRequestEvent{cn, r})
595 return cn.peerImpl._request(r), nil
598 func (me *PeerConn) _request(r Request) bool {
599 return me.write(pp.Message{
607 func (me *Peer) cancel(r Request) bool {
608 if me.deleteRequest(r) {
609 return me.peerImpl._cancel(r)
614 func (me *PeerConn) _cancel(r Request) bool {
615 return me.write(makeCancelMessage(r))
618 func (cn *PeerConn) fillWriteBuffer() {
619 if !cn.applyNextRequestState() {
622 if cn.pex.IsEnabled() {
623 if flow := cn.pex.Share(cn.write); !flow {
630 func (cn *PeerConn) have(piece pieceIndex) {
631 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
636 Index: pp.Integer(piece),
638 cn.sentHaves.Add(bitmap.BitIndex(piece))
641 func (cn *PeerConn) postBitfield() {
642 if cn.sentHaves.Len() != 0 {
643 panic("bitfield must be first have-related message sent")
645 if !cn.t.haveAnyPieces() {
650 Bitfield: cn.t.bitfield(),
652 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
655 func (cn *PeerConn) updateRequests() {
656 if len(cn.actualRequestState.Requests) != 0 {
662 // Emits the indices in the Bitmaps bms in order, never repeating any index.
663 // skip is mutated during execution, and its initial values will never be
665 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
666 return func(cb iter.Callback) {
667 for _, bm := range bms {
669 func(_i interface{}) bool {
671 if skip.Contains(bitmap.BitIndex(i)) {
674 skip.Add(bitmap.BitIndex(i))
685 // check callers updaterequests
686 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
687 return cn._pieceRequestOrder.Remove(piece)
690 // This is distinct from Torrent piece priority, which is the user's
691 // preference. Connection piece priority is specific to a connection and is
692 // used to pseudorandomly avoid connections always requesting the same pieces
693 // and thus wasting effort.
694 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
695 tpp := cn.t.piecePriority(piece)
696 if !cn.peerHasPiece(piece) {
697 tpp = PiecePriorityNone
699 if tpp == PiecePriorityNone {
700 return cn.stopRequestingPiece(piece)
702 prio := cn.getPieceInclination()[piece]
703 return cn._pieceRequestOrder.Set(piece, prio)
706 func (cn *Peer) getPieceInclination() []int {
707 if cn.pieceInclination == nil {
708 cn.pieceInclination = cn.t.getConnPieceInclination()
710 return cn.pieceInclination
713 func (cn *Peer) discardPieceInclination() {
714 if cn.pieceInclination == nil {
717 cn.t.putPieceInclination(cn.pieceInclination)
718 cn.pieceInclination = nil
721 func (cn *Peer) peerPiecesChanged() {
723 prioritiesChanged := false
724 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
725 if cn.updatePiecePriority(i) {
726 prioritiesChanged = true
729 if prioritiesChanged {
733 cn.t.maybeDropMutuallyCompletePeer(cn)
736 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
737 if newMin > cn.peerMinPieces {
738 cn.peerMinPieces = newMin
742 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
743 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
744 return errors.New("invalid piece")
746 if cn.peerHasPiece(piece) {
749 cn.raisePeerMinPieces(piece + 1)
750 if !cn.peerHasPiece(piece) {
751 cn.t.incPieceAvailability(piece)
753 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
754 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
755 if cn.updatePiecePriority(piece) {
761 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
763 panic("expected bitfield length divisible by 8")
765 // We know that the last byte means that at most the last 7 bits are wasted.
766 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
767 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
768 // Ignore known excess pieces.
769 bf = bf[:cn.t.numPieces()]
771 pp := cn.newPeerPieces()
772 cn.peerSentHaveAll = false
773 for i, have := range bf {
775 cn.raisePeerMinPieces(pieceIndex(i) + 1)
776 if !pp.Contains(bitmap.BitIndex(i)) {
777 cn.t.incPieceAvailability(i)
780 if pp.Contains(bitmap.BitIndex(i)) {
781 cn.t.decPieceAvailability(i)
784 cn._peerPieces.Set(bitmap.BitIndex(i), have)
786 cn.peerPiecesChanged()
790 func (cn *Peer) onPeerHasAllPieces() {
793 npp, pc := cn.newPeerPieces(), t.numPieces()
794 for i := 0; i < pc; i += 1 {
795 if !npp.Contains(bitmap.BitIndex(i)) {
796 t.incPieceAvailability(i)
800 cn.peerSentHaveAll = true
801 cn._peerPieces.Clear()
802 cn.peerPiecesChanged()
805 func (cn *PeerConn) onPeerSentHaveAll() error {
806 cn.onPeerHasAllPieces()
810 func (cn *PeerConn) peerSentHaveNone() error {
811 cn.t.decPeerPieceAvailability(&cn.Peer)
812 cn._peerPieces.Clear()
813 cn.peerSentHaveAll = false
814 cn.peerPiecesChanged()
818 func (c *PeerConn) requestPendingMetadata() {
822 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
823 // Peer doesn't support this.
826 // Request metadata pieces that we don't have in a random order.
828 for index := 0; index < c.t.metadataPieceCount(); index++ {
829 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
830 pending = append(pending, index)
833 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
834 for _, i := range pending {
835 c.requestMetadataPiece(i)
839 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
840 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
841 if msg.Type == pp.Extended {
842 for name, id := range cn.PeerExtensionIDs {
843 if id != msg.ExtendedID {
846 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
849 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
852 // After handshake, we know what Torrent and Client stats to include for a
854 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
860 // All ConnStats that include this connection. Some objects are not known
861 // until the handshake is complete, after which it's expected to reconcile the
863 func (cn *Peer) allStats(f func(*ConnStats)) {
865 if cn.reconciledHandshakeStats {
866 cn.postHandshakeStats(f)
870 func (cn *PeerConn) wroteBytes(n int64) {
871 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
874 func (cn *PeerConn) readBytes(n int64) {
875 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
878 // Returns whether the connection could be useful to us. We're seeding and
879 // they want data, we don't have metainfo and they can provide it, etc.
880 func (c *Peer) useful() bool {
882 if c.closed.IsSet() {
886 return c.supportsExtension("ut_metadata")
888 if t.seeding() && c.peerInterested {
891 if c.peerHasWantedPieces() {
897 func (c *Peer) lastHelpful() (ret time.Time) {
898 ret = c.lastUsefulChunkReceived
899 if c.t.seeding() && c.lastChunkSent.After(ret) {
900 ret = c.lastChunkSent
905 func (c *PeerConn) fastEnabled() bool {
906 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
909 func (c *PeerConn) reject(r Request) {
910 if !c.fastEnabled() {
911 panic("fast not enabled")
913 c.write(r.ToMsg(pp.Reject))
914 delete(c.peerRequests, r)
917 func (c *PeerConn) onReadRequest(r Request) error {
918 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
919 if _, ok := c.peerRequests[r]; ok {
920 torrent.Add("duplicate requests received", 1)
924 torrent.Add("requests received while choking", 1)
926 torrent.Add("requests rejected while choking", 1)
931 // TODO: What if they've already requested this?
932 if len(c.peerRequests) >= localClientReqq {
933 torrent.Add("requests received while queue full", 1)
937 // BEP 6 says we may close here if we choose.
940 if !c.t.havePiece(pieceIndex(r.Index)) {
941 // This isn't necessarily them screwing up. We can drop pieces
942 // from our storage, and can't communicate this to peers
943 // except by reconnecting.
944 requestsReceivedForMissingPieces.Add(1)
945 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
947 // Check this after we know we have the piece, so that the piece length will be known.
948 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
949 torrent.Add("bad requests received", 1)
950 return errors.New("bad Request")
952 if c.peerRequests == nil {
953 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
955 value := &peerRequestState{}
956 c.peerRequests[r] = value
957 go c.peerRequestDataReader(r, value)
962 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
963 b, err := readPeerRequestData(r, c)
965 defer c.locker().Unlock()
967 c.peerRequestDataReadFailed(err, r)
970 panic("data must be non-nil to trigger send")
977 // If this is maintained correctly, we might be able to support optional synchronous reading for
978 // chunk sending, the way it used to work.
979 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
980 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
981 i := pieceIndex(r.Index)
982 if c.t.pieceComplete(i) {
983 // There used to be more code here that just duplicated the following break. Piece
984 // completions are currently cached, so I'm not sure how helpful this update is, except to
985 // pull any completion changes pushed to the storage backend in failed reads that got us
987 c.t.updatePieceCompletion(i)
989 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
990 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
991 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
992 // next connect. TODO: Support rejecting here too.
994 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
999 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1000 b := make([]byte, r.Length)
1001 p := c.t.info.Piece(int(r.Index))
1002 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1009 panic("expected error")
1015 func runSafeExtraneous(f func()) {
1023 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1024 // exit. Returning will end the connection.
1025 func (c *PeerConn) mainReadLoop() (err error) {
1028 torrent.Add("connection.mainReadLoop returned with error", 1)
1030 torrent.Add("connection.mainReadLoop returned with no error", 1)
1036 decoder := pp.Decoder{
1037 R: bufio.NewReaderSize(c.r, 1<<17),
1038 MaxLength: 256 * 1024,
1046 err = decoder.Decode(&msg)
1048 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1051 if t.closed.IsSet() || c.closed.IsSet() {
1057 c.lastMessageReceived = time.Now()
1059 receivedKeepalives.Add(1)
1062 messageTypesReceived.Add(msg.Type.String(), 1)
1063 if msg.Type.FastExtension() && !c.fastEnabled() {
1064 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1065 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1069 c.peerChoking = true
1070 if !c.fastEnabled() {
1071 c.deleteAllRequests()
1073 // We can then reset our interest.
1075 c.updateExpectingChunks()
1077 c.peerChoking = false
1079 c.updateExpectingChunks()
1081 c.peerInterested = true
1083 case pp.NotInterested:
1084 c.peerInterested = false
1085 // We don't clear their requests since it isn't clear in the spec.
1086 // We'll probably choke them for this, which will clear them if
1087 // appropriate, and is clearly specified.
1089 err = c.peerSentHave(pieceIndex(msg.Index))
1091 err = c.peerSentBitfield(msg.Bitfield)
1093 r := newRequestFromMessage(&msg)
1094 err = c.onReadRequest(r)
1096 c.doChunkReadStats(int64(len(msg.Piece)))
1097 err = c.receiveChunk(&msg)
1098 if len(msg.Piece) == int(t.chunkSize) {
1099 t.chunkPool.Put(&msg.Piece)
1102 err = fmt.Errorf("receiving chunk: %s", err)
1105 req := newRequestFromMessage(&msg)
1106 c.onPeerSentCancel(req)
1108 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1112 pingAddr := net.UDPAddr{
1117 pingAddr.Port = int(msg.Port)
1119 cl.eachDhtServer(func(s DhtServer) {
1120 go s.Ping(&pingAddr)
1123 torrent.Add("suggests received", 1)
1124 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1127 err = c.onPeerSentHaveAll()
1129 err = c.peerSentHaveNone()
1131 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1132 case pp.AllowedFast:
1133 torrent.Add("allowed fasts received", 1)
1134 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1135 c.peerAllowedFast.Add(bitmap.BitIndex(msg.Index))
1138 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1140 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1148 func (c *Peer) remoteRejectedRequest(r Request) {
1149 if c.deleteRequest(r) {
1150 c.decExpectedChunkReceive(r)
1154 func (c *Peer) decExpectedChunkReceive(r Request) {
1155 count := c.validReceiveChunks[r]
1157 delete(c.validReceiveChunks, r)
1158 } else if count > 1 {
1159 c.validReceiveChunks[r] = count - 1
1165 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1167 // TODO: Should we still do this?
1169 // These clients use their own extension IDs for outgoing message
1170 // types, which is incorrect.
1171 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1179 case pp.HandshakeExtendedID:
1180 var d pp.ExtendedHandshakeMessage
1181 if err := bencode.Unmarshal(payload, &d); err != nil {
1182 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1183 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1185 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1188 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1190 c.PeerMaxRequests = d.Reqq
1192 c.PeerClientName = d.V
1193 if c.PeerExtensionIDs == nil {
1194 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1196 c.PeerListenPort = d.Port
1197 c.PeerPrefersEncryption = d.Encryption
1198 for name, id := range d.M {
1199 if _, ok := c.PeerExtensionIDs[name]; !ok {
1200 peersSupportingExtension.Add(string(name), 1)
1202 c.PeerExtensionIDs[name] = id
1204 if d.MetadataSize != 0 {
1205 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1206 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1209 c.requestPendingMetadata()
1210 if !t.cl.config.DisablePEX {
1211 t.pex.Add(c) // we learnt enough now
1215 case metadataExtendedId:
1216 err := cl.gotMetadataExtensionMsg(payload, t, c)
1218 return fmt.Errorf("handling metadata extension message: %w", err)
1222 if !c.pex.IsEnabled() {
1223 return nil // or hang-up maybe?
1225 return c.pex.Recv(payload)
1227 return fmt.Errorf("unexpected extended message ID: %v", id)
1231 // Set both the Reader and Writer for the connection from a single ReadWriter.
1232 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1237 // Returns the Reader and Writer as a combined ReadWriter.
1238 func (cn *PeerConn) rw() io.ReadWriter {
1245 func (c *Peer) doChunkReadStats(size int64) {
1246 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1249 // Handle a received chunk from a peer.
1250 func (c *Peer) receiveChunk(msg *pp.Message) error {
1251 chunksReceived.Add("total", 1)
1253 req := newRequestFromMessage(msg)
1256 chunksReceived.Add("while choked", 1)
1259 if c.validReceiveChunks[req] <= 0 {
1260 chunksReceived.Add("unexpected", 1)
1261 return errors.New("received unexpected chunk")
1263 c.decExpectedChunkReceive(req)
1265 if c.peerChoking && c.peerAllowedFast.Get(bitmap.BitIndex(req.Index)) {
1266 chunksReceived.Add("due to allowed fast", 1)
1269 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1270 // have actually already received the piece, while we have the Client unlocked to write the data
1272 deletedRequest := false
1274 if _, ok := c.actualRequestState.Requests[req]; ok {
1275 for _, f := range c.callbacks.ReceivedRequested {
1276 f(PeerMessageEvent{c, msg})
1279 // Request has been satisfied.
1280 if c.deleteRequest(req) {
1281 deletedRequest = true
1283 c._chunksReceivedWhileExpecting++
1286 chunksReceived.Add("unwanted", 1)
1293 // Do we actually want this chunk?
1294 if t.haveChunk(req) {
1295 chunksReceived.Add("wasted", 1)
1296 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1300 piece := &t.pieces[req.Index]
1302 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1303 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1305 c.piecesReceivedSinceLastRequestUpdate++
1307 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1309 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1310 f(ReceivedUsefulDataEvent{c, msg})
1312 c.lastUsefulChunkReceived = time.Now()
1314 // Need to record that it hasn't been written yet, before we attempt to do
1315 // anything with it.
1316 piece.incrementPendingWrites()
1317 // Record that we have the chunk, so we aren't trying to download it while
1318 // waiting for it to be written to storage.
1319 piece.unpendChunkIndex(chunkIndex(req.ChunkSpec, t.chunkSize))
1321 // Cancel pending requests for this chunk from *other* peers.
1322 t.iterPeers(func(p *Peer) {
1329 err := func() error {
1332 concurrentChunkWrites.Add(1)
1333 defer concurrentChunkWrites.Add(-1)
1334 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1335 // number of connections. We write inline with receiving the chunk (with this lock dance),
1336 // because we want to handle errors synchronously and I haven't thought of a nice way to
1337 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1339 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1342 piece.decrementPendingWrites()
1345 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1347 //t.updatePieceCompletion(pieceIndex(msg.Index))
1348 t.onWriteChunkErr(err)
1352 c.onDirtiedPiece(pieceIndex(req.Index))
1354 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1355 if t.pieceAllDirty(pieceIndex(req.Index)) && piece.pendingWrites == 0 {
1356 t.queuePieceCheck(pieceIndex(req.Index))
1357 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1358 // chunk status (such as the haveChunk call above) to have to check all the various other
1359 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1360 // that chunk pieces are pended at an appropriate time later however.
1363 cl.event.Broadcast()
1364 // We do this because we've written a chunk, and may change PieceState.Partial.
1365 t.publishPieceChange(pieceIndex(req.Index))
1370 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1371 if c.peerTouchedPieces == nil {
1372 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1374 c.peerTouchedPieces[piece] = struct{}{}
1375 ds := &c.t.pieces[piece].dirtiers
1377 *ds = make(map[*Peer]struct{})
1379 (*ds)[c] = struct{}{}
1382 func (c *PeerConn) uploadAllowed() bool {
1383 if c.t.cl.config.NoUpload {
1386 if c.t.dataUploadDisallowed {
1392 if !c.peerHasWantedPieces() {
1395 // Don't upload more than 100 KiB more than we download.
1396 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1402 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1403 if c.uploadTimer == nil {
1404 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1406 c.uploadTimer.Reset(delay)
1410 // Also handles choking and unchoking of the remote peer.
1411 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1412 // Breaking or completing this loop means we don't want to upload to the
1413 // peer anymore, and we choke them.
1415 for c.uploadAllowed() {
1416 // We want to upload to the peer.
1417 if !c.unchoke(msg) {
1420 for r, state := range c.peerRequests {
1421 if state.data == nil {
1424 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1426 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1428 delay := res.Delay()
1431 c.setRetryUploadTimer(delay)
1432 // Hard to say what to return here.
1435 more := c.sendChunk(r, msg, state)
1436 delete(c.peerRequests, r)
1447 func (cn *PeerConn) drop() {
1448 cn.t.dropConnection(cn)
1451 func (cn *Peer) netGoodPiecesDirtied() int64 {
1452 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1455 func (c *Peer) peerHasWantedPieces() bool {
1456 return !c._pieceRequestOrder.IsEmpty()
1459 func (c *Peer) deleteRequest(r Request) bool {
1460 delete(c.nextRequestState.Requests, r)
1461 if _, ok := c.actualRequestState.Requests[r]; !ok {
1464 delete(c.actualRequestState.Requests, r)
1465 for _, f := range c.callbacks.DeletedRequest {
1466 f(PeerRequestEvent{c, r})
1468 c.updateExpectingChunks()
1469 pr := c.t.pendingRequests
1481 func (c *Peer) deleteAllRequests() {
1482 for r := range c.actualRequestState.Requests {
1485 if l := len(c.actualRequestState.Requests); l != 0 {
1488 c.nextRequestState.Requests = nil
1489 // for c := range c.t.conns {
1494 // This is called when something has changed that should wake the writer, such as putting stuff into
1495 // the writeBuffer, or changing some state that the writer can act on.
1496 func (c *PeerConn) tickleWriter() {
1497 c.messageWriter.writeCond.Broadcast()
1500 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1501 c.lastChunkSent = time.Now()
1502 return msg(pp.Message{
1510 func (c *PeerConn) setTorrent(t *Torrent) {
1512 panic("connection already associated with a torrent")
1515 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1516 t.reconcileHandshakeStats(c)
1519 func (c *Peer) peerPriority() (peerPriority, error) {
1520 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1523 func (c *Peer) remoteIp() net.IP {
1524 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1525 return net.ParseIP(host)
1528 func (c *Peer) remoteIpPort() IpPort {
1529 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1530 return IpPort{ipa.IP, uint16(ipa.Port)}
1533 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1534 f := pp.PexPeerFlags(0)
1535 if c.PeerPrefersEncryption {
1536 f |= pp.PexPrefersEncryption
1539 f |= pp.PexOutgoingConn
1542 f |= pp.PexSupportsUtp
1547 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1548 // advertised listen port.
1549 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1550 if !c.outgoing && c.PeerListenPort != 0 {
1551 switch addr := c.RemoteAddr.(type) {
1554 dialAddr.Port = c.PeerListenPort
1558 dialAddr.Port = c.PeerListenPort
1565 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1566 f := c.pexPeerFlags()
1567 addr := c.dialAddr()
1568 return pexEvent{t, addr, f}
1571 func (c *PeerConn) String() string {
1572 return fmt.Sprintf("connection %p", c)
1575 func (c *Peer) trust() connectionTrust {
1576 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1579 type connectionTrust struct {
1581 NetGoodPiecesDirted int64
1584 func (l connectionTrust) Less(r connectionTrust) bool {
1585 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1588 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1589 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1590 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1592 defer cn.locker().RUnlock()
1593 return cn.newPeerPieces()
1596 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1597 func (cn *Peer) newPeerPieces() bitmap.Bitmap {
1598 ret := cn._peerPieces.Copy()
1599 if cn.peerSentHaveAll {
1600 if cn.t.haveInfo() {
1601 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1603 ret.AddRange(0, bitmap.ToEnd)
1609 func (cn *Peer) stats() *ConnStats {
1613 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1614 pc, ok := p.peerImpl.(*PeerConn)
1618 func (p *PeerConn) onNextRequestStateChanged() {