15 "github.com/anacrolix/log"
16 "github.com/anacrolix/missinggo"
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"
21 "github.com/anacrolix/torrent/metainfo"
22 "github.com/pkg/errors"
24 "github.com/anacrolix/torrent/bencode"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
29 type PeerSource string
32 PeerSourceTracker = "Tr"
33 PeerSourceIncoming = "I"
34 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
35 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
40 // First to ensure 64-bit alignment for atomics. See #262.
50 // True if the connection is operating over MSE obfuscation.
52 cryptoMethod mse.CryptoMethod
55 closed missinggo.Event
56 // Set true after we've added our ConnStats generated during handshake to
57 // other ConnStat instances as determined when the *Torrent became known.
58 reconciledHandshakeStats bool
60 lastMessageReceived time.Time
61 completedHandshake time.Time
62 lastUsefulChunkReceived time.Time
63 lastChunkSent time.Time
65 // Stuff controlled by the local peer.
67 lastBecameInterested time.Time
68 priorInterest time.Duration
70 lastStartedExpectingToReceiveChunks time.Time
71 cumulativeExpectedToReceiveChunks time.Duration
72 _chunksReceivedWhileExpecting int64
75 requests map[request]struct{}
77 // Chunks that we might reasonably expect to receive from the peer. Due to
78 // latency, buffering, and implementation differences, we may receive
79 // chunks that are no longer in the set of requests actually want.
80 validReceiveChunks map[request]int
81 // Indexed by metadata piece, set to true if posted and pending a
83 metadataRequests []bool
84 sentHaves bitmap.Bitmap
86 // Stuff controlled by the remote peer.
89 peerRequests map[request]struct{}
90 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
92 // The pieces the peer has claimed to have.
93 _peerPieces bitmap.Bitmap
94 // The peer has everything. This can occur due to a special message, when
95 // we may not even know the number of pieces in the torrent yet.
97 // The highest possible number of pieces the torrent could have based on
98 // communication with the peer. Generally only useful until we have the
100 peerMinPieces pieceIndex
101 // Pieces we've accepted chunks for from the peer.
102 peerTouchedPieces map[pieceIndex]struct{}
103 peerAllowedFast bitmap.Bitmap
105 PeerMaxRequests int // Maximum pending requests the peer allows.
106 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
107 PeerClientName string
109 pieceInclination []int
110 _pieceRequestOrder prioritybitmap.PriorityBitmap
115 // Maintains the state of a BitTorrent-protocol based connection with a peer.
116 type PeerConn struct {
119 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
120 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
125 PeerExtensionBytes pp.PeerExtensionBits
127 // The actual Conn, used for closing, and setting socket options.
129 // The Reader and Writer for this Conn, with hooks installed for stats,
130 // limiting, deadlines etc.
134 writeBuffer *bytes.Buffer
135 uploadTimer *time.Timer
143 func (cn *PeerConn) connStatusString() string {
144 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
147 func (cn *peer) updateExpectingChunks() {
148 if cn.expectingChunks() {
149 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
150 cn.lastStartedExpectingToReceiveChunks = time.Now()
153 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
154 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
155 cn.lastStartedExpectingToReceiveChunks = time.Time{}
160 func (cn *peer) expectingChunks() bool {
161 return cn.interested && !cn.peerChoking
164 // Returns true if the connection is over IPv6.
165 func (cn *PeerConn) ipv6() bool {
166 ip := addrIpOrNil(cn.RemoteAddr)
170 return len(ip) == net.IPv6len
173 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
174 // specification for this.
175 func (cn *PeerConn) isPreferredDirection() bool {
176 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
179 // Returns whether the left connection should be preferred over the right one,
180 // considering only their networking properties. If ok is false, we can't
182 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
184 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
185 ml.NextBool(!l.utp(), !r.utp())
186 ml.NextBool(l.ipv6(), r.ipv6())
190 func (cn *peer) cumInterest() time.Duration {
191 ret := cn.priorInterest
193 ret += time.Since(cn.lastBecameInterested)
198 func (cn *PeerConn) peerHasAllPieces() (all bool, known bool) {
199 if cn.peerSentHaveAll {
202 if !cn.t.haveInfo() {
205 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
208 func (cn *PeerConn) locker() *lockWithDeferreds {
209 return cn.t.cl.locker()
212 func (cn *peer) supportsExtension(ext pp.ExtensionName) bool {
213 _, ok := cn.PeerExtensionIDs[ext]
217 // The best guess at number of pieces in the torrent for this peer.
218 func (cn *peer) bestPeerNumPieces() pieceIndex {
220 return cn.t.numPieces()
222 return cn.peerMinPieces
225 func (cn *peer) completedString() string {
226 have := pieceIndex(cn._peerPieces.Len())
227 if cn.peerSentHaveAll {
228 have = cn.bestPeerNumPieces()
230 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
233 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
234 cn.setNumPieces(info.NumPieces())
237 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
238 // receiving badly sized BITFIELD, or invalid HAVE messages.
239 func (cn *PeerConn) setNumPieces(num pieceIndex) {
240 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
241 cn.peerPiecesChanged()
244 func eventAgeString(t time.Time) string {
248 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
251 func (cn *PeerConn) connectionFlags() (ret string) {
253 ret += string([]byte{b})
255 if cn.cryptoMethod == mse.CryptoMethodRC4 {
257 } else if cn.headerEncrypted {
260 ret += string(cn.Discovery)
267 func (cn *PeerConn) utp() bool {
268 return parseNetworkString(cn.network).Udp
271 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
272 func (cn *peer) statusFlags() (ret string) {
274 ret += string([]byte{b})
283 ret += cn.connectionFlags()
285 if cn.peerInterested {
294 // func (cn *connection) String() string {
295 // var buf bytes.Buffer
296 // cn.writeStatus(&buf, nil)
297 // return buf.String()
300 func (cn *peer) downloadRate() float64 {
301 return float64(cn._stats.BytesReadUsefulData.Int64()) / cn.cumInterest().Seconds()
304 func (cn *peer) writeStatus(w io.Writer, t *Torrent) {
305 // \t isn't preserved in <pre> blocks?
306 fmt.Fprintln(w, cn.connStatusString())
307 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
308 eventAgeString(cn.lastMessageReceived),
309 eventAgeString(cn.completedHandshake),
310 eventAgeString(cn.lastHelpful()),
312 cn.totalExpectingTime(),
315 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
316 cn.completedString(),
317 len(cn.peerTouchedPieces),
318 &cn._stats.ChunksReadUseful,
319 &cn._stats.ChunksRead,
320 &cn._stats.ChunksWritten,
322 cn.numLocalRequests(),
323 cn.nominalMaxRequests(),
324 len(cn.peerRequests),
326 cn.downloadRate()/(1<<10),
328 fmt.Fprintf(w, " next pieces: %v%s\n",
329 iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
331 if cn == t.fastestPeer {
340 func (cn *peer) close() {
341 if !cn.closed.Set() {
344 cn.discardPieceInclination()
345 cn._pieceRequestOrder.Clear()
349 func (cn *PeerConn) _close() {
350 if cn.pex.IsEnabled() {
357 if cb := cn.callbacks.PeerConnClosed; cb != nil {
362 func (cn *peer) peerHasPiece(piece pieceIndex) bool {
363 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
366 // Writes a message into the write buffer.
367 func (cn *PeerConn) post(msg pp.Message) {
368 torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
369 // We don't need to track bytes here because a connection.w Writer wrapper
370 // takes care of that (although there's some delay between us recording
371 // the message, and the connection writer flushing it out.).
372 cn.writeBuffer.Write(msg.MustMarshalBinary())
373 // Last I checked only Piece messages affect stats, and we don't post
379 // Returns true if there's room to write more.
380 func (cn *PeerConn) write(msg pp.Message) bool {
382 cn.writeBuffer.Write(msg.MustMarshalBinary())
383 torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
384 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update
385 // when https://github.com/pion/datachannel/issues/59 is fixed.
386 return cn.writeBuffer.Len() < 1<<15
389 func (cn *PeerConn) requestMetadataPiece(index int) {
390 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
394 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
397 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
401 ExtendedPayload: func() []byte {
402 b, err := bencode.Marshal(map[string]int{
403 "msg_type": pp.RequestMetadataExtensionMsgType,
412 for index >= len(cn.metadataRequests) {
413 cn.metadataRequests = append(cn.metadataRequests, false)
415 cn.metadataRequests[index] = true
418 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
419 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
422 // The actual value to use as the maximum outbound requests.
423 func (cn *peer) nominalMaxRequests() (ret int) {
426 int64(cn.PeerMaxRequests),
427 int64(cn.t.requestStrategy.nominalMaxRequests(cn.requestStrategyConnection())),
431 func (cn *peer) totalExpectingTime() (ret time.Duration) {
432 ret = cn.cumulativeExpectedToReceiveChunks
433 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
434 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
440 func (cn *PeerConn) onPeerSentCancel(r request) {
441 if _, ok := cn.peerRequests[r]; !ok {
442 torrent.Add("unexpected cancels received", 1)
445 if cn.fastEnabled() {
448 delete(cn.peerRequests, r)
452 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
457 more = msg(pp.Message{
460 if cn.fastEnabled() {
461 for r := range cn.peerRequests {
462 // TODO: Don't reject pieces in allowed fast set.
466 cn.peerRequests = nil
471 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
476 return msg(pp.Message{
481 func (cn *peer) setInterested(interested bool) bool {
482 if cn.interested == interested {
485 cn.interested = interested
487 cn.lastBecameInterested = time.Now()
488 } else if !cn.lastBecameInterested.IsZero() {
489 cn.priorInterest += time.Since(cn.lastBecameInterested)
491 cn.updateExpectingChunks()
492 // log.Printf("%p: setting interest: %v", cn, interested)
493 return cn.writeInterested(interested)
496 func (pc *PeerConn) writeInterested(interested bool) bool {
497 return pc.write(pp.Message{
498 Type: func() pp.MessageType {
502 return pp.NotInterested
508 // The function takes a message to be sent, and returns true if more messages
510 type messageWriter func(pp.Message) bool
512 func (cn *peer) request(r request) bool {
513 if _, ok := cn.requests[r]; ok {
514 panic("chunk already requested")
516 if !cn.peerHasPiece(pieceIndex(r.Index)) {
517 panic("requesting piece peer doesn't have")
519 if !cn.t.peerIsActive(cn) {
520 panic("requesting but not in active conns")
522 if cn.closed.IsSet() {
523 panic("requesting when connection is closed")
526 if cn.peerAllowedFast.Get(int(r.Index)) {
527 torrent.Add("allowed fast requests sent", 1)
529 panic("requesting while choking and not allowed fast")
532 if cn.t.hashingPiece(pieceIndex(r.Index)) {
533 panic("piece is being hashed")
535 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
536 panic("piece is queued for hash")
538 if cn.requests == nil {
539 cn.requests = make(map[request]struct{})
541 cn.requests[r] = struct{}{}
542 if cn.validReceiveChunks == nil {
543 cn.validReceiveChunks = make(map[request]int)
545 cn.validReceiveChunks[r]++
546 cn.t.pendingRequests[r]++
547 cn.t.requestStrategy.hooks().sentRequest(r)
548 cn.updateExpectingChunks()
549 return cn.peerImpl.request(r)
552 func (me *PeerConn) request(r request) bool {
553 return me.write(pp.Message{
561 func (me *PeerConn) cancel(r request) bool {
562 return me.write(makeCancelMessage(r))
565 func (cn *peer) doRequestState() bool {
566 if !cn.t.networkingEnabled || cn.t.dataDownloadDisallowed {
567 if !cn.setInterested(false) {
570 if len(cn.requests) != 0 {
571 for r := range cn.requests {
573 // log.Printf("%p: cancelling request: %v", cn, r)
574 if !cn.peerImpl.cancel(r) {
579 } else if len(cn.requests) <= cn.requestsLowWater {
580 filledBuffer := false
581 cn.iterPendingPieces(func(pieceIndex pieceIndex) bool {
582 cn.iterPendingRequests(pieceIndex, func(r request) bool {
583 if !cn.setInterested(true) {
587 if len(cn.requests) >= cn.nominalMaxRequests() {
590 // Choking is looked at here because our interest is dependent
591 // on whether we'd make requests in its absence.
593 if !cn.peerAllowedFast.Get(bitmap.BitIndex(r.Index)) {
597 if _, ok := cn.requests[r]; ok {
600 filledBuffer = !cn.request(r)
606 // If we didn't completely top up the requests, we shouldn't mark
607 // the low water, since we'll want to top up the requests as soon
608 // as we have more write buffer space.
611 cn.requestsLowWater = len(cn.requests) / 2
616 func (cn *PeerConn) fillWriteBuffer() {
617 if !cn.doRequestState() {
620 if cn.pex.IsEnabled() {
621 if flow := cn.pex.Share(cn.write); !flow {
628 // Routine that writes to the peer. Some of what to write is buffered by
629 // activity elsewhere in the Client, and some is determined locally when the
630 // connection is writable.
631 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
633 lastWrite time.Time = time.Now()
634 keepAliveTimer *time.Timer
636 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
638 defer cn.locker().Unlock()
639 if time.Since(lastWrite) >= keepAliveTimeout {
642 keepAliveTimer.Reset(keepAliveTimeout)
645 defer cn.locker().Unlock()
647 defer keepAliveTimer.Stop()
648 frontBuf := new(bytes.Buffer)
650 if cn.closed.IsSet() {
653 if cn.writeBuffer.Len() == 0 {
656 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout {
657 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
658 postedKeepalives.Add(1)
660 if cn.writeBuffer.Len() == 0 {
661 // TODO: Minimize wakeups....
666 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
668 n, err := cn.w.Write(frontBuf.Bytes())
671 lastWrite = time.Now()
672 keepAliveTimer.Reset(keepAliveTimeout)
675 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
678 if n != frontBuf.Len() {
685 func (cn *PeerConn) have(piece pieceIndex) {
686 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
691 Index: pp.Integer(piece),
693 cn.sentHaves.Add(bitmap.BitIndex(piece))
696 func (cn *PeerConn) postBitfield() {
697 if cn.sentHaves.Len() != 0 {
698 panic("bitfield must be first have-related message sent")
700 if !cn.t.haveAnyPieces() {
705 Bitfield: cn.t.bitfield(),
707 cn.sentHaves = cn.t._completedPieces.Copy()
710 func (cn *PeerConn) updateRequests() {
711 // log.Print("update requests")
715 // Emits the indices in the Bitmaps bms in order, never repeating any index.
716 // skip is mutated during execution, and its initial values will never be
718 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
719 return func(cb iter.Callback) {
720 for _, bm := range bms {
722 func(i interface{}) bool {
726 bitmap.Sub(bm, *skip).Iter,
734 func iterUnbiasedPieceRequestOrder(cn requestStrategyConnection, f func(piece pieceIndex) bool) bool {
735 now, readahead := cn.torrent().readerPiecePriorities()
736 skip := bitmap.Flip(cn.peerPieces(), 0, cn.torrent().numPieces())
737 skip.Union(cn.torrent().ignorePieces())
738 // Return an iterator over the different priority classes, minus the skip pieces.
740 func(_piece interface{}) bool {
741 return f(pieceIndex(_piece.(bitmap.BitIndex)))
743 iterBitmapsDistinct(&skip, now, readahead),
744 // We have to iterate _pendingPieces separately because it isn't a Bitmap.
745 func(cb iter.Callback) {
746 cn.torrent().pendingPieces().IterTyped(func(piece int) bool {
747 if skip.Contains(piece) {
758 // The connection should download highest priority pieces first, without any inclination toward
759 // avoiding wastage. Generally we might do this if there's a single connection, or this is the
760 // fastest connection, and we have active readers that signal an ordering preference. It's
761 // conceivable that the best connection should do this, since it's least likely to waste our time if
762 // assigned to the highest priority pieces, and assigning more than one this role would cause
763 // significant wasted bandwidth.
764 func (cn *peer) shouldRequestWithoutBias() bool {
765 return cn.t.requestStrategy.shouldRequestWithoutBias(cn.requestStrategyConnection())
768 func (cn *peer) iterPendingPieces(f func(pieceIndex) bool) bool {
769 if !cn.t.haveInfo() {
772 return cn.t.requestStrategy.iterPendingPieces(cn, f)
774 func (cn *peer) iterPendingPiecesUntyped(f iter.Callback) {
775 cn.iterPendingPieces(func(i pieceIndex) bool { return f(i) })
778 func (cn *peer) iterPendingRequests(piece pieceIndex, f func(request) bool) bool {
779 return cn.t.requestStrategy.iterUndirtiedChunks(
780 cn.t.piece(piece).requestStrategyPiece(),
781 func(cs chunkSpec) bool {
782 return f(request{pp.Integer(piece), cs})
787 // check callers updaterequests
788 func (cn *peer) stopRequestingPiece(piece pieceIndex) bool {
789 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
792 // This is distinct from Torrent piece priority, which is the user's
793 // preference. Connection piece priority is specific to a connection and is
794 // used to pseudorandomly avoid connections always requesting the same pieces
795 // and thus wasting effort.
796 func (cn *peer) updatePiecePriority(piece pieceIndex) bool {
797 tpp := cn.t.piecePriority(piece)
798 if !cn.peerHasPiece(piece) {
799 tpp = PiecePriorityNone
801 if tpp == PiecePriorityNone {
802 return cn.stopRequestingPiece(piece)
804 prio := cn.getPieceInclination()[piece]
805 prio = cn.t.requestStrategy.piecePriority(cn, piece, tpp, prio)
806 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio) || cn.shouldRequestWithoutBias()
809 func (cn *peer) getPieceInclination() []int {
810 if cn.pieceInclination == nil {
811 cn.pieceInclination = cn.t.getConnPieceInclination()
813 return cn.pieceInclination
816 func (cn *peer) discardPieceInclination() {
817 if cn.pieceInclination == nil {
820 cn.t.putPieceInclination(cn.pieceInclination)
821 cn.pieceInclination = nil
824 func (cn *PeerConn) peerPiecesChanged() {
826 prioritiesChanged := false
827 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
828 if cn.updatePiecePriority(i) {
829 prioritiesChanged = true
832 if prioritiesChanged {
838 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
839 if newMin > cn.peerMinPieces {
840 cn.peerMinPieces = newMin
844 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
845 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
846 return errors.New("invalid piece")
848 if cn.peerHasPiece(piece) {
851 cn.raisePeerMinPieces(piece + 1)
852 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
853 if cn.updatePiecePriority(piece) {
859 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
860 cn.peerSentHaveAll = false
862 panic("expected bitfield length divisible by 8")
864 // We know that the last byte means that at most the last 7 bits are
866 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
867 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
868 // Ignore known excess pieces.
869 bf = bf[:cn.t.numPieces()]
871 for i, have := range bf {
873 cn.raisePeerMinPieces(pieceIndex(i) + 1)
875 cn._peerPieces.Set(i, have)
877 cn.peerPiecesChanged()
881 func (cn *PeerConn) onPeerSentHaveAll() error {
882 cn.peerSentHaveAll = true
883 cn._peerPieces.Clear()
884 cn.peerPiecesChanged()
888 func (cn *PeerConn) peerSentHaveNone() error {
889 cn._peerPieces.Clear()
890 cn.peerSentHaveAll = false
891 cn.peerPiecesChanged()
895 func (c *PeerConn) requestPendingMetadata() {
899 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
900 // Peer doesn't support this.
903 // Request metadata pieces that we don't have in a random order.
905 for index := 0; index < c.t.metadataPieceCount(); index++ {
906 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
907 pending = append(pending, index)
910 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
911 for _, i := range pending {
912 c.requestMetadataPiece(i)
916 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
917 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
918 if msg.Type == pp.Extended {
919 for name, id := range cn.PeerExtensionIDs {
920 if id != msg.ExtendedID {
923 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
926 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
929 func (cn *PeerConn) readMsg(msg *pp.Message) {
930 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
933 // After handshake, we know what Torrent and Client stats to include for a
935 func (cn *peer) postHandshakeStats(f func(*ConnStats)) {
941 // All ConnStats that include this connection. Some objects are not known
942 // until the handshake is complete, after which it's expected to reconcile the
944 func (cn *peer) allStats(f func(*ConnStats)) {
946 if cn.reconciledHandshakeStats {
947 cn.postHandshakeStats(f)
951 func (cn *PeerConn) wroteBytes(n int64) {
952 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
955 func (cn *PeerConn) readBytes(n int64) {
956 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
959 // Returns whether the connection could be useful to us. We're seeding and
960 // they want data, we don't have metainfo and they can provide it, etc.
961 func (c *peer) useful() bool {
963 if c.closed.IsSet() {
967 return c.supportsExtension("ut_metadata")
969 if t.seeding() && c.peerInterested {
972 if c.peerHasWantedPieces() {
978 func (c *peer) lastHelpful() (ret time.Time) {
979 ret = c.lastUsefulChunkReceived
980 if c.t.seeding() && c.lastChunkSent.After(ret) {
981 ret = c.lastChunkSent
986 func (c *PeerConn) fastEnabled() bool {
987 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
990 func (c *PeerConn) reject(r request) {
991 if !c.fastEnabled() {
992 panic("fast not enabled")
994 c.post(r.ToMsg(pp.Reject))
995 delete(c.peerRequests, r)
998 func (c *PeerConn) onReadRequest(r request) error {
999 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
1000 if _, ok := c.peerRequests[r]; ok {
1001 torrent.Add("duplicate requests received", 1)
1005 torrent.Add("requests received while choking", 1)
1006 if c.fastEnabled() {
1007 torrent.Add("requests rejected while choking", 1)
1012 if len(c.peerRequests) >= maxRequests {
1013 torrent.Add("requests received while queue full", 1)
1014 if c.fastEnabled() {
1017 // BEP 6 says we may close here if we choose.
1020 if !c.t.havePiece(pieceIndex(r.Index)) {
1021 // This isn't necessarily them screwing up. We can drop pieces
1022 // from our storage, and can't communicate this to peers
1023 // except by reconnecting.
1024 requestsReceivedForMissingPieces.Add(1)
1025 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
1027 // Check this after we know we have the piece, so that the piece length will be known.
1028 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
1029 torrent.Add("bad requests received", 1)
1030 return errors.New("bad request")
1032 if c.peerRequests == nil {
1033 c.peerRequests = make(map[request]struct{}, maxRequests)
1035 c.peerRequests[r] = struct{}{}
1040 func runSafeExtraneous(f func()) {
1048 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1049 // exit. Returning will end the connection.
1050 func (c *PeerConn) mainReadLoop() (err error) {
1053 torrent.Add("connection.mainReadLoop returned with error", 1)
1055 torrent.Add("connection.mainReadLoop returned with no error", 1)
1061 decoder := pp.Decoder{
1062 R: bufio.NewReaderSize(c.r, 1<<17),
1063 MaxLength: 256 * 1024,
1071 err = decoder.Decode(&msg)
1073 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1076 if t.closed.IsSet() || c.closed.IsSet() {
1083 c.lastMessageReceived = time.Now()
1085 receivedKeepalives.Add(1)
1088 messageTypesReceived.Add(msg.Type.String(), 1)
1089 if msg.Type.FastExtension() && !c.fastEnabled() {
1090 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1091 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1095 c.peerChoking = true
1096 if !c.fastEnabled() {
1097 c.deleteAllRequests()
1099 // We can then reset our interest.
1101 c.updateExpectingChunks()
1103 c.peerChoking = false
1105 c.updateExpectingChunks()
1107 c.peerInterested = true
1109 case pp.NotInterested:
1110 c.peerInterested = false
1111 // We don't clear their requests since it isn't clear in the spec.
1112 // We'll probably choke them for this, which will clear them if
1113 // appropriate, and is clearly specified.
1115 err = c.peerSentHave(pieceIndex(msg.Index))
1117 err = c.peerSentBitfield(msg.Bitfield)
1119 r := newRequestFromMessage(&msg)
1120 err = c.onReadRequest(r)
1122 err = c.receiveChunk(&msg)
1123 if len(msg.Piece) == int(t.chunkSize) {
1124 t.chunkPool.Put(&msg.Piece)
1127 err = fmt.Errorf("receiving chunk: %s", err)
1130 req := newRequestFromMessage(&msg)
1131 c.onPeerSentCancel(req)
1133 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1137 pingAddr := net.UDPAddr{
1142 pingAddr.Port = int(msg.Port)
1144 cl.eachDhtServer(func(s DhtServer) {
1145 go s.Ping(&pingAddr)
1148 torrent.Add("suggests received", 1)
1149 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1152 err = c.onPeerSentHaveAll()
1154 err = c.peerSentHaveNone()
1156 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1157 case pp.AllowedFast:
1158 torrent.Add("allowed fasts received", 1)
1159 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1160 c.peerAllowedFast.Add(int(msg.Index))
1163 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1165 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1173 func (c *peer) remoteRejectedRequest(r request) {
1174 if c.deleteRequest(r) {
1175 c.decExpectedChunkReceive(r)
1179 func (c *peer) decExpectedChunkReceive(r request) {
1180 count := c.validReceiveChunks[r]
1182 delete(c.validReceiveChunks, r)
1183 } else if count > 1 {
1184 c.validReceiveChunks[r] = count - 1
1190 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1192 // TODO: Should we still do this?
1194 // These clients use their own extension IDs for outgoing message
1195 // types, which is incorrect.
1196 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1204 case pp.HandshakeExtendedID:
1205 var d pp.ExtendedHandshakeMessage
1206 if err := bencode.Unmarshal(payload, &d); err != nil {
1207 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1208 return errors.Wrap(err, "unmarshalling extended handshake payload")
1210 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1213 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1215 c.PeerMaxRequests = d.Reqq
1217 c.PeerClientName = d.V
1218 if c.PeerExtensionIDs == nil {
1219 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1221 c.PeerListenPort = d.Port
1222 c.PeerPrefersEncryption = d.Encryption
1223 for name, id := range d.M {
1224 if _, ok := c.PeerExtensionIDs[name]; !ok {
1225 torrent.Add(fmt.Sprintf("peers supporting extension %q", name), 1)
1227 c.PeerExtensionIDs[name] = id
1229 if d.MetadataSize != 0 {
1230 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1231 return errors.Wrapf(err, "setting metadata size to %d", d.MetadataSize)
1234 c.requestPendingMetadata()
1235 if !t.cl.config.DisablePEX {
1236 t.pex.Add(c) // we learnt enough now
1240 case metadataExtendedId:
1241 err := cl.gotMetadataExtensionMsg(payload, t, c)
1243 return fmt.Errorf("handling metadata extension message: %w", err)
1247 if !c.pex.IsEnabled() {
1248 return nil // or hang-up maybe?
1250 return c.pex.Recv(payload)
1252 return fmt.Errorf("unexpected extended message ID: %v", id)
1256 // Set both the Reader and Writer for the connection from a single ReadWriter.
1257 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1262 // Returns the Reader and Writer as a combined ReadWriter.
1263 func (cn *PeerConn) rw() io.ReadWriter {
1270 // Handle a received chunk from a peer.
1271 func (c *peer) receiveChunk(msg *pp.Message) error {
1274 torrent.Add("chunks received", 1)
1276 req := newRequestFromMessage(msg)
1279 torrent.Add("chunks received while choking", 1)
1282 if c.validReceiveChunks[req] <= 0 {
1283 torrent.Add("chunks received unexpected", 1)
1284 return errors.New("received unexpected chunk")
1286 c.decExpectedChunkReceive(req)
1288 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1289 torrent.Add("chunks received due to allowed fast", 1)
1293 // Request has been satisfied.
1294 if c.deleteRequest(req) {
1295 if c.expectingChunks() {
1296 c._chunksReceivedWhileExpecting++
1299 torrent.Add("chunks received unwanted", 1)
1303 // Do we actually want this chunk?
1304 if t.haveChunk(req) {
1305 torrent.Add("chunks received wasted", 1)
1306 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1310 piece := &t.pieces[req.Index]
1312 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1313 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1314 c.lastUsefulChunkReceived = time.Now()
1315 // if t.fastestPeer != c {
1316 // log.Printf("setting fastest connection %p", c)
1320 // Need to record that it hasn't been written yet, before we attempt to do
1321 // anything with it.
1322 piece.incrementPendingWrites()
1323 // Record that we have the chunk, so we aren't trying to download it while
1324 // waiting for it to be written to storage.
1325 piece.unpendChunkIndex(chunkIndex(req.chunkSpec, t.chunkSize))
1327 // Cancel pending requests for this chunk.
1328 for c := range t.conns {
1332 err := func() error {
1335 concurrentChunkWrites.Add(1)
1336 defer concurrentChunkWrites.Add(-1)
1337 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1338 // number of connections. We write inline with receiving the chunk (with this lock dance),
1339 // because we want to handle errors synchronously and I haven't thought of a nice way to
1340 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1342 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1345 piece.decrementPendingWrites()
1348 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1350 //t.updatePieceCompletion(pieceIndex(msg.Index))
1351 t.onWriteChunkErr(err)
1355 c.onDirtiedPiece(pieceIndex(req.Index))
1357 if t.pieceAllDirty(pieceIndex(req.Index)) {
1358 t.queuePieceCheck(pieceIndex(req.Index))
1359 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1360 // chunk status (such as the haveChunk call above) to have to check all the various other
1361 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1362 // that chunk pieces are pended at an appropriate time later however.
1365 cl.event.Broadcast()
1366 // We do this because we've written a chunk, and may change PieceState.Partial.
1367 t.publishPieceChange(pieceIndex(req.Index))
1372 func (c *peer) onDirtiedPiece(piece pieceIndex) {
1373 if c.peerTouchedPieces == nil {
1374 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1376 c.peerTouchedPieces[piece] = struct{}{}
1377 ds := &c.t.pieces[piece].dirtiers
1379 *ds = make(map[*peer]struct{})
1381 (*ds)[c] = struct{}{}
1384 func (c *PeerConn) uploadAllowed() bool {
1385 if c.t.cl.config.NoUpload {
1388 if c.t.dataUploadDisallowed {
1394 if !c.peerHasWantedPieces() {
1397 // Don't upload more than 100 KiB more than we download.
1398 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1404 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1405 if c.uploadTimer == nil {
1406 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1408 c.uploadTimer.Reset(delay)
1412 // Also handles choking and unchoking of the remote peer.
1413 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1414 // Breaking or completing this loop means we don't want to upload to the
1415 // peer anymore, and we choke them.
1417 for c.uploadAllowed() {
1418 // We want to upload to the peer.
1419 if !c.unchoke(msg) {
1422 for r := range c.peerRequests {
1423 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1425 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1427 delay := res.Delay()
1430 c.setRetryUploadTimer(delay)
1431 // Hard to say what to return here.
1434 more, err := c.sendChunk(r, msg)
1436 c.logger.WithDefaultLevel(log.Warning).Printf("sending chunk to peer: %v", err)
1437 i := pieceIndex(r.Index)
1438 if c.t.pieceComplete(i) {
1439 // There used to be more code here that just duplicated the following break.
1440 // Piece completions are currently cached, so I'm not sure how helpful this
1441 // update is, except to pull any completion changes pushed to the storage
1442 // backend in failed reads that got us here.
1443 c.t.updatePieceCompletion(i)
1445 // If we failed to send a chunk, choke the peer by breaking out of the loop here to
1446 // ensure they flush all their requests. We've probably dropped a piece from
1447 // storage, but there's no way to communicate this to the peer. If they ask for it
1448 // again, we'll kick them to allow us to send them an updated bitfield on the next
1451 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1455 delete(c.peerRequests, r)
1466 func (cn *PeerConn) drop() {
1467 cn.t.dropConnection(cn)
1470 func (cn *peer) netGoodPiecesDirtied() int64 {
1471 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1474 func (c *peer) peerHasWantedPieces() bool {
1475 return !c._pieceRequestOrder.IsEmpty()
1478 func (c *peer) numLocalRequests() int {
1479 return len(c.requests)
1482 func (c *peer) deleteRequest(r request) bool {
1483 if _, ok := c.requests[r]; !ok {
1486 delete(c.requests, r)
1487 c.updateExpectingChunks()
1488 c.t.requestStrategy.hooks().deletedRequest(r)
1489 pr := c.t.pendingRequests
1498 // If a request fails, updating the requests for the current peer first may miss the opportunity
1499 // to try other peers for that request instead, depending on the request strategy. This might
1500 // only affect webseed peers though, since they synchronously issue new requests: PeerConns do
1501 // it in the writer routine.
1502 const updateCurrentConnRequestsFirst = false
1503 if updateCurrentConnRequestsFirst {
1506 // Give other conns a chance to pick up the request.
1507 c.t.iterPeers(func(_c *peer) {
1508 // We previously checked that the peer wasn't interested to to only wake connections that
1509 // were unable to issue requests due to starvation by the request strategy. There could be
1510 // performance ramifications.
1511 if _c != c && c.peerHasPiece(pieceIndex(r.Index)) {
1515 if !updateCurrentConnRequestsFirst {
1521 func (c *peer) deleteAllRequests() {
1522 for r := range c.requests {
1525 if len(c.requests) != 0 {
1526 panic(len(c.requests))
1528 // for c := range c.t.conns {
1533 func (c *PeerConn) tickleWriter() {
1534 c.writerCond.Broadcast()
1537 func (c *peer) postCancel(r request) bool {
1538 if !c.deleteRequest(r) {
1541 c.peerImpl._postCancel(r)
1545 func (c *PeerConn) _postCancel(r request) {
1546 c.post(makeCancelMessage(r))
1549 func (c *PeerConn) sendChunk(r request, msg func(pp.Message) bool) (more bool, err error) {
1550 b := make([]byte, r.Length)
1551 p := c.t.info.Piece(int(r.Index))
1552 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1555 panic("expected error")
1558 } else if err == io.EOF {
1561 more = msg(pp.Message{
1567 c.lastChunkSent = time.Now()
1571 func (c *PeerConn) setTorrent(t *Torrent) {
1573 panic("connection already associated with a torrent")
1576 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1577 t.reconcileHandshakeStats(c)
1580 func (c *peer) peerPriority() (peerPriority, error) {
1581 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1584 func (c *peer) remoteIp() net.IP {
1585 return addrIpOrNil(c.RemoteAddr)
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
1601 if c.RemoteAddr != nil && strings.Contains(c.RemoteAddr.Network(), "udp") {
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() net.Addr {
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 func (cn *peer) requestStrategyConnection() requestStrategyConnection {
1652 func (cn *peer) chunksReceivedWhileExpecting() int64 {
1653 return cn._chunksReceivedWhileExpecting
1656 func (cn *peer) fastest() bool {
1657 return cn == cn.t.fastestPeer
1660 func (cn *peer) peerMaxRequests() int {
1661 return cn.PeerMaxRequests
1664 // Returns the pieces the peer has claimed to have.
1665 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1667 defer cn.locker().RUnlock()
1668 return cn.peerPieces()
1671 func (cn *peer) peerPieces() bitmap.Bitmap {
1672 ret := cn._peerPieces.Copy()
1673 if cn.peerSentHaveAll {
1674 ret.AddRange(0, cn.t.numPieces())
1679 func (cn *peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1680 return &cn._pieceRequestOrder
1683 func (cn *peer) stats() *ConnStats {
1687 func (cn *peer) torrent() requestStrategyTorrent {
1688 return cn.t.requestStrategyTorrent()