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
87 // Stuff controlled by the remote peer.
90 peerRequests map[request]struct{}
91 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
93 // The pieces the peer has claimed to have.
94 _peerPieces bitmap.Bitmap
95 // The peer has everything. This can occur due to a special message, when
96 // we may not even know the number of pieces in the torrent yet.
98 // The highest possible number of pieces the torrent could have based on
99 // communication with the peer. Generally only useful until we have the
101 peerMinPieces pieceIndex
102 // Pieces we've accepted chunks for from the peer.
103 peerTouchedPieces map[pieceIndex]struct{}
104 peerAllowedFast bitmap.Bitmap
106 PeerMaxRequests int // Maximum pending requests the peer allows.
107 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
108 PeerClientName string
110 pieceInclination []int
111 _pieceRequestOrder prioritybitmap.PriorityBitmap
116 // Maintains the state of a BitTorrent-protocol based connection with a peer.
117 type PeerConn struct {
120 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
121 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
126 PeerExtensionBytes pp.PeerExtensionBits
128 // The actual Conn, used for closing, and setting socket options.
130 // The Reader and Writer for this Conn, with hooks installed for stats,
131 // limiting, deadlines etc.
135 writeBuffer *bytes.Buffer
136 uploadTimer *time.Timer
140 func (cn *PeerConn) connStatusString() string {
141 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
144 func (cn *peer) updateExpectingChunks() {
145 if cn.expectingChunks() {
146 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
147 cn.lastStartedExpectingToReceiveChunks = time.Now()
150 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
151 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
152 cn.lastStartedExpectingToReceiveChunks = time.Time{}
157 func (cn *peer) expectingChunks() bool {
158 return cn.interested && !cn.peerChoking
161 // Returns true if the connection is over IPv6.
162 func (cn *PeerConn) ipv6() bool {
163 ip := addrIpOrNil(cn.RemoteAddr)
167 return len(ip) == net.IPv6len
170 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
171 // specification for this.
172 func (cn *PeerConn) isPreferredDirection() bool {
173 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
176 // Returns whether the left connection should be preferred over the right one,
177 // considering only their networking properties. If ok is false, we can't
179 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
181 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
182 ml.NextBool(!l.utp(), !r.utp())
183 ml.NextBool(l.ipv6(), r.ipv6())
187 func (cn *peer) cumInterest() time.Duration {
188 ret := cn.priorInterest
190 ret += time.Since(cn.lastBecameInterested)
195 func (cn *PeerConn) peerHasAllPieces() (all bool, known bool) {
196 if cn.peerSentHaveAll {
199 if !cn.t.haveInfo() {
202 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
205 func (cn *PeerConn) locker() *lockWithDeferreds {
206 return cn.t.cl.locker()
209 func (cn *PeerConn) localAddr() net.Addr {
210 return cn.conn.LocalAddr()
213 func (cn *peer) supportsExtension(ext pp.ExtensionName) bool {
214 _, ok := cn.PeerExtensionIDs[ext]
218 // The best guess at number of pieces in the torrent for this peer.
219 func (cn *peer) bestPeerNumPieces() pieceIndex {
221 return cn.t.numPieces()
223 return cn.peerMinPieces
226 func (cn *peer) completedString() string {
227 have := pieceIndex(cn._peerPieces.Len())
228 if cn.peerSentHaveAll {
229 have = cn.bestPeerNumPieces()
231 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
234 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
235 cn.setNumPieces(info.NumPieces())
238 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
239 // receiving badly sized BITFIELD, or invalid HAVE messages.
240 func (cn *PeerConn) setNumPieces(num pieceIndex) {
241 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
242 cn.peerPiecesChanged()
245 func eventAgeString(t time.Time) string {
249 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
252 func (cn *PeerConn) connectionFlags() (ret string) {
254 ret += string([]byte{b})
256 if cn.cryptoMethod == mse.CryptoMethodRC4 {
258 } else if cn.headerEncrypted {
261 ret += string(cn.Discovery)
268 func (cn *PeerConn) utp() bool {
269 return parseNetworkString(cn.network).Udp
272 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
273 func (cn *peer) statusFlags() (ret string) {
275 ret += string([]byte{b})
284 ret += cn.connectionFlags()
286 if cn.peerInterested {
295 // func (cn *connection) String() string {
296 // var buf bytes.Buffer
297 // cn.writeStatus(&buf, nil)
298 // return buf.String()
301 func (cn *peer) downloadRate() float64 {
302 return float64(cn._stats.BytesReadUsefulData.Int64()) / cn.cumInterest().Seconds()
305 func (cn *peer) writeStatus(w io.Writer, t *Torrent) {
306 // \t isn't preserved in <pre> blocks?
307 fmt.Fprintln(w, cn.connStatusString())
308 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
309 eventAgeString(cn.lastMessageReceived),
310 eventAgeString(cn.completedHandshake),
311 eventAgeString(cn.lastHelpful()),
313 cn.totalExpectingTime(),
316 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
317 cn.completedString(),
318 len(cn.peerTouchedPieces),
319 &cn._stats.ChunksReadUseful,
320 &cn._stats.ChunksRead,
321 &cn._stats.ChunksWritten,
323 cn.numLocalRequests(),
324 cn.nominalMaxRequests(),
325 len(cn.peerRequests),
327 cn.downloadRate()/(1<<10),
329 fmt.Fprintf(w, " next pieces: %v%s\n",
330 iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
332 if cn == t.fastestPeer {
341 func (cn *peer) close() {
342 if !cn.closed.Set() {
345 cn.discardPieceInclination()
346 cn._pieceRequestOrder.Clear()
350 func (cn *PeerConn) _close() {
351 if cn.pex.IsEnabled() {
358 if cb := cn.t.cl.config.Callbacks.PeerConnClosed; cb != nil {
363 func (cn *peer) peerHasPiece(piece pieceIndex) bool {
364 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
367 // Writes a message into the write buffer.
368 func (cn *PeerConn) post(msg pp.Message) {
369 torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
370 // We don't need to track bytes here because a connection.w Writer wrapper
371 // takes care of that (although there's some delay between us recording
372 // the message, and the connection writer flushing it out.).
373 cn.writeBuffer.Write(msg.MustMarshalBinary())
374 // Last I checked only Piece messages affect stats, and we don't post
380 // Returns true if there's room to write more.
381 func (cn *PeerConn) write(msg pp.Message) bool {
383 cn.writeBuffer.Write(msg.MustMarshalBinary())
384 torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
385 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update
386 // when https://github.com/pion/datachannel/issues/59 is fixed.
387 return cn.writeBuffer.Len() < 1<<15
390 func (cn *PeerConn) requestMetadataPiece(index int) {
391 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
395 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
398 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
402 ExtendedPayload: func() []byte {
403 b, err := bencode.Marshal(map[string]int{
404 "msg_type": pp.RequestMetadataExtensionMsgType,
413 for index >= len(cn.metadataRequests) {
414 cn.metadataRequests = append(cn.metadataRequests, false)
416 cn.metadataRequests[index] = true
419 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
420 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
423 // The actual value to use as the maximum outbound requests.
424 func (cn *peer) nominalMaxRequests() (ret int) {
427 int64(cn.PeerMaxRequests),
428 int64(cn.t.requestStrategy.nominalMaxRequests(cn.requestStrategyConnection())),
432 func (cn *peer) totalExpectingTime() (ret time.Duration) {
433 ret = cn.cumulativeExpectedToReceiveChunks
434 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
435 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
441 func (cn *PeerConn) onPeerSentCancel(r request) {
442 if _, ok := cn.peerRequests[r]; !ok {
443 torrent.Add("unexpected cancels received", 1)
446 if cn.fastEnabled() {
449 delete(cn.peerRequests, r)
453 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
458 more = msg(pp.Message{
461 if cn.fastEnabled() {
462 for r := range cn.peerRequests {
463 // TODO: Don't reject pieces in allowed fast set.
467 cn.peerRequests = nil
472 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
477 return msg(pp.Message{
482 func (cn *peer) setInterested(interested bool) bool {
483 if cn.interested == interested {
486 cn.interested = interested
488 cn.lastBecameInterested = time.Now()
489 } else if !cn.lastBecameInterested.IsZero() {
490 cn.priorInterest += time.Since(cn.lastBecameInterested)
492 cn.updateExpectingChunks()
493 // log.Printf("%p: setting interest: %v", cn, interested)
494 return cn.writeInterested(interested)
497 func (pc *PeerConn) writeInterested(interested bool) bool {
498 return pc.write(pp.Message{
499 Type: func() pp.MessageType {
503 return pp.NotInterested
509 // The function takes a message to be sent, and returns true if more messages
511 type messageWriter func(pp.Message) bool
513 func (cn *peer) request(r request) bool {
514 if _, ok := cn.requests[r]; ok {
515 panic("chunk already requested")
517 if !cn.peerHasPiece(pieceIndex(r.Index)) {
518 panic("requesting piece peer doesn't have")
520 if !cn.t.peerIsActive(cn) {
521 panic("requesting but not in active conns")
523 if cn.closed.IsSet() {
524 panic("requesting when connection is closed")
527 if cn.peerAllowedFast.Get(int(r.Index)) {
528 torrent.Add("allowed fast requests sent", 1)
530 panic("requesting while choking and not allowed fast")
533 if cn.t.hashingPiece(pieceIndex(r.Index)) {
534 panic("piece is being hashed")
536 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
537 panic("piece is queued for hash")
539 if cn.requests == nil {
540 cn.requests = make(map[request]struct{})
542 cn.requests[r] = struct{}{}
543 if cn.validReceiveChunks == nil {
544 cn.validReceiveChunks = make(map[request]int)
546 cn.validReceiveChunks[r]++
547 cn.t.pendingRequests[r]++
548 cn.t.requestStrategy.hooks().sentRequest(r)
549 cn.updateExpectingChunks()
550 return cn.peerImpl.request(r)
553 func (me *PeerConn) request(r request) bool {
554 return me.write(pp.Message{
562 func (me *PeerConn) cancel(r request) bool {
563 return me.write(makeCancelMessage(r))
566 func (cn *peer) doRequestState() bool {
567 if !cn.t.networkingEnabled || cn.t.dataDownloadDisallowed {
568 if !cn.setInterested(false) {
571 if len(cn.requests) != 0 {
572 for r := range cn.requests {
574 // log.Printf("%p: cancelling request: %v", cn, r)
575 if !cn.peerImpl.cancel(r) {
580 } else if len(cn.requests) <= cn.requestsLowWater {
581 filledBuffer := false
582 cn.iterPendingPieces(func(pieceIndex pieceIndex) bool {
583 cn.iterPendingRequests(pieceIndex, func(r request) bool {
584 if !cn.setInterested(true) {
588 if len(cn.requests) >= cn.nominalMaxRequests() {
591 // Choking is looked at here because our interest is dependent
592 // on whether we'd make requests in its absence.
594 if !cn.peerAllowedFast.Get(bitmap.BitIndex(r.Index)) {
598 if _, ok := cn.requests[r]; ok {
601 filledBuffer = !cn.request(r)
607 // If we didn't completely top up the requests, we shouldn't mark
608 // the low water, since we'll want to top up the requests as soon
609 // as we have more write buffer space.
612 cn.requestsLowWater = len(cn.requests) / 2
617 func (cn *PeerConn) fillWriteBuffer() {
618 if !cn.doRequestState() {
621 if cn.pex.IsEnabled() {
622 if flow := cn.pex.Share(cn.write); !flow {
629 // Routine that writes to the peer. Some of what to write is buffered by
630 // activity elsewhere in the Client, and some is determined locally when the
631 // connection is writable.
632 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
634 lastWrite time.Time = time.Now()
635 keepAliveTimer *time.Timer
637 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
639 defer cn.locker().Unlock()
640 if time.Since(lastWrite) >= keepAliveTimeout {
643 keepAliveTimer.Reset(keepAliveTimeout)
646 defer cn.locker().Unlock()
648 defer keepAliveTimer.Stop()
649 frontBuf := new(bytes.Buffer)
651 if cn.closed.IsSet() {
654 if cn.writeBuffer.Len() == 0 {
657 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout {
658 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
659 postedKeepalives.Add(1)
661 if cn.writeBuffer.Len() == 0 {
662 // TODO: Minimize wakeups....
667 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
669 n, err := cn.w.Write(frontBuf.Bytes())
672 lastWrite = time.Now()
673 keepAliveTimer.Reset(keepAliveTimeout)
676 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
679 if n != frontBuf.Len() {
686 func (cn *PeerConn) have(piece pieceIndex) {
687 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
692 Index: pp.Integer(piece),
694 cn.sentHaves.Add(bitmap.BitIndex(piece))
697 func (cn *PeerConn) postBitfield() {
698 if cn.sentHaves.Len() != 0 {
699 panic("bitfield must be first have-related message sent")
701 if !cn.t.haveAnyPieces() {
706 Bitfield: cn.t.bitfield(),
708 cn.sentHaves = cn.t._completedPieces.Copy()
711 func (cn *PeerConn) updateRequests() {
712 // log.Print("update requests")
716 // Emits the indices in the Bitmaps bms in order, never repeating any index.
717 // skip is mutated during execution, and its initial values will never be
719 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
720 return func(cb iter.Callback) {
721 for _, bm := range bms {
723 func(i interface{}) bool {
727 bitmap.Sub(bm, *skip).Iter,
735 func iterUnbiasedPieceRequestOrder(cn requestStrategyConnection, f func(piece pieceIndex) bool) bool {
736 now, readahead := cn.torrent().readerPiecePriorities()
737 skip := bitmap.Flip(cn.peerPieces(), 0, cn.torrent().numPieces())
738 skip.Union(cn.torrent().ignorePieces())
739 // Return an iterator over the different priority classes, minus the skip pieces.
741 func(_piece interface{}) bool {
742 return f(pieceIndex(_piece.(bitmap.BitIndex)))
744 iterBitmapsDistinct(&skip, now, readahead),
745 // We have to iterate _pendingPieces separately because it isn't a Bitmap.
746 func(cb iter.Callback) {
747 cn.torrent().pendingPieces().IterTyped(func(piece int) bool {
748 if skip.Contains(piece) {
759 // The connection should download highest priority pieces first, without any inclination toward
760 // avoiding wastage. Generally we might do this if there's a single connection, or this is the
761 // fastest connection, and we have active readers that signal an ordering preference. It's
762 // conceivable that the best connection should do this, since it's least likely to waste our time if
763 // assigned to the highest priority pieces, and assigning more than one this role would cause
764 // significant wasted bandwidth.
765 func (cn *peer) shouldRequestWithoutBias() bool {
766 return cn.t.requestStrategy.shouldRequestWithoutBias(cn.requestStrategyConnection())
769 func (cn *peer) iterPendingPieces(f func(pieceIndex) bool) bool {
770 if !cn.t.haveInfo() {
773 return cn.t.requestStrategy.iterPendingPieces(cn, f)
775 func (cn *peer) iterPendingPiecesUntyped(f iter.Callback) {
776 cn.iterPendingPieces(func(i pieceIndex) bool { return f(i) })
779 func (cn *peer) iterPendingRequests(piece pieceIndex, f func(request) bool) bool {
780 return cn.t.requestStrategy.iterUndirtiedChunks(
781 cn.t.piece(piece).requestStrategyPiece(),
782 func(cs chunkSpec) bool {
783 return f(request{pp.Integer(piece), cs})
788 // check callers updaterequests
789 func (cn *peer) stopRequestingPiece(piece pieceIndex) bool {
790 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
793 // This is distinct from Torrent piece priority, which is the user's
794 // preference. Connection piece priority is specific to a connection and is
795 // used to pseudorandomly avoid connections always requesting the same pieces
796 // and thus wasting effort.
797 func (cn *peer) updatePiecePriority(piece pieceIndex) bool {
798 tpp := cn.t.piecePriority(piece)
799 if !cn.peerHasPiece(piece) {
800 tpp = PiecePriorityNone
802 if tpp == PiecePriorityNone {
803 return cn.stopRequestingPiece(piece)
805 prio := cn.getPieceInclination()[piece]
806 prio = cn.t.requestStrategy.piecePriority(cn, piece, tpp, prio)
807 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio) || cn.shouldRequestWithoutBias()
810 func (cn *peer) getPieceInclination() []int {
811 if cn.pieceInclination == nil {
812 cn.pieceInclination = cn.t.getConnPieceInclination()
814 return cn.pieceInclination
817 func (cn *peer) discardPieceInclination() {
818 if cn.pieceInclination == nil {
821 cn.t.putPieceInclination(cn.pieceInclination)
822 cn.pieceInclination = nil
825 func (cn *PeerConn) peerPiecesChanged() {
827 prioritiesChanged := false
828 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
829 if cn.updatePiecePriority(i) {
830 prioritiesChanged = true
833 if prioritiesChanged {
839 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
840 if newMin > cn.peerMinPieces {
841 cn.peerMinPieces = newMin
845 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
846 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
847 return errors.New("invalid piece")
849 if cn.peerHasPiece(piece) {
852 cn.raisePeerMinPieces(piece + 1)
853 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
854 if cn.updatePiecePriority(piece) {
860 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
861 cn.peerSentHaveAll = false
863 panic("expected bitfield length divisible by 8")
865 // We know that the last byte means that at most the last 7 bits are
867 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
868 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
869 // Ignore known excess pieces.
870 bf = bf[:cn.t.numPieces()]
872 for i, have := range bf {
874 cn.raisePeerMinPieces(pieceIndex(i) + 1)
876 cn._peerPieces.Set(i, have)
878 cn.peerPiecesChanged()
882 func (cn *PeerConn) onPeerSentHaveAll() error {
883 cn.peerSentHaveAll = true
884 cn._peerPieces.Clear()
885 cn.peerPiecesChanged()
889 func (cn *PeerConn) peerSentHaveNone() error {
890 cn._peerPieces.Clear()
891 cn.peerSentHaveAll = false
892 cn.peerPiecesChanged()
896 func (c *PeerConn) requestPendingMetadata() {
900 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
901 // Peer doesn't support this.
904 // Request metadata pieces that we don't have in a random order.
906 for index := 0; index < c.t.metadataPieceCount(); index++ {
907 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
908 pending = append(pending, index)
911 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
912 for _, i := range pending {
913 c.requestMetadataPiece(i)
917 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
918 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
919 if msg.Type == pp.Extended {
920 for name, id := range cn.PeerExtensionIDs {
921 if id != msg.ExtendedID {
924 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
927 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
930 func (cn *PeerConn) readMsg(msg *pp.Message) {
931 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
934 // After handshake, we know what Torrent and Client stats to include for a
936 func (cn *peer) postHandshakeStats(f func(*ConnStats)) {
942 // All ConnStats that include this connection. Some objects are not known
943 // until the handshake is complete, after which it's expected to reconcile the
945 func (cn *peer) allStats(f func(*ConnStats)) {
947 if cn.reconciledHandshakeStats {
948 cn.postHandshakeStats(f)
952 func (cn *PeerConn) wroteBytes(n int64) {
953 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
956 func (cn *PeerConn) readBytes(n int64) {
957 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
960 // Returns whether the connection could be useful to us. We're seeding and
961 // they want data, we don't have metainfo and they can provide it, etc.
962 func (c *peer) useful() bool {
964 if c.closed.IsSet() {
968 return c.supportsExtension("ut_metadata")
970 if t.seeding() && c.peerInterested {
973 if c.peerHasWantedPieces() {
979 func (c *peer) lastHelpful() (ret time.Time) {
980 ret = c.lastUsefulChunkReceived
981 if c.t.seeding() && c.lastChunkSent.After(ret) {
982 ret = c.lastChunkSent
987 func (c *PeerConn) fastEnabled() bool {
988 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
991 func (c *PeerConn) reject(r request) {
992 if !c.fastEnabled() {
993 panic("fast not enabled")
995 c.post(r.ToMsg(pp.Reject))
996 delete(c.peerRequests, r)
999 func (c *PeerConn) onReadRequest(r request) error {
1000 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
1001 if _, ok := c.peerRequests[r]; ok {
1002 torrent.Add("duplicate requests received", 1)
1006 torrent.Add("requests received while choking", 1)
1007 if c.fastEnabled() {
1008 torrent.Add("requests rejected while choking", 1)
1013 if len(c.peerRequests) >= maxRequests {
1014 torrent.Add("requests received while queue full", 1)
1015 if c.fastEnabled() {
1018 // BEP 6 says we may close here if we choose.
1021 if !c.t.havePiece(pieceIndex(r.Index)) {
1022 // This isn't necessarily them screwing up. We can drop pieces
1023 // from our storage, and can't communicate this to peers
1024 // except by reconnecting.
1025 requestsReceivedForMissingPieces.Add(1)
1026 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
1028 // Check this after we know we have the piece, so that the piece length will be known.
1029 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
1030 torrent.Add("bad requests received", 1)
1031 return errors.New("bad request")
1033 if c.peerRequests == nil {
1034 c.peerRequests = make(map[request]struct{}, maxRequests)
1036 c.peerRequests[r] = struct{}{}
1041 func runSafeExtraneous(f func()) {
1049 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1050 // exit. Returning will end the connection.
1051 func (c *PeerConn) mainReadLoop() (err error) {
1054 torrent.Add("connection.mainReadLoop returned with error", 1)
1056 torrent.Add("connection.mainReadLoop returned with no error", 1)
1062 decoder := pp.Decoder{
1063 R: bufio.NewReaderSize(c.r, 1<<17),
1064 MaxLength: 256 * 1024,
1072 err = decoder.Decode(&msg)
1074 if cb := cl.config.Callbacks.ReadMessage; cb != nil && err == nil {
1077 if t.closed.IsSet() || c.closed.IsSet() {
1084 c.lastMessageReceived = time.Now()
1086 receivedKeepalives.Add(1)
1089 messageTypesReceived.Add(msg.Type.String(), 1)
1090 if msg.Type.FastExtension() && !c.fastEnabled() {
1091 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1092 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1096 c.peerChoking = true
1097 if !c.fastEnabled() {
1098 c.deleteAllRequests()
1100 // We can then reset our interest.
1102 c.updateExpectingChunks()
1104 c.peerChoking = false
1106 c.updateExpectingChunks()
1108 c.peerInterested = true
1110 case pp.NotInterested:
1111 c.peerInterested = false
1112 // We don't clear their requests since it isn't clear in the spec.
1113 // We'll probably choke them for this, which will clear them if
1114 // appropriate, and is clearly specified.
1116 err = c.peerSentHave(pieceIndex(msg.Index))
1118 err = c.peerSentBitfield(msg.Bitfield)
1120 r := newRequestFromMessage(&msg)
1121 err = c.onReadRequest(r)
1123 err = c.receiveChunk(&msg)
1124 if len(msg.Piece) == int(t.chunkSize) {
1125 t.chunkPool.Put(&msg.Piece)
1128 err = fmt.Errorf("receiving chunk: %s", err)
1131 req := newRequestFromMessage(&msg)
1132 c.onPeerSentCancel(req)
1134 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1138 pingAddr := net.UDPAddr{
1143 pingAddr.Port = int(msg.Port)
1145 cl.eachDhtServer(func(s DhtServer) {
1146 go s.Ping(&pingAddr)
1149 torrent.Add("suggests received", 1)
1150 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1153 err = c.onPeerSentHaveAll()
1155 err = c.peerSentHaveNone()
1157 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1158 case pp.AllowedFast:
1159 torrent.Add("allowed fasts received", 1)
1160 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1161 c.peerAllowedFast.Add(int(msg.Index))
1164 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1166 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1174 func (c *peer) remoteRejectedRequest(r request) {
1175 if c.deleteRequest(r) {
1176 c.decExpectedChunkReceive(r)
1180 func (c *peer) decExpectedChunkReceive(r request) {
1181 count := c.validReceiveChunks[r]
1183 delete(c.validReceiveChunks, r)
1184 } else if count > 1 {
1185 c.validReceiveChunks[r] = count - 1
1191 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1193 // TODO: Should we still do this?
1195 // These clients use their own extension IDs for outgoing message
1196 // types, which is incorrect.
1197 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1205 case pp.HandshakeExtendedID:
1206 var d pp.ExtendedHandshakeMessage
1207 if err := bencode.Unmarshal(payload, &d); err != nil {
1208 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1209 return errors.Wrap(err, "unmarshalling extended handshake payload")
1211 if cb := cl.config.Callbacks.ReadExtendedHandshake; cb != nil {
1214 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1216 c.PeerMaxRequests = d.Reqq
1218 c.PeerClientName = d.V
1219 if c.PeerExtensionIDs == nil {
1220 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1222 c.PeerListenPort = d.Port
1223 c.PeerPrefersEncryption = d.Encryption
1224 for name, id := range d.M {
1225 if _, ok := c.PeerExtensionIDs[name]; !ok {
1226 torrent.Add(fmt.Sprintf("peers supporting extension %q", name), 1)
1228 c.PeerExtensionIDs[name] = id
1230 if d.MetadataSize != 0 {
1231 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1232 return errors.Wrapf(err, "setting metadata size to %d", d.MetadataSize)
1235 c.requestPendingMetadata()
1236 if !t.cl.config.DisablePEX {
1237 t.pex.Add(c) // we learnt enough now
1241 case metadataExtendedId:
1242 err := cl.gotMetadataExtensionMsg(payload, t, c)
1244 return fmt.Errorf("handling metadata extension message: %w", err)
1248 if !c.pex.IsEnabled() {
1249 return nil // or hang-up maybe?
1251 return c.pex.Recv(payload)
1253 return fmt.Errorf("unexpected extended message ID: %v", id)
1257 // Set both the Reader and Writer for the connection from a single ReadWriter.
1258 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1263 // Returns the Reader and Writer as a combined ReadWriter.
1264 func (cn *PeerConn) rw() io.ReadWriter {
1271 // Handle a received chunk from a peer.
1272 func (c *peer) receiveChunk(msg *pp.Message) error {
1275 torrent.Add("chunks received", 1)
1277 req := newRequestFromMessage(msg)
1280 torrent.Add("chunks received while choking", 1)
1283 if c.validReceiveChunks[req] <= 0 {
1284 torrent.Add("chunks received unexpected", 1)
1285 return errors.New("received unexpected chunk")
1287 c.decExpectedChunkReceive(req)
1289 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1290 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)
1302 // Do we actually want this chunk?
1303 if t.haveChunk(req) {
1304 torrent.Add("chunks received wasted", 1)
1305 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1309 piece := &t.pieces[req.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 }))
1313 c.lastUsefulChunkReceived = time.Now()
1314 // if t.fastestPeer != c {
1315 // log.Printf("setting fastest connection %p", c)
1319 // Need to record that it hasn't been written yet, before we attempt to do
1320 // anything with it.
1321 piece.incrementPendingWrites()
1322 // Record that we have the chunk, so we aren't trying to download it while
1323 // waiting for it to be written to storage.
1324 piece.unpendChunkIndex(chunkIndex(req.chunkSpec, t.chunkSize))
1326 // Cancel pending requests for this chunk.
1327 for c := range t.conns {
1331 err := func() error {
1334 concurrentChunkWrites.Add(1)
1335 defer concurrentChunkWrites.Add(-1)
1336 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1337 // number of connections. We write inline with receiving the chunk (with this lock dance),
1338 // because we want to handle errors synchronously and I haven't thought of a nice way to
1339 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1341 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1344 piece.decrementPendingWrites()
1347 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1349 //t.updatePieceCompletion(pieceIndex(msg.Index))
1350 t.onWriteChunkErr(err)
1354 c.onDirtiedPiece(pieceIndex(req.Index))
1356 if t.pieceAllDirty(pieceIndex(req.Index)) {
1357 t.queuePieceCheck(pieceIndex(req.Index))
1358 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1359 // chunk status (such as the haveChunk call above) to have to check all the various other
1360 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1361 // that chunk pieces are pended at an appropriate time later however.
1364 cl.event.Broadcast()
1365 // We do this because we've written a chunk, and may change PieceState.Partial.
1366 t.publishPieceChange(pieceIndex(req.Index))
1371 func (c *peer) onDirtiedPiece(piece pieceIndex) {
1372 if c.peerTouchedPieces == nil {
1373 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1375 c.peerTouchedPieces[piece] = struct{}{}
1376 ds := &c.t.pieces[piece].dirtiers
1378 *ds = make(map[*peer]struct{})
1380 (*ds)[c] = struct{}{}
1383 func (c *PeerConn) uploadAllowed() bool {
1384 if c.t.cl.config.NoUpload {
1387 if c.t.dataUploadDisallowed {
1393 if !c.peerHasWantedPieces() {
1396 // Don't upload more than 100 KiB more than we download.
1397 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1403 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1404 if c.uploadTimer == nil {
1405 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1407 c.uploadTimer.Reset(delay)
1411 // Also handles choking and unchoking of the remote peer.
1412 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1413 // Breaking or completing this loop means we don't want to upload to the
1414 // peer anymore, and we choke them.
1416 for c.uploadAllowed() {
1417 // We want to upload to the peer.
1418 if !c.unchoke(msg) {
1421 for r := range c.peerRequests {
1422 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1424 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1426 delay := res.Delay()
1429 c.setRetryUploadTimer(delay)
1430 // Hard to say what to return here.
1433 more, err := c.sendChunk(r, msg)
1435 c.logger.WithDefaultLevel(log.Warning).Printf("sending chunk to peer: %v", err)
1436 i := pieceIndex(r.Index)
1437 if c.t.pieceComplete(i) {
1438 // There used to be more code here that just duplicated the following break.
1439 // Piece completions are currently cached, so I'm not sure how helpful this
1440 // update is, except to pull any completion changes pushed to the storage
1441 // backend in failed reads that got us here.
1442 c.t.updatePieceCompletion(i)
1444 // If we failed to send a chunk, choke the peer by breaking out of the loop here to
1445 // ensure they flush all their requests. We've probably dropped a piece from
1446 // storage, but there's no way to communicate this to the peer. If they ask for it
1447 // again, we'll kick them to allow us to send them an updated bitfield on the next
1450 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1454 delete(c.peerRequests, r)
1465 func (cn *PeerConn) drop() {
1466 cn.t.dropConnection(cn)
1469 func (cn *peer) netGoodPiecesDirtied() int64 {
1470 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1473 func (c *peer) peerHasWantedPieces() bool {
1474 return !c._pieceRequestOrder.IsEmpty()
1477 func (c *peer) numLocalRequests() int {
1478 return len(c.requests)
1481 func (c *peer) deleteRequest(r request) bool {
1482 if _, ok := c.requests[r]; !ok {
1485 delete(c.requests, r)
1486 c.updateExpectingChunks()
1487 c.t.requestStrategy.hooks().deletedRequest(r)
1488 pr := c.t.pendingRequests
1498 c.t.iterPeers(func(_c *peer) {
1499 if !_c.interested && _c != c && c.peerHasPiece(pieceIndex(r.Index)) {
1506 func (c *peer) deleteAllRequests() {
1507 for r := range c.requests {
1510 if len(c.requests) != 0 {
1511 panic(len(c.requests))
1513 // for c := range c.t.conns {
1518 func (c *PeerConn) tickleWriter() {
1519 c.writerCond.Broadcast()
1522 func (c *peer) postCancel(r request) bool {
1523 if !c.deleteRequest(r) {
1526 c.peerImpl._postCancel(r)
1530 func (c *PeerConn) _postCancel(r request) {
1531 c.post(makeCancelMessage(r))
1534 func (c *PeerConn) sendChunk(r request, msg func(pp.Message) bool) (more bool, err error) {
1535 // Count the chunk being sent, even if it isn't.
1536 b := make([]byte, r.Length)
1537 p := c.t.info.Piece(int(r.Index))
1538 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1541 panic("expected error")
1544 } else if err == io.EOF {
1547 more = msg(pp.Message{
1553 c.lastChunkSent = time.Now()
1557 func (c *PeerConn) setTorrent(t *Torrent) {
1559 panic("connection already associated with a torrent")
1562 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1563 t.reconcileHandshakeStats(c)
1566 func (c *peer) peerPriority() (peerPriority, error) {
1567 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1570 func (c *peer) remoteIp() net.IP {
1571 return addrIpOrNil(c.RemoteAddr)
1574 func (c *peer) remoteIpPort() IpPort {
1575 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1576 return IpPort{ipa.IP, uint16(ipa.Port)}
1579 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1580 f := pp.PexPeerFlags(0)
1581 if c.PeerPrefersEncryption {
1582 f |= pp.PexPrefersEncryption
1585 f |= pp.PexOutgoingConn
1587 if c.RemoteAddr != nil && strings.Contains(c.RemoteAddr.Network(), "udp") {
1588 f |= pp.PexSupportsUtp
1593 func (c *PeerConn) dialAddr() net.Addr {
1594 if !c.outgoing && c.PeerListenPort != 0 {
1595 switch addr := c.RemoteAddr.(type) {
1598 dialAddr.Port = c.PeerListenPort
1602 dialAddr.Port = c.PeerListenPort
1609 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1610 f := c.pexPeerFlags()
1611 addr := c.dialAddr()
1612 return pexEvent{t, addr, f}
1615 func (c *PeerConn) String() string {
1616 return fmt.Sprintf("connection %p", c)
1619 func (c *peer) trust() connectionTrust {
1620 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1623 type connectionTrust struct {
1625 NetGoodPiecesDirted int64
1628 func (l connectionTrust) Less(r connectionTrust) bool {
1629 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1632 func (cn *peer) requestStrategyConnection() requestStrategyConnection {
1636 func (cn *peer) chunksReceivedWhileExpecting() int64 {
1637 return cn._chunksReceivedWhileExpecting
1640 func (cn *peer) fastest() bool {
1641 return cn == cn.t.fastestPeer
1644 func (cn *peer) peerMaxRequests() int {
1645 return cn.PeerMaxRequests
1648 // Returns the pieces the peer has claimed to have.
1649 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1651 defer cn.locker().RUnlock()
1652 return cn.peerPieces()
1655 func (cn *peer) peerPieces() bitmap.Bitmap {
1656 ret := cn._peerPieces.Copy()
1657 if cn.peerSentHaveAll {
1658 ret.AddRange(0, cn.t.numPieces())
1663 func (cn *peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1664 return &cn._pieceRequestOrder
1667 func (cn *peer) stats() *ConnStats {
1671 func (cn *peer) torrent() requestStrategyTorrent {
1672 return cn.t.requestStrategyTorrent()