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 *PeerConn) localAddr() net.Addr {
213 return cn.conn.LocalAddr()
216 func (cn *peer) supportsExtension(ext pp.ExtensionName) bool {
217 _, ok := cn.PeerExtensionIDs[ext]
221 // The best guess at number of pieces in the torrent for this peer.
222 func (cn *peer) bestPeerNumPieces() pieceIndex {
224 return cn.t.numPieces()
226 return cn.peerMinPieces
229 func (cn *peer) completedString() string {
230 have := pieceIndex(cn._peerPieces.Len())
231 if cn.peerSentHaveAll {
232 have = cn.bestPeerNumPieces()
234 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
237 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
238 cn.setNumPieces(info.NumPieces())
241 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
242 // receiving badly sized BITFIELD, or invalid HAVE messages.
243 func (cn *PeerConn) setNumPieces(num pieceIndex) {
244 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
245 cn.peerPiecesChanged()
248 func eventAgeString(t time.Time) string {
252 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
255 func (cn *PeerConn) connectionFlags() (ret string) {
257 ret += string([]byte{b})
259 if cn.cryptoMethod == mse.CryptoMethodRC4 {
261 } else if cn.headerEncrypted {
264 ret += string(cn.Discovery)
271 func (cn *PeerConn) utp() bool {
272 return parseNetworkString(cn.network).Udp
275 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
276 func (cn *peer) statusFlags() (ret string) {
278 ret += string([]byte{b})
287 ret += cn.connectionFlags()
289 if cn.peerInterested {
298 // func (cn *connection) String() string {
299 // var buf bytes.Buffer
300 // cn.writeStatus(&buf, nil)
301 // return buf.String()
304 func (cn *peer) downloadRate() float64 {
305 return float64(cn._stats.BytesReadUsefulData.Int64()) / cn.cumInterest().Seconds()
308 func (cn *peer) writeStatus(w io.Writer, t *Torrent) {
309 // \t isn't preserved in <pre> blocks?
310 fmt.Fprintln(w, cn.connStatusString())
311 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
312 eventAgeString(cn.lastMessageReceived),
313 eventAgeString(cn.completedHandshake),
314 eventAgeString(cn.lastHelpful()),
316 cn.totalExpectingTime(),
319 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
320 cn.completedString(),
321 len(cn.peerTouchedPieces),
322 &cn._stats.ChunksReadUseful,
323 &cn._stats.ChunksRead,
324 &cn._stats.ChunksWritten,
326 cn.numLocalRequests(),
327 cn.nominalMaxRequests(),
328 len(cn.peerRequests),
330 cn.downloadRate()/(1<<10),
332 fmt.Fprintf(w, " next pieces: %v%s\n",
333 iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
335 if cn == t.fastestPeer {
344 func (cn *peer) close() {
345 if !cn.closed.Set() {
348 cn.discardPieceInclination()
349 cn._pieceRequestOrder.Clear()
353 func (cn *PeerConn) _close() {
354 if cn.pex.IsEnabled() {
361 if cb := cn.callbacks.PeerConnClosed; cb != nil {
366 func (cn *peer) peerHasPiece(piece pieceIndex) bool {
367 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
370 // Writes a message into the write buffer.
371 func (cn *PeerConn) post(msg pp.Message) {
372 torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
373 // We don't need to track bytes here because a connection.w Writer wrapper
374 // takes care of that (although there's some delay between us recording
375 // the message, and the connection writer flushing it out.).
376 cn.writeBuffer.Write(msg.MustMarshalBinary())
377 // Last I checked only Piece messages affect stats, and we don't post
383 // Returns true if there's room to write more.
384 func (cn *PeerConn) write(msg pp.Message) bool {
386 cn.writeBuffer.Write(msg.MustMarshalBinary())
387 torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
388 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update
389 // when https://github.com/pion/datachannel/issues/59 is fixed.
390 return cn.writeBuffer.Len() < 1<<15
393 func (cn *PeerConn) requestMetadataPiece(index int) {
394 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
398 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
401 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
405 ExtendedPayload: func() []byte {
406 b, err := bencode.Marshal(map[string]int{
407 "msg_type": pp.RequestMetadataExtensionMsgType,
416 for index >= len(cn.metadataRequests) {
417 cn.metadataRequests = append(cn.metadataRequests, false)
419 cn.metadataRequests[index] = true
422 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
423 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
426 // The actual value to use as the maximum outbound requests.
427 func (cn *peer) nominalMaxRequests() (ret int) {
430 int64(cn.PeerMaxRequests),
431 int64(cn.t.requestStrategy.nominalMaxRequests(cn.requestStrategyConnection())),
435 func (cn *peer) totalExpectingTime() (ret time.Duration) {
436 ret = cn.cumulativeExpectedToReceiveChunks
437 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
438 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
444 func (cn *PeerConn) onPeerSentCancel(r request) {
445 if _, ok := cn.peerRequests[r]; !ok {
446 torrent.Add("unexpected cancels received", 1)
449 if cn.fastEnabled() {
452 delete(cn.peerRequests, r)
456 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
461 more = msg(pp.Message{
464 if cn.fastEnabled() {
465 for r := range cn.peerRequests {
466 // TODO: Don't reject pieces in allowed fast set.
470 cn.peerRequests = nil
475 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
480 return msg(pp.Message{
485 func (cn *peer) setInterested(interested bool) bool {
486 if cn.interested == interested {
489 cn.interested = interested
491 cn.lastBecameInterested = time.Now()
492 } else if !cn.lastBecameInterested.IsZero() {
493 cn.priorInterest += time.Since(cn.lastBecameInterested)
495 cn.updateExpectingChunks()
496 // log.Printf("%p: setting interest: %v", cn, interested)
497 return cn.writeInterested(interested)
500 func (pc *PeerConn) writeInterested(interested bool) bool {
501 return pc.write(pp.Message{
502 Type: func() pp.MessageType {
506 return pp.NotInterested
512 // The function takes a message to be sent, and returns true if more messages
514 type messageWriter func(pp.Message) bool
516 func (cn *peer) request(r request) bool {
517 if _, ok := cn.requests[r]; ok {
518 panic("chunk already requested")
520 if !cn.peerHasPiece(pieceIndex(r.Index)) {
521 panic("requesting piece peer doesn't have")
523 if !cn.t.peerIsActive(cn) {
524 panic("requesting but not in active conns")
526 if cn.closed.IsSet() {
527 panic("requesting when connection is closed")
530 if cn.peerAllowedFast.Get(int(r.Index)) {
531 torrent.Add("allowed fast requests sent", 1)
533 panic("requesting while choking and not allowed fast")
536 if cn.t.hashingPiece(pieceIndex(r.Index)) {
537 panic("piece is being hashed")
539 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
540 panic("piece is queued for hash")
542 if cn.requests == nil {
543 cn.requests = make(map[request]struct{})
545 cn.requests[r] = struct{}{}
546 if cn.validReceiveChunks == nil {
547 cn.validReceiveChunks = make(map[request]int)
549 cn.validReceiveChunks[r]++
550 cn.t.pendingRequests[r]++
551 cn.t.requestStrategy.hooks().sentRequest(r)
552 cn.updateExpectingChunks()
553 return cn.peerImpl.request(r)
556 func (me *PeerConn) request(r request) bool {
557 return me.write(pp.Message{
565 func (me *PeerConn) cancel(r request) bool {
566 return me.write(makeCancelMessage(r))
569 func (cn *peer) doRequestState() bool {
570 if !cn.t.networkingEnabled || cn.t.dataDownloadDisallowed {
571 if !cn.setInterested(false) {
574 if len(cn.requests) != 0 {
575 for r := range cn.requests {
577 // log.Printf("%p: cancelling request: %v", cn, r)
578 if !cn.peerImpl.cancel(r) {
583 } else if len(cn.requests) <= cn.requestsLowWater {
584 filledBuffer := false
585 cn.iterPendingPieces(func(pieceIndex pieceIndex) bool {
586 cn.iterPendingRequests(pieceIndex, func(r request) bool {
587 if !cn.setInterested(true) {
591 if len(cn.requests) >= cn.nominalMaxRequests() {
594 // Choking is looked at here because our interest is dependent
595 // on whether we'd make requests in its absence.
597 if !cn.peerAllowedFast.Get(bitmap.BitIndex(r.Index)) {
601 if _, ok := cn.requests[r]; ok {
604 filledBuffer = !cn.request(r)
610 // If we didn't completely top up the requests, we shouldn't mark
611 // the low water, since we'll want to top up the requests as soon
612 // as we have more write buffer space.
615 cn.requestsLowWater = len(cn.requests) / 2
620 func (cn *PeerConn) fillWriteBuffer() {
621 if !cn.doRequestState() {
624 if cn.pex.IsEnabled() {
625 if flow := cn.pex.Share(cn.write); !flow {
632 // Routine that writes to the peer. Some of what to write is buffered by
633 // activity elsewhere in the Client, and some is determined locally when the
634 // connection is writable.
635 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
637 lastWrite time.Time = time.Now()
638 keepAliveTimer *time.Timer
640 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
642 defer cn.locker().Unlock()
643 if time.Since(lastWrite) >= keepAliveTimeout {
646 keepAliveTimer.Reset(keepAliveTimeout)
649 defer cn.locker().Unlock()
651 defer keepAliveTimer.Stop()
652 frontBuf := new(bytes.Buffer)
654 if cn.closed.IsSet() {
657 if cn.writeBuffer.Len() == 0 {
660 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout {
661 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
662 postedKeepalives.Add(1)
664 if cn.writeBuffer.Len() == 0 {
665 // TODO: Minimize wakeups....
670 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
672 n, err := cn.w.Write(frontBuf.Bytes())
675 lastWrite = time.Now()
676 keepAliveTimer.Reset(keepAliveTimeout)
679 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
682 if n != frontBuf.Len() {
689 func (cn *PeerConn) have(piece pieceIndex) {
690 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
695 Index: pp.Integer(piece),
697 cn.sentHaves.Add(bitmap.BitIndex(piece))
700 func (cn *PeerConn) postBitfield() {
701 if cn.sentHaves.Len() != 0 {
702 panic("bitfield must be first have-related message sent")
704 if !cn.t.haveAnyPieces() {
709 Bitfield: cn.t.bitfield(),
711 cn.sentHaves = cn.t._completedPieces.Copy()
714 func (cn *PeerConn) updateRequests() {
715 // log.Print("update requests")
719 // Emits the indices in the Bitmaps bms in order, never repeating any index.
720 // skip is mutated during execution, and its initial values will never be
722 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
723 return func(cb iter.Callback) {
724 for _, bm := range bms {
726 func(i interface{}) bool {
730 bitmap.Sub(bm, *skip).Iter,
738 func iterUnbiasedPieceRequestOrder(cn requestStrategyConnection, f func(piece pieceIndex) bool) bool {
739 now, readahead := cn.torrent().readerPiecePriorities()
740 skip := bitmap.Flip(cn.peerPieces(), 0, cn.torrent().numPieces())
741 skip.Union(cn.torrent().ignorePieces())
742 // Return an iterator over the different priority classes, minus the skip pieces.
744 func(_piece interface{}) bool {
745 return f(pieceIndex(_piece.(bitmap.BitIndex)))
747 iterBitmapsDistinct(&skip, now, readahead),
748 // We have to iterate _pendingPieces separately because it isn't a Bitmap.
749 func(cb iter.Callback) {
750 cn.torrent().pendingPieces().IterTyped(func(piece int) bool {
751 if skip.Contains(piece) {
762 // The connection should download highest priority pieces first, without any inclination toward
763 // avoiding wastage. Generally we might do this if there's a single connection, or this is the
764 // fastest connection, and we have active readers that signal an ordering preference. It's
765 // conceivable that the best connection should do this, since it's least likely to waste our time if
766 // assigned to the highest priority pieces, and assigning more than one this role would cause
767 // significant wasted bandwidth.
768 func (cn *peer) shouldRequestWithoutBias() bool {
769 return cn.t.requestStrategy.shouldRequestWithoutBias(cn.requestStrategyConnection())
772 func (cn *peer) iterPendingPieces(f func(pieceIndex) bool) bool {
773 if !cn.t.haveInfo() {
776 return cn.t.requestStrategy.iterPendingPieces(cn, f)
778 func (cn *peer) iterPendingPiecesUntyped(f iter.Callback) {
779 cn.iterPendingPieces(func(i pieceIndex) bool { return f(i) })
782 func (cn *peer) iterPendingRequests(piece pieceIndex, f func(request) bool) bool {
783 return cn.t.requestStrategy.iterUndirtiedChunks(
784 cn.t.piece(piece).requestStrategyPiece(),
785 func(cs chunkSpec) bool {
786 return f(request{pp.Integer(piece), cs})
791 // check callers updaterequests
792 func (cn *peer) stopRequestingPiece(piece pieceIndex) bool {
793 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
796 // This is distinct from Torrent piece priority, which is the user's
797 // preference. Connection piece priority is specific to a connection and is
798 // used to pseudorandomly avoid connections always requesting the same pieces
799 // and thus wasting effort.
800 func (cn *peer) updatePiecePriority(piece pieceIndex) bool {
801 tpp := cn.t.piecePriority(piece)
802 if !cn.peerHasPiece(piece) {
803 tpp = PiecePriorityNone
805 if tpp == PiecePriorityNone {
806 return cn.stopRequestingPiece(piece)
808 prio := cn.getPieceInclination()[piece]
809 prio = cn.t.requestStrategy.piecePriority(cn, piece, tpp, prio)
810 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio) || cn.shouldRequestWithoutBias()
813 func (cn *peer) getPieceInclination() []int {
814 if cn.pieceInclination == nil {
815 cn.pieceInclination = cn.t.getConnPieceInclination()
817 return cn.pieceInclination
820 func (cn *peer) discardPieceInclination() {
821 if cn.pieceInclination == nil {
824 cn.t.putPieceInclination(cn.pieceInclination)
825 cn.pieceInclination = nil
828 func (cn *PeerConn) peerPiecesChanged() {
830 prioritiesChanged := false
831 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
832 if cn.updatePiecePriority(i) {
833 prioritiesChanged = true
836 if prioritiesChanged {
842 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
843 if newMin > cn.peerMinPieces {
844 cn.peerMinPieces = newMin
848 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
849 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
850 return errors.New("invalid piece")
852 if cn.peerHasPiece(piece) {
855 cn.raisePeerMinPieces(piece + 1)
856 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
857 if cn.updatePiecePriority(piece) {
863 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
864 cn.peerSentHaveAll = false
866 panic("expected bitfield length divisible by 8")
868 // We know that the last byte means that at most the last 7 bits are
870 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
871 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
872 // Ignore known excess pieces.
873 bf = bf[:cn.t.numPieces()]
875 for i, have := range bf {
877 cn.raisePeerMinPieces(pieceIndex(i) + 1)
879 cn._peerPieces.Set(i, have)
881 cn.peerPiecesChanged()
885 func (cn *PeerConn) onPeerSentHaveAll() error {
886 cn.peerSentHaveAll = true
887 cn._peerPieces.Clear()
888 cn.peerPiecesChanged()
892 func (cn *PeerConn) peerSentHaveNone() error {
893 cn._peerPieces.Clear()
894 cn.peerSentHaveAll = false
895 cn.peerPiecesChanged()
899 func (c *PeerConn) requestPendingMetadata() {
903 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
904 // Peer doesn't support this.
907 // Request metadata pieces that we don't have in a random order.
909 for index := 0; index < c.t.metadataPieceCount(); index++ {
910 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
911 pending = append(pending, index)
914 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
915 for _, i := range pending {
916 c.requestMetadataPiece(i)
920 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
921 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
922 if msg.Type == pp.Extended {
923 for name, id := range cn.PeerExtensionIDs {
924 if id != msg.ExtendedID {
927 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
930 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
933 func (cn *PeerConn) readMsg(msg *pp.Message) {
934 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
937 // After handshake, we know what Torrent and Client stats to include for a
939 func (cn *peer) postHandshakeStats(f func(*ConnStats)) {
945 // All ConnStats that include this connection. Some objects are not known
946 // until the handshake is complete, after which it's expected to reconcile the
948 func (cn *peer) allStats(f func(*ConnStats)) {
950 if cn.reconciledHandshakeStats {
951 cn.postHandshakeStats(f)
955 func (cn *PeerConn) wroteBytes(n int64) {
956 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
959 func (cn *PeerConn) readBytes(n int64) {
960 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
963 // Returns whether the connection could be useful to us. We're seeding and
964 // they want data, we don't have metainfo and they can provide it, etc.
965 func (c *peer) useful() bool {
967 if c.closed.IsSet() {
971 return c.supportsExtension("ut_metadata")
973 if t.seeding() && c.peerInterested {
976 if c.peerHasWantedPieces() {
982 func (c *peer) lastHelpful() (ret time.Time) {
983 ret = c.lastUsefulChunkReceived
984 if c.t.seeding() && c.lastChunkSent.After(ret) {
985 ret = c.lastChunkSent
990 func (c *PeerConn) fastEnabled() bool {
991 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
994 func (c *PeerConn) reject(r request) {
995 if !c.fastEnabled() {
996 panic("fast not enabled")
998 c.post(r.ToMsg(pp.Reject))
999 delete(c.peerRequests, r)
1002 func (c *PeerConn) onReadRequest(r request) error {
1003 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
1004 if _, ok := c.peerRequests[r]; ok {
1005 torrent.Add("duplicate requests received", 1)
1009 torrent.Add("requests received while choking", 1)
1010 if c.fastEnabled() {
1011 torrent.Add("requests rejected while choking", 1)
1016 if len(c.peerRequests) >= maxRequests {
1017 torrent.Add("requests received while queue full", 1)
1018 if c.fastEnabled() {
1021 // BEP 6 says we may close here if we choose.
1024 if !c.t.havePiece(pieceIndex(r.Index)) {
1025 // This isn't necessarily them screwing up. We can drop pieces
1026 // from our storage, and can't communicate this to peers
1027 // except by reconnecting.
1028 requestsReceivedForMissingPieces.Add(1)
1029 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
1031 // Check this after we know we have the piece, so that the piece length will be known.
1032 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
1033 torrent.Add("bad requests received", 1)
1034 return errors.New("bad request")
1036 if c.peerRequests == nil {
1037 c.peerRequests = make(map[request]struct{}, maxRequests)
1039 c.peerRequests[r] = struct{}{}
1044 func runSafeExtraneous(f func()) {
1052 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1053 // exit. Returning will end the connection.
1054 func (c *PeerConn) mainReadLoop() (err error) {
1057 torrent.Add("connection.mainReadLoop returned with error", 1)
1059 torrent.Add("connection.mainReadLoop returned with no error", 1)
1065 decoder := pp.Decoder{
1066 R: bufio.NewReaderSize(c.r, 1<<17),
1067 MaxLength: 256 * 1024,
1075 err = decoder.Decode(&msg)
1077 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1080 if t.closed.IsSet() || c.closed.IsSet() {
1087 c.lastMessageReceived = time.Now()
1089 receivedKeepalives.Add(1)
1092 messageTypesReceived.Add(msg.Type.String(), 1)
1093 if msg.Type.FastExtension() && !c.fastEnabled() {
1094 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1095 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1099 c.peerChoking = true
1100 if !c.fastEnabled() {
1101 c.deleteAllRequests()
1103 // We can then reset our interest.
1105 c.updateExpectingChunks()
1107 c.peerChoking = false
1109 c.updateExpectingChunks()
1111 c.peerInterested = true
1113 case pp.NotInterested:
1114 c.peerInterested = false
1115 // We don't clear their requests since it isn't clear in the spec.
1116 // We'll probably choke them for this, which will clear them if
1117 // appropriate, and is clearly specified.
1119 err = c.peerSentHave(pieceIndex(msg.Index))
1121 err = c.peerSentBitfield(msg.Bitfield)
1123 r := newRequestFromMessage(&msg)
1124 err = c.onReadRequest(r)
1126 err = c.receiveChunk(&msg)
1127 if len(msg.Piece) == int(t.chunkSize) {
1128 t.chunkPool.Put(&msg.Piece)
1131 err = fmt.Errorf("receiving chunk: %s", err)
1134 req := newRequestFromMessage(&msg)
1135 c.onPeerSentCancel(req)
1137 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1141 pingAddr := net.UDPAddr{
1146 pingAddr.Port = int(msg.Port)
1148 cl.eachDhtServer(func(s DhtServer) {
1149 go s.Ping(&pingAddr)
1152 torrent.Add("suggests received", 1)
1153 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1156 err = c.onPeerSentHaveAll()
1158 err = c.peerSentHaveNone()
1160 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1161 case pp.AllowedFast:
1162 torrent.Add("allowed fasts received", 1)
1163 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1164 c.peerAllowedFast.Add(int(msg.Index))
1167 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1169 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1177 func (c *peer) remoteRejectedRequest(r request) {
1178 if c.deleteRequest(r) {
1179 c.decExpectedChunkReceive(r)
1183 func (c *peer) decExpectedChunkReceive(r request) {
1184 count := c.validReceiveChunks[r]
1186 delete(c.validReceiveChunks, r)
1187 } else if count > 1 {
1188 c.validReceiveChunks[r] = count - 1
1194 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1196 // TODO: Should we still do this?
1198 // These clients use their own extension IDs for outgoing message
1199 // types, which is incorrect.
1200 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1208 case pp.HandshakeExtendedID:
1209 var d pp.ExtendedHandshakeMessage
1210 if err := bencode.Unmarshal(payload, &d); err != nil {
1211 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1212 return errors.Wrap(err, "unmarshalling extended handshake payload")
1214 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1217 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1219 c.PeerMaxRequests = d.Reqq
1221 c.PeerClientName = d.V
1222 if c.PeerExtensionIDs == nil {
1223 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1225 c.PeerListenPort = d.Port
1226 c.PeerPrefersEncryption = d.Encryption
1227 for name, id := range d.M {
1228 if _, ok := c.PeerExtensionIDs[name]; !ok {
1229 torrent.Add(fmt.Sprintf("peers supporting extension %q", name), 1)
1231 c.PeerExtensionIDs[name] = id
1233 if d.MetadataSize != 0 {
1234 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1235 return errors.Wrapf(err, "setting metadata size to %d", d.MetadataSize)
1238 c.requestPendingMetadata()
1239 if !t.cl.config.DisablePEX {
1240 t.pex.Add(c) // we learnt enough now
1244 case metadataExtendedId:
1245 err := cl.gotMetadataExtensionMsg(payload, t, c)
1247 return fmt.Errorf("handling metadata extension message: %w", err)
1251 if !c.pex.IsEnabled() {
1252 return nil // or hang-up maybe?
1254 return c.pex.Recv(payload)
1256 return fmt.Errorf("unexpected extended message ID: %v", id)
1260 // Set both the Reader and Writer for the connection from a single ReadWriter.
1261 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1266 // Returns the Reader and Writer as a combined ReadWriter.
1267 func (cn *PeerConn) rw() io.ReadWriter {
1274 // Handle a received chunk from a peer.
1275 func (c *peer) receiveChunk(msg *pp.Message) error {
1278 torrent.Add("chunks received", 1)
1280 req := newRequestFromMessage(msg)
1283 torrent.Add("chunks received while choking", 1)
1286 if c.validReceiveChunks[req] <= 0 {
1287 torrent.Add("chunks received unexpected", 1)
1288 return errors.New("received unexpected chunk")
1290 c.decExpectedChunkReceive(req)
1292 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1293 torrent.Add("chunks received due to allowed fast", 1)
1296 // Request has been satisfied.
1297 if c.deleteRequest(req) {
1298 if c.expectingChunks() {
1299 c._chunksReceivedWhileExpecting++
1302 torrent.Add("chunks received unwanted", 1)
1305 // Do we actually want this chunk?
1306 if t.haveChunk(req) {
1307 torrent.Add("chunks received wasted", 1)
1308 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1312 piece := &t.pieces[req.Index]
1314 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1315 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1316 c.lastUsefulChunkReceived = time.Now()
1317 // if t.fastestPeer != c {
1318 // log.Printf("setting fastest connection %p", c)
1322 // Need to record that it hasn't been written yet, before we attempt to do
1323 // anything with it.
1324 piece.incrementPendingWrites()
1325 // Record that we have the chunk, so we aren't trying to download it while
1326 // waiting for it to be written to storage.
1327 piece.unpendChunkIndex(chunkIndex(req.chunkSpec, t.chunkSize))
1329 // Cancel pending requests for this chunk.
1330 for c := range t.conns {
1334 err := func() error {
1337 concurrentChunkWrites.Add(1)
1338 defer concurrentChunkWrites.Add(-1)
1339 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1340 // number of connections. We write inline with receiving the chunk (with this lock dance),
1341 // because we want to handle errors synchronously and I haven't thought of a nice way to
1342 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1344 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1347 piece.decrementPendingWrites()
1350 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1352 //t.updatePieceCompletion(pieceIndex(msg.Index))
1353 t.onWriteChunkErr(err)
1357 c.onDirtiedPiece(pieceIndex(req.Index))
1359 if t.pieceAllDirty(pieceIndex(req.Index)) {
1360 t.queuePieceCheck(pieceIndex(req.Index))
1361 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1362 // chunk status (such as the haveChunk call above) to have to check all the various other
1363 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1364 // that chunk pieces are pended at an appropriate time later however.
1367 cl.event.Broadcast()
1368 // We do this because we've written a chunk, and may change PieceState.Partial.
1369 t.publishPieceChange(pieceIndex(req.Index))
1374 func (c *peer) onDirtiedPiece(piece pieceIndex) {
1375 if c.peerTouchedPieces == nil {
1376 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1378 c.peerTouchedPieces[piece] = struct{}{}
1379 ds := &c.t.pieces[piece].dirtiers
1381 *ds = make(map[*peer]struct{})
1383 (*ds)[c] = struct{}{}
1386 func (c *PeerConn) uploadAllowed() bool {
1387 if c.t.cl.config.NoUpload {
1390 if c.t.dataUploadDisallowed {
1396 if !c.peerHasWantedPieces() {
1399 // Don't upload more than 100 KiB more than we download.
1400 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1406 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1407 if c.uploadTimer == nil {
1408 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1410 c.uploadTimer.Reset(delay)
1414 // Also handles choking and unchoking of the remote peer.
1415 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1416 // Breaking or completing this loop means we don't want to upload to the
1417 // peer anymore, and we choke them.
1419 for c.uploadAllowed() {
1420 // We want to upload to the peer.
1421 if !c.unchoke(msg) {
1424 for r := range c.peerRequests {
1425 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1427 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1429 delay := res.Delay()
1432 c.setRetryUploadTimer(delay)
1433 // Hard to say what to return here.
1436 more, err := c.sendChunk(r, msg)
1438 c.logger.WithDefaultLevel(log.Warning).Printf("sending chunk to peer: %v", err)
1439 i := pieceIndex(r.Index)
1440 if c.t.pieceComplete(i) {
1441 // There used to be more code here that just duplicated the following break.
1442 // Piece completions are currently cached, so I'm not sure how helpful this
1443 // update is, except to pull any completion changes pushed to the storage
1444 // backend in failed reads that got us here.
1445 c.t.updatePieceCompletion(i)
1447 // If we failed to send a chunk, choke the peer by breaking out of the loop here to
1448 // ensure they flush all their requests. We've probably dropped a piece from
1449 // storage, but there's no way to communicate this to the peer. If they ask for it
1450 // again, we'll kick them to allow us to send them an updated bitfield on the next
1453 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1457 delete(c.peerRequests, r)
1468 func (cn *PeerConn) drop() {
1469 cn.t.dropConnection(cn)
1472 func (cn *peer) netGoodPiecesDirtied() int64 {
1473 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1476 func (c *peer) peerHasWantedPieces() bool {
1477 return !c._pieceRequestOrder.IsEmpty()
1480 func (c *peer) numLocalRequests() int {
1481 return len(c.requests)
1484 func (c *peer) deleteRequest(r request) bool {
1485 if _, ok := c.requests[r]; !ok {
1488 delete(c.requests, r)
1489 c.updateExpectingChunks()
1490 c.t.requestStrategy.hooks().deletedRequest(r)
1491 pr := c.t.pendingRequests
1501 c.t.iterPeers(func(_c *peer) {
1502 if !_c.interested && _c != c && c.peerHasPiece(pieceIndex(r.Index)) {
1509 func (c *peer) deleteAllRequests() {
1510 for r := range c.requests {
1513 if len(c.requests) != 0 {
1514 panic(len(c.requests))
1516 // for c := range c.t.conns {
1521 func (c *PeerConn) tickleWriter() {
1522 c.writerCond.Broadcast()
1525 func (c *peer) postCancel(r request) bool {
1526 if !c.deleteRequest(r) {
1529 c.peerImpl._postCancel(r)
1533 func (c *PeerConn) _postCancel(r request) {
1534 c.post(makeCancelMessage(r))
1537 func (c *PeerConn) sendChunk(r request, msg func(pp.Message) bool) (more bool, err error) {
1538 // Count the chunk being sent, even if it isn't.
1539 b := make([]byte, r.Length)
1540 p := c.t.info.Piece(int(r.Index))
1541 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1544 panic("expected error")
1547 } else if err == io.EOF {
1550 more = msg(pp.Message{
1556 c.lastChunkSent = time.Now()
1560 func (c *PeerConn) setTorrent(t *Torrent) {
1562 panic("connection already associated with a torrent")
1565 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1566 t.reconcileHandshakeStats(c)
1569 func (c *peer) peerPriority() (peerPriority, error) {
1570 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1573 func (c *peer) remoteIp() net.IP {
1574 return addrIpOrNil(c.RemoteAddr)
1577 func (c *peer) remoteIpPort() IpPort {
1578 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1579 return IpPort{ipa.IP, uint16(ipa.Port)}
1582 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1583 f := pp.PexPeerFlags(0)
1584 if c.PeerPrefersEncryption {
1585 f |= pp.PexPrefersEncryption
1588 f |= pp.PexOutgoingConn
1590 if c.RemoteAddr != nil && strings.Contains(c.RemoteAddr.Network(), "udp") {
1591 f |= pp.PexSupportsUtp
1596 func (c *PeerConn) dialAddr() net.Addr {
1597 if !c.outgoing && c.PeerListenPort != 0 {
1598 switch addr := c.RemoteAddr.(type) {
1601 dialAddr.Port = c.PeerListenPort
1605 dialAddr.Port = c.PeerListenPort
1612 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1613 f := c.pexPeerFlags()
1614 addr := c.dialAddr()
1615 return pexEvent{t, addr, f}
1618 func (c *PeerConn) String() string {
1619 return fmt.Sprintf("connection %p", c)
1622 func (c *peer) trust() connectionTrust {
1623 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1626 type connectionTrust struct {
1628 NetGoodPiecesDirted int64
1631 func (l connectionTrust) Less(r connectionTrust) bool {
1632 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1635 func (cn *peer) requestStrategyConnection() requestStrategyConnection {
1639 func (cn *peer) chunksReceivedWhileExpecting() int64 {
1640 return cn._chunksReceivedWhileExpecting
1643 func (cn *peer) fastest() bool {
1644 return cn == cn.t.fastestPeer
1647 func (cn *peer) peerMaxRequests() int {
1648 return cn.PeerMaxRequests
1651 // Returns the pieces the peer has claimed to have.
1652 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1654 defer cn.locker().RUnlock()
1655 return cn.peerPieces()
1658 func (cn *peer) peerPieces() bitmap.Bitmap {
1659 ret := cn._peerPieces.Copy()
1660 if cn.peerSentHaveAll {
1661 ret.AddRange(0, cn.t.numPieces())
1666 func (cn *peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1667 return &cn._pieceRequestOrder
1670 func (cn *peer) stats() *ConnStats {
1674 func (cn *peer) torrent() requestStrategyTorrent {
1675 return cn.t.requestStrategyTorrent()