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.
37 // The peer was given directly, such as through a magnet link.
38 PeerSourceDirect = "M"
41 type peerRequestState struct {
45 type PeerRemoteAddr interface {
50 // First to ensure 64-bit alignment for atomics. See #262.
60 RemoteAddr PeerRemoteAddr
61 // True if the connection is operating over MSE obfuscation.
63 cryptoMethod mse.CryptoMethod
66 closed missinggo.Event
67 // Set true after we've added our ConnStats generated during handshake to
68 // other ConnStat instances as determined when the *Torrent became known.
69 reconciledHandshakeStats bool
71 lastMessageReceived time.Time
72 completedHandshake time.Time
73 lastUsefulChunkReceived time.Time
74 lastChunkSent time.Time
76 // Stuff controlled by the local peer.
78 lastBecameInterested time.Time
79 priorInterest time.Duration
81 lastStartedExpectingToReceiveChunks time.Time
82 cumulativeExpectedToReceiveChunks time.Duration
83 _chunksReceivedWhileExpecting int64
86 requests map[Request]struct{}
88 // Chunks that we might reasonably expect to receive from the peer. Due to
89 // latency, buffering, and implementation differences, we may receive
90 // chunks that are no longer in the set of requests actually want.
91 validReceiveChunks map[Request]int
92 // Indexed by metadata piece, set to true if posted and pending a
94 metadataRequests []bool
95 sentHaves bitmap.Bitmap
97 // Stuff controlled by the remote peer.
100 peerRequests map[Request]*peerRequestState
101 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
103 // The pieces the peer has claimed to have.
104 _peerPieces bitmap.Bitmap
105 // The peer has everything. This can occur due to a special message, when
106 // we may not even know the number of pieces in the torrent yet.
108 // The highest possible number of pieces the torrent could have based on
109 // communication with the peer. Generally only useful until we have the
111 peerMinPieces pieceIndex
112 // Pieces we've accepted chunks for from the peer.
113 peerTouchedPieces map[pieceIndex]struct{}
114 peerAllowedFast bitmap.Bitmap
116 PeerMaxRequests int // Maximum pending requests the peer allows.
117 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
118 PeerClientName string
120 pieceInclination []int
121 _pieceRequestOrder prioritybitmap.PriorityBitmap
126 // Maintains the state of a BitTorrent-protocol based connection with a peer.
127 type PeerConn struct {
130 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
131 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
136 PeerExtensionBytes pp.PeerExtensionBits
138 // The actual Conn, used for closing, and setting socket options.
140 // The Reader and Writer for this Conn, with hooks installed for stats,
141 // limiting, deadlines etc.
145 writeBuffer *bytes.Buffer
146 uploadTimer *time.Timer
152 func (cn *PeerConn) connStatusString() string {
153 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
156 func (cn *Peer) updateExpectingChunks() {
157 if cn.expectingChunks() {
158 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
159 cn.lastStartedExpectingToReceiveChunks = time.Now()
162 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
163 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
164 cn.lastStartedExpectingToReceiveChunks = time.Time{}
169 func (cn *Peer) expectingChunks() bool {
170 return len(cn.requests) != 0 && !cn.peerChoking
173 // Returns true if the connection is over IPv6.
174 func (cn *PeerConn) ipv6() bool {
179 return len(ip) == net.IPv6len
182 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
183 // specification for this.
184 func (cn *PeerConn) isPreferredDirection() bool {
185 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
188 // Returns whether the left connection should be preferred over the right one,
189 // considering only their networking properties. If ok is false, we can't
191 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
193 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
194 ml.NextBool(!l.utp(), !r.utp())
195 ml.NextBool(l.ipv6(), r.ipv6())
199 func (cn *Peer) cumInterest() time.Duration {
200 ret := cn.priorInterest
202 ret += time.Since(cn.lastBecameInterested)
207 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
208 if cn.peerSentHaveAll {
211 if !cn.t.haveInfo() {
214 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
217 func (cn *PeerConn) locker() *lockWithDeferreds {
218 return cn.t.cl.locker()
221 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
222 _, ok := cn.PeerExtensionIDs[ext]
226 // The best guess at number of pieces in the torrent for this peer.
227 func (cn *Peer) bestPeerNumPieces() pieceIndex {
229 return cn.t.numPieces()
231 return cn.peerMinPieces
234 func (cn *Peer) completedString() string {
235 have := pieceIndex(cn._peerPieces.Len())
236 if cn.peerSentHaveAll {
237 have = cn.bestPeerNumPieces()
239 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
242 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
243 cn.setNumPieces(info.NumPieces())
246 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
247 // receiving badly sized BITFIELD, or invalid HAVE messages.
248 func (cn *PeerConn) setNumPieces(num pieceIndex) {
249 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
250 cn.peerPiecesChanged()
253 func eventAgeString(t time.Time) string {
257 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
260 func (cn *PeerConn) connectionFlags() (ret string) {
262 ret += string([]byte{b})
264 if cn.cryptoMethod == mse.CryptoMethodRC4 {
266 } else if cn.headerEncrypted {
269 ret += string(cn.Discovery)
276 func (cn *PeerConn) utp() bool {
277 return parseNetworkString(cn.Network).Udp
280 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
281 func (cn *Peer) statusFlags() (ret string) {
283 ret += string([]byte{b})
292 ret += cn.connectionFlags()
294 if cn.peerInterested {
303 // func (cn *connection) String() string {
304 // var buf bytes.Buffer
305 // cn.writeStatus(&buf, nil)
306 // return buf.String()
309 func (cn *Peer) downloadRate() float64 {
310 return float64(cn._stats.BytesReadUsefulData.Int64()) / cn.cumInterest().Seconds()
313 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
314 // \t isn't preserved in <pre> blocks?
315 fmt.Fprintln(w, cn.connStatusString())
316 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
317 eventAgeString(cn.lastMessageReceived),
318 eventAgeString(cn.completedHandshake),
319 eventAgeString(cn.lastHelpful()),
321 cn.totalExpectingTime(),
324 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
325 cn.completedString(),
326 len(cn.peerTouchedPieces),
327 &cn._stats.ChunksReadUseful,
328 &cn._stats.ChunksRead,
329 &cn._stats.ChunksWritten,
331 cn.numLocalRequests(),
332 cn.nominalMaxRequests(),
333 len(cn.peerRequests),
335 cn.downloadRate()/(1<<10),
337 fmt.Fprintf(w, " next pieces: %v%s\n",
338 iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
340 if cn == t.fastestPeer {
349 func (cn *Peer) close() {
350 if !cn.closed.Set() {
353 cn.discardPieceInclination()
354 cn._pieceRequestOrder.Clear()
355 cn.peerImpl.onClose()
356 for _, f := range cn.callbacks.PeerClosed {
361 func (cn *PeerConn) onClose() {
362 if cn.pex.IsEnabled() {
369 if cb := cn.callbacks.PeerConnClosed; cb != nil {
374 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
375 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
378 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
379 // https://github.com/pion/datachannel/issues/59 is fixed.
380 const writeBufferHighWaterLen = 1 << 15
382 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Posting is
383 // done asynchronously, so it may be that we're not able to honour backpressure from this method. It
384 // might be possible to merge this with PeerConn.write down the track? They seem to be very similar.
385 func (cn *PeerConn) post(msg pp.Message) bool {
386 torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
387 // We don't need to track bytes here because a connection.w Writer wrapper takes care of that
388 // (although there's some delay between us recording the message, and the connection writer
389 // flushing it out.).
390 cn.writeBuffer.Write(msg.MustMarshalBinary())
391 // Last I checked only Piece messages affect stats, and we don't post those.
394 return cn.writeBuffer.Len() < writeBufferHighWaterLen
397 // Returns true if there's room to write more.
398 func (cn *PeerConn) write(msg pp.Message) bool {
400 cn.writeBuffer.Write(msg.MustMarshalBinary())
401 torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
402 return cn.writeBuffer.Len() < writeBufferHighWaterLen
405 func (cn *PeerConn) requestMetadataPiece(index int) {
406 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
410 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
413 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
417 ExtendedPayload: func() []byte {
418 b, err := bencode.Marshal(map[string]int{
419 "msg_type": pp.RequestMetadataExtensionMsgType,
428 for index >= len(cn.metadataRequests) {
429 cn.metadataRequests = append(cn.metadataRequests, false)
431 cn.metadataRequests[index] = true
434 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
435 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
438 // The actual value to use as the maximum outbound requests.
439 func (cn *Peer) nominalMaxRequests() (ret int) {
442 int64(cn.PeerMaxRequests),
443 int64(cn.t.requestStrategy.nominalMaxRequests(cn.requestStrategyConnection())),
447 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
448 ret = cn.cumulativeExpectedToReceiveChunks
449 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
450 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
456 func (cn *PeerConn) onPeerSentCancel(r Request) {
457 if _, ok := cn.peerRequests[r]; !ok {
458 torrent.Add("unexpected cancels received", 1)
461 if cn.fastEnabled() {
464 delete(cn.peerRequests, r)
468 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
473 more = msg(pp.Message{
476 if cn.fastEnabled() {
477 for r := range cn.peerRequests {
478 // TODO: Don't reject pieces in allowed fast set.
482 cn.peerRequests = nil
487 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
492 return msg(pp.Message{
497 func (cn *Peer) setInterested(interested bool) bool {
498 if cn.interested == interested {
501 cn.interested = interested
503 cn.lastBecameInterested = time.Now()
504 } else if !cn.lastBecameInterested.IsZero() {
505 cn.priorInterest += time.Since(cn.lastBecameInterested)
507 cn.updateExpectingChunks()
508 // log.Printf("%p: setting interest: %v", cn, interested)
509 return cn.writeInterested(interested)
512 func (pc *PeerConn) writeInterested(interested bool) bool {
513 return pc.write(pp.Message{
514 Type: func() pp.MessageType {
518 return pp.NotInterested
524 // The function takes a message to be sent, and returns true if more messages
526 type messageWriter func(pp.Message) bool
528 func (cn *Peer) request(r Request) bool {
529 if _, ok := cn.requests[r]; ok {
530 panic("chunk already requested")
532 if !cn.peerHasPiece(pieceIndex(r.Index)) {
533 panic("requesting piece peer doesn't have")
535 if !cn.t.peerIsActive(cn) {
536 panic("requesting but not in active conns")
538 if cn.closed.IsSet() {
539 panic("requesting when connection is closed")
542 if cn.peerAllowedFast.Get(int(r.Index)) {
543 torrent.Add("allowed fast requests sent", 1)
545 panic("requesting while choking and not allowed fast")
548 if cn.t.hashingPiece(pieceIndex(r.Index)) {
549 panic("piece is being hashed")
551 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
552 panic("piece is queued for hash")
554 if cn.requests == nil {
555 cn.requests = make(map[Request]struct{})
557 cn.requests[r] = struct{}{}
558 if cn.validReceiveChunks == nil {
559 cn.validReceiveChunks = make(map[Request]int)
561 cn.validReceiveChunks[r]++
562 cn.t.pendingRequests[r]++
563 cn.t.requestStrategy.hooks().sentRequest(r)
564 cn.updateExpectingChunks()
565 for _, f := range cn.callbacks.SentRequest {
566 f(PeerRequestEvent{cn, r})
568 return cn.peerImpl.request(r)
571 func (me *PeerConn) request(r Request) bool {
572 return me.write(pp.Message{
580 func (me *PeerConn) cancel(r Request) bool {
581 return me.write(makeCancelMessage(r))
584 func (cn *Peer) doRequestState() bool {
585 if !cn.t.networkingEnabled || cn.t.dataDownloadDisallowed {
586 if !cn.setInterested(false) {
589 if len(cn.requests) != 0 {
590 for r := range cn.requests {
592 // log.Printf("%p: cancelling request: %v", cn, r)
593 if !cn.peerImpl.cancel(r) {
598 } else if len(cn.requests) <= cn.requestsLowWater {
599 filledBuffer := false
600 cn.iterPendingPieces(func(pieceIndex pieceIndex) bool {
601 cn.iterPendingRequests(pieceIndex, func(r Request) bool {
602 if !cn.setInterested(true) {
606 if len(cn.requests) >= cn.nominalMaxRequests() {
609 // Choking is looked at here because our interest is dependent
610 // on whether we'd make requests in its absence.
612 if !cn.peerAllowedFast.Get(bitmap.BitIndex(r.Index)) {
616 if _, ok := cn.requests[r]; ok {
619 filledBuffer = !cn.request(r)
625 // If we didn't completely top up the requests, we shouldn't mark
626 // the low water, since we'll want to top up the requests as soon
627 // as we have more write buffer space.
630 cn.requestsLowWater = len(cn.requests) / 2
631 if len(cn.requests) == 0 {
632 return cn.setInterested(false)
638 func (cn *PeerConn) fillWriteBuffer() {
639 if !cn.doRequestState() {
642 if cn.pex.IsEnabled() {
643 if flow := cn.pex.Share(cn.write); !flow {
650 // Routine that writes to the peer. Some of what to write is buffered by
651 // activity elsewhere in the Client, and some is determined locally when the
652 // connection is writable.
653 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
655 lastWrite time.Time = time.Now()
656 keepAliveTimer *time.Timer
658 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
660 defer cn.locker().Unlock()
661 if time.Since(lastWrite) >= keepAliveTimeout {
664 keepAliveTimer.Reset(keepAliveTimeout)
667 defer cn.locker().Unlock()
669 defer keepAliveTimer.Stop()
670 frontBuf := new(bytes.Buffer)
672 if cn.closed.IsSet() {
675 if cn.writeBuffer.Len() == 0 {
678 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.useful() {
679 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
680 postedKeepalives.Add(1)
682 if cn.writeBuffer.Len() == 0 {
683 // TODO: Minimize wakeups....
688 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
690 n, err := cn.w.Write(frontBuf.Bytes())
693 lastWrite = time.Now()
694 keepAliveTimer.Reset(keepAliveTimeout)
697 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
700 if n != frontBuf.Len() {
707 func (cn *PeerConn) have(piece pieceIndex) {
708 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
713 Index: pp.Integer(piece),
715 cn.sentHaves.Add(bitmap.BitIndex(piece))
718 func (cn *PeerConn) postBitfield() {
719 if cn.sentHaves.Len() != 0 {
720 panic("bitfield must be first have-related message sent")
722 if !cn.t.haveAnyPieces() {
727 Bitfield: cn.t.bitfield(),
729 cn.sentHaves = cn.t._completedPieces.Copy()
732 func (cn *PeerConn) updateRequests() {
733 // log.Print("update requests")
737 // Emits the indices in the Bitmaps bms in order, never repeating any index.
738 // skip is mutated during execution, and its initial values will never be
740 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
741 return func(cb iter.Callback) {
742 for _, bm := range bms {
744 func(i interface{}) bool {
748 bitmap.Sub(bm, *skip).Iter,
756 func iterUnbiasedPieceRequestOrder(cn requestStrategyConnection, f func(piece pieceIndex) bool) bool {
757 now, readahead := cn.torrent().readerPiecePriorities()
758 skip := bitmap.Flip(cn.peerPieces(), 0, cn.torrent().numPieces())
759 skip.Union(cn.torrent().ignorePieces())
760 // Return an iterator over the different priority classes, minus the skip pieces.
762 func(_piece interface{}) bool {
763 return f(pieceIndex(_piece.(bitmap.BitIndex)))
765 iterBitmapsDistinct(&skip, now, readahead),
766 // We have to iterate _pendingPieces separately because it isn't a Bitmap.
767 func(cb iter.Callback) {
768 cn.torrent().pendingPieces().IterTyped(func(piece int) bool {
769 if skip.Contains(piece) {
780 // The connection should download highest priority pieces first, without any inclination toward
781 // avoiding wastage. Generally we might do this if there's a single connection, or this is the
782 // fastest connection, and we have active readers that signal an ordering preference. It's
783 // conceivable that the best connection should do this, since it's least likely to waste our time if
784 // assigned to the highest priority pieces, and assigning more than one this role would cause
785 // significant wasted bandwidth.
786 func (cn *Peer) shouldRequestWithoutBias() bool {
787 return cn.t.requestStrategy.shouldRequestWithoutBias(cn.requestStrategyConnection())
790 func (cn *Peer) iterPendingPieces(f func(pieceIndex) bool) bool {
791 if !cn.t.haveInfo() {
794 return cn.t.requestStrategy.iterPendingPieces(cn, f)
796 func (cn *Peer) iterPendingPiecesUntyped(f iter.Callback) {
797 cn.iterPendingPieces(func(i pieceIndex) bool { return f(i) })
800 func (cn *Peer) iterPendingRequests(piece pieceIndex, f func(Request) bool) bool {
801 return cn.t.requestStrategy.iterUndirtiedChunks(
802 cn.t.piece(piece).requestStrategyPiece(),
803 func(cs ChunkSpec) bool {
804 return f(Request{pp.Integer(piece), cs})
809 // check callers updaterequests
810 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
811 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
814 // This is distinct from Torrent piece priority, which is the user's
815 // preference. Connection piece priority is specific to a connection and is
816 // used to pseudorandomly avoid connections always requesting the same pieces
817 // and thus wasting effort.
818 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
819 tpp := cn.t.piecePriority(piece)
820 if !cn.peerHasPiece(piece) {
821 tpp = PiecePriorityNone
823 if tpp == PiecePriorityNone {
824 return cn.stopRequestingPiece(piece)
826 prio := cn.getPieceInclination()[piece]
827 prio = cn.t.requestStrategy.piecePriority(cn, piece, tpp, prio)
828 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio) || cn.shouldRequestWithoutBias()
831 func (cn *Peer) getPieceInclination() []int {
832 if cn.pieceInclination == nil {
833 cn.pieceInclination = cn.t.getConnPieceInclination()
835 return cn.pieceInclination
838 func (cn *Peer) discardPieceInclination() {
839 if cn.pieceInclination == nil {
842 cn.t.putPieceInclination(cn.pieceInclination)
843 cn.pieceInclination = nil
846 func (cn *PeerConn) peerPiecesChanged() {
848 prioritiesChanged := false
849 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
850 if cn.updatePiecePriority(i) {
851 prioritiesChanged = true
854 if prioritiesChanged {
858 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
861 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
862 if newMin > cn.peerMinPieces {
863 cn.peerMinPieces = newMin
867 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
868 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
869 return errors.New("invalid piece")
871 if cn.peerHasPiece(piece) {
874 cn.raisePeerMinPieces(piece + 1)
875 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
876 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
877 if cn.updatePiecePriority(piece) {
883 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
884 cn.peerSentHaveAll = false
886 panic("expected bitfield length divisible by 8")
888 // We know that the last byte means that at most the last 7 bits are
890 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
891 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
892 // Ignore known excess pieces.
893 bf = bf[:cn.t.numPieces()]
895 for i, have := range bf {
897 cn.raisePeerMinPieces(pieceIndex(i) + 1)
899 cn._peerPieces.Set(i, have)
901 cn.peerPiecesChanged()
905 func (cn *PeerConn) onPeerSentHaveAll() error {
906 cn.peerSentHaveAll = true
907 cn._peerPieces.Clear()
908 cn.peerPiecesChanged()
912 func (cn *PeerConn) peerSentHaveNone() error {
913 cn._peerPieces.Clear()
914 cn.peerSentHaveAll = false
915 cn.peerPiecesChanged()
919 func (c *PeerConn) requestPendingMetadata() {
923 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
924 // Peer doesn't support this.
927 // Request metadata pieces that we don't have in a random order.
929 for index := 0; index < c.t.metadataPieceCount(); index++ {
930 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
931 pending = append(pending, index)
934 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
935 for _, i := range pending {
936 c.requestMetadataPiece(i)
940 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
941 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
942 if msg.Type == pp.Extended {
943 for name, id := range cn.PeerExtensionIDs {
944 if id != msg.ExtendedID {
947 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
950 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
953 func (cn *PeerConn) readMsg(msg *pp.Message) {
954 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
957 // After handshake, we know what Torrent and Client stats to include for a
959 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
965 // All ConnStats that include this connection. Some objects are not known
966 // until the handshake is complete, after which it's expected to reconcile the
968 func (cn *Peer) allStats(f func(*ConnStats)) {
970 if cn.reconciledHandshakeStats {
971 cn.postHandshakeStats(f)
975 func (cn *PeerConn) wroteBytes(n int64) {
976 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
979 func (cn *PeerConn) readBytes(n int64) {
980 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
983 // Returns whether the connection could be useful to us. We're seeding and
984 // they want data, we don't have metainfo and they can provide it, etc.
985 func (c *Peer) useful() bool {
987 if c.closed.IsSet() {
991 return c.supportsExtension("ut_metadata")
993 if t.seeding() && c.peerInterested {
996 if c.peerHasWantedPieces() {
1002 func (c *Peer) lastHelpful() (ret time.Time) {
1003 ret = c.lastUsefulChunkReceived
1004 if c.t.seeding() && c.lastChunkSent.After(ret) {
1005 ret = c.lastChunkSent
1010 func (c *PeerConn) fastEnabled() bool {
1011 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
1014 func (c *PeerConn) reject(r Request) {
1015 if !c.fastEnabled() {
1016 panic("fast not enabled")
1018 c.post(r.ToMsg(pp.Reject))
1019 delete(c.peerRequests, r)
1022 func (c *PeerConn) onReadRequest(r Request) error {
1023 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
1024 if _, ok := c.peerRequests[r]; ok {
1025 torrent.Add("duplicate requests received", 1)
1029 torrent.Add("requests received while choking", 1)
1030 if c.fastEnabled() {
1031 torrent.Add("requests rejected while choking", 1)
1036 if len(c.peerRequests) >= maxRequests {
1037 torrent.Add("requests received while queue full", 1)
1038 if c.fastEnabled() {
1041 // BEP 6 says we may close here if we choose.
1044 if !c.t.havePiece(pieceIndex(r.Index)) {
1045 // This isn't necessarily them screwing up. We can drop pieces
1046 // from our storage, and can't communicate this to peers
1047 // except by reconnecting.
1048 requestsReceivedForMissingPieces.Add(1)
1049 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
1051 // Check this after we know we have the piece, so that the piece length will be known.
1052 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
1053 torrent.Add("bad requests received", 1)
1054 return errors.New("bad Request")
1056 if c.peerRequests == nil {
1057 c.peerRequests = make(map[Request]*peerRequestState, maxRequests)
1059 value := &peerRequestState{}
1060 c.peerRequests[r] = value
1061 go c.peerRequestDataReader(r, value)
1066 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
1067 b, err := readPeerRequestData(r, c)
1069 defer c.locker().Unlock()
1071 c.peerRequestDataReadFailed(err, r)
1074 panic("data must be non-nil to trigger send")
1081 // If this is maintained correctly, we might be able to support optional synchronous reading for
1082 // chunk sending, the way it used to work.
1083 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
1084 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
1085 i := pieceIndex(r.Index)
1086 if c.t.pieceComplete(i) {
1087 // There used to be more code here that just duplicated the following break. Piece
1088 // completions are currently cached, so I'm not sure how helpful this update is, except to
1089 // pull any completion changes pushed to the storage backend in failed reads that got us
1091 c.t.updatePieceCompletion(i)
1093 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
1094 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
1095 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1096 // next connect. TODO: Support rejecting here too.
1098 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1103 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1104 b := make([]byte, r.Length)
1105 p := c.t.info.Piece(int(r.Index))
1106 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1113 panic("expected error")
1119 func runSafeExtraneous(f func()) {
1127 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1128 // exit. Returning will end the connection.
1129 func (c *PeerConn) mainReadLoop() (err error) {
1132 torrent.Add("connection.mainReadLoop returned with error", 1)
1134 torrent.Add("connection.mainReadLoop returned with no error", 1)
1140 decoder := pp.Decoder{
1141 R: bufio.NewReaderSize(c.r, 1<<17),
1142 MaxLength: 256 * 1024,
1150 err = decoder.Decode(&msg)
1152 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1155 if t.closed.IsSet() || c.closed.IsSet() {
1162 c.lastMessageReceived = time.Now()
1164 receivedKeepalives.Add(1)
1167 messageTypesReceived.Add(msg.Type.String(), 1)
1168 if msg.Type.FastExtension() && !c.fastEnabled() {
1169 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1170 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1174 c.peerChoking = true
1175 if !c.fastEnabled() {
1176 c.deleteAllRequests()
1178 // We can then reset our interest.
1180 c.updateExpectingChunks()
1182 c.peerChoking = false
1184 c.updateExpectingChunks()
1186 c.peerInterested = true
1188 case pp.NotInterested:
1189 c.peerInterested = false
1190 // We don't clear their requests since it isn't clear in the spec.
1191 // We'll probably choke them for this, which will clear them if
1192 // appropriate, and is clearly specified.
1194 err = c.peerSentHave(pieceIndex(msg.Index))
1196 err = c.peerSentBitfield(msg.Bitfield)
1198 r := newRequestFromMessage(&msg)
1199 err = c.onReadRequest(r)
1201 err = c.receiveChunk(&msg)
1202 if len(msg.Piece) == int(t.chunkSize) {
1203 t.chunkPool.Put(&msg.Piece)
1206 err = fmt.Errorf("receiving chunk: %s", err)
1209 req := newRequestFromMessage(&msg)
1210 c.onPeerSentCancel(req)
1212 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1216 pingAddr := net.UDPAddr{
1221 pingAddr.Port = int(msg.Port)
1223 cl.eachDhtServer(func(s DhtServer) {
1224 go s.Ping(&pingAddr)
1227 torrent.Add("suggests received", 1)
1228 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1231 err = c.onPeerSentHaveAll()
1233 err = c.peerSentHaveNone()
1235 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1236 case pp.AllowedFast:
1237 torrent.Add("allowed fasts received", 1)
1238 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1239 c.peerAllowedFast.Add(int(msg.Index))
1242 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1244 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1252 func (c *Peer) remoteRejectedRequest(r Request) {
1253 if c.deleteRequest(r) {
1254 c.decExpectedChunkReceive(r)
1258 func (c *Peer) decExpectedChunkReceive(r Request) {
1259 count := c.validReceiveChunks[r]
1261 delete(c.validReceiveChunks, r)
1262 } else if count > 1 {
1263 c.validReceiveChunks[r] = count - 1
1269 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1271 // TODO: Should we still do this?
1273 // These clients use their own extension IDs for outgoing message
1274 // types, which is incorrect.
1275 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1283 case pp.HandshakeExtendedID:
1284 var d pp.ExtendedHandshakeMessage
1285 if err := bencode.Unmarshal(payload, &d); err != nil {
1286 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1287 return errors.Wrap(err, "unmarshalling extended handshake payload")
1289 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1292 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1294 c.PeerMaxRequests = d.Reqq
1296 c.PeerClientName = d.V
1297 if c.PeerExtensionIDs == nil {
1298 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1300 c.PeerListenPort = d.Port
1301 c.PeerPrefersEncryption = d.Encryption
1302 for name, id := range d.M {
1303 if _, ok := c.PeerExtensionIDs[name]; !ok {
1304 torrent.Add(fmt.Sprintf("peers supporting extension %q", name), 1)
1306 c.PeerExtensionIDs[name] = id
1308 if d.MetadataSize != 0 {
1309 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1310 return errors.Wrapf(err, "setting metadata size to %d", d.MetadataSize)
1313 c.requestPendingMetadata()
1314 if !t.cl.config.DisablePEX {
1315 t.pex.Add(c) // we learnt enough now
1319 case metadataExtendedId:
1320 err := cl.gotMetadataExtensionMsg(payload, t, c)
1322 return fmt.Errorf("handling metadata extension message: %w", err)
1326 if !c.pex.IsEnabled() {
1327 return nil // or hang-up maybe?
1329 return c.pex.Recv(payload)
1331 return fmt.Errorf("unexpected extended message ID: %v", id)
1335 // Set both the Reader and Writer for the connection from a single ReadWriter.
1336 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1341 // Returns the Reader and Writer as a combined ReadWriter.
1342 func (cn *PeerConn) rw() io.ReadWriter {
1349 // Handle a received chunk from a peer.
1350 func (c *Peer) receiveChunk(msg *pp.Message) error {
1353 torrent.Add("chunks received", 1)
1355 req := newRequestFromMessage(msg)
1358 torrent.Add("chunks received while choking", 1)
1361 if c.validReceiveChunks[req] <= 0 {
1362 torrent.Add("chunks received unexpected", 1)
1363 return errors.New("received unexpected chunk")
1365 c.decExpectedChunkReceive(req)
1367 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1368 torrent.Add("chunks received due to allowed fast", 1)
1371 // TODO: This needs to happen immediately, to prevent cancels occurring asynchronously when have
1372 // actually already received the piece, while we have the Client unlocked to write the data out.
1374 if _, ok := c.requests[req]; ok {
1375 for _, f := range c.callbacks.ReceivedRequested {
1376 f(PeerMessageEvent{c, msg})
1379 // Request has been satisfied.
1380 if c.deleteRequest(req) {
1381 if c.expectingChunks() {
1382 c._chunksReceivedWhileExpecting++
1385 torrent.Add("chunks received unwanted", 1)
1389 // Do we actually want this chunk?
1390 if t.haveChunk(req) {
1391 torrent.Add("chunks received wasted", 1)
1392 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1396 piece := &t.pieces[req.Index]
1398 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1399 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1400 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1401 f(ReceivedUsefulDataEvent{c, msg})
1403 c.lastUsefulChunkReceived = time.Now()
1404 // if t.fastestPeer != c {
1405 // log.Printf("setting fastest connection %p", c)
1409 // Need to record that it hasn't been written yet, before we attempt to do
1410 // anything with it.
1411 piece.incrementPendingWrites()
1412 // Record that we have the chunk, so we aren't trying to download it while
1413 // waiting for it to be written to storage.
1414 piece.unpendChunkIndex(chunkIndex(req.ChunkSpec, t.chunkSize))
1416 // Cancel pending requests for this chunk from *other* peers.
1417 t.iterPeers(func(p *Peer) {
1424 err := func() error {
1427 concurrentChunkWrites.Add(1)
1428 defer concurrentChunkWrites.Add(-1)
1429 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1430 // number of connections. We write inline with receiving the chunk (with this lock dance),
1431 // because we want to handle errors synchronously and I haven't thought of a nice way to
1432 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1434 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1437 piece.decrementPendingWrites()
1440 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1442 //t.updatePieceCompletion(pieceIndex(msg.Index))
1443 t.onWriteChunkErr(err)
1447 c.onDirtiedPiece(pieceIndex(req.Index))
1449 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1450 if t.pieceAllDirty(pieceIndex(req.Index)) && piece.pendingWrites == 0 {
1451 t.queuePieceCheck(pieceIndex(req.Index))
1452 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1453 // chunk status (such as the haveChunk call above) to have to check all the various other
1454 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1455 // that chunk pieces are pended at an appropriate time later however.
1458 cl.event.Broadcast()
1459 // We do this because we've written a chunk, and may change PieceState.Partial.
1460 t.publishPieceChange(pieceIndex(req.Index))
1465 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1466 if c.peerTouchedPieces == nil {
1467 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1469 c.peerTouchedPieces[piece] = struct{}{}
1470 ds := &c.t.pieces[piece].dirtiers
1472 *ds = make(map[*Peer]struct{})
1474 (*ds)[c] = struct{}{}
1477 func (c *PeerConn) uploadAllowed() bool {
1478 if c.t.cl.config.NoUpload {
1481 if c.t.dataUploadDisallowed {
1487 if !c.peerHasWantedPieces() {
1490 // Don't upload more than 100 KiB more than we download.
1491 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1497 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1498 if c.uploadTimer == nil {
1499 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1501 c.uploadTimer.Reset(delay)
1505 // Also handles choking and unchoking of the remote peer.
1506 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1507 // Breaking or completing this loop means we don't want to upload to the
1508 // peer anymore, and we choke them.
1510 for c.uploadAllowed() {
1511 // We want to upload to the peer.
1512 if !c.unchoke(msg) {
1515 for r, state := range c.peerRequests {
1516 if state.data == nil {
1519 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1521 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1523 delay := res.Delay()
1526 c.setRetryUploadTimer(delay)
1527 // Hard to say what to return here.
1530 more := c.sendChunk(r, msg, state)
1531 delete(c.peerRequests, r)
1542 func (cn *PeerConn) drop() {
1543 cn.t.dropConnection(cn)
1546 func (cn *Peer) netGoodPiecesDirtied() int64 {
1547 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1550 func (c *Peer) peerHasWantedPieces() bool {
1551 return !c._pieceRequestOrder.IsEmpty()
1554 func (c *Peer) numLocalRequests() int {
1555 return len(c.requests)
1558 func (c *Peer) deleteRequest(r Request) bool {
1559 if _, ok := c.requests[r]; !ok {
1562 delete(c.requests, r)
1563 for _, f := range c.callbacks.DeletedRequest {
1564 f(PeerRequestEvent{c, r})
1566 c.updateExpectingChunks()
1567 c.t.requestStrategy.hooks().deletedRequest(r)
1568 pr := c.t.pendingRequests
1577 // If a request fails, updating the requests for the current peer first may miss the opportunity
1578 // to try other peers for that request instead, depending on the request strategy. This might
1579 // only affect webseed peers though, since they synchronously issue new requests: PeerConns do
1580 // it in the writer routine.
1581 const updateCurrentConnRequestsFirst = false
1582 if updateCurrentConnRequestsFirst {
1585 // Give other conns a chance to pick up the request.
1586 c.t.iterPeers(func(_c *Peer) {
1587 // We previously checked that the peer wasn't interested to to only wake connections that
1588 // were unable to issue requests due to starvation by the request strategy. There could be
1589 // performance ramifications.
1590 if _c != c && c.peerHasPiece(pieceIndex(r.Index)) {
1594 if !updateCurrentConnRequestsFirst {
1600 func (c *Peer) deleteAllRequests() {
1601 for r := range c.requests {
1604 if len(c.requests) != 0 {
1605 panic(len(c.requests))
1607 // for c := range c.t.conns {
1612 // This is called when something has changed that should wake the writer, such as putting stuff into
1613 // the writeBuffer, or changing some state that the writer can act on.
1614 func (c *PeerConn) tickleWriter() {
1615 c.writerCond.Broadcast()
1618 func (c *Peer) postCancel(r Request) bool {
1619 if !c.deleteRequest(r) {
1622 c.peerImpl._postCancel(r)
1626 func (c *PeerConn) _postCancel(r Request) {
1627 c.post(makeCancelMessage(r))
1630 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1631 c.lastChunkSent = time.Now()
1632 return msg(pp.Message{
1640 func (c *PeerConn) setTorrent(t *Torrent) {
1642 panic("connection already associated with a torrent")
1645 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1646 t.reconcileHandshakeStats(c)
1649 func (c *Peer) peerPriority() (peerPriority, error) {
1650 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1653 func (c *Peer) remoteIp() net.IP {
1654 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1655 return net.ParseIP(host)
1658 func (c *Peer) remoteIpPort() IpPort {
1659 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1660 return IpPort{ipa.IP, uint16(ipa.Port)}
1663 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1664 f := pp.PexPeerFlags(0)
1665 if c.PeerPrefersEncryption {
1666 f |= pp.PexPrefersEncryption
1669 f |= pp.PexOutgoingConn
1672 f |= pp.PexSupportsUtp
1677 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1678 // advertised listen port.
1679 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1680 if !c.outgoing && c.PeerListenPort != 0 {
1681 switch addr := c.RemoteAddr.(type) {
1684 dialAddr.Port = c.PeerListenPort
1688 dialAddr.Port = c.PeerListenPort
1695 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1696 f := c.pexPeerFlags()
1697 addr := c.dialAddr()
1698 return pexEvent{t, addr, f}
1701 func (c *PeerConn) String() string {
1702 return fmt.Sprintf("connection %p", c)
1705 func (c *Peer) trust() connectionTrust {
1706 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1709 type connectionTrust struct {
1711 NetGoodPiecesDirted int64
1714 func (l connectionTrust) Less(r connectionTrust) bool {
1715 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1718 func (cn *Peer) requestStrategyConnection() requestStrategyConnection {
1722 func (cn *Peer) chunksReceivedWhileExpecting() int64 {
1723 return cn._chunksReceivedWhileExpecting
1726 func (cn *Peer) fastest() bool {
1727 return cn == cn.t.fastestPeer
1730 func (cn *Peer) peerMaxRequests() int {
1731 return cn.PeerMaxRequests
1734 // Returns the pieces the peer has claimed to have.
1735 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1737 defer cn.locker().RUnlock()
1738 return cn.peerPieces()
1741 func (cn *Peer) peerPieces() bitmap.Bitmap {
1742 ret := cn._peerPieces.Copy()
1743 if cn.peerSentHaveAll {
1744 ret.AddRange(0, cn.t.numPieces())
1749 func (cn *Peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1750 return &cn._pieceRequestOrder
1753 func (cn *Peer) stats() *ConnStats {
1757 func (cn *Peer) torrent() requestStrategyTorrent {
1758 return cn.t.requestStrategyTorrent()
1761 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1762 pc, ok := p.peerImpl.(*PeerConn)