16 "github.com/RoaringBitmap/roaring"
17 "github.com/anacrolix/log"
18 "github.com/anacrolix/missinggo/iter"
19 "github.com/anacrolix/missinggo/v2/bitmap"
20 "github.com/anacrolix/multiless"
22 "github.com/anacrolix/chansync"
23 "github.com/anacrolix/torrent/bencode"
24 "github.com/anacrolix/torrent/metainfo"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
27 request_strategy "github.com/anacrolix/torrent/request-strategy"
30 type PeerSource string
33 PeerSourceTracker = "Tr"
34 PeerSourceIncoming = "I"
35 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
36 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
38 // The peer was given directly, such as through a magnet link.
39 PeerSourceDirect = "M"
42 type peerRequestState struct {
46 type PeerRemoteAddr interface {
50 // Since we have to store all the requests in memory, we can't reasonably exceed what would be
51 // indexable with the memory space available.
54 requestState = request_strategy.PeerNextRequestState
58 // First to ensure 64-bit alignment for atomics. See #262.
68 RemoteAddr PeerRemoteAddr
69 // True if the connection is operating over MSE obfuscation.
71 cryptoMethod mse.CryptoMethod
74 closed chansync.SetOnce
75 // Set true after we've added our ConnStats generated during handshake to
76 // other ConnStat instances as determined when the *Torrent became known.
77 reconciledHandshakeStats bool
79 lastMessageReceived time.Time
80 completedHandshake time.Time
81 lastUsefulChunkReceived time.Time
82 lastChunkSent time.Time
84 // Stuff controlled by the local peer.
85 needRequestUpdate string
86 actualRequestState requestState
87 cancelledRequests roaring.Bitmap
88 lastBecameInterested time.Time
89 priorInterest time.Duration
91 lastStartedExpectingToReceiveChunks time.Time
92 cumulativeExpectedToReceiveChunks time.Duration
93 _chunksReceivedWhileExpecting int64
96 piecesReceivedSinceLastRequestUpdate maxRequests
97 maxPiecesReceivedBetweenRequestUpdates maxRequests
98 // Chunks that we might reasonably expect to receive from the peer. Due to
99 // latency, buffering, and implementation differences, we may receive
100 // chunks that are no longer in the set of requests actually want.
101 validReceiveChunks map[RequestIndex]int
102 // Indexed by metadata piece, set to true if posted and pending a
104 metadataRequests []bool
105 sentHaves bitmap.Bitmap
107 // Stuff controlled by the remote peer.
110 peerRequests map[Request]*peerRequestState
111 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
113 // The pieces the peer has claimed to have.
114 _peerPieces roaring.Bitmap
115 // The peer has everything. This can occur due to a special message, when
116 // we may not even know the number of pieces in the torrent yet.
118 // The highest possible number of pieces the torrent could have based on
119 // communication with the peer. Generally only useful until we have the
121 peerMinPieces pieceIndex
122 // Pieces we've accepted chunks for from the peer.
123 peerTouchedPieces map[pieceIndex]struct{}
124 peerAllowedFast roaring.Bitmap
126 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
127 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
128 PeerClientName string
133 // Maintains the state of a BitTorrent-protocol based connection with a peer.
134 type PeerConn struct {
137 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
138 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
143 PeerExtensionBytes pp.PeerExtensionBits
145 // The actual Conn, used for closing, and setting socket options.
147 // The Reader and Writer for this Conn, with hooks installed for stats,
148 // limiting, deadlines etc.
152 messageWriter peerConnMsgWriter
154 uploadTimer *time.Timer
158 func (cn *PeerConn) connStatusString() string {
159 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
162 func (cn *Peer) updateExpectingChunks() {
163 if cn.expectingChunks() {
164 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
165 cn.lastStartedExpectingToReceiveChunks = time.Now()
168 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
169 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
170 cn.lastStartedExpectingToReceiveChunks = time.Time{}
175 func (cn *Peer) expectingChunks() bool {
176 if cn.actualRequestState.Requests.IsEmpty() {
179 if !cn.actualRequestState.Interested {
185 haveAllowedFastRequests := false
186 cn.peerAllowedFast.Iterate(func(i uint32) bool {
187 haveAllowedFastRequests = roaringBitmapRangeCardinality(
188 &cn.actualRequestState.Requests,
189 cn.t.pieceRequestIndexOffset(pieceIndex(i)),
190 cn.t.pieceRequestIndexOffset(pieceIndex(i+1)),
192 return !haveAllowedFastRequests
194 return haveAllowedFastRequests
197 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
198 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
201 // Returns true if the connection is over IPv6.
202 func (cn *PeerConn) ipv6() bool {
207 return len(ip) == net.IPv6len
210 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
211 // specification for this.
212 func (cn *PeerConn) isPreferredDirection() bool {
213 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
216 // Returns whether the left connection should be preferred over the right one,
217 // considering only their networking properties. If ok is false, we can't
219 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
221 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
222 ml.NextBool(!l.utp(), !r.utp())
223 ml.NextBool(l.ipv6(), r.ipv6())
227 func (cn *Peer) cumInterest() time.Duration {
228 ret := cn.priorInterest
229 if cn.actualRequestState.Interested {
230 ret += time.Since(cn.lastBecameInterested)
235 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
236 if cn.peerSentHaveAll {
239 if !cn.t.haveInfo() {
242 return roaring.Flip(&cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
245 func (cn *PeerConn) locker() *lockWithDeferreds {
246 return cn.t.cl.locker()
249 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
250 _, ok := cn.PeerExtensionIDs[ext]
254 // The best guess at number of pieces in the torrent for this peer.
255 func (cn *Peer) bestPeerNumPieces() pieceIndex {
257 return cn.t.numPieces()
259 return cn.peerMinPieces
262 func (cn *Peer) completedString() string {
263 have := pieceIndex(cn._peerPieces.GetCardinality())
264 if cn.peerSentHaveAll {
265 have = cn.bestPeerNumPieces()
267 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
270 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
271 cn.setNumPieces(info.NumPieces())
274 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
275 // receiving badly sized BITFIELD, or invalid HAVE messages.
276 func (cn *PeerConn) setNumPieces(num pieceIndex) {
277 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
278 cn.peerPiecesChanged()
281 func eventAgeString(t time.Time) string {
285 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
288 func (cn *PeerConn) connectionFlags() (ret string) {
290 ret += string([]byte{b})
292 if cn.cryptoMethod == mse.CryptoMethodRC4 {
294 } else if cn.headerEncrypted {
297 ret += string(cn.Discovery)
304 func (cn *PeerConn) utp() bool {
305 return parseNetworkString(cn.Network).Udp
308 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
309 func (cn *Peer) statusFlags() (ret string) {
311 ret += string([]byte{b})
313 if cn.actualRequestState.Interested {
320 ret += cn.connectionFlags()
322 if cn.peerInterested {
331 func (cn *Peer) downloadRate() float64 {
332 num := cn._stats.BytesReadUsefulData.Int64()
336 return float64(num) / cn.totalExpectingTime().Seconds()
339 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
340 ret = make(map[pieceIndex]int)
341 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
342 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
348 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
349 // \t isn't preserved in <pre> blocks?
350 if cn.closed.IsSet() {
351 fmt.Fprint(w, "CLOSED: ")
353 fmt.Fprintln(w, cn.connStatusString())
354 prio, err := cn.peerPriority()
355 prioStr := fmt.Sprintf("%08x", prio)
357 prioStr += ": " + err.Error()
359 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
360 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
361 eventAgeString(cn.lastMessageReceived),
362 eventAgeString(cn.completedHandshake),
363 eventAgeString(cn.lastHelpful()),
365 cn.totalExpectingTime(),
368 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
369 cn.completedString(),
370 len(cn.peerTouchedPieces),
371 &cn._stats.ChunksReadUseful,
372 &cn._stats.ChunksRead,
373 &cn._stats.ChunksWritten,
374 cn.actualRequestState.Requests.GetCardinality(),
375 cn.nominalMaxRequests(),
377 len(cn.peerRequests),
380 cn.downloadRate()/(1<<10),
382 fmt.Fprintf(w, " requested pieces:")
383 type pieceNumRequestsType struct {
387 var pieceNumRequests []pieceNumRequestsType
388 for piece, count := range cn.numRequestsByPiece() {
389 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
391 sort.Slice(pieceNumRequests, func(i, j int) bool {
392 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
394 for _, elem := range pieceNumRequests {
395 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
400 func (p *Peer) close() {
406 p.t.decPeerPieceAvailability(p)
408 for _, f := range p.callbacks.PeerClosed {
413 func (cn *PeerConn) onClose() {
414 if cn.pex.IsEnabled() {
421 if cb := cn.callbacks.PeerConnClosed; cb != nil {
426 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
427 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
430 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
431 // https://github.com/pion/datachannel/issues/59 is fixed.
432 const writeBufferHighWaterLen = 1 << 15
434 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
435 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
436 func (cn *PeerConn) write(msg pp.Message) bool {
437 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
438 // We don't need to track bytes here because the connection's Writer has that behaviour injected
439 // (although there's some delay between us buffering the message, and the connection writer
440 // flushing it out.).
441 notFull := cn.messageWriter.write(msg)
442 // Last I checked only Piece messages affect stats, and we don't write those.
448 func (cn *PeerConn) requestMetadataPiece(index int) {
449 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
450 if eID == pp.ExtensionDeleteNumber {
453 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
456 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
457 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
458 for index >= len(cn.metadataRequests) {
459 cn.metadataRequests = append(cn.metadataRequests, false)
461 cn.metadataRequests[index] = true
464 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
465 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
468 // The actual value to use as the maximum outbound requests.
469 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
470 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 2048))
473 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
474 ret = cn.cumulativeExpectedToReceiveChunks
475 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
476 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
482 func (cn *PeerConn) onPeerSentCancel(r Request) {
483 if _, ok := cn.peerRequests[r]; !ok {
484 torrent.Add("unexpected cancels received", 1)
487 if cn.fastEnabled() {
490 delete(cn.peerRequests, r)
494 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
499 more = msg(pp.Message{
502 if cn.fastEnabled() {
503 for r := range cn.peerRequests {
504 // TODO: Don't reject pieces in allowed fast set.
508 cn.peerRequests = nil
513 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
518 return msg(pp.Message{
523 func (cn *Peer) setInterested(interested bool) bool {
524 if cn.actualRequestState.Interested == interested {
527 cn.actualRequestState.Interested = interested
529 cn.lastBecameInterested = time.Now()
530 } else if !cn.lastBecameInterested.IsZero() {
531 cn.priorInterest += time.Since(cn.lastBecameInterested)
533 cn.updateExpectingChunks()
534 // log.Printf("%p: setting interest: %v", cn, interested)
535 return cn.writeInterested(interested)
538 func (pc *PeerConn) writeInterested(interested bool) bool {
539 return pc.write(pp.Message{
540 Type: func() pp.MessageType {
544 return pp.NotInterested
550 // The function takes a message to be sent, and returns true if more messages
552 type messageWriter func(pp.Message) bool
554 func (cn *Peer) shouldRequest(r RequestIndex) error {
555 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
556 if !cn.peerHasPiece(pi) {
557 return errors.New("requesting piece peer doesn't have")
559 if !cn.t.peerIsActive(cn) {
560 panic("requesting but not in active conns")
562 if cn.closed.IsSet() {
563 panic("requesting when connection is closed")
565 if cn.t.hashingPiece(pi) {
566 panic("piece is being hashed")
568 if cn.t.pieceQueuedForHash(pi) {
569 panic("piece is queued for hash")
571 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
572 panic("peer choking and piece not allowed fast")
577 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
578 if err := cn.shouldRequest(r); err != nil {
581 if cn.actualRequestState.Requests.Contains(r) {
584 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
585 return true, errors.New("too many outstanding requests")
587 cn.actualRequestState.Requests.Add(r)
588 if cn.validReceiveChunks == nil {
589 cn.validReceiveChunks = make(map[RequestIndex]int)
591 cn.validReceiveChunks[r]++
592 cn.t.pendingRequests.Inc(r)
593 cn.updateExpectingChunks()
594 ppReq := cn.t.requestIndexToRequest(r)
595 for _, f := range cn.callbacks.SentRequest {
596 f(PeerRequestEvent{cn, ppReq})
598 return cn.peerImpl._request(ppReq), nil
601 func (me *PeerConn) _request(r Request) bool {
602 return me.write(pp.Message{
610 func (me *Peer) cancel(r RequestIndex) bool {
611 if !me.actualRequestState.Requests.Contains(r) {
617 func (me *PeerConn) _cancel(r RequestIndex) bool {
618 if me.cancelledRequests.Contains(r) {
619 // Already cancelled and waiting for a response.
622 if me.fastEnabled() {
623 me.cancelledRequests.Add(r)
625 if !me.deleteRequest(r) {
626 panic("request not existing should have been guarded")
628 if me.actualRequestState.Requests.GetCardinality() == 0 {
629 me.updateRequests("Peer.cancel")
632 return me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
635 func (cn *PeerConn) fillWriteBuffer() {
636 if !cn.applyNextRequestState() {
639 if cn.pex.IsEnabled() {
640 if flow := cn.pex.Share(cn.write); !flow {
647 func (cn *PeerConn) have(piece pieceIndex) {
648 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
653 Index: pp.Integer(piece),
655 cn.sentHaves.Add(bitmap.BitIndex(piece))
658 func (cn *PeerConn) postBitfield() {
659 if cn.sentHaves.Len() != 0 {
660 panic("bitfield must be first have-related message sent")
662 if !cn.t.haveAnyPieces() {
667 Bitfield: cn.t.bitfield(),
669 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
672 func (cn *PeerConn) updateRequests(reason string) {
673 if cn.needRequestUpdate != "" {
676 cn.needRequestUpdate = reason
680 // Emits the indices in the Bitmaps bms in order, never repeating any index.
681 // skip is mutated during execution, and its initial values will never be
683 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
684 return func(cb iter.Callback) {
685 for _, bm := range bms {
687 func(_i interface{}) bool {
689 if skip.Contains(bitmap.BitIndex(i)) {
692 skip.Add(bitmap.BitIndex(i))
703 func (cn *Peer) peerPiecesChanged() {
704 cn.t.maybeDropMutuallyCompletePeer(cn)
707 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
708 if newMin > cn.peerMinPieces {
709 cn.peerMinPieces = newMin
713 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
714 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
715 return errors.New("invalid piece")
717 if cn.peerHasPiece(piece) {
720 cn.raisePeerMinPieces(piece + 1)
721 if !cn.peerHasPiece(piece) {
722 cn.t.incPieceAvailability(piece)
724 cn._peerPieces.Add(uint32(piece))
725 if cn.t.wantPieceIndex(piece) {
726 cn.updateRequests("have")
728 cn.peerPiecesChanged()
732 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
734 panic("expected bitfield length divisible by 8")
736 // We know that the last byte means that at most the last 7 bits are wasted.
737 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
738 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
739 // Ignore known excess pieces.
740 bf = bf[:cn.t.numPieces()]
742 pp := cn.newPeerPieces()
743 cn.peerSentHaveAll = false
744 for i, have := range bf {
746 cn.raisePeerMinPieces(pieceIndex(i) + 1)
747 if !pp.Contains(bitmap.BitIndex(i)) {
748 cn.t.incPieceAvailability(i)
751 if pp.Contains(bitmap.BitIndex(i)) {
752 cn.t.decPieceAvailability(i)
756 cn._peerPieces.Add(uint32(i))
757 if cn.t.wantPieceIndex(i) {
758 cn.updateRequests("bitfield")
761 cn._peerPieces.Remove(uint32(i))
764 cn.peerPiecesChanged()
768 func (cn *Peer) onPeerHasAllPieces() {
771 npp, pc := cn.newPeerPieces(), t.numPieces()
772 for i := 0; i < pc; i += 1 {
773 if !npp.Contains(bitmap.BitIndex(i)) {
774 t.incPieceAvailability(i)
778 cn.peerSentHaveAll = true
779 cn._peerPieces.Clear()
780 if cn.t._pendingPieces.Len() != 0 {
781 cn.updateRequests("have all")
783 cn.peerPiecesChanged()
786 func (cn *PeerConn) onPeerSentHaveAll() error {
787 cn.onPeerHasAllPieces()
791 func (cn *PeerConn) peerSentHaveNone() error {
792 cn.t.decPeerPieceAvailability(&cn.Peer)
793 cn._peerPieces.Clear()
794 cn.peerSentHaveAll = false
795 cn.peerPiecesChanged()
799 func (c *PeerConn) requestPendingMetadata() {
803 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
804 // Peer doesn't support this.
807 // Request metadata pieces that we don't have in a random order.
809 for index := 0; index < c.t.metadataPieceCount(); index++ {
810 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
811 pending = append(pending, index)
814 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
815 for _, i := range pending {
816 c.requestMetadataPiece(i)
820 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
821 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
822 if msg.Type == pp.Extended {
823 for name, id := range cn.PeerExtensionIDs {
824 if id != msg.ExtendedID {
827 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
830 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
833 // After handshake, we know what Torrent and Client stats to include for a
835 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
841 // All ConnStats that include this connection. Some objects are not known
842 // until the handshake is complete, after which it's expected to reconcile the
844 func (cn *Peer) allStats(f func(*ConnStats)) {
846 if cn.reconciledHandshakeStats {
847 cn.postHandshakeStats(f)
851 func (cn *PeerConn) wroteBytes(n int64) {
852 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
855 func (cn *PeerConn) readBytes(n int64) {
856 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
859 // Returns whether the connection could be useful to us. We're seeding and
860 // they want data, we don't have metainfo and they can provide it, etc.
861 func (c *Peer) useful() bool {
863 if c.closed.IsSet() {
867 return c.supportsExtension("ut_metadata")
869 if t.seeding() && c.peerInterested {
872 if c.peerHasWantedPieces() {
878 func (c *Peer) lastHelpful() (ret time.Time) {
879 ret = c.lastUsefulChunkReceived
880 if c.t.seeding() && c.lastChunkSent.After(ret) {
881 ret = c.lastChunkSent
886 func (c *PeerConn) fastEnabled() bool {
887 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
890 func (c *PeerConn) reject(r Request) {
891 if !c.fastEnabled() {
892 panic("fast not enabled")
894 c.write(r.ToMsg(pp.Reject))
895 delete(c.peerRequests, r)
898 func (c *PeerConn) onReadRequest(r Request) error {
899 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
900 if _, ok := c.peerRequests[r]; ok {
901 torrent.Add("duplicate requests received", 1)
905 torrent.Add("requests received while choking", 1)
907 torrent.Add("requests rejected while choking", 1)
912 // TODO: What if they've already requested this?
913 if len(c.peerRequests) >= localClientReqq {
914 torrent.Add("requests received while queue full", 1)
918 // BEP 6 says we may close here if we choose.
921 if !c.t.havePiece(pieceIndex(r.Index)) {
922 // This isn't necessarily them screwing up. We can drop pieces
923 // from our storage, and can't communicate this to peers
924 // except by reconnecting.
925 requestsReceivedForMissingPieces.Add(1)
926 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
928 // Check this after we know we have the piece, so that the piece length will be known.
929 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
930 torrent.Add("bad requests received", 1)
931 return errors.New("bad Request")
933 if c.peerRequests == nil {
934 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
936 value := &peerRequestState{}
937 c.peerRequests[r] = value
938 go c.peerRequestDataReader(r, value)
943 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
944 b, err := readPeerRequestData(r, c)
946 defer c.locker().Unlock()
948 c.peerRequestDataReadFailed(err, r)
951 panic("data must be non-nil to trigger send")
958 // If this is maintained correctly, we might be able to support optional synchronous reading for
959 // chunk sending, the way it used to work.
960 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
961 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
962 i := pieceIndex(r.Index)
963 if c.t.pieceComplete(i) {
964 // There used to be more code here that just duplicated the following break. Piece
965 // completions are currently cached, so I'm not sure how helpful this update is, except to
966 // pull any completion changes pushed to the storage backend in failed reads that got us
968 c.t.updatePieceCompletion(i)
970 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
971 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
972 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
973 // next connect. TODO: Support rejecting here too.
975 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
980 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
981 b := make([]byte, r.Length)
982 p := c.t.info.Piece(int(r.Index))
983 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
990 panic("expected error")
996 func runSafeExtraneous(f func()) {
1004 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1005 // exit. Returning will end the connection.
1006 func (c *PeerConn) mainReadLoop() (err error) {
1009 torrent.Add("connection.mainReadLoop returned with error", 1)
1011 torrent.Add("connection.mainReadLoop returned with no error", 1)
1017 decoder := pp.Decoder{
1018 R: bufio.NewReaderSize(c.r, 1<<17),
1019 MaxLength: 256 * 1024,
1027 err = decoder.Decode(&msg)
1029 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1032 if t.closed.IsSet() || c.closed.IsSet() {
1038 c.lastMessageReceived = time.Now()
1040 receivedKeepalives.Add(1)
1043 messageTypesReceived.Add(msg.Type.String(), 1)
1044 if msg.Type.FastExtension() && !c.fastEnabled() {
1045 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1046 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1053 if !c.fastEnabled() {
1054 c.deleteAllRequests()
1056 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1057 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1058 c.t.pendingRequests.Dec(x)
1063 c.peerChoking = true
1064 // We can then reset our interest.
1065 c.updateRequests("choked")
1066 c.updateExpectingChunks()
1069 return errors.New("got unchoke but not choked")
1071 c.peerChoking = false
1073 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1074 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1076 c.t.pendingRequests.Inc(x)
1080 if preservedCount != 0 {
1081 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
1083 log.Printf("%v requests were preserved while being choked", preservedCount)
1084 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
1086 c.updateRequests("unchoked")
1087 c.updateExpectingChunks()
1089 c.peerInterested = true
1091 case pp.NotInterested:
1092 c.peerInterested = false
1093 // We don't clear their requests since it isn't clear in the spec.
1094 // We'll probably choke them for this, which will clear them if
1095 // appropriate, and is clearly specified.
1097 err = c.peerSentHave(pieceIndex(msg.Index))
1099 err = c.peerSentBitfield(msg.Bitfield)
1101 r := newRequestFromMessage(&msg)
1102 err = c.onReadRequest(r)
1104 c.doChunkReadStats(int64(len(msg.Piece)))
1105 err = c.receiveChunk(&msg)
1106 if len(msg.Piece) == int(t.chunkSize) {
1107 t.chunkPool.Put(&msg.Piece)
1110 err = fmt.Errorf("receiving chunk: %w", err)
1113 req := newRequestFromMessage(&msg)
1114 c.onPeerSentCancel(req)
1116 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1120 pingAddr := net.UDPAddr{
1125 pingAddr.Port = int(msg.Port)
1127 cl.eachDhtServer(func(s DhtServer) {
1128 go s.Ping(&pingAddr)
1131 torrent.Add("suggests received", 1)
1132 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1133 c.updateRequests("suggested")
1135 err = c.onPeerSentHaveAll()
1137 err = c.peerSentHaveNone()
1139 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1140 case pp.AllowedFast:
1141 torrent.Add("allowed fasts received", 1)
1142 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1143 pieceIndex := msg.Index.Int()
1144 // If we have outstanding requests that aren't currently counted toward the combined
1145 // outstanding request count, increment them.
1146 if c.peerAllowedFast.CheckedAdd(msg.Index.Uint32()) && c.peerChoking &&
1147 // The check here could be against having the info, but really what we need to know
1148 // is if there are any existing requests.
1149 !c.actualRequestState.Requests.IsEmpty() {
1151 i := c.actualRequestState.Requests.Iterator()
1152 i.AdvanceIfNeeded(t.pieceRequestIndexOffset(pieceIndex))
1155 if r >= t.pieceRequestIndexOffset(pieceIndex+1) {
1158 c.t.pendingRequests.Inc(r)
1161 c.updateRequests("PeerConn.mainReadLoop allowed fast")
1163 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1165 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1173 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1174 if c.deleteRequest(r) {
1175 if c.actualRequestState.Requests.GetCardinality() == 0 {
1176 c.updateRequests("Peer.remoteRejectedRequest")
1178 c.decExpectedChunkReceive(r)
1182 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1183 count := c.validReceiveChunks[r]
1185 delete(c.validReceiveChunks, r)
1186 } else if count > 1 {
1187 c.validReceiveChunks[r] = count - 1
1193 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1195 // TODO: Should we still do this?
1197 // These clients use their own extension IDs for outgoing message
1198 // types, which is incorrect.
1199 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1207 case pp.HandshakeExtendedID:
1208 var d pp.ExtendedHandshakeMessage
1209 if err := bencode.Unmarshal(payload, &d); err != nil {
1210 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1211 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1213 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1216 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1218 c.PeerMaxRequests = d.Reqq
1220 c.PeerClientName = d.V
1221 if c.PeerExtensionIDs == nil {
1222 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1224 c.PeerListenPort = d.Port
1225 c.PeerPrefersEncryption = d.Encryption
1226 for name, id := range d.M {
1227 if _, ok := c.PeerExtensionIDs[name]; !ok {
1228 peersSupportingExtension.Add(string(name), 1)
1230 c.PeerExtensionIDs[name] = id
1232 if d.MetadataSize != 0 {
1233 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1234 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1237 c.requestPendingMetadata()
1238 if !t.cl.config.DisablePEX {
1239 t.pex.Add(c) // we learnt enough now
1243 case metadataExtendedId:
1244 err := cl.gotMetadataExtensionMsg(payload, t, c)
1246 return fmt.Errorf("handling metadata extension message: %w", err)
1250 if !c.pex.IsEnabled() {
1251 return nil // or hang-up maybe?
1253 return c.pex.Recv(payload)
1255 return fmt.Errorf("unexpected extended message ID: %v", id)
1259 // Set both the Reader and Writer for the connection from a single ReadWriter.
1260 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1265 // Returns the Reader and Writer as a combined ReadWriter.
1266 func (cn *PeerConn) rw() io.ReadWriter {
1273 func (c *Peer) doChunkReadStats(size int64) {
1274 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1277 // Handle a received chunk from a peer.
1278 func (c *Peer) receiveChunk(msg *pp.Message) error {
1279 chunksReceived.Add("total", 1)
1281 ppReq := newRequestFromMessage(msg)
1282 req := c.t.requestIndexFromRequest(ppReq)
1285 chunksReceived.Add("while choked", 1)
1288 if c.validReceiveChunks[req] <= 0 {
1289 chunksReceived.Add("unexpected", 1)
1290 return errors.New("received unexpected chunk")
1292 c.decExpectedChunkReceive(req)
1294 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1295 chunksReceived.Add("due to allowed fast", 1)
1298 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1299 // have actually already received the piece, while we have the Client unlocked to write the data
1301 deletedRequest := false
1303 if c.actualRequestState.Requests.Contains(req) {
1304 for _, f := range c.callbacks.ReceivedRequested {
1305 f(PeerMessageEvent{c, msg})
1308 // Request has been satisfied.
1309 if c.deleteRequest(req) {
1310 deletedRequest = true
1312 c._chunksReceivedWhileExpecting++
1314 if c.actualRequestState.Requests.GetCardinality() == 0 {
1315 c.updateRequests("Peer.receiveChunk deleted request")
1318 chunksReceived.Add("unwanted", 1)
1325 // Do we actually want this chunk?
1326 if t.haveChunk(ppReq) {
1327 chunksReceived.Add("wasted", 1)
1328 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1332 piece := &t.pieces[ppReq.Index]
1334 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1335 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1337 c.piecesReceivedSinceLastRequestUpdate++
1338 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1340 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1341 f(ReceivedUsefulDataEvent{c, msg})
1343 c.lastUsefulChunkReceived = time.Now()
1345 // Need to record that it hasn't been written yet, before we attempt to do
1346 // anything with it.
1347 piece.incrementPendingWrites()
1348 // Record that we have the chunk, so we aren't trying to download it while
1349 // waiting for it to be written to storage.
1350 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1352 // Cancel pending requests for this chunk from *other* peers.
1353 t.iterPeers(func(p *Peer) {
1360 err := func() error {
1363 concurrentChunkWrites.Add(1)
1364 defer concurrentChunkWrites.Add(-1)
1365 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1366 // number of connections. We write inline with receiving the chunk (with this lock dance),
1367 // because we want to handle errors synchronously and I haven't thought of a nice way to
1368 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1370 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1373 piece.decrementPendingWrites()
1376 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1378 // Necessary to pass TestReceiveChunkStorageFailureSeederFastExtensionDisabled. I think a
1379 // request update runs while we're writing the chunk that just failed. Then we never do a
1380 // fresh update after pending the failed request.
1381 c.updateRequests("Peer.receiveChunk error writing chunk")
1382 t.onWriteChunkErr(err)
1386 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1388 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1389 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1390 t.queuePieceCheck(pieceIndex(ppReq.Index))
1391 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1392 // chunk status (such as the haveChunk call above) to have to check all the various other
1393 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1394 // that chunk pieces are pended at an appropriate time later however.
1397 cl.event.Broadcast()
1398 // We do this because we've written a chunk, and may change PieceState.Partial.
1399 t.publishPieceChange(pieceIndex(ppReq.Index))
1404 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1405 if c.peerTouchedPieces == nil {
1406 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1408 c.peerTouchedPieces[piece] = struct{}{}
1409 ds := &c.t.pieces[piece].dirtiers
1411 *ds = make(map[*Peer]struct{})
1413 (*ds)[c] = struct{}{}
1416 func (c *PeerConn) uploadAllowed() bool {
1417 if c.t.cl.config.NoUpload {
1420 if c.t.dataUploadDisallowed {
1426 if !c.peerHasWantedPieces() {
1429 // Don't upload more than 100 KiB more than we download.
1430 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1436 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1437 if c.uploadTimer == nil {
1438 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1440 c.uploadTimer.Reset(delay)
1444 // Also handles choking and unchoking of the remote peer.
1445 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1446 // Breaking or completing this loop means we don't want to upload to the
1447 // peer anymore, and we choke them.
1449 for c.uploadAllowed() {
1450 // We want to upload to the peer.
1451 if !c.unchoke(msg) {
1454 for r, state := range c.peerRequests {
1455 if state.data == nil {
1458 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1460 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1462 delay := res.Delay()
1465 c.setRetryUploadTimer(delay)
1466 // Hard to say what to return here.
1469 more := c.sendChunk(r, msg, state)
1470 delete(c.peerRequests, r)
1481 func (cn *PeerConn) drop() {
1482 cn.t.dropConnection(cn)
1485 func (cn *Peer) netGoodPiecesDirtied() int64 {
1486 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1489 func (c *Peer) peerHasWantedPieces() bool {
1490 if c.peerSentHaveAll {
1491 return !c.t.haveAllPieces()
1493 if !c.t.haveInfo() {
1494 return c._peerPieces.GetCardinality() != 0
1496 return c._peerPieces.Intersects(
1497 roaring.FlipInt(&c.t._completedPieces, 0, c.t.numPieces()),
1501 func (c *Peer) deleteRequest(r RequestIndex) bool {
1502 if !c.actualRequestState.Requests.CheckedRemove(r) {
1505 c.cancelledRequests.Remove(r)
1506 for _, f := range c.callbacks.DeletedRequest {
1507 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1509 c.updateExpectingChunks()
1510 if !c.peerChoking || c.peerAllowedFast.Contains(r/c.t.chunksPerRegularPiece()) {
1511 c.t.pendingRequests.Dec(r)
1516 func (c *Peer) deleteAllRequests() {
1517 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1521 if !c.actualRequestState.Requests.IsEmpty() {
1522 panic(c.actualRequestState.Requests.GetCardinality())
1524 // for c := range c.t.conns {
1529 // This is called when something has changed that should wake the writer, such as putting stuff into
1530 // the writeBuffer, or changing some state that the writer can act on.
1531 func (c *PeerConn) tickleWriter() {
1532 c.messageWriter.writeCond.Broadcast()
1535 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1536 c.lastChunkSent = time.Now()
1537 return msg(pp.Message{
1545 func (c *PeerConn) setTorrent(t *Torrent) {
1547 panic("connection already associated with a torrent")
1550 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1551 t.reconcileHandshakeStats(c)
1554 func (c *Peer) peerPriority() (peerPriority, error) {
1555 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1558 func (c *Peer) remoteIp() net.IP {
1559 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1560 return net.ParseIP(host)
1563 func (c *Peer) remoteIpPort() IpPort {
1564 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1565 return IpPort{ipa.IP, uint16(ipa.Port)}
1568 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1569 f := pp.PexPeerFlags(0)
1570 if c.PeerPrefersEncryption {
1571 f |= pp.PexPrefersEncryption
1574 f |= pp.PexOutgoingConn
1577 f |= pp.PexSupportsUtp
1582 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1583 // advertised listen port.
1584 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1585 if !c.outgoing && c.PeerListenPort != 0 {
1586 switch addr := c.RemoteAddr.(type) {
1589 dialAddr.Port = c.PeerListenPort
1593 dialAddr.Port = c.PeerListenPort
1600 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1601 f := c.pexPeerFlags()
1602 addr := c.dialAddr()
1603 return pexEvent{t, addr, f}
1606 func (c *PeerConn) String() string {
1607 return fmt.Sprintf("connection %p", c)
1610 func (c *Peer) trust() connectionTrust {
1611 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1614 type connectionTrust struct {
1616 NetGoodPiecesDirted int64
1619 func (l connectionTrust) Less(r connectionTrust) bool {
1620 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1623 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1624 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1625 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1627 defer cn.locker().RUnlock()
1628 return cn.newPeerPieces()
1631 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1632 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1633 // TODO: Can we use copy on write?
1634 ret := cn._peerPieces.Clone()
1635 if cn.peerSentHaveAll {
1636 if cn.t.haveInfo() {
1637 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1639 ret.AddRange(0, bitmap.ToEnd)
1645 func (cn *Peer) stats() *ConnStats {
1649 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1650 pc, ok := p.peerImpl.(*PeerConn)
1654 func (p *PeerConn) onNextRequestStateChanged() {