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 lastBecameInterested time.Time
88 priorInterest time.Duration
90 lastStartedExpectingToReceiveChunks time.Time
91 cumulativeExpectedToReceiveChunks time.Duration
92 _chunksReceivedWhileExpecting int64
95 piecesReceivedSinceLastRequestUpdate maxRequests
96 maxPiecesReceivedBetweenRequestUpdates maxRequests
97 // Chunks that we might reasonably expect to receive from the peer. Due to
98 // latency, buffering, and implementation differences, we may receive
99 // chunks that are no longer in the set of requests actually want.
100 validReceiveChunks map[RequestIndex]int
101 // Indexed by metadata piece, set to true if posted and pending a
103 metadataRequests []bool
104 sentHaves bitmap.Bitmap
106 // Stuff controlled by the remote peer.
109 peerRequests map[Request]*peerRequestState
110 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
112 // The pieces the peer has claimed to have.
113 _peerPieces roaring.Bitmap
114 // The peer has everything. This can occur due to a special message, when
115 // we may not even know the number of pieces in the torrent yet.
117 // The highest possible number of pieces the torrent could have based on
118 // communication with the peer. Generally only useful until we have the
120 peerMinPieces pieceIndex
121 // Pieces we've accepted chunks for from the peer.
122 peerTouchedPieces map[pieceIndex]struct{}
123 peerAllowedFast roaring.Bitmap
125 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
126 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
127 PeerClientName string
132 // Maintains the state of a BitTorrent-protocol based connection with a peer.
133 type PeerConn struct {
136 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
137 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
142 PeerExtensionBytes pp.PeerExtensionBits
144 // The actual Conn, used for closing, and setting socket options.
146 // The Reader and Writer for this Conn, with hooks installed for stats,
147 // limiting, deadlines etc.
151 messageWriter peerConnMsgWriter
153 uploadTimer *time.Timer
157 func (cn *PeerConn) connStatusString() string {
158 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
161 func (cn *Peer) updateExpectingChunks() {
162 if cn.expectingChunks() {
163 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
164 cn.lastStartedExpectingToReceiveChunks = time.Now()
167 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
168 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
169 cn.lastStartedExpectingToReceiveChunks = time.Time{}
174 func (cn *Peer) expectingChunks() bool {
175 if cn.actualRequestState.Requests.IsEmpty() {
178 if !cn.actualRequestState.Interested {
184 haveAllowedFastRequests := false
185 cn.peerAllowedFast.Iterate(func(i uint32) bool {
186 haveAllowedFastRequests = roaringBitmapRangeCardinality(
187 &cn.actualRequestState.Requests,
188 cn.t.pieceRequestIndexOffset(pieceIndex(i)),
189 cn.t.pieceRequestIndexOffset(pieceIndex(i+1)),
191 return !haveAllowedFastRequests
193 return haveAllowedFastRequests
196 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
197 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
200 // Returns true if the connection is over IPv6.
201 func (cn *PeerConn) ipv6() bool {
206 return len(ip) == net.IPv6len
209 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
210 // specification for this.
211 func (cn *PeerConn) isPreferredDirection() bool {
212 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
215 // Returns whether the left connection should be preferred over the right one,
216 // considering only their networking properties. If ok is false, we can't
218 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
220 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
221 ml.NextBool(!l.utp(), !r.utp())
222 ml.NextBool(l.ipv6(), r.ipv6())
226 func (cn *Peer) cumInterest() time.Duration {
227 ret := cn.priorInterest
228 if cn.actualRequestState.Interested {
229 ret += time.Since(cn.lastBecameInterested)
234 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
235 if cn.peerSentHaveAll {
238 if !cn.t.haveInfo() {
241 return roaring.Flip(&cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
244 func (cn *PeerConn) locker() *lockWithDeferreds {
245 return cn.t.cl.locker()
248 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
249 _, ok := cn.PeerExtensionIDs[ext]
253 // The best guess at number of pieces in the torrent for this peer.
254 func (cn *Peer) bestPeerNumPieces() pieceIndex {
256 return cn.t.numPieces()
258 return cn.peerMinPieces
261 func (cn *Peer) completedString() string {
262 have := pieceIndex(cn._peerPieces.GetCardinality())
263 if cn.peerSentHaveAll {
264 have = cn.bestPeerNumPieces()
266 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
269 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
270 cn.setNumPieces(info.NumPieces())
273 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
274 // receiving badly sized BITFIELD, or invalid HAVE messages.
275 func (cn *PeerConn) setNumPieces(num pieceIndex) {
276 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
277 cn.peerPiecesChanged()
280 func eventAgeString(t time.Time) string {
284 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
287 func (cn *PeerConn) connectionFlags() (ret string) {
289 ret += string([]byte{b})
291 if cn.cryptoMethod == mse.CryptoMethodRC4 {
293 } else if cn.headerEncrypted {
296 ret += string(cn.Discovery)
303 func (cn *PeerConn) utp() bool {
304 return parseNetworkString(cn.Network).Udp
307 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
308 func (cn *Peer) statusFlags() (ret string) {
310 ret += string([]byte{b})
312 if cn.actualRequestState.Interested {
319 ret += cn.connectionFlags()
321 if cn.peerInterested {
330 func (cn *Peer) downloadRate() float64 {
331 num := cn._stats.BytesReadUsefulData.Int64()
335 return float64(num) / cn.totalExpectingTime().Seconds()
338 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
339 ret = make(map[pieceIndex]int)
340 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
341 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
347 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
348 // \t isn't preserved in <pre> blocks?
349 if cn.closed.IsSet() {
350 fmt.Fprint(w, "CLOSED: ")
352 fmt.Fprintln(w, cn.connStatusString())
353 prio, err := cn.peerPriority()
354 prioStr := fmt.Sprintf("%08x", prio)
356 prioStr += ": " + err.Error()
358 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
359 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
360 eventAgeString(cn.lastMessageReceived),
361 eventAgeString(cn.completedHandshake),
362 eventAgeString(cn.lastHelpful()),
364 cn.totalExpectingTime(),
367 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
368 cn.completedString(),
369 len(cn.peerTouchedPieces),
370 &cn._stats.ChunksReadUseful,
371 &cn._stats.ChunksRead,
372 &cn._stats.ChunksWritten,
373 cn.actualRequestState.Requests.GetCardinality(),
374 cn.nominalMaxRequests(),
376 len(cn.peerRequests),
379 cn.downloadRate()/(1<<10),
381 fmt.Fprintf(w, " requested pieces:")
382 type pieceNumRequestsType struct {
386 var pieceNumRequests []pieceNumRequestsType
387 for piece, count := range cn.numRequestsByPiece() {
388 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
390 sort.Slice(pieceNumRequests, func(i, j int) bool {
391 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
393 for _, elem := range pieceNumRequests {
394 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
399 func (p *Peer) close() {
405 p.t.decPeerPieceAvailability(p)
407 for _, f := range p.callbacks.PeerClosed {
412 func (cn *PeerConn) onClose() {
413 if cn.pex.IsEnabled() {
420 if cb := cn.callbacks.PeerConnClosed; cb != nil {
425 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
426 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
429 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
430 // https://github.com/pion/datachannel/issues/59 is fixed.
431 const writeBufferHighWaterLen = 1 << 15
433 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
434 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
435 func (cn *PeerConn) write(msg pp.Message) bool {
436 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
437 // We don't need to track bytes here because the connection's Writer has that behaviour injected
438 // (although there's some delay between us buffering the message, and the connection writer
439 // flushing it out.).
440 notFull := cn.messageWriter.write(msg)
441 // Last I checked only Piece messages affect stats, and we don't write those.
447 func (cn *PeerConn) requestMetadataPiece(index int) {
448 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
449 if eID == pp.ExtensionDeleteNumber {
452 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
455 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
456 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
457 for index >= len(cn.metadataRequests) {
458 cn.metadataRequests = append(cn.metadataRequests, false)
460 cn.metadataRequests[index] = true
463 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
464 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
467 // The actual value to use as the maximum outbound requests.
468 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
469 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 2048))
472 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
473 ret = cn.cumulativeExpectedToReceiveChunks
474 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
475 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
481 func (cn *PeerConn) onPeerSentCancel(r Request) {
482 if _, ok := cn.peerRequests[r]; !ok {
483 torrent.Add("unexpected cancels received", 1)
486 if cn.fastEnabled() {
489 delete(cn.peerRequests, r)
493 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
498 more = msg(pp.Message{
501 if cn.fastEnabled() {
502 for r := range cn.peerRequests {
503 // TODO: Don't reject pieces in allowed fast set.
507 cn.peerRequests = nil
512 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
517 return msg(pp.Message{
522 func (cn *Peer) setInterested(interested bool) bool {
523 if cn.actualRequestState.Interested == interested {
526 cn.actualRequestState.Interested = interested
528 cn.lastBecameInterested = time.Now()
529 } else if !cn.lastBecameInterested.IsZero() {
530 cn.priorInterest += time.Since(cn.lastBecameInterested)
532 cn.updateExpectingChunks()
533 // log.Printf("%p: setting interest: %v", cn, interested)
534 return cn.writeInterested(interested)
537 func (pc *PeerConn) writeInterested(interested bool) bool {
538 return pc.write(pp.Message{
539 Type: func() pp.MessageType {
543 return pp.NotInterested
549 // The function takes a message to be sent, and returns true if more messages
551 type messageWriter func(pp.Message) bool
553 func (cn *Peer) shouldRequest(r RequestIndex) error {
554 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
555 if !cn.peerHasPiece(pi) {
556 return errors.New("requesting piece peer doesn't have")
558 if !cn.t.peerIsActive(cn) {
559 panic("requesting but not in active conns")
561 if cn.closed.IsSet() {
562 panic("requesting when connection is closed")
564 if cn.t.hashingPiece(pi) {
565 panic("piece is being hashed")
567 if cn.t.pieceQueuedForHash(pi) {
568 panic("piece is queued for hash")
570 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
571 panic("peer choking and piece not allowed fast")
576 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
577 if err := cn.shouldRequest(r); err != nil {
580 if cn.actualRequestState.Requests.Contains(r) {
583 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
584 return true, errors.New("too many outstanding requests")
586 cn.actualRequestState.Requests.Add(r)
587 if cn.validReceiveChunks == nil {
588 cn.validReceiveChunks = make(map[RequestIndex]int)
590 cn.validReceiveChunks[r]++
591 cn.t.pendingRequests.Inc(r)
592 cn.updateExpectingChunks()
593 ppReq := cn.t.requestIndexToRequest(r)
594 for _, f := range cn.callbacks.SentRequest {
595 f(PeerRequestEvent{cn, ppReq})
597 return cn.peerImpl._request(ppReq), nil
600 func (me *PeerConn) _request(r Request) bool {
601 return me.write(pp.Message{
609 func (me *Peer) cancel(r RequestIndex) bool {
610 if me.deleteRequest(r) {
611 if me.actualRequestState.Requests.GetCardinality() == 0 {
612 me.updateRequests("Peer.cancel")
614 return me.peerImpl._cancel(me.t.requestIndexToRequest(r))
619 func (me *PeerConn) _cancel(r Request) bool {
620 return me.write(makeCancelMessage(r))
623 func (cn *PeerConn) fillWriteBuffer() {
624 if !cn.applyNextRequestState() {
627 if cn.pex.IsEnabled() {
628 if flow := cn.pex.Share(cn.write); !flow {
635 func (cn *PeerConn) have(piece pieceIndex) {
636 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
641 Index: pp.Integer(piece),
643 cn.sentHaves.Add(bitmap.BitIndex(piece))
646 func (cn *PeerConn) postBitfield() {
647 if cn.sentHaves.Len() != 0 {
648 panic("bitfield must be first have-related message sent")
650 if !cn.t.haveAnyPieces() {
655 Bitfield: cn.t.bitfield(),
657 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
660 func (cn *PeerConn) updateRequests(reason string) {
661 if cn.needRequestUpdate != "" {
664 cn.needRequestUpdate = reason
668 // Emits the indices in the Bitmaps bms in order, never repeating any index.
669 // skip is mutated during execution, and its initial values will never be
671 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
672 return func(cb iter.Callback) {
673 for _, bm := range bms {
675 func(_i interface{}) bool {
677 if skip.Contains(bitmap.BitIndex(i)) {
680 skip.Add(bitmap.BitIndex(i))
691 func (cn *Peer) peerPiecesChanged() {
692 cn.t.maybeDropMutuallyCompletePeer(cn)
695 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
696 if newMin > cn.peerMinPieces {
697 cn.peerMinPieces = newMin
701 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
702 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
703 return errors.New("invalid piece")
705 if cn.peerHasPiece(piece) {
708 cn.raisePeerMinPieces(piece + 1)
709 if !cn.peerHasPiece(piece) {
710 cn.t.incPieceAvailability(piece)
712 cn._peerPieces.Add(uint32(piece))
713 if cn.t.wantPieceIndex(piece) {
714 cn.updateRequests("have")
716 cn.peerPiecesChanged()
720 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
722 panic("expected bitfield length divisible by 8")
724 // We know that the last byte means that at most the last 7 bits are wasted.
725 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
726 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
727 // Ignore known excess pieces.
728 bf = bf[:cn.t.numPieces()]
730 pp := cn.newPeerPieces()
731 cn.peerSentHaveAll = false
732 for i, have := range bf {
734 cn.raisePeerMinPieces(pieceIndex(i) + 1)
735 if !pp.Contains(bitmap.BitIndex(i)) {
736 cn.t.incPieceAvailability(i)
739 if pp.Contains(bitmap.BitIndex(i)) {
740 cn.t.decPieceAvailability(i)
744 cn._peerPieces.Add(uint32(i))
745 if cn.t.wantPieceIndex(i) {
746 cn.updateRequests("bitfield")
749 cn._peerPieces.Remove(uint32(i))
752 cn.peerPiecesChanged()
756 func (cn *Peer) onPeerHasAllPieces() {
759 npp, pc := cn.newPeerPieces(), t.numPieces()
760 for i := 0; i < pc; i += 1 {
761 if !npp.Contains(bitmap.BitIndex(i)) {
762 t.incPieceAvailability(i)
766 cn.peerSentHaveAll = true
767 cn._peerPieces.Clear()
768 if cn.t._pendingPieces.Len() != 0 {
769 cn.updateRequests("have all")
771 cn.peerPiecesChanged()
774 func (cn *PeerConn) onPeerSentHaveAll() error {
775 cn.onPeerHasAllPieces()
779 func (cn *PeerConn) peerSentHaveNone() error {
780 cn.t.decPeerPieceAvailability(&cn.Peer)
781 cn._peerPieces.Clear()
782 cn.peerSentHaveAll = false
783 cn.peerPiecesChanged()
787 func (c *PeerConn) requestPendingMetadata() {
791 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
792 // Peer doesn't support this.
795 // Request metadata pieces that we don't have in a random order.
797 for index := 0; index < c.t.metadataPieceCount(); index++ {
798 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
799 pending = append(pending, index)
802 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
803 for _, i := range pending {
804 c.requestMetadataPiece(i)
808 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
809 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
810 if msg.Type == pp.Extended {
811 for name, id := range cn.PeerExtensionIDs {
812 if id != msg.ExtendedID {
815 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
818 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
821 // After handshake, we know what Torrent and Client stats to include for a
823 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
829 // All ConnStats that include this connection. Some objects are not known
830 // until the handshake is complete, after which it's expected to reconcile the
832 func (cn *Peer) allStats(f func(*ConnStats)) {
834 if cn.reconciledHandshakeStats {
835 cn.postHandshakeStats(f)
839 func (cn *PeerConn) wroteBytes(n int64) {
840 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
843 func (cn *PeerConn) readBytes(n int64) {
844 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
847 // Returns whether the connection could be useful to us. We're seeding and
848 // they want data, we don't have metainfo and they can provide it, etc.
849 func (c *Peer) useful() bool {
851 if c.closed.IsSet() {
855 return c.supportsExtension("ut_metadata")
857 if t.seeding() && c.peerInterested {
860 if c.peerHasWantedPieces() {
866 func (c *Peer) lastHelpful() (ret time.Time) {
867 ret = c.lastUsefulChunkReceived
868 if c.t.seeding() && c.lastChunkSent.After(ret) {
869 ret = c.lastChunkSent
874 func (c *PeerConn) fastEnabled() bool {
875 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
878 func (c *PeerConn) reject(r Request) {
879 if !c.fastEnabled() {
880 panic("fast not enabled")
882 c.write(r.ToMsg(pp.Reject))
883 delete(c.peerRequests, r)
886 func (c *PeerConn) onReadRequest(r Request) error {
887 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
888 if _, ok := c.peerRequests[r]; ok {
889 torrent.Add("duplicate requests received", 1)
893 torrent.Add("requests received while choking", 1)
895 torrent.Add("requests rejected while choking", 1)
900 // TODO: What if they've already requested this?
901 if len(c.peerRequests) >= localClientReqq {
902 torrent.Add("requests received while queue full", 1)
906 // BEP 6 says we may close here if we choose.
909 if !c.t.havePiece(pieceIndex(r.Index)) {
910 // This isn't necessarily them screwing up. We can drop pieces
911 // from our storage, and can't communicate this to peers
912 // except by reconnecting.
913 requestsReceivedForMissingPieces.Add(1)
914 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
916 // Check this after we know we have the piece, so that the piece length will be known.
917 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
918 torrent.Add("bad requests received", 1)
919 return errors.New("bad Request")
921 if c.peerRequests == nil {
922 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
924 value := &peerRequestState{}
925 c.peerRequests[r] = value
926 go c.peerRequestDataReader(r, value)
931 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
932 b, err := readPeerRequestData(r, c)
934 defer c.locker().Unlock()
936 c.peerRequestDataReadFailed(err, r)
939 panic("data must be non-nil to trigger send")
946 // If this is maintained correctly, we might be able to support optional synchronous reading for
947 // chunk sending, the way it used to work.
948 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
949 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
950 i := pieceIndex(r.Index)
951 if c.t.pieceComplete(i) {
952 // There used to be more code here that just duplicated the following break. Piece
953 // completions are currently cached, so I'm not sure how helpful this update is, except to
954 // pull any completion changes pushed to the storage backend in failed reads that got us
956 c.t.updatePieceCompletion(i)
958 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
959 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
960 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
961 // next connect. TODO: Support rejecting here too.
963 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
968 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
969 b := make([]byte, r.Length)
970 p := c.t.info.Piece(int(r.Index))
971 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
978 panic("expected error")
984 func runSafeExtraneous(f func()) {
992 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
993 // exit. Returning will end the connection.
994 func (c *PeerConn) mainReadLoop() (err error) {
997 torrent.Add("connection.mainReadLoop returned with error", 1)
999 torrent.Add("connection.mainReadLoop returned with no error", 1)
1005 decoder := pp.Decoder{
1006 R: bufio.NewReaderSize(c.r, 1<<17),
1007 MaxLength: 256 * 1024,
1015 err = decoder.Decode(&msg)
1017 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1020 if t.closed.IsSet() || c.closed.IsSet() {
1026 c.lastMessageReceived = time.Now()
1028 receivedKeepalives.Add(1)
1031 messageTypesReceived.Add(msg.Type.String(), 1)
1032 if msg.Type.FastExtension() && !c.fastEnabled() {
1033 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1034 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1041 if !c.fastEnabled() {
1042 c.deleteAllRequests()
1044 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1045 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1046 c.t.pendingRequests.Dec(x)
1051 c.peerChoking = true
1052 // We can then reset our interest.
1053 c.updateRequests("choked")
1054 c.updateExpectingChunks()
1057 return errors.New("got unchoke but not choked")
1059 c.peerChoking = false
1061 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1062 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1064 c.t.pendingRequests.Inc(x)
1068 if preservedCount != 0 {
1069 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
1071 log.Printf("%v requests were preserved while being choked", preservedCount)
1072 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
1074 c.updateRequests("unchoked")
1075 c.updateExpectingChunks()
1077 c.peerInterested = true
1079 case pp.NotInterested:
1080 c.peerInterested = false
1081 // We don't clear their requests since it isn't clear in the spec.
1082 // We'll probably choke them for this, which will clear them if
1083 // appropriate, and is clearly specified.
1085 err = c.peerSentHave(pieceIndex(msg.Index))
1087 err = c.peerSentBitfield(msg.Bitfield)
1089 r := newRequestFromMessage(&msg)
1090 err = c.onReadRequest(r)
1092 c.doChunkReadStats(int64(len(msg.Piece)))
1093 err = c.receiveChunk(&msg)
1094 if len(msg.Piece) == int(t.chunkSize) {
1095 t.chunkPool.Put(&msg.Piece)
1098 err = fmt.Errorf("receiving chunk: %w", err)
1101 req := newRequestFromMessage(&msg)
1102 c.onPeerSentCancel(req)
1104 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1108 pingAddr := net.UDPAddr{
1113 pingAddr.Port = int(msg.Port)
1115 cl.eachDhtServer(func(s DhtServer) {
1116 go s.Ping(&pingAddr)
1119 torrent.Add("suggests received", 1)
1120 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1121 c.updateRequests("suggested")
1123 err = c.onPeerSentHaveAll()
1125 err = c.peerSentHaveNone()
1127 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1128 case pp.AllowedFast:
1129 torrent.Add("allowed fasts received", 1)
1130 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1131 pieceIndex := msg.Index.Int()
1132 // If we have outstanding requests that aren't currently counted toward the combined
1133 // outstanding request count, increment them.
1134 if c.peerAllowedFast.CheckedAdd(msg.Index.Uint32()) && c.peerChoking &&
1135 // The check here could be against having the info, but really what we need to know
1136 // is if there are any existing requests.
1137 !c.actualRequestState.Requests.IsEmpty() {
1139 i := c.actualRequestState.Requests.Iterator()
1140 i.AdvanceIfNeeded(t.pieceRequestIndexOffset(pieceIndex))
1143 if r >= t.pieceRequestIndexOffset(pieceIndex+1) {
1146 c.t.pendingRequests.Inc(r)
1149 c.updateRequests("PeerConn.mainReadLoop allowed fast")
1151 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1153 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1161 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1162 if c.deleteRequest(r) {
1163 if c.actualRequestState.Requests.GetCardinality() == 0 {
1164 c.updateRequests("Peer.remoteRejectedRequest")
1166 c.decExpectedChunkReceive(r)
1170 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1171 count := c.validReceiveChunks[r]
1173 delete(c.validReceiveChunks, r)
1174 } else if count > 1 {
1175 c.validReceiveChunks[r] = count - 1
1181 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1183 // TODO: Should we still do this?
1185 // These clients use their own extension IDs for outgoing message
1186 // types, which is incorrect.
1187 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1195 case pp.HandshakeExtendedID:
1196 var d pp.ExtendedHandshakeMessage
1197 if err := bencode.Unmarshal(payload, &d); err != nil {
1198 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1199 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1201 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1204 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1206 c.PeerMaxRequests = d.Reqq
1208 c.PeerClientName = d.V
1209 if c.PeerExtensionIDs == nil {
1210 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1212 c.PeerListenPort = d.Port
1213 c.PeerPrefersEncryption = d.Encryption
1214 for name, id := range d.M {
1215 if _, ok := c.PeerExtensionIDs[name]; !ok {
1216 peersSupportingExtension.Add(string(name), 1)
1218 c.PeerExtensionIDs[name] = id
1220 if d.MetadataSize != 0 {
1221 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1222 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1225 c.requestPendingMetadata()
1226 if !t.cl.config.DisablePEX {
1227 t.pex.Add(c) // we learnt enough now
1231 case metadataExtendedId:
1232 err := cl.gotMetadataExtensionMsg(payload, t, c)
1234 return fmt.Errorf("handling metadata extension message: %w", err)
1238 if !c.pex.IsEnabled() {
1239 return nil // or hang-up maybe?
1241 return c.pex.Recv(payload)
1243 return fmt.Errorf("unexpected extended message ID: %v", id)
1247 // Set both the Reader and Writer for the connection from a single ReadWriter.
1248 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1253 // Returns the Reader and Writer as a combined ReadWriter.
1254 func (cn *PeerConn) rw() io.ReadWriter {
1261 func (c *Peer) doChunkReadStats(size int64) {
1262 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1265 // Handle a received chunk from a peer.
1266 func (c *Peer) receiveChunk(msg *pp.Message) error {
1267 chunksReceived.Add("total", 1)
1269 ppReq := newRequestFromMessage(msg)
1270 req := c.t.requestIndexFromRequest(ppReq)
1273 chunksReceived.Add("while choked", 1)
1276 if c.validReceiveChunks[req] <= 0 {
1277 chunksReceived.Add("unexpected", 1)
1278 return errors.New("received unexpected chunk")
1280 c.decExpectedChunkReceive(req)
1282 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1283 chunksReceived.Add("due to allowed fast", 1)
1286 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1287 // have actually already received the piece, while we have the Client unlocked to write the data
1289 deletedRequest := false
1291 if c.actualRequestState.Requests.Contains(req) {
1292 for _, f := range c.callbacks.ReceivedRequested {
1293 f(PeerMessageEvent{c, msg})
1296 // Request has been satisfied.
1297 if c.deleteRequest(req) {
1298 deletedRequest = true
1300 c._chunksReceivedWhileExpecting++
1303 chunksReceived.Add("unwanted", 1)
1310 // Do we actually want this chunk?
1311 if t.haveChunk(ppReq) {
1312 chunksReceived.Add("wasted", 1)
1313 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1317 piece := &t.pieces[ppReq.Index]
1319 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1320 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1322 c.piecesReceivedSinceLastRequestUpdate++
1323 if c.actualRequestState.Requests.GetCardinality() == 0 {
1324 c.updateRequests("Peer.receiveChunk deleted request")
1326 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1328 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1329 f(ReceivedUsefulDataEvent{c, msg})
1331 c.lastUsefulChunkReceived = time.Now()
1333 // Need to record that it hasn't been written yet, before we attempt to do
1334 // anything with it.
1335 piece.incrementPendingWrites()
1336 // Record that we have the chunk, so we aren't trying to download it while
1337 // waiting for it to be written to storage.
1338 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1340 // Cancel pending requests for this chunk from *other* peers.
1341 t.iterPeers(func(p *Peer) {
1348 err := func() error {
1351 concurrentChunkWrites.Add(1)
1352 defer concurrentChunkWrites.Add(-1)
1353 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1354 // number of connections. We write inline with receiving the chunk (with this lock dance),
1355 // because we want to handle errors synchronously and I haven't thought of a nice way to
1356 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1358 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1361 piece.decrementPendingWrites()
1364 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1366 // Necessary to pass TestReceiveChunkStorageFailureSeederFastExtensionDisabled. I think a
1367 // request update runs while we're writing the chunk that just failed. Then we never do a
1368 // fresh update after pending the failed request.
1369 c.updateRequests("Peer.receiveChunk error writing chunk")
1370 t.onWriteChunkErr(err)
1374 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1376 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1377 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1378 t.queuePieceCheck(pieceIndex(ppReq.Index))
1379 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1380 // chunk status (such as the haveChunk call above) to have to check all the various other
1381 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1382 // that chunk pieces are pended at an appropriate time later however.
1385 cl.event.Broadcast()
1386 // We do this because we've written a chunk, and may change PieceState.Partial.
1387 t.publishPieceChange(pieceIndex(ppReq.Index))
1392 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1393 if c.peerTouchedPieces == nil {
1394 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1396 c.peerTouchedPieces[piece] = struct{}{}
1397 ds := &c.t.pieces[piece].dirtiers
1399 *ds = make(map[*Peer]struct{})
1401 (*ds)[c] = struct{}{}
1404 func (c *PeerConn) uploadAllowed() bool {
1405 if c.t.cl.config.NoUpload {
1408 if c.t.dataUploadDisallowed {
1414 if !c.peerHasWantedPieces() {
1417 // Don't upload more than 100 KiB more than we download.
1418 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1424 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1425 if c.uploadTimer == nil {
1426 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1428 c.uploadTimer.Reset(delay)
1432 // Also handles choking and unchoking of the remote peer.
1433 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1434 // Breaking or completing this loop means we don't want to upload to the
1435 // peer anymore, and we choke them.
1437 for c.uploadAllowed() {
1438 // We want to upload to the peer.
1439 if !c.unchoke(msg) {
1442 for r, state := range c.peerRequests {
1443 if state.data == nil {
1446 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1448 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1450 delay := res.Delay()
1453 c.setRetryUploadTimer(delay)
1454 // Hard to say what to return here.
1457 more := c.sendChunk(r, msg, state)
1458 delete(c.peerRequests, r)
1469 func (cn *PeerConn) drop() {
1470 cn.t.dropConnection(cn)
1473 func (cn *Peer) netGoodPiecesDirtied() int64 {
1474 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1477 func (c *Peer) peerHasWantedPieces() bool {
1478 if c.peerSentHaveAll {
1479 return !c.t.haveAllPieces()
1481 if !c.t.haveInfo() {
1482 return c._peerPieces.GetCardinality() != 0
1484 return c._peerPieces.Intersects(
1485 roaring.FlipInt(&c.t._completedPieces, 0, c.t.numPieces()),
1489 func (c *Peer) deleteRequest(r RequestIndex) bool {
1490 if !c.actualRequestState.Requests.CheckedRemove(r) {
1493 for _, f := range c.callbacks.DeletedRequest {
1494 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1496 c.updateExpectingChunks()
1497 if !c.peerChoking || c.peerAllowedFast.Contains(r/c.t.chunksPerRegularPiece()) {
1498 c.t.pendingRequests.Dec(r)
1503 func (c *Peer) deleteAllRequests() {
1504 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1508 if !c.actualRequestState.Requests.IsEmpty() {
1509 panic(c.actualRequestState.Requests.GetCardinality())
1511 // for c := range c.t.conns {
1516 // This is called when something has changed that should wake the writer, such as putting stuff into
1517 // the writeBuffer, or changing some state that the writer can act on.
1518 func (c *PeerConn) tickleWriter() {
1519 c.messageWriter.writeCond.Broadcast()
1522 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1523 c.lastChunkSent = time.Now()
1524 return msg(pp.Message{
1532 func (c *PeerConn) setTorrent(t *Torrent) {
1534 panic("connection already associated with a torrent")
1537 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1538 t.reconcileHandshakeStats(c)
1541 func (c *Peer) peerPriority() (peerPriority, error) {
1542 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1545 func (c *Peer) remoteIp() net.IP {
1546 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1547 return net.ParseIP(host)
1550 func (c *Peer) remoteIpPort() IpPort {
1551 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1552 return IpPort{ipa.IP, uint16(ipa.Port)}
1555 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1556 f := pp.PexPeerFlags(0)
1557 if c.PeerPrefersEncryption {
1558 f |= pp.PexPrefersEncryption
1561 f |= pp.PexOutgoingConn
1564 f |= pp.PexSupportsUtp
1569 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1570 // advertised listen port.
1571 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1572 if !c.outgoing && c.PeerListenPort != 0 {
1573 switch addr := c.RemoteAddr.(type) {
1576 dialAddr.Port = c.PeerListenPort
1580 dialAddr.Port = c.PeerListenPort
1587 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1588 f := c.pexPeerFlags()
1589 addr := c.dialAddr()
1590 return pexEvent{t, addr, f}
1593 func (c *PeerConn) String() string {
1594 return fmt.Sprintf("connection %p", c)
1597 func (c *Peer) trust() connectionTrust {
1598 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1601 type connectionTrust struct {
1603 NetGoodPiecesDirted int64
1606 func (l connectionTrust) Less(r connectionTrust) bool {
1607 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1610 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1611 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1612 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1614 defer cn.locker().RUnlock()
1615 return cn.newPeerPieces()
1618 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1619 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1620 // TODO: Can we use copy on write?
1621 ret := cn._peerPieces.Clone()
1622 if cn.peerSentHaveAll {
1623 if cn.t.haveInfo() {
1624 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1626 ret.AddRange(0, bitmap.ToEnd)
1632 func (cn *Peer) stats() *ConnStats {
1636 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1637 pc, ok := p.peerImpl.(*PeerConn)
1641 func (p *PeerConn) onNextRequestStateChanged() {