16 "github.com/anacrolix/log"
17 "github.com/anacrolix/missinggo"
18 "github.com/anacrolix/missinggo/iter"
19 "github.com/anacrolix/missinggo/v2/bitmap"
20 "github.com/anacrolix/missinggo/v2/prioritybitmap"
21 "github.com/anacrolix/multiless"
22 "github.com/anacrolix/torrent/metainfo"
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 if cn.closed.IsSet() {
316 fmt.Fprint(w, "CLOSED: ")
318 fmt.Fprintln(w, cn.connStatusString())
319 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
320 eventAgeString(cn.lastMessageReceived),
321 eventAgeString(cn.completedHandshake),
322 eventAgeString(cn.lastHelpful()),
324 cn.totalExpectingTime(),
327 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: (%d,%d,%d]-%d, flags: %s, dr: %.1f KiB/s\n",
328 cn.completedString(),
329 len(cn.peerTouchedPieces),
330 &cn._stats.ChunksReadUseful,
331 &cn._stats.ChunksRead,
332 &cn._stats.ChunksWritten,
334 cn.numLocalRequests(),
335 cn.nominalMaxRequests(),
336 len(cn.peerRequests),
338 cn.downloadRate()/(1<<10),
340 //fmt.Fprintf(w, " next pieces: %v%s\n",
341 // iter.ToSlice(iter.Head(10, cn.iterPendingPiecesUntyped)),
343 // if cn == t.fastestPeer {
344 // return " (fastest)"
352 func (cn *Peer) close() {
353 if !cn.closed.Set() {
356 cn.discardPieceInclination()
357 cn._pieceRequestOrder.Clear()
358 cn.peerImpl.onClose()
359 for _, f := range cn.callbacks.PeerClosed {
364 func (cn *PeerConn) onClose() {
365 if cn.pex.IsEnabled() {
372 if cb := cn.callbacks.PeerConnClosed; cb != nil {
377 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
378 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
381 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
382 // https://github.com/pion/datachannel/issues/59 is fixed.
383 const writeBufferHighWaterLen = 1 << 15
385 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Posting is
386 // done asynchronously, so it may be that we're not able to honour backpressure from this method. It
387 // might be possible to merge this with PeerConn.write down the track? They seem to be very similar.
388 func (cn *PeerConn) post(msg pp.Message) bool {
389 torrent.Add(fmt.Sprintf("messages posted of type %s", msg.Type.String()), 1)
390 // We don't need to track bytes here because a connection.w Writer wrapper takes care of that
391 // (although there's some delay between us recording the message, and the connection writer
392 // flushing it out.).
393 cn.writeBuffer.Write(msg.MustMarshalBinary())
394 // Last I checked only Piece messages affect stats, and we don't post those.
397 return cn.writeBuffer.Len() < writeBufferHighWaterLen
400 // Returns true if there's room to write more.
401 func (cn *PeerConn) write(msg pp.Message) bool {
403 cn.writeBuffer.Write(msg.MustMarshalBinary())
404 torrent.Add(fmt.Sprintf("messages filled of type %s", msg.Type.String()), 1)
406 return !cn.writeBufferFull()
409 func (cn *PeerConn) writeBufferFull() bool {
410 return cn.writeBuffer.Len() >= writeBufferHighWaterLen
413 func (cn *PeerConn) requestMetadataPiece(index int) {
414 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
418 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
421 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
425 ExtendedPayload: func() []byte {
426 b, err := bencode.Marshal(map[string]int{
427 "msg_type": pp.RequestMetadataExtensionMsgType,
436 for index >= len(cn.metadataRequests) {
437 cn.metadataRequests = append(cn.metadataRequests, false)
439 cn.metadataRequests[index] = true
442 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
443 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
446 // The actual value to use as the maximum outbound requests.
447 func (cn *Peer) nominalMaxRequests() (ret int) {
448 return cn.PeerMaxRequests
451 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
452 ret = cn.cumulativeExpectedToReceiveChunks
453 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
454 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
460 func (cn *PeerConn) onPeerSentCancel(r Request) {
461 if _, ok := cn.peerRequests[r]; !ok {
462 torrent.Add("unexpected cancels received", 1)
465 if cn.fastEnabled() {
468 delete(cn.peerRequests, r)
472 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
477 more = msg(pp.Message{
480 if cn.fastEnabled() {
481 for r := range cn.peerRequests {
482 // TODO: Don't reject pieces in allowed fast set.
486 cn.peerRequests = nil
491 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
496 return msg(pp.Message{
501 func (cn *Peer) setInterested(interested bool) bool {
502 if cn.interested == interested {
505 cn.interested = interested
507 cn.lastBecameInterested = time.Now()
508 } else if !cn.lastBecameInterested.IsZero() {
509 cn.priorInterest += time.Since(cn.lastBecameInterested)
511 cn.updateExpectingChunks()
512 // log.Printf("%p: setting interest: %v", cn, interested)
513 return cn.writeInterested(interested)
516 func (pc *PeerConn) writeInterested(interested bool) bool {
517 return pc.write(pp.Message{
518 Type: func() pp.MessageType {
522 return pp.NotInterested
528 // The function takes a message to be sent, and returns true if more messages
530 type messageWriter func(pp.Message) bool
532 func (cn *Peer) request(r Request) (more bool, err error) {
533 if _, ok := cn.requests[r]; ok {
536 if !cn.peerHasPiece(pieceIndex(r.Index)) {
537 return true, errors.New("requesting piece peer doesn't have")
539 if !cn.t.peerIsActive(cn) {
540 panic("requesting but not in active conns")
542 if cn.closed.IsSet() {
543 panic("requesting when connection is closed")
546 if cn.peerAllowedFast.Get(int(r.Index)) {
547 torrent.Add("allowed fast requests sent", 1)
549 return cn.setInterested(true), errors.New("requesting while choked and not allowed fast")
552 if cn.t.hashingPiece(pieceIndex(r.Index)) {
553 panic("piece is being hashed")
555 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
556 panic("piece is queued for hash")
558 if cn.requests == nil {
559 cn.requests = make(map[Request]struct{})
561 cn.requests[r] = struct{}{}
562 if cn.validReceiveChunks == nil {
563 cn.validReceiveChunks = make(map[Request]int)
565 cn.validReceiveChunks[r]++
566 cn.t.pendingRequests[r]++
567 cn.updateExpectingChunks()
568 for _, f := range cn.callbacks.SentRequest {
569 f(PeerRequestEvent{cn, r})
571 return cn.peerImpl.request(r), nil
574 func (me *PeerConn) request(r Request) bool {
575 return me.write(pp.Message{
583 func (me *PeerConn) cancel(r Request) bool {
584 return me.write(makeCancelMessage(r))
587 func (cn *PeerConn) fillWriteBuffer() {
588 if cn.pex.IsEnabled() {
589 if flow := cn.pex.Share(cn.write); !flow {
596 // Routine that writes to the peer. Some of what to write is buffered by
597 // activity elsewhere in the Client, and some is determined locally when the
598 // connection is writable.
599 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
601 lastWrite time.Time = time.Now()
602 keepAliveTimer *time.Timer
604 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
606 defer cn.locker().Unlock()
607 if time.Since(lastWrite) >= keepAliveTimeout {
610 keepAliveTimer.Reset(keepAliveTimeout)
613 defer cn.locker().Unlock()
615 defer keepAliveTimer.Stop()
616 frontBuf := new(bytes.Buffer)
618 if cn.closed.IsSet() {
621 if cn.writeBuffer.Len() == 0 {
624 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.useful() {
625 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
626 torrent.Add("written keepalives", 1)
628 if cn.writeBuffer.Len() == 0 {
629 // TODO: Minimize wakeups....
634 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
636 n, err := cn.w.Write(frontBuf.Bytes())
639 lastWrite = time.Now()
640 keepAliveTimer.Reset(keepAliveTimeout)
643 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
646 if n != frontBuf.Len() {
653 func (cn *PeerConn) have(piece pieceIndex) {
654 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
659 Index: pp.Integer(piece),
661 cn.sentHaves.Add(bitmap.BitIndex(piece))
664 func (cn *PeerConn) postBitfield() {
665 if cn.sentHaves.Len() != 0 {
666 panic("bitfield must be first have-related message sent")
668 if !cn.t.haveAnyPieces() {
673 Bitfield: cn.t.bitfield(),
675 cn.sentHaves = cn.t._completedPieces.Copy()
678 func (cn *PeerConn) updateRequests() {
679 // log.Print("update requests")
683 // Emits the indices in the Bitmaps bms in order, never repeating any index.
684 // skip is mutated during execution, and its initial values will never be
686 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
687 return func(cb iter.Callback) {
688 for _, bm := range bms {
690 func(_i interface{}) bool {
692 if skip.Contains(i) {
706 // check callers updaterequests
707 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
708 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
711 // This is distinct from Torrent piece priority, which is the user's
712 // preference. Connection piece priority is specific to a connection and is
713 // used to pseudorandomly avoid connections always requesting the same pieces
714 // and thus wasting effort.
715 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
716 tpp := cn.t.piecePriority(piece)
717 if !cn.peerHasPiece(piece) {
718 tpp = PiecePriorityNone
720 if tpp == PiecePriorityNone {
721 return cn.stopRequestingPiece(piece)
723 prio := cn.getPieceInclination()[piece]
724 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio)
727 func (cn *Peer) getPieceInclination() []int {
728 if cn.pieceInclination == nil {
729 cn.pieceInclination = cn.t.getConnPieceInclination()
731 return cn.pieceInclination
734 func (cn *Peer) discardPieceInclination() {
735 if cn.pieceInclination == nil {
738 cn.t.putPieceInclination(cn.pieceInclination)
739 cn.pieceInclination = nil
742 func (cn *PeerConn) peerPiecesChanged() {
744 prioritiesChanged := false
745 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
746 if cn.updatePiecePriority(i) {
747 prioritiesChanged = true
750 if prioritiesChanged {
754 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
757 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
758 if newMin > cn.peerMinPieces {
759 cn.peerMinPieces = newMin
763 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
764 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
765 return errors.New("invalid piece")
767 if cn.peerHasPiece(piece) {
770 cn.raisePeerMinPieces(piece + 1)
771 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
772 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
773 if cn.updatePiecePriority(piece) {
779 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
780 cn.peerSentHaveAll = false
782 panic("expected bitfield length divisible by 8")
784 // We know that the last byte means that at most the last 7 bits are
786 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
787 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
788 // Ignore known excess pieces.
789 bf = bf[:cn.t.numPieces()]
791 for i, have := range bf {
793 cn.raisePeerMinPieces(pieceIndex(i) + 1)
795 cn._peerPieces.Set(i, have)
797 cn.peerPiecesChanged()
801 func (cn *PeerConn) onPeerSentHaveAll() error {
802 cn.peerSentHaveAll = true
803 cn._peerPieces.Clear()
804 cn.peerPiecesChanged()
808 func (cn *PeerConn) peerSentHaveNone() error {
809 cn._peerPieces.Clear()
810 cn.peerSentHaveAll = false
811 cn.peerPiecesChanged()
815 func (c *PeerConn) requestPendingMetadata() {
819 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
820 // Peer doesn't support this.
823 // Request metadata pieces that we don't have in a random order.
825 for index := 0; index < c.t.metadataPieceCount(); index++ {
826 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
827 pending = append(pending, index)
830 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
831 for _, i := range pending {
832 c.requestMetadataPiece(i)
836 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
837 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
838 if msg.Type == pp.Extended {
839 for name, id := range cn.PeerExtensionIDs {
840 if id != msg.ExtendedID {
843 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
846 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
849 func (cn *PeerConn) readMsg(msg *pp.Message) {
850 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
853 // After handshake, we know what Torrent and Client stats to include for a
855 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
861 // All ConnStats that include this connection. Some objects are not known
862 // until the handshake is complete, after which it's expected to reconcile the
864 func (cn *Peer) allStats(f func(*ConnStats)) {
866 if cn.reconciledHandshakeStats {
867 cn.postHandshakeStats(f)
871 func (cn *PeerConn) wroteBytes(n int64) {
872 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
875 func (cn *PeerConn) readBytes(n int64) {
876 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
879 // Returns whether the connection could be useful to us. We're seeding and
880 // they want data, we don't have metainfo and they can provide it, etc.
881 func (c *Peer) useful() bool {
883 if c.closed.IsSet() {
887 return c.supportsExtension("ut_metadata")
889 if t.seeding() && c.peerInterested {
892 if c.peerHasWantedPieces() {
898 func (c *Peer) lastHelpful() (ret time.Time) {
899 ret = c.lastUsefulChunkReceived
900 if c.t.seeding() && c.lastChunkSent.After(ret) {
901 ret = c.lastChunkSent
906 func (c *PeerConn) fastEnabled() bool {
907 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
910 func (c *PeerConn) reject(r Request) {
911 if !c.fastEnabled() {
912 panic("fast not enabled")
914 c.post(r.ToMsg(pp.Reject))
915 delete(c.peerRequests, r)
918 func (c *PeerConn) onReadRequest(r Request) error {
919 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
920 if _, ok := c.peerRequests[r]; ok {
921 torrent.Add("duplicate requests received", 1)
925 torrent.Add("requests received while choking", 1)
927 torrent.Add("requests rejected while choking", 1)
932 if len(c.peerRequests) >= maxRequests {
933 torrent.Add("requests received while queue full", 1)
937 // BEP 6 says we may close here if we choose.
940 if !c.t.havePiece(pieceIndex(r.Index)) {
941 // This isn't necessarily them screwing up. We can drop pieces
942 // from our storage, and can't communicate this to peers
943 // except by reconnecting.
944 requestsReceivedForMissingPieces.Add(1)
945 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
947 // Check this after we know we have the piece, so that the piece length will be known.
948 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
949 torrent.Add("bad requests received", 1)
950 return errors.New("bad Request")
952 if c.peerRequests == nil {
953 c.peerRequests = make(map[Request]*peerRequestState, maxRequests)
955 value := &peerRequestState{}
956 c.peerRequests[r] = value
957 go c.peerRequestDataReader(r, value)
962 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
963 b, err := readPeerRequestData(r, c)
965 defer c.locker().Unlock()
967 c.peerRequestDataReadFailed(err, r)
970 panic("data must be non-nil to trigger send")
977 // If this is maintained correctly, we might be able to support optional synchronous reading for
978 // chunk sending, the way it used to work.
979 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
980 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
981 i := pieceIndex(r.Index)
982 if c.t.pieceComplete(i) {
983 // There used to be more code here that just duplicated the following break. Piece
984 // completions are currently cached, so I'm not sure how helpful this update is, except to
985 // pull any completion changes pushed to the storage backend in failed reads that got us
987 c.t.updatePieceCompletion(i)
989 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
990 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
991 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
992 // next connect. TODO: Support rejecting here too.
994 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
999 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1000 b := make([]byte, r.Length)
1001 p := c.t.info.Piece(int(r.Index))
1002 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1009 panic("expected error")
1015 func runSafeExtraneous(f func()) {
1023 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1024 // exit. Returning will end the connection.
1025 func (c *PeerConn) mainReadLoop() (err error) {
1028 torrent.Add("connection.mainReadLoop returned with error", 1)
1030 torrent.Add("connection.mainReadLoop returned with no error", 1)
1036 decoder := pp.Decoder{
1037 R: bufio.NewReaderSize(c.r, 1<<17),
1038 MaxLength: 256 * 1024,
1046 err = decoder.Decode(&msg)
1048 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1051 if t.closed.IsSet() || c.closed.IsSet() {
1058 c.lastMessageReceived = time.Now()
1060 receivedKeepalives.Add(1)
1063 messageTypesReceived.Add(msg.Type.String(), 1)
1064 if msg.Type.FastExtension() && !c.fastEnabled() {
1065 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1066 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1070 c.peerChoking = true
1071 if !c.fastEnabled() {
1072 c.deleteAllRequests()
1074 // We can then reset our interest.
1076 c.updateExpectingChunks()
1078 c.peerChoking = false
1080 c.updateExpectingChunks()
1082 c.peerInterested = true
1084 case pp.NotInterested:
1085 c.peerInterested = false
1086 // We don't clear their requests since it isn't clear in the spec.
1087 // We'll probably choke them for this, which will clear them if
1088 // appropriate, and is clearly specified.
1090 err = c.peerSentHave(pieceIndex(msg.Index))
1092 err = c.peerSentBitfield(msg.Bitfield)
1094 r := newRequestFromMessage(&msg)
1095 err = c.onReadRequest(r)
1097 err = c.receiveChunk(&msg)
1098 if len(msg.Piece) == int(t.chunkSize) {
1099 t.chunkPool.Put(&msg.Piece)
1102 err = fmt.Errorf("receiving chunk: %s", err)
1105 req := newRequestFromMessage(&msg)
1106 c.onPeerSentCancel(req)
1108 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1112 pingAddr := net.UDPAddr{
1117 pingAddr.Port = int(msg.Port)
1119 cl.eachDhtServer(func(s DhtServer) {
1120 go s.Ping(&pingAddr)
1123 torrent.Add("suggests received", 1)
1124 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1127 err = c.onPeerSentHaveAll()
1129 err = c.peerSentHaveNone()
1131 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1132 case pp.AllowedFast:
1133 torrent.Add("allowed fasts received", 1)
1134 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1135 c.peerAllowedFast.Add(int(msg.Index))
1138 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1140 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1148 func (c *Peer) remoteRejectedRequest(r Request) {
1149 if c.deleteRequest(r) {
1150 c.decExpectedChunkReceive(r)
1154 func (c *Peer) decExpectedChunkReceive(r Request) {
1155 count := c.validReceiveChunks[r]
1157 delete(c.validReceiveChunks, r)
1158 } else if count > 1 {
1159 c.validReceiveChunks[r] = count - 1
1165 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1167 // TODO: Should we still do this?
1169 // These clients use their own extension IDs for outgoing message
1170 // types, which is incorrect.
1171 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1179 case pp.HandshakeExtendedID:
1180 var d pp.ExtendedHandshakeMessage
1181 if err := bencode.Unmarshal(payload, &d); err != nil {
1182 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1183 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1185 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1188 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1190 c.PeerMaxRequests = d.Reqq
1192 c.PeerClientName = d.V
1193 if c.PeerExtensionIDs == nil {
1194 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1196 c.PeerListenPort = d.Port
1197 c.PeerPrefersEncryption = d.Encryption
1198 for name, id := range d.M {
1199 if _, ok := c.PeerExtensionIDs[name]; !ok {
1200 peersSupportingExtension.Add(string(name), 1)
1202 c.PeerExtensionIDs[name] = id
1204 if d.MetadataSize != 0 {
1205 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1206 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1209 c.requestPendingMetadata()
1210 if !t.cl.config.DisablePEX {
1211 t.pex.Add(c) // we learnt enough now
1215 case metadataExtendedId:
1216 err := cl.gotMetadataExtensionMsg(payload, t, c)
1218 return fmt.Errorf("handling metadata extension message: %w", err)
1222 if !c.pex.IsEnabled() {
1223 return nil // or hang-up maybe?
1225 return c.pex.Recv(payload)
1227 return fmt.Errorf("unexpected extended message ID: %v", id)
1231 // Set both the Reader and Writer for the connection from a single ReadWriter.
1232 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1237 // Returns the Reader and Writer as a combined ReadWriter.
1238 func (cn *PeerConn) rw() io.ReadWriter {
1245 // Handle a received chunk from a peer.
1246 func (c *Peer) receiveChunk(msg *pp.Message) error {
1249 chunksReceived.Add("total", 1)
1251 req := newRequestFromMessage(msg)
1254 chunksReceived.Add("while choked", 1)
1257 if c.validReceiveChunks[req] <= 0 {
1258 chunksReceived.Add("unexpected", 1)
1259 return errors.New("received unexpected chunk")
1261 c.decExpectedChunkReceive(req)
1263 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1264 chunksReceived.Add("due to allowed fast", 1)
1267 // TODO: This needs to happen immediately, to prevent cancels occurring asynchronously when have
1268 // actually already received the piece, while we have the Client unlocked to write the data out.
1270 if _, ok := c.requests[req]; ok {
1271 for _, f := range c.callbacks.ReceivedRequested {
1272 f(PeerMessageEvent{c, msg})
1275 // Request has been satisfied.
1276 if c.deleteRequest(req) {
1277 if c.expectingChunks() {
1278 c._chunksReceivedWhileExpecting++
1281 chunksReceived.Add("unwanted", 1)
1285 // Do we actually want this chunk?
1286 if t.haveChunk(req) {
1287 chunksReceived.Add("wasted", 1)
1288 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1292 piece := &t.pieces[req.Index]
1294 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1295 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1296 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1297 f(ReceivedUsefulDataEvent{c, msg})
1299 c.lastUsefulChunkReceived = time.Now()
1300 // if t.fastestPeer != c {
1301 // log.Printf("setting fastest connection %p", c)
1305 // Need to record that it hasn't been written yet, before we attempt to do
1306 // anything with it.
1307 piece.incrementPendingWrites()
1308 // Record that we have the chunk, so we aren't trying to download it while
1309 // waiting for it to be written to storage.
1310 piece.unpendChunkIndex(chunkIndex(req.ChunkSpec, t.chunkSize))
1312 // Cancel pending requests for this chunk from *other* peers.
1313 t.iterPeers(func(p *Peer) {
1320 err := func() error {
1323 concurrentChunkWrites.Add(1)
1324 defer concurrentChunkWrites.Add(-1)
1325 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1326 // number of connections. We write inline with receiving the chunk (with this lock dance),
1327 // because we want to handle errors synchronously and I haven't thought of a nice way to
1328 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1330 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1333 piece.decrementPendingWrites()
1336 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1338 //t.updatePieceCompletion(pieceIndex(msg.Index))
1339 t.onWriteChunkErr(err)
1343 c.onDirtiedPiece(pieceIndex(req.Index))
1345 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1346 if t.pieceAllDirty(pieceIndex(req.Index)) && piece.pendingWrites == 0 {
1347 t.queuePieceCheck(pieceIndex(req.Index))
1348 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1349 // chunk status (such as the haveChunk call above) to have to check all the various other
1350 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1351 // that chunk pieces are pended at an appropriate time later however.
1354 cl.event.Broadcast()
1355 // We do this because we've written a chunk, and may change PieceState.Partial.
1356 t.publishPieceChange(pieceIndex(req.Index))
1361 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1362 if c.peerTouchedPieces == nil {
1363 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1365 c.peerTouchedPieces[piece] = struct{}{}
1366 ds := &c.t.pieces[piece].dirtiers
1368 *ds = make(map[*Peer]struct{})
1370 (*ds)[c] = struct{}{}
1373 func (c *PeerConn) uploadAllowed() bool {
1374 if c.t.cl.config.NoUpload {
1377 if c.t.dataUploadDisallowed {
1383 if !c.peerHasWantedPieces() {
1386 // Don't upload more than 100 KiB more than we download.
1387 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1393 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1394 if c.uploadTimer == nil {
1395 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1397 c.uploadTimer.Reset(delay)
1401 // Also handles choking and unchoking of the remote peer.
1402 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1403 // Breaking or completing this loop means we don't want to upload to the
1404 // peer anymore, and we choke them.
1406 for c.uploadAllowed() {
1407 // We want to upload to the peer.
1408 if !c.unchoke(msg) {
1411 for r, state := range c.peerRequests {
1412 if state.data == nil {
1415 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1417 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1419 delay := res.Delay()
1422 c.setRetryUploadTimer(delay)
1423 // Hard to say what to return here.
1426 more := c.sendChunk(r, msg, state)
1427 delete(c.peerRequests, r)
1438 func (cn *PeerConn) drop() {
1439 cn.t.dropConnection(cn)
1442 func (cn *Peer) netGoodPiecesDirtied() int64 {
1443 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1446 func (c *Peer) peerHasWantedPieces() bool {
1447 return !c._pieceRequestOrder.IsEmpty()
1450 func (c *Peer) numLocalRequests() int {
1451 return len(c.requests)
1454 func (c *Peer) deleteRequest(r Request) bool {
1455 if _, ok := c.requests[r]; !ok {
1458 delete(c.requests, r)
1459 for _, f := range c.callbacks.DeletedRequest {
1460 f(PeerRequestEvent{c, r})
1462 c.updateExpectingChunks()
1463 pr := c.t.pendingRequests
1472 // If a request fails, updating the requests for the current peer first may miss the opportunity
1473 // to try other peers for that request instead, depending on the request strategy. This might
1474 // only affect webseed peers though, since they synchronously issue new requests: PeerConns do
1475 // it in the writer routine.
1476 const updateCurrentConnRequestsFirst = false
1477 if updateCurrentConnRequestsFirst {
1480 // Give other conns a chance to pick up the request.
1481 c.t.iterPeers(func(_c *Peer) {
1482 // We previously checked that the peer wasn't interested to to only wake connections that
1483 // were unable to issue requests due to starvation by the request strategy. There could be
1484 // performance ramifications.
1485 if _c != c && c.peerHasPiece(pieceIndex(r.Index)) {
1489 if !updateCurrentConnRequestsFirst {
1495 func (c *Peer) deleteAllRequests() {
1496 for r := range c.requests {
1499 if len(c.requests) != 0 {
1500 panic(len(c.requests))
1502 // for c := range c.t.conns {
1507 // This is called when something has changed that should wake the writer, such as putting stuff into
1508 // the writeBuffer, or changing some state that the writer can act on.
1509 func (c *PeerConn) tickleWriter() {
1510 c.writerCond.Broadcast()
1513 func (c *Peer) postCancel(r Request) bool {
1514 if !c.deleteRequest(r) {
1517 c.peerImpl._postCancel(r)
1521 func (c *PeerConn) _postCancel(r Request) {
1522 c.post(makeCancelMessage(r))
1525 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1526 c.lastChunkSent = time.Now()
1527 return msg(pp.Message{
1535 func (c *PeerConn) setTorrent(t *Torrent) {
1537 panic("connection already associated with a torrent")
1540 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1541 t.reconcileHandshakeStats(c)
1544 func (c *Peer) peerPriority() (peerPriority, error) {
1545 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1548 func (c *Peer) remoteIp() net.IP {
1549 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1550 return net.ParseIP(host)
1553 func (c *Peer) remoteIpPort() IpPort {
1554 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1555 return IpPort{ipa.IP, uint16(ipa.Port)}
1558 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1559 f := pp.PexPeerFlags(0)
1560 if c.PeerPrefersEncryption {
1561 f |= pp.PexPrefersEncryption
1564 f |= pp.PexOutgoingConn
1567 f |= pp.PexSupportsUtp
1572 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1573 // advertised listen port.
1574 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1575 if !c.outgoing && c.PeerListenPort != 0 {
1576 switch addr := c.RemoteAddr.(type) {
1579 dialAddr.Port = c.PeerListenPort
1583 dialAddr.Port = c.PeerListenPort
1590 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1591 f := c.pexPeerFlags()
1592 addr := c.dialAddr()
1593 return pexEvent{t, addr, f}
1596 func (c *PeerConn) String() string {
1597 return fmt.Sprintf("connection %p", c)
1600 func (c *Peer) trust() connectionTrust {
1601 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1604 type connectionTrust struct {
1606 NetGoodPiecesDirted int64
1609 func (l connectionTrust) Less(r connectionTrust) bool {
1610 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1613 func (cn *Peer) chunksReceivedWhileExpecting() int64 {
1614 return cn._chunksReceivedWhileExpecting
1617 func (cn *Peer) fastest() bool {
1618 return cn == cn.t.fastestPeer
1621 func (cn *Peer) peerMaxRequests() int {
1622 return cn.PeerMaxRequests
1625 // Returns the pieces the peer has claimed to have.
1626 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1628 defer cn.locker().RUnlock()
1629 return cn.peerPieces()
1632 func (cn *Peer) peerPieces() bitmap.Bitmap {
1633 ret := cn._peerPieces.Copy()
1634 if cn.peerSentHaveAll {
1635 ret.AddRange(0, cn.t.numPieces())
1640 func (cn *Peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1641 return &cn._pieceRequestOrder
1644 func (cn *Peer) stats() *ConnStats {
1648 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1649 pc, ok := p.peerImpl.(*PeerConn)