17 "github.com/RoaringBitmap/roaring"
18 . "github.com/anacrolix/generics"
19 "github.com/anacrolix/log"
20 "github.com/anacrolix/missinggo/v2/bitmap"
21 "github.com/anacrolix/multiless"
22 "golang.org/x/time/rate"
24 "github.com/anacrolix/torrent/bencode"
25 "github.com/anacrolix/torrent/internal/alloclim"
26 "github.com/anacrolix/torrent/metainfo"
27 "github.com/anacrolix/torrent/mse"
28 pp "github.com/anacrolix/torrent/peer_protocol"
29 utHolepunch "github.com/anacrolix/torrent/peer_protocol/ut-holepunch"
32 // Maintains the state of a BitTorrent-protocol based connection with a peer.
33 type PeerConn struct {
36 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
37 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
42 PeerExtensionBytes pp.PeerExtensionBits
44 // The actual Conn, used for closing, and setting socket options. Do not use methods on this
45 // while holding any mutexes.
47 // The Reader and Writer for this Conn, with hooks installed for stats,
48 // limiting, deadlines etc.
52 messageWriter peerConnMsgWriter
54 uploadTimer *time.Timer
57 // The pieces the peer has claimed to have.
58 _peerPieces roaring.Bitmap
59 // The peer has everything. This can occur due to a special message, when
60 // we may not even know the number of pieces in the torrent yet.
63 peerRequestDataAllocLimiter alloclim.Limiter
65 outstandingHolepunchingRendezvous map[netip.AddrPort]struct{}
68 func (cn *PeerConn) pexStatus() string {
69 if !cn.bitExtensionEnabled(pp.ExtensionBitExtended) {
70 return "extended protocol disabled"
72 if cn.PeerExtensionIDs == nil {
73 return "pending extended handshake"
75 if !cn.supportsExtension(pp.ExtensionNamePex) {
79 "%v conns, %v unsent events",
80 len(cn.pex.remoteLiveConns),
85 func (cn *PeerConn) peerImplStatusLines() []string {
88 fmt.Sprintf("peer id: %+q", cn.PeerID),
89 fmt.Sprintf("extensions: %v", cn.PeerExtensionBytes),
90 fmt.Sprintf("pex: %s", cn.pexStatus()),
94 // Returns true if the connection is over IPv6.
95 func (cn *PeerConn) ipv6() bool {
100 return len(ip) == net.IPv6len
103 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
104 // specification for this.
105 func (cn *PeerConn) isPreferredDirection() bool {
106 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
109 // Returns whether the left connection should be preferred over the right one,
110 // considering only their networking properties. If ok is false, we can't
112 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) bool {
113 var ml multiless.Computation
114 ml = ml.Bool(r.isPreferredDirection(), l.isPreferredDirection())
115 ml = ml.Bool(l.utp(), r.utp())
116 ml = ml.Bool(r.ipv6(), l.ipv6())
120 func (cn *PeerConn) peerHasAllPieces() (all, known bool) {
121 if cn.peerSentHaveAll {
124 if !cn.t.haveInfo() {
127 return cn._peerPieces.GetCardinality() == uint64(cn.t.numPieces()), true
130 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
131 cn.setNumPieces(info.NumPieces())
134 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
135 // receiving badly sized BITFIELD, or invalid HAVE messages.
136 func (cn *PeerConn) setNumPieces(num pieceIndex) {
137 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
138 cn.peerPiecesChanged()
141 func (cn *PeerConn) peerPieces() *roaring.Bitmap {
142 return &cn._peerPieces
145 func (cn *PeerConn) connectionFlags() (ret string) {
147 ret += string([]byte{b})
149 if cn.cryptoMethod == mse.CryptoMethodRC4 {
151 } else if cn.headerEncrypted {
154 ret += string(cn.Discovery)
161 func (cn *PeerConn) utp() bool {
162 return parseNetworkString(cn.Network).Udp
165 func (cn *PeerConn) onClose() {
166 if cn.pex.IsEnabled() {
173 if cb := cn.callbacks.PeerConnClosed; cb != nil {
178 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
179 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
180 func (cn *PeerConn) write(msg pp.Message) bool {
181 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
182 // We don't need to track bytes here because the connection's Writer has that behaviour injected
183 // (although there's some delay between us buffering the message, and the connection writer
184 // flushing it out.).
185 notFull := cn.messageWriter.write(msg)
186 // Last I checked only Piece messages affect stats, and we don't write those.
192 func (cn *PeerConn) requestMetadataPiece(index int) {
193 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
194 if eID == pp.ExtensionDeleteNumber {
197 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
200 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
201 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
202 for index >= len(cn.metadataRequests) {
203 cn.metadataRequests = append(cn.metadataRequests, false)
205 cn.metadataRequests[index] = true
208 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
209 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
212 func (cn *PeerConn) onPeerSentCancel(r Request) {
213 if _, ok := cn.peerRequests[r]; !ok {
214 torrent.Add("unexpected cancels received", 1)
217 if cn.fastEnabled() {
220 delete(cn.peerRequests, r)
224 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
229 more = msg(pp.Message{
232 if !cn.fastEnabled() {
233 cn.deleteAllPeerRequests()
238 func (cn *PeerConn) deleteAllPeerRequests() {
239 for _, state := range cn.peerRequests {
240 state.allocReservation.Drop()
242 cn.peerRequests = nil
245 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
250 return msg(pp.Message{
255 func (pc *PeerConn) writeInterested(interested bool) bool {
256 return pc.write(pp.Message{
257 Type: func() pp.MessageType {
261 return pp.NotInterested
267 func (me *PeerConn) _request(r Request) bool {
268 return me.write(pp.Message{
276 func (me *PeerConn) _cancel(r RequestIndex) bool {
277 me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
278 // Transmission does not send rejects for received cancels. See
279 // https://github.com/transmission/transmission/pull/2275.
280 return me.fastEnabled() && !me.remoteIsTransmission()
283 func (cn *PeerConn) fillWriteBuffer() {
284 if cn.messageWriter.writeBuffer.Len() > writeBufferLowWaterLen {
285 // Fully committing to our max requests requires sufficient space (see
286 // maxLocalToRemoteRequests). Flush what we have instead. We also prefer always to make
287 // requests than to do PEX or upload, so we short-circuit before handling those. Any update
288 // request reason will not be cleared, so we'll come right back here when there's space. We
289 // can't do this in maybeUpdateActualRequestState because it's a method on Peer and has no
290 // knowledge of write buffers.
292 cn.maybeUpdateActualRequestState()
293 if cn.pex.IsEnabled() {
294 if flow := cn.pex.Share(cn.write); !flow {
301 func (cn *PeerConn) have(piece pieceIndex) {
302 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
307 Index: pp.Integer(piece),
309 cn.sentHaves.Add(bitmap.BitIndex(piece))
312 func (cn *PeerConn) postBitfield() {
313 if cn.sentHaves.Len() != 0 {
314 panic("bitfield must be first have-related message sent")
316 if !cn.t.haveAnyPieces() {
321 Bitfield: cn.t.bitfield(),
323 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
326 func (cn *PeerConn) handleUpdateRequests() {
327 // The writer determines the request state as needed when it can write.
331 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
332 if newMin > cn.peerMinPieces {
333 cn.peerMinPieces = newMin
337 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
338 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
339 return errors.New("invalid piece")
341 if cn.peerHasPiece(piece) {
344 cn.raisePeerMinPieces(piece + 1)
345 if !cn.peerHasPiece(piece) {
346 cn.t.incPieceAvailability(piece)
348 cn._peerPieces.Add(uint32(piece))
349 if cn.t.wantPieceIndex(piece) {
350 cn.updateRequests("have")
352 cn.peerPiecesChanged()
356 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
358 panic("expected bitfield length divisible by 8")
360 // We know that the last byte means that at most the last 7 bits are wasted.
361 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
362 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
363 // Ignore known excess pieces.
364 bf = bf[:cn.t.numPieces()]
366 bm := boolSliceToBitmap(bf)
367 if cn.t.haveInfo() && pieceIndex(bm.GetCardinality()) == cn.t.numPieces() {
368 cn.onPeerHasAllPieces()
372 cn.raisePeerMinPieces(pieceIndex(bm.Maximum()) + 1)
374 shouldUpdateRequests := false
375 if cn.peerSentHaveAll {
376 if !cn.t.deleteConnWithAllPieces(&cn.Peer) {
379 cn.peerSentHaveAll = false
380 if !cn._peerPieces.IsEmpty() {
381 panic("if peer has all, we expect no individual peer pieces to be set")
384 bm.Xor(&cn._peerPieces)
386 cn.peerSentHaveAll = false
387 // bm is now 'on' for pieces that are changing
388 bm.Iterate(func(x uint32) bool {
390 if cn._peerPieces.Contains(x) {
391 // Then we must be losing this piece
392 cn.t.decPieceAvailability(pi)
394 if !shouldUpdateRequests && cn.t.wantPieceIndex(pieceIndex(x)) {
395 shouldUpdateRequests = true
397 // We must be gaining this piece
398 cn.t.incPieceAvailability(pieceIndex(x))
402 // Apply the changes. If we had everything previously, this should be empty, so xor is the same
404 cn._peerPieces.Xor(&bm)
405 if shouldUpdateRequests {
406 cn.updateRequests("bitfield")
408 // We didn't guard this before, I see no reason to do it now.
409 cn.peerPiecesChanged()
413 func (cn *PeerConn) onPeerHasAllPieces() {
416 cn._peerPieces.Iterate(func(x uint32) bool {
417 t.decPieceAvailability(pieceIndex(x))
421 t.addConnWithAllPieces(&cn.Peer)
422 cn.peerSentHaveAll = true
423 cn._peerPieces.Clear()
424 if !cn.t._pendingPieces.IsEmpty() {
425 cn.updateRequests("Peer.onPeerHasAllPieces")
427 cn.peerPiecesChanged()
430 func (cn *PeerConn) onPeerSentHaveAll() error {
431 cn.onPeerHasAllPieces()
435 func (cn *PeerConn) peerSentHaveNone() error {
436 if !cn.peerSentHaveAll {
437 cn.t.decPeerPieceAvailability(&cn.Peer)
439 cn._peerPieces.Clear()
440 cn.peerSentHaveAll = false
441 cn.peerPiecesChanged()
445 func (c *PeerConn) requestPendingMetadata() {
449 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
450 // Peer doesn't support this.
453 // Request metadata pieces that we don't have in a random order.
455 for index := 0; index < c.t.metadataPieceCount(); index++ {
456 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
457 pending = append(pending, index)
460 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
461 for _, i := range pending {
462 c.requestMetadataPiece(i)
466 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
467 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
468 if msg.Type == pp.Extended {
469 for name, id := range cn.PeerExtensionIDs {
470 if id != msg.ExtendedID {
473 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
476 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
479 func (cn *PeerConn) wroteBytes(n int64) {
480 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
483 func (c *PeerConn) fastEnabled() bool {
484 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
487 func (c *PeerConn) reject(r Request) {
488 if !c.fastEnabled() {
489 panic("fast not enabled")
491 c.write(r.ToMsg(pp.Reject))
492 // It is possible to reject a request before it is added to peer requests due to being invalid.
493 if state, ok := c.peerRequests[r]; ok {
494 state.allocReservation.Drop()
495 delete(c.peerRequests, r)
499 func (c *PeerConn) maximumPeerRequestChunkLength() (_ Option[int]) {
500 uploadRateLimiter := c.t.cl.config.UploadRateLimiter
501 if uploadRateLimiter.Limit() == rate.Inf {
504 return Some(uploadRateLimiter.Burst())
507 // startFetch is for testing purposes currently.
508 func (c *PeerConn) onReadRequest(r Request, startFetch bool) error {
509 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
510 if _, ok := c.peerRequests[r]; ok {
511 torrent.Add("duplicate requests received", 1)
513 return errors.New("received duplicate request with fast enabled")
518 torrent.Add("requests received while choking", 1)
520 torrent.Add("requests rejected while choking", 1)
525 // TODO: What if they've already requested this?
526 if len(c.peerRequests) >= localClientReqq {
527 torrent.Add("requests received while queue full", 1)
531 // BEP 6 says we may close here if we choose.
534 if opt := c.maximumPeerRequestChunkLength(); opt.Ok && int(r.Length) > opt.Value {
535 err := fmt.Errorf("peer requested chunk too long (%v)", r.Length)
536 c.logger.Levelf(log.Warning, err.Error())
544 if !c.t.havePiece(pieceIndex(r.Index)) {
545 // TODO: Tell the peer we don't have the piece, and reject this request.
546 requestsReceivedForMissingPieces.Add(1)
547 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
549 pieceLength := c.t.pieceLength(pieceIndex(r.Index))
550 // Check this after we know we have the piece, so that the piece length will be known.
551 if chunkOverflowsPiece(r.ChunkSpec, pieceLength) {
552 torrent.Add("bad requests received", 1)
553 return errors.New("chunk overflows piece")
555 if c.peerRequests == nil {
556 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
558 value := &peerRequestState{
559 allocReservation: c.peerRequestDataAllocLimiter.Reserve(int64(r.Length)),
561 c.peerRequests[r] = value
563 // TODO: Limit peer request data read concurrency.
564 go c.peerRequestDataReader(r, value)
569 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
570 b, err := c.readPeerRequestData(r, prs)
572 defer c.locker().Unlock()
574 c.peerRequestDataReadFailed(err, r)
577 panic("data must be non-nil to trigger send")
579 torrent.Add("peer request data read successes", 1)
581 // This might be required for the error case too (#752 and #753).
586 // If this is maintained correctly, we might be able to support optional synchronous reading for
587 // chunk sending, the way it used to work.
588 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
589 torrent.Add("peer request data read failures", 1)
590 logLevel := log.Warning
591 if c.t.hasStorageCap() {
592 // It's expected that pieces might drop. See
593 // https://github.com/anacrolix/torrent/issues/702#issuecomment-1000953313.
596 c.logger.WithDefaultLevel(logLevel).Printf("error reading chunk for peer Request %v: %v", r, err)
597 if c.t.closed.IsSet() {
600 i := pieceIndex(r.Index)
601 if c.t.pieceComplete(i) {
602 // There used to be more code here that just duplicated the following break. Piece
603 // completions are currently cached, so I'm not sure how helpful this update is, except to
604 // pull any completion changes pushed to the storage backend in failed reads that got us
606 c.t.updatePieceCompletion(i)
608 // We've probably dropped a piece from storage, but there's no way to communicate this to the
609 // peer. If they ask for it again, we kick them allowing us to send them updated piece states if
610 // we reconnect. TODO: Instead, we could just try to update them with Bitfield or HaveNone and
611 // if they kick us for breaking protocol, on reconnect we will be compliant again (at least
617 // If fast isn't enabled, I think we would have wiped all peer requests when we last
618 // choked, and requests while we're choking would be ignored. It could be possible that
619 // a peer request data read completed concurrently to it being deleted elsewhere.
620 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
622 // Choking a non-fast peer should cause them to flush all their requests.
627 func (c *PeerConn) readPeerRequestData(r Request, prs *peerRequestState) ([]byte, error) {
628 // Should we depend on Torrent closure here? I think it's okay to get cancelled from elsewhere,
629 // or fail to read and then cleanup.
630 ctx := context.Background()
631 err := prs.allocReservation.Wait(ctx)
633 if ctx.Err() == nil {
634 // The error is from the reservation itself. Something is very broken, or we're not
635 // guarding against excessively large requests.
636 err = log.WithLevel(log.Critical, err)
638 err = fmt.Errorf("waiting for alloc limit reservation: %w", err)
641 b := make([]byte, r.Length)
642 p := c.t.info.Piece(int(r.Index))
643 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
650 panic("expected error")
656 func (c *PeerConn) logProtocolBehaviour(level log.Level, format string, arg ...interface{}) {
657 c.logger.WithContextText(fmt.Sprintf(
658 "peer id %q, ext v %q", c.PeerID, c.PeerClientName.Load(),
659 )).SkipCallers(1).Levelf(level, format, arg...)
662 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
663 // exit. Returning will end the connection.
664 func (c *PeerConn) mainReadLoop() (err error) {
667 torrent.Add("connection.mainReadLoop returned with error", 1)
669 torrent.Add("connection.mainReadLoop returned with no error", 1)
675 decoder := pp.Decoder{
676 R: bufio.NewReaderSize(c.r, 1<<17),
677 MaxLength: 4 * pp.Integer(max(int64(t.chunkSize), defaultChunkSize)),
685 err = decoder.Decode(&msg)
687 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
690 if t.closed.IsSet() || c.closed.IsSet() {
696 c.lastMessageReceived = time.Now()
698 receivedKeepalives.Add(1)
701 messageTypesReceived.Add(msg.Type.String(), 1)
702 if msg.Type.FastExtension() && !c.fastEnabled() {
703 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
704 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
711 if !c.fastEnabled() {
712 c.deleteAllRequests("choked by non-fast PeerConn")
714 // We don't decrement pending requests here, let's wait for the peer to either
715 // reject or satisfy the outstanding requests. Additionally, some peers may unchoke
716 // us and resume where they left off, we don't want to have piled on to those chunks
717 // in the meanwhile. I think a peer's ability to abuse this should be limited: they
718 // could let us request a lot of stuff, then choke us and never reject, but they're
719 // only a single peer, our chunk balancing should smooth over this abuse.
722 c.updateExpectingChunks()
725 // Some clients do this for some reason. Transmission doesn't error on this, so we
726 // won't for consistency.
727 c.logProtocolBehaviour(log.Debug, "received unchoke when already unchoked")
730 c.peerChoking = false
732 c.requestState.Requests.Iterate(func(x RequestIndex) bool {
733 if !c.peerAllowedFast.Contains(c.t.pieceIndexOfRequestIndex(x)) {
738 if preservedCount != 0 {
739 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
741 c.logger.Levelf(log.Debug,
742 "%v requests were preserved while being choked (fast=%v)",
746 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
748 if !c.t._pendingPieces.IsEmpty() {
749 c.updateRequests("unchoked")
751 c.updateExpectingChunks()
753 c.peerInterested = true
755 case pp.NotInterested:
756 c.peerInterested = false
757 // We don't clear their requests since it isn't clear in the spec.
758 // We'll probably choke them for this, which will clear them if
759 // appropriate, and is clearly specified.
761 err = c.peerSentHave(pieceIndex(msg.Index))
763 err = c.peerSentBitfield(msg.Bitfield)
765 r := newRequestFromMessage(&msg)
766 err = c.onReadRequest(r, true)
768 err = fmt.Errorf("on reading request %v: %w", r, err)
771 c.doChunkReadStats(int64(len(msg.Piece)))
772 err = c.receiveChunk(&msg)
773 if len(msg.Piece) == int(t.chunkSize) {
774 t.chunkPool.Put(&msg.Piece)
777 err = fmt.Errorf("receiving chunk: %w", err)
780 req := newRequestFromMessage(&msg)
781 c.onPeerSentCancel(req)
783 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
787 pingAddr := net.UDPAddr{
792 pingAddr.Port = int(msg.Port)
794 cl.eachDhtServer(func(s DhtServer) {
798 torrent.Add("suggests received", 1)
799 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).LogLevel(log.Debug, c.t.logger)
800 c.updateRequests("suggested")
802 err = c.onPeerSentHaveAll()
804 err = c.peerSentHaveNone()
806 req := newRequestFromMessage(&msg)
807 if !c.remoteRejectedRequest(c.t.requestIndexFromRequest(req)) {
808 c.logger.Printf("received invalid reject [request=%v, peer=%v]", req, c)
809 err = fmt.Errorf("received invalid reject [request=%v]", req)
812 torrent.Add("allowed fasts received", 1)
813 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).LogLevel(log.Debug, c.t.logger)
814 c.updateRequests("PeerConn.mainReadLoop allowed fast")
816 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
818 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
826 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
828 // TODO: Should we still do this?
830 // These clients use their own extension IDs for outgoing message
831 // types, which is incorrect.
832 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
840 case pp.HandshakeExtendedID:
841 var d pp.ExtendedHandshakeMessage
842 if err := bencode.Unmarshal(payload, &d); err != nil {
843 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
844 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
846 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
849 // c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
851 c.PeerMaxRequests = d.Reqq
853 c.PeerClientName.Store(d.V)
854 if c.PeerExtensionIDs == nil {
855 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
857 c.PeerListenPort = d.Port
858 c.PeerPrefersEncryption = d.Encryption
859 for name, id := range d.M {
860 if _, ok := c.PeerExtensionIDs[name]; !ok {
861 peersSupportingExtension.Add(
862 // expvar.Var.String must produce valid JSON. "ut_payme\xeet_address" was being
863 // entered here which caused problems later when unmarshalling.
864 strconv.Quote(string(name)),
867 c.PeerExtensionIDs[name] = id
869 if d.MetadataSize != 0 {
870 if err = t.setMetadataSize(d.MetadataSize); err != nil {
871 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
874 c.requestPendingMetadata()
875 if !t.cl.config.DisablePEX {
876 t.pex.Add(c) // we learnt enough now
877 // This checks the extension is supported internally.
881 case metadataExtendedId:
882 err := cl.gotMetadataExtensionMsg(payload, t, c)
884 return fmt.Errorf("handling metadata extension message: %w", err)
888 if !c.pex.IsEnabled() {
889 return nil // or hang-up maybe?
891 err = c.pex.Recv(payload)
893 err = fmt.Errorf("receiving pex message: %w", err)
896 case utHolepunchExtendedId:
897 var msg utHolepunch.Msg
898 err = msg.UnmarshalBinary(payload)
900 err = fmt.Errorf("unmarshalling ut_holepunch message: %w", err)
903 err = c.t.handleReceivedUtHolepunchMsg(msg, c)
906 return fmt.Errorf("unexpected extended message ID: %v", id)
910 // Set both the Reader and Writer for the connection from a single ReadWriter.
911 func (cn *PeerConn) setRW(rw io.ReadWriter) {
916 // Returns the Reader and Writer as a combined ReadWriter.
917 func (cn *PeerConn) rw() io.ReadWriter {
924 func (c *PeerConn) uploadAllowed() bool {
925 if c.t.cl.config.NoUpload {
928 if c.t.dataUploadDisallowed {
934 if !c.peerHasWantedPieces() {
937 // Don't upload more than 100 KiB more than we download.
938 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
944 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
945 if c.uploadTimer == nil {
946 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
948 c.uploadTimer.Reset(delay)
952 // Also handles choking and unchoking of the remote peer.
953 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
954 // Breaking or completing this loop means we don't want to upload to the
955 // peer anymore, and we choke them.
957 for c.uploadAllowed() {
958 // We want to upload to the peer.
962 for r, state := range c.peerRequests {
963 if state.data == nil {
966 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
968 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
973 c.setRetryUploadTimer(delay)
974 // Hard to say what to return here.
977 more := c.sendChunk(r, msg, state)
978 delete(c.peerRequests, r)
989 func (cn *PeerConn) drop() {
990 cn.t.dropConnection(cn)
993 func (cn *PeerConn) ban() {
994 cn.t.cl.banPeerIP(cn.remoteIp())
997 // This is called when something has changed that should wake the writer, such as putting stuff into
998 // the writeBuffer, or changing some state that the writer can act on.
999 func (c *PeerConn) tickleWriter() {
1000 c.messageWriter.writeCond.Broadcast()
1003 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1004 c.lastChunkSent = time.Now()
1005 state.allocReservation.Release()
1006 return msg(pp.Message{
1014 func (c *PeerConn) setTorrent(t *Torrent) {
1016 panic("connection already associated with a torrent")
1019 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1020 t.reconcileHandshakeStats(c)
1023 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1024 f := pp.PexPeerFlags(0)
1025 if c.PeerPrefersEncryption {
1026 f |= pp.PexPrefersEncryption
1029 f |= pp.PexOutgoingConn
1032 f |= pp.PexSupportsUtp
1037 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1038 // advertised listen port.
1039 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1040 if !c.outgoing && c.PeerListenPort != 0 {
1041 switch addr := c.RemoteAddr.(type) {
1044 dialAddr.Port = c.PeerListenPort
1048 dialAddr.Port = c.PeerListenPort
1055 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1056 f := c.pexPeerFlags()
1057 addr := c.dialAddr()
1058 return pexEvent{t, addr, f, nil}
1061 func (c *PeerConn) String() string {
1062 return fmt.Sprintf("%T %p [id=%q, exts=%v, v=%q]", c, c, c.PeerID, c.PeerExtensionBytes, c.PeerClientName.Load())
1065 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1066 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1067 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1069 defer cn.locker().RUnlock()
1070 return cn.newPeerPieces()
1073 func (pc *PeerConn) remoteIsTransmission() bool {
1074 return bytes.HasPrefix(pc.PeerID[:], []byte("-TR")) && pc.PeerID[7] == '-'
1077 func (pc *PeerConn) remoteAddrPort() Option[netip.AddrPort] {
1078 return Some(pc.conn.RemoteAddr().(interface {
1079 AddrPort() netip.AddrPort
1083 func (pc *PeerConn) bitExtensionEnabled(bit pp.ExtensionBit) bool {
1084 return pc.t.cl.config.Extensions.GetBit(bit) && pc.PeerExtensionBytes.GetBit(bit)