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) peerImplStatusLines() []string {
69 lines := make([]string, 0, 2)
72 fmt.Sprintf("%+-55q %v %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString))
73 if cn.supportsExtension(pp.ExtensionNamePex) {
77 "pex: %v conns, %v unsent events",
78 cn.pex.remoteLiveConns,
84 // Returns true if the connection is over IPv6.
85 func (cn *PeerConn) ipv6() bool {
90 return len(ip) == net.IPv6len
93 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
94 // specification for this.
95 func (cn *PeerConn) isPreferredDirection() bool {
96 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
99 // Returns whether the left connection should be preferred over the right one,
100 // considering only their networking properties. If ok is false, we can't
102 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) bool {
103 var ml multiless.Computation
104 ml = ml.Bool(r.isPreferredDirection(), l.isPreferredDirection())
105 ml = ml.Bool(l.utp(), r.utp())
106 ml = ml.Bool(r.ipv6(), l.ipv6())
110 func (cn *PeerConn) peerHasAllPieces() (all, known bool) {
111 if cn.peerSentHaveAll {
114 if !cn.t.haveInfo() {
117 return cn._peerPieces.GetCardinality() == uint64(cn.t.numPieces()), true
120 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
121 cn.setNumPieces(info.NumPieces())
124 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
125 // receiving badly sized BITFIELD, or invalid HAVE messages.
126 func (cn *PeerConn) setNumPieces(num pieceIndex) {
127 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
128 cn.peerPiecesChanged()
131 func (cn *PeerConn) peerPieces() *roaring.Bitmap {
132 return &cn._peerPieces
135 func (cn *PeerConn) connectionFlags() (ret string) {
137 ret += string([]byte{b})
139 if cn.cryptoMethod == mse.CryptoMethodRC4 {
141 } else if cn.headerEncrypted {
144 ret += string(cn.Discovery)
151 func (cn *PeerConn) utp() bool {
152 return parseNetworkString(cn.Network).Udp
155 func (cn *PeerConn) onClose() {
156 if cn.pex.IsEnabled() {
163 if cb := cn.callbacks.PeerConnClosed; cb != nil {
168 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
169 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
170 func (cn *PeerConn) write(msg pp.Message) bool {
171 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
172 // We don't need to track bytes here because the connection's Writer has that behaviour injected
173 // (although there's some delay between us buffering the message, and the connection writer
174 // flushing it out.).
175 notFull := cn.messageWriter.write(msg)
176 // Last I checked only Piece messages affect stats, and we don't write those.
182 func (cn *PeerConn) requestMetadataPiece(index int) {
183 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
184 if eID == pp.ExtensionDeleteNumber {
187 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
190 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
191 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
192 for index >= len(cn.metadataRequests) {
193 cn.metadataRequests = append(cn.metadataRequests, false)
195 cn.metadataRequests[index] = true
198 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
199 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
202 func (cn *PeerConn) onPeerSentCancel(r Request) {
203 if _, ok := cn.peerRequests[r]; !ok {
204 torrent.Add("unexpected cancels received", 1)
207 if cn.fastEnabled() {
210 delete(cn.peerRequests, r)
214 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
219 more = msg(pp.Message{
222 if !cn.fastEnabled() {
223 cn.deleteAllPeerRequests()
228 func (cn *PeerConn) deleteAllPeerRequests() {
229 for _, state := range cn.peerRequests {
230 state.allocReservation.Drop()
232 cn.peerRequests = nil
235 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
240 return msg(pp.Message{
245 func (pc *PeerConn) writeInterested(interested bool) bool {
246 return pc.write(pp.Message{
247 Type: func() pp.MessageType {
251 return pp.NotInterested
257 func (me *PeerConn) _request(r Request) bool {
258 return me.write(pp.Message{
266 func (me *PeerConn) _cancel(r RequestIndex) bool {
267 me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
268 // Transmission does not send rejects for received cancels. See
269 // https://github.com/transmission/transmission/pull/2275.
270 return me.fastEnabled() && !me.remoteIsTransmission()
273 func (cn *PeerConn) fillWriteBuffer() {
274 if cn.messageWriter.writeBuffer.Len() > writeBufferLowWaterLen {
275 // Fully committing to our max requests requires sufficient space (see
276 // maxLocalToRemoteRequests). Flush what we have instead. We also prefer always to make
277 // requests than to do PEX or upload, so we short-circuit before handling those. Any update
278 // request reason will not be cleared, so we'll come right back here when there's space. We
279 // can't do this in maybeUpdateActualRequestState because it's a method on Peer and has no
280 // knowledge of write buffers.
282 cn.maybeUpdateActualRequestState()
283 if cn.pex.IsEnabled() {
284 if flow := cn.pex.Share(cn.write); !flow {
291 func (cn *PeerConn) have(piece pieceIndex) {
292 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
297 Index: pp.Integer(piece),
299 cn.sentHaves.Add(bitmap.BitIndex(piece))
302 func (cn *PeerConn) postBitfield() {
303 if cn.sentHaves.Len() != 0 {
304 panic("bitfield must be first have-related message sent")
306 if !cn.t.haveAnyPieces() {
311 Bitfield: cn.t.bitfield(),
313 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
316 func (cn *PeerConn) handleUpdateRequests() {
317 // The writer determines the request state as needed when it can write.
321 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
322 if newMin > cn.peerMinPieces {
323 cn.peerMinPieces = newMin
327 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
328 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
329 return errors.New("invalid piece")
331 if cn.peerHasPiece(piece) {
334 cn.raisePeerMinPieces(piece + 1)
335 if !cn.peerHasPiece(piece) {
336 cn.t.incPieceAvailability(piece)
338 cn._peerPieces.Add(uint32(piece))
339 if cn.t.wantPieceIndex(piece) {
340 cn.updateRequests("have")
342 cn.peerPiecesChanged()
346 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
348 panic("expected bitfield length divisible by 8")
350 // We know that the last byte means that at most the last 7 bits are wasted.
351 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
352 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
353 // Ignore known excess pieces.
354 bf = bf[:cn.t.numPieces()]
356 bm := boolSliceToBitmap(bf)
357 if cn.t.haveInfo() && pieceIndex(bm.GetCardinality()) == cn.t.numPieces() {
358 cn.onPeerHasAllPieces()
362 cn.raisePeerMinPieces(pieceIndex(bm.Maximum()) + 1)
364 shouldUpdateRequests := false
365 if cn.peerSentHaveAll {
366 if !cn.t.deleteConnWithAllPieces(&cn.Peer) {
369 cn.peerSentHaveAll = false
370 if !cn._peerPieces.IsEmpty() {
371 panic("if peer has all, we expect no individual peer pieces to be set")
374 bm.Xor(&cn._peerPieces)
376 cn.peerSentHaveAll = false
377 // bm is now 'on' for pieces that are changing
378 bm.Iterate(func(x uint32) bool {
380 if cn._peerPieces.Contains(x) {
381 // Then we must be losing this piece
382 cn.t.decPieceAvailability(pi)
384 if !shouldUpdateRequests && cn.t.wantPieceIndex(pieceIndex(x)) {
385 shouldUpdateRequests = true
387 // We must be gaining this piece
388 cn.t.incPieceAvailability(pieceIndex(x))
392 // Apply the changes. If we had everything previously, this should be empty, so xor is the same
394 cn._peerPieces.Xor(&bm)
395 if shouldUpdateRequests {
396 cn.updateRequests("bitfield")
398 // We didn't guard this before, I see no reason to do it now.
399 cn.peerPiecesChanged()
403 func (cn *PeerConn) onPeerHasAllPieces() {
406 cn._peerPieces.Iterate(func(x uint32) bool {
407 t.decPieceAvailability(pieceIndex(x))
411 t.addConnWithAllPieces(&cn.Peer)
412 cn.peerSentHaveAll = true
413 cn._peerPieces.Clear()
414 if !cn.t._pendingPieces.IsEmpty() {
415 cn.updateRequests("Peer.onPeerHasAllPieces")
417 cn.peerPiecesChanged()
420 func (cn *PeerConn) onPeerSentHaveAll() error {
421 cn.onPeerHasAllPieces()
425 func (cn *PeerConn) peerSentHaveNone() error {
426 if !cn.peerSentHaveAll {
427 cn.t.decPeerPieceAvailability(&cn.Peer)
429 cn._peerPieces.Clear()
430 cn.peerSentHaveAll = false
431 cn.peerPiecesChanged()
435 func (c *PeerConn) requestPendingMetadata() {
439 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
440 // Peer doesn't support this.
443 // Request metadata pieces that we don't have in a random order.
445 for index := 0; index < c.t.metadataPieceCount(); index++ {
446 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
447 pending = append(pending, index)
450 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
451 for _, i := range pending {
452 c.requestMetadataPiece(i)
456 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
457 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
458 if msg.Type == pp.Extended {
459 for name, id := range cn.PeerExtensionIDs {
460 if id != msg.ExtendedID {
463 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
466 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
469 func (cn *PeerConn) wroteBytes(n int64) {
470 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
473 func (c *PeerConn) fastEnabled() bool {
474 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
477 func (c *PeerConn) reject(r Request) {
478 if !c.fastEnabled() {
479 panic("fast not enabled")
481 c.write(r.ToMsg(pp.Reject))
482 // It is possible to reject a request before it is added to peer requests due to being invalid.
483 if state, ok := c.peerRequests[r]; ok {
484 state.allocReservation.Drop()
485 delete(c.peerRequests, r)
489 func (c *PeerConn) maximumPeerRequestChunkLength() (_ Option[int]) {
490 uploadRateLimiter := c.t.cl.config.UploadRateLimiter
491 if uploadRateLimiter.Limit() == rate.Inf {
494 return Some(uploadRateLimiter.Burst())
497 // startFetch is for testing purposes currently.
498 func (c *PeerConn) onReadRequest(r Request, startFetch bool) error {
499 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
500 if _, ok := c.peerRequests[r]; ok {
501 torrent.Add("duplicate requests received", 1)
503 return errors.New("received duplicate request with fast enabled")
508 torrent.Add("requests received while choking", 1)
510 torrent.Add("requests rejected while choking", 1)
515 // TODO: What if they've already requested this?
516 if len(c.peerRequests) >= localClientReqq {
517 torrent.Add("requests received while queue full", 1)
521 // BEP 6 says we may close here if we choose.
524 if opt := c.maximumPeerRequestChunkLength(); opt.Ok && int(r.Length) > opt.Value {
525 err := fmt.Errorf("peer requested chunk too long (%v)", r.Length)
526 c.logger.Levelf(log.Warning, err.Error())
534 if !c.t.havePiece(pieceIndex(r.Index)) {
535 // TODO: Tell the peer we don't have the piece, and reject this request.
536 requestsReceivedForMissingPieces.Add(1)
537 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
539 pieceLength := c.t.pieceLength(pieceIndex(r.Index))
540 // Check this after we know we have the piece, so that the piece length will be known.
541 if chunkOverflowsPiece(r.ChunkSpec, pieceLength) {
542 torrent.Add("bad requests received", 1)
543 return errors.New("chunk overflows piece")
545 if c.peerRequests == nil {
546 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
548 value := &peerRequestState{
549 allocReservation: c.peerRequestDataAllocLimiter.Reserve(int64(r.Length)),
551 c.peerRequests[r] = value
553 // TODO: Limit peer request data read concurrency.
554 go c.peerRequestDataReader(r, value)
559 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
560 b, err := c.readPeerRequestData(r, prs)
562 defer c.locker().Unlock()
564 c.peerRequestDataReadFailed(err, r)
567 panic("data must be non-nil to trigger send")
569 torrent.Add("peer request data read successes", 1)
571 // This might be required for the error case too (#752 and #753).
576 // If this is maintained correctly, we might be able to support optional synchronous reading for
577 // chunk sending, the way it used to work.
578 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
579 torrent.Add("peer request data read failures", 1)
580 logLevel := log.Warning
581 if c.t.hasStorageCap() {
582 // It's expected that pieces might drop. See
583 // https://github.com/anacrolix/torrent/issues/702#issuecomment-1000953313.
586 c.logger.WithDefaultLevel(logLevel).Printf("error reading chunk for peer Request %v: %v", r, err)
587 if c.t.closed.IsSet() {
590 i := pieceIndex(r.Index)
591 if c.t.pieceComplete(i) {
592 // There used to be more code here that just duplicated the following break. Piece
593 // completions are currently cached, so I'm not sure how helpful this update is, except to
594 // pull any completion changes pushed to the storage backend in failed reads that got us
596 c.t.updatePieceCompletion(i)
598 // We've probably dropped a piece from storage, but there's no way to communicate this to the
599 // peer. If they ask for it again, we kick them allowing us to send them updated piece states if
600 // we reconnect. TODO: Instead, we could just try to update them with Bitfield or HaveNone and
601 // if they kick us for breaking protocol, on reconnect we will be compliant again (at least
607 // If fast isn't enabled, I think we would have wiped all peer requests when we last
608 // choked, and requests while we're choking would be ignored. It could be possible that
609 // a peer request data read completed concurrently to it being deleted elsewhere.
610 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
612 // Choking a non-fast peer should cause them to flush all their requests.
617 func (c *PeerConn) readPeerRequestData(r Request, prs *peerRequestState) ([]byte, error) {
618 // Should we depend on Torrent closure here? I think it's okay to get cancelled from elsewhere,
619 // or fail to read and then cleanup.
620 ctx := context.Background()
621 err := prs.allocReservation.Wait(ctx)
623 if ctx.Err() == nil {
624 // The error is from the reservation itself. Something is very broken, or we're not
625 // guarding against excessively large requests.
626 err = log.WithLevel(log.Critical, err)
628 err = fmt.Errorf("waiting for alloc limit reservation: %w", err)
631 b := make([]byte, r.Length)
632 p := c.t.info.Piece(int(r.Index))
633 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
640 panic("expected error")
646 func (c *PeerConn) logProtocolBehaviour(level log.Level, format string, arg ...interface{}) {
647 c.logger.WithContextText(fmt.Sprintf(
648 "peer id %q, ext v %q", c.PeerID, c.PeerClientName.Load(),
649 )).SkipCallers(1).Levelf(level, format, arg...)
652 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
653 // exit. Returning will end the connection.
654 func (c *PeerConn) mainReadLoop() (err error) {
657 torrent.Add("connection.mainReadLoop returned with error", 1)
659 torrent.Add("connection.mainReadLoop returned with no error", 1)
665 decoder := pp.Decoder{
666 R: bufio.NewReaderSize(c.r, 1<<17),
667 MaxLength: 4 * pp.Integer(max(int64(t.chunkSize), defaultChunkSize)),
675 err = decoder.Decode(&msg)
677 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
680 if t.closed.IsSet() || c.closed.IsSet() {
686 c.lastMessageReceived = time.Now()
688 receivedKeepalives.Add(1)
691 messageTypesReceived.Add(msg.Type.String(), 1)
692 if msg.Type.FastExtension() && !c.fastEnabled() {
693 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
694 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
701 if !c.fastEnabled() {
702 c.deleteAllRequests("choked by non-fast PeerConn")
704 // We don't decrement pending requests here, let's wait for the peer to either
705 // reject or satisfy the outstanding requests. Additionally, some peers may unchoke
706 // us and resume where they left off, we don't want to have piled on to those chunks
707 // in the meanwhile. I think a peer's ability to abuse this should be limited: they
708 // could let us request a lot of stuff, then choke us and never reject, but they're
709 // only a single peer, our chunk balancing should smooth over this abuse.
712 c.updateExpectingChunks()
715 // Some clients do this for some reason. Transmission doesn't error on this, so we
716 // won't for consistency.
717 c.logProtocolBehaviour(log.Debug, "received unchoke when already unchoked")
720 c.peerChoking = false
722 c.requestState.Requests.Iterate(func(x RequestIndex) bool {
723 if !c.peerAllowedFast.Contains(c.t.pieceIndexOfRequestIndex(x)) {
728 if preservedCount != 0 {
729 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
731 c.logger.Levelf(log.Debug,
732 "%v requests were preserved while being choked (fast=%v)",
736 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
738 if !c.t._pendingPieces.IsEmpty() {
739 c.updateRequests("unchoked")
741 c.updateExpectingChunks()
743 c.peerInterested = true
745 case pp.NotInterested:
746 c.peerInterested = false
747 // We don't clear their requests since it isn't clear in the spec.
748 // We'll probably choke them for this, which will clear them if
749 // appropriate, and is clearly specified.
751 err = c.peerSentHave(pieceIndex(msg.Index))
753 err = c.peerSentBitfield(msg.Bitfield)
755 r := newRequestFromMessage(&msg)
756 err = c.onReadRequest(r, true)
758 err = fmt.Errorf("on reading request %v: %w", r, err)
761 c.doChunkReadStats(int64(len(msg.Piece)))
762 err = c.receiveChunk(&msg)
763 if len(msg.Piece) == int(t.chunkSize) {
764 t.chunkPool.Put(&msg.Piece)
767 err = fmt.Errorf("receiving chunk: %w", err)
770 req := newRequestFromMessage(&msg)
771 c.onPeerSentCancel(req)
773 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
777 pingAddr := net.UDPAddr{
782 pingAddr.Port = int(msg.Port)
784 cl.eachDhtServer(func(s DhtServer) {
788 torrent.Add("suggests received", 1)
789 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).LogLevel(log.Debug, c.t.logger)
790 c.updateRequests("suggested")
792 err = c.onPeerSentHaveAll()
794 err = c.peerSentHaveNone()
796 req := newRequestFromMessage(&msg)
797 if !c.remoteRejectedRequest(c.t.requestIndexFromRequest(req)) {
798 c.logger.Printf("received invalid reject [request=%v, peer=%v]", req, c)
799 err = fmt.Errorf("received invalid reject [request=%v]", req)
802 torrent.Add("allowed fasts received", 1)
803 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).LogLevel(log.Debug, c.t.logger)
804 c.updateRequests("PeerConn.mainReadLoop allowed fast")
806 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
808 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
816 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
818 // TODO: Should we still do this?
820 // These clients use their own extension IDs for outgoing message
821 // types, which is incorrect.
822 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
830 case pp.HandshakeExtendedID:
831 var d pp.ExtendedHandshakeMessage
832 if err := bencode.Unmarshal(payload, &d); err != nil {
833 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
834 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
836 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
839 // c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
841 c.PeerMaxRequests = d.Reqq
843 c.PeerClientName.Store(d.V)
844 if c.PeerExtensionIDs == nil {
845 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
847 c.PeerListenPort = d.Port
848 c.PeerPrefersEncryption = d.Encryption
849 for name, id := range d.M {
850 if _, ok := c.PeerExtensionIDs[name]; !ok {
851 peersSupportingExtension.Add(
852 // expvar.Var.String must produce valid JSON. "ut_payme\xeet_address" was being
853 // entered here which caused problems later when unmarshalling.
854 strconv.Quote(string(name)),
857 c.PeerExtensionIDs[name] = id
859 if d.MetadataSize != 0 {
860 if err = t.setMetadataSize(d.MetadataSize); err != nil {
861 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
864 c.requestPendingMetadata()
865 if !t.cl.config.DisablePEX {
866 t.pex.Add(c) // we learnt enough now
867 // This checks the extension is supported internally.
871 case metadataExtendedId:
872 err := cl.gotMetadataExtensionMsg(payload, t, c)
874 return fmt.Errorf("handling metadata extension message: %w", err)
878 if !c.pex.IsEnabled() {
879 return nil // or hang-up maybe?
881 err = c.pex.Recv(payload)
883 err = fmt.Errorf("receiving pex message: %w", err)
886 case utHolepunchExtendedId:
887 var msg utHolepunch.Msg
888 err = msg.UnmarshalBinary(payload)
890 err = fmt.Errorf("unmarshalling ut_holepunch message: %w", err)
893 err = c.t.handleReceivedUtHolepunchMsg(msg, c)
896 return fmt.Errorf("unexpected extended message ID: %v", id)
900 // Set both the Reader and Writer for the connection from a single ReadWriter.
901 func (cn *PeerConn) setRW(rw io.ReadWriter) {
906 // Returns the Reader and Writer as a combined ReadWriter.
907 func (cn *PeerConn) rw() io.ReadWriter {
914 func (c *PeerConn) uploadAllowed() bool {
915 if c.t.cl.config.NoUpload {
918 if c.t.dataUploadDisallowed {
924 if !c.peerHasWantedPieces() {
927 // Don't upload more than 100 KiB more than we download.
928 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
934 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
935 if c.uploadTimer == nil {
936 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
938 c.uploadTimer.Reset(delay)
942 // Also handles choking and unchoking of the remote peer.
943 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
944 // Breaking or completing this loop means we don't want to upload to the
945 // peer anymore, and we choke them.
947 for c.uploadAllowed() {
948 // We want to upload to the peer.
952 for r, state := range c.peerRequests {
953 if state.data == nil {
956 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
958 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
963 c.setRetryUploadTimer(delay)
964 // Hard to say what to return here.
967 more := c.sendChunk(r, msg, state)
968 delete(c.peerRequests, r)
979 func (cn *PeerConn) drop() {
980 cn.t.dropConnection(cn)
983 func (cn *PeerConn) ban() {
984 cn.t.cl.banPeerIP(cn.remoteIp())
987 // This is called when something has changed that should wake the writer, such as putting stuff into
988 // the writeBuffer, or changing some state that the writer can act on.
989 func (c *PeerConn) tickleWriter() {
990 c.messageWriter.writeCond.Broadcast()
993 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
994 c.lastChunkSent = time.Now()
995 state.allocReservation.Release()
996 return msg(pp.Message{
1004 func (c *PeerConn) setTorrent(t *Torrent) {
1006 panic("connection already associated with a torrent")
1009 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1010 t.reconcileHandshakeStats(c)
1013 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1014 f := pp.PexPeerFlags(0)
1015 if c.PeerPrefersEncryption {
1016 f |= pp.PexPrefersEncryption
1019 f |= pp.PexOutgoingConn
1022 f |= pp.PexSupportsUtp
1027 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1028 // advertised listen port.
1029 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1030 if !c.outgoing && c.PeerListenPort != 0 {
1031 switch addr := c.RemoteAddr.(type) {
1034 dialAddr.Port = c.PeerListenPort
1038 dialAddr.Port = c.PeerListenPort
1045 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1046 f := c.pexPeerFlags()
1047 addr := c.dialAddr()
1048 return pexEvent{t, addr, f, nil}
1051 func (c *PeerConn) String() string {
1052 return fmt.Sprintf("%T %p [id=%q, exts=%v, v=%q]", c, c, c.PeerID, c.PeerExtensionBytes, c.PeerClientName.Load())
1055 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1056 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1057 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1059 defer cn.locker().RUnlock()
1060 return cn.newPeerPieces()
1063 func (pc *PeerConn) remoteIsTransmission() bool {
1064 return bytes.HasPrefix(pc.PeerID[:], []byte("-TR")) && pc.PeerID[7] == '-'
1067 func (pc *PeerConn) remoteAddrPort() Option[netip.AddrPort] {
1068 return Some(pc.conn.RemoteAddr().(interface {
1069 AddrPort() netip.AddrPort