21 "github.com/anacrolix/chansync"
22 "github.com/anacrolix/chansync/events"
23 "github.com/anacrolix/dht/v2"
24 "github.com/anacrolix/dht/v2/krpc"
25 . "github.com/anacrolix/generics"
26 g "github.com/anacrolix/generics"
27 "github.com/anacrolix/log"
28 "github.com/anacrolix/missinggo/perf"
29 "github.com/anacrolix/missinggo/v2"
30 "github.com/anacrolix/missinggo/v2/bitmap"
31 "github.com/anacrolix/missinggo/v2/pproffd"
32 "github.com/anacrolix/sync"
33 "github.com/davecgh/go-spew/spew"
34 "github.com/dustin/go-humanize"
35 gbtree "github.com/google/btree"
36 "github.com/pion/datachannel"
37 "golang.org/x/time/rate"
39 "github.com/anacrolix/torrent/bencode"
40 "github.com/anacrolix/torrent/internal/check"
41 "github.com/anacrolix/torrent/internal/limiter"
42 "github.com/anacrolix/torrent/internal/panicif"
43 "github.com/anacrolix/torrent/iplist"
44 "github.com/anacrolix/torrent/metainfo"
45 "github.com/anacrolix/torrent/mse"
46 pp "github.com/anacrolix/torrent/peer_protocol"
47 utHolepunch "github.com/anacrolix/torrent/peer_protocol/ut-holepunch"
48 request_strategy "github.com/anacrolix/torrent/request-strategy"
49 "github.com/anacrolix/torrent/storage"
50 "github.com/anacrolix/torrent/tracker"
51 "github.com/anacrolix/torrent/types/infohash"
52 "github.com/anacrolix/torrent/webtorrent"
55 // Clients contain zero or more Torrents. A Client manages a blocklist, the
56 // TCP/UDP protocol ports, and DHT as desired.
58 // An aggregate of stats over all connections. First in struct to ensure 64-bit alignment of
64 closed chansync.SetOnce
70 defaultStorage *storage.Client
74 dhtServers []DhtServer
75 ipBlockList iplist.Ranger
77 // Set of addresses that have our client ID. This intentionally will
78 // include ourselves if we end up trying to connect to our own address
79 // through legitimate channels.
80 dopplegangerAddrs map[string]struct{}
81 badPeerIPs map[netip.Addr]struct{}
82 torrents map[InfoHash]*Torrent
83 pieceRequestOrder map[interface{}]*request_strategy.PieceRequestOrder
85 acceptLimiter map[ipStr]int
86 dialRateLimiter *rate.Limiter
89 websocketTrackers websocketTrackers
91 activeAnnounceLimiter limiter.Instance
92 httpClient *http.Client
97 func (cl *Client) BadPeerIPs() (ips []string) {
99 ips = cl.badPeerIPsLocked()
104 func (cl *Client) badPeerIPsLocked() (ips []string) {
105 ips = make([]string, len(cl.badPeerIPs))
107 for k := range cl.badPeerIPs {
114 func (cl *Client) PeerID() PeerID {
118 // Returns the port number for the first listener that has one. No longer assumes that all port
119 // numbers are the same, due to support for custom listeners. Returns zero if no port number is
121 func (cl *Client) LocalPort() (port int) {
122 for i := 0; i < len(cl.listeners); i += 1 {
123 if port = addrPortOrZero(cl.listeners[i].Addr()); port != 0 {
130 func writeDhtServerStatus(w io.Writer, s DhtServer) {
131 dhtStats := s.Stats()
132 fmt.Fprintf(w, " ID: %x\n", s.ID())
133 spew.Fdump(w, dhtStats)
136 // Writes out a human readable status of the client, such as for writing to a
138 func (cl *Client) WriteStatus(_w io.Writer) {
141 w := bufio.NewWriter(_w)
143 fmt.Fprintf(w, "Listen port: %d\n", cl.LocalPort())
144 fmt.Fprintf(w, "Peer ID: %+q\n", cl.PeerID())
145 fmt.Fprintf(w, "Extension bits: %v\n", cl.config.Extensions)
146 fmt.Fprintf(w, "Announce key: %x\n", cl.announceKey())
147 fmt.Fprintf(w, "Banned IPs: %d\n", len(cl.badPeerIPsLocked()))
148 cl.eachDhtServer(func(s DhtServer) {
149 fmt.Fprintf(w, "%s DHT server at %s:\n", s.Addr().Network(), s.Addr().String())
150 writeDhtServerStatus(w, s)
152 spew.Fdump(w, &cl.stats)
153 torrentsSlice := cl.torrentsAsSlice()
154 fmt.Fprintf(w, "# Torrents: %d\n", len(torrentsSlice))
156 sort.Slice(torrentsSlice, func(l, r int) bool {
157 return torrentsSlice[l].infoHash.AsString() < torrentsSlice[r].infoHash.AsString()
159 for _, t := range torrentsSlice {
161 fmt.Fprint(w, "<unknown name>")
163 fmt.Fprint(w, t.name())
169 "%f%% of %d bytes (%s)",
170 100*(1-float64(t.bytesMissingLocked())/float64(t.info.TotalLength())),
172 humanize.Bytes(uint64(t.length())))
174 w.WriteString("<missing metainfo>")
182 func (cl *Client) initLogger() {
183 logger := cl.config.Logger
188 logger = logger.FilterLevel(log.Debug)
190 cl.logger = logger.WithValues(cl)
193 func (cl *Client) announceKey() int32 {
194 return int32(binary.BigEndian.Uint32(cl.peerID[16:20]))
197 // Initializes a bare minimum Client. *Client and *ClientConfig must not be nil.
198 func (cl *Client) init(cfg *ClientConfig) {
200 g.MakeMap(&cl.dopplegangerAddrs)
201 cl.torrents = make(map[metainfo.Hash]*Torrent)
202 cl.dialRateLimiter = rate.NewLimiter(10, 10)
203 cl.activeAnnounceLimiter.SlotsPerKey = 2
204 cl.event.L = cl.locker()
205 cl.ipBlockList = cfg.IPBlocklist
206 cl.httpClient = &http.Client{
207 Transport: &http.Transport{
208 Proxy: cfg.HTTPProxy,
209 DialContext: cfg.HTTPDialContext,
210 // I think this value was observed from some webseeds. It seems reasonable to extend it
211 // to other uses of HTTP from the client.
217 func NewClient(cfg *ClientConfig) (cl *Client, err error) {
219 cfg = NewDefaultClientConfig()
225 go cl.acceptLimitClearer()
234 storageImpl := cfg.DefaultStorage
235 if storageImpl == nil {
236 // We'd use mmap by default but HFS+ doesn't support sparse files.
237 storageImplCloser := storage.NewFile(cfg.DataDir)
238 cl.onClose = append(cl.onClose, func() {
239 if err := storageImplCloser.Close(); err != nil {
240 cl.logger.Printf("error closing default storage: %s", err)
243 storageImpl = storageImplCloser
245 cl.defaultStorage = storage.NewClient(storageImpl)
247 if cfg.PeerID != "" {
248 missinggo.CopyExact(&cl.peerID, cfg.PeerID)
250 o := copy(cl.peerID[:], cfg.Bep20)
251 _, err = rand.Read(cl.peerID[o:])
253 panic("error generating peer id")
257 sockets, err := listenAll(cl.listenNetworks(), cl.config.ListenHost, cl.config.ListenPort, cl.firewallCallback, cl.logger)
265 for _, _s := range sockets {
266 s := _s // Go is fucking retarded.
267 cl.onClose = append(cl.onClose, func() { go s.Close() })
268 if peerNetworkEnabled(parseNetworkString(s.Addr().Network()), cl.config) {
269 cl.dialers = append(cl.dialers, s)
270 cl.listeners = append(cl.listeners, s)
271 if cl.config.AcceptPeerConnections {
272 go cl.acceptConnections(s)
279 for _, s := range sockets {
280 if pc, ok := s.(net.PacketConn); ok {
281 ds, err := cl.NewAnacrolixDhtServer(pc)
285 cl.dhtServers = append(cl.dhtServers, AnacrolixDhtServerWrapper{ds})
286 cl.onClose = append(cl.onClose, func() { ds.Close() })
291 cl.websocketTrackers = websocketTrackers{
294 GetAnnounceRequest: func(event tracker.AnnounceEvent, infoHash [20]byte) (tracker.AnnounceRequest, error) {
297 t, ok := cl.torrents[infoHash]
299 return tracker.AnnounceRequest{}, errors.New("torrent not tracked by client")
301 return t.announceRequest(event), nil
303 Proxy: cl.config.HTTPProxy,
304 WebsocketTrackerHttpHeader: cl.config.WebsocketTrackerHttpHeader,
305 DialContext: cl.config.TrackerDialContext,
306 OnConn: func(dc datachannel.ReadWriteCloser, dcc webtorrent.DataChannelContext) {
309 t, ok := cl.torrents[dcc.InfoHash]
311 cl.logger.WithDefaultLevel(log.Warning).Printf(
312 "got webrtc conn for unloaded torrent with infohash %x",
318 go t.onWebRtcConn(dc, dcc)
325 func (cl *Client) AddDhtServer(d DhtServer) {
326 cl.dhtServers = append(cl.dhtServers, d)
329 // Adds a Dialer for outgoing connections. All Dialers are used when attempting to connect to a
330 // given address for any Torrent.
331 func (cl *Client) AddDialer(d Dialer) {
334 cl.dialers = append(cl.dialers, d)
335 for _, t := range cl.torrents {
340 func (cl *Client) Listeners() []Listener {
344 // Registers a Listener, and starts Accepting on it. You must Close Listeners provided this way
346 func (cl *Client) AddListener(l Listener) {
347 cl.listeners = append(cl.listeners, l)
348 if cl.config.AcceptPeerConnections {
349 go cl.acceptConnections(l)
353 func (cl *Client) firewallCallback(net.Addr) bool {
355 block := !cl.wantConns() || !cl.config.AcceptPeerConnections
358 torrent.Add("connections firewalled", 1)
360 torrent.Add("connections not firewalled", 1)
365 func (cl *Client) listenOnNetwork(n network) bool {
366 if n.Ipv4 && cl.config.DisableIPv4 {
369 if n.Ipv6 && cl.config.DisableIPv6 {
372 if n.Tcp && cl.config.DisableTCP {
375 if n.Udp && cl.config.DisableUTP && cl.config.NoDHT {
381 func (cl *Client) listenNetworks() (ns []network) {
382 for _, n := range allPeerNetworks {
383 if cl.listenOnNetwork(n) {
390 // Creates an anacrolix/dht Server, as would be done internally in NewClient, for the given conn.
391 func (cl *Client) NewAnacrolixDhtServer(conn net.PacketConn) (s *dht.Server, err error) {
392 logger := cl.logger.WithNames("dht", conn.LocalAddr().String())
393 cfg := dht.ServerConfig{
394 IPBlocklist: cl.ipBlockList,
396 OnAnnouncePeer: cl.onDHTAnnouncePeer,
397 PublicIP: func() net.IP {
398 if connIsIpv6(conn) && cl.config.PublicIp6 != nil {
399 return cl.config.PublicIp6
401 return cl.config.PublicIp4
403 StartingNodes: cl.config.DhtStartingNodes(conn.LocalAddr().Network()),
404 OnQuery: cl.config.DHTOnQuery,
407 if f := cl.config.ConfigureAnacrolixDhtServer; f != nil {
410 s, err = dht.NewServer(&cfg)
412 go s.TableMaintainer()
417 func (cl *Client) Closed() events.Done {
418 return cl.closed.Done()
421 func (cl *Client) eachDhtServer(f func(DhtServer)) {
422 for _, ds := range cl.dhtServers {
427 // Stops the client. All connections to peers are closed and all activity will come to a halt.
428 func (cl *Client) Close() (errs []error) {
429 var closeGroup sync.WaitGroup // For concurrent cleanup to complete before returning
431 for _, t := range cl.torrents {
432 err := t.close(&closeGroup)
434 errs = append(errs, err)
437 for i := range cl.onClose {
438 cl.onClose[len(cl.onClose)-1-i]()
443 closeGroup.Wait() // defer is LIFO. We want to Wait() after cl.unlock()
447 func (cl *Client) ipBlockRange(ip net.IP) (r iplist.Range, blocked bool) {
448 if cl.ipBlockList == nil {
451 return cl.ipBlockList.Lookup(ip)
454 func (cl *Client) ipIsBlocked(ip net.IP) bool {
455 _, blocked := cl.ipBlockRange(ip)
459 func (cl *Client) wantConns() bool {
460 if cl.config.AlwaysWantConns {
463 for _, t := range cl.torrents {
464 if t.wantIncomingConns() {
471 // TODO: Apply filters for non-standard networks, particularly rate-limiting.
472 func (cl *Client) rejectAccepted(conn net.Conn) error {
474 return errors.New("don't want conns right now")
476 ra := conn.RemoteAddr()
477 if rip := addrIpOrNil(ra); rip != nil {
478 if cl.config.DisableIPv4Peers && rip.To4() != nil {
479 return errors.New("ipv4 peers disabled")
481 if cl.config.DisableIPv4 && len(rip) == net.IPv4len {
482 return errors.New("ipv4 disabled")
484 if cl.config.DisableIPv6 && len(rip) == net.IPv6len && rip.To4() == nil {
485 return errors.New("ipv6 disabled")
487 if cl.rateLimitAccept(rip) {
488 return errors.New("source IP accepted rate limited")
490 if cl.badPeerIPPort(rip, missinggo.AddrPort(ra)) {
491 return errors.New("bad source addr")
497 func (cl *Client) acceptConnections(l Listener) {
499 conn, err := l.Accept()
500 torrent.Add("client listener accepts", 1)
501 conn = pproffd.WrapNetConn(conn)
503 closed := cl.closed.IsSet()
505 if !closed && conn != nil {
506 reject = cl.rejectAccepted(conn)
516 log.Fmsg("error accepting connection: %s", err).LogLevel(log.Debug, cl.logger)
521 torrent.Add("rejected accepted connections", 1)
522 cl.logger.LazyLog(log.Debug, func() log.Msg {
523 return log.Fmsg("rejecting accepted conn: %v", reject)
527 go cl.incomingConnection(conn)
529 cl.logger.LazyLog(log.Debug, func() log.Msg {
530 return log.Fmsg("accepted %q connection at %q from %q",
536 torrent.Add(fmt.Sprintf("accepted conn remote IP len=%d", len(addrIpOrNil(conn.RemoteAddr()))), 1)
537 torrent.Add(fmt.Sprintf("accepted conn network=%s", conn.RemoteAddr().Network()), 1)
538 torrent.Add(fmt.Sprintf("accepted on %s listener", l.Addr().Network()), 1)
543 // Creates the PeerConn.connString for a regular net.Conn PeerConn.
544 func regularNetConnPeerConnConnString(nc net.Conn) string {
545 return fmt.Sprintf("%s-%s", nc.LocalAddr(), nc.RemoteAddr())
548 func (cl *Client) incomingConnection(nc net.Conn) {
550 if tc, ok := nc.(*net.TCPConn); ok {
553 remoteAddr, _ := tryIpPortFromNetAddr(nc.RemoteAddr())
554 c := cl.newConnection(
558 remoteAddr: nc.RemoteAddr(),
559 localPublicAddr: cl.publicAddr(remoteAddr.IP),
560 network: nc.RemoteAddr().Network(),
561 connString: regularNetConnPeerConnConnString(nc),
568 c.Discovery = PeerSourceIncoming
569 cl.runReceivedConn(c)
572 // Returns a handle to the given torrent, if it's present in the client.
573 func (cl *Client) Torrent(ih metainfo.Hash) (t *Torrent, ok bool) {
576 t, ok = cl.torrents[ih]
580 func (cl *Client) torrent(ih metainfo.Hash) *Torrent {
581 return cl.torrents[ih]
584 type DialResult struct {
589 func countDialResult(err error) {
591 torrent.Add("successful dials", 1)
593 torrent.Add("unsuccessful dials", 1)
597 func reducedDialTimeout(minDialTimeout, max time.Duration, halfOpenLimit, pendingPeers int) (ret time.Duration) {
598 ret = max / time.Duration((pendingPeers+halfOpenLimit)/halfOpenLimit)
599 if ret < minDialTimeout {
605 // Returns whether an address is known to connect to a client with our own ID.
606 func (cl *Client) dopplegangerAddr(addr string) bool {
607 _, ok := cl.dopplegangerAddrs[addr]
611 // Returns a connection over UTP or TCP, whichever is first to connect.
612 func (cl *Client) dialFirst(ctx context.Context, addr string) (res DialResult) {
613 return DialFirst(ctx, addr, cl.dialers)
616 // Returns a connection over UTP or TCP, whichever is first to connect.
617 func DialFirst(ctx context.Context, addr string, dialers []Dialer) (res DialResult) {
619 t := perf.NewTimer(perf.CallerName(0))
622 t.Mark(fmt.Sprintf("returned no conn (context: %v)", ctx.Err()))
624 t.Mark("returned conn over " + res.Dialer.DialerNetwork())
628 ctx, cancel := context.WithCancel(ctx)
629 // As soon as we return one connection, cancel the others.
632 resCh := make(chan DialResult, left)
633 for _, _s := range dialers {
638 dialFromSocket(ctx, s, addr),
643 // Wait for a successful connection.
645 defer perf.ScopeTimer()()
646 for ; left > 0 && res.Conn == nil; left-- {
650 // There are still uncompleted dials.
652 for ; left > 0; left-- {
653 conn := (<-resCh).Conn
660 go torrent.Add(fmt.Sprintf("network dialed first: %s", res.Conn.RemoteAddr().Network()), 1)
665 func dialFromSocket(ctx context.Context, s Dialer, addr string) net.Conn {
666 c, err := s.Dial(ctx, addr)
668 log.Levelf(log.Debug, "error dialing %q: %v", addr, err)
670 // This is a bit optimistic, but it looks non-trivial to thread this through the proxy code. Set
671 // it now in case we close the connection forthwith. Note this is also done in the TCP dialer
672 // code to increase the chance it's done.
673 if tc, ok := c.(*net.TCPConn); ok {
680 func (cl *Client) noLongerHalfOpen(t *Torrent, addr string, attemptKey outgoingConnAttemptKey) {
681 path := t.getHalfOpenPath(addr, attemptKey)
683 panic("should exist")
688 panicif.NotEqual(cl.numHalfOpen, cl.countHalfOpenFromTorrents())
690 for _, t := range cl.torrents {
695 func (cl *Client) countHalfOpenFromTorrents() (count int) {
696 for _, t := range cl.torrents {
697 for _, attempts := range t.halfOpen {
698 count += len(attempts)
704 // Performs initiator handshakes and returns a connection. Returns nil *PeerConn if no connection
705 // for valid reasons.
706 func (cl *Client) initiateProtocolHandshakes(
711 newConnOpts newConnectionOpts,
713 c *PeerConn, err error,
715 c = cl.newConnection(nc, newConnOpts)
716 c.headerEncrypted = encryptHeader
717 ctx, cancel := context.WithTimeout(ctx, cl.config.HandshakesTimeout)
719 dl, ok := ctx.Deadline()
723 err = nc.SetDeadline(dl)
727 err = cl.initiateHandshakes(c, t)
731 func (cl *Client) waitForRendezvousConnect(ctx context.Context, rz *utHolepunchRendezvous) error {
734 case rz.gotConnect.IsSet():
736 case len(rz.relays) == 0:
737 return errors.New("all relays failed")
738 case ctx.Err() != nil:
739 return context.Cause(ctx)
741 relayCond := rz.relayCond.Signaled()
744 case <-rz.gotConnect.Done():
752 // Returns nil connection and nil error if no connection could be established for valid reasons.
753 func (cl *Client) initiateRendezvousConnect(
754 t *Torrent, addr PeerRemoteAddr,
755 ) (ok bool, err error) {
756 holepunchAddr, err := addrPortFromPeerRemoteAddr(addr)
762 rz, err := t.startHolepunchRendezvous(holepunchAddr)
770 ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
772 err = cl.waitForRendezvousConnect(ctx, rz)
773 delete(t.utHolepunchRendezvous, holepunchAddr)
775 err = fmt.Errorf("waiting for rendezvous connect signal: %w", err)
780 // Returns nil connection and nil error if no connection could be established for valid reasons.
781 func (cl *Client) establishOutgoingConnEx(
782 opts outgoingConnOpts,
783 obfuscatedHeader bool,
785 _ *PeerConn, err error,
790 if !opts.skipHolepunchRendezvous {
791 rzOk, err = cl.initiateRendezvousConnect(t, addr)
793 err = fmt.Errorf("initiating rendezvous connect: %w", err)
796 if opts.requireRendezvous && !rzOk {
802 dialCtx, cancel := context.WithTimeout(context.Background(), func() time.Duration {
805 return t.dialTimeout()
808 dr := cl.dialFirst(dialCtx, addr.String())
811 if dialCtx.Err() != nil {
812 return nil, fmt.Errorf("dialing: %w", dialCtx.Err())
814 return nil, errors.New("dial failed")
816 addrIpPort, _ := tryIpPortFromNetAddr(addr)
817 c, err := cl.initiateProtocolHandshakes(
818 context.Background(), nc, t, obfuscatedHeader,
822 // It would be possible to retrieve a public IP from the dialer used here?
823 localPublicAddr: cl.publicAddr(addrIpPort.IP),
824 network: dr.Dialer.DialerNetwork(),
825 connString: regularNetConnPeerConnConnString(nc),
833 // Returns nil connection and nil error if no connection could be established
834 // for valid reasons.
835 func (cl *Client) establishOutgoingConn(opts outgoingConnOpts) (c *PeerConn, err error) {
836 torrent.Add("establish outgoing connection", 1)
837 obfuscatedHeaderFirst := cl.config.HeaderObfuscationPolicy.Preferred
838 c, err = cl.establishOutgoingConnEx(opts, obfuscatedHeaderFirst)
840 torrent.Add("initiated conn with preferred header obfuscation", 1)
843 // cl.logger.Printf("error establishing connection to %s (obfuscatedHeader=%t): %v", addr, obfuscatedHeaderFirst, err)
844 if cl.config.HeaderObfuscationPolicy.RequirePreferred {
845 // We should have just tried with the preferred header obfuscation. If it was required,
846 // there's nothing else to try.
849 // Try again with encryption if we didn't earlier, or without if we did.
850 c, err = cl.establishOutgoingConnEx(opts, !obfuscatedHeaderFirst)
852 torrent.Add("initiated conn with fallback header obfuscation", 1)
854 // cl.logger.Printf("error establishing fallback connection to %v: %v", addr, err)
858 type outgoingConnOpts struct {
861 // Don't attempt to connect unless a connect message is received after initiating a rendezvous.
862 requireRendezvous bool
863 // Don't send rendezvous requests to eligible relays.
864 skipHolepunchRendezvous bool
867 // Called to dial out and run a connection. The addr we're given is already
868 // considered half-open.
869 func (cl *Client) outgoingConnection(
870 opts outgoingConnOpts,
873 attemptKey outgoingConnAttemptKey,
875 cl.dialRateLimiter.Wait(context.Background())
876 c, err := cl.establishOutgoingConn(opts)
878 c.conn.SetWriteDeadline(time.Time{})
882 // Don't release lock between here and addPeerConn, unless it's for
884 cl.noLongerHalfOpen(opts.t, opts.addr.String(), attemptKey)
887 cl.logger.Levelf(log.Debug, "error establishing outgoing connection to %v: %v", opts.addr, err)
894 opts.t.runHandshookConnLoggingErr(c)
897 // The port number for incoming peer connections. 0 if the client isn't listening.
898 func (cl *Client) incomingPeerPort() int {
899 return cl.LocalPort()
902 func (cl *Client) initiateHandshakes(c *PeerConn, t *Torrent) error {
903 if c.headerEncrypted {
906 rw, c.cryptoMethod, err = mse.InitiateHandshake(
913 cl.config.CryptoProvides,
917 return fmt.Errorf("header obfuscation handshake: %w", err)
920 ih, err := cl.connBtHandshake(c, &t.infoHash)
922 return fmt.Errorf("bittorrent protocol handshake: %w", err)
924 if ih != t.infoHash {
925 return errors.New("bittorrent protocol handshake: peer infohash didn't match")
930 // Calls f with any secret keys. Note that it takes the Client lock, and so must be used from code
931 // that won't also try to take the lock. This saves us copying all the infohashes everytime.
932 func (cl *Client) forSkeys(f func([]byte) bool) {
935 if false { // Emulate the bug from #114
937 for ih := range cl.torrents {
941 for range cl.torrents {
948 for ih := range cl.torrents {
955 func (cl *Client) handshakeReceiverSecretKeys() mse.SecretKeyIter {
956 if ret := cl.config.Callbacks.ReceiveEncryptedHandshakeSkeys; ret != nil {
962 // Do encryption and bittorrent handshakes as receiver.
963 func (cl *Client) receiveHandshakes(c *PeerConn) (t *Torrent, err error) {
964 defer perf.ScopeTimerErr(&err)()
966 rw, c.headerEncrypted, c.cryptoMethod, err = handleEncryption(c.rw(), cl.handshakeReceiverSecretKeys(), cl.config.HeaderObfuscationPolicy, cl.config.CryptoSelector)
968 if err == nil || err == mse.ErrNoSecretKeyMatch {
969 if c.headerEncrypted {
970 torrent.Add("handshakes received encrypted", 1)
972 torrent.Add("handshakes received unencrypted", 1)
975 torrent.Add("handshakes received with error while handling encryption", 1)
978 if err == mse.ErrNoSecretKeyMatch {
983 if cl.config.HeaderObfuscationPolicy.RequirePreferred && c.headerEncrypted != cl.config.HeaderObfuscationPolicy.Preferred {
984 err = errors.New("connection does not have required header obfuscation")
987 ih, err := cl.connBtHandshake(c, nil)
989 return nil, fmt.Errorf("during bt handshake: %w", err)
997 var successfulPeerWireProtocolHandshakePeerReservedBytes expvar.Map
1001 "successful_peer_wire_protocol_handshake_peer_reserved_bytes",
1002 &successfulPeerWireProtocolHandshakePeerReservedBytes)
1005 func (cl *Client) connBtHandshake(c *PeerConn, ih *metainfo.Hash) (ret metainfo.Hash, err error) {
1006 res, err := pp.Handshake(c.rw(), ih, cl.peerID, cl.config.Extensions)
1010 successfulPeerWireProtocolHandshakePeerReservedBytes.Add(res.PeerExtensionBits.String(), 1)
1012 c.PeerExtensionBytes = res.PeerExtensionBits
1013 c.PeerID = res.PeerID
1014 c.completedHandshake = time.Now()
1015 if cb := cl.config.Callbacks.CompletedHandshake; cb != nil {
1021 func (cl *Client) runReceivedConn(c *PeerConn) {
1022 err := c.conn.SetDeadline(time.Now().Add(cl.config.HandshakesTimeout))
1026 t, err := cl.receiveHandshakes(c)
1028 cl.logger.LazyLog(log.Debug, func() log.Msg {
1030 "error receiving handshakes on %v: %s", c, err,
1032 "network", c.Network,
1035 torrent.Add("error receiving handshake", 1)
1037 cl.onBadAccept(c.RemoteAddr)
1042 torrent.Add("received handshake for unloaded torrent", 1)
1043 cl.logger.LazyLog(log.Debug, func() log.Msg {
1044 return log.Fmsg("received handshake for unloaded torrent")
1047 cl.onBadAccept(c.RemoteAddr)
1051 torrent.Add("received handshake for loaded torrent", 1)
1052 c.conn.SetWriteDeadline(time.Time{})
1055 t.runHandshookConnLoggingErr(c)
1058 // Client lock must be held before entering this.
1059 func (cl *Client) runHandshookConn(c *PeerConn, t *Torrent) error {
1061 for i, b := range cl.config.MinPeerExtensions {
1062 if c.PeerExtensionBytes[i]&b != b {
1063 return fmt.Errorf("peer did not meet minimum peer extensions: %x", c.PeerExtensionBytes[:])
1066 if c.PeerID == cl.peerID {
1069 addr := c.RemoteAddr.String()
1070 cl.dopplegangerAddrs[addr] = struct{}{}
1072 // Because the remote address is not necessarily the same as its client's torrent listen
1073 // address, we won't record the remote address as a doppleganger. Instead, the initiator
1074 // can record *us* as the doppleganger.
1076 t.logger.Levelf(log.Debug, "local and remote peer ids are the same")
1079 c.r = deadlineReader{c.conn, c.r}
1080 completedHandshakeConnectionFlags.Add(c.connectionFlags(), 1)
1081 if connIsIpv6(c.conn) {
1082 torrent.Add("completed handshake over ipv6", 1)
1084 if err := t.addPeerConn(c); err != nil {
1085 return fmt.Errorf("adding connection: %w", err)
1087 defer t.dropConnection(c)
1088 c.startMessageWriter()
1089 cl.sendInitialMessages(c, t)
1090 c.initUpdateRequestsTimer()
1091 err := c.mainReadLoop()
1093 return fmt.Errorf("main read loop: %w", err)
1098 func (p *Peer) initUpdateRequestsTimer() {
1100 if p.updateRequestsTimer != nil {
1101 panic(p.updateRequestsTimer)
1104 if enableUpdateRequestsTimer {
1105 p.updateRequestsTimer = time.AfterFunc(math.MaxInt64, p.updateRequestsTimerFunc)
1109 const peerUpdateRequestsTimerReason = "updateRequestsTimer"
1111 func (c *Peer) updateRequestsTimerFunc() {
1113 defer c.locker().Unlock()
1114 if c.closed.IsSet() {
1117 if c.isLowOnRequests() {
1118 // If there are no outstanding requests, then a request update should have already run.
1121 if d := time.Since(c.lastRequestUpdate); d < updateRequestsTimerDuration {
1122 // These should be benign, Timer.Stop doesn't guarantee that its function won't run if it's
1123 // already been fired.
1124 torrent.Add("spurious timer requests updates", 1)
1127 c.updateRequests(peerUpdateRequestsTimerReason)
1130 // Maximum pending requests we allow peers to send us. If peer requests are buffered on read, this
1131 // instructs the amount of memory that might be used to cache pending writes. Assuming 512KiB
1132 // (1<<19) cached for sending, for 16KiB (1<<14) chunks.
1133 const localClientReqq = 1024
1135 // See the order given in Transmission's tr_peerMsgsNew.
1136 func (cl *Client) sendInitialMessages(conn *PeerConn, torrent *Torrent) {
1137 if conn.PeerExtensionBytes.SupportsExtended() && cl.config.Extensions.SupportsExtended() {
1138 conn.write(pp.Message{
1140 ExtendedID: pp.HandshakeExtendedID,
1141 ExtendedPayload: func() []byte {
1142 msg := pp.ExtendedHandshakeMessage{
1143 M: map[pp.ExtensionName]pp.ExtensionNumber{
1144 pp.ExtensionNameMetadata: metadataExtendedId,
1145 utHolepunch.ExtensionName: utHolepunchExtendedId,
1147 V: cl.config.ExtendedHandshakeClientVersion,
1148 Reqq: localClientReqq,
1149 YourIp: pp.CompactIp(conn.remoteIp()),
1150 Encryption: cl.config.HeaderObfuscationPolicy.Preferred || !cl.config.HeaderObfuscationPolicy.RequirePreferred,
1151 Port: cl.incomingPeerPort(),
1152 MetadataSize: torrent.metadataSize(),
1153 // TODO: We can figure these out specific to the socket used.
1154 Ipv4: pp.CompactIp(cl.config.PublicIp4.To4()),
1155 Ipv6: cl.config.PublicIp6.To16(),
1157 if !cl.config.DisablePEX {
1158 msg.M[pp.ExtensionNamePex] = pexExtendedId
1160 return bencode.MustMarshal(msg)
1165 if conn.fastEnabled() {
1166 if torrent.haveAllPieces() {
1167 conn.write(pp.Message{Type: pp.HaveAll})
1168 conn.sentHaves.AddRange(0, bitmap.BitRange(conn.t.NumPieces()))
1170 } else if !torrent.haveAnyPieces() {
1171 conn.write(pp.Message{Type: pp.HaveNone})
1172 conn.sentHaves.Clear()
1178 if conn.PeerExtensionBytes.SupportsDHT() && cl.config.Extensions.SupportsDHT() && cl.haveDhtServer() {
1179 conn.write(pp.Message{
1186 func (cl *Client) dhtPort() (ret uint16) {
1187 if len(cl.dhtServers) == 0 {
1190 return uint16(missinggo.AddrPort(cl.dhtServers[len(cl.dhtServers)-1].Addr()))
1193 func (cl *Client) haveDhtServer() bool {
1194 return len(cl.dhtServers) > 0
1197 // Process incoming ut_metadata message.
1198 func (cl *Client) gotMetadataExtensionMsg(payload []byte, t *Torrent, c *PeerConn) error {
1199 var d pp.ExtendedMetadataRequestMsg
1200 err := bencode.Unmarshal(payload, &d)
1201 if _, ok := err.(bencode.ErrUnusedTrailingBytes); ok {
1202 } else if err != nil {
1203 return fmt.Errorf("error unmarshalling bencode: %s", err)
1207 case pp.DataMetadataExtensionMsgType:
1208 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.MetadataChunksRead }))
1209 if !c.requestedMetadataPiece(piece) {
1210 return fmt.Errorf("got unexpected piece %d", piece)
1212 c.metadataRequests[piece] = false
1213 begin := len(payload) - d.PieceSize()
1214 if begin < 0 || begin >= len(payload) {
1215 return fmt.Errorf("data has bad offset in payload: %d", begin)
1217 t.saveMetadataPiece(piece, payload[begin:])
1218 c.lastUsefulChunkReceived = time.Now()
1219 err = t.maybeCompleteMetadata()
1221 // Log this at the Torrent-level, as we don't partition metadata by Peer yet, so we
1222 // don't know who to blame. TODO: Also errors can be returned here that aren't related
1223 // to verifying metadata, which should be fixed. This should be tagged with metadata, so
1224 // log consumers can filter for this message.
1225 t.logger.WithDefaultLevel(log.Warning).Printf("error completing metadata: %v", err)
1228 case pp.RequestMetadataExtensionMsgType:
1229 if !t.haveMetadataPiece(piece) {
1230 c.write(t.newMetadataExtensionMessage(c, pp.RejectMetadataExtensionMsgType, d.Piece, nil))
1233 start := (1 << 14) * piece
1234 c.logger.WithDefaultLevel(log.Debug).Printf("sending metadata piece %d", piece)
1235 c.write(t.newMetadataExtensionMessage(c, pp.DataMetadataExtensionMsgType, piece, t.metadataBytes[start:start+t.metadataPieceSize(piece)]))
1237 case pp.RejectMetadataExtensionMsgType:
1240 return errors.New("unknown msg_type value")
1244 func (cl *Client) badPeerAddr(addr PeerRemoteAddr) bool {
1245 if ipa, ok := tryIpPortFromNetAddr(addr); ok {
1246 return cl.badPeerIPPort(ipa.IP, ipa.Port)
1251 // Returns whether the IP address and port are considered "bad".
1252 func (cl *Client) badPeerIPPort(ip net.IP, port int) bool {
1253 if port == 0 || ip == nil {
1256 if cl.dopplegangerAddr(net.JoinHostPort(ip.String(), strconv.FormatInt(int64(port), 10))) {
1259 if _, ok := cl.ipBlockRange(ip); ok {
1262 ipAddr, ok := netip.AddrFromSlice(ip)
1266 if _, ok := cl.badPeerIPs[ipAddr]; ok {
1272 // Return a Torrent ready for insertion into a Client.
1273 func (cl *Client) newTorrent(ih metainfo.Hash, specStorage storage.ClientImpl) (t *Torrent) {
1274 return cl.newTorrentOpt(AddTorrentOpts{
1276 Storage: specStorage,
1280 // Return a Torrent ready for insertion into a Client.
1281 func (cl *Client) newTorrentOpt(opts AddTorrentOpts) (t *Torrent) {
1282 // use provided storage, if provided
1283 storageClient := cl.defaultStorage
1284 if opts.Storage != nil {
1285 storageClient = storage.NewClient(opts.Storage)
1290 infoHash: opts.InfoHash,
1291 peers: prioritizedPeers{
1293 getPrio: func(p PeerInfo) peerPriority {
1295 return bep40PriorityIgnoreError(cl.publicAddr(ipPort.IP), ipPort)
1298 conns: make(map[*PeerConn]struct{}, 2*cl.config.EstablishedConnsPerTorrent),
1300 storageOpener: storageClient,
1301 maxEstablishedConns: cl.config.EstablishedConnsPerTorrent,
1303 metadataChanged: sync.Cond{
1306 webSeeds: make(map[string]*Peer),
1307 gotMetainfoC: make(chan struct{}),
1309 t.smartBanCache.Hash = sha1.Sum
1310 t.smartBanCache.Init()
1311 t.networkingEnabled.Set()
1312 t.logger = cl.logger.WithContextValue(t).WithNames("torrent", t.infoHash.HexString()).WithDefaultLevel(log.Debug)
1313 t.sourcesLogger = t.logger.WithNames("sources")
1314 if opts.ChunkSize == 0 {
1315 opts.ChunkSize = defaultChunkSize
1317 t.setChunkSize(opts.ChunkSize)
1321 // A file-like handle to some torrent data resource.
1322 type Handle interface {
1329 func (cl *Client) AddTorrentInfoHash(infoHash metainfo.Hash) (t *Torrent, new bool) {
1330 return cl.AddTorrentInfoHashWithStorage(infoHash, nil)
1333 // Adds a torrent by InfoHash with a custom Storage implementation.
1334 // If the torrent already exists then this Storage is ignored and the
1335 // existing torrent returned with `new` set to `false`
1336 func (cl *Client) AddTorrentInfoHashWithStorage(infoHash metainfo.Hash, specStorage storage.ClientImpl) (t *Torrent, new bool) {
1339 t, ok := cl.torrents[infoHash]
1345 t = cl.newTorrent(infoHash, specStorage)
1346 cl.eachDhtServer(func(s DhtServer) {
1347 if cl.config.PeriodicallyAnnounceTorrentsToDht {
1348 go t.dhtAnnouncer(s)
1351 cl.torrents[infoHash] = t
1352 cl.clearAcceptLimits()
1353 t.updateWantPeersEvent()
1354 // Tickle Client.waitAccept, new torrent may want conns.
1355 cl.event.Broadcast()
1359 // Adds a torrent by InfoHash with a custom Storage implementation. If the torrent already exists
1360 // then this Storage is ignored and the existing torrent returned with `new` set to `false`.
1361 func (cl *Client) AddTorrentOpt(opts AddTorrentOpts) (t *Torrent, new bool) {
1362 infoHash := opts.InfoHash
1365 t, ok := cl.torrents[infoHash]
1371 t = cl.newTorrentOpt(opts)
1372 cl.eachDhtServer(func(s DhtServer) {
1373 if cl.config.PeriodicallyAnnounceTorrentsToDht {
1374 go t.dhtAnnouncer(s)
1377 cl.torrents[infoHash] = t
1378 t.setInfoBytesLocked(opts.InfoBytes)
1379 cl.clearAcceptLimits()
1380 t.updateWantPeersEvent()
1381 // Tickle Client.waitAccept, new torrent may want conns.
1382 cl.event.Broadcast()
1386 type AddTorrentOpts struct {
1388 Storage storage.ClientImpl
1389 ChunkSize pp.Integer
1393 // Add or merge a torrent spec. Returns new if the torrent wasn't already in the client. See also
1394 // Torrent.MergeSpec.
1395 func (cl *Client) AddTorrentSpec(spec *TorrentSpec) (t *Torrent, new bool, err error) {
1396 t, new = cl.AddTorrentOpt(AddTorrentOpts{
1397 InfoHash: spec.InfoHash,
1398 Storage: spec.Storage,
1399 ChunkSize: spec.ChunkSize,
1403 // ChunkSize was already applied by adding a new Torrent, and MergeSpec disallows changing
1405 modSpec.ChunkSize = 0
1407 err = t.MergeSpec(&modSpec)
1408 if err != nil && new {
1414 // The trackers will be merged with the existing ones. If the Info isn't yet known, it will be set.
1415 // spec.DisallowDataDownload/Upload will be read and applied
1416 // The display name is replaced if the new spec provides one. Note that any `Storage` is ignored.
1417 func (t *Torrent) MergeSpec(spec *TorrentSpec) error {
1418 if spec.DisplayName != "" {
1419 t.SetDisplayName(spec.DisplayName)
1421 if spec.InfoBytes != nil {
1422 err := t.SetInfoBytes(spec.InfoBytes)
1428 cl.AddDhtNodes(spec.DhtNodes)
1429 t.UseSources(spec.Sources)
1432 t.initialPieceCheckDisabled = spec.DisableInitialPieceCheck
1433 for _, url := range spec.Webseeds {
1436 for _, peerAddr := range spec.PeerAddrs {
1438 Addr: StringAddr(peerAddr),
1439 Source: PeerSourceDirect,
1443 if spec.ChunkSize != 0 {
1444 panic("chunk size cannot be changed for existing Torrent")
1446 t.addTrackers(spec.Trackers)
1448 t.dataDownloadDisallowed.SetBool(spec.DisallowDataDownload)
1449 t.dataUploadDisallowed = spec.DisallowDataUpload
1453 func (cl *Client) dropTorrent(infoHash metainfo.Hash, wg *sync.WaitGroup) (err error) {
1454 t, ok := cl.torrents[infoHash]
1456 err = fmt.Errorf("no such torrent")
1460 delete(cl.torrents, infoHash)
1464 func (cl *Client) allTorrentsCompleted() bool {
1465 for _, t := range cl.torrents {
1469 if !t.haveAllPieces() {
1476 // Returns true when all torrents are completely downloaded and false if the
1477 // client is stopped before that.
1478 func (cl *Client) WaitAll() bool {
1481 for !cl.allTorrentsCompleted() {
1482 if cl.closed.IsSet() {
1490 // Returns handles to all the torrents loaded in the Client.
1491 func (cl *Client) Torrents() []*Torrent {
1494 return cl.torrentsAsSlice()
1497 func (cl *Client) torrentsAsSlice() (ret []*Torrent) {
1498 for _, t := range cl.torrents {
1499 ret = append(ret, t)
1504 func (cl *Client) AddMagnet(uri string) (T *Torrent, err error) {
1505 spec, err := TorrentSpecFromMagnetUri(uri)
1509 T, _, err = cl.AddTorrentSpec(spec)
1513 func (cl *Client) AddTorrent(mi *metainfo.MetaInfo) (T *Torrent, err error) {
1514 ts, err := TorrentSpecFromMetaInfoErr(mi)
1518 T, _, err = cl.AddTorrentSpec(ts)
1522 func (cl *Client) AddTorrentFromFile(filename string) (T *Torrent, err error) {
1523 mi, err := metainfo.LoadFromFile(filename)
1527 return cl.AddTorrent(mi)
1530 func (cl *Client) DhtServers() []DhtServer {
1531 return cl.dhtServers
1534 func (cl *Client) AddDhtNodes(nodes []string) {
1535 for _, n := range nodes {
1536 hmp := missinggo.SplitHostMaybePort(n)
1537 ip := net.ParseIP(hmp.Host)
1539 cl.logger.Printf("won't add DHT node with bad IP: %q", hmp.Host)
1542 ni := krpc.NodeInfo{
1543 Addr: krpc.NodeAddr{
1548 cl.eachDhtServer(func(s DhtServer) {
1554 func (cl *Client) banPeerIP(ip net.IP) {
1555 // We can't take this from string, because it will lose netip's v4on6. net.ParseIP parses v4
1556 // addresses directly to v4on6, which doesn't compare equal with v4.
1557 ipAddr, ok := netip.AddrFromSlice(ip)
1561 g.MakeMapIfNilAndSet(&cl.badPeerIPs, ipAddr, struct{}{})
1562 for _, t := range cl.torrents {
1563 t.iterPeers(func(p *Peer) {
1564 if p.remoteIp().Equal(ip) {
1565 t.logger.Levelf(log.Warning, "dropping peer %v with banned ip %v", p, ip)
1566 // Should this be a close?
1573 type newConnectionOpts struct {
1575 remoteAddr PeerRemoteAddr
1576 localPublicAddr peerLocalPublicAddr
1581 func (cl *Client) newConnection(nc net.Conn, opts newConnectionOpts) (c *PeerConn) {
1582 if opts.network == "" {
1583 panic(opts.remoteAddr)
1587 outgoing: opts.outgoing,
1590 PeerMaxRequests: 250,
1592 RemoteAddr: opts.remoteAddr,
1593 localPublicAddr: opts.localPublicAddr,
1594 Network: opts.network,
1595 callbacks: &cl.config.Callbacks,
1597 connString: opts.connString,
1600 c.peerRequestDataAllocLimiter.Max = cl.config.MaxAllocPeerRequestDataPerConn
1601 c.initRequestState()
1602 // TODO: Need to be much more explicit about this, including allowing non-IP bannable addresses.
1603 if opts.remoteAddr != nil {
1604 netipAddrPort, err := netip.ParseAddrPort(opts.remoteAddr.String())
1606 c.bannableAddr = Some(netipAddrPort.Addr())
1610 c.logger = cl.logger.WithDefaultLevel(log.Warning)
1611 c.setRW(connStatsReadWriter{nc, c})
1612 c.r = &rateLimitedReader{
1613 l: cl.config.DownloadRateLimiter,
1618 "new PeerConn %p [Client %p remoteAddr %v network %v outgoing %t]",
1619 c, cl, opts.remoteAddr, opts.network, opts.outgoing,
1621 for _, f := range cl.config.Callbacks.NewPeer {
1627 func (cl *Client) onDHTAnnouncePeer(ih metainfo.Hash, ip net.IP, port int, portOk bool) {
1634 t.addPeers([]PeerInfo{{
1635 Addr: ipPortAddr{ip, port},
1636 Source: PeerSourceDhtAnnouncePeer,
1640 func firstNotNil(ips ...net.IP) net.IP {
1641 for _, ip := range ips {
1649 func (cl *Client) eachListener(f func(Listener) bool) {
1650 for _, s := range cl.listeners {
1657 func (cl *Client) findListener(f func(Listener) bool) (ret Listener) {
1658 for i := 0; i < len(cl.listeners); i += 1 {
1659 if ret = cl.listeners[i]; f(ret) {
1666 func (cl *Client) publicIp(peer net.IP) net.IP {
1667 // TODO: Use BEP 10 to determine how peers are seeing us.
1668 if peer.To4() != nil {
1670 cl.config.PublicIp4,
1671 cl.findListenerIp(func(ip net.IP) bool { return ip.To4() != nil }),
1676 cl.config.PublicIp6,
1677 cl.findListenerIp(func(ip net.IP) bool { return ip.To4() == nil }),
1681 func (cl *Client) findListenerIp(f func(net.IP) bool) net.IP {
1682 l := cl.findListener(
1683 func(l Listener) bool {
1684 return f(addrIpOrNil(l.Addr()))
1690 return addrIpOrNil(l.Addr())
1693 // Our IP as a peer should see it.
1694 func (cl *Client) publicAddr(peer net.IP) IpPort {
1695 return IpPort{IP: cl.publicIp(peer), Port: uint16(cl.incomingPeerPort())}
1698 // ListenAddrs addresses currently being listened to.
1699 func (cl *Client) ListenAddrs() (ret []net.Addr) {
1701 ret = make([]net.Addr, len(cl.listeners))
1702 for i := 0; i < len(cl.listeners); i += 1 {
1703 ret[i] = cl.listeners[i].Addr()
1709 func (cl *Client) PublicIPs() (ips []net.IP) {
1710 if ip := cl.config.PublicIp4; ip != nil {
1711 ips = append(ips, ip)
1713 if ip := cl.config.PublicIp6; ip != nil {
1714 ips = append(ips, ip)
1719 func (cl *Client) onBadAccept(addr PeerRemoteAddr) {
1720 ipa, ok := tryIpPortFromNetAddr(addr)
1724 ip := maskIpForAcceptLimiting(ipa.IP)
1725 if cl.acceptLimiter == nil {
1726 cl.acceptLimiter = make(map[ipStr]int)
1728 cl.acceptLimiter[ipStr(ip.String())]++
1731 func maskIpForAcceptLimiting(ip net.IP) net.IP {
1732 if ip4 := ip.To4(); ip4 != nil {
1733 return ip4.Mask(net.CIDRMask(24, 32))
1738 func (cl *Client) clearAcceptLimits() {
1739 cl.acceptLimiter = nil
1742 func (cl *Client) acceptLimitClearer() {
1745 case <-cl.closed.Done():
1747 case <-time.After(15 * time.Minute):
1749 cl.clearAcceptLimits()
1755 func (cl *Client) rateLimitAccept(ip net.IP) bool {
1756 if cl.config.DisableAcceptRateLimiting {
1759 return cl.acceptLimiter[ipStr(maskIpForAcceptLimiting(ip).String())] > 0
1762 func (cl *Client) rLock() {
1766 func (cl *Client) rUnlock() {
1770 func (cl *Client) lock() {
1774 func (cl *Client) unlock() {
1778 func (cl *Client) locker() *lockWithDeferreds {
1782 func (cl *Client) String() string {
1783 return fmt.Sprintf("<%[1]T %[1]p>", cl)
1786 // Returns connection-level aggregate stats at the Client level. See the comment on
1787 // TorrentStats.ConnStats.
1788 func (cl *Client) ConnStats() ConnStats {
1789 return cl.stats.Copy()