// Copyright (c) Tailscale Inc & AUTHORS // SPDX-License-Identifier: BSD-3-Clause // Package magicsock implements a socket that can change its communication path while // in use, actively searching for the best way to communicate. package magicsock import ( "bufio" "context" "errors" "fmt" "io" "net" "net/netip" "runtime" "strconv" "strings" "sync" "sync/atomic" "time" "github.com/tailscale/wireguard-go/conn" "go4.org/mem" "golang.org/x/net/ipv4" "golang.org/x/net/ipv6" "tailscale.com/control/controlknobs" "tailscale.com/disco" "tailscale.com/envknob" "tailscale.com/health" "tailscale.com/hostinfo" "tailscale.com/ipn/ipnstate" "tailscale.com/net/connstats" "tailscale.com/net/interfaces" "tailscale.com/net/netcheck" "tailscale.com/net/neterror" "tailscale.com/net/netmon" "tailscale.com/net/netns" "tailscale.com/net/packet" "tailscale.com/net/ping" "tailscale.com/net/portmapper" "tailscale.com/net/sockstats" "tailscale.com/net/stun" "tailscale.com/net/tstun" "tailscale.com/syncs" "tailscale.com/tailcfg" "tailscale.com/tstime" "tailscale.com/tstime/mono" "tailscale.com/types/key" "tailscale.com/types/lazy" "tailscale.com/types/logger" "tailscale.com/types/netmap" "tailscale.com/types/nettype" "tailscale.com/types/views" "tailscale.com/util/clientmetric" "tailscale.com/util/mak" "tailscale.com/util/ringbuffer" "tailscale.com/util/set" "tailscale.com/util/testenv" "tailscale.com/util/uniq" "tailscale.com/wgengine/capture" "tailscale.com/wgengine/wgint" ) const ( // These are disco.Magic in big-endian form, 4 then 2 bytes. The // BPF filters need the magic in this format to match on it. Used // only in magicsock_linux.go, but defined here so that the test // which verifies this is the correct magic doesn't also need a // _linux variant. discoMagic1 = 0x5453f09f discoMagic2 = 0x92ac // UDP socket read/write buffer size (7MB). The value of 7MB is chosen as it // is the max supported by a default configuration of macOS. Some platforms // will silently clamp the value. socketBufferSize = 7 << 20 ) // A Conn routes UDP packets and actively manages a list of its endpoints. type Conn struct { // This block mirrors the contents and field order of the Options // struct. Initialized once at construction, then constant. logf logger.Logf epFunc func([]tailcfg.Endpoint) derpActiveFunc func() idleFunc func() time.Duration // nil means unknown testOnlyPacketListener nettype.PacketListener noteRecvActivity func(key.NodePublic) // or nil, see Options.NoteRecvActivity netMon *netmon.Monitor // or nil controlKnobs *controlknobs.Knobs // or nil // ================================================================ // No locking required to access these fields, either because // they're static after construction, or are wholly owned by a // single goroutine. connCtx context.Context // closed on Conn.Close connCtxCancel func() // closes connCtx donec <-chan struct{} // connCtx.Done()'s to avoid context.cancelCtx.Done()'s mutex per call // pconn4 and pconn6 are the underlying UDP sockets used to // send/receive packets for wireguard and other magicsock // protocols. pconn4 RebindingUDPConn pconn6 RebindingUDPConn receiveBatchPool sync.Pool // closeDisco4 and closeDisco6 are io.Closers to shut down the raw // disco packet receivers. If nil, no raw disco receiver is // running for the given family. closeDisco4 io.Closer closeDisco6 io.Closer // netChecker is the prober that discovers local network // conditions, including the closest DERP relay and NAT mappings. netChecker *netcheck.Client // portMapper is the NAT-PMP/PCP/UPnP prober/client, for requesting // port mappings from NAT devices. portMapper *portmapper.Client // derpRecvCh is used by receiveDERP to read DERP messages. // It must have buffer size > 0; see issue 3736. derpRecvCh chan derpReadResult // bind is the wireguard-go conn.Bind for Conn. bind *connBind // ============================================================ // Fields that must be accessed via atomic load/stores. // noV4 and noV6 are whether IPv4 and IPv6 are known to be // missing. They're only used to suppress log spam. The name // is named negatively because in early start-up, we don't yet // necessarily have a netcheck.Report and don't want to skip // logging. noV4, noV6 atomic.Bool silentDiscoOn atomic.Bool // whether silent disco is enabled probeUDPLifetimeOn atomic.Bool // whether probing of UDP lifetime is enabled // noV4Send is whether IPv4 UDP is known to be unable to transmit // at all. This could happen if the socket is in an invalid state // (as can happen on darwin after a network link status change). noV4Send atomic.Bool // networkUp is whether the network is up (some interface is up // with IPv4 or IPv6). It's used to suppress log spam and prevent // new connection that'll fail. networkUp atomic.Bool // Whether debugging logging is enabled. debugLogging atomic.Bool // havePrivateKey is whether privateKey is non-zero. havePrivateKey atomic.Bool publicKeyAtomic syncs.AtomicValue[key.NodePublic] // or NodeKey zero value if !havePrivateKey // derpMapAtomic is the same as derpMap, but without requiring // sync.Mutex. For use with NewRegionClient's callback, to avoid // lock ordering deadlocks. See issue 3726 and mu field docs. derpMapAtomic atomic.Pointer[tailcfg.DERPMap] lastNetCheckReport atomic.Pointer[netcheck.Report] // port is the preferred port from opts.Port; 0 means auto. port atomic.Uint32 // peerMTUEnabled is whether path MTU discovery to peers is enabled. // //lint:ignore U1000 used on Linux/Darwin only peerMTUEnabled atomic.Bool // stats maintains per-connection counters. stats atomic.Pointer[connstats.Statistics] // captureHook, if non-nil, is the pcap logging callback when capturing. captureHook syncs.AtomicValue[capture.Callback] // discoPrivate is the private naclbox key used for active // discovery traffic. It is always present, and immutable. discoPrivate key.DiscoPrivate // public of discoPrivate. It is always present and immutable. discoPublic key.DiscoPublic // ShortString of discoPublic (to save logging work later). It is always // present and immutable. discoShort string // ============================================================ // mu guards all following fields; see userspaceEngine lock // ordering rules against the engine. For derphttp, mu must // be held before derphttp.Client.mu. mu sync.Mutex muCond *sync.Cond onlyTCP443 atomic.Bool closed bool // Close was called closing atomic.Bool // Close is in progress (or done) // derpCleanupTimer is the timer that fires to occasionally clean // up idle DERP connections. It's only used when there is a non-home // DERP connection in use. derpCleanupTimer *time.Timer // derpCleanupTimerArmed is whether derpCleanupTimer is // scheduled to fire within derpCleanStaleInterval. derpCleanupTimerArmed bool // periodicReSTUNTimer, when non-nil, is an AfterFunc timer // that will call Conn.doPeriodicSTUN. periodicReSTUNTimer *time.Timer // endpointsUpdateActive indicates that updateEndpoints is // currently running. It's used to deduplicate concurrent endpoint // update requests. endpointsUpdateActive bool // wantEndpointsUpdate, if non-empty, means that a new endpoints // update should begin immediately after the currently-running one // completes. It can only be non-empty if // endpointsUpdateActive==true. wantEndpointsUpdate string // true if non-empty; string is reason // lastEndpoints records the endpoints found during the previous // endpoint discovery. It's used to avoid duplicate endpoint // change notifications. lastEndpoints []tailcfg.Endpoint // lastEndpointsTime is the last time the endpoints were updated, // even if there was no change. lastEndpointsTime time.Time // onEndpointRefreshed are funcs to run (in their own goroutines) // when endpoints are refreshed. onEndpointRefreshed map[*endpoint]func() // endpointTracker tracks the set of cached endpoints that we advertise // for a period of time before withdrawing them. endpointTracker endpointTracker // peerSet is the set of peers that are currently configured in // WireGuard. These are not used to filter inbound or outbound // traffic at all, but only to track what state can be cleaned up // in other maps below that are keyed by peer public key. peerSet set.Set[key.NodePublic] // peerMap tracks the networkmap Node entity for each peer // by node key, node ID, and discovery key. peerMap peerMap // discoInfo is the state for an active DiscoKey. discoInfo map[key.DiscoPublic]*discoInfo // netInfoFunc is a callback that provides a tailcfg.NetInfo when // discovered network conditions change. // // TODO(danderson): why can't it be set at construction time? // There seem to be a few natural places in ipn/local.go to // swallow untimely invocations. netInfoFunc func(*tailcfg.NetInfo) // nil until set // netInfoLast is the NetInfo provided in the last call to // netInfoFunc. It's used to deduplicate calls to netInfoFunc. // // TODO(danderson): should all the deduping happen in // ipn/local.go? We seem to be doing dedupe at several layers, and // magicsock could do with any complexity reduction it can get. netInfoLast *tailcfg.NetInfo derpMap *tailcfg.DERPMap // nil (or zero regions/nodes) means DERP is disabled peers views.Slice[tailcfg.NodeView] // from last SetNetworkMap update lastFlags debugFlags // at time of last SetNetworkMap firstAddrForTest netip.Addr // from last SetNetworkMap update; for tests only privateKey key.NodePrivate // WireGuard private key for this node everHadKey bool // whether we ever had a non-zero private key myDerp int // nearest DERP region ID; 0 means none/unknown homeless bool // if true, don't try to find & stay conneted to a DERP home (myDerp will stay 0) derpStarted chan struct{} // closed on first connection to DERP; for tests & cleaner Close activeDerp map[int]activeDerp // DERP regionID -> connection to a node in that region prevDerp map[int]*syncs.WaitGroupChan // derpRoute contains optional alternate routes to use as an // optimization instead of contacting a peer via their home // DERP connection. If they sent us a message on a different // DERP connection (which should really only be on our DERP // home connection, or what was once our home), then we // remember that route here to optimistically use instead of // creating a new DERP connection back to their home. derpRoute map[key.NodePublic]derpRoute // peerLastDerp tracks which DERP node we last used to speak with a // peer. It's only used to quiet logging, so we only log on change. peerLastDerp map[key.NodePublic]int // wgPinger is the WireGuard only pinger used for latency measurements. wgPinger lazy.SyncValue[*ping.Pinger] // onPortUpdate is called with the new port when magicsock rebinds to // a new port. onPortUpdate func(port uint16, network string) // getPeerByKey optionally specifies a function to look up a peer's // wireguard state by its public key. If nil, it's not used. getPeerByKey func(key.NodePublic) (_ wgint.Peer, ok bool) } // SetDebugLoggingEnabled controls whether spammy debug logging is enabled. // // Note that this is currently independent from the log levels, even though // they're pretty correlated: debugging logs should be [v1] (or higher), but // some non-debug logs may also still have a [vN] annotation. The [vN] level // controls which gets shown in stderr. The dlogf method, on the other hand, // controls which gets even printed or uploaded at any level. func (c *Conn) SetDebugLoggingEnabled(v bool) { c.debugLogging.Store(v) } // dlogf logs a debug message if debug logging is enabled via SetDebugLoggingEnabled. func (c *Conn) dlogf(format string, a ...any) { if c.debugLogging.Load() { c.logf(format, a...) } } // Options contains options for Listen. type Options struct { // Logf optionally provides a log function to use. // Must not be nil. Logf logger.Logf // Port is the port to listen on. // Zero means to pick one automatically. Port uint16 // EndpointsFunc optionally provides a func to be called when // endpoints change. The called func does not own the slice. EndpointsFunc func([]tailcfg.Endpoint) // DERPActiveFunc optionally provides a func to be called when // a connection is made to a DERP server. DERPActiveFunc func() // IdleFunc optionally provides a func to return how long // it's been since a TUN packet was sent or received. IdleFunc func() time.Duration // TestOnlyPacketListener optionally specifies how to create PacketConns. // Only used by tests. TestOnlyPacketListener nettype.PacketListener // NoteRecvActivity, if provided, is a func for magicsock to call // whenever it receives a packet from a a peer if it's been more // than ~10 seconds since the last one. (10 seconds is somewhat // arbitrary; the sole user just doesn't need or want it called on // every packet, just every minute or two for WireGuard timeouts, // and 10 seconds seems like a good trade-off between often enough // and not too often.) // The provided func is likely to call back into // Conn.ParseEndpoint, which acquires Conn.mu. As such, you should // not hold Conn.mu while calling it. NoteRecvActivity func(key.NodePublic) // NetMon is the network monitor to use. // With one, the portmapper won't be used. NetMon *netmon.Monitor // ControlKnobs are the set of control knobs to use. // If nil, they're ignored and not updated. ControlKnobs *controlknobs.Knobs // OnPortUpdate is called with the new port when magicsock rebinds to // a new port. OnPortUpdate func(port uint16, network string) // PeerByKeyFunc optionally specifies a function to look up a peer's // WireGuard state by its public key. If nil, it's not used. // In regular use, this will be wgengine.(*userspaceEngine).PeerByKey. PeerByKeyFunc func(key.NodePublic) (_ wgint.Peer, ok bool) } func (o *Options) logf() logger.Logf { if o.Logf == nil { panic("must provide magicsock.Options.logf") } return o.Logf } func (o *Options) endpointsFunc() func([]tailcfg.Endpoint) { if o == nil || o.EndpointsFunc == nil { return func([]tailcfg.Endpoint) {} } return o.EndpointsFunc } func (o *Options) derpActiveFunc() func() { if o == nil || o.DERPActiveFunc == nil { return func() {} } return o.DERPActiveFunc } // newConn is the error-free, network-listening-side-effect-free based // of NewConn. Mostly for tests. func newConn() *Conn { discoPrivate := key.NewDisco() c := &Conn{ derpRecvCh: make(chan derpReadResult, 1), // must be buffered, see issue 3736 derpStarted: make(chan struct{}), peerLastDerp: make(map[key.NodePublic]int), peerMap: newPeerMap(), discoInfo: make(map[key.DiscoPublic]*discoInfo), discoPrivate: discoPrivate, discoPublic: discoPrivate.Public(), } c.discoShort = c.discoPublic.ShortString() c.bind = &connBind{Conn: c, closed: true} c.receiveBatchPool = sync.Pool{New: func() any { msgs := make([]ipv6.Message, c.bind.BatchSize()) for i := range msgs { msgs[i].Buffers = make([][]byte, 1) msgs[i].OOB = make([]byte, controlMessageSize) } batch := &receiveBatch{ msgs: msgs, } return batch }} c.muCond = sync.NewCond(&c.mu) c.networkUp.Store(true) // assume up until told otherwise return c } // NewConn creates a magic Conn listening on opts.Port. // As the set of possible endpoints for a Conn changes, the // callback opts.EndpointsFunc is called. func NewConn(opts Options) (*Conn, error) { c := newConn() c.port.Store(uint32(opts.Port)) c.controlKnobs = opts.ControlKnobs c.logf = opts.logf() c.epFunc = opts.endpointsFunc() c.derpActiveFunc = opts.derpActiveFunc() c.idleFunc = opts.IdleFunc c.testOnlyPacketListener = opts.TestOnlyPacketListener c.noteRecvActivity = opts.NoteRecvActivity portMapOpts := &portmapper.DebugKnobs{ DisableAll: func() bool { return c.onlyTCP443.Load() }, } c.portMapper = portmapper.NewClient(logger.WithPrefix(c.logf, "portmapper: "), opts.NetMon, portMapOpts, opts.ControlKnobs, c.onPortMapChanged) if opts.NetMon != nil { c.portMapper.SetGatewayLookupFunc(opts.NetMon.GatewayAndSelfIP) } c.netMon = opts.NetMon c.onPortUpdate = opts.OnPortUpdate c.getPeerByKey = opts.PeerByKeyFunc if err := c.rebind(keepCurrentPort); err != nil { return nil, err } c.connCtx, c.connCtxCancel = context.WithCancel(context.Background()) c.donec = c.connCtx.Done() c.netChecker = &netcheck.Client{ Logf: logger.WithPrefix(c.logf, "netcheck: "), NetMon: c.netMon, SendPacket: func(b []byte, ap netip.AddrPort) (int, error) { ok, err := c.sendUDP(ap, b) if !ok { return 0, err } return len(b), err }, SkipExternalNetwork: inTest(), PortMapper: c.portMapper, UseDNSCache: true, } if d4, err := c.listenRawDisco("ip4"); err == nil { c.logf("[v1] using BPF disco receiver for IPv4") c.closeDisco4 = d4 } else { c.logf("[v1] couldn't create raw v4 disco listener, using regular listener instead: %v", err) } if d6, err := c.listenRawDisco("ip6"); err == nil { c.logf("[v1] using BPF disco receiver for IPv6") c.closeDisco6 = d6 } else { c.logf("[v1] couldn't create raw v6 disco listener, using regular listener instead: %v", err) } c.logf("magicsock: disco key = %v", c.discoShort) return c, nil } // InstallCaptureHook installs a callback which is called to // log debug information into the pcap stream. This function // can be called with a nil argument to uninstall the capture // hook. func (c *Conn) InstallCaptureHook(cb capture.Callback) { c.captureHook.Store(cb) } // doPeriodicSTUN is called (in a new goroutine) by // periodicReSTUNTimer when periodic STUNs are active. func (c *Conn) doPeriodicSTUN() { c.ReSTUN("periodic") } func (c *Conn) stopPeriodicReSTUNTimerLocked() { if t := c.periodicReSTUNTimer; t != nil { t.Stop() c.periodicReSTUNTimer = nil } } // c.mu must NOT be held. func (c *Conn) updateEndpoints(why string) { metricUpdateEndpoints.Add(1) defer func() { c.mu.Lock() defer c.mu.Unlock() why := c.wantEndpointsUpdate c.wantEndpointsUpdate = "" if !c.closed { if why != "" { go c.updateEndpoints(why) return } if c.shouldDoPeriodicReSTUNLocked() { // Pick a random duration between 20 // and 26 seconds (just under 30s, a // common UDP NAT timeout on Linux, // etc) d := tstime.RandomDurationBetween(20*time.Second, 26*time.Second) if t := c.periodicReSTUNTimer; t != nil { if debugReSTUNStopOnIdle() { c.logf("resetting existing periodicSTUN to run in %v", d) } t.Reset(d) } else { if debugReSTUNStopOnIdle() { c.logf("scheduling periodicSTUN to run in %v", d) } c.periodicReSTUNTimer = time.AfterFunc(d, c.doPeriodicSTUN) } } else { if debugReSTUNStopOnIdle() { c.logf("periodic STUN idle") } c.stopPeriodicReSTUNTimerLocked() } } c.endpointsUpdateActive = false c.muCond.Broadcast() }() c.dlogf("[v1] magicsock: starting endpoint update (%s)", why) if c.noV4Send.Load() && runtime.GOOS != "js" { c.mu.Lock() closed := c.closed c.mu.Unlock() if !closed { c.logf("magicsock: last netcheck reported send error. Rebinding.") c.Rebind() } } endpoints, err := c.determineEndpoints(c.connCtx) if err != nil { c.logf("magicsock: endpoint update (%s) failed: %v", why, err) // TODO(crawshaw): are there any conditions under which // we should trigger a retry based on the error here? return } if c.setEndpoints(endpoints) { c.logEndpointChange(endpoints) c.epFunc(endpoints) } } // setEndpoints records the new endpoints, reporting whether they're changed. // It takes ownership of the slice. func (c *Conn) setEndpoints(endpoints []tailcfg.Endpoint) (changed bool) { anySTUN := false for _, ep := range endpoints { if ep.Type == tailcfg.EndpointSTUN { anySTUN = true } } c.mu.Lock() defer c.mu.Unlock() if !anySTUN && c.derpMap == nil && !inTest() { // Don't bother storing or reporting this yet. We // don't have a DERP map or any STUN entries, so we're // just starting up. A DERP map should arrive shortly // and then we'll have more interesting endpoints to // report. This saves a map update. // TODO(bradfitz): this optimization is currently // skipped during the e2e tests because they depend // too much on the exact sequence of updates. Fix the // tests. But a protocol rewrite might happen first. c.dlogf("[v1] magicsock: ignoring pre-DERP map, STUN-less endpoint update: %v", endpoints) return false } c.lastEndpointsTime = time.Now() for de, fn := range c.onEndpointRefreshed { go fn() delete(c.onEndpointRefreshed, de) } if endpointSetsEqual(endpoints, c.lastEndpoints) { return false } c.lastEndpoints = endpoints return true } // setNetInfoHavePortMap updates NetInfo.HavePortMap to true. func (c *Conn) setNetInfoHavePortMap() { c.mu.Lock() defer c.mu.Unlock() if c.netInfoLast == nil { // No NetInfo yet. Nothing to update. return } if c.netInfoLast.HavePortMap { // No change. return } ni := c.netInfoLast.Clone() ni.HavePortMap = true c.callNetInfoCallbackLocked(ni) } func (c *Conn) updateNetInfo(ctx context.Context) (*netcheck.Report, error) { c.mu.Lock() dm := c.derpMap c.mu.Unlock() if dm == nil || c.networkDown() { return new(netcheck.Report), nil } ctx, cancel := context.WithTimeout(ctx, 2*time.Second) defer cancel() report, err := c.netChecker.GetReport(ctx, dm, &netcheck.GetReportOpts{ // Pass information about the last time that we received a // frame from a DERP server to our netchecker to help avoid // flapping the home region while there's still active // communication. // // NOTE(andrew-d): I don't love that we're depending on the // health package here, but I'd rather do that and not store // the exact same state in two different places. GetLastDERPActivity: health.GetDERPRegionReceivedTime, }) if err != nil { return nil, err } c.lastNetCheckReport.Store(report) c.noV4.Store(!report.IPv4) c.noV6.Store(!report.IPv6) c.noV4Send.Store(!report.IPv4CanSend) ni := &tailcfg.NetInfo{ DERPLatency: map[string]float64{}, MappingVariesByDestIP: report.MappingVariesByDestIP, HairPinning: report.HairPinning, UPnP: report.UPnP, PMP: report.PMP, PCP: report.PCP, HavePortMap: c.portMapper.HaveMapping(), } for rid, d := range report.RegionV4Latency { ni.DERPLatency[fmt.Sprintf("%d-v4", rid)] = d.Seconds() } for rid, d := range report.RegionV6Latency { ni.DERPLatency[fmt.Sprintf("%d-v6", rid)] = d.Seconds() } ni.WorkingIPv6.Set(report.IPv6) ni.OSHasIPv6.Set(report.OSHasIPv6) ni.WorkingUDP.Set(report.UDP) ni.WorkingICMPv4.Set(report.ICMPv4) ni.PreferredDERP = c.maybeSetNearestDERP(report) ni.FirewallMode = hostinfo.FirewallMode() c.callNetInfoCallback(ni) return report, nil } // callNetInfoCallback calls the callback (if previously // registered with SetNetInfoCallback) if ni has substantially changed // since the last state. // // callNetInfoCallback takes ownership of ni. // // c.mu must NOT be held. func (c *Conn) callNetInfoCallback(ni *tailcfg.NetInfo) { c.mu.Lock() defer c.mu.Unlock() if ni.BasicallyEqual(c.netInfoLast) { return } c.callNetInfoCallbackLocked(ni) } func (c *Conn) callNetInfoCallbackLocked(ni *tailcfg.NetInfo) { c.netInfoLast = ni if c.netInfoFunc != nil { c.dlogf("[v1] magicsock: netInfo update: %+v", ni) go c.netInfoFunc(ni) } } // addValidDiscoPathForTest makes addr a validated disco address for // discoKey. It's used in tests to enable receiving of packets from // addr without having to spin up the entire active discovery // machinery. func (c *Conn) addValidDiscoPathForTest(nodeKey key.NodePublic, addr netip.AddrPort) { c.mu.Lock() defer c.mu.Unlock() c.peerMap.setNodeKeyForIPPort(addr, nodeKey) } // SetNetInfoCallback sets the func to be called whenever the network conditions // change. // // At most one func can be registered; the most recent one replaces any previous // registration. // // This is called by LocalBackend. func (c *Conn) SetNetInfoCallback(fn func(*tailcfg.NetInfo)) { if fn == nil { panic("nil NetInfoCallback") } c.mu.Lock() last := c.netInfoLast c.netInfoFunc = fn c.mu.Unlock() if last != nil { fn(last) } } // LastRecvActivityOfNodeKey describes the time we last got traffic from // this endpoint (updated every ~10 seconds). func (c *Conn) LastRecvActivityOfNodeKey(nk key.NodePublic) string { c.mu.Lock() defer c.mu.Unlock() de, ok := c.peerMap.endpointForNodeKey(nk) if !ok { return "never" } saw := de.lastRecvWG.LoadAtomic() if saw == 0 { return "never" } return mono.Since(saw).Round(time.Second).String() } // Ping handles a "tailscale ping" CLI query. func (c *Conn) Ping(peer tailcfg.NodeView, res *ipnstate.PingResult, size int, cb func(*ipnstate.PingResult)) { c.mu.Lock() defer c.mu.Unlock() if c.privateKey.IsZero() { res.Err = "local tailscaled stopped" cb(res) return } if peer.Addresses().Len() > 0 { res.NodeIP = peer.Addresses().At(0).Addr().String() } res.NodeName = peer.Name() // prefer DNS name if res.NodeName == "" { res.NodeName = peer.Hostinfo().Hostname() // else hostname } else { res.NodeName, _, _ = strings.Cut(res.NodeName, ".") } ep, ok := c.peerMap.endpointForNodeKey(peer.Key()) if !ok { res.Err = "unknown peer" cb(res) return } ep.discoPing(res, size, cb) } // c.mu must be held func (c *Conn) populateCLIPingResponseLocked(res *ipnstate.PingResult, latency time.Duration, ep netip.AddrPort) { res.LatencySeconds = latency.Seconds() if ep.Addr() != tailcfg.DerpMagicIPAddr { res.Endpoint = ep.String() return } regionID := int(ep.Port()) res.DERPRegionID = regionID res.DERPRegionCode = c.derpRegionCodeLocked(regionID) } // GetEndpointChanges returns the most recent changes for a particular // endpoint. The returned EndpointChange structs are for debug use only and // there are no guarantees about order, size, or content. func (c *Conn) GetEndpointChanges(peer tailcfg.NodeView) ([]EndpointChange, error) { c.mu.Lock() if c.privateKey.IsZero() { c.mu.Unlock() return nil, fmt.Errorf("tailscaled stopped") } ep, ok := c.peerMap.endpointForNodeKey(peer.Key()) c.mu.Unlock() if !ok { return nil, fmt.Errorf("unknown peer") } return ep.debugUpdates.GetAll(), nil } // DiscoPublicKey returns the discovery public key. func (c *Conn) DiscoPublicKey() key.DiscoPublic { return c.discoPublic } // determineEndpoints returns the machine's endpoint addresses. It // does a STUN lookup (via netcheck) to determine its public address. // // c.mu must NOT be held. func (c *Conn) determineEndpoints(ctx context.Context) ([]tailcfg.Endpoint, error) { var havePortmap bool var portmapExt netip.AddrPort if runtime.GOOS != "js" { portmapExt, havePortmap = c.portMapper.GetCachedMappingOrStartCreatingOne() } nr, err := c.updateNetInfo(ctx) if err != nil { c.logf("magicsock.Conn.determineEndpoints: updateNetInfo: %v", err) return nil, err } if runtime.GOOS == "js" { // TODO(bradfitz): why does control require an // endpoint? Otherwise it doesn't stream map responses // back. return []tailcfg.Endpoint{ { Addr: netip.MustParseAddrPort("[fe80:123:456:789::1]:12345"), Type: tailcfg.EndpointLocal, }, }, nil } var already map[netip.AddrPort]tailcfg.EndpointType // endpoint -> how it was found var eps []tailcfg.Endpoint // unique endpoints ipp := func(s string) (ipp netip.AddrPort) { ipp, _ = netip.ParseAddrPort(s) return } addAddr := func(ipp netip.AddrPort, et tailcfg.EndpointType) { if !ipp.IsValid() || (debugOmitLocalAddresses() && et == tailcfg.EndpointLocal) { return } if _, ok := already[ipp]; !ok { mak.Set(&already, ipp, et) eps = append(eps, tailcfg.Endpoint{Addr: ipp, Type: et}) } } // If we didn't have a portmap earlier, maybe it's done by now. if !havePortmap { portmapExt, havePortmap = c.portMapper.GetCachedMappingOrStartCreatingOne() } if havePortmap { addAddr(portmapExt, tailcfg.EndpointPortmapped) c.setNetInfoHavePortMap() } if nr.GlobalV4 != "" { addAddr(ipp(nr.GlobalV4), tailcfg.EndpointSTUN) // If they're behind a hard NAT and are using a fixed // port locally, assume they might've added a static // port mapping on their router to the same explicit // port that tailscaled is running with. Worst case // it's an invalid candidate mapping. if port := c.port.Load(); nr.MappingVariesByDestIP.EqualBool(true) && port != 0 { if ip, _, err := net.SplitHostPort(nr.GlobalV4); err == nil { addAddr(ipp(net.JoinHostPort(ip, strconv.Itoa(int(port)))), tailcfg.EndpointSTUN4LocalPort) } } } if nr.GlobalV6 != "" { addAddr(ipp(nr.GlobalV6), tailcfg.EndpointSTUN) } // Update our set of endpoints by adding any endpoints that we // previously found but haven't expired yet. This also updates the // cache with the set of endpoints discovered in this function. // // NOTE: we do this here and not below so that we don't cache local // endpoints; we know that the local endpoints we discover are all // possible local endpoints since we determine them by looking at the // set of addresses on our local interfaces. // // TODO(andrew): If we pull in any cached endpoints, we should probably // do something to ensure we're propagating the removal of those cached // endpoints if they do actually time out without being rediscovered. // For now, though, rely on a minor LinkChange event causing this to // re-run. eps = c.endpointTracker.update(time.Now(), eps) if localAddr := c.pconn4.LocalAddr(); localAddr.IP.IsUnspecified() { ips, loopback, err := interfaces.LocalAddresses() if err != nil { return nil, err } if len(ips) == 0 && len(eps) == 0 { // Only include loopback addresses if we have no // interfaces at all to use as endpoints and don't // have a public IPv4 or IPv6 address. This allows // for localhost testing when you're on a plane and // offline, for example. ips = loopback } for _, ip := range ips { addAddr(netip.AddrPortFrom(ip, uint16(localAddr.Port)), tailcfg.EndpointLocal) } } else { // Our local endpoint is bound to a particular address. // Do not offer addresses on other local interfaces. addAddr(ipp(localAddr.String()), tailcfg.EndpointLocal) } // Note: the endpoints are intentionally returned in priority order, // from "farthest but most reliable" to "closest but least // reliable." Addresses returned from STUN should be globally // addressable, but might go farther on the network than necessary. // Local interface addresses might have lower latency, but not be // globally addressable. // // The STUN address(es) are always first so that legacy wireguard // can use eps[0] as its only known endpoint address (although that's // obviously non-ideal). // // Despite this sorting, though, clients since 0.100 haven't relied // on the sorting order for any decisions. return eps, nil } // endpointSetsEqual reports whether x and y represent the same set of // endpoints. The order doesn't matter. // // It does not mutate the slices. func endpointSetsEqual(x, y []tailcfg.Endpoint) bool { if len(x) == len(y) { orderMatches := true for i := range x { if x[i] != y[i] { orderMatches = false break } } if orderMatches { return true } } m := map[tailcfg.Endpoint]int{} for _, v := range x { m[v] |= 1 } for _, v := range y { m[v] |= 2 } for _, n := range m { if n != 3 { return false } } return true } // LocalPort returns the current IPv4 listener's port number. func (c *Conn) LocalPort() uint16 { if runtime.GOOS == "js" { return 12345 } laddr := c.pconn4.LocalAddr() return uint16(laddr.Port) } var errNetworkDown = errors.New("magicsock: network down") func (c *Conn) networkDown() bool { return !c.networkUp.Load() } // Send implements conn.Bind. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.Send func (c *Conn) Send(buffs [][]byte, ep conn.Endpoint) error { n := int64(len(buffs)) metricSendData.Add(n) if c.networkDown() { metricSendDataNetworkDown.Add(n) return errNetworkDown } return ep.(*endpoint).send(buffs) } var errConnClosed = errors.New("Conn closed") var errDropDerpPacket = errors.New("too many DERP packets queued; dropping") var errNoUDP = errors.New("no UDP available on platform") var errUnsupportedConnType = errors.New("unsupported connection type") var ( // This acts as a compile-time check for our usage of ipv6.Message in // batchingUDPConn for both IPv6 and IPv4 operations. _ ipv6.Message = ipv4.Message{} ) func (c *Conn) sendUDPBatch(addr netip.AddrPort, buffs [][]byte) (sent bool, err error) { isIPv6 := false switch { case addr.Addr().Is4(): case addr.Addr().Is6(): isIPv6 = true default: panic("bogus sendUDPBatch addr type") } if isIPv6 { err = c.pconn6.WriteBatchTo(buffs, addr) } else { err = c.pconn4.WriteBatchTo(buffs, addr) } if err != nil { var errGSO neterror.ErrUDPGSODisabled if errors.As(err, &errGSO) { c.logf("magicsock: %s", errGSO.Error()) err = errGSO.RetryErr } } return err == nil, err } // sendUDP sends UDP packet b to ipp. // See sendAddr's docs on the return value meanings. func (c *Conn) sendUDP(ipp netip.AddrPort, b []byte) (sent bool, err error) { if runtime.GOOS == "js" { return false, errNoUDP } sent, err = c.sendUDPStd(ipp, b) if err != nil { metricSendUDPError.Add(1) } else { if sent { metricSendUDP.Add(1) } } return } // sendUDP sends UDP packet b to addr. // See sendAddr's docs on the return value meanings. func (c *Conn) sendUDPStd(addr netip.AddrPort, b []byte) (sent bool, err error) { if c.onlyTCP443.Load() { return false, nil } switch { case addr.Addr().Is4(): _, err = c.pconn4.WriteToUDPAddrPort(b, addr) if err != nil && (c.noV4.Load() || neterror.TreatAsLostUDP(err)) { return false, nil } case addr.Addr().Is6(): _, err = c.pconn6.WriteToUDPAddrPort(b, addr) if err != nil && (c.noV6.Load() || neterror.TreatAsLostUDP(err)) { return false, nil } default: panic("bogus sendUDPStd addr type") } return err == nil, err } // sendAddr sends packet b to addr, which is either a real UDP address // or a fake UDP address representing a DERP server (see derpmap.go). // The provided public key identifies the recipient. // // The returned err is whether there was an error writing when it // should've worked. // The returned sent is whether a packet went out at all. // An example of when they might be different: sending to an // IPv6 address when the local machine doesn't have IPv6 support // returns (false, nil); it's not an error, but nothing was sent. func (c *Conn) sendAddr(addr netip.AddrPort, pubKey key.NodePublic, b []byte) (sent bool, err error) { if addr.Addr() != tailcfg.DerpMagicIPAddr { return c.sendUDP(addr, b) } ch := c.derpWriteChanOfAddr(addr, pubKey) if ch == nil { metricSendDERPErrorChan.Add(1) return false, nil } // TODO(bradfitz): this makes garbage for now; we could use a // buffer pool later. Previously we passed ownership of this // to derpWriteRequest and waited for derphttp.Client.Send to // complete, but that's too slow while holding wireguard-go // internal locks. pkt := make([]byte, len(b)) copy(pkt, b) select { case <-c.donec: metricSendDERPErrorClosed.Add(1) return false, errConnClosed case ch <- derpWriteRequest{addr, pubKey, pkt}: metricSendDERPQueued.Add(1) return true, nil default: metricSendDERPErrorQueue.Add(1) // Too many writes queued. Drop packet. return false, errDropDerpPacket } } type receiveBatch struct { msgs []ipv6.Message } func (c *Conn) getReceiveBatchForBuffs(buffs [][]byte) *receiveBatch { batch := c.receiveBatchPool.Get().(*receiveBatch) for i := range buffs { batch.msgs[i].Buffers[0] = buffs[i] batch.msgs[i].OOB = batch.msgs[i].OOB[:cap(batch.msgs[i].OOB)] } return batch } func (c *Conn) putReceiveBatch(batch *receiveBatch) { for i := range batch.msgs { batch.msgs[i] = ipv6.Message{Buffers: batch.msgs[i].Buffers, OOB: batch.msgs[i].OOB} } c.receiveBatchPool.Put(batch) } // receiveIPv4 creates an IPv4 ReceiveFunc reading from c.pconn4. func (c *Conn) receiveIPv4() conn.ReceiveFunc { return c.mkReceiveFunc(&c.pconn4, &health.ReceiveIPv4, metricRecvDataIPv4) } // receiveIPv6 creates an IPv6 ReceiveFunc reading from c.pconn6. func (c *Conn) receiveIPv6() conn.ReceiveFunc { return c.mkReceiveFunc(&c.pconn6, &health.ReceiveIPv6, metricRecvDataIPv6) } // mkReceiveFunc creates a ReceiveFunc reading from ruc. // The provided healthItem and metric are updated if non-nil. func (c *Conn) mkReceiveFunc(ruc *RebindingUDPConn, healthItem *health.ReceiveFuncStats, metric *clientmetric.Metric) conn.ReceiveFunc { // epCache caches an IPPort->endpoint for hot flows. var epCache ippEndpointCache return func(buffs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) { if healthItem != nil { healthItem.Enter() defer healthItem.Exit() } if ruc == nil { panic("nil RebindingUDPConn") } batch := c.getReceiveBatchForBuffs(buffs) defer c.putReceiveBatch(batch) for { numMsgs, err := ruc.ReadBatch(batch.msgs[:len(buffs)], 0) if err != nil { if neterror.PacketWasTruncated(err) { continue } return 0, err } reportToCaller := false for i, msg := range batch.msgs[:numMsgs] { if msg.N == 0 { sizes[i] = 0 continue } ipp := msg.Addr.(*net.UDPAddr).AddrPort() if ep, ok := c.receiveIP(msg.Buffers[0][:msg.N], ipp, &epCache); ok { if metric != nil { metric.Add(1) } eps[i] = ep sizes[i] = msg.N reportToCaller = true } else { sizes[i] = 0 } } if reportToCaller { return numMsgs, nil } } } } // receiveIP is the shared bits of ReceiveIPv4 and ReceiveIPv6. // // ok is whether this read should be reported up to wireguard-go (our // caller). func (c *Conn) receiveIP(b []byte, ipp netip.AddrPort, cache *ippEndpointCache) (ep *endpoint, ok bool) { if stun.Is(b) { c.netChecker.ReceiveSTUNPacket(b, ipp) return nil, false } if c.handleDiscoMessage(b, ipp, key.NodePublic{}, discoRXPathUDP) { return nil, false } if !c.havePrivateKey.Load() { // If we have no private key, we're logged out or // stopped. Don't try to pass these wireguard packets // up to wireguard-go; it'll just complain (issue 1167). return nil, false } if cache.ipp == ipp && cache.de != nil && cache.gen == cache.de.numStopAndReset() { ep = cache.de } else { c.mu.Lock() de, ok := c.peerMap.endpointForIPPort(ipp) c.mu.Unlock() if !ok { return nil, false } cache.ipp = ipp cache.de = de cache.gen = de.numStopAndReset() ep = de } now := mono.Now() ep.lastRecvUDPAny.StoreAtomic(now) ep.noteRecvActivity(ipp, now) if stats := c.stats.Load(); stats != nil { stats.UpdateRxPhysical(ep.nodeAddr, ipp, len(b)) } return ep, true } // discoLogLevel controls the verbosity of discovery log messages. type discoLogLevel int const ( // discoLog means that a message should be logged. discoLog discoLogLevel = iota // discoVerboseLog means that a message should only be logged // in TS_DEBUG_DISCO mode. discoVerboseLog ) // TS_DISCO_PONG_IPV4_DELAY, if set, is a time.Duration string that is how much // fake latency to add before replying to disco pings. This can be used to bias // peers towards using IPv6 when both IPv4 and IPv6 are available at similar // speeds. var debugIPv4DiscoPingPenalty = envknob.RegisterDuration("TS_DISCO_PONG_IPV4_DELAY") // sendDiscoMessage sends discovery message m to dstDisco at dst. // // If dst is a DERP IP:port, then dstKey must be non-zero. // // The dstKey should only be non-zero if the dstDisco key // unambiguously maps to exactly one peer. func (c *Conn) sendDiscoMessage(dst netip.AddrPort, dstKey key.NodePublic, dstDisco key.DiscoPublic, m disco.Message, logLevel discoLogLevel) (sent bool, err error) { isDERP := dst.Addr() == tailcfg.DerpMagicIPAddr if _, isPong := m.(*disco.Pong); isPong && !isDERP && dst.Addr().Is4() { time.Sleep(debugIPv4DiscoPingPenalty()) } c.mu.Lock() if c.closed { c.mu.Unlock() return false, errConnClosed } pkt := make([]byte, 0, 512) // TODO: size it correctly? pool? if it matters. pkt = append(pkt, disco.Magic...) pkt = c.discoPublic.AppendTo(pkt) di := c.discoInfoLocked(dstDisco) c.mu.Unlock() if isDERP { metricSendDiscoDERP.Add(1) } else { metricSendDiscoUDP.Add(1) } box := di.sharedKey.Seal(m.AppendMarshal(nil)) pkt = append(pkt, box...) sent, err = c.sendAddr(dst, dstKey, pkt) if sent { if logLevel == discoLog || (logLevel == discoVerboseLog && debugDisco()) { node := "?" if !dstKey.IsZero() { node = dstKey.ShortString() } c.dlogf("[v1] magicsock: disco: %v->%v (%v, %v) sent %v len %v\n", c.discoShort, dstDisco.ShortString(), node, derpStr(dst.String()), disco.MessageSummary(m), len(pkt)) } if isDERP { metricSentDiscoDERP.Add(1) } else { metricSentDiscoUDP.Add(1) } switch m.(type) { case *disco.Ping: metricSentDiscoPing.Add(1) case *disco.Pong: metricSentDiscoPong.Add(1) case *disco.CallMeMaybe: metricSentDiscoCallMeMaybe.Add(1) } } else if err == nil { // Can't send. (e.g. no IPv6 locally) } else { if !c.networkDown() && pmtuShouldLogDiscoTxErr(m, err) { c.logf("magicsock: disco: failed to send %v to %v: %v", disco.MessageSummary(m), dst, err) } } return sent, err } type discoRXPath string const ( discoRXPathUDP discoRXPath = "UDP socket" discoRXPathDERP discoRXPath = "DERP" discoRXPathRawSocket discoRXPath = "raw socket" ) // handleDiscoMessage handles a discovery message and reports whether // msg was a Tailscale inter-node discovery message. // // A discovery message has the form: // // - magic [6]byte // - senderDiscoPubKey [32]byte // - nonce [24]byte // - naclbox of payload (see tailscale.com/disco package for inner payload format) // // For messages received over DERP, the src.Addr() will be derpMagicIP (with // src.Port() being the region ID) and the derpNodeSrc will be the node key // it was received from at the DERP layer. derpNodeSrc is zero when received // over UDP. func (c *Conn) handleDiscoMessage(msg []byte, src netip.AddrPort, derpNodeSrc key.NodePublic, via discoRXPath) (isDiscoMsg bool) { const headerLen = len(disco.Magic) + key.DiscoPublicRawLen if len(msg) < headerLen || string(msg[:len(disco.Magic)]) != disco.Magic { return false } // If the first four parts are the prefix of disco.Magic // (0x5453f09f) then it's definitely not a valid WireGuard // packet (which starts with little-endian uint32 1, 2, 3, 4). // Use naked returns for all following paths. isDiscoMsg = true sender := key.DiscoPublicFromRaw32(mem.B(msg[len(disco.Magic):headerLen])) c.mu.Lock() defer c.mu.Unlock() if c.closed { return } if debugDisco() { c.logf("magicsock: disco: got disco-looking frame from %v via %s len %v", sender.ShortString(), via, len(msg)) } if c.privateKey.IsZero() { // Ignore disco messages when we're stopped. // Still return true, to not pass it down to wireguard. return } if !c.peerMap.knownPeerDiscoKey(sender) { metricRecvDiscoBadPeer.Add(1) if debugDisco() { c.logf("magicsock: disco: ignoring disco-looking frame, don't know of key %v", sender.ShortString()) } return } isDERP := src.Addr() == tailcfg.DerpMagicIPAddr if !isDERP { // Record receive time for UDP transport packets. pi, ok := c.peerMap.byIPPort[src] if ok { pi.ep.lastRecvUDPAny.StoreAtomic(mono.Now()) } } // We're now reasonably sure we're expecting communication from // this peer, do the heavy crypto lifting to see what they want. // // From here on, peerNode and de are non-nil. di := c.discoInfoLocked(sender) sealedBox := msg[headerLen:] payload, ok := di.sharedKey.Open(sealedBox) if !ok { // This might be have been intended for a previous // disco key. When we restart we get a new disco key // and old packets might've still been in flight (or // scheduled). This is particularly the case for LANs // or non-NATed endpoints. UDP offloading on Linux // can also cause this when a disco message is // received via raw socket at the head of a coalesced // group of messages. Don't log in normal case. // Callers may choose to pass on to wireguard, in case // it's actually a wireguard packet (super unlikely, but). if debugDisco() { c.logf("magicsock: disco: failed to open naclbox from %v (wrong rcpt?) via %s", sender, via) } metricRecvDiscoBadKey.Add(1) return } // Emit information about the disco frame into the pcap stream // if a capture hook is installed. if cb := c.captureHook.Load(); cb != nil { cb(capture.PathDisco, time.Now(), disco.ToPCAPFrame(src, derpNodeSrc, payload), packet.CaptureMeta{}) } dm, err := disco.Parse(payload) if debugDisco() { c.logf("magicsock: disco: disco.Parse = %T, %v", dm, err) } if err != nil { // Couldn't parse it, but it was inside a correctly // signed box, so just ignore it, assuming it's from a // newer version of Tailscale that we don't // understand. Not even worth logging about, lest it // be too spammy for old clients. metricRecvDiscoBadParse.Add(1) return } if isDERP { metricRecvDiscoDERP.Add(1) } else { metricRecvDiscoUDP.Add(1) } switch dm := dm.(type) { case *disco.Ping: metricRecvDiscoPing.Add(1) c.handlePingLocked(dm, src, di, derpNodeSrc) case *disco.Pong: metricRecvDiscoPong.Add(1) // There might be multiple nodes for the sender's DiscoKey. // Ask each to handle it, stopping once one reports that // the Pong's TxID was theirs. c.peerMap.forEachEndpointWithDiscoKey(sender, func(ep *endpoint) (keepGoing bool) { if ep.handlePongConnLocked(dm, di, src) { return false } return true }) case *disco.CallMeMaybe: metricRecvDiscoCallMeMaybe.Add(1) if !isDERP || derpNodeSrc.IsZero() { // CallMeMaybe messages should only come via DERP. c.logf("[unexpected] CallMeMaybe packets should only come via DERP") return } nodeKey := derpNodeSrc ep, ok := c.peerMap.endpointForNodeKey(nodeKey) if !ok { metricRecvDiscoCallMeMaybeBadNode.Add(1) c.logf("magicsock: disco: ignoring CallMeMaybe from %v; %v is unknown", sender.ShortString(), derpNodeSrc.ShortString()) return } epDisco := ep.disco.Load() if epDisco == nil { return } if epDisco.key != di.discoKey { metricRecvDiscoCallMeMaybeBadDisco.Add(1) c.logf("[unexpected] CallMeMaybe from peer via DERP whose netmap discokey != disco source") return } c.dlogf("[v1] magicsock: disco: %v<-%v (%v, %v) got call-me-maybe, %d endpoints", c.discoShort, epDisco.short, ep.publicKey.ShortString(), derpStr(src.String()), len(dm.MyNumber)) go ep.handleCallMeMaybe(dm) } return } // unambiguousNodeKeyOfPingLocked attempts to look up an unambiguous mapping // from a DiscoKey dk (which sent ping dm) to a NodeKey. ok is true // if there's the NodeKey is known unambiguously. // // derpNodeSrc is non-zero if the disco ping arrived via DERP. // // c.mu must be held. func (c *Conn) unambiguousNodeKeyOfPingLocked(dm *disco.Ping, dk key.DiscoPublic, derpNodeSrc key.NodePublic) (nk key.NodePublic, ok bool) { if !derpNodeSrc.IsZero() { if ep, ok := c.peerMap.endpointForNodeKey(derpNodeSrc); ok { epDisco := ep.disco.Load() if epDisco != nil && epDisco.key == dk { return derpNodeSrc, true } } } // Pings after 1.16.0 contains its node source. See if it maps back. if !dm.NodeKey.IsZero() { if ep, ok := c.peerMap.endpointForNodeKey(dm.NodeKey); ok { epDisco := ep.disco.Load() if epDisco != nil && epDisco.key == dk { return dm.NodeKey, true } } } // If there's exactly 1 node in our netmap with DiscoKey dk, // then it's not ambiguous which node key dm was from. if set := c.peerMap.nodesOfDisco[dk]; len(set) == 1 { for nk = range set { return nk, true } } return nk, false } // di is the discoInfo of the source of the ping. // derpNodeSrc is non-zero if the ping arrived via DERP. func (c *Conn) handlePingLocked(dm *disco.Ping, src netip.AddrPort, di *discoInfo, derpNodeSrc key.NodePublic) { likelyHeartBeat := src == di.lastPingFrom && time.Since(di.lastPingTime) < 5*time.Second di.lastPingFrom = src di.lastPingTime = time.Now() isDerp := src.Addr() == tailcfg.DerpMagicIPAddr // If we can figure out with certainty which node key this disco // message is for, eagerly update our IP<>node and disco<>node // mappings to make p2p path discovery faster in simple // cases. Without this, disco would still work, but would be // reliant on DERP call-me-maybe to establish the disco<>node // mapping, and on subsequent disco handlePongConnLocked to establish // the IP<>disco mapping. if nk, ok := c.unambiguousNodeKeyOfPingLocked(dm, di.discoKey, derpNodeSrc); ok { if !isDerp { c.peerMap.setNodeKeyForIPPort(src, nk) } } // If we got a ping over DERP, then derpNodeSrc is non-zero and we reply // over DERP (in which case ipDst is also a DERP address). // But if the ping was over UDP (ipDst is not a DERP address), then dstKey // will be zero here, but that's fine: sendDiscoMessage only requires // a dstKey if the dst ip:port is DERP. dstKey := derpNodeSrc // Remember this route if not present. var numNodes int var dup bool if isDerp { if ep, ok := c.peerMap.endpointForNodeKey(derpNodeSrc); ok { if ep.addCandidateEndpoint(src, dm.TxID) { return } numNodes = 1 } } else { c.peerMap.forEachEndpointWithDiscoKey(di.discoKey, func(ep *endpoint) (keepGoing bool) { if ep.addCandidateEndpoint(src, dm.TxID) { dup = true return false } numNodes++ if numNodes == 1 && dstKey.IsZero() { dstKey = ep.publicKey } return true }) if dup { return } if numNodes > 1 { // Zero it out if it's ambiguous, so sendDiscoMessage logging // isn't confusing. dstKey = key.NodePublic{} } } if numNodes == 0 { c.logf("[unexpected] got disco ping from %v/%v for node not in peers", src, derpNodeSrc) return } if !likelyHeartBeat || debugDisco() { pingNodeSrcStr := dstKey.ShortString() if numNodes > 1 { pingNodeSrcStr = "[one-of-multi]" } c.dlogf("[v1] magicsock: disco: %v<-%v (%v, %v) got ping tx=%x padding=%v", c.discoShort, di.discoShort, pingNodeSrcStr, src, dm.TxID[:6], dm.Padding) } ipDst := src discoDest := di.discoKey go c.sendDiscoMessage(ipDst, dstKey, discoDest, &disco.Pong{ TxID: dm.TxID, Src: src, }, discoVerboseLog) } // enqueueCallMeMaybe schedules a send of disco.CallMeMaybe to de via derpAddr // once we know that our STUN endpoint is fresh. // // derpAddr is de.derpAddr at the time of send. It's assumed the peer won't be // flipping primary DERPs in the 0-30ms it takes to confirm our STUN endpoint. // If they do, traffic will just go over DERP for a bit longer until the next // discovery round. func (c *Conn) enqueueCallMeMaybe(derpAddr netip.AddrPort, de *endpoint) { c.mu.Lock() defer c.mu.Unlock() epDisco := de.disco.Load() if epDisco == nil { return } if !c.lastEndpointsTime.After(time.Now().Add(-endpointsFreshEnoughDuration)) { c.dlogf("[v1] magicsock: want call-me-maybe but endpoints stale; restunning") mak.Set(&c.onEndpointRefreshed, de, func() { c.dlogf("[v1] magicsock: STUN done; sending call-me-maybe to %v %v", epDisco.short, de.publicKey.ShortString()) c.enqueueCallMeMaybe(derpAddr, de) }) // TODO(bradfitz): make a new 'reSTUNQuickly' method // that passes down a do-a-lite-netcheck flag down to // netcheck that does 1 (or 2 max) STUN queries // (UDP-only, not HTTPs) to find our port mapping to // our home DERP and maybe one other. For now we do a // "full" ReSTUN which may or may not be a full one // (depending on age) and may do HTTPS timing queries // (if UDP is blocked). Good enough for now. go c.ReSTUN("refresh-for-peering") return } eps := make([]netip.AddrPort, 0, len(c.lastEndpoints)) for _, ep := range c.lastEndpoints { eps = append(eps, ep.Addr) } go de.c.sendDiscoMessage(derpAddr, de.publicKey, epDisco.key, &disco.CallMeMaybe{MyNumber: eps}, discoLog) if debugSendCallMeUnknownPeer() { // Send a callMeMaybe packet to a non-existent peer unknownKey := key.NewNode().Public() c.logf("magicsock: sending CallMeMaybe to unknown peer per TS_DEBUG_SEND_CALLME_UNKNOWN_PEER") go de.c.sendDiscoMessage(derpAddr, unknownKey, epDisco.key, &disco.CallMeMaybe{MyNumber: eps}, discoLog) } } // discoInfoLocked returns the previous or new discoInfo for k. // // c.mu must be held. func (c *Conn) discoInfoLocked(k key.DiscoPublic) *discoInfo { di, ok := c.discoInfo[k] if !ok { di = &discoInfo{ discoKey: k, discoShort: k.ShortString(), sharedKey: c.discoPrivate.Shared(k), } c.discoInfo[k] = di } return di } func (c *Conn) SetNetworkUp(up bool) { c.mu.Lock() defer c.mu.Unlock() if c.networkUp.Load() == up { return } c.logf("magicsock: SetNetworkUp(%v)", up) c.networkUp.Store(up) if up { c.startDerpHomeConnectLocked() } else { c.portMapper.NoteNetworkDown() c.closeAllDerpLocked("network-down") } } // SetPreferredPort sets the connection's preferred local port. func (c *Conn) SetPreferredPort(port uint16) { if uint16(c.port.Load()) == port { return } c.port.Store(uint32(port)) if err := c.rebind(dropCurrentPort); err != nil { c.logf("%v", err) return } c.resetEndpointStates() } // SetPrivateKey sets the connection's private key. // // This is only used to be able prove our identity when connecting to // DERP servers. // // If the private key changes, any DERP connections are torn down & // recreated when needed. func (c *Conn) SetPrivateKey(privateKey key.NodePrivate) error { c.mu.Lock() defer c.mu.Unlock() oldKey, newKey := c.privateKey, privateKey if newKey.Equal(oldKey) { return nil } c.privateKey = newKey c.havePrivateKey.Store(!newKey.IsZero()) if newKey.IsZero() { c.publicKeyAtomic.Store(key.NodePublic{}) } else { c.publicKeyAtomic.Store(newKey.Public()) } if oldKey.IsZero() { c.everHadKey = true c.logf("magicsock: SetPrivateKey called (init)") go c.ReSTUN("set-private-key") } else if newKey.IsZero() { c.logf("magicsock: SetPrivateKey called (zeroed)") c.closeAllDerpLocked("zero-private-key") c.stopPeriodicReSTUNTimerLocked() c.onEndpointRefreshed = nil } else { c.logf("magicsock: SetPrivateKey called (changed)") c.closeAllDerpLocked("new-private-key") } // Key changed. Close existing DERP connections and reconnect to home. if c.myDerp != 0 && !newKey.IsZero() { c.logf("magicsock: private key changed, reconnecting to home derp-%d", c.myDerp) c.startDerpHomeConnectLocked() } if newKey.IsZero() { c.peerMap.forEachEndpoint(func(ep *endpoint) { ep.stopAndReset() }) } return nil } // UpdatePeers is called when the set of WireGuard peers changes. It // then removes any state for old peers. // // The caller passes ownership of newPeers map to UpdatePeers. func (c *Conn) UpdatePeers(newPeers set.Set[key.NodePublic]) { c.mu.Lock() defer c.mu.Unlock() oldPeers := c.peerSet c.peerSet = newPeers // Clean up any key.NodePublic-keyed maps for peers that no longer // exist. for peer := range oldPeers { if !newPeers.Contains(peer) { delete(c.derpRoute, peer) delete(c.peerLastDerp, peer) } } if len(oldPeers) == 0 && len(newPeers) > 0 { go c.ReSTUN("non-zero-peers") } } func nodesEqual(x, y views.Slice[tailcfg.NodeView]) bool { if x.Len() != y.Len() { return false } for i := range x.Len() { if !x.At(i).Equal(y.At(i)) { return false } } return true } // debugRingBufferSize returns a maximum size for our set of endpoint ring // buffers by assuming that a single large update is ~500 bytes, and that we // want to not use more than 1MiB of memory on phones / 4MiB on other devices. // Calculate the per-endpoint ring buffer size by dividing that out, but always // storing at least two entries. func debugRingBufferSize(numPeers int) int { const defaultVal = 2 if numPeers == 0 { return defaultVal } var maxRingBufferSize int if runtime.GOOS == "ios" || runtime.GOOS == "android" { maxRingBufferSize = 1 << 20 // But as of 2024-03-20, we now just disable the ring buffer entirely // on mobile as it hadn't proven useful enough to justify even 1 MB. } else { maxRingBufferSize = 4 << 20 } if v := debugRingBufferMaxSizeBytes(); v > 0 { maxRingBufferSize = v } const averageRingBufferElemSize = 512 return max(defaultVal, maxRingBufferSize/(averageRingBufferElemSize*numPeers)) } // debugFlags are the debug flags in use by the magicsock package. // They might be set by envknob and/or controlknob. // The value is comparable. type debugFlags struct { heartbeatDisabled bool probeUDPLifetimeOn bool } func (c *Conn) debugFlagsLocked() (f debugFlags) { f.heartbeatDisabled = debugEnableSilentDisco() || c.silentDiscoOn.Load() f.probeUDPLifetimeOn = c.probeUDPLifetimeOn.Load() return } // SetSilentDisco toggles silent disco based on v. func (c *Conn) SetSilentDisco(v bool) { old := c.silentDiscoOn.Swap(v) if old == v { return } c.mu.Lock() defer c.mu.Unlock() c.peerMap.forEachEndpoint(func(ep *endpoint) { ep.setHeartbeatDisabled(v) }) } // SilentDisco returns true if silent disco is enabled, otherwise false. func (c *Conn) SilentDisco() bool { c.mu.Lock() defer c.mu.Unlock() flags := c.debugFlagsLocked() return flags.heartbeatDisabled } // SetProbeUDPLifetime toggles probing of UDP lifetime based on v. func (c *Conn) SetProbeUDPLifetime(v bool) { old := c.probeUDPLifetimeOn.Swap(v) if old == v { return } c.mu.Lock() defer c.mu.Unlock() c.peerMap.forEachEndpoint(func(ep *endpoint) { ep.setProbeUDPLifetimeOn(v) }) } // SetNetworkMap is called when the control client gets a new network // map from the control server. It must always be non-nil. // // It should not use the DERPMap field of NetworkMap; that's // conditionally sent to SetDERPMap instead. func (c *Conn) SetNetworkMap(nm *netmap.NetworkMap) { c.mu.Lock() defer c.mu.Unlock() if c.closed { return } priorPeers := c.peers metricNumPeers.Set(int64(len(nm.Peers))) // Update c.netMap regardless, before the following early return. curPeers := views.SliceOf(nm.Peers) c.peers = curPeers flags := c.debugFlagsLocked() if addrs := nm.GetAddresses(); addrs.Len() > 0 { c.firstAddrForTest = addrs.At(0).Addr() } else { c.firstAddrForTest = netip.Addr{} } if nodesEqual(priorPeers, curPeers) && c.lastFlags == flags { // The rest of this function is all adjusting state for peers that have // changed. But if the set of peers is equal and the debug flags (for // silent disco and probe UDP lifetime) haven't changed, there is no // need to do anything else. return } c.lastFlags = flags c.logf("[v1] magicsock: got updated network map; %d peers", len(nm.Peers)) entriesPerBuffer := debugRingBufferSize(len(nm.Peers)) // Try a pass of just upserting nodes and creating missing // endpoints. If the set of nodes is the same, this is an // efficient alloc-free update. If the set of nodes is different, // we'll fall through to the next pass, which allocates but can // handle full set updates. for _, n := range nm.Peers { if n.ID() == 0 { devPanicf("node with zero ID") continue } if n.Key().IsZero() { devPanicf("node with zero key") continue } ep, ok := c.peerMap.endpointForNodeID(n.ID()) if ok && ep.publicKey != n.Key() { // The node rotated public keys. Delete the old endpoint and create // it anew. c.peerMap.deleteEndpoint(ep) ok = false } if ok { // At this point we're modifying an existing endpoint (ep) whose // public key and nodeID match n. Its other fields (such as disco // key or endpoints) might've changed. if n.DiscoKey().IsZero() && !n.IsWireGuardOnly() { // Discokey transitioned from non-zero to zero? This should not // happen in the wild, however it could mean: // 1. A node was downgraded from post 0.100 to pre 0.100. // 2. A Tailscale node key was extracted and used on a // non-Tailscale node (should not enter here due to the // IsWireGuardOnly check) // 3. The server is misbehaving. c.peerMap.deleteEndpoint(ep) continue } var oldDiscoKey key.DiscoPublic if epDisco := ep.disco.Load(); epDisco != nil { oldDiscoKey = epDisco.key } ep.updateFromNode(n, flags.heartbeatDisabled, flags.probeUDPLifetimeOn) c.peerMap.upsertEndpoint(ep, oldDiscoKey) // maybe update discokey mappings in peerMap continue } if ep, ok := c.peerMap.endpointForNodeKey(n.Key()); ok { // At this point n.Key() should be for a key we've never seen before. If // ok was true above, it was an update to an existing matching key and // we don't get this far. If ok was false above, that means it's a key // that differs from the one the NodeID had. But double check. if ep.nodeID != n.ID() { // Server error. devPanicf("public key moved between nodeIDs (old=%v new=%v, key=%s)", ep.nodeID, n.ID(), n.Key().String()) } else { // Internal data structures out of sync. devPanicf("public key found in peerMap but not by nodeID") } continue } if n.DiscoKey().IsZero() && !n.IsWireGuardOnly() { // Ancient pre-0.100 node, which does not have a disco key. // No longer supported. continue } ep = &endpoint{ c: c, nodeID: n.ID(), publicKey: n.Key(), publicKeyHex: n.Key().UntypedHexString(), sentPing: map[stun.TxID]sentPing{}, endpointState: map[netip.AddrPort]*endpointState{}, heartbeatDisabled: flags.heartbeatDisabled, isWireguardOnly: n.IsWireGuardOnly(), } switch runtime.GOOS { case "ios", "android": // Omit, to save memory. Prior to 2024-03-20 we used to limit it to // ~1MB on mobile but we never used the data so the memory was just // wasted. default: ep.debugUpdates = ringbuffer.New[EndpointChange](entriesPerBuffer) } if n.Addresses().Len() > 0 { ep.nodeAddr = n.Addresses().At(0).Addr() } ep.initFakeUDPAddr() if n.DiscoKey().IsZero() { ep.disco.Store(nil) } else { ep.disco.Store(&endpointDisco{ key: n.DiscoKey(), short: n.DiscoKey().ShortString(), }) } if debugPeerMap() { c.logEndpointCreated(n) } ep.updateFromNode(n, flags.heartbeatDisabled, flags.probeUDPLifetimeOn) c.peerMap.upsertEndpoint(ep, key.DiscoPublic{}) } // If the set of nodes changed since the last SetNetworkMap, the // upsert loop just above made c.peerMap contain the union of the // old and new peers - which will be larger than the set from the // current netmap. If that happens, go through the allocful // deletion path to clean up moribund nodes. if c.peerMap.nodeCount() != len(nm.Peers) { keep := set.Set[key.NodePublic]{} for _, n := range nm.Peers { keep.Add(n.Key()) } c.peerMap.forEachEndpoint(func(ep *endpoint) { if !keep.Contains(ep.publicKey) { c.peerMap.deleteEndpoint(ep) } }) } // discokeys might have changed in the above. Discard unused info. for dk := range c.discoInfo { if !c.peerMap.knownPeerDiscoKey(dk) { delete(c.discoInfo, dk) } } } func devPanicf(format string, a ...any) { if testenv.InTest() || envknob.CrashOnUnexpected() { panic(fmt.Sprintf(format, a...)) } } func (c *Conn) logEndpointCreated(n tailcfg.NodeView) { c.logf("magicsock: created endpoint key=%s: disco=%s; %v", n.Key().ShortString(), n.DiscoKey().ShortString(), logger.ArgWriter(func(w *bufio.Writer) { const derpPrefix = "127.3.3.40:" if strings.HasPrefix(n.DERP(), derpPrefix) { ipp, _ := netip.ParseAddrPort(n.DERP()) regionID := int(ipp.Port()) code := c.derpRegionCodeLocked(regionID) if code != "" { code = "(" + code + ")" } fmt.Fprintf(w, "derp=%v%s ", regionID, code) } for i := range n.AllowedIPs().Len() { a := n.AllowedIPs().At(i) if a.IsSingleIP() { fmt.Fprintf(w, "aip=%v ", a.Addr()) } else { fmt.Fprintf(w, "aip=%v ", a) } } for i := range n.Endpoints().Len() { ep := n.Endpoints().At(i) fmt.Fprintf(w, "ep=%v ", ep) } })) } func (c *Conn) logEndpointChange(endpoints []tailcfg.Endpoint) { c.logf("magicsock: endpoints changed: %s", logger.ArgWriter(func(buf *bufio.Writer) { for i, ep := range endpoints { if i > 0 { buf.WriteString(", ") } fmt.Fprintf(buf, "%s (%s)", ep.Addr, ep.Type) } })) } // Bind returns the wireguard-go conn.Bind for c. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind func (c *Conn) Bind() conn.Bind { return c.bind } // connBind is a wireguard-go conn.Bind for a Conn. // It bridges the behavior of wireguard-go and a Conn. // wireguard-go calls Close then Open on device.Up. // That won't work well for a Conn, which is only closed on shutdown. // The subsequent Close is a real close. type connBind struct { *Conn mu sync.Mutex closed bool } // This is a compile-time assertion that connBind implements the wireguard-go // conn.Bind interface. var _ conn.Bind = (*connBind)(nil) // BatchSize returns the number of buffers expected to be passed to // the ReceiveFuncs, and the maximum expected to be passed to SendBatch. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.BatchSize func (c *connBind) BatchSize() int { // TODO(raggi): determine by properties rather than hardcoding platform behavior switch runtime.GOOS { case "linux": return conn.IdealBatchSize default: return 1 } } // Open is called by WireGuard to create a UDP binding. // The ignoredPort comes from wireguard-go, via the wgcfg config. // We ignore that port value here, since we have the local port available easily. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.Open func (c *connBind) Open(ignoredPort uint16) ([]conn.ReceiveFunc, uint16, error) { c.mu.Lock() defer c.mu.Unlock() if !c.closed { return nil, 0, errors.New("magicsock: connBind already open") } c.closed = false fns := []conn.ReceiveFunc{c.receiveIPv4(), c.receiveIPv6(), c.receiveDERP} if runtime.GOOS == "js" { fns = []conn.ReceiveFunc{c.receiveDERP} } // TODO: Combine receiveIPv4 and receiveIPv6 and receiveIP into a single // closure that closes over a *RebindingUDPConn? return fns, c.LocalPort(), nil } // SetMark is used by wireguard-go to set a mark bit for packets to avoid routing loops. // We handle that ourselves elsewhere. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.SetMark func (c *connBind) SetMark(value uint32) error { return nil } // Close closes the connBind, unless it is already closed. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.Close func (c *connBind) Close() error { c.mu.Lock() defer c.mu.Unlock() if c.closed { return nil } c.closed = true // Unblock all outstanding receives. c.pconn4.Close() c.pconn6.Close() if c.closeDisco4 != nil { c.closeDisco4.Close() } if c.closeDisco6 != nil { c.closeDisco6.Close() } // Send an empty read result to unblock receiveDERP, // which will then check connBind.Closed. // connBind.Closed takes c.mu, but c.derpRecvCh is buffered. c.derpRecvCh <- derpReadResult{} return nil } // isClosed reports whether c is closed. func (c *connBind) isClosed() bool { c.mu.Lock() defer c.mu.Unlock() return c.closed } // Close closes the connection. // // Only the first close does anything. Any later closes return nil. func (c *Conn) Close() error { c.mu.Lock() defer c.mu.Unlock() if c.closed { return nil } c.closing.Store(true) if c.derpCleanupTimerArmed { c.derpCleanupTimer.Stop() } c.stopPeriodicReSTUNTimerLocked() c.portMapper.Close() c.peerMap.forEachEndpoint(func(ep *endpoint) { ep.stopAndReset() }) c.closed = true c.connCtxCancel() c.closeAllDerpLocked("conn-close") // Ignore errors from c.pconnN.Close. // They will frequently have been closed already by a call to connBind.Close. c.pconn6.Close() c.pconn4.Close() if c.closeDisco4 != nil { c.closeDisco4.Close() } if c.closeDisco6 != nil { c.closeDisco6.Close() } // Wait on goroutines updating right at the end, once everything is // already closed. We want everything else in the Conn to be // consistently in the closed state before we release mu to wait // on the endpoint updater & derphttp.Connect. for c.goroutinesRunningLocked() { c.muCond.Wait() } if pinger := c.getPinger(); pinger != nil { pinger.Close() } return nil } func (c *Conn) goroutinesRunningLocked() bool { if c.endpointsUpdateActive { return true } // The goroutine running dc.Connect in derpWriteChanOfAddr may linger // and appear to leak, as observed in https://github.com/tailscale/tailscale/issues/554. // This is despite the underlying context being cancelled by connCtxCancel above. // To avoid this condition, we must wait on derpStarted here // to ensure that this goroutine has exited by the time Close returns. // We only do this if derpWriteChanOfAddr has executed at least once: // on the first run, it sets firstDerp := true and spawns the aforementioned goroutine. // To detect this, we check activeDerp, which is initialized to non-nil on the first run. if c.activeDerp != nil { select { case <-c.derpStarted: default: return true } } return false } func (c *Conn) shouldDoPeriodicReSTUNLocked() bool { if c.networkDown() || c.homeless { return false } if len(c.peerSet) == 0 || c.privateKey.IsZero() { // If no peers, not worth doing. // Also don't if there's no key (not running). return false } if f := c.idleFunc; f != nil { idleFor := f() if debugReSTUNStopOnIdle() { c.logf("magicsock: periodicReSTUN: idle for %v", idleFor.Round(time.Second)) } if idleFor > sessionActiveTimeout { if c.controlKnobs != nil && c.controlKnobs.ForceBackgroundSTUN.Load() { // Overridden by control. return true } return false } } return true } func (c *Conn) onPortMapChanged() { c.ReSTUN("portmap-changed") } // ReSTUN triggers an address discovery. // The provided why string is for debug logging only. func (c *Conn) ReSTUN(why string) { c.mu.Lock() defer c.mu.Unlock() if c.closed { // raced with a shutdown. return } metricReSTUNCalls.Add(1) // If the user stopped the app, stop doing work. (When the // user stops Tailscale via the GUI apps, ipn/local.go // reconfigures the engine with a zero private key.) // // This used to just check c.privateKey.IsZero, but that broke // some end-to-end tests that didn't ever set a private // key somehow. So for now, only stop doing work if we ever // had a key, which helps real users, but appeases tests for // now. TODO: rewrite those tests to be less brittle or more // realistic. if c.privateKey.IsZero() && c.everHadKey { c.logf("magicsock: ReSTUN(%q) ignored; stopped, no private key", why) return } if c.endpointsUpdateActive { if c.wantEndpointsUpdate != why { c.dlogf("[v1] magicsock: ReSTUN: endpoint update active, need another later (%q)", why) c.wantEndpointsUpdate = why } } else { c.endpointsUpdateActive = true go c.updateEndpoints(why) } } // listenPacket opens a packet listener. // The network must be "udp4" or "udp6". func (c *Conn) listenPacket(network string, port uint16) (nettype.PacketConn, error) { ctx := context.Background() // unused without DNS name to resolve if network == "udp4" { ctx = sockstats.WithSockStats(ctx, sockstats.LabelMagicsockConnUDP4, c.logf) } else { ctx = sockstats.WithSockStats(ctx, sockstats.LabelMagicsockConnUDP6, c.logf) } addr := net.JoinHostPort("", fmt.Sprint(port)) if c.testOnlyPacketListener != nil { return nettype.MakePacketListenerWithNetIP(c.testOnlyPacketListener).ListenPacket(ctx, network, addr) } return nettype.MakePacketListenerWithNetIP(netns.Listener(c.logf, c.netMon)).ListenPacket(ctx, network, addr) } // bindSocket initializes rucPtr if necessary and binds a UDP socket to it. // Network indicates the UDP socket type; it must be "udp4" or "udp6". // If rucPtr had an existing UDP socket bound, it closes that socket. // The caller is responsible for informing the portMapper of any changes. // If curPortFate is set to dropCurrentPort, no attempt is made to reuse // the current port. func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate currentPortFate) error { if debugBindSocket() { c.logf("magicsock: bindSocket: network=%q curPortFate=%v", network, curPortFate) } // Hold the ruc lock the entire time, so that the close+bind is atomic // from the perspective of ruc receive functions. ruc.mu.Lock() defer ruc.mu.Unlock() if runtime.GOOS == "js" { ruc.setConnLocked(newBlockForeverConn(), "", c.bind.BatchSize()) return nil } if debugAlwaysDERP() { c.logf("disabled %v per TS_DEBUG_ALWAYS_USE_DERP", network) ruc.setConnLocked(newBlockForeverConn(), "", c.bind.BatchSize()) return nil } // Build a list of preferred ports. // Best is the port that the user requested. // Second best is the port that is currently in use. // If those fail, fall back to 0. var ports []uint16 if port := uint16(c.port.Load()); port != 0 { ports = append(ports, port) } if ruc.pconn != nil && curPortFate == keepCurrentPort { curPort := uint16(ruc.localAddrLocked().Port) ports = append(ports, curPort) } ports = append(ports, 0) // Remove duplicates. (All duplicates are consecutive.) uniq.ModifySlice(&ports) if debugBindSocket() { c.logf("magicsock: bindSocket: candidate ports: %+v", ports) } var pconn nettype.PacketConn for _, port := range ports { // Close the existing conn, in case it is sitting on the port we want. err := ruc.closeLocked() if err != nil && !errors.Is(err, net.ErrClosed) && !errors.Is(err, errNilPConn) { c.logf("magicsock: bindSocket %v close failed: %v", network, err) } // Open a new one with the desired port. pconn, err = c.listenPacket(network, port) if err != nil { c.logf("magicsock: unable to bind %v port %d: %v", network, port, err) continue } if c.onPortUpdate != nil { _, gotPortStr, err := net.SplitHostPort(pconn.LocalAddr().String()) if err != nil { c.logf("could not parse port from %s: %w", pconn.LocalAddr().String(), err) } else { gotPort, err := strconv.ParseUint(gotPortStr, 10, 16) if err != nil { c.logf("could not parse port from %s: %w", gotPort, err) } else { c.onPortUpdate(uint16(gotPort), network) } } } trySetSocketBuffer(pconn, c.logf) // Success. if debugBindSocket() { c.logf("magicsock: bindSocket: successfully listened %v port %d", network, port) } ruc.setConnLocked(pconn, network, c.bind.BatchSize()) if network == "udp4" { health.SetUDP4Unbound(false) } return nil } // Failed to bind, including on port 0 (!). // Set pconn to a dummy conn whose reads block until closed. // This keeps the receive funcs alive for a future in which // we get a link change and we can try binding again. ruc.setConnLocked(newBlockForeverConn(), "", c.bind.BatchSize()) if network == "udp4" { health.SetUDP4Unbound(true) } return fmt.Errorf("failed to bind any ports (tried %v)", ports) } type currentPortFate uint8 const ( keepCurrentPort = currentPortFate(0) dropCurrentPort = currentPortFate(1) ) // rebind closes and re-binds the UDP sockets. // We consider it successful if we manage to bind the IPv4 socket. func (c *Conn) rebind(curPortFate currentPortFate) error { if err := c.bindSocket(&c.pconn6, "udp6", curPortFate); err != nil { c.logf("magicsock: Rebind ignoring IPv6 bind failure: %v", err) } if err := c.bindSocket(&c.pconn4, "udp4", curPortFate); err != nil { return fmt.Errorf("magicsock: Rebind IPv4 failed: %w", err) } c.portMapper.SetLocalPort(c.LocalPort()) c.UpdatePMTUD() return nil } // Rebind closes and re-binds the UDP sockets and resets the DERP connection. // It should be followed by a call to ReSTUN. func (c *Conn) Rebind() { metricRebindCalls.Add(1) if err := c.rebind(keepCurrentPort); err != nil { c.logf("%v", err) return } var ifIPs []netip.Prefix if c.netMon != nil { st := c.netMon.InterfaceState() defIf := st.DefaultRouteInterface ifIPs = st.InterfaceIPs[defIf] c.logf("Rebind; defIf=%q, ips=%v", defIf, ifIPs) } c.maybeCloseDERPsOnRebind(ifIPs) c.resetEndpointStates() } // resetEndpointStates resets the preferred address for all peers. // This is called when connectivity changes enough that we no longer // trust the old routes. func (c *Conn) resetEndpointStates() { c.mu.Lock() defer c.mu.Unlock() c.peerMap.forEachEndpoint(func(ep *endpoint) { ep.noteConnectivityChange() }) } // packIPPort packs an IPPort into the form wanted by WireGuard. func packIPPort(ua netip.AddrPort) []byte { ip := ua.Addr().Unmap() a := ip.As16() ipb := a[:] if ip.Is4() { ipb = ipb[12:] } b := make([]byte, 0, len(ipb)+2) b = append(b, ipb...) b = append(b, byte(ua.Port())) b = append(b, byte(ua.Port()>>8)) return b } // ParseEndpoint implements conn.Bind; it's called by WireGuard to connect to an endpoint. // // See https://pkg.go.dev/golang.zx2c4.com/wireguard/conn#Bind.ParseEndpoint func (c *Conn) ParseEndpoint(nodeKeyStr string) (conn.Endpoint, error) { k, err := key.ParseNodePublicUntyped(mem.S(nodeKeyStr)) if err != nil { return nil, fmt.Errorf("magicsock: ParseEndpoint: parse failed on %q: %w", nodeKeyStr, err) } c.mu.Lock() defer c.mu.Unlock() if c.closed { return nil, errConnClosed } ep, ok := c.peerMap.endpointForNodeKey(k) if !ok { // We should never be telling WireGuard about a new peer // before magicsock knows about it. c.logf("[unexpected] magicsock: ParseEndpoint: unknown node key=%s", k.ShortString()) return nil, fmt.Errorf("magicsock: ParseEndpoint: unknown peer %q", k.ShortString()) } return ep, nil } func (c *batchingUDPConn) writeBatch(msgs []ipv6.Message) error { var head int for { n, err := c.xpc.WriteBatch(msgs[head:], 0) if err != nil || n == len(msgs[head:]) { // Returning the number of packets written would require // unraveling individual msg len and gso size during a coalesced // write. The top of the call stack disregards partial success, // so keep this simple for now. return err } head += n } } // splitCoalescedMessages splits coalesced messages from the tail of dst // beginning at index 'firstMsgAt' into the head of the same slice. It reports // the number of elements to evaluate in msgs for nonzero len (msgs[i].N). An // error is returned if a socket control message cannot be parsed or a split // operation would overflow msgs. func (c *batchingUDPConn) splitCoalescedMessages(msgs []ipv6.Message, firstMsgAt int) (n int, err error) { for i := firstMsgAt; i < len(msgs); i++ { msg := &msgs[i] if msg.N == 0 { return n, err } var ( gsoSize int start int end = msg.N numToSplit = 1 ) gsoSize, err = c.getGSOSizeFromControl(msg.OOB[:msg.NN]) if err != nil { return n, err } if gsoSize > 0 { numToSplit = (msg.N + gsoSize - 1) / gsoSize end = gsoSize } for j := 0; j < numToSplit; j++ { if n > i { return n, errors.New("splitting coalesced packet resulted in overflow") } copied := copy(msgs[n].Buffers[0], msg.Buffers[0][start:end]) msgs[n].N = copied msgs[n].Addr = msg.Addr start = end end += gsoSize if end > msg.N { end = msg.N } n++ } if i != n-1 { // It is legal for bytes to move within msg.Buffers[0] as a result // of splitting, so we only zero the source msg len when it is not // the destination of the last split operation above. msg.N = 0 } } return n, nil } func (c *batchingUDPConn) ReadBatch(msgs []ipv6.Message, flags int) (n int, err error) { if !c.rxOffload || len(msgs) < 2 { return c.xpc.ReadBatch(msgs, flags) } // Read into the tail of msgs, split into the head. readAt := len(msgs) - 2 numRead, err := c.xpc.ReadBatch(msgs[readAt:], 0) if err != nil || numRead == 0 { return 0, err } return c.splitCoalescedMessages(msgs, readAt) } func (c *batchingUDPConn) LocalAddr() net.Addr { return c.pc.LocalAddr().(*net.UDPAddr) } func (c *batchingUDPConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) { return c.pc.WriteToUDPAddrPort(b, addr) } func (c *batchingUDPConn) Close() error { return c.pc.Close() } // tryUpgradeToBatchingUDPConn probes the capabilities of the OS and pconn, and // upgrades pconn to a *batchingUDPConn if appropriate. func tryUpgradeToBatchingUDPConn(pconn nettype.PacketConn, network string, batchSize int) nettype.PacketConn { if network != "udp4" && network != "udp6" { return pconn } if runtime.GOOS != "linux" { return pconn } if strings.HasPrefix(hostinfo.GetOSVersion(), "2.") { // recvmmsg/sendmmsg were added in 2.6.33, but we support down to // 2.6.32 for old NAS devices. See https://github.com/tailscale/tailscale/issues/6807. // As a cheap heuristic: if the Linux kernel starts with "2", just // consider it too old for mmsg. Nobody who cares about performance runs // such ancient kernels. UDP offload was added much later, so no // upgrades are available. return pconn } uc, ok := pconn.(*net.UDPConn) if !ok { return pconn } b := &batchingUDPConn{ pc: pconn, getGSOSizeFromControl: getGSOSizeFromControl, setGSOSizeInControl: setGSOSizeInControl, sendBatchPool: sync.Pool{ New: func() any { ua := &net.UDPAddr{ IP: make([]byte, 16), } msgs := make([]ipv6.Message, batchSize) for i := range msgs { msgs[i].Buffers = make([][]byte, 1) msgs[i].Addr = ua msgs[i].OOB = make([]byte, controlMessageSize) } return &sendBatch{ ua: ua, msgs: msgs, } }, }, } switch network { case "udp4": b.xpc = ipv4.NewPacketConn(uc) case "udp6": b.xpc = ipv6.NewPacketConn(uc) default: panic("bogus network") } var txOffload bool txOffload, b.rxOffload = tryEnableUDPOffload(uc) b.txOffload.Store(txOffload) return b } func newBlockForeverConn() *blockForeverConn { c := new(blockForeverConn) c.cond = sync.NewCond(&c.mu) return c } // simpleDur rounds d such that it stringifies to something short. func simpleDur(d time.Duration) time.Duration { if d < time.Second { return d.Round(time.Millisecond) } if d < time.Minute { return d.Round(time.Second) } return d.Round(time.Minute) } // UpdateNetmapDelta implements controlclient.NetmapDeltaUpdater. func (c *Conn) UpdateNetmapDelta(muts []netmap.NodeMutation) (handled bool) { c.mu.Lock() defer c.mu.Unlock() for _, m := range muts { nodeID := m.NodeIDBeingMutated() ep, ok := c.peerMap.endpointForNodeID(nodeID) if !ok { continue } switch m := m.(type) { case netmap.NodeMutationDERPHome: ep.setDERPHome(uint16(m.DERPRegion)) case netmap.NodeMutationEndpoints: ep.mu.Lock() ep.setEndpointsLocked(views.SliceOf(m.Endpoints)) ep.mu.Unlock() } } return true } // UpdateStatus implements the interface nede by ipnstate.StatusBuilder. // // This method adds in the magicsock-specific information only. Most // of the status is otherwise populated by LocalBackend. func (c *Conn) UpdateStatus(sb *ipnstate.StatusBuilder) { c.mu.Lock() defer c.mu.Unlock() sb.MutateSelfStatus(func(ss *ipnstate.PeerStatus) { ss.Addrs = make([]string, 0, len(c.lastEndpoints)) for _, ep := range c.lastEndpoints { ss.Addrs = append(ss.Addrs, ep.Addr.String()) } if c.derpMap != nil { if reg, ok := c.derpMap.Regions[c.myDerp]; ok { ss.Relay = reg.RegionCode } } }) if sb.WantPeers { c.peerMap.forEachEndpoint(func(ep *endpoint) { ps := &ipnstate.PeerStatus{InMagicSock: true} ep.populatePeerStatus(ps) sb.AddPeer(ep.publicKey, ps) }) } c.foreachActiveDerpSortedLocked(func(node int, ad activeDerp) { // TODO(bradfitz): add a method to ipnstate.StatusBuilder // to include all the DERP connections we have open // and add it here. See the other caller of foreachActiveDerpSortedLocked. }) } // SetStatistics specifies a per-connection statistics aggregator. // Nil may be specified to disable statistics gathering. func (c *Conn) SetStatistics(stats *connstats.Statistics) { c.stats.Store(stats) } // SetHomeless sets whether magicsock should idle harder and not have a DERP // home connection active and not search for its nearest DERP home. In this // homeless mode, the node is unreachable by others. func (c *Conn) SetHomeless(v bool) { c.mu.Lock() defer c.mu.Unlock() c.homeless = v if v && c.myDerp != 0 { oldHome := c.myDerp c.myDerp = 0 c.closeDerpLocked(oldHome, "set-homeless") } if !v { go c.updateEndpoints("set-homeless-disabled") } } const ( // sessionActiveTimeout is how long since the last activity we // try to keep an established endpoint peering alive. // It's also the idle time at which we stop doing STUN queries to // keep NAT mappings alive. sessionActiveTimeout = 45 * time.Second // upgradeInterval is how often we try to upgrade to a better path // even if we have some non-DERP route that works. upgradeInterval = 1 * time.Minute // heartbeatInterval is how often pings to the best UDP address // are sent. heartbeatInterval = 3 * time.Second // trustUDPAddrDuration is how long we trust a UDP address as the exclusive // path (without using DERP) without having heard a Pong reply. trustUDPAddrDuration = 6500 * time.Millisecond // goodEnoughLatency is the latency at or under which we don't // try to upgrade to a better path. goodEnoughLatency = 5 * time.Millisecond // endpointsFreshEnoughDuration is how long we consider a // STUN-derived endpoint valid for. UDP NAT mappings typically // expire at 30 seconds, so this is a few seconds shy of that. endpointsFreshEnoughDuration = 27 * time.Second ) // Constants that are variable for testing. var ( // pingTimeoutDuration is how long we wait for a pong reply before // assuming it's never coming. pingTimeoutDuration = 5 * time.Second // discoPingInterval is the minimum time between pings // to an endpoint. (Except in the case of CallMeMaybe frames // resetting the counter, as the first pings likely didn't through // the firewall) discoPingInterval = 5 * time.Second // wireguardPingInterval is the minimum time between pings to an endpoint. // Pings are only sent if we have not observed bidirectional traffic with an // endpoint in at least this duration. wireguardPingInterval = 5 * time.Second ) // indexSentinelDeleted is the temporary value that endpointState.index takes while // a endpoint's endpoints are being updated from a new network map. const indexSentinelDeleted = -1 // getPinger lazily instantiates a pinger and returns it, if it was // already instantiated it returns the existing one. func (c *Conn) getPinger() *ping.Pinger { return c.wgPinger.Get(func() *ping.Pinger { return ping.New(c.connCtx, c.dlogf, netns.Listener(c.logf, c.netMon)) }) } // DebugPickNewDERP picks a new DERP random home temporarily (even if just for // seconds) and reports it to control. It exists to test DERP home changes and // netmap deltas, etc. It serves no useful user purpose. func (c *Conn) DebugPickNewDERP() error { c.mu.Lock() defer c.mu.Unlock() dm := c.derpMap if dm == nil { return errors.New("no derpmap") } if c.netInfoLast == nil { return errors.New("no netinfo") } for _, r := range dm.Regions { if r.RegionID == c.myDerp { continue } c.logf("magicsock: [debug] switching derp home to random %v (%v)", r.RegionID, r.RegionCode) go c.setNearestDERP(r.RegionID) ni2 := c.netInfoLast.Clone() ni2.PreferredDERP = r.RegionID c.callNetInfoCallbackLocked(ni2) return nil } return errors.New("too few regions") } // portableTrySetSocketBuffer sets SO_SNDBUF and SO_RECVBUF on pconn to socketBufferSize, // logging an error if it occurs. func portableTrySetSocketBuffer(pconn nettype.PacketConn, logf logger.Logf) { if c, ok := pconn.(*net.UDPConn); ok { // Attempt to increase the buffer size, and allow failures. if err := c.SetReadBuffer(socketBufferSize); err != nil { logf("magicsock: failed to set UDP read buffer size to %d: %v", socketBufferSize, err) } if err := c.SetWriteBuffer(socketBufferSize); err != nil { logf("magicsock: failed to set UDP write buffer size to %d: %v", socketBufferSize, err) } } } // derpStr replaces DERP IPs in s with "derp-". func derpStr(s string) string { return strings.ReplaceAll(s, "127.3.3.40:", "derp-") } // ippEndpointCache is a mutex-free single-element cache, mapping from // a single netip.AddrPort to a single endpoint. type ippEndpointCache struct { ipp netip.AddrPort gen int64 de *endpoint } // discoInfo is the info and state for the DiscoKey // in the Conn.discoInfo map key. // // Note that a DiscoKey does not necessarily map to exactly one // node. In the case of shared nodes and users switching accounts, two // nodes in the NetMap may legitimately have the same DiscoKey. As // such, no fields in here should be considered node-specific. type discoInfo struct { // discoKey is the same as the Conn.discoInfo map key, // just so you can pass around a *discoInfo alone. // Not modified once initialized. discoKey key.DiscoPublic // discoShort is discoKey.ShortString(). // Not modified once initialized; discoShort string // sharedKey is the precomputed key for communication with the // peer that has the DiscoKey used to look up this *discoInfo in // Conn.discoInfo. // Not modified once initialized. sharedKey key.DiscoShared // Mutable fields follow, owned by Conn.mu: // lastPingFrom is the src of a ping for discoKey. lastPingFrom netip.AddrPort // lastPingTime is the last time of a ping for discoKey. lastPingTime time.Time } var ( metricNumPeers = clientmetric.NewGauge("magicsock_netmap_num_peers") metricNumDERPConns = clientmetric.NewGauge("magicsock_num_derp_conns") metricRebindCalls = clientmetric.NewCounter("magicsock_rebind_calls") metricReSTUNCalls = clientmetric.NewCounter("magicsock_restun_calls") metricUpdateEndpoints = clientmetric.NewCounter("magicsock_update_endpoints") // Sends (data or disco) metricSendDERPQueued = clientmetric.NewCounter("magicsock_send_derp_queued") metricSendDERPErrorChan = clientmetric.NewCounter("magicsock_send_derp_error_chan") metricSendDERPErrorClosed = clientmetric.NewCounter("magicsock_send_derp_error_closed") metricSendDERPErrorQueue = clientmetric.NewCounter("magicsock_send_derp_error_queue") metricSendUDP = clientmetric.NewCounter("magicsock_send_udp") metricSendUDPError = clientmetric.NewCounter("magicsock_send_udp_error") metricSendDERP = clientmetric.NewCounter("magicsock_send_derp") metricSendDERPError = clientmetric.NewCounter("magicsock_send_derp_error") // Data packets (non-disco) metricSendData = clientmetric.NewCounter("magicsock_send_data") metricSendDataNetworkDown = clientmetric.NewCounter("magicsock_send_data_network_down") metricRecvDataDERP = clientmetric.NewCounter("magicsock_recv_data_derp") metricRecvDataIPv4 = clientmetric.NewCounter("magicsock_recv_data_ipv4") metricRecvDataIPv6 = clientmetric.NewCounter("magicsock_recv_data_ipv6") // Disco packets metricSendDiscoUDP = clientmetric.NewCounter("magicsock_disco_send_udp") metricSendDiscoDERP = clientmetric.NewCounter("magicsock_disco_send_derp") metricSentDiscoUDP = clientmetric.NewCounter("magicsock_disco_sent_udp") metricSentDiscoDERP = clientmetric.NewCounter("magicsock_disco_sent_derp") metricSentDiscoPing = clientmetric.NewCounter("magicsock_disco_sent_ping") metricSentDiscoPong = clientmetric.NewCounter("magicsock_disco_sent_pong") metricSentDiscoPeerMTUProbes = clientmetric.NewCounter("magicsock_disco_sent_peer_mtu_probes") metricSentDiscoPeerMTUProbeBytes = clientmetric.NewCounter("magicsock_disco_sent_peer_mtu_probe_bytes") metricSentDiscoCallMeMaybe = clientmetric.NewCounter("magicsock_disco_sent_callmemaybe") metricRecvDiscoBadPeer = clientmetric.NewCounter("magicsock_disco_recv_bad_peer") metricRecvDiscoBadKey = clientmetric.NewCounter("magicsock_disco_recv_bad_key") metricRecvDiscoBadParse = clientmetric.NewCounter("magicsock_disco_recv_bad_parse") metricRecvDiscoUDP = clientmetric.NewCounter("magicsock_disco_recv_udp") metricRecvDiscoDERP = clientmetric.NewCounter("magicsock_disco_recv_derp") metricRecvDiscoPing = clientmetric.NewCounter("magicsock_disco_recv_ping") metricRecvDiscoPong = clientmetric.NewCounter("magicsock_disco_recv_pong") metricRecvDiscoCallMeMaybe = clientmetric.NewCounter("magicsock_disco_recv_callmemaybe") metricRecvDiscoCallMeMaybeBadNode = clientmetric.NewCounter("magicsock_disco_recv_callmemaybe_bad_node") metricRecvDiscoCallMeMaybeBadDisco = clientmetric.NewCounter("magicsock_disco_recv_callmemaybe_bad_disco") metricRecvDiscoDERPPeerNotHere = clientmetric.NewCounter("magicsock_disco_recv_derp_peer_not_here") metricRecvDiscoDERPPeerGoneUnknown = clientmetric.NewCounter("magicsock_disco_recv_derp_peer_gone_unknown") // metricDERPHomeChange is how many times our DERP home region DI has // changed from non-zero to a different non-zero. metricDERPHomeChange = clientmetric.NewCounter("derp_home_change") // Disco packets received bpf read path //lint:ignore U1000 used on Linux only metricRecvDiscoPacketIPv4 = clientmetric.NewCounter("magicsock_disco_recv_bpf_ipv4") //lint:ignore U1000 used on Linux only metricRecvDiscoPacketIPv6 = clientmetric.NewCounter("magicsock_disco_recv_bpf_ipv6") // metricMaxPeerMTUProbed is the largest peer path MTU we successfully probed. metricMaxPeerMTUProbed = clientmetric.NewGauge("magicsock_max_peer_mtu_probed") // metricRecvDiscoPeerMTUProbesByMTU collects the number of times we // received an peer MTU probe response for a given MTU size. // TODO: add proper support for label maps in clientmetrics metricRecvDiscoPeerMTUProbesByMTU syncs.Map[string, *clientmetric.Metric] // metricUDPLifetime* metrics pertain to UDP lifetime probing, see type // probeUDPLifetime. These metrics assume a static/default configuration for // probing (defaultProbeUDPLifetimeConfig) until we disseminate // ProbeUDPLifetimeConfig from control, and have lifetime management (GC old // metrics) of clientmetrics or similar. metricUDPLifetimeCliffsScheduled = newUDPLifetimeCounter("magicsock_udp_lifetime_cliffs_scheduled") metricUDPLifetimeCliffsCompleted = newUDPLifetimeCounter("magicsock_udp_lifetime_cliffs_completed") metricUDPLifetimeCliffsMissed = newUDPLifetimeCounter("magicsock_udp_lifetime_cliffs_missed") metricUDPLifetimeCliffsRescheduled = newUDPLifetimeCounter("magicsock_udp_lifetime_cliffs_rescheduled") metricUDPLifetimeCyclesCompleted = newUDPLifetimeCounter("magicsock_udp_lifetime_cycles_completed") metricUDPLifetimeCycleCompleteNoCliffReached = newUDPLifetimeCounter("magicsock_udp_lifetime_cycle_complete_no_cliff_reached") metricUDPLifetimeCycleCompleteAt10sCliff = newUDPLifetimeCounter("magicsock_udp_lifetime_cycle_complete_at_10s_cliff") metricUDPLifetimeCycleCompleteAt30sCliff = newUDPLifetimeCounter("magicsock_udp_lifetime_cycle_complete_at_30s_cliff") metricUDPLifetimeCycleCompleteAt60sCliff = newUDPLifetimeCounter("magicsock_udp_lifetime_cycle_complete_at_60s_cliff") ) // newUDPLifetimeCounter returns a new *clientmetric.Metric with the provided // name combined with a suffix representing defaultProbeUDPLifetimeConfig. func newUDPLifetimeCounter(name string) *clientmetric.Metric { var sb strings.Builder for _, cliff := range defaultProbeUDPLifetimeConfig.Cliffs { sb.WriteString(fmt.Sprintf("%ds", cliff/time.Second)) } sb.WriteString(fmt.Sprintf("_%ds", defaultProbeUDPLifetimeConfig.CycleCanStartEvery/time.Second)) return clientmetric.NewCounter(fmt.Sprintf("%s_%s", name, sb.String())) } func getPeerMTUsProbedMetric(mtu tstun.WireMTU) *clientmetric.Metric { key := fmt.Sprintf("magicsock_recv_disco_peer_mtu_probes_by_mtu_%d", mtu) mm, _ := metricRecvDiscoPeerMTUProbesByMTU.LoadOrInit(key, func() *clientmetric.Metric { return clientmetric.NewCounter(key) }) return mm }