// 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" crand "crypto/rand" "encoding/binary" "errors" "fmt" "hash/fnv" "io" "math" "math/rand" "net" "net/netip" "reflect" "runtime" "sort" "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/controlclient" "tailscale.com/derp" "tailscale.com/derp/derphttp" "tailscale.com/disco" "tailscale.com/envknob" "tailscale.com/health" "tailscale.com/hostinfo" "tailscale.com/ipn/ipnstate" "tailscale.com/logtail/backoff" "tailscale.com/net/connstats" "tailscale.com/net/dnscache" "tailscale.com/net/interfaces" "tailscale.com/net/netaddr" "tailscale.com/net/netcheck" "tailscale.com/net/neterror" "tailscale.com/net/netns" "tailscale.com/net/portmapper" "tailscale.com/net/stun" "tailscale.com/net/tsaddr" "tailscale.com/syncs" "tailscale.com/tailcfg" "tailscale.com/tstime" "tailscale.com/tstime/mono" "tailscale.com/types/key" "tailscale.com/types/logger" "tailscale.com/types/netmap" "tailscale.com/types/nettype" "tailscale.com/util/clientmetric" "tailscale.com/util/mak" "tailscale.com/util/uniq" "tailscale.com/version" "tailscale.com/wgengine/monitor" ) 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 ) // useDerpRoute reports whether magicsock should enable the DERP // return path optimization (Issue 150). func useDerpRoute() bool { if b, ok := debugUseDerpRoute().Get(); ok { return b } ob := controlclient.DERPRouteFlag() if v, ok := ob.Get(); ok { return v } return true // as of 1.21.x } // peerInfo is all the information magicsock tracks about a particular // peer. type peerInfo struct { ep *endpoint // always non-nil. // ipPorts is an inverted version of peerMap.byIPPort (below), so // that when we're deleting this node, we can rapidly find out the // keys that need deleting from peerMap.byIPPort without having to // iterate over every IPPort known for any peer. ipPorts map[netip.AddrPort]bool } func newPeerInfo(ep *endpoint) *peerInfo { return &peerInfo{ ep: ep, ipPorts: map[netip.AddrPort]bool{}, } } // peerMap is an index of peerInfos by node (WireGuard) key, disco // key, and discovered ip:port endpoints. // // Doesn't do any locking, all access must be done with Conn.mu held. type peerMap struct { byNodeKey map[key.NodePublic]*peerInfo byIPPort map[netip.AddrPort]*peerInfo // nodesOfDisco contains the set of nodes that are using a // DiscoKey. Usually those sets will be just one node. nodesOfDisco map[key.DiscoPublic]map[key.NodePublic]bool } func newPeerMap() peerMap { return peerMap{ byNodeKey: map[key.NodePublic]*peerInfo{}, byIPPort: map[netip.AddrPort]*peerInfo{}, nodesOfDisco: map[key.DiscoPublic]map[key.NodePublic]bool{}, } } // nodeCount returns the number of nodes currently in m. func (m *peerMap) nodeCount() int { return len(m.byNodeKey) } // anyEndpointForDiscoKey reports whether there exists any // peers in the netmap with dk as their DiscoKey. func (m *peerMap) anyEndpointForDiscoKey(dk key.DiscoPublic) bool { return len(m.nodesOfDisco[dk]) > 0 } // endpointForNodeKey returns the endpoint for nk, or nil if // nk is not known to us. func (m *peerMap) endpointForNodeKey(nk key.NodePublic) (ep *endpoint, ok bool) { if nk.IsZero() { return nil, false } if info, ok := m.byNodeKey[nk]; ok { return info.ep, true } return nil, false } // endpointForIPPort returns the endpoint for the peer we // believe to be at ipp, or nil if we don't know of any such peer. func (m *peerMap) endpointForIPPort(ipp netip.AddrPort) (ep *endpoint, ok bool) { if info, ok := m.byIPPort[ipp]; ok { return info.ep, true } return nil, false } // forEachEndpoint invokes f on every endpoint in m. func (m *peerMap) forEachEndpoint(f func(ep *endpoint)) { for _, pi := range m.byNodeKey { f(pi.ep) } } // forEachEndpointWithDiscoKey invokes f on every endpoint in m that has the // provided DiscoKey until f returns false or there are no endpoints left to // iterate. func (m *peerMap) forEachEndpointWithDiscoKey(dk key.DiscoPublic, f func(*endpoint) (keepGoing bool)) { for nk := range m.nodesOfDisco[dk] { pi, ok := m.byNodeKey[nk] if !ok { // Unexpected. Data structures would have to // be out of sync. But we don't have a logger // here to log [unexpected], so just skip. // Maybe log later once peerMap is merged back // into Conn. continue } if !f(pi.ep) { return } } } // upsertEndpoint stores endpoint in the peerInfo for // ep.publicKey, and updates indexes. m must already have a // tailcfg.Node for ep.publicKey. func (m *peerMap) upsertEndpoint(ep *endpoint, oldDiscoKey key.DiscoPublic) { if m.byNodeKey[ep.publicKey] == nil { m.byNodeKey[ep.publicKey] = newPeerInfo(ep) } if oldDiscoKey != ep.discoKey { delete(m.nodesOfDisco[oldDiscoKey], ep.publicKey) } set := m.nodesOfDisco[ep.discoKey] if set == nil { set = map[key.NodePublic]bool{} m.nodesOfDisco[ep.discoKey] = set } set[ep.publicKey] = true } // setNodeKeyForIPPort makes future peer lookups by ipp return the // same endpoint as a lookup by nk. // // This should only be called with a fully verified mapping of ipp to // nk, because calling this function defines the endpoint we hand to // WireGuard for packets received from ipp. func (m *peerMap) setNodeKeyForIPPort(ipp netip.AddrPort, nk key.NodePublic) { if pi := m.byIPPort[ipp]; pi != nil { delete(pi.ipPorts, ipp) delete(m.byIPPort, ipp) } if pi, ok := m.byNodeKey[nk]; ok { pi.ipPorts[ipp] = true m.byIPPort[ipp] = pi } } // deleteEndpoint deletes the peerInfo associated with ep, and // updates indexes. func (m *peerMap) deleteEndpoint(ep *endpoint) { if ep == nil { return } ep.stopAndReset() pi := m.byNodeKey[ep.publicKey] delete(m.nodesOfDisco[ep.discoKey], ep.publicKey) delete(m.byNodeKey, ep.publicKey) if pi == nil { // Kneejerk paranoia from earlier issue 2801. // Unexpected. But no logger plumbed here to log so. return } for ip := range pi.ipPorts { delete(m.byIPPort, ip) } } // A Conn routes UDP packets and actively manages a list of its endpoints. // It implements wireguard/conn.Bind. 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 linkMon *monitor.Mon // 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 sendBatchPool 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 // stunReceiveFunc holds the current STUN packet processing func. // Its Loaded value is always non-nil. stunReceiveFunc syncs.AtomicValue[func(p []byte, fromAddr netip.AddrPort)] // 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 // ippEndpoint4 and ippEndpoint6 are owned by receiveIPv4 and // receiveIPv6, respectively, to cache an IPPort->endpoint for // hot flows. ippEndpoint4, ippEndpoint6 ippEndpointCache // ============================================================ // 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 // 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 // stats maintains per-connection counters. stats atomic.Pointer[connstats.Statistics] // ============================================================ // 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 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() // 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 map[key.NodePublic]struct{} // discoPrivate is the private naclbox key used for active // discovery traffic. It's created once near (but not during) // construction. discoPrivate key.DiscoPrivate discoPublic key.DiscoPublic // public of discoPrivate discoShort string // ShortString of discoPublic (to save logging work later) // nodeOfDisco tracks the networkmap Node entity for each peer // 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 netMap *netmap.NetworkMap 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 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 } // 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...) } } // derpRoute is a route entry for a public key, saying that a certain // peer should be available at DERP node derpID, as long as the // current connection for that derpID is dc. (but dc should not be // used to write directly; it's owned by the read/write loops) type derpRoute struct { derpID int dc *derphttp.Client // don't use directly; see comment above } // removeDerpPeerRoute removes a DERP route entry previously added by addDerpPeerRoute. func (c *Conn) removeDerpPeerRoute(peer key.NodePublic, derpID int, dc *derphttp.Client) { c.mu.Lock() defer c.mu.Unlock() r2 := derpRoute{derpID, dc} if r, ok := c.derpRoute[peer]; ok && r == r2 { delete(c.derpRoute, peer) } } // addDerpPeerRoute adds a DERP route entry, noting that peer was seen // on DERP node derpID, at least on the connection identified by dc. // See issue 150 for details. func (c *Conn) addDerpPeerRoute(peer key.NodePublic, derpID int, dc *derphttp.Client) { c.mu.Lock() defer c.mu.Unlock() mak.Set(&c.derpRoute, peer, derpRoute{derpID, dc}) } var derpMagicIPAddr = netip.MustParseAddr(tailcfg.DerpMagicIP) // activeDerp contains fields for an active DERP connection. type activeDerp struct { c *derphttp.Client cancel context.CancelFunc writeCh chan<- derpWriteRequest // lastWrite is the time of the last request for its write // channel (currently even if there was no write). // It is always non-nil and initialized to a non-zero Time. lastWrite *time.Time createTime time.Time } // 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) // LinkMonitor is the link monitor to use. // With one, the portmapper won't be used. LinkMonitor *monitor.Mon } 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 { 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), } 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) } batch := &receiveBatch{ msgs: msgs, } return batch }} c.sendBatchPool = sync.Pool{New: func() any { ua := &net.UDPAddr{ IP: make([]byte, 16), } msgs := make([]ipv6.Message, c.bind.BatchSize()) for i := range msgs { msgs[i].Buffers = make([][]byte, 1) msgs[i].Addr = ua } return &sendBatch{ ua: ua, msgs: msgs, } }} 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.logf = opts.logf() c.epFunc = opts.endpointsFunc() c.derpActiveFunc = opts.derpActiveFunc() c.idleFunc = opts.IdleFunc c.testOnlyPacketListener = opts.TestOnlyPacketListener c.noteRecvActivity = opts.NoteRecvActivity c.portMapper = portmapper.NewClient(logger.WithPrefix(c.logf, "portmapper: "), c.onPortMapChanged) if opts.LinkMonitor != nil { c.portMapper.SetGatewayLookupFunc(opts.LinkMonitor.GatewayAndSelfIP) } c.linkMon = opts.LinkMonitor 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: "), GetSTUNConn4: func() netcheck.STUNConn { return &c.pconn4 }, GetSTUNConn6: func() netcheck.STUNConn { return &c.pconn6 }, SkipExternalNetwork: inTest(), PortMapper: c.portMapper, } c.ignoreSTUNPackets() 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) } return c, nil } // ignoreSTUNPackets sets a STUN packet processing func that does nothing. func (c *Conn) ignoreSTUNPackets() { c.stunReceiveFunc.Store(func([]byte, netip.AddrPort) {}) } // 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() c.stunReceiveFunc.Store(c.netChecker.ReceiveSTUNPacket) defer c.ignoreSTUNPackets() report, err := c.netChecker.GetReport(ctx, dm) 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 = report.PreferredDERP if ni.PreferredDERP == 0 { // Perhaps UDP is blocked. Pick a deterministic but arbitrary // one. ni.PreferredDERP = c.pickDERPFallback() } if !c.setNearestDERP(ni.PreferredDERP) { ni.PreferredDERP = 0 } // TODO: set link type c.callNetInfoCallback(ni) return report, nil } var processStartUnixNano = time.Now().UnixNano() // pickDERPFallback returns a non-zero but deterministic DERP node to // connect to. This is only used if netcheck couldn't find the // nearest one (for instance, if UDP is blocked and thus STUN latency // checks aren't working). // // c.mu must NOT be held. func (c *Conn) pickDERPFallback() int { c.mu.Lock() defer c.mu.Unlock() if !c.wantDerpLocked() { return 0 } ids := c.derpMap.RegionIDs() if len(ids) == 0 { // No DERP regions in non-nil map. return 0 } // TODO: figure out which DERP region most of our peers are using, // and use that region as our fallback. // // If we already had selected something in the past and it has any // peers, we want to stay on it. If there are no peers at all, // stay on whatever DERP we previously picked. If we need to pick // one and have no peer info, pick a region randomly. // // We used to do the above for legacy clients, but never updated // it for disco. if c.myDerp != 0 { return c.myDerp } h := fnv.New64() fmt.Fprintf(h, "%p/%d", c, processStartUnixNano) // arbitrary return ids[rand.New(rand.NewSource(int64(h.Sum64()))).Intn(len(ids))] } // callNetInfoCallback calls the NetInfo 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) } 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.lastRecv.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.Node, res *ipnstate.PingResult, cb func(*ipnstate.PingResult)) { c.mu.Lock() defer c.mu.Unlock() if c.privateKey.IsZero() { res.Err = "local tailscaled stopped" cb(res) return } if len(peer.Addresses) > 0 { res.NodeIP = peer.Addresses[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.cliPing(res, 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() != derpMagicIPAddr { res.Endpoint = ep.String() return } regionID := int(ep.Port()) res.DERPRegionID = regionID res.DERPRegionCode = c.derpRegionCodeLocked(regionID) } func (c *Conn) derpRegionCodeLocked(regionID int) string { if c.derpMap == nil { return "" } if dr, ok := c.derpMap.Regions[regionID]; ok { return dr.RegionCode } return "" } // DiscoPublicKey returns the discovery public key. func (c *Conn) DiscoPublicKey() key.DiscoPublic { c.mu.Lock() defer c.mu.Unlock() if c.discoPrivate.IsZero() { priv := key.NewDisco() c.discoPrivate = priv c.discoPublic = priv.Public() c.discoShort = c.discoPublic.ShortString() c.logf("magicsock: disco key = %v", c.discoShort) } return c.discoPublic } // c.mu must NOT be held. func (c *Conn) setNearestDERP(derpNum int) (wantDERP bool) { c.mu.Lock() defer c.mu.Unlock() if !c.wantDerpLocked() { c.myDerp = 0 health.SetMagicSockDERPHome(0) return false } if derpNum == c.myDerp { // No change. return true } if c.myDerp != 0 && derpNum != 0 { metricDERPHomeChange.Add(1) } c.myDerp = derpNum health.SetMagicSockDERPHome(derpNum) if c.privateKey.IsZero() { // No private key yet, so DERP connections won't come up anyway. // Return early rather than ultimately log a couple lines of noise. return true } // On change, notify all currently connected DERP servers and // start connecting to our home DERP if we are not already. dr := c.derpMap.Regions[derpNum] if dr == nil { c.logf("[unexpected] magicsock: derpMap.Regions[%v] is nil", derpNum) } else { c.logf("magicsock: home is now derp-%v (%v)", derpNum, c.derpMap.Regions[derpNum].RegionCode) } for i, ad := range c.activeDerp { go ad.c.NotePreferred(i == c.myDerp) } c.goDerpConnect(derpNum) return true } // startDerpHomeConnectLocked starts connecting to our DERP home, if any. // // c.mu must be held. func (c *Conn) startDerpHomeConnectLocked() { c.goDerpConnect(c.myDerp) } // goDerpConnect starts a goroutine to start connecting to the given // DERP node. // // c.mu may be held, but does not need to be. func (c *Conn) goDerpConnect(node int) { if node == 0 { return } go c.derpWriteChanOfAddr(netip.AddrPortFrom(derpMagicIPAddr, uint16(node)), key.NodePublic{}) } // 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) } c.ignoreSTUNPackets() 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() } 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 ( // This acts as a compile-time check for our usage of ipv6.Message in // udpConnWithBatchOps for both IPv6 and IPv4 operations. _ ipv6.Message = ipv4.Message{} ) type sendBatch struct { ua *net.UDPAddr msgs []ipv6.Message // ipv4.Message and ipv6.Message are the same underlying type } func (c *Conn) sendUDPBatch(addr netip.AddrPort, buffs [][]byte) (sent bool, err error) { batch := c.sendBatchPool.Get().(*sendBatch) defer c.sendBatchPool.Put(batch) isIPv6 := false switch { case addr.Addr().Is4(): case addr.Addr().Is6(): isIPv6 = true default: panic("bogus sendUDPBatch addr type") } as16 := addr.Addr().As16() copy(batch.ua.IP, as16[:]) batch.ua.Port = int(addr.Port()) for i, buff := range buffs { batch.msgs[i].Buffers[0] = buff batch.msgs[i].Addr = batch.ua } if isIPv6 { _, err = c.pconn6.WriteBatch(batch.msgs[:len(buffs)], 0) } else { _, err = c.pconn4.WriteBatch(batch.msgs[:len(buffs)], 0) } 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) { 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() != 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 } } // bufferedDerpWritesBeforeDrop is how many packets writes can be // queued up the DERP client to write on the wire before we start // dropping. // // TODO: this is currently arbitrary. Figure out something better? const bufferedDerpWritesBeforeDrop = 32 // derpWriteChanOfAddr returns a DERP client for fake UDP addresses that // represent DERP servers, creating them as necessary. For real UDP // addresses, it returns nil. // // If peer is non-zero, it can be used to find an active reverse // path, without using addr. func (c *Conn) derpWriteChanOfAddr(addr netip.AddrPort, peer key.NodePublic) chan<- derpWriteRequest { if addr.Addr() != derpMagicIPAddr { return nil } regionID := int(addr.Port()) if c.networkDown() { return nil } c.mu.Lock() defer c.mu.Unlock() if !c.wantDerpLocked() || c.closed { return nil } if c.derpMap == nil || c.derpMap.Regions[regionID] == nil { return nil } if c.privateKey.IsZero() { c.logf("magicsock: DERP lookup of %v with no private key; ignoring", addr) return nil } // See if we have a connection open to that DERP node ID // first. If so, might as well use it. (It's a little // arbitrary whether we use this one vs. the reverse route // below when we have both.) ad, ok := c.activeDerp[regionID] if ok { *ad.lastWrite = time.Now() c.setPeerLastDerpLocked(peer, regionID, regionID) return ad.writeCh } // If we don't have an open connection to the peer's home DERP // node, see if we have an open connection to a DERP node // where we'd heard from that peer already. For instance, // perhaps peer's home is Frankfurt, but they dialed our home DERP // node in SF to reach us, so we can reply to them using our // SF connection rather than dialing Frankfurt. (Issue 150) if !peer.IsZero() && useDerpRoute() { if r, ok := c.derpRoute[peer]; ok { if ad, ok := c.activeDerp[r.derpID]; ok && ad.c == r.dc { c.setPeerLastDerpLocked(peer, r.derpID, regionID) *ad.lastWrite = time.Now() return ad.writeCh } } } why := "home-keep-alive" if !peer.IsZero() { why = peer.ShortString() } c.logf("magicsock: adding connection to derp-%v for %v", regionID, why) firstDerp := false if c.activeDerp == nil { firstDerp = true c.activeDerp = make(map[int]activeDerp) c.prevDerp = make(map[int]*syncs.WaitGroupChan) } // Note that derphttp.NewRegionClient does not dial the server // (it doesn't block) so it is safe to do under the c.mu lock. dc := derphttp.NewRegionClient(c.privateKey, c.logf, func() *tailcfg.DERPRegion { // Warning: it is not legal to acquire // magicsock.Conn.mu from this callback. // It's run from derphttp.Client.connect (via Send, etc) // and the lock ordering rules are that magicsock.Conn.mu // must be acquired before derphttp.Client.mu. // See https://github.com/tailscale/tailscale/issues/3726 if c.connCtx.Err() != nil { // We're closing anyway; return nil to stop dialing. return nil } derpMap := c.derpMapAtomic.Load() if derpMap == nil { return nil } return derpMap.Regions[regionID] }) dc.SetCanAckPings(true) dc.NotePreferred(c.myDerp == regionID) dc.SetAddressFamilySelector(derpAddrFamSelector{c}) dc.DNSCache = dnscache.Get() ctx, cancel := context.WithCancel(c.connCtx) ch := make(chan derpWriteRequest, bufferedDerpWritesBeforeDrop) ad.c = dc ad.writeCh = ch ad.cancel = cancel ad.lastWrite = new(time.Time) *ad.lastWrite = time.Now() ad.createTime = time.Now() c.activeDerp[regionID] = ad metricNumDERPConns.Set(int64(len(c.activeDerp))) c.logActiveDerpLocked() c.setPeerLastDerpLocked(peer, regionID, regionID) c.scheduleCleanStaleDerpLocked() // Build a startGate for the derp reader+writer // goroutines, so they don't start running until any // previous generation is closed. startGate := syncs.ClosedChan() if prev := c.prevDerp[regionID]; prev != nil { startGate = prev.DoneChan() } // And register a WaitGroup(Chan) for this generation. wg := syncs.NewWaitGroupChan() wg.Add(2) c.prevDerp[regionID] = wg if firstDerp { startGate = c.derpStarted go func() { dc.Connect(ctx) close(c.derpStarted) c.muCond.Broadcast() }() } go c.runDerpReader(ctx, addr, dc, wg, startGate) go c.runDerpWriter(ctx, dc, ch, wg, startGate) go c.derpActiveFunc() return ad.writeCh } // setPeerLastDerpLocked notes that peer is now being written to via // the provided DERP regionID, and that the peer advertises a DERP // home region ID of homeID. // // If there's any change, it logs. // // c.mu must be held. func (c *Conn) setPeerLastDerpLocked(peer key.NodePublic, regionID, homeID int) { if peer.IsZero() { return } old := c.peerLastDerp[peer] if old == regionID { return } c.peerLastDerp[peer] = regionID var newDesc string switch { case regionID == homeID && regionID == c.myDerp: newDesc = "shared home" case regionID == homeID: newDesc = "their home" case regionID == c.myDerp: newDesc = "our home" case regionID != homeID: newDesc = "alt" } if old == 0 { c.logf("[v1] magicsock: derp route for %s set to derp-%d (%s)", peer.ShortString(), regionID, newDesc) } else { c.logf("[v1] magicsock: derp route for %s changed from derp-%d => derp-%d (%s)", peer.ShortString(), old, regionID, newDesc) } } // derpReadResult is the type sent by runDerpClient to ReceiveIPv4 // when a DERP packet is available. // // Notably, it doesn't include the derp.ReceivedPacket because we // don't want to give the receiver access to the aliased []byte. To // get at the packet contents they need to call copyBuf to copy it // out, which also releases the buffer. type derpReadResult struct { regionID int n int // length of data received src key.NodePublic // copyBuf is called to copy the data to dst. It returns how // much data was copied, which will be n if dst is large // enough. copyBuf can only be called once. // If copyBuf is nil, that's a signal from the sender to ignore // this message. copyBuf func(dst []byte) int } // runDerpReader runs in a goroutine for the life of a DERP // connection, handling received packets. func (c *Conn) runDerpReader(ctx context.Context, derpFakeAddr netip.AddrPort, dc *derphttp.Client, wg *syncs.WaitGroupChan, startGate <-chan struct{}) { defer wg.Decr() defer dc.Close() select { case <-startGate: case <-ctx.Done(): return } didCopy := make(chan struct{}, 1) regionID := int(derpFakeAddr.Port()) res := derpReadResult{regionID: regionID} var pkt derp.ReceivedPacket res.copyBuf = func(dst []byte) int { n := copy(dst, pkt.Data) didCopy <- struct{}{} return n } defer health.SetDERPRegionConnectedState(regionID, false) defer health.SetDERPRegionHealth(regionID, "") // peerPresent is the set of senders we know are present on this // connection, based on messages we've received from the server. peerPresent := map[key.NodePublic]bool{} bo := backoff.NewBackoff(fmt.Sprintf("derp-%d", regionID), c.logf, 5*time.Second) var lastPacketTime time.Time var lastPacketSrc key.NodePublic for { msg, connGen, err := dc.RecvDetail() if err != nil { health.SetDERPRegionConnectedState(regionID, false) // Forget that all these peers have routes. for peer := range peerPresent { delete(peerPresent, peer) c.removeDerpPeerRoute(peer, regionID, dc) } if err == derphttp.ErrClientClosed { return } if c.networkDown() { c.logf("[v1] magicsock: derp.Recv(derp-%d): network down, closing", regionID) return } select { case <-ctx.Done(): return default: } c.logf("magicsock: [%p] derp.Recv(derp-%d): %v", dc, regionID, err) // If our DERP connection broke, it might be because our network // conditions changed. Start that check. c.ReSTUN("derp-recv-error") // Back off a bit before reconnecting. bo.BackOff(ctx, err) select { case <-ctx.Done(): return default: } continue } bo.BackOff(ctx, nil) // reset now := time.Now() if lastPacketTime.IsZero() || now.Sub(lastPacketTime) > 5*time.Second { health.NoteDERPRegionReceivedFrame(regionID) lastPacketTime = now } switch m := msg.(type) { case derp.ServerInfoMessage: health.SetDERPRegionConnectedState(regionID, true) health.SetDERPRegionHealth(regionID, "") // until declared otherwise c.logf("magicsock: derp-%d connected; connGen=%v", regionID, connGen) continue case derp.ReceivedPacket: pkt = m res.n = len(m.Data) res.src = m.Source if logDerpVerbose() { c.logf("magicsock: got derp-%v packet: %q", regionID, m.Data) } // If this is a new sender we hadn't seen before, remember it and // register a route for this peer. if res.src != lastPacketSrc { // avoid map lookup w/ high throughput single peer lastPacketSrc = res.src if _, ok := peerPresent[res.src]; !ok { peerPresent[res.src] = true c.addDerpPeerRoute(res.src, regionID, dc) } } case derp.PingMessage: // Best effort reply to the ping. pingData := [8]byte(m) go func() { if err := dc.SendPong(pingData); err != nil { c.logf("magicsock: derp-%d SendPong error: %v", regionID, err) } }() continue case derp.HealthMessage: health.SetDERPRegionHealth(regionID, m.Problem) case derp.PeerGoneMessage: c.removeDerpPeerRoute(key.NodePublic(m), regionID, dc) default: // Ignore. continue } select { case <-ctx.Done(): return case c.derpRecvCh <- res: } select { case <-ctx.Done(): return case <-didCopy: continue } } } type derpWriteRequest struct { addr netip.AddrPort pubKey key.NodePublic b []byte // copied; ownership passed to receiver } // runDerpWriter runs in a goroutine for the life of a DERP // connection, handling received packets. func (c *Conn) runDerpWriter(ctx context.Context, dc *derphttp.Client, ch <-chan derpWriteRequest, wg *syncs.WaitGroupChan, startGate <-chan struct{}) { defer wg.Decr() select { case <-startGate: case <-ctx.Done(): return } for { select { case <-ctx.Done(): return case wr := <-ch: err := dc.Send(wr.pubKey, wr.b) if err != nil { c.logf("magicsock: derp.Send(%v): %v", wr.addr, err) metricSendDERPError.Add(1) } else { metricSendDERP.Add(1) } } } } type receiveBatch struct { msgs []ipv6.Message } func (c *Conn) getReceiveBatch() *receiveBatch { batch := c.receiveBatchPool.Get().(*receiveBatch) return batch } func (c *Conn) putReceiveBatch(batch *receiveBatch) { for i := range batch.msgs { batch.msgs[i] = ipv6.Message{Buffers: batch.msgs[i].Buffers} } c.receiveBatchPool.Put(batch) } func (c *Conn) receiveIPv6(buffs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) { health.ReceiveIPv6.Enter() defer health.ReceiveIPv6.Exit() batch := c.getReceiveBatch() defer c.putReceiveBatch(batch) for { for i := range buffs { batch.msgs[i].Buffers[0] = buffs[i] } numMsgs, err := c.pconn6.ReadBatch(batch.msgs, 0) if err != nil { if neterror.PacketWasTruncated(err) { // TODO(raggi): discuss whether to log? continue } return 0, err } reportToCaller := false for i, msg := range batch.msgs[:numMsgs] { ipp := msg.Addr.(*net.UDPAddr).AddrPort() if ep, ok := c.receiveIP(msg.Buffers[0][:msg.N], ipp, &c.ippEndpoint6); ok { metricRecvDataIPv6.Add(1) eps[i] = ep sizes[i] = msg.N reportToCaller = true } else { sizes[i] = 0 } } if reportToCaller { return numMsgs, nil } } } func (c *Conn) receiveIPv4(buffs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) { health.ReceiveIPv4.Enter() defer health.ReceiveIPv4.Exit() batch := c.getReceiveBatch() defer c.putReceiveBatch(batch) for { for i := range buffs { batch.msgs[i].Buffers[0] = buffs[i] } numMsgs, err := c.pconn4.ReadBatch(batch.msgs, 0) if err != nil { if neterror.PacketWasTruncated(err) { // TODO(raggi): discuss whether to log? continue } return 0, err } reportToCaller := false for i, msg := range batch.msgs[:numMsgs] { ipp := msg.Addr.(*net.UDPAddr).AddrPort() if ep, ok := c.receiveIP(msg.Buffers[0][:msg.N], ipp, &c.ippEndpoint4); ok { metricRecvDataIPv4.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.stunReceiveFunc.Load()(b, ipp) return nil, false } if c.handleDiscoMessage(b, ipp, key.NodePublic{}) { 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 } ep.noteRecvActivity() if stats := c.stats.Load(); stats != nil { stats.UpdateRxPhysical(ep.nodeAddr, ipp, len(b)) } return ep, true } func (c *connBind) receiveDERP(buffs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) { health.ReceiveDERP.Enter() defer health.ReceiveDERP.Exit() for dm := range c.derpRecvCh { if c.Closed() { break } n, ep := c.processDERPReadResult(dm, buffs[0]) if n == 0 { // No data read occurred. Wait for another packet. continue } metricRecvDataDERP.Add(1) sizes[0] = n eps[0] = ep return 1, nil } return 0, net.ErrClosed } func (c *Conn) processDERPReadResult(dm derpReadResult, b []byte) (n int, ep *endpoint) { if dm.copyBuf == nil { return 0, nil } var regionID int n, regionID = dm.n, dm.regionID ncopy := dm.copyBuf(b) if ncopy != n { err := fmt.Errorf("received DERP packet of length %d that's too big for WireGuard buf size %d", n, ncopy) c.logf("magicsock: %v", err) return 0, nil } ipp := netip.AddrPortFrom(derpMagicIPAddr, uint16(regionID)) if c.handleDiscoMessage(b[:n], ipp, dm.src) { return 0, nil } var ok bool c.mu.Lock() ep, ok = c.peerMap.endpointForNodeKey(dm.src) c.mu.Unlock() if !ok { // We don't know anything about this node key, nothing to // record or process. return 0, nil } ep.noteRecvActivity() if stats := c.stats.Load(); stats != nil { stats.UpdateRxPhysical(ep.nodeAddr, ipp, dm.n) } return n, ep } // 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() == 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 } var nonce [disco.NonceLen]byte if _, err := crand.Read(nonce[:]); err != nil { panic(err) // worth dying for } 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", c.discoShort, dstDisco.ShortString(), node, derpStr(dst.String()), disco.MessageSummary(m)) } 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() { c.logf("magicsock: disco: failed to send %T to %v: %v", m, dst, err) } } return sent, err } // 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) (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", sender.ShortString()) } if c.privateKey.IsZero() { // Ignore disco messages when we're stopped. // Still return true, to not pass it down to wireguard. return } if c.discoPrivate.IsZero() { if debugDisco() { c.logf("magicsock: disco: ignoring disco-looking frame, no local key") } return } if !c.peerMap.anyEndpointForDiscoKey(sender) { metricRecvDiscoBadPeer.Add(1) if debugDisco() { c.logf("magicsock: disco: ignoring disco-looking frame, don't know endpoint for %v", sender.ShortString()) } return } // 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. // Don't log in normal case. 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?)", sender) } metricRecvDiscoBadKey.Add(1) return } 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 } isDERP := src.Addr() == derpMagicIPAddr 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 } if ep.discoKey != di.discoKey { metricRecvDiscoCallMeMaybeBadDisco.Add(1) c.logf("[unexpected] CallMeMaybe from peer via DERP whose netmap discokey != disco source") return } di.setNodeKey(nodeKey) c.dlogf("[v1] magicsock: disco: %v<-%v (%v, %v) got call-me-maybe, %d endpoints", c.discoShort, ep.discoShort, 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 && ep.discoKey == 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 && ep.discoKey == 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() == 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 handlePongLocked to establish // the IP<>disco mapping. if nk, ok := c.unambiguousNodeKeyOfPingLocked(dm, di.discoKey, derpNodeSrc); ok { di.setNodeKey(nk) 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", c.discoShort, di.discoShort, pingNodeSrcStr, src, dm.TxID[:6]) } 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() 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", de.discoShort, 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, de.discoKey, &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("%w", 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 map[key.NodePublic]struct{}) { 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 _, ok := newPeers[peer]; !ok { delete(c.derpRoute, peer) delete(c.peerLastDerp, peer) } } if len(oldPeers) == 0 && len(newPeers) > 0 { go c.ReSTUN("non-zero-peers") } } // SetDERPMap controls which (if any) DERP servers are used. // A nil value means to disable DERP; it's disabled by default. func (c *Conn) SetDERPMap(dm *tailcfg.DERPMap) { c.mu.Lock() defer c.mu.Unlock() if reflect.DeepEqual(dm, c.derpMap) { return } c.derpMapAtomic.Store(dm) old := c.derpMap c.derpMap = dm if dm == nil { c.closeAllDerpLocked("derp-disabled") return } // Reconnect any DERP region that changed definitions. if old != nil { changes := false for rid, oldDef := range old.Regions { if reflect.DeepEqual(oldDef, dm.Regions[rid]) { continue } changes = true if rid == c.myDerp { c.myDerp = 0 } c.closeDerpLocked(rid, "derp-region-redefined") } if changes { c.logActiveDerpLocked() } } go c.ReSTUN("derp-map-update") } func nodesEqual(x, y []*tailcfg.Node) bool { if len(x) != len(y) { return false } for i := range x { if !x[i].Equal(y[i]) { return false } } return true } // 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 } priorNetmap := c.netMap var priorDebug *tailcfg.Debug if priorNetmap != nil { priorDebug = priorNetmap.Debug } debugChanged := !reflect.DeepEqual(priorDebug, nm.Debug) metricNumPeers.Set(int64(len(nm.Peers))) // Update c.netMap regardless, before the following early return. c.netMap = nm if priorNetmap != nil && nodesEqual(priorNetmap.Peers, nm.Peers) && !debugChanged { // 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) haven't changed, no need to do anything else. return } c.logf("[v1] magicsock: got updated network map; %d peers", len(nm.Peers)) heartbeatDisabled := debugEnableSilentDisco() || (c.netMap != nil && c.netMap.Debug != nil && c.netMap.Debug.EnableSilentDisco) // 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 ep, ok := c.peerMap.endpointForNodeKey(n.Key); ok { if n.DiscoKey.IsZero() { // Discokey transitioned from non-zero to zero? Ignore. Server's confused. c.peerMap.deleteEndpoint(ep) continue } oldDiscoKey := ep.discoKey ep.updateFromNode(n, heartbeatDisabled) c.peerMap.upsertEndpoint(ep, oldDiscoKey) // maybe update discokey mappings in peerMap continue } if n.DiscoKey.IsZero() { // Ancient pre-0.100 node. Ignore, so we can assume elsewhere in magicsock // that all nodes have a DiscoKey. continue } ep := &endpoint{ c: c, publicKey: n.Key, publicKeyHex: n.Key.UntypedHexString(), sentPing: map[stun.TxID]sentPing{}, endpointState: map[netip.AddrPort]*endpointState{}, heartbeatDisabled: heartbeatDisabled, } if len(n.Addresses) > 0 { ep.nodeAddr = n.Addresses[0].Addr() } ep.discoKey = n.DiscoKey ep.discoShort = n.DiscoKey.ShortString() ep.initFakeUDPAddr() if debugDisco() { // rather than making a new knob 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 _, a := range n.AllowedIPs { if a.IsSingleIP() { fmt.Fprintf(w, "aip=%v ", a.Addr()) } else { fmt.Fprintf(w, "aip=%v ", a) } } for _, ep := range n.Endpoints { fmt.Fprintf(w, "ep=%v ", ep) } })) } ep.updateFromNode(n, heartbeatDisabled) 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 := make(map[key.NodePublic]bool, len(nm.Peers)) for _, n := range nm.Peers { keep[n.Key] = true } c.peerMap.forEachEndpoint(func(ep *endpoint) { if !keep[ep.publicKey] { c.peerMap.deleteEndpoint(ep) } }) } // discokeys might have changed in the above. Discard unused info. for dk := range c.discoInfo { if !c.peerMap.anyEndpointForDiscoKey(dk) { delete(c.discoInfo, dk) } } } func (c *Conn) wantDerpLocked() bool { return c.derpMap != nil } // c.mu must be held. func (c *Conn) closeAllDerpLocked(why string) { if len(c.activeDerp) == 0 { return // without the useless log statement } for i := range c.activeDerp { c.closeDerpLocked(i, why) } c.logActiveDerpLocked() } // maybeCloseDERPsOnRebind, in response to a rebind, closes all // DERP connections that don't have a local address in okayLocalIPs // and pings all those that do. func (c *Conn) maybeCloseDERPsOnRebind(okayLocalIPs []netip.Prefix) { c.mu.Lock() defer c.mu.Unlock() for regionID, ad := range c.activeDerp { la, err := ad.c.LocalAddr() if err != nil { c.closeOrReconnectDERPLocked(regionID, "rebind-no-localaddr") continue } if !tsaddr.PrefixesContainsIP(okayLocalIPs, la.Addr()) { c.closeOrReconnectDERPLocked(regionID, "rebind-default-route-change") continue } regionID := regionID dc := ad.c go func() { ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second) defer cancel() if err := dc.Ping(ctx); err != nil { c.mu.Lock() defer c.mu.Unlock() c.closeOrReconnectDERPLocked(regionID, "rebind-ping-fail") return } c.logf("post-rebind ping of DERP region %d okay", regionID) }() } c.logActiveDerpLocked() } // closeOrReconnectDERPLocked closes the DERP connection to the // provided regionID and starts reconnecting it if it's our current // home DERP. // // why is a reason for logging. // // c.mu must be held. func (c *Conn) closeOrReconnectDERPLocked(regionID int, why string) { c.closeDerpLocked(regionID, why) if !c.privateKey.IsZero() && c.myDerp == regionID { c.startDerpHomeConnectLocked() } } // c.mu must be held. // It is the responsibility of the caller to call logActiveDerpLocked after any set of closes. func (c *Conn) closeDerpLocked(regionID int, why string) { if ad, ok := c.activeDerp[regionID]; ok { c.logf("magicsock: closing connection to derp-%v (%v), age %v", regionID, why, time.Since(ad.createTime).Round(time.Second)) go ad.c.Close() ad.cancel() delete(c.activeDerp, regionID) metricNumDERPConns.Set(int64(len(c.activeDerp))) } } // c.mu must be held. func (c *Conn) logActiveDerpLocked() { now := time.Now() c.logf("magicsock: %v active derp conns%s", len(c.activeDerp), logger.ArgWriter(func(buf *bufio.Writer) { if len(c.activeDerp) == 0 { return } buf.WriteString(":") c.foreachActiveDerpSortedLocked(func(node int, ad activeDerp) { fmt.Fprintf(buf, " derp-%d=cr%v,wr%v", node, simpleDur(now.Sub(ad.createTime)), simpleDur(now.Sub(*ad.lastWrite))) }) })) } 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) } })) } // c.mu must be held. func (c *Conn) foreachActiveDerpSortedLocked(fn func(regionID int, ad activeDerp)) { if len(c.activeDerp) < 2 { for id, ad := range c.activeDerp { fn(id, ad) } return } ids := make([]int, 0, len(c.activeDerp)) for id := range c.activeDerp { ids = append(ids, id) } sort.Ints(ids) for _, id := range ids { fn(id, c.activeDerp[id]) } } func (c *Conn) cleanStaleDerp() { c.mu.Lock() defer c.mu.Unlock() if c.closed { return } c.derpCleanupTimerArmed = false tooOld := time.Now().Add(-derpInactiveCleanupTime) dirty := false someNonHomeOpen := false for i, ad := range c.activeDerp { if i == c.myDerp { continue } if ad.lastWrite.Before(tooOld) { c.closeDerpLocked(i, "idle") dirty = true } else { someNonHomeOpen = true } } if dirty { c.logActiveDerpLocked() } if someNonHomeOpen { c.scheduleCleanStaleDerpLocked() } } func (c *Conn) scheduleCleanStaleDerpLocked() { if c.derpCleanupTimerArmed { // Already going to fire soon. Let the existing one // fire lest it get infinitely delayed by repeated // calls to scheduleCleanStaleDerpLocked. return } c.derpCleanupTimerArmed = true if c.derpCleanupTimer != nil { c.derpCleanupTimer.Reset(derpCleanStaleInterval) } else { c.derpCleanupTimer = time.AfterFunc(derpCleanStaleInterval, c.cleanStaleDerp) } } // DERPs reports the number of active DERP connections. func (c *Conn) DERPs() int { c.mu.Lock() defer c.mu.Unlock() return len(c.activeDerp) } // Bind returns the wireguard-go conn.Bind for c. 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 } func (c *connBind) BatchSize() int { // TODO(raggi): determine by properties rather than hardcoding platform behavior switch runtime.GOOS { case "linux": return conn.DefaultBatchSize 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. 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. func (c *connBind) SetMark(value uint32) error { return nil } // Close closes the connBind, unless it is already closed. 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 } // Closed reports whether c is closed. func (c *connBind) Closed() 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() // 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() } 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: break default: return true } } return false } func maxIdleBeforeSTUNShutdown() time.Duration { if debugReSTUNStopOnIdle() { return 45 * time.Second } return sessionActiveTimeout } func (c *Conn) shouldDoPeriodicReSTUNLocked() bool { if c.networkDown() { 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 > maxIdleBeforeSTUNShutdown() { if c.netMap != nil && c.netMap.Debug != nil && c.netMap.Debug.ForceBackgroundSTUN { // 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 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)).ListenPacket(ctx, network, addr) } var debugBindSocket = envknob.RegisterBool("TS_DEBUG_MAGICSOCK_BIND_SOCKET") // 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(), "") return nil } if debugAlwaysDERP() { c.logf("disabled %v per TS_DEBUG_ALWAYS_USE_DERP", network) ruc.setConnLocked(newBlockForeverConn(), "") 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 } trySetSocketBuffer(pconn, c.logf) // Success. if debugBindSocket() { c.logf("magicsock: bindSocket: successfully listened %v port %d", network, port) } ruc.setConnLocked(pconn, network) 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(), "") 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()) 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("%w", err) return } var ifIPs []netip.Prefix if c.linkMon != nil { st := c.linkMon.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 is called by WireGuard to connect to an endpoint. 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 } type batchReaderWriter interface { batchReader batchWriter } type batchWriter interface { WriteBatch([]ipv6.Message, int) (int, error) } type batchReader interface { ReadBatch([]ipv6.Message, int) (int, error) } // udpConnWithBatchOps wraps a *net.UDPConn in order to extend it to support // batch operations. // // TODO(jwhited): This wrapping is temporary. https://github.com/golang/go/issues/45886 type udpConnWithBatchOps struct { *net.UDPConn xpc batchReaderWriter } func newUDPConnWithBatchOps(conn *net.UDPConn, network string) udpConnWithBatchOps { ucbo := udpConnWithBatchOps{ UDPConn: conn, } switch network { case "udp4": ucbo.xpc = ipv4.NewPacketConn(conn) case "udp6": ucbo.xpc = ipv6.NewPacketConn(conn) default: panic("bogus network") } return ucbo } func (u udpConnWithBatchOps) WriteBatch(ms []ipv6.Message, flags int) (int, error) { return u.xpc.WriteBatch(ms, flags) } func (u udpConnWithBatchOps) ReadBatch(ms []ipv6.Message, flags int) (int, error) { return u.xpc.ReadBatch(ms, flags) } // RebindingUDPConn is a UDP socket that can be re-bound. // Unix has no notion of re-binding a socket, so we swap it out for a new one. type RebindingUDPConn struct { // pconnAtomic is a pointer to the value stored in pconn, but doesn't // require acquiring mu. It's used for reads/writes and only upon failure // do the reads/writes then check pconn (after acquiring mu) to see if // there's been a rebind meanwhile. // pconn isn't really needed, but makes some of the code simpler // to keep it distinct. // Neither is expected to be nil, sockets are bound on creation. pconnAtomic atomic.Pointer[nettype.PacketConn] mu sync.Mutex // held while changing pconn (and pconnAtomic) pconn nettype.PacketConn port uint16 } // upgradePacketConn may upgrade a nettype.PacketConn to a udpConnWithBatchOps. func upgradePacketConn(p nettype.PacketConn, network string) nettype.PacketConn { uc, ok := p.(*net.UDPConn) if ok && runtime.GOOS == "linux" && (network == "udp4" || network == "udp6") { // 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 the fast paths. Nobody who cares about performance runs such // ancient kernels. if strings.HasPrefix(hostinfo.GetOSVersion(), "2") { return p } // Non-Linux does not support batch operations. x/net will fall back to // recv/sendmsg, but not all platforms have recv/sendmsg support. Keep // this simple for now. return newUDPConnWithBatchOps(uc, network) } return p } // setConnLocked sets the provided nettype.PacketConn. It should be called only // after acquiring RebindingUDPConn.mu. It upgrades the provided // nettype.PacketConn to a udpConnWithBatchOps when appropriate. This upgrade // is intentionally pushed closest to where read/write ops occur in order to // avoid disrupting surrounding code that assumes nettype.PacketConn is a // *net.UDPConn. func (c *RebindingUDPConn) setConnLocked(p nettype.PacketConn, network string) { upc := upgradePacketConn(p, network) c.pconn = upc c.pconnAtomic.Store(&upc) c.port = uint16(c.localAddrLocked().Port) } // currentConn returns c's current pconn, acquiring c.mu in the process. func (c *RebindingUDPConn) currentConn() nettype.PacketConn { c.mu.Lock() defer c.mu.Unlock() return c.pconn } func (c *RebindingUDPConn) readFromWithInitPconn(pconn nettype.PacketConn, b []byte) (int, net.Addr, error) { for { n, addr, err := pconn.ReadFrom(b) if err != nil && pconn != c.currentConn() { pconn = *c.pconnAtomic.Load() continue } return n, addr, err } } // ReadFrom reads a packet from c into b. // It returns the number of bytes copied and the source address. func (c *RebindingUDPConn) ReadFrom(b []byte) (int, net.Addr, error) { return c.readFromWithInitPconn(*c.pconnAtomic.Load(), b) } // ReadFromNetaddr reads a packet from c into b. // It returns the number of bytes copied and the return address. // It is identical to c.ReadFrom, except that it returns a netip.AddrPort instead of a net.Addr. // ReadFromNetaddr is designed to work with specific underlying connection types. // If c's underlying connection returns a non-*net.UPDAddr return address, ReadFromNetaddr will return an error. // ReadFromNetaddr exists because it removes an allocation per read, // when c's underlying connection is a net.UDPConn. func (c *RebindingUDPConn) ReadFromNetaddr(b []byte) (n int, ipp netip.AddrPort, err error) { for { pconn := *c.pconnAtomic.Load() // Optimization: Treat *net.UDPConn specially. // This lets us avoid allocations by calling ReadFromUDPAddrPort. // The non-*net.UDPConn case works, but it allocates. if udpConn, ok := pconn.(*net.UDPConn); ok { n, ipp, err = udpConn.ReadFromUDPAddrPort(b) } else { var addr net.Addr n, addr, err = pconn.ReadFrom(b) pAddr, ok := addr.(*net.UDPAddr) if addr != nil && !ok { return 0, netip.AddrPort{}, fmt.Errorf("RebindingUDPConn.ReadFromNetaddr: underlying connection returned address of type %T, want *netaddr.UDPAddr", addr) } if pAddr != nil { ipp = netaddr.Unmap(pAddr.AddrPort()) if !ipp.IsValid() { return 0, netip.AddrPort{}, errors.New("netaddr.FromStdAddr failed") } } } if err != nil && pconn != c.currentConn() { // The connection changed underfoot. Try again. continue } return n, ipp, err } } func (c *RebindingUDPConn) WriteBatch(msgs []ipv6.Message, flags int) (int, error) { var ( n int err error start int ) for { pconn := *c.pconnAtomic.Load() bw, ok := pconn.(batchWriter) if !ok { for _, msg := range msgs { _, err = c.writeToWithInitPconn(pconn, msg.Buffers[0], msg.Addr) if err != nil { return n, err } n++ } return n, nil } n, err = bw.WriteBatch(msgs[start:], flags) if err != nil { if pconn != c.currentConn() { continue } return n, err } else if n == len(msgs[start:]) { return len(msgs), nil } else { start += n } } } func (c *RebindingUDPConn) ReadBatch(msgs []ipv6.Message, flags int) (int, error) { for { pconn := *c.pconnAtomic.Load() br, ok := pconn.(batchReader) if !ok { var err error msgs[0].N, msgs[0].Addr, err = c.readFromWithInitPconn(pconn, msgs[0].Buffers[0]) if err == nil { return 1, nil } return 0, err } n, err := br.ReadBatch(msgs, flags) if err != nil && pconn != c.currentConn() { continue } return n, err } } func (c *RebindingUDPConn) Port() uint16 { c.mu.Lock() defer c.mu.Unlock() return c.port } func (c *RebindingUDPConn) LocalAddr() *net.UDPAddr { c.mu.Lock() defer c.mu.Unlock() return c.localAddrLocked() } func (c *RebindingUDPConn) localAddrLocked() *net.UDPAddr { return c.pconn.LocalAddr().(*net.UDPAddr) } // errNilPConn is returned by RebindingUDPConn.Close when there is no current pconn. // It is for internal use only and should not be returned to users. var errNilPConn = errors.New("nil pconn") func (c *RebindingUDPConn) Close() error { c.mu.Lock() defer c.mu.Unlock() return c.closeLocked() } func (c *RebindingUDPConn) closeLocked() error { if c.pconn == nil { return errNilPConn } c.port = 0 return c.pconn.Close() } func (c *RebindingUDPConn) writeToWithInitPconn(pconn nettype.PacketConn, b []byte, addr net.Addr) (int, error) { for { n, err := pconn.WriteTo(b, addr) if err != nil && pconn != c.currentConn() { pconn = *c.pconnAtomic.Load() continue } return n, err } } func (c *RebindingUDPConn) WriteTo(b []byte, addr net.Addr) (int, error) { return c.writeToWithInitPconn(*c.pconnAtomic.Load(), b, addr) } func (c *RebindingUDPConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) { for { pconn := *c.pconnAtomic.Load() n, err := pconn.WriteToUDPAddrPort(b, addr) if err != nil && pconn != c.currentConn() { continue } return n, err } } func newBlockForeverConn() *blockForeverConn { c := new(blockForeverConn) c.cond = sync.NewCond(&c.mu) return c } // blockForeverConn is a net.PacketConn whose reads block until it is closed. type blockForeverConn struct { mu sync.Mutex cond *sync.Cond closed bool } func (c *blockForeverConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) { c.mu.Lock() for !c.closed { c.cond.Wait() } c.mu.Unlock() return 0, nil, net.ErrClosed } func (c *blockForeverConn) WriteTo(p []byte, addr net.Addr) (n int, err error) { // Silently drop writes. return len(p), nil } func (c *blockForeverConn) WriteToUDPAddrPort(p []byte, addr netip.AddrPort) (int, error) { // Silently drop writes. return len(p), nil } func (c *blockForeverConn) ReadBatch(p []ipv6.Message, flags int) (int, error) { c.mu.Lock() for !c.closed { c.cond.Wait() } c.mu.Unlock() return 0, net.ErrClosed } func (c *blockForeverConn) WriteBatch(p []ipv6.Message, flags int) (int, error) { // Silently drop writes. return len(p), nil } func (c *blockForeverConn) LocalAddr() net.Addr { // Return a *net.UDPAddr because lots of code assumes that it will. return new(net.UDPAddr) } func (c *blockForeverConn) Close() error { c.mu.Lock() defer c.mu.Unlock() if c.closed { return net.ErrClosed } c.closed = true c.cond.Broadcast() return nil } func (c *blockForeverConn) SetDeadline(t time.Time) error { return errors.New("unimplemented") } func (c *blockForeverConn) SetReadDeadline(t time.Time) error { return errors.New("unimplemented") } func (c *blockForeverConn) SetWriteDeadline(t time.Time) error { return errors.New("unimplemented") } // 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) } func sbPrintAddr(sb *strings.Builder, a netip.AddrPort) { is6 := a.Addr().Is6() if is6 { sb.WriteByte('[') } fmt.Fprintf(sb, "%s", a.Addr()) if is6 { sb.WriteByte(']') } fmt.Fprintf(sb, ":%d", a.Port()) } func (c *Conn) derpRegionCodeOfAddrLocked(ipPort string) string { _, portStr, err := net.SplitHostPort(ipPort) if err != nil { return "" } regionID, err := strconv.Atoi(portStr) if err != nil { return "" } return c.derpRegionCodeOfIDLocked(regionID) } func (c *Conn) derpRegionCodeOfIDLocked(regionID int) string { if c.derpMap == nil { return "" } if r, ok := c.derpMap.Regions[regionID]; ok { return r.RegionCode } return "" } func (c *Conn) UpdateStatus(sb *ipnstate.StatusBuilder) { c.mu.Lock() defer c.mu.Unlock() var tailscaleIPs []netip.Addr if c.netMap != nil { tailscaleIPs = make([]netip.Addr, 0, len(c.netMap.Addresses)) for _, addr := range c.netMap.Addresses { if !addr.IsSingleIP() { continue } sb.AddTailscaleIP(addr.Addr()) tailscaleIPs = append(tailscaleIPs, addr.Addr()) } } sb.MutateSelfStatus(func(ss *ipnstate.PeerStatus) { if !c.privateKey.IsZero() { ss.PublicKey = c.privateKey.Public() } else { ss.PublicKey = key.NodePublic{} } ss.Addrs = make([]string, 0, len(c.lastEndpoints)) for _, ep := range c.lastEndpoints { ss.Addrs = append(ss.Addrs, ep.Addr.String()) } ss.OS = version.OS() if c.derpMap != nil { derpRegion, ok := c.derpMap.Regions[c.myDerp] if ok { ss.Relay = derpRegion.RegionCode } } ss.TailscaleIPs = tailscaleIPs }) if sb.WantPeers { c.peerMap.forEachEndpoint(func(ep *endpoint) { ps := &ipnstate.PeerStatus{InMagicSock: true} //ps.Addrs = append(ps.Addrs, n.Endpoints...) ep.populatePeerStatus(ps) sb.AddPeer(ep.publicKey, ps) }) } c.foreachActiveDerpSortedLocked(func(node int, ad activeDerp) { // TODO(bradfitz): add to ipnstate.StatusBuilder //f("
  • derp-%v: cr%v,wr%v
    • ", node, simpleDur(now.Sub(ad.createTime)), simpleDur(now.Sub(*ad.lastWrite))) }) } // 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) } func ippDebugString(ua netip.AddrPort) string { if ua.Addr() == derpMagicIPAddr { return fmt.Sprintf("derp-%d", ua.Port()) } return ua.String() } // endpointSendFunc is a func that writes encrypted Wireguard payloads from // WireGuard to a peer. It might write via UDP, DERP, both, or neither. // // What these funcs should NOT do is too much work. Minimize use of mutexes, map // lookups, etc. The idea is that selecting the path to use is done infrequently // and mostly async from sending packets. When conditions change (including the // passing of time and loss of confidence in certain routes), then a new send // func gets set on an sendpoint. // // A nil value means the current fast path has expired and needs to be // recalculated. type endpointSendFunc func([][]byte) error // endpoint is a wireguard/conn.Endpoint that picks the best // available path to communicate with a peer, based on network // conditions and what the peer supports. type endpoint struct { // atomically accessed; declared first for alignment reasons lastRecv mono.Time numStopAndResetAtomic int64 sendFunc syncs.AtomicValue[endpointSendFunc] // nil or unset means unused // These fields are initialized once and never modified. c *Conn publicKey key.NodePublic // peer public key (for WireGuard + DERP) publicKeyHex string // cached output of publicKey.UntypedHexString fakeWGAddr netip.AddrPort // the UDP address we tell wireguard-go we're using nodeAddr netip.Addr // the node's first tailscale address; used for logging & wireguard rate-limiting (Issue 6686) // mu protects all following fields. mu sync.Mutex // Lock ordering: Conn.mu, then endpoint.mu discoKey key.DiscoPublic // for discovery messages. Should never be the zero value. discoShort string // ShortString of discoKey. Empty if peer can't disco. heartBeatTimer *time.Timer // nil when idle lastSend mono.Time // last time there was outgoing packets sent to this peer (from wireguard-go) lastFullPing mono.Time // last time we pinged all endpoints derpAddr netip.AddrPort // fallback/bootstrap path, if non-zero (non-zero for well-behaved clients) bestAddr addrLatency // best non-DERP path; zero if none bestAddrAt mono.Time // time best address re-confirmed trustBestAddrUntil mono.Time // time when bestAddr expires sentPing map[stun.TxID]sentPing endpointState map[netip.AddrPort]*endpointState isCallMeMaybeEP map[netip.AddrPort]bool pendingCLIPings []pendingCLIPing // any outstanding "tailscale ping" commands running // The following fields are related to the new "silent disco" // implementation that's a WIP as of 2022-10-20. // See #540 for background. heartbeatDisabled bool pathFinderRunning bool expired bool // whether the node has expired } type pendingCLIPing struct { res *ipnstate.PingResult cb func(*ipnstate.PingResult) } 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 // derpInactiveCleanupTime is how long a non-home DERP connection // needs to be idle (last written to) before we close it. derpInactiveCleanupTime = 60 * time.Second // derpCleanStaleInterval is how often cleanStaleDerp runs when there // are potentially-stale DERP connections to close. derpCleanStaleInterval = 15 * time.Second // 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 ) // endpointState is some state and history for a specific endpoint of // a endpoint. (The subject is the endpoint.endpointState // map key) type endpointState struct { // all fields guarded by endpoint.mu // lastPing is the last (outgoing) ping time. lastPing mono.Time // lastGotPing, if non-zero, means that this was an endpoint // that we learned about at runtime (from an incoming ping) // and that is not in the network map. If so, we keep the time // updated and use it to discard old candidates. lastGotPing time.Time // lastGotPingTxID contains the TxID for the last incoming ping. This is // used to de-dup incoming pings that we may see on both the raw disco // socket on Linux, and UDP socket. We cannot rely solely on the raw socket // disco handling due to https://github.com/tailscale/tailscale/issues/7078. lastGotPingTxID stun.TxID // callMeMaybeTime, if non-zero, is the time this endpoint // was advertised last via a call-me-maybe disco message. callMeMaybeTime time.Time recentPongs []pongReply // ring buffer up to pongHistoryCount entries recentPong uint16 // index into recentPongs of most recent; older before, wrapped index int16 // index in nodecfg.Node.Endpoints; meaningless if lastGotPing non-zero } // 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 // shouldDeleteLocked reports whether we should delete this endpoint. func (st *endpointState) shouldDeleteLocked() bool { switch { case !st.callMeMaybeTime.IsZero(): return false case st.lastGotPing.IsZero(): // This was an endpoint from the network map. Is it still in the network map? return st.index == indexSentinelDeleted default: // This was an endpoint discovered at runtime. return time.Since(st.lastGotPing) > sessionActiveTimeout } } func (de *endpoint) deleteEndpointLocked(ep netip.AddrPort) { delete(de.endpointState, ep) if de.bestAddr.AddrPort == ep { de.bestAddr = addrLatency{} } } // pongHistoryCount is how many pongReply values we keep per endpointState const pongHistoryCount = 64 type pongReply struct { latency time.Duration pongAt mono.Time // when we received the pong from netip.AddrPort // the pong's src (usually same as endpoint map key) pongSrc netip.AddrPort // what they reported they heard } type sentPing struct { to netip.AddrPort at mono.Time timer *time.Timer // timeout timer purpose discoPingPurpose } // initFakeUDPAddr populates fakeWGAddr with a globally unique fake UDPAddr. // The current implementation just uses the pointer value of de jammed into an IPv6 // address, but it could also be, say, a counter. func (de *endpoint) initFakeUDPAddr() { var addr [16]byte addr[0] = 0xfd addr[1] = 0x00 binary.BigEndian.PutUint64(addr[2:], uint64(reflect.ValueOf(de).Pointer())) de.fakeWGAddr = netip.AddrPortFrom(netip.AddrFrom16(addr).Unmap(), 12345) } // noteRecvActivity records receive activity on de, and invokes // Conn.noteRecvActivity no more than once every 10s. func (de *endpoint) noteRecvActivity() { if de.c.noteRecvActivity == nil { return } now := mono.Now() elapsed := now.Sub(de.lastRecv.LoadAtomic()) if elapsed > 10*time.Second { de.lastRecv.StoreAtomic(now) de.c.noteRecvActivity(de.publicKey) } } // String exists purely so wireguard-go internals can log.Printf("%v") // its internal conn.Endpoints and we don't end up with data races // from fmt (via log) reading mutex fields and such. func (de *endpoint) String() string { return fmt.Sprintf("magicsock.endpoint{%v, %v}", de.publicKey.ShortString(), de.discoShort) } func (de *endpoint) ClearSrc() {} func (de *endpoint) SrcToString() string { panic("unused") } // unused by wireguard-go func (de *endpoint) SrcIP() netip.Addr { panic("unused") } // unused by wireguard-go func (de *endpoint) DstToString() string { return de.publicKeyHex } func (de *endpoint) DstIP() netip.Addr { return de.nodeAddr } // see tailscale/tailscale#6686 func (de *endpoint) DstToBytes() []byte { return packIPPort(de.fakeWGAddr) } // addrForSendLocked returns the address(es) that should be used for // sending the next packet. Zero, one, or both of UDP address and DERP // addr may be non-zero. // // de.mu must be held. func (de *endpoint) addrForSendLocked(now mono.Time) (udpAddr, derpAddr netip.AddrPort) { udpAddr = de.bestAddr.AddrPort if !udpAddr.IsValid() || now.After(de.trustBestAddrUntil) { // We had a bestAddr but it expired so send both to it // and DERP. derpAddr = de.derpAddr } return } // heartbeat is called every heartbeatInterval to keep the best UDP path alive, // or kick off discovery of other paths. func (de *endpoint) heartbeat() { de.mu.Lock() defer de.mu.Unlock() de.heartBeatTimer = nil if de.heartbeatDisabled { // If control override to disable heartBeatTimer set, return early. return } if de.lastSend.IsZero() { // Shouldn't happen. return } if mono.Since(de.lastSend) > sessionActiveTimeout { // Session's idle. Stop heartbeating. de.c.dlogf("[v1] magicsock: disco: ending heartbeats for idle session to %v (%v)", de.publicKey.ShortString(), de.discoShort) return } now := mono.Now() udpAddr, _ := de.addrForSendLocked(now) if udpAddr.IsValid() { // We have a preferred path. Ping that every 2 seconds. de.startPingLocked(udpAddr, now, pingHeartbeat) } if de.wantFullPingLocked(now) { de.sendPingsLocked(now, true) } de.heartBeatTimer = time.AfterFunc(heartbeatInterval, de.heartbeat) } // wantFullPingLocked reports whether we should ping to all our peers looking for // a better path. // // de.mu must be held. func (de *endpoint) wantFullPingLocked(now mono.Time) bool { if runtime.GOOS == "js" { return false } if !de.bestAddr.IsValid() || de.lastFullPing.IsZero() { return true } if now.After(de.trustBestAddrUntil) { return true } if de.bestAddr.latency <= goodEnoughLatency { return false } if now.Sub(de.lastFullPing) >= upgradeInterval { return true } return false } func (de *endpoint) noteActiveLocked() { de.lastSend = mono.Now() if de.heartBeatTimer == nil && !de.heartbeatDisabled { de.heartBeatTimer = time.AfterFunc(heartbeatInterval, de.heartbeat) } } // cliPing starts a ping for the "tailscale ping" command. res is value to call cb with, // already partially filled. func (de *endpoint) cliPing(res *ipnstate.PingResult, cb func(*ipnstate.PingResult)) { de.mu.Lock() defer de.mu.Unlock() if de.expired { res.Err = errExpired.Error() cb(res) return } de.pendingCLIPings = append(de.pendingCLIPings, pendingCLIPing{res, cb}) now := mono.Now() udpAddr, derpAddr := de.addrForSendLocked(now) if derpAddr.IsValid() { de.startPingLocked(derpAddr, now, pingCLI) } if udpAddr.IsValid() && now.Before(de.trustBestAddrUntil) { // Already have an active session, so just ping the address we're using. // Otherwise "tailscale ping" results to a node on the local network // can look like they're bouncing between, say 10.0.0.0/9 and the peer's // IPv6 address, both 1ms away, and it's random who replies first. de.startPingLocked(udpAddr, now, pingCLI) } else { for ep := range de.endpointState { de.startPingLocked(ep, now, pingCLI) } } de.noteActiveLocked() } var ( errExpired = errors.New("peer's node key has expired") errNoUDPOrDERP = errors.New("no UDP or DERP addr") ) func (de *endpoint) send(buffs [][]byte) error { if fn := de.sendFunc.Load(); fn != nil { return fn(buffs) } de.mu.Lock() if de.expired { de.mu.Unlock() return errExpired } // if heartbeat disabled, kick off pathfinder if de.heartbeatDisabled { if !de.pathFinderRunning { de.startPathFinder() } } now := mono.Now() udpAddr, derpAddr := de.addrForSendLocked(now) if !udpAddr.IsValid() || now.After(de.trustBestAddrUntil) { de.sendPingsLocked(now, true) } de.noteActiveLocked() de.mu.Unlock() if !udpAddr.IsValid() && !derpAddr.IsValid() { return errNoUDPOrDERP } var err error if udpAddr.IsValid() { _, err = de.c.sendUDPBatch(udpAddr, buffs) // TODO(raggi): needs updating for accuracy, as in error conditions we may have partial sends. if stats := de.c.stats.Load(); err == nil && stats != nil { var txBytes int for _, b := range buffs { txBytes += len(b) } stats.UpdateTxPhysical(de.nodeAddr, udpAddr, txBytes) } } if derpAddr.IsValid() { allOk := true for _, buff := range buffs { ok, _ := de.c.sendAddr(derpAddr, de.publicKey, buff) if stats := de.c.stats.Load(); stats != nil { stats.UpdateTxPhysical(de.nodeAddr, derpAddr, len(buff)) } if !ok { allOk = false } } if allOk { return nil } } return err } func (de *endpoint) pingTimeout(txid stun.TxID) { de.mu.Lock() defer de.mu.Unlock() sp, ok := de.sentPing[txid] if !ok { return } if debugDisco() || !de.bestAddr.IsValid() || mono.Now().After(de.trustBestAddrUntil) { de.c.dlogf("[v1] magicsock: disco: timeout waiting for pong %x from %v (%v, %v)", txid[:6], sp.to, de.publicKey.ShortString(), de.discoShort) } de.removeSentPingLocked(txid, sp) } // forgetPing is called by a timer when a ping either fails to send or // has taken too long to get a pong reply. func (de *endpoint) forgetPing(txid stun.TxID) { de.mu.Lock() defer de.mu.Unlock() if sp, ok := de.sentPing[txid]; ok { de.removeSentPingLocked(txid, sp) } } func (de *endpoint) removeSentPingLocked(txid stun.TxID, sp sentPing) { // Stop the timer for the case where sendPing failed to write to UDP. // In the case of a timer already having fired, this is a no-op: sp.timer.Stop() delete(de.sentPing, txid) } // sendDiscoPing sends a ping with the provided txid to ep using de's discoKey. // // The caller (startPingLocked) should've already recorded the ping in // sentPing and set up the timer. // // The caller should use de.discoKey as the discoKey argument. // It is passed in so that sendDiscoPing doesn't need to lock de.mu. func (de *endpoint) sendDiscoPing(ep netip.AddrPort, discoKey key.DiscoPublic, txid stun.TxID, logLevel discoLogLevel) { sent, _ := de.c.sendDiscoMessage(ep, de.publicKey, discoKey, &disco.Ping{ TxID: [12]byte(txid), NodeKey: de.c.publicKeyAtomic.Load(), }, logLevel) if !sent { de.forgetPing(txid) } } // discoPingPurpose is the reason why a discovery ping message was sent. type discoPingPurpose int //go:generate go run tailscale.com/cmd/addlicense -file discopingpurpose_string.go go run golang.org/x/tools/cmd/stringer -type=discoPingPurpose -trimprefix=ping const ( // pingDiscovery means that purpose of a ping was to see if a // path was valid. pingDiscovery discoPingPurpose = iota // pingHeartbeat means that purpose of a ping was whether a // peer was still there. pingHeartbeat // pingCLI means that the user is running "tailscale ping" // from the CLI. These types of pings can go over DERP. pingCLI ) func (de *endpoint) startPingLocked(ep netip.AddrPort, now mono.Time, purpose discoPingPurpose) { if runtime.GOOS == "js" { return } if purpose != pingCLI { st, ok := de.endpointState[ep] if !ok { // Shouldn't happen. But don't ping an endpoint that's // not active for us. de.c.logf("magicsock: disco: [unexpected] attempt to ping no longer live endpoint %v", ep) return } st.lastPing = now } txid := stun.NewTxID() de.sentPing[txid] = sentPing{ to: ep, at: now, timer: time.AfterFunc(pingTimeoutDuration, func() { de.pingTimeout(txid) }), purpose: purpose, } logLevel := discoLog if purpose == pingHeartbeat { logLevel = discoVerboseLog } go de.sendDiscoPing(ep, de.discoKey, txid, logLevel) } func (de *endpoint) sendPingsLocked(now mono.Time, sendCallMeMaybe bool) { de.lastFullPing = now var sentAny bool for ep, st := range de.endpointState { if st.shouldDeleteLocked() { de.deleteEndpointLocked(ep) continue } if runtime.GOOS == "js" { continue } if !st.lastPing.IsZero() && now.Sub(st.lastPing) < discoPingInterval { continue } firstPing := !sentAny sentAny = true if firstPing && sendCallMeMaybe { de.c.dlogf("[v1] magicsock: disco: send, starting discovery for %v (%v)", de.publicKey.ShortString(), de.discoShort) } de.startPingLocked(ep, now, pingDiscovery) } derpAddr := de.derpAddr if sentAny && sendCallMeMaybe && derpAddr.IsValid() { // Have our magicsock.Conn figure out its STUN endpoint (if // it doesn't know already) and then send a CallMeMaybe // message to our peer via DERP informing them that we've // sent so our firewall ports are probably open and now // would be a good time for them to connect. go de.c.enqueueCallMeMaybe(derpAddr, de) } } func (de *endpoint) updateFromNode(n *tailcfg.Node, heartbeatDisabled bool) { if n == nil { panic("nil node when updating disco ep") } de.mu.Lock() defer de.mu.Unlock() de.heartbeatDisabled = heartbeatDisabled de.expired = n.Expired if de.discoKey != n.DiscoKey { de.c.logf("[v1] magicsock: disco: node %s changed from discokey %s to %s", de.publicKey.ShortString(), de.discoKey, n.DiscoKey) de.discoKey = n.DiscoKey de.discoShort = de.discoKey.ShortString() de.resetLocked() } if n.DERP == "" { de.derpAddr = netip.AddrPort{} } else { de.derpAddr, _ = netip.ParseAddrPort(n.DERP) } for _, st := range de.endpointState { st.index = indexSentinelDeleted // assume deleted until updated in next loop } for i, epStr := range n.Endpoints { if i > math.MaxInt16 { // Seems unlikely. continue } ipp, err := netip.ParseAddrPort(epStr) if err != nil { de.c.logf("magicsock: bogus netmap endpoint %q", epStr) continue } if st, ok := de.endpointState[ipp]; ok { st.index = int16(i) } else { de.endpointState[ipp] = &endpointState{index: int16(i)} } } // Now delete anything unless it's still in the network map or // was a recently discovered endpoint. for ep, st := range de.endpointState { if st.shouldDeleteLocked() { de.deleteEndpointLocked(ep) } } // Node changed. Invalidate its sending fast path, if any. de.sendFunc.Store(nil) } // addCandidateEndpoint adds ep as an endpoint to which we should send // future pings. If there is an existing endpointState for ep, and forRxPingTxID // matches the last received ping TxID, this function reports true, otherwise // false. // // This is called once we've already verified that we got a valid // discovery message from de via ep. func (de *endpoint) addCandidateEndpoint(ep netip.AddrPort, forRxPingTxID stun.TxID) (duplicatePing bool) { de.mu.Lock() defer de.mu.Unlock() if st, ok := de.endpointState[ep]; ok { duplicatePing = forRxPingTxID == st.lastGotPingTxID if !duplicatePing { st.lastGotPingTxID = forRxPingTxID } if st.lastGotPing.IsZero() { // Already-known endpoint from the network map. return duplicatePing } st.lastGotPing = time.Now() return duplicatePing } // Newly discovered endpoint. Exciting! de.c.dlogf("[v1] magicsock: disco: adding %v as candidate endpoint for %v (%s)", ep, de.discoShort, de.publicKey.ShortString()) de.endpointState[ep] = &endpointState{ lastGotPing: time.Now(), lastGotPingTxID: forRxPingTxID, } // If for some reason this gets very large, do some cleanup. if size := len(de.endpointState); size > 100 { for ep, st := range de.endpointState { if st.shouldDeleteLocked() { de.deleteEndpointLocked(ep) } } size2 := len(de.endpointState) de.c.dlogf("[v1] magicsock: disco: addCandidateEndpoint pruned %v candidate set from %v to %v entries", size, size2) } return false } // noteConnectivityChange is called when connectivity changes enough // that we should question our earlier assumptions about which paths // work. func (de *endpoint) noteConnectivityChange() { de.mu.Lock() defer de.mu.Unlock() de.trustBestAddrUntil = 0 } // handlePongConnLocked handles a Pong message (a reply to an earlier ping). // It should be called with the Conn.mu held. // // It reports whether m.TxID corresponds to a ping that this endpoint sent. func (de *endpoint) handlePongConnLocked(m *disco.Pong, di *discoInfo, src netip.AddrPort) (knownTxID bool) { de.mu.Lock() defer de.mu.Unlock() isDerp := src.Addr() == derpMagicIPAddr sp, ok := de.sentPing[m.TxID] if !ok { // This is not a pong for a ping we sent. return false } knownTxID = true // for naked returns below de.removeSentPingLocked(m.TxID, sp) di.setNodeKey(de.publicKey) now := mono.Now() latency := now.Sub(sp.at) if !isDerp { st, ok := de.endpointState[sp.to] if !ok { // This is no longer an endpoint we care about. return } de.c.peerMap.setNodeKeyForIPPort(src, de.publicKey) st.addPongReplyLocked(pongReply{ latency: latency, pongAt: now, from: src, pongSrc: m.Src, }) } if sp.purpose != pingHeartbeat { de.c.dlogf("[v1] magicsock: disco: %v<-%v (%v, %v) got pong tx=%x latency=%v pong.src=%v%v", de.c.discoShort, de.discoShort, de.publicKey.ShortString(), src, m.TxID[:6], latency.Round(time.Millisecond), m.Src, logger.ArgWriter(func(bw *bufio.Writer) { if sp.to != src { fmt.Fprintf(bw, " ping.to=%v", sp.to) } })) } for _, pp := range de.pendingCLIPings { de.c.populateCLIPingResponseLocked(pp.res, latency, sp.to) go pp.cb(pp.res) } de.pendingCLIPings = nil // Promote this pong response to our current best address if it's lower latency. // TODO(bradfitz): decide how latency vs. preference order affects decision if !isDerp { thisPong := addrLatency{sp.to, latency} if betterAddr(thisPong, de.bestAddr) { de.c.logf("magicsock: disco: node %v %v now using %v", de.publicKey.ShortString(), de.discoShort, sp.to) de.bestAddr = thisPong } if de.bestAddr.AddrPort == thisPong.AddrPort { de.bestAddr.latency = latency de.bestAddrAt = now de.trustBestAddrUntil = now.Add(trustUDPAddrDuration) } } return } // 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) } } } // addrLatency is an IPPort with an associated latency. type addrLatency struct { netip.AddrPort latency time.Duration } // betterAddr reports whether a is a better addr to use than b. func betterAddr(a, b addrLatency) bool { if a.AddrPort == b.AddrPort { return false } if !b.IsValid() { return true } if !a.IsValid() { return false } if a.Addr().Is6() && b.Addr().Is4() { // Prefer IPv6 for being a bit more robust, as long as // the latencies are roughly equivalent. if a.latency/10*9 < b.latency { return true } } else if a.Addr().Is4() && b.Addr().Is6() { if betterAddr(b, a) { return false } } return a.latency < b.latency } // endpoint.mu must be held. func (st *endpointState) addPongReplyLocked(r pongReply) { if n := len(st.recentPongs); n < pongHistoryCount { st.recentPong = uint16(n) st.recentPongs = append(st.recentPongs, r) return } i := st.recentPong + 1 if i == pongHistoryCount { i = 0 } st.recentPongs[i] = r st.recentPong = i } // handleCallMeMaybe handles a CallMeMaybe discovery message via // DERP. The contract for use of this message is that the peer has // already sent to us via UDP, so their stateful firewall should be // open. Now we can Ping back and make it through. func (de *endpoint) handleCallMeMaybe(m *disco.CallMeMaybe) { if runtime.GOOS == "js" { // Nothing to do on js/wasm if we can't send UDP packets anyway. return } de.mu.Lock() defer de.mu.Unlock() now := time.Now() for ep := range de.isCallMeMaybeEP { de.isCallMeMaybeEP[ep] = false // mark for deletion } var newEPs []netip.AddrPort for _, ep := range m.MyNumber { if ep.Addr().Is6() && ep.Addr().IsLinkLocalUnicast() { // We send these out, but ignore them for now. // TODO: teach the ping code to ping on all interfaces // for these. continue } mak.Set(&de.isCallMeMaybeEP, ep, true) if es, ok := de.endpointState[ep]; ok { es.callMeMaybeTime = now } else { de.endpointState[ep] = &endpointState{callMeMaybeTime: now} newEPs = append(newEPs, ep) } } if len(newEPs) > 0 { de.c.dlogf("[v1] magicsock: disco: call-me-maybe from %v %v added new endpoints: %v", de.publicKey.ShortString(), de.discoShort, logger.ArgWriter(func(w *bufio.Writer) { for i, ep := range newEPs { if i > 0 { w.WriteString(", ") } w.WriteString(ep.String()) } })) } // Delete any prior CallMeMaybe endpoints that weren't included // in this message. for ep, want := range de.isCallMeMaybeEP { if !want { delete(de.isCallMeMaybeEP, ep) de.deleteEndpointLocked(ep) } } // Zero out all the lastPing times to force sendPingsLocked to send new ones, // even if it's been less than 5 seconds ago. for _, st := range de.endpointState { st.lastPing = 0 } de.sendPingsLocked(mono.Now(), false) } func (de *endpoint) populatePeerStatus(ps *ipnstate.PeerStatus) { de.mu.Lock() defer de.mu.Unlock() ps.Relay = de.c.derpRegionCodeOfIDLocked(int(de.derpAddr.Port())) if de.lastSend.IsZero() { return } now := mono.Now() ps.LastWrite = de.lastSend.WallTime() ps.Active = now.Sub(de.lastSend) < sessionActiveTimeout if udpAddr, derpAddr := de.addrForSendLocked(now); udpAddr.IsValid() && !derpAddr.IsValid() { ps.CurAddr = udpAddr.String() } } // stopAndReset stops timers associated with de and resets its state back to zero. // It's called when a discovery endpoint is no longer present in the // NetworkMap, or when magicsock is transitioning from running to // stopped state (via SetPrivateKey(zero)) func (de *endpoint) stopAndReset() { atomic.AddInt64(&de.numStopAndResetAtomic, 1) de.mu.Lock() defer de.mu.Unlock() if closing := de.c.closing.Load(); !closing { de.c.logf("[v1] magicsock: doing cleanup for discovery key %s", de.discoKey.ShortString()) } de.resetLocked() if de.heartBeatTimer != nil { de.heartBeatTimer.Stop() de.heartBeatTimer = nil } de.pendingCLIPings = nil } // resetLocked clears all the endpoint's p2p state, reverting it to a // DERP-only endpoint. It does not stop the endpoint's heartbeat // timer, if one is running. func (de *endpoint) resetLocked() { de.lastSend = 0 de.lastFullPing = 0 de.bestAddr = addrLatency{} de.bestAddrAt = 0 de.trustBestAddrUntil = 0 for _, es := range de.endpointState { es.lastPing = 0 } for txid, sp := range de.sentPing { de.removeSentPingLocked(txid, sp) } } func (de *endpoint) numStopAndReset() int64 { return atomic.LoadInt64(&de.numStopAndResetAtomic) } // 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 // lastNodeKey is the last NodeKey seen using discoKey. // It's only updated if the NodeKey is unambiguous. lastNodeKey key.NodePublic // lastNodeKeyTime is the time a NodeKey was last seen using // this discoKey. It's only updated if the NodeKey is // unambiguous. lastNodeKeyTime time.Time } // setNodeKey sets the most recent mapping from di.discoKey to the // NodeKey nk. func (di *discoInfo) setNodeKey(nk key.NodePublic) { di.lastNodeKey = nk di.lastNodeKeyTime = time.Now() } // derpAddrFamSelector is the derphttp.AddressFamilySelector we pass // to derphttp.Client.SetAddressFamilySelector. // // It provides the hint as to whether in an IPv4-vs-IPv6 race that // IPv4 should be held back a bit to give IPv6 a better-than-50/50 // chance of winning. We only return true when we believe IPv6 will // work anyway, so we don't artificially delay the connection speed. type derpAddrFamSelector struct{ c *Conn } func (s derpAddrFamSelector) PreferIPv6() bool { if r := s.c.lastNetCheckReport.Load(); r != nil { return r.IPv6 } return false } 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") 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") // 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 metricRecvDiscoPacketIPv4 = clientmetric.NewCounter("magicsock_disco_recv_bpf_ipv4") metricRecvDiscoPacketIPv6 = clientmetric.NewCounter("magicsock_disco_recv_bpf_ipv6") )