// Copyright (c) 2019 Tailscale Inc & AUTHORS All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // 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" "encoding/json" "errors" "fmt" "hash/fnv" "math" "math/rand" "net" "os" "reflect" "sort" "strconv" "strings" "sync" "sync/atomic" "time" "golang.org/x/crypto/nacl/box" "golang.org/x/time/rate" "golang.zx2c4.com/wireguard/conn" "inet.af/netaddr" "tailscale.com/control/controlclient" "tailscale.com/derp" "tailscale.com/derp/derphttp" "tailscale.com/disco" "tailscale.com/health" "tailscale.com/ipn/ipnstate" "tailscale.com/logtail/backoff" "tailscale.com/net/dnscache" "tailscale.com/net/interfaces" "tailscale.com/net/netcheck" "tailscale.com/net/netns" "tailscale.com/net/portmapper" "tailscale.com/net/stun" "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/types/wgkey" "tailscale.com/util/uniq" "tailscale.com/version" "tailscale.com/wgengine/monitor" "tailscale.com/wgengine/wgcfg" ) // Various debugging and experimental tweakables, set by environment // variable. var ( // logPacketDests prints the known addresses for a peer every time // they change, in the legacy (non-discovery) endpoint code only. logPacketDests, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_LOG_PACKET_DESTS")) // debugDisco prints verbose logs of active discovery events as // they happen. debugDisco, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DISCO")) // debugOmitLocalAddresses removes all local interface addresses // from magicsock's discovered local endpoints. Used in some tests. debugOmitLocalAddresses, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_OMIT_LOCAL_ADDRS")) // debugUseDerpRoute temporarily (2020-03-22) controls whether DERP // reverse routing is enabled (Issue 150). It will become always true // later. debugUseDerpRouteEnv = os.Getenv("TS_DEBUG_ENABLE_DERP_ROUTE") debugUseDerpRoute, _ = strconv.ParseBool(debugUseDerpRouteEnv) // logDerpVerbose logs all received DERP packets, including their // full payload. logDerpVerbose, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DERP")) // debugReSTUNStopOnIdle unconditionally enables the "shut down // STUN if magicsock is idle" behavior that normally only triggers // on mobile devices, lowers the shutdown interval, and logs more // verbosely about idle measurements. debugReSTUNStopOnIdle, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_RESTUN_STOP_ON_IDLE")) // debugAlwaysDERP disables the use of UDP, forcing all peer communication over DERP. debugAlwaysDERP, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_ALWAYS_USE_DERP")) ) // useDerpRoute reports whether magicsock should enable the DERP // return path optimization (Issue 150). func useDerpRoute() bool { if debugUseDerpRouteEnv != "" { return debugUseDerpRoute } ob := controlclient.DERPRouteFlag() if v, ok := ob.Get(); ok { return v } return false } // inTest reports whether the running program is a test that set the // IN_TS_TEST environment variable. // // Unlike the other debug tweakables above, this one needs to be // checked every time at runtime, because tests set this after program // startup. func inTest() bool { inTest, _ := strconv.ParseBool(os.Getenv("IN_TS_TEST")) return inTest } // 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 packetListener nettype.PacketListener noteRecvActivity func(tailcfg.DiscoKey) // or nil, see Options.NoteRecvActivity simulatedNetwork bool disableLegacy bool // ================================================================ // 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 // 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 // sendLogLimit is a rate limiter for errors logged in the (hot) // packet sending codepath. It's so that, if magicsock gets into a // bad state, we don't spam one error per wireguard packet being // transmitted. // TODO(danderson): now that we have global rate-limiting, is this still useful? sendLogLimit *rate.Limiter // stunReceiveFunc holds the current STUN packet processing func. // Its Loaded value is always non-nil. stunReceiveFunc atomic.Value // of func(p []byte, fromAddr *net.UDPAddr) // derpRecvCh is used by receiveDERP to read DERP messages. 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 syncs.AtomicBool // 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 syncs.AtomicBool // havePrivateKey is whether privateKey is non-zero. havePrivateKey syncs.AtomicBool // port is the preferred port from opts.Port; 0 means auto. port syncs.AtomicUint32 // ============================================================ // mu guards all following fields; see userspaceEngine lock ordering rules mu sync.Mutex muCond *sync.Cond started bool // Start was called closed bool // Close was called // 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[*discoEndpoint]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.Public]struct{} // discoPrivate is the private naclbox key used for active // discovery traffic. It's created once near (but not during) // construction. discoPrivate key.Private discoPublic tailcfg.DiscoKey // public of discoPrivate discoShort string // ShortString of discoPublic (to save logging work later) // nodeOfDisco tracks the networkmap Node entity for each peer // discovery key. // // TODO(danderson): the only thing we ever use from this is the // peer's WireGuard public key. This could be a map of DiscoKey to // NodeKey. nodeOfDisco map[tailcfg.DiscoKey]*tailcfg.Node discoOfNode map[tailcfg.NodeKey]tailcfg.DiscoKey discoOfAddr map[netaddr.IPPort]tailcfg.DiscoKey // validated non-DERP paths only // endpointsOfDisco tracks the wireguard-go endpoints for peers // with recent activity. endpointOfDisco map[tailcfg.DiscoKey]*discoEndpoint // those with activity only sharedDiscoKey map[tailcfg.DiscoKey]*[32]byte // nacl/box precomputed key // addrsByUDP is a map of every remote ip:port to a priority // list of endpoint addresses for a peer. // The priority list is provided by wgengine configuration. // // Given a wgcfg describing: // machineA: 10.0.0.1:1, 10.0.0.2:2 // machineB: 10.0.0.3:3 // the addrsByUDP map contains: // 10.0.0.1:1 -> [10.0.0.1:1, 10.0.0.2:2] // 10.0.0.2:2 -> [10.0.0.1:1, 10.0.0.2:2] // 10.0.0.3:3 -> [10.0.0.3:3] // // Used only to communicate with legacy, pre-active-discovery // clients. addrsByUDP map[netaddr.IPPort]*addrSet // addrsByKey maps from public keys (as seen by incoming DERP // packets) to its addrSet (the same values as in addrsByUDP). // // Used only to communicate with legacy, pre-active-discovery // clients. addrsByKey map[key.Public]*addrSet // 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.Private // 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.Public]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.Public]int } // 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.Public, 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.Public, derpID int, dc *derphttp.Client) { c.mu.Lock() defer c.mu.Unlock() if c.derpRoute == nil { c.derpRoute = make(map[key.Public]derpRoute) } r := derpRoute{derpID, dc} c.derpRoute[peer] = r } // DerpMagicIP is a fake WireGuard endpoint IP address that means // to use DERP. When used, the port number of the WireGuard endpoint // is the DERP server number to use. // // Mnemonic: 3.3.40 are numbers above the keys D, E, R, P. const DerpMagicIP = "127.3.3.40" var derpMagicIPAddr = netaddr.MustParseIP(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 // PacketListener optionally specifies how to create PacketConns. // It's meant for testing. PacketListener nettype.PacketListener // NoteRecvActivity, if provided, is a func for magicsock to // call whenever it receives a packet from a a // discovery-capable 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 called // while holding userspaceEngine.wgLock and likely calls // Conn.ParseEndpoint, which acquires Conn.mu. As such, you // should not hold Conn.mu while calling it. NoteRecvActivity func(tailcfg.DiscoKey) // SimulatedNetwork can be set true in tests to signal that // the network is simulated and thus it's okay to bind on the // unspecified address (which we'd normally avoid to avoid // triggering macOS and Windows firwall dialog boxes during // "go test"). SimulatedNetwork bool // DisableLegacyNetworking disables legacy peer handling. When // enabled, only active discovery-aware nodes will be able to // communicate with Conn. DisableLegacyNetworking bool // 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{ disableLegacy: true, sendLogLimit: rate.NewLimiter(rate.Every(1*time.Minute), 1), addrsByUDP: make(map[netaddr.IPPort]*addrSet), addrsByKey: make(map[key.Public]*addrSet), derpRecvCh: make(chan derpReadResult), derpStarted: make(chan struct{}), peerLastDerp: make(map[key.Public]int), endpointOfDisco: make(map[tailcfg.DiscoKey]*discoEndpoint), sharedDiscoKey: make(map[tailcfg.DiscoKey]*[32]byte), discoOfAddr: make(map[netaddr.IPPort]tailcfg.DiscoKey), } c.bind = &connBind{Conn: c, closed: true} c.muCond = sync.NewCond(&c.mu) c.networkUp.Set(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. // // It doesn't start doing anything until Start is called. func NewConn(opts Options) (*Conn, error) { c := newConn() c.port.Set(uint32(opts.Port)) c.logf = opts.logf() c.epFunc = opts.endpointsFunc() c.derpActiveFunc = opts.derpActiveFunc() c.idleFunc = opts.IdleFunc c.packetListener = opts.PacketListener c.noteRecvActivity = opts.NoteRecvActivity c.simulatedNetwork = opts.SimulatedNetwork c.disableLegacy = opts.DisableLegacyNetworking c.portMapper = portmapper.NewClient(logger.WithPrefix(c.logf, "portmapper: "), c.onPortMapChanged) if opts.LinkMonitor != nil { c.portMapper.SetGatewayLookupFunc(opts.LinkMonitor.GatewayAndSelfIP) } if err := c.initialBind(); 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 }, SkipExternalNetwork: inTest(), PortMapper: c.portMapper, } if c.pconn6 != nil { c.netChecker.GetSTUNConn6 = func() netcheck.STUNConn { return c.pconn6 } } c.ignoreSTUNPackets() return c, nil } func (c *Conn) Start() { c.mu.Lock() if c.started { panic("duplicate Start call") } c.started = true c.mu.Unlock() c.ReSTUN("initial") } // ignoreSTUNPackets sets a STUN packet processing func that does nothing. func (c *Conn) ignoreSTUNPackets() { c.stunReceiveFunc.Store(func([]byte, netaddr.IPPort) {}) } // 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) { 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.logf("[v1] magicsock: starting endpoint update (%s)", why) 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.logf("[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.noV4.Set(!report.IPv4) c.noV6.Set(!report.IPv6) 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.WorkingUDP.Set(report.UDP) 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 } // See where our peers are. var ( peersOnDerp = map[int]int{} best int bestCount int ) for _, as := range c.addrsByKey { if id := as.derpID(); id != 0 { peersOnDerp[id]++ if v := peersOnDerp[id]; v > bestCount { bestCount = v best = id } } } // If we already had selected something in the past and it has // any peers, stay on it. If there are no peers, though, also // stay where we are. if c.myDerp != 0 && (best == 0 || peersOnDerp[c.myDerp] != 0) { return c.myDerp } // Otherwise pick wherever the most peers are. if best != 0 { return best } // Otherwise just pick something randomly. h := fnv.New64() h.Write([]byte(fmt.Sprintf("%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.logf("[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(discoKey tailcfg.DiscoKey, addr netaddr.IPPort) { c.mu.Lock() defer c.mu.Unlock() c.discoOfAddr[addr] = discoKey } 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) } } // LastRecvActivityOfDisco describes the time we last got traffic from // this endpoint (updated every ~10 seconds). func (c *Conn) LastRecvActivityOfDisco(dk tailcfg.DiscoKey) string { c.mu.Lock() defer c.mu.Unlock() de, ok := c.endpointOfDisco[dk] 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].IP().String() } res.NodeName = peer.Name // prefer DNS name if res.NodeName == "" { res.NodeName = peer.Hostinfo.Hostname // else hostname } else { if i := strings.Index(res.NodeName, "."); i != -1 { res.NodeName = res.NodeName[:i] } } dk, ok := c.discoOfNode[peer.Key] if !ok { // peer is using outdated Tailscale version (pre-0.100) res.Err = "no discovery key for peer (pre Tailscale 0.100 version?). Try: ping 100.x.y.z" cb(res) return } de, ok := c.endpointOfDisco[dk] if !ok { c.mu.Unlock() // temporarily release if c.noteRecvActivity != nil { c.noteRecvActivity(dk) } c.mu.Lock() // re-acquire // re-check at least basic invariant: if c.privateKey.IsZero() { res.Err = "local tailscaled stopped" cb(res) return } de, ok = c.endpointOfDisco[dk] if !ok { res.Err = "internal error: failed to create endpoint for discokey" cb(res) return } c.logf("[v1] magicsock: started peer %v for ping to %v", dk.ShortString(), peer.Key.ShortString()) } de.cliPing(res, cb) } // c.mu must be held func (c *Conn) populateCLIPingResponseLocked(res *ipnstate.PingResult, latency time.Duration, ep netaddr.IPPort) { res.LatencySeconds = latency.Seconds() if ep.IP() != derpMagicIPAddr { res.Endpoint = ep.String() return } regionID := int(ep.Port()) res.DERPRegionID = regionID if c.derpMap != nil { if dr, ok := c.derpMap.Regions[regionID]; ok { res.DERPRegionCode = dr.RegionCode } } } // DiscoPublicKey returns the discovery public key. func (c *Conn) DiscoPublicKey() tailcfg.DiscoKey { c.mu.Lock() defer c.mu.Unlock() if c.discoPrivate.IsZero() { priv := key.NewPrivate() c.discoPrivate = priv c.discoPublic = tailcfg.DiscoKey(priv.Public()) c.discoShort = c.discoPublic.ShortString() c.logf("magicsock: disco key = %v", c.discoShort) } return c.discoPublic } // PeerHasDiscoKey reports whether peer k supports discovery keys (client version 0.100.0+). func (c *Conn) PeerHasDiscoKey(k tailcfg.NodeKey) bool { c.mu.Lock() defer c.mu.Unlock() _, ok := c.discoOfNode[k] return ok } // 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 } 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(netaddr.IPPortFrom(derpMagicIPAddr, uint16(node)), key.Public{}) } // 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) { portmapExt, havePortmap := c.portMapper.GetCachedMappingOrStartCreatingOne() nr, err := c.updateNetInfo(ctx) if err != nil { c.logf("magicsock.Conn.determineEndpoints: updateNetInfo: %v", err) return nil, err } already := make(map[netaddr.IPPort]tailcfg.EndpointType) // endpoint -> how it was found var eps []tailcfg.Endpoint // unique endpoints ipp := func(s string) (ipp netaddr.IPPort) { ipp, _ = netaddr.ParseIPPort(s) return } addAddr := func(ipp netaddr.IPPort, et tailcfg.EndpointType) { if ipp.IsZero() || (debugOmitLocalAddresses && et == tailcfg.EndpointLocal) { return } if _, ok := already[ipp]; !ok { 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.Get(); 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(netaddr.IPPortFrom(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 { laddr := c.pconn4.LocalAddr() return uint16(laddr.Port) } var errNetworkDown = errors.New("magicsock: network down") func (c *Conn) networkDown() bool { return !c.networkUp.Get() } func (c *Conn) Send(b []byte, ep conn.Endpoint) error { if c.networkDown() { return errNetworkDown } switch v := ep.(type) { default: panic(fmt.Sprintf("[unexpected] Endpoint type %T", v)) case *discoEndpoint: return v.send(b) case *addrSet: return c.sendAddrSet(b, v) } } var errConnClosed = errors.New("Conn closed") var errDropDerpPacket = errors.New("too many DERP packets queued; dropping") var udpAddrPool = &sync.Pool{ New: func() interface{} { return new(net.UDPAddr) }, } // sendUDP sends UDP packet b to ipp. // See sendAddr's docs on the return value meanings. func (c *Conn) sendUDP(ipp netaddr.IPPort, b []byte) (sent bool, err error) { ua := udpAddrPool.Get().(*net.UDPAddr) defer udpAddrPool.Put(ua) return c.sendUDPStd(ipp.UDPAddrAt(ua), b) } // sendUDP sends UDP packet b to addr. // See sendAddr's docs on the return value meanings. func (c *Conn) sendUDPStd(addr *net.UDPAddr, b []byte) (sent bool, err error) { switch { case addr.IP.To4() != nil: _, err = c.pconn4.WriteTo(b, addr) if err != nil && c.noV4.Get() { return false, nil } case len(addr.IP) == net.IPv6len: if c.pconn6 == nil { // ignore IPv6 dest if we don't have an IPv6 address. return false, nil } _, err = c.pconn6.WriteTo(b, addr) if err != nil && c.noV6.Get() { 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 netaddr.IPPort, pubKey key.Public, b []byte) (sent bool, err error) { if addr.IP() != derpMagicIPAddr { return c.sendUDP(addr, b) } ch := c.derpWriteChanOfAddr(addr, pubKey) if ch == nil { 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: return false, errConnClosed case ch <- derpWriteRequest{addr, pubKey, pkt}: return true, nil default: // 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 netaddr.IPPort, peer key.Public) chan<- derpWriteRequest { if addr.IP() != 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.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 = peerShort(peer) } 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) } if c.derpMap == nil || c.derpMap.Regions[regionID] == nil { return nil } // Note that derphttp.NewRegionClient does not dial the server // so it is safe to do under the mu lock. dc := derphttp.NewRegionClient(c.privateKey, c.logf, func() *tailcfg.DERPRegion { if c.connCtx.Err() != nil { // If we're closing, don't try to acquire the lock. // We might already be in Conn.Close and the Lock would deadlock. return nil } c.mu.Lock() defer c.mu.Unlock() if c.derpMap == nil { return nil } return c.derpMap.Regions[regionID] }) dc.SetCanAckPings(true) dc.NotePreferred(c.myDerp == regionID) 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 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.Public, 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)", peerShort(peer), regionID, newDesc) } else { c.logf("[v1] magicsock: derp route for %s changed from derp-%d => derp-%d (%s)", peerShort(peer), 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.Public // may be zero until server deployment if v2+ // 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 netaddr.IPPort, 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) // 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.Public]bool{} bo := backoff.NewBackoff(fmt.Sprintf("derp-%d", regionID), c.logf, 5*time.Second) var lastPacketTime time.Time 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) 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 _, ok := peerPresent[m.Source]; !ok { peerPresent[m.Source] = true c.addDerpPeerRoute(m.Source, 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 default: // Ignore. continue } select { case <-ctx.Done(): return case c.derpRecvCh <- res: } select { case <-ctx.Done(): return case <-didCopy: continue } } } type derpWriteRequest struct { addr netaddr.IPPort pubKey key.Public 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) } } } } // findEndpoint maps from a UDP address to a WireGuard endpoint, for // ReceiveIPv4/ReceiveIPv6. // // TODO(bradfitz): add a fast path that returns nil here for normal // wireguard-go transport packets; wireguard-go only uses this // Endpoint for the relatively rare non-data packets; but we need the // Endpoint to find the UDPAddr to return to wireguard anyway, so no // benefit unless we can, say, always return the same fake UDPAddr for // all packets. func (c *Conn) findEndpoint(ipp netaddr.IPPort, packet []byte) conn.Endpoint { c.mu.Lock() defer c.mu.Unlock() // See if they have a discoEndpoint, for a set of peers // both supporting active discovery. if dk, ok := c.discoOfAddr[ipp]; ok { if ep, ok := c.endpointOfDisco[dk]; ok { return ep } } return c.findLegacyEndpointLocked(ipp, packet) } // noteRecvActivityFromEndpoint calls the c.noteRecvActivity hook if // e is a discovery-capable peer and this is the first receive activity // it's got in awhile (in last 10 seconds). // // This should be called whenever a packet arrives from e. func (c *Conn) noteRecvActivityFromEndpoint(e conn.Endpoint) { de, ok := e.(*discoEndpoint) if ok && c.noteRecvActivity != nil && de.isFirstRecvActivityInAwhile() { c.noteRecvActivity(de.discoKey) } } // receiveIPv6 receives a UDP IPv6 packet. It is called by wireguard-go. func (c *Conn) receiveIPv6(b []byte) (int, conn.Endpoint, error) { health.ReceiveIPv6.Enter() defer health.ReceiveIPv6.Exit() for { n, ipp, err := c.pconn6.ReadFromNetaddr(b) if err != nil { return 0, nil, err } if ep, ok := c.receiveIP(b[:n], ipp, &c.ippEndpoint6); ok { return n, ep, nil } } } // receiveIPv4 receives a UDP IPv4 packet. It is called by wireguard-go. func (c *Conn) receiveIPv4(b []byte) (n int, ep conn.Endpoint, err error) { health.ReceiveIPv4.Enter() defer health.ReceiveIPv4.Exit() for { n, ipp, err := c.pconn4.ReadFromNetaddr(b) if err != nil { return 0, nil, err } if ep, ok := c.receiveIP(b[:n], ipp, &c.ippEndpoint4); ok { return n, ep, 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 netaddr.IPPort, cache *ippEndpointCache) (ep conn.Endpoint, ok bool) { if stun.Is(b) { c.stunReceiveFunc.Load().(func([]byte, netaddr.IPPort))(b, ipp) return nil, false } if c.handleDiscoMessage(b, ipp) { return nil, false } if !c.havePrivateKey.Get() { // 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 { ep = c.findEndpoint(ipp, b) if ep == nil { return nil, false } if de, ok := ep.(*discoEndpoint); ok { cache.ipp = ipp cache.de = de cache.gen = de.numStopAndReset() } } c.noteRecvActivityFromEndpoint(ep) return ep, true } // receiveDERP reads a packet from c.derpRecvCh into b and returns the associated endpoint. // It is called by wireguard-go. // // If the packet was a disco message or the peer endpoint wasn't // found, the returned error is errLoopAgain. func (c *connBind) receiveDERP(b []byte) (n int, ep conn.Endpoint, err error) { health.ReceiveDERP.Enter() defer health.ReceiveDERP.Exit() for dm := range c.derpRecvCh { if c.Closed() { break } n, ep := c.processDERPReadResult(dm, b) if n == 0 { // No data read occurred. Wait for another packet. continue } return n, ep, nil } return 0, nil, net.ErrClosed } func (c *Conn) processDERPReadResult(dm derpReadResult, b []byte) (n int, ep conn.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 := netaddr.IPPortFrom(derpMagicIPAddr, uint16(regionID)) if c.handleDiscoMessage(b[:n], ipp) { return 0, nil } var ( didNoteRecvActivity bool discoEp *discoEndpoint asEp *addrSet ) c.mu.Lock() if dk, ok := c.discoOfNode[tailcfg.NodeKey(dm.src)]; ok { discoEp = c.endpointOfDisco[dk] // If we know about the node (it's in discoOfNode) but don't know about the // endpoint, that's because it's an idle peer that doesn't yet exist in the // wireguard config. So run the receive hook, if defined, which should // create the wireguard peer. if discoEp == nil && c.noteRecvActivity != nil { didNoteRecvActivity = true c.mu.Unlock() // release lock before calling noteRecvActivity c.noteRecvActivity(dk) // (calls back into ParseEndpoint) // Now require the lock. No invariants need to be rechecked; just // 1-2 map lookups follow that are harmless if, say, the peer has // been deleted during this time. c.mu.Lock() discoEp = c.endpointOfDisco[dk] c.logf("magicsock: DERP packet received from idle peer %v; created=%v", dm.src.ShortString(), discoEp != nil) } } if !c.disableLegacy { asEp = c.addrsByKey[dm.src] } c.mu.Unlock() if discoEp != nil { ep = discoEp } else if asEp != nil { ep = asEp } else { key := wgkey.Key(dm.src) c.logf("magicsock: DERP packet from unknown key: %s", key.ShortString()) ep = c.findEndpoint(ipp, b[:n]) if ep == nil { return 0, nil } } if !didNoteRecvActivity { c.noteRecvActivityFromEndpoint(ep) } 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 ) func (c *Conn) sendDiscoMessage(dst netaddr.IPPort, dstKey tailcfg.NodeKey, dstDisco tailcfg.DiscoKey, m disco.Message, logLevel discoLogLevel) (sent bool, err error) { 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 = append(pkt, c.discoPublic[:]...) pkt = append(pkt, nonce[:]...) sharedKey := c.sharedDiscoKeyLocked(dstDisco) c.mu.Unlock() pkt = box.SealAfterPrecomputation(pkt, m.AppendMarshal(nil), &nonce, sharedKey) sent, err = c.sendAddr(dst, key.Public(dstKey), pkt) if sent { if logLevel == discoLog || (logLevel == discoVerboseLog && debugDisco) { c.logf("[v1] magicsock: disco: %v->%v (%v, %v) sent %v", c.discoShort, dstDisco.ShortString(), dstKey.ShortString(), derpStr(dst.String()), disco.MessageSummary(m)) } } 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 addr will be derpMagicIP (with // port being the region) func (c *Conn) handleDiscoMessage(msg []byte, src netaddr.IPPort) (isDiscoMsg bool) { const headerLen = len(disco.Magic) + len(tailcfg.DiscoKey{}) + disco.NonceLen 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 var sender tailcfg.DiscoKey copy(sender[:], msg[len(disco.Magic):]) 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 } peerNode, ok := c.nodeOfDisco[sender] if !ok { if debugDisco { c.logf("magicsock: disco: ignoring disco-looking frame, don't know node for %v", sender.ShortString()) } return } needsRecvActivityCall := false de, endpointFound0 := c.endpointOfDisco[sender] if !endpointFound0 { // We don't have an active endpoint for this sender but we knew about the node, so // it's an idle endpoint that doesn't yet exist in the wireguard config. We now have // to notify the userspace engine (via noteRecvActivity) so wireguard-go can create // an Endpoint (ultimately calling our ParseEndpoint). c.logf("magicsock: got disco message from idle peer, starting lazy conf for %v, %v", peerNode.Key.ShortString(), sender.ShortString()) if c.noteRecvActivity == nil { c.logf("magicsock: [unexpected] have node without endpoint, without c.noteRecvActivity hook") return } needsRecvActivityCall = true } else { needsRecvActivityCall = de.isFirstRecvActivityInAwhile() } if needsRecvActivityCall && c.noteRecvActivity != nil { // We can't hold Conn.mu while calling noteRecvActivity. // noteRecvActivity acquires userspaceEngine.wgLock (and per our // lock ordering rules: wgLock must come first), and also calls // back into our Conn.ParseEndpoint, which would double-acquire // Conn.mu. c.mu.Unlock() c.noteRecvActivity(sender) c.mu.Lock() // re-acquire // Now, recheck invariants that might've changed while we'd // released the lock, which isn't much: if c.closed || c.privateKey.IsZero() { return } de, ok = c.endpointOfDisco[sender] if !ok { if _, ok := c.nodeOfDisco[sender]; !ok { // They just disappeared while we'd released the lock. return false } c.logf("magicsock: [unexpected] lazy endpoint not created for %v, %v", peerNode.Key.ShortString(), sender.ShortString()) return } if !endpointFound0 { c.logf("magicsock: lazy endpoint created via disco message for %v, %v", peerNode.Key.ShortString(), sender.ShortString()) } } // First, do we even know (and thus care) about this sender? If not, // don't bother decrypting it. var nonce [disco.NonceLen]byte copy(nonce[:], msg[len(disco.Magic)+len(key.Public{}):]) sealedBox := msg[headerLen:] payload, ok := box.OpenAfterPrecomputation(nil, sealedBox, &nonce, c.sharedDiscoKeyLocked(sender)) 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 a wireguard packet (super unlikely, // but). if debugDisco { c.logf("magicsock: disco: failed to open naclbox from %v (wrong rcpt?)", sender) } // TODO(bradfitz): add some counter for this that logs rarely 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. // TODO(bradfitz): add some counter for this that logs rarely return } switch dm := dm.(type) { case *disco.Ping: c.handlePingLocked(dm, de, src, sender, peerNode) case *disco.Pong: if de == nil { return } de.handlePongConnLocked(dm, src) case *disco.CallMeMaybe: if src.IP() != derpMagicIPAddr { // CallMeMaybe messages should only come via DERP. c.logf("[unexpected] CallMeMaybe packets should only come via DERP") return } if de != nil { c.logf("[v1] magicsock: disco: %v<-%v (%v, %v) got call-me-maybe, %d endpoints", c.discoShort, de.discoShort, de.publicKey.ShortString(), derpStr(src.String()), len(dm.MyNumber)) go de.handleCallMeMaybe(dm) } } return } func (c *Conn) handlePingLocked(dm *disco.Ping, de *discoEndpoint, src netaddr.IPPort, sender tailcfg.DiscoKey, peerNode *tailcfg.Node) { if peerNode == nil { c.logf("magicsock: disco: [unexpected] ignoring ping from unknown peer Node") return } likelyHeartBeat := src == de.lastPingFrom && time.Since(de.lastPingTime) < 5*time.Second de.lastPingFrom = src de.lastPingTime = time.Now() if !likelyHeartBeat || debugDisco { c.logf("[v1] magicsock: disco: %v<-%v (%v, %v) got ping tx=%x", c.discoShort, de.discoShort, peerNode.Key.ShortString(), src, dm.TxID[:6]) } // Remember this route if not present. c.setAddrToDiscoLocked(src, sender, nil) de.addCandidateEndpoint(src) ipDst := src discoDest := sender go c.sendDiscoMessage(ipDst, peerNode.Key, 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 netaddr.IPPort, de *discoEndpoint) { c.mu.Lock() defer c.mu.Unlock() if !c.lastEndpointsTime.After(time.Now().Add(-endpointsFreshEnoughDuration)) { c.logf("magicsock: want call-me-maybe but endpoints stale; restunning") if c.onEndpointRefreshed == nil { c.onEndpointRefreshed = map[*discoEndpoint]func(){} } c.onEndpointRefreshed[de] = func() { c.logf("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([]netaddr.IPPort, 0, len(c.lastEndpoints)) for _, ep := range c.lastEndpoints { eps = append(eps, ep.Addr) } go de.sendDiscoMessage(derpAddr, &disco.CallMeMaybe{MyNumber: eps}, discoLog) } // setAddrToDiscoLocked records that newk is at src. // // c.mu must be held. // // If the caller already has a discoEndpoint mutex held as well, it // can be passed in as alreadyLocked so it won't be re-acquired during // any lazy cleanup of the mapping. func (c *Conn) setAddrToDiscoLocked(src netaddr.IPPort, newk tailcfg.DiscoKey, alreadyLocked *discoEndpoint) { oldk, ok := c.discoOfAddr[src] if ok && oldk == newk { return } if ok { c.logf("[v1] magicsock: disco: changing mapping of %v from %x=>%x", src, oldk.ShortString(), newk.ShortString()) } else { c.logf("[v1] magicsock: disco: adding mapping of %v to %v", src, newk.ShortString()) } c.discoOfAddr[src] = newk if !ok { c.cleanDiscoOfAddrLocked(alreadyLocked) } } // cleanDiscoOfAddrLocked lazily checks a few entries in c.discoOfAddr // and deletes them if they're stale. It has no pointers in it so we // don't go through the effort of keeping it aggressively // pruned. Instead, we lazily clean it whenever it grows. // // c.mu must be held. // // If the caller already has a discoEndpoint mutex held as well, it // can be passed in as alreadyLocked so it won't be re-acquired. func (c *Conn) cleanDiscoOfAddrLocked(alreadyLocked *discoEndpoint) { // If it's small enough, don't worry about it. if len(c.discoOfAddr) < 16 { return } const checkEntries = 5 // per one unit of growth // Take advantage of Go's random map iteration to check & clean // a few entries. n := 0 for ipp, dk := range c.discoOfAddr { n++ if n > checkEntries { return } de, ok := c.endpointOfDisco[dk] if !ok { // This discokey isn't even known anymore. Clean. delete(c.discoOfAddr, ipp) continue } if de != alreadyLocked { de.mu.Lock() } if _, ok := de.endpointState[ipp]; !ok { // The discoEndpoint no longer knows about that endpoint. // It must've changed. Clean. delete(c.discoOfAddr, ipp) } if de != alreadyLocked { de.mu.Unlock() } } } func (c *Conn) sharedDiscoKeyLocked(k tailcfg.DiscoKey) *[32]byte { if v, ok := c.sharedDiscoKey[k]; ok { return v } shared := new([32]byte) box.Precompute(shared, key.Public(k).B32(), c.discoPrivate.B32()) c.sharedDiscoKey[k] = shared return shared } func (c *Conn) SetNetworkUp(up bool) { c.mu.Lock() defer c.mu.Unlock() if c.networkUp.Get() == up { return } c.logf("magicsock: SetNetworkUp(%v)", up) c.networkUp.Set(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.Get()) == port { return } c.port.Set(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 wgkey.Private) error { c.mu.Lock() defer c.mu.Unlock() oldKey, newKey := c.privateKey, key.Private(privateKey) if newKey == oldKey { return nil } c.privateKey = newKey c.havePrivateKey.Set(!newKey.IsZero()) if oldKey.IsZero() { c.everHadKey = true c.logf("magicsock: SetPrivateKey called (init)") if c.started { 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() { for _, de := range c.endpointOfDisco { de.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.Public]struct{}) { c.mu.Lock() defer c.mu.Unlock() oldPeers := c.peerSet c.peerSet = newPeers // Clean up any key.Public-keyed maps for peers that no longer // exist. for peer := range oldPeers { if _, ok := newPeers[peer]; !ok { delete(c.addrsByKey, peer) 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.derpMap = dm if dm == nil { c.closeAllDerpLocked("derp-disabled") return } if c.started { 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.netMap != nil && nodesEqual(c.netMap.Peers, nm.Peers) { return } numDisco := 0 for _, n := range nm.Peers { if n.DiscoKey.IsZero() { continue } numDisco++ if ep, ok := c.endpointOfDisco[n.DiscoKey]; ok && ep.publicKey == n.Key { ep.updateFromNode(n) } else if ok { c.logf("magicsock: disco key %v changed from node key %v to %v", n.DiscoKey, ep.publicKey.ShortString(), n.Key.ShortString()) ep.stopAndReset() delete(c.endpointOfDisco, n.DiscoKey) } } c.logf("[v1] magicsock: got updated network map; %d peers (%d with discokey)", len(nm.Peers), numDisco) c.netMap = nm // Build and/or update node<->disco maps, only reallocating if // the set of discokeys changed. for pass := 1; pass <= 2; pass++ { if c.nodeOfDisco == nil || pass == 2 { c.nodeOfDisco = map[tailcfg.DiscoKey]*tailcfg.Node{} c.discoOfNode = map[tailcfg.NodeKey]tailcfg.DiscoKey{} } for _, n := range nm.Peers { if !n.DiscoKey.IsZero() { c.nodeOfDisco[n.DiscoKey] = n if old, ok := c.discoOfNode[n.Key]; ok && old != n.DiscoKey { c.logf("magicsock: node %s changed discovery key from %x to %x", n.Key.ShortString(), old[:8], n.DiscoKey[:8]) } c.discoOfNode[n.Key] = n.DiscoKey } } if len(c.nodeOfDisco) == numDisco && len(c.discoOfNode) == numDisco { break } } // Clean c.endpointOfDisco for discovery keys that are no longer present. for dk, de := range c.endpointOfDisco { if _, ok := c.nodeOfDisco[dk]; !ok { de.stopAndReset() delete(c.endpointOfDisco, dk) delete(c.sharedDiscoKey, 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() } // c.mu must be held. // It is the responsibility of the caller to call logActiveDerpLocked after any set of closes. func (c *Conn) closeDerpLocked(node int, why string) { if ad, ok := c.activeDerp[node]; ok { c.logf("magicsock: closing connection to derp-%v (%v), age %v", node, why, time.Since(ad.createTime).Round(time.Second)) go ad.c.Close() ad.cancel() delete(c.activeDerp, node) } } // 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 } // 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} // 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() // Send an empty read result to unblock receiveDERP, // which will then check connBind.Closed. 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 } if c.derpCleanupTimerArmed { c.derpCleanupTimer.Stop() } c.stopPeriodicReSTUNTimerLocked() c.portMapper.Close() for _, ep := range c.endpointOfDisco { 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. if c.pconn6 != nil { 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.started { panic("call to ReSTUN before Start") } if c.closed { // raced with a shutdown. return } // 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 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.logf("[v1] magicsock: ReSTUN: endpoint update active, need another later (%q)", why) c.wantEndpointsUpdate = why } } else { c.endpointsUpdateActive = true go c.updateEndpoints(why) } } func (c *Conn) initialBind() error { if err := c.bindSocket(&c.pconn4, "udp4", keepCurrentPort); err != nil { return fmt.Errorf("magicsock: initialBind IPv4 failed: %w", err) } c.portMapper.SetLocalPort(c.LocalPort()) if err := c.bindSocket(&c.pconn6, "udp6", keepCurrentPort); err != nil { c.logf("magicsock: ignoring IPv6 bind failure: %v", err) } return nil } // listenPacket opens a packet listener. // The network must be "udp4" or "udp6". // Host is the (local) IP address to listen on; use the zero IP to leave unspecified. func (c *Conn) listenPacket(network string, host netaddr.IP, port uint16) (net.PacketConn, error) { ctx := context.Background() // unused without DNS name to resolve // Translate host to package net: "" for the zero value, the IP address string otherwise. var s string if !host.IsZero() { s = host.String() } addr := net.JoinHostPort(s, fmt.Sprint(port)) if c.packetListener != nil { return c.packetListener.ListenPacket(ctx, network, addr) } return netns.Listener().ListenPacket(ctx, network, addr) } // bindSocket initializes rucPtr if necessary and binds a UDP socket to it. // Network indicates the UDP socket type; it must be "udp4" or "udp6". // If rucPtr had an existing UDP socket bound, it closes that socket. // The caller is responsible for informing the portMapper of any changes. // If curPortFate is set to dropCurrentPort, no attempt is made to reuse // the current port. func (c *Conn) bindSocket(rucPtr **RebindingUDPConn, network string, curPortFate currentPortFate) error { var host netaddr.IP if inTest() && !c.simulatedNetwork { switch network { case "udp4": host = netaddr.MustParseIP("127.0.0.1") case "udp6": host = netaddr.MustParseIP("::1") default: panic("unrecognized network in bindSocket: " + network) } } if *rucPtr == nil { *rucPtr = new(RebindingUDPConn) } ruc := *rucPtr // 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 debugAlwaysDERP { c.logf("disabled %v per TS_DEBUG_ALWAYS_USE_DERP", network) ruc.pconn = 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.Get()); 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, func(i, j int) bool { return ports[i] == ports[j] }) var pconn net.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, host, port) if err != nil { c.logf("magicsock: unable to bind %v port %d: %v", network, port, err) continue } // Success. ruc.pconn = pconn 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.pconn = 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.pconn4, "udp4", curPortFate); err != nil { return fmt.Errorf("magicsock: Rebind IPv4 failed: %w", err) } c.portMapper.SetLocalPort(c.LocalPort()) if err := c.bindSocket(&c.pconn6, "udp6", curPortFate); err != nil { c.logf("magicsock: Rebind ignoring IPv6 bind failure: %v", err) } 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() { if err := c.rebind(keepCurrentPort); err != nil { c.logf("%w", err) return } c.mu.Lock() c.closeAllDerpLocked("rebind") if !c.privateKey.IsZero() { c.startDerpHomeConnectLocked() } c.mu.Unlock() c.resetEndpointStates() } // resetEndpointStates resets the preferred address for all peers and // re-enables spraying. // 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() for _, de := range c.endpointOfDisco { de.noteConnectivityChange() } c.resetAddrSetStatesLocked() } // packIPPort packs an IPPort into the form wanted by WireGuard. func packIPPort(ua netaddr.IPPort) []byte { ip := ua.IP().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. // endpointStr is a json-serialized wgcfg.Endpoints struct. // If those Endpoints contain an active discovery key, ParseEndpoint returns a discoEndpoint. // Otherwise it returns a legacy endpoint. func (c *Conn) ParseEndpoint(endpointStr string) (conn.Endpoint, error) { var endpoints wgcfg.Endpoints err := json.Unmarshal([]byte(endpointStr), &endpoints) if err != nil { return nil, fmt.Errorf("magicsock: ParseEndpoint: json.Unmarshal failed on %q: %w", endpointStr, err) } pk := key.Public(endpoints.PublicKey) discoKey := endpoints.DiscoKey c.logf("magicsock: ParseEndpoint: key=%s: disco=%s ipps=%s", pk.ShortString(), discoKey.ShortString(), derpStr(endpoints.IPPorts.String())) c.mu.Lock() defer c.mu.Unlock() if discoKey.IsZero() { return c.createLegacyEndpointLocked(pk, endpoints.IPPorts, endpointStr) } de := &discoEndpoint{ c: c, publicKey: tailcfg.NodeKey(pk), // peer public key (for WireGuard + DERP) discoKey: tailcfg.DiscoKey(discoKey), // for discovery mesages discoShort: tailcfg.DiscoKey(discoKey).ShortString(), wgEndpoint: endpointStr, sentPing: map[stun.TxID]sentPing{}, endpointState: map[netaddr.IPPort]*endpointState{}, } de.initFakeUDPAddr() de.updateFromNode(c.nodeOfDisco[de.discoKey]) c.endpointOfDisco[de.discoKey] = de return de, nil } // 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 { mu sync.Mutex pconn net.PacketConn } // currentConn returns c's current pconn. func (c *RebindingUDPConn) currentConn() net.PacketConn { c.mu.Lock() defer c.mu.Unlock() return c.pconn } // 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) { for { pconn := c.currentConn() n, addr, err := pconn.ReadFrom(b) if err != nil && pconn != c.currentConn() { continue } return n, addr, err } } // 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 netaddr.IPPort 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 netaddr.IPPort, err error) { for { pconn := c.currentConn() // Optimization: Treat *net.UDPConn specially. // ReadFromUDP gets partially inlined, avoiding allocating a *net.UDPAddr, // as long as pAddr itself doesn't escape. // The non-*net.UDPConn case works, but it allocates. var pAddr *net.UDPAddr if udpConn, ok := pconn.(*net.UDPConn); ok { n, pAddr, err = udpConn.ReadFromUDP(b) } else { var addr net.Addr n, addr, err = pconn.ReadFrom(b) if addr != nil { pAddr, ok = addr.(*net.UDPAddr) if !ok { return 0, netaddr.IPPort{}, fmt.Errorf("RebindingUDPConn.ReadFromNetaddr: underlying connection returned address of type %T, want *netaddr.UDPAddr", addr) } } } if err != nil { if pconn != c.currentConn() { continue } } else { // Convert pAddr to a netaddr.IPPort. // This prevents pAddr from escaping. var ok bool ipp, ok = netaddr.FromStdAddr(pAddr.IP, pAddr.Port, pAddr.Zone) if !ok { return 0, netaddr.IPPort{}, errors.New("netaddr.FromStdAddr failed") } } return n, ipp, err } } 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 } return c.pconn.Close() } func (c *RebindingUDPConn) WriteTo(b []byte, addr net.Addr) (int, error) { for { c.mu.Lock() pconn := c.pconn c.mu.Unlock() n, err := pconn.WriteTo(b, addr) if err != nil { c.mu.Lock() pconn2 := c.pconn c.mu.Unlock() if pconn != pconn2 { 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) 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 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 peerShort(k key.Public) string { k2 := wgkey.Key(k) return k2.ShortString() } func sbPrintAddr(sb *strings.Builder, a netaddr.IPPort) { is6 := a.IP().Is6() if is6 { sb.WriteByte('[') } fmt.Fprintf(sb, "%s", a.IP()) 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 tailAddr4 string var tailscaleIPs []netaddr.IP if c.netMap != nil { tailscaleIPs = make([]netaddr.IP, 0, len(c.netMap.Addresses)) for _, addr := range c.netMap.Addresses { if !addr.IsSingleIP() { continue } sb.AddTailscaleIP(addr.IP()) // TailAddr previously only allowed for a // single Tailscale IP. For compatibility for // a couple releases starting with 1.8, keep // that field pulled out separately. if addr.IP().Is4() { tailAddr4 = addr.IP().String() } tailscaleIPs = append(tailscaleIPs, addr.IP()) } } sb.MutateSelfStatus(func(ss *ipnstate.PeerStatus) { ss.PublicKey = c.privateKey.Public() 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.netMap != nil { ss.HostName = c.netMap.Hostinfo.Hostname ss.DNSName = c.netMap.Name ss.UserID = c.netMap.User if c.netMap.SelfNode != nil { if c := c.netMap.SelfNode.Capabilities; len(c) > 0 { ss.Capabilities = append([]string(nil), c...) } } } else { ss.HostName, _ = os.Hostname() } if c.derpMap != nil { derpRegion, ok := c.derpMap.Regions[c.myDerp] if ok { ss.Relay = derpRegion.RegionCode } } ss.TailscaleIPs = tailscaleIPs ss.TailAddrDeprecated = tailAddr4 }) for dk, n := range c.nodeOfDisco { ps := &ipnstate.PeerStatus{InMagicSock: true} ps.Addrs = append(ps.Addrs, n.Endpoints...) ps.Relay = c.derpRegionCodeOfAddrLocked(n.DERP) if de, ok := c.endpointOfDisco[dk]; ok { de.populatePeerStatus(ps) } sb.AddPeer(key.Public(n.Key), ps) } // Old-style (pre-disco) peers: for k, as := range c.addrsByKey { ps := &ipnstate.PeerStatus{ InMagicSock: true, Relay: c.derpRegionCodeOfIDLocked(as.derpID()), } as.populatePeerStatus(ps) sb.AddPeer(k, 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))) }) } func ippDebugString(ua netaddr.IPPort) string { if ua.IP() == derpMagicIPAddr { return fmt.Sprintf("derp-%d", ua.Port()) } return ua.String() } // discoEndpoint is a wireguard/conn.Endpoint for new-style peers that // advertise a DiscoKey and participate in active discovery. type discoEndpoint struct { // atomically accessed; declared first for alignment reasons lastRecv mono.Time numStopAndResetAtomic int64 // These fields are initialized once and never modified. c *Conn publicKey tailcfg.NodeKey // peer public key (for WireGuard + DERP) discoKey tailcfg.DiscoKey // for discovery mesages discoShort string // ShortString of discoKey fakeWGAddr netaddr.IPPort // the UDP address we tell wireguard-go we're using wgEndpoint string // string from ParseEndpoint, holds a JSON-serialized wgcfg.Endpoints // Owned by Conn.mu: lastPingFrom netaddr.IPPort lastPingTime time.Time // mu protects all following fields. mu sync.Mutex // Lock ordering: Conn.mu, then discoEndpoint.mu 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 netaddr.IPPort // 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[netaddr.IPPort]*endpointState isCallMeMaybeEP map[netaddr.IPPort]bool pendingCLIPings []pendingCLIPing // any outstanding "tailscale ping" commands running } 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 discoEndpoint peering alive. // It's also the idle time at which we stop doing STUN queries to // keep NAT mappings alive. sessionActiveTimeout = 2 * time.Minute // 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 = 2 * 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 // pingTimeoutDuration is how long we wait for a pong reply before // assuming it's never coming. pingTimeoutDuration = 5 * 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 = 5 * time.Second // 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 ) // endpointState is some state and history for a specific endpoint of // a discoEndpoint. (The subject is the discoEndpoint.endpointState // map key) type endpointState struct { // all fields guarded by discoEndpoint.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 // 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 discoEndpoint'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 *discoEndpoint) deleteEndpointLocked(ep netaddr.IPPort) { delete(de.endpointState, ep) if de.bestAddr.IPPort == 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 netaddr.IPPort // the pong's src (usually same as endpoint map key) pongSrc netaddr.IPPort // what they reported they heard } type sentPing struct { to netaddr.IPPort 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 *discoEndpoint) initFakeUDPAddr() { var addr [16]byte addr[0] = 0xfd addr[1] = 0x00 binary.BigEndian.PutUint64(addr[2:], uint64(reflect.ValueOf(de).Pointer())) de.fakeWGAddr = netaddr.IPPortFrom(netaddr.IPFrom16(addr), 12345) } // isFirstRecvActivityInAwhile notes that receive activity has occured for this // endpoint and reports whether it's been at least 10 seconds since the last // receive activity (including having never received from this peer before). func (de *discoEndpoint) isFirstRecvActivityInAwhile() bool { now := mono.Now() elapsed := now.Sub(de.lastRecv.LoadAtomic()) if elapsed > 10*time.Second { de.lastRecv.StoreAtomic(now) return true } return false } // 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 *discoEndpoint) String() string { return fmt.Sprintf("magicsock.discoEndpoint{%v, %v}", de.publicKey.ShortString(), de.discoShort) } func (de *discoEndpoint) ClearSrc() {} func (de *discoEndpoint) SrcToString() string { panic("unused") } // unused by wireguard-go func (de *discoEndpoint) SrcIP() net.IP { panic("unused") } // unused by wireguard-go func (de *discoEndpoint) DstToString() string { return de.wgEndpoint } func (de *discoEndpoint) DstIP() net.IP { panic("unused") } func (de *discoEndpoint) 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 *discoEndpoint) addrForSendLocked(now mono.Time) (udpAddr, derpAddr netaddr.IPPort) { udpAddr = de.bestAddr.IPPort if udpAddr.IsZero() || 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 *discoEndpoint) heartbeat() { de.mu.Lock() defer de.mu.Unlock() de.heartBeatTimer = nil if de.lastSend.IsZero() { // Shouldn't happen. return } if mono.Since(de.lastSend) > sessionActiveTimeout { // Session's idle. Stop heartbeating. de.c.logf("[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.IsZero() { // 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 *discoEndpoint) wantFullPingLocked(now mono.Time) bool { if de.bestAddr.IsZero() || 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 *discoEndpoint) noteActiveLocked() { de.lastSend = mono.Now() if de.heartBeatTimer == nil { 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 *discoEndpoint) cliPing(res *ipnstate.PingResult, cb func(*ipnstate.PingResult)) { de.mu.Lock() defer de.mu.Unlock() de.pendingCLIPings = append(de.pendingCLIPings, pendingCLIPing{res, cb}) now := mono.Now() udpAddr, derpAddr := de.addrForSendLocked(now) if !derpAddr.IsZero() { de.startPingLocked(derpAddr, now, pingCLI) } if !udpAddr.IsZero() && 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() } func (de *discoEndpoint) send(b []byte) error { now := mono.Now() de.mu.Lock() udpAddr, derpAddr := de.addrForSendLocked(now) if udpAddr.IsZero() || now.After(de.trustBestAddrUntil) { de.sendPingsLocked(now, true) } de.noteActiveLocked() de.mu.Unlock() if udpAddr.IsZero() && derpAddr.IsZero() { return errors.New("no UDP or DERP addr") } var err error if !udpAddr.IsZero() { _, err = de.c.sendAddr(udpAddr, key.Public(de.publicKey), b) } if !derpAddr.IsZero() { if ok, _ := de.c.sendAddr(derpAddr, key.Public(de.publicKey), b); ok && err != nil { // UDP failed but DERP worked, so good enough: return nil } } return err } func (de *discoEndpoint) pingTimeout(txid stun.TxID) { de.mu.Lock() defer de.mu.Unlock() sp, ok := de.sentPing[txid] if !ok { return } if debugDisco || de.bestAddr.IsZero() || mono.Now().After(de.trustBestAddrUntil) { de.c.logf("[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 *discoEndpoint) forgetPing(txid stun.TxID) { de.mu.Lock() defer de.mu.Unlock() if sp, ok := de.sentPing[txid]; ok { de.removeSentPingLocked(txid, sp) } } func (de *discoEndpoint) 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. // // The caller (startPingLocked) should've already been recorded the ping in // sentPing and set up the timer. func (de *discoEndpoint) sendDiscoPing(ep netaddr.IPPort, txid stun.TxID, logLevel discoLogLevel) { sent, _ := de.sendDiscoMessage(ep, &disco.Ping{TxID: [12]byte(txid)}, 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 -year 2020 -file discopingpurpose_string.go 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 *discoEndpoint) startPingLocked(ep netaddr.IPPort, now mono.Time, purpose discoPingPurpose) { 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, txid, logLevel) } func (de *discoEndpoint) 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 !st.lastPing.IsZero() && now.Sub(st.lastPing) < discoPingInterval { continue } firstPing := !sentAny sentAny = true if firstPing && sendCallMeMaybe { de.c.logf("[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.IsZero() { // 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 *discoEndpoint) sendDiscoMessage(dst netaddr.IPPort, dm disco.Message, logLevel discoLogLevel) (sent bool, err error) { return de.c.sendDiscoMessage(dst, de.publicKey, de.discoKey, dm, logLevel) } func (de *discoEndpoint) updateFromNode(n *tailcfg.Node) { if n == nil { // TODO: log, error, count? if this even happens. return } de.mu.Lock() defer de.mu.Unlock() if n.DERP == "" { de.derpAddr = netaddr.IPPort{} } else { de.derpAddr, _ = netaddr.ParseIPPort(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 := netaddr.ParseIPPort(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) } } } // addCandidateEndpoint adds ep as an endpoint to which we should send // future pings. // // This is called once we've already verified that we got a valid // discovery message from de via ep. func (de *discoEndpoint) addCandidateEndpoint(ep netaddr.IPPort) { de.mu.Lock() defer de.mu.Unlock() if st, ok := de.endpointState[ep]; ok { if st.lastGotPing.IsZero() { // Already-known endpoint from the network map. return } st.lastGotPing = time.Now() return } // Newly discovered endpoint. Exciting! de.c.logf("[v1] magicsock: disco: adding %v as candidate endpoint for %v (%s)", ep, de.discoShort, de.publicKey.ShortString()) de.endpointState[ep] = &endpointState{ lastGotPing: time.Now(), } // 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.logf("[v1] magicsock: disco: addCandidateEndpoint pruned %v candidate set from %v to %v entries", size, size2) } } // noteConnectivityChange is called when connectivity changes enough // that we should question our earlier assumptions about which paths // work. func (de *discoEndpoint) 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. func (de *discoEndpoint) handlePongConnLocked(m *disco.Pong, src netaddr.IPPort) { de.mu.Lock() defer de.mu.Unlock() isDerp := src.IP() == derpMagicIPAddr sp, ok := de.sentPing[m.TxID] if !ok { // This is not a pong for a ping we sent. Ignore. return } de.removeSentPingLocked(m.TxID, sp) 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.setAddrToDiscoLocked(src, de.discoKey, de) st.addPongReplyLocked(pongReply{ latency: latency, pongAt: now, from: src, pongSrc: m.Src, }) } if sp.purpose != pingHeartbeat { de.c.logf("[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.IPPort == thisPong.IPPort { de.bestAddr.latency = latency de.bestAddrAt = now de.trustBestAddrUntil = now.Add(trustUDPAddrDuration) } } } // addrLatency is an IPPort with an associated latency. type addrLatency struct { netaddr.IPPort latency time.Duration } // betterAddr reports whether a is a better addr to use than b. func betterAddr(a, b addrLatency) bool { if a.IPPort == b.IPPort { return false } if b.IsZero() { return true } if a.IsZero() { return false } if a.IP().Is6() && b.IP().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.IP().Is4() && b.IP().Is6() { if betterAddr(b, a) { return false } } return a.latency < b.latency } // discoEndpoint.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 *discoEndpoint) handleCallMeMaybe(m *disco.CallMeMaybe) { de.mu.Lock() defer de.mu.Unlock() now := time.Now() for ep := range de.isCallMeMaybeEP { de.isCallMeMaybeEP[ep] = false // mark for deletion } if de.isCallMeMaybeEP == nil { de.isCallMeMaybeEP = map[netaddr.IPPort]bool{} } var newEPs []netaddr.IPPort for _, ep := range m.MyNumber { if ep.IP().Is6() && ep.IP().IsLinkLocalUnicast() { // We send these out, but ignore them for now. // TODO: teach the ping code to ping on all interfaces // for these. continue } 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.logf("[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 CalllMeMaybe 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 *discoEndpoint) populatePeerStatus(ps *ipnstate.PeerStatus) { de.mu.Lock() defer de.mu.Unlock() if de.lastSend.IsZero() { return } ps.LastWrite = de.lastSend now := mono.Now() if udpAddr, derpAddr := de.addrForSendLocked(now); !udpAddr.IsZero() && derpAddr.IsZero() { 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 transition from running to stopped state (via SetPrivateKey(zero)) func (de *discoEndpoint) stopAndReset() { atomic.AddInt64(&de.numStopAndResetAtomic, 1) de.mu.Lock() defer de.mu.Unlock() de.c.logf("[v1] magicsock: doing cleanup for discovery key %x", de.discoKey[:]) // Zero these fields so if the user re-starts the network, the discovery // state isn't a mix of before & after two sessions. 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) } if de.heartBeatTimer != nil { de.heartBeatTimer.Stop() de.heartBeatTimer = nil } de.pendingCLIPings = nil } func (de *discoEndpoint) 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 netaddr.IPPort to a single endpoint. type ippEndpointCache struct { ipp netaddr.IPPort gen int64 de *discoEndpoint }