package headscale import ( "context" "crypto/tls" "errors" "fmt" "io" "io/fs" "net" "net/http" "net/url" "os" "os/signal" "sort" "strings" "sync" "syscall" "time" "github.com/coreos/go-oidc/v3/oidc" "github.com/gin-gonic/gin" grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware" "github.com/grpc-ecosystem/grpc-gateway/v2/runtime" v1 "github.com/juanfont/headscale/gen/go/headscale/v1" "github.com/patrickmn/go-cache" zerolog "github.com/philip-bui/grpc-zerolog" zl "github.com/rs/zerolog" "github.com/rs/zerolog/log" ginprometheus "github.com/zsais/go-gin-prometheus" "golang.org/x/crypto/acme" "golang.org/x/crypto/acme/autocert" "golang.org/x/oauth2" "golang.org/x/sync/errgroup" "google.golang.org/grpc" "google.golang.org/grpc/codes" "google.golang.org/grpc/credentials" "google.golang.org/grpc/credentials/insecure" "google.golang.org/grpc/metadata" "google.golang.org/grpc/peer" "google.golang.org/grpc/reflection" "google.golang.org/grpc/status" "gorm.io/gorm" "inet.af/netaddr" "tailscale.com/tailcfg" "tailscale.com/types/dnstype" "tailscale.com/types/key" ) const ( AuthPrefix = "Bearer " Postgres = "postgres" Sqlite = "sqlite3" updateInterval = 5000 HTTPReadTimeout = 30 * time.Second privateKeyFileMode = 0o600 registerCacheExpiration = time.Minute * 15 registerCacheCleanup = time.Minute * 20 errUnsupportedDatabase = Error("unsupported DB") errUnsupportedLetsEncryptChallengeType = Error( "unknown value for Lets Encrypt challenge type", ) DisabledClientAuth = "disabled" RelaxedClientAuth = "relaxed" EnforcedClientAuth = "enforced" ) // Config contains the initial Headscale configuration. type Config struct { ServerURL string Addr string MetricsAddr string GRPCAddr string GRPCAllowInsecure bool EphemeralNodeInactivityTimeout time.Duration IPPrefixes []netaddr.IPPrefix PrivateKeyPath string BaseDomain string DERP DERPConfig DBtype string DBpath string DBhost string DBport int DBname string DBuser string DBpass string TLSLetsEncryptListen string TLSLetsEncryptHostname string TLSLetsEncryptCacheDir string TLSLetsEncryptChallengeType string TLSCertPath string TLSKeyPath string TLSClientAuthMode tls.ClientAuthType ACMEURL string ACMEEmail string DNSConfig *tailcfg.DNSConfig UnixSocket string UnixSocketPermission fs.FileMode OIDC OIDCConfig CLI CLIConfig } type OIDCConfig struct { Issuer string ClientID string ClientSecret string StripEmaildomain bool } type DERPConfig struct { ServerEnabled bool ServerRegionID int ServerRegionCode string ServerRegionName string STUNEnabled bool STUNAddr string URLs []url.URL Paths []string AutoUpdate bool UpdateFrequency time.Duration } type CLIConfig struct { Address string APIKey string Timeout time.Duration Insecure bool } // Headscale represents the base app of the service. type Headscale struct { cfg Config db *gorm.DB dbString string dbType string dbDebug bool privateKey *key.MachinePrivate DERPMap *tailcfg.DERPMap DERPServer *DERPServer aclPolicy *ACLPolicy aclRules []tailcfg.FilterRule lastStateChange sync.Map oidcProvider *oidc.Provider oauth2Config *oauth2.Config registrationCache *cache.Cache ipAllocationMutex sync.Mutex } // Look up the TLS constant relative to user-supplied TLS client // authentication mode. If an unknown mode is supplied, the default // value, tls.RequireAnyClientCert, is returned. The returned boolean // indicates if the supplied mode was valid. func LookupTLSClientAuthMode(mode string) (tls.ClientAuthType, bool) { switch mode { case DisabledClientAuth: // Client cert is _not_ required. return tls.NoClientCert, true case RelaxedClientAuth: // Client cert required, but _not verified_. return tls.RequireAnyClientCert, true case EnforcedClientAuth: // Client cert is _required and verified_. return tls.RequireAndVerifyClientCert, true default: // Return the default when an unknown value is supplied. return tls.RequireAnyClientCert, false } } func NewHeadscale(cfg Config) (*Headscale, error) { privKey, err := readOrCreatePrivateKey(cfg.PrivateKeyPath) if err != nil { return nil, fmt.Errorf("failed to read or create private key: %w", err) } var dbString string switch cfg.DBtype { case Postgres: dbString = fmt.Sprintf( "host=%s port=%d dbname=%s user=%s password=%s sslmode=disable", cfg.DBhost, cfg.DBport, cfg.DBname, cfg.DBuser, cfg.DBpass, ) case Sqlite: dbString = cfg.DBpath default: return nil, errUnsupportedDatabase } registrationCache := cache.New( registerCacheExpiration, registerCacheCleanup, ) app := Headscale{ cfg: cfg, dbType: cfg.DBtype, dbString: dbString, privateKey: privKey, aclRules: tailcfg.FilterAllowAll, // default allowall registrationCache: registrationCache, } err = app.initDB() if err != nil { return nil, err } if cfg.OIDC.Issuer != "" { err = app.initOIDC() if err != nil { return nil, err } } if app.cfg.DNSConfig != nil && app.cfg.DNSConfig.Proxied { // if MagicDNS magicDNSDomains := generateMagicDNSRootDomains(app.cfg.IPPrefixes) // we might have routes already from Split DNS if app.cfg.DNSConfig.Routes == nil { app.cfg.DNSConfig.Routes = make(map[string][]dnstype.Resolver) } for _, d := range magicDNSDomains { app.cfg.DNSConfig.Routes[d.WithoutTrailingDot()] = nil } } if cfg.DERP.ServerEnabled { embeddedDERPServer, err := app.NewDERPServer() if err != nil { return nil, err } app.DERPServer = embeddedDERPServer } return &app, nil } // Redirect to our TLS url. func (h *Headscale) redirect(w http.ResponseWriter, req *http.Request) { target := h.cfg.ServerURL + req.URL.RequestURI() http.Redirect(w, req, target, http.StatusFound) } // expireEphemeralNodes deletes ephemeral machine records that have not been // seen for longer than h.cfg.EphemeralNodeInactivityTimeout. func (h *Headscale) expireEphemeralNodes(milliSeconds int64) { ticker := time.NewTicker(time.Duration(milliSeconds) * time.Millisecond) for range ticker.C { h.expireEphemeralNodesWorker() } } func (h *Headscale) expireEphemeralNodesWorker() { namespaces, err := h.ListNamespaces() if err != nil { log.Error().Err(err).Msg("Error listing namespaces") return } for _, namespace := range namespaces { machines, err := h.ListMachinesInNamespace(namespace.Name) if err != nil { log.Error(). Err(err). Str("namespace", namespace.Name). Msg("Error listing machines in namespace") return } for _, machine := range machines { if machine.AuthKey != nil && machine.LastSeen != nil && machine.AuthKey.Ephemeral && time.Now(). After(machine.LastSeen.Add(h.cfg.EphemeralNodeInactivityTimeout)) { log.Info(). Str("machine", machine.Name). Msg("Ephemeral client removed from database") err = h.db.Unscoped().Delete(machine).Error if err != nil { log.Error(). Err(err). Str("machine", machine.Name). Msg("🤮 Cannot delete ephemeral machine from the database") } } } h.setLastStateChangeToNow(namespace.Name) } } func (h *Headscale) grpcAuthenticationInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) { // Check if the request is coming from the on-server client. // This is not secure, but it is to maintain maintainability // with the "legacy" database-based client // It is also neede for grpc-gateway to be able to connect to // the server client, _ := peer.FromContext(ctx) log.Trace(). Caller(). Str("client_address", client.Addr.String()). Msg("Client is trying to authenticate") meta, ok := metadata.FromIncomingContext(ctx) if !ok { log.Error(). Caller(). Str("client_address", client.Addr.String()). Msg("Retrieving metadata is failed") return ctx, status.Errorf( codes.InvalidArgument, "Retrieving metadata is failed", ) } authHeader, ok := meta["authorization"] if !ok { log.Error(). Caller(). Str("client_address", client.Addr.String()). Msg("Authorization token is not supplied") return ctx, status.Errorf( codes.Unauthenticated, "Authorization token is not supplied", ) } token := authHeader[0] if !strings.HasPrefix(token, AuthPrefix) { log.Error(). Caller(). Str("client_address", client.Addr.String()). Msg(`missing "Bearer " prefix in "Authorization" header`) return ctx, status.Error( codes.Unauthenticated, `missing "Bearer " prefix in "Authorization" header`, ) } valid, err := h.ValidateAPIKey(strings.TrimPrefix(token, AuthPrefix)) if err != nil { log.Error(). Caller(). Err(err). Str("client_address", client.Addr.String()). Msg("failed to validate token") return ctx, status.Error(codes.Internal, "failed to validate token") } if !valid { log.Info(). Str("client_address", client.Addr.String()). Msg("invalid token") return ctx, status.Error(codes.Unauthenticated, "invalid token") } return handler(ctx, req) } func (h *Headscale) httpAuthenticationMiddleware(ctx *gin.Context) { log.Trace(). Caller(). Str("client_address", ctx.ClientIP()). Msg("HTTP authentication invoked") authHeader := ctx.GetHeader("authorization") if !strings.HasPrefix(authHeader, AuthPrefix) { log.Error(). Caller(). Str("client_address", ctx.ClientIP()). Msg(`missing "Bearer " prefix in "Authorization" header`) ctx.AbortWithStatus(http.StatusUnauthorized) return } ctx.AbortWithStatus(http.StatusUnauthorized) valid, err := h.ValidateAPIKey(strings.TrimPrefix(authHeader, AuthPrefix)) if err != nil { log.Error(). Caller(). Err(err). Str("client_address", ctx.ClientIP()). Msg("failed to validate token") ctx.AbortWithStatus(http.StatusInternalServerError) return } if !valid { log.Info(). Str("client_address", ctx.ClientIP()). Msg("invalid token") ctx.AbortWithStatus(http.StatusUnauthorized) return } ctx.Next() } // ensureUnixSocketIsAbsent will check if the given path for headscales unix socket is clear // and will remove it if it is not. func (h *Headscale) ensureUnixSocketIsAbsent() error { // File does not exist, all fine if _, err := os.Stat(h.cfg.UnixSocket); errors.Is(err, os.ErrNotExist) { return nil } return os.Remove(h.cfg.UnixSocket) } func (h *Headscale) createPrometheusRouter() *gin.Engine { promRouter := gin.Default() prometheus := ginprometheus.NewPrometheus("gin") prometheus.Use(promRouter) return promRouter } func (h *Headscale) createRouter(grpcMux *runtime.ServeMux) *gin.Engine { router := gin.Default() router.GET( "/health", func(c *gin.Context) { c.JSON(http.StatusOK, gin.H{"healthy": "ok"}) }, ) router.GET("/key", h.KeyHandler) router.GET("/register", h.RegisterWebAPI) router.POST("/machine/:id/map", h.PollNetMapHandler) router.POST("/machine/:id", h.RegistrationHandler) router.GET("/oidc/register/:mkey", h.RegisterOIDC) router.GET("/oidc/callback", h.OIDCCallback) router.GET("/apple", h.AppleConfigMessage) router.GET("/apple/:platform", h.ApplePlatformConfig) router.GET("/windows", h.WindowsConfigMessage) router.GET("/windows/tailscale.reg", h.WindowsRegConfig) router.GET("/swagger", SwaggerUI) router.GET("/swagger/v1/openapiv2.json", SwaggerAPIv1) if h.cfg.DERP.ServerEnabled { router.Any("/derp", h.DERPHandler) router.Any("/derp/probe", h.DERPProbeHandler) router.Any("/bootstrap-dns", h.DERPBootstrapDNSHandler) } api := router.Group("/api") api.Use(h.httpAuthenticationMiddleware) { api.Any("/v1/*any", gin.WrapF(grpcMux.ServeHTTP)) } router.NoRoute(stdoutHandler) return router } // Serve launches a GIN server with the Headscale API. func (h *Headscale) Serve() error { var err error // Fetch an initial DERP Map before we start serving h.DERPMap = GetDERPMap(h.cfg.DERP) if h.cfg.DERP.ServerEnabled { h.DERPMap.Regions[h.DERPServer.region.RegionID] = &h.DERPServer.region if h.cfg.DERP.STUNEnabled { go h.ServeSTUN() } } if h.cfg.DERP.AutoUpdate { derpMapCancelChannel := make(chan struct{}) defer func() { derpMapCancelChannel <- struct{}{} }() go h.scheduledDERPMapUpdateWorker(derpMapCancelChannel) } go h.expireEphemeralNodes(updateInterval) if zl.GlobalLevel() == zl.TraceLevel { zerolog.RespLog = true } else { zerolog.RespLog = false } // Prepare group for running listeners errorGroup := new(errgroup.Group) ctx := context.Background() ctx, cancel := context.WithCancel(ctx) defer cancel() // // // Set up LOCAL listeners // err = h.ensureUnixSocketIsAbsent() if err != nil { return fmt.Errorf("unable to remove old socket file: %w", err) } socketListener, err := net.Listen("unix", h.cfg.UnixSocket) if err != nil { return fmt.Errorf("failed to set up gRPC socket: %w", err) } // Change socket permissions if err := os.Chmod(h.cfg.UnixSocket, h.cfg.UnixSocketPermission); err != nil { return fmt.Errorf("failed change permission of gRPC socket: %w", err) } // Handle common process-killing signals so we can gracefully shut down: sigc := make(chan os.Signal, 1) signal.Notify(sigc, os.Interrupt, syscall.SIGTERM) go func(c chan os.Signal) { // Wait for a SIGINT or SIGKILL: sig := <-c log.Printf("Caught signal %s: shutting down.", sig) // Stop listening (and unlink the socket if unix type): socketListener.Close() // And we're done: os.Exit(0) }(sigc) grpcGatewayMux := runtime.NewServeMux() // Make the grpc-gateway connect to grpc over socket grpcGatewayConn, err := grpc.Dial( h.cfg.UnixSocket, []grpc.DialOption{ grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithContextDialer(GrpcSocketDialer), }..., ) if err != nil { return err } // Connect to the gRPC server over localhost to skip // the authentication. err = v1.RegisterHeadscaleServiceHandler(ctx, grpcGatewayMux, grpcGatewayConn) if err != nil { return err } // Start the local gRPC server without TLS and without authentication grpcSocket := grpc.NewServer(zerolog.UnaryInterceptor()) v1.RegisterHeadscaleServiceServer(grpcSocket, newHeadscaleV1APIServer(h)) reflection.Register(grpcSocket) errorGroup.Go(func() error { return grpcSocket.Serve(socketListener) }) // // // Set up REMOTE listeners // tlsConfig, err := h.getTLSSettings() if err != nil { log.Error().Err(err).Msg("Failed to set up TLS configuration") return err } // // // gRPC setup // // We are sadly not able to run gRPC and HTTPS (2.0) on the same // port because the connection mux does not support matching them // since they are so similar. There is multiple issues open and we // can revisit this if changes: // https://github.com/soheilhy/cmux/issues/68 // https://github.com/soheilhy/cmux/issues/91 if tlsConfig != nil || h.cfg.GRPCAllowInsecure { log.Info().Msgf("Enabling remote gRPC at %s", h.cfg.GRPCAddr) grpcOptions := []grpc.ServerOption{ grpc.UnaryInterceptor( grpc_middleware.ChainUnaryServer( h.grpcAuthenticationInterceptor, zerolog.NewUnaryServerInterceptor(), ), ), } if tlsConfig != nil { grpcOptions = append(grpcOptions, grpc.Creds(credentials.NewTLS(tlsConfig)), ) } else { log.Warn().Msg("gRPC is running without security") } grpcServer := grpc.NewServer(grpcOptions...) v1.RegisterHeadscaleServiceServer(grpcServer, newHeadscaleV1APIServer(h)) reflection.Register(grpcServer) grpcListener, err := net.Listen("tcp", h.cfg.GRPCAddr) if err != nil { return fmt.Errorf("failed to bind to TCP address: %w", err) } errorGroup.Go(func() error { return grpcServer.Serve(grpcListener) }) log.Info(). Msgf("listening and serving gRPC on: %s", h.cfg.GRPCAddr) } // // // HTTP setup // router := h.createRouter(grpcGatewayMux) httpServer := &http.Server{ Addr: h.cfg.Addr, Handler: router, ReadTimeout: HTTPReadTimeout, // Go does not handle timeouts in HTTP very well, and there is // no good way to handle streaming timeouts, therefore we need to // keep this at unlimited and be careful to clean up connections // https://blog.cloudflare.com/the-complete-guide-to-golang-net-http-timeouts/#aboutstreaming WriteTimeout: 0, } var httpListener net.Listener if tlsConfig != nil { httpServer.TLSConfig = tlsConfig httpListener, err = tls.Listen("tcp", h.cfg.Addr, tlsConfig) } else { httpListener, err = net.Listen("tcp", h.cfg.Addr) } if err != nil { return fmt.Errorf("failed to bind to TCP address: %w", err) } errorGroup.Go(func() error { return httpServer.Serve(httpListener) }) log.Info(). Msgf("listening and serving HTTP on: %s", h.cfg.Addr) promRouter := h.createPrometheusRouter() promHTTPServer := &http.Server{ Addr: h.cfg.MetricsAddr, Handler: promRouter, ReadTimeout: HTTPReadTimeout, WriteTimeout: 0, } var promHTTPListener net.Listener promHTTPListener, err = net.Listen("tcp", h.cfg.MetricsAddr) if err != nil { return fmt.Errorf("failed to bind to TCP address: %w", err) } errorGroup.Go(func() error { return promHTTPServer.Serve(promHTTPListener) }) log.Info(). Msgf("listening and serving metrics on: %s", h.cfg.MetricsAddr) return errorGroup.Wait() } func (h *Headscale) getTLSSettings() (*tls.Config, error) { var err error if h.cfg.TLSLetsEncryptHostname != "" { if !strings.HasPrefix(h.cfg.ServerURL, "https://") { log.Warn(). Msg("Listening with TLS but ServerURL does not start with https://") } certManager := autocert.Manager{ Prompt: autocert.AcceptTOS, HostPolicy: autocert.HostWhitelist(h.cfg.TLSLetsEncryptHostname), Cache: autocert.DirCache(h.cfg.TLSLetsEncryptCacheDir), Client: &acme.Client{ DirectoryURL: h.cfg.ACMEURL, }, Email: h.cfg.ACMEEmail, } switch h.cfg.TLSLetsEncryptChallengeType { case "TLS-ALPN-01": // Configuration via autocert with TLS-ALPN-01 (https://tools.ietf.org/html/rfc8737) // The RFC requires that the validation is done on port 443; in other words, headscale // must be reachable on port 443. return certManager.TLSConfig(), nil case "HTTP-01": // Configuration via autocert with HTTP-01. This requires listening on // port 80 for the certificate validation in addition to the headscale // service, which can be configured to run on any other port. go func() { log.Fatal(). Caller(). Err(http.ListenAndServe(h.cfg.TLSLetsEncryptListen, certManager.HTTPHandler(http.HandlerFunc(h.redirect)))). Msg("failed to set up a HTTP server") }() return certManager.TLSConfig(), nil default: return nil, errUnsupportedLetsEncryptChallengeType } } else if h.cfg.TLSCertPath == "" { if !strings.HasPrefix(h.cfg.ServerURL, "http://") { log.Warn().Msg("Listening without TLS but ServerURL does not start with http://") } return nil, err } else { if !strings.HasPrefix(h.cfg.ServerURL, "https://") { log.Warn().Msg("Listening with TLS but ServerURL does not start with https://") } log.Info().Msg(fmt.Sprintf( "Client authentication (mTLS) is \"%s\". See the docs to learn about configuring this setting.", h.cfg.TLSClientAuthMode)) tlsConfig := &tls.Config{ ClientAuth: h.cfg.TLSClientAuthMode, NextProtos: []string{"http/1.1"}, Certificates: make([]tls.Certificate, 1), MinVersion: tls.VersionTLS12, } tlsConfig.Certificates[0], err = tls.LoadX509KeyPair(h.cfg.TLSCertPath, h.cfg.TLSKeyPath) return tlsConfig, err } } func (h *Headscale) setLastStateChangeToNow(namespace string) { now := time.Now().UTC() lastStateUpdate.WithLabelValues("", "headscale").Set(float64(now.Unix())) h.lastStateChange.Store(namespace, now) } func (h *Headscale) getLastStateChange(namespaces ...string) time.Time { times := []time.Time{} for _, namespace := range namespaces { if wrapped, ok := h.lastStateChange.Load(namespace); ok { lastChange, _ := wrapped.(time.Time) times = append(times, lastChange) } } sort.Slice(times, func(i, j int) bool { return times[i].After(times[j]) }) log.Trace().Msgf("Latest times %#v", times) if len(times) == 0 { return time.Now().UTC() } else { return times[0] } } func stdoutHandler(ctx *gin.Context) { body, _ := io.ReadAll(ctx.Request.Body) log.Trace(). Interface("header", ctx.Request.Header). Interface("proto", ctx.Request.Proto). Interface("url", ctx.Request.URL). Bytes("body", body). Msg("Request did not match") } func readOrCreatePrivateKey(path string) (*key.MachinePrivate, error) { privateKey, err := os.ReadFile(path) if errors.Is(err, os.ErrNotExist) { log.Info().Str("path", path).Msg("No private key file at path, creating...") machineKey := key.NewMachine() machineKeyStr, err := machineKey.MarshalText() if err != nil { return nil, fmt.Errorf( "failed to convert private key to string for saving: %w", err, ) } err = os.WriteFile(path, machineKeyStr, privateKeyFileMode) if err != nil { return nil, fmt.Errorf( "failed to save private key to disk: %w", err, ) } return &machineKey, nil } else if err != nil { return nil, fmt.Errorf("failed to read private key file: %w", err) } trimmedPrivateKey := strings.TrimSpace(string(privateKey)) privateKeyEnsurePrefix := PrivateKeyEnsurePrefix(trimmedPrivateKey) var machineKey key.MachinePrivate if err = machineKey.UnmarshalText([]byte(privateKeyEnsurePrefix)); err != nil { log.Info(). Str("path", path). Msg("This might be due to a legacy (headscale pre-0.12) private key. " + "If the key is in WireGuard format, delete the key and restart headscale. " + "A new key will automatically be generated. All Tailscale clients will have to be restarted") return nil, fmt.Errorf("failed to parse private key: %w", err) } return &machineKey, nil }