package server import ( "context" "fmt" "os" "os/exec" "runtime" "strconv" "sync" "time" "github.com/cenkalti/backoff/v4" "golang.org/x/exp/maps" "google.golang.org/protobuf/types/known/durationpb" log "github.com/sirupsen/logrus" "google.golang.org/grpc/codes" "google.golang.org/grpc/metadata" gstatus "google.golang.org/grpc/status" "google.golang.org/protobuf/types/known/timestamppb" "github.com/netbirdio/netbird/client/internal/auth" "github.com/netbirdio/netbird/client/system" "github.com/netbirdio/netbird/client/internal" "github.com/netbirdio/netbird/client/internal/peer" "github.com/netbirdio/netbird/client/proto" "github.com/netbirdio/netbird/version" ) const ( probeThreshold = time.Second * 5 retryInitialIntervalVar = "NB_CONN_RETRY_INTERVAL_TIME" maxRetryIntervalVar = "NB_CONN_MAX_RETRY_INTERVAL_TIME" maxRetryTimeVar = "NB_CONN_MAX_RETRY_TIME_TIME" retryMultiplierVar = "NB_CONN_RETRY_MULTIPLIER" defaultInitialRetryTime = 30 * time.Minute defaultMaxRetryInterval = 60 * time.Minute defaultMaxRetryTime = 14 * 24 * time.Hour defaultRetryMultiplier = 1.7 ) // Server for service control. type Server struct { rootCtx context.Context actCancel context.CancelFunc latestConfigInput internal.ConfigInput logFile string oauthAuthFlow oauthAuthFlow mutex sync.Mutex config *internal.Config proto.UnimplementedDaemonServiceServer connectClient *internal.ConnectClient statusRecorder *peer.Status sessionWatcher *internal.SessionWatcher mgmProbe *internal.Probe signalProbe *internal.Probe relayProbe *internal.Probe wgProbe *internal.Probe lastProbe time.Time } type oauthAuthFlow struct { expiresAt time.Time flow auth.OAuthFlow info auth.AuthFlowInfo waitCancel context.CancelFunc } // New server instance constructor. func New(ctx context.Context, configPath, logFile string) *Server { return &Server{ rootCtx: ctx, latestConfigInput: internal.ConfigInput{ ConfigPath: configPath, }, logFile: logFile, mgmProbe: internal.NewProbe(), signalProbe: internal.NewProbe(), relayProbe: internal.NewProbe(), wgProbe: internal.NewProbe(), } } func (s *Server) Start() error { s.mutex.Lock() defer s.mutex.Unlock() state := internal.CtxGetState(s.rootCtx) // if current state contains any error, return it // in all other cases we can continue execution only if status is idle and up command was // not in the progress or already successfully established connection. status, err := state.Status() if err != nil { return err } if status != internal.StatusIdle { return nil } ctx, cancel := context.WithCancel(s.rootCtx) s.actCancel = cancel // if configuration exists, we just start connections. if is new config we skip and set status NeedsLogin // on failure we return error to retry config, err := internal.UpdateConfig(s.latestConfigInput) if errorStatus, ok := gstatus.FromError(err); ok && errorStatus.Code() == codes.NotFound { s.config, err = internal.UpdateOrCreateConfig(s.latestConfigInput) if err != nil { log.Warnf("unable to create configuration file: %v", err) return err } state.Set(internal.StatusNeedsLogin) return nil } else if err != nil { log.Warnf("unable to create configuration file: %v", err) return err } // if configuration exists, we just start connections. config, _ = internal.UpdateOldManagementURL(ctx, config, s.latestConfigInput.ConfigPath) s.config = config if s.statusRecorder == nil { s.statusRecorder = peer.NewRecorder(config.ManagementURL.String()) } s.statusRecorder.UpdateManagementAddress(config.ManagementURL.String()) s.statusRecorder.UpdateRosenpass(config.RosenpassEnabled, config.RosenpassPermissive) if s.sessionWatcher == nil { s.sessionWatcher = internal.NewSessionWatcher(s.rootCtx, s.statusRecorder) s.sessionWatcher.SetOnExpireListener(s.onSessionExpire) } if !config.DisableAutoConnect { go s.connectWithRetryRuns(ctx, config, s.statusRecorder, s.mgmProbe, s.signalProbe, s.relayProbe, s.wgProbe) } return nil } // connectWithRetryRuns runs the client connection with a backoff strategy where we retry the operation as additional // mechanism to keep the client connected even when the connection is lost. // we cancel retry if the client receive a stop or down command, or if disable auto connect is configured. func (s *Server) connectWithRetryRuns(ctx context.Context, config *internal.Config, statusRecorder *peer.Status, mgmProbe *internal.Probe, signalProbe *internal.Probe, relayProbe *internal.Probe, wgProbe *internal.Probe, ) { backOff := getConnectWithBackoff(ctx) retryStarted := false go func() { t := time.NewTicker(24 * time.Hour) for { select { case <-ctx.Done(): t.Stop() return case <-t.C: if retryStarted { mgmtState := statusRecorder.GetManagementState() signalState := statusRecorder.GetSignalState() if mgmtState.Connected && signalState.Connected { log.Tracef("resetting status") retryStarted = false } else { log.Tracef("not resetting status: mgmt: %v, signal: %v", mgmtState.Connected, signalState.Connected) } } } } }() runOperation := func() error { log.Tracef("running client connection") s.connectClient = internal.NewConnectClient(ctx, config, statusRecorder) err := s.connectClient.RunWithProbes(mgmProbe, signalProbe, relayProbe, wgProbe) if err != nil { log.Debugf("run client connection exited with error: %v. Will retry in the background", err) } if config.DisableAutoConnect { return backoff.Permanent(err) } if !retryStarted { retryStarted = true backOff.Reset() } log.Tracef("client connection exited") return fmt.Errorf("client connection exited") } err := backoff.Retry(runOperation, backOff) if s, ok := gstatus.FromError(err); ok && s.Code() != codes.Canceled { log.Errorf("received an error when trying to connect: %v", err) } else { log.Tracef("retry canceled") } } // getConnectWithBackoff returns a backoff with exponential backoff strategy for connection retries func getConnectWithBackoff(ctx context.Context) backoff.BackOff { initialInterval := parseEnvDuration(retryInitialIntervalVar, defaultInitialRetryTime) maxInterval := parseEnvDuration(maxRetryIntervalVar, defaultMaxRetryInterval) maxElapsedTime := parseEnvDuration(maxRetryTimeVar, defaultMaxRetryTime) multiplier := defaultRetryMultiplier if envValue := os.Getenv(retryMultiplierVar); envValue != "" { // parse the multiplier from the environment variable string value to float64 value, err := strconv.ParseFloat(envValue, 64) if err != nil { log.Warnf("unable to parse environment variable %s: %s. using default: %f", retryMultiplierVar, envValue, multiplier) } else { multiplier = value } } return backoff.WithContext(&backoff.ExponentialBackOff{ InitialInterval: initialInterval, RandomizationFactor: 1, Multiplier: multiplier, MaxInterval: maxInterval, MaxElapsedTime: maxElapsedTime, // 14 days Stop: backoff.Stop, Clock: backoff.SystemClock, }, ctx) } // parseEnvDuration parses the environment variable and returns the duration func parseEnvDuration(envVar string, defaultDuration time.Duration) time.Duration { if envValue := os.Getenv(envVar); envValue != "" { if duration, err := time.ParseDuration(envValue); err == nil { return duration } log.Warnf("unable to parse environment variable %s: %s. using default: %s", envVar, envValue, defaultDuration) } return defaultDuration } // loginAttempt attempts to login using the provided information. it returns a status in case something fails func (s *Server) loginAttempt(ctx context.Context, setupKey, jwtToken string) (internal.StatusType, error) { var status internal.StatusType err := internal.Login(ctx, s.config, setupKey, jwtToken) if err != nil { if s, ok := gstatus.FromError(err); ok && (s.Code() == codes.InvalidArgument || s.Code() == codes.PermissionDenied) { log.Warnf("failed login: %v", err) status = internal.StatusNeedsLogin } else { log.Errorf("failed login: %v", err) status = internal.StatusLoginFailed } return status, err } return "", nil } // Login uses setup key to prepare configuration for the daemon. func (s *Server) Login(callerCtx context.Context, msg *proto.LoginRequest) (*proto.LoginResponse, error) { s.mutex.Lock() if s.actCancel != nil { s.actCancel() } ctx, cancel := context.WithCancel(s.rootCtx) md, ok := metadata.FromIncomingContext(callerCtx) if ok { ctx = metadata.NewOutgoingContext(ctx, md) } s.actCancel = cancel s.mutex.Unlock() state := internal.CtxGetState(ctx) defer func() { status, err := state.Status() if err != nil || (status != internal.StatusNeedsLogin && status != internal.StatusLoginFailed) { state.Set(internal.StatusIdle) } }() s.mutex.Lock() inputConfig := s.latestConfigInput if msg.ManagementUrl != "" { inputConfig.ManagementURL = msg.ManagementUrl s.latestConfigInput.ManagementURL = msg.ManagementUrl } if msg.AdminURL != "" { inputConfig.AdminURL = msg.AdminURL s.latestConfigInput.AdminURL = msg.AdminURL } if msg.CleanNATExternalIPs { inputConfig.NATExternalIPs = make([]string, 0) s.latestConfigInput.NATExternalIPs = nil } else if msg.NatExternalIPs != nil { inputConfig.NATExternalIPs = msg.NatExternalIPs s.latestConfigInput.NATExternalIPs = msg.NatExternalIPs } inputConfig.CustomDNSAddress = msg.CustomDNSAddress s.latestConfigInput.CustomDNSAddress = msg.CustomDNSAddress if string(msg.CustomDNSAddress) == "empty" { inputConfig.CustomDNSAddress = []byte{} s.latestConfigInput.CustomDNSAddress = []byte{} } if msg.Hostname != "" { // nolint ctx = context.WithValue(ctx, system.DeviceNameCtxKey, msg.Hostname) } if msg.RosenpassEnabled != nil { inputConfig.RosenpassEnabled = msg.RosenpassEnabled s.latestConfigInput.RosenpassEnabled = msg.RosenpassEnabled } if msg.RosenpassPermissive != nil { inputConfig.RosenpassPermissive = msg.RosenpassPermissive s.latestConfigInput.RosenpassPermissive = msg.RosenpassPermissive } if msg.ServerSSHAllowed != nil { inputConfig.ServerSSHAllowed = msg.ServerSSHAllowed s.latestConfigInput.ServerSSHAllowed = msg.ServerSSHAllowed } if msg.DisableAutoConnect != nil { inputConfig.DisableAutoConnect = msg.DisableAutoConnect s.latestConfigInput.DisableAutoConnect = msg.DisableAutoConnect } if msg.InterfaceName != nil { inputConfig.InterfaceName = msg.InterfaceName s.latestConfigInput.InterfaceName = msg.InterfaceName } if msg.WireguardPort != nil { port := int(*msg.WireguardPort) inputConfig.WireguardPort = &port s.latestConfigInput.WireguardPort = &port } if msg.NetworkMonitor != nil { inputConfig.NetworkMonitor = msg.NetworkMonitor s.latestConfigInput.NetworkMonitor = msg.NetworkMonitor } if len(msg.ExtraIFaceBlacklist) > 0 { inputConfig.ExtraIFaceBlackList = msg.ExtraIFaceBlacklist s.latestConfigInput.ExtraIFaceBlackList = msg.ExtraIFaceBlacklist } if msg.DnsRouteInterval != nil { duration := msg.DnsRouteInterval.AsDuration() inputConfig.DNSRouteInterval = &duration s.latestConfigInput.DNSRouteInterval = &duration } s.mutex.Unlock() if msg.OptionalPreSharedKey != nil { inputConfig.PreSharedKey = msg.OptionalPreSharedKey } config, err := internal.UpdateOrCreateConfig(inputConfig) if err != nil { return nil, err } if msg.ManagementUrl == "" { config, _ = internal.UpdateOldManagementURL(ctx, config, s.latestConfigInput.ConfigPath) s.config = config s.latestConfigInput.ManagementURL = config.ManagementURL.String() } s.mutex.Lock() s.config = config s.mutex.Unlock() if _, err := s.loginAttempt(ctx, "", ""); err == nil { state.Set(internal.StatusIdle) return &proto.LoginResponse{}, nil } state.Set(internal.StatusConnecting) if msg.SetupKey == "" { oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.IsLinuxDesktopClient) if err != nil { state.Set(internal.StatusLoginFailed) return nil, err } if s.oauthAuthFlow.flow != nil && s.oauthAuthFlow.flow.GetClientID(ctx) == oAuthFlow.GetClientID(context.TODO()) { if s.oauthAuthFlow.expiresAt.After(time.Now().Add(90 * time.Second)) { log.Debugf("using previous oauth flow info") return &proto.LoginResponse{ NeedsSSOLogin: true, VerificationURI: s.oauthAuthFlow.info.VerificationURI, VerificationURIComplete: s.oauthAuthFlow.info.VerificationURIComplete, UserCode: s.oauthAuthFlow.info.UserCode, }, nil } else { log.Warnf("canceling previous waiting execution") if s.oauthAuthFlow.waitCancel != nil { s.oauthAuthFlow.waitCancel() } } } authInfo, err := oAuthFlow.RequestAuthInfo(context.TODO()) if err != nil { log.Errorf("getting a request OAuth flow failed: %v", err) return nil, err } s.mutex.Lock() s.oauthAuthFlow.flow = oAuthFlow s.oauthAuthFlow.info = authInfo s.oauthAuthFlow.expiresAt = time.Now().Add(time.Duration(authInfo.ExpiresIn) * time.Second) s.mutex.Unlock() state.Set(internal.StatusNeedsLogin) return &proto.LoginResponse{ NeedsSSOLogin: true, VerificationURI: authInfo.VerificationURI, VerificationURIComplete: authInfo.VerificationURIComplete, UserCode: authInfo.UserCode, }, nil } if loginStatus, err := s.loginAttempt(ctx, msg.SetupKey, ""); err != nil { state.Set(loginStatus) return nil, err } return &proto.LoginResponse{}, nil } // WaitSSOLogin uses the userCode to validate the TokenInfo and // waits for the user to continue with the login on a browser func (s *Server) WaitSSOLogin(callerCtx context.Context, msg *proto.WaitSSOLoginRequest) (*proto.WaitSSOLoginResponse, error) { s.mutex.Lock() if s.actCancel != nil { s.actCancel() } ctx, cancel := context.WithCancel(s.rootCtx) md, ok := metadata.FromIncomingContext(callerCtx) if ok { ctx = metadata.NewOutgoingContext(ctx, md) } if msg.Hostname != "" { // nolint ctx = context.WithValue(ctx, system.DeviceNameCtxKey, msg.Hostname) } s.actCancel = cancel s.mutex.Unlock() if s.oauthAuthFlow.flow == nil { return nil, gstatus.Errorf(codes.Internal, "oauth flow is not initialized") } state := internal.CtxGetState(ctx) defer func() { s, err := state.Status() if err != nil || (s != internal.StatusNeedsLogin && s != internal.StatusLoginFailed) { state.Set(internal.StatusIdle) } }() state.Set(internal.StatusConnecting) s.mutex.Lock() flowInfo := s.oauthAuthFlow.info s.mutex.Unlock() if flowInfo.UserCode != msg.UserCode { state.Set(internal.StatusLoginFailed) return nil, gstatus.Errorf(codes.InvalidArgument, "sso user code is invalid") } if s.oauthAuthFlow.waitCancel != nil { s.oauthAuthFlow.waitCancel() } waitTimeout := time.Until(s.oauthAuthFlow.expiresAt) waitCTX, cancel := context.WithTimeout(ctx, waitTimeout) defer cancel() s.mutex.Lock() s.oauthAuthFlow.waitCancel = cancel s.mutex.Unlock() tokenInfo, err := s.oauthAuthFlow.flow.WaitToken(waitCTX, flowInfo) if err != nil { if err == context.Canceled { return nil, nil //nolint:nilnil } s.mutex.Lock() s.oauthAuthFlow.expiresAt = time.Now() s.mutex.Unlock() state.Set(internal.StatusLoginFailed) log.Errorf("waiting for browser login failed: %v", err) return nil, err } s.mutex.Lock() s.oauthAuthFlow.expiresAt = time.Now() s.mutex.Unlock() if loginStatus, err := s.loginAttempt(ctx, "", tokenInfo.GetTokenToUse()); err != nil { state.Set(loginStatus) return nil, err } return &proto.WaitSSOLoginResponse{}, nil } // Up starts engine work in the daemon. func (s *Server) Up(callerCtx context.Context, _ *proto.UpRequest) (*proto.UpResponse, error) { s.mutex.Lock() defer s.mutex.Unlock() state := internal.CtxGetState(s.rootCtx) // if current state contains any error, return it // in all other cases we can continue execution only if status is idle and up command was // not in the progress or already successfully established connection. status, err := state.Status() if err != nil { return nil, err } if status != internal.StatusIdle { return nil, fmt.Errorf("up already in progress: current status %s", status) } // it should be nil here, but . if s.actCancel != nil { s.actCancel() } ctx, cancel := context.WithCancel(s.rootCtx) md, ok := metadata.FromIncomingContext(callerCtx) if ok { ctx = metadata.NewOutgoingContext(ctx, md) } s.actCancel = cancel if s.config == nil { return nil, fmt.Errorf("config is not defined, please call login command first") } if s.statusRecorder == nil { s.statusRecorder = peer.NewRecorder(s.config.ManagementURL.String()) } s.statusRecorder.UpdateManagementAddress(s.config.ManagementURL.String()) s.statusRecorder.UpdateRosenpass(s.config.RosenpassEnabled, s.config.RosenpassPermissive) go s.connectWithRetryRuns(ctx, s.config, s.statusRecorder, s.mgmProbe, s.signalProbe, s.relayProbe, s.wgProbe) return &proto.UpResponse{}, nil } // Down engine work in the daemon. func (s *Server) Down(ctx context.Context, _ *proto.DownRequest) (*proto.DownResponse, error) { s.mutex.Lock() defer s.mutex.Unlock() if s.actCancel == nil { return nil, fmt.Errorf("service is not up") } s.actCancel() state := internal.CtxGetState(s.rootCtx) state.Set(internal.StatusIdle) maxWaitTime := 5 * time.Second timeout := time.After(maxWaitTime) engine := s.connectClient.Engine() for { if !engine.IsWGIfaceUp() { return &proto.DownResponse{}, nil } select { case <-ctx.Done(): return &proto.DownResponse{}, nil case <-timeout: return nil, fmt.Errorf("failed to shut down properly") default: time.Sleep(100 * time.Millisecond) } } } // Status returns the daemon status func (s *Server) Status( _ context.Context, msg *proto.StatusRequest, ) (*proto.StatusResponse, error) { s.mutex.Lock() defer s.mutex.Unlock() status, err := internal.CtxGetState(s.rootCtx).Status() if err != nil { return nil, err } statusResponse := proto.StatusResponse{Status: string(status), DaemonVersion: version.NetbirdVersion()} if s.statusRecorder == nil { s.statusRecorder = peer.NewRecorder(s.config.ManagementURL.String()) } s.statusRecorder.UpdateManagementAddress(s.config.ManagementURL.String()) s.statusRecorder.UpdateRosenpass(s.config.RosenpassEnabled, s.config.RosenpassPermissive) if msg.GetFullPeerStatus { s.runProbes() fullStatus := s.statusRecorder.GetFullStatus() pbFullStatus := toProtoFullStatus(fullStatus) statusResponse.FullStatus = pbFullStatus } return &statusResponse, nil } func (s *Server) runProbes() { if time.Since(s.lastProbe) > probeThreshold { managementHealthy := s.mgmProbe.Probe() signalHealthy := s.signalProbe.Probe() relayHealthy := s.relayProbe.Probe() wgProbe := s.wgProbe.Probe() // Update last time only if all probes were successful if managementHealthy && signalHealthy && relayHealthy && wgProbe { s.lastProbe = time.Now() } } } // GetConfig of the daemon. func (s *Server) GetConfig(_ context.Context, _ *proto.GetConfigRequest) (*proto.GetConfigResponse, error) { s.mutex.Lock() defer s.mutex.Unlock() managementURL := s.latestConfigInput.ManagementURL adminURL := s.latestConfigInput.AdminURL preSharedKey := "" if s.config != nil { if managementURL == "" && s.config.ManagementURL != nil { managementURL = s.config.ManagementURL.String() } if s.config.AdminURL != nil { adminURL = s.config.AdminURL.String() } preSharedKey = s.config.PreSharedKey if preSharedKey != "" { preSharedKey = "**********" } } return &proto.GetConfigResponse{ ManagementUrl: managementURL, ConfigFile: s.latestConfigInput.ConfigPath, LogFile: s.logFile, PreSharedKey: preSharedKey, AdminURL: adminURL, InterfaceName: s.config.WgIface, WireguardPort: int64(s.config.WgPort), DisableAutoConnect: s.config.DisableAutoConnect, ServerSSHAllowed: *s.config.ServerSSHAllowed, RosenpassEnabled: s.config.RosenpassEnabled, RosenpassPermissive: s.config.RosenpassPermissive, }, nil } func (s *Server) onSessionExpire() { if runtime.GOOS != "windows" { isUIActive := internal.CheckUIApp() if !isUIActive { if err := sendTerminalNotification(); err != nil { log.Errorf("send session expire terminal notification: %v", err) } } } } func toProtoFullStatus(fullStatus peer.FullStatus) *proto.FullStatus { pbFullStatus := proto.FullStatus{ ManagementState: &proto.ManagementState{}, SignalState: &proto.SignalState{}, LocalPeerState: &proto.LocalPeerState{}, Peers: []*proto.PeerState{}, } pbFullStatus.ManagementState.URL = fullStatus.ManagementState.URL pbFullStatus.ManagementState.Connected = fullStatus.ManagementState.Connected if err := fullStatus.ManagementState.Error; err != nil { pbFullStatus.ManagementState.Error = err.Error() } pbFullStatus.SignalState.URL = fullStatus.SignalState.URL pbFullStatus.SignalState.Connected = fullStatus.SignalState.Connected if err := fullStatus.SignalState.Error; err != nil { pbFullStatus.SignalState.Error = err.Error() } pbFullStatus.LocalPeerState.IP = fullStatus.LocalPeerState.IP pbFullStatus.LocalPeerState.PubKey = fullStatus.LocalPeerState.PubKey pbFullStatus.LocalPeerState.KernelInterface = fullStatus.LocalPeerState.KernelInterface pbFullStatus.LocalPeerState.Fqdn = fullStatus.LocalPeerState.FQDN pbFullStatus.LocalPeerState.RosenpassPermissive = fullStatus.RosenpassState.Permissive pbFullStatus.LocalPeerState.RosenpassEnabled = fullStatus.RosenpassState.Enabled pbFullStatus.LocalPeerState.Routes = maps.Keys(fullStatus.LocalPeerState.Routes) for _, peerState := range fullStatus.Peers { pbPeerState := &proto.PeerState{ IP: peerState.IP, PubKey: peerState.PubKey, ConnStatus: peerState.ConnStatus.String(), ConnStatusUpdate: timestamppb.New(peerState.ConnStatusUpdate), Relayed: peerState.Relayed, Direct: peerState.Direct, LocalIceCandidateType: peerState.LocalIceCandidateType, RemoteIceCandidateType: peerState.RemoteIceCandidateType, LocalIceCandidateEndpoint: peerState.LocalIceCandidateEndpoint, RemoteIceCandidateEndpoint: peerState.RemoteIceCandidateEndpoint, Fqdn: peerState.FQDN, LastWireguardHandshake: timestamppb.New(peerState.LastWireguardHandshake), BytesRx: peerState.BytesRx, BytesTx: peerState.BytesTx, RosenpassEnabled: peerState.RosenpassEnabled, Routes: maps.Keys(peerState.GetRoutes()), Latency: durationpb.New(peerState.Latency), } pbFullStatus.Peers = append(pbFullStatus.Peers, pbPeerState) } for _, relayState := range fullStatus.Relays { pbRelayState := &proto.RelayState{ URI: relayState.URI.String(), Available: relayState.Err == nil, } if err := relayState.Err; err != nil { pbRelayState.Error = err.Error() } pbFullStatus.Relays = append(pbFullStatus.Relays, pbRelayState) } for _, dnsState := range fullStatus.NSGroupStates { var err string if dnsState.Error != nil { err = dnsState.Error.Error() } pbDnsState := &proto.NSGroupState{ Servers: dnsState.Servers, Domains: dnsState.Domains, Enabled: dnsState.Enabled, Error: err, } pbFullStatus.DnsServers = append(pbFullStatus.DnsServers, pbDnsState) } return &pbFullStatus } // sendTerminalNotification sends a terminal notification message // to inform the user that the NetBird connection session has expired. func sendTerminalNotification() error { message := "NetBird connection session expired\n\nPlease re-authenticate to connect to the network." echoCmd := exec.Command("echo", message) wallCmd := exec.Command("sudo", "wall") echoCmdStdout, err := echoCmd.StdoutPipe() if err != nil { return err } wallCmd.Stdin = echoCmdStdout if err := echoCmd.Start(); err != nil { return err } if err := wallCmd.Start(); err != nil { return err } if err := echoCmd.Wait(); err != nil { return err } return wallCmd.Wait() }