Various improvements and bug fixes

- Watch more events for lease file changes
 - Improving network up detection by using bootstrap IPv6 along side
   IPv4 one.
 - Emitting log to notice user that ctrld is starting.
 - Using systemd wrapper to provide correct status.
 - Restoring DNS on stop on Windows.

cmd/ctrld/cli.go

@@ -429,6 +429,7 @@ func initCLI() {
 				{s.Install, false},
 				{s.Start, true},
 			}
+			mainLog.Load().Notice().Msg("Starting service")
 			if doTasks(tasks) {
 				if err := p.router.Install(sc); err != nil {
 					mainLog.Load().Warn().Err(err).Msg("post installation failed, please check system/service log for details error")
@@ -450,12 +451,7 @@ func initCLI() {
 					uninstall(p, s)
 					os.Exit(1)
 				}
-				// On Linux, Darwin, Freebsd, ctrld set DNS on startup, because the DNS setting could be
-				// reset after rebooting. On windows, we only need to set once here. See prog.preRun in
-				// prog_*.go file for dedicated code on each platform. (1)
-				if runtime.GOOS == "windows" {
-					p.setDNS()
-				}
+				p.setDNS()
 			}
 		},
 	}
@@ -524,10 +520,7 @@ func initCLI() {
 			initLogging()
 			if doTasks([]task{{s.Stop, true}}) {
 				p.router.Cleanup()
-				// See comment (1) in startCmd.
-				if runtime.GOOS != "windows" {
-					p.resetDNS()
-				}
+				p.resetDNS()
 				mainLog.Load().Notice().Msg("Service stopped")
 			}
 		},

cmd/ctrld/prog.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"net/url"
 	"os"
+	"runtime"
 	"strconv"
 	"sync"
 	"syscall"
@@ -63,6 +64,19 @@ func (p *prog) Start(s service.Service) error {
 	return nil
 }
 
+func (p *prog) preRun() {
+	if !service.Interactive() {
+		p.setDNS()
+	}
+	if runtime.GOOS == "darwin" {
+		p.onStopped = append(p.onStopped, func() {
+			if !service.Interactive() {
+				p.resetDNS()
+			}
+		})
+	}
+}
+
 func (p *prog) run() {
 	// Wait the caller to signal that we can do our logic.
 	<-p.waitCh

cmd/ctrld/prog_darwin.go

@@ -4,17 +4,6 @@ import (
 	"github.com/kardianos/service"
 )
 
-func (p *prog) preRun() {
-	if !service.Interactive() {
-		p.setDNS()
-	}
-	p.onStopped = append(p.onStopped, func() {
-		if !service.Interactive() {
-			p.resetDNS()
-		}
-	})
-}
-
 func setDependencies(svc *service.Config) {}
 
 func setWorkingDirectory(svc *service.Config, dir string) {

cmd/ctrld/prog_freebsd.go

@@ -6,12 +6,6 @@ import (
 	"github.com/kardianos/service"
 )
 
-func (p *prog) preRun() {
-	if !service.Interactive() {
-		p.setDNS()
-	}
-}
-
 func setDependencies(svc *service.Config) {
 	// TODO(cuonglm): remove once https://github.com/kardianos/service/issues/359 fixed.
 	_ = os.MkdirAll("/usr/local/etc/rc.d", 0755)

cmd/ctrld/prog_linux.go

@@ -13,12 +13,6 @@ func init() {
 	}
 }
 
-func (p *prog) preRun() {
-	if !service.Interactive() {
-		p.setDNS()
-	}
-}
-
 func setDependencies(svc *service.Config) {
 	svc.Dependencies = []string{
 		"Wants=network-online.target",

cmd/ctrld/prog_others.go

@@ -4,8 +4,6 @@ package main
 
 import "github.com/kardianos/service"
 
-func (p *prog) preRun() {}
-
 func setDependencies(svc *service.Config) {}
 
 func setWorkingDirectory(svc *service.Config, dir string) {

cmd/ctrld/service.go

@@ -26,6 +26,8 @@ func newService(i service.Interface, c *service.Config) (service.Service, error)
 		return &sysV{s}, nil
 	case s.Platform() == "unix-systemv":
 		return &sysV{s}, nil
+	case s.Platform() == "linux-systemd":
+		return &systemd{s}, nil
 	}
 	return s, nil
 }
@@ -105,6 +107,20 @@ func (s *procd) Status() (service.Status, error) {
 	return service.StatusRunning, nil
 }
 
+// procd wraps a service.Service, and provide status command to
+// report the status correctly.
+type systemd struct {
+	service.Service
+}
+
+func (s *systemd) Status() (service.Status, error) {
+	out, _ := exec.Command("systemctl", "status", "ctrld").CombinedOutput()
+	if bytes.Contains(out, []byte("/FAILURE)")) {
+		return service.StatusStopped, nil
+	}
+	return s.Service.Status()
+}
+
 type task struct {
 	f            func() error
 	abortOnError bool

internal/clientinfo/dhcp.go

@@ -53,7 +53,7 @@ func (d *dhcp) watchChanges() {
 			if !ok {
 				return
 			}
-			if event.Has(fsnotify.Write) {
+			if event.Has(fsnotify.Write) || event.Has(fsnotify.Rename) || event.Has(fsnotify.Chmod) || event.Has(fsnotify.Remove) {
 				format := clientInfoFiles[event.Name]
 				if err := d.readLeaseFile(event.Name, format); err != nil && !os.IsNotExist(err) {
 					ctrld.ProxyLogger.Load().Err(err).Str("file", event.Name).Msg("leases file changed but failed to update client info")

internal/net/net.go

@@ -4,8 +4,11 @@ import (
 	"context"
 	"errors"
 	"net"
+	"os"
+	"os/signal"
 	"sync"
 	"sync/atomic"
+	"syscall"
 	"time"
 
 	"tailscale.com/logtail/backoff"
@@ -13,17 +16,17 @@ import (
 
 const (
 	controldIPv6Test = "ipv6.controld.io"
-	bootstrapDNS     = "76.76.2.0:53"
+	v4BootstrapDNS   = "76.76.2.0:53"
+	v6BootstrapDNS   = "[2606:1a40::]:53"
 )
 
 var Dialer = &net.Dialer{
 	Resolver: &net.Resolver{
 		PreferGo: true,
 		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
-			d := net.Dialer{
-				Timeout: 10 * time.Second,
-			}
-			return d.DialContext(ctx, "udp", bootstrapDNS)
+			d := ParallelDialer{}
+			d.Timeout = 10 * time.Second
+			return d.DialContext(ctx, "udp", []string{v4BootstrapDNS, v6BootstrapDNS})
 		},
 	},
 }
@@ -59,14 +62,32 @@ func supportListenIPv6Local() bool {
 }
 
 func probeStack() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go func() {
+		sigs := make(chan os.Signal, 1)
+		signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+		<-sigs
+		cancel()
+	}()
+
 	b := backoff.NewBackoff("probeStack", func(format string, args ...any) {}, 5*time.Second)
 	for {
-		if _, err := probeStackDialer.Dial("udp", bootstrapDNS); err == nil {
+		if _, err := probeStackDialer.DialContext(ctx, "udp", v4BootstrapDNS); err == nil {
 			hasNetworkUp = true
 			break
-		} else {
-			b.BackOff(context.Background(), err)
 		}
+		if _, err := probeStackDialer.DialContext(ctx, "udp", v6BootstrapDNS); err == nil {
+			hasNetworkUp = true
+			break
+		}
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+		b.BackOff(context.Background(), errors.New("network is down"))
 	}
 	canListenIPv6Local = supportListenIPv6Local()
 }