all: make router setup/cleanup works more generally

cmd/ctrld/cli.go

@@ -275,22 +275,19 @@ func initCLI() {
 				if cp := router.CertPool(); cp != nil {
 					rootCertPool = cp
 				}
-				// Perform router setup/cleanup if ctrld could not be direct listener.
-				if !couldBeDirectListener(cfg.FirstListener()) {
-					p.onStarted = append(p.onStarted, func() {
-						mainLog.Debug().Msg("router setup")
-						if err := p.router.Setup(); err != nil {
-							mainLog.Error().Err(err).Msg("could not configure router")
-						}
-					})
-					p.onStopped = append(p.onStopped, func() {
-						mainLog.Debug().Msg("router cleanup")
-						if err := p.router.Cleanup(); err != nil {
-							mainLog.Error().Err(err).Msg("could not cleanup router")
-						}
-						p.resetDNS()
-					})
-				}
+				p.onStarted = append(p.onStarted, func() {
+					mainLog.Debug().Msg("router setup")
+					if err := p.router.Setup(); err != nil {
+						mainLog.Error().Err(err).Msg("could not configure router")
+					}
+				})
+				p.onStopped = append(p.onStopped, func() {
+					mainLog.Debug().Msg("router cleanup")
+					if err := p.router.Cleanup(); err != nil {
+						mainLog.Error().Err(err).Msg("could not cleanup router")
+					}
+					p.resetDNS()
+				})
 			}
 
 			close(waitCh)
@@ -404,7 +401,7 @@ func initCLI() {
 				return
 			}
 
-			if router.Name() != "" && !couldBeDirectListener(cfg.FirstListener()) {
+			if router.Name() != "" {
 				mainLog.Debug().Msg("cleaning up router before installing")
 				_ = p.router.Cleanup()
 			}
@@ -504,15 +501,18 @@ func initCLI() {
 		Short: "Stop the ctrld service",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			prog := &prog{}
-			s, err := newService(prog, svcConfig)
+			tryReadingConfig(false)
+			v.Unmarshal(&cfg)
+			p := &prog{router: router.New(&cfg)}
+			s, err := newService(p, svcConfig)
 			if err != nil {
 				mainLog.Error().Msg(err.Error())
 				return
 			}
 			initLogging()
 			if doTasks([]task{{s.Stop, true}}) {
-				prog.resetDNS()
+				p.router.Cleanup()
+				p.resetDNS()
 				mainLog.Notice().Msg("Service stopped")
 			}
 		},
@@ -591,7 +591,9 @@ func initCLI() {
 NOTE: Uninstalling will set DNS to values provided by DHCP.`,
 		Args: cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			p := &prog{}
+			tryReadingConfig(false)
+			v.Unmarshal(&cfg)
+			p := &prog{router: router.New(&cfg)}
 			s, err := newService(p, svcConfig)
 			if err != nil {
 				mainLog.Error().Msg(err.Error())
@@ -1157,19 +1159,20 @@ func uninstall(p *prog, s service.Service) {
 	}
 	initLogging()
 	if doTasks(tasks) {
-		r := router.New(&cfg)
-		if err := r.Uninstall(svcConfig); err != nil {
+		if err := p.router.ConfigureService(svcConfig); err != nil {
+			mainLog.Fatal().Err(err).Msg("could not configure service")
+		}
+		if err := p.router.Uninstall(svcConfig); err != nil {
 			mainLog.Warn().Err(err).Msg("post uninstallation failed, please check system/service log for details error")
 			return
 		}
-		// Stop already reset DNS on router.
-		if router.Name() == "" {
-			p.resetDNS()
+		p.resetDNS()
+		if router.Name() != "" {
+			mainLog.Debug().Msg("Router cleanup")
 		}
-		mainLog.Debug().Msg("Router cleanup")
 		// Stop already did router.Cleanup and report any error if happens,
 		// ignoring error here to prevent false positive.
-		_ = r.Cleanup()
+		_ = p.router.Cleanup()
 		mainLog.Notice().Msg("Service uninstalled")
 		return
 	}

cmd/ctrld/os_linux.go

@@ -147,7 +147,7 @@ func resetDNS(iface *net.Interface) (err error) {
 	if ctrldnet.IPv6Available(ctx) {
 		c := client6.NewClient()
 		conversation, err := c.Exchange(iface.Name)
-		if err != nil {
+		if err != nil && !errAddrInUse(err) {
 			mainLog.Debug().Err(err).Msg("could not exchange DHCPv6")
 		}
 		for _, packet := range conversation {

cmd/ctrld/prog.go

@@ -1,12 +1,14 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"math/rand"
 	"net"
 	"os"
 	"strconv"
 	"sync"
+	"syscall"
 
 	"github.com/kardianos/service"
 
@@ -216,7 +218,7 @@ func (p *prog) setDNS() {
 	logger.Debug().Msg("setting DNS for interface")
 	ns := lc.IP
 	switch {
-	case couldBeDirectListener(lc):
+	case lc.IsDirectDnsListener():
 		// If ctrld is direct listener, use 127.0.0.1 as nameserver.
 		ns = "127.0.0.1"
 	case lc.Port != 53:
@@ -294,3 +296,11 @@ func runLogServer(sockPath string) net.Conn {
 	}
 	return server
 }
+
+func errAddrInUse(err error) bool {
+	opErr, ok := err.(*net.OpError)
+	if !ok {
+		return false
+	}
+	return errors.Is(opErr.Err, syscall.EADDRINUSE)
+}

config.go

@@ -207,6 +207,24 @@ type ListenerConfig struct {
 	Policy     *ListenerPolicyConfig `mapstructure:"policy" toml:"policy,omitempty"`
 }
 
+// IsDirectDnsListener reports whether ctrld can be a direct listener on port 53.
+// It returns true only if ctrld can listen on port 53 for all interfaces. That means
+// there's no other software listening on port 53.
+//
+// If someone listening on port 53, or ctrld could only listen on port 53 for a specific
+// interface, ctrld could only be configured as a DNS forwarder.
+func (lc *ListenerConfig) IsDirectDnsListener() bool {
+	if lc == nil || lc.Port != 53 {
+		return false
+	}
+	switch lc.IP {
+	case "", "::", "0.0.0.0":
+		return true
+	default:
+		return false
+	}
+}
+
 // ListenerPolicyConfig specifies the policy rules for ctrld to filter incoming requests.
 type ListenerPolicyConfig struct {
 	Name                 string   `mapstructure:"name" toml:"name,omitempty"`

internal/router/ddwrt/ddwrt.go

@@ -58,6 +58,9 @@ func (d *Ddwrt) PreRun() error {
 }
 
 func (d *Ddwrt) Setup() error {
+	if d.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Already setup.
 	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
 		return nil
@@ -81,6 +84,9 @@ func (d *Ddwrt) Setup() error {
 }
 
 func (d *Ddwrt) Cleanup() error {
+	if d.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
 		nvramKvMap["dnsmasq_options"] = ""
 		// Restore old configs.

internal/router/edgeos/edgeos.go

@@ -62,6 +62,9 @@ func (e *EdgeOS) PreRun() error {
 }
 
 func (e *EdgeOS) Setup() error {
+	if e.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	if e.isUSG {
 		return e.setupUSG()
 	}
@@ -69,6 +72,9 @@ func (e *EdgeOS) Setup() error {
 }
 
 func (e *EdgeOS) Cleanup() error {
+	if e.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	if e.isUSG {
 		return e.cleanupUSG()
 	}

internal/router/firewalla/firewalla.go

@@ -54,6 +54,9 @@ func (f *Firewalla) PreRun() error {
 }
 
 func (f *Firewalla) Setup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	data, err := dnsmasq.FirewallaConfTmpl(dnsmasq.ConfigContentTmpl, f.cfg)
 	if err != nil {
 		return fmt.Errorf("generating dnsmasq config: %w", err)
@@ -71,6 +74,9 @@ func (f *Firewalla) Setup() error {
 }
 
 func (f *Firewalla) Cleanup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Removing current config.
 	if err := os.Remove(firewallaDNSMasqConfigPath); err != nil {
 		return fmt.Errorf("removing ctrld config: %w", err)

internal/router/merlin/merlin.go

@@ -49,6 +49,9 @@ func (m *Merlin) PreRun() error {
 }
 
 func (m *Merlin) Setup() error {
+	if m.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	buf, err := os.ReadFile(dnsmasq.MerlinPostConfPath)
 	// Already setup.
 	if bytes.Contains(buf, []byte(dnsmasq.MerlinPostConfMarker)) {
@@ -86,6 +89,9 @@ func (m *Merlin) Setup() error {
 }
 
 func (m *Merlin) Cleanup() error {
+	if m.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
 		// Restore old configs.
 		if err := nvram.Restore(nvramKvMap, nvram.CtrldSetupKey); err != nil {

internal/router/openwrt/openwrt.go

@@ -49,6 +49,9 @@ func (o *Openwrt) PreRun() error {
 }
 
 func (o *Openwrt) Setup() error {
+	if o.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, o.cfg)
 	if err != nil {
 		return err
@@ -68,6 +71,9 @@ func (o *Openwrt) Setup() error {
 }
 
 func (o *Openwrt) Cleanup() error {
+	if o.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Remove the custom dnsmasq config
 	if err := os.Remove(openwrtDNSMasqConfigPath); err != nil {
 		return err

internal/router/pfsense/pfsense.go

@@ -66,6 +66,9 @@ func (p *Pfsense) Install(config *service.Config) error {
 }
 
 func (p *Pfsense) Uninstall(config *service.Config) error {
+	if err := os.Remove(filepath.Join(rcPath, p.svcName+".sh")); err != nil {
+		return fmt.Errorf("os.Remove: %w", err)
+	}
 	return nil
 }
 
@@ -84,11 +87,10 @@ func (p *Pfsense) Setup() error {
 }
 
 func (p *Pfsense) Cleanup() error {
-	if err := os.Remove(filepath.Join(rcPath, p.svcName+".sh")); err != nil {
-		return fmt.Errorf("os.Remove: %w", err)
+	if p.cfg.FirstListener().IsDirectDnsListener() {
+		_ = exec.Command(unboundRcPath, "onerestart").Run()
+		_ = exec.Command(dnsmasqRcPath, "onerestart").Run()
 	}
-	_ = exec.Command(unboundRcPath, "onerestart").Run()
-	_ = exec.Command(dnsmasqRcPath, "onerestart").Run()
 
 	return nil
 }

internal/router/synology/synology.go

@@ -44,6 +44,9 @@ func (s *Synology) PreRun() error {
 }
 
 func (s *Synology) Setup() error {
+	if s.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, s.cfg)
 	if err != nil {
 		return err
@@ -61,6 +64,9 @@ func (s *Synology) Setup() error {
 }
 
 func (s *Synology) Cleanup() error {
+	if s.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Remove the custom config files.
 	for _, f := range []string{synologyDNSMasqConfigPath, synologyDhcpdInfoPath} {
 		if err := os.Remove(f); err != nil {

internal/router/tomato/tomato.go

@@ -53,6 +53,9 @@ func (f *FreshTomato) PreRun() error {
 }
 
 func (f *FreshTomato) Setup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Already setup.
 	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
 		return nil
@@ -83,6 +86,9 @@ func (f *FreshTomato) Setup() error {
 }
 
 func (f *FreshTomato) Cleanup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
 		nvramKvMap["dnsmasq_custom"] = ""
 		// Restore old configs.

internal/router/ubios/ubios.go

@@ -47,6 +47,9 @@ func (u *Ubios) PreRun() error {
 }
 
 func (u *Ubios) Setup() error {
+	if u.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, u.cfg)
 	if err != nil {
 		return err
@@ -62,6 +65,9 @@ func (u *Ubios) Setup() error {
 }
 
 func (u *Ubios) Cleanup() error {
+	if u.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
 	// Remove the custom dnsmasq config
 	if err := os.Remove(ubiosDNSMasqConfigPath); err != nil {
 		return err