all: implement router setup for openwrt

internal/router/openwrt.go

@@ -0,0 +1,74 @@
+package router
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+var errUCIEntryNotFound = errors.New("uci: Entry not found")
+
+const openwrtDNSMasqConfigPath = "/tmp/dnsmasq.d/ctrld.conf"
+const openwrtDNSMasqConfigContent = `# GENERATED BY ctrld - DO NOT MODIFY
+port=0
+`
+
+func setupOpenWrt() error {
+	// Delete dnsmasq port if set.
+	if _, err := uci("delete", "dhcp.@dnsmasq[0].port"); err != nil && !errors.Is(err, errUCIEntryNotFound) {
+		return err
+	}
+	// Disable dnsmasq as DNS server.
+	if err := os.WriteFile(openwrtDNSMasqConfigPath, []byte(openwrtDNSMasqConfigContent), 0600); err != nil {
+		return err
+	}
+	// Commit.
+	if _, err := uci("commit"); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func cleanupOpenWrt() error {
+	// Remove the custom dnsmasq config
+	if err := os.Remove(openwrtDNSMasqConfigPath); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func postInstallOpenWrt() error {
+	return exec.Command("/etc/init.d/ctrld", "enable").Run()
+}
+
+func uci(args ...string) (string, error) {
+	cmd := exec.Command("uci", args...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		if strings.HasPrefix(stderr.String(), errUCIEntryNotFound.Error()) {
+			return "", errUCIEntryNotFound
+		}
+		return "", fmt.Errorf("%s:%w", stderr.String(), err)
+	}
+	return strings.TrimSpace(stdout.String()), nil
+}
+
+func restartDNSMasq() error {
+	if out, err := exec.Command("/etc/init.d/dnsmasq", "restart").CombinedOutput(); err != nil {
+		return fmt.Errorf("%s: %w", string(out), err)
+	}
+	return nil
+}

internal/router/procd.go

@@ -0,0 +1,24 @@
+package router
+
+const openWrtScript = `#!/bin/sh /etc/rc.common
+USE_PROCD=1
+# After network starts
+START=21
+# Before network stops
+STOP=89
+cmd="{{.Path}}{{range .Arguments}} {{.|cmd}}{{end}}"
+name="{{.Name}}"
+pid_file="/var/run/${name}.pid"
+
+start_service() {
+    echo "Starting ${name}"
+    procd_open_instance
+    procd_set_param command ${cmd}
+    procd_set_param respawn             # respawn automatically if something died
+    procd_set_param stdout 1            # forward stdout of the command to logd
+    procd_set_param stderr 1            # same for stderr
+    procd_set_param pidfile ${pid_file} # write a pid file on instance start and remove it on stop
+    procd_close_instance
+    echo "${name} has been started"
+}
+`

internal/router/router.go

@@ -8,6 +8,8 @@ import (
 	"os/exec"
 	"sync/atomic"
 
+	"github.com/kardianos/service"
+
 	"github.com/Control-D-Inc/ctrld"
 )
 
@@ -21,7 +23,7 @@ const (
 // ErrNotSupported reports the current router is not supported error.
 var ErrNotSupported = errors.New("unsupported platform")
 
-var routerAtomic atomic.Pointer[router]
+var routerPlatform atomic.Pointer[router]
 
 type router struct {
 	name string
@@ -32,11 +34,13 @@ func SupportedPlatforms() []string {
 	return []string{DDWrt, Merlin, OpenWrt, Ubios}
 }
 
-// Configure change the given *ctrld.Config for running on the router.
+// Configure configures things for running ctrld on the router.
 func Configure(c *ctrld.Config) error {
 	name := Name()
 	switch name {
-	case DDWrt, Merlin, OpenWrt, Ubios:
+	case OpenWrt:
+		return setupOpenWrt()
+	case DDWrt, Merlin, Ubios:
 	default:
 		return ErrNotSupported
 	}
@@ -45,14 +49,57 @@ func Configure(c *ctrld.Config) error {
 	return nil
 }
 
+// ConfigureService performs necessary setup for running ctrld as a service on router.
+func ConfigureService(sc *service.Config) {
+	name := Name()
+	switch name {
+	case OpenWrt:
+		sc.Option["SysvScript"] = openWrtScript
+	case DDWrt, Merlin, Ubios:
+	}
+}
+
+// PostInstall performs task after installing ctrld on router.
+func PostInstall() error {
+	name := Name()
+	switch name {
+	case OpenWrt:
+		return postInstallOpenWrt()
+	case DDWrt, Merlin, Ubios:
+	}
+	return nil
+}
+
+// Cleanup cleans ctrld setup on the router.
+func Cleanup() error {
+	name := Name()
+	switch name {
+	case OpenWrt:
+		return cleanupOpenWrt()
+	case DDWrt, Merlin, Ubios:
+	}
+	return nil
+}
+
+// ListenAddress returns the listener address of ctrld on router.
+func ListenAddress() string {
+	name := Name()
+	switch name {
+	case OpenWrt:
+		return ":53"
+	case DDWrt, Merlin, Ubios:
+	}
+	return ""
+}
+
 // Name returns name of the router platform.
 func Name() string {
-	if r := routerAtomic.Load(); r != nil {
+	if r := routerPlatform.Load(); r != nil {
 		return r.name
 	}
 	r := &router{}
 	r.name = distroName()
-	routerAtomic.Store(r)
+	routerPlatform.Store(r)
 	return r.name
 }