Add D-Bus API for configuring NTP servers of systemd-timesyncd

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	os_time "github.com/home-assistant/os-agent/time"
 	"time"
 
 	"github.com/coreos/go-systemd/v22/daemon"
@@ -70,6 +71,7 @@ func main() {
 	apparmor.InitializeDBus(conn)
 	cgroup.InitializeDBus(conn)
 	boards.InitializeDBus(conn, board)
+	os_time.InitializeDBus(conn)
 
 	_, err = daemon.SdNotify(false, daemon.SdNotifyReady)
 	if err != nil {

time/timesyncd.go

@@ -0,0 +1,175 @@
+package time
+
+import (
+	"fmt"
+	"github.com/godbus/dbus/v5"
+	"github.com/godbus/dbus/v5/introspect"
+	"github.com/godbus/dbus/v5/prop"
+	"github.com/home-assistant/os-agent/utils/lineinfile"
+	"regexp"
+	"strings"
+
+	logging "github.com/home-assistant/os-agent/utils/log"
+)
+
+const (
+	objectPath    = "/io/hass/os/Time/Timesyncd"
+	ifaceName     = "io.hass.os.Time.Timesyncd"
+	timesyncdConf = "/etc/systemd/timesyncd.conf"
+)
+
+var (
+	optNTPServer         []string
+	optFallbackNTPServer []string
+	configFile           = lineinfile.LineInFile{FilePath: timesyncdConf}
+)
+
+type timesyncd struct {
+	conn  *dbus.Conn
+	props *prop.Properties
+}
+
+func getNTPServers() []string {
+	return getTimesyncdConfigProperty("NTP")
+}
+
+func getFallbackNTPServers() []string {
+	return getTimesyncdConfigProperty("FallbackNTP")
+}
+
+func setNTPServer(c *prop.Change) *dbus.Error {
+	servers, ok := c.Value.([]string)
+	if !ok {
+		return dbus.MakeFailedError(fmt.Errorf("invalid type for NTPServer"))
+	}
+
+	value := strings.Join(servers, " ")
+
+	if err := setTimesyncdConfigProperty("NTP", value); err != nil {
+		return dbus.MakeFailedError(err)
+	}
+
+	optNTPServer = servers
+	return nil
+}
+
+func setFallbackNTPServer(c *prop.Change) *dbus.Error {
+	servers, ok := c.Value.([]string)
+	if !ok {
+		return dbus.MakeFailedError(fmt.Errorf("invalid type for FallbackNTPServer"))
+	}
+
+	value := strings.Join(servers, " ")
+
+	if err := setTimesyncdConfigProperty("FallbackNTP", value); err != nil {
+		return dbus.MakeFailedError(err)
+	}
+
+	optFallbackNTPServer = servers
+	return nil
+}
+
+func getTimesyncdConfigProperty(property string) []string {
+	value, err := configFile.Find(`^\s*(`+property+`=).*$`, `\[Time\]`, true)
+
+	var servers []string
+
+	if err != nil || value == nil {
+		return servers
+	}
+
+	matches := regexp.MustCompile(property + `=([^\s#]+(?:\s+[^\s#]+)*)`).FindStringSubmatch(*value)
+	if len(matches) > 1 {
+		servers = strings.Split(matches[1], " ")
+	}
+
+	return servers
+}
+
+func setTimesyncdConfigProperty(property string, value string) error {
+	var params = lineinfile.NewPresentParams("NTP=" + value)
+	params.Regexp, _ = regexp.Compile(`^\s*#?\s*(` + property + `=).*$`)
+	// Keep it simple, timesyncd.conf only has the [Time] section
+	params.After = `\[Time\]`
+	if err := configFile.Present(params); err != nil {
+		return fmt.Errorf("failed to set %s: %w", property, err)
+	}
+
+	if err := restartTimesyncd(); err != nil {
+		return fmt.Errorf("failed to restart timesyncd: %w", err)
+	}
+
+	return nil
+}
+
+func restartTimesyncd() error {
+	conn, err := dbus.SystemBus()
+	if err != nil {
+		return err
+	}
+
+	obj := conn.Object("org.freedesktop.systemd1", "/org/freedesktop/systemd1")
+	call := obj.Call("org.freedesktop.systemd1.Manager.RestartUnit", 0, "systemd-timesyncd.service", "replace")
+	if call.Err != nil {
+		return call.Err
+	}
+
+	return nil
+}
+
+func InitializeDBus(conn *dbus.Conn) {
+	d := timesyncd{
+		conn: conn,
+	}
+
+	optNTPServer = getNTPServers()
+	optFallbackNTPServer = getFallbackNTPServers()
+
+	propsSpec := map[string]map[string]*prop.Prop{
+		ifaceName: {
+			"NTPServer": {
+				Value:    optNTPServer,
+				Writable: true,
+				Emit:     prop.EmitTrue,
+				Callback: setNTPServer,
+			},
+			"FallbackNTPServer": {
+				Value:    optFallbackNTPServer,
+				Writable: true,
+				Emit:     prop.EmitTrue,
+				Callback: setFallbackNTPServer,
+			},
+		},
+	}
+
+	props, err := prop.Export(conn, objectPath, propsSpec)
+	if err != nil {
+		logging.Critical.Panic(err)
+	}
+	d.props = props
+
+	err = conn.Export(d, objectPath, ifaceName)
+	if err != nil {
+		logging.Critical.Panic(err)
+	}
+
+	node := &introspect.Node{
+		Name: objectPath,
+		Interfaces: []introspect.Interface{
+			introspect.IntrospectData,
+			prop.IntrospectData,
+			{
+				Name:       ifaceName,
+				Methods:    introspect.Methods(d),
+				Properties: props.Introspection(ifaceName),
+			},
+		},
+	}
+
+	err = conn.Export(introspect.NewIntrospectable(node), objectPath, "org.freedesktop.DBus.Introspectable")
+	if err != nil {
+		logging.Critical.Panic(err)
+	}
+
+	logging.Info.Printf("Exposing object %s with interface %s ...", objectPath, ifaceName)
+}