ntp: Add write_to_system service option

cmd/sing-box/cmd_tools_synctime.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"context"
+	"os"
+
+	"github.com/sagernet/sing-box/common/settings"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/log"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/ntp"
+
+	"github.com/spf13/cobra"
+)
+
+var (
+	commandSyncTimeFlagServer   string
+	commandSyncTimeOutputFormat string
+	commandSyncTimeWrite        bool
+)
+
+var commandSyncTime = &cobra.Command{
+	Use:   "synctime",
+	Short: "Sync time using the NTP protocol",
+	Args:  cobra.NoArgs,
+	Run: func(cmd *cobra.Command, args []string) {
+		err := syncTime()
+		if err != nil {
+			log.Fatal(err)
+		}
+	},
+}
+
+func init() {
+	commandSyncTime.Flags().StringVarP(&commandSyncTimeFlagServer, "server", "s", "time.apple.com", "Set NTP server")
+	commandSyncTime.Flags().StringVarP(&commandSyncTimeOutputFormat, "format", "f", C.TimeLayout, "Set output format")
+	commandSyncTime.Flags().BoolVarP(&commandSyncTimeWrite, "write", "w", false, "Write time to system")
+	commandTools.AddCommand(commandSyncTime)
+}
+
+func syncTime() error {
+	instance, err := createPreStartedClient()
+	if err != nil {
+		return err
+	}
+	dialer, err := createDialer(instance, N.NetworkUDP, commandToolsFlagOutbound)
+	if err != nil {
+		return err
+	}
+	defer instance.Close()
+	serverAddress := M.ParseSocksaddr(commandSyncTimeFlagServer)
+	if serverAddress.Port == 0 {
+		serverAddress.Port = 123
+	}
+	response, err := ntp.Exchange(context.Background(), dialer, serverAddress)
+	if err != nil {
+		return err
+	}
+	if commandSyncTimeWrite {
+		err = settings.SetSystemTime(response.Time)
+		if err != nil {
+			return E.Cause(err, "write time to system")
+		}
+	}
+	os.Stdout.WriteString(response.Time.Local().Format(commandSyncTimeOutputFormat))
+	return nil
+}