feat: ntp service

ntp/service.go

@@ -0,0 +1,84 @@
+package ntp
+
+import (
+	"context"
+	"github.com/Dreamacro/clash/log"
+	"github.com/beevik/ntp"
+	"sync"
+	"time"
+)
+
+var offset time.Duration
+var service *Service
+
+type Service struct {
+	addr     string
+	interval time.Duration
+	ticker   *time.Ticker
+	ctx      context.Context
+	cancel   context.CancelFunc
+	mu       *sync.Mutex
+	running  bool
+}
+
+func ReCreateNTPService(addr string, interval time.Duration) {
+	if service != nil {
+		service.Stop()
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	service = &Service{addr: addr, interval: interval, ctx: ctx, cancel: cancel, mu: &sync.Mutex{}}
+	service.Start()
+}
+
+func (srv *Service) Start() {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	log.Infoln("NTP service start")
+	srv.ticker = time.NewTicker(srv.interval * time.Minute)
+	service.running = true
+	go func() {
+		for {
+			err := srv.updateTime(srv.addr)
+			if err != nil {
+				log.Warnln("updateTime failed:", err)
+			}
+			select {
+			case <-srv.ticker.C:
+			case <-srv.ctx.Done():
+				return
+			}
+		}
+	}()
+}
+
+func (srv *Service) Stop() {
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	srv.ticker.Stop()
+	srv.cancel()
+	service.running = false
+}
+
+func (srv *Service) updateTime(addr string) error {
+	response, err := ntp.Query(addr)
+	if err != nil {
+		return err
+	}
+	localTime := time.Now()
+	ntpTime := response.Time
+	offset = localTime.Sub(ntpTime)
+	if offset > time.Duration(0) {
+		log.Warnln("System clock is ahead of NTP time by", offset)
+	} else if offset < time.Duration(0) {
+		log.Warnln("System clock is behind NTP time by", -offset)
+	}
+	return nil
+}
+
+func Now() time.Time {
+	now := time.Now()
+	if service.running && offset.Abs() > 0 {
+		now = now.Add(offset)
+	}
+	return now
+}