Device/SERVER/Meter_Service/core/tcpserver/gontpd.go

package tcpserver

import (
	"encoding/binary"
	//	"flag"
	"fmt"
	"log"
	"net"
	"time"
)

const ntpEpochOffset = 2208988800

type packet struct {
	Settings       uint8
	Stratum        uint8
	Poll           int8
	Precision      int8
	RootDelay      uint32
	RootDispersion uint32
	ReferenceID    uint32
	RefTimeSec     uint32
	RefTimeFrac    uint32
	OrigTimeSec    uint32
	OrigTimeFrac   uint32
	RxTimeSec      uint32
	RxTimeFrac     uint32
	TxTimeSec      uint32
	TxTimeFrac     uint32
}

func GoNtpd() {
	//var host string
	//flag.StringVar(&host, "e", "ntp.api.bz", "NTP host") //"182.92.12.11:123"
	//flag.Parse()

	conn, err := net.Dial("udp", "ntp.api.bz:123") //host)
	if err != nil {
		log.Fatalf("failed to connect: %v", err)
	}
	defer conn.Close()
	if err := conn.SetDeadline(time.Now().Add(15 * time.Second)); err != nil {
		log.Fatalf("failed to set deadline: %v", err)
	}

	req := &packet{Settings: 0x1B}

	if err := binary.Write(conn, binary.BigEndian, req); err != nil {
		log.Fatalf("failed to send request: %v", err)
	}

	rsp := &packet{}
	if err := binary.Read(conn, binary.BigEndian, rsp); err != nil {
		log.Fatalf("failed to read server response: %v", err)
	}

	secs := float64(rsp.TxTimeSec) - ntpEpochOffset
	nanos := (int64(rsp.TxTimeFrac) * 1e9) >> 32

	showtime := time.Unix(int64(secs), nanos)
	fmt.Printf("%v\n", showtime)
	fmt.Println("now:", int64(secs))
}