// Copyright Fuzamei Corp. 2018 All Rights Reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package common import ( "encoding/binary" "errors" "fmt" "math" "net" "sort" "time" ) const ntpEpochOffset = 2208988800 //ErrNetWorkDealy error var ErrNetWorkDealy = errors.New("ErrNetWorkDealy") // NTP packet format (v3 with optional v4 fields removed) // // 0 1 2 3 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // |LI | VN |Mode | Stratum | Poll | Precision | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | Root Delay | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | Root Dispersion | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | Reference ID | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | | // + Reference Timestamp (64) + // | | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | | // + Origin Timestamp (64) + // | | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | | // + Receive Timestamp (64) + // | | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | | // + Transmit Timestamp (64) + // | | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // type packet struct { Settings uint8 // leap yr indicator, ver number, and mode Stratum uint8 // stratum of local clock Poll int8 // poll exponent Precision int8 // precision exponent RootDelay uint32 // root delay RootDispersion uint32 // root dispersion ReferenceID uint32 // reference id RefTimeSec uint32 // reference timestamp sec RefTimeFrac uint32 // reference timestamp fractional OrigTimeSec uint32 // origin time secs OrigTimeFrac uint32 // origin time fractional RxTimeSec uint32 // receive time secs RxTimeFrac uint32 // receive time frac TxTimeSec uint32 // transmit time secs TxTimeFrac uint32 // transmit time frac } /* t2 t3 t6 t7 --------------------------------------------------------- /\ \ /\ \ / \ / \ / \ / \ / \/ / \/ --------------------------------------------------------- t1 t4 t5 t8 */ //GetNtpTime 利用服务器返回的 t2, t3, 和本地的 t1, t4 校准时间 //delt = ((t2-t1)+(t3-t4))/2 //current = t4 + delt func GetNtpTime(host string) (time.Time, error) { // Setup a UDP connection conn, err := net.Dial("udp", host) if err != nil { return time.Time{}, err } defer conn.Close() if err := conn.SetDeadline(time.Now().Add(3 * time.Second)); err != nil { return time.Time{}, err } // configure request settings by specifying the first byte as // 00 011 011 (or 0x1B) // | | +-- client mode (3) // | + ----- version (3) // + -------- leap year indicator, 0 no warning req := &packet{Settings: 0x1B} t1 := time.Now() // send time request if err := binary.Write(conn, binary.BigEndian, req); err != nil { return time.Time{}, err } // block to receive server response rsp := &packet{} if err := binary.Read(conn, binary.BigEndian, rsp); err != nil { return time.Time{}, err } t2 := intToTime(rsp.RxTimeSec, rsp.RxTimeFrac) t3 := intToTime(rsp.TxTimeSec, rsp.TxTimeFrac) t4 := time.Now() // On POSIX-compliant OS, time is expressed // using the Unix time epoch (or secs since year 1970). // NTP seconds are counted since 1900 and therefore must // be corrected with an epoch offset to convert NTP seconds // to Unix time by removing 70 yrs of seconds (1970-1900) // or 2208988800 seconds. /* js, _ := json.MarshalIndent(rsp, "", "\t") fmt.Println(string(js)) */ //t2 - t1 -> deltaNet + deltaTime = d1 //t3 - t4 -> -deltaNet + deltaTime = d2 //如果deltaNet相同 //判断t2 - t1 和 t3 - t4 绝对值的 倍数，如果超过2倍，认为无效(请求和回复延时严重不对称) d1 := t2.Sub(t1) d2 := t3.Sub(t4) delt := (d1 + d2) / 2 return t4.Add(delt), nil } //n timeserver //n/2+1 is ok and the same type durationSlice []time.Duration func (s durationSlice) Len() int { return len(s) } func (s durationSlice) Less(i, j int) bool { return s[i] < s[j] } func (s durationSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] } //GetRealTime 获取实际时间 func GetRealTime(hosts []string) time.Time { q := len(hosts)/2 + 1 ch := make(chan time.Duration, len(hosts)) for i := 0; i < len(hosts); i++ { go func(host string) { ntptime, _ := getTimeRetry(host, 10) if ntptime.IsZero() { ch <- time.Duration(math.MaxInt64) } else { dt := time.Until(ntptime) fmt.Println(host, dt) ch <- dt } }(hosts[i]) } dtlist := make([]time.Duration, 0) for i := 0; i < len(hosts); i++ { t := <-ch if t == time.Duration(math.MaxInt64) { continue } dtlist = append(dtlist, t) fmt.Println(dtlist) if len(dtlist) >= q { calclist := make([]time.Duration, len(dtlist)) copy(calclist, dtlist) sort.Sort(durationSlice(calclist)) calclist = maxSubList(calclist) if len(calclist) < q { continue } drift := time.Duration(0) for i := 0; i < len(calclist); i++ { drift += calclist[i] } return time.Now().Add(drift / time.Duration(len(calclist))) } } return time.Time{} } func abs(t time.Duration) time.Duration { if t < 0 { return -t } return t } func maxSubList(list []time.Duration) (sub []time.Duration) { start := 0 end := 0 if len(list) == 0 { return list } for i := 0; i < len(list); i++ { var nextheight time.Duration if i+1 == len(list) { nextheight = math.MaxInt64 } else { nextheight = list[i+1] } if abs(nextheight-list[i]) > time.Millisecond*100 { end = i + 1 if len(sub) < (end - start) { sub = list[start:end] } start = i + 1 end = i + 1 } else { end = i + 1 } } //只有一个节点，那么取差最小的节点 if len(sub) <= 1 { return list[0:1] } return sub } //GetRealTimeRetry 重试获取实际时间 func GetRealTimeRetry(hosts []string, retry int) time.Time { for i := 0; i < retry; i++ { t := GetRealTime(hosts) if !t.IsZero() { return t } } return time.Time{} } func getTimeRetry(host string, retry int) (time.Time, error) { var lasterr error for i := 0; i < retry; i++ { t, err := GetNtpTime(host) if err != nil { lasterr = err if i < retry-1 { //have a rest time.Sleep(time.Millisecond * 10) continue } return time.Time{}, err } return t, nil } return time.Time{}, lasterr } func intToTime(sec, frac uint32) time.Time { secs := int64(sec) - int64(ntpEpochOffset) nanos := (int64(frac) * 1e9) >> 32 return time.Unix(secs, nanos) }