golang ipc 通信_golang 2.0

NTP（Network Time Protocol，网络时间协议）是由RFC 1305定义的时间同步协议，用来在分布式时间服务器和客户端之间进行时间同步。NTP基于UDP报文进行传输，使用的UDP端口号为123。

使用NTP的目的是对网络内所有具有时钟的设备进行时钟同步，使网络内所有设备的时钟保持一致，从而使设备能够提供基于统一时间的多种应用。

对于运行NTP的本地系统，既可以接收来自其他时钟源的同步，又可以作为时钟源同步其他的时钟，并且可以和其他设备互相同步。

其实NTP协议是很简单的协议，据说很快就要被代替了，之前还写过一个python解析flv协议文件代码，这些应用层协议都是开放的，不是私有的，知道协议是很容易解析出的，不说废话了

ntp.go

package main

import (

"bytes"

"encoding/binary"

)

const (

UNIX_STA_TIMESTAMP = 2208988800

)

/**

NTP协议 http://www.ntp.org/documentation.html

@author mengdj@outlook.com

*/

type Ntp struct {

//1:32bits

Li        uint8 //2 bits

Vn        uint8 //3 bits

Mode      uint8 //3 bits

Stratum   uint8

Poll      uint8

Precision uint8

//2:

RootDelay           int32

RootDispersion      int32

ReferenceIdentifier int32

//64位时间戳

ReferenceTimestamp uint64 //指示系统时钟最后一次校准的时间

OriginateTimestamp uint64 //指示客户向服务器发起请求的时间

ReceiveTimestamp   uint64 //指服务器收到客户请求的时间

TransmitTimestamp  uint64 //指示服务器向客户发时间戳的时间

}

func NewNtp() (p *Ntp) {

//其他参数通常都是服务器返回的

p = &Ntp{Li: 0, Vn: 3, Mode: 3, Stratum: 0}

return p

}

/**

构建NTP协议信息

*/

func (this *Ntp) GetBytes() []byte {

//注意网络上使用的是大端字节排序

buf := &bytes.Buffer{}

head := (this.Li << 6) | (this.Vn << 3) | ((this.Mode << 5) >> 5)

binary.Write(buf, binary.BigEndian, uint8(head))

binary.Write(buf, binary.BigEndian, this.Stratum)

binary.Write(buf, binary.BigEndian, this.Poll)

binary.Write(buf, binary.BigEndian, this.Precision)

//写入其他字节数据

binary.Write(buf, binary.BigEndian, this.RootDelay)

binary.Write(buf, binary.BigEndian, this.RootDispersion)

binary.Write(buf, binary.BigEndian, this.ReferenceIdentifier)

binary.Write(buf, binary.BigEndian, this.ReferenceTimestamp)

binary.Write(buf, binary.BigEndian, this.OriginateTimestamp)

binary.Write(buf, binary.BigEndian, this.ReceiveTimestamp)

binary.Write(buf, binary.BigEndian, this.TransmitTimestamp)

//[27 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

return buf.Bytes()

}

func (this *Ntp) Parse(bf []byte, useUnixSec bool) {

var (

bit8  uint8

bit32 int32

bit64 uint64

rb    *bytes.Reader

)

//貌似这binary.Read只能顺序读，不能跳着读，想要跳着读只能使用切片bf

rb = bytes.NewReader(bf)

binary.Read(rb, binary.BigEndian, &bit8)

//向右偏移6位得到前两位LI即可

this.Li = bit8 >> 6

//向右偏移2位,向右偏移5位,得到前中间3位

this.Vn = (bit8 << 2) >> 5

//向左偏移5位，然后右偏移5位得到最后3位

this.Mode = (bit8 << 5) >> 5

binary.Read(rb, binary.BigEndian, &bit8)

this.Stratum = bit8

binary.Read(rb, binary.BigEndian, &bit8)

this.Poll = bit8

binary.Read(rb, binary.BigEndian, &bit8)

this.Precision = bit8

//32bits

binary.Read(rb, binary.BigEndian, &bit32)

this.RootDelay = bit32

binary.Read(rb, binary.BigEndian, &bit32)

this.RootDispersion = bit32

binary.Read(rb, binary.BigEndian, &bit32)

this.ReferenceIdentifier = bit32

//以下几个字段都是64位时间戳(NTP都是64位的时间戳)

binary.Read(rb, binary.BigEndian, &bit64)

this.ReferenceTimestamp = bit64

binary.Read(rb, binary.BigEndian, &bit64)

this.OriginateTimestamp = bit64

binary.Read(rb, binary.BigEndian, &bit64)

this.ReceiveTimestamp = bit64

binary.Read(rb, binary.BigEndian, &bit64)

this.TransmitTimestamp = bit64

//转换为unix时间戳,先左偏移32位拿到64位时间戳的整数部分，然后ntp的起始时间戳 1900年1月1日 0时0分0秒 2208988800

if useUnixSec {

this.ReferenceTimestamp = (this.ReceiveTimestamp >> 32) - UNIX_STA_TIMESTAMP

if this.OriginateTimestamp > 0 {

this.OriginateTimestamp = (this.OriginateTimestamp >> 32) - UNIX_STA_TIMESTAMP

}

this.ReceiveTimestamp = (this.ReceiveTimestamp >> 32) - UNIX_STA_TIMESTAMP

this.TransmitTimestamp = (this.TransmitTimestamp >> 32) - UNIX_STA_TIMESTAMP

}

}

main.go

package main

import (

"fmt"

"log"

"net"

)

func main() {

var (

ntp    *Ntp

buffer []byte

err    error

ret    int

)

//链接阿里云NTP服务器,NTP有很多免费服务器可以使用time.windows.com

conn, err := net.Dial("udp", "ntp1.aliyun.com:123")

defer func() {

if err := recover(); err != nil {

log.Println(err)

}

conn.Close()

}()

ntp = NewNtp()

conn.Write(ntp.GetBytes())

buffer = make([]byte, 2048)

ret, err = conn.Read(buffer)

if err == nil {

if ret > 0 {

ntp.Parse(buffer, true)

fmt.Println(fmt.Sprintf(

"LI:%d\r\n版本:%d\r\n模式:%d\r\n精度:%d\r\n轮询:%d\r\n系统精度:%d\r\n延时:%ds\r\n最大误差:%d\r\n时钟表示:%d\r\n时间戳:%d %d %d %d\r\n",

ntp.Li,

ntp.Vn,

ntp.Mode,

ntp.Stratum,

ntp.Poll,

ntp.Precision,

ntp.RootDelay,

ntp.RootDispersion,

ntp.ReferenceIdentifier,

ntp.ReferenceTimestamp,

ntp.OriginateTimestamp,

ntp.ReceiveTimestamp,

ntp.TransmitTimestamp,

))

}

}

}

golang ipc 通信_golang 2.0

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