使用Go实现了一个ping命令

• 注意差错校验CheckSum在总字节为奇数时，需要将最后一个byte左移8位凑成16位
• 在操作binary时注意网络字节序问题
  github地址 https://github.com/openex27/Ping/blob/master/Ping.go

package main

import (
    "bytes"
    "encoding/binary"
    "fmt"
    "net"
    "os"
    "strconv"
    "time"
)

const (
    MAX_PG = 2000
)

type ICMP struct {
    Type        uint8
    Code        uint8
    Checksum    uint16
    Identifier  uint16
    SequenceNum uint16
}

var (
    originBytes []byte
)

func init() {
    originBytes = make([]byte, MAX_PG)
}

func CheckSum(data []byte) (rt uint16) {
    var (
        sum    uint32
        length int = len(data)
        index  int
    )
    for length > 1 {
        sum += uint32(data[index])<<8 + uint32(data[index+1])
        index += 2
        length -= 2
    }
    if length > 0 {
        sum += uint32(data[index]) << 8
    }
    rt = uint16(sum) + uint16(sum>>16)

    return ^rt
}

func Ping(domain string, PS, Count int) {
    var (
        icmp                      ICMP
        laddr                     = net.IPAddr{IP: net.ParseIP("0.0.0.0")}
        raddr, _                  = net.ResolveIPAddr("ip", domain)
        max_lan, min_lan, avg_lan float64
    )

    conn, err := net.DialIP("ip4:icmp", &laddr, raddr)

    if err != nil {
        fmt.Println(err.Error())
        return
    }

    defer conn.Close()
    icmp.Type = 8
    icmp.Code = 0
    icmp.Checksum = 0
    icmp.Identifier = 0
    icmp.SequenceNum = 0

    var buffer bytes.Buffer
    binary.Write(&buffer, binary.BigEndian, icmp)
    binary.Write(&buffer, binary.BigEndian, originBytes[0:PS])
    b := buffer.Bytes()
    binary.BigEndian.PutUint16(b[2:], CheckSum(b))
    fmt.Printf("\n正在 Ping %s 具有 %d(%d) 字节的数据:\n", raddr.String(), PS,PS+28)
    recv := make([]byte, 1024)
    ret_list := []float64{}
    dropPack := 0.0
    max_lan = 3000.0
    min_lan = 0.0
    avg_lan = 0.0
    for i := Count; i > 0; i-- {
        if _, err := conn.Write(buffer.Bytes()); err != nil {
            dropPack++
            time.Sleep(time.Second)
            continue
        }
        t_start := time.Now()
        conn.SetReadDeadline((time.Now().Add(time.Second * 3)))
        _, err := conn.Read(recv)
        if err != nil {
            dropPack++
            time.Sleep(time.Second)
            continue
        }
        t_end := time.Now()
        dur := float64(t_end.Sub(t_start).Nanoseconds()) / 1e6
        ret_list = append(ret_list, dur)
        if dur < max_lan {
            max_lan = dur
        }
        if dur > min_lan {
            min_lan = dur
        }
        fmt.Printf("来自 %s 的回复: 时间 = %.3fms\n", raddr.String(), dur)
        time.Sleep(time.Second)
    }
    fmt.Printf("丢包率: %.2f%%\n", dropPack/float64(Count))
    if len(ret_list) == 0 {
        avg_lan = 3000.0
    } else {
        sum := 0.0
        for _, n := range ret_list {
            sum += n
        }
        avg_lan = sum / float64(len(ret_list))
    }
    fmt.Printf("rtt min/avg/max = %.3fms/%.3fms/%.3fms\n", min_lan, avg_lan, max_lan)

}

func main() {
    if len(os.Args) < 3 {
        fmt.Printf("Param domain |data package Sizeof|trace times\n Ex: ./Ping www.so.com 100 4\n")
        os.Exit(1)
    }
    PS, err := strconv.Atoi(os.Args[2])
    if err != nil {
        fmt.Println("you need input correct PackageSizeof(complete int)")
        os.Exit(1)
    }
    Count, err := strconv.Atoi(os.Args[3])
    if err != nil {
        fmt.Println("you need input correct Counts")
        os.Exit(1)
    }
    Ping(os.Args[1], PS, Count)
}