Go实现 icmp 协议 ping

前段时间在用go写个工具,偶然在github上发现了一个用go写的icmp协议ping的实现代码,在此分享
编辑的时候用pre标签格式化代码好像有点问题,附上原链接 https://github.com/paulstuart/ping/blob/master/ping.go
原Ping()中超时时间为 time.Second秒位单位 ,下面我改成 time.Millisecond毫秒位单位

package main

import (
        "bytes"
        "errors"
        "net"
        "os"
        "time"
)

const (
        icmpv4EchoRequest = 8
        icmpv4EchoReply = 0
        icmpv6EchoRequest = 128
        icmpv6EchoReply = 129
)

type icmpMessage struct {
        Type int // type
        Code int // code
        Checksum int // checksum
        Body icmpMessageBody // body
}

type icmpMessageBody interface {
        Len() int
        Marshal() ([]byte, error)
}

func main() {
    ip := "192.168.1.1" //IP地址
    timeout := 400       //设置一个ping超时时间,单位为毫秒
    if Ping(ip, timeout) {
       fmt.Println("ping ", ip, "ok!")
       return
    }
    fmt.Println("ping ", ip, "fail!")
}

// Marshal returns the binary enconding of the ICMP echo request or
// reply message m.
func (m *icmpMessage) Marshal() ([]byte, error) {
        b := []byte{byte(m.Type), byte(m.Code), 0, 0}
        if m.Body != nil && m.Body.Len() != 0 {
                mb, err := m.Body.Marshal()
                if err != nil {
                        return nil, err
                }
                b = append(b, mb...)
        }
        switch m.Type {
        case icmpv6EchoRequest, icmpv6EchoReply:
                return b, nil
        }
        csumcv := len(b) - 1 // checksum coverage
        s := uint32(0)
        for i := 0; i >16 + s&0xffff
        s = s + s>>16
        // Place checksum back in header; using ^= avoids the
        // assumption the checksum bytes are zero.
        b[2] ^= byte(^s & 0xff)
        b[3] ^= byte(^s >> 8)
        return b, nil
}

// parseICMPMessage parses b as an ICMP message.
func parseICMPMessage(b []byte) (*icmpMessage, error) {
        msglen := len(b)
        if msglen  4 {
                var err error
                switch m.Type {
                case icmpv4EchoRequest, icmpv4EchoReply, icmpv6EchoRequest, icmpv6EchoReply:
                        m.Body, err = parseICMPEcho(b[4:])
                        if err != nil {
                                return nil, err
                        }
                }
        }
        return m, nil
}

// imcpEcho represenets an ICMP echo request or reply message body.
type icmpEcho struct {
        ID int // identifier
        Seq int // sequence number
        Data []byte // data
}

func (p *icmpEcho) Len() int {
        if p == nil {
                return 0
        }
        return 4 + len(p.Data)
}

// Marshal returns the binary enconding of the ICMP echo request or
// reply message body p.
func (p *icmpEcho) Marshal() ([]byte, error) {
        b := make([]byte, 4+len(p.Data))
        b[0], b[1] = byte(p.ID>>8), byte(p.ID&0xff)
        b[2], b[3] = byte(p.Seq>>8), byte(p.Seq&0xff)
        copy(b[4:], p.Data)
        return b, nil
}

// parseICMPEcho parses b as an ICMP echo request or reply message body.
func parseICMPEcho(b []byte) (*icmpEcho, error) {
        bodylen := len(b)
        p := &icmpEcho{ID: int(b[0]) 4 {
                p.Data = make([]byte, bodylen-4)
                copy(p.Data, b[4:])
        }
        return p, nil
}

func Ping(address string, timeout int) (alive bool) {
        err := Pinger(address, timeout)
        alive = err == nil
        return
}

func Pinger(address string, timeout int) (err error) {
        c, err := net.Dial("ip4:icmp", address)
        if err != nil {
                return
        }
        c.SetDeadline(time.Now().Add(time.Duration(timeout) * time.Millisecond))
        defer c.Close()

    typ := icmpv4EchoRequest
    xid, xseq := os.Getpid()&0xffff, 1
    wb, err := (&icmpMessage{
            Type: typ, Code: 0,
            Body: &icmpEcho{
                    ID: xid, Seq: xseq,
                    Data: bytes.Repeat([]byte("Go Go Gadget Ping!!!"), 3),
            },
    }).Marshal()
    if err != nil {
            return
    }
    if _, err = c.Write(wb); err != nil {
            return
    }
    var m *icmpMessage
    rb := make([]byte, 20+len(wb))
    for {
            if _, err = c.Read(rb); err != nil {
                    return
            }
            rb = ipv4Payload(rb)
            if m, err = parseICMPMessage(rb); err != nil {
                    return
            }
            switch m.Type {
            case icmpv4EchoRequest, icmpv6EchoRequest:
                    continue
            }
            break
    }
    return

} func ipv4Payload(b []byte) []byte { if len(b) < 20 { return b } hdrlen := int(b[0]&0x0f) << 2 return b[hdrlen:] }

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