Implementing ICMP ping in Go

Is it p开发者_运维百科ossible to implement an ICMP ping in Go? The alternative is to fork a 'ping' process, but I'd rather write it in Go.

The following code shows how to perform a ping over IPv4 using a raw socket (requires root privs):

package main

import (
    "log"
    "net"
    "os"

    "golang.org/x/net/icmp"
    "golang.org/x/net/ipv4"
)

const targetIP = "8.8.8.8"

func main() {
    c, err := icmp.ListenPacket("ip4:icmp", "0.0.0.0")
    if err != nil {
        log.Fatalf("listen err, %s", err)
    }
    defer c.Close()

    wm := icmp.Message{
        Type: ipv4.ICMPTypeEcho, Code: 0,
        Body: &icmp.Echo{
            ID: os.Getpid() & 0xffff, Seq: 1,
            Data: []byte("HELLO-R-U-THERE"),
        },
    }
    wb, err := wm.Marshal(nil)
    if err != nil {
        log.Fatal(err)
    }
    if _, err := c.WriteTo(wb, &net.IPAddr{IP: net.ParseIP(targetIP)}); err != nil {
        log.Fatalf("WriteTo err, %s", err)
    }

    rb := make([]byte, 1500)
    n, peer, err := c.ReadFrom(rb)
    if err != nil {
        log.Fatal(err)
    }
    rm, err := icmp.ParseMessage(ipv4.ICMPTypeEchoReply.Protocol(), rb[:n])
    if err != nil {
        log.Fatal(err)
    }
    switch rm.Type {
    case ipv4.ICMPTypeEchoReply:
        log.Printf("got reflection from %v", peer)
    default:
        log.Printf("got %+v; want echo reply", rm)
    }
}

Code based on the example found here: https://godoc.org/golang.org/x/net/icmp#PacketConn

In order to ping from Linux as a non-privileged user, see this post

Currently, the ICMP Echo (Ping) function isn't supported in the Go net package.

There's no support for sending ICMP echo requests. You'd have to add support to package net. ping

To perform this without root requirement you can use

package main

import (
    "fmt"
    "net"
    "os"
    "time"

    "golang.org/x/net/icmp"
    "golang.org/x/net/ipv4"
)

const target = "google.com"

func main() {
    for {
        time.Sleep(time.Second * 1)
        Ping(target)
    }
}

func Ping(target string) {
    ip, err := net.ResolveIPAddr("ip4", target)
    if err != nil {
        panic(err)
    }
    conn, err := icmp.ListenPacket("udp4", "0.0.0.0")
    if err != nil {
        fmt.Printf("Error on ListenPacket")
        panic(err)
    }
    defer conn.Close()

    msg := icmp.Message{
        Type: ipv4.ICMPTypeEcho, Code: 0,
        Body: &icmp.Echo{
            ID: os.Getpid() & 0xffff, Seq: 1,
            Data: []byte(""),
        },
    }
    msg_bytes, err := msg.Marshal(nil)
    if err != nil {
        fmt.Printf("Error on Marshal %v", msg_bytes)
        panic(err)
    }

    // Write the message to the listening connection
    if _, err := conn.WriteTo(msg_bytes, &net.UDPAddr{IP: net.ParseIP(ip.String())}); err != nil {
        fmt.Printf("Error on WriteTo %v", err)
        panic(err)
    }

    err = conn.SetReadDeadline(time.Now().Add(time.Second * 1))
    if err != nil {
        fmt.Printf("Error on SetReadDeadline %v", err)
        panic(err)
    }
    reply := make([]byte, 1500)
    n, _, err := conn.ReadFrom(reply)

    if err != nil {
        fmt.Printf("Error on ReadFrom %v", err)
        panic(err)
    }
    parsed_reply, err := icmp.ParseMessage(1, reply[:n])

    if err != nil {
        fmt.Printf("Error on ParseMessage %v", err)
        panic(err)
    }

    switch parsed_reply.Code {
    case 0:
        // Got a reply so we can save this
        fmt.Printf("Got Reply from %s\n", target)
    case 3:
        fmt.Printf("Host %s is unreachable\n", target)
        // Given that we don't expect google to be unreachable, we can assume that our network is down
    case 11:
        // Time Exceeded so we can assume our network is slow
        fmt.Printf("Host %s is slow\n", target)
    default:
        // We don't know what this is so we can assume it's unreachable
        fmt.Printf("Host %s is unreachable\n", target)
    }
}