如何使用“获取icmp（ping）目标ip地址”；golang.org/x/net/icmp“；

我有一个icmp侦听功能：

func Start(url string) {

conn, err := icmp.ListenPacket("ip4:icmp", url)
if err != nil {
    log.Fatal(err)
}

for {
    var msg []byte
    length, sourceIP, err := conn.ReadFrom(msg)

    if err != nil {
        log.Println(err)
        continue
    }
    fmt.Println(url + "===========")
    log.Printf("message = '%s', length = %d, source-ip = %s", string(msg), length, sourceIP)
}
_ = conn.Close()

}

由于我的服务器主机中有两张网卡，我用“start（0.0.0.0）”启动这个函数

ping到此服务器时，获取了以下信息：

2020/08/31 11:11:02 message = '', length = 0, source-ip = 192.168.255.133
192.168.255.128===========
2020/08/31 11:11:03 message = '', length = 0, source-ip = 192.168.255.133
192.168.255.128===========
2020/08/31 11:11:04 message = '', length = 0, source-ip = 192.168.255.133

仅源ip地址，如何获取ping目标ip地址