Golang1.7使用ICMP協議實現ping功能,帶TIME和TTL

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package mainimport (    "errors"    "fmt"    "math/rand"    "net"    "os"    "time"    "golang.org/x/net/icmp"    "golang.org/x/net/ipv4")func Lookup(host string) (string, error) {    addrs, err := net.LookupHost(host)    if err != nil {        return "", err    }    if len(addrs) < 1 {        return "", errors.New("unknown host")    }    rd := rand.New(rand.NewSource(time.Now().UnixNano()))    return addrs[rd.Intn(len(addrs))], nil}var Data = []byte("abcdefghijklmnopqrstuvwabcdefghi")type Reply struct {    Time  int64    TTL   uint8    Error error}func main() {    ping, err := Run("www.google.com", 8, Data)    if err != nil {        fmt.Println(err)        return    }    defer ping.Close()    ping.Ping(5)    fmt.Println(ping.PingCount(6))}func MarshalMsg(req int, data []byte) ([]byte, error) {    xid, xseq := os.Getpid()&0xffff, req    wm := icmp.Message{        Type: ipv4.ICMPTypeEcho, Code: 0,        Body: &icmp.Echo{            ID: xid, Seq: xseq,            Data: data,        },    }    return wm.Marshal(nil)}type ping struct {    Addr string    Conn net.Conn    Data []byte}func (self *ping) Dail() (err error) {    self.Conn, err = net.Dial("ip4:icmp", self.Addr)    if err != nil {        return err    }    return nil}func (self *ping) SetDeadline(timeout int) error {    return self.Conn.SetDeadline(time.Now().Add(time.Duration(timeout) * time.Second))}func (self *ping) Close() error {    return self.Conn.Close()}func (self *ping) Ping(count int) {    if err := self.Dail(); err != nil {        fmt.Println("Not found remote host")        return    }    fmt.Println("Start ping from ", self.Conn.LocalAddr())    self.SetDeadline(10)    for i := 0; i < count; i++ {        r := sendPingMsg(self.Conn, self.Data)        if r.Error != nil {            if opt, ok := r.Error.(*net.OpError); ok && opt.Timeout() {                fmt.Printf("From %s reply: TimeOut\n", self.Addr)                if err := self.Dail(); err != nil {                    fmt.Println("Not found remote host")                    return                }            } else {                fmt.Printf("From %s reply: %s\n", self.Addr, r.Error)            }        } else {            fmt.Printf("From %s reply: time=%d ttl=%d\n", self.Addr, r.Time, r.TTL)        }        time.Sleep(1e9)    }}func (self *ping) PingCount(count int) (reply []Reply) {    if err := self.Dail(); err != nil {        fmt.Println("Not found remote host")        return    }    self.SetDeadline(10)    for i := 0; i < count; i++ {        r := sendPingMsg(self.Conn, self.Data)        reply = append(reply, r)        time.Sleep(1e9)    }    return}func Run(addr string, req int, data []byte) (*ping, error) {    wb, err := MarshalMsg(req, data)    if err != nil {        return nil, err    }    addr, err = Lookup(addr)    if err != nil {        return nil, err    }    return &ping{Data: wb, Addr: addr}, nil}func sendPingMsg(c net.Conn, wb []byte) (reply Reply) {    start := time.Now()    if _, reply.Error = c.Write(wb); reply.Error != nil {        return    }    rb := make([]byte, 1500)    var n int    n, reply.Error = c.Read(rb)    if reply.Error != nil {        return    }    duration := time.Now().Sub(start)    ttl := uint8(rb[8])    rb = func(b []byte) []byte {        if len(b) < 20 {            return b        }        hdrlen := int(b[0]&0x0f) << 2        return b[hdrlen:]    }(rb)    var rm *icmp.Message    rm, reply.Error = icmp.ParseMessage(1, rb[:n])    if reply.Error != nil {        return    }    switch rm.Type {    case ipv4.ICMPTypeEchoReply:        t := int64(duration / time.Millisecond)        reply = Reply{t, ttl, nil}    case ipv4.ICMPTypeDestinationUnreachable:        reply.Error = errors.New("Destination Unreachable")    default:        reply.Error = fmt.Errorf("Not ICMPTypeEchoReply %v", rm)    }    return}