Golang PacketConn.ReadFrom方法代码示例

func (p *Pinger) recvICMP(conn *icmp.PacketConn, ctx *context, wg *sync.WaitGroup) {

	for {
		select {
		case <-ctx.stop:
			wg.Done()
			return
		default:
		}

		bytes := make([]byte, 512)
		conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))

		_, ra, err := conn.ReadFrom(bytes)

		if err != nil {
			if neterr, ok := err.(*net.OpError); ok {
				if neterr.Timeout() {
					continue
				} else {
					// prevent 2x close in different threads
					p.mu.Lock()
					if ctx.err == nil {
						close(ctx.done)
					}
					ctx.err = err
					p.mu.Unlock()
					wg.Done()
					return
				}
			}
		}
		p.procRecv(bytes, ra, ctx)
	}
}

func (p *Pinger) recvICMP(
	conn *icmp.PacketConn,
	recv chan<- *packet,
	wg *sync.WaitGroup,
) {
	defer wg.Done()
	for {
		select {
		case <-p.done:
			return
		default:
			bytes := make([]byte, 512)
			conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
			n, _, err := conn.ReadFrom(bytes)
			if err != nil {
				if neterr, ok := err.(*net.OpError); ok {
					if neterr.Timeout() {
						// Read timeout
						continue
					} else {
						close(p.done)
						return
					}
				}
			}

			recv <- &packet{bytes: bytes, nbytes: n}
		}
	}
}

func (p *Pinger) recvICMP(conn *icmp.PacketConn, recv chan<- *packet, ctx *context, wg *sync.WaitGroup) {
	p.debugln("recvICMP(): Start")
	for {
		select {
		case <-ctx.stop:
			p.debugln("recvICMP(): <-ctx.stop")
			wg.Done()
			p.debugln("recvICMP(): wg.Done()")
			return
		default:
		}

		bytes := make([]byte, 512)
		conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
		p.debugln("recvICMP(): ReadFrom Start")
		_, ra, err := conn.ReadFrom(bytes)
		p.debugln("recvICMP(): ReadFrom End")
		if err != nil {
			if neterr, ok := err.(*net.OpError); ok {
				if neterr.Timeout() {
					p.debugln("recvICMP(): Read Timeout")
					continue
				} else {
					p.debugln("recvICMP(): OpError happen", err)
					p.mu.Lock()
					ctx.err = err
					p.mu.Unlock()
					p.debugln("recvICMP(): close(ctx.done)")
					close(ctx.done)
					p.debugln("recvICMP(): wg.Done()")
					wg.Done()
					return
				}
			}
		}
		p.debugln("recvICMP(): p.recv <- packet")

		select {
		case recv <- &packet{bytes: bytes, addr: ra}:
		case <-ctx.stop:
			p.debugln("recvICMP(): <-ctx.stop")
			wg.Done()
			p.debugln("recvICMP(): wg.Done()")
			return
		}
	}
}

func ping(listener *icmp.PacketConn, message icmp.Message, raddr net.Addr, timeout time.Duration) (Pong, error) {
	data, err := message.Marshal(nil)
	if err != nil {
		return Pong{}, err
	}
	_, err = listener.WriteTo(data, raddr)
	if err != nil {
		return Pong{}, err
	}
	now := time.Now()
	done := make(chan Pong)
	go func() {
		for {
			buf := make([]byte, 10000)
			// bufio
			n, peer, err := listener.ReadFrom(buf)
			if err != nil {
				return
			}
			since := time.Since(now)
			input, err := icmp.ParseMessage(protocolICMP, buf[:n])
			if err != nil {
				return
			}
			if input.Type != ipv4.ICMPTypeEchoReply {
				continue
			}
			echo := input.Body.(*icmp.Echo)
			pong := Pong{
				Peer: peer,
				ID:   echo.ID,
				Seq:  echo.Seq,
				Data: echo.Data,
				Size: n,
				RTT:  since,
			}
			done <- pong
			return
		}
	}()
	select {
	case pong := <-done:
		return pong, nil
	case <-time.After(timeout):
		return Pong{}, errors.New("Timeout")
	}
}

// This checks if we can convert an URL to an IP
func testDNS(pr *pingResponse, pi pingInfo, conn *icmp.PacketConn) {
	start := time.Now()
	msg := createMessage()

	msg_bytes, err := msg.Marshal(nil)
	if err != nil {
		emsg := "Could not marshal the message to []byte."
		logger.WriteString(emsg)
		pr.err = errors.New(emsg)
		return
	}

	ip, _ := net.LookupHost(pi.externalurl)

	if _, err := conn.WriteTo(msg_bytes, &net.UDPAddr{IP: net.ParseIP(ip[0]), Zone: "en0"}); err != nil {
		emsg := "Could not write to the internal ip address: " + ip[0]
		logger.WriteString(emsg)
		pr.external_url = false
		pr.err = errors.New(emsg)
		return
	}

	pr.external_url = true

	response := make([]byte, 1500)
	count, peer, err := conn.ReadFrom(response)
	if err != nil {
		emsg := "Could not read the response."
		logger.WriteString(emsg)
		pr.external_url = false
		pr.err = errors.New(emsg)
		return
	}

	_, err = icmp.ParseMessage(protocolICMP, response[:count])
	if err != nil {
		emsg := "Could not parse the message received."
		logger.WriteString(emsg)
		pr.external_url = false
		pr.err = errors.New(emsg)
		return
	}

	logger.WriteString("Response " + strconv.Itoa(sequence) + " received from " + peer.String() +
		" after " + time.Now().Sub(start).String())
}

// Sends a single ICMP echo to an IP and returns success and latency information.
// Borrowed from BrianBrazil's blackbox exporter
func Ping(ip net.IP, maxRTT time.Duration) (success bool, latency time.Duration) {
	deadline := time.Now().Add(maxRTT)

	var socket *icmp.PacketConn
	var err error
	if isIPv4(ip) {
		socket, err = icmp.ListenPacket("ip4:icmp", "0.0.0.0")
	} else if isIPv6(ip) {
		socket, err = icmp.ListenPacket("ip6:ipv6-icmp", "::")
	} else {
		log.Errorln("IP did not match any known types?")
		return
	}

	if err != nil {
		log.Errorf("Error listening to socket: %s", err)
		return
	}
	defer socket.Close()

	seq := getICMPSequence()
	pid := os.Getpid() & 0xffff

	// Build the packet
	var wm icmp.Message
	if isIPv4(ip) {
		wm = icmp.Message{
			Type: ipv4.ICMPTypeEcho, Code: 0,
			Body: &icmp.Echo{
				ID: pid, Seq: int(seq),
				Data: []byte("poller_exporter"),
			},
		}
	} else if isIPv6(ip) {
		wm = icmp.Message{
			Type: ipv6.ICMPTypeEchoRequest, Code: 0,
			Body: &icmp.Echo{
				ID: pid, Seq: int(seq),
				Data: []byte("poller_exporter"),
			},
		}
	} else {
		log.Errorln("IP did not match any known types?")
		return
	}

	wb, err := wm.Marshal(nil)
	if err != nil {
		log.Errorf("Error marshalling packet for %s: %s", ip.String(), err)
		return
	}

	sendTime := time.Now()

	var dst *net.IPAddr
	dst = &net.IPAddr{IP: ip}

	if _, err := socket.WriteTo(wb, dst); err != nil {
		log.Errorf("Error writing to socket for %s: %s", ip.String(), err)
		return
	}

	// Reply should be the same except for the message type.
	if isIPv4(ip) {
		wm.Type = ipv4.ICMPTypeEchoReply
	} else if isIPv6(ip) {
		wm.Type = ipv6.ICMPTypeEchoReply
	} else {
		log.Errorln("IP did not match any known types?")
		return
	}

	wb, err = wm.Marshal(nil)
	if err != nil {
		log.Errorf("Error marshalling packet for %s: %s", ip.String(), err)
		return
	}

	rb := make([]byte, 1500)
	if err := socket.SetReadDeadline(deadline); err != nil {
		log.Errorf("Error setting socket deadline for %s: %s", ip.String(), err)
		return
	}
	for {
		n, peer, err := socket.ReadFrom(rb)
		if err != nil {
			if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
				log.Infof("Timeout reading from socket for %s: %s", ip.String(), err)
				return
			}
			log.Errorf("Error reading from socket for %s: %s", ip.String(), err)
			continue
		}
		if peer.String() != ip.String() {
			continue
		}
		if bytes.Compare(rb[:n], wb) == 0 {
			success = true
//.........这里部分代码省略.........

func (l *icmpLoop) runICMPRecv(conn *icmp.PacketConn, proto int) {
	for {
		bytes := make([]byte, 512)
		conn.SetReadDeadline(time.Now().Add(1 * time.Second))
		_, addr, err := conn.ReadFrom(bytes)
		if err != nil {
			if neterr, ok := err.(*net.OpError); ok {
				if neterr.Timeout() {
					continue
				} else {
					// TODO: report error and quit loop
					return
				}
			}
		}

		ts := time.Now()
		m, err := icmp.ParseMessage(proto, bytes)
		if err != nil {
			continue
		}

		// process echo reply only
		if m.Type != ipv4.ICMPTypeEchoReply && m.Type != ipv6.ICMPTypeEchoReply {
			continue
		}
		echo, ok := m.Body.(*icmp.Echo)
		if !ok {
			continue
		}

		id := requestID{
			addr:  addr.String(),
			proto: proto,
			id:    echo.ID,
			seq:   echo.Seq,
		}

		l.mutex.Lock()
		ctx := l.requests[id]
		if ctx != nil {
			delete(l.requests, id)
		}
		l.mutex.Unlock()

		// no return context available for echo reply -> handle next message
		if ctx == nil {
			continue
		}

		ctx.result <- requestResult{
			packet: packet{
				ts:   ts,
				addr: addr,

				Type:     m.Type,
				Code:     m.Code,
				Checksum: m.Checksum,
				Echo:     *echo,
			},
		}
	}
}

func probeICMP(target string, w http.ResponseWriter, module Module) (success bool) {
	var (
		socket           *icmp.PacketConn
		requestType      icmp.Type
		replyType        icmp.Type
		fallbackProtocol string
	)

	deadline := time.Now().Add(module.Timeout)

	// Defaults to IPv4 to be compatible with older versions
	if module.ICMP.Protocol == "" {
		module.ICMP.Protocol = "icmp"
	}

	// In case of ICMP prefer IPv6 by default
	if module.ICMP.Protocol == "icmp" && module.ICMP.PreferredIpProtocol == "" {
		module.ICMP.PreferredIpProtocol = "ip6"
	}

	if module.ICMP.Protocol == "icmp4" {
		module.ICMP.PreferredIpProtocol = "ip4"
		fallbackProtocol = ""
	} else if module.ICMP.Protocol == "icmp6" {
		module.ICMP.PreferredIpProtocol = "ip6"
		fallbackProtocol = ""
	} else if module.ICMP.PreferredIpProtocol == "ip6" {
		fallbackProtocol = "ip4"
	} else {
		fallbackProtocol = "ip6"
	}

	ip, err := net.ResolveIPAddr(module.ICMP.PreferredIpProtocol, target)
	if err != nil && fallbackProtocol != "" {
		ip, err = net.ResolveIPAddr(fallbackProtocol, target)
	}
	if err != nil {
		log.Errorf("Error resolving address %s: %s", target, err)
	}

	if ip.IP.To4() == nil {
		requestType = ipv6.ICMPTypeEchoRequest
		replyType = ipv6.ICMPTypeEchoReply
		socket, err = icmp.ListenPacket("ip6:ipv6-icmp", "::")
		fmt.Fprintf(w, "probe_ip_protocol 6\n")
	} else {
		requestType = ipv4.ICMPTypeEcho
		replyType = ipv4.ICMPTypeEchoReply
		socket, err = icmp.ListenPacket("ip4:icmp", "0.0.0.0")
		fmt.Fprintf(w, "probe_ip_protocol 4\n")
	}

	if err != nil {
		log.Errorf("Error listening to socket: %s", err)
		return
	}
	defer socket.Close()

	if err != nil {
		log.Errorf("Error resolving address %s: %s", target, err)
		return
	}

	seq := getICMPSequence()
	pid := os.Getpid() & 0xffff

	wm := icmp.Message{
		Type: requestType,
		Code: 0,
		Body: &icmp.Echo{
			ID: pid, Seq: int(seq),
			Data: []byte("Prometheus Blackbox Exporter"),
		},
	}

	wb, err := wm.Marshal(nil)
	if err != nil {
		log.Errorf("Error marshalling packet for %s: %s", target, err)
		return
	}
	if _, err := socket.WriteTo(wb, ip); err != nil {
		log.Errorf("Error writing to socker for %s: %s", target, err)
		return
	}

	// Reply should be the same except for the message type.
	wm.Type = replyType
	wb, err = wm.Marshal(nil)
	if err != nil {
		log.Errorf("Error marshalling packet for %s: %s", target, err)
		return
	}

	rb := make([]byte, 1500)
	if err := socket.SetReadDeadline(deadline); err != nil {
		log.Errorf("Error setting socket deadline for %s: %s", target, err)
		return
	}
	for {
		n, peer, err := socket.ReadFrom(rb)
//.........这里部分代码省略.........