Golang Client.DialTimeout方法代碼示例

func LookupIP(domain string, timeout int) ([]string, error) {
	var c dns.Client
	var err error
	ips := []string{}
	domain = strings.TrimRight(domain, ".") + "."
	c.DialTimeout = time.Duration(timeout) * time.Millisecond
	c.ReadTimeout = time.Duration(timeout) * time.Millisecond
	c.WriteTimeout = time.Duration(timeout) * time.Millisecond

	m := new(dns.Msg)
	m.SetQuestion(domain, dns.TypeA)

	ret, _, err := c.Exchange(m, "114.114.114.114:53")
	if err != nil {
		domain = strings.TrimRight(domain, ".")
		e := fmt.Sprintf("lookup error: %s, %s", domain, err.Error())
		return ips, errors.New(e)
	}

	for _, i := range ret.Answer {
		result := strings.Split(i.String(), "\t")
		if result[3] == "A" && IsIP(result[4]) {
			ips = append(ips, result[4])
		}
	}
	return ips, err
}

func lookupHost(host string, config *dns.ClientConfig) (addrs []string, err error) {
	if utilNet.IsValidIpv4(host) || utilNet.IsValidIpv6(host) {
		return []string{host}, nil
	}
	if host == "localhost" {
		return []string{"127.0.0.1", "::1"}, nil
	}

	c := new(dns.Client)
	c.DialTimeout = DialTimeout
	c.ReadTimeout = ReadTimeout
	c.WriteTimeout = WriteTimeout
	m := new(dns.Msg)
	m.SetQuestion(dns.Fqdn(host), dns.TypeA)
	var r *dns.Msg
	for i := 0; i < len(config.Servers); i++ {
		r, _, err = c.Exchange(m, config.Servers[i]+":"+config.Port)
		if err != nil {
			continue
		}
		err = nil
	}
	if err != nil {
		return nil, e.Forward(err)
	}
	if r.Rcode != dns.RcodeSuccess {
		return nil, e.New("can't resolve %v", host)
	}

	addrs = make([]string, 0, 10)
	for _, a := range r.Answer {
		if addr, ok := a.(*dns.A); ok {
			addrs = append(addrs, addr.A.String())
		}
	}

	m.SetQuestion(dns.Fqdn(host), dns.TypeAAAA)
	for i := 0; i < len(config.Servers); i++ {
		r, _, err = c.Exchange(m, config.Servers[0]+":"+config.Port)
		if err != nil {
			continue
		}
		err = nil
	}
	if err != nil {
		return nil, e.Forward(err)
	}
	if r.Rcode != dns.RcodeSuccess {
		return nil, e.New("no success")
	}

	for _, a := range r.Answer {
		if addr, ok := a.(*dns.AAAA); ok {
			addrs = append(addrs, addr.AAAA.String())
		}
	}
	return
}

func LookupIp(ip string) (host string, err error) {
	if !utilNet.IsValidIpv4(ip) && !utilNet.IsValidIpv6(ip) {
		return "", e.New("not a valid ip address")
	}
	if ip == "127.0.0.1" || ip == "::1" {
		return "localhost", nil
	}
	config, err := dns.ClientConfigFromFile(ConfigurationFile)
	if err != nil {
		return "", e.Forward(err)
	}
	config.Timeout = Timeout

	c := new(dns.Client)
	c.DialTimeout = DialTimeout
	c.ReadTimeout = ReadTimeout
	c.WriteTimeout = WriteTimeout
	m := new(dns.Msg)
	rev, err := dns.ReverseAddr(ip)
	if err != nil {
		return "", e.Forward(err)
	}
	m.SetQuestion(rev, dns.TypePTR)
	var r *dns.Msg
	for i := 0; i < len(config.Servers); i++ {
		r, _, err = c.Exchange(m, config.Servers[i]+":"+config.Port)
		if err != nil {
			continue
		}
		err = nil
	}
	if err != nil {
		return "", e.Forward(err)
	}
	if r.Rcode != dns.RcodeSuccess {
		return "", e.New("can't resolve %v", ip)
	}

	for _, a := range r.Answer {
		if ptr, ok := a.(*dns.PTR); ok {
			return strings.TrimSuffix(ptr.Ptr, "."), nil
		}
	}
	return "", e.New("no ptr available")
}

// defaultExtResolver queries other nameserver, potentially recurses; callers should probably be invoking extResolver
// instead since that's the pluggable entrypoint into external resolution.
func (res *Resolver) defaultExtResolver(r *dns.Msg, nameserver string, proto string, cnt int) (*dns.Msg, error) {
	var in *dns.Msg
	var err error

	c := new(dns.Client)
	c.Net = proto

	var t time.Duration = 5 * 1e9
	if res.config.Timeout != 0 {
		t = time.Duration(int64(res.config.Timeout * 1e9))
	}

	c.DialTimeout = t
	c.ReadTimeout = t
	c.WriteTimeout = t

	in, _, err = c.Exchange(r, nameserver)
	if err != nil {
		return in, err
	}

	// recurse
	if (in != nil) && (len(in.Answer) == 0) && (!in.MsgHdr.Authoritative) && (len(in.Ns) > 0) && (err != nil) {

		if cnt == recurseCnt {
			logging.CurLog.NonMesosRecursed.Inc()
		}

		if cnt > 0 {
			if soa, ok := (in.Ns[0]).(*dns.SOA); ok {
				return res.defaultExtResolver(r, net.JoinHostPort(soa.Ns, "53"), proto, cnt-1)
			}
		}

	}

	return in, err
}