Golang Msg.Rcode方法代码示例

func (res *Resolver) handleEmpty(rs *records.RecordGenerator, name string, m, r *dns.Msg) error {
	qType := r.Question[0].Qtype
	switch qType {
	case dns.TypeSOA, dns.TypeNS, dns.TypeSRV:
		logging.CurLog.MesosSuccess.Inc()
		return nil
	}

	m.Rcode = dns.RcodeNameError
	if qType == dns.TypeAAAA && len(rs.SRVs[name])+len(rs.As[name]) > 0 {
		m.Rcode = dns.RcodeSuccess
	}

	logging.CurLog.MesosNXDomain.Inc()
	logging.VeryVerbose.Println("total A rrs:\t" + strconv.Itoa(len(rs.As)))
	logging.VeryVerbose.Println("failed looking for " + r.Question[0].String())

	rr, err := res.formatSOA(r.Question[0].Name)
	if err != nil {
		return err
	}

	m.Ns = append(m.Ns, rr)
	return nil
}

func (h *dnsHandler) leaderResponse(name string, q dns.Question, res *dns.Msg) {
	if q.Qtype != dns.TypeA {
		return
	}

	zone := strings.Replace(name, "leader.", "", 1)
	if zone != h.zone {
		servers, err := h.store.getServers(zone)
		if err != nil {
			res.Rcode = dns.RcodeServerFailure
			return
		}
		if len(servers) == 0 {
			res.Rcode = dns.RcodeNameError
			return
		}

		referral(res, fmt.Sprintf("%s.%s", zone, h.domain), servers)
		return
	}

	leader, err := h.store.getLeader()
	if err != nil {
		res.Rcode = dns.RcodeServerFailure
		return
	}
	res.Answer = append(res.Answer, newRR(q, leader))
}

// handlerFunc receives requests, looks up the result and returns what is found.
func handlerFunc(res dns.ResponseWriter, req *dns.Msg) {
	message := new(dns.Msg)
	switch req.Opcode {
	case dns.OpcodeQuery:
		message.SetReply(req)
		message.Compress = false
		message.Answer = make([]dns.RR, 0)

		for _, question := range message.Question {
			answers := answerQuestion(strings.ToLower(question.Name), question.Qtype)
			if len(answers) > 0 {
				for i := range answers {
					message.Answer = append(message.Answer, answers[i])
				}
			} else {
				// If there are no records, go back through and search for SOA records
				for _, question := range message.Question {
					answers := answerQuestion(strings.ToLower(question.Name), dns.TypeSOA)
					for i := range answers {
						message.Ns = append(message.Ns, answers[i])
					}
				}
			}
		}
		if len(message.Answer) == 0 && len(message.Ns) == 0 {
			message.Rcode = dns.RcodeNameError
		}
	default:
		message = message.SetRcode(req, dns.RcodeNotImplemented)
	}
	res.WriteMsg(message)
}

func makeDNSFailResponse(r *dns.Msg) *dns.Msg {
	m := new(dns.Msg)
	m.SetReply(r)
	m.RecursionAvailable = true
	m.Rcode = dns.RcodeNameError
	return m
}

func (t *UsageTracker) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
	var latest *usage.ProjectVersion
	var event *TrackingEvent

	m := new(dns.Msg)
	m.SetReply(r)

	q := r.Question[0].Name

	pv, err := usage.ParseV1(q)
	if err != nil {
		log.Printf("error parsing %s (%s): %s", q, w.RemoteAddr().(*net.UDPAddr).IP, err)
		// m.Rcode = dns.RcodeRefused
		m.Rcode = dns.RcodeNameError
		goto response
	}

	latest, err = t.GetLatest(pv)
	if err != nil {
		// TODO if format is right, but project is missing,
		// return an NXDOMAIN error
		log.Printf("error fetching latest for %v: %s", pv, err)
		m.Rcode = dns.RcodeNameError
		goto response
	}

	// do this after getting the version so we don't track results for
	// projects that aren't found
	event = &TrackingEvent{*pv, ""}
	if addr, ok := w.RemoteAddr().(*net.UDPAddr); ok {
		event.ClientAddress = addr.IP.String()
	}
	if err = t.Track(event); err != nil {
		log.Printf("error tracking %v: %s", event, err)
		// tracking error is not fatal, so still return the results
	}

	m.Answer = append(m.Answer, PtrRecord(latest))

response:
	err = w.WriteMsg(m)
	if err != nil {
		log.Printf("error writing response %v: %s", m, err)
	}
}

func prepareFailureMsg(req *dns.Msg) *dns.Msg {
	failMsg := new(dns.Msg)
	failMsg.Id = req.Id
	failMsg.Response = true
	failMsg.Authoritative = true
	failMsg.Question = req.Question
	failMsg.Rcode = dns.RcodeNameError
	return failMsg
}

func prepareAnswerMsg(req *dns.Msg, answers []dns.RR) *dns.Msg {
	answerMsg := new(dns.Msg)
	answerMsg.Id = req.Id
	answerMsg.Response = true
	answerMsg.Authoritative = true
	answerMsg.Question = req.Question
	answerMsg.Answer = answers
	answerMsg.Rcode = dns.RcodeSuccess
	answerMsg.Extra = []dns.RR{}
	return answerMsg
}

func (d *DNSServer) errorResponse(r *dns.Msg, code int, w dns.ResponseWriter) {
	m := dns.Msg{}
	m.SetReply(r)
	m.RecursionAvailable = true
	m.Rcode = code

	d.ns.debugf("error response: %+v", m)
	if err := w.WriteMsg(&m); err != nil {
		d.ns.infof("error responding: %v", err)
	}
}

func (h *dnsHandler) serviceResponse(name string, q dns.Question, res *dns.Msg) {
	if q.Qtype != dns.TypeA && q.Qtype != dns.TypeSRV {
		return
	}

	all := strings.Count(name, ".") == 5 && strings.HasPrefix(name, allPrefix)
	if all {
		name = name[len(allPrefix):]
	}

	srv, err := infoFromAddr(name)
	if err != nil {
		res.Rcode = dns.RcodeNameError
		return
	}

	var instances instances
	if all {
		instances, err = h.store.getAllInstances(srv)
	} else {
		instances, err = h.store.getHealthyInstances(srv)
	}
	if err != nil {
		// TODO(ts): Maybe return NoError for registered service without
		//           instances.
		if isNoInstances(err) {
			res.Rcode = dns.RcodeNameError
			return
		}

		res.Rcode = dns.RcodeServerFailure
		return
	}

	for _, i := range instances {
		res.Answer = append(res.Answer, newRR(q, i))
	}
}

func (h *dnsHandler) serverResponse(name string, q dns.Question, res *dns.Msg) {
	if q.Qtype != dns.TypeA && q.Qtype != dns.TypeNS {
		return
	}

	ns, zone := parseServerQuestion(name)
	if ns != "" && q.Qtype == dns.TypeNS {
		return
	}

	servers, err := h.store.getServers(zone)
	if err != nil && !isNoInstances(err) {
		res.Rcode = dns.RcodeServerFailure
		return
	}
	sort.Sort(servers)

	// return list of all nameservers
	if ns == "" {
		for i, server := range servers {
			server.host = fmt.Sprintf("ns%d.%s", i, q.Name)
			res.Answer = append(res.Answer, newRR(q, server))
		}
		return
	}

	// return requested nameserver
	index, err := strconv.Atoi(ns[2:])
	if err != nil {
		res.Rcode = dns.RcodeNameError
		return
	}
	if len(servers) <= index {
		return
	}
	res.Answer = append(res.Answer, newRR(q, servers[index]))
}

func (res *Resolver) handleEmpty(rs *records.RecordGenerator, name string, m, r *dns.Msg) error {
	qType := r.Question[0].Qtype
	switch qType {
	case dns.TypeSOA, dns.TypeNS, dns.TypeSRV:
		logging.CurLog.MesosSuccess.Inc()
		return nil
	}

	m.Rcode = dns.RcodeNameError

	// Because we don't implement AAAA records, AAAA queries will always
	// go via this path
	// Unfortunately, we don't implement AAAA queries in Mesos-DNS,
	// and although the 'Not Implemented' error code seems more suitable,
	// RFCs do not recommend it: https://tools.ietf.org/html/rfc4074
	// Therefore we always return success, which is synonymous with NODATA
	// to get a positive cache on no records AAAA
	// Further information:
	// PR: https://github.com/mesosphere/mesos-dns/pull/366
	// Issue: https://github.com/mesosphere/mesos-dns/issues/363

	// The second component is just a matter of returning NODATA if we have
	// SRV or A records for the given name, but no neccessarily the given query

	if (qType == dns.TypeAAAA) || (len(rs.SRVs[name])+len(rs.As[name]) > 0) {
		m.Rcode = dns.RcodeSuccess
	}

	logging.CurLog.MesosNXDomain.Inc()
	logging.VeryVerbose.Println("total A rrs:\t" + strconv.Itoa(len(rs.As)))
	logging.VeryVerbose.Println("failed looking for " + r.Question[0].String())

	m.Ns = append(m.Ns, res.formatSOA(r.Question[0].Name))

	return nil
}

func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
	q := r.Question[0]

	info := fmt.Sprintf("Question: Type=%s Class=%s Name=%s", dns.TypeToString[q.Qtype], dns.ClassToString[q.Qclass], q.Name)

	if q.Qtype == dns.TypeA && q.Qclass == dns.ClassINET {
		m := new(dns.Msg)
		m.SetReply(r)
		a := new(dns.A)
		a.Hdr = dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 600}
		a.A = resolveIP
		m.Answer = []dns.RR{a}
		w.WriteMsg(m)
		log.Printf("%s (RESOLVED)\n", info)
	} else {
		m := new(dns.Msg)
		m.SetReply(r)
		m.Rcode = dns.RcodeNameError // NXDOMAIN
		w.WriteMsg(m)
		log.Printf("%s (NXDOMAIN)\n", info)
	}
}

func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
	state := middleware.State{W: w, Req: r}

	if state.QClass() != dns.ClassINET {
		return dns.RcodeServerFailure, errors.New("can only deal with ClassINET")
	}
	qname := state.Name()
	zone := middleware.Zones(f.Zones.Names).Matches(qname)
	if zone == "" {
		if f.Next != nil {
			return f.Next.ServeDNS(ctx, w, r)
		}
		return dns.RcodeServerFailure, errors.New("no next middleware found")
	}
	z, ok := f.Zones.Z[zone]
	if !ok {
		return f.Next.ServeDNS(ctx, w, r)
	}
	if z == nil {
		return dns.RcodeServerFailure, nil
	}
	if r.Opcode == dns.OpcodeNotify {
		if z.isNotify(state) {
			m := new(dns.Msg)
			m.SetReply(r)
			m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
			state.SizeAndDo(m)
			w.WriteMsg(m)

			log.Printf("[INFO] Notify from %s for %s: checking transfer", state.IP(), zone)
			ok, err := z.shouldTransfer()
			if ok {
				z.TransferIn()
			} else {
				log.Printf("[INFO] Notify from %s for %s: no serial increase seen", state.IP(), zone)
			}
			if err != nil {
				log.Printf("[WARNING] Notify from %s for %s: failed primary check: %s", state.IP(), zone, err)
			}
			return dns.RcodeSuccess, nil
		}
		log.Printf("[INFO] Dropping notify from %s for %s", state.IP(), zone)
		return dns.RcodeSuccess, nil
	}

	if z.Expired != nil && *z.Expired {
		log.Printf("[ERROR] Zone %s is expired", zone)
		return dns.RcodeServerFailure, nil
	}

	if state.QType() == dns.TypeAXFR || state.QType() == dns.TypeIXFR {
		xfr := Xfr{z}
		return xfr.ServeDNS(ctx, w, r)
	}

	answer, ns, extra, result := z.Lookup(qname, state.QType(), state.Do())

	m := new(dns.Msg)
	m.SetReply(r)
	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
	m.Answer, m.Ns, m.Extra = answer, ns, extra

	switch result {
	case Success:
	case NoData:
	case NameError:
		m.Rcode = dns.RcodeNameError
	case Delegation:
		m.Authoritative = false
	case ServerFailure:
		return dns.RcodeServerFailure, nil
	}

	state.SizeAndDo(m)
	m, _ = state.Scrub(m)
	w.WriteMsg(m)
	return dns.RcodeSuccess, nil
}

// ServeDNS is the handler for DNS requests, responsible for parsing DNS request, possibly forwarding
// it to a real dns server and returning a response.
func (s *server) ServeDNS(w dns.ResponseWriter, req *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(req)
	m.Authoritative = true
	m.RecursionAvailable = true
	m.Compress = true
	bufsize := uint16(512)
	dnssec := false
	tcp := false
	start := time.Now()

	if req.Question[0].Qtype == dns.TypeANY {
		m.Authoritative = false
		m.Rcode = dns.RcodeRefused
		m.RecursionAvailable = false
		m.RecursionDesired = false
		m.Compress = false
		// if write fails don't care
		w.WriteMsg(m)

		promErrorCount.WithLabelValues("refused").Inc()
		return
	}

	if o := req.IsEdns0(); o != nil {
		bufsize = o.UDPSize()
		dnssec = o.Do()
	}
	if bufsize < 512 {
		bufsize = 512
	}
	// with TCP we can send 64K
	if tcp = isTCP(w); tcp {
		bufsize = dns.MaxMsgSize - 1
		promRequestCount.WithLabelValues("tcp").Inc()
	} else {
		promRequestCount.WithLabelValues("udp").Inc()
	}

	StatsRequestCount.Inc(1)

	if dnssec {
		StatsDnssecOkCount.Inc(1)
		promDnssecOkCount.Inc()
	}

	defer func() {
		promCacheSize.WithLabelValues("response").Set(float64(s.rcache.Size()))
	}()

	// Check cache first.
	key := cache.QuestionKey(req.Question[0], dnssec)
	m1, exp, hit := s.rcache.Search(key)
	if hit {
		// Cache hit! \o/
		if time.Since(exp) < 0 {
			m1.Id = m.Id
			m1.Compress = true
			m1.Truncated = false

			if dnssec {
				// The key for DNS/DNSSEC in cache is different, no
				// need to do Denial/Sign here.
				//if s.config.PubKey != nil {
				//s.Denial(m1) // not needed for cache hits
				//s.Sign(m1, bufsize)
				//}
			}
			if m1.Len() > int(bufsize) && !tcp {
				promErrorCount.WithLabelValues("truncated").Inc()
				m1.Truncated = true
			}
			// Still round-robin even with hits from the cache.
			// Only shuffle A and AAAA records with each other.
			if req.Question[0].Qtype == dns.TypeA || req.Question[0].Qtype == dns.TypeAAAA {
				s.RoundRobin(m1.Answer)
			}

			if err := w.WriteMsg(m1); err != nil {
				log.Printf("skydns: failure to return reply %q", err)
			}
			metricSizeAndDuration(m1, start, tcp)
			return
		}
		// Expired! /o\
		s.rcache.Remove(key)
	}

	q := req.Question[0]
	name := strings.ToLower(q.Name)

	if s.config.Verbose {
		log.Printf("skydns: received DNS Request for %q from %q with type %d", q.Name, w.RemoteAddr(), q.Qtype)
	}

	for zone, ns := range *s.config.stub {
		if strings.HasSuffix(name, zone) {
			resp := s.ServeDNSStubForward(w, req, ns)
//.........这里部分代码省略.........

func TestUDPDNSServer(t *testing.T) {
	setupForTest(t)

	const (
		successTestName = "test1.weave.local."
		failTestName    = "fail.weave.local."
		nonLocalName    = "weave.works."
		testAddr1       = "10.2.2.1"
		containerID     = "somecontainer"
	)
	testCIDR1 := testAddr1 + "/24"

	InitDefaultLogging(testing.Verbose())
	Info.Println("TestUDPDNSServer starting")

	zone, err := NewZoneDb(ZoneConfig{})
	require.NoError(t, err)
	err = zone.Start()
	require.NoError(t, err)
	defer zone.Stop()

	ip, _, _ := net.ParseCIDR(testCIDR1)
	zone.AddRecord(containerID, successTestName, ip)

	fallbackHandler := func(w dns.ResponseWriter, req *dns.Msg) {
		if len(req.Question) == 0 {
			return // ignore empty queries (sent when shutting down the server)
		}
		m := new(dns.Msg)
		m.SetReply(req)
		q := req.Question[0]
		if q.Name == nonLocalName && q.Qtype == dns.TypeMX {
			m.Answer = make([]dns.RR, 1)
			m.Answer[0] = &dns.MX{Hdr: dns.RR_Header{Name: m.Question[0].Name, Rrtype: dns.TypeMX, Class: dns.ClassINET, Ttl: 0}, Mx: "mail." + nonLocalName}
		} else if q.Name == nonLocalName && q.Qtype == dns.TypeANY {
			m.Answer = make([]dns.RR, 512/len("mailn."+nonLocalName)+1)
			for i := range m.Answer {
				m.Answer[i] = &dns.MX{Hdr: dns.RR_Header{Name: m.Question[0].Name, Rrtype: dns.TypeMX, Class: dns.ClassINET, Ttl: 0}, Mx: fmt.Sprintf("mail%d.%s", i, nonLocalName)}
			}
		} else if q.Name == testRDNSnonlocal && q.Qtype == dns.TypePTR {
			m.Answer = make([]dns.RR, 1)
			m.Answer[0] = &dns.PTR{Hdr: dns.RR_Header{Name: m.Question[0].Name, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: 0}, Ptr: "ns1.google.com."}
		} else if q.Name == testRDNSfail && q.Qtype == dns.TypePTR {
			m.Rcode = dns.RcodeNameError
		}
		w.WriteMsg(m)
	}

	// Run another DNS server for fallback
	fallback, err := newMockedFallback(fallbackHandler, nil)
	require.NoError(t, err)
	fallback.Start()
	defer fallback.Stop()

	srv, err := NewDNSServer(DNSServerConfig{
		Zone:              zone,
		UpstreamCfg:       fallback.CliConfig,
		CacheDisabled:     true,
		ListenReadTimeout: testSocketTimeout,
	})
	require.NoError(t, err)
	err = srv.Start()
	require.NoError(t, err)
	go srv.ActivateAndServe()
	defer srv.Stop()
	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start

	var r *dns.Msg

	testPort, err := srv.GetPort()
	require.NoError(t, err)
	require.NotEqual(t, 0, testPort, "invalid listen port")

	_, r = assertExchange(t, successTestName, dns.TypeA, testPort, 1, 1, 0)
	require.IsType(t, (*dns.A)(nil), r.Answer[0], "DNS record")
	require.Equal(t, testAddr1, r.Answer[0].(*dns.A).A.String(), "IP address")

	assertExchange(t, failTestName, dns.TypeA, testPort, 0, 0, dns.RcodeNameError)

	_, r = assertExchange(t, testRDNSsuccess, dns.TypePTR, testPort, 1, 1, 0)
	require.IsType(t, (*dns.PTR)(nil), r.Answer[0], "DNS record")
	require.Equal(t, successTestName, r.Answer[0].(*dns.PTR).Ptr, "IP address")

	assertExchange(t, testRDNSfail, dns.TypePTR, testPort, 0, 0, dns.RcodeNameError)

	// This should fail because we don't handle MX records
	assertExchange(t, successTestName, dns.TypeMX, testPort, 0, 0, dns.RcodeNameError)

	// This non-local query for an MX record should succeed by being
	// passed on to the fallback server
	assertExchange(t, nonLocalName, dns.TypeMX, testPort, 1, -1, 0)

	// Now ask a query that we expect to return a lot of data.
	assertExchange(t, nonLocalName, dns.TypeANY, testPort, 5, -1, 0)

	assertExchange(t, testRDNSnonlocal, dns.TypePTR, testPort, 1, -1, 0)

	// Not testing MDNS functionality of server here (yet), since it
	// needs two servers, each listening on its own address
}