Golang Msg.Authoritative方法代碼示例

// Instantiate a new answer as a reply of the passed message.
func (h *ENUMHandler) answerForRequest(message *dns.Msg) *dns.Msg {
	answer := new(dns.Msg)
	answer.SetReply(message)
	answer.Authoritative = true
	answer.RecursionAvailable = false
	return answer
}

// handleDomain handles DNS queries that come to the cluster
func (d *DnsServer) handleDomain(w dns.ResponseWriter, r *dns.Msg) {
	dom, qType := parseQuestion(r)
	q := dns.TypeToString[qType] + " " + dom
	log.Printf("--> Internal: %s", q)

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

	supported, found, recs := d.queryRR(qType, dom)
	if !supported {
		log.Printf("<-x %s: NOTIMP", q)
		m.SetRcode(r, dns.RcodeNotImplemented) // NOTIMP
	} else if !found {
		log.Printf("<-x %s: NXDOMAIN", q)
		m.SetRcode(r, dns.RcodeNameError) // NXDOMAIN
	} else {
		for _, rec := range recs {
			rr, err := rrtype.ToRR(qType, dom, rec)
			if err != nil {
				log.Printf("<-x %s SERVFAIL: record conv err: %v", q, err)
				m.SetRcode(r, dns.RcodeServerFailure)
				break
			} else {
				log.Printf("<-- %s: %s", q, rr.String())
				m.Answer = append(m.Answer, rr)
			}
		}
	}
	w.WriteMsg(m)
}

// handleQUery is used to handle DNS queries in the configured domain
func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) {
	q := req.Question[0]
	defer func(s time.Time) {
		d.logger.Printf("[DEBUG] dns: request for %v (%v)", q, time.Now().Sub(s))
	}(time.Now())

	// Switch to TCP if the client is
	network := "udp"
	if _, ok := resp.RemoteAddr().(*net.TCPAddr); ok {
		network = "tcp"
	}

	// Setup the message response
	m := new(dns.Msg)
	m.SetReply(req)
	m.Authoritative = true
	m.RecursionAvailable = (len(d.recursors) > 0)

	// Only add the SOA if requested
	if req.Question[0].Qtype == dns.TypeSOA {
		d.addSOA(d.domain, m)
	}

	// Dispatch the correct handler
	d.dispatch(network, req, m)

	// Write out the complete response
	if err := resp.WriteMsg(m); err != nil {
		d.logger.Printf("[WARN] dns: failed to respond: %v", err)
	}
}

func (s *jujuNameServer) handleRequest(w dns.ResponseWriter, r *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(r)
	for _, q := range r.Question {
		rr, err := s.answer(q)
		if err != nil {
			m.SetRcodeFormatError(r)
			t := new(dns.TXT)
			t.Hdr = dns.RR_Header{
				Name:   q.Name,
				Rrtype: dns.TypeTXT,
				Class:  dns.ClassNONE,
			}
			t.Txt = []string{err.Error()}
			m.Extra = append(m.Extra, t)
			continue
		} else if rr != nil {
			m.Answer = append(m.Answer, rr)
		}
	}
	m.Authoritative = true
	// recursion isn't really available, but it's apparently
	// necessary to set this to make nslookup happy.
	m.RecursionAvailable = true
	w.WriteMsg(m)
}

func (h dnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
	if len(r.Question) != 1 {
		h.t.Fatalf("bad: %#v", r.Question)
	}

	name := "join.service.consul."
	question := r.Question[0]
	if question.Name != name || question.Qtype != dns.TypeANY {
		h.t.Fatalf("bad: %#v", question)
	}

	m := new(dns.Msg)
	m.SetReply(r)
	m.Authoritative = true
	m.RecursionAvailable = false
	m.Answer = append(m.Answer, &dns.A{
		Hdr: dns.RR_Header{
			Name:   name,
			Rrtype: dns.TypeA,
			Class:  dns.ClassINET},
		A: net.ParseIP("127.0.0.1"),
	})
	m.Answer = append(m.Answer, &dns.AAAA{
		Hdr: dns.RR_Header{
			Name:   name,
			Rrtype: dns.TypeAAAA,
			Class:  dns.ClassINET},
		AAAA: net.ParseIP("2001:db8:a0b:12f0::1"),
	})
	if err := w.WriteMsg(m); err != nil {
		h.t.Fatalf("err: %v", err)
	}
}

func (c *Config) GenerateServeDNS(hostname string) func(dns.ResponseWriter, *dns.Msg) {
	if len(hostname) > 0 {
		if hostname[len(hostname)-1] != '.' {
			hostname += "."
		}
	}

	return func(w dns.ResponseWriter, r *dns.Msg) {
		m := new(dns.Msg)
		m.SetReply(r)
		m.Authoritative = true

		ip, err := c.GetOrLaunchInstance()
		if err != nil {
			// TODO: error handling
			log.Println("Error in GetOrLaunchInstance:", err)
			w.Close()
			return
		}

		rr := new(dns.A)
		rr.Hdr = dns.RR_Header{Name: hostname, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: uint32(c.MaxIdleTime.Seconds())}
		rr.A = ip

		m.Answer = []dns.RR{rr}
		w.WriteMsg(m)
	}
}

// handleTest is used to handle DNS queries in the ".consul." domain
func (d *DNSServer) handleTest(resp dns.ResponseWriter, req *dns.Msg) {
	q := req.Question[0]
	defer func(s time.Time) {
		d.logger.Printf("[DEBUG] dns: request for %v (%v)", q, time.Now().Sub(s))
	}(time.Now())

	if !(q.Qtype == dns.TypeANY || q.Qtype == dns.TypeTXT) {
		return
	}
	if q.Name != testQuery {
		return
	}

	// Always respond with TXT "ok"
	m := new(dns.Msg)
	m.SetReply(req)
	m.Authoritative = true
	m.RecursionAvailable = true
	header := dns.RR_Header{Name: q.Name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
	txt := &dns.TXT{header, []string{"ok"}}
	m.Answer = append(m.Answer, txt)
	d.addSOA(consulDomain, m)
	if err := resp.WriteMsg(m); err != nil {
		d.logger.Printf("[WARN] dns: failed to respond: %v", err)
	}
}

func main() {
	runtime.GOMAXPROCS(runtime.NumCPU() * 4)
	for z, rr := range zones {
		rrx := rr.(*dns.SOA) // Needed to create the actual RR, and not an reference.
		dns.HandleFunc(z, func(w dns.ResponseWriter, r *dns.Msg) {
			m := new(dns.Msg)
			m.SetReply(r)
			m.Authoritative = true
			m.Ns = []dns.RR{rrx}
			w.WriteMsg(m)
		})
	}
	go func() {
		err := dns.ListenAndServe(":8053", "tcp", nil)
		if err != nil {
			log.Fatal("Failed to set tcp listener %s\n", err.Error())
		}
	}()
	go func() {
		err := dns.ListenAndServe(":8053", "udp", nil)
		if err != nil {
			log.Fatal("Failed to set udp listener %s\n", err.Error())
		}
	}()
	sig := make(chan os.Signal)
	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
	for {
		select {
		case s := <-sig:
			log.Fatalf("Signal (%d) received, stopping\n", s)
		}
	}
}

// handleExternal handles DNS queries that are outside the cluster's domain such
// as the Public Internet.
func (d *DnsServer) handleExternal(w dns.ResponseWriter, r *dns.Msg) {
	dom, qType := parseQuestion(r)
	q := dns.TypeToString[qType] + " " + dom
	log.Printf("--> External: %s", q)

	if !d.recurse {
		log.Printf("<-x %s: SERVFAIL: recursion disabled", q)
		m := new(dns.Msg)
		m.SetReply(r)
		m.SetRcode(r, dns.RcodeServerFailure)
		m.Authoritative = false
		m.RecursionAvailable = false
		w.WriteMsg(m)
	} else {
		in, ns, err := d.queryExternal(r)
		if err != nil {
			log.Printf("<-x %s (@%s): SERVFAIL: %v", q, ns, err)
			m := new(dns.Msg)
			m.SetReply(r)
			m.SetRcode(r, dns.RcodeServerFailure)
			w.WriteMsg(m)
		} else {
			log.Printf("<-- %s (@%s): %d answers, %d extra, %d ns", q, ns, len(in.Answer), len(in.Extra), len(in.Ns))
			in.Compress = true
			w.WriteMsg(in)
		}
	}
}

// handlePtr is used to handle "reverse" DNS queries
func (d *DNSServer) handlePtr(resp dns.ResponseWriter, req *dns.Msg) {
	q := req.Question[0]
	defer func(s time.Time) {
		d.logger.Printf("[DEBUG] dns: request for %v (%v) from client %s (%s)",
			q, time.Now().Sub(s), resp.RemoteAddr().String(),
			resp.RemoteAddr().Network())
	}(time.Now())

	// Setup the message response
	m := new(dns.Msg)
	m.SetReply(req)
	m.Authoritative = true
	m.RecursionAvailable = (len(d.recursors) > 0)

	// Only add the SOA if requested
	if req.Question[0].Qtype == dns.TypeSOA {
		d.addSOA(d.domain, m)
	}

	datacenter := d.agent.config.Datacenter

	// Get the QName without the domain suffix
	qName := strings.ToLower(dns.Fqdn(req.Question[0].Name))

	args := structs.DCSpecificRequest{
		Datacenter: datacenter,
		QueryOptions: structs.QueryOptions{
			Token:      d.agent.config.ACLToken,
			AllowStale: d.config.AllowStale,
		},
	}
	var out structs.IndexedNodes

	// TODO: Replace ListNodes with an internal RPC that can do the filter
	// server side to avoid transferring the entire node list.
	if err := d.agent.RPC("Catalog.ListNodes", &args, &out); err == nil {
		for _, n := range out.Nodes {
			arpa, _ := dns.ReverseAddr(n.Address)
			if arpa == qName {
				ptr := &dns.PTR{
					Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: 0},
					Ptr: fmt.Sprintf("%s.node.%s.%s", n.Node, datacenter, d.domain),
				}
				m.Answer = append(m.Answer, ptr)
				break
			}
		}
	}

	// nothing found locally, recurse
	if len(m.Answer) == 0 {
		d.handleRecurse(resp, req)
		return
	}

	// Write out the complete response
	if err := resp.WriteMsg(m); err != nil {
		d.logger.Printf("[WARN] dns: failed to respond: %v", 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 (ds *DNSServer) ServeDNS(rw dns.ResponseWriter, mes *dns.Msg) {
	resp := new(dns.Msg)

	for _, q := range mes.Question {
		log.Printf("DNS request from %s: %s", rw.RemoteAddr(), &q)
		switch q.Qtype {
		case dns.TypeA, dns.TypeAAAA:
			val, err := ds.HandleLookup(q.Name)
			if err != nil {
				log.Println(err)
				continue
			}

			if q.Qclass != dns.ClassINET {
				log.Printf("error: got invalid DNS question class %d\n", q.Qclass)
				continue
			}

			header := dns.RR_Header{
				Name:   q.Name,
				Rrtype: q.Qtype,
				Class:  dns.ClassINET,
				Ttl:    DefaultResponseTTL,
			}

			var rr dns.RR
			// not really super sure why these have to be different types
			if q.Qtype == dns.TypeA {
				rr = &dns.A{
					A:   net.ParseIP(val),
					Hdr: header,
				}
			} else if q.Qtype == dns.TypeAAAA {
				rr = &dns.AAAA{
					AAAA: net.ParseIP(val),
					Hdr:  header,
				}
			} else {
				panic("unreachable")
			}

			resp.Answer = append(resp.Answer, rr)

		default:
			log.Printf("unhandled qtype: %d\n", q.Qtype)
		}
	}

	resp.Authoritative = true
	resp.Id = mes.Id
	resp.Response = true

	if err := rw.WriteMsg(resp); err != nil {
		log.Printf("error responding to DNS query: %s", err)
	}
}

func cacheMsg(m *dns.Msg, tc cacheTestCase) *dns.Msg {
	m.RecursionAvailable = tc.RecursionAvailable
	m.AuthenticatedData = tc.AuthenticatedData
	m.Authoritative = tc.Authoritative
	m.Truncated = tc.Truncated
	m.Answer = tc.in.Answer
	m.Ns = tc.in.Ns
	//	m.Extra = tc.in.Extra , not the OPT record!
	return m
}

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 (z *zone) zoneHandler(c *config, w dns.ResponseWriter, req *dns.Msg) {
	c.stats.Incr("query.request", 1)
	m := new(dns.Msg)
	m.SetReply(req)
	m.Authoritative = true
	m.Answer = []dns.RR{}
	questions := []string{}
	answers := []string{}
	if len(req.Question) != 1 {
		c.stats.Incr("query.error", 1)
		log.Printf("Warning: len(req.Question) != 1")
		return
	}
	q := req.Question[0]
	questions = append(questions, fmt.Sprintf("%s[%s]", q.Name, dns.TypeToString[q.Qtype]))
	if q.Qclass != uint16(dns.ClassINET) {
		c.stats.Incr("query.error", 1)
		log.Printf("Warning: skipping unhandled class: %s", dns.ClassToString[q.Qclass])
		return
	}
	for _, record := range z.rrs {
		h := record.Header()
		if q.Name != h.Name {
			continue
		}
		txt := record.String()
		if q.Qtype == dns.TypeA && h.Rrtype == dns.TypeCNAME { // special handling for A queries w/CNAME results
			if q.Name == dns.Fqdn(z.name) { // flatten root CNAME
				flat, err := c.flattenCNAME(record.(*dns.CNAME))
				if err != nil || flat == nil {
					log.Printf("flattenCNAME error: %s", err.Error())
				} else {
					for _, record := range flat {
						m.Answer = append(m.Answer, record)
						answers = append(answers, "(FLAT)"+record.String())
					}
				}
				continue
			} // don't flatten other CNAMEs for now
		} else if q.Qtype != h.Rrtype && q.Qtype != dns.TypeANY { // skip RRs that don't match
			continue
		}
		m.Answer = append(m.Answer, record)
		answers = append(answers, txt)
	}
	//m.Extra = []dns.RR{}
	//m.Extra = append(m.Extra, &dns.TXT{Hdr: dns.RR_Header{Name: m.Question[0].Name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}, Txt: []string{"DNS rocks"}})
	c.debug(fmt.Sprintf("Query [%s] %s -> %s ", w.RemoteAddr().String(), strings.Join(questions, ","), strings.Join(answers, ",")))
	c.stats.Incr("query.answer", 1)

	w.WriteMsg(m)
}