Golang Msg.SetReply方法代码示例

func rootZone(w dns.ResponseWriter, req *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(req)
	rr, _ := dns.NewRR(". 0 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2016110600 1800 900 604800 86400")
	m.Ns = []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 createRespMsg(query *dns.Msg) *dns.Msg {
	resp := new(dns.Msg)
	resp.SetReply(query)
	setCommonFlags(resp)

	return resp
}

// 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)
	}
}

// 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)
	}
}

// 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)
}

// Create DNS packet with the config in line with the meta zone
// paper from Vixie
func metazone(w dns.ResponseWriter, req *dns.Msg, c *Config) {
	logPrintf("metazone command")

	// Only called when the class is CHAOS
	// PTR zone.	-> get a list of zone names

	// Top level zone stuff -- list them
	if strings.ToUpper(req.Question[0].Name) == "ZONE." {
		m := new(dns.Msg)
		m.SetReply(req)
		for _, z := range c.Zones {
			ptr, _ := dns.NewRR("zone. 0 CH PTR " + z.Origin)
			m.Answer = append(m.Answer, ptr)
		}
		w.WriteMsg(m)
		return
	}

	// Top level user stuff -- list them
	if strings.ToUpper(req.Question[0].Name) == "USER." {

	}

	// <zone>.ZONE.

	formerr(w, req)
	return
}

func (r *resolver) handleIPQuery(name string, query *dns.Msg, ipType int) (*dns.Msg, error) {
	addr := r.sb.ResolveName(name, ipType)
	if addr == nil {
		return nil, nil
	}

	log.Debugf("Lookup for %s: IP %v", name, addr)

	resp := new(dns.Msg)
	resp.SetReply(query)
	setCommonFlags(resp)

	if len(addr) > 1 {
		addr = shuffleAddr(addr)
	}
	if ipType == netutils.IPv4 {
		for _, ip := range addr {
			rr := new(dns.A)
			rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
			rr.A = ip
			resp.Answer = append(resp.Answer, rr)
		}
	} else {
		for _, ip := range addr {
			rr := new(dns.AAAA)
			rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: respTTL}
			rr.AAAA = ip
			resp.Answer = append(resp.Answer, rr)
		}
	}
	return resp, nil
}

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)
	}
}

func (s *DNS) handleDNSInternal(w dns.ResponseWriter, req *dns.Msg) {

	q := req.Question[0]

	if q.Qtype == dns.TypeA && q.Qclass == dns.ClassINET {
		if record, ok := s.cache.Get(q.Name); ok {

			log.Printf("Found internal record for %s", q.Name)

			m := new(dns.Msg)
			m.SetReply(req)
			rr_header := dns.RR_Header{
				Name:   q.Name,
				Rrtype: dns.TypeA,
				Class:  dns.ClassINET,
				Ttl:    0,
			}
			a := &dns.A{rr_header, net.ParseIP(record.ip)}
			m.Answer = append(m.Answer, a)
			w.WriteMsg(m)

			return
		}

		log.Printf("No internal record found for %s", q.Name)
		dns.HandleFailed(w, req)
	}

	log.Printf("Only handling type A requests, skipping")
	dns.HandleFailed(w, req)
}

func handleDnsRequest(w dns.ResponseWriter, r *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(r)
	records := make([]dns.RR, 0)
	q := r.Question[0]

	if q.Qtype == dns.TypeA && strings.HasSuffix(q.Name, ".docker.") {
		docker, _ := dockerclient.NewDockerClient("unix:///var/run/docker.sock", &tls.Config{})
		name := strings.SplitN(q.Name, ".", 2)[0]
		containers, err := docker.ListContainers(false, false, fmt.Sprintf("{\"name\":[\"%s\"]}", name))
		if err != nil {
			log.Fatal(err)
		}
		for _, c := range containers {
			info, _ := docker.InspectContainer(c.Id)
			log.Printf("Container %s[%6s] has ip %s\n", name, info.Id, info.NetworkSettings.IPAddress)
			records = append(records,
				&dns.A{
					Hdr: dns.RR_Header{
						Name:   q.Name,
						Rrtype: dns.TypeA,
						Class:  dns.ClassINET,
						Ttl:    60},
					A: net.ParseIP(info.NetworkSettings.IPAddress),
				})
		}
	}

	m.Answer = append(m.Answer, records...)
	defer w.WriteMsg(m)
}

func (s *DNS) handleReverseDNSLookup(w dns.ResponseWriter, req *dns.Msg) {

	q := req.Question[0]

	if q.Qtype == dns.TypePTR && q.Qclass == dns.ClassINET {

		if record, ok := s.cache.Get(q.Name); ok {

			log.Printf("Found internal record for %s", q.Name)

			m := new(dns.Msg)
			m.SetReply(req)
			rr_header := dns.RR_Header{
				Name:   q.Name,
				Rrtype: dns.TypePTR,
				Class:  dns.ClassINET,
				Ttl:    0,
			}

			a := &dns.PTR{rr_header, record.fqdn}
			m.Answer = append(m.Answer, a)
			w.WriteMsg(m)

			return

		}

		log.Printf("Forwarding request to external recursor for: %s", q.Name)

		// Forward the request
		s.handleDNSExternal(w, req)
	}

	dns.HandleFailed(w, req)
}

// 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 handlerToAnswer(w dns.ResponseWriter, r *dns.Msg) {
	db, err := sql.Open("mysql", "inserter:[email protected]/dnsServerCache") //Handler for database
	if err != nil {
		panic(err.Error()) // Just for example purpose. You should use proper error handling instead of panic
	}

	answer := new(dns.Msg) //Set answer to client
	answer.SetReply(r)     //Set reply flag and start collecting data for reply
	var answersAll []dns.RR
	answersAll = dbRespond(db, r.Question[0].String())
	if len(answersAll) != 0 {
		for _, answers := range answersAll {
			answer.Answer = append(answer.Answer, answers)
		}
	} else {
		client := new(dns.Client)
		var err1 error
		config, _ := dns.ClientConfigFromFile("/etc/resolv.conf")
		answer, _, err1 = client.Exchange(r, config.Servers[0]+":"+config.Port)
		if err1 != nil {
			panic(err1.Error())
		}
		if r.Rcode != dns.RcodeSuccess {
			return
		}
		go dbWriter(answer.Answer, db, r.Question[0].String())
	}
	w.WriteMsg(answer)
}

func (manager *DnsManager) dnsHandler(w dns.ResponseWriter, req *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(req)

	name := req.Question[0].Name
	name = strings.TrimSuffix(name, "."+manager.BaseName)

	manager.dbMutex.Lock()
	entry, ok := manager.db[name]
	manager.dbMutex.Unlock()

	if ok {
		switch req.Question[0].Qtype {
		case dns.TypeSRV:
			m.Answer = manager.makeAllSRV(entry)
		case dns.TypeA:
			m.Answer = manager.makeAllA(entry)
			if manager.PushSRV {
				m.Extra = manager.makeAllSRV(entry)
			}
		}
	}

	w.WriteMsg(m)
}