Golang Msg.SetRcode方法代碼示例

// ServeDNS resolution.
func (h *RandomUpstream) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
	ns := h.upstream[rand.Intn(len(h.upstream))]
	ns = defaultPort(ns)

	for _, q := range r.Question {
		log.Printf("[info] [%v] <== %s %s %v (ns %s)\n", r.Id,
			dns.ClassToString[q.Qclass],
			dns.TypeToString[q.Qtype],
			q.Name,
			ns)
	}

	client := &dns.Client{
		Net: w.RemoteAddr().Network(),
	}

	res, rtt, err := client.Exchange(r, ns)
	if err != nil {
		msg := new(dns.Msg)
		msg.SetRcode(r, dns.RcodeServerFailure)
		w.WriteMsg(msg)
		return
	}

	log.Printf("[info] [%v] ==> %s:", r.Id, rtt)
	for _, a := range res.Answer {
		log.Printf("[info] [%v] ----> %s\n", r.Id, a)
	}

	err = w.WriteMsg(res)
	if err != nil {
		log.Printf("[error] [%v] failed to respond – %s", r.Id, err)
	}
}

// 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)
		}
	}
}

func (s *server) NameError(req *dns.Msg) *dns.Msg {
	m := new(dns.Msg)
	m.SetRcode(req, dns.RcodeNameError)
	m.Ns = []dns.RR{s.NewSOA()}
	m.Ns[0].Header().Ttl = s.config.MinTtl
	return m
}

// nodeLookup is used to handle a node query
func (d *DNSServer) nodeLookup(network, datacenter, node string, req, resp *dns.Msg) {
	// Only handle ANY and A type requests
	qType := req.Question[0].Qtype
	if qType != dns.TypeANY && qType != dns.TypeA {
		return
	}

	// Make an RPC request
	args := structs.NodeSpecificRequest{
		Datacenter: datacenter,
		Node:       node,
	}
	var out structs.IndexedNodeServices
	if err := d.agent.RPC("Catalog.NodeServices", &args, &out); err != nil {
		d.logger.Printf("[ERR] dns: rpc error: %v", err)
		resp.SetRcode(req, dns.RcodeServerFailure)
		return
	}

	// If we have no address, return not found!
	if out.NodeServices == nil {
		resp.SetRcode(req, dns.RcodeNameError)
		return
	}

	// Add the node record
	records := d.formatNodeRecord(&out.NodeServices.Node, req.Question[0].Name, qType)
	if records != nil {
		resp.Answer = append(resp.Answer, records...)
	}
}

func (srv *Server) setupRootZone() {
	dns.HandleFunc(".", func(w dns.ResponseWriter, r *dns.Msg) {
		m := new(dns.Msg)
		m.SetRcode(r, dns.RcodeRefused)
		w.WriteMsg(m)
	})
}

func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
	state := middleware.State{W: w, Req: r}
	for _, rule := range l.Rules {
		if middleware.Name(rule.NameScope).Matches(state.Name()) {
			responseRecorder := middleware.NewResponseRecorder(w)
			rcode, err := l.Next.ServeDNS(ctx, responseRecorder, r)

			if rcode > 0 {
				// There was an error up the chain, but no response has been written yet.
				// The error must be handled here so the log entry will record the response size.
				if l.ErrorFunc != nil {
					l.ErrorFunc(responseRecorder, r, rcode)
				} else {
					rc := middleware.RcodeToString(rcode)

					answer := new(dns.Msg)
					answer.SetRcode(r, rcode)
					state.SizeAndDo(answer)

					metrics.Report(state, metrics.Dropped, rc, answer.Len(), time.Now())
					w.WriteMsg(answer)
				}
				rcode = 0
			}
			rep := middleware.NewReplacer(r, responseRecorder, CommonLogEmptyValue)
			rule.Log.Println(rep.Replace(rule.Format))
			return rcode, err

		}
	}
	return l.Next.ServeDNS(ctx, w, r)
}

func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
	switch {
	case r.IsNotify():
		if *flaglog {
			log.Printf("fks-shield: notify/update")
		}
		fallthrough
	case r.IsUpdate():
		client := new(dns.Client)
		if p, e := client.Exchange(r, *server); e == nil {
			w.WriteMsg(p)
		}
		return
	}
	if p := c.Find(r); p != nil {
		b := []byte{byte(r.MsgHdr.Id >> 8), byte(r.MsgHdr.Id)}
		p = append(b, p...)
		w.Write(p)
		return
	}
	// Cache miss
	client := new(dns.Client)
	if p, e := client.Exchange(r, *server); e == nil {
		// TODO(mg): If r has edns0 and p has not we create a mismatch here
		w.WriteMsg(p)
		c.Insert(p)
		return
	} else {
		log.Printf("fks-shield: failed to get answer " + e.Error())
		m := new(dns.Msg)
		m.SetRcode(r, dns.RcodeServerFailure)
		w.WriteMsg(m)
	}
}

// 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 (s *DNSServer) doHandle(w dns.ResponseWriter, r *dns.Msg) *dns.Msg {
	m := new(dns.Msg)
	m.SetReply(r)

	// Send empty response for empty requests
	if len(r.Question) == 0 {
		m.Ns = s.createSOA()
		return m
	}

	switch r.Question[0].Qtype {
	case dns.TypePTR:
		s.handlePTRRequest(r, m)
	case dns.TypeMX:
		s.handleMXRequest(r, m)
	case dns.TypeA:
		s.handleARequest(r, m)
	case dns.TypeSOA:
		m.Answer = s.createSOA()
	default:
		m.Ns = s.createSOA()
		m.SetRcode(r, dns.RcodeNotImplemented)
	}

	return m
}

func handle(writer dns.ResponseWriter, request *dns.Msg) {
	message := new(dns.Msg)
	message.SetReply(request)
	message.SetRcode(message, dns.RcodeSuccess)
	question := request.Question[0]

	switch request.Opcode {
	case dns.OpcodeNotify:
		log.Println(fmt.Sprintf("Recieved NOTIFY for %s", question.Name))
		message = handle_notify(question, message, writer)
	case dns.OpcodeQuery:
		log.Println(fmt.Sprintf("Recieved QUERY for %s", question.Name))
		message = handle_query(question, message, writer)
	default:
		message = handle_error(message, writer, "REFUSED")
	}

	// Apparently this dns library takes the question out on
	// certain RCodes, like REFUSED, which is not right. So we reinsert it.
	message.Question[0].Name = question.Name
	message.Question[0].Qtype = question.Qtype
	message.Question[0].Qclass = question.Qclass
	message.MsgHdr.Opcode = request.Opcode

	// Send an authoritative answer
	message.MsgHdr.Authoritative = true

	writer.WriteMsg(message)
}

// serviceLookup is used to handle a service query
func (d *DNSServer) serviceLookup(network, datacenter, service, tag string, req, resp *dns.Msg) {
	// Make an RPC request
	args := structs.ServiceSpecificRequest{
		Datacenter:   datacenter,
		ServiceName:  service,
		ServiceTag:   tag,
		TagFilter:    tag != "",
		QueryOptions: structs.QueryOptions{AllowStale: d.config.AllowStale},
	}
	var out structs.IndexedCheckServiceNodes
RPC:
	if err := d.agent.RPC("Health.ServiceNodes", &args, &out); err != nil {
		d.logger.Printf("[ERR] dns: rpc error: %v", err)
		resp.SetRcode(req, dns.RcodeServerFailure)
		return
	}

	// Verify that request is not too stale, redo the request
	if args.AllowStale && out.LastContact > d.config.MaxStale {
		args.AllowStale = false
		d.logger.Printf("[WARN] dns: Query results too stale, re-requesting")
		goto RPC
	}

	// If we have no nodes, return not found!
	if len(out.Nodes) == 0 {
		resp.SetRcode(req, dns.RcodeNameError)
		return
	}

	// Determine the TTL
	var ttl time.Duration
	if d.config.ServiceTTL != nil {
		var ok bool
		ttl, ok = d.config.ServiceTTL[service]
		if !ok {
			ttl = d.config.ServiceTTL["*"]
		}
	}

	// Filter out any service nodes due to health checks
	out.Nodes = d.filterServiceNodes(out.Nodes)

	// Perform a random shuffle
	shuffleServiceNodes(out.Nodes)

	// If the network is not TCP, restrict the number of responses
	if network != "tcp" && len(out.Nodes) > maxServiceResponses {
		out.Nodes = out.Nodes[:maxServiceResponses]
	}

	// Add various responses depending on the request
	qType := req.Question[0].Qtype
	d.serviceNodeRecords(out.Nodes, req, resp, ttl)

	if qType == dns.TypeSRV {
		d.serviceSRVRecords(datacenter, out.Nodes, req, resp, ttl)
	}
}

func formerr(w dns.ResponseWriter, req *dns.Msg) {
	m := new(dns.Msg)
	m.MsgHdr.Opcode = dns.OpcodeUpdate
	if req.IsTsig() != nil {
		m.SetTsig(userFromTsig(req), dns.HmacMD5, 300, time.Now().Unix())
	}
	w.WriteMsg(m.SetRcode(req, dns.RcodeFormatError))
}

// NoData write a nodata response to the client.
func (k Kubernetes) Err(zone string, rcode int, state middleware.State) (int, error) {
	m := new(dns.Msg)
	m.SetRcode(state.Req, rcode)
	m.Ns = []dns.RR{k.SOA(zone, state)}
	state.SizeAndDo(m)
	state.W.WriteMsg(m)
	return rcode, nil
}

func (s *server) NoDataError(m, req *dns.Msg) {
	m.SetRcode(req, dns.RcodeSuccess)
	m.Ns = []dns.RR{s.NewSOA()}
	m.Ns[0].Header().Ttl = s.config.MinTtl

	StatsNoDataCount.Inc(1)
	promErrorCount.WithLabelValues("nodata")
}

func (s *server) NameError(m, req *dns.Msg) {
	m.SetRcode(req, dns.RcodeNameError)
	m.Ns = []dns.RR{s.NewSOA()}
	m.Ns[0].Header().Ttl = s.config.MinTtl

	StatsNameErrorCount.Inc(1)
	promErrorCount.WithLabelValues("nxdomain")
}