Golang dns.HandleFailed函數代碼示例

// ProxyDNS returns a handler for a proxy DNS server.
func ProxyDNS(server *app.App) func(w dns.ResponseWriter, req *dns.Msg) {
	return func(w dns.ResponseWriter, req *dns.Msg) {
		if len(req.Question) == 0 {
			dns.HandleFailed(w, req)
			return
		}
		name := req.Question[0].Name
		record, err := models.FindRecordBySubOfFQDN(server.DB, name)
		if err != nil || record.ID == "" {
			dns.HandleFailed(w, req)
			return
		}
		if record.Blacklist {
			dns.HandleFailed(w, req)
			return
		}
		transport := "udp"
		if _, ok := w.RemoteAddr().(*net.TCPAddr); ok {
			transport = "tcp"
		}
		c := &dns.Client{Net: transport}
		resp, _, err := c.Exchange(req, record.HandlerHost+":"+strconv.Itoa(record.HandlerPort))
		if err != nil {
			dns.HandleFailed(w, req)
			return
		}
		if err := w.WriteMsg(resp); err != nil {
			dns.HandleFailed(w, req)
			return
		}
	}
}

func proxy(addr string, w dns.ResponseWriter, req *dns.Msg) {
	transport := "udp"
	if _, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		transport = "tcp"
	}
	if isTransfer(req) {
		if transport != "tcp" {
			dns.HandleFailed(w, req)
			return
		}
		t := new(dns.Transfer)
		c, err := t.In(req, addr)
		if err != nil {
			dns.HandleFailed(w, req)
			return
		}
		if err = t.Out(w, req, c); err != nil {
			dns.HandleFailed(w, req)
			return
		}
		return
	}
	c := &dns.Client{Net: transport}
	resp, _, err := c.Exchange(req, addr)
	if err != nil {
		dns.HandleFailed(w, req)
		return
	}
	w.WriteMsg(resp)
}

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 (h *Handler) handle(proto string, w dns.ResponseWriter, r *dns.Msg) {
	ques := question.NewQuestion(r.Question[0])

	subnet := ""
	if ip, ok := w.RemoteAddr().(*net.UDPAddr); ok {
		subnet = networks.Find(ip.IP)
	}
	if ip, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		subnet = networks.Find(ip.IP)
	}

	if subnet == "" {
		dns.HandleFailed(w, r)
		return
	}

	if ques.IsIpQuery && ques.TopDomain == "vpn" {
		msg, err := h.reslvr.LookupUser(proto, ques, subnet, r)
		if err != nil {
			dns.HandleFailed(w, r)
			return
		}
		w.WriteMsg(msg)
	} else {
		servers := database.DnsServers[subnet]
		res, err := h.reslvr.Lookup(proto, servers, r)
		if err != nil {
			dns.HandleFailed(w, r)
			return
		}

		w.WriteMsg(res)
	}
}

// NewServer creates a new Server with the given options.
func NewServer(o Options) (*Server, error) {
	if err := o.validate(); err != nil {
		return nil, err
	}

	s := Server{
		c: &dns.Client{},
		s: &dns.Server{
			Net:  o.Net,
			Addr: o.Bind,
		},
		white:   o.Whitelist != "",
		hosts:   hosts{},
		hostsRX: hostsRX{},

		privateHosts:   map[string]struct{}{},
		privateHostsRX: map[string]*regexp.Regexp{},
	}

	hostListPath := o.Whitelist
	if hostListPath == "" {
		hostListPath = o.Blacklist
	}
	s.hostsFile.path = hostListPath
	if err := s.loadHostEntries(); err != nil {
		return nil, err
	}
	if o.Poll != 0 {
		go s.monitorHostEntries(o.Poll)
	}
	s.s.Handler = dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
		// If no upstream proxy is present, drop the query:
		if len(o.Resolve) == 0 {
			dns.HandleFailed(w, r)
			return
		}

		// Filter Questions:
		if r.Question = s.filter(r.Question); len(r.Question) == 0 {
			w.WriteMsg(r)
			return
		}

		// Proxy Query:
		for _, addr := range o.Resolve {
			in, _, err := s.c.Exchange(r, addr)
			if err != nil {
				continue
			}
			w.WriteMsg(in)
			return
		}
		dns.HandleFailed(w, r)
	})
	return &s, nil
}

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)
}

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

	network := "udp"
	if _, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		network = "tcp"
	}

	c := &dns.Client{Net: network}
	var r *dns.Msg
	var err error
	for _, recursor := range s.recursors {

		if recursor == "" {
			log.Printf("Found empty recursor")
			continue
		}

		log.Printf("Forwarding request to external recursor for: %s", req.Question[0].Name)

		r, _, err = c.Exchange(req, recursor)
		if err == nil {
			if err := w.WriteMsg(r); err != nil {
				log.Printf("DNS lookup failed %v", err)
			}
			return
		}
	}

	dns.HandleFailed(w, req)
}

func (h *GODNSHandler) do(Net string, w dns.ResponseWriter, req *dns.Msg) {

	q := req.Question[0]
	Q := Question{UnFqdn(q.Name), dns.TypeToString[q.Qtype], dns.ClassToString[q.Qclass]}

	Debug("Question:　%s", Q.String())

	// Query hosts
	if settings.Hosts.Enable && h.isIPQuery(q) {
		if ip, ok := h.hosts.Get(Q.qname); ok {
			m := new(dns.Msg)
			m.SetReply(req)
			rr_header := dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: settings.Hosts.TTL}
			a := &dns.A{rr_header, net.ParseIP(ip)}
			m.Answer = append(m.Answer, a)
			w.WriteMsg(m)
			Debug("%s found in hosts", Q.qname)
			return
		}

	}

	// Only query cache when qtype == 'A' , qclass == 'IN'
	key := KeyGen(Q)
	if h.isIPQuery(q) {
		mesg, err := h.cache.Get(key)
		if err != nil {
			Debug("%s didn't hit cache: %s", Q.String(), err)
		} else {
			Debug("%s hit cache", Q.String())
			mesg.Id = req.Id
			w.WriteMsg(mesg)
			return
		}

	}

	mesg, err := h.resolver.Lookup(Net, req)

	if err != nil {
		Debug("%s", err)
		dns.HandleFailed(w, req)
		return
	}

	w.WriteMsg(mesg)

	if h.isIPQuery(q) {
		err = h.cache.Set(key, mesg)

		if err != nil {
			Debug("Set %s cache failed: %s", Q.String(), err.Error())
		}

		Debug("Insert %s into cache", Q.String())
	}

}

func (s *Server) recurse(w dns.ResponseWriter, req *dns.Msg) {
	if s.recurseTo == "" {
		dns.HandleFailed(w, req)
		return
	}
	c := new(dns.Client)
	in, _, err := c.Exchange(req, s.recurseTo)
	if err == nil {
		if in.MsgHdr.Truncated {
			c.Net = "tcp"
			in, _, err = c.Exchange(req, s.recurseTo)
		}
		w.WriteMsg(in)
		return
	}
	log.Warnf("Recursive error: %+v", err)
	dns.HandleFailed(w, req)
}

func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
	kv := llog.KV{}
	// Can be nil during testing
	if raddr := w.RemoteAddr(); raddr != nil {
		kv["srcAddr"] = raddr.String()
	}

	if err := validateRequest(r); err != nil {
		kv["err"] = err
		llog.Warn("invalid request", kv)
		sendFormatError(w, r)
		return
	}

	start := time.Now()
	kv["question"] = r.Question[0].Name
	kv["questionType"] = r.Question[0].Qtype
	llog.Info("handling request", kv)

	rr := NewReq{r, make(chan *dns.Msg)}
	newCh <- rr
	m := <-rr.ReplyCh

	kv["ms"] = int64(time.Since(start).Nanoseconds() / 1e6)

	if m == nil {
		llog.Warn("error handling request", kv)
		dns.HandleFailed(w, r)
		return
	}

	//we need to make sure the sent ID matches the replied one
	//it might be different if we combined in-flight messages
	//copy the struct so we don't affect anything else handling this
	m2 := *m
	m2.Id = r.Id
	m = &m2

	//we always want to compress since there's no downsides afaik
	m.Compress = true

	kv["rcode"], _ = dns.RcodeToString[m.Rcode]
	if len(m.Answer) > 0 {
		kv["answer"] = m.Answer[0]
		kv["answerCnt"] = len(m.Answer)
	}
	kv["len"] = m.Len()
	llog.Info("responding to request", kv)

	err := w.WriteMsg(m)
	if err != nil {
		kv["err"] = err
		llog.Warn("error writing response", kv)
		//no need to handle HandleFailed here because we cannot write
	}
}

func sendTruncated(w dns.ResponseWriter, msgHdr dns.MsgHdr) {
	emptyResp := new(dns.Msg)
	emptyResp.MsgHdr = msgHdr
	emptyResp.Response = true
	if _, isTCP := w.RemoteAddr().(*net.TCPAddr); isTCP {
		dns.HandleFailed(w, emptyResp)
		return
	}
	emptyResp.Truncated = true
	w.WriteMsg(emptyResp)
}

func route(w dns.ResponseWriter, req *dns.Msg) {
	if len(req.Question) == 0 || !allowed(w, req) {
		dns.HandleFailed(w, req)
		return
	}
	for name, addr := range routes {
		if strings.HasSuffix(req.Question[0].Name, name) {
			proxy(addr, w, req)
			return
		}
	}
	proxy(*defaultServer, w, req)
}

func serve(w dns.ResponseWriter, req *dns.Msg) {
	var resp dns.Msg
	var err error
	key := msgKey(req)
	cacheLock.Lock()
	cached, ok := cache[key]
	// cached value will not change until return because of SingleInflight
	cacheLock.Unlock()
	if !ok {
		log.Printf("%04X┐%s\n", req.Id, key)
		for attempt := 1; attempt <= queryAttempts; attempt++ {
			cached, _, err = dnsclient.Exchange(req, *flUpstream)
			if err != nil {
				cacheLock.Lock()
				_, ok = cache[key]
				cacheLock.Unlock()
				if ok {
					// concurrent exchange succeeded
					err = nil
					break
				}
				sep := "·"
				if attempt == queryAttempts {
					sep = "╳"
				}
				log.Printf("%04X%s%s: [%d/%d] %v\n", req.Id, sep, key,
					attempt, queryAttempts, err)
			}
		}
		if err != nil {
			dns.HandleFailed(w, req)
			return
		}
		cacheLock.Lock()
		cached2, ok := cache[key]
		if ok {
			// concurrent exchange has already updated the cache
			cached = cached2
			log.Printf("%04X┴%04X\n", req.Id, cached.Id)
		} else {
			cache[key] = cached
			log.Printf("%04X└%s = %s\n", req.Id, key, answersSummary(cached))
		}
		cacheLock.Unlock()
	}
	resp = *cached
	resp.Id = req.Id
	err = w.WriteMsg(&resp)
	eprint(err)
}

func (s *Server) do(Net string, w dns.ResponseWriter, req *dns.Msg) {
	if len(req.Question) != 1 {
		dns.HandleFailed(w, req)
		return
	}
	zone, name := s.zones.match(req.Question[0].Name, req.Question[0].Qtype)
	if zone == nil {
		s.recurse(w, req)
		return
	}

	s.zones.Lock()
	defer s.zones.Unlock()

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

	var answerKnown bool
	dnsreq := dns.RR_Header{Name: req.Question[0].Name, Rrtype: req.Question[0].Qtype, Class: req.Question[0].Qclass}
	for _, r := range (*zone)[dnsreq] {
		m.Answer = append(m.Answer, r)
		answerKnown = true
	}
	// TODO: more logs here
	s.roundRobin(zone, dnsreq)

	if !answerKnown && s.recurseTo != "" {
		s.recurse(w, req)
		return
	}

	// Add Authority section
	for _, r := range (*zone)[dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET}] {
		m.Ns = append(m.Ns, r)
		// Resolve Authority if possible and serve as Extra
		for _, r := range (*zone)[dns.RR_Header{Name: r.(*dns.NS).Ns, Rrtype: dns.TypeA, Class: dns.ClassINET}] {
			m.Extra = append(m.Extra, r)
		}
		for _, r := range (*zone)[dns.RR_Header{Name: r.(*dns.NS).Ns, Rrtype: dns.TypeAAAA, Class: dns.ClassINET}] {
			m.Extra = append(m.Extra, r)
		}
	}

	m.Authoritative = true
	w.WriteMsg(m)
}

func (h *GODNSHandler) do(Net string, w dns.ResponseWriter, req *dns.Msg) {
	q := req.Question[0]
	Q := Question{UnFqdn(q.Name), dns.TypeToString[q.Qtype], dns.ClassToString[q.Qclass]}

	fmt.Println("DNS Lookup ", Q.String())

	IPQuery := h.isIPQuery(q)
	key := fmt.Sprintf("%s-%s", h.GetHour(), Q.String())
	fmt.Println("Cache key: ", key)
	if IPQuery > 0 {
		mesg, ok := h.Cache.Get(key)
		if ok == true {
			fmt.Println("Hit cache", Q.String())
			rmesg := mesg.(*dns.Msg)
			rmesg.Id = req.Id
			w.WriteMsg(BuildDNSMsg(rmesg))
			return
		}
	}

	mesg, err := h.resolver.Lookup(Net, req)

	if err != nil {
		mesg, err = h.resolver.Lookup(Net, req) // try to lookup again
		if err != nil {
			fmt.Println("Resolve query error ", err)
			dns.HandleFailed(w, req)
		}
		return
	}

	w.WriteMsg(BuildDNSMsg(mesg))

	if IPQuery > 0 && len(mesg.Answer) > 0 {
		h.Cache.Add(key, mesg)
		fmt.Println("Insert into cache", Q.String())
	}
}