Golang Msg.Extra方法代碼示例

func handleReflect(w dns.ResponseWriter, r *dns.Msg) {
	var (
		v4  bool
		rr  dns.RR
		str string
		a   net.IP
	)
	// TC must be done here
	m := new(dns.Msg)
	m.SetReply(r)
	m.Compress = *compress
	if ip, ok := w.RemoteAddr().(*net.UDPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (udp)"
		a = ip.IP
		v4 = a.To4() != nil
	}
	if ip, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (tcp)"
		a = ip.IP
		v4 = a.To4() != nil
	}

	if v4 {
		rr = new(dns.RR_A)
		rr.(*dns.RR_A).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_A).A = a.To4()
	} else {
		rr = new(dns.RR_AAAA)
		rr.(*dns.RR_AAAA).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_AAAA).AAAA = a
	}

	t := new(dns.RR_TXT)
	t.Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
	t.Txt = []string{str}

	switch r.Question[0].Qtype {
	case dns.TypeTXT:
		m.Answer = append(m.Answer, t)
		m.Extra = append(m.Extra, rr)
	default:
		fallthrough
	case dns.TypeAAAA, dns.TypeA:
		m.Answer = append(m.Answer, rr)
		m.Extra = append(m.Extra, t)
	}

	if r.IsTsig() {
		if w.TsigStatus() == nil {
			m.SetTsig(r.Extra[len(r.Extra)-1].(*dns.RR_TSIG).Hdr.Name, dns.HmacMD5, 300, r.MsgHdr.Id, time.Now().Unix())
		} else {
			println("Status", w.TsigStatus().Error())
		}
	}
	if *printf {
		fmt.Printf("%v\n", m.String())
	}
	w.Write(m)
}

func handleQuery(w dns.ResponseWriter, req *dns.Msg) {
	var dnssec bool
	m := new(dns.Msg)
	if req.Question[0].Qclass != dns.ClassINET {
		m.SetRcode(req, dns.RcodeServerFailure)
		send(w, m)
		return
	}
	m.SetReply(req)
	m.Ns = ns
	m.Extra = make([]dns.RR, 1)
	m.Extra[0] = spamIN

	// Check DNSSEC OK
	for _, v := range req.Extra {
		if o, ok := v.(*dns.RR_OPT); ok {
			if dnssec = o.Do(); dnssec {
				m.Extra = append(m.Extra, o)
				m.Ns = nsDNSSEC
				break
			}
		}
	}

	//m.Answer = make([]dns.RR, 0)
	s, _ := zone.LookupQuestion(req.Question[0])
	if s == nil {
		// Authority section should only contain the SOA record for NXDOMAIN
		m.Ns = m.Ns[:1]
		m.Ns[0] = soa
		m.MsgHdr.Rcode = dns.RcodeNameError
		send(w, m)
		// Lookup the previous name in the Nxt list for this zone
		// and insert the nsec/nsec3 from that. Also give the nsec
		// that proofs there is no wildcard
		return
	}

	// TODO CNAME
	//cname:
	switch req.Question[0].Qtype {
	case dns.TypeRRSIG:
		m.Answer = s.RRsigs
	case dns.TypeNSEC, dns.TypeNSEC3:
		m.Answer = []dns.RR{s.Nxt}
	default:
		m.Answer = s.RRs
	}
	if dnssec && req.Question[0].Qtype != dns.TypeRRSIG && len(s.RRsigs) > 0 {
		for _, r := range s.RRsigs {
			m.Answer = append(m.Answer, r)
		}
	}
	if *debug {
		println(m.Question[0].String())
	}
	send(w, m)
}

func handleQueryCHAOS(w dns.ResponseWriter, req *dns.Msg) {
	m := new(dns.Msg)
	qname := strings.ToLower(req.Question[0].Name)
	qtype := req.Question[0].Qtype
	qclass := req.Question[0].Qclass

	m.Extra = make([]dns.RR, 1)
	m.Extra[0] = spamCH

	if qclass != dns.ClassCHAOS {
		m.SetRcode(req, dns.RcodeServerFailure)
		send(w, m)
		return
	}

	if (qname == "version.bind." || qname == "id.server.") && qtype == dns.TypeTXT {
		m.SetReply(req)
		m.Answer = make([]dns.RR, 1)
		m.Answer[0] = &dns.RR_TXT{Hdr: dns.RR_Header{Name: qname,
			Rrtype: qtype, Class: qclass}, Txt: "NS 0.0.1"}
		send(w, m)
		return
	}
	if (qname == "authors.bind." || qname == "authors.server.") && qtype == dns.TypeTXT {
		m.SetReply(req)
		m.Answer = make([]dns.RR, 1)
		m.Answer[0] = &dns.RR_TXT{Hdr: dns.RR_Header{Name: qname,
			Rrtype: qtype, Class: qclass}, Txt: "Miek Gieben"}
		send(w, m)
		return
	}
	m.SetRcode(req, dns.RcodeServerFailure)
	send(w, m)
	return
}

func newConnMsg(qname, nameserver string, attempts int, qtype, qclass uint16, aa, ad, cd, rd, dnssec, nsid bool) (*dns.Conn, *dns.Msg) {
	d := new(dns.Conn)
	d.RemoteAddr = nameserver
	d.Attempts = attempts

	m := new(dns.Msg)
	m.MsgHdr.Authoritative = aa
	m.MsgHdr.AuthenticatedData = ad
	m.MsgHdr.CheckingDisabled = cd
	m.MsgHdr.RecursionDesired = rd
	m.Question = make([]dns.Question, 1)
	if dnssec || nsid {
		opt := new(dns.RR_OPT)
		opt.SetDo()
		opt.SetVersion(0)
		opt.SetUDPSize(dns.DefaultMsgSize)
		if nsid {
			opt.SetNsid("")
		}
		m.Extra = make([]dns.RR, 1)
		m.Extra[0] = opt
	}
	m.Question[0] = dns.Question{qname, qtype, qclass}
	m.Id = dns.Id()
	return d, m
}

func handleReflect(w dns.ResponseWriter, r *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(r)
	m.Extra = make([]dns.RR, 1)
	m.Answer = make([]dns.RR, 1)
	var (
		v4  bool
		rr  dns.RR
		str string
		a   net.IP
	)

	if ip, ok := w.RemoteAddr().(*net.UDPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (udp)"
		a = ip.IP
		v4 = a.To4() != nil
	}
	if ip, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (tcp)"
		a = ip.IP
		v4 = a.To4() != nil
	}

	if v4 {
		rr = new(dns.RR_A)
		rr.(*dns.RR_A).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_A).A = a
	} else {
		rr = new(dns.RR_AAAA)
		rr.(*dns.RR_AAAA).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_AAAA).AAAA = a
	}

	t := new(dns.RR_TXT)
	t.Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
	t.Txt = str
	m.Extra[0] = t
	m.Answer[0] = rr

	b, ok := m.Pack()
	if !ok {
		return
	}
	w.Write(b)
}

func reply(c *dns.Conn, in *dns.Msg) []byte {
	m := new(dns.Msg)
	m.SetReply(in)

	m.Question = make([]dns.Question, 1)
	m.Answer = make([]dns.RR, 1)
	m.Extra = make([]dns.RR, 1)

	// Copy the question.
	m.Question[0] = in.Question[0]

	// Some foo to check if we are called through ip6 or ip4.
	// We add the correct reply RR.
	var ad net.IP
	if c.UDP != nil {
		ad = c.Addr.(*net.UDPAddr).IP
	} else {
		ad = c.Addr.(*net.TCPAddr).IP
	}

	if ad.To4() != nil {
		r := new(dns.RR_A)
		r.Hdr = dns.RR_Header{Name: "whoami.miek.nl.", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
		r.A = ad
		m.Answer[0] = r
	} else {
		r := new(dns.RR_AAAA)
		r.Hdr = dns.RR_Header{Name: "whoami.miek.nl.", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 0}
		r.AAAA = ad
		m.Answer[0] = r
	}

	t := new(dns.RR_TXT)
	t.Hdr = dns.RR_Header{Name: "whoami.miek.nl.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
	if c.TCP != nil {
		t.Txt = "Port: " + strconv.Itoa(c.Port) + " (tcp)"
	} else {
		t.Txt = "Port: " + strconv.Itoa(c.Port) + " (udp)"
	}
	m.Extra[0] = t

	b, _ := m.Pack()
	return b
}

func main() {
	conf, err := dns.ClientConfigFromFile("/etc/resolv.conf")
	if len(os.Args) != 2 || err != nil {
		fmt.Printf("%s DOMAIN\n", os.Args[0])
		os.Exit(1)
	}
	m := new(dns.Msg)
	m.SetQuestion(os.Args[1], dns.TypeDNSKEY)

	// Set EDNS0's Do bit
	e := new(dns.RR_OPT)
	e.Hdr.Name = "."
	e.Hdr.Rrtype = dns.TypeOPT
	e.SetUDPSize(2048)
	e.SetDo()
	m.Extra = append(m.Extra, e)

	c := dns.NewClient()
	r := c.Exchange(m, conf.Servers[0])
	if r == nil {
		fmt.Printf("*** no answer received for %s\n", os.Args[1])
		os.Exit(1)
	}

	if r.Rcode != dns.RcodeSuccess {
		fmt.Printf(" *** invalid answer name %s after DNSKEY query for %s\n", os.Args[1], os.Args[1])
		os.Exit(1)
	}
	// Stuff must be in the answer section, check len(r.Answer)
	for _, k := range r.Answer {
		// Foreach key would need to provide a DS records, both sha1 and sha256
		if key, ok := k.(*dns.RR_DNSKEY); ok {
			key.Hdr.Ttl = 0
			ds := key.ToDS(dns.SHA1)
			fmt.Printf("%v\n", ds)
			ds = key.ToDS(dns.SHA256)
			fmt.Printf("%v\n", ds)
			ds = key.ToDS(dns.SHA384)
			fmt.Printf("%v\n", ds)
		}
	}
}

//.........這裏部分代碼省略.........

	if *dnssec || *nsid || *client != "" {
		o := new(dns.RR_OPT)
		o.Hdr.Name = "."
		o.Hdr.Rrtype = dns.TypeOPT
		if *dnssec {
			o.SetDo()
			o.SetUDPSize(dns.DefaultMsgSize)
		}
		if *nsid {
			e := new(dns.EDNS0_NSID)
			e.Code = dns.EDNS0NSID
			o.Option = append(o.Option, e)
			// NSD will not return nsid when the udp message size is too small
			o.SetUDPSize(dns.DefaultMsgSize)
		}
		if *client != "" {
			e := new(dns.EDNS0_SUBNET)
			e.Code = dns.EDNS0SUBNET
			e.SourceScope = 0
			e.Address = net.ParseIP(*client)
			if e.Address == nil {
				fmt.Fprintf(os.Stderr, "Failure to parse IP address: %s\n", *client)
				return
			}
			e.Family = 1 // IP4
			e.SourceNetmask = net.IPv4len * 8
			if e.Address.To4() == nil {
				e.Family = 2 // IP6
				e.SourceNetmask = net.IPv6len * 8
			}
			o.Option = append(o.Option, e)
		}
		m.Extra = append(m.Extra, o)
	}

	for i, v := range qname {
		m.Question[0] = dns.Question{v, qtype, qclass}
		m.Id = dns.Id()
		if *query {
			fmt.Printf("%s", m.String())
			fmt.Printf("\n;; size: %d bytes\n\n", m.Len())
		}
		// Add tsig
		if *tsig != "" {
			if algo, name, secret, ok := tsigKeyParse(*tsig); ok {
				m.SetTsig(name, algo, 300, time.Now().Unix())
				c.TsigSecret = map[string]string{name: secret}
			} else {
				fmt.Fprintf(os.Stderr, "tsig key data error\n")
				return
			}
		}
		c.DoRtt(m, nameserver, nil, func(m, r *dns.Msg, rtt time.Duration, e error, data interface{}) {
			defer func() {
				if i == len(qname)-1 {
					os.Exit(0)
				}
			}()
		Redo:
			if r == nil {
				return
			}
			if r.Rcode != dns.RcodeSuccess {
				return
			}

//.........這裏部分代碼省略.........
		if k, ok := dns.Str_rr[strings.ToUpper(flag.Arg(i))]; ok {
			qtype = k
			continue Flags
		}
		// If it looks like a class, it is a class
		if k, ok := dns.Str_class[strings.ToUpper(flag.Arg(i))]; ok {
			qclass = k
			continue Flags
		}
		// If it starts with TYPExxx it is unknown rr
		if strings.HasPrefix(flag.Arg(i), "TYPE") {
			i, e := strconv.Atoi(string([]byte(flag.Arg(i))[4:]))
			if e == nil {
				qtype = uint16(i)
				continue Flags
			}
		}

		// Anything else is a qname
		qname = append(qname, flag.Arg(i))
	}
	if len(qname) == 0 {
		qname = make([]string, 1)
		qname[0] = "."
		qtype = dns.TypeNS
	}
	if qtype == 0 {
		qtype = dns.TypeA
	}

	nameserver = string([]byte(nameserver)[1:]) // chop off @
	nameserver += ":" + strconv.Itoa(*port)

	// ipv6 todo
	// We use the async query handling, just to show how
	// it is to be used.
	dns.HandleQueryFunc(".", q)
	dns.ListenAndQuery(nil, nil)
	c := dns.NewClient()
	if *tcp {
		c.Net = "tcp"
	}

	m := new(dns.Msg)
	m.MsgHdr.Authoritative = *aa
	m.MsgHdr.AuthenticatedData = *ad
	m.MsgHdr.CheckingDisabled = *cd
	m.MsgHdr.RecursionDesired = *rd
	m.Question = make([]dns.Question, 1)
	if *dnssec || *nsid {
		o := new(dns.RR_OPT)
		o.Hdr.Name = "."
		o.Hdr.Rrtype = dns.TypeOPT
		if *dnssec {
			o.SetDo()
			o.SetUDPSize(dns.DefaultMsgSize)
		}
		if *nsid {
			o.SetNsid("")
		}
		m.Extra = append(m.Extra, o)
	}

	for _, v := range qname {
		m.Question[0] = dns.Question{v, qtype, qclass}
		m.Id = dns.Id()
		if *query {
			fmt.Printf("%s\n", m.String())
		}
		c.Do(m, nameserver)
	}

	i := 0
forever:
	for {
		select {
		case r := <-dns.DefaultReplyChan:
			if r.Reply != nil {
				if r.Reply.Rcode == dns.RcodeSuccess {
					if r.Request.Id != r.Reply.Id {
						fmt.Printf("Id mismatch\n")
					}
				}
				if *check {
					sigCheck(r.Reply, nameserver, *tcp)
					nsecCheck(r.Reply)
				}
				if *short {
					r.Reply = shortMsg(r.Reply)
				}

				fmt.Printf("%v", r.Reply)
			}
			i++
			if i == len(qname) {
				break forever
			}
		}
	}
}

func main() {
	var dnssec *bool = flag.Bool("dnssec", false, "request DNSSEC records")
	var query *bool = flag.Bool("question", false, "show question")
	var short *bool = flag.Bool("short", false, "abbriate long DNSKEY and RRSIG RRs")
	var aa *bool = flag.Bool("aa", false, "set AA flag in query")
	var ad *bool = flag.Bool("ad", false, "set AD flag in query")
	var cd *bool = flag.Bool("cd", false, "set CD flag in query")
	var rd *bool = flag.Bool("rd", true, "unset RD flag in query")
	var tcp *bool = flag.Bool("tcp", false, "TCP mode")
	var nsid *bool = flag.Bool("nsid", false, "ask for NSID")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage: %s [@server(:port)] [qtype] [qclass] [name ...]\n", os.Args[0])
		flag.PrintDefaults()
	}

	// Need to think about it... Config
	conf, _ := dns.ClientConfigFromFile("/etc/resolv.conf")
	nameserver := "@" + conf.Servers[0]
	qtype := uint16(0)
	qclass := uint16(dns.ClassINET) // Default qclass
	var qname []string

	flag.Parse()

Flags:
	for i := 0; i < flag.NArg(); i++ {
		// If it starts with @ it is a nameserver
		if flag.Arg(i)[0] == '@' {
			nameserver = flag.Arg(i)
			continue Flags
		}
		// First class, then type, to make ANY queries possible
		// And if it looks like type, it is a type
		for k, v := range dns.Rr_str {
			if v == strings.ToUpper(flag.Arg(i)) {
				qtype = k
				continue Flags
			}
		}
		// If it looks like a class, it is a class
		for k, v := range dns.Class_str {
			if v == strings.ToUpper(flag.Arg(i)) {
				qclass = k
				continue Flags
			}
		}
		// If it starts with TYPExxx it is unknown rr
		if strings.HasPrefix(flag.Arg(i), "TYPE") {
			i, e := strconv.Atoi(string([]byte(flag.Arg(i))[4:]))
			if e == nil {
				qtype = uint16(i)
				continue Flags
			}
		}

		// Anything else is a qname
		qname = append(qname, flag.Arg(i))
	}
	if len(qname) == 0 {
		qname = make([]string, 1)
		qname[0] = "."
		qtype = dns.TypeNS
	}
	if qtype == 0 {
		qtype = dns.TypeA
	}

	nameserver = string([]byte(nameserver)[1:]) // chop off @
	if !strings.HasSuffix(nameserver, ":53") {
		nameserver += ":53"
	}
	// ipv6 todo

	// We use the async query handling, just to show how
	// it is to be used.
	dns.HandleQueryFunc(".", q)
	dns.ListenAndQuery(nil, nil)
	c := dns.NewClient()
	if *tcp {
		c.Net = "tcp"
	}

	m := new(dns.Msg)
	m.MsgHdr.Authoritative = *aa
	m.MsgHdr.AuthenticatedData = *ad
	m.MsgHdr.CheckingDisabled = *cd
	m.MsgHdr.RecursionDesired = *rd
	m.Question = make([]dns.Question, 1)
	if *dnssec || *nsid {
		opt := dns.NewRR(dns.TypeOPT).(*dns.RR_OPT)
		opt.Hdr.Rrtype = 0
		opt.SetDo()
		opt.SetVersion(0)
		opt.SetUDPSize(dns.DefaultMsgSize)
		if *nsid {
			opt.SetNsid("")
		}
		m.Extra = make([]dns.RR, 1)
		m.Extra[0] = opt
	}
//.........這裏部分代碼省略.........

func handleReflect(w dns.ResponseWriter, r *dns.Msg) {
	var (
		v4  bool
		rr  dns.RR
		str string
		a   net.IP
	)
	m := new(dns.Msg)
	m.SetReply(r)
	if ip, ok := w.RemoteAddr().(*net.UDPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (udp)"
		a = ip.IP
		v4 = a.To4() != nil
	}
	if ip, ok := w.RemoteAddr().(*net.TCPAddr); ok {
		str = "Port: " + strconv.Itoa(ip.Port) + " (tcp)"
		a = ip.IP
		v4 = a.To4() != nil
	}

	if v4 {
		rr = new(dns.RR_A)
		rr.(*dns.RR_A).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_A).A = a.To4()
	} else {
		rr = new(dns.RR_AAAA)
		rr.(*dns.RR_AAAA).Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 0}
		rr.(*dns.RR_AAAA).AAAA = a
	}

	t := new(dns.RR_TXT)
	t.Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
	t.Txt = str

	switch r.Question[0].Qtype {
	case dns.TypeTXT:
		m.Answer = append(m.Answer, t)
		m.Extra = append(m.Extra, rr)
	default:
		fallthrough
	case dns.TypeAAAA, dns.TypeA:
		m.Answer = append(m.Answer, rr)
		m.Extra = append(m.Extra, t)

	}
	/*
	   nsec3 := new(dns.RR_NSEC3)
	   nsec3.Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeNSEC3, Class: dns.ClassINET, Ttl: 0}
	   nsec3.Hash = dns.SHA1
	   nsec3.Flags = 0
	   nsec3.Iterations = 1
	   nsec3.Salt = "AABB"
	   nsec3.SaltLength = uint8(len(nsec3.Salt)/2)
	   nsec3.NextDomain = "miek.nl."
	   nsec3.TypeBitMap = []uint16{dns.TypeA, dns.TypeNS, dns.TypeSOA, dns.TypeTXT, dns.TypeRRSIG, 4000, 4001, 5949}
	   nsec3.HashNames("miek.nl.")
	   m.Extra = append(m.Extra, nsec3)
	*/

	b, ok := m.Pack()
	if *printf {
		fmt.Printf("%v\n", m.String())
	}
	if !ok {
		log.Print("Packing failed")
		m.SetRcode(r, dns.RcodeServerFailure)
		m.Extra = nil
		m.Answer = nil
		b, _ = m.Pack()
	}
	w.Write(b)
}

//.........這裏部分代碼省略.........
		if *four {
			c.Net = "tcp4"
		}
		if *six {
			c.Net = "tcp6"
		}
	} else {
		c.Net = "udp"
		if *four {
			c.Net = "udp4"
		}
		if *six {
			c.Net = "udp6"
		}
	}

	m := new(dns.Msg)
	m.MsgHdr.Authoritative = *aa
	m.MsgHdr.AuthenticatedData = *ad
	m.MsgHdr.CheckingDisabled = *cd
	m.MsgHdr.RecursionDesired = *rd
	m.Question = make([]dns.Question, 1)
	if *dnssec || *nsid {
		o := new(dns.RR_OPT)
		o.Hdr.Name = "."
		o.Hdr.Rrtype = dns.TypeOPT
		if *dnssec {
			o.SetDo()
			o.SetUDPSize(dns.DefaultMsgSize)
		}
		if *nsid {
			o.SetNsid("")
		}
		m.Extra = append(m.Extra, o)
	}

	for _, v := range qname {
		m.Question[0] = dns.Question{v, qtype, qclass}
		m.Id = dns.Id()
		if *query {
			fmt.Printf("%s\n", m.String())
		}
		// Add tsig
		if *tsig != "" {
			if algo, name, secret, ok := tsigKeyParse(*tsig); ok {
				m.SetTsig(name, algo, 300, time.Now().Unix())
				c.TsigSecret = map[string]string{name: secret}
			} else {
				fmt.Fprintf(os.Stderr, "tsig key data error\n")
				return
			}
		}
		c.Do(m, nameserver)
	}

	i := 0
forever:
	for {
		select {
		case r := <-c.Reply:
			if r.Reply != nil {
				if r.Reply.Rcode == dns.RcodeSuccess {
					if r.Request.Id != r.Reply.Id {
						fmt.Printf("Id mismatch\n")
					}
				}