Golang dns.Client類代碼示例

func main() {
	serial := flag.Int("serial", 0, "Perform an IXFR with the given serial")
	nameserver := flag.String("ns", "127.0.0.1:53", "Query this nameserver")
	tsig := flag.String("tsig", "", "request tsig with key: name:key (only hmac-md5)")
	flag.Parse()
	zone := flag.Arg(flag.NArg() - 1)

	client := new(dns.Client)
	client.Net = "tcp"
	m := new(dns.Msg)
	if *serial > 0 {
		m.SetIxfr(zone, uint32(*serial))
	} else {
		m.SetAxfr(zone)
	}
	if *tsig != "" {
		a := strings.SplitN(*tsig, ":", 2)
		name, secret := a[0], a[1]
		client.TsigSecret = map[string]string{name: secret}
		m.SetTsig(name, dns.HmacMD5, 300, time.Now().Unix())
	}

	if t, e := client.XfrReceive(m, *nameserver); e == nil {
		for r := range t {
			if r.Error == nil {
				fmt.Printf("%v\n", r.Reply)
			}
		}
	} else {
		fmt.Printf("Error %v\n", e)
	}
}

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(dns.Fqdn(os.Args[1]), dns.TypeDNSKEY)
	m.SetEdns0(2048, true)

	c := new(dns.Client)
	r, _ := c.Exchange(m, conf.Servers[0]+":"+conf.Port)
	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)
	}
	for _, k := range r.Answer {
		if key, ok := k.(*dns.RR_DNSKEY); ok {
			key.Hdr.Ttl = 0
			for _, alg := range []int{dns.SHA1, dns.SHA256, dns.SHA384} {
				ds := key.ToDS(alg)
				fmt.Printf("%v; %d\n", ds, key.Flags)
			}
		}
	}
}

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("%s NAMESERVER\n", os.Args[0])
		os.Exit(1)
	}
	conf, _ := dns.ClientConfigFromFile("/etc/resolv.conf")

	m := new(dns.Msg)
	m.Question = make([]dns.Question, 1)
	c := new(dns.Client)

	addr := addresses(conf, c, os.Args[1])
	if len(addr) == 0 {
		fmt.Printf("No address found for %s\n", os.Args[1])
		os.Exit(1)
	}
	for _, a := range addr {
		m.Question[0] = dns.Question{"version.bind.", dns.TypeTXT, dns.ClassCHAOS}
		in, rtt, _, _ := c.ExchangeRtt(m, a)
		if in != nil && len(in.Answer) > 0 {
			fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
		}
		m.Question[0] = dns.Question{"hostname.bind.", dns.TypeTXT, dns.ClassCHAOS}
		in, rtt, _, _ = c.ExchangeRtt(m, a)
		if in != nil && len(in.Answer) > 0 {
			fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
		}
	}
}

func addresses(conf *dns.ClientConfig, c *dns.Client, name string) []string {
	m4 := new(dns.Msg)
	m4.SetQuestion(dns.Fqdn(os.Args[1]), dns.TypeA)
	m6 := new(dns.Msg)
	m6.SetQuestion(dns.Fqdn(os.Args[1]), dns.TypeAAAA)

	addr := make(chan []string)
	defer close(addr)
	c.Do(m4, conf.Servers[0]+":"+conf.Port, addr, qhandler)
	c.Do(m6, conf.Servers[0]+":"+conf.Port, addr, qhandler)

	var ips []string
	i := 2 // two outstanding queries
forever:
	for {
		select {
		case ip := <-addr:
			ips = append(ips, ip...)
			i--
			if i == 0 {
				break forever
			}
		}
	}
	return ips
}

// probe creates a packet and sends it to the nameserver. It
// returns a fingerprint.
func probe(c *dns.Client, addr string, f *fingerprint) *fingerprint {
	m := f.msg()
	r, err := c.Exchange(m, addr)
	if err != nil {
		return errorToFingerprint(err)
	}
	return toFingerprint(r)
}

// Get the key from the DNS (uses the local resolver) and return them.
// If nothing is found we return nil
func getKey(name string, keytag uint16, server string, tcp bool) *dns.RR_DNSKEY {
	c := new(dns.Client)
	if tcp {
		c.Net = "tcp"
	}
	m := new(dns.Msg)
	m.SetQuestion(name, dns.TypeDNSKEY)
	m.SetEdns0(4096, true)
	r, err := c.Exchange(m, server)
	if err != nil {
		return nil
	}
	for _, k := range r.Answer {
		if k1, ok := k.(*dns.RR_DNSKEY); ok {
			if k1.KeyTag() == keytag {
				return k1
			}
		}
	}
	return nil
}

func addresses(conf *dns.ClientConfig, c *dns.Client, name string) []string {
	dns.HandleQueryFunc(os.Args[1], qhandler)
	dns.ListenAndQuery(nil, nil)

	m4 := new(dns.Msg)
	m4.SetQuestion(os.Args[1], dns.TypeA)
	m6 := new(dns.Msg)
	m6.SetQuestion(os.Args[1], dns.TypeAAAA)
	c.Do(m4, conf.Servers[0]) // Also 1 and 2 (and merge the results??
	c.Do(m6, conf.Servers[0])

	var ips []string
	i := 2 // two outstanding queries
forever:
	for {
		select {
		case r := <-dns.DefaultReplyChan:
			if r[1] != nil && r[1].Rcode == dns.RcodeSuccess {
				for _, aa := range r[1].Answer {
					switch aa.(type) {
					case *dns.RR_A:
						ips = append(ips, aa.(*dns.RR_A).A.String()+":53")
					case *dns.RR_AAAA:
						ips = append(ips, "["+aa.(*dns.RR_AAAA).AAAA.String()+"]:53")
					}
				}
			} else {
				fmt.Printf("Nothing recevied for %s\n", name)
			}
			i--
			if i == 0 {
				break forever
			}
		}
	}
	return ips
}

func main() {
	dnssec := flag.Bool("dnssec", false, "request DNSSEC records")
	query := flag.Bool("question", false, "show question")
	short := flag.Bool("short", false, "abbreviate long DNSSEC records")
	check := flag.Bool("check", false, "check internal DNSSEC consistency")
	six := flag.Bool("6", false, "use IPv6 only")
	four := flag.Bool("4", false, "use IPv4 only")
	anchor := flag.String("anchor", "", "use the DNSKEY in this file for interal DNSSEC consistency")
	tsig := flag.String("tsig", "", "request tsig with key: [hmac:]name:key")
	port := flag.Int("port", 53, "port number to use")
	aa := flag.Bool("aa", false, "set AA flag in query")
	ad := flag.Bool("ad", false, "set AD flag in query")
	cd := flag.Bool("cd", false, "set CD flag in query")
	rd := flag.Bool("rd", true, "set RD flag in query")
	fallback := flag.Bool("fallback", false, "fallback to 4096 bytes bufsize and after that TCP")
	tcp := flag.Bool("tcp", false, "TCP mode")
	nsid := flag.Bool("nsid", false, "set edns nsid option")
	client := flag.String("client", "", "set edns client-subnet option")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage: %s [@server] [qtype] [qclass] [name ...]\n", os.Args[0])
		flag.PrintDefaults()
	}

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

	flag.Parse()
	if *anchor != "" {
		f, err := os.Open(*anchor)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failure to open %s: %s\n", *anchor, err.Error())
		}
		r, err := dns.ReadRR(f, *anchor)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failure to read an RR from %s: %s\n", *anchor, err.Error())
		}
		if k, ok := r.(*dns.RR_DNSKEY); !ok {
			fmt.Fprintf(os.Stderr, "No DNSKEY read from %s\n", *anchor)
		} else {
			dnskey = k
		}
	}

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
		if k, ok := dns.Str_rr[strings.ToUpper(flag.Arg(i))]; ok {
			qtype = k
			switch qtype {
			case dns.TypeAXFR:
				fmt.Fprintf(os.Stderr, "AXFR not supported\n")
				return
			case dns.TypeIXFR:
				fmt.Fprintf(os.Stderr, "AXFR not supported\n")
				return
			}
			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)
				switch qtype {
				case dns.TypeAXFR:
					fmt.Fprintf(os.Stderr, "AXFR not supported\n")
					return
				case dns.TypeIXFR:
					fmt.Fprintf(os.Stderr, "AXFR not supported\n")
					return
				}
				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
	}
//.........這裏部分代碼省略.........

func main() {
	dnssec := flag.Bool("dnssec", false, "request DNSSEC records")
	query := flag.Bool("question", false, "show question")
	short := flag.Bool("short", false, "abbreviate long DNSSEC records")
	check := flag.Bool("check", false, "check internal DNSSEC consistency")
	six := flag.Bool("6", false, "use IPv6 only")
	four := flag.Bool("4", false, "use IPv4 only")
	anchor := flag.String("anchor", "", "use the DNSKEY in this file for interal DNSSEC consistency")
	tsig := flag.String("tsig", "", "request tsig with key: [hmac:]name:key")
	port := flag.Int("port", 53, "port number to use")
	aa := flag.Bool("aa", false, "set AA flag in query")
	ad := flag.Bool("ad", false, "set AD flag in query")
	cd := flag.Bool("cd", false, "set CD flag in query")
	rd := flag.Bool("rd", true, "set RD flag in query")
	fallback := flag.Bool("fallback", false, "fallback to 4096 bytes bufsize and after that TCP")
	tcp := flag.Bool("tcp", false, "TCP mode")
	nsid := flag.Bool("nsid", false, "ask for NSID")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage: %s [@server] [qtype] [qclass] [name ...]\n", os.Args[0])
		flag.PrintDefaults()
	}

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

	flag.Parse()
	if *anchor != "" {
		f, err := os.Open(*anchor)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failure to open %s: %s\n", *anchor, err.Error())
		}
		r, err := dns.ReadRR(f, *anchor)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failure to read an RR from %s: %s\n", *anchor, err.Error())
		}
		if k, ok := r.(*dns.RR_DNSKEY); !ok {
			fmt.Fprintf(os.Stderr, "No DNSKEY read from %s\n", *anchor)
		} else {
			dnskey = k
		}
	}

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
		if k, ok := dns.Str_rr[strings.ToUpper(flag.Arg(i))]; ok {
			qtype = k
			switch qtype {
			case dns.TypeAXFR:
				fmt.Fprintf(os.Stderr, "AXFR not supported\n")
				return
			case dns.TypeIXFR:
				fmt.Fprintf(os.Stderr, "AXFR not supported\n")
				return
			}
			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)
				switch qtype {
				case dns.TypeAXFR:
					fmt.Fprintf(os.Stderr, "AXFR not supported\n")
					return
				case dns.TypeIXFR:
					fmt.Fprintf(os.Stderr, "AXFR not supported\n")
					return
				}
				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
	}

//.........這裏部分代碼省略.........