Example #1
0
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.Exchange(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.Exchange(m, a)
		if in != nil && len(in.Answer) > 0 {
			fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
		}
	}
}
Example #2
0
func do(t chan *dns.Msg, c *dns.Client, m *dns.Msg, addr string) {
	go func() {
		r, _, err := c.Exchange(m, addr)
		if err != nil {
			//print error stuff
			t <- nil
		}
		t <- r
	}()
}
Example #3
0
File: q.go Project: Meyermagic/dns
// 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.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.DNSKEY); ok {
			if k1.KeyTag() == keytag {
				return k1
			}
		}
	}
	return nil
}
Example #4
0
File: q.go Project: Meyermagic/dns
func main() {
	short = flag.Bool("short", false, "abbreviate long DNSSEC records")
	dnssec := flag.Bool("dnssec", false, "request DNSSEC records")
	query := flag.Bool("question", false, "show question")
	check := flag.Bool("check", false, "check internal DNSSEC consistency")
	raw := flag.Bool("raw", false, "do not strip 'http://' from the qname")
	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")
	//serial := flag.Int("serial", 0, "perform an IXFR with this serial")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage: %s [options] [@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)
	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.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.StringToType[strings.ToUpper(flag.Arg(i))]; ok {
			qtype = k
			continue Flags
		}
		// If it looks like a class, it is a class
		if k, ok := dns.StringToClass[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 @
	// if the nameserver is from /etc/resolv.conf the [ and ] are already
	// added, thereby breaking net.ParseIP. Check for this and don't
	// fully qualify such a name
	if nameserver[0] == '[' && nameserver[len(nameserver)-1] == ']' {
		nameserver = nameserver[1 : len(nameserver)-1]
	}
	if i := net.ParseIP(nameserver); i != nil {
		nameserver = net.JoinHostPort(nameserver, strconv.Itoa(*port))
	} else {
		nameserver = dns.Fqdn(nameserver) + ":" + strconv.Itoa(*port)
	}
	c := new(dns.Client)
	if *tcp {
		c.Net = "tcp"
		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 || *client != "" {
		o := new(dns.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 _, v := range qname {
		if !*raw && strings.HasPrefix(v, "http://") {
			v = v[7:]
			if v[len(v)-1] == '/' {
				v = v[:len(v)-1]
			}
		}

		m.Question[0] = dns.Question{dns.Fqdn(v), qtype, qclass}
		m.Id = dns.Id()
		// 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
			}
		}
		if *query {
			fmt.Printf("%s", m.String())
			fmt.Printf("\n;; size: %d bytes\n\n", m.Len())
		}
		if qtype == dns.TypeAXFR {
			c.Net = "tcp"
			doXfr(c, m, nameserver)
			continue
		}
		if qtype == dns.TypeIXFR {
			doXfr(c, m, nameserver)
			continue
		}
	Redo:
		r, rtt, e := c.Exchange(m, nameserver)
		if e != nil {
			fmt.Printf(";; %s\n", e.Error())
			continue
		}
		if r.Id != m.Id {
			fmt.Fprintf(os.Stderr, "Id mismatch\n")
			return
		}
		if r.MsgHdr.Truncated && *fallback {
			if c.Net != "tcp" {
				if !*dnssec {
					fmt.Printf(";; Truncated, trying %d bytes bufsize\n", dns.DefaultMsgSize)
					o := new(dns.OPT)
					o.Hdr.Name = "."
					o.Hdr.Rrtype = dns.TypeOPT
					o.SetUDPSize(dns.DefaultMsgSize)
					m.Extra = append(m.Extra, o)
					r, rtt, e = c.Exchange(m, nameserver)
					*dnssec = true
					goto Redo
				} else {
					// First EDNS, then TCP
					fmt.Printf(";; Truncated, trying TCP\n")
					c.Net = "tcp"
					r, rtt, e = c.Exchange(m, nameserver)
					goto Redo
				}
			}
		}
		if r.MsgHdr.Truncated && !*fallback {
			fmt.Printf(";; Truncated\n")
		}
		if *check {
			sigCheck(r, nameserver, *tcp)
		}
		if *short {
			r = shortMsg(r)
		}

		fmt.Printf("%v", r)
		fmt.Printf("\n;; query time: %.3d µs, server: %s(%s), size: %d bytes\n", rtt/1e3, nameserver, c.Net, r.Len())
	}
}
Example #5
0
func main() {
	var err error
	if len(os.Args) != 2 {
		fmt.Printf("%s ZONE\n", os.Args[0])
		os.Exit(1)
	}
	conf, err = dns.ClientConfigFromFile("/etc/resolv.conf")
	if conf == nil {
		fmt.Printf("Cannot initialize the local resolver: %s\n", err)
		os.Exit(1)
	}
	localm = new(dns.Msg)
	localm.MsgHdr.RecursionDesired = true
	localm.Question = make([]dns.Question, 1)
	localc = new(dns.Client)
	localc.ReadTimeout = TIMEOUT * 1e9
	r, err := localQuery(dns.Fqdn(os.Args[1]), dns.TypeNS)
	if r == nil {
		fmt.Printf("Cannot retrieve the list of name servers for %s: %s\n", dns.Fqdn(os.Args[1]), err)
		os.Exit(1)
	}
	if r.Rcode == dns.RcodeNameError {
		fmt.Printf("No such domain %s\n", dns.Fqdn(os.Args[1]))
		os.Exit(1)
	}
	m := new(dns.Msg)
	m.MsgHdr.RecursionDesired = false
	m.Question = make([]dns.Question, 1)
	c := new(dns.Client)
	c.ReadTimeout = TIMEOUT * 1e9
	success := true
	numNS := 0
	for _, ans := range r.Answer {
		switch ans.(type) {
		case *dns.NS:
			nameserver := ans.(*dns.NS).Ns
			numNS += 1
			ips := make([]string, 0)
			fmt.Printf("%s : ", nameserver)
			ra, err := localQuery(nameserver, dns.TypeA)
			if ra == nil {
				fmt.Printf("Error getting the IPv4 address of %s: %s\n", nameserver, err)
				os.Exit(1)
			}
			if ra.Rcode != dns.RcodeSuccess {
				fmt.Printf("Error getting the IPv4 address of %s: %s\n", nameserver, dns.RcodeToString[ra.Rcode])
				os.Exit(1)
			}
			for _, ansa := range ra.Answer {
				switch ansa.(type) {
				case *dns.A:
					ips = append(ips, ansa.(*dns.A).A.String())
				}
			}
			raaaa, err := localQuery(nameserver, dns.TypeAAAA)
			if raaaa == nil {
				fmt.Printf("Error getting the IPv6 address of %s: %s\n", nameserver, err)
				os.Exit(1)
			}
			if raaaa.Rcode != dns.RcodeSuccess {
				fmt.Printf("Error getting the IPv6 address of %s: %s\n", nameserver, dns.RcodeToString[raaaa.Rcode])
				os.Exit(1)
			}
			for _, ansaaaa := range raaaa.Answer {
				switch ansaaaa.(type) {
				case *dns.AAAA:
					ips = append(ips, ansaaaa.(*dns.AAAA).AAAA.String())
				}
			}
			if len(ips) == 0 {
				success = false
				fmt.Printf("No IP address for this server")
			}
			for _, ip := range ips {
				m.Question[0] = dns.Question{dns.Fqdn(os.Args[1]), dns.TypeSOA, dns.ClassINET}
				nsAddressPort := ""
				if strings.ContainsAny(":", ip) {
					// IPv6 address
					nsAddressPort = "[" + ip + "]:53"
				} else {
					nsAddressPort = ip + ":53"
				}
				soa, _, err := c.Exchange(m, nsAddressPort)
				// TODO: retry if timeout? Otherwise, one lost UDP packet and it is the end
				if soa == nil {
					success = false
					fmt.Printf("%s (%s) ", ip, err)
					goto Next
				}
				if soa.Rcode != dns.RcodeSuccess {
					success = false
					fmt.Printf("%s (%s) ", ips, dns.RcodeToString[soa.Rcode])
					goto Next
				}
				if len(soa.Answer) == 0 { // May happen if the server is a recursor, not authoritative, since we query with RD=0
					success = false
					fmt.Printf("%s (0 answer) ", ip)
					goto Next
				}
				rsoa := soa.Answer[0]
				switch rsoa.(type) {
				case *dns.SOA:
					if soa.MsgHdr.Authoritative {
						// TODO: test if all name servers have the same serial ?
						fmt.Printf("%s (%d) ", ips, rsoa.(*dns.SOA).Serial)
					} else {
						success = false
						fmt.Printf("%s (not authoritative) ", ips)
					}
				}
			}
		Next:
			fmt.Printf("\n")
		}
	}
	if numNS == 0 {
		fmt.Printf("No NS records for \"%s\". It is probably a CNAME to a domain but not a zone\n", dns.Fqdn(os.Args[1]))
		os.Exit(1)
	}
	if success {
		os.Exit(0)
	}
	os.Exit(1)
}