Example #1
0
File: q.go Project: polvi/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")
	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 [@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.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
			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 = dns.Fqdn(string([]byte(nameserver)[1:])) // chop off @
	nameserver += ":" + strconv.Itoa(*port)

	// We use the async query handling, just to show how it is to be used.
	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.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{dns.Fqdn(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
			}
		}
		if qtype == dns.TypeAXFR {
			c.Net = "tcp"
			doXfr(c, m, nameserver)
			continue
		}
		if qtype == dns.TypeIXFR {
			doXfr(c, m, nameserver)
			continue
		}

		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 e != nil {
				fmt.Printf(";; %s\n", e.Error())
				return
			}
			if r.Rcode != dns.RcodeSuccess {
				return
			}
			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.RR_OPT)
						o.Hdr.Name = "."
						o.Hdr.Rrtype = dns.TypeOPT
						o.SetUDPSize(dns.DefaultMsgSize)
						m.Extra = append(m.Extra, o)
						r, rtt, e = c.ExchangeRtt(m, nameserver)
						*dnssec = true
						goto Redo
					} else {
						// First EDNS, then TCP
						fmt.Printf(";; Truncated, trying TCP\n")
						c.Net = "tcp"
						r, rtt, e = c.ExchangeRtt(m, nameserver)
						goto Redo
					}
				}
			}
			if r.MsgHdr.Truncated && !*fallback {
				fmt.Printf(";; Truncated\n")
			}
			if *check {
				sigCheck(r, nameserver, *tcp)
				nsecCheck(r)
			}
			if *short {
				r = shortMsg(r)
			}

			fmt.Printf("%v", r)
			fmt.Printf("\n;; query time: %.3d ┬Ás, server: %s(%s), size: %d bytes\n", rtt/1e3, nameserver, c.Net, r.Size)
		})
	}
	if qtype != dns.TypeAXFR && qtype != dns.TypeIXFR {
		// xfr don't start any goroutines
		select {}
	}

}