// 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 }
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()) } }