// 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())
}
}