dns/_examples/q/q.go

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package main
import (
"net"
"dns"
"dns/resolver"
"os"
"flag"
"fmt"
)
var Usage = func() {
fmt.Fprintf(os.Stderr, "Usage: %s [@server] [qtype] [qclass] [name ...]\n", os.Args[0])
flag.PrintDefaults()
}
func main() {
var dnssec *bool = flag.Bool("dnssec", false, "Set the DO (DNSSEC OK) bit and set the bufsize to 4096")
nameserver := "127.0.0.1" // Default nameserver
qtype := uint16(dns.TypeA) // Default qtype
qclass := uint16(dns.ClassINET) // Default qclass
var qname []string
flag.Parse()
if *dnssec {
/* */
}
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
}
// If it looks like a class, it is a class
for k, v := range dns.Class_str {
if v == flag.Arg(i) {
qclass = k
continue FLAGS
}
}
// And if it looks like type, it is a type
for k, v := range dns.Rr_str {
if v == flag.Arg(i) {
qtype = k
continue FLAGS
}
}
// Anything else is a qname
qname = append(qname, flag.Arg(i))
}
r := new(resolver.Resolver)
r.Timeout = 2
r.Attempts = 1
qr := resolver.NewQuerier(r)
// @server may be a name, resolv that
var err os.Error
_, addr, err := net.LookupHost(nameserver)
if err == nil {
r.Servers = addr
} else {
r.Servers = []string{nameserver}
}
m := new(dns.Msg)
m.Question = make([]dns.Question, 1)
for _, v := range qname {
m.Question[0] = dns.Question{v, qtype, qclass}
qr <- resolver.DnsMsg{m, nil}
in := <-qr
if in.Dns != nil {
fmt.Printf("%v\n", in.Dns)
}
}
qr <- resolver.DnsMsg{nil, nil}
<-qr
}