query.go

package main

import (
	"net"
	"strings"

	"github.com/miekg/dns"
)

var client dns.Client

func init() {
	client.Timeout = globalTimeout
	client.Dialer = &net.Dialer{
		Timeout: globalTimeout,
	}
}

// NOTE: these query functions are not fully recursive
// they are meant to be used with a fully recursive resolver like unbound/bind/named

func queryNS(server, domain string) ([]string, error) {
	domain = dns.Fqdn(domain)
	v("dns query: @%s NS %s", server, domain)
	m := new(dns.Msg)
	m.SetQuestion(domain, dns.TypeNS)

	in, _, err := client.Exchange(m, server)
	if err != nil {
		return nil, err
	}

	out := make([]string, 0, 2)
	for i := range in.Answer {
		if t, ok := in.Answer[i].(*dns.NS); ok {
			v("dns answer NS @%s\t%s:\t%s\n", server, domain, t.Ns)
			t.Ns = strings.ToLower(t.Ns)
			out = append(out, t.Ns)
		}
	}

	return out, nil
}

func queryA(server, domain string) ([]net.IP, error) {
	domain = dns.Fqdn(domain)
	v("dns query: @%s A %s", server, domain)
	m := new(dns.Msg)
	m.SetQuestion(domain, dns.TypeA)

	in, _, err := client.Exchange(m, server)
	if err != nil {
		return nil, err
	}

	out := make([]net.IP, 0, 1)
	for i := range in.Answer {
		if t, ok := in.Answer[i].(*dns.A); ok {
			v("dns answer A @%s\t%s:\t%s\n", server, domain, t.A.String())
			out = append(out, t.A)
		}
	}

	return out, nil
}

func queryAAAA(server, domain string) ([]net.IP, error) {
	domain = dns.Fqdn(domain)
	v("dns query: @%s AAAA %s", server, domain)
	m := new(dns.Msg)
	m.SetQuestion(domain, dns.TypeAAAA)

	in, _, err := client.Exchange(m, server)
	if err != nil {
		return nil, err
	}

	out := make([]net.IP, 0, 1)
	for i := range in.Answer {
		if t, ok := in.Answer[i].(*dns.AAAA); ok {
			v("dns answer AAAA @%s\t%s:\t%s\n", server, domain, t.AAAA.String())
			out = append(out, t.AAAA)
		}
	}

	return out, nil
}

func queryIP(server, domain string) ([]net.IP, error) {
	aIPs, err := queryA(server, domain)
	if err != nil {
		return aIPs, err
	}
	aaaaIPs, err := queryAAAA(server, domain)
	return append(aIPs, aaaaIPs...), err
}