package main

// Print the version.bind and hostname.bind for each
// address of NAMESERVER
// (c) Miek Gieben - 2011
import (
	"dns"
	"os"
	"fmt"
)

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("%s NAMESERVER\n", os.Args[0])
		os.Exit(1)
	}
	conf, _ := dns.ClientConfigFromFile("/etc/resolv.conf")

	m := new(dns.Msg)
	m.Question = make([]dns.Question, 1)
        c := dns.NewClient()

        // Todo: in parallel
        addr := addresses(conf, c, os.Args[0])
        if len(addr) == 0 {
                fmt.Printf("No address found for %s\n", os.Args[1])
                os.Exit(1)
        }
	for _, a := range addr {
		m.Question[0] = dns.Question{"version.bind.", dns.TypeTXT, dns.ClassCHAOS}
		in := c.Exchange(m, a)
		if in != nil && in.Answer != nil {
			fmt.Printf("%v\n", in.Answer[0])
		}
		m.Question[0] = dns.Question{"hostname.bind.", dns.TypeTXT, dns.ClassCHAOS}
		in = c.Exchange(m, a)
		if in != nil && in.Answer != nil {
			fmt.Printf("%v\n", in.Answer[0])
		}
	}
}

func qhandler(w dns.RequestWriter, m *dns.Msg) {
        w.Send(m)
        r, _ := w.Receive()
        w.Write(r)
}

func addresses(conf *dns.ClientConfig, c *dns.Client, name string) []string {
        dns.HandleQueryFunc(os.Args[1], qhandler)
        dns.ListenAndQuery(nil, nil)

	m4 := new(dns.Msg)
        m4.SetQuestion(os.Args[1], dns.TypeA)
	m6 := new(dns.Msg)
        m6.SetQuestion(os.Args[1], dns.TypeAAAA)
        c.Do(m4, conf.Servers[0])       // Also 1 and 2 (and merge the results??
        c.Do(m6, conf.Servers[0])

	var ips []string
        i := 2  // two outstanding queries
forever:
        for {
                select {
                case r := <-dns.DefaultReplyChan:
                        if r[1] !=nil && r[1].Rcode == dns.RcodeSuccess {
                                for _, aa := range r[1].Answer {
                                        switch aa.(type) {
                                        case *dns.RR_A:
                                                ips = append(ips, aa.(*dns.RR_A).A.String()+":53")
                                        case *dns.RR_AAAA:
                                                ips = append(ips, "[" + aa.(*dns.RR_AAAA).AAAA.String()+"]:53")
                                        }
                                }
                        } else {
		                fmt.Printf("Nothing recevied for %s\n", name)
                        }
                        i--
                        if i == 0 {
                                break forever
                        }
                }
        }
	return ips
}