90 lines
2.0 KiB
Go
90 lines
2.0 KiB
Go
package main
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// Print the version.bind and hostname.bind for each
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// address of NAMESERVER
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// (c) Miek Gieben - 2011
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import (
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"dns"
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"fmt"
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"os"
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)
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func main() {
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if len(os.Args) != 2 {
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fmt.Printf("%s NAMESERVER\n", os.Args[0])
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os.Exit(1)
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}
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conf, _ := dns.ClientConfigFromFile("/etc/resolv.conf")
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m := new(dns.Msg)
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m.Question = make([]dns.Question, 1)
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c := new(dns.Client)
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addr := addresses(conf, c, os.Args[1])
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if len(addr) == 0 {
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fmt.Printf("No address found for %s\n", os.Args[1])
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os.Exit(1)
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}
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for _, a := range addr {
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m.Question[0] = dns.Question{"version.bind.", dns.TypeTXT, dns.ClassCHAOS}
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in, rtt, _, _ := c.ExchangeRtt(m, a)
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if in != nil && len(in.Answer) > 0 {
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fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
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}
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m.Question[0] = dns.Question{"hostname.bind.", dns.TypeTXT, dns.ClassCHAOS}
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in, rtt, _, _ = c.ExchangeRtt(m, a)
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if in != nil && len(in.Answer) > 0 {
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fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
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}
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}
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}
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func qhandler(w dns.RequestWriter, m *dns.Msg) {
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w.Dial()
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defer w.Close()
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if err := w.Send(m); err != nil {
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w.Write(nil)
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return
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}
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r, _ := w.Receive()
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w.Write(r)
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}
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func addresses(conf *dns.ClientConfig, c *dns.Client, name string) []string {
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dns.HandleQueryFunc(os.Args[1], qhandler)
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dns.ListenAndQuery(nil)
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m4 := new(dns.Msg)
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m4.SetQuestion(dns.Fqdn(os.Args[1]), dns.TypeA)
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m6 := new(dns.Msg)
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m6.SetQuestion(dns.Fqdn(os.Args[1]), dns.TypeAAAA)
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c.Do(m4, conf.Servers[0]+":"+conf.Port)
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c.Do(m6, conf.Servers[0]+":"+conf.Port)
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var ips []string
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i := 2 // two outstanding queries
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forever:
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for {
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select {
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case r := <-c.Reply:
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if r.Reply != nil && r.Reply.Rcode == dns.RcodeSuccess {
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for _, aa := range r.Reply.Answer {
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switch aa.(type) {
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case *dns.RR_A:
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ips = append(ips, aa.(*dns.RR_A).A.String()+":53")
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case *dns.RR_AAAA:
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ips = append(ips, "["+aa.(*dns.RR_AAAA).AAAA.String()+"]:53")
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}
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}
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} else {
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fmt.Printf("Nothing recevied for %s\n", name)
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}
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i--
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if i == 0 {
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break forever
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}
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}
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}
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return ips
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}
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