96 lines
2.2 KiB
Go
96 lines
2.2 KiB
Go
// Copyright 2011 Miek Gieben. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Chaos is a small program that prints the version.bind and hostname.bind
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// for each address of the nameserver given as argument.
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package main
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import (
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"fmt"
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"github.com/miekg/dns"
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"net"
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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.Exchange(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.Exchange(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 do(t chan *dns.Msg, c *dns.Client, m *dns.Msg, addr string) {
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go func() {
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r, _, err := c.Exchange(m, addr)
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if err != nil {
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//print error stuff
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t <- nil
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}
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t <- r
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}()
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}
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func addresses(conf *dns.ClientConfig, c *dns.Client, name string) (ips []string) {
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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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t := make(chan *dns.Msg)
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defer close(t)
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do(t, c, m4, net.JoinHostPort(conf.Servers[0], conf.Port))
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do(t, c, m6, net.JoinHostPort(conf.Servers[0], conf.Port))
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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 d := <-t:
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i--
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if d == nil {
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continue
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}
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if i == 0 {
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break forever
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}
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if d.Rcode == dns.RcodeSuccess {
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for _, a := range d.Answer {
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switch a.(type) {
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case *dns.A:
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ips = append(ips,
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net.JoinHostPort(a.(*dns.A).A.String(), "53"))
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case *dns.AAAA:
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ips = append(ips,
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net.JoinHostPort(a.(*dns.AAAA).AAAA.String(), "53"))
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}
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}
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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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