func ExamplePrivateHandle() { dns.PrivateHandle("APAIR", TypeAPAIR, NewAPAIR) defer dns.PrivateHandleRemove(TypeAPAIR) rr, err := dns.NewRR("miek.nl. APAIR (1.2.3.4 1.2.3.5)") if err != nil { log.Fatal("could not parse APAIR record: ", err) } fmt.Println(rr) // Output: miek.nl. 3600 IN APAIR 1.2.3.4 1.2.3.5 m := new(dns.Msg) m.Id = 12345 m.SetQuestion("miek.nl.", TypeAPAIR) m.Answer = append(m.Answer, rr) fmt.Println(m) // ;; opcode: QUERY, status: NOERROR, id: 12345 // ;; flags: rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 // // ;; QUESTION SECTION: // ;miek.nl. IN APAIR // // ;; ANSWER SECTION: // miek.nl. 3600 IN APAIR 1.2.3.4 1.2.3.5 }
func setupRootZone() { dns.HandleFunc(".", func(w dns.ResponseWriter, r *dns.Msg) { m := new(dns.Msg) m.SetRcode(r, dns.RcodeRefused) w.WriteMsg(m) }) }
func dorequest(c *C, msg *dns.Msg) *dns.Msg { cli := new(dns.Client) // cli.ReadTimeout = 2 * time.Second r, _, err := cli.Exchange(msg, "127.0.0.1"+PORT) if err != nil { c.Logf("request err '%s': %s", msg.String(), err) c.Fail() } return r }
// Retrieve the MX records for miek.nl. func ExampleMX() { config, _ := dns.ClientConfigFromFile("/etc/resolv.conf") c := new(dns.Client) m := new(dns.Msg) m.SetQuestion("miek.nl.", dns.TypeMX) m.RecursionDesired = true r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port) if err != nil { return } if r.Rcode != dns.RcodeSuccess { return } for _, a := range r.Answer { if mx, ok := a.(*dns.MX); ok { fmt.Printf("%s\n", mx.String()) } } }
func exchangeSubnet(c *C, name string, dnstype uint16, ip string) *dns.Msg { msg := new(dns.Msg) msg.SetQuestion(name, dnstype) o := new(dns.OPT) o.Hdr.Name = "." o.Hdr.Rrtype = dns.TypeOPT e := new(dns.EDNS0_SUBNET) e.Code = dns.EDNS0SUBNET e.SourceScope = 0 e.Address = net.ParseIP(ip) e.Family = 1 // IP4 e.SourceNetmask = net.IPv4len * 8 o.Option = append(o.Option, e) msg.Extra = append(msg.Extra, o) c.Log("msg", msg) return dorequest(c, msg) }
// Retrieve the DNSKEY records of a zone and convert them // to DS records for SHA1, SHA256 and SHA384. func ExampleDS(zone string) { config, _ := dns.ClientConfigFromFile("/etc/resolv.conf") c := new(dns.Client) m := new(dns.Msg) if zone == "" { zone = "miek.nl" } m.SetQuestion(dns.Fqdn(zone), dns.TypeDNSKEY) m.SetEdns0(4096, true) r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port) if err != nil { return } if r.Rcode != dns.RcodeSuccess { return } for _, k := range r.Answer { if key, ok := k.(*dns.DNSKEY); ok { for _, alg := range []uint8{dns.SHA1, dns.SHA256, dns.SHA384} { fmt.Printf("%s; %d\n", key.ToDS(alg).String(), key.Flags) } } } }
func exchange(c *C, name string, dnstype uint16) *dns.Msg { msg := new(dns.Msg) msg.SetQuestion(name, dnstype) return dorequest(c, msg) }
func serve(w dns.ResponseWriter, req *dns.Msg, z *Zone) { qtype := req.Question[0].Qtype logPrintf("[zone %s] incoming %s %s %d from %s\n", z.Origin, req.Question[0].Name, dns.TypeToString[qtype], req.MsgHdr.Id, w.RemoteAddr()) // Global meter metrics.Get("queries").(metrics.Meter).Mark(1) // Zone meter z.Metrics.Queries.Mark(1) logPrintln("Got request", req) label := getQuestionName(z, req) z.Metrics.LabelStats.Add(label) realIp, _, _ := net.SplitHostPort(w.RemoteAddr().String()) z.Metrics.ClientStats.Add(realIp) var ip net.IP // EDNS or real IP var edns *dns.EDNS0_SUBNET var opt_rr *dns.OPT for _, extra := range req.Extra { switch extra.(type) { case *dns.OPT: for _, o := range extra.(*dns.OPT).Option { opt_rr = extra.(*dns.OPT) switch e := o.(type) { case *dns.EDNS0_NSID: // do stuff with e.Nsid case *dns.EDNS0_SUBNET: z.Metrics.EdnsQueries.Mark(1) logPrintln("Got edns", e.Address, e.Family, e.SourceNetmask, e.SourceScope) if e.Address != nil { edns = e ip = e.Address } } } } } if len(ip) == 0 { // no edns subnet ip = net.ParseIP(realIp) } targets, netmask := z.Options.Targeting.GetTargets(ip) m := new(dns.Msg) m.SetReply(req) if e := m.IsEdns0(); e != nil { m.SetEdns0(4096, e.Do()) } m.Authoritative = true // TODO: set scope to 0 if there are no alternate responses if edns != nil { if edns.Family != 0 { if netmask < 16 { netmask = 16 } edns.SourceScope = uint8(netmask) m.Extra = append(m.Extra, opt_rr) } } labels, labelQtype := z.findLabels(label, targets, qTypes{dns.TypeMF, dns.TypeCNAME, qtype}) if labelQtype == 0 { labelQtype = qtype } if labels == nil { firstLabel := (strings.Split(label, "."))[0] if firstLabel == "_status" { if qtype == dns.TypeANY || qtype == dns.TypeTXT { m.Answer = statusRR(label + "." + z.Origin + ".") } else { m.Ns = append(m.Ns, z.SoaRR()) } m.Authoritative = true w.WriteMsg(m) return } if firstLabel == "_country" { if qtype == dns.TypeANY || qtype == dns.TypeTXT { h := dns.RR_Header{Ttl: 1, Class: dns.ClassINET, Rrtype: dns.TypeTXT} h.Name = label + "." + z.Origin + "." txt := []string{ w.RemoteAddr().String(), ip.String(), } targets, netmask := z.Options.Targeting.GetTargets(ip) txt = append(txt, strings.Join(targets, " ")) txt = append(txt, fmt.Sprintf("/%d", netmask), serverID, serverIP) m.Answer = []dns.RR{&dns.TXT{Hdr: h, Txt: txt, }} } else { m.Ns = append(m.Ns, z.SoaRR()) } m.Authoritative = true w.WriteMsg(m) return } // return NXDOMAIN m.SetRcode(req, dns.RcodeNameError) m.Authoritative = true m.Ns = []dns.RR{z.SoaRR()} w.WriteMsg(m) return } if servers := labels.Picker(labelQtype, labels.MaxHosts); servers != nil { var rrs []dns.RR for _, record := range servers { rr := record.RR rr.Header().Name = req.Question[0].Name rrs = append(rrs, rr) } m.Answer = rrs } if len(m.Answer) == 0 { m.Ns = append(m.Ns, z.SoaRR()) } logPrintln(m) err := w.WriteMsg(m) if err != nil { // if Pack'ing fails the Write fails. Return SERVFAIL. log.Println("Error writing packet", m) dns.HandleFailed(w, req) } return }
func serve(w dns.ResponseWriter, req *dns.Msg, z *Zone) { qtype := req.Question[0].Qtype logPrintf("[zone %s] incoming %s %s (id %d) from %s\n", z.Origin, req.Question[0].Name, dns.TypeToString[qtype], req.Id, w.RemoteAddr()) // Global meter metrics.Get("queries").(metrics.Meter).Mark(1) // Zone meter z.Metrics.Queries.Mark(1) logPrintln("Got request", req) label := getQuestionName(z, req) z.Metrics.LabelStats.Add(label) // IP that's talking to us (not EDNS CLIENT SUBNET) var realIP net.IP if addr, ok := w.RemoteAddr().(*net.UDPAddr); ok { realIP = make(net.IP, len(addr.IP)) copy(realIP, addr.IP) } else if addr, ok := w.RemoteAddr().(*net.TCPAddr); ok { realIP = make(net.IP, len(addr.IP)) copy(realIP, addr.IP) } z.Metrics.ClientStats.Add(realIP.String()) var ip net.IP // EDNS or real IP var edns *dns.EDNS0_SUBNET var opt_rr *dns.OPT for _, extra := range req.Extra { switch extra.(type) { case *dns.OPT: for _, o := range extra.(*dns.OPT).Option { opt_rr = extra.(*dns.OPT) switch e := o.(type) { case *dns.EDNS0_NSID: // do stuff with e.Nsid case *dns.EDNS0_SUBNET: z.Metrics.EdnsQueries.Mark(1) logPrintln("Got edns", e.Address, e.Family, e.SourceNetmask, e.SourceScope) if e.Address != nil { edns = e ip = e.Address } } } } } if len(ip) == 0 { // no edns subnet ip = realIP } targets, netmask := z.Options.Targeting.GetTargets(ip) m := new(dns.Msg) m.SetReply(req) if e := m.IsEdns0(); e != nil { m.SetEdns0(4096, e.Do()) } m.Authoritative = true // TODO: set scope to 0 if there are no alternate responses if edns != nil { if edns.Family != 0 { if netmask < 16 { netmask = 16 } edns.SourceScope = uint8(netmask) m.Extra = append(m.Extra, opt_rr) } } labels, labelQtype := z.findLabels(label, targets, qTypes{dns.TypeMF, dns.TypeCNAME, qtype}) if labelQtype == 0 { labelQtype = qtype } if labels == nil { permitDebug := !*flagPrivateDebug || (realIP != nil && realIP.IsLoopback()) firstLabel := (strings.Split(label, "."))[0] if permitDebug && firstLabel == "_status" { if qtype == dns.TypeANY || qtype == dns.TypeTXT { m.Answer = statusRR(label + "." + z.Origin + ".") } else { m.Ns = append(m.Ns, z.SoaRR()) } m.Authoritative = true w.WriteMsg(m) t := time.Now() logAccessPrintf("%s [%02d/%02d/%04d:%02d:%02d:%02d] %s %s %s\n", w.RemoteAddr(), t.Day(), t.Month(), t.Year(), t.Hour(), t.Minute(), t.Second(), req.Question[0].Name, dns.TypeToString[qtype], m.Answer) return } if firstLabel == "_country" { if qtype == dns.TypeANY || qtype == dns.TypeTXT { h := dns.RR_Header{Ttl: 1, Class: dns.ClassINET, Rrtype: dns.TypeTXT} h.Name = label + "." + z.Origin + "." txt := []string{ w.RemoteAddr().String(), ip.String(), } targets, netmask := z.Options.Targeting.GetTargets(ip) txt = append(txt, strings.Join(targets, " ")) txt = append(txt, fmt.Sprintf("/%d", netmask), serverID, serverIP) m.Answer = []dns.RR{&dns.TXT{Hdr: h, Txt: txt, }} } else { m.Ns = append(m.Ns, z.SoaRR()) } m.Authoritative = true w.WriteMsg(m) t := time.Now() logAccessPrintf("%s [%02d/%02d/%04d:%02d:%02d:%02d] %s %s %s\n", w.RemoteAddr(), t.Day(), t.Month(), t.Year(), t.Hour(), t.Minute(), t.Second(), req.Question[0].Name, dns.TypeToString[qtype], m.Answer) return } // return NXDOMAIN m.SetRcode(req, dns.RcodeNameError) m.Authoritative = true m.Ns = []dns.RR{z.SoaRR()} w.WriteMsg(m) t := time.Now() logAccessPrintf("%s [%02d/%02d/%04d:%02d:%02d:%02d] %s %s %s\n", w.RemoteAddr(), t.Day(), t.Month(), t.Year(), t.Hour(), t.Minute(), t.Second(), req.Question[0].Name, dns.TypeToString[qtype], m.Answer) return } if servers := labels.Picker(labelQtype, labels.MaxHosts); servers != nil { var rrs []dns.RR for _, record := range servers { rr := dns.Copy(record.RR) rr.Header().Name = req.Question[0].Name rrs = append(rrs, rr) } m.Answer = rrs } if len(m.Answer) == 0 { m.Ns = append(m.Ns, z.SoaRR()) } else { if z.Labels[label] != nil { z.Labels[label].Hits++ logPrintln("*********** ", z.Labels[label].Hits) } } //logPrintln(m) err := w.WriteMsg(m) if err != nil { // if Pack'ing fails the Write fails. Return SERVFAIL. log.Println("Error writing packet", m) dns.HandleFailed(w, req) } t := time.Now() logAccessPrintf("%s [%02d/%02d/%04d:%02d:%02d:%02d] %s %s %s\n", w.RemoteAddr(), t.Day(), t.Month(), t.Year(), t.Hour(), t.Minute(), t.Second(), req.Question[0].Name, dns.TypeToString[qtype], m.Answer) return }