func DiscoverDNS(domain string) (*m.SuggestedMonitor, error) {
recordType := "A"
recordName := domain
server := "8.8.8.8"
for {
nameservers, err := net.LookupNS(domain)
if err != nil || len(nameservers) < 1 {
parts := strings.Split(domain, ".")
if len(parts) < 2 {
break
}
domain = strings.Join(parts[1:], ".")
} else {
servers := make([]string, len(nameservers))
for i, ns := range nameservers {
s := strings.TrimSuffix(ns.Host, ".")
servers[i] = s
}
server = strings.Join(servers, ",")
break
}
}
settings := []m.MonitorSettingDTO{
{Variable: "name", Value: recordName},
{Variable: "type", Value: recordType},
{Variable: "server", Value: server},
}
return &m.SuggestedMonitor{MonitorTypeId: 4, Settings: settings}, nil
}
func (c *Bootstrap) checkDomain(fqdn string, cached bool, r serviceRegistry) (uris []string, err error) {
uris, err = r.matchDomain(fqdn)
if err != nil {
return
}
if len(uris) > 0 || !cached {
return
}
if nsSet, err := net.LookupNS(fqdn); err != nil || len(nsSet) == 0 {
return nil, nil
}
c.reloadCache = true
body, cached, err := c.fetch(fmt.Sprintf(c.Bootstrap, dns))
if err != nil {
return nil, err
}
defer body.Close()
if err := json.NewDecoder(body).Decode(&r); err != nil {
return nil, err
}
return r.matchDomain(fqdn)
}
// checkNSRecordMatches does a spot check for DNS misconfiguration, and prints a warning
// if using it for DNS is likely to be broken.
func checkNSRecordMatches(domain, hostname string) {
time.Sleep(1 * time.Second)
results, err := net.LookupNS(domain)
if err != nil {
log.Printf("|WARN| No working NS records found for %s", domain)
log.Printf("|WARN| You can still test things using `dig example.%s @%s`, but you won't be able to resolve hosts directly.", domain, hostname)
log.Printf("|WARN| See https://github.com/ConradIrwin/aws-name-server for instructions on setting up NS records.")
return
}
matched := false
for _, record := range results {
if record.Host == hostname {
matched = true
}
}
if !matched {
log.Printf("|WARN| The NS record for %s points to: %s", domain, results[0].Host)
log.Printf("|WARN| But --hostname is: %s", hostname)
log.Printf("|WARN| These hostnames must match if you want DNS to work properly.")
log.Printf("|WARN| See https://github.com/ConradIrwin/aws-name-server for instructions on NS records.")
}
}
func main() {
members := make([]string, 0)
raft.SetLogLevel(0)
flag.Parse()
if discover {
ns, err := net.LookupNS(domain)
if err != nil {
log.Fatal(err)
return
}
if len(ns) < 1 {
log.Fatal("No NS records found for ", domain)
return
}
for _, n := range ns {
members = append(members, strings.TrimPrefix(n.Host, "."))
}
} else if join != "" {
members = strings.Split(join, ",")
}
s := NewServer(members, domain, ldns, lhttp, dataDir, rtimeout, wtimeout, secret)
// Set up metrics if specified on the command line
if metricsToStdErr {
go metrics.Log(metrics.DefaultRegistry, 60e9, log.New(os.Stderr, "metrics: ", log.Lmicroseconds))
}
if len(graphiteServer) > 1 {
addr, err := net.ResolveTCPAddr("tcp", graphiteServer)
if err != nil {
go metrics.Graphite(metrics.DefaultRegistry, 10e9, "skydns", addr)
}
}
if len(stathatUser) > 1 {
go stathat.Stathat(metrics.DefaultRegistry, 10e9, stathatUser)
}
waiter, err := s.Start()
if err != nil {
log.Fatal(err)
return
}
waiter.Wait()
}
func domainExists(name string) (bool, error) {
nss, err := net.LookupNS(name)
if err != nil {
if err, ok := err.(*net.DNSError); ok {
if err.Err == "no such host" {
return false, nil
}
}
return false, err
}
return len(nss) > 0, nil
}
func (l *lookup) process() {
nss, err := net.LookupNS(l.name)
if err != nil {
l.err = err
} else {
for _, ns := range nss {
if strings.HasSuffix(ns.Host, ".ns.cloudflare.com.") {
l.cloudflare = true
break
}
}
}
}
func (d Domain) ns() string {
addrs, err := net.LookupNS(d.domain)
if err != nil {
return "\nName servers\n" +
"--\n" + err.Error()
}
records := "\nName servers\n" +
"--\n"
for _, val := range addrs {
records += val.Host + "\n"
}
return records
}
func main() {
members := make([]string, 0)
raft.SetLogLevel(0)
flag.Parse()
nameservers := strings.Split(nameserver, ",")
// empty argument given
if len(nameservers) == 1 && nameservers[0] == "" {
nameservers = make([]string, 0)
config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
if err == nil {
for _, s := range config.Servers {
nameservers = append(nameservers, net.JoinHostPort(s, config.Port))
}
} else {
log.Fatal(err)
return
}
}
if discover {
ns, err := net.LookupNS(domain)
if err != nil {
log.Fatal(err)
return
}
if len(ns) < 1 {
log.Fatal("No NS records found for ", domain)
return
}
for _, n := range ns {
members = append(members, strings.TrimPrefix(n.Host, "."))
}
} else if join != "" {
members = strings.Split(join, ",")
}
s := server.NewServer(members, domain, ldns, lhttp, dataDir, rtimeout, wtimeout, secret, nameservers)
stats.Collect()
waiter, err := s.Start()
if err != nil {
log.Fatal(err)
return
}
waiter.Wait()
}
func ns(domain string) (data []byte, err error) {
nss, err := net.LookupNS(domain)
if err != nil {
err = os.ErrNotExist
return
}
buf := bytes.NewBuffer(make([]byte, 0, len(nss)*16))
for _, ns := range nss {
buf.WriteString(ns.Host)
buf.WriteByte('\n')
}
data = buf.Bytes()
return
}
func dns(w http.ResponseWriter, r *http.Request) {
q := r.URL.Query().Get("q")
// Note that the below is NOT safe from input attacks, but that's OK
// because this is just for debugging.
fmt.Fprintf(w, `<html><body>
<form action="/dns">
<input name="q" type="text" value="%v"></input>
<button type="submit">Lookup</button>
</form>
<br/><br/><pre>`, q)
{
res, err := net.LookupNS(q)
spew.Fprintf(w, "LookupNS(%v):\nResult: %#v\nError: %v\n\n", q, res, err)
}
{
res, err := net.LookupTXT(q)
spew.Fprintf(w, "LookupTXT(%v):\nResult: %#v\nError: %v\n\n", q, res, err)
}
{
cname, res, err := net.LookupSRV("", "", q)
spew.Fprintf(w, `LookupSRV("", "", %v):
cname: %v
Result: %#v
Error: %v
`, q, cname, res, err)
}
{
res, err := net.LookupHost(q)
spew.Fprintf(w, "LookupHost(%v):\nResult: %#v\nError: %v\n\n", q, res, err)
}
{
res, err := net.LookupIP(q)
spew.Fprintf(w, "LookupIP(%v):\nResult: %#v\nError: %v\n\n", q, res, err)
}
{
res, err := net.LookupMX(q)
spew.Fprintf(w, "LookupMX(%v):\nResult: %#v\nError: %v\n\n", q, res, err)
}
fmt.Fprintf(w, `</pre>
</body>
</html>`)
}
func main() {
var err error
cmdFlags()
flag.Parse()
if interfaces, err = net.Interfaces(); err != nil {
panic(err)
}
if interfaceAddrs, err = net.InterfaceAddrs(); err != nil {
panic(err)
}
if Options.listInterfaces {
listInterfaces(interfaces)
} else if Options.listInterfaceAddrs {
listInterfaceAddrs(interfaceAddrs)
} else if Options.rdns != "" {
hostnames, _ := net.LookupAddr(Options.rdns)
for _, hostname := range hostnames {
fmt.Println(hostname)
}
} else if Options.ip != "" {
ips, _ := net.LookupIP(Options.ip)
for _, ip := range ips {
fmt.Println(ip)
}
} else if Options.mx != "" {
mxs, _ := net.LookupMX(Options.mx)
for _, mx := range mxs {
fmt.Println(mx.Pref, mx.Host)
}
} else if Options.ns != "" {
nss, _ := net.LookupNS(Options.ns)
for _, ns := range nss {
fmt.Println(ns.Host)
}
} else if Options.txt != "" {
txts, _ := net.LookupTXT(Options.txt)
for _, txt := range txts {
fmt.Println(txt)
}
}
}
func ZoneTransfer(domain string) Results {
results := NewResultSet()
fqdn := dns.Fqdn(domain)
servers, err := net.LookupNS(domain)
if err != nil {
log.Fatal(err)
}
for _, server := range servers {
msg := new(dns.Msg)
msg.SetAxfr(fqdn)
transfer := new(dns.Transfer)
answerChan, err := transfer.In(msg, net.JoinHostPort(server.Host, "53"))
if err != nil {
log.Println(err)
continue
}
for envelope := range answerChan {
if envelope.Error != nil {
log.Println(envelope.Error)
break
}
for _, rr := range envelope.RR {
switch v := rr.(type) {
case *dns.A:
results.Add(strings.TrimRight(v.Header().Name, "."), v.A.String())
case *dns.AAAA:
results.Add(strings.TrimRight(v.Header().Name, "."), v.AAAA.String())
default:
}
}
}
}
return results.Results()
}
func check(domain string, tldPlusOne string) bool {
// check ns record
if len(tldPlusOne) == 0 {
tldPlusOne, _ = publicsuffix.EffectiveTLDPlusOne(domain)
}
nss, err := net.LookupNS(tldPlusOne)
if err != nil {
log.Println("LookupNS failed", tldPlusOne, err)
addToIgnoreList(tldPlusOne, false)
addToIgnoreList(domain, false)
return false
}
for _, v := range nss {
if chinaNS.MatchString(v.Host) {
addToChinaList(tldPlusOne)
return true
}
// check if ns record is belong to china domain
ns := strings.TrimSuffix(strings.TrimSpace(v.Host), ".")
ns, err = publicsuffix.EffectiveTLDPlusOne(domain)
if err == nil && isChina(ns) {
addToChinaList(tldPlusOne)
return true
}
}
// put it in ignores list to avoid double check
addToIgnoreList(tldPlusOne, false)
if len(nss) > 0 {
log.Println("out-china ns server:", nss[0].Host)
}
return false
}
func DiscoverDNS(endpoint *Endpoint) (*m.Check, error) {
domain := endpoint.Host
recordType := "A"
recordName := domain
server := "8.8.8.8"
for {
nameservers, err := net.LookupNS(domain)
if err != nil || len(nameservers) < 1 {
parts := strings.Split(domain, ".")
if len(parts) < 2 {
break
}
domain = strings.Join(parts[1:], ".")
} else {
servers := make([]string, len(nameservers))
for i, ns := range nameservers {
s := strings.TrimSuffix(ns.Host, ".")
servers[i] = s
}
server = strings.Join(servers, ",")
break
}
}
return &m.Check{
Type: "dns",
Frequency: 60,
Settings: map[string]interface{}{
"name": recordName,
"type": recordType,
"server": server,
"timeout": 5,
"protocol": "udp",
},
Enabled: true,
}, nil
}
func configure(hub *StatusHub) {
cfg, err := configRead(*configFile)
if err != nil {
log.Printf("Could not read config file: %s\n", err)
os.Exit(2)
}
hub.MarkConfigurationStart()
wg := &sync.WaitGroup{}
errch := make(chan error, 20)
for _, server := range cfg.Servers.A {
log.Println("Adding", server)
wg.Add(1)
hub.AddNameBackground(server, errch)
}
for _, domain := range cfg.Servers.Domain {
log.Println("Adding NSes for", domain)
nses, err := net.LookupNS(domain)
log.Printf("NSes: %#v: %s\n", nses, err)
for _, ns := range nses {
log.Printf("Adding '%s'\n", ns.Host)
wg.Add(1)
hub.AddNameBackground(ns.Host, errch)
}
}
for _, txtconfig := range cfg.Servers.Txt {
x := strings.SplitN(txtconfig, ",", 2)
txtname := strings.TrimSpace(x[0])
txtbase := strings.TrimSpace(x[1])
log.Println("Adding TXT for", txtname, txtbase)
txts, err := net.LookupTXT(txtname)
log.Printf("TXTs: %#v: %s\n", txts, err)
names := []string{}
for _, txt := range txts {
for _, name := range strings.Split(txt, " ") {
names = append(names, name)
}
}
nameSlice := []string{"", txtbase}
for _, name := range names {
nameSlice[0] = name
hub.AddNameBackground(strings.Join(nameSlice, "."), errch)
}
}
go func() {
for err := range errch {
if err != nil {
log.Println(err)
}
wg.Done()
}
}()
wg.Wait()
close(errch)
hub.MarkConfigurationEnd()
}
func main() {
members := make([]string, 0)
raft.SetLogLevel(0)
flag.Parse()
nameservers := strings.Split(nameserver, ",")
// empty argument given
if len(nameservers) == 1 && nameservers[0] == "" {
nameservers = make([]string, 0)
config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
if err == nil {
for _, s := range config.Servers {
nameservers = append(nameservers, net.JoinHostPort(s, config.Port))
}
} else {
log.Fatal(err)
return
}
}
if discover {
ns, err := net.LookupNS(domain)
if err != nil {
log.Fatal(err)
return
}
if len(ns) < 1 {
log.Fatal("No NS records found for ", domain)
return
}
for _, n := range ns {
members = append(members, strings.TrimPrefix(n.Host, "."))
}
} else if join != "" {
members = strings.Split(join, ",")
}
s := server.NewServer(members, domain, ldns, lhttp, dataDir, rtimeout, wtimeout, secret, nameservers, !norr, tlskey, tlspem)
if dnssec != "" {
k, p, e := server.ParseKeyFile(dnssec)
if e != nil {
log.Fatal(e)
return
}
if k.Header().Name != dns.Fqdn(domain) {
log.Fatal(errors.New("Owner name of DNSKEY must match SkyDNS domain"))
return
}
s.SetKeys(k, p)
}
stats.Collect()
waiter, err := s.Start()
if err != nil {
log.Fatal(err)
return
}
waiter.Wait()
}
func main() {
members := make([]string, 0)
raft.SetLogLevel(0)
flag.Parse()
nameservers := strings.Split(nameserver, ",")
// empty argument given
if len(nameservers) == 1 && nameservers[0] == "" {
nameservers = make([]string, 0)
config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
if err == nil {
for _, s := range config.Servers {
nameservers = append(nameservers, net.JoinHostPort(s, config.Port))
}
} else {
log.Fatal(err)
return
}
}
if discover {
ns, err := net.LookupNS(domain)
if err != nil {
log.Fatal(err)
return
}
if len(ns) < 1 {
log.Fatal("No NS records found for ", domain)
return
}
for _, n := range ns {
members = append(members, strings.TrimPrefix(n.Host, "."))
}
} else if join != "" {
members = strings.Split(join, ",")
}
s := server.NewServer(members, domain, ldns, lhttp, dataDir, rtimeout, wtimeout, secret, nameservers)
// Set up metrics if specified on the command line
if metricsToStdErr {
go metrics.Log(metrics.DefaultRegistry, 60e9, log.New(os.Stderr, "metrics: ", log.Lmicroseconds))
}
if len(graphiteServer) > 1 {
addr, err := net.ResolveTCPAddr("tcp", graphiteServer)
if err != nil {
go metrics.Graphite(metrics.DefaultRegistry, 10e9, "skydns", addr)
}
}
if len(stathatUser) > 1 {
go stathat.Stathat(metrics.DefaultRegistry, 10e9, stathatUser)
}
waiter, err := s.Start()
if err != nil {
log.Fatal(err)
return
}
waiter.Wait()
}
func main() {
// Load the configuration
m := multiconfig.NewWithPath(os.Getenv("config"))
cfg := &dns.Config{}
m.MustLoad(cfg)
// Parse the log level
lvl, err := log.LvlFromString(cfg.LogLevel)
if err != nil {
panic(err)
}
// Create a new logger
l := log.New()
l.SetHandler(
log.LvlFilterHandler(lvl, log.StdoutHandler),
)
// Start the initialization
il := l.New("module", "init")
il.Info("Starting up the application")
// Parse the Redis connection string
url := redisurl.Parse(cfg.Redis)
// Create an options list
opts := []redis.DialOption{}
if url.Database != 0 {
opts = append(opts, redis.DialDatabase(url.Database))
}
if url.Password != "" {
opts = append(opts, redis.DialPassword(url.Password))
}
// Verify the DNS setup
results, err := net.LookupNS(cfg.Domain)
if err != nil {
il.Warn("Unable to look up the NS of domain", "domain", cfg.Domain, "error", err.Error())
}
if len(results) > 0 {
found := false
for _, record := range results {
if record.Host == cfg.Hostname {
found = true
}
}
if !found {
existing := []string{}
for _, record := range results {
existing = append(existing, record.Host)
}
il.Warn("Invalid NS records for the domain", "domain", cfg.Domain, "records", existing)
}
} else {
il.Warn("No NS records found for domain", "domain", cfg.Domain, "error", err.Error())
}
// Dial the server
rc, err := redis.Dial("tcp", url.Host+":"+strconv.Itoa(url.Port), opts...)
if err != nil {
il.Crit("Unable to connect to the Redis server", "error", err.Error())
return
}
// Initialize the DNS server
ds := &dns.DNS{
Config: cfg,
Redis: rc,
}
if err := ds.ListenAndServe(); err != nil {
il.Crit("Error while listening to the specified port", "error", err.Error())
}
}
