func LookupIP(domain string, timeout int) ([]string, error) {
var c dns.Client
var err error
ips := []string{}
domain = strings.TrimRight(domain, ".") + "."
c.DialTimeout = time.Duration(timeout) * time.Millisecond
c.ReadTimeout = time.Duration(timeout) * time.Millisecond
c.WriteTimeout = time.Duration(timeout) * time.Millisecond
m := new(dns.Msg)
m.SetQuestion(domain, dns.TypeA)
ret, _, err := c.Exchange(m, "114.114.114.114:53")
if err != nil {
domain = strings.TrimRight(domain, ".")
e := fmt.Sprintf("lookup error: %s, %s", domain, err.Error())
return ips, errors.New(e)
}
for _, i := range ret.Answer {
result := strings.Split(i.String(), "\t")
if result[3] == "A" && IsIP(result[4]) {
ips = append(ips, result[4])
}
}
return ips, err
}
// NewDNSResolverImpl constructs a new DNS resolver object that utilizes the
// provided list of DNS servers for resolution.
func NewDNSResolverImpl(
readTimeout time.Duration,
servers []string,
caaSERVFAILExceptions map[string]bool,
stats metrics.Scope,
clk clock.Clock,
maxTries int,
) *DNSResolverImpl {
// TODO(jmhodges): make constructor use an Option func pattern
dnsClient := new(dns.Client)
// Set timeout for underlying net.Conn
dnsClient.ReadTimeout = readTimeout
dnsClient.Net = "tcp"
return &DNSResolverImpl{
dnsClient: dnsClient,
servers: servers,
allowRestrictedAddresses: false,
caaSERVFAILExceptions: caaSERVFAILExceptions,
maxTries: maxTries,
clk: clk,
stats: stats,
txtStats: stats.NewScope("TXT"),
aStats: stats.NewScope("A"),
aaaaStats: stats.NewScope("AAAA"),
caaStats: stats.NewScope("CAA"),
mxStats: stats.NewScope("MX"),
}
}
func (this Server) DoDNSquery(m dns.Msg, TransProString string, server []string, timeout time.Duration) (*dns.Msg, error) {
dnsClient := new(dns.Client)
if dnsClient == nil {
return nil, errors.New("Cannot create DNS client")
}
dnsClient.ReadTimeout = timeout
dnsClient.WriteTimeout = timeout
if TransProString != "TCP" && TransProString != "UDP" {
return nil, errors.New("TransProString run")
}
dnsClient.Net = strings.ToLower(TransProString)
ServerStr := server[rand.Intn(len(server))]
ServerAddr := net.ParseIP(ServerStr)
if ServerAddr.To16() != nil {
ServerStr = "[" + ServerStr + "]:" + this.Port
} else if ServerAddr.To4() != nil {
ServerStr = ServerStr + this.Port
} else {
return nil, errors.New("invalid Server Address")
}
dnsResponse, _, err := dnsClient.Exchange(&m, ServerStr)
if err != nil {
return nil, err
}
return dnsResponse, nil
}
func localQuery(mychan chan DNSreply, qname string, qtype uint16) {
var result DNSreply
var trials uint
result.qname = qname
result.qtype = qtype
result.r = nil
result.err = errors.New("No name server to answer the question")
localm := new(dns.Msg)
localm.Id = dns.Id()
localm.RecursionDesired = true
localm.Question = make([]dns.Question, 1)
localm.SetEdns0(EDNSBUFFERSIZE, false) // Even if no EDNS requested, see #9 May be we should retry without it if timeout?
localc := new(dns.Client)
localc.ReadTimeout = timeout
localm.Question[0] = dns.Question{qname, qtype, dns.ClassINET}
Tests:
for trials = 0; trials < uint(*maxTrials); trials++ {
Resolvers:
for serverIndex := range conf.Servers {
server := conf.Servers[serverIndex]
result.nameserver = server
// Brackets around the server address are necessary for IPv6 name servers
r, rtt, err := localc.Exchange(localm, "["+server+"]:"+conf.Port) // Do not use net.JoinHostPort, see https://github.com/bortzmeyer/check-soa/commit/3e4edb13855d8c4016768796b2892aa83eda1933#commitcomment-2355543
if r == nil {
result.r = nil
result.err = err
if strings.Contains(err.Error(), "timeout") {
// Try another resolver
break Resolvers
} else { // We give in
break Tests
}
} else {
result.rtt = rtt
if r.Rcode == dns.RcodeSuccess {
// TODO: as a result, NODATA (NOERROR/ANSWER=0) are silently ignored (try "foo", for instance, the name exists but no IP address)
// TODO: for rcodes like SERVFAIL, trying another resolver could make sense
result.r = r
result.err = nil
break Tests
} else {
// All the other codes are errors. Yes, it may
// happens that one resolver returns REFUSED
// and the others work but we do not handle
// this case. TODO: delete the resolver from
// the list and try another one
result.r = r
result.err = errors.New(dns.RcodeToString[r.Rcode])
break Tests
}
}
}
}
if *debug {
fmt.Printf("DEBUG: end of DNS request \"%s\" / %d\n", qname, qtype)
}
mychan <- result
}
func lookupHost(host string, config *dns.ClientConfig) (addrs []string, err error) {
if utilNet.IsValidIpv4(host) || utilNet.IsValidIpv6(host) {
return []string{host}, nil
}
if host == "localhost" {
return []string{"127.0.0.1", "::1"}, nil
}
c := new(dns.Client)
c.DialTimeout = DialTimeout
c.ReadTimeout = ReadTimeout
c.WriteTimeout = WriteTimeout
m := new(dns.Msg)
m.SetQuestion(dns.Fqdn(host), dns.TypeA)
var r *dns.Msg
for i := 0; i < len(config.Servers); i++ {
r, _, err = c.Exchange(m, config.Servers[i]+":"+config.Port)
if err != nil {
continue
}
err = nil
}
if err != nil {
return nil, e.Forward(err)
}
if r.Rcode != dns.RcodeSuccess {
return nil, e.New("can't resolve %v", host)
}
addrs = make([]string, 0, 10)
for _, a := range r.Answer {
if addr, ok := a.(*dns.A); ok {
addrs = append(addrs, addr.A.String())
}
}
m.SetQuestion(dns.Fqdn(host), dns.TypeAAAA)
for i := 0; i < len(config.Servers); i++ {
r, _, err = c.Exchange(m, config.Servers[0]+":"+config.Port)
if err != nil {
continue
}
err = nil
}
if err != nil {
return nil, e.Forward(err)
}
if r.Rcode != dns.RcodeSuccess {
return nil, e.New("no success")
}
for _, a := range r.Answer {
if addr, ok := a.(*dns.AAAA); ok {
addrs = append(addrs, addr.AAAA.String())
}
}
return
}
func (self *TrivialDnsServer) exchangeWithUpstream(r *dns.Msg) (*dns.Msg, time.Duration, error) {
self.Count("upstream_queries")
c := new(dns.Client)
c.ReadTimeout = CommonTimeout
c.WriteTimeout = CommonTimeout
i := rand.Intn(len(self.Servers))
upstreamServer := self.Servers[i]
response, rtt, err := c.Exchange(r, upstreamServer)
return response, rtt, err
}
func (this ClientProxy) getServerIP() error {
var dns_servers []string
dnsClient := new(dns.Client)
if dnsClient == nil {
return errors.New("Can not new dns Client")
}
dnsClient.WriteTimeout = this.timeout
dnsClient.ReadTimeout = this.timeout
for _, serverstring := range this.SERVERS {
ipaddress := net.ParseIP(serverstring)
if ipaddress != nil {
dns_servers = append(dns_servers, serverstring)
} else {
//used for unitest need to delete after test.
/*if strings.EqualFold(serverstring, "example.com") {
dns_servers = append(dns_servers, "127.0.0.1")
continue
}
IPResult, err := net.LookupIP(serverstring)
if err == nil {
for _, appendStr := range IPResult {
dns_servers = append(dns_servers, appendStr.String())
}
} else {
return err
}*/
dnsResponse, err := searchServerIP(serverstring, 4, this.DNS_SERVERS)
if err != nil {
for i := 0; i < len(dnsResponse.Answer); i++ {
dns_servers = append(dns_servers, dnsResponse.Answer[i].String())
}
} else {
return err
}
dnsResponse, err = searchServerIP(serverstring, 6, this.DNS_SERVERS)
if err == nil {
for i := 0; i < len(dnsResponse.Answer); i++ {
dns_servers = append(dns_servers, "["+dnsResponse.Answer[i].String()+"]")
}
} else {
return err
}
}
}
this.SERVERS = dns_servers
return nil
}
// Returns true if domain has a Name Server associated
func queryNS(domain string, dnsServers []string, proto string) (int, error) {
c := new(dns.Client)
c.ReadTimeout = time.Duration(2 * time.Second)
c.WriteTimeout = time.Duration(2 * time.Second)
c.Net = proto
m := new(dns.Msg)
m.RecursionDesired = true
dnsServer := dnsServers[rand.Intn(len(dnsServers))]
m.SetQuestion(dns.Fqdn(domain), dns.TypeNS)
in, _, err := c.Exchange(m, dnsServer+":53")
if err == nil {
return in.Rcode, err
}
return dns.RcodeRefused, err
}
// our ServeDNS interface, which gets invoked on every DNS message
func (this ServerProxy) ServeDNS(w dns.ResponseWriter, request *dns.Msg) {
// see if we have our groovy custom EDNS0 option
client_supports_appfrag := false
opt := request.IsEdns0()
if opt != nil {
for ofs, e := range opt.Option {
if e.Option() == dns.EDNS0LOCALSTART {
_D("%s QID:%d found EDNS0LOCALSTART", w.RemoteAddr(), request.Id)
client_supports_appfrag = true
// go ahead and use the maximum UDP size for the local communication
// with our server
opt.SetUDPSize(65535)
// remove the fragmentation option
opt.Option = append(opt.Option[0:ofs], opt.Option[ofs+1:]...)
// in principle we should only have one of these options
break
}
}
}
// proxy the query
c := new(dns.Client)
c.ReadTimeout = this.timeout
c.WriteTimeout = this.timeout
response, rtt, err := c.Exchange(request, this.SERVERS[rand.Intn(this.s_len)])
if err != nil {
_D("%s QID:%d error proxying query: %s", w.RemoteAddr(), request.Id, err)
this.SRVFAIL(w, request)
return
}
_D("%s QID:%d request took %s", w.RemoteAddr(), request.Id, rtt)
// if the client does not support fragmentation, we just send the response back and finish
if !client_supports_appfrag {
_D("%s QID:%d sending raw response to client", w.RemoteAddr(), request.Id)
w.WriteMsg(response)
return
}
// otherwise lets get our fragments
all_frags := frag(response)
// send our fragments
for n, frag := range all_frags {
_D("%s QID:%d sending fragment %d", w.RemoteAddr(), request.Id, n)
w.WriteMsg(&frag)
}
}
func LookupIp(ip string) (host string, err error) {
if !utilNet.IsValidIpv4(ip) && !utilNet.IsValidIpv6(ip) {
return "", e.New("not a valid ip address")
}
if ip == "127.0.0.1" || ip == "::1" {
return "localhost", nil
}
config, err := dns.ClientConfigFromFile(ConfigurationFile)
if err != nil {
return "", e.Forward(err)
}
config.Timeout = Timeout
c := new(dns.Client)
c.DialTimeout = DialTimeout
c.ReadTimeout = ReadTimeout
c.WriteTimeout = WriteTimeout
m := new(dns.Msg)
rev, err := dns.ReverseAddr(ip)
if err != nil {
return "", e.Forward(err)
}
m.SetQuestion(rev, dns.TypePTR)
var r *dns.Msg
for i := 0; i < len(config.Servers); i++ {
r, _, err = c.Exchange(m, config.Servers[i]+":"+config.Port)
if err != nil {
continue
}
err = nil
}
if err != nil {
return "", e.Forward(err)
}
if r.Rcode != dns.RcodeSuccess {
return "", e.New("can't resolve %v", ip)
}
for _, a := range r.Answer {
if ptr, ok := a.(*dns.PTR); ok {
return strings.TrimSuffix(ptr.Ptr, "."), nil
}
}
return "", e.New("no ptr available")
}
// defaultExtResolver queries other nameserver, potentially recurses; callers should probably be invoking extResolver
// instead since that's the pluggable entrypoint into external resolution.
func (res *Resolver) defaultExtResolver(r *dns.Msg, nameserver string, proto string, cnt int) (*dns.Msg, error) {
var in *dns.Msg
var err error
c := new(dns.Client)
c.Net = proto
var t time.Duration = 5 * 1e9
if res.config.Timeout != 0 {
t = time.Duration(int64(res.config.Timeout * 1e9))
}
c.DialTimeout = t
c.ReadTimeout = t
c.WriteTimeout = t
in, _, err = c.Exchange(r, nameserver)
if err != nil {
return in, err
}
// recurse
if (in != nil) && (len(in.Answer) == 0) && (!in.MsgHdr.Authoritative) && (len(in.Ns) > 0) && (err != nil) {
if cnt == recurseCnt {
logging.CurLog.NonMesosRecursed.Inc()
}
if cnt > 0 {
if soa, ok := (in.Ns[0]).(*dns.SOA); ok {
return res.defaultExtResolver(r, net.JoinHostPort(soa.Ns, "53"), proto, cnt-1)
}
}
}
return in, err
}
func testSoa(msg *dns.Msg, server string, tries uint) (soa *dns.Msg, err error) {
c := new(dns.Client)
c.ReadTimeout = timeout * 1e9
tests := uint(0)
over := false
for !over {
soa, _, err = c.Exchange(msg, server)
if err != nil {
if e, ok := err.(net.Error); ok && e.Timeout() {
tests++
if tests < tries {
continue
} else {
over = true
}
} else {
over = true
}
} else {
over = true
}
}
return soa, err
}
func (d *DnsQuery) getDnsQueryTime(domain string, server string) (float64, error) {
dnsQueryTime := float64(0)
c := new(dns.Client)
c.ReadTimeout = time.Duration(d.Timeout) * time.Second
m := new(dns.Msg)
recordType, err := d.parseRecordType()
if err != nil {
return dnsQueryTime, err
}
m.SetQuestion(dns.Fqdn(domain), recordType)
m.RecursionDesired = true
r, rtt, err := c.Exchange(m, net.JoinHostPort(server, strconv.Itoa(d.Port)))
if err != nil {
return dnsQueryTime, err
}
if r.Rcode != dns.RcodeSuccess {
return dnsQueryTime, errors.New(fmt.Sprintf("Invalid answer name %s after %s query for %s\n", domain, d.RecordType, domain))
}
dnsQueryTime = float64(rtt.Nanoseconds()) / 1e6
return dnsQueryTime, nil
}
func main() {
var err error
if len(os.Args) != 2 {
fmt.Printf("%s ZONE\n", os.Args[0])
os.Exit(1)
}
conf, err = dns.ClientConfigFromFile("/etc/resolv.conf")
if conf == nil {
fmt.Printf("Cannot initialize the local resolver: %s\n", err)
os.Exit(1)
}
localm = new(dns.Msg)
localm.RecursionDesired = true
localm.Question = make([]dns.Question, 1)
localc = new(dns.Client)
localc.ReadTimeout = TIMEOUT * 1e9
r, err := localQuery(dns.Fqdn(os.Args[1]), dns.TypeNS)
if r == nil {
fmt.Printf("Cannot retrieve the list of name servers for %s: %s\n", dns.Fqdn(os.Args[1]), err)
os.Exit(1)
}
if r.Rcode == dns.RcodeNameError {
fmt.Printf("No such domain %s\n", dns.Fqdn(os.Args[1]))
os.Exit(1)
}
m := new(dns.Msg)
m.RecursionDesired = false
m.Question = make([]dns.Question, 1)
c := new(dns.Client)
c.ReadTimeout = TIMEOUT * 1e9
success := true
numNS := 0
for _, ans := range r.Answer {
switch ans.(type) {
case *dns.NS:
nameserver := ans.(*dns.NS).Ns
numNS += 1
ips := make([]string, 0)
fmt.Printf("%s : ", nameserver)
ra, err := localQuery(nameserver, dns.TypeA)
if ra == nil {
fmt.Printf("Error getting the IPv4 address of %s: %s\n", nameserver, err)
os.Exit(1)
}
if ra.Rcode != dns.RcodeSuccess {
fmt.Printf("Error getting the IPv4 address of %s: %s\n", nameserver, dns.RcodeToString[ra.Rcode])
os.Exit(1)
}
for _, ansa := range ra.Answer {
switch ansa.(type) {
case *dns.A:
ips = append(ips, ansa.(*dns.A).A.String())
}
}
raaaa, err := localQuery(nameserver, dns.TypeAAAA)
if raaaa == nil {
fmt.Printf("Error getting the IPv6 address of %s: %s\n", nameserver, err)
os.Exit(1)
}
if raaaa.Rcode != dns.RcodeSuccess {
fmt.Printf("Error getting the IPv6 address of %s: %s\n", nameserver, dns.RcodeToString[raaaa.Rcode])
os.Exit(1)
}
for _, ansaaaa := range raaaa.Answer {
switch ansaaaa.(type) {
case *dns.AAAA:
ips = append(ips, ansaaaa.(*dns.AAAA).AAAA.String())
}
}
if len(ips) == 0 {
success = false
fmt.Printf("No IP address for this server")
}
for _, ip := range ips {
m.Question[0] = dns.Question{dns.Fqdn(os.Args[1]), dns.TypeSOA, dns.ClassINET}
nsAddressPort := ""
if strings.ContainsAny(":", ip) {
// IPv6 address
nsAddressPort = "[" + ip + "]:53"
} else {
nsAddressPort = ip + ":53"
}
soa, _, err := c.Exchange(m, nsAddressPort)
// TODO: retry if timeout? Otherwise, one lost UDP packet and it is the end
if soa == nil {
success = false
fmt.Printf("%s (%s) ", ip, err)
goto Next
}
if soa.Rcode != dns.RcodeSuccess {
success = false
fmt.Printf("%s (%s) ", ips, dns.RcodeToString[soa.Rcode])
goto Next
}
if len(soa.Answer) == 0 { // May happen if the server is a recursor, not authoritative, since we query with RD=0
success = false
fmt.Printf("%s (0 answer) ", ip)
goto Next
}
rsoa := soa.Answer[0]
switch rsoa.(type) {
case *dns.SOA:
if soa.Authoritative {
// TODO: test if all name servers have the same serial ?
fmt.Printf("%s (%d) ", ips, rsoa.(*dns.SOA).Serial)
} else {
success = false
fmt.Printf("%s (not authoritative) ", ips)
}
}
}
Next:
fmt.Printf("\n")
}
}
if numNS == 0 {
fmt.Printf("No NS records for \"%s\". It is probably a CNAME to a domain but not a zone\n", dns.Fqdn(os.Args[1]))
os.Exit(1)
}
if success {
os.Exit(0)
}
os.Exit(1)
}
func sendNotify(servers []string, domain string) []NotifyResponse {
if !strings.HasSuffix(domain, ".") {
domain = domain + "."
}
if len(servers) == 0 {
fmt.Println("No servers")
resp := NotifyResponse{Result: "No servers", Error: true}
fmt.Println("No servers")
return []NotifyResponse{resp}
}
c := new(dns.Client)
c.ReadTimeout = time.Duration(*timeout) * time.Millisecond
m := new(dns.Msg)
m.SetNotify(domain)
wg := new(sync.WaitGroup)
responseChannel := make(chan NotifyResponse, len(servers))
for _, server := range servers {
go func(server string) {
result := NotifyResponse{Server: server}
wg.Add(1)
defer func() {
wg.Done()
if result.Error || !*quiet {
fmt.Printf("%s: %s\n", result.Server, result.Result)
}
responseChannel <- result
}()
target, err := fixupHost(server)
if err != nil {
result.Result = fmt.Sprintf("%s: %s", server, err)
fmt.Println(result.Result)
result.Error = true
return
}
result.Server = target
if *verbose {
fmt.Println("Sending notify to", target)
}
resp, rtt, err := c.Exchange(m, target)
if err != nil {
result.Error = true
result.Result = err.Error()
return
}
ok := "ok"
if !resp.Authoritative {
ok = fmt.Sprintf("not ok (%s)", dns.RcodeToString[resp.Rcode])
}
result.Result = fmt.Sprintf("%s: %s (%s)",
target, ok, rtt.String())
responseChannel <- result
}(server)
}
responses := make([]NotifyResponse, len(servers))
for i := 0; i < len(servers); i++ {
responses[i] = <-responseChannel
}
wg.Wait()
return responses
}
func soaQuery(mychan chan SOAreply, zone string, name string, server string) {
var result SOAreply
var trials uint
result.retrieved = false
result.name = name
result.address = server
result.msg = "UNKNOWN"
m := new(dns.Msg)
if !*noedns {
m.SetEdns0(EDNSBUFFERSIZE, !*nodnssec)
}
m.Id = dns.Id()
if *recursion {
m.RecursionDesired = true
} else {
m.RecursionDesired = false
}
m.Question = make([]dns.Question, 1)
c := new(dns.Client)
c.ReadTimeout = timeout // Seems ignored for TCP?
if *tcp {
c.Net = "tcp"
}
m.Question[0] = dns.Question{zone, dns.TypeSOA, dns.ClassINET}
nsAddressPort := ""
nsAddressPort = net.JoinHostPort(server, "53")
if *debug {
fmt.Printf("DEBUG Querying SOA from %s\n", nsAddressPort)
}
for trials = 0; trials < uint(*maxTrials); trials++ {
soa, rtt, err := c.Exchange(m, nsAddressPort)
if soa == nil {
result.rtt = 0
result.msg = fmt.Sprintf("%s", err.Error())
} else {
result.rtt = rtt
if soa.Rcode != dns.RcodeSuccess {
result.msg = dns.RcodeToString[soa.Rcode]
break
} else {
if len(soa.Answer) == 0 { /* May happen if the server is a recursor, not authoritative, since we query with RD=0 */
result.msg = "0 answer"
break
} else {
gotSoa := false
for _, rsoa := range soa.Answer {
switch rsoa.(type) {
case *dns.SOA:
if *noauthrequired || soa.MsgHdr.Authoritative {
result.retrieved = true
result.serial = rsoa.(*dns.SOA).Serial
result.msg = "OK"
} else {
result.msg = "Not authoritative"
}
gotSoa = true
case *dns.CNAME: /* Bad practice but common */
fmt.Printf("Apparently not a zone but an alias\n")
os.Exit(1)
case *dns.RRSIG:
/* Ignore them. See bug #8 */
default:
// TODO: a name server can send us other RR types.
fmt.Printf("Internal error when processing %s, unexpected record type\n", rsoa)
os.Exit(1)
}
}
if !gotSoa {
result.msg = "No SOA record in reply"
}
break
}
}
break // We got a reply
}
}
mychan <- result
}
//not sure how to make a server fail, error 501?
func (this Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
TransProString := r.Header.Get("X-Proxy-DNS-Transport")
if TransProString == "tcp" {
this.TransPro = TCPcode
} else if TransProString == "udp" {
this.TransPro = UDPcode
} else {
_D("Transport protol not udp or tcp")
http.Error(w, "unknown transport protocol", 415)
return
}
contentTypeStr := r.Header.Get("Content-Type")
if contentTypeStr != "application/X-DNSoverHTTP" {
_D("Content-Type illegal")
http.Error(w, "unknown content type", 415)
return
}
var requestBody []byte
requestBody, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(w, "error in reading request", 400)
_D("error in reading HTTP request, error message: %s", err)
return
}
if len(requestBody) < (int)(r.ContentLength) {
http.Error(w, "error in reading request", 400)
_D("fail to read all HTTP content")
return
}
var dnsRequest dns.Msg
err = dnsRequest.Unpack(requestBody)
if err != nil {
http.Error(w, "bad DNS request", 400)
_D("error in packing HTTP response to DNS, error message: %s", err)
return
}
dnsClient := new(dns.Client)
if dnsClient == nil {
http.Error(w, "Server Error", 500)
_D("cannot create DNS client")
return
}
dnsClient.ReadTimeout = this.timeout
dnsClient.WriteTimeout = this.timeout
dnsClient.Net = TransProString
//will use a parameter to let user address resolver in future
dnsResponse, RTT, err := dnsClient.Exchange(&dnsRequest, this.SERVERS[rand.Intn(len(this.SERVERS))])
//dnsResponse, RTT, err := dnsClient.Exchange(&dnsRequest, this.SERVERS[0])
if err != nil {
_D("error in communicate with resolver, error message: %s", err)
http.Error(w, "Server Error", 500)
return
} else {
_D("request took %s", RTT)
}
if dnsResponse == nil {
_D("no response back")
http.Error(w, "Server Error:No Recursive response", 500)
return
}
response_bytes, err := dnsResponse.Pack()
if err != nil {
http.Error(w, "error packing reply", 500)
_D("error in packing request, error message: %s", err)
return
}
_, err = w.Write(response_bytes)
if err != nil {
_D("Can not write response rightly, error message: %s", err)
return
}
//don't know how to creat a response here
}