func (r *resolver) handleIPQuery(name string, query *dns.Msg, ipType int) (*dns.Msg, error) {
addr, ipv6Miss := r.sb.ResolveName(name, ipType)
if addr == nil && ipv6Miss {
// Send a reply without any Answer sections
log.Debugf("Lookup name %s present without IPv6 address", name)
resp := createRespMsg(query)
return resp, nil
}
if addr == nil {
return nil, nil
}
log.Debugf("Lookup for %s: IP %v", name, addr)
resp := createRespMsg(query)
if len(addr) > 1 {
addr = shuffleAddr(addr)
}
if ipType == types.IPv4 {
for _, ip := range addr {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr.A = ip
resp.Answer = append(resp.Answer, rr)
}
} else {
for _, ip := range addr {
rr := new(dns.AAAA)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: respTTL}
rr.AAAA = ip
resp.Answer = append(resp.Answer, rr)
}
}
return resp, nil
}
func (r *resolver) handleSRVQuery(svc string, query *dns.Msg) (*dns.Msg, error) {
srv, ip := r.backend.ResolveService(svc)
if len(srv) == 0 {
return nil, nil
}
if len(srv) != len(ip) {
return nil, fmt.Errorf("invalid reply for SRV query %s", svc)
}
resp := createRespMsg(query)
for i, r := range srv {
rr := new(dns.SRV)
rr.Hdr = dns.RR_Header{Name: svc, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: respTTL}
rr.Port = r.Port
rr.Target = r.Target
resp.Answer = append(resp.Answer, rr)
rr1 := new(dns.A)
rr1.Hdr = dns.RR_Header{Name: r.Target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr1.A = ip[i]
resp.Extra = append(resp.Extra, rr1)
}
return resp, nil
}
func (s *DNSServer) handleARequest(r *dns.Msg, m *dns.Msg) {
m.Answer = make([]dns.RR, 0, 2)
query := r.Question[0].Name
if query[len(query)-1] == '.' {
query = query[:len(query)-1]
}
for service := range s.queryServices(query) {
rr := new(dns.A)
var ttl int
if service.Ttl != -1 {
ttl = service.Ttl
} else {
ttl = s.config.ttl
}
rr.Hdr = dns.RR_Header{
Name: r.Question[0].Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: uint32(ttl),
}
rr.A = service.Ip
m.Answer = append(m.Answer, rr)
}
}
func (c *Config) GenerateServeDNS(hostname string) func(dns.ResponseWriter, *dns.Msg) {
if len(hostname) > 0 {
if hostname[len(hostname)-1] != '.' {
hostname += "."
}
}
return func(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative = true
ip, err := c.GetOrLaunchInstance()
if err != nil {
// TODO: error handling
log.Println("Error in GetOrLaunchInstance:", err)
w.Close()
return
}
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: hostname, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: uint32(c.MaxIdleTime.Seconds())}
rr.A = ip
m.Answer = []dns.RR{rr}
w.WriteMsg(m)
}
}
func (r *resolver) handleIPQuery(name string, query *dns.Msg, ipType int) (*dns.Msg, error) {
addr := r.sb.ResolveName(name, ipType)
if addr == nil {
return nil, nil
}
log.Debugf("Lookup for %s: IP %v", name, addr)
resp := new(dns.Msg)
resp.SetReply(query)
setCommonFlags(resp)
if len(addr) > 1 {
addr = shuffleAddr(addr)
}
if ipType == netutils.IPv4 {
for _, ip := range addr {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr.A = ip
resp.Answer = append(resp.Answer, rr)
}
} else {
for _, ip := range addr {
rr := new(dns.AAAA)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: respTTL}
rr.AAAA = ip
resp.Answer = append(resp.Answer, rr)
}
}
return resp, nil
}
// DNS requests go to this function
func dnsHandle(w dns.ResponseWriter, r *dns.Msg) {
name := r.Question[0].Name
if !namePattern.MatchString(name) {
kilog.Debug("%v does not match pattern, forwarding", name)
dnsForward(w, r)
return
}
// otherwise
kilog.Debug("%v matches pattern, handling", name)
dnsLock.Lock()
defer dnsLock.Unlock()
// check in table first
fakeIP, ok := nameToIP[name]
if !ok {
// place in table
var nwIP string
for {
haha := ipAlloc().String()
_, exists := ipToName[haha]
if exists {
continue
}
nwIP = haha
break
}
fakeIP = nwIP
nameToIP[name] = fakeIP
ipToName[fakeIP] = name
// remove in 30 minutes
go func() {
time.Sleep(time.Minute * 30)
dnsLock.Lock()
defer dnsLock.Unlock()
delete(nameToIP, name)
delete(ipToName, fakeIP)
}()
}
// return the fake IP to the user
resp := new(dns.A)
resp.Hdr.Name = name
resp.Hdr.Ttl = 1 // very short
resp.Hdr.Class = dns.ClassINET
resp.Hdr.Rrtype = dns.TypeA
resp.A = net.ParseIP(fakeIP)
towrite := new(dns.Msg)
towrite.Id = r.Id
towrite.RecursionAvailable = true
towrite.RecursionDesired = true
towrite.Response = true
towrite.Question = r.Question
towrite.Answer = make([]dns.RR, 1)
towrite.Answer[0] = resp
w.WriteMsg(towrite)
kilog.Debug("returning mapping %v -> %v", name, fakeIP)
}
func newRR(host string, addr net.IP) dns.RR {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{
Name: host,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0}
rr.A = addr.To4()
return rr
}
// hijackResponse returns a modified version on the input dns.Msg with the A record modified
// to point to our server
func hijackResponse(r *dns.Msg) (m *dns.Msg) {
m = new(dns.Msg)
m.SetReply(r)
m.Answer = make([]dns.RR, 1)
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: m.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 600}
rr.A = net.ParseIP(config.EXTERNAL_ADDRESS)
m.Answer[0] = rr
return m
}
func dnsAddressRecord(query *dns.Msg, name string, addrs []net.IP) *dns.Msg {
resp := new(dns.Msg)
resp.SetReply(query)
for _, addr := range addrs {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
rr.A = addr
resp.Answer = append(resp.Answer, rr)
}
return resp
}
func (r *resolver) handleIPv4Query(name string, query *dns.Msg) (*dns.Msg, error) {
addr := r.sb.ResolveName(name)
if addr == nil {
return nil, nil
}
log.Debugf("Lookup for %s: IP %s", name, addr.String())
resp := new(dns.Msg)
resp.SetReply(query)
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr.A = addr
resp.Answer = append(resp.Answer, rr)
return resp, nil
}
/* ----------------------------------------------------------------------------
FUNCTION
Name: Serve Response
Prototype: func serveResponse(w dns.ResponseWriter, r *dns.Msg)
Developer: Andrew Burian
Created On: 2015-09-24
Parameters:
w dns.ResponseWriter
the writer that will respond to the dns query
r dns.Msg
the dns query to respond to
Return Values:
(none)
Description:
Handles a single dns request by generating and writing
a response to the provided writer.
Also strips out the contained data and sends it over a
channel
Revisions:
(none)
---------------------------------------------------------------------------- */
func serveResponse(w dns.ResponseWriter, r *dns.Msg) {
// create a message to respond with
respMsg := new(dns.Msg)
// set this message to be a response to the first
respMsg.SetReply(r)
// create a new record to respond with
respRec := new(dns.A)
respRec.Hdr = dns.RR_Header{
Name: r.Question[0].Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0} // 0 TTL to avoid caching
// pseudo random IP
rand_bytes := make([]byte, 4)
rand.Read(rand_bytes)
respRec.A = rand_bytes
respMsg.Answer = append(respMsg.Answer, respRec)
w.WriteMsg(respMsg)
// now that the response has been handled
// process the covert data
// get the data from the query
data := (strings.Split(r.Question[0].Name, "."))[0]
// create the new message channel
datachan := make(chan byte, len(data))
// send it to the main
messages <- datachan
// read all the bytes into the channel
for _, b := range []byte(data) {
datachan <- b
}
close(datachan)
}
func route(w dns.ResponseWriter, req *dns.Msg) {
if len(req.Question) != 1 {
failWithRcode(w, req, dns.RcodeRefused)
return
}
question := req.Question[0]
qtype := question.Qtype
if question.Qclass != dns.ClassINET {
failWithRcode(w, req, dns.RcodeRefused)
return
}
remoteIP := w.RemoteAddr().(*net.UDPAddr).IP
m := new(dns.Msg)
m.Id = req.Id
switch qtype {
case dns.TypeA:
if remoteIP4 := remoteIP.To4(); remoteIP4 != nil {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: question.Name, Rrtype: question.Qtype,
Class: dns.ClassINET, Ttl: 10}
rr.A = remoteIP4
m.Answer = []dns.RR{rr}
}
case dns.TypeAAAA:
if remoteIP16 := remoteIP.To16(); remoteIP16 != nil {
rr := new(dns.AAAA)
rr.Hdr = dns.RR_Header{Name: question.Name, Rrtype: question.Qtype,
Class: dns.ClassINET, Ttl: 10}
rr.AAAA = remoteIP16
m.Answer = []dns.RR{rr}
}
case dns.TypeTXT:
rr := new(dns.TXT)
rr.Hdr = dns.RR_Header{Name: question.Name, Rrtype: question.Qtype,
Class: dns.ClassINET, Ttl: 10}
rr.Txt = []string{fmt.Sprintf("Resolver IP: %v", remoteIP.String())}
m.Answer = []dns.RR{rr}
}
m.Question = req.Question
m.Response = true
m.Authoritative = true
w.WriteMsg(m)
}
func parseValue(t uint16, value string, h dns.RR_Header) dns.RR {
switch t {
case dns.TypeA:
a := new(dns.A)
a.Hdr = h
a.A, _ = parseA(value)
return a
case dns.TypeAAAA:
aaaa := new(dns.AAAA)
aaaa.Hdr = h
aaaa.AAAA, _ = parseAAAA(value)
return aaaa
case dns.TypeSRV:
srv := new(dns.SRV)
srv.Hdr = h
srv.Priority, srv.Weight, srv.Port, srv.Target, _ = parseSRV(value)
return srv
}
return nil
}
func (s *DNSServer) makeServiceA(n string, service *Service) dns.RR {
rr := new(dns.A)
var ttl int
if service.Ttl != -1 {
ttl = service.Ttl
} else {
ttl = s.config.ttl
}
rr.Hdr = dns.RR_Header{
Name: n,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: uint32(ttl),
}
rr.A = service.Ip
return rr
}
func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
q := r.Question[0]
info := fmt.Sprintf("Question: Type=%s Class=%s Name=%s", dns.TypeToString[q.Qtype], dns.ClassToString[q.Qclass], q.Name)
if q.Qtype == dns.TypeA && q.Qclass == dns.ClassINET {
m := new(dns.Msg)
m.SetReply(r)
a := new(dns.A)
a.Hdr = dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 600}
a.A = resolveIP
m.Answer = []dns.RR{a}
w.WriteMsg(m)
log.Printf("%s (RESOLVED)\n", info)
} else {
m := new(dns.Msg)
m.SetReply(r)
m.Rcode = dns.RcodeNameError // NXDOMAIN
w.WriteMsg(m)
log.Printf("%s (NXDOMAIN)\n", info)
}
}
func answerA(q dns.Question, value net.IP) dns.RR {
answer := new(dns.A)
answer.Header().Name = q.Name
answer.Header().Rrtype = dns.TypeA
answer.Header().Class = dns.ClassINET
answer.A = value
return answer
}
func answerA(q *dns.Question, v *DNSValue) dns.RR {
answer := new(dns.A)
answer.Header().Name = q.Name
answer.Header().Rrtype = dns.TypeA
answer.Header().Class = dns.ClassINET
answer.A = net.ParseIP(v.Value)
return answer
}
func (s *server) AddressRecords(q dns.Question, name string) (records []dns.RR, err error) {
results, err := s.hosts.FindHosts(name)
if err != nil {
return nil, err
}
for _, ip := range results {
switch {
case ip.To4() != nil && (q.Qtype == dns.TypeA || q.Qtype == dns.TypeANY):
r := new(dns.A)
r.Hdr = dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA,
Class: dns.ClassINET, Ttl: s.config.HostsTtl}
r.A = ip.To4()
records = append(records, r)
case ip.To4() == nil && (q.Qtype == dns.TypeAAAA || q.Qtype == dns.TypeANY):
r := new(dns.AAAA)
r.Hdr = dns.RR_Header{Name: q.Name, Rrtype: dns.TypeAAAA,
Class: dns.ClassINET, Ttl: s.config.HostsTtl}
r.AAAA = ip.To16()
records = append(records, r)
}
}
return records, nil
}
func (c *config) flattenCNAME(in *dns.CNAME) ([]dns.RR, error) { // TODO: cache CNAME lookups
h := in.Header()
answers := []dns.RR{}
m := new(dns.Msg)
m.SetQuestion(in.Target, dns.TypeA)
m.RecursionDesired = true
d := new(dns.Client)
record, _, err := d.Exchange(m, c.resolver) // TODO: try multiple resolvers
if err != nil {
return nil, err
}
if record == nil || record.Rcode == dns.RcodeNameError || record.Rcode != dns.RcodeSuccess {
return nil, fmt.Errorf("Record error code %s: %s", record.Rcode, err.Error())
}
for _, a := range record.Answer {
if r, ok := a.(*dns.A); ok {
out := new(dns.A)
out.Hdr = dns.RR_Header{Name: h.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 300}
out.A = r.A
answers = append(answers, out)
}
}
return answers, nil
}
func (s *SenseDNS) fillWithData(pairs api.KVPairs, network string) {
zs := s.dnsServer.zones
zs.Lock()
defer zs.Unlock()
key := s.dnsServer.getNetDomain(network)
zs.store[key] = make(map[dns.RR_Header][]dns.RR)
for _, value := range pairs {
path := strings.Split(value.Key, "/")
hostname := fmt.Sprintf("%s.%s.%s", path[3], network, s.dnsServer.networkTLD)
ip := string(value.Value)
rr := new(dns.A)
rr.A = net.ParseIP(ip)
rr.Hdr = dns.RR_Header{Name: dns.Fqdn(hostname), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 3600}
key2 := dns.RR_Header{Name: dns.Fqdn(rr.Header().Name), Rrtype: rr.Header().Rrtype, Class: rr.Header().Class}
zs.store[key][key2] = append(zs.store[key][key2], rr)
}
if log.Level == logrus.DebugLevel {
s.dnsServer.printRoutingTable()
}
}
func dnsHandler(w dns.ResponseWriter, r *dns.Msg) {
defer w.Close()
m := new(dns.Msg)
m.SetReply(r)
m.Compress = false
for _, q := range r.Question {
fmt.Printf("dns-srv: Query -- [%s] %s\n", q.Name, dns.TypeToString[q.Qtype])
switch q.Qtype {
case dns.TypeA:
record := new(dns.A)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0,
}
record.A = net.ParseIP("127.0.0.1")
m.Answer = append(m.Answer, record)
case dns.TypeMX:
record := new(dns.MX)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeMX,
Class: dns.ClassINET,
Ttl: 0,
}
record.Mx = "mail." + q.Name
record.Preference = 10
m.Answer = append(m.Answer, record)
}
}
w.WriteMsg(m)
return
}
func proxyServe(w dns.ResponseWriter, req *dns.Msg) {
var (
key string
m *dns.Msg
err error
tried bool
data []byte
id uint16
query []string
questions []dns.Question
used string
)
defer func() {
if err := recover(); err != nil {
fmt.Println(err)
}
}()
if req.MsgHdr.Response == true {
return
}
query = make([]string, len(req.Question))
for i, q := range req.Question {
if q.Qtype != dns.TypeAAAA || *ipv6 {
questions = append(questions, q)
}
query[i] = fmt.Sprintf("(%s %s %s)", q.Name, dns.ClassToString[q.Qclass], dns.TypeToString[q.Qtype])
}
if len(questions) == 0 {
return
}
//check local map
dom := req.Question[0].Name
domain := dom[0 : len(dom)-1]
v, ok := localMap[domain]
if ok {
tm := new(dns.Msg)
tm.Id = req.Id
tm.Answer = make([]dns.RR, 1)
dom := req.Question[0].Name
trr := new(dns.A)
trr.Hdr = dns.RR_Header{Name: dom, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}
trr.A = net.ParseIP(v)
tm.Answer[0] = trr
err = w.WriteMsg(tm)
if DEBUG > 0 {
log.Printf("hosts:%v ip:%v\n", domain, v)
}
goto end
}
req.Question = questions
id = req.Id
req.Id = 0
key = toMd5(req.String())
req.Id = id
if ENCACHE {
if reply, ok := conn.Get(key); ok {
data, _ = reply.([]byte)
}
if data != nil && len(data) > 0 {
m = &dns.Msg{}
m.Unpack(data)
m.Id = id
err = w.WriteMsg(m)
if DEBUG > 0 {
log.Printf("id:%5d cache: HIT %v\n", id, query)
}
goto end
} else {
if DEBUG > 0 {
log.Printf("id: %5d cache: MISS %v\n", id, query)
}
}
}
for i, parts := range DNS {
dns := parts[0]
proto := parts[1]
tried = i > 0
if DEBUG > 0 {
if tried {
log.Printf("id: 5%d try: %v %s %s\n", id, query, dns, proto)
} else {
log.Printf("id: 5%d resolve: %v %s %s\n", id, query, dns, proto)
}
}
client := clientUDP
if proto == "tcp" {
client = clientTCP
}
m, _, err = client.Exchange(req, dns)
if err == nil && len(m.Answer) > 0 {
used = dns
break
}
}
if err == nil {
if DEBUG > 0 {
if tried {
if len(m.Answer) == 0 {
log.Printf("id: %5d failed: %v\n", id, query)
} else {
log.Printf("id: %5d bingo: %v %s\n", id, query, used)
}
}
}
data, err = m.Pack()
if err == nil {
_, err = w.Write(data)
if err == nil {
if ENCACHE {
m.Id = 0
data, _ = m.Pack()
ttl := 0
if len(m.Answer) > 0 {
ttl = int(m.Answer[0].Header().Ttl)
if ttl < 0 {
ttl = 0
}
}
conn.Set(key, data, time.Second*time.Duration(ttl))
m.Id = id
if DEBUG > 0 {
log.Printf("id: %5d cache: CACHED %v TTL %v\n", id, query, ttl)
}
}
}
}
}
end:
if DEBUG > 1 {
fmt.Println(req)
if m != nil {
fmt.Println(m)
}
}
if err != nil {
log.Printf("id: %5d error: %v %s\n", id, query, err)
}
if DEBUG > 1 {
fmt.Println("======================================")
}
}
func (s *server) AddressRecords(q dns.Question) (records []dns.RR, err error) {
name := strings.ToLower(q.Name)
if name == "master."+s.config.Domain || name == s.config.Domain {
for _, m := range s.client.GetCluster() {
u, e := url.Parse(m)
if e != nil {
continue
}
h, _, e := net.SplitHostPort(u.Host)
if e != nil {
continue
}
ip := net.ParseIP(h)
switch {
case ip.To4() != nil && q.Qtype == dns.TypeA:
records = append(records, &dns.A{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: s.Ttl}, A: ip.To4()})
case ip.To4() == nil && q.Qtype == dns.TypeAAAA:
records = append(records, &dns.AAAA{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: s.Ttl}, AAAA: ip.To16()})
}
}
return
}
r, err := s.client.Get(path(name), false, true)
if err != nil {
println(err.Error())
return nil, err
}
var serv *Service
if !r.Node.Dir { // single element
if err := json.Unmarshal([]byte(r.Node.Value), &serv); err != nil {
log.Printf("error: Failure to parse value: %q", err)
return nil, err
}
ip := net.ParseIP(serv.Host)
ttl := uint32(r.Node.TTL)
if ttl == 0 {
ttl = s.Ttl
}
switch {
case ip == nil:
case ip.To4() != nil && q.Qtype == dns.TypeA:
a := new(dns.A)
a.Hdr = dns.RR_Header{Name: q.Name, Rrtype: q.Qtype, Class: dns.ClassINET, Ttl: ttl}
a.A = ip.To4()
records = append(records, a)
case ip.To4() == nil && q.Qtype == dns.TypeAAAA:
aaaa := new(dns.AAAA)
aaaa.Hdr = dns.RR_Header{Name: q.Name, Rrtype: q.Qtype, Class: dns.ClassINET, Ttl: ttl}
aaaa.AAAA = ip.To16()
records = append(records, aaaa)
}
return records, nil
}
for _, serv := range s.loopNodes(&r.Node.Nodes) {
ip := net.ParseIP(serv.Host)
switch {
case ip == nil:
case ip.To4() != nil && q.Qtype == dns.TypeA:
a := new(dns.A)
a.Hdr = dns.RR_Header{Name: q.Name, Rrtype: q.Qtype, Class: dns.ClassINET, Ttl: uint32(r.Node.TTL)}
a.A = ip.To4()
records = append(records, a)
case ip.To4() == nil && q.Qtype == dns.TypeAAAA:
aaaa := new(dns.AAAA)
aaaa.Hdr = dns.RR_Header{Name: q.Name, Rrtype: q.Qtype, Class: dns.ClassINET, Ttl: uint32(r.Node.TTL)}
aaaa.AAAA = ip.To16()
records = append(records, aaaa)
}
}
if s.config.RoundRobin {
switch l := len(records); l {
case 2:
if dns.Id()%2 == 0 {
records[0], records[1] = records[1], records[0]
}
default:
// Do a minimum of l swap, maximum of 4l swaps
for j := 0; j < l*(int(dns.Id())%4+1); j++ {
q := int(dns.Id()) % l
p := int(dns.Id()) % l
if q == p {
p = (p + 1) % l
}
records[q], records[p] = records[p], records[q]
}
}
}
return records, nil
}
func handleDnsRequest(w dns.ResponseWriter, req *dns.Msg) {
r := new(dns.Msg)
r.SetReply(req)
r.Authoritative = true
if len(req.Question) > 1 || req.Rcode != dns.OpcodeQuery {
r.SetRcode(req, dns.RcodeNotImplemented)
}
if len(req.Question) == 0 {
r.SetRcode(req, dns.RcodeFormatError)
}
if r.Rcode != dns.RcodeSuccess {
w.WriteMsg(r)
dnsReportChan <- 1
return
}
q := req.Question[0]
log.Debug("dns server: question=%v type=%v remote_host=%v", q.Name, q.Qtype, w.RemoteAddr())
switch q.Qtype {
case dns.TypeA:
h, _ := randomHost()
if h == "" || !isIPv4(h) {
if *f_randomhosts {
h = randomIPv4Addr()
} else {
// return NXDOMAIN
r.SetRcode(req, dns.RcodeNameError)
break
}
}
resp := new(dns.A)
resp.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: ttl,
}
resp.A = net.ParseIP(h)
r.Answer = append(r.Answer, resp)
case dns.TypeAAAA:
h, _ := randomHost()
if h == "" || !isIPv6(h) {
if *f_randomhosts {
h = randomIPv6Addr()
} else {
// return NXDOMAIN
r.SetRcode(req, dns.RcodeNameError)
break
}
}
resp := new(dns.AAAA)
resp.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: ttl,
}
resp.AAAA = net.ParseIP(h)
r.Answer = append(r.Answer, resp)
case dns.TypeCNAME:
resp := new(dns.CNAME)
resp.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeCNAME,
Class: dns.ClassINET,
Ttl: ttl,
}
resp.Target = fmt.Sprintf("cname.%s", q.Name)
r.Answer = append(r.Answer, resp)
case dns.TypeMX:
resp := new(dns.MX)
resp.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeMX,
Class: dns.ClassINET,
Ttl: ttl,
}
resp.Mx = fmt.Sprintf("mx.%s", q.Name)
r.Answer = append(r.Answer, resp)
case dns.TypeSOA:
resp := new(dns.SOA)
resp.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeSOA,
Class: dns.ClassINET,
Ttl: ttl,
}
resp.Ns = fmt.Sprintf("ns.%s", q.Name)
resp.Mbox = fmt.Sprintf("admin-%s", q.Name)
r.Answer = append(r.Answer, resp)
}
w.WriteMsg(r)
dnsReportChan <- 1
}
// TODO(axw) define an error for "no answer"
func (s *jujuNameServer) answer(q dns.Question) (dns.RR, error) {
if q.Qtype != dns.TypeA {
return nil, nil
}
var envName string
entityName := strings.ToLower(strings.TrimSuffix(q.Name, "."+zone))
if i := strings.IndexRune(entityName, '.'); i >= 0 {
envName = entityName[i+1:]
entityName = entityName[:i]
} else {
var err error
envName, err = envcmd.GetDefaultEnvironment()
if err != nil {
return nil, err
}
}
// TODO(axw) cache API connection
api, err := s.openAPI(envName)
if err != nil {
return nil, err
}
defer api.Close()
client := api.Client()
// If the entity name parses as a tag, extract the ID. This enables
// us to address "unit-mysql-0", where we couldn't otherwise, since
// slashes are not allowed in domain names. Similarly for container
// machines (e.g. to address "0/lxc/0", pass "machine-0-lxc-0").
if tag, err := names.ParseTag(entityName); err == nil {
entityName = tag.Id()
}
var addr string
if names.IsValidService(entityName) {
status, err := client.Status([]string{entityName})
if err != nil {
return nil, err
}
service := status.Services[entityName]
addresses := make([]string, 0, len(service.Units))
for _, unit := range service.Units {
if unit.PublicAddress == "" {
continue
}
if includeLost || unit.UnitAgent.Status != "lost" {
addresses = append(addresses, unit.PublicAddress)
}
}
// Might be nice to have additional info in TXT?
if len(addresses) == 0 {
return nil, nil
}
addr = addresses[rand.Intn(len(addresses))]
} else {
// Assume it's a machine or unit name.
addr, err = client.PublicAddress(entityName)
if err != nil {
return nil, err
}
}
ip := net.ParseIP(addr)
if ip != nil {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0,
}
rr.A = ip
return rr, nil
} else {
rr := new(dns.CNAME)
rr.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeCNAME,
Class: dns.ClassINET,
Ttl: 0,
}
rr.Target = addr + "."
return rr, nil
}
}
func (ts *testSrv) dnsHandler(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
m.Compress = false
// Normally this test DNS server will return 127.0.0.1 for everything.
// However, in some situations (for instance Docker), it's useful to return a
// different hardcoded host. You can do so by setting the FAKE_DNS environment
// variable.
fakeDNS := os.Getenv("FAKE_DNS")
if fakeDNS == "" {
fakeDNS = "127.0.0.1"
}
for _, q := range r.Question {
fmt.Printf("dns-srv: Query -- [%s] %s\n", q.Name, dns.TypeToString[q.Qtype])
switch q.Qtype {
case dns.TypeA:
record := new(dns.A)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 0,
}
record.A = net.ParseIP(fakeDNS)
m.Answer = append(m.Answer, record)
case dns.TypeMX:
record := new(dns.MX)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeMX,
Class: dns.ClassINET,
Ttl: 0,
}
record.Mx = "mail." + q.Name
record.Preference = 10
m.Answer = append(m.Answer, record)
case dns.TypeTXT:
ts.mu.RLock()
value, present := ts.txtRecords[q.Name]
ts.mu.RUnlock()
if !present {
continue
}
record := new(dns.TXT)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeTXT,
Class: dns.ClassINET,
Ttl: 0,
}
record.Txt = []string{value}
m.Answer = append(m.Answer, record)
case dns.TypeCAA:
if q.Name == "bad-caa-reserved.com." || q.Name == "good-caa-reserved.com." {
record := new(dns.CAA)
record.Hdr = dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeCAA,
Class: dns.ClassINET,
Ttl: 0,
}
record.Tag = "issue"
if q.Name == "bad-caa-reserved.com." {
record.Value = "sad-hacker-ca.invalid"
} else if q.Name == "good-caa-reserved.com." {
record.Value = "happy-hacker-ca.invalid"
}
m.Answer = append(m.Answer, record)
}
}
}
auth := new(dns.SOA)
auth.Hdr = dns.RR_Header{Name: "boulder.invalid.", Rrtype: dns.TypeSOA, Class: dns.ClassINET, Ttl: 0}
auth.Ns = "ns.boulder.invalid."
auth.Mbox = "master.boulder.invalid."
auth.Serial = 1
auth.Refresh = 1
auth.Retry = 1
auth.Expire = 1
auth.Minttl = 1
m.Ns = append(m.Ns, auth)
w.WriteMsg(m)
return
}
// updateDNS updates the current slices of dns.RR so incoming requests get a
// fast answer
func updateDNS(s *dnsseeder) {
var rr4std, rr4non, rr6std, rr6non []dns.RR
s.mtx.RLock()
// loop over each dns recprd type we need
for t := range []int{dnsV4Std, dnsV4Non, dnsV6Std, dnsV6Non} {
// FIXME above needs to be convertwd into one scan of theList if possible
numRR := 0
for _, nd := range s.theList {
// when we reach max exit
if numRR >= 25 {
break
}
if nd.status != statusCG {
continue
}
if t == dnsV4Std || t == dnsV4Non {
if t == dnsV4Std && nd.dnsType == dnsV4Std {
r := new(dns.A)
r.Hdr = dns.RR_Header{Name: s.dnsHost + ".", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: s.ttl}
r.A = nd.na.IP
rr4std = append(rr4std, r)
numRR++
}
// if the node is using a non standard port then add the encoded port info to DNS
if t == dnsV4Non && nd.dnsType == dnsV4Non {
r := new(dns.A)
r.Hdr = dns.RR_Header{Name: "nonstd." + s.dnsHost + ".", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: s.ttl}
r.A = nd.na.IP
rr4non = append(rr4non, r)
numRR++
r = new(dns.A)
r.Hdr = dns.RR_Header{Name: "nonstd." + s.dnsHost + ".", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: s.ttl}
r.A = nd.nonstdIP
rr4non = append(rr4non, r)
numRR++
}
}
if t == dnsV6Std || t == dnsV6Non {
if t == dnsV6Std && nd.dnsType == dnsV6Std {
r := new(dns.AAAA)
r.Hdr = dns.RR_Header{Name: s.dnsHost + ".", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: s.ttl}
r.AAAA = nd.na.IP
rr6std = append(rr6std, r)
numRR++
}
// if the node is using a non standard port then add the encoded port info to DNS
if t == dnsV6Non && nd.dnsType == dnsV6Non {
r := new(dns.AAAA)
r.Hdr = dns.RR_Header{Name: "nonstd." + s.dnsHost + ".", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: s.ttl}
r.AAAA = nd.na.IP
rr6non = append(rr6non, r)
numRR++
r = new(dns.AAAA)
r.Hdr = dns.RR_Header{Name: "nonstd." + s.dnsHost + ".", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: s.ttl}
r.AAAA = nd.nonstdIP
rr6non = append(rr6non, r)
numRR++
}
}
}
}
s.mtx.RUnlock()
config.dnsmtx.Lock()
// update the map holding the details for this seeder
for t := range []int{dnsV4Std, dnsV4Non, dnsV6Std, dnsV6Non} {
switch t {
case dnsV4Std:
config.dns[s.dnsHost+".A"] = rr4std
case dnsV4Non:
config.dns["nonstd."+s.dnsHost+".A"] = rr4non
case dnsV6Std:
config.dns[s.dnsHost+".AAAA"] = rr6std
case dnsV6Non:
config.dns["nonstd."+s.dnsHost+".AAAA"] = rr6non
}
}
config.dnsmtx.Unlock()
if config.stats {
s.counts.mtx.RLock()
log.Printf("%s - DNS available: v4std: %v v4non: %v v6std: %v v6non: %v\n", s.name, len(rr4std), len(rr4non), len(rr6std), len(rr6non))
log.Printf("%s - DNS counts: v4std: %v v4non: %v v6std: %v v6non: %v total: %v\n",
s.name,
s.counts.DNSCounts[dnsV4Std],
s.counts.DNSCounts[dnsV4Non],
s.counts.DNSCounts[dnsV6Std],
s.counts.DNSCounts[dnsV6Non],
s.counts.DNSCounts[dnsV4Std]+s.counts.DNSCounts[dnsV4Non]+s.counts.DNSCounts[dnsV6Std]+s.counts.DNSCounts[dnsV6Non])
s.counts.mtx.RUnlock()
}
}
