func respondWithFallback(raw []uint8, clientMsg *dns.Msg, clientQuestion dns.Question, proxy *net.UDPAddr) {
LOG.Println("fallback:", clientQuestion, proxy)
conn, err := net.Dial("udp", proxy.String())
if err != nil {
LOG.Fatalln(err)
}
conn.Write(raw)
buffer := make([]byte, 1<<15)
size, err := conn.Read(buffer)
if err != nil {
LOG.Fatalln(err, proxy)
}
msg := &dns.Msg{}
msg.Unpack(buffer[0:size])
LOG.Println(msg)
for _, answer := range msg.Answer {
clientMsg.Answer = append(clientMsg.Answer, answer)
}
clientMsg.Rcode = msg.Rcode
clientMsg.Response = msg.Response
clientMsg.Authoritative = msg.Authoritative
clientMsg.Recursion_desired = msg.Recursion_desired
clientMsg.Recursion_available = msg.Recursion_available
}
// For now, we only answer queries for A and NS
func respondWithDotBit(msg *dns.Msg, question dns.Question) {
// "foo.bar.bit." => ["foo", "bar", "bit"]
nameParts := strings.Split(question.Name, ".", -1)
var name []string
for _, part := range nameParts {
if part != "" {
name = append(name, part)
}
}
// edge case, if we get "bit." as question.Name
// TODO: handle as proper error
if len(name) <= 1 {
return
}
// ["foo", "bar", "bit"] => ["foo", "bar"]
name = name[0 : len(name)-1]
// look up the root "d/bar"
record, err := nmcLookup(name[len(name)-1])
if err != nil {
LOG.Fatalln(err)
}
var value NMCValue
json.Unmarshal([]uint8(record.Value), &value)
msg.Response = true
switch question.Qtype {
case dns.TypeA:
answerA(msg, question, name, value)
case dns.TypeAAAA:
answerAAAA(msg, question, name, value)
//case dns.TypeNS: answerNS(msg)
//case dns.TypeMD: answerMD(msg)
//case dns.TypeMF: answerMF(msg)
//case dns.TypeCNAME: answerCNAME(msg)
//case dns.TypeSOA: answerSOA(msg)
//case dns.TypeMB: answerMB(msg)
//case dns.TypeMG: answerMG(msg)
//case dns.TypeMR: answerMR(msg)
//case dns.TypeNULL: answerNULL(msg)
//case dns.TypeWKS: answerWKS(msg)
//case dns.TypePTR: answerPTR(msg)
//case dns.TypeHINFO: answerHINFO(msg)
//case dns.TypeMINFO: answerMINFO(msg)
//case dns.TypeMX: answerMX(msg)
//case dns.TypeTXT: answerTXT(msg)
//case dns.TypeSRV: answerSRV(msg)
default:
LOG.Fatalln("Cannot serve name:", name, "qtype:", question.Qtype)
msg.Rcode = dns.RcodeNotImplemented
}
}
func answerAAAA(msg *dns.Msg, question dns.Question, name []string, value NMCValue) {
var parsedIp net.IP
// len == 1 means root domain: check "ip" and "map".""
if len(name) == 1 {
vips := value.Ip6
if len(vips) == 0 {
// can't answer, make an error here.
return
} else {
parsedIp = net.ParseIP(vips[0])
}
}
ip := parsedIp.To16()
if ip == nil {
return
}
LOG.Println("AAAA", name, "=>", ip)
rraaaa := &dns.RR_AAAA{}
copy(ip, rraaaa.AAAA[:])
rrh := &dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: 60,
Rdlength: 100,
}
rraaaa.Hdr = *rrh
msg.Rcode = dns.RcodeSuccess
msg.Answer = append(msg.Answer, rraaaa)
msg.Response = true
msg.Authoritative = true
msg.Recursion_desired = true
msg.Recursion_available = true
}
func answerA(msg *dns.Msg, question dns.Question, name []string, value NMCValue) {
var parsedIp net.IP
// len == 1 means root domain: check "ip" and "map".""
if len(name) == 1 {
vips := value.Ip
// this is legacy support
if len(vips) == 0 {
vmap := value.Map
if vmap == nil {
return
}
vmip, ok := value.Map[""]
if !ok && vmip == "" {
// can't answer, make an error here.
return
}
switch vmip.(type) {
case nil:
return
case map[string]interface{}:
nsAvailable := vmip.(map[string]interface{})["ns"]
switch nsAvailable.(type) {
case []interface{}:
ns := nsAvailable.([]interface{})[0]
switch ns.(type) {
case string:
h := dns.MsgHdr{
Id: uint16(rand.Int()) ^ uint16(time.Nanoseconds()),
Recursion_desired: true,
}
q := &dns.Question{
Name: question.Name,
Qtype: dns.TypeA,
Qclass: dns.ClassINET,
}
m := &dns.Msg{}
m.MsgHdr = h
m.Question = append(m.Question, *q)
LOG.Println(m)
out, ok := m.Pack()
if !ok {
LOG.Fatalln("Failed to Pack:", msg)
}
nsaddr := ns.(string) + ":53"
conn, err := net.Dial("udp", nsaddr)
if err != nil {
LOG.Fatalf("net.DialUDP(\"udp\", nil, %v) => %v", nsaddr, err)
}
LOG.Println("out:", out)
n, err := conn.Write(out)
if err != nil {
LOG.Fatalln(err)
}
LOG.Println("wrote:", n)
conn.SetReadTimeout(10e9)
defer conn.Close()
b := make([]byte, 1<<15)
s, err := conn.Read(b)
if err != nil {
LOG.Fatalln(err, nsaddr)
}
err = conn.Close()
if err != nil {
LOG.Fatalln(err)
}
a := &dns.Msg{}
a.Unpack(b[0:s])
LOG.Println("a:", a)
msg.Answer = append(msg.Answer, a.Answer[0])
return
default:
LOG.Printf("can't find the type of: %#v", ns)
}
default:
LOG.Printf("can't find the type of: %#v", nsAvailable)
}
case string:
parsedIp = net.ParseIP(vmip.(string))
default:
LOG.Printf("can't find the type of: %#v", vmip)
}
} else {
parsedIp = net.ParseIP(vips[0])
}
}
ip := parsedIp.To4()
if ip == nil {
return
}
LOG.Println("A", name, "=>", ip)
var a uint32
rra := &dns.RR_A{}
rra.A = (a | uint32(ip[0])<<24 | uint32(ip[1])<<16 | uint32(ip[2])<<8 | uint32(ip[3]))
rrh := &dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 60,
Rdlength: 100,
}
rra.Hdr = *rrh
msg.Rcode = dns.RcodeSuccess
msg.Answer = append(msg.Answer, rra)
msg.Response = true
msg.Authoritative = true
msg.Recursion_desired = true
msg.Recursion_available = true
}