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package main
import (
"flag"
"fmt"
_ "math/rand"
"net"
"strconv"
"strings"
_ "time"
"github.com/miekg/dns"
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
var CONFIG_SLD string
var CONFIG_NS string
var UniqueCounter uint32 = 0xfffffffa
func strategyMaker(name string, qtype uint16) int8 {
var subdomain string
labels := strings.Split(name, ".")
if len(labels) >= 4 {
subdomain = strings.ToLower(labels[len(labels)-4])
}
if qtype == dns.TypeA {
if len(labels) == 4 && (subdomain == "ns1" || subdomain == "ns2") {
return 0
} else if strings.Contains(subdomain, "fwd") {
return 1 // return rdns ip in cname
} else if strings.Contains(subdomain, "rdns") {
return 2 // return honey cname record
} else if strings.Contains(subdomain, "honey") {
return 3 // return timestamp in a record
} else if strings.Contains(subdomain, "echo") {
return 4 // basic echodns
} else if strings.Contains(subdomain, "ttl") {
return 5 // ttl test
} else if strings.Contains(subdomain, "wrong-id") {
return 6 // return response with wrong txid
} else if strings.Contains(subdomain, "wrong-rec") {
return 7 // return response with wrong records
} else if strings.Contains(subdomain, "bailiwick") {
return 8 // bailiwick verification
} else if strings.Contains(subdomain, "cname-chain") {
return 9 // unlimited ns chain
} else if strings.Contains(subdomain, "ns-chain") {
return 10 // unlimited cname chain
} else if strings.Contains(subdomain, "attack") {
return 11
}
}
return -1
}
func InttoIPv4(n uint32) net.IP {
b0 := (n >> 24) & 0xff
b1 := (n >> 16) & 0xff
b2 := (n >> 8) & 0xff
b3 := n & 0xff
return net.IPv4(byte(b0), byte(b1), byte(b2), byte(b3))
}
func TtlParser(domain string) uint32 {
subdomain := strings.ToLower(strings.Split(domain, ".")[0])
ttl, _ := strconv.Atoi(strings.Split(subdomain, "-")[0])
return uint32(ttl)
}
func handleReflect(w dns.ResponseWriter, r *dns.Msg) {
var (
ip net.IP
port int
id uint16
name string
qtype uint16
)
m := new(dns.Msg)
m.SetReply(r)
m.Compress = true
m.Authoritative = true
if addr, ok := w.RemoteAddr().(*net.UDPAddr); ok {
ip = addr.IP
port = addr.Port
}
id = m.MsgHdr.Id
name = m.Question[0].Name
subdomain := strings.ToLower(strings.Split(name, ".")[0])
qtype = m.Question[0].Qtype
log.Log().Str("sip", ip.String()).Int64("port", int64(port)).Int64("id", int64(id)).Str("name", name).Int64("qtype", int64(qtype)).Msg("")
//log.Printf("%v|%v|%v|%v|%v", ip, port, id, name, qtype)
//fmt.Println(ip)
//fmt.Println(name)
//fmt.Println(qtype)
switch strategyMaker(name, qtype) {
case 1:
cname_subdomain := "rdns-" + strings.Replace(ip.String(), ".", "-", -1)
cname_fqdn := dns.Fqdn(cname_subdomain + "." + CONFIG_SLD)
cname := &dns.CNAME{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 14400},
Target: cname_fqdn,
}
//fmt.Println(name+" "+cname_fqdn)
m.Answer = append(m.Answer, cname)
case 2:
cname_fqdn := dns.Fqdn("honey." + CONFIG_SLD)
cname := &dns.CNAME{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 14400},
Target: cname_fqdn,
}
//fmt.Println(cname_fqdn)
m.Answer = append(m.Answer, cname)
case 3:
//time_str := strconv.FormatInt(time.Now().UnixMicro(), 10)
//time_int, _ := strconv.Atoi(time_str[5 : len(time_str)-2])
//time_int += rand.Intn(10000)
UniqueCounter += 1
timestamp := InttoIPv4(uint32(UniqueCounter))
a := &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 14400},
A: timestamp,
}
m.Answer = append(m.Answer, a)
case 4:
a := &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
A: ip,
}
m.Answer = append(m.Answer, a)
case 5:
query_ttl := TtlParser(name)
//fmt.Println(query_ttl)
a := &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: query_ttl},
A: ip,
}
m.Answer = append(m.Answer, a)
case 6:
m.MsgHdr.Id += 1
a := &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
A: ip,
}
m.Answer = append(m.Answer, a)
case 7:
wrong_answer := &dns.AAAA{
Hdr: dns.RR_Header{Name: "www.example.com.", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 60},
AAAA: net.ParseIP("fe80::7526:a2ae:a0b8:946d"),
}
m.Answer = append(m.Answer, wrong_answer)
case 8:
wrong_ns := &dns.NS{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: 60},
Ns: dns.Fqdn("dns.baidu.com"),
}
wrong_ns_ip := &dns.A{
Hdr: dns.RR_Header{Name: "dns.baidu.com.", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
A: net.ParseIP("159.75.200.247"),
}
m.Ns = append(m.Ns, wrong_ns)
m.Extra = append(m.Extra, wrong_ns_ip)
case 9:
cname_target := ""
labels := strings.Split(subdomain, "-")
if labels[len(labels)-1] == "chain" {
cname_target = subdomain + "-0"
} else {
iter_cnt, _ := strconv.Atoi(labels[len(labels)-1])
iter_cnt += 1
labels = append(labels[:len(labels)-1], strconv.Itoa(iter_cnt))
cname_target = strings.Join(labels, "-")
//cname_target = strings.Join([]string{labels[0], labels[1], strconv.Itoa(iter_cnt)}, "-")
}
cname_target = dns.Fqdn(cname_target + "." + CONFIG_SLD)
cname_redir := &dns.CNAME{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 60},
Target: cname_target,
}
m.Answer = append(m.Answer, cname_redir)
case 10:
ns_target := ""
labels := strings.Split(subdomain, "-")
if labels[len(labels)-1] == "chain" {
ns_target = subdomain + "-0"
} else {
iter_cnt, _ := strconv.Atoi(labels[len(labels)-1])
iter_cnt += 1
labels = append(labels[:len(labels)-1], strconv.Itoa(iter_cnt))
ns_target = strings.Join(labels, "-")
//ns_target = strings.Join([]string{labels[0], labels[1], strconv.Itoa(iter_cnt)}, "-")
}
ns_target = dns.Fqdn(ns_target + "." + CONFIG_SLD)
ns_delegation := &dns.NS{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: 60},
Ns: ns_target,
}
m.Ns = append(m.Ns, ns_delegation)
case 11:
ns_record := &dns.NS{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: 60},
Ns: "shiyan7.jthmfgz.icu.",
}
m.Ns = append(m.Ns, ns_record)
case 0:
a := &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 3600},
A: net.ParseIP(CONFIG_NS),
}
m.Answer = append(m.Answer, a)
case -1:
m.MsgHdr.Rcode = dns.RcodeNameError
}
w.WriteMsg(m)
}
func main() {
flag.StringVar(&CONFIG_NS, "ns", "159.75.200.247", "configure nameserver ip for echo dns zone")
flag.StringVar(&CONFIG_SLD, "sld", "", "configure sld for echo dns server")
flag.Parse()
if CONFIG_SLD == "" {
panic("Please configure the SLD for the echo dns server!\n")
}
zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
dns.HandleFunc(dns.Fqdn(CONFIG_SLD), handleReflect)
server := &dns.Server{Addr: ":53", Net: "udp"}
if err := server.ListenAndServe(); err != nil {
fmt.Println("Failed to set up dns server!")
panic(err)
}
}
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