update
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MDK
158
echodns.go
158
echodns.go
@@ -1,72 +1,118 @@
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package main
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import (
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"bytes"
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"encoding/binary"
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_ "fmt"
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"fmt"
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"net"
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"strconv"
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"strings"
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"time"
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"math/rand"
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"github.com/google/gopacket"
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"github.com/google/gopacket/layers"
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"github.com/miekg/dns"
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)
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func serveDNS(u *net.UDPConn, clientaddr net.Addr, request *layers.DNS) {
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replyMess := request
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var dnsAnswer layers.DNSResourceRecord
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if request == nil || request.Questions == nil || len(request.Questions) == 0 {
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func strategyMaker(name string, qtype uint16) uint16 {
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subdomain := strings.ToLower(strings.Split(name, ".")[0])
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if qtype == dns.TypeA {
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if strings.Contains(subdomain, "fwd") {
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return 1 // return rdns ip in cname
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} else if strings.Contains(subdomain, "rdns") {
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return 2 // return honey cname record
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} else if strings.Contains(subdomain, "honey") {
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return 3 // return timestamp in a record
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} else if strings.Contains(subdomain, "echo") {
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return 4 // basic echodns
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} else if strings.Contains(subdomain, "ttl") {
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return 5 // ttl test
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}
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}
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return 0
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}
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func InttoIPv4(n uint32) net.IP {
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b0 := (n >> 24) & 0xff
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b1 := (n >> 16) & 0xff
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b2 := (n >> 8) & 0xff
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b3 := n & 0xff
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return net.IPv4(byte(b0), byte(b1), byte(b2), byte(b3))
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}
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func TtlParser(domain string) uint32 {
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subdomain := strings.ToLower(strings.Split(domain, ".")[0])
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ttl, _ := strconv.Atoi(strings.Split(subdomain, "-")[0])
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return uint32(ttl)
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}
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func handleReflect(w dns.ResponseWriter, r *dns.Msg) {
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var (
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ip net.IP
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name string
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qtype uint16
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)
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m := new(dns.Msg)
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m.SetReply(r)
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m.Compress = true
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m.Authoritative = true
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if addr, ok := w.RemoteAddr().(*net.UDPAddr); ok {
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ip = addr.IP
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}
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name = m.Question[0].Name
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qtype = m.Question[0].Qtype
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//fmt.Println(ip)
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//fmt.Println(name)
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//fmt.Println(qtype)
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switch strategyMaker(name, qtype) {
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case 1:
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cname_subdomain := "rdns-" + strings.Replace(ip.String(), ".", "-", -1)
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cname_fqdn := cname_subdomain + ".echodns.xyz."
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cname := &dns.CNAME{
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Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 14400},
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Target: cname_fqdn,
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}
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//fmt.Println(name+" "+cname_fqdn)
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m.Answer = append(m.Answer, cname)
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case 2:
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cname_fqdn := "honey.echodns.xyz."
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cname := &dns.CNAME{
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Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 14400},
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Target: cname_fqdn,
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}
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//fmt.Println(cname_fqdn)
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m.Answer = append(m.Answer, cname)
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case 3:
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time_str := strconv.FormatInt(time.Now().UnixMicro(), 10)
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time_int, _ := strconv.Atoi(time_str[5 : len(time_str)-2])
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time_int += rand.Intn(10000)
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timestamp := InttoIPv4(uint32(time_int))
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a := &dns.A{
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Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 14400},
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A: timestamp,
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}
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m.Answer = append(m.Answer, a)
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case 4:
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a := &dns.A{
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Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
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A: ip,
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}
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m.Answer = append(m.Answer, a)
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case 5:
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query_ttl := TtlParser(name)
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//fmt.Println(query_ttl)
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a := &dns.A{
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Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: query_ttl},
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A: ip,
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}
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m.Answer = append(m.Answer, a)
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case 0:
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return
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} else {
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dnsAnswer.Name = []byte(request.Questions[0].Name)
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}
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//fmt.Println(clientaddr.String())
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replyMess.QR = true
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replyMess.ANCount = 1
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replyMess.OpCode = layers.DNSOpCodeQuery
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replyMess.AA = true
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if request.Questions[0].Type == layers.DNSTypeA {
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dnsAnswer.Type = layers.DNSTypeA
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dnsAnswer.Class = layers.DNSClassIN
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dnsAnswer.IP = net.ParseIP(strings.Split(clientaddr.String(), ":")[0])
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dnsAnswer.TTL = 1000
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} else if request.Questions[0].Type == layers.DNSTypeAAAA {
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dnsAnswer.Type = layers.DNSTypeAAAA
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dnsAnswer.Class = layers.DNSClassIN
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t := time.Now().UnixMicro()
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rdns_ipv4 := net.ParseIP(strings.Split(clientaddr.String(), ":")[0]).To4()
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bytebuf := bytes.NewBuffer([]byte{})
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binary.Write(bytebuf, binary.BigEndian, t)
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binary.Write(bytebuf, binary.BigEndian, rdns_ipv4)
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binary.Write(bytebuf, binary.BigEndian, []byte{0, 0, 0, 0})
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dnsAnswer.IP = net.IP(bytebuf.Bytes())
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dnsAnswer.TTL = 1000
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}
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replyMess.Answers = append(replyMess.Answers, dnsAnswer)
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replyMess.ResponseCode = layers.DNSResponseCodeNoErr
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buf := gopacket.NewSerializeBuffer()
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opts := gopacket.SerializeOptions{}
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err := replyMess.SerializeTo(buf, opts)
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if err != nil {
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panic(err)
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}
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u.WriteTo(buf.Bytes(), clientaddr)
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w.WriteMsg(m)
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}
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func main() {
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addr := net.UDPAddr{
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Port: 53,
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IP: net.ParseIP("localhost.localdomain"), //localhost
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}
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u, _ := net.ListenUDP("udp", &addr)
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for {
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tmp := make([]byte, 1024)
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_, addr, _ := u.ReadFrom(tmp)
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clientaddr := addr
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packet := gopacket.NewPacket(tmp, layers.LayerTypeDNS, gopacket.Default)
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dnsPacket := packet.Layer(layers.LayerTypeDNS)
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tcp, _ := dnsPacket.(*layers.DNS)
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serveDNS(u, clientaddr, tcp)
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dns.HandleFunc("echodns.xyz.", handleReflect)
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server := &dns.Server{Addr: ":53", Net: "udp"}
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if err := server.ListenAndServe(); err != nil {
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fmt.Println("Failed to set up dns server!")
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}
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}
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