282 lines
6.5 KiB
Go
282 lines
6.5 KiB
Go
// Package main provides ...
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package main
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import (
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"dns"
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"fmt"
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"strconv"
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"strings"
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)
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const (
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// Detected software types
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NSD = "NSD"
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BIND = "BIND"
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POWERDNS = "PowerDNS"
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WINDOWSDNS = "Windows DNS"
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MARADNS = "MaraDNS"
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NEUSTARDNS = "Neustar DNS"
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ATLAS = "Atlas"
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// Vendors
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ISC = "ISC"
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MARA = "MaraDNS.org" // check
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NLNETLABS = "NLnet Labs"
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MICROSOFT = "Microsoft"
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POWER = "PowerDNS.com"
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NEUSTAR = "Neustar"
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VERISIGN = "Verisign"
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)
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func startParse(addr string) {
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l := &lexer{
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addr: addr,
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client: dns.NewClient(),
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fp: new(fingerprint),
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items: make(chan item),
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state: dnsAlive,
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debug: true,
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}
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l.run()
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// Not completely sure about this code..
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for {
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item := <-l.items
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fmt.Printf("{%s %s}\n", itemString[item.typ], item.val)
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if l.state == nil {
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break
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}
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}
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}
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// SendProbe creates a packet and sends it to the nameserver. It
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// returns a fingerprint.
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func sendProbe(c *dns.Client, addr string, f *fingerprint, q dns.Question) *fingerprint {
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m := f.toProbe(q)
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r, err := c.Exchange(m, addr)
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if err != nil {
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return errorToFingerprint(err)
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}
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return msgToFingerprint(r)
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}
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// This leads to strings like: "QUERY,NOERROR,qr,aa,tc,RD,ad,cd,z,1,0,0,1,DO,4096,NSID"
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type fingerprint struct {
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Error error
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Opcode int
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Rcode int
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Response bool
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Authoritative bool
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Truncated bool
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RecursionDesired bool
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RecursionAvailable bool
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AuthenticatedData bool
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CheckingDisabled bool
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Zero bool
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Question int
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Answer int
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Ns int
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Extra int
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Do bool
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UDPSize int
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Nsid bool
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}
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// String creates a (short) string representation of a dns message.
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// If a bit is set we uppercase the name 'AD' otherwise it's lowercase 'ad'.
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// This leads to strings like: "QUERY,NOERROR,qr,aa,tc,RD,ad,cd,z,1,0,0,1,DO,4096,NSID"
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func (f *fingerprint) String() string {
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if f == nil {
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return "<nil>"
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}
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// Use the same order as in Perl's fpdns. But use more flags.
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var s string
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if op, ok := dns.Opcode_str[f.Opcode]; ok {
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s = op
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} else { // number
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s = valueOfInt(f.Opcode)
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}
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if op, ok := dns.Rcode_str[f.Rcode]; ok {
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s += "," + op
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} else { // number
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s += "," + valueOfInt(f.Rcode)
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}
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s += valueOfBool(f.Response, ",qr")
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s += valueOfBool(f.Authoritative, ",aa")
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s += valueOfBool(f.Truncated, ",tc")
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s += valueOfBool(f.RecursionDesired, ",rd")
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s += valueOfBool(f.RecursionAvailable, ",ra")
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s += valueOfBool(f.AuthenticatedData, ",ad")
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s += valueOfBool(f.CheckingDisabled, ",cd")
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s += valueOfBool(f.Zero, ",z")
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s += "," + valueOfInt(f.Question)
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s += "," + valueOfInt(f.Answer)
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s += "," + valueOfInt(f.Ns)
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s += "," + valueOfInt(f.Extra)
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s += valueOfBool(f.Do, ",do")
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s += "," + valueOfInt(f.UDPSize)
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s += valueOfBool(f.Nsid, ",nsid")
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return s
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}
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// fingerStringNoSections returns the strings representation
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// without the sections' count and the EDNS0 stuff
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func (f *fingerprint) StringNoSections() string {
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s := strings.SplitN(f.String(), ",", 11)
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return strings.Join(s[:10], ",")
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}
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// SetString set the string to fp.. todo
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func (f *fingerprint) setString(str string) {
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for i, s := range strings.Split(str, ",") {
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switch i {
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case 0:
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if op, ok := dns.Str_opcode[s]; ok {
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f.Opcode = op
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} else { // number
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f.Opcode = valueOfString(s)
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}
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case 1:
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if op, ok := dns.Str_rcode[s]; ok {
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f.Rcode = op
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} else { // number
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f.Rcode = valueOfString(s)
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}
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case 2:
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f.Response = s == strings.ToUpper("qr")
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case 3:
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f.Authoritative = s == strings.ToUpper("aa")
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case 4:
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f.Truncated = s == strings.ToUpper("tc")
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case 5:
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f.RecursionDesired = s == strings.ToUpper("rd")
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case 6:
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f.RecursionAvailable = s == strings.ToUpper("ra")
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case 7:
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f.AuthenticatedData = s == strings.ToUpper("ad")
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case 8:
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f.CheckingDisabled = s == strings.ToUpper("cd")
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case 9:
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f.Zero = s == strings.ToUpper("z")
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case 10, 11, 12, 13:
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// Can not set content of the message
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case 14:
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f.Do = s == strings.ToUpper("do")
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case 15:
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f.UDPSize = valueOfString(s)
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case 16:
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f.Nsid = s == strings.ToUpper("nsid")
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default:
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panic("unhandled fingerprint")
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}
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}
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return
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}
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func (f *fingerprint) ok() bool {
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return f.Error == nil
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}
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func (f *fingerprint) error() string {
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if f.Error == nil {
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panic("error is nil")
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}
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return f.Error.Error()
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}
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func errorToFingerprint(e error) *fingerprint {
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f := new(fingerprint)
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f.Error = e
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return f
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}
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func msgToFingerprint(m *dns.Msg) *fingerprint {
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if m == nil {
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return nil
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}
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h := m.MsgHdr
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f := new(fingerprint)
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f.Opcode = h.Opcode
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f.Rcode = h.Rcode
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f.Response = h.Response
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f.Authoritative = h.Authoritative
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f.Truncated = h.Truncated
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f.RecursionDesired = h.RecursionDesired
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f.RecursionAvailable = h.RecursionAvailable
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f.AuthenticatedData = h.AuthenticatedData
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f.CheckingDisabled = h.CheckingDisabled
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f.Zero = h.Zero
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f.Question = len(m.Question)
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f.Answer = len(m.Answer)
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f.Ns = len(m.Ns)
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f.Extra = len(m.Extra)
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f.Do = false
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f.UDPSize = 0
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for _, r := range m.Extra {
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if r.Header().Rrtype == dns.TypeOPT {
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// version is always 0 - and I cannot set it anyway
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f.Do = r.(*dns.RR_OPT).Do()
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f.UDPSize = int(r.(*dns.RR_OPT).UDPSize())
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if len(r.(*dns.RR_OPT).Option) == 1 {
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// Only support NSID atm
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f.Nsid = r.(*dns.RR_OPT).Option[0].Code == dns.OptionCodeNSID
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}
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}
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}
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return f
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}
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// Create a dns message from a fingerprint string and
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// a DNS question. The order of a string is always the same.
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// QUERY,NOERROR,qr,aa,tc,RD,ad,ad,z,1,0,0,1,DO,4096,nsid
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func (f *fingerprint) toProbe(q dns.Question) *dns.Msg {
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m := new(dns.Msg)
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m.MsgHdr.Id = dns.Id()
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m.Question = make([]dns.Question, 1)
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m.Question[0] = q
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m.MsgHdr.Opcode = f.Opcode
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m.MsgHdr.Rcode = f.Rcode
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m.MsgHdr.Response = f.Response
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m.MsgHdr.Authoritative = f.Authoritative
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m.MsgHdr.Truncated = f.Truncated
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m.MsgHdr.RecursionDesired = f.RecursionDesired
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m.MsgHdr.AuthenticatedData = f.AuthenticatedData
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m.MsgHdr.CheckingDisabled = f.CheckingDisabled
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m.MsgHdr.Zero = f.Zero
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if f.Do {
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// Add an OPT section.
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m.SetEdns0(0, true)
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// We have added an OPT RR, set the size.
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m.Extra[0].(*dns.RR_OPT).SetUDPSize(uint16(f.UDPSize))
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if f.Nsid {
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m.Extra[0].(*dns.RR_OPT).SetNsid("")
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}
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}
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return m
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}
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func valueOfBool(b bool, w string) string {
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if b {
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return strings.ToUpper(w)
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}
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return strings.ToLower(w)
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}
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func valueOfInt(i int) string {
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return strconv.Itoa(i)
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}
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func valueOfString(s string) int {
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i, _ := strconv.Atoi(s)
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return i
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}
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