Create fp as a type
This commit is contained in:
Miek Gieben
parent
1b96a4413a
commit
fb68e29eb1
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@ -3,6 +3,6 @@
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# license that can be found in the LICENSE file.
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include $(GOROOT)/src/Make.inc
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TARG=q
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GOFILES=q.go fp.go
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GOFILES=q.go fp.go lex.go
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DEPS=../../
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include $(GOROOT)/src/Make.cmd
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@ -7,55 +7,202 @@ import (
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"strings"
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)
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// fingerPrint creates a (short) string representation of a dns message.
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// SendProbe creates a packet and sends it to the nameserver.
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// Connection errors are returned as:
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// ...
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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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println(err.String())
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// return "connection error"
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return nil
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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"
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type fingerprint struct {
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Error string
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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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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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}
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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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func msgToFingerPrint(m *dns.Msg) string {
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if m == nil {
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// This leads to strings like: "QUERY,NOERROR,qr,aa,tc,RD,ad,cd,z,1,0,0,1,DO,4096"
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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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h := m.MsgHdr
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// Use the same order as in Perl's fpdns. But use more flags.
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s := dns.Opcode_str[f.Opcode]
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s += "," + dns.Rcode_str[f.Rcode]
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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.AuthenticatedData, ",ad")
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s += valueOfBool(f.CheckingDisabled, ",cd")
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s += valueOfBool(f.Zero, ",z")
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// Use the same order as in Perl's fpdns.
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// But use more flags.
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s := dns.Opcode_str[h.Opcode]
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s += "," + dns.Rcode_str[h.Rcode]
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s += valueOf(h.Response, ",qr")
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s += valueOf(h.Authoritative, ",aa")
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s += valueOf(h.Truncated, ",tc")
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s += valueOf(h.RecursionDesired, ",rd")
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s += valueOf(h.AuthenticatedData, ",ad")
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s += valueOf(h.CheckingDisabled, ",ad")
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s += valueOf(h.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 += "," + strconv.Itoa(len(m.Question))
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s += "," + strconv.Itoa(len(m.Answer))
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s += "," + strconv.Itoa(len(m.Ns))
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s += "," + strconv.Itoa(len(m.Extra))
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// EDNS0
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// V0,DO,4096 (all on)
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// v0,do,0 (all off)
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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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s += valueOf(r.(*dns.RR_OPT).Do(), ",do")
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s += "," + strconv.Itoa(int(r.(*dns.RR_OPT).UDPSize()))
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return s
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}
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}
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s += ",do,0"
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s += valueOfBool(f.Do, ",do")
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s += valueOfInt(f.UDPSize)
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return s
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}
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// Create a dns message from a fingerprint string
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func fingerPrintToProbe(fp string, q dns.Question) *dns.Msg {
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return nil
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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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f.Opcode = dns.Str_opcode[s]
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case 1:
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f.Rcode = dns.Str_rcode[s]
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case 2:
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f.Response = false
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if s == strings.ToUpper("qr") {
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f.Response = true
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}
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case 3:
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f.Authoritative = false
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if s == strings.ToUpper("aa") {
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f.Authoritative = true
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}
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case 4:
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f.Truncated = false
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if s == strings.ToUpper("tc") {
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f.Truncated = true
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}
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case 5:
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f.RecursionDesired = false
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if s == strings.ToUpper("rd") {
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f.RecursionDesired = true
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}
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case 6:
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f.AuthenticatedData = false
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if s == strings.ToUpper("ad") {
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f.AuthenticatedData = true
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}
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case 7:
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f.CheckingDisabled = false
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if s == strings.ToUpper("cd") {
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f.CheckingDisabled = true
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}
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case 8:
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f.Zero = false
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if s == strings.ToUpper("z") {
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f.Zero = true
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}
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case 9, 10, 11, 12:
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// Can not set content of the message
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case 13:
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f.Do = false
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if s == strings.ToUpper("do") {
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f.Do = true
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}
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case 14:
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f.UDPSize = 0
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f.UDPSize = valueOfString(s)
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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 valueOf(x bool, w string) string {
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if x {
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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.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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}
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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
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// same.
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// QUERY,NOERROR,qr,aa,tc,RD,ad,ad,z,1,0,0,1,DO,4096
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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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}
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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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@ -0,0 +1,54 @@
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package main
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import (
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"dns"
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)
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type itemType int
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// We handle the checking as a lexing program.
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// We use the lexer like Rob Pike lectures about in this
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// clip: http://www.youtube.com/watch?v=HxaD_trXwRE
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type item struct {
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typ itemType
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val string
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}
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const (
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itemError itemType = iota
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itemVender // software vendor
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itemSoftware // the name of the DNS server software
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itemVersion // the version of the software (empty if not determined)
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)
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// stateFn represents the state of the scanner as a function that returns the next state.
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type stateFn func(*lexer) stateFn
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type lexer struct {
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client *dns.Client // client used.
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addr string // addr of the server being scanned.
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fp *fingerprint // fingerprint to test.
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q dns.Question // question to ask.
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items chan item // channel of scanned items.
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state stateFn // the next function to enter.
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}
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func (l *lexer) probe() *fingerprint {
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return sendProbe(l.client, l.addr, l.fp, l.q)
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}
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func (l *lexer) emit() {
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// send item on the channel
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}
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// "Lexer" functions
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// Check if the server returns the DO-bit when set in the request.
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func lexDoBitMirorred(l *lexer) stateFn {
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// The important part here is that the DO bit is on
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l.fp.SetString("QUERY,NOERROR,qr,aa,tc,RD,ad,cd,z,1,0,0,0,DO,0")
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l.q = dns.Question{".", dns.TypeNS, dns.ClassINET}
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l.probe()
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return nil
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}
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@ -114,6 +114,7 @@ Flags:
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m.Question[0] = dns.Question{v, qtype, qclass}
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m.Id = dns.Id()
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if *query {
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fmt.Printf("%s\n", msgToFingerprint(m))
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fmt.Printf("%s\n", m.String())
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}
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c.Do(m, nameserver)
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@ -134,7 +135,7 @@ forever:
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r.Reply = shortMsg(r.Reply)
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}
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if *fp {
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fmt.Printf("%s\n", msgToFingerPrint(r.Reply))
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fmt.Printf("%s\n", msgToFingerprint(r.Reply))
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}
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fmt.Printf("%v", r.Reply)
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}
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20
msg.go
20
msg.go
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@ -124,8 +124,14 @@ var Rr_str = map[uint16]string{
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}
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// Reverse, needed for string parsing.
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var str_rr = reverse(Rr_str)
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var str_class = reverse(Class_str)
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var Str_rr = reverseInt16(Rr_str)
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var Str_class = reverseInt16(Class_str)
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// Map of opcodes strings.
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var Str_opcode = reverseInt(Opcode_str)
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// Map of rcodes strings.
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var Str_rcode = reverseInt(Rcode_str)
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// Map of strings for each CLASS wire type.
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var Class_str = map[uint16]string{
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@ -864,7 +870,7 @@ func unpackRR(msg []byte, off int) (rr RR, off1 int, ok bool) {
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}
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// Reverse a map
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func reverse(m map[uint16]string) map[string]uint16 {
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func reverseInt16(m map[uint16]string) map[string]uint16 {
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n := make(map[string]uint16)
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for u, s := range m {
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n[s] = u
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@ -872,6 +878,14 @@ func reverse(m map[uint16]string) map[string]uint16 {
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return n
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}
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func reverseInt(m map[int]string) map[string]int {
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n := make(map[string]int)
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for u, s := range m {
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n[s] = u
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}
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return n
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}
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// Convert a MsgHdr to a string, mimic the way Dig displays headers:
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//;; opcode: QUERY, status: NOERROR, id: 48404
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//;; flags: qr aa rd ra;
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