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EDNS is easy 

Only the OPT RR needs to be supported
This commit is contained in:
Miek Gieben 2010-12-23 14:07:35 +01:00
parent 8302d19b42
commit 18afd5e536
5 changed files with 88 additions and 73 deletions
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5
Makefile
View File

@ -14,7 +14,7 @@ GOFILES=\
include $(GOROOT)/src/Make.pkg
p: restest manglertest ednstest dnssectest
p: restest manglertest ednstest dnssectest ednstest2
# too lazy to lookup how this works again in Makefiles
restest: restest.go $(GOFILES)
@ -23,6 +23,9 @@ restest: restest.go $(GOFILES)
ednstest: ednstest.go $(GOFILES)
6g -I _obj ednstest.go && 6l -L _obj -o ednstest ednstest.6
ednstest2: ednstest2.go $(GOFILES)
6g -I _obj ednstest2.go && 6l -L _obj -o ednstest2 ednstest2.6
manglertest: manglertest.go $(GOFILES)
6g -I _obj manglertest.go && 6l -L _obj -o manglertest manglertest.6

6
edns.go
View File

@ -15,12 +15,10 @@ type Option struct {
}
// EDNS extended RR.
// If we are dealing with this, we might copy
// the RR_Header over to this type and allow for
// easy access
// Not used yet
type EDNS0_Header struct {
Name string "extended-name"
Opt uint16 // was type
Opt uint16 // was type, but is always TypeOPT
UDPSize uint16 // was class
ExtendedRcode uint8 // was TTL
Version uint8 // was TTL

36
ednstest.go Normal file
View File

@ -0,0 +1,36 @@
package main
// Test EDNS RR records
import (
"fmt"
"dns"
)
func main() {
sig := new(dns.RR_RRSIG)
sig.Hdr.Name = "miek.nl."
sig.Hdr.Rrtype = dns.TypeRRSIG
sig.Hdr.Class = dns.ClassINET
sig.Hdr.Ttl = 3600
sig.TypeCovered = dns.TypeDNSKEY
sig.Algorithm = dns.AlgRSASHA1
sig.Labels = 2
sig.OrigTtl = 4000
sig.Expiration = 1000
sig.Inception = 800
sig.KeyTag = 34641
sig.SignerName = "miek.nl."
sig.Sig = "AwEAAaHIwpx3w4VHKi6i1LHnTaWeHCL154Jug0Rtc9ji5qwPXpBo6A5sRv7cSsPQKPIwxLpyCrbJ4mr2L0EPOdvP6z6YfljK2ZmTbogU9aSU2fiq/4wjxbdkLyoDVgtO+JsxNN4bjr4WcWhsmk1Hg93FV9ZpkWb0Tbad8DFqNDzr//kZ"
fmt.Printf("%v\n", sig)
edns := new(dns.RR_OPT)
edns.Hdr.Name = "miek.nl."
edns.Hdr.Rrtype = dns.TypeOPT
edns.Hdr.Class = dns.ClassINET
edns.Hdr.Ttl = 3600
edns.Option = make([]dns.Option, 1)
edns.Option[0].Code = dns.OptionCodeNSID
edns.Option[0].Data = "lalalala"
fmt.Printf("%v\n", edns)
}

108
msg.go
View File

@ -67,20 +67,12 @@ var rcode_str = map[int]string{
// Pack a domain name s into msg[off:].
// Domain names are a sequence of counted strings
// split at the dots. They end with a zero-length string.
func packDomainName(s string, msg []byte, off int, edns bool) (off1 int, ok bool) {
func packDomainName(s string, msg []byte, off int) (off1 int, ok bool) {
// Add trailing dot to canonicalize name.
if n := len(s); n == 0 || s[n-1] != '.' {
s += "."
}
if edns {
// packing for edns is actually easy
msg[0] = 0x40 // 01 111111
msg[1] = 0x00
off += 2
return off, true
}
// Each dot ends a segment of the name.
// We trade each dot byte for a length byte.
// There is also a trailing zero.
@ -106,6 +98,10 @@ func packDomainName(s string, msg []byte, off int, edns bool) (off1 int, ok bool
begin = i + 1
}
}
// Root label is special
if s == "." {
return off,true
}
msg[off] = 0
off++
return off, true
@ -124,13 +120,13 @@ func packDomainName(s string, msg []byte, off int, edns bool) (off1 int, ok bool
// which is where the next record will start.
// In theory, the pointers are only allowed to jump backward.
// We let them jump anywhere and stop jumping after a while.
func unpackDomainName(msg []byte, off int) (s string, off1 int, ok, edns bool) {
func unpackDomainName(msg []byte, off int) (s string, off1 int, ok bool) {
s = ""
ptr := 0 // number of pointers followed
Loop:
for {
if off >= len(msg) {
return "", len(msg), false, false
return "", len(msg), false
}
c := int(msg[off])
off++
@ -142,23 +138,10 @@ Loop:
}
// literal string
if off+c > len(msg) {
return "", len(msg), false, false
return "", len(msg), false
}
s += string(msg[off:off+c]) + "."
off += c
case 0x40:
// Need a check if a RR has this, because
// we need to set RR_Heasder.Edns to true
// edns extended name, does not matter for
// the rest of the RR (which should be OPT)
// but the parsing here (is for now) relatively simple
// The name must be the root label aka 00
// TODO check! MG
println("*** Seeing EDNS")
edns = true
s = ""
off++
break Loop
case 0xC0:
// pointer to somewhere else in msg.
// remember location after first ptr,
@ -166,7 +149,7 @@ Loop:
// also, don't follow too many pointers --
// maybe there's a loop.
if off >= len(msg) {
return "", len(msg), false, false
return "", len(msg), false
}
c1 := msg[off]
off++
@ -174,24 +157,24 @@ Loop:
off1 = off
}
if ptr++; ptr > 10 {
return "", len(msg), false, false
return "", len(msg), false
}
off = (c^0xC0)<<8 | int(c1)
default:
// 0x80 and 0x40 are reserved
return "", len(msg), false, false
return "", len(msg), false
}
}
if ptr == 0 {
off1 = off
}
return s, off1, true, edns
return s, off1, true
}
// TODO(rsc): Move into generic library?
// Pack a reflect.StructValue into msg. Struct members can only be uint8, uint16, uint32, string,
// slices and other (often anonymous) structs.
func packStructValue(val *reflect.StructValue, msg []byte, off int, edns bool) (off1 int, ok bool) {
func packStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int, ok bool) {
for i := 0; i < val.NumField(); i++ {
f := val.Type().(*reflect.StructType).Field(i)
switch fv := val.Field(i).(type) {
@ -208,7 +191,6 @@ func packStructValue(val *reflect.StructValue, msg []byte, off int, edns bool) (
fmt.Fprintf(os.Stderr, "net: dns: unknown IP tag %v\n", f.Tag)
return len(msg), false
case "OPT": // edns
// Set the Hdr.Edns to true
for j := 0; j < val.Field(i).(*reflect.SliceValue).Len(); j++ {
println(j) // TODO MG
element := val.Field(i).(*reflect.SliceValue).Elem(j)
@ -245,7 +227,7 @@ func packStructValue(val *reflect.StructValue, msg []byte, off int, edns bool) (
}
}
case *reflect.StructValue:
off, ok = packStructValue(fv, msg, off, edns)
off, ok = packStructValue(fv, msg, off)
case *reflect.UintValue:
i := fv.Get()
switch fv.Type().Kind() {
@ -289,7 +271,7 @@ func packStructValue(val *reflect.StructValue, msg []byte, off int, edns bool) (
}
off += b64len
case "domain-name":
off, ok = packDomainName(s, msg, off, edns)
off, ok = packDomainName(s, msg, off)
if !ok {
return len(msg), false
}
@ -317,21 +299,21 @@ func structValue(any interface{}) *reflect.StructValue {
return reflect.NewValue(any).(*reflect.PtrValue).Elem().(*reflect.StructValue)
}
func packStruct(any interface{}, msg []byte, off int, edns bool) (off1 int, ok bool) {
off, ok = packStructValue(structValue(any), msg, off, edns)
func packStruct(any interface{}, msg []byte, off int) (off1 int, ok bool) {
off, ok = packStructValue(structValue(any), msg, off)
return off, ok
}
// Unpack a reflect.StructValue from msg.
// Same restrictions as packStructValue.
func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int, ok, edns bool) {
func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int, ok bool) {
for i := 0; i < val.NumField(); i++ {
f := val.Type().(*reflect.StructType).Field(i)
switch fv := val.Field(i).(type) {
default:
BadType:
fmt.Fprintf(os.Stderr, "net: dns: unknown packing type %v", f.Type)
return len(msg), false, false
return len(msg), false
case *reflect.BoolValue:
// Used internally for Edns, not present in the DNS
continue
@ -339,17 +321,17 @@ func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int,
switch f.Tag {
default:
fmt.Fprintf(os.Stderr, "net: dns: unknown IP tag %v", f.Tag)
return len(msg), false, false
return len(msg), false
case "A":
if off+net.IPv4len > len(msg) {
return len(msg), false, false
return len(msg), false
}
b := net.IPv4(msg[off], msg[off+1], msg[off+2], msg[off+3])
fv.Set(reflect.NewValue(b).(*reflect.SliceValue))
off += net.IPv4len
case "AAAA":
if off+net.IPv6len > len(msg) {
return len(msg), false, false
return len(msg), false
}
p := make(net.IP, net.IPv6len)
copy(p, msg[off:off+net.IPv6len])
@ -360,28 +342,28 @@ func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int,
// do it here
}
case *reflect.StructValue:
off, ok, edns = unpackStructValue(fv, msg, off)
off, ok = unpackStructValue(fv, msg, off)
case *reflect.UintValue:
switch fv.Type().Kind() {
default:
goto BadType
case reflect.Uint8:
if off+1 > len(msg) {
return len(msg), false, false
return len(msg), false
}
i := uint8(msg[off])
fv.Set(uint64(i))
off++
case reflect.Uint16:
if off+2 > len(msg) {
return len(msg), false, false
return len(msg), false
}
i := uint16(msg[off])<<8 | uint16(msg[off+1])
fv.Set(uint64(i))
off += 2
case reflect.Uint32:
if off+4 > len(msg) {
return len(msg), false, false
return len(msg), false
}
i := uint32(msg[off])<<24 | uint32(msg[off+1])<<16 | uint32(msg[off+2])<<8 | uint32(msg[off+3])
fv.Set(uint64(i))
@ -392,7 +374,7 @@ func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int,
switch f.Tag {
default:
fmt.Fprintf(os.Stderr, "net: dns: unknown string tag %v", f.Tag)
return len(msg), false, false
return len(msg), false
case "hex":
// Rest of the RR is hex encoded
rdlength := int(val.FieldByName("Hdr").(*reflect.StructValue).FieldByName("Rdlength").(*reflect.UintValue).Get())
@ -428,13 +410,13 @@ func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int,
s = string(b64)
off += rdlength - consumed
case "domain-name":
s, off, ok, edns = unpackDomainName(msg, off)
s, off, ok = unpackDomainName(msg, off)
if !ok {
return len(msg), false, false
return len(msg), false
}
case "":
if off >= len(msg) || off+1+int(msg[off]) > len(msg) {
return len(msg), false, false
return len(msg), false
}
n := int(msg[off])
off++
@ -448,12 +430,12 @@ func unpackStructValue(val *reflect.StructValue, msg []byte, off int) (off1 int,
fv.Set(s)
}
}
return off, true, edns
return off, true
}
func unpackStruct(any interface{}, msg []byte, off int) (off1 int, ok, edns bool) {
off, ok, edns = unpackStructValue(structValue(any), msg, off)
return off, ok, edns
func unpackStruct(any interface{}, msg []byte, off int) (off1 int, ok bool) {
off, ok = unpackStructValue(structValue(any), msg, off)
return off, ok
}
// THIS can GO TODO
@ -490,30 +472,26 @@ func packRR(rr RR, msg []byte, off int) (off2 int, ok bool) {
// a bit inefficient but this doesn't need to be fast.
// off1 is end of header
// off2 is end of rr
edns := rr.Header().Edns
off1, ok = packStruct(rr.Header(), msg, off, edns)
off2, ok = packStruct(rr, msg, off, edns)
off1, ok = packStruct(rr.Header(), msg, off)
off2, ok = packStruct(rr, msg, off)
if !ok {
return len(msg), false
}
// TODO make this quicker?
// pack a third time; redo header with correct data length
rr.Header().Rdlength = uint16(off2 - off1)
packStruct(rr.Header(), msg, off, edns)
packStruct(rr.Header(), msg, off)
return off2, true
}
// Resource record unpacker.
func unpackRR(msg []byte, off int) (rr RR, off1 int, ok bool) {
// unpack just the header, to find the rr type and length
// check if we have an edns packet, and set h.Edns to true
var h RR_Header
var edns bool
off0 := off
if off, ok, edns = unpackStruct(&h, msg, off); !ok {
if off, ok = unpackStruct(&h, msg, off); !ok {
return nil, len(msg), false
}
h.Edns = edns // set Edns if found
end := off + int(h.Rdlength)
// make an rr of that type and re-unpack.
@ -524,7 +502,7 @@ func unpackRR(msg []byte, off int) (rr RR, off1 int, ok bool) {
}
rr = mk()
off, ok, _ = unpackStruct(rr, msg, off0) // don't care about edns?
off, ok = unpackStruct(rr, msg, off0)
if off != end {
// added MG
// println("Hier gaat het dan fout, echt waar en was if off0", off0)
@ -651,9 +629,9 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
// Pack it in: header and then the pieces.
off := 0
off, ok = packStruct(&dh, msg, off, false)
off, ok = packStruct(&dh, msg, off)
for i := 0; i < len(question); i++ {
off, ok = packStruct(&question[i], msg, off, false)
off, ok = packStruct(&question[i], msg, off)
}
for i := 0; i < len(answer); i++ {
off, ok = packRR(answer[i], msg, off)
@ -675,7 +653,7 @@ func (dns *Msg) Unpack(msg []byte) bool {
var dh Header
off := 0
var ok bool
if off, ok, _ = unpackStruct(&dh, msg, off); !ok {
if off, ok = unpackStruct(&dh, msg, off); !ok {
return false
}
dns.Id = dh.Id
@ -694,7 +672,7 @@ func (dns *Msg) Unpack(msg []byte) bool {
dns.Extra = make([]RR, dh.Arcount)
for i := 0; i < len(dns.Question); i++ {
off, ok, _ = unpackStruct(&dns.Question[i], msg, off)
off, ok = unpackStruct(&dns.Question[i], msg, off)
}
for i := 0; i < len(dns.Answer); i++ {
dns.Answer[i], off, ok = unpackRR(msg, off)

6
resolverEdns_test.go
View File

@ -26,7 +26,7 @@ func TestResolverEdns(t *testing.T) {
edns.Hdr.Rrtype = TypeOPT
edns.Hdr.Class = ClassINET
edns.Hdr.Ttl = 3600
// no options
// no options for now
// edns.Option = make([]Option, 1)
// edns.Option[0].Code = OptionCodeNSID
// edns.Option[0].Data = "lalalala"
@ -35,7 +35,7 @@ func TestResolverEdns(t *testing.T) {
m.Question[0] = Question{"miek.nl", TypeSOA, ClassINET}
m.Extra[0] = edns
fmt.Printf("%v\n", m)
fmt.Printf("Sending: %v\n", m)
ch <- DnsMsg{m, nil}
in := <-ch
@ -44,7 +44,7 @@ func TestResolverEdns(t *testing.T) {
t.Log("Failed to get an valid answer")
t.Fail()
}
fmt.Printf("%v\n", in)
fmt.Printf("Recv: %v\n", in.Dns)
ch <- DnsMsg{nil, nil}
time.Sleep(1.0e9)