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More fixes for compression

This commit is contained in:
Miek Gieben 2012-01-11 11:13:17 +01:00
parent f66bb9d6f5
commit 974c28d1b1
5 changed files with 41 additions and 161 deletions
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12
dnssec.go
View File

@ -91,7 +91,7 @@ func (k *RR_DNSKEY) KeyTag() uint16 {
keywire.Algorithm = k.Algorithm
keywire.PublicKey = k.PublicKey
wire := make([]byte, DefaultMsgSize)
n, ok := packStruct(keywire, wire, 0)
n, ok := packStruct(keywire, wire, 0, nil)
if !ok {
return 0
}
@ -126,14 +126,14 @@ func (k *RR_DNSKEY) ToDS(h int) *RR_DS {
keywire.Algorithm = k.Algorithm
keywire.PublicKey = k.PublicKey
wire := make([]byte, DefaultMsgSize)
n, ok := packStruct(keywire, wire, 0)
n, ok := packStruct(keywire, wire, 0, nil)
if !ok {
return nil
}
wire = wire[:n]
owner := make([]byte, 255)
off, ok1 := PackDomainName(k.Hdr.Name, owner, 0)
off, ok1 := PackDomainName(k.Hdr.Name, owner, 0, nil)
if !ok1 {
return nil
}
@ -205,7 +205,7 @@ func (s *RR_RRSIG) Sign(k PrivateKey, rrset RRset) error {
// Create the desired binary blob
signdata := make([]byte, DefaultMsgSize)
n, ok := packStruct(sigwire, signdata, 0)
n, ok := packStruct(sigwire, signdata, 0, nil)
if !ok {
return ErrPack
}
@ -300,7 +300,7 @@ func (s *RR_RRSIG) Verify(k *RR_DNSKEY, rrset RRset) error {
sigwire.SignerName = strings.ToLower(s.SignerName)
// Create the desired binary blob
signeddata := make([]byte, DefaultMsgSize)
n, ok := packStruct(sigwire, signeddata, 0)
n, ok := packStruct(sigwire, signeddata, 0, nil)
if !ok {
return ErrPack
}
@ -492,7 +492,7 @@ func rawSignatureData(rrset RRset, s *RR_RRSIG) (buf []byte) {
ttl := h.Ttl
h.Ttl = s.OrigTtl
wire := make([]byte, DefaultMsgSize)
off, ok1 := packRR(r, wire, 0)
off, ok1 := packRR(r, wire, 0, nil)
wire = wire[:off]
h.Ttl = ttl // restore the order in the universe TODO(mg) work on copy
h.Name = name

45
msg.go
View File

@ -18,6 +18,7 @@ import (
"encoding/base32"
"encoding/base64"
"encoding/hex"
"fmt"
"math/rand"
"net"
"reflect"
@ -25,6 +26,8 @@ import (
"time"
)
const MaxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer
var (
ErrUnpack error = &Error{Err: "unpacking failed"}
ErrPack error = &Error{Err: "packing failed"}
@ -174,7 +177,7 @@ var Rcode_str = map[int]string{
// PackDomainName packs 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) (off1 int, ok bool) {
func PackDomainName(s string, msg []byte, off int, compression map[string]int) (off1 int, ok bool) {
// Add trailing dot to canonicalize name.
lenmsg := len(msg)
if n := len(s); n == 0 || s[n-1] != '.' {
@ -211,11 +214,21 @@ func PackDomainName(s string, msg []byte, off int) (off1 int, ok bool) {
return lenmsg, false
}
msg[off] = byte(i - begin)
offset := off
off++
for j := begin; j < i; j++ {
msg[off] = bs[j]
off++
}
str, _, ok := UnpackDomainName(msg, offset)
if !ok {
// hmmm how can this be?
}
if compression != nil {
if _, ok := compression[str]; !ok {
compression[str] = offset
}
}
begin = i + 1
}
}
@ -303,7 +316,7 @@ Loop:
// 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.Value, msg []byte, off int) (off1 int, ok bool) {
func packStructValue(val reflect.Value, msg []byte, off int, compression map[string]int) (off1 int, ok bool) {
for i := 0; i < val.NumField(); i++ {
// f := val.Type().Field(i)
lenmsg := len(msg)
@ -382,7 +395,7 @@ func packStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok bool)
// TODO(mg)
}
case reflect.Struct:
off, ok = packStructValue(fv, msg, off)
off, ok = packStructValue(fv, msg, off, compression)
case reflect.Uint8:
if off+1 > lenmsg {
//fmt.Fprintf(os.Stderr, "dns: overflow packing uint8")
@ -449,7 +462,7 @@ func packStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok bool)
copy(msg[off:off+len(b64)], b64)
off += len(b64)
case "domain-name":
off, ok = PackDomainName(s, msg, off)
off, ok = PackDomainName(s, msg, off, compression)
if !ok {
//fmt.Fprintf(os.Stderr, "dns: overflow packing domain-name")
return lenmsg, false
@ -500,8 +513,8 @@ func structValue(any interface{}) reflect.Value {
return reflect.ValueOf(any).Elem()
}
func packStruct(any interface{}, msg []byte, off int) (off1 int, ok bool) {
off, ok = packStructValue(structValue(any), msg, off)
func packStruct(any interface{}, msg []byte, off int, compression map[string]int) (off1 int, ok bool) {
off, ok = packStructValue(structValue(any), msg, off, compression)
return off, ok
}
@ -829,7 +842,7 @@ func packBase32(s []byte) ([]byte, error) {
}
// Resource record packer.
func packRR(rr RR, msg []byte, off int) (off2 int, ok bool) {
func packRR(rr RR, msg []byte, off int, compression map[string]int) (off2 int, ok bool) {
if rr == nil {
return len(msg), false
}
@ -840,15 +853,15 @@ 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
off1, ok = packStruct(rr.Header(), msg, off)
off2, ok = packStruct(rr, msg, off)
off1, ok = packStruct(rr.Header(), msg, off, compression)
off2, ok = packStruct(rr, msg, off, compression)
if !ok {
return len(msg), false
}
// pack a third time; redo header with correct data length
rr.Header().Rdlength = uint16(off2 - off1)
packStruct(rr.Header(), msg, off)
packStruct(rr.Header(), msg, off, compression)
return off2, true
// rr.Header().Rdlength = uint16(off2 - off1)
// if !rr.Header().RawSetRdlength(msg, off) {
@ -943,6 +956,7 @@ func (h *MsgHdr) String() string {
// Pack a msg: convert it to wire format.
func (dns *Msg) Pack() (msg []byte, ok bool) {
var dh Header
compression := make(map[string]int) // Compression pointer mappings
// Convert convenient Msg into wire-like Header.
dh.Id = dns.Id
@ -988,26 +1002,27 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
// Pack it in: header and then the pieces.
off := 0
off, ok = packStruct(&dh, msg, off)
off, ok = packStruct(&dh, msg, off, compression)
for i := 0; i < len(question); i++ {
off, ok = packStruct(&question[i], msg, off)
off, ok = packStruct(&question[i], msg, off, compression)
// println("Question", off)
}
for i := 0; i < len(answer); i++ {
off, ok = packRR(answer[i], msg, off)
off, ok = packRR(answer[i], msg, off, compression)
// println("Answer", off)
}
for i := 0; i < len(ns); i++ {
off, ok = packRR(ns[i], msg, off)
off, ok = packRR(ns[i], msg, off, compression)
// println("Authority", off)
}
for i := 0; i < len(extra); i++ {
off, ok = packRR(extra[i], msg, off)
off, ok = packRR(extra[i], msg, off, compression)
// println("Additional", off)
}
if !ok {
return nil, false
}
fmt.Printf("**%v\n", compression)
return msg[:off], true
}

4
nsec3.go
View File

@ -17,13 +17,13 @@ func HashName(label string, ha, iter int, salt string) string {
saltwire := new(saltWireFmt)
saltwire.Salt = salt
wire := make([]byte, DefaultMsgSize)
n, ok := packStruct(saltwire, wire, 0)
n, ok := packStruct(saltwire, wire, 0, nil)
if !ok {
return ""
}
wire = wire[:n]
name := make([]byte, 255)
off, ok1 := PackDomainName(strings.ToLower(label), name, 0)
off, ok1 := PackDomainName(strings.ToLower(label), name, 0, nil)
if !ok1 {
return ""
}

135
rawmsg.go
View File

@ -8,8 +8,6 @@ import (
"fmt"
)
const maxPointer = 2 << 13 // We have 14 bits for the offset
// Function defined in this subpackage work on []byte and but still
// provide some higher level functions.
@ -18,136 +16,3 @@ func RawSetId(msg []byte, off int, id uint16) bool {
msg[off], msg[off+1] = packUint16(id)
return true
}
type rawlabel struct {
offset int // offset where this labels starts in the msg buf
name string // the label, not this includes the length at the start
}
type rawmove struct {
offset int // where to point to
from int // where in the buffer set the pointer
length int // used in calculating how much to shrink the message
}
// Compress performs name compression in the dns message contained in buf.
// It returns the shortened buffer.
func Compress(msg []byte) []byte {
// First we create a table of domain names to which we
// can link. This is stored in 'table'
// Once, for another name, the longest possible link is
// found we save how we must change msg to perform this
// compression. This is saved in 'moves'. After we
// traversed the entire message, we perform all the
// moves.
// TODO: Maybe it should be optimized.
// TODO: put this in the packRR function
// TODO: only compresses owner names, not the well known RR
// These all those defined in 1035, important ones: CNAME, MX, NS, PTR, SOA
// Map the labels to the offset in the message
table := make(map[string]int)
moves := make([]rawmove, 0)
l := make([]rawlabel, 127) // Max labels?
i := 0
// Very much like the loop in msg.go
off := 12 // Start of the first name in the q section
question := true
Loop:
for {
c := int(msg[off])
switch c & 0xC0 {
case 0x00:
if c == 0x00 {
// Do all of the bookkeeping
name := ""
poffset := 0 // Where to point to
moffset := 0 // From where to insert the pointer
for j := i - 1; j >= 0; j-- {
name = l[j].name + name
if idx, ok := table[name]; !ok {
table[name] = l[j].offset
} else {
poffset = idx
moffset = l[j].offset
}
}
if poffset != 0 {
//println("We kunnen verwijzen naar", poffset, "vanaf", moffset, "voor", name)
//println("met lengte", len(name)+1)
// the +1 for the name is for the null byte at the end
// Discount for previous moves, decrease the poffset counter
// with moves that occur before it
for i := len(moves) - 1; i >= 0; i-- {
if poffset > moves[i].from {
poffset -= (moves[i].length - 2)
}
}
// Only need to shorten the RR when I'm shortening the rdata
moves = append(moves, rawmove{offset: poffset, from: moffset, length: len(name) + 1})
}
// end of the name
if question {
// In question section
off += 4 // type, class + 1
question = false
} else {
// How to handle well known records here
// NS, MX, CNAME? eatName() function?
// In the "body" of the msg
t, _ := unpackUint16(msg, off+1)
switch t {
case TypeMX:
println("MX")
// get the labels n check
}
off += 2 + 2 + 4 + 1 // type, class, ttl + 1
// we are at the rdlength
rdlength, _ := unpackUint16(msg, off)
off += int(rdlength) + 1 // Skip the rdata
}
off++
if off+1 > len(msg) {
break Loop
}
i = 0
continue Loop
}
if off+c+1 > len(msg) {
break Loop
}
// If we are too deep in the message we cannot point to
// it, otherwise we can just save it.
if off < maxPointer {
l[i] = rawlabel{offset: off, name: string(msg[off : off+c+1])}
i++
}
// save the new names
off += c + 1
default:
break Loop
}
}
// fmt.Printf("table %v\n", table)
// fmt.Printf("moves %v\n", moves)
saved := 0
// Start at the back, easier to move
for i := len(moves) - 1; i >= 0; i-- {
fmt.Printf("%v\n", moves[i])
// move the bytes
copy(msg[moves[i].from+1:], msg[moves[i].from+moves[i].length-1:])
// Now set the pointer at moves[i].from and moves[i].from+1
fmt.Printf("bits %b\n", moves[i].offset^0xC000)
msg[moves[i].from], msg[moves[i].from+1] = packUint16(uint16(moves[i].offset ^ 0xC000))
saved += (moves[i].length - 2) // minus something
}
msg = msg[:len(msg)-saved]
return msg
}

6
tsig.go
View File

@ -161,7 +161,7 @@ func tsigBuffer(msgbuf []byte, rr *RR_TSIG, requestMAC string, timersOnly bool)
m.MACSize = uint16(len(requestMAC) / 2)
m.MAC = requestMAC
macbuf = make([]byte, len(requestMAC)) // reqmac should be twice as long
n, _ := packStruct(m, macbuf, 0)
n, _ := packStruct(m, macbuf, 0, nil)
macbuf = macbuf[:n]
}
@ -170,7 +170,7 @@ func tsigBuffer(msgbuf []byte, rr *RR_TSIG, requestMAC string, timersOnly bool)
tsig := new(timerWireFmt)
tsig.TimeSigned = rr.TimeSigned
tsig.Fudge = rr.Fudge
n, _ := packStruct(tsig, tsigvar, 0)
n, _ := packStruct(tsig, tsigvar, 0, nil)
tsigvar = tsigvar[:n]
} else {
tsig := new(tsigWireFmt)
@ -183,7 +183,7 @@ func tsigBuffer(msgbuf []byte, rr *RR_TSIG, requestMAC string, timersOnly bool)
tsig.Error = rr.Error
tsig.OtherLen = rr.OtherLen
tsig.OtherData = rr.OtherData
n, _ := packStruct(tsig, tsigvar, 0)
n, _ := packStruct(tsig, tsigvar, 0, nil)
tsigvar = tsigvar[:n]
}
if rr.MAC != "" {