Take the max compression offset into account in Len(). (#658)

This offset max was not taking into account leading Len() to emit a
smaller value that could not be matched by Pack(), i.e all names can
be fully compressed or used as a target for compression.

Split length tests off in seperate file length_test.go to clean up
dns_test.og a bit.
This commit is contained in:
Miek Gieben 2018-04-01 09:45:32 +01:00 committed by GitHub
parent d174bbf0a5
commit dfb943b13e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 213 additions and 169 deletions

View File

@ -142,152 +142,6 @@ func TestPackNAPTR(t *testing.T) {
}
}
func TestCompressLength(t *testing.T) {
m := new(Msg)
m.SetQuestion("miek.nl", TypeMX)
ul := m.Len()
m.Compress = true
if ul != m.Len() {
t.Fatalf("should be equal")
}
}
// Does the predicted length match final packed length?
func TestMsgCompressLength(t *testing.T) {
makeMsg := func(question string, ans, ns, e []RR) *Msg {
msg := new(Msg)
msg.SetQuestion(Fqdn(question), TypeANY)
msg.Answer = append(msg.Answer, ans...)
msg.Ns = append(msg.Ns, ns...)
msg.Extra = append(msg.Extra, e...)
msg.Compress = true
return msg
}
name1 := "12345678901234567890123456789012345.12345678.123."
rrA := testRR(name1 + " 3600 IN A 192.0.2.1")
rrMx := testRR(name1 + " 3600 IN MX 10 " + name1)
tests := []*Msg{
makeMsg(name1, []RR{rrA}, nil, nil),
makeMsg(name1, []RR{rrMx, rrMx}, nil, nil)}
for _, msg := range tests {
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted < len(buf) {
t.Errorf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d",
msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
}
}
}
func TestMsgLength(t *testing.T) {
makeMsg := func(question string, ans, ns, e []RR) *Msg {
msg := new(Msg)
msg.SetQuestion(Fqdn(question), TypeANY)
msg.Answer = append(msg.Answer, ans...)
msg.Ns = append(msg.Ns, ns...)
msg.Extra = append(msg.Extra, e...)
return msg
}
name1 := "12345678901234567890123456789012345.12345678.123."
rrA := testRR(name1 + " 3600 IN A 192.0.2.1")
rrMx := testRR(name1 + " 3600 IN MX 10 " + name1)
tests := []*Msg{
makeMsg(name1, []RR{rrA}, nil, nil),
makeMsg(name1, []RR{rrMx, rrMx}, nil, nil)}
for _, msg := range tests {
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted < len(buf) {
t.Errorf("predicted length is wrong: predicted %s (len=%d), actual %d",
msg.Question[0].Name, predicted, len(buf))
}
}
}
func TestMsgLength2(t *testing.T) {
// Serialized replies
var testMessages = []string{
// google.com. IN A?
"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",
// amazon.com. IN A? (reply has no EDNS0 record)
// TODO(miek): this one is off-by-one, need to find out why
//"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",
// yahoo.com. IN A?
"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",
// microsoft.com. IN A?
"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",
// google.com. IN MX?
"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",
// reddit.com. IN A?
"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",
}
for i, hexData := range testMessages {
// we won't fail the decoding of the hex
input, _ := hex.DecodeString(hexData)
m := new(Msg)
m.Unpack(input)
m.Compress = true
lenComp := m.Len()
b, _ := m.Pack()
pacComp := len(b)
m.Compress = false
lenUnComp := m.Len()
b, _ = m.Pack()
pacUnComp := len(b)
if pacComp+1 != lenComp {
t.Errorf("msg.Len(compressed)=%d actual=%d for test %d", lenComp, pacComp, i)
}
if pacUnComp+1 != lenUnComp {
t.Errorf("msg.Len(uncompressed)=%d actual=%d for test %d", lenUnComp, pacUnComp, i)
}
}
}
func TestMsgLengthCompressionMalformed(t *testing.T) {
// SOA with empty hostmaster, which is illegal
soa := &SOA{Hdr: RR_Header{Name: ".", Rrtype: TypeSOA, Class: ClassINET, Ttl: 12345},
Ns: ".",
Mbox: "",
Serial: 0,
Refresh: 28800,
Retry: 7200,
Expire: 604800,
Minttl: 60}
m := new(Msg)
m.Compress = true
m.Ns = []RR{soa}
m.Len() // Should not crash.
}
func TestMsgCompressLength2(t *testing.T) {
msg := new(Msg)
msg.Compress = true
msg.SetQuestion(Fqdn("bliep."), TypeANY)
msg.Answer = append(msg.Answer, &SRV{Hdr: RR_Header{Name: "blaat.", Rrtype: 0x21, Class: 0x1, Ttl: 0x3c}, Port: 0x4c57, Target: "foo.bar."})
msg.Extra = append(msg.Extra, &A{Hdr: RR_Header{Name: "foo.bar.", Rrtype: 0x1, Class: 0x1, Ttl: 0x3c}, A: net.IP{0xac, 0x11, 0x0, 0x3}})
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted != len(buf) {
t.Errorf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d",
msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
}
}
func TestToRFC3597(t *testing.T) {
a := testRR("miek.nl. IN A 10.0.1.1")
x := new(RFC3597)

174
length_test.go Normal file
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@ -0,0 +1,174 @@
package dns
import (
"encoding/hex"
"fmt"
"net"
"testing"
)
func TestCompressLength(t *testing.T) {
m := new(Msg)
m.SetQuestion("miek.nl", TypeMX)
ul := m.Len()
m.Compress = true
if ul != m.Len() {
t.Fatalf("should be equal")
}
}
// Does the predicted length match final packed length?
func TestMsgCompressLength(t *testing.T) {
makeMsg := func(question string, ans, ns, e []RR) *Msg {
msg := new(Msg)
msg.SetQuestion(Fqdn(question), TypeANY)
msg.Answer = append(msg.Answer, ans...)
msg.Ns = append(msg.Ns, ns...)
msg.Extra = append(msg.Extra, e...)
msg.Compress = true
return msg
}
name1 := "12345678901234567890123456789012345.12345678.123."
rrA := testRR(name1 + " 3600 IN A 192.0.2.1")
rrMx := testRR(name1 + " 3600 IN MX 10 " + name1)
tests := []*Msg{
makeMsg(name1, []RR{rrA}, nil, nil),
makeMsg(name1, []RR{rrMx, rrMx}, nil, nil)}
for _, msg := range tests {
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted < len(buf) {
t.Errorf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d",
msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
}
}
}
func TestMsgLength(t *testing.T) {
makeMsg := func(question string, ans, ns, e []RR) *Msg {
msg := new(Msg)
msg.SetQuestion(Fqdn(question), TypeANY)
msg.Answer = append(msg.Answer, ans...)
msg.Ns = append(msg.Ns, ns...)
msg.Extra = append(msg.Extra, e...)
return msg
}
name1 := "12345678901234567890123456789012345.12345678.123."
rrA := testRR(name1 + " 3600 IN A 192.0.2.1")
rrMx := testRR(name1 + " 3600 IN MX 10 " + name1)
tests := []*Msg{
makeMsg(name1, []RR{rrA}, nil, nil),
makeMsg(name1, []RR{rrMx, rrMx}, nil, nil)}
for _, msg := range tests {
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted < len(buf) {
t.Errorf("predicted length is wrong: predicted %s (len=%d), actual %d",
msg.Question[0].Name, predicted, len(buf))
}
}
}
func TestMsgLength2(t *testing.T) {
// Serialized replies
var testMessages = []string{
// google.com. IN A?
"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",
// amazon.com. IN A? (reply has no EDNS0 record)
// TODO(miek): this one is off-by-one, need to find out why
//"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",
// yahoo.com. IN A?
"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",
// microsoft.com. IN A?
"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",
// google.com. IN MX?
"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",
// reddit.com. IN A?
"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",
}
for i, hexData := range testMessages {
// we won't fail the decoding of the hex
input, _ := hex.DecodeString(hexData)
m := new(Msg)
m.Unpack(input)
m.Compress = true
lenComp := m.Len()
b, _ := m.Pack()
pacComp := len(b)
m.Compress = false
lenUnComp := m.Len()
b, _ = m.Pack()
pacUnComp := len(b)
if pacComp+1 != lenComp {
t.Errorf("msg.Len(compressed)=%d actual=%d for test %d", lenComp, pacComp, i)
}
if pacUnComp+1 != lenUnComp {
t.Errorf("msg.Len(uncompressed)=%d actual=%d for test %d", lenUnComp, pacUnComp, i)
}
}
}
func TestMsgLengthCompressionMalformed(t *testing.T) {
// SOA with empty hostmaster, which is illegal
soa := &SOA{Hdr: RR_Header{Name: ".", Rrtype: TypeSOA, Class: ClassINET, Ttl: 12345},
Ns: ".",
Mbox: "",
Serial: 0,
Refresh: 28800,
Retry: 7200,
Expire: 604800,
Minttl: 60}
m := new(Msg)
m.Compress = true
m.Ns = []RR{soa}
m.Len() // Should not crash.
}
func TestMsgCompressLength2(t *testing.T) {
msg := new(Msg)
msg.Compress = true
msg.SetQuestion(Fqdn("bliep."), TypeANY)
msg.Answer = append(msg.Answer, &SRV{Hdr: RR_Header{Name: "blaat.", Rrtype: 0x21, Class: 0x1, Ttl: 0x3c}, Port: 0x4c57, Target: "foo.bar."})
msg.Extra = append(msg.Extra, &A{Hdr: RR_Header{Name: "foo.bar.", Rrtype: 0x1, Class: 0x1, Ttl: 0x3c}, A: net.IP{0xac, 0x11, 0x0, 0x3}})
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted != len(buf) {
t.Errorf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d",
msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
}
}
func TestMsgCompressLengthLargeRecords(t *testing.T) {
msg := new(Msg)
msg.Compress = true
msg.SetQuestion("my.service.acme.", TypeSRV)
j := 1
for i := 0; i < 250; i++ {
target := fmt.Sprintf("host-redis-%d-%d.test.acme.com.node.dc1.consul.", j, i)
msg.Answer = append(msg.Answer, &SRV{Hdr: RR_Header{Name: "redis.service.consul.", Class: 1, Rrtype: TypeSRV, Ttl: 0x3c}, Port: 0x4c57, Target: target})
msg.Extra = append(msg.Extra, &CNAME{Hdr: RR_Header{Name: target, Class: 1, Rrtype: TypeCNAME, Ttl: 0x3c}, Target: fmt.Sprintf("fx.168.%d.%d.", j, i)})
}
predicted := msg.Len()
buf, err := msg.Pack()
if err != nil {
t.Error(err)
}
if predicted != len(buf) {
t.Fatalf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d", msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
}
}

62
msg.go
View File

@ -933,49 +933,65 @@ func compressedLen(dns *Msg, compress bool) int {
l += r.len()
compressionLenHelper(compression, r.Name)
}
l += compressionLenSlice(compression, dns.Answer)
l += compressionLenSlice(compression, dns.Ns)
l += compressionLenSlice(compression, dns.Extra)
} else {
for _, r := range dns.Question {
l += compressionLenSlice(l, compression, dns.Answer)
l += compressionLenSlice(l, compression, dns.Ns)
l += compressionLenSlice(l, compression, dns.Extra)
return l
}
for _, r := range dns.Question {
l += r.len()
}
for _, r := range dns.Answer {
if r != nil {
l += r.len()
}
for _, r := range dns.Answer {
if r != nil {
l += r.len()
}
}
for _, r := range dns.Ns {
if r != nil {
l += r.len()
}
}
for _, r := range dns.Extra {
if r != nil {
l += r.len()
}
}
for _, r := range dns.Ns {
if r != nil {
l += r.len()
}
}
for _, r := range dns.Extra {
if r != nil {
l += r.len()
}
}
return l
}
func compressionLenSlice(c map[string]int, rs []RR) int {
func compressionLenSlice(len int, c map[string]int, rs []RR) int {
var l int
for _, r := range rs {
if r == nil {
continue
}
l += r.len()
// track this length, and the global length in len, while taking compression into account for both.
x := r.len()
l += x
len += x
k, ok := compressionLenSearch(c, r.Header().Name)
if ok {
l += 1 - k
len += 1 - k
}
compressionLenHelper(c, r.Header().Name)
if len < maxCompressionOffset {
compressionLenHelper(c, r.Header().Name)
}
k, ok = compressionLenSearchType(c, r)
if ok {
l += 1 - k
len += 1 - k
}
if len < maxCompressionOffset {
compressionLenHelperType(c, r)
}
compressionLenHelperType(c, r)
}
return l
}