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plugin/file: fix less is not up to RFC 1034 and 4034 (#8503)

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* plugin/file: fix less to follow RFC 1034 and RFC 4034 matching and ordering requirements

- Ensure comparison is left-justified
- Ensure case folding applies only to A-Z
- Decode \DDD without allocations

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

* plugin/file: faster exit for less when a == b

Avoid two calls and two reslices.

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

* plugin/file: consolidate less tests

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

* plugin/file: exit less early when there are no more labels

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

* plugin/file: match dns.PackDomainName in handling \-escapes

Compare unterminated names as root-terminating

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

* plugin/file: More tests of less.

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>

---------

Signed-off-by: Ilya Kulakov <kulakov.ilya@gmail.com>
This commit is contained in:
Ilya Kulakov
2026-09-16 17:51:15 -07:00
committed by GitHub
parent b93e449b2f
commit 25eb456b57
2 changed files with 210 additions and 105 deletions
Download Patch File Download Diff File Expand all files Collapse all files

166
plugin/file/tree/less_test.go
View File

@@ -2,7 +2,8 @@ package tree
import (
"bytes"
"sort"
"cmp"
"slices"
"strings"
"sync"
"testing"
@@ -10,24 +11,18 @@ import (
"github.com/miekg/dns"
)
type set []string
func (p set) Len() int { return len(p) }
func (p set) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p set) Less(i, j int) bool { d := less(p[i], p[j]); return d <= 0 }
func TestLess(t *testing.T) {
tests := []struct {
in []string
out []string
}{
{
[]string{"aaa.powerdns.de", "bbb.powerdns.net.", "xxx.powerdns.com."},
[]string{"xxx.powerdns.com.", "aaa.powerdns.de", "bbb.powerdns.net."},
[]string{"aaa.powerdns.de.", "bbb.powerdns.net.", "xxx.powerdns.com."},
[]string{"xxx.powerdns.com.", "aaa.powerdns.de.", "bbb.powerdns.net."},
},
{
[]string{"aaa.POWERDNS.de", "bbb.PoweRdnS.net.", "xxx.powerdns.com."},
[]string{"xxx.powerdns.com.", "aaa.POWERDNS.de", "bbb.PoweRdnS.net."},
[]string{"aaa.POWERDNS.de.", "bbb.PoweRdnS.net.", "xxx.powerdns.com."},
[]string{"xxx.powerdns.com.", "aaa.POWERDNS.de.", "bbb.PoweRdnS.net."},
},
{
[]string{"aaa.aaaa.aa.", "aa.aaa.a.", "bbb.bbbb.bb."},
@@ -58,15 +53,7 @@ func TestLess(t *testing.T) {
Tests:
for j, test := range tests {
// Need to lowercase these example as the Less function does lowercase for us anymore.
for i, b := range test.in {
test.in[i] = strings.ToLower(b)
}
for i, b := range test.out {
test.out[i] = strings.ToLower(b)
}
sort.Sort(set(test.in))
slices.SortFunc(test.in, less)
for i := range len(test.in) {
if test.in[i] != test.out[i] {
t.Errorf("Test %d: expected %s, got %s", j, test.out[i], test.in[i])
@@ -83,21 +70,6 @@ Tests:
}
}
func TestLess_EmptyVsName(t *testing.T) {
if d := less("", "a."); d >= 0 {
t.Fatalf("expected < 0, got %d", d)
}
if d := less("a.", ""); d <= 0 {
t.Fatalf("expected > 0, got %d", d)
}
}
func TestLess_EmptyVsEmpty(t *testing.T) {
if d := less("", ""); d != 0 {
t.Fatalf("expected 0, got %d", d)
}
}
// Test that concurrent calls to Less (which calls Elem.Name) do not race or panic.
// See issue #7561 for reference.
func TestLess_ConcurrentNameAccess(t *testing.T) {
@@ -121,37 +93,67 @@ func TestLess_ConcurrentNameAccess(t *testing.T) {
wg.Wait()
}
func BenchmarkLess(b *testing.B) {
// The original less function, serving as the benchmark test baseline.
less0 := func(a, b string) int {
i := 1
aj := len(a)
bj := len(b)
for {
ai, oka := dns.PrevLabel(a, i)
bi, okb := dns.PrevLabel(b, i)
if oka && okb {
return 0
func TestLess_EdgeCases(t *testing.T) {
// For every case four variants are synthesized:
// - a b
// - a. b
// - a b.
// - a. b.
//
// For each variant commutativity is tested.
tests := []struct {
a, b string
variants bool
want int
}{
{``, ``, true, 0},
{``, `\000`, true, -1},
{``, `\.`, true, -1},
{`\.`, `\.`, true, 0},
{``, `example`, true, -1},
{`example`, `example`, true, 0},
{`a\.example`, `a.example`, true, -1},
{`a.example`, `a-b.example`, true, -1},
{`a.example`, `a*.example`, true, -1},
{`a.example`, `a\000.example`, true, -1},
{`a.eXaMpLe`, `a.example`, true, 0},
{`\000\0320 \"\046@*`, `\000\032\048\032\034\046\064\042`, true, 0},
{`<=>?@ABCDE`, `\060\061\062\063\064\065\066\067\068\069`, true, 0},
{`<=>?@ABCDE`, `\060\061\062\063\064\097\098\099\100\101`, true, 0},
{`café.example`, `CAFÉ.example`, true, 1}, // é (\195\169) > É (\195\137)
{`\\065.example`, `\\097.example`, true, -1},
{``, `\`, false, 0},
{`a\.b.example`, `a\046b.example`, true, 0},
{`0.example`, `\0.example`, true, 0},
{`01.example`, `\01.example`, true, 0},
{`a\.b.example`, `a\046b.example`, true, 0},
{`\\.example`, `\092.example`, true, 0},
}
for i, test := range tests {
variants := []struct{ a, b string }{
{test.a, test.b},
{test.a + `.`, test.b},
{test.a, test.b + `.`},
{test.a + `.`, test.b + `.`},
}
if !test.variants {
variants = variants[:1]
}
for _, variant := range variants {
if got := less(variant.a, variant.b); cmp.Compare(got, 0) != test.want {
t.Errorf("Test %d: expected less(%s, %s)=%d, got %d", i, variant.a, variant.b, test.want, cmp.Compare(got, 0))
}
// sadly this []byte will allocate... TODO(miek): check if this is needed
// for a name, otherwise compare the strings.
ab := []byte(strings.ToLower(a[ai:aj]))
bb := []byte(strings.ToLower(b[bi:bj]))
doDDD(ab)
doDDD(bb)
res := bytes.Compare(ab, bb)
if res != 0 {
return res
if got := less(variant.b, variant.a); cmp.Compare(got, 0) != -test.want {
t.Errorf("Test %d: expected less(%s, %s)=%d, got %d", i, variant.b, variant.a, -test.want, cmp.Compare(got, 0))
}
i++
aj, bj = ai, bi
}
}
}
tests := []set{
func BenchmarkLess(b *testing.B) {
tests := [][]string{
{"aaa.powerdns.de", "bbb.powerdns.net.", "xxx.powerdns.com."},
{"aaa.POWERDNS.de", "bbb.PoweRdnS.net.", "xxx.powerdns.com."},
{"aaa.aaaa.aa.", "aa.aaa.a.", "bbb.bbbb.bb."},
@@ -187,3 +189,47 @@ func BenchmarkLess(b *testing.B) {
}
})
}
// The original less function, serving as the benchmark test baseline.
func less0(a, b string) int {
i := 1
aj := len(a)
bj := len(b)
for {
ai, oka := dns.PrevLabel(a, i)
bi, okb := dns.PrevLabel(b, i)
if oka && okb {
return 0
}
// sadly this []byte will allocate... TODO(miek): check if this is needed
// for a name, otherwise compare the strings.
ab := []byte(strings.ToLower(a[ai:aj]))
bb := []byte(strings.ToLower(b[bi:bj]))
doDDD(ab)
doDDD(bb)
res := bytes.Compare(ab, bb)
if res != 0 {
return res
}
i++
aj, bj = ai, bi
}
}
func doDDD(b []byte) {
lb := len(b)
for i := 0; i < lb; i++ {
if i+3 < lb && b[i] == '\\' && isDigit(b[i+1]) && isDigit(b[i+2]) && isDigit(b[i+3]) {
b[i] = dddToByte(b[i:])
for j := i + 1; j < lb-3; j++ {
b[j] = b[j+3]
}
lb -= 3
}
}
}
func isDigit(b byte) bool { return b >= '0' && b <= '9' }
func dddToByte(s []byte) byte { return (s[1]-'0')*100 + (s[2]-'0')*10 + (s[3] - '0') }