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Revert "labels: eliminate most allocations and improve perf by 15-65% (#1007)" (#1022) 

This reverts commit ab6ac402ba.

This break CoreDNS tests and probably a lot of other apps as well.
Reverted
This commit is contained in:
Miek Gieben 2019-10-04 10:26:59 +01:00 committed by GitHub
parent 041b4bc010
commit 1cd342c79a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 115 additions and 172 deletions
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177
labels.go
View File

@ -13,29 +13,27 @@ func SplitDomainName(s string) (labels []string) {
if len(s) == 0 {
return nil
}
if s == "." {
return nil
}
// offset of the final '.' or the length of the name
var fqdnEnd int
fqdnEnd := 0 // offset of the final '.' or the length of the name
idx := Split(s)
begin := 0
if IsFqdn(s) {
fqdnEnd = len(s) - 1
} else {
fqdnEnd = len(s)
}
var (
begin int
off int
end bool
)
for {
off, end = NextLabel(s, off)
if end {
break
switch len(idx) {
case 0:
return nil
case 1:
// no-op
default:
for _, end := range idx[1:] {
labels = append(labels, s[begin:end-1])
begin = end
}
labels = append(labels, s[begin:off-1])
begin = off
}
return append(labels, s[begin:fqdnEnd])
}
@ -54,50 +52,52 @@ func CompareDomainName(s1, s2 string) (n int) {
return 0
}
j1 := len(s1)
if s1[j1-1] == '.' {
j1--
l1 := Split(s1)
l2 := Split(s2)
j1 := len(l1) - 1 // end
i1 := len(l1) - 2 // start
j2 := len(l2) - 1
i2 := len(l2) - 2
// the second check can be done here: last/only label
// before we fall through into the for-loop below
if equal(s1[l1[j1]:], s2[l2[j2]:]) {
n++
} else {
return
}
j2 := len(s2)
if s2[j2-1] == '.' {
j2--
}
var i1, i2 int
for {
i1 = prevLabel(s1, j1-1)
i2 = prevLabel(s2, j2-1)
if equal(s1[i1:j1], s2[i2:j2]) {
if i1 < 0 || i2 < 0 {
break
}
if equal(s1[l1[i1]:l1[j1]], s2[l2[i2]:l2[j2]]) {
n++
} else {
break
}
if i1 == 0 || i2 == 0 {
break
}
j1 = i1 - 2
j2 = i2 - 2
j1--
i1--
j2--
i2--
}
return
}
// CountLabel counts the the number of labels in the string s.
// s must be a syntactically valid domain name.
func CountLabel(s string) int {
func CountLabel(s string) (labels int) {
if s == "." {
return 0
return
}
labels := 1
for i := 0; i < len(s)-1; i++ {
c := s[i]
if c == '\\' {
i++
continue
}
if c == '.' {
labels++
off := 0
end := false
for {
off, end = NextLabel(s, off)
labels++
if end {
return
}
}
return labels
}
// Split splits a name s into its label indexes.
@ -126,70 +126,40 @@ func Split(s string) []int {
// The bool end is true when the end of the string has been reached.
// Also see PrevLabel.
func NextLabel(s string, offset int) (i int, end bool) {
quote := false
for i = offset; i < len(s)-1; i++ {
c := s[i]
if c == '\\' {
i++
continue
}
if c == '.' {
switch s[i] {
case '\\':
quote = !quote
default:
quote = false
case '.':
if quote {
quote = !quote
continue
}
return i + 1, false
}
}
return i + 1, true
}
func prevLabel(s string, offset int) int {
for i := offset; i >= 0; i-- {
if s[i] == '.' {
if i == 0 || s[i-1] != '\\' {
return i + 1 // the '.' is not escaped
}
// We are at '\.' and need to check if the '\' itself is escaped.
// We do this by walking backwards from '\.' and counting the
// number of '\' we encounter. If the number of '\' is even
// (though here it's actually odd since we start at '\.') the '\'
// is escaped.
j := i - 2
for ; j >= 0 && s[j] == '\\'; j-- {
}
// An odd number here indicates that the '\' preceding the '.'
// is escaped.
if (i-j)&1 == 1 {
return i + 1
}
i = j + 1
}
}
return 0
}
// PrevLabel returns the index of the label when starting from the right and
// jumping n labels to the left.
// The bool start is true when the start of the string has been overshot.
// Also see NextLabel.
func PrevLabel(s string, n int) (i int, start bool) {
if s == "." {
return 0, true
}
if n == 0 {
return len(s), false
}
i = len(s) - 1
if s[i] == '.' {
i--
}
for ; n > 0; n-- {
i = prevLabel(s, i)
if i == 0 {
break
}
i -= 2
}
if n > 0 {
lab := Split(s)
if lab == nil {
return 0, true
}
return i + 2, false
if n > len(lab) {
return 0, true
}
return lab[len(lab)-n], false
}
// equal compares a and b while ignoring case. It returns true when equal otherwise false.
@ -200,19 +170,18 @@ func equal(a, b string) bool {
if la != lb {
return false
}
if a != b {
// case-insensitive comparison
for i := la - 1; i >= 0; i-- {
ai := a[i]
bi := b[i]
if ai != bi {
if bi < ai {
bi, ai = ai, bi
}
if !('A' <= ai && ai <= 'Z' && bi == ai+'a'-'A') {
return false
}
}
for i := la - 1; i >= 0; i-- {
ai := a[i]
bi := b[i]
if ai >= 'A' && ai <= 'Z' {
ai |= 'a' - 'A'
}
if bi >= 'A' && bi <= 'Z' {
bi |= 'a' - 'A'
}
if ai != bi {
return false
}
}
return true

110
labels_test.go
View File

@ -1,50 +1,55 @@
package dns
import (
"strings"
"testing"
)
import "testing"
func TestCompareDomainName(t *testing.T) {
tests := []struct {
s1, s2 string
expected int
}{
{"www.miek.nl.", "miek.nl.", 2},
{"miek.nl.", "www.bla.nl.", 1},
{"www.bla.nl.", "nl.www.bla.", 0},
{"www.miek.nl.", "nl.", 1},
{"www.miek.nl.", "miek.nl.", 2},
{"www.miek.nl.", ".", 0},
{".", ".", 0},
{"test.com.", "TEST.COM.", 2},
{"a.b.c.d.e.f.", "a.b.c.d.e.", 0},
{"a.b.c.d.e.", "a.b.c.d.e.", 5},
s1 := "www.miek.nl."
s2 := "miek.nl."
s3 := "www.bla.nl."
s4 := "nl.www.bla."
s5 := "nl."
s6 := "miek.nl."
if CompareDomainName(s1, s2) != 2 {
t.Errorf("%s with %s should be %d", s1, s2, 2)
}
for _, x := range tests {
if i := CompareDomainName(x.s1, x.s2); i != x.expected {
t.Errorf("%s with %s should be %d got: %d", x.s1, x.s2, x.expected, i)
}
if CompareDomainName(s1, s3) != 1 {
t.Errorf("%s with %s should be %d", s1, s3, 1)
}
if CompareDomainName(s3, s4) != 0 {
t.Errorf("%s with %s should be %d", s3, s4, 0)
}
// Non qualified tests
if CompareDomainName(s1, s5) != 1 {
t.Errorf("%s with %s should be %d", s1, s5, 1)
}
if CompareDomainName(s1, s6) != 2 {
t.Errorf("%s with %s should be %d", s1, s5, 2)
}
if CompareDomainName(s1, ".") != 0 {
t.Errorf("%s with %s should be %d", s1, s5, 0)
}
if CompareDomainName(".", ".") != 0 {
t.Errorf("%s with %s should be %d", ".", ".", 0)
}
if CompareDomainName("test.com.", "TEST.COM.") != 2 {
t.Errorf("test.com. and TEST.COM. should be an exact match")
}
}
func TestSplit(t *testing.T) {
splitter := map[string]int{
"www.miek.nl.": 3,
"www.miek.nl": 3,
"www..miek.nl": 4,
`www\.miek.nl.`: 2,
`www\\.miek.nl.`: 3,
`\\.miek.nl.`: 3,
`\\\.miek.nl.`: 2,
`\\\\.miek.nl.`: 3,
`www.miek\\\\.nl.`: 3,
`www.miek\\\.nl.`: 2,
".": 0,
"nl.": 1,
"nl": 1,
"com.": 1,
".com.": 2,
"www.miek.nl.": 3,
"www.miek.nl": 3,
"www..miek.nl": 4,
`www\.miek.nl.`: 2,
`www\\.miek.nl.`: 3,
".": 0,
"nl.": 1,
"nl": 1,
"com.": 1,
".com.": 2,
}
for s, i := range splitter {
if x := len(Split(s)); x != i {
@ -93,17 +98,7 @@ func TestPrevLabel(t *testing.T) {
{"www.miek.nl.", 3}: 0,
{"www.miek.nl", 3}: 0,
{"a.b.c.", 1}: 4,
{"a.b.c", 1}: 4,
}
// make sure we are safe when the label begins with a possibly escaped '.'
for i := 1; i < 8; i++ {
s := strings.Repeat(`\`, i) + "."
prever[prev{s, 0}] = i + 1
}
for s, i := range prever {
x, ok := PrevLabel(s.string, s.int)
if i != x {
@ -215,27 +210,6 @@ func TestIsFqdnEscaped(t *testing.T) {
}
}
func TestEqual(t *testing.T) {
type testcase struct {
a, b string
match bool
}
tests := []testcase{
{"a", "a", true},
{"a", "A", true},
{"A", "a", true},
{"A", "b", false},
{"www.example.com.", "www.exAmpLe.com.", true},
{"www.example.com.", "www.exAmpLe.org.", false},
}
for _, x := range tests {
eq := equal(x.a, x.b)
if eq != x.match {
t.Errorf("%+v: want: %t got: %t", x, x.match, eq)
}
}
}
func BenchmarkSplitLabels(b *testing.B) {
for i := 0; i < b.N; i++ {
Split("www.example.com.")