Optimise sprintX functions in types.go (#757)
* Simplify appendByte * Add test case and benchmark for sprintName * Add test case and benchmark for sprintTxtOctet * Add test case and benchmark for sprintTxt * Use strings.Builder for sprint* functions in types.go * Use writeByte helper in unpackString * Rename writeByte to writeEscapedByte This better captures the purpose of this function.
This commit is contained in:
Tom Thorogood
GitHub
parent
36ffedf7d0
commit
0d29b283ac
4
msg.go
4
msg.go
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@ -531,6 +531,10 @@ func dddToByte(s []byte) byte {
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return byte((s[0]-'0')*100 + (s[1]-'0')*10 + (s[2] - '0'))
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}
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func dddStringToByte(s string) byte {
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return byte((s[0]-'0')*100 + (s[1]-'0')*10 + (s[2] - '0'))
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}
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// Helper function for packing and unpacking
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func intToBytes(i *big.Int, length int) []byte {
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buf := i.Bytes()
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@ -6,7 +6,6 @@ import (
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"encoding/binary"
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"encoding/hex"
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"net"
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"strconv"
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"strings"
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)
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@ -276,13 +275,7 @@ func unpackString(msg []byte, off int) (string, int, error) {
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s.WriteByte('\\')
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s.WriteByte(b)
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case b < ' ' || b > '~': // unprintable
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var buf [3]byte
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bufs := strconv.AppendInt(buf[:0], int64(b), 10)
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s.WriteByte('\\')
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for i := len(bufs); i < 3; i++ {
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s.WriteByte('0')
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}
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s.Write(bufs)
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writeEscapedByte(&s, b)
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default:
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s.WriteByte(b)
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}
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150
types.go
150
types.go
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@ -419,128 +419,130 @@ type TXT struct {
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func (rr *TXT) String() string { return rr.Hdr.String() + sprintTxt(rr.Txt) }
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func sprintName(s string) string {
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src := []byte(s)
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dst := make([]byte, 0, len(src))
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for i := 0; i < len(src); {
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if i+1 < len(src) && src[i] == '\\' && src[i+1] == '.' {
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dst = append(dst, src[i:i+2]...)
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var dst strings.Builder
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dst.Grow(len(s))
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for i := 0; i < len(s); {
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if i+1 < len(s) && s[i] == '\\' && s[i+1] == '.' {
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dst.WriteString(s[i : i+2])
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i += 2
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} else {
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b, n := nextByte(src, i)
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if n == 0 {
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i++ // dangling back slash
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} else if b == '.' {
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dst = append(dst, b)
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} else {
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dst = appendDomainNameByte(dst, b)
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}
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i += n
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continue
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}
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b, n := nextByte(s, i)
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switch {
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case n == 0:
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i++ // dangling back slash
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case b == '.':
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dst.WriteByte('.')
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default:
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writeDomainNameByte(&dst, b)
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}
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i += n
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}
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return string(dst)
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return dst.String()
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}
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func sprintTxtOctet(s string) string {
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src := []byte(s)
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dst := make([]byte, 0, len(src))
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dst = append(dst, '"')
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for i := 0; i < len(src); {
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if i+1 < len(src) && src[i] == '\\' && src[i+1] == '.' {
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dst = append(dst, src[i:i+2]...)
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var dst strings.Builder
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dst.Grow(2 + len(s))
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dst.WriteByte('"')
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for i := 0; i < len(s); {
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if i+1 < len(s) && s[i] == '\\' && s[i+1] == '.' {
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dst.WriteString(s[i : i+2])
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i += 2
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} else {
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b, n := nextByte(src, i)
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if n == 0 {
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i++ // dangling back slash
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} else if b == '.' {
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dst = append(dst, b)
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} else {
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if b < ' ' || b > '~' {
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dst = appendByte(dst, b)
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} else {
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dst = append(dst, b)
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}
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}
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i += n
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continue
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}
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b, n := nextByte(s, i)
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switch {
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case n == 0:
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i++ // dangling back slash
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case b == '.':
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dst.WriteByte('.')
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case b < ' ' || b > '~':
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writeEscapedByte(&dst, b)
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default:
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dst.WriteByte(b)
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}
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i += n
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}
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dst = append(dst, '"')
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return string(dst)
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dst.WriteByte('"')
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return dst.String()
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}
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func sprintTxt(txt []string) string {
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var out []byte
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var out strings.Builder
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for i, s := range txt {
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out.Grow(3 + len(s))
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if i > 0 {
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out = append(out, ` "`...)
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out.WriteString(` "`)
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} else {
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out = append(out, '"')
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out.WriteByte('"')
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}
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bs := []byte(s)
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for j := 0; j < len(bs); {
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b, n := nextByte(bs, j)
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for j := 0; j < len(s); {
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b, n := nextByte(s, j)
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if n == 0 {
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break
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}
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out = appendTXTStringByte(out, b)
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writeTXTStringByte(&out, b)
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j += n
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}
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out = append(out, '"')
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out.WriteByte('"')
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}
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return string(out)
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return out.String()
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}
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func appendDomainNameByte(s []byte, b byte) []byte {
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func writeDomainNameByte(s *strings.Builder, b byte) {
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switch b {
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case '.', ' ', '\'', '@', ';', '(', ')': // additional chars to escape
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return append(s, '\\', b)
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s.WriteByte('\\')
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s.WriteByte(b)
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default:
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writeTXTStringByte(s, b)
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}
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return appendTXTStringByte(s, b)
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}
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func appendTXTStringByte(s []byte, b byte) []byte {
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switch b {
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case '"', '\\':
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return append(s, '\\', b)
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func writeTXTStringByte(s *strings.Builder, b byte) {
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switch {
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case b == '"' || b == '\\':
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s.WriteByte('\\')
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s.WriteByte(b)
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case b < ' ' || b > '~':
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writeEscapedByte(s, b)
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default:
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s.WriteByte(b)
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}
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if b < ' ' || b > '~' {
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return appendByte(s, b)
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}
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return append(s, b)
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}
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func appendByte(s []byte, b byte) []byte {
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func writeEscapedByte(s *strings.Builder, b byte) {
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var buf [3]byte
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bufs := strconv.AppendInt(buf[:0], int64(b), 10)
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s = append(s, '\\')
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for i := 0; i < 3-len(bufs); i++ {
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s = append(s, '0')
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s.WriteByte('\\')
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for i := len(bufs); i < 3; i++ {
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s.WriteByte('0')
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}
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for _, r := range bufs {
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s = append(s, r)
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}
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return s
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s.Write(bufs)
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}
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func nextByte(b []byte, offset int) (byte, int) {
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if offset >= len(b) {
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func nextByte(s string, offset int) (byte, int) {
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if offset >= len(s) {
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return 0, 0
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}
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if b[offset] != '\\' {
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if s[offset] != '\\' {
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// not an escape sequence
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return b[offset], 1
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return s[offset], 1
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}
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switch len(b) - offset {
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switch len(s) - offset {
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case 1: // dangling escape
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return 0, 0
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case 2, 3: // too short to be \ddd
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default: // maybe \ddd
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if isDigit(b[offset+1]) && isDigit(b[offset+2]) && isDigit(b[offset+3]) {
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return dddToByte(b[offset+1:]), 4
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if isDigit(s[offset+1]) && isDigit(s[offset+2]) && isDigit(s[offset+3]) {
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return dddStringToByte(s[offset+1:]), 4
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}
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}
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// not \ddd, just an RFC 1035 "quoted" character
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return b[offset+1], 2
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return s[offset+1], 2
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}
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// SPF RR. See RFC 4408, Section 3.1.1.
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@ -72,3 +72,65 @@ func TestSplitN(t *testing.T) {
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t.Errorf("failure to split 510 char long string: %d", len(xs))
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}
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}
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func TestSprintName(t *testing.T) {
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got := sprintName("abc\\.def\007\"\127@\255\x05\xef\\")
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if want := "abc\\.def\\007\\\"W\\@\\173\\005\\239"; got != want {
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t.Errorf("expected %q, got %q", got, want)
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}
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}
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func TestSprintTxtOctet(t *testing.T) {
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got := sprintTxtOctet("abc\\.def\007\"\127@\255\x05\xef\\")
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if want := "\"abc\\.def\\007\"W@\\173\\005\\239\""; got != want {
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t.Errorf("expected %q, got %q", got, want)
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}
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}
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func TestSprintTxt(t *testing.T) {
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got := sprintTxt([]string{
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"abc\\.def\007\"\127@\255\x05\xef\\",
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"example.com",
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})
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if want := "\"abc.def\\007\\\"W@\\173\\005\\239\" \"example.com\""; got != want {
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t.Errorf("expected %q, got %q", got, want)
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}
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}
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func BenchmarkSprintName(b *testing.B) {
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for n := 0; n < b.N; n++ {
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got := sprintName("abc\\.def\007\"\127@\255\x05\xef\\")
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if want := "abc\\.def\\007\\\"W\\@\\173\\005\\239"; got != want {
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b.Fatalf("expected %q, got %q", got, want)
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}
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}
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}
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func BenchmarkSprintTxtOctet(b *testing.B) {
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for n := 0; n < b.N; n++ {
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got := sprintTxtOctet("abc\\.def\007\"\127@\255\x05\xef\\")
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if want := "\"abc\\.def\\007\"W@\\173\\005\\239\""; got != want {
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b.Fatalf("expected %q, got %q", got, want)
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}
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}
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}
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func BenchmarkSprintTxt(b *testing.B) {
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txt := []string{
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"abc\\.def\007\"\127@\255\x05\xef\\",
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"example.com",
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}
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for n := 0; n < b.N; n++ {
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got := sprintTxt(txt)
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if want := "\"abc.def\\007\\\"W@\\173\\005\\239\" \"example.com\""; got != want {
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b.Fatalf("expected %q, got %q", got, want)
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}
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}
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}
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