+++ /dev/null
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package idna
-
-// This file implements the Punycode algorithm from RFC 3492.
-
-import (
- "math"
- "strings"
- "unicode/utf8"
-)
-
-// These parameter values are specified in section 5.
-//
-// All computation is done with int32s, so that overflow behavior is identical
-// regardless of whether int is 32-bit or 64-bit.
-const (
- base int32 = 36
- damp int32 = 700
- initialBias int32 = 72
- initialN int32 = 128
- skew int32 = 38
- tmax int32 = 26
- tmin int32 = 1
-)
-
-func punyError(s string) error { return &labelError{s, "A3"} }
-
-// decode decodes a string as specified in section 6.2.
-func decode(encoded string) (string, error) {
- if encoded == "" {
- return "", nil
- }
- pos := 1 + strings.LastIndex(encoded, "-")
- if pos == 1 {
- return "", punyError(encoded)
- }
- if pos == len(encoded) {
- return encoded[:len(encoded)-1], nil
- }
- output := make([]rune, 0, len(encoded))
- if pos != 0 {
- for _, r := range encoded[:pos-1] {
- output = append(output, r)
- }
- }
- i, n, bias := int32(0), initialN, initialBias
- for pos < len(encoded) {
- oldI, w := i, int32(1)
- for k := base; ; k += base {
- if pos == len(encoded) {
- return "", punyError(encoded)
- }
- digit, ok := decodeDigit(encoded[pos])
- if !ok {
- return "", punyError(encoded)
- }
- pos++
- i += digit * w
- if i < 0 {
- return "", punyError(encoded)
- }
- t := k - bias
- if t < tmin {
- t = tmin
- } else if t > tmax {
- t = tmax
- }
- if digit < t {
- break
- }
- w *= base - t
- if w >= math.MaxInt32/base {
- return "", punyError(encoded)
- }
- }
- x := int32(len(output) + 1)
- bias = adapt(i-oldI, x, oldI == 0)
- n += i / x
- i %= x
- if n > utf8.MaxRune || len(output) >= 1024 {
- return "", punyError(encoded)
- }
- output = append(output, 0)
- copy(output[i+1:], output[i:])
- output[i] = n
- i++
- }
- return string(output), nil
-}
-
-// encode encodes a string as specified in section 6.3 and prepends prefix to
-// the result.
-//
-// The "while h < length(input)" line in the specification becomes "for
-// remaining != 0" in the Go code, because len(s) in Go is in bytes, not runes.
-func encode(prefix, s string) (string, error) {
- output := make([]byte, len(prefix), len(prefix)+1+2*len(s))
- copy(output, prefix)
- delta, n, bias := int32(0), initialN, initialBias
- b, remaining := int32(0), int32(0)
- for _, r := range s {
- if r < 0x80 {
- b++
- output = append(output, byte(r))
- } else {
- remaining++
- }
- }
- h := b
- if b > 0 {
- output = append(output, '-')
- }
- for remaining != 0 {
- m := int32(0x7fffffff)
- for _, r := range s {
- if m > r && r >= n {
- m = r
- }
- }
- delta += (m - n) * (h + 1)
- if delta < 0 {
- return "", punyError(s)
- }
- n = m
- for _, r := range s {
- if r < n {
- delta++
- if delta < 0 {
- return "", punyError(s)
- }
- continue
- }
- if r > n {
- continue
- }
- q := delta
- for k := base; ; k += base {
- t := k - bias
- if t < tmin {
- t = tmin
- } else if t > tmax {
- t = tmax
- }
- if q < t {
- break
- }
- output = append(output, encodeDigit(t+(q-t)%(base-t)))
- q = (q - t) / (base - t)
- }
- output = append(output, encodeDigit(q))
- bias = adapt(delta, h+1, h == b)
- delta = 0
- h++
- remaining--
- }
- delta++
- n++
- }
- return string(output), nil
-}
-
-func decodeDigit(x byte) (digit int32, ok bool) {
- switch {
- case '0' <= x && x <= '9':
- return int32(x - ('0' - 26)), true
- case 'A' <= x && x <= 'Z':
- return int32(x - 'A'), true
- case 'a' <= x && x <= 'z':
- return int32(x - 'a'), true
- }
- return 0, false
-}
-
-func encodeDigit(digit int32) byte {
- switch {
- case 0 <= digit && digit < 26:
- return byte(digit + 'a')
- case 26 <= digit && digit < 36:
- return byte(digit + ('0' - 26))
- }
- panic("idna: internal error in punycode encoding")
-}
-
-// adapt is the bias adaptation function specified in section 6.1.
-func adapt(delta, numPoints int32, firstTime bool) int32 {
- if firstTime {
- delta /= damp
- } else {
- delta /= 2
- }
- delta += delta / numPoints
- k := int32(0)
- for delta > ((base-tmin)*tmax)/2 {
- delta /= base - tmin
- k += base
- }
- return k + (base-tmin+1)*delta/(delta+skew)
-}
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