54 lines
1.4 KiB
Go
54 lines
1.4 KiB
Go
// Copyright 2015 The Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package mdurl
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import (
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"bytes"
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"strings"
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"unicode/utf8"
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)
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// Encode percent-encodes rawurl, avoiding double encoding.
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// It doesn't touch:
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// - alphanumeric characters ([0-9a-zA-Z]);
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// - percent-encoded characters (%[0-9a-fA-F]{2});
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// - excluded characters ([;/?:@&=+$,-_.!~*'()#]).
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// Invalid UTF-8 sequences are replaced with U+FFFD.
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func Encode(rawurl string) string {
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const hexdigit = "0123456789ABCDEF"
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var buf bytes.Buffer
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i := 0
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for i < len(rawurl) {
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r, rlen := utf8.DecodeRuneInString(rawurl[i:])
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if r >= 0x80 {
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for j, n := i, i+rlen; j < n; j++ {
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b := rawurl[j]
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buf.WriteByte('%')
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buf.WriteByte(hexdigit[(b>>4)&0xf])
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buf.WriteByte(hexdigit[b&0xf])
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}
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} else if r == '%' {
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if i+2 < len(rawurl) &&
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hexDigit(rawurl[i+1]) &&
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hexDigit(rawurl[i+2]) {
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buf.WriteByte('%')
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buf.WriteByte(byteToUpper(rawurl[i+1]))
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buf.WriteByte(byteToUpper(rawurl[i+2]))
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i += 2
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} else {
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buf.WriteString("%25")
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}
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} else if strings.IndexByte("!#$&'()*+,-./0123456789:;=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz~", byte(r)) == -1 {
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buf.WriteByte('%')
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buf.WriteByte(hexdigit[(r>>4)&0xf])
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buf.WriteByte(hexdigit[r&0xf])
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} else {
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buf.WriteByte(byte(r))
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}
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i += rlen
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}
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return buf.String()
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}
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