forked from golang/hotime
51 lines
1.5 KiB
Go
51 lines
1.5 KiB
Go
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// Copyright 2015 The Go 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 pkcs12
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import (
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"errors"
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"unicode/utf16"
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)
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// bmpString returns s encoded in UCS-2 with a zero terminator.
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func bmpString(s string) ([]byte, error) {
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// References:
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// https://tools.ietf.org/html/rfc7292#appendix-B.1
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// https://en.wikipedia.org/wiki/Plane_(Unicode)#Basic_Multilingual_Plane
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// - non-BMP characters are encoded in UTF 16 by using a surrogate pair of 16-bit codes
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// EncodeRune returns 0xfffd if the rune does not need special encoding
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// - the above RFC provides the info that BMPStrings are NULL terminated.
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ret := make([]byte, 0, 2*len(s)+2)
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for _, r := range s {
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if t, _ := utf16.EncodeRune(r); t != 0xfffd {
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return nil, errors.New("pkcs12: string contains characters that cannot be encoded in UCS-2")
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}
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ret = append(ret, byte(r/256), byte(r%256))
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}
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return append(ret, 0, 0), nil
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}
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func decodeBMPString(bmpString []byte) (string, error) {
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if len(bmpString)%2 != 0 {
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return "", errors.New("pkcs12: odd-length BMP string")
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}
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// strip terminator if present
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if l := len(bmpString); l >= 2 && bmpString[l-1] == 0 && bmpString[l-2] == 0 {
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bmpString = bmpString[:l-2]
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}
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s := make([]uint16, 0, len(bmpString)/2)
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for len(bmpString) > 0 {
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s = append(s, uint16(bmpString[0])<<8+uint16(bmpString[1]))
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bmpString = bmpString[2:]
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}
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return string(utf16.Decode(s)), nil
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}
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