68 lines
2.3 KiB
Go
68 lines
2.3 KiB
Go
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package base64
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import (
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"encoding/base64"
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)
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const (
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StdPadding rune = base64.StdPadding
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NoPadding rune = base64.NoPadding
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encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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encodeURL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
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encodeIMAP = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"
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letterRange = int8('Z' - 'A' + 1)
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)
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// StdEncoding is the standard base64 encoding, as defined in RFC 4648.
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var StdEncoding = NewEncoding(encodeStd)
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// URLEncoding is the alternate base64 encoding defined in RFC 4648.
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// It is typically used in URLs and file names.
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var URLEncoding = NewEncoding(encodeURL)
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// RawStdEncoding is the standard unpadded base64 encoding defined in RFC 4648 section 3.2.
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// This is the same as StdEncoding but omits padding characters.
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var RawStdEncoding = StdEncoding.WithPadding(NoPadding)
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// RawURLEncoding is the unpadded alternate base64 encoding defined in RFC 4648.
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// This is the same as URLEncoding but omits padding characters.
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var RawURLEncoding = URLEncoding.WithPadding(NoPadding)
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// NewEncoding returns a new padded Encoding defined by the given alphabet,
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// which must be a 64-byte string that does not contain the padding character
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// or CR / LF ('\r', '\n'). Unlike the standard library, the encoding alphabet
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// cannot be abitrary, and it must follow one of the know standard encoding
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// variants.
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//
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// Required alphabet values:
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// * [0,26): characters 'A'..'Z'
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// * [26,52): characters 'a'..'z'
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// * [52,62): characters '0'..'9'
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// Flexible alphabet value options:
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// * RFC 4648, RFC 1421, RFC 2045, RFC 2152, RFC 4880: '+' and '/'
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// * RFC 4648 URI: '-' and '_'
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// * RFC 3501: '+' and ','
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//
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// The resulting Encoding uses the default padding character ('='), which may
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// be changed or disabled via WithPadding. The padding characters is urestricted,
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// but it must be a character outside of the encoder alphabet.
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func NewEncoding(encoder string) *Encoding {
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if len(encoder) != 64 {
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panic("encoding alphabet is not 64-bytes long")
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}
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if _, ok := allowedEncoding[encoder]; !ok {
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panic("non-standard encoding alphabets are not supported")
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}
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return newEncoding(encoder)
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}
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var allowedEncoding = map[string]struct{}{
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encodeStd: {},
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encodeURL: {},
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encodeIMAP: {},
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}
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