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67 lines
2.3 KiB
67 lines
2.3 KiB
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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