Documentation ¶
Overview ¶
Package base64 implements base64 encoding as specified by RFC 4648.
Copyright 2017 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 base64 implements base64 encoding as specified by RFC 4648.
Index ¶
- Constants
- Variables
- func EncodeFast(src []byte) []byte
- func EncodeToStream(src []byte, writer generic.Writer)
- func EncodeToString(src []byte) string
- func NewDecoder(enc *Encoding, r io.Reader) io.Reader
- func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser
- type CorruptInputError
- type Encoding
- func (enc *Encoding) Decode(dst, src []byte) (n int, err error)
- func (enc *Encoding) DecodeString(s string) ([]byte, error)
- func (enc *Encoding) DecodedLen(n int) int
- func (enc *Encoding) Encode(dst, src []byte)
- func (enc *Encoding) EncodeToString(src []byte) string
- func (enc *Encoding) EncodedLen(n int) int
- func (enc Encoding) Strict() *Encoding
- func (enc Encoding) WithPadding(padding rune) *Encoding
Constants ¶
const ( StdPadding rune = '=' // Standard padding character NoPadding rune = -1 // No padding )
Variables ¶
var RawStdEncoding = StdEncoding.WithPadding(NoPadding)
RawStdEncoding is the standard raw, unpadded base64 encoding, as defined in RFC 4648 section 3.2. This is the same as StdEncoding but omits padding characters.
var RawURLEncoding = URLEncoding.WithPadding(NoPadding)
RawURLEncoding is the unpadded alternate base64 encoding defined in RFC 4648. It is typically used in URLs and file names. This is the same as URLEncoding but omits padding characters.
var StdEncoding = NewEncoding(encodeStd)
StdEncoding is the standard base64 encoding, as defined in RFC 4648.
var URLEncoding = NewEncoding(encodeURL)
URLEncoding is the alternate base64 encoding defined in RFC 4648. It is typically used in URLs and file names.
Functions ¶
func EncodeFast ¶
func EncodeToStream ¶
func EncodeToString ¶
The Base64 encoding process is to: Divid the input bytes stream into blocks of 3 bytes. Divid 24 bits of each 3-byte block into 4 groups of 6 bits. Map each group of 6 bits to 1 printable character, based on the 6-bit value using the Base64 character set map. If the last 3-byte block has only 1 byte of input data, pad 2 bytes of zero (\x0000). After encoding it as a normal block, override the last 2 characters with 2 equal signs (==), so the decoding process knows 2 bytes of zero were padded. If the last 3-byte block has only 2 bytes of input data, pad 1 byte of zero (\x00). After encoding it as a normal block, override the last 1 character with 1 equal signs (=), so the decoding process knows 1 byte of zero was padded. Carriage return (\r) and new line (\n) are inserted into the output character stream. They will be ignored by the decoding process.
This solution requires following operations:
3 memory loads; 3 bit-ands; 2 bit-ors 5 bit-shifts.
func NewDecoder ¶
NewDecoder constructs a new base64 stream decoder.
func NewEncoder ¶
func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser
NewEncoder returns a new base64 stream encoder. Data written to the returned writer will be encoded using enc and then written to w. Base64 encodings operate in 4-byte blocks; when finished writing, the caller must Close the returned encoder to flush any partially written blocks.
Types ¶
type CorruptInputError ¶
type CorruptInputError int64
func (CorruptInputError) Error ¶
func (e CorruptInputError) Error() string
type Encoding ¶
type Encoding struct {
// contains filtered or unexported fields
}
An Encoding is a radix 64 encoding/decoding scheme, defined by a 64-character alphabet. The most common encoding is the "base64" encoding defined in RFC 4648 and used in MIME (RFC 2045) and PEM (RFC 1421). RFC 4648 also defines an alternate encoding, which is the standard encoding with - and _ substituted for + and /.
func NewEncoding ¶
NewEncoding returns a new padded Encoding defined by the given alphabet, which must be a 64-byte string that does not contain the padding character or CR / LF ('\r', '\n'). The resulting Encoding uses the default padding character ('='), which may be changed or disabled via WithPadding.
func (*Encoding) Decode ¶
Decode decodes src using the encoding enc. It writes at most DecodedLen(len(src)) bytes to dst and returns the number of bytes written. If src contains invalid base64 data, it will return the number of bytes successfully written and CorruptInputError. New line characters (\r and \n) are ignored.
func (*Encoding) DecodeString ¶
DecodeString returns the bytes represented by the base64 string s.
func (*Encoding) DecodedLen ¶
DecodedLen returns the maximum length in bytes of the decoded data corresponding to n bytes of base64-encoded data.
func (*Encoding) Encode ¶
Encode encodes src using the encoding enc, writing EncodedLen(len(src)) bytes to dst.
The encoding pads the output to a multiple of 4 bytes, so Encode is not appropriate for use on individual blocks of a large data stream. Use NewEncoder() instead.
func (*Encoding) EncodeToString ¶
EncodeToString returns the base64 encoding of src.
func (*Encoding) EncodedLen ¶
EncodedLen returns the length in bytes of the base64 encoding of an input buffer of length n.
func (Encoding) Strict ¶
Strict creates a new encoding identical to enc except with strict decoding enabled. In this mode, the decoder requires that trailing padding bits are zero, as described in RFC 4648 section 3.5.
func (Encoding) WithPadding ¶
WithPadding creates a new encoding identical to enc except with a specified padding character, or NoPadding to disable padding. The padding character must not be '\r' or '\n', must not be contained in the encoding's alphabet and must be a rune equal or below '\xff'.