+++ /dev/null
-// Package base32 implements base32 encoding as specified by RFC 4648.
-package base32
-
-import (
- "bytes"
- "io"
- "strconv"
- "strings"
-)
-
-/*
- * Encodings
- */
-
-// An Encoding is a radix 32 encoding/decoding scheme, defined by a
-// 32-character alphabet. The most common is the "base32" encoding
-// introduced for SASL GSSAPI and standardized in RFC 4648.
-// The alternate "base32hex" encoding is used in DNSSEC.
-type Encoding struct {
- encode string
- decodeMap [256]byte
- padChar rune
-}
-
-const (
- StdPadding rune = '=' // Standard padding character
- NoPadding rune = -1 // No padding
-)
-
-const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
-const encodeHex = "0123456789ABCDEFGHIJKLMNOPQRSTUV"
-
-// NewEncoding returns a new Encoding defined by the given alphabet,
-// which must be a 32-byte string.
-func NewEncoding(encoder string) *Encoding {
- e := new(Encoding)
- e.encode = encoder
- e.padChar = StdPadding
-
- for i := 0; i < len(e.decodeMap); i++ {
- e.decodeMap[i] = 0xFF
- }
- for i := 0; i < len(encoder); i++ {
- e.decodeMap[encoder[i]] = byte(i)
- }
- return e
-}
-
-// StdEncoding is the standard base32 encoding, as defined in
-// RFC 4648.
-var StdEncoding = NewEncoding(encodeStd)
-
-// HexEncoding is the ``Extended Hex Alphabet'' defined in RFC 4648.
-// It is typically used in DNS.
-var HexEncoding = NewEncoding(encodeHex)
-
-var removeNewlinesMapper = func(r rune) rune {
- if r == '\r' || r == '\n' {
- return -1
- }
- return r
-}
-
-// 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'.
-func (enc Encoding) WithPadding(padding rune) *Encoding {
- if padding == '\r' || padding == '\n' || padding > 0xff {
- panic("invalid padding")
- }
-
- for i := 0; i < len(enc.encode); i++ {
- if rune(enc.encode[i]) == padding {
- panic("padding contained in alphabet")
- }
- }
-
- enc.padChar = padding
- return &enc
-}
-
-/*
- * Encoder
- */
-
-// Encode encodes src using the encoding enc, writing
-// EncodedLen(len(src)) bytes to dst.
-//
-// The encoding pads the output to a multiple of 8 bytes,
-// so Encode is not appropriate for use on individual blocks
-// of a large data stream. Use NewEncoder() instead.
-func (enc *Encoding) Encode(dst, src []byte) {
- if len(src) == 0 {
- return
- }
-
- for len(src) > 0 {
- var b [8]byte
-
- // Unpack 8x 5-bit source blocks into a 5 byte
- // destination quantum
- switch len(src) {
- default:
- b[7] = src[4] & 0x1F
- b[6] = src[4] >> 5
- fallthrough
- case 4:
- b[6] |= (src[3] << 3) & 0x1F
- b[5] = (src[3] >> 2) & 0x1F
- b[4] = src[3] >> 7
- fallthrough
- case 3:
- b[4] |= (src[2] << 1) & 0x1F
- b[3] = (src[2] >> 4) & 0x1F
- fallthrough
- case 2:
- b[3] |= (src[1] << 4) & 0x1F
- b[2] = (src[1] >> 1) & 0x1F
- b[1] = (src[1] >> 6) & 0x1F
- fallthrough
- case 1:
- b[1] |= (src[0] << 2) & 0x1F
- b[0] = src[0] >> 3
- }
-
- // Encode 5-bit blocks using the base32 alphabet
- size := len(dst)
- if size >= 8 {
- // Common case, unrolled for extra performance
- dst[0] = enc.encode[b[0]]
- dst[1] = enc.encode[b[1]]
- dst[2] = enc.encode[b[2]]
- dst[3] = enc.encode[b[3]]
- dst[4] = enc.encode[b[4]]
- dst[5] = enc.encode[b[5]]
- dst[6] = enc.encode[b[6]]
- dst[7] = enc.encode[b[7]]
- } else {
- for i := 0; i < size; i++ {
- dst[i] = enc.encode[b[i]]
- }
- }
-
- // Pad the final quantum
- if len(src) < 5 {
- if enc.padChar == NoPadding {
- break
- }
-
- dst[7] = byte(enc.padChar)
- if len(src) < 4 {
- dst[6] = byte(enc.padChar)
- dst[5] = byte(enc.padChar)
- if len(src) < 3 {
- dst[4] = byte(enc.padChar)
- if len(src) < 2 {
- dst[3] = byte(enc.padChar)
- dst[2] = byte(enc.padChar)
- }
- }
- }
-
- break
- }
-
- src = src[5:]
- dst = dst[8:]
- }
-}
-
-// EncodeToString returns the base32 encoding of src.
-func (enc *Encoding) EncodeToString(src []byte) string {
- buf := make([]byte, enc.EncodedLen(len(src)))
- enc.Encode(buf, src)
- return string(buf)
-}
-
-type encoder struct {
- err error
- enc *Encoding
- w io.Writer
- buf [5]byte // buffered data waiting to be encoded
- nbuf int // number of bytes in buf
- out [1024]byte // output buffer
-}
-
-func (e *encoder) Write(p []byte) (n int, err error) {
- if e.err != nil {
- return 0, e.err
- }
-
- // Leading fringe.
- if e.nbuf > 0 {
- var i int
- for i = 0; i < len(p) && e.nbuf < 5; i++ {
- e.buf[e.nbuf] = p[i]
- e.nbuf++
- }
- n += i
- p = p[i:]
- if e.nbuf < 5 {
- return
- }
- e.enc.Encode(e.out[0:], e.buf[0:])
- if _, e.err = e.w.Write(e.out[0:8]); e.err != nil {
- return n, e.err
- }
- e.nbuf = 0
- }
-
- // Large interior chunks.
- for len(p) >= 5 {
- nn := len(e.out) / 8 * 5
- if nn > len(p) {
- nn = len(p)
- nn -= nn % 5
- }
- e.enc.Encode(e.out[0:], p[0:nn])
- if _, e.err = e.w.Write(e.out[0 : nn/5*8]); e.err != nil {
- return n, e.err
- }
- n += nn
- p = p[nn:]
- }
-
- // Trailing fringe.
- for i := 0; i < len(p); i++ {
- e.buf[i] = p[i]
- }
- e.nbuf = len(p)
- n += len(p)
- return
-}
-
-// Close flushes any pending output from the encoder.
-// It is an error to call Write after calling Close.
-func (e *encoder) Close() error {
- // If there's anything left in the buffer, flush it out
- if e.err == nil && e.nbuf > 0 {
- e.enc.Encode(e.out[0:], e.buf[0:e.nbuf])
- e.nbuf = 0
- _, e.err = e.w.Write(e.out[0:8])
- }
- return e.err
-}
-
-// NewEncoder returns a new base32 stream encoder. Data written to
-// the returned writer will be encoded using enc and then written to w.
-// Base32 encodings operate in 5-byte blocks; when finished
-// writing, the caller must Close the returned encoder to flush any
-// partially written blocks.
-func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {
- return &encoder{enc: enc, w: w}
-}
-
-// EncodedLen returns the length in bytes of the base32 encoding
-// of an input buffer of length n.
-func (enc *Encoding) EncodedLen(n int) int {
- if enc.padChar == NoPadding {
- return (n*8 + 4) / 5
- }
- return (n + 4) / 5 * 8
-}
-
-/*
- * Decoder
- */
-
-type CorruptInputError int64
-
-func (e CorruptInputError) Error() string {
- return "illegal base32 data at input byte " + strconv.FormatInt(int64(e), 10)
-}
-
-// decode is like Decode but returns an additional 'end' value, which
-// indicates if end-of-message padding was encountered and thus any
-// additional data is an error. This method assumes that src has been
-// stripped of all supported whitespace ('\r' and '\n').
-func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
- olen := len(src)
- for len(src) > 0 && !end {
- // Decode quantum using the base32 alphabet
- var dbuf [8]byte
- dlen := 8
-
- for j := 0; j < 8; {
-
- // We have reached the end and are missing padding
- if len(src) == 0 && enc.padChar != NoPadding {
- return n, false, CorruptInputError(olen - len(src) - j)
- }
-
- // We have reached the end and are not expecing any padding
- if len(src) == 0 && enc.padChar == NoPadding {
- dlen, end = j, true
- break
- }
-
- in := src[0]
- src = src[1:]
- if in == byte(enc.padChar) && j >= 2 && len(src) < 8 {
- // We've reached the end and there's padding
- if len(src)+j < 8-1 {
- // not enough padding
- return n, false, CorruptInputError(olen)
- }
- for k := 0; k < 8-1-j; k++ {
- if len(src) > k && src[k] != byte(enc.padChar) {
- // incorrect padding
- return n, false, CorruptInputError(olen - len(src) + k - 1)
- }
- }
- dlen, end = j, true
- // 7, 5 and 2 are not valid padding lengths, and so 1, 3 and 6 are not
- // valid dlen values. See RFC 4648 Section 6 "Base 32 Encoding" listing
- // the five valid padding lengths, and Section 9 "Illustrations and
- // Examples" for an illustration for how the 1st, 3rd and 6th base32
- // src bytes do not yield enough information to decode a dst byte.
- if dlen == 1 || dlen == 3 || dlen == 6 {
- return n, false, CorruptInputError(olen - len(src) - 1)
- }
- break
- }
- dbuf[j] = enc.decodeMap[in]
- if dbuf[j] == 0xFF {
- return n, false, CorruptInputError(olen - len(src) - 1)
- }
- j++
- }
-
- // Pack 8x 5-bit source blocks into 5 byte destination
- // quantum
- switch dlen {
- case 8:
- dst[4] = dbuf[6]<<5 | dbuf[7]
- fallthrough
- case 7:
- dst[3] = dbuf[4]<<7 | dbuf[5]<<2 | dbuf[6]>>3
- fallthrough
- case 5:
- dst[2] = dbuf[3]<<4 | dbuf[4]>>1
- fallthrough
- case 4:
- dst[1] = dbuf[1]<<6 | dbuf[2]<<1 | dbuf[3]>>4
- fallthrough
- case 2:
- dst[0] = dbuf[0]<<3 | dbuf[1]>>2
- }
-
- if !end {
- dst = dst[5:]
- }
-
- switch dlen {
- case 2:
- n += 1
- case 4:
- n += 2
- case 5:
- n += 3
- case 7:
- n += 4
- case 8:
- n += 5
- }
- }
- return n, end, nil
-}
-
-// 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 base32 data, it will return the
-// number of bytes successfully written and CorruptInputError.
-// New line characters (\r and \n) are ignored.
-func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
- src = bytes.Map(removeNewlinesMapper, src)
- n, _, err = enc.decode(dst, src)
- return
-}
-
-// DecodeString returns the bytes represented by the base32 string s.
-func (enc *Encoding) DecodeString(s string) ([]byte, error) {
- s = strings.Map(removeNewlinesMapper, s)
- dbuf := make([]byte, enc.DecodedLen(len(s)))
- n, _, err := enc.decode(dbuf, []byte(s))
- return dbuf[:n], err
-}
-
-type decoder struct {
- err error
- enc *Encoding
- r io.Reader
- end bool // saw end of message
- buf [1024]byte // leftover input
- nbuf int
- out []byte // leftover decoded output
- outbuf [1024 / 8 * 5]byte
-}
-
-func readEncodedData(r io.Reader, buf []byte, min int) (n int, err error) {
- for n < min && err == nil {
- var nn int
- nn, err = r.Read(buf[n:])
- n += nn
- }
- if n < min && n > 0 && err == io.EOF {
- err = io.ErrUnexpectedEOF
- }
- return
-}
-
-func (d *decoder) Read(p []byte) (n int, err error) {
- // Use leftover decoded output from last read.
- if len(d.out) > 0 {
- n = copy(p, d.out)
- d.out = d.out[n:]
- if len(d.out) == 0 {
- return n, d.err
- }
- return n, nil
- }
-
- if d.err != nil {
- return 0, d.err
- }
-
- // Read a chunk.
- nn := len(p) / 5 * 8
- if nn < 8 {
- nn = 8
- }
- if nn > len(d.buf) {
- nn = len(d.buf)
- }
-
- nn, d.err = readEncodedData(d.r, d.buf[d.nbuf:nn], 8-d.nbuf)
- d.nbuf += nn
- if d.nbuf < 8 {
- return 0, d.err
- }
-
- // Decode chunk into p, or d.out and then p if p is too small.
- nr := d.nbuf / 8 * 8
- nw := d.nbuf / 8 * 5
- if nw > len(p) {
- nw, d.end, err = d.enc.decode(d.outbuf[0:], d.buf[0:nr])
- d.out = d.outbuf[0:nw]
- n = copy(p, d.out)
- d.out = d.out[n:]
- } else {
- n, d.end, err = d.enc.decode(p, d.buf[0:nr])
- }
- d.nbuf -= nr
- for i := 0; i < d.nbuf; i++ {
- d.buf[i] = d.buf[i+nr]
- }
-
- if err != nil && (d.err == nil || d.err == io.EOF) {
- d.err = err
- }
-
- if len(d.out) > 0 {
- // We cannot return all the decoded bytes to the caller in this
- // invocation of Read, so we return a nil error to ensure that Read
- // will be called again. The error stored in d.err, if any, will be
- // returned with the last set of decoded bytes.
- return n, nil
- }
-
- return n, d.err
-}
-
-type newlineFilteringReader struct {
- wrapped io.Reader
-}
-
-func (r *newlineFilteringReader) Read(p []byte) (int, error) {
- n, err := r.wrapped.Read(p)
- for n > 0 {
- offset := 0
- for i, b := range p[0:n] {
- if b != '\r' && b != '\n' {
- if i != offset {
- p[offset] = b
- }
- offset++
- }
- }
- if err != nil || offset > 0 {
- return offset, err
- }
- // Previous buffer entirely whitespace, read again
- n, err = r.wrapped.Read(p)
- }
- return n, err
-}
-
-// NewDecoder constructs a new base32 stream decoder.
-func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
- return &decoder{enc: enc, r: &newlineFilteringReader{r}}
-}
-
-// DecodedLen returns the maximum length in bytes of the decoded data
-// corresponding to n bytes of base32-encoded data.
-func (enc *Encoding) DecodedLen(n int) int {
- if enc.padChar == NoPadding {
- return n * 5 / 8
- }
-
- return n / 8 * 5
-}
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