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mirror of https://github.com/golang/go synced 2024-11-25 03:07:56 -07:00

encoding/base32: new package

R=rsc
CC=Miek Gieben, golang-dev
https://golang.org/cl/3926041
This commit is contained in:
Miek Gieben 2011-01-20 12:51:15 -05:00 committed by Russ Cox
parent 007aaa474e
commit 40c7449044
4 changed files with 574 additions and 0 deletions

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@ -58,6 +58,7 @@ DIRS=\
debug/proc\
ebnf\
encoding/ascii85\
encoding/base32\
encoding/base64\
encoding/binary\
encoding/git85\

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@ -0,0 +1,11 @@
# Copyright 2009 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.
include $(GOROOT)/src/Make.inc
TARG=encoding/base32
GOFILES=\
base32.go\
include $(GOROOT)/src/Make.pkg

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@ -0,0 +1,368 @@
// Copyright 2011 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 base32 implements base32 encoding as specified by RFC 4648.
package base32
import (
"io"
"os"
"strconv"
)
/*
* 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
}
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
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)
/*
* 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 {
dst[0] = 0
dst[1] = 0
dst[2] = 0
dst[3] = 0
dst[4] = 0
dst[5] = 0
dst[6] = 0
dst[7] = 0
// Unpack 8x 5-bit source blocks into a 5 byte
// destination quantum
switch len(src) {
default:
dst[7] |= src[4] & 0x1F
dst[6] |= src[4] >> 5
fallthrough
case 4:
dst[6] |= (src[3] << 3) & 0x1F
dst[5] |= (src[3] >> 2) & 0x1F
dst[4] |= src[3] >> 7
fallthrough
case 3:
dst[4] |= (src[2] << 1) & 0x1F
dst[3] |= (src[2] >> 4) & 0x1F
fallthrough
case 2:
dst[3] |= (src[1] << 4) & 0x1F
dst[2] |= (src[1] >> 1) & 0x1F
dst[1] |= (src[1] >> 6) & 0x1F
fallthrough
case 1:
dst[1] |= (src[0] << 2) & 0x1F
dst[0] |= src[0] >> 3
}
// Encode 5-bit blocks using the base32 alphabet
for j := 0; j < 8; j++ {
dst[j] = enc.encode[dst[j]]
}
// Pad the final quantum
if len(src) < 5 {
dst[7] = '='
if len(src) < 4 {
dst[6] = '='
dst[5] = '='
if len(src) < 3 {
dst[4] = '='
if len(src) < 2 {
dst[3] = '='
dst[2] = '='
}
}
}
break
}
src = src[5:]
dst = dst[8:]
}
}
type encoder struct {
err os.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 os.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
if nn > 0 {
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() os.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 { return (n + 4) / 5 * 8 }
/*
* Decoder
*/
type CorruptInputError int64
func (e CorruptInputError) String() string {
return "illegal base32 data at input byte " + strconv.Itoa64(int64(e))
}
// 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. decode also assumes len(src)%8==0,
// since it is meant for internal use.
func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err os.Error) {
for i := 0; i < len(src)/8 && !end; i++ {
// Decode quantum using the base32 alphabet
var dbuf [8]byte
dlen := 8
// do the top bytes contain any data?
dbufloop:
for j := 0; j < 8; j++ {
in := src[i*8+j]
if in == '=' && j >= 2 && i == len(src)/8-1 {
// We've reached the end and there's
// padding, the rest should be padded
for k := j; k < 8; k++ {
if src[i*8+k] != '=' {
return n, false, CorruptInputError(i*8 + j)
}
}
dlen = j
end = true
break dbufloop
}
dbuf[j] = enc.decodeMap[in]
if dbuf[j] == 0xFF {
return n, false, CorruptInputError(i*8 + j)
}
}
// Pack 8x 5-bit source blocks into 5 byte destination
// quantum
switch dlen {
case 7, 8:
dst[i*5+4] = dbuf[6]<<5 | dbuf[7]
fallthrough
case 6, 5:
dst[i*5+3] = dbuf[4]<<7 | dbuf[5]<<2 | dbuf[6]>>3
fallthrough
case 4:
dst[i*5+2] = dbuf[3]<<4 | dbuf[4]>>1
fallthrough
case 3:
dst[i*5+1] = dbuf[1]<<6 | dbuf[2]<<1 | dbuf[3]>>4
fallthrough
case 2:
dst[i*5+0] = dbuf[0]<<3 | dbuf[1]>>2
}
switch dlen {
case 2:
n += 1
case 3, 4:
n += 2
case 5:
n += 3
case 6, 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.
func (enc *Encoding) Decode(dst, src []byte) (n int, err os.Error) {
if len(src)%8 != 0 {
return 0, CorruptInputError(len(src) / 8 * 8)
}
n, _, err = enc.decode(dst, src)
return
}
type decoder struct {
err os.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 (d *decoder) Read(p []byte) (n int, err os.Error) {
if d.err != nil {
return 0, d.err
}
// Use leftover decoded output from last read.
if len(d.out) > 0 {
n = copy(p, d.out)
d.out = d.out[n:]
return n, nil
}
// 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 = io.ReadAtLeast(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, d.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, d.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 d.err == nil {
d.err = err
}
return n, d.err
}
// NewDecoder constructs a new base32 stream decoder.
func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
return &decoder{enc: enc, r: 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 { return n / 8 * 5 }

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// Copyright 2009 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 base32
import (
"bytes"
"io/ioutil"
"os"
"testing"
)
type testpair struct {
decoded, encoded string
}
var pairs = []testpair{
// RFC 4648 examples
{"", ""},
{"f", "MY======"},
{"fo", "MZXQ===="},
{"foo", "MZXW6==="},
{"foob", "MZXW6YQ="},
{"fooba", "MZXW6YTB"},
{"foobar", "MZXW6YTBOI======"},
// Wikipedia examples, converted to base32
{"sure.", "ON2XEZJO"},
{"sure", "ON2XEZI="},
{"sur", "ON2XE==="},
{"su", "ON2Q===="},
{"leasure.", "NRSWC43VOJSS4==="},
{"easure.", "MVQXG5LSMUXA===="},
{"asure.", "MFZXK4TFFY======"},
{"sure.", "ON2XEZJO"},
}
var bigtest = testpair{
"Twas brillig, and the slithy toves",
"KR3WC4ZAMJZGS3DMNFTSYIDBNZSCA5DIMUQHG3DJORUHSIDUN53GK4Y=",
}
func testEqual(t *testing.T, msg string, args ...interface{}) bool {
if args[len(args)-2] != args[len(args)-1] {
t.Errorf(msg, args...)
return false
}
return true
}
func TestEncode(t *testing.T) {
for _, p := range pairs {
buf := make([]byte, StdEncoding.EncodedLen(len(p.decoded)))
StdEncoding.Encode(buf, []byte(p.decoded))
testEqual(t, "Encode(%q) = %q, want %q", p.decoded, string(buf), p.encoded)
}
}
func TestEncoder(t *testing.T) {
for _, p := range pairs {
bb := &bytes.Buffer{}
encoder := NewEncoder(StdEncoding, bb)
encoder.Write([]byte(p.decoded))
encoder.Close()
testEqual(t, "Encode(%q) = %q, want %q", p.decoded, bb.String(), p.encoded)
}
}
func TestEncoderBuffering(t *testing.T) {
input := []byte(bigtest.decoded)
for bs := 1; bs <= 12; bs++ {
bb := &bytes.Buffer{}
encoder := NewEncoder(StdEncoding, bb)
for pos := 0; pos < len(input); pos += bs {
end := pos + bs
if end > len(input) {
end = len(input)
}
n, err := encoder.Write(input[pos:end])
testEqual(t, "Write(%q) gave error %v, want %v", input[pos:end], err, os.Error(nil))
testEqual(t, "Write(%q) gave length %v, want %v", input[pos:end], n, end-pos)
}
err := encoder.Close()
testEqual(t, "Close gave error %v, want %v", err, os.Error(nil))
testEqual(t, "Encoding/%d of %q = %q, want %q", bs, bigtest.decoded, bb.String(), bigtest.encoded)
}
}
func TestDecode(t *testing.T) {
for _, p := range pairs {
dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))
count, end, err := StdEncoding.decode(dbuf, []byte(p.encoded))
testEqual(t, "Decode(%q) = error %v, want %v", p.encoded, err, os.Error(nil))
testEqual(t, "Decode(%q) = length %v, want %v", p.encoded, count, len(p.decoded))
if len(p.encoded) > 0 {
testEqual(t, "Decode(%q) = end %v, want %v", p.encoded, end, (p.encoded[len(p.encoded)-1] == '='))
}
testEqual(t, "Decode(%q) = %q, want %q", p.encoded,
string(dbuf[0:count]),
p.decoded)
}
}
func TestDecoder(t *testing.T) {
for _, p := range pairs {
decoder := NewDecoder(StdEncoding, bytes.NewBufferString(p.encoded))
dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))
count, err := decoder.Read(dbuf)
if err != nil && err != os.EOF {
t.Fatal("Read failed", err)
}
testEqual(t, "Read from %q = length %v, want %v", p.encoded, count, len(p.decoded))
testEqual(t, "Decoding of %q = %q, want %q", p.encoded, string(dbuf[0:count]), p.decoded)
if err != os.EOF {
count, err = decoder.Read(dbuf)
}
testEqual(t, "Read from %q = %v, want %v", p.encoded, err, os.EOF)
}
}
func TestDecoderBuffering(t *testing.T) {
for bs := 1; bs <= 12; bs++ {
decoder := NewDecoder(StdEncoding, bytes.NewBufferString(bigtest.encoded))
buf := make([]byte, len(bigtest.decoded)+12)
var total int
for total = 0; total < len(bigtest.decoded); {
n, err := decoder.Read(buf[total : total+bs])
testEqual(t, "Read from %q at pos %d = %d, %v, want _, %v", bigtest.encoded, total, n, err, os.Error(nil))
total += n
}
testEqual(t, "Decoding/%d of %q = %q, want %q", bs, bigtest.encoded, string(buf[0:total]), bigtest.decoded)
}
}
func TestDecodeCorrupt(t *testing.T) {
type corrupt struct {
e string
p int
}
examples := []corrupt{
{"!!!!", 0},
{"x===", 0},
{"AA=A====", 2},
{"AAA=AAAA", 3},
{"MMMMMMMMM", 8},
{"MMMMMM", 0},
}
for _, e := range examples {
dbuf := make([]byte, StdEncoding.DecodedLen(len(e.e)))
_, err := StdEncoding.Decode(dbuf, []byte(e.e))
switch err := err.(type) {
case CorruptInputError:
testEqual(t, "Corruption in %q at offset %v, want %v", e.e, int(err), e.p)
default:
t.Error("Decoder failed to detect corruption in", e)
}
}
}
func TestBig(t *testing.T) {
n := 3*1000 + 1
raw := make([]byte, n)
const alpha = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
for i := 0; i < n; i++ {
raw[i] = alpha[i%len(alpha)]
}
encoded := new(bytes.Buffer)
w := NewEncoder(StdEncoding, encoded)
nn, err := w.Write(raw)
if nn != n || err != nil {
t.Fatalf("Encoder.Write(raw) = %d, %v want %d, nil", nn, err, n)
}
err = w.Close()
if err != nil {
t.Fatalf("Encoder.Close() = %v want nil", err)
}
decoded, err := ioutil.ReadAll(NewDecoder(StdEncoding, encoded))
if err != nil {
t.Fatalf("ioutil.ReadAll(NewDecoder(...)): %v", err)
}
if !bytes.Equal(raw, decoded) {
var i int
for i = 0; i < len(decoded) && i < len(raw); i++ {
if decoded[i] != raw[i] {
break
}
}
t.Errorf("Decode(Encode(%d-byte string)) failed at offset %d", n, i)
}
}