]> Cypherpunks repositories - gostls13.git/commitdiff
encoding/base32: new package
authorMiek Gieben <miek@miek.nl>
Thu, 20 Jan 2011 17:51:15 +0000 (12:51 -0500)
committerRuss Cox <rsc@golang.org>
Thu, 20 Jan 2011 17:51:15 +0000 (12:51 -0500)
R=rsc
CC=Miek Gieben, golang-dev
https://golang.org/cl/3926041

src/pkg/Makefile
src/pkg/encoding/base32/Makefile [new file with mode: 0644]
src/pkg/encoding/base32/base32.go [new file with mode: 0644]
src/pkg/encoding/base32/base32_test.go [new file with mode: 0644]

index 3494e1c13aefee1c9d6c44e3549f23e6356082cb..6e3c7f05f7c6fd6c510a863968a4a0b203a7001b 100644 (file)
@@ -58,6 +58,7 @@ DIRS=\
        debug/proc\
        ebnf\
        encoding/ascii85\
+       encoding/base32\
        encoding/base64\
        encoding/binary\
        encoding/git85\
diff --git a/src/pkg/encoding/base32/Makefile b/src/pkg/encoding/base32/Makefile
new file mode 100644 (file)
index 0000000..c0e85b6
--- /dev/null
@@ -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
diff --git a/src/pkg/encoding/base32/base32.go b/src/pkg/encoding/base32/base32.go
new file mode 100644 (file)
index 0000000..acace30
--- /dev/null
@@ -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 }
diff --git a/src/pkg/encoding/base32/base32_test.go b/src/pkg/encoding/base32/base32_test.go
new file mode 100644 (file)
index 0000000..792e4dc
--- /dev/null
@@ -0,0 +1,194 @@
+// 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)
+       }
+}