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encoding.base32: initial implementation

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Joe Conigliaro 2022-09-27 16:25:50 +10:00
parent 385acb448a
commit 5415c4f75e
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339
vlib/encoding/base32/base32.v Normal file
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// 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.
// Based off: https://github.com/golang/go/blob/master/src/encoding/base32/base32.go
// Last commit: https://github.com/golang/go/commit/e1b62efaf33988a5153510898d37309cee78f26e
// TODO: standardize fn naming conventions & strip newlines on input & clean up an go remnant's
module base32
pub const(
std_padding = `=` // Standard padding character
no_padding = u8(-1) // No padding
std_alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'.bytes()
hex_alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUV'.bytes()
)
struct Encoding {
padding_char u8
alphabet []u8
mut:
decode_map [256]u8
}
pub fn decode_string_to_string(src string) ?string {
return decode_to_string(src.bytes())
}
pub fn decode_to_string(src []u8) ?string {
res := decode(src)?
return res.bytestr()
}
pub fn decode(src []u8) ?[]u8 {
mut e := new_encoding(std_alphabet)
return e.decode(src)
}
pub fn encode_string_to_string(src string) string {
return encode_to_string(src.bytes())
}
pub fn encode_to_string(src []u8) string {
return encode(src).bytestr()
}
pub fn encode(src []u8) []u8 {
e := new_encoding(std_alphabet)
return e.encode(src)
}
pub fn (enc &Encoding) encode_to_string(src []u8) string {
return enc.encode(src).bytestr()
}
pub fn (enc &Encoding) encode_string_to_string(src string) string {
return enc.encode(src.bytes()).bytestr()
}
pub fn new_std_encoding() Encoding {
return new_encoding_with_padding(std_alphabet, std_padding)
}
pub fn new_std_encoding_with_padding(padding u8) Encoding {
return new_encoding_with_padding(std_alphabet, padding)
}
pub fn new_encoding(alphabet []u8) Encoding {
return new_encoding_with_padding(alphabet, std_padding)
}
pub fn new_encoding_with_padding(alphabet []u8, padding_char u8) Encoding {
if padding_char == `\r` || padding_char == `\n` || padding_char > 0xff {
panic('invalid padding')
}
for i := 0; i < alphabet.len; i++ {
if alphabet[i] == padding_char {
panic('padding contained in alphabet')
}
}
mut decode_map := [256]u8{}
for i in 0..alphabet.len {
decode_map[alphabet[i]] = u8(i)
}
return Encoding{
alphabet: alphabet
padding_char: padding_char
decode_map: decode_map
}
}
fn (enc &Encoding) encode(src []u8) []u8 {
mut buf := []u8{len: enc.encoded_len(src.len)}
mut dst := unsafe { buf }
enc.encode_(src, mut dst)
return buf
}
// Encode encodes src using the encoding enc, writing
// encoded_len(src.len) u8s to dst.
//
// The encoding pads the output to a multiple of 8 u8s,
// so Encode is not appropriate for use on individual blocks
// of a large data stream. Use new_encoder() instead.
fn (enc &Encoding) encode_(src_ []u8, mut dst []u8) {
mut src := unsafe { src_ }
for src.len > 0 {
mut b := [8]u8{}
// Unpack 8x 5-bit source blocks into a 5 u8
// destination quantum
if src.len > 4 {
b[7] = src[4] & 0x1F
b[6] = src[4] >> 5
}
if src.len >= 4 {
b[6] |= (src[3] << 3) & 0x1F
b[5] = (src[3] >> 2) & 0x1F
b[4] = src[3] >> 7
}
if src.len >= 3 {
b[4] |= (src[2] << 1) & 0x1F
b[3] = (src[2] >> 4) & 0x1F
}
if src.len >= 2 {
b[3] |= (src[1] << 4) & 0x1F
b[2] = (src[1] >> 1) & 0x1F
b[1] = (src[1] >> 6) & 0x1F
}
if src.len >= 1 {
b[1] |= (src[0] << 2) & 0x1F
b[0] = src[0] >> 3
}
// Encode 5-bit blocks using the base32 alphabet
if dst.len >= 8 {
// Common case, unrolled for extra performance
dst[0] = enc.alphabet[b[0]&31]
dst[1] = enc.alphabet[b[1]&31]
dst[2] = enc.alphabet[b[2]&31]
dst[3] = enc.alphabet[b[3]&31]
dst[4] = enc.alphabet[b[4]&31]
dst[5] = enc.alphabet[b[5]&31]
dst[6] = enc.alphabet[b[6]&31]
dst[7] = enc.alphabet[b[7]&31]
} else {
for i := 0; i < dst.len; i++ {
dst[i] = enc.alphabet[b[i]&31]
}
}
// Pad the final quantum
if src.len < 5 {
if enc.padding_char == no_padding {
break
}
dst[7] = enc.padding_char
if src.len < 4 {
dst[6] = enc.padding_char
dst[5] = enc.padding_char
if src.len < 3 {
dst[4] = enc.padding_char
if src.len < 2 {
dst[3] = enc.padding_char
dst[2] = enc.padding_char
}
}
}
break
}
src = src[5..]
dst = dst[8..]
}
}
fn (enc &Encoding) encoded_len(n int) int {
if enc.padding_char == no_padding {
return (n*8 + 4) / 5
}
return (n + 4) / 5 * 8
}
pub fn (enc &Encoding) decode_string(src string) ?[]u8 {
return enc.decode(src.bytes())
// mut buf := strip_newlines(src.bytes())
// mut dst := unsafe { buf }
// // l := strip_newlines(mut buf)
// n, _ := enc.decode_(buf, mut dst)?
// return buf[..n]
}
pub fn (enc &Encoding) decode_string_to_string(src string) ?string {
decoded := enc.decode_string(src)?
return decoded.bytestr()
}
pub fn (enc &Encoding) decode(src []u8) ?[]u8 {
mut buf := []u8{len: src.len}
// mut dst := unsafe { buf }
// l := strip_newlines(mut dst, src)
// n, _ := enc.decode_(src[..l], mut dst) or {
// src := strip_newlines(src_)
n, _ := enc.decode_(src, mut buf) or {
return err
}
return buf[..n]
}
// 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`).
fn (enc &Encoding) decode_(src_ []u8, mut dst []u8) ?(int, bool) {
mut src := unsafe { src_ }
mut n := 0
mut end := false
// Lift the nil check outside of the loop.
// _ = enc.decode_map
mut dsti := 0
olen := src.len
for src.len > 0 && !end {
// Decode quantum using the base32 alphabet
mut dbuf := [8]u8{}
mut dlen := 8
for j := 0; j < 8; {
if src.len == 0 {
if enc.padding_char != no_padding {
// We have reached the end and are missing padding
// return n, false, corrupt_input_error(olen - src.len - j)
return error(corrupt_input_error_msg(olen - src.len - j))
}
// We have reached the end and are not expecting any padding
dlen, end = j, true
break
}
in0 := src[0]
src = src[1..]
if in0 == enc.padding_char && j >= 2 && src.len < 8 {
// We`ve reached the end and there`s padding
if src.len+j < 8-1 {
// not enough padding
// return n, false, corrupt_input_error(olen)
return error(corrupt_input_error_msg(olen))
}
for k := 0; k < 8-1-j; k++ {
if src.len > k && src[k] != enc.padding_char {
// incorrect padding
// return n, false, corrupt_input_error(olen - src.len + k - 1)
return error(corrupt_input_error_msg(olen - src.len + 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 u8s do not yield enough information to decode a dst u8.
if dlen == 1 || dlen == 3 || dlen == 6 {
// return n, false, corrupt_input_error(olen - src.len - 1)
return error(corrupt_input_error_msg(olen - src.len - 1))
}
break
}
dbuf[j] = enc.decode_map[in0]
if dbuf[j] == 0xFF {
// return n, false, corrupt_input_error(olen - src.len - 1)
return error(corrupt_input_error_msg(olen - src.len - 1))
}
j++
}
// Pack 8x 5-bit source blocks into 5 u8 destination
// quantum
if dlen == 8 {
dst[dsti+4] = dbuf[6]<<5 | dbuf[7]
n++
}
if dlen >= 7 {
dst[dsti+3] = dbuf[4]<<7 | dbuf[5]<<2 | dbuf[6]>>3
n++
}
if dlen >= 5 {
dst[dsti+2] = dbuf[3]<<4 | dbuf[4]>>1
n++
}
if dlen >= 4 {
dst[dsti+1] = dbuf[1]<<6 | dbuf[2]<<1 | dbuf[3]>>4
n++
}
if dlen >= 2 {
dst[dsti+0] = dbuf[0]<<3 | dbuf[1]>>2
n++
}
dsti += 5
}
return n, end
}
// stripNewlines removes newline characters and returns the number
// of non-newline characters copied to dst.
// fn strip_newlines(mut dst []u8, src []byte) int {
// mut offset := 0
// for b in src {
// if b in [`\r`, `\n`] {
// continue
// }
// dst[offset] = b
// offset++
// }
// return offset
// }
fn strip_newlines(src []u8) []u8 {
mut dst := []u8{}
for b in src {
if b in [`\r`, `\n`] {
continue
}
dst << b
}
return dst
}
fn corrupt_input_error_msg(e int) string {
// return error('illegal base32 data at input byte ' + strconv.FormatInt(int64(e), 10)
return 'illegal base32 data at input byte $e'
}

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vlib/encoding/base32/base32_test.v Normal file
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import encoding.base32
// TODO: add more tests
fn test_encode_and_decode() {
input := 'hello v'
encoded := base32.encode_string_to_string(input)
assert encoded == 'NBSWY3DPEB3A===='
decoded := base32.decode_string_to_string(encoded) or {
panic('error decoding: $err')
}
assert decoded == input
encoder_no_padding := base32.new_std_encoding_with_padding(base32.no_padding)
encoded2 := encoder_no_padding.encode_string_to_string(input)
assert encoded2 == 'NBSWY3DPEB3A'
decoded2 := encoder_no_padding.decode_string_to_string(encoded2) or {
panic('error decoding: $err')
}
assert decoded2 == input
}