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#[cfg(test)]
extern crate quickcheck;
#[cfg(test)]
extern crate rand;
use std::cmp::min;
#[derive(Copy,Clone)]
pub enum Alphabet {
RFC4648 { padding: bool },
Crockford,
}
const RFC4648_ALPHABET: &'static [u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
const CROCKFORD_ALPHABET: &'static [u8] = b"0123456789ABCDEFGHJKMNPQRSTVWXYZ";
pub fn encode(alphabet: Alphabet, data: &[u8]) -> String {
let (alphabet, padding) = match alphabet {
Alphabet::RFC4648 { padding } => (RFC4648_ALPHABET, padding),
Alphabet::Crockford => (CROCKFORD_ALPHABET, false),
};
let mut ret = Vec::with_capacity((data.len()+3)/4*5);
for chunk in data.chunks(5) {
let buf = {
let mut buf = [0u8; 5];
for (i, &b) in chunk.iter().enumerate() {
buf[i] = b;
}
buf
};
ret.push(alphabet[((buf[0] & 0xF8) >> 3) as usize]);
ret.push(alphabet[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
ret.push(alphabet[((buf[1] & 0x3E) >> 1) as usize]);
ret.push(alphabet[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
ret.push(alphabet[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
ret.push(alphabet[((buf[3] & 0x7C) >> 2) as usize]);
ret.push(alphabet[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
ret.push(alphabet[(buf[4] & 0x1F) as usize]);
}
if data.len() % 5 != 0 {
let len = ret.len();
let num_extra = 8-(data.len()%5*8+4)/5;
if padding {
for i in 1..num_extra+1 {
ret[len-i] = b'=';
}
} else {
ret.truncate(len-num_extra);
}
}
String::from_utf8(ret).unwrap()
}
const RFC4648_INV_ALPHABET: [i8; 43] = [-1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, 0, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25];
const CROCKFORD_INV_ALPHABET: [i8; 43] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, 16, 17, 1, 18, 19, 1, 20, 21, 0, 22, 23, 24, 25, 26, -1, 27, 28, 29, 30, 31];
pub fn decode(alphabet: Alphabet, data: &str) -> Option<Vec<u8>> {
if !data.is_ascii() {
return None;
}
let data = data.as_bytes();
let alphabet = match alphabet {
Alphabet::RFC4648 {..} => RFC4648_INV_ALPHABET,
Alphabet::Crockford => CROCKFORD_INV_ALPHABET
};
let mut unpadded_data_length = data.len();
for i in 1..min(6, data.len())+1 {
if data[data.len() - i] != b'=' {
break;
}
unpadded_data_length -= 1;
}
let output_length = unpadded_data_length*5/8;
let mut ret = Vec::with_capacity((output_length+4)/5*5);
for chunk in data.chunks(8) {
let buf = {
let mut buf = [0u8; 8];
for (i, &c) in chunk.iter().enumerate() {
match alphabet.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
Some(&-1) | None => return None,
Some(&value) => buf[i] = value as u8,
};
}
buf
};
ret.push((buf[0] << 3) | (buf[1] >> 2));
ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
ret.push((buf[3] << 4) | (buf[4] >> 1));
ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
ret.push((buf[6] << 5) | buf[7]);
}
ret.truncate(output_length);
Some(ret)
}
#[cfg(test)]
#[allow(dead_code, unused_attributes)]
mod test {
use super::{encode, decode};
use super::Alphabet::{Crockford, RFC4648};
use quickcheck;
use std;
use rand::Rng;
#[derive(Clone)]
struct B32 {
c: u8
}
impl quickcheck::Arbitrary for B32 {
fn arbitrary<G: quickcheck::Gen>(g: &mut G) -> B32 {
let alphabet = b"0123456789ABCDEFGHJKMNPQRSTVWXYZ";
B32 {
c: alphabet[g.gen_range(0, alphabet.len())]
}
}
}
impl std::fmt::Debug for B32 {
fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
(self.c as char).fmt(f)
}
}
#[test]
fn masks_crockford() {
assert_eq!(encode(Crockford, &[0xF8, 0x3E, 0x0F, 0x83, 0xE0]), "Z0Z0Z0Z0");
assert_eq!(encode(Crockford, &[0x07, 0xC1, 0xF0, 0x7C, 0x1F]), "0Z0Z0Z0Z");
assert_eq!(decode(Crockford, "Z0Z0Z0Z0").unwrap(), [0xF8, 0x3E, 0x0F, 0x83, 0xE0]);
assert_eq!(decode(Crockford, "0Z0Z0Z0Z").unwrap(), [0x07, 0xC1, 0xF0, 0x7C, 0x1F]);
}
#[test]
fn masks_rfc4648() {
assert_eq!(encode(RFC4648 { padding: true }, &[0xF8, 0x3E, 0x7F, 0x83, 0xE7]), "7A7H7A7H");
assert_eq!(encode(RFC4648 { padding: true }, &[0x77, 0xC1, 0xF7, 0x7C, 0x1F]), "O7A7O7A7");
assert_eq!(decode(RFC4648 { padding: true }, "7A7H7A7H").unwrap(), [0xF8, 0x3E, 0x7F, 0x83, 0xE7]);
assert_eq!(decode(RFC4648 { padding: true }, "O7A7O7A7").unwrap(), [0x77, 0xC1, 0xF7, 0x7C, 0x1F]);
assert_eq!(encode(RFC4648 { padding: true }, &[0xF8, 0x3E, 0x7F, 0x83]), "7A7H7AY=");
}
#[test]
fn masks_unpadded_rfc4648() {
assert_eq!(encode(RFC4648 { padding: false }, &[0xF8, 0x3E, 0x7F, 0x83, 0xE7]), "7A7H7A7H");
assert_eq!(encode(RFC4648 { padding: false }, &[0x77, 0xC1, 0xF7, 0x7C, 0x1F]), "O7A7O7A7");
assert_eq!(decode(RFC4648 { padding: false }, "7A7H7A7H").unwrap(), [0xF8, 0x3E, 0x7F, 0x83, 0xE7]);
assert_eq!(decode(RFC4648 { padding: false }, "O7A7O7A7").unwrap(), [0x77, 0xC1, 0xF7, 0x7C, 0x1F]);
assert_eq!(encode(RFC4648 { padding: false }, &[0xF8, 0x3E, 0x7F, 0x83]), "7A7H7AY");
}
#[test]
fn padding() {
let num_padding = [0, 6, 4, 3, 1];
for i in 1..6 {
let encoded = encode(RFC4648 { padding: true }, (0..(i as u8)).collect::<Vec<u8>>().as_ref());
assert_eq!(encoded.len(), 8);
for j in 0..(num_padding[i % 5]) {
assert_eq!(encoded.as_bytes()[encoded.len()-j-1], b'=');
}
for j in 0..(8 - num_padding[i % 5]) {
assert!(encoded.as_bytes()[j] != b'=');
}
}
}
#[test]
fn invertible_crockford() {
fn test(data: Vec<u8>) -> bool {
decode(Crockford, encode(Crockford, data.as_ref()).as_ref()).unwrap() == data
}
quickcheck::quickcheck(test as fn(Vec<u8>) -> bool)
}
#[test]
fn invertible_rfc4648() {
fn test(data: Vec<u8>) -> bool {
decode(RFC4648 { padding: true }, encode(RFC4648 { padding: true }, data.as_ref()).as_ref()).unwrap() == data
}
quickcheck::quickcheck(test as fn(Vec<u8>) -> bool)
}
#[test]
fn invertible_unpadded_rfc4648() {
fn test(data: Vec<u8>) -> bool {
decode(RFC4648 { padding: false }, encode(RFC4648 { padding: false }, data.as_ref()).as_ref()).unwrap() == data
}
quickcheck::quickcheck(test as fn(Vec<u8>) -> bool)
}
#[test]
fn lower_case() {
fn test(data: Vec<B32>) -> bool {
let data: String = data.iter().map(|e| e.c as char).collect();
decode(Crockford, data.as_ref()) == decode(Crockford, data.to_ascii_lowercase().as_ref())
}
quickcheck::quickcheck(test as fn(Vec<B32>) -> bool)
}
#[test]
#[allow(non_snake_case)]
fn iIlL1_oO0() {
assert_eq!(decode(Crockford, "IiLlOo"), decode(Crockford, "111100"));
}
#[test]
fn invalid_chars_crockford() {
assert_eq!(decode(Crockford, ","), None)
}
#[test]
fn invalid_chars_rfc4648() {
assert_eq!(decode(RFC4648 { padding: true }, ","), None)
}
#[test]
fn invalid_chars_unpadded_rfc4648() {
assert_eq!(decode(RFC4648 { padding: false }, ","), None)
}
}
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