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|
use crate::error::Error;
use lazy_static::lazy_static;
pub fn encoded_len(input_len: usize) -> usize {
if input_len == 0 {
0
} else {
(input_len * 8 - 1) / 5 + 1
}
}
pub fn decoded_len(input_len: usize) -> usize {
input_len * 5 / 8
}
static BASE32_CHARS: &[u8; 32] = &b"0123456789abcdfghijklmnpqrsvwxyz";
lazy_static! {
static ref BASE32_CHARS_REVERSE: Box<[u8; 256]> = {
let mut xs = [0xffu8; 256];
for (n, c) in BASE32_CHARS.iter().enumerate() {
xs[*c as usize] = n as u8;
}
Box::new(xs)
};
}
pub fn encode(input: &[u8]) -> String {
let mut buf = vec![0; encoded_len(input.len())];
encode_into(input, &mut buf);
std::str::from_utf8(&buf).unwrap().to_string()
}
pub fn encode_into(input: &[u8], output: &mut [u8]) {
let len = encoded_len(input.len());
assert_eq!(len, output.len());
let mut nr_bits_left: usize = 0;
let mut bits_left: u16 = 0;
let mut pos = len;
for b in input {
bits_left |= (*b as u16) << nr_bits_left;
nr_bits_left += 8;
while nr_bits_left > 5 {
output[pos - 1] = BASE32_CHARS[(bits_left & 0x1f) as usize];
pos -= 1;
bits_left >>= 5;
nr_bits_left -= 5;
}
}
if nr_bits_left > 0 {
output[pos - 1] = BASE32_CHARS[(bits_left & 0x1f) as usize];
pos -= 1;
}
assert_eq!(pos, 0);
}
pub fn decode(input: &str) -> Result<Vec<u8>, crate::Error> {
let mut res = Vec::with_capacity(decoded_len(input.len()));
let mut nr_bits_left: usize = 0;
let mut bits_left: u16 = 0;
for c in input.chars().rev() {
let b = BASE32_CHARS_REVERSE[c as usize];
if b == 0xff {
return Err(Error::BadBase32);
}
bits_left |= (b as u16) << nr_bits_left;
nr_bits_left += 5;
if nr_bits_left >= 8 {
res.push((bits_left & 0xff) as u8);
bits_left >>= 8;
nr_bits_left -= 8;
}
}
if nr_bits_left > 0 && bits_left != 0 {
return Err(Error::BadBase32);
}
Ok(res)
}
#[cfg(test)]
mod tests {
use super::*;
use assert_matches::assert_matches;
use hex;
use proptest::proptest;
#[test]
fn test_encode() {
assert_eq!(encode(&[]), "");
assert_eq!(
encode(&hex::decode("0839703786356bca59b0f4a32987eb2e6de43ae8").unwrap()),
"x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88"
);
assert_eq!(
encode(
&hex::decode("ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad")
.unwrap()
),
"1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"
);
assert_eq!(
encode(
&hex::decode("ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f")
.unwrap()
),
"2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx"
);
}
#[test]
fn test_decode() {
assert_eq!(hex::encode(decode("").unwrap()), "");
assert_eq!(
hex::encode(decode("x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88").unwrap()),
"0839703786356bca59b0f4a32987eb2e6de43ae8"
);
assert_eq!(
hex::encode(decode("1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s").unwrap()),
"ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
);
assert_eq!(
hex::encode(decode("2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx").unwrap()),
"ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f"
);
assert_matches!(
decode("xoxf8v9fxf3jk8zln1cwlsrmhqvp0f88"),
Err(Error::BadBase32)
);
assert_matches!(
decode("2b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"),
Err(Error::BadBase32)
);
assert_matches!(decode("2"), Err(Error::BadBase32));
assert_matches!(decode("2gs"), Err(Error::BadBase32));
assert_matches!(decode("2gs8"), Err(Error::BadBase32));
}
proptest! {
#[test]
fn roundtrip(s: Vec<u8>) {
assert_eq!(s, decode(&encode(&s)).unwrap());
}
}
}
|
