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use super::{ErrorKind, Result};
#[inline(always)]
fn encode_base64_char(six_bits: u8) -> u8 {
let mut offset = 0x41_u16;
offset = offset.wrapping_add(25_u16.wrapping_sub(six_bits.into()) >> 8 & 6u16);
offset = offset.wrapping_sub(51_u16.wrapping_sub(six_bits.into()) >> 8 & 75u16);
offset = offset.wrapping_sub(61_u16.wrapping_sub(six_bits.into()) >> 8 & 15u16);
offset = offset.wrapping_add(62_u16.wrapping_sub(six_bits.into()) >> 8 & 3u16);
(six_bits.wrapping_add(offset as u8))
}
#[inline(always)]
fn decode_base64_char(chr: u8) -> u8 {
let mut ret = -1;
let src = i32::from(chr as i8);
ret += (((0x40 - src) & (src - 0x5b)) >> 8) & (src - 64);
ret += (((0x60 - src) & (src - 0x7b)) >> 8) & (src - 70);
ret += (((0x2f - src) & (src - 0x3a)) >> 8) & (src + 5);
ret += (((0x2a - src) & (src - 0x2c)) >> 8) & 63;
ret += (((0x2e - src) & (src - 0x30)) >> 8) & 64;
ret as u8
}
#[inline(always)]
pub fn base64_encoded_max_size(sz: usize) -> usize {
(sz / 3 + 1) * 4
}
#[inline(always)]
pub fn base64_decoded_max_size(sz: usize) -> usize {
(sz / 4 + 1) * 3
}
pub fn base64_encode(bytestring: &[u8], add_padding: bool) -> Vec<u8> {
let mut dest = Vec::<u8>::with_capacity(base64_encoded_max_size(bytestring.len()));
for chunk in bytestring.chunks(3) {
let b0 = chunk[0];
match chunk.len() {
3 => {
let b1 = chunk[1];
let b2 = chunk[2];
dest.push(encode_base64_char(b0 >> 2));
dest.push(encode_base64_char((b0 << 4 | b1 >> 4) & 63));
dest.push(encode_base64_char((b1 << 2 | b2 >> 6) & 63));
dest.push(encode_base64_char(b2 & 63));
}
2 => {
let b1 = chunk[1];
dest.push(encode_base64_char(b0 >> 2));
dest.push(encode_base64_char((b0 << 4 | b1 >> 4) & 63));
dest.push(encode_base64_char((b1 << 2) & 63));
if add_padding {
dest.push(b'=');
}
}
_ => {
dest.push(encode_base64_char(b0 >> 2));
dest.push(encode_base64_char(b0 << 4 & 63));
if add_padding {
dest.push(b'=');
dest.push(b'=');
}
}
}
}
dest
}
pub fn base64_decode(encoded: &[u8], strict_padding: bool) -> Result<Vec<u8>> {
if encoded.is_empty() {
return Ok(vec![]);
}
let mut out = Vec::<u8>::with_capacity(base64_decoded_max_size(encoded.len()));
let encoded_unpad = if strict_padding {
let mut end_len = encoded.len();
if end_len & 3 == 0 && encoded[end_len - 1] == b'=' {
end_len -= 1;
if encoded[end_len - 1] == b'=' {
end_len -= 1;
}
}
if end_len & 3 == 1 {
return Err(ErrorKind::BadPadding);
}
if encoded[end_len - 1] == b'=' {
return Err(ErrorKind::BadPadding);
}
&encoded[0..end_len]
} else {
let diff = encoded.iter().rev().skip_while(|b| **b == b'=').count();
let end_len = encoded.len();
&encoded[0..end_len - (end_len - diff)]
};
let mut err = 0;
for chunk in encoded_unpad.chunks(4) {
let c0 = decode_base64_char(chunk[0]);
match chunk.len() {
4 => {
let c1 = decode_base64_char(chunk[1]);
let c2 = decode_base64_char(chunk[2]);
let c3 = decode_base64_char(chunk[3]);
out.push((c0 << 2) | (c1 >> 4));
out.push((c1 << 4) | (c2 >> 2));
out.push((c2 << 6) | c3);
err |= i32::from((c0 | c1 | c2 | c3) as i8) >> 8;
}
3 => {
let c1 = decode_base64_char(chunk[1]);
let c2 = decode_base64_char(chunk[2]);
out.push((c0 << 2) | (c1 >> 4));
out.push((c1 << 4) | (c2 >> 2));
err |= i32::from((c0 | c1 | c2) as i8) >> 8;
}
2 => {
let c1 = decode_base64_char(chunk[1]);
out.push((c0 << 2) | (c1 >> 4));
err |= i32::from((c0 | c1) as i8) >> 8;
}
_ => if strict_padding {
err |= 1;
},
}
}
if err != 0 {
Err(ErrorKind::InvalidEncodingChar)
} else {
Ok(out)
}
}
#[cfg(test)]
mod tests {
use base64::{base64_decode, base64_encode, decode_base64_char, encode_base64_char};
#[test]
fn test_encoding() {
assert_eq!(
(0u8..64u8)
.map(|x| encode_base64_char(x))
.collect::<Vec<u8>>(),
("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
.as_bytes()
.to_owned())
);
}
#[test]
fn test_decoding() {
assert_eq!(
b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
.to_owned()
.iter()
.map(|x| decode_base64_char(*x))
.collect::<Vec<u8>>(),
(0u8..64u8).map(|x| x).collect::<Vec<u8>>()
);
}
#[test]
fn test_can_encode() {
assert_eq!(
&base64_encode(b"Hello, world!", true),
b"SGVsbG8sIHdvcmxkIQ=="
);
}
#[test]
fn test_can_decode() {
assert_eq!(
&*base64_decode(b"SGVsbG8sIHdvcmxkIQ==", true).unwrap(),
b"Hello, world!"
);
}
#[test]
fn test_can_encode_empty() {
assert_eq!(&base64_encode(b"", true), b"");
}
#[test]
fn test_can_decode_empty() {
assert_eq!(*base64_decode(b"", true).unwrap(), []);
}
quickcheck! {
fn test_encode_always_correctly_padded(bytes: Vec<u8>) -> bool {
println!("Trying {:?}", bytes);
base64_encode(&bytes, true).len() % 4 == 0
}
fn test_encode_decode_is_identity(bytes: Vec<u8>) -> bool {
println!("Trying {:?}", bytes);
bytes == base64_decode(&base64_encode(&bytes, true), true).unwrap()
}
}
}