blob: 2dfa3ad0387b41b774e7a837b5cb37a0dc78fa0b [file] [log] [blame]
use byteorder::{BigEndian, ByteOrder};
use {tables, Config, STANDARD};
use std::{error, fmt, str};
// decode logic operates on chunks of 8 input bytes without padding
const INPUT_CHUNK_LEN: usize = 8;
const DECODED_CHUNK_LEN: usize = 6;
// we read a u64 and write a u64, but a u64 of input only yields 6 bytes of output, so the last
// 2 bytes of any output u64 should not be counted as written to (but must be available in a
// slice).
const DECODED_CHUNK_SUFFIX: usize = 2;
// how many u64's of input to handle at a time
const CHUNKS_PER_FAST_LOOP_BLOCK: usize = 4;
const INPUT_BLOCK_LEN: usize = CHUNKS_PER_FAST_LOOP_BLOCK * INPUT_CHUNK_LEN;
// includes the trailing 2 bytes for the final u64 write
const DECODED_BLOCK_LEN: usize =
CHUNKS_PER_FAST_LOOP_BLOCK * DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX;
/// Errors that can occur while decoding.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum DecodeError {
/// An invalid byte was found in the input. The offset and offending byte are provided.
InvalidByte(usize, u8),
/// The length of the input is invalid.
InvalidLength,
/// The last non-padding input symbol's encoded 6 bits have nonzero bits that will be discarded.
/// This is indicative of corrupted or truncated Base64.
/// Unlike InvalidByte, which reports symbols that aren't in the alphabet, this error is for
/// symbols that are in the alphabet but represent nonsensical encodings.
InvalidLastSymbol(usize, u8),
}
impl fmt::Display for DecodeError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
DecodeError::InvalidByte(index, byte) => {
write!(f, "Invalid byte {}, offset {}.", byte, index)
}
DecodeError::InvalidLength => write!(f, "Encoded text cannot have a 6-bit remainder."),
DecodeError::InvalidLastSymbol(index, byte) => {
write!(f, "Invalid last symbol {}, offset {}.", byte, index)
}
}
}
}
impl error::Error for DecodeError {
fn description(&self) -> &str {
match *self {
DecodeError::InvalidByte(_, _) => "invalid byte",
DecodeError::InvalidLength => "invalid length",
DecodeError::InvalidLastSymbol(_, _) => "invalid last symbol",
}
}
fn cause(&self) -> Option<&error::Error> {
None
}
}
///Decode from string reference as octets.
///Returns a Result containing a Vec<u8>.
///Convenience `decode_config(input, base64::STANDARD);`.
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let bytes = base64::decode("aGVsbG8gd29ybGQ=").unwrap();
/// println!("{:?}", bytes);
///}
///```
pub fn decode<T: ?Sized + AsRef<[u8]>>(input: &T) -> Result<Vec<u8>, DecodeError> {
decode_config(input, STANDARD)
}
///Decode from string reference as octets.
///Returns a Result containing a Vec<u8>.
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let bytes = base64::decode_config("aGVsbG8gd29ybGR+Cg==", base64::STANDARD).unwrap();
/// println!("{:?}", bytes);
///
/// let bytes_url = base64::decode_config("aGVsbG8gaW50ZXJuZXR-Cg==", base64::URL_SAFE).unwrap();
/// println!("{:?}", bytes_url);
///}
///```
pub fn decode_config<T: ?Sized + AsRef<[u8]>>(
input: &T,
config: Config,
) -> Result<Vec<u8>, DecodeError> {
let mut buffer = Vec::<u8>::with_capacity(input.as_ref().len() * 4 / 3);
decode_config_buf(input, config, &mut buffer).map(|_| buffer)
}
///Decode from string reference as octets.
///Writes into the supplied buffer to avoid allocation.
///Returns a Result containing an empty tuple, aka ().
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let mut buffer = Vec::<u8>::new();
/// base64::decode_config_buf("aGVsbG8gd29ybGR+Cg==", base64::STANDARD, &mut buffer).unwrap();
/// println!("{:?}", buffer);
///
/// buffer.clear();
///
/// base64::decode_config_buf("aGVsbG8gaW50ZXJuZXR-Cg==", base64::URL_SAFE, &mut buffer)
/// .unwrap();
/// println!("{:?}", buffer);
///}
///```
pub fn decode_config_buf<T: ?Sized + AsRef<[u8]>>(
input: &T,
config: Config,
buffer: &mut Vec<u8>,
) -> Result<(), DecodeError> {
let input_bytes = input.as_ref();
let starting_output_len = buffer.len();
let num_chunks = num_chunks(input_bytes);
let decoded_len_estimate = num_chunks
.checked_mul(DECODED_CHUNK_LEN)
.and_then(|p| p.checked_add(starting_output_len))
.expect("Overflow when calculating output buffer length");
buffer.resize(decoded_len_estimate, 0);
let bytes_written;
{
let buffer_slice = &mut buffer.as_mut_slice()[starting_output_len..];
bytes_written = decode_helper(input_bytes, num_chunks, config, buffer_slice)?;
}
buffer.truncate(starting_output_len + bytes_written);
Ok(())
}
/// Decode the input into the provided output slice.
///
/// This will not write any bytes past exactly what is decoded (no stray garbage bytes at the end).
///
/// If you don't know ahead of time what the decoded length should be, size your buffer with a
/// conservative estimate for the decoded length of an input: 3 bytes of output for every 4 bytes of
/// input, rounded up, or in other words `(input_len + 3) / 4 * 3`.
///
/// If the slice is not large enough, this will panic.
pub fn decode_config_slice<T: ?Sized + AsRef<[u8]>>(
input: &T,
config: Config,
output: &mut [u8],
) -> Result<usize, DecodeError> {
let input_bytes = input.as_ref();
decode_helper(
input_bytes,
num_chunks(input_bytes),
config,
output,
)
}
/// Return the number of input chunks (including a possibly partial final chunk) in the input
fn num_chunks(input: &[u8]) -> usize {
input
.len()
.checked_add(INPUT_CHUNK_LEN - 1)
.expect("Overflow when calculating number of chunks in input")
/ INPUT_CHUNK_LEN
}
/// Helper to avoid duplicating num_chunks calculation, which is costly on short inputs.
/// Returns the number of bytes written, or an error.
// We're on the fragile edge of compiler heuristics here. If this is not inlined, slow. If this is
// inlined(always), a different slow. plain ol' inline makes the benchmarks happiest at the moment,
// but this is fragile and the best setting changes with only minor code modifications.
#[inline]
fn decode_helper(
input: &[u8],
num_chunks: usize,
config: Config,
output: &mut [u8],
) -> Result<usize, DecodeError> {
let char_set = config.char_set;
let decode_table = char_set.decode_table();
let remainder_len = input.len() % INPUT_CHUNK_LEN;
// Because the fast decode loop writes in groups of 8 bytes (unrolled to
// CHUNKS_PER_FAST_LOOP_BLOCK times 8 bytes, where possible) and outputs 8 bytes at a time (of
// which only 6 are valid data), we need to be sure that we stop using the fast decode loop
// soon enough that there will always be 2 more bytes of valid data written after that loop.
let trailing_bytes_to_skip = match remainder_len {
// if input is a multiple of the chunk size, ignore the last chunk as it may have padding,
// and the fast decode logic cannot handle padding
0 => INPUT_CHUNK_LEN,
// 1 and 5 trailing bytes are illegal: can't decode 6 bits of input into a byte
1 | 5 => return Err(DecodeError::InvalidLength),
// This will decode to one output byte, which isn't enough to overwrite the 2 extra bytes
// written by the fast decode loop. So, we have to ignore both these 2 bytes and the
// previous chunk.
2 => INPUT_CHUNK_LEN + 2,
// If this is 3 unpadded chars, then it would actually decode to 2 bytes. However, if this
// is an erroneous 2 chars + 1 pad char that would decode to 1 byte, then it should fail
// with an error, not panic from going past the bounds of the output slice, so we let it
// use stage 3 + 4.
3 => INPUT_CHUNK_LEN + 3,
// This can also decode to one output byte because it may be 2 input chars + 2 padding
// chars, which would decode to 1 byte.
4 => INPUT_CHUNK_LEN + 4,
// Everything else is a legal decode len (given that we don't require padding), and will
// decode to at least 2 bytes of output.
_ => remainder_len,
};
// rounded up to include partial chunks
let mut remaining_chunks = num_chunks;
let mut input_index = 0;
let mut output_index = 0;
{
let length_of_fast_decode_chunks = input.len().saturating_sub(trailing_bytes_to_skip);
// Fast loop, stage 1
// manual unroll to CHUNKS_PER_FAST_LOOP_BLOCK of u64s to amortize slice bounds checks
if let Some(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_BLOCK_LEN) {
while input_index <= max_start_index {
let input_slice = &input[input_index..(input_index + INPUT_BLOCK_LEN)];
let output_slice = &mut output[output_index..(output_index + DECODED_BLOCK_LEN)];
decode_chunk(
&input_slice[0..],
input_index,
decode_table,
&mut output_slice[0..],
)?;
decode_chunk(
&input_slice[8..],
input_index + 8,
decode_table,
&mut output_slice[6..],
)?;
decode_chunk(
&input_slice[16..],
input_index + 16,
decode_table,
&mut output_slice[12..],
)?;
decode_chunk(
&input_slice[24..],
input_index + 24,
decode_table,
&mut output_slice[18..],
)?;
input_index += INPUT_BLOCK_LEN;
output_index += DECODED_BLOCK_LEN - DECODED_CHUNK_SUFFIX;
remaining_chunks -= CHUNKS_PER_FAST_LOOP_BLOCK;
}
}
// Fast loop, stage 2 (aka still pretty fast loop)
// 8 bytes at a time for whatever we didn't do in stage 1.
if let Some(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_CHUNK_LEN) {
while input_index < max_start_index {
decode_chunk(
&input[input_index..(input_index + INPUT_CHUNK_LEN)],
input_index,
decode_table,
&mut output
[output_index..(output_index + DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX)],
)?;
output_index += DECODED_CHUNK_LEN;
input_index += INPUT_CHUNK_LEN;
remaining_chunks -= 1;
}
}
}
// Stage 3
// If input length was such that a chunk had to be deferred until after the fast loop
// because decoding it would have produced 2 trailing bytes that wouldn't then be
// overwritten, we decode that chunk here. This way is slower but doesn't write the 2
// trailing bytes.
// However, we still need to avoid the last chunk (partial or complete) because it could
// have padding, so we always do 1 fewer to avoid the last chunk.
for _ in 1..remaining_chunks {
decode_chunk_precise(
&input[input_index..],
input_index,
decode_table,
&mut output[output_index..(output_index + DECODED_CHUNK_LEN)],
)?;
input_index += INPUT_CHUNK_LEN;
output_index += DECODED_CHUNK_LEN;
}
// always have one more (possibly partial) block of 8 input
debug_assert!(input.len() - input_index > 1 || input.is_empty());
debug_assert!(input.len() - input_index <= 8);
// Stage 4
// Finally, decode any leftovers that aren't a complete input block of 8 bytes.
// Use a u64 as a stack-resident 8 byte buffer.
let mut leftover_bits: u64 = 0;
let mut morsels_in_leftover = 0;
let mut padding_bytes = 0;
let mut first_padding_index: usize = 0;
let mut last_symbol = 0_u8;
let start_of_leftovers = input_index;
for (i, b) in input[start_of_leftovers..].iter().enumerate() {
// '=' padding
if *b == 0x3D {
// There can be bad padding in a few ways:
// 1 - Padding with non-padding characters after it
// 2 - Padding after zero or one non-padding characters before it
// in the current quad.
// 3 - More than two characters of padding. If 3 or 4 padding chars
// are in the same quad, that implies it will be caught by #2.
// If it spreads from one quad to another, it will be caught by
// #2 in the second quad.
if i % 4 < 2 {
// Check for case #2.
let bad_padding_index = start_of_leftovers + if padding_bytes > 0 {
// If we've already seen padding, report the first padding index.
// This is to be consistent with the faster logic above: it will report an
// error on the first padding character (since it doesn't expect to see
// anything but actual encoded data).
first_padding_index
} else {
// haven't seen padding before, just use where we are now
i
};
return Err(DecodeError::InvalidByte(bad_padding_index, *b));
}
if padding_bytes == 0 {
first_padding_index = i;
}
padding_bytes += 1;
continue;
}
// Check for case #1.
// To make '=' handling consistent with the main loop, don't allow
// non-suffix '=' in trailing chunk either. Report error as first
// erroneous padding.
if padding_bytes > 0 {
return Err(DecodeError::InvalidByte(
start_of_leftovers + first_padding_index,
0x3D,
));
}
last_symbol = *b;
// can use up to 8 * 6 = 48 bits of the u64, if last chunk has no padding.
// To minimize shifts, pack the leftovers from left to right.
let shift = 64 - (morsels_in_leftover + 1) * 6;
// tables are all 256 elements, lookup with a u8 index always succeeds
let morsel = decode_table[*b as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(start_of_leftovers + i, *b));
}
leftover_bits |= (morsel as u64) << shift;
morsels_in_leftover += 1;
}
let leftover_bits_ready_to_append = match morsels_in_leftover {
0 => 0,
2 => 8,
3 => 16,
4 => 24,
6 => 32,
7 => 40,
8 => 48,
_ => unreachable!(
"Impossible: must only have 0 to 8 input bytes in last chunk, with no invalid lengths"
),
};
// if there are bits set outside the bits we care about, last symbol encodes trailing bits that
// will not be included in the output
let mask = !0 >> leftover_bits_ready_to_append;
if !config.decode_allow_trailing_bits && (leftover_bits & mask) != 0 {
// last morsel is at `morsels_in_leftover` - 1
return Err(DecodeError::InvalidLastSymbol(
start_of_leftovers + morsels_in_leftover - 1,
last_symbol,
));
}
let mut leftover_bits_appended_to_buf = 0;
while leftover_bits_appended_to_buf < leftover_bits_ready_to_append {
// `as` simply truncates the higher bits, which is what we want here
let selected_bits = (leftover_bits >> (56 - leftover_bits_appended_to_buf)) as u8;
output[output_index] = selected_bits;
output_index += 1;
leftover_bits_appended_to_buf += 8;
}
Ok(output_index)
}
/// Decode 8 bytes of input into 6 bytes of output. 8 bytes of output will be written, but only the
/// first 6 of those contain meaningful data.
///
/// `input` is the bytes to decode, of which the first 8 bytes will be processed.
/// `index_at_start_of_input` is the offset in the overall input (used for reporting errors
/// accurately)
/// `decode_table` is the lookup table for the particular base64 alphabet.
/// `output` will have its first 8 bytes overwritten, of which only the first 6 are valid decoded
/// data.
// yes, really inline (worth 30-50% speedup)
#[inline(always)]
fn decode_chunk(
input: &[u8],
index_at_start_of_input: usize,
decode_table: &[u8; 256],
output: &mut [u8],
) -> Result<(), DecodeError> {
let mut accum: u64;
let morsel = decode_table[input[0] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(index_at_start_of_input, input[0]));
}
accum = (morsel as u64) << 58;
let morsel = decode_table[input[1] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 1,
input[1],
));
}
accum |= (morsel as u64) << 52;
let morsel = decode_table[input[2] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 2,
input[2],
));
}
accum |= (morsel as u64) << 46;
let morsel = decode_table[input[3] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 3,
input[3],
));
}
accum |= (morsel as u64) << 40;
let morsel = decode_table[input[4] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 4,
input[4],
));
}
accum |= (morsel as u64) << 34;
let morsel = decode_table[input[5] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 5,
input[5],
));
}
accum |= (morsel as u64) << 28;
let morsel = decode_table[input[6] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 6,
input[6],
));
}
accum |= (morsel as u64) << 22;
let morsel = decode_table[input[7] as usize];
if morsel == tables::INVALID_VALUE {
return Err(DecodeError::InvalidByte(
index_at_start_of_input + 7,
input[7],
));
}
accum |= (morsel as u64) << 16;
BigEndian::write_u64(output, accum);
Ok(())
}
/// Decode an 8-byte chunk, but only write the 6 bytes actually decoded instead of including 2
/// trailing garbage bytes.
#[inline]
fn decode_chunk_precise(
input: &[u8],
index_at_start_of_input: usize,
decode_table: &[u8; 256],
output: &mut [u8],
) -> Result<(), DecodeError> {
let mut tmp_buf = [0_u8; 8];
decode_chunk(
input,
index_at_start_of_input,
decode_table,
&mut tmp_buf[..],
)?;
output[0..6].copy_from_slice(&tmp_buf[0..6]);
Ok(())
}
#[cfg(test)]
mod tests {
extern crate rand;
use super::*;
use encode::encode_config_buf;
use tests::{assert_encode_sanity, random_config};
use self::rand::distributions::{Distribution, Uniform};
use self::rand::{FromEntropy, Rng};
#[test]
fn decode_chunk_precise_writes_only_6_bytes() {
let input = b"Zm9vYmFy"; // "foobar"
let mut output = [0_u8, 1, 2, 3, 4, 5, 6, 7];
decode_chunk_precise(&input[..], 0, tables::STANDARD_DECODE, &mut output).unwrap();
assert_eq!(&vec![b'f', b'o', b'o', b'b', b'a', b'r', 6, 7], &output);
}
#[test]
fn decode_chunk_writes_8_bytes() {
let input = b"Zm9vYmFy"; // "foobar"
let mut output = [0_u8, 1, 2, 3, 4, 5, 6, 7];
decode_chunk(&input[..], 0, tables::STANDARD_DECODE, &mut output).unwrap();
assert_eq!(&vec![b'f', b'o', b'o', b'b', b'a', b'r', 0, 0], &output);
}
#[test]
fn decode_into_nonempty_vec_doesnt_clobber_existing_prefix() {
let mut orig_data = Vec::new();
let mut encoded_data = String::new();
let mut decoded_with_prefix = Vec::new();
let mut decoded_without_prefix = Vec::new();
let mut prefix = Vec::new();
let prefix_len_range = Uniform::new(0, 1000);
let input_len_range = Uniform::new(0, 1000);
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..10_000 {
orig_data.clear();
encoded_data.clear();
decoded_with_prefix.clear();
decoded_without_prefix.clear();
prefix.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
orig_data.push(rng.gen());
}
let config = random_config(&mut rng);
encode_config_buf(&orig_data, config, &mut encoded_data);
assert_encode_sanity(&encoded_data, config, input_len);
let prefix_len = prefix_len_range.sample(&mut rng);
// fill the buf with a prefix
for _ in 0..prefix_len {
prefix.push(rng.gen());
}
decoded_with_prefix.resize(prefix_len, 0);
decoded_with_prefix.copy_from_slice(&prefix);
// decode into the non-empty buf
decode_config_buf(&encoded_data, config, &mut decoded_with_prefix).unwrap();
// also decode into the empty buf
decode_config_buf(&encoded_data, config, &mut decoded_without_prefix).unwrap();
assert_eq!(
prefix_len + decoded_without_prefix.len(),
decoded_with_prefix.len()
);
assert_eq!(orig_data, decoded_without_prefix);
// append plain decode onto prefix
prefix.append(&mut decoded_without_prefix);
assert_eq!(prefix, decoded_with_prefix);
}
}
#[test]
fn decode_into_slice_doesnt_clobber_existing_prefix_or_suffix() {
let mut orig_data = Vec::new();
let mut encoded_data = String::new();
let mut decode_buf = Vec::new();
let mut decode_buf_copy: Vec<u8> = Vec::new();
let input_len_range = Uniform::new(0, 1000);
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..10_000 {
orig_data.clear();
encoded_data.clear();
decode_buf.clear();
decode_buf_copy.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
orig_data.push(rng.gen());
}
let config = random_config(&mut rng);
encode_config_buf(&orig_data, config, &mut encoded_data);
assert_encode_sanity(&encoded_data, config, input_len);
// fill the buffer with random garbage, long enough to have some room before and after
for _ in 0..5000 {
decode_buf.push(rng.gen());
}
// keep a copy for later comparison
decode_buf_copy.extend(decode_buf.iter());
let offset = 1000;
// decode into the non-empty buf
let decode_bytes_written =
decode_config_slice(&encoded_data, config, &mut decode_buf[offset..]).unwrap();
assert_eq!(orig_data.len(), decode_bytes_written);
assert_eq!(
orig_data,
&decode_buf[offset..(offset + decode_bytes_written)]
);
assert_eq!(&decode_buf_copy[0..offset], &decode_buf[0..offset]);
assert_eq!(
&decode_buf_copy[offset + decode_bytes_written..],
&decode_buf[offset + decode_bytes_written..]
);
}
}
#[test]
fn decode_into_slice_fits_in_precisely_sized_slice() {
let mut orig_data = Vec::new();
let mut encoded_data = String::new();
let mut decode_buf = Vec::new();
let input_len_range = Uniform::new(0, 1000);
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..10_000 {
orig_data.clear();
encoded_data.clear();
decode_buf.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
orig_data.push(rng.gen());
}
let config = random_config(&mut rng);
encode_config_buf(&orig_data, config, &mut encoded_data);
assert_encode_sanity(&encoded_data, config, input_len);
decode_buf.resize(input_len, 0);
// decode into the non-empty buf
let decode_bytes_written =
decode_config_slice(&encoded_data, config, &mut decode_buf[..]).unwrap();
assert_eq!(orig_data.len(), decode_bytes_written);
assert_eq!(orig_data, decode_buf);
}
}
#[test]
fn detect_invalid_last_symbol_two_bytes() {
let decode = |input, forgiving| {
decode_config(input, STANDARD.decode_allow_trailing_bits(forgiving))
};
// example from https://github.com/alicemaz/rust-base64/issues/75
assert!(decode("iYU=", false).is_ok());
// trailing 01
assert_eq!(Err(DecodeError::InvalidLastSymbol(2, b'V')), decode("iYV=", false));
assert_eq!(Ok(vec![137, 133]), decode("iYV=", true));
// trailing 10
assert_eq!(Err(DecodeError::InvalidLastSymbol(2, b'W')), decode("iYW=", false));
assert_eq!(Ok(vec![137, 133]), decode("iYV=", true));
// trailing 11
assert_eq!(Err(DecodeError::InvalidLastSymbol(2, b'X')), decode("iYX=", false));
assert_eq!(Ok(vec![137, 133]), decode("iYV=", true));
// also works when there are 2 quads in the last block
assert_eq!(Err(DecodeError::InvalidLastSymbol(6, b'X')), decode("AAAAiYX=", false));
assert_eq!(Ok(vec![0, 0, 0, 137, 133]), decode("AAAAiYX=", true));
}
#[test]
fn detect_invalid_last_symbol_one_byte() {
// 0xFF -> "/w==", so all letters > w, 0-9, and '+', '/' should get InvalidLastSymbol
assert!(decode("/w==").is_ok());
// trailing 01
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'x')), decode("/x=="));
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'z')), decode("/z=="));
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'0')), decode("/0=="));
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'9')), decode("/9=="));
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'+')), decode("/+=="));
assert_eq!(Err(DecodeError::InvalidLastSymbol(1, b'/')), decode("//=="));
// also works when there are 2 quads in the last block
assert_eq!(
Err(DecodeError::InvalidLastSymbol(5, b'x')),
decode("AAAA/x==")
);
}
#[test]
fn detect_invalid_last_symbol_every_possible_three_symbols() {
let mut base64_to_bytes = ::std::collections::HashMap::new();
let mut bytes = [0_u8; 2];
for b1 in 0_u16..256 {
bytes[0] = b1 as u8;
for b2 in 0_u16..256 {
bytes[1] = b2 as u8;
let mut b64 = vec![0_u8; 4];
assert_eq!(4, ::encode_config_slice(&bytes, STANDARD, &mut b64[..]));
let mut v = ::std::vec::Vec::with_capacity(2);
v.extend_from_slice(&bytes[..]);
assert!(base64_to_bytes.insert(b64, v).is_none());
}
}
// every possible combination of symbols must either decode to 2 bytes or get InvalidLastSymbol
let mut symbols = [0_u8; 4];
for &s1 in STANDARD.char_set.encode_table().iter() {
symbols[0] = s1;
for &s2 in STANDARD.char_set.encode_table().iter() {
symbols[1] = s2;
for &s3 in STANDARD.char_set.encode_table().iter() {
symbols[2] = s3;
symbols[3] = b'=';
match base64_to_bytes.get(&symbols[..]) {
Some(bytes) => {
assert_eq!(Ok(bytes.to_vec()), decode_config(&symbols, STANDARD))
}
None => assert_eq!(
Err(DecodeError::InvalidLastSymbol(2, s3)),
decode_config(&symbols[..], STANDARD)
),
}
}
}
}
}
#[test]
fn detect_invalid_last_symbol_every_possible_two_symbols() {
let mut base64_to_bytes = ::std::collections::HashMap::new();
for b in 0_u16..256 {
let mut b64 = vec![0_u8; 4];
assert_eq!(4, ::encode_config_slice(&[b as u8], STANDARD, &mut b64[..]));
let mut v = ::std::vec::Vec::with_capacity(1);
v.push(b as u8);
assert!(base64_to_bytes.insert(b64, v).is_none());
}
// every possible combination of symbols must either decode to 1 byte or get InvalidLastSymbol
let mut symbols = [0_u8; 4];
for &s1 in STANDARD.char_set.encode_table().iter() {
symbols[0] = s1;
for &s2 in STANDARD.char_set.encode_table().iter() {
symbols[1] = s2;
symbols[2] = b'=';
symbols[3] = b'=';
match base64_to_bytes.get(&symbols[..]) {
Some(bytes) => {
assert_eq!(Ok(bytes.to_vec()), decode_config(&symbols, STANDARD))
}
None => assert_eq!(
Err(DecodeError::InvalidLastSymbol(1, s2)),
decode_config(&symbols[..], STANDARD)
),
}
}
}
}
}