use crate::{Config, PAD_BYTE};
#[cfg(any(feature = "alloc", feature = "std", test))]
use crate::{chunked_encoder, STANDARD};
#[cfg(any(feature = "alloc", feature = "std", test))]
use alloc::{string::String, vec};
use core::convert::TryInto;
///Encode arbitrary octets as base64.
///Returns a String.
///Convenience for `encode_config(input, base64::STANDARD);`.
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let b64 = base64::encode(b"hello world");
/// println!("{}", b64);
///}
///```
#[cfg(any(feature = "alloc", feature = "std", test))]
pub fn encode<T: AsRef<[u8]>>(input: T) -> String {
encode_config(input, STANDARD)
}
///Encode arbitrary octets as base64.
///Returns a String.
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let b64 = base64::encode_config(b"hello world~", base64::STANDARD);
/// println!("{}", b64);
///
/// let b64_url = base64::encode_config(b"hello internet~", base64::URL_SAFE);
/// println!("{}", b64_url);
///}
///```
#[cfg(any(feature = "alloc", feature = "std", test))]
pub fn encode_config<T: AsRef<[u8]>>(input: T, config: Config) -> String {
let mut buf = match encoded_size(input.as_ref().len(), config) {
Some(n) => vec![0; n],
None => panic!("integer overflow when calculating buffer size"),
};
encode_with_padding(input.as_ref(), config, buf.len(), &mut buf[..]);
String::from_utf8(buf).expect("Invalid UTF8")
}
///Encode arbitrary octets as base64.
///Writes into the supplied output buffer, which will grow the buffer if needed.
///
///# Example
///
///```rust
///extern crate base64;
///
///fn main() {
/// let mut buf = String::new();
/// base64::encode_config_buf(b"hello world~", base64::STANDARD, &mut buf);
/// println!("{}", buf);
///
/// buf.clear();
/// base64::encode_config_buf(b"hello internet~", base64::URL_SAFE, &mut buf);
/// println!("{}", buf);
///}
///```
#[cfg(any(feature = "alloc", feature = "std", test))]
pub fn encode_config_buf<T: AsRef<[u8]>>(input: T, config: Config, buf: &mut String) {
let input_bytes = input.as_ref();
{
let mut sink = chunked_encoder::StringSink::new(buf);
let encoder = chunked_encoder::ChunkedEncoder::new(config);
encoder
.encode(input_bytes, &mut sink)
.expect("Writing to a String shouldn't fail")
}
}
/// Encode arbitrary octets as base64.
/// Writes into the supplied output buffer.
///
/// This is useful if you wish to avoid allocation entirely (e.g. encoding into a stack-resident
/// or statically-allocated buffer).
///
/// # Panics
///
/// If `output` is too small to hold the encoded version of `input`, a panic will result.
///
/// # Example
///
/// ```rust
/// extern crate base64;
///
/// fn main() {
/// let s = b"hello internet!";
/// let mut buf = Vec::new();
/// // make sure we'll have a slice big enough for base64 + padding
/// buf.resize(s.len() * 4 / 3 + 4, 0);
///
/// let bytes_written = base64::encode_config_slice(s,
/// base64::STANDARD, &mut buf);
///
/// // shorten our vec down to just what was written
/// buf.resize(bytes_written, 0);
///
/// assert_eq!(s, base64::decode(&buf).unwrap().as_slice());
/// }
/// ```
pub fn encode_config_slice<T: AsRef<[u8]>>(input: T, config: Config, output: &mut [u8]) -> usize {
let input_bytes = input.as_ref();
let encoded_size = encoded_size(input_bytes.len(), config)
.expect("usize overflow when calculating buffer size");
let mut b64_output = &mut output[0..encoded_size];
encode_with_padding(&input_bytes, config, encoded_size, &mut b64_output);
encoded_size
}
/// B64-encode and pad (if configured).
///
/// This helper exists to avoid recalculating encoded_size, which is relatively expensive on short
/// inputs.
///
/// `encoded_size` is the encoded size calculated for `input`.
///
/// `output` must be of size `encoded_size`.
///
/// All bytes in `output` will be written to since it is exactly the size of the output.
fn encode_with_padding(input: &[u8], config: Config, encoded_size: usize, output: &mut [u8]) {
debug_assert_eq!(encoded_size, output.len());
let b64_bytes_written = encode_to_slice(input, output, config.char_set.encode_table());
let padding_bytes = if config.pad {
add_padding(input.len(), &mut output[b64_bytes_written..])
} else {
0
};
let encoded_bytes = b64_bytes_written
.checked_add(padding_bytes)
.expect("usize overflow when calculating b64 length");
debug_assert_eq!(encoded_size, encoded_bytes);
}
#[inline]
fn read_u64(s: &[u8]) -> u64 {
u64::from_be_bytes(s[..8].try_into().unwrap())
}
/// Encode input bytes to utf8 base64 bytes. Does not pad.
/// `output` must be long enough to hold the encoded `input` without padding.
/// Returns the number of bytes written.
#[inline]
pub fn encode_to_slice(input: &[u8], output: &mut [u8], encode_table: &[u8; 64]) -> usize {
let mut input_index: usize = 0;
const BLOCKS_PER_FAST_LOOP: usize = 4;
const LOW_SIX_BITS: u64 = 0x3F;
// we read 8 bytes at a time (u64) but only actually consume 6 of those bytes. Thus, we need
// 2 trailing bytes to be available to read..
let last_fast_index = input.len().saturating_sub(BLOCKS_PER_FAST_LOOP * 6 + 2);
let mut output_index = 0;
if last_fast_index > 0 {
while input_index <= last_fast_index {
// Major performance wins from letting the optimizer do the bounds check once, mostly
// on the output side
let input_chunk = &input[input_index..(input_index + (BLOCKS_PER_FAST_LOOP * 6 + 2))];
let output_chunk = &mut output[output_index..(output_index + BLOCKS_PER_FAST_LOOP * 8)];
// Hand-unrolling for 32 vs 16 or 8 bytes produces yields performance about equivalent
// to unsafe pointer code on a Xeon E5-1650v3. 64 byte unrolling was slightly better for
// large inputs but significantly worse for 50-byte input, unsurprisingly. I suspect
// that it's a not uncommon use case to encode smallish chunks of data (e.g. a 64-byte
// SHA-512 digest), so it would be nice if that fit in the unrolled loop at least once.
// Plus, single-digit percentage performance differences might well be quite different
// on different hardware.
let input_u64 = read_u64(&input_chunk[0..]);
output_chunk[0] = encode_table[((input_u64 >> 58) & LOW_SIX_BITS) as usize];
output_chunk[1] = encode_table[((input_u64 >> 52) & LOW_SIX_BITS) as usize];
output_chunk[2] = encode_table[((input_u64 >> 46) & LOW_SIX_BITS) as usize];
output_chunk[3] = encode_table[((input_u64 >> 40) & LOW_SIX_BITS) as usize];
output_chunk[4] = encode_table[((input_u64 >> 34) & LOW_SIX_BITS) as usize];
output_chunk[5] = encode_table[((input_u64 >> 28) & LOW_SIX_BITS) as usize];
output_chunk[6] = encode_table[((input_u64 >> 22) & LOW_SIX_BITS) as usize];
output_chunk[7] = encode_table[((input_u64 >> 16) & LOW_SIX_BITS) as usize];
let input_u64 = read_u64(&input_chunk[6..]);
output_chunk[8] = encode_table[((input_u64 >> 58) & LOW_SIX_BITS) as usize];
output_chunk[9] = encode_table[((input_u64 >> 52) & LOW_SIX_BITS) as usize];
output_chunk[10] = encode_table[((input_u64 >> 46) & LOW_SIX_BITS) as usize];
output_chunk[11] = encode_table[((input_u64 >> 40) & LOW_SIX_BITS) as usize];
output_chunk[12] = encode_table[((input_u64 >> 34) & LOW_SIX_BITS) as usize];
output_chunk[13] = encode_table[((input_u64 >> 28) & LOW_SIX_BITS) as usize];
output_chunk[14] = encode_table[((input_u64 >> 22) & LOW_SIX_BITS) as usize];
output_chunk[15] = encode_table[((input_u64 >> 16) & LOW_SIX_BITS) as usize];
let input_u64 = read_u64(&input_chunk[12..]);
output_chunk[16] = encode_table[((input_u64 >> 58) & LOW_SIX_BITS) as usize];
output_chunk[17] = encode_table[((input_u64 >> 52) & LOW_SIX_BITS) as usize];
output_chunk[18] = encode_table[((input_u64 >> 46) & LOW_SIX_BITS) as usize];
output_chunk[19] = encode_table[((input_u64 >> 40) & LOW_SIX_BITS) as usize];
output_chunk[20] = encode_table[((input_u64 >> 34) & LOW_SIX_BITS) as usize];
output_chunk[21] = encode_table[((input_u64 >> 28) & LOW_SIX_BITS) as usize];
output_chunk[22] = encode_table[((input_u64 >> 22) & LOW_SIX_BITS) as usize];
output_chunk[23] = encode_table[((input_u64 >> 16) & LOW_SIX_BITS) as usize];
let input_u64 = read_u64(&input_chunk[18..]);
output_chunk[24] = encode_table[((input_u64 >> 58) & LOW_SIX_BITS) as usize];
output_chunk[25] = encode_table[((input_u64 >> 52) & LOW_SIX_BITS) as usize];
output_chunk[26] = encode_table[((input_u64 >> 46) & LOW_SIX_BITS) as usize];
output_chunk[27] = encode_table[((input_u64 >> 40) & LOW_SIX_BITS) as usize];
output_chunk[28] = encode_table[((input_u64 >> 34) & LOW_SIX_BITS) as usize];
output_chunk[29] = encode_table[((input_u64 >> 28) & LOW_SIX_BITS) as usize];
output_chunk[30] = encode_table[((input_u64 >> 22) & LOW_SIX_BITS) as usize];
output_chunk[31] = encode_table[((input_u64 >> 16) & LOW_SIX_BITS) as usize];
output_index += BLOCKS_PER_FAST_LOOP * 8;
input_index += BLOCKS_PER_FAST_LOOP * 6;
}
}
// Encode what's left after the fast loop.
const LOW_SIX_BITS_U8: u8 = 0x3F;
let rem = input.len() % 3;
let start_of_rem = input.len() - rem;
// start at the first index not handled by fast loop, which may be 0.
while input_index < start_of_rem {
let input_chunk = &input[input_index..(input_index + 3)];
let output_chunk = &mut output[output_index..(output_index + 4)];
output_chunk[0] = encode_table[(input_chunk[0] >> 2) as usize];
output_chunk[1] =
encode_table[((input_chunk[0] << 4 | input_chunk[1] >> 4) & LOW_SIX_BITS_U8) as usize];
output_chunk[2] =
encode_table[((input_chunk[1] << 2 | input_chunk[2] >> 6) & LOW_SIX_BITS_U8) as usize];
output_chunk[3] = encode_table[(input_chunk[2] & LOW_SIX_BITS_U8) as usize];
input_index += 3;
output_index += 4;
}
if rem == 2 {
output[output_index] = encode_table[(input[start_of_rem] >> 2) as usize];
output[output_index + 1] = encode_table[((input[start_of_rem] << 4
| input[start_of_rem + 1] >> 4)
& LOW_SIX_BITS_U8) as usize];
output[output_index + 2] =
encode_table[((input[start_of_rem + 1] << 2) & LOW_SIX_BITS_U8) as usize];
output_index += 3;
} else if rem == 1 {
output[output_index] = encode_table[(input[start_of_rem] >> 2) as usize];
output[output_index + 1] =
encode_table[((input[start_of_rem] << 4) & LOW_SIX_BITS_U8) as usize];
output_index += 2;
}
output_index
}
/// calculate the base64 encoded string size, including padding if appropriate
pub fn encoded_size(bytes_len: usize, config: Config) -> Option<usize> {
let rem = bytes_len % 3;
let complete_input_chunks = bytes_len / 3;
let complete_chunk_output = complete_input_chunks.checked_mul(4);
if rem > 0 {
if config.pad {
complete_chunk_output.and_then(|c| c.checked_add(4))
} else {
let encoded_rem = match rem {
1 => 2,
2 => 3,
_ => unreachable!("Impossible remainder"),
};
complete_chunk_output.and_then(|c| c.checked_add(encoded_rem))
}
} else {
complete_chunk_output
}
}
/// Write padding characters.
/// `output` is the slice where padding should be written, of length at least 2.
///
/// Returns the number of padding bytes written.
pub fn add_padding(input_len: usize, output: &mut [u8]) -> usize {
let rem = input_len % 3;
let mut bytes_written = 0;
for _ in 0..((3 - rem) % 3) {
output[bytes_written] = PAD_BYTE;
bytes_written += 1;
}
bytes_written
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{
decode::decode_config_buf,
tests::{assert_encode_sanity, random_config},
Config, STANDARD, URL_SAFE_NO_PAD,
};
use rand::{
distributions::{Distribution, Uniform},
FromEntropy, Rng,
};
use std;
use std::str;
#[test]
fn encoded_size_correct_standard() {
assert_encoded_length(0, 0, STANDARD);
assert_encoded_length(1, 4, STANDARD);
assert_encoded_length(2, 4, STANDARD);
assert_encoded_length(3, 4, STANDARD);
assert_encoded_length(4, 8, STANDARD);
assert_encoded_length(5, 8, STANDARD);
assert_encoded_length(6, 8, STANDARD);
assert_encoded_length(7, 12, STANDARD);
assert_encoded_length(8, 12, STANDARD);
assert_encoded_length(9, 12, STANDARD);
assert_encoded_length(54, 72, STANDARD);
assert_encoded_length(55, 76, STANDARD);
assert_encoded_length(56, 76, STANDARD);
assert_encoded_length(57, 76, STANDARD);
assert_encoded_length(58, 80, STANDARD);
}
#[test]
fn encoded_size_correct_no_pad() {
assert_encoded_length(0, 0, URL_SAFE_NO_PAD);
assert_encoded_length(1, 2, URL_SAFE_NO_PAD);
assert_encoded_length(2, 3, URL_SAFE_NO_PAD);
assert_encoded_length(3, 4, URL_SAFE_NO_PAD);
assert_encoded_length(4, 6, URL_SAFE_NO_PAD);
assert_encoded_length(5, 7, URL_SAFE_NO_PAD);
assert_encoded_length(6, 8, URL_SAFE_NO_PAD);
assert_encoded_length(7, 10, URL_SAFE_NO_PAD);
assert_encoded_length(8, 11, URL_SAFE_NO_PAD);
assert_encoded_length(9, 12, URL_SAFE_NO_PAD);
assert_encoded_length(54, 72, URL_SAFE_NO_PAD);
assert_encoded_length(55, 74, URL_SAFE_NO_PAD);
assert_encoded_length(56, 75, URL_SAFE_NO_PAD);
assert_encoded_length(57, 76, URL_SAFE_NO_PAD);
assert_encoded_length(58, 78, URL_SAFE_NO_PAD);
}
#[test]
fn encoded_size_overflow() {
assert_eq!(None, encoded_size(std::usize::MAX, STANDARD));
}
#[test]
fn encode_config_buf_into_nonempty_buffer_doesnt_clobber_prefix() {
let mut orig_data = Vec::new();
let mut prefix = String::new();
let mut encoded_data_no_prefix = String::new();
let mut encoded_data_with_prefix = String::new();
let mut decoded = 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();
prefix.clear();
encoded_data_no_prefix.clear();
encoded_data_with_prefix.clear();
decoded.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
orig_data.push(rng.gen());
}
let prefix_len = prefix_len_range.sample(&mut rng);
for _ in 0..prefix_len {
// getting convenient random single-byte printable chars that aren't base64 is
// annoying
prefix.push('#');
}
encoded_data_with_prefix.push_str(&prefix);
let config = random_config(&mut rng);
encode_config_buf(&orig_data, config, &mut encoded_data_no_prefix);
encode_config_buf(&orig_data, config, &mut encoded_data_with_prefix);
assert_eq!(
encoded_data_no_prefix.len() + prefix_len,
encoded_data_with_prefix.len()
);
assert_encode_sanity(&encoded_data_no_prefix, config, input_len);
assert_encode_sanity(&encoded_data_with_prefix[prefix_len..], config, input_len);
// append plain encode onto prefix
prefix.push_str(&mut encoded_data_no_prefix);
assert_eq!(prefix, encoded_data_with_prefix);
decode_config_buf(&encoded_data_no_prefix, config, &mut decoded).unwrap();
assert_eq!(orig_data, decoded);
}
}
#[test]
fn encode_config_slice_into_nonempty_buffer_doesnt_clobber_suffix() {
let mut orig_data = Vec::new();
let mut encoded_data = Vec::new();
let mut encoded_data_original_state = Vec::new();
let mut decoded = 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();
encoded_data_original_state.clear();
decoded.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
orig_data.push(rng.gen());
}
// plenty of existing garbage in the encoded buffer
for _ in 0..10 * input_len {
encoded_data.push(rng.gen());
}
encoded_data_original_state.extend_from_slice(&encoded_data);
let config = random_config(&mut rng);
let encoded_size = encoded_size(input_len, config).unwrap();
assert_eq!(
encoded_size,
encode_config_slice(&orig_data, config, &mut encoded_data)
);
assert_encode_sanity(
std::str::from_utf8(&encoded_data[0..encoded_size]).unwrap(),
config,
input_len,
);
assert_eq!(
&encoded_data[encoded_size..],
&encoded_data_original_state[encoded_size..]
);
decode_config_buf(&encoded_data[0..encoded_size], config, &mut decoded).unwrap();
assert_eq!(orig_data, decoded);
}
}
#[test]
fn encode_config_slice_fits_into_precisely_sized_slice() {
let mut orig_data = Vec::new();
let mut encoded_data = Vec::new();
let mut decoded = 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();
decoded.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);
let encoded_size = encoded_size(input_len, config).unwrap();
encoded_data.resize(encoded_size, 0);
assert_eq!(
encoded_size,
encode_config_slice(&orig_data, config, &mut encoded_data)
);
assert_encode_sanity(
std::str::from_utf8(&encoded_data[0..encoded_size]).unwrap(),
config,
input_len,
);
decode_config_buf(&encoded_data[0..encoded_size], config, &mut decoded).unwrap();
assert_eq!(orig_data, decoded);
}
}
#[test]
fn encode_to_slice_random_valid_utf8() {
let mut input = Vec::new();
let mut output = Vec::new();
let input_len_range = Uniform::new(0, 1000);
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..10_000 {
input.clear();
output.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
input.push(rng.gen());
}
let config = random_config(&mut rng);
// fill up the output buffer with garbage
let encoded_size = encoded_size(input_len, config).unwrap();
for _ in 0..encoded_size {
output.push(rng.gen());
}
let orig_output_buf = output.to_vec();
let bytes_written =
encode_to_slice(&input, &mut output, config.char_set.encode_table());
// make sure the part beyond bytes_written is the same garbage it was before
assert_eq!(orig_output_buf[bytes_written..], output[bytes_written..]);
// make sure the encoded bytes are UTF-8
let _ = str::from_utf8(&output[0..bytes_written]).unwrap();
}
}
#[test]
fn encode_with_padding_random_valid_utf8() {
let mut input = Vec::new();
let mut output = Vec::new();
let input_len_range = Uniform::new(0, 1000);
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..10_000 {
input.clear();
output.clear();
let input_len = input_len_range.sample(&mut rng);
for _ in 0..input_len {
input.push(rng.gen());
}
let config = random_config(&mut rng);
// fill up the output buffer with garbage
let encoded_size = encoded_size(input_len, config).unwrap();
for _ in 0..encoded_size + 1000 {
output.push(rng.gen());
}
let orig_output_buf = output.to_vec();
encode_with_padding(&input, config, encoded_size, &mut output[0..encoded_size]);
// make sure the part beyond b64 is the same garbage it was before
assert_eq!(orig_output_buf[encoded_size..], output[encoded_size..]);
// make sure the encoded bytes are UTF-8
let _ = str::from_utf8(&output[0..encoded_size]).unwrap();
}
}
#[test]
fn add_padding_random_valid_utf8() {
let mut output = Vec::new();
let mut rng = rand::rngs::SmallRng::from_entropy();
// cover our bases for length % 3
for input_len in 0..10 {
output.clear();
// fill output with random
for _ in 0..10 {
output.push(rng.gen());
}
let orig_output_buf = output.to_vec();
let bytes_written = add_padding(input_len, &mut output);
// make sure the part beyond bytes_written is the same garbage it was before
assert_eq!(orig_output_buf[bytes_written..], output[bytes_written..]);
// make sure the encoded bytes are UTF-8
let _ = str::from_utf8(&output[0..bytes_written]).unwrap();
}
}
fn assert_encoded_length(input_len: usize, encoded_len: usize, config: Config) {
assert_eq!(encoded_len, encoded_size(input_len, config).unwrap());
let mut bytes: Vec<u8> = Vec::new();
let mut rng = rand::rngs::SmallRng::from_entropy();
for _ in 0..input_len {
bytes.push(rng.gen());
}
let encoded = encode_config(&bytes, config);
assert_encode_sanity(&encoded, config, input_len);
assert_eq!(encoded_len, encoded.len());
}
#[test]
fn encode_imap() {
assert_eq!(
encode_config(b"\xFB\xFF", crate::IMAP_MUTF7),
encode_config(b"\xFB\xFF", crate::STANDARD_NO_PAD).replace("/", ",")
);
}
}
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