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extern crate byteorder;
use std::{fmt, error, str};
use byteorder::{BigEndian, ByteOrder};
mod tables;
#[derive(Clone, Copy, Debug)]
pub enum CharacterSet {
Standard,
UrlSafe
}
#[derive(Clone, Copy, Debug)]
pub struct Config {
pub char_set: CharacterSet,
pub pad: bool,
}
pub static STANDARD: Config = Config {char_set: CharacterSet::Standard, pad: true};
pub static URL_SAFE: Config = Config {char_set: CharacterSet::UrlSafe, pad: true};
pub static URL_SAFE_NO_PAD: Config = Config {char_set: CharacterSet::UrlSafe, pad: false};
#[derive(Debug, PartialEq, Eq)]
pub enum Base64Error {
Utf8(str::Utf8Error),
InvalidByte(usize, u8),
InvalidLength,
}
impl fmt::Display for Base64Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Base64Error::Utf8(ref err) => err.fmt(f),
Base64Error::InvalidByte(index, byte) =>
write!(f, "Invalid byte {}, offset {}.", byte, index),
Base64Error::InvalidLength =>
write!(f, "Encoded text cannot have a 6-bit remainder.")
}
}
}
impl error::Error for Base64Error {
fn description(&self) -> &str {
match *self {
Base64Error::Utf8(ref err) => err.description(),
Base64Error::InvalidByte(_,_) => "invalid byte",
Base64Error::InvalidLength => "invalid length"
}
}
fn cause(&self) -> Option<&error::Error> {
match *self {
Base64Error::Utf8(ref err) => Some(err as &error::Error),
_ => None
}
}
}
impl From<str::Utf8Error> for Base64Error {
fn from(err: str::Utf8Error) -> Base64Error {
Base64Error::Utf8(err)
}
}
pub fn encode(input: &[u8]) -> String {
encode_config(input, STANDARD)
}
pub fn decode<T: ?Sized + AsRef<[u8]>>(input: &T) -> Result<Vec<u8>, Base64Error> {
decode_config(input, STANDARD)
}
pub fn decode_ws(input: &str) -> Result<Vec<u8>, Base64Error> {
let mut raw = Vec::<u8>::with_capacity(input.len());
raw.extend(input.bytes().filter(|b| !b" \n\t\r\x0c".contains(b)));
let sans_ws = String::from_utf8(raw).unwrap();
decode_config(&sans_ws, STANDARD)
}
pub fn encode_config(input: &[u8], config: Config) -> String {
let mut buf = String::with_capacity(encoded_size(input.len()));
encode_config_buf(input, config, &mut buf);
buf
}
fn encoded_size(bytes_len: usize) -> usize {
let rem = bytes_len % 3;
let complete_input_chunks = bytes_len / 3;
let complete_output_chars = complete_input_chunks * 4;
let leftover_output_chars = if rem == 0 {
0
} else {
4
};
return complete_output_chars + leftover_output_chars;
}
pub fn encode_config_buf(input: &[u8], config: Config, buf: &mut String) {
let ref charset = match config.char_set {
CharacterSet::Standard => tables::STANDARD_ENCODE,
CharacterSet::UrlSafe => tables::URL_SAFE_ENCODE,
};
buf.reserve(encoded_size(input.len()));
let orig_buf_len = buf.len();
let mut fast_loop_output_buf_len = orig_buf_len;
let input_chunk_len = 6;
let last_fast_index = input.len().saturating_sub(8);
let mut raw = unsafe { buf.as_mut_vec() };
let mut output_ptr = unsafe { raw.as_mut_ptr().offset(orig_buf_len as isize) };
let mut input_index: usize = 0;
if input.len() >= 8 {
while input_index <= last_fast_index {
let input_chunk = BigEndian::read_u64(&input[input_index..(input_index + 8)]);
unsafe {
std::ptr::write(output_ptr, charset[((input_chunk >> 58) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(1), charset[((input_chunk >> 52) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(2), charset[((input_chunk >> 46) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(3), charset[((input_chunk >> 40) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(4), charset[((input_chunk >> 34) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(5), charset[((input_chunk >> 28) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(6), charset[((input_chunk >> 22) & 0x3F) as usize]);
std::ptr::write(output_ptr.offset(7), charset[((input_chunk >> 16) & 0x3F) as usize]);
output_ptr = output_ptr.offset(8);
}
input_index += input_chunk_len;
fast_loop_output_buf_len += 8;
}
}
unsafe {
raw.set_len(fast_loop_output_buf_len);
}
let rem = input.len() % 3;
let start_of_rem = input.len() - rem;
let mut leftover_index = input_index;
while leftover_index < start_of_rem {
raw.push(charset[(input[leftover_index] >> 2) as usize]);
raw.push(charset[((input[leftover_index] << 4 | input[leftover_index + 1] >> 4) & 0x3f) as usize]);
raw.push(charset[((input[leftover_index + 1] << 2 | input[leftover_index + 2] >> 6) & 0x3f) as usize]);
raw.push(charset[(input[leftover_index + 2] & 0x3f) as usize]);
leftover_index += 3;
}
if rem == 2 {
raw.push(charset[(input[start_of_rem] >> 2) as usize]);
raw.push(charset[((input[start_of_rem] << 4 | input[start_of_rem + 1] >> 4) & 0x3f) as usize]);
raw.push(charset[(input[start_of_rem + 1] << 2 & 0x3f) as usize]);
} else if rem == 1 {
raw.push(charset[(input[start_of_rem] >> 2) as usize]);
raw.push(charset[(input[start_of_rem] << 4 & 0x3f) as usize]);
}
if config.pad {
for _ in 0..((3 - rem) % 3) {
raw.push(0x3d);
}
}
}
pub fn decode_config<T: ?Sized + AsRef<[u8]>>(input: &T, config: Config) -> Result<Vec<u8>, Base64Error> {
let mut buffer = Vec::<u8>::with_capacity(input.as_ref().len() * 4 / 3);
decode_config_buf(input, config, &mut buffer).map(|_| buffer)
}
pub fn decode_config_buf<T: ?Sized + AsRef<[u8]>>(input: &T,
config: Config,
buffer: &mut Vec<u8>)
-> Result<(), Base64Error> {
let input_bytes = input.as_ref();
let ref decode_table = match config.char_set {
CharacterSet::Standard => tables::STANDARD_DECODE,
CharacterSet::UrlSafe => tables::URL_SAFE_DECODE,
};
buffer.reserve(input_bytes.len() * 3 / 4);
let chunk_len = 8;
let decoded_chunk_len = 6;
let remainder_len = input_bytes.len() % chunk_len;
let trailing_bytes_to_skip = if remainder_len == 0 {
chunk_len
} else {
remainder_len
};
let length_of_full_chunks = input_bytes.len().saturating_sub(trailing_bytes_to_skip);
let starting_output_index = buffer.len();
let new_size = starting_output_index
+ length_of_full_chunks / chunk_len * decoded_chunk_len
+ (chunk_len - decoded_chunk_len);
buffer.resize(new_size, 0);
let mut output_index = starting_output_index;
{
let buffer_slice = buffer.as_mut_slice();
let mut input_index = 0;
let mut bad_byte_index: usize = 0;
let mut morsel: u8 = 0;
while input_index < length_of_full_chunks {
let mut accum: u64;
let input_chunk = BigEndian::read_u64(&input_bytes[input_index..(input_index + 8)]);
morsel = decode_table[(input_chunk >> 56) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index;
break;
};
accum = (morsel as u64) << 58;
morsel = decode_table[(input_chunk >> 48 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 1;
break;
};
accum |= (morsel as u64) << 52;
morsel = decode_table[(input_chunk >> 40 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 2;
break;
};
accum |= (morsel as u64) << 46;
morsel = decode_table[(input_chunk >> 32 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 3;
break;
};
accum |= (morsel as u64) << 40;
morsel = decode_table[(input_chunk >> 24 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 4;
break;
};
accum |= (morsel as u64) << 34;
morsel = decode_table[(input_chunk >> 16 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 5;
break;
};
accum |= (morsel as u64) << 28;
morsel = decode_table[(input_chunk >> 8 & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 6;
break;
};
accum |= (morsel as u64) << 22;
morsel = decode_table[(input_chunk & 0xFF) as usize];
if morsel == tables::INVALID_VALUE {
bad_byte_index = input_index + 7;
break;
};
accum |= (morsel as u64) << 16;
BigEndian::write_u64(&mut buffer_slice[(output_index)..(output_index + 8)],
accum);
output_index += 6;
input_index += chunk_len;
};
if morsel == tables::INVALID_VALUE {
return Err(Base64Error::InvalidByte(bad_byte_index, input_bytes[bad_byte_index]));
}
}
let new_len = buffer.len() - (chunk_len - decoded_chunk_len);
buffer.truncate(new_len);
let mut leftover_bits: u64 = 0;
let mut morsels_in_leftover = 0;
let mut padding_bytes = 0;
let mut first_padding_index: usize = 0;
for (i, b) in input_bytes[length_of_full_chunks..].iter().enumerate() {
if *b == 0x3D {
if i % 4 < 2 {
return Err(Base64Error::InvalidByte(length_of_full_chunks + i, *b));
};
if padding_bytes == 0 {
first_padding_index = i;
};
padding_bytes += 1;
continue;
};
if padding_bytes > 0 {
return Err(Base64Error::InvalidByte(
length_of_full_chunks + first_padding_index, 0x3D));
};
let shift = 64 - (morsels_in_leftover + 1) * 6;
let morsel = decode_table[*b as usize];
if morsel == tables::INVALID_VALUE {
return Err(Base64Error::InvalidByte(length_of_full_chunks + i, *b));
};
leftover_bits |= (morsel as u64) << shift;
morsels_in_leftover += 1;
};
let leftover_bits_ready_to_append = match morsels_in_leftover {
0 => 0,
1 => return Err(Base64Error::InvalidLength),
2 => 8,
3 => 16,
4 => 24,
5 => return Err(Base64Error::InvalidLength),
6 => 32,
7 => 40,
8 => 48,
_ => panic!("Impossible: must only have 0 to 4 input bytes in last quad")
};
let mut leftover_bits_appended_to_buf = 0;
while leftover_bits_appended_to_buf < leftover_bits_ready_to_append {
let selected_bits = (leftover_bits >> (56 - leftover_bits_appended_to_buf)) as u8;
buffer.push(selected_bits);
leftover_bits_appended_to_buf += 8;
};
Ok(())
}
#[cfg(test)]
mod tests {
use super::encoded_size;
#[test]
fn encoded_size_correct() {
assert_eq!(0, encoded_size(0));
assert_eq!(4, encoded_size(1));
assert_eq!(4, encoded_size(2));
assert_eq!(4, encoded_size(3));
assert_eq!(8, encoded_size(4));
assert_eq!(8, encoded_size(5));
assert_eq!(8, encoded_size(6));
assert_eq!(12, encoded_size(7));
assert_eq!(12, encoded_size(8));
assert_eq!(12, encoded_size(9));
}
}