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Diffstat (limited to 'third_party/rust/base64/src/decode.rs')
| -rw-r--r-- | third_party/rust/base64/src/decode.rs | 893 |
1 files changed, 893 insertions, 0 deletions
diff --git a/third_party/rust/base64/src/decode.rs b/third_party/rust/base64/src/decode.rs new file mode 100644 index 0000000000..e349240ac7 --- /dev/null +++ b/third_party/rust/base64/src/decode.rs @@ -0,0 +1,893 @@ +use crate::{tables, Config, PAD_BYTE}; + +#[cfg(any(feature = "alloc", feature = "std", test))] +use crate::STANDARD; +#[cfg(any(feature = "alloc", feature = "std", test))] +use alloc::vec::Vec; +use core::fmt; +#[cfg(any(feature = "std", test))] +use std::error; + +// 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. + /// A typical cause of this is stray trailing whitespace or other separator bytes. + /// In the case where excess trailing bytes have produced an invalid length *and* the last byte + /// is also an invalid base64 symbol (as would be the case for whitespace, etc), `InvalidByte` + /// will be emitted instead of `InvalidLength` to make the issue easier to debug. + 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) + } + } + } +} + +#[cfg(any(feature = "std", test))] +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<&dyn 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); +///} +///``` +#[cfg(any(feature = "alloc", feature = "std", test))] +pub fn decode<T: 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); +///} +///``` +#[cfg(any(feature = "alloc", feature = "std", test))] +pub fn decode_config<T: AsRef<[u8]>>(input: T, config: Config) -> Result<Vec<u8>, DecodeError> { + let decoded_length_estimate = (input + .as_ref() + .len() + .checked_add(3) + .expect("decoded length calculation overflow")) + / 4 + * 3; + let mut buffer = Vec::<u8>::with_capacity(decoded_length_estimate); + + 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); +///} +///``` +#[cfg(any(feature = "alloc", feature = "std", test))] +pub fn decode_config_buf<T: 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: 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 => { + // trailing whitespace is so common that it's worth it to check the last byte to + // possibly return a better error message + if let Some(b) = input.last() { + if *b != PAD_BYTE && decode_table[*b as usize] == tables::INVALID_VALUE { + return Err(DecodeError::InvalidByte(input.len() - 1, *b)); + } + } + + 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 == PAD_BYTE { + // 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, + PAD_BYTE, + )); + } + 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) +} + +#[inline] +fn write_u64(output: &mut [u8], value: u64) { + output[..8].copy_from_slice(&value.to_be_bytes()); +} + +/// 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; + + 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 { + use super::*; + use crate::{ + encode::encode_config_buf, + encode::encode_config_slice, + tests::{assert_encode_sanity, random_config}, + }; + + use rand::{ + distributions::{Distribution, Uniform}, + 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/marshallpierce/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] = PAD_BYTE; + + 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] = PAD_BYTE; + symbols[3] = PAD_BYTE; + + 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) + ), + } + } + } + } + + #[test] + fn decode_config_estimation_works_for_various_lengths() { + for num_prefix_quads in 0..100 { + for suffix in &["AA", "AAA", "AAAA"] { + let mut prefix = "AAAA".repeat(num_prefix_quads); + prefix.push_str(suffix); + // make sure no overflow (and thus a panic) occurs + let res = decode_config(prefix, STANDARD); + assert!(res.is_ok()); + } + } + } +} |