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bincode
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Feature/config limit (#439) 

* Added Limit<N> and NoLimit to the configuration
* Added a limit check to Decoder and DecoderImpl
* Added test cases, added a helper function specialized for containers
* Added a test to see if inlining makes the limit config faster, added inlining to the decoder
This commit is contained in:
Trangar 2021-12-11 15:44:43 +01:00 committed by GitHub
parent ed57fd0810
commit 63f4607992
10 changed files with 287 additions and 15 deletions
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4
Cargo.toml
View File

@ -50,6 +50,10 @@ rand = "0.8"
name = "varint"
harness = false
[[bench]]
name = "inline"
harness = false
[profile.bench]
codegen-units = 1
debug = 1

18
benches/inline.rs Normal file
View File

@ -0,0 +1,18 @@
use criterion::{black_box, criterion_group, criterion_main, Criterion};
use bincode::config::Configuration;
fn inline_decoder_claim_bytes_read(c: &mut Criterion) {
let config = Configuration::standard().with_limit::<100000>();
let slice = bincode::encode_to_vec(vec![String::from("Hello world"); 1000], config).unwrap();
c.bench_function("inline_decoder_claim_bytes_read", |b| {
b.iter(|| {
let _: Vec<String> =
black_box(bincode::decode_from_slice(black_box(&slice), config).unwrap());
})
});
}
criterion_group!(benches, inline_decoder_claim_bytes_read);
criterion_main!(benches);

66
src/config.rs
View File

@ -40,10 +40,11 @@ use core::marker::PhantomData;
/// [skip_fixed_array_length]: #method.skip_fixed_array_length
/// [write_fixed_array_length]: #method.write_fixed_array_length
#[derive(Copy, Clone)]
pub struct Configuration<E = LittleEndian, I = Varint, A = SkipFixedArrayLength> {
pub struct Configuration<E = LittleEndian, I = Varint, A = SkipFixedArrayLength, L = NoLimit> {
_e: PhantomData<E>,
_i: PhantomData<I>,
_a: PhantomData<A>,
_l: PhantomData<L>,
}
impl Configuration {
@ -59,17 +60,18 @@ impl Configuration {
/// - Little endian
/// - Fixed int length encoding
/// - Write array lengths
pub fn legacy() -> Configuration<LittleEndian, Fixint, WriteFixedArrayLength> {
pub fn legacy() -> Configuration<LittleEndian, Fixint, WriteFixedArrayLength, NoLimit> {
Self::generate()
}
}
impl<E, I, A> Configuration<E, I, A> {
fn generate<_E, _I, _A>() -> Configuration<_E, _I, _A> {
impl<E, I, A, L> Configuration<E, I, A, L> {
fn generate<_E, _I, _A, _L>() -> Configuration<_E, _I, _A, _L> {
Configuration {
_e: PhantomData,
_i: PhantomData,
_a: PhantomData,
_l: PhantomData,
}
}
@ -162,16 +164,36 @@ impl<E, I, A> Configuration<E, I, A> {
pub fn write_fixed_array_length(self) -> Configuration<E, I, WriteFixedArrayLength> {
Self::generate()
}
/// Sets the byte limit to `limit`.
pub fn with_limit<const N: usize>(self) -> Configuration<E, I, A, Limit<N>> {
Self::generate()
}
/// Clear the byte limit.
pub fn with_no_limit(self) -> Configuration<E, I, A, NoLimit> {
Self::generate()
}
}
/// Indicates a type is valid for controlling the bincode configuration
pub trait Config:
InternalEndianConfig + InternalArrayLengthConfig + InternalIntEncodingConfig + Copy + Clone
InternalEndianConfig
+ InternalArrayLengthConfig
+ InternalIntEncodingConfig
+ InternalLimitConfig
+ Copy
+ Clone
{
}
impl<T> Config for T where
T: InternalEndianConfig + InternalArrayLengthConfig + InternalIntEncodingConfig + Copy + Clone
T: InternalEndianConfig
+ InternalArrayLengthConfig
+ InternalIntEncodingConfig
+ InternalLimitConfig
+ Copy
+ Clone
{
}
@ -223,6 +245,20 @@ impl InternalArrayLengthConfig for WriteFixedArrayLength {
const SKIP_FIXED_ARRAY_LENGTH: bool = false;
}
#[doc(hidden)]
#[derive(Copy, Clone)]
pub struct NoLimit {}
impl InternalLimitConfig for NoLimit {
const LIMIT: Option<usize> = None;
}
#[doc(hidden)]
#[derive(Copy, Clone)]
pub struct Limit<const N: usize> {}
impl<const N: usize> InternalLimitConfig for Limit<N> {
const LIMIT: Option<usize> = Some(N);
}
mod internal {
use super::Configuration;
@ -230,7 +266,7 @@ mod internal {
const ENDIAN: Endian;
}
impl<E: InternalEndianConfig, I, A> InternalEndianConfig for Configuration<E, I, A> {
impl<E: InternalEndianConfig, I, A, L> InternalEndianConfig for Configuration<E, I, A, L> {
const ENDIAN: Endian = E::ENDIAN;
}
@ -244,7 +280,9 @@ mod internal {
const INT_ENCODING: IntEncoding;
}
impl<E, I: InternalIntEncodingConfig, A> InternalIntEncodingConfig for Configuration<E, I, A> {
impl<E, I: InternalIntEncodingConfig, A, L> InternalIntEncodingConfig
for Configuration<E, I, A, L>
{
const INT_ENCODING: IntEncoding = I::INT_ENCODING;
}
@ -258,7 +296,17 @@ mod internal {
const SKIP_FIXED_ARRAY_LENGTH: bool;
}
impl<E, I, A: InternalArrayLengthConfig> InternalArrayLengthConfig for Configuration<E, I, A> {
impl<E, I, A: InternalArrayLengthConfig, L> InternalArrayLengthConfig
for Configuration<E, I, A, L>
{
const SKIP_FIXED_ARRAY_LENGTH: bool = A::SKIP_FIXED_ARRAY_LENGTH;
}
pub trait InternalLimitConfig {
const LIMIT: Option<usize>;
}
impl<E, I, A, L: InternalLimitConfig> InternalLimitConfig for Configuration<E, I, A, L> {
const LIMIT: Option<usize> = L::LIMIT;
}
}

37
src/de/decoder.rs
View File

@ -2,7 +2,7 @@ use super::{
read::{BorrowReader, Reader},
BorrowDecoder, Decoder,
};
use crate::{config::Config, utils::Sealed};
use crate::{config::Config, error::DecodeError, utils::Sealed};
/// A Decoder that reads bytes from a given reader `R`.
///
@ -24,12 +24,17 @@ use crate::{config::Config, utils::Sealed};
pub struct DecoderImpl<R, C: Config> {
reader: R,
config: C,
bytes_read: usize,
}
impl<R: Reader, C: Config> DecoderImpl<R, C> {
/// Construct a new Decoder
pub fn new(reader: R, config: C) -> DecoderImpl<R, C> {
DecoderImpl { reader, config }
DecoderImpl {
reader,
config,
bytes_read: 0,
}
}
}
@ -55,4 +60,32 @@ impl<R: Reader, C: Config> Decoder for DecoderImpl<R, C> {
fn config(&self) -> &Self::C {
&self.config
}
#[inline]
fn claim_bytes_read(&mut self, n: usize) -> Result<(), DecodeError> {
// C::LIMIT is a const so this check should get compiled away
if let Some(limit) = C::LIMIT {
// Make sure we don't accidentally overflow `bytes_read`
self.bytes_read = self
.bytes_read
.checked_add(n)
.ok_or(DecodeError::LimitExceeded)?;
if self.bytes_read > limit {
Err(DecodeError::LimitExceeded)
} else {
Ok(())
}
} else {
Ok(())
}
}
#[inline]
fn unclaim_bytes_read(&mut self, n: usize) {
// C::LIMIT is a const so this check should get compiled away
if C::LIMIT.is_some() {
// We should always be claiming more than we unclaim, so this should never underflow
self.bytes_read -= n;
}
}
}

31
src/de/impls.rs
View File

@ -33,6 +33,7 @@ impl Decode for bool {
impl Decode for u8 {
#[inline]
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(1)?;
if let Some(buf) = decoder.reader().peek_read(1) {
let byte = buf[0];
decoder.reader().consume(1);
@ -55,6 +56,7 @@ impl Decode for NonZeroU8 {
impl Decode for u16 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(2)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_u16(decoder.reader(), D::C::ENDIAN)
@ -81,6 +83,7 @@ impl Decode for NonZeroU16 {
impl Decode for u32 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(4)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_u32(decoder.reader(), D::C::ENDIAN)
@ -107,6 +110,7 @@ impl Decode for NonZeroU32 {
impl Decode for u64 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(8)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_u64(decoder.reader(), D::C::ENDIAN)
@ -133,6 +137,7 @@ impl Decode for NonZeroU64 {
impl Decode for u128 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(16)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_u128(decoder.reader(), D::C::ENDIAN)
@ -159,6 +164,7 @@ impl Decode for NonZeroU128 {
impl Decode for usize {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(8)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_usize(decoder.reader(), D::C::ENDIAN)
@ -185,6 +191,7 @@ impl Decode for NonZeroUsize {
impl Decode for i8 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(1)?;
let mut bytes = [0u8; 1];
decoder.reader().read(&mut bytes)?;
Ok(bytes[0] as i8)
@ -201,6 +208,7 @@ impl Decode for NonZeroI8 {
impl Decode for i16 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(2)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_i16(decoder.reader(), D::C::ENDIAN)
@ -227,6 +235,7 @@ impl Decode for NonZeroI16 {
impl Decode for i32 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(4)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_i32(decoder.reader(), D::C::ENDIAN)
@ -253,6 +262,7 @@ impl Decode for NonZeroI32 {
impl Decode for i64 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(8)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_i64(decoder.reader(), D::C::ENDIAN)
@ -279,6 +289,7 @@ impl Decode for NonZeroI64 {
impl Decode for i128 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(16)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_i128(decoder.reader(), D::C::ENDIAN)
@ -305,6 +316,7 @@ impl Decode for NonZeroI128 {
impl Decode for isize {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(8)?;
match D::C::INT_ENCODING {
IntEncoding::Variable => {
crate::varint::varint_decode_isize(decoder.reader(), D::C::ENDIAN)
@ -331,6 +343,7 @@ impl Decode for NonZeroIsize {
impl Decode for f32 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(4)?;
let mut bytes = [0u8; 4];
decoder.reader().read(&mut bytes)?;
Ok(match D::C::ENDIAN {
@ -342,6 +355,7 @@ impl Decode for f32 {
impl Decode for f64 {
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
decoder.claim_bytes_read(8)?;
let mut bytes = [0u8; 8];
decoder.reader().read(&mut bytes)?;
Ok(match D::C::ENDIAN {
@ -362,6 +376,10 @@ impl Decode for char {
if width == 0 {
return Err(DecodeError::InvalidCharEncoding(array));
}
// Normally we have to `.claim_bytes_read` before reading, however in this
// case the amount of bytes read from `char` can vary wildly, and it should
// only read up to 4 bytes too much.
decoder.claim_bytes_read(width)?;
if width == 1 {
return Ok(array[0] as char);
}
@ -379,6 +397,7 @@ impl Decode for char {
impl<'a, 'de: 'a> BorrowDecode<'de> for &'a [u8] {
fn borrow_decode<D: BorrowDecoder<'de>>(mut decoder: D) -> Result<Self, DecodeError> {
let len = super::decode_slice_len(&mut decoder)?;
decoder.claim_bytes_read(len)?;
decoder.borrow_reader().take_bytes(len)
}
}
@ -397,7 +416,7 @@ impl<'a, 'de: 'a> BorrowDecode<'de> for Option<&'a [u8]> {
impl<'a, 'de: 'a> BorrowDecode<'de> for &'a str {
fn borrow_decode<D: BorrowDecoder<'de>>(decoder: D) -> Result<Self, DecodeError> {
let slice: &[u8] = BorrowDecode::borrow_decode(decoder)?;
let slice = <&[u8]>::borrow_decode(decoder)?;
core::str::from_utf8(slice).map_err(DecodeError::Utf8)
}
}
@ -429,6 +448,9 @@ where
}
}
decoder.claim_bytes_read(core::mem::size_of::<[T; N]>())?;
// Optimize for `[u8; N]`
if TypeId::of::<u8>() == TypeId::of::<T>() {
let mut buf = [0u8; N];
decoder.reader().read(&mut buf)?;
@ -439,8 +461,11 @@ where
let res = unsafe { ptr.read() };
Ok(res)
} else {
let result =
super::impl_core::collect_into_array(&mut (0..N).map(|_| T::decode(&mut decoder)));
let result = super::impl_core::collect_into_array(&mut (0..N).map(|_| {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<T>());
T::decode(&mut decoder)
}));
// result is only None if N does not match the values of `(0..N)`, which it always should
// So this unwrap should never occur

75
src/de/mod.rs
View File

@ -6,7 +6,11 @@ mod impl_tuples;
mod impls;
use self::read::{BorrowReader, Reader};
use crate::{config::Config, error::DecodeError, utils::Sealed};
use crate::{
config::{Config, InternalLimitConfig},
error::DecodeError,
utils::Sealed,
};
pub mod read;
@ -53,6 +57,65 @@ pub trait Decoder: Sealed {
/// Returns a mutable reference to the config
fn config(&self) -> &Self::C;
/// Claim that `n` bytes are going to be read from the decoder.
/// This can be used to validate `Configuration::Limit<N>()`.
fn claim_bytes_read(&mut self, n: usize) -> Result<(), DecodeError>;
/// Claim that we're going to read a container which contains `len` entries of `T`.
/// This will correctly handle overflowing if `len * size_of::<T>() > usize::max_value`
fn claim_container_read<T>(&mut self, len: usize) -> Result<(), DecodeError> {
if <Self::C as InternalLimitConfig>::LIMIT.is_some() {
match len.checked_mul(core::mem::size_of::<T>()) {
Some(val) => self.claim_bytes_read(val),
None => Err(DecodeError::LimitExceeded),
}
} else {
Ok(())
}
}
/// Notify the decoder that `n` bytes are being reclaimed.
///
/// When decoding container types, a typical implementation would claim to read `len * size_of::<T>()` bytes.
/// This is to ensure that bincode won't allocate several GB of memory while constructing the container.
///
/// Because the implementation claims `len * size_of::<T>()`, but then has to decode each `T`, this would be marked
/// as double. This function allows us to un-claim each `T` that gets decoded.
///
/// We cannot check if `len * size_of::<T>()` is valid without claiming it, because this would mean that if you have
/// a nested container (e.g. `Vec<Vec<T>>`), it does not know how much memory is already claimed, and could easily
/// allocate much more than the user intends.
/// ```
/// # use bincode::de::{Decode, Decoder};
/// # use bincode::error::DecodeError;
/// # struct Container<T>(Vec<T>);
/// # impl<T> Container<T> {
/// # fn with_capacity(cap: usize) -> Self {
/// # Self(Vec::with_capacity(cap))
/// # }
/// #
/// # fn push(&mut self, t: T) {
/// # self.0.push(t);
/// # }
/// # }
/// impl<T: Decode> Decode for Container<T> {
/// fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
/// let len = u64::decode(&mut decoder)? as usize;
/// // Make sure we don't allocate too much memory
/// decoder.claim_bytes_read(len * core::mem::size_of::<T>());
///
/// let mut result = Container::with_capacity(len);
/// for _ in 0..len {
/// // un-claim the memory
/// decoder.unclaim_bytes_read(core::mem::size_of::<T>());
/// result.push(T::decode(&mut decoder)?)
/// }
/// Ok(result)
/// }
/// }
/// ```
fn unclaim_bytes_read(&mut self, n: usize);
}
/// Any source that can decode basic types. This type is most notably implemented for [Decoder].
@ -81,6 +144,16 @@ where
fn config(&self) -> &Self::C {
T::config(self)
}
#[inline]
fn claim_bytes_read(&mut self, n: usize) -> Result<(), DecodeError> {
T::claim_bytes_read(self, n)
}
#[inline]
fn unclaim_bytes_read(&mut self, n: usize) {
T::unclaim_bytes_read(self, n)
}
}
impl<'a, 'de, T> BorrowDecoder<'de> for &'a mut T

3
src/error.rs
View File

@ -70,6 +70,9 @@ pub enum DecodeError {
/// The reader reached its end but more bytes were expected.
UnexpectedEnd,
/// The given configuration limit was exceeded
LimitExceeded,
/// Invalid type was found. The decoder tried to read type `expected`, but found type `found` instead.
InvalidIntegerType {
/// The type that was being read from the reader

25
src/features/impl_alloc.rs
View File

@ -52,8 +52,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<T>(len)?;
let mut map = BinaryHeap::with_capacity(len);
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<T>());
let key = T::decode(&mut decoder)?;
map.push(key);
}
@ -81,8 +86,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<(K, V)>(len)?;
let mut map = BTreeMap::new();
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<(K, V)>());
let key = K::decode(&mut decoder)?;
let value = V::decode(&mut decoder)?;
map.insert(key, value);
@ -112,8 +122,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<T>(len)?;
let mut map = BTreeSet::new();
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<T>());
let key = T::decode(&mut decoder)?;
map.insert(key);
}
@ -140,8 +155,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<T>(len)?;
let mut map = VecDeque::with_capacity(len);
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<T>());
let key = T::decode(&mut decoder)?;
map.push_back(key);
}
@ -168,8 +188,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<T>(len)?;
let mut vec = Vec::with_capacity(len);
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<T>());
vec.push(T::decode(&mut decoder)?);
}
Ok(vec)

5
src/features/impl_std.rs
View File

@ -369,8 +369,13 @@ where
{
fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
let len = crate::de::decode_slice_len(&mut decoder)?;
decoder.claim_container_read::<(K, V)>(len)?;
let mut map = HashMap::with_capacity(len);
for _ in 0..len {
// See the documentation on `unclaim_bytes_read` as to why we're doing this here
decoder.unclaim_bytes_read(core::mem::size_of::<(K, V)>());
let k = K::decode(&mut decoder)?;
let v = V::decode(&mut decoder)?;
map.insert(k, v);

38
tests/alloc.rs
View File

@ -89,3 +89,41 @@ fn test_alloc_commons() {
set
});
}
#[test]
fn test_container_limits() {
use bincode::{error::DecodeError, Decode};
const DECODE_LIMIT: usize = 100_000;
// for this test we'll create a malformed package of a lot of bytes
let test_cases = &[
// u64::max_value(), should overflow
bincode::encode_to_vec(u64::max_value(), Configuration::standard()).unwrap(),
// A high value which doesn't overflow, but exceeds the decode limit
bincode::encode_to_vec(DECODE_LIMIT as u64, Configuration::standard()).unwrap(),
];
fn validate_fail<T: Decode + core::fmt::Debug>(slice: &[u8]) {
let result = bincode::decode_from_slice::<T, _>(
slice,
Configuration::standard().with_limit::<DECODE_LIMIT>(),
);
assert_eq!(result.unwrap_err(), DecodeError::LimitExceeded);
}
for slice in test_cases {
validate_fail::<BinaryHeap<i32>>(slice);
validate_fail::<BTreeMap<i32, i32>>(slice);
validate_fail::<BTreeSet<i32>>(slice);
validate_fail::<VecDeque<i32>>(slice);
validate_fail::<Vec<i32>>(slice);
validate_fail::<String>(slice);
validate_fail::<Box<[u8]>>(slice);
#[cfg(feature = "std")]
{
validate_fail::<std::collections::HashMap<i32, i32>>(slice);
}
}
}