Struct CompactSizeDecoder 

pub struct CompactSizeDecoder { /* private fields */ }

Decodes a compact size encoded integer as a length prefix.

The decoded value is returned as a usize and is bounded by a configurable limit (default: 4,000,000). This limit is a denial-of-service protection: a malicious peer can send a compact size value up to 2^64-1, and without a limit check the caller might attempt to allocate an enormous buffer based on that value. CompactSizeDecoder prevents this by rejecting values that exceed the limit before returning them to the caller.

If you are decoding an arbitrary u64 integer that is genuinely not a length prefix, use CompactSizeU64Decoder instead.

For more information about decoders see the documentation of the Decoder trait.

Implementations

impl CompactSizeDecoder

pub const fn new() -> Self

Constructs a new compact size decoder with the default length limit.

The decoded value must not exceed 4,000,000 and must fit in a usize, otherwise end will return an error. This default limit reflects the maximum sensible vector length under the 4 MB block weight limit.

pub const fn new_with_limit(limit: usize) -> Self

Constructs a new compact size decoder with a custom length limit.

The decoded value must not exceed limit, otherwise end will return an error. Use this when you know the field you are decoding has a tighter bound than the default limit of 4,000,000.

Trait Implementations

impl Clone for CompactSizeDecoder

fn clone(&self) -> CompactSizeDecoder

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CompactSizeDecoder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Decoder for CompactSizeDecoder

type Output = usize

The type that this decoder produces when decoding is complete.

type Error = CompactSizeDecoderError

The error type that this decoder can produce.

fn push_bytes(&mut self, bytes: &mut &[u8]) -> Result<bool, Self::Error>

Pushes bytes into the decoder, consuming as much as possible.

fn end(self) -> Result<Self::Output, Self::Error>

Completes the decoding process and return the final result.

fn read_limit(&self) -> usize

Returns the maximum number of bytes this decoder can consume without over-reading.

impl Default for CompactSizeDecoder

fn default() -> Self

Returns the “default value” for a type.