79 lines
2.3 KiB
Rust
79 lines
2.3 KiB
Rust
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//! Recursive Length Prefix (RLP) encoding support.
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use crate::{Encoding, Uint};
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use rlp::{DecoderError, Rlp, RlpStream};
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impl<const LIMBS: usize> rlp::Encodable for Uint<LIMBS>
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where
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Self: Encoding,
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{
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fn rlp_append(&self, stream: &mut RlpStream) {
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let bytes = self.to_be_bytes();
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let mut bytes_stripped = bytes.as_ref();
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while bytes_stripped.first().cloned() == Some(0) {
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bytes_stripped = &bytes_stripped[1..];
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}
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stream.encoder().encode_value(bytes_stripped);
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}
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}
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impl<const LIMBS: usize> rlp::Decodable for Uint<LIMBS>
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where
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Self: Encoding,
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<Self as Encoding>::Repr: Default,
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{
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fn decode(rlp: &Rlp<'_>) -> Result<Self, DecoderError> {
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rlp.decoder().decode_value(|bytes| {
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if bytes.first().cloned() == Some(0) {
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Err(rlp::DecoderError::RlpInvalidIndirection)
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} else {
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let mut repr = <Self as Encoding>::Repr::default();
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let offset = repr
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.as_ref()
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.len()
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.checked_sub(bytes.len())
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.ok_or(DecoderError::RlpIsTooBig)?;
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repr.as_mut()[offset..].copy_from_slice(bytes);
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Ok(Self::from_be_bytes(repr))
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}
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})
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}
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}
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#[cfg(test)]
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#[allow(clippy::unwrap_used)]
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mod tests {
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use crate::U256;
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use hex_literal::hex;
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/// U256 test vectors from the `rlp` crate.
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///
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/// <https://github.com/paritytech/parity-common/blob/faad8b6/rlp/tests/tests.rs#L216-L222>
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const U256_VECTORS: &[(U256, &[u8])] = &[
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(U256::ZERO, &hex!("80")),
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(
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U256::from_be_hex("0000000000000000000000000000000000000000000000000000000001000000"),
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&hex!("8401000000"),
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),
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(
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U256::from_be_hex("00000000000000000000000000000000000000000000000000000000ffffffff"),
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&hex!("84ffffffff"),
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),
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(
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U256::from_be_hex("8090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0"),
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&hex!("a08090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0"),
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),
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];
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#[test]
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fn round_trip() {
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for &(uint, expected_bytes) in U256_VECTORS {
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assert_eq!(rlp::encode(&uint), expected_bytes);
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assert_eq!(rlp::decode::<U256>(expected_bytes).unwrap(), uint);
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}
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}
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}
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