lighthouse/eth2/operation_pool/src/attestation_id.rs

use int_to_bytes::int_to_bytes8;
use serde_derive::{Deserialize, Serialize};
use ssz::ssz_encode;
use ssz_derive::{Decode, Encode};
use types::{AttestationData, ChainSpec, Domain, Epoch, Fork};

/// Serialized `AttestationData` augmented with a domain to encode the fork info.
#[derive(
    PartialEq, Eq, Clone, Hash, Debug, PartialOrd, Ord, Encode, Decode, Serialize, Deserialize,
)]
pub struct AttestationId {
    v: Vec<u8>,
}

/// Number of domain bytes that the end of an attestation ID is padded with.
const DOMAIN_BYTES_LEN: usize = 8;

impl AttestationId {
    pub fn from_data(attestation: &AttestationData, fork: &Fork, spec: &ChainSpec) -> Self {
        let mut bytes = ssz_encode(attestation);
        let epoch = attestation.target.epoch;
        bytes.extend_from_slice(&AttestationId::compute_domain_bytes(epoch, fork, spec));
        AttestationId { v: bytes }
    }

    pub fn compute_domain_bytes(epoch: Epoch, fork: &Fork, spec: &ChainSpec) -> Vec<u8> {
        int_to_bytes8(spec.get_domain(epoch, Domain::BeaconAttester, fork))
    }

    pub fn domain_bytes_match(&self, domain_bytes: &[u8]) -> bool {
        &self.v[self.v.len() - DOMAIN_BYTES_LEN..] == domain_bytes
    }
}