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Fix bug in beacon state randao getter

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This commit is contained in:
Paul Hauner 2019-05-23 16:53:18 +10:00
parent c214bec344
commit b8e25a3e4c
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1 changed files with 14 additions and 9 deletions
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23
eth2/types/src/beacon_state.rs
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@ -680,18 +680,23 @@ impl<T: EthSpec> BeaconState<T> {
/// Generate a seed for the given `epoch`.
///
/// Spec v0.5.1
/// Spec v0.6.1
pub fn generate_seed(&self, epoch: Epoch, spec: &ChainSpec) -> Result<Hash256, Error> {
let mut input = self
.get_randao_mix(epoch - spec.min_seed_lookahead)?
.as_bytes()
.to_vec();
// Bypass the safe getter for RANDAO so we can gracefully handle the scenario where `epoch
// == 0`.
let randao = {
let i = epoch + T::latest_randao_mixes_length() as u64 - spec.min_seed_lookahead;
self.latest_randao_mixes[i.as_usize() % self.latest_randao_mixes.len()]
};
let active_index_root = self.get_active_index_root(epoch, spec)?;
let epoch_bytes = int_to_bytes32(epoch.as_u64());
input.append(&mut self.get_active_index_root(epoch, spec)?.as_bytes().to_vec());
let mut preimage = [0; 32 * 3];
preimage[0..32].copy_from_slice(&randao[..]);
preimage[32..64].copy_from_slice(&active_index_root[..]);
preimage[64..].copy_from_slice(&epoch_bytes);
input.append(&mut int_to_bytes32(epoch.as_u64()));
Ok(Hash256::from_slice(&hash(&input[..])[..]))
Ok(Hash256::from_slice(&hash(&preimage)))
}
/// Return the effective balance (also known as "balance at stake") for a validator with the given ``index``.