lighthouse/beacon_node/beacon_chain/src/observed_operations.rs
Michael Sproul bcb6afa0aa
Process exits and slashings off the network (#1253)
* Process exits and slashings off the network

* Fix rest_api tests

* Add op verification tests

* Add tests for pruning of slashings in the op pool

* Address Paul's review comments
2020-06-18 21:06:34 +10:00

105 lines
4.3 KiB
Rust

use derivative::Derivative;
use parking_lot::Mutex;
use smallvec::SmallVec;
use state_processing::{SigVerifiedOp, VerifyOperation};
use std::collections::HashSet;
use std::iter::FromIterator;
use std::marker::PhantomData;
use types::{
AttesterSlashing, BeaconState, ChainSpec, EthSpec, ProposerSlashing, SignedVoluntaryExit,
};
/// Number of validator indices to store on the stack in `observed_validators`.
pub const SMALL_VEC_SIZE: usize = 8;
/// Stateful tracker for exit/slashing operations seen on the network.
///
/// Implements the conditions for gossip verification of exits and slashings from the P2P spec.
#[derive(Debug, Derivative)]
#[derivative(Default(bound = "T: ObservableOperation<E>, E: EthSpec"))]
pub struct ObservedOperations<T: ObservableOperation<E>, E: EthSpec> {
/// Indices of validators for whom we have already seen an instance of an operation `T`.
///
/// For voluntary exits, this is the set of all `signed_voluntary_exit.message.validator_index`.
/// For proposer slashings, this is the set of all `proposer_slashing.index`.
/// For attester slashings, this is the set of all validators who would be slashed by
/// previously seen attester slashings, i.e. those validators in the intersection of
/// `attestation_1.attester_indices` and `attestation_2.attester_indices`.
observed_validator_indices: Mutex<HashSet<u64>>,
_phantom: PhantomData<(T, E)>,
}
/// Was the observed operation new and valid for further processing, or a useless duplicate?
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum ObservationOutcome<T> {
New(SigVerifiedOp<T>),
AlreadyKnown,
}
/// Trait for exits and slashings which can be observed using `ObservedOperations`.
pub trait ObservableOperation<E: EthSpec>: VerifyOperation<E> + Sized {
/// The set of validator indices involved in this operation.
///
/// See the comment on `observed_validator_indices` above for detail.
fn observed_validators(&self) -> SmallVec<[u64; SMALL_VEC_SIZE]>;
}
impl<E: EthSpec> ObservableOperation<E> for SignedVoluntaryExit {
fn observed_validators(&self) -> SmallVec<[u64; SMALL_VEC_SIZE]> {
std::iter::once(self.message.validator_index).collect()
}
}
impl<E: EthSpec> ObservableOperation<E> for ProposerSlashing {
fn observed_validators(&self) -> SmallVec<[u64; SMALL_VEC_SIZE]> {
std::iter::once(self.signed_header_1.message.proposer_index).collect()
}
}
impl<E: EthSpec> ObservableOperation<E> for AttesterSlashing<E> {
fn observed_validators(&self) -> SmallVec<[u64; SMALL_VEC_SIZE]> {
let attestation_1_indices =
HashSet::<u64>::from_iter(self.attestation_1.attesting_indices.iter().copied());
let attestation_2_indices =
HashSet::<u64>::from_iter(self.attestation_2.attesting_indices.iter().copied());
attestation_1_indices
.intersection(&attestation_2_indices)
.copied()
.collect()
}
}
impl<T: ObservableOperation<E>, E: EthSpec> ObservedOperations<T, E> {
pub fn verify_and_observe(
&self,
op: T,
head_state: &BeaconState<E>,
spec: &ChainSpec,
) -> Result<ObservationOutcome<T>, T::Error> {
let mut observed_validator_indices = self.observed_validator_indices.lock();
let new_validator_indices = op.observed_validators();
// If all of the new validator indices have been previously observed, short-circuit
// the validation. This implements the uniqueness check part of the spec, which for attester
// slashings reads:
//
// At least one index in the intersection of the attesting indices of each attestation has
// not yet been seen in any prior attester_slashing.
if new_validator_indices
.iter()
.all(|index| observed_validator_indices.contains(index))
{
return Ok(ObservationOutcome::AlreadyKnown);
}
// Validate the op using operation-specific logic (`verify_attester_slashing`, etc).
let verified_op = op.validate(head_state, spec)?;
// Add the relevant indices to the set of known indices to prevent processing of duplicates
// in the future.
observed_validator_indices.extend(new_validator_indices);
Ok(ObservationOutcome::New(verified_op))
}
}