public void ProcessAttestation(BeaconState state, Attestation attestation)
{
_logger.LogInformation(Event.ProcessAttestation, "Process block operation attestation {Attestation} for state {BeaconState}.", attestation, state);
var timeParameters = _timeParameterOptions.CurrentValue;
var data = attestation.Data;
var committeeCount = _beaconStateAccessor.GetCommitteeCountAtSlot(state, data.Slot);
if ((ulong)data.Index >= committeeCount)
{
throw new ArgumentOutOfRangeException("attestation.Data.Index", data.Index, $"Attestation data committee index must be less that the committee count {committeeCount}.");
}
var previousEpoch = _beaconStateAccessor.GetPreviousEpoch(state);
var currentEpoch = _beaconStateAccessor.GetCurrentEpoch(state);
if (data.Target.Epoch != previousEpoch && data.Target.Epoch != currentEpoch)
{
throw new ArgumentOutOfRangeException("attestation.Data.Target.Epoch", data.Target.Epoch, $"Attestation data target epoch must be either the previous epoch {previousEpoch} or the current epoch {currentEpoch}.");
}
var minimumSlot = data.Slot + timeParameters.MinimumAttestationInclusionDelay;
var maximumSlot = data.Slot + timeParameters.SlotsPerEpoch;
if (state.Slot < minimumSlot)
{
throw new Exception($"Current state slot {state.Slot} must be equal or greater than the attestion slot {data.Slot} plus minimum delay {timeParameters.MinimumAttestationInclusionDelay}.");
}
if (state.Slot > maximumSlot)
{
throw new Exception($"Current state slot {state.Slot} must be equal or less than the attestation slot {data.Slot} plus slots per epoch {timeParameters.SlotsPerEpoch}.");
}
var committee = _beaconStateAccessor.GetBeaconCommittee(state, data.Slot, data.Index);
if (attestation.AggregationBits.Count != attestation.CustodyBits.Count)
{
throw new Exception($"The attestation aggregation bit length {attestation.AggregationBits.Count} must be the same as the custody bit length {attestation.CustodyBits.Count}.");
}
if (attestation.AggregationBits.Count != committee.Count)
{
throw new Exception($"The attestation aggregation bit (and custody bit) length {attestation.AggregationBits.Count} must be the same as the committee length {committee.Count}.");
}
var inclusionDelay = state.Slot - data.Slot;
var proposerIndex = _beaconStateAccessor.GetBeaconProposerIndex(state);
var pendingAttestation = new PendingAttestation(attestation.AggregationBits, data, inclusionDelay, proposerIndex);
if (data.Target.Epoch == currentEpoch)
{
if (!data.Source.Equals(state.CurrentJustifiedCheckpoint))
{
throw new Exception($"For a current epoch target attestation the data source checkpoint {data.Source} must be the same as the current justified checkpoint {state.CurrentJustifiedCheckpoint}.");
}
state.AddCurrentAttestation(pendingAttestation);
}
else
{
if (!data.Source.Equals(state.PreviousJustifiedCheckpoint))
{
throw new Exception($"For a previous epoch target attestation the data source checkpoint {data.Source} must be the same as the previous justified checkpoint {state.PreviousJustifiedCheckpoint}.");
}
state.AddPreviousAttestation(pendingAttestation);
}
// Check signature
var indexedAttestation = _beaconStateAccessor.GetIndexedAttestation(state, attestation);
var domain = _beaconStateAccessor.GetDomain(state, _signatureDomainOptions.CurrentValue.BeaconAttester, data.Target.Epoch);
var isValid = _beaconChainUtility.IsValidIndexedAttestation(state, indexedAttestation, domain);
if (!isValid)
{
throw new Exception($"Indexed attestation {indexedAttestation} is not valid.");
}
}
/// <summary>
/// Run ``on_attestation`` upon receiving a new ``attestation`` from either within a block or directly on the wire.
/// An ``attestation`` that is asserted as invalid may be valid at a later time,
/// consider scheduling it for later processing in such case.
/// </summary>
public void OnAttestation(IStore store, Attestation attestation)
{
var initialValues = _initialValueOptions.CurrentValue;
var timeParameters = _timeParameterOptions.CurrentValue;
var target = attestation.Data.Target;
// Attestations must be from the current or previous epoch
var currentSlot = GetCurrentSlot(store);
var currentEpoch = _beaconChainUtility.ComputeEpochAtSlot(currentSlot);
// Use GENESIS_EPOCH for previous when genesis to avoid underflow
var previousEpoch = currentEpoch > initialValues.GenesisEpoch
? currentEpoch - new Epoch(1)
: initialValues.GenesisEpoch;
if (target.Epoch != currentEpoch && target.Epoch != previousEpoch)
{
throw new ArgumentOutOfRangeException("attestation.Target.Epoch", target.Epoch, $"Attestation target epoch must be either the current epoch {currentEpoch} or previous epoch {previousEpoch}.");
}
// Cannot calculate the current shuffling if have not seen the target
if (!store.TryGetBlock(target.Root, out var targetBlock))
{
throw new ArgumentOutOfRangeException("attestation.Target.Root", target.Root, "Attestation target root not found in the block history.");
}
// Attestations target be for a known block. If target block is unknown, delay consideration until the block is found
if (!store.TryGetBlockState(target.Root, out var targetStoredState))
{
throw new ArgumentOutOfRangeException("attestation.Target.Root", target.Root, "Attestation target root not found in the block stores history.");
}
// Attestations cannot be from future epochs. If they are, delay consideration until the epoch arrives
var baseState = BeaconState.Clone(targetStoredState);
var targetEpochStartSlot = _beaconChainUtility.ComputeStartSlotOfEpoch(target.Epoch);
var targetEpochStartSlotTime = baseState.GenesisTime + (ulong)targetEpochStartSlot * timeParameters.SecondsPerSlot;
if (store.Time < targetEpochStartSlotTime)
{
throw new Exception($"Ättestation target state time {targetEpochStartSlotTime} should not be larger than the store time {store.Time}).");
}
// Attestations must be for a known block. If block is unknown, delay consideration until the block is found
if (!store.TryGetBlock(attestation.Data.BeaconBlockRoot, out var attestationBlock))
{
throw new ArgumentOutOfRangeException("attestation.Data.BeaconBlockRoot", attestation.Data.BeaconBlockRoot, "Attestation data root not found in the block history.");
}
// Attestations must not be for blocks in the future. If not, the attestation should not be considered
if (attestationBlock.Slot > attestation.Data.Slot)
{
throw new Exception($"Ättestation data root slot {attestationBlock.Slot} should not be larger than the attestation data slot {attestation.Data.Slot}).");
}
// Store target checkpoint state if not yet seen
if (!store.TryGetCheckpointState(target, out var targetState))
{
_beaconStateTransition.ProcessSlots(baseState, targetEpochStartSlot);
store.SetCheckpointState(target, baseState);
targetState = baseState;
}
// Attestations can only affect the fork choice of subsequent slots.
// Delay consideration in the fork choice until their slot is in the past.
//var attestationDataSlotTime = ((ulong)attestation.Data.Slot + 1) * timeParameters.SecondsPerSlot;
var attestationDataSlotTime = targetState.GenesisTime + ((ulong)attestation.Data.Slot + 1) * timeParameters.SecondsPerSlot;
if (store.Time < attestationDataSlotTime)
{
throw new Exception($"Ättestation data time {attestationDataSlotTime} should not be larger than the store time {store.Time}).");
}
// Get state at the `target` to validate attestation and calculate the committees
var indexedAttestation = _beaconStateAccessor.GetIndexedAttestation(targetState, attestation);
var domain = _beaconStateAccessor.GetDomain(targetState, _signatureDomainOptions.CurrentValue.BeaconAttester, indexedAttestation.Data.Target.Epoch);
var isValid = _beaconChainUtility.IsValidIndexedAttestation(targetState, indexedAttestation, domain);
if (!isValid)
{
throw new Exception($"Indexed attestation {indexedAttestation} is not valid.");
}
// Update latest messages
var attestingIndices = _beaconStateAccessor.GetAttestingIndices(targetState, attestation.Data, attestation.AggregationBits);
foreach (var index in attestingIndices)
{
if (!store.TryGetLatestMessage(index, out var latestMessage) || target.Epoch > latestMessage.Epoch)
{
var newLatestMessage = new LatestMessage(target.Epoch, attestation.Data.BeaconBlockRoot);
store.SetLatestMessage(index, newLatestMessage);
}
}
}