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.");
}
}