prysm-pulse/beacon-chain/blockchain/process_attestation.go
terence tsao bc2c206832
Add verify slot target epoch function and apply all (#8273)
* Add verify slot target epoch function and apply all

* Fix TestProcessAttestationsNoVerify_IncorrectSlotTargetEpoch

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>
2021-01-19 21:41:44 +00:00

104 lines
4.1 KiB
Go

package blockchain
import (
"context"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
"github.com/prysmaticlabs/prysm/shared/bytesutil"
"github.com/prysmaticlabs/prysm/shared/params"
"github.com/prysmaticlabs/prysm/shared/timeutils"
"go.opencensus.io/trace"
)
// ErrTargetRootNotInDB returns when the target block root of an attestation cannot be found in the
// beacon database.
var ErrTargetRootNotInDB = errors.New("target root does not exist in db")
// onAttestation is called whenever an attestation is received, verifies the attestation is valid and saves
// it to the DB. As a stateless function, this does not hold nor delay attestation based on the spec descriptions.
// The delay is handled by the caller in `processAttestation`.
//
// Spec pseudocode definition:
// def on_attestation(store: Store, attestation: Attestation) -> None:
// """
// 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.
// """
// validate_on_attestation(store, attestation)
// store_target_checkpoint_state(store, attestation.data.target)
//
// # Get state at the `target` to fully validate attestation
// target_state = store.checkpoint_states[attestation.data.target]
// indexed_attestation = get_indexed_attestation(target_state, attestation)
// assert is_valid_indexed_attestation(target_state, indexed_attestation)
//
// # Update latest messages for attesting indices
// update_latest_messages(store, indexed_attestation.attesting_indices, attestation)
// TODO(#6072): This code path is highly untested. Requires comprehensive tests and simpler refactoring.
func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) ([]uint64, error) {
ctx, span := trace.StartSpan(ctx, "blockChain.onAttestation")
defer span.End()
if err := helpers.ValidateNilAttestation(a); err != nil {
return nil, err
}
if err := helpers.ValidateSlotTargetEpoch(a.Data); err != nil {
return nil, err
}
tgt := stateTrie.CopyCheckpoint(a.Data.Target)
// Verify beacon node has seen the target block before.
if !s.hasBlock(ctx, bytesutil.ToBytes32(tgt.Root)) {
return nil, ErrTargetRootNotInDB
}
// Retrieve attestation's data beacon block pre state. Advance pre state to latest epoch if necessary and
// save it to the cache.
baseState, err := s.getAttPreState(ctx, tgt)
if err != nil {
return nil, err
}
genesisTime := baseState.GenesisTime()
// Verify attestation target is from current epoch or previous epoch.
if err := s.verifyAttTargetEpoch(ctx, genesisTime, uint64(timeutils.Now().Unix()), tgt); err != nil {
return nil, err
}
// Verify attestation beacon block is known and not from the future.
if err := s.verifyBeaconBlock(ctx, a.Data); err != nil {
return nil, errors.Wrap(err, "could not verify attestation beacon block")
}
// Verify LMG GHOST and FFG votes are consistent with each other.
if err := s.verifyLMDFFGConsistent(ctx, a.Data.Target.Epoch, a.Data.Target.Root, a.Data.BeaconBlockRoot); err != nil {
return nil, errors.Wrap(err, "could not verify attestation beacon block")
}
// Verify attestations can only affect the fork choice of subsequent slots.
if err := helpers.VerifySlotTime(genesisTime, a.Data.Slot+1, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
return nil, err
}
// Use the target state to validate attestation and calculate the committees.
indexedAtt, err := s.verifyAttestation(ctx, baseState, a)
if err != nil {
return nil, err
}
if indexedAtt.AttestingIndices == nil {
return nil, errors.New("nil attesting indices")
}
// Update forkchoice store with the new attestation for updating weight.
s.forkChoiceStore.ProcessAttestation(ctx, indexedAtt.AttestingIndices, bytesutil.ToBytes32(a.Data.BeaconBlockRoot), a.Data.Target.Epoch)
return indexedAtt.AttestingIndices, nil
}