/
detect.go
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/
detect.go
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package detection
import (
"bytes"
"context"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
slashpb "github.com/prysmaticlabs/prysm/proto/slashing"
"github.com/prysmaticlabs/prysm/shared/attestationutil"
"github.com/prysmaticlabs/prysm/shared/bytesutil"
"github.com/prysmaticlabs/prysm/shared/hashutil"
"github.com/prysmaticlabs/prysm/shared/slashutil"
"github.com/prysmaticlabs/prysm/shared/sliceutil"
status "github.com/prysmaticlabs/prysm/slasher/db/types"
"github.com/prysmaticlabs/prysm/slasher/detection/attestations/types"
"go.opencensus.io/trace"
)
// DetectAttesterSlashings detects double, surround and surrounding attestation offences given an attestation.
func (s *Service) DetectAttesterSlashings(
ctx context.Context,
att *ethpb.IndexedAttestation,
) ([]*ethpb.AttesterSlashing, error) {
ctx, span := trace.StartSpan(ctx, "detection.DetectAttesterSlashings")
defer span.End()
results, err := s.minMaxSpanDetector.DetectSlashingsForAttestation(ctx, att)
if err != nil {
return nil, err
}
// If the response is nil, there was no slashing detected.
if len(results) == 0 {
return nil, nil
}
resultsToAtts, err := s.mapResultsToAtts(ctx, results)
if err != nil {
return nil, err
}
var slashings []*ethpb.AttesterSlashing
for _, result := range results {
resultKey := resultHash(result)
var slashing *ethpb.AttesterSlashing
switch result.Kind {
case types.DoubleVote:
slashing, err = s.detectDoubleVote(ctx, resultsToAtts[resultKey], att, result)
if err != nil {
return nil, errors.Wrap(err, "could not detect double votes on attestation")
}
case types.SurroundVote:
slashing, err = s.detectSurroundVotes(ctx, resultsToAtts[resultKey], att, result)
if err != nil {
return nil, errors.Wrap(err, "could not detect surround votes on attestation")
}
}
if slashing != nil {
slashings = append(slashings, slashing)
}
}
// Clear out any duplicate results.
keys := make(map[[32]byte]bool)
var slashingList []*ethpb.AttesterSlashing
for _, ss := range slashings {
hash, err := hashutil.HashProto(ss)
if err != nil {
return nil, errors.Wrap(err, "could not hash slashing")
}
if _, value := keys[hash]; !value {
keys[hash] = true
slashingList = append(slashingList, ss)
}
}
if len(slashings) > 0 {
if err := s.cfg.SlasherDB.SaveAttesterSlashings(ctx, status.Active, slashings); err != nil {
return nil, err
}
}
return slashingList, nil
}
// UpdateSpans passthrough function that updates span maps given an indexed attestation.
func (s *Service) UpdateSpans(ctx context.Context, att *ethpb.IndexedAttestation) error {
return s.minMaxSpanDetector.UpdateSpans(ctx, att)
}
// detectDoubleVote cross references the passed in attestation with the bloom filter maintained
// for every epoch for the validator in order to determine if it is a double vote.
func (s *Service) detectDoubleVote(
_ context.Context,
possibleAtts []*ethpb.IndexedAttestation,
incomingAtt *ethpb.IndexedAttestation,
detectionResult *types.DetectionResult,
) (*ethpb.AttesterSlashing, error) {
if detectionResult == nil || detectionResult.Kind != types.DoubleVote {
return nil, nil
}
for _, att := range possibleAtts {
if att.Data == nil {
continue
}
if !isDoubleVote(incomingAtt, att) {
continue
}
// If there are no shared indices, there is no validator to slash.
if !sliceutil.IsInUint64(detectionResult.ValidatorIndex, att.AttestingIndices) {
continue
}
doubleVotesDetected.Inc()
return ðpb.AttesterSlashing{
Attestation_1: incomingAtt,
Attestation_2: att,
}, nil
}
return nil, nil
}
// detectSurroundVotes cross references the passed in attestation with the requested validator's
// voting history in order to detect any possible surround votes.
func (s *Service) detectSurroundVotes(
ctx context.Context,
possibleAtts []*ethpb.IndexedAttestation,
incomingAtt *ethpb.IndexedAttestation,
detectionResult *types.DetectionResult,
) (*ethpb.AttesterSlashing, error) {
ctx, span := trace.StartSpan(ctx, "detection.detectSurroundVotes")
defer span.End()
if detectionResult == nil || detectionResult.Kind != types.SurroundVote {
return nil, nil
}
for _, att := range possibleAtts {
if att.Data == nil {
continue
}
isSurround := slashutil.IsSurround(incomingAtt, att)
isSurrounded := slashutil.IsSurround(att, incomingAtt)
if !isSurround && !isSurrounded {
continue
}
// If there are no shared indices, there is no validator to slash.
if !sliceutil.IsInUint64(detectionResult.ValidatorIndex, att.AttestingIndices) {
continue
}
// Slashings must be submitted as the incoming attestation surrounding the saved attestation.
// So we swap the order if needed.
if isSurround {
surroundingVotesDetected.Inc()
return ðpb.AttesterSlashing{
Attestation_1: incomingAtt,
Attestation_2: att,
}, nil
} else if isSurrounded {
surroundedVotesDetected.Inc()
return ðpb.AttesterSlashing{
Attestation_1: att,
Attestation_2: incomingAtt,
}, nil
}
}
return nil, errors.New("unexpected false positive in surround vote detection")
}
// DetectDoubleProposals checks if the given signed beacon block is a slashable offense and returns the slashing.
func (s *Service) DetectDoubleProposals(ctx context.Context, incomingBlock *ethpb.SignedBeaconBlockHeader) (*ethpb.ProposerSlashing, error) {
return s.proposalsDetector.DetectDoublePropose(ctx, incomingBlock)
}
// DetectDoubleProposeNoUpdate checks if the given beacon block header is a slashable offense.
func (s *Service) DetectDoubleProposeNoUpdate(ctx context.Context, incomingBlock *ethpb.BeaconBlockHeader) (bool, error) {
return s.proposalsDetector.DetectDoubleProposeNoUpdate(ctx, incomingBlock)
}
// mapResultsToAtts handles any duplicate detections by ensuring they reuse the same pool of attestations, instead of re-checking the DB for the same data.
func (s *Service) mapResultsToAtts(ctx context.Context, results []*types.DetectionResult) (map[[32]byte][]*ethpb.IndexedAttestation, error) {
ctx, span := trace.StartSpan(ctx, "detection.mapResultsToAtts")
defer span.End()
resultsToAtts := make(map[[32]byte][]*ethpb.IndexedAttestation)
for _, result := range results {
resultKey := resultHash(result)
if _, ok := resultsToAtts[resultKey]; ok {
continue
}
matchingAtts, err := s.cfg.SlasherDB.IndexedAttestationsWithPrefix(ctx, result.SlashableEpoch, result.SigBytes[:])
if err != nil {
return nil, err
}
resultsToAtts[resultKey] = matchingAtts
}
return resultsToAtts, nil
}
func resultHash(result *types.DetectionResult) [32]byte {
resultBytes := append(bytesutil.Bytes8(uint64(result.SlashableEpoch)), result.SigBytes[:]...)
return hashutil.Hash(resultBytes)
}
func isDoublePropose(incomingBlockHeader, prevBlockHeader *ethpb.SignedBeaconBlockHeader) bool {
return incomingBlockHeader.Header.ProposerIndex == prevBlockHeader.Header.ProposerIndex &&
!bytes.Equal(incomingBlockHeader.Signature, prevBlockHeader.Signature) &&
incomingBlockHeader.Header.Slot == prevBlockHeader.Header.Slot
}
func isDoubleVote(incomingAtt, prevAtt *ethpb.IndexedAttestation) bool {
return !attestationutil.AttDataIsEqual(incomingAtt.Data, prevAtt.Data) && incomingAtt.Data.Target.Epoch == prevAtt.Data.Target.Epoch
}
// UpdateHighestAttestation updates to the db the highest source and target attestations for a each validator.
func (s *Service) UpdateHighestAttestation(ctx context.Context, att *ethpb.IndexedAttestation) error {
for _, idx := range att.AttestingIndices {
h, err := s.cfg.SlasherDB.HighestAttestation(ctx, idx)
if err != nil {
return err
}
// Creates a default instance.
if h == nil {
h = &slashpb.HighestAttestation{
HighestSourceEpoch: 0,
HighestTargetEpoch: 0,
ValidatorId: idx,
}
}
update := false
if h.HighestSourceEpoch < att.Data.Source.Epoch {
h.HighestSourceEpoch = att.Data.Source.Epoch
update = true
}
if h.HighestTargetEpoch < att.Data.Target.Epoch {
h.HighestTargetEpoch = att.Data.Target.Epoch
update = true
}
// If it's not a new instance of HighestAttestation, changing it will also change the cached instance.
if update {
if err := s.cfg.SlasherDB.SaveHighestAttestation(ctx, h); err != nil {
return err
}
}
}
return nil
}