[WIP] Broadcast Slashing on equivocation

beacon-chain/blockchain/process_block.go

@@ -75,6 +75,23 @@ func (s *Service) postBlockProcess(cfg *postBlockProcessConfig) error {
 	defer reportProcessingTime(startTime)
 	defer reportAttestationInclusion(cfg.roblock.Block())
 
+	// Check for equivocation before inserting into fork choice
+	slashing, slashingErr := s.detectEquivocatingBlock(cfg.ctx, cfg.roblock)
+	if slashingErr != nil {
+		return errors.Wrap(slashingErr, "could not detect equivocating block")
+	}
+
+	if slashing != nil {
+		if err := s.broadcastProposerSlashing(cfg.ctx, slashing); err != nil {
+			log.WithError(err).Error("Could not broadcast proposer slashing")
+		}
+
+		// Also insert into slashing pool
+		if err := s.cfg.SlashingPool.InsertProposerSlashing(cfg.ctx, cfg.postState, slashing); err != nil {
+			log.WithError(err).Error("Could not insert proposer slashing into pool")
+		}
+	}
+
 	err := s.cfg.ForkChoiceStore.InsertNode(ctx, cfg.postState, cfg.roblock)
 	if err != nil {
 		// Do not use parent context in the event it deadlined
@@ -706,3 +723,11 @@ func (s *Service) rollbackBlock(ctx context.Context, blockRoot [32]byte) {
 		log.WithError(err).Errorf("Could not delete block with block root %#x", blockRoot)
 	}
 }
+
+func (s *Service) broadcastProposerSlashing(ctx context.Context, slashing *ethpb.ProposerSlashing) error {
+	if features.Get().DisableBroadcastSlashings {
+		return nil
+	}
+
+	return s.cfg.P2p.Broadcast(ctx, slashing)
+}

beacon-chain/blockchain/service.go

@@ -580,3 +580,50 @@
 	}
 	go slots.CountdownToGenesis(ctx, genesisTime, uint64(gState.NumValidators()), gRoot)
 }
+
+func (s *Service) detectEquivocatingBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock) (*ethpb.ProposerSlashing, error) {
+	// Get the incoming block's header
+	header1, err := block.Header()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get header from incoming block")
+	}
+
+	s.headLock.RLock()
+	headBlock, err := s.headBlock()
+	if err != nil {
+		s.headLock.RUnlock()
+		return nil, errors.Wrap(err, "could not get head block")
+	}
+	s.headLock.RUnlock()
+
+	// Get the head block's header
+	header2, err := headBlock.Header()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get header from head block")
+	}
+
+	// Check for equivocation:
+	if header1.Header.Slot == header2.Header.Slot &&
+		header1.Header.ProposerIndex == header2.Header.ProposerIndex {
+
+		header1Root, err := header1.Header.HashTreeRoot()
+		if err != nil {
+			return nil, errors.Wrap(err, "could not hash header 1")
+		}
+
+		header2Root, err := header2.Header.HashTreeRoot()
+		if err != nil {
+			return nil, errors.Wrap(err, "could not hash header 2")
+		}
+
+		// Different header roots means equivocation
+		if header1Root != header2Root {
+			return &ethpb.ProposerSlashing{
+				Header_1: header1,
+				Header_2: header2,
+			}, nil
+		}
+	}
+
+	return nil, nil
+}