Cleanup Validate Beacon Block

beacon-chain/sync/validate_beacon_blocks.go

@@ -241,45 +241,56 @@ func (s *Service) validateBeaconBlock(ctx context.Context, blk interfaces.ReadOn
 		return err
 	}
 
+	parentState, err := s.validatePhase0Block(ctx, blk, blockRoot)
+	if err != nil {
+		return err
+	}
+
+	if err = s.validateBellatrixBeaconBlock(ctx, parentState, blk.Block()); err != nil {
+		if errors.Is(err, ErrOptimisticParent) {
+			return err
+		}
+		// for other kinds of errors, set this block as a bad block.
+		s.setBadBlock(ctx, blockRoot)
+		return err
+	}
+	return nil
+}
+
+// Validates beacon block according to phase 0 validity conditions.
+// - Checks that the parent is in our forkchoice tree.
+// - Validates that the proposer signature is valid.
+// - Validates that the proposer index is valid.
+func (s *Service) validatePhase0Block(ctx context.Context, blk interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) (state.BeaconState, error) {
 	if !s.cfg.chain.InForkchoice(blk.Block().ParentRoot()) {
 		s.setBadBlock(ctx, blockRoot)
-		return blockchain.ErrNotDescendantOfFinalized
+		return nil, blockchain.ErrNotDescendantOfFinalized
 	}
 
 	parentState, err := s.cfg.stateGen.StateByRoot(ctx, blk.Block().ParentRoot())
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := blocks.VerifyBlockSignatureUsingCurrentFork(parentState, blk); err != nil {
-		s.setBadBlock(ctx, blockRoot)
-		return err
+		return nil, err
 	}
 	// In the event the block is more than an epoch ahead from its
 	// parent state, we have to advance the state forward.
 	parentRoot := blk.Block().ParentRoot()
 	parentState, err = transition.ProcessSlotsUsingNextSlotCache(ctx, parentState, parentRoot[:], blk.Block().Slot())
 	if err != nil {
-		return err
+		return nil, err
 	}
 	idx, err := helpers.BeaconProposerIndex(ctx, parentState)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	if blk.Block().ProposerIndex() != idx {
 		s.setBadBlock(ctx, blockRoot)
-		return errors.New("incorrect proposer index")
+		return nil, errors.New("incorrect proposer index")
 	}
-
-	if err = s.validateBellatrixBeaconBlock(ctx, parentState, blk.Block()); err != nil {
-		if errors.Is(err, ErrOptimisticParent) {
-			return err
-		}
-		// for other kinds of errors, set this block as a bad block.
-		s.setBadBlock(ctx, blockRoot)
-		return err
-	}
-	return nil
+	return parentState, nil
 }
 
 func validateDenebBeaconBlock(blk interfaces.ReadOnlyBeaconBlock) error {