DataColumnSidecarsForReconstruct: Add guards (prysmaticlabs#15051)

Author: nalepae

beacon-chain/core/peerdas/reconstruction.go

@@ -97,17 +97,25 @@ func DataColumnSidecarsForReconstruct(
 
 	// Get the column sidecars.
 	sidecars := make([]*ethpb.DataColumnSidecar, 0, fieldparams.NumberOfColumns)
-	for columnIndex := uint64(0); columnIndex < fieldparams.NumberOfColumns; columnIndex++ {
+	for columnIndex := range fieldparams.NumberOfColumns {
 		column := make([]kzg.Cell, 0, blobsCount)
 		kzgProofOfColumn := make([]kzg.Proof, 0, blobsCount)
 
-		for rowIndex := 0; rowIndex < blobsCount; rowIndex++ {
+		for rowIndex := range blobsCount {
 			cellsForRow := cellsAndProofs[rowIndex].Cells
 			proofsForRow := cellsAndProofs[rowIndex].Proofs
 
+			if len(cellsForRow) != fieldparams.NumberOfColumns {
+				return nil, errors.Errorf("cells don't have the expected size: expected %d - actual %d", fieldparams.NumberOfColumns, len(cellsForRow))
+			}
+
 			cell := cellsForRow[columnIndex]
 			column = append(column, cell)
 
+			if len(proofsForRow) != fieldparams.NumberOfColumns {
+				return nil, errors.Errorf("proofs don't have the expected size: expected %d - actual %d", fieldparams.NumberOfColumns, len(proofsForRow))
+			}
+
 			kzgProof := proofsForRow[columnIndex]
 			kzgProofOfColumn = append(kzgProofOfColumn, kzgProof)
 		}
@@ -124,7 +132,7 @@ func DataColumnSidecarsForReconstruct(
 		}
 
 		sidecar := &ethpb.DataColumnSidecar{
-			ColumnIndex:                  columnIndex,
+			ColumnIndex:                  uint64(columnIndex),
 			DataColumn:                   columnBytes,
 			KzgCommitments:               blobKzgCommitments,
 			KzgProof:                     kzgProofOfColumnBytes,

beacon-chain/sync/subscriber_beacon_blocks.go

@@ -75,8 +75,21 @@ func (s *Service) reconstructAndBroadcastBlobs(ctx context.Context, block interf
 }
 
 // reconstructAndBroadcastBlobsInDataColumn reconstructs and broadcasts blobs in data column format for a given beacon block, it also saves data column sidecars into the blob storage.
-func (s *Service) reconstructAndBroadcastBlobsInDataColumn(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock) {
-	blockRoot, err := block.Block().HashTreeRoot()
+func (s *Service) reconstructAndBroadcastBlobsInDataColumn(ctx context.Context, roSignedBlock interfaces.ReadOnlySignedBeaconBlock) {
+	block := roSignedBlock.Block()
+
+	kzgCommitments, err := block.Body().BlobKzgCommitments()
+	if err != nil {
+		log.WithError(err).Error("Failed to read commitments from block")
+		return
+	}
+
+	if len(kzgCommitments) == 0 {
+		// No blobs to reconstruct.
+		return
+	}
+
+	blockRoot, err := block.HashTreeRoot()
 	if err != nil {
 		log.WithError(err).Error("Failed to calculate block root")
 		return
@@ -87,7 +100,7 @@ func (s *Service) reconstructAndBroadcastBlobsInDataColumn(ctx context.Context,
 	}
 
 	// when this function is called, it's from the time when the block is received, so in almost all situations we need to get the data column from EL instead of the blob storage.
-	sidecars, err := s.cfg.executionReconstructor.ReconstructDataColumnSidecars(ctx, block, blockRoot)
+	sidecars, err := s.cfg.executionReconstructor.ReconstructDataColumnSidecars(ctx, roSignedBlock, blockRoot)
 	if err != nil {
 		log.WithError(err).Debug("Cannot reconstruct data column sidecars after receiving the block")
 		return

beacon-chain/sync/subscriber_beacon_blocks_test.go

@@ -218,10 +218,6 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 			Genesis: time.Now(),
 		}
 
-		b := util.NewBeaconBlockFulu()
-		sb, err := blocks.NewSignedBeaconBlock(b)
-		require.NoError(t, err)
-
 		allColumns := make([]blocks.VerifiedRODataColumn, 128)
 		for i := range allColumns {
 			rod, err := blocks.NewRODataColumn(
@@ -244,15 +240,18 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 		tests := []struct {
 			name                    string
 			dataColumnSidecars      []blocks.VerifiedRODataColumn
+			blobCount               int
 			expectedDataColumnCount int
 		}{
 			{
 				name:                    "Constructed 0 data columns with no blobs",
+				blobCount:               0,
 				dataColumnSidecars:      nil,
 				expectedDataColumnCount: 0,
 			},
 			{
 				name:                    "Constructed 128 data columns with all blobs",
+				blobCount:               1,
 				dataColumnSidecars:      allColumns,
 				expectedDataColumnCount: 8, // default is 8
 			},
@@ -276,6 +275,19 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 					receivedDataColumnsFromRoot: gcache.New(1*time.Minute, 2*time.Minute),
 					storedDataColumnsFromRoot:   gcache.New(1*time.Minute, 2*time.Minute),
 				}
+
+				kzgCommitments := make([][]byte, 0, tt.blobCount)
+				for range tt.blobCount {
+					kzgCommitment := make([]byte, 48)
+					kzgCommitments = append(kzgCommitments, kzgCommitment)
+				}
+
+				b := util.NewBeaconBlockFulu()
+				b.Block.Body.BlobKzgCommitments = kzgCommitments
+
+				sb, err := blocks.NewSignedBeaconBlock(b)
+				require.NoError(t, err)
+
 				s.reconstructAndBroadcastBlobs(context.Background(), sb)
 				require.Equal(t, tt.expectedDataColumnCount, len(chainService.DataColumns))
 			})