core/types: enhance BlobTx decode to validate blob sidecar version

[islishude]

Don't let v0 blob use v1 encoding structure.

[rjl493456442]

nitpick

diff --git a/core/types/tx_blob.go b/core/types/tx_blob.go
index bbfd3c98db..464e294218 100644
--- a/core/types/tx_blob.go
+++ b/core/types/tx_blob.go
@@ -401,13 +401,18 @@ func (tx *BlobTx) decode(input []byte) error {
 	if err != nil {
 		return err
 	}
-	var payload blobTxWithBlobs
+	var (
+		payload blobTxWithBlobs
+		version byte
+	)
 	if secondElemKind == rlp.List {
 		// No version byte: blob sidecar v0.
 		payload = new(blobTxWithBlobsV0)
+		version = BlobSidecarVersion0
 	} else {
 		// It has a version byte. Decode as v1, version is checked by assign()
 		payload = new(blobTxWithBlobsV1)
+		version = BlobSidecarVersion1
 	}
 	if err := rlp.DecodeBytes(input, payload); err != nil {
 		return err
@@ -416,6 +421,9 @@ func (tx *BlobTx) decode(input []byte) error {
 	if err := payload.assign(sc); err != nil {
 		return err
 	}
+	if sc.Version != version {
+		return fmt.Errorf("unexpected sidecar version, want: %d, got: %d", version, sc.Version)
+	}
 	*tx = *payload.tx()
 	tx.Sidecar = sc
 	return nil

[rjl493456442]

Thanks for catching it, and I would appreciate if you can also add the associated unit test.

[rjl493456442]

I just realized that we do have the validation for version tag.

func (btx *blobTxWithBlobsV1) assign(sc *BlobTxSidecar) error {
	if btx.Version != BlobSidecarVersion1 {
		return fmt.Errorf("unsupported blob tx version %d", btx.Version)
	}
	sc.Version = BlobSidecarVersion1
	sc.Blobs = btx.Blobs
	sc.Commitments = btx.Commitments
	sc.Proofs = btx.Proofs
	return nil
}

I think the extra validation you have added is redundant. Close it.