core/types: support for optional blob sidecar in BlobTx (#27841)

This PR removes the newly added txpool.Transaction wrapper type, and instead adds a way
of keeping the blob sidecar within types.Transaction. It's better this way because most
code in go-ethereum does not care about blob transactions, and probably never will. This
will start mattering especially on the client side of RPC, where all APIs are based on
types.Transaction. Users need to be able to use the same signing flows they already
have.

However, since blobs are only allowed in some places but not others, we will now need to
add checks to avoid creating invalid blocks. I'm still trying to figure out the best place
to do some of these. The way I have it currently is as follows:

- In block validation (import), txs are verified not to have a blob sidecar.
- In miner, we strip off the sidecar when committing the transaction into the block.
- In TxPool validation, txs must have a sidecar to be added into the blobpool.
  - Note there is a special case here: when transactions are re-added because of a chain
    reorg, we cannot use the transactions gathered from the old chain blocks as-is,
    because they will be missing their blobs. This was previously handled by storing the
    blobs into the 'blobpool limbo'. The code has now changed to store the full
    transaction in the limbo instead, but it might be confusing for code readers why we're
    not simply adding the types.Transaction we already have.

Code changes summary:

- txpool.Transaction removed and all uses replaced by types.Transaction again
- blobpool now stores types.Transaction instead of defining its own blobTx format for storage
- the blobpool limbo now stores types.Transaction instead of storing only the blobs
- checks to validate the presence/absence of the blob sidecar added in certain critical places

core/txpool/validation.go

@@ -46,7 +46,7 @@ type ValidationOptions struct {
 //
 // This check is public to allow different transaction pools to check the basic
 // rules without duplicating code and running the risk of missed updates.
-func ValidateTransaction(tx *types.Transaction, blobs []kzg4844.Blob, commits []kzg4844.Commitment, proofs []kzg4844.Proof, head *types.Header, signer types.Signer, opts *ValidationOptions) error {
+func ValidateTransaction(tx *types.Transaction, head *types.Header, signer types.Signer, opts *ValidationOptions) error {
 	// Ensure transactions not implemented by the calling pool are rejected
 	if opts.Accept&(1<<tx.Type()) == 0 {
 		return fmt.Errorf("%w: tx type %v not supported by this pool", core.ErrTxTypeNotSupported, tx.Type())
@@ -110,6 +110,10 @@ func ValidateTransaction(tx *types.Transaction, blobs []kzg4844.Blob, commits []
 	}
 	// Ensure blob transactions have valid commitments
 	if tx.Type() == types.BlobTxType {
+		sidecar := tx.BlobTxSidecar()
+		if sidecar == nil {
+			return fmt.Errorf("missing sidecar in blob transaction")
+		}
 		// Ensure the number of items in the blob transaction and vairous side
 		// data match up before doing any expensive validations
 		hashes := tx.BlobHashes()
@@ -119,37 +123,44 @@ func ValidateTransaction(tx *types.Transaction, blobs []kzg4844.Blob, commits []
 		if len(hashes) > params.BlobTxMaxBlobGasPerBlock/params.BlobTxBlobGasPerBlob {
 			return fmt.Errorf("too many blobs in transaction: have %d, permitted %d", len(hashes), params.BlobTxMaxBlobGasPerBlock/params.BlobTxBlobGasPerBlob)
 		}
-		if len(blobs) != len(hashes) {
-			return fmt.Errorf("invalid number of %d blobs compared to %d blob hashes", len(blobs), len(hashes))
+		if err := validateBlobSidecar(hashes, sidecar); err != nil {
+			return err
 		}
-		if len(commits) != len(hashes) {
-			return fmt.Errorf("invalid number of %d blob commitments compared to %d blob hashes", len(commits), len(hashes))
-		}
-		if len(proofs) != len(hashes) {
-			return fmt.Errorf("invalid number of %d blob proofs compared to %d blob hashes", len(proofs), len(hashes))
-		}
-		// Blob quantities match up, validate that the provers match with the
-		// transaction hash before getting to the cryptography
-		hasher := sha256.New()
-		for i, want := range hashes {
-			hasher.Write(commits[i][:])
-			hash := hasher.Sum(nil)
-			hasher.Reset()
+	}
+	return nil
+}
 
-			var vhash common.Hash
-			vhash[0] = params.BlobTxHashVersion
-			copy(vhash[1:], hash[1:])
+func validateBlobSidecar(hashes []common.Hash, sidecar *types.BlobTxSidecar) error {
+	if len(sidecar.Blobs) != len(hashes) {
+		return fmt.Errorf("invalid number of %d blobs compared to %d blob hashes", len(sidecar.Blobs), len(hashes))
+	}
+	if len(sidecar.Commitments) != len(hashes) {
+		return fmt.Errorf("invalid number of %d blob commitments compared to %d blob hashes", len(sidecar.Commitments), len(hashes))
+	}
+	if len(sidecar.Proofs) != len(hashes) {
+		return fmt.Errorf("invalid number of %d blob proofs compared to %d blob hashes", len(sidecar.Proofs), len(hashes))
+	}
+	// Blob quantities match up, validate that the provers match with the
+	// transaction hash before getting to the cryptography
+	hasher := sha256.New()
+	for i, want := range hashes {
+		hasher.Write(sidecar.Commitments[i][:])
+		hash := hasher.Sum(nil)
+		hasher.Reset()
 
-			if vhash != want {
-				return fmt.Errorf("blob %d: computed hash %#x mismatches transaction one %#x", i, vhash, want)
-			}
+		var vhash common.Hash
+		vhash[0] = params.BlobTxHashVersion
+		copy(vhash[1:], hash[1:])
+
+		if vhash != want {
+			return fmt.Errorf("blob %d: computed hash %#x mismatches transaction one %#x", i, vhash, want)
 		}
-		// Blob commitments match with the hashes in the transaction, verify the
-		// blobs themselves via KZG
-		for i := range blobs {
-			if err := kzg4844.VerifyBlobProof(blobs[i], commits[i], proofs[i]); err != nil {
-				return fmt.Errorf("invalid blob %d: %v", i, err)
-			}
+	}
+	// Blob commitments match with the hashes in the transaction, verify the
+	// blobs themselves via KZG
+	for i := range sidecar.Blobs {
+		if err := kzg4844.VerifyBlobProof(sidecar.Blobs[i], sidecar.Commitments[i], sidecar.Proofs[i]); err != nil {
+			return fmt.Errorf("invalid blob %d: %v", i, err)
 		}
 	}
 	return nil