core/txpool: reject blob txs with blob fee cap below the minimum (#29081)

* make blobpool reject blob transactions with fee below the minimum

* core/txpool: some minot nitpick polishes and unified error formats

* core/txpool: do less big.Int constructions with the min blob cap

---------

Co-authored-by: Péter Szilágyi <[email protected]>

Author: Roberto Bayardo

core/txpool/blobpool/blobpool.go

@@ -402,7 +402,7 @@ func (p *BlobPool) Init(gasTip uint64, head *types.Header, reserve txpool.Addres
 	}
 	var (
 		basefee = uint256.MustFromBig(eip1559.CalcBaseFee(p.chain.Config(), p.head))
-		blobfee = uint256.MustFromBig(big.NewInt(params.BlobTxMinBlobGasprice))
+		blobfee = uint256.NewInt(params.BlobTxMinBlobGasprice)
 	)
 	if p.head.ExcessBlobGas != nil {
 		blobfee = uint256.MustFromBig(eip4844.CalcBlobFee(*p.head.ExcessBlobGas))

core/txpool/blobpool/blobpool_test.go

@@ -1228,6 +1228,24 @@ func TestAdd(t *testing.T) {
 				},
 			},
 		},
+		// Blob transactions that don't meet the min blob gas price should be rejected
+		{
+			seeds: map[string]seed{
+				"alice": {balance: 10000000},
+			},
+			adds: []addtx{
+				{ // New account, no previous txs, nonce 0, but blob fee cap too low
+					from: "alice",
+					tx:   makeUnsignedTx(0, 1, 1, 0),
+					err:  txpool.ErrUnderpriced,
+				},
+				{ // Same as above but blob fee cap equals minimum, should be accepted
+					from: "alice",
+					tx:   makeUnsignedTx(0, 1, 1, params.BlobTxMinBlobGasprice),
+					err:  nil,
+				},
+			},
+		},
 	}
 	for i, tt := range tests {
 		// Create a temporary folder for the persistent backend

core/txpool/validation.go

@@ -30,6 +30,12 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+var (
+	// blobTxMinBlobGasPrice is the big.Int version of the configured protocol
+	// parameter to avoid constucting a new big integer for every transaction.
+	blobTxMinBlobGasPrice = big.NewInt(params.BlobTxMinBlobGasprice)
+)
+
 // ValidationOptions define certain differences between transaction validation
 // across the different pools without having to duplicate those checks.
 type ValidationOptions struct {
@@ -101,15 +107,17 @@ func ValidateTransaction(tx *types.Transaction, head *types.Header, signer types
 		return err
 	}
 	if tx.Gas() < intrGas {
-		return fmt.Errorf("%w: needed %v, allowed %v", core.ErrIntrinsicGas, intrGas, tx.Gas())
+		return fmt.Errorf("%w: gas %v, minimum needed %v", core.ErrIntrinsicGas, tx.Gas(), intrGas)
 	}
-	// Ensure the gasprice is high enough to cover the requirement of the calling
-	// pool and/or block producer
+	// Ensure the gasprice is high enough to cover the requirement of the calling pool
 	if tx.GasTipCapIntCmp(opts.MinTip) < 0 {
-		return fmt.Errorf("%w: tip needed %v, tip permitted %v", ErrUnderpriced, opts.MinTip, tx.GasTipCap())
+		return fmt.Errorf("%w: gas tip cap %v, minimum needed %v", ErrUnderpriced, tx.GasTipCap(), opts.MinTip)
 	}
-	// Ensure blob transactions have valid commitments
 	if tx.Type() == types.BlobTxType {
+		// Ensure the blob fee cap satisfies the minimum blob gas price
+		if tx.BlobGasFeeCapIntCmp(blobTxMinBlobGasPrice) < 0 {
+			return fmt.Errorf("%w: blob fee cap %v, minimum needed %v", ErrUnderpriced, tx.BlobGasFeeCap(), blobTxMinBlobGasPrice)
+		}
 		sidecar := tx.BlobTxSidecar()
 		if sidecar == nil {
 			return fmt.Errorf("missing sidecar in blob transaction")
@@ -123,6 +131,7 @@ func ValidateTransaction(tx *types.Transaction, head *types.Header, signer types
 		if len(hashes) > params.MaxBlobGasPerBlock/params.BlobTxBlobGasPerBlob {
 			return fmt.Errorf("too many blobs in transaction: have %d, permitted %d", len(hashes), params.MaxBlobGasPerBlock/params.BlobTxBlobGasPerBlob)
 		}
+		// Ensure commitments, proofs and hashes are valid
 		if err := validateBlobSidecar(hashes, sidecar); err != nil {
 			return err
 		}