feat(blobpool): add explicit max blob count limit

core/txpool/blobpool/blobpool.go

@@ -62,6 +62,12 @@ const (
 	// limit can never hurt.
 	txMaxSize = 1024 * 1024
 
+	// maxBlobsPerTx is the maximum number of blobs that a single transaction can
+	// carry. We choose a smaller limit than the protocol-permitted MaxBlobsPerBlock
+	// in order to ensure network and txpool stability.
+	// Note: if you increase this, validation will fail on txMaxSize.
+	maxBlobsPerTx = 7
+
 	// maxTxsPerAccount is the maximum number of blob transactions admitted from
 	// a single account. The limit is enforced to minimize the DoS potential of
 	// a private tx cancelling publicly propagated blobs.
@@ -1099,6 +1105,7 @@ func (p *BlobPool) ValidateTxBasics(tx *types.Transaction) error {
 		Accept:       1 << types.BlobTxType,
 		MaxSize:      txMaxSize,
 		MinTip:       p.gasTip.ToBig(),
+		MaxBlobCount: maxBlobsPerTx,
 	}
 	return txpool.ValidateTransaction(tx, p.head, p.signer, opts)
 }

core/txpool/blobpool/blobpool_test.go

@@ -43,6 +43,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/holiman/billy"
 	"github.com/holiman/uint256"
+	"github.com/stretchr/testify/assert"
 )
 
 var (
@@ -1142,6 +1143,63 @@ func TestChangingSlotterSize(t *testing.T) {
 	}
 }
 
+// TestBlobCountLimit tests the blobpool enforced limits on the max blob count.
+func TestBlobCountLimit(t *testing.T) {
+	// Create a temporary folder for the persistent backend
+	storage := t.TempDir()
+
+	// Create transactions from a few accounts.
+	var (
+		key1, _ = crypto.GenerateKey()
+		key2, _ = crypto.GenerateKey()
+
+		addr1 = crypto.PubkeyToAddress(key1.PublicKey)
+		addr2 = crypto.PubkeyToAddress(key2.PublicKey)
+
+		tx1 = makeMultiBlobTx(0, 1, 1000, 100, 7, key1)
+		tx2 = makeMultiBlobTx(0, 1, 800, 70, 8, key2)
+	)
+
+	statedb, _ := state.New(types.EmptyRootHash, state.NewDatabaseForTesting())
+	statedb.AddBalance(addr1, uint256.NewInt(1_000_000_000), tracing.BalanceChangeUnspecified)
+	statedb.AddBalance(addr2, uint256.NewInt(1_000_000_000), tracing.BalanceChangeUnspecified)
+	statedb.Commit(0, true, false)
+
+	// Make Prague-enabled custom chain config.
+	cancunTime := uint64(0)
+	pragueTime := uint64(0)
+	config := &params.ChainConfig{
+		ChainID:     big.NewInt(1),
+		LondonBlock: big.NewInt(0),
+		BerlinBlock: big.NewInt(0),
+		CancunTime:  &cancunTime,
+		PragueTime:  &pragueTime,
+		BlobScheduleConfig: &params.BlobScheduleConfig{
+			Cancun: params.DefaultCancunBlobConfig,
+			Prague: params.DefaultPragueBlobConfig,
+		},
+	}
+	chain := &testBlockChain{
+		config:  config,
+		basefee: uint256.NewInt(1050),
+		blobfee: uint256.NewInt(105),
+		statedb: statedb,
+	}
+	pool := New(Config{Datadir: storage}, chain, nil)
+	if err := pool.Init(1, chain.CurrentBlock(), newReserver()); err != nil {
+		t.Fatalf("failed to create blob pool: %v", err)
+	}
+
+	// Attempt to add transactions.
+	errs := pool.Add([]*types.Transaction{tx1, tx2}, true)
+	assert.Equal(t, 2, len(errs))
+	assert.NoError(t, errs[0])
+	assert.EqualError(t, errs[1], "too many blobs in transaction: have 8, permitted 7")
+
+	verifyPoolInternals(t, pool)
+	pool.Close()
+}
+
 // Tests that adding transaction will correctly store it in the persistent store
 // and update all the indices.
 //

core/txpool/legacypool/legacypool.go

@@ -573,6 +573,7 @@ func (pool *LegacyPool) ValidateTxBasics(tx *types.Transaction) error {
 			1<<types.SetCodeTxType,
 		MaxSize:      txMaxSize,
 		MinTip:       pool.gasTip.Load().ToBig(),
+		MaxBlobCount: 0,
 	}
 	return txpool.ValidateTransaction(tx, pool.currentHead.Load(), pool.signer, opts)
 }

core/txpool/validation.go

@@ -44,6 +44,7 @@ type ValidationOptions struct {
 
 	Accept       uint8    // Bitmap of transaction types that should be accepted for the calling pool
 	MaxSize      uint64   // Maximum size of a transaction that the caller can meaningfully handle
+	MaxBlobCount int      // Maximum number of blobs allowed per transaction
 	MinTip       *big.Int // Minimum gas tip needed to allow a transaction into the caller pool
 }
 
@@ -63,6 +64,9 @@ func ValidateTransaction(tx *types.Transaction, head *types.Header, signer types
 	if opts.Accept&(1<<tx.Type()) == 0 {
 		return fmt.Errorf("%w: tx type %v not supported by this pool", core.ErrTxTypeNotSupported, tx.Type())
 	}
+	if blobCount := len(tx.BlobHashes()); blobCount > opts.MaxBlobCount {
+		return fmt.Errorf("too many blobs in transaction: have %d, permitted %d", blobCount, opts.MaxBlobCount)
+	}
 	// Before performing any expensive validations, sanity check that the tx is
 	// smaller than the maximum limit the pool can meaningfully handle
 	if tx.Size() > opts.MaxSize {