core, light: allow zero cost txs from inexistent accounts too

core/tx_pool.go

@@ -41,7 +41,6 @@ var (
 	ErrNonce             = errors.New("Nonce too low")
 	ErrCheap             = errors.New("Gas price too low for acceptance")
 	ErrBalance           = errors.New("Insufficient balance")
-	ErrNonExistentAccount = errors.New("Account does not exist or account balance too low")
 	ErrInsufficientFunds = errors.New("Insufficient funds for gas * price + value")
 	ErrIntrinsicGas      = errors.New("Intrinsic gas too low")
 	ErrGasLimit          = errors.New("Exceeds block gas limit")
@@ -287,13 +286,6 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 	if err != nil {
 		return ErrInvalidSender
 	}
-
-	// Make sure the account exist. Non existent accounts
-	// haven't got funds and well therefor never pass.
-	if !currentState.Exist(from) {
-		return ErrNonExistentAccount
-	}
-
 	// Last but not least check for nonce errors
 	if currentState.GetNonce(from) > tx.Nonce() {
 		return ErrNonce

core/tx_pool_test.go

@@ -129,10 +129,6 @@ func TestInvalidTransactions(t *testing.T) {
 	pool, key := setupTxPool()
 
 	tx := transaction(0, big.NewInt(100), key)
-	if err := pool.Add(tx); err != ErrNonExistentAccount {
-		t.Error("expected", ErrNonExistentAccount)
-	}
-
 	from, _ := deriveSender(tx)
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1))

light/txpool.go

@@ -346,19 +346,8 @@ func (pool *TxPool) validateTx(ctx context.Context, tx *types.Transaction) error
 	if from, err = types.Sender(pool.signer, tx); err != nil {
 		return core.ErrInvalidSender
 	}
-
-	// Make sure the account exist. Non existent accounts
-	// haven't got funds and well therefor never pass.
-	currentState := pool.currentState()
-	if h, err := currentState.HasAccount(ctx, from); err == nil {
-		if !h {
-			return core.ErrNonExistentAccount
-		}
-	} else {
-		return err
-	}
-
 	// Last but not least check for nonce errors
+	currentState := pool.currentState()
 	if n, err := currentState.GetNonce(ctx, from); err == nil {
 		if n > tx.Nonce() {
 			return core.ErrNonce