state_processor_test.go

// (c) 2019-2021, Ava Labs, Inc.
//
// This file is a derived work, based on the go-ethereum library whose original
// notices appear below.
//
// It is distributed under a license compatible with the licensing terms of the
// original code from which it is derived.
//
// Much love to the original authors for their work.
// **********
// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
	"math/big"
	"testing"

	"github.com/ava-labs/subnet-evm/consensus"
	"github.com/ava-labs/subnet-evm/consensus/dummy"
	"github.com/ava-labs/subnet-evm/core/rawdb"
	"github.com/ava-labs/subnet-evm/core/types"
	"github.com/ava-labs/subnet-evm/core/vm"
	"github.com/ava-labs/subnet-evm/params"
	"github.com/ava-labs/subnet-evm/precompile/contracts/txallowlist"
	"github.com/ava-labs/subnet-evm/trie"
	"github.com/ava-labs/subnet-evm/utils"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"golang.org/x/crypto/sha3"
)

var (
	cpcfg      = *params.TestChainConfig
	config     = &cpcfg
	signer     = types.LatestSigner(config)
	testKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
)

func makeTx(nonce uint64, to common.Address, amount *big.Int, gasLimit uint64, gasPrice *big.Int, data []byte) *types.Transaction {
	tx, _ := types.SignTx(types.NewTransaction(nonce, to, amount, gasLimit, gasPrice, data), signer, testKey)
	return tx
}

func mkDynamicTx(nonce uint64, to common.Address, gasLimit uint64, gasTipCap, gasFeeCap *big.Int) *types.Transaction {
	tx, _ := types.SignTx(types.NewTx(&types.DynamicFeeTx{
		Nonce:     nonce,
		GasTipCap: gasTipCap,
		GasFeeCap: gasFeeCap,
		Gas:       gasLimit,
		To:        &to,
		Value:     big.NewInt(0),
	}), signer, testKey)
	return tx
}

func mkDynamicCreationTx(nonce uint64, gasLimit uint64, gasTipCap, gasFeeCap *big.Int, data []byte) *types.Transaction {
	tx, _ := types.SignTx(types.NewTx(&types.DynamicFeeTx{
		Nonce:     nonce,
		GasTipCap: gasTipCap,
		GasFeeCap: gasFeeCap,
		Gas:       gasLimit,
		Value:     big.NewInt(0),
		Data:      data,
	}), signer, testKey)
	return tx
}

func u64(val uint64) *uint64 { return &val }

// TestStateProcessorErrors tests the output from the 'core' errors
// as defined in core/error.go. These errors are generated when the
// blockchain imports bad blocks, meaning blocks which have valid headers but
// contain invalid transactions
func TestStateProcessorErrors(t *testing.T) {
	config.FeeConfig.MinBaseFee = big.NewInt(params.TestMaxBaseFee)
	{ // Tests against a 'recent' chain definition
		var (
			db    = rawdb.NewMemoryDatabase()
			gspec = &Genesis{
				Config: config,
				Alloc: GenesisAlloc{
					common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7"): GenesisAccount{
						Balance: big.NewInt(4000000000000000000), // 4 ether
						Nonce:   0,
					},
				},
				GasLimit: params.TestChainConfig.FeeConfig.GasLimit.Uint64(),
			}
			blockchain, _ = NewBlockChain(db, DefaultCacheConfig, gspec, dummy.NewCoinbaseFaker(), vm.Config{}, common.Hash{}, false)
		)
		defer blockchain.Stop()
		bigNumber := new(big.Int).SetBytes(common.FromHex("0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"))
		tooBigNumber := new(big.Int).Set(bigNumber)
		tooBigNumber.Add(tooBigNumber, common.Big1)
		for i, tt := range []struct {
			txs  []*types.Transaction
			want string
		}{
			{ // ErrNonceTooLow
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(0), params.TxGas, big.NewInt(225000000000), nil),
					makeTx(0, common.Address{}, big.NewInt(0), params.TxGas, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 1 [0x734d821c990099c6ae42d78072aadd3931c35328cf03ef4cf5b2a4ac9c398522]: nonce too low: address 0x71562b71999873DB5b286dF957af199Ec94617F7, tx: 0 state: 1",
			},
			{ // ErrNonceTooHigh
				txs: []*types.Transaction{
					makeTx(100, common.Address{}, big.NewInt(0), params.TxGas, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 0 [0x0df36254cfbef8ed6961b38fc68aecc777177166144c8a56bc8919e23a559bf4]: nonce too high: address 0x71562b71999873DB5b286dF957af199Ec94617F7, tx: 100 state: 0",
			},
			{ // ErrGasLimitReached
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(0), 15000001, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 0 [0x1354370681d2ab68247073d889736f8be4a8d87e35956f0c02658d3670803a66]: gas limit reached",
			},
			{ // ErrInsufficientFundsForTransfer
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(4000000000000000000), params.TxGas, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 0 [0x1632f2bffcce84a5c91dd8ab2016128fccdbcfbe0485d2c67457e1c793c72a4b]: insufficient funds for gas * price + value: address 0x71562b71999873DB5b286dF957af199Ec94617F7 have 4000000000000000000 want 4004725000000000000",
			},
			{ // ErrInsufficientFunds
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(0), params.TxGas, big.NewInt(900000000000000000), nil),
				},
				want: "could not apply tx 0 [0x4a69690c4b0cd85e64d0d9ea06302455b01e10a83db964d60281739752003440]: insufficient funds for gas * price + value: address 0x71562b71999873DB5b286dF957af199Ec94617F7 have 4000000000000000000 want 18900000000000000000000",
			},
			// ErrGasUintOverflow
			// One missing 'core' error is ErrGasUintOverflow: "gas uint64 overflow",
			// In order to trigger that one, we'd have to allocate a _huge_ chunk of data, such that the
			// multiplication len(data) +gas_per_byte overflows uint64. Not testable at the moment
			{ // ErrIntrinsicGas
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(0), params.TxGas-1000, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 0 [0x2fc3e3b5cc26917d413e26983fe189475f47d4f0757e32aaa5561fcb9c9dc432]: intrinsic gas too low: have 20000, want 21000",
			},
			{ // ErrGasLimitReached
				txs: []*types.Transaction{
					makeTx(0, common.Address{}, big.NewInt(0), params.TxGas*762, big.NewInt(225000000000), nil),
				},
				want: "could not apply tx 0 [0x76c07cc2b32007eb1a9c3fa066d579a3d77ec4ecb79bbc266624a601d7b08e46]: gas limit reached",
			},
			{ // ErrFeeCapTooLow
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, big.NewInt(0), big.NewInt(0)),
				},
				want: "could not apply tx 0 [0xc4ab868fef0c82ae0387b742aee87907f2d0fc528fc6ea0a021459fb0fc4a4a8]: max fee per gas less than block base fee: address 0x71562b71999873DB5b286dF957af199Ec94617F7, maxFeePerGas: 0 baseFee: 225000000000",
			},
			{ // ErrTipVeryHigh
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, tooBigNumber, big.NewInt(1)),
				},
				want: "could not apply tx 0 [0x15b8391b9981f266b32f3ab7da564bbeb3d6c21628364ea9b32a21139f89f712]: max priority fee per gas higher than 2^256-1: address 0x71562b71999873DB5b286dF957af199Ec94617F7, maxPriorityFeePerGas bit length: 257",
			},
			{ // ErrFeeCapVeryHigh
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, big.NewInt(1), tooBigNumber),
				},
				want: "could not apply tx 0 [0x48bc299b83fdb345c57478f239e89814bb3063eb4e4b49f3b6057a69255c16bd]: max fee per gas higher than 2^256-1: address 0x71562b71999873DB5b286dF957af199Ec94617F7, maxFeePerGas bit length: 257",
			},
			{ // ErrTipAboveFeeCap
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, big.NewInt(2), big.NewInt(1)),
				},
				want: "could not apply tx 0 [0xf987a31ff0c71895780a7612f965a0c8b056deb54e020bb44fa478092f14c9b4]: max priority fee per gas higher than max fee per gas: address 0x71562b71999873DB5b286dF957af199Ec94617F7, maxPriorityFeePerGas: 2, maxFeePerGas: 1",
			},
			{ // ErrInsufficientFunds
				// Available balance:           1000000000000000000
				// Effective cost:                   18375000021000
				// FeeCap * gas:                1050000000000000000
				// This test is designed to have the effective cost be covered by the balance, but
				// the extended requirement on FeeCap*gas < balance to fail
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, big.NewInt(1), big.NewInt(200000000000000)),
				},
				want: "could not apply tx 0 [0xa3840aa3cad37eec8607b9f4846813d4a80e70b462a793fa21f64138156f849b]: insufficient funds for gas * price + value: address 0x71562b71999873DB5b286dF957af199Ec94617F7 have 4000000000000000000 want 4200000000000000000",
			},
			{ // Another ErrInsufficientFunds, this one to ensure that feecap/tip of max u256 is allowed
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas, bigNumber, bigNumber),
				},
				want: "could not apply tx 0 [0xd82a0c2519acfeac9a948258c47e784acd20651d9d80f9a1c67b4137651c3a24]: insufficient funds for gas * price + value: address 0x71562b71999873DB5b286dF957af199Ec94617F7 have 4000000000000000000 want 2431633873983640103894990685182446064918669677978451844828609264166175722438635000",
			},
		} {
			block := GenerateBadBlock(gspec.ToBlock(), dummy.NewCoinbaseFaker(), tt.txs, gspec.Config)
			_, err := blockchain.InsertChain(types.Blocks{block})
			if err == nil {
				t.Fatal("block imported without errors")
			}
			if have, want := err.Error(), tt.want; have != want {
				t.Errorf("test %d:\nhave \"%v\"\nwant \"%v\"\n", i, have, want)
			}
		}
	}

	// ErrTxTypeNotSupported, For this, we need an older chain
	{
		var (
			db    = rawdb.NewMemoryDatabase()
			gspec = &Genesis{
				Config: &params.ChainConfig{
					ChainID:             big.NewInt(1),
					FeeConfig:           params.DefaultFeeConfig,
					HomesteadBlock:      big.NewInt(0),
					EIP150Block:         big.NewInt(0),
					EIP155Block:         big.NewInt(0),
					EIP158Block:         big.NewInt(0),
					ByzantiumBlock:      big.NewInt(0),
					ConstantinopleBlock: big.NewInt(0),
					PetersburgBlock:     big.NewInt(0),
					IstanbulBlock:       big.NewInt(0),
					MuirGlacierBlock:    big.NewInt(0),
				},
				Alloc: GenesisAlloc{
					common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7"): GenesisAccount{
						Balance: big.NewInt(1000000000000000000), // 1 ether
						Nonce:   0,
					},
				},
				GasLimit: params.TestChainConfig.FeeConfig.GasLimit.Uint64(),
			}
			blockchain, _ = NewBlockChain(db, DefaultCacheConfig, gspec, dummy.NewCoinbaseFaker(), vm.Config{}, common.Hash{}, false)
		)
		defer blockchain.Stop()
		for i, tt := range []struct {
			txs  []*types.Transaction
			want string
		}{
			{ // ErrTxTypeNotSupported
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas-1000, big.NewInt(0), big.NewInt(0)),
				},
				want: "could not apply tx 0 [0x88626ac0d53cb65308f2416103c62bb1f18b805573d4f96a3640bbbfff13c14f]: transaction type not supported",
			},
		} {
			block := GenerateBadBlock(gspec.ToBlock(), dummy.NewCoinbaseFaker(), tt.txs, gspec.Config)
			_, err := blockchain.InsertChain(types.Blocks{block})
			if err == nil {
				t.Fatal("block imported without errors")
			}
			if have, want := err.Error(), tt.want; have != want {
				t.Errorf("test %d:\nhave \"%v\"\nwant \"%v\"\n", i, have, want)
			}
		}
	}

	// ErrSenderNoEOA, for this we need the sender to have contract code
	{
		var (
			db    = rawdb.NewMemoryDatabase()
			gspec = &Genesis{
				Config: config,
				Alloc: GenesisAlloc{
					common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7"): GenesisAccount{
						Balance: big.NewInt(1000000000000000000), // 1 ether
						Nonce:   0,
						Code:    common.FromHex("0xB0B0FACE"),
					},
				},
				GasLimit: params.TestChainConfig.FeeConfig.GasLimit.Uint64(),
			}
			blockchain, _ = NewBlockChain(db, DefaultCacheConfig, gspec, dummy.NewCoinbaseFaker(), vm.Config{}, common.Hash{}, false)
		)
		defer blockchain.Stop()
		for i, tt := range []struct {
			txs  []*types.Transaction
			want string
		}{
			{ // ErrSenderNoEOA
				txs: []*types.Transaction{
					mkDynamicTx(0, common.Address{}, params.TxGas-1000, big.NewInt(0), big.NewInt(0)),
				},
				want: "could not apply tx 0 [0x88626ac0d53cb65308f2416103c62bb1f18b805573d4f96a3640bbbfff13c14f]: sender not an eoa: address 0x71562b71999873DB5b286dF957af199Ec94617F7, codehash: 0x9280914443471259d4570a8661015ae4a5b80186dbc619658fb494bebc3da3d1",
			},
		} {
			block := GenerateBadBlock(gspec.ToBlock(), dummy.NewCoinbaseFaker(), tt.txs, gspec.Config)
			_, err := blockchain.InsertChain(types.Blocks{block})
			if err == nil {
				t.Fatal("block imported without errors")
			}
			if have, want := err.Error(), tt.want; have != want {
				t.Errorf("test %d:\nhave \"%v\"\nwant \"%v\"\n", i, have, want)
			}
		}
	}

	// ErrMaxInitCodeSizeExceeded, for this we need extra Shanghai (DUpgrade/EIP-3860) enabled.
	{
		var (
			db    = rawdb.NewMemoryDatabase()
			gspec = &Genesis{
				Config: &params.ChainConfig{
					ChainID:             big.NewInt(1),
					HomesteadBlock:      big.NewInt(0),
					EIP150Block:         big.NewInt(0),
					EIP155Block:         big.NewInt(0),
					EIP158Block:         big.NewInt(0),
					ByzantiumBlock:      big.NewInt(0),
					ConstantinopleBlock: big.NewInt(0),
					PetersburgBlock:     big.NewInt(0),
					IstanbulBlock:       big.NewInt(0),
					MuirGlacierBlock:    big.NewInt(0),
					MandatoryNetworkUpgrades: params.MandatoryNetworkUpgrades{
						SubnetEVMTimestamp: utils.NewUint64(0),
						DUpgradeTimestamp:  utils.NewUint64(0),
					},
					FeeConfig: params.DefaultFeeConfig,
				},
				Alloc: GenesisAlloc{
					common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7"): GenesisAccount{
						Balance: big.NewInt(1000000000000000000), // 1 ether
						Nonce:   0,
					},
				},
				GasLimit: params.DefaultFeeConfig.GasLimit.Uint64(),
			}
			blockchain, _  = NewBlockChain(db, DefaultCacheConfig, gspec, dummy.NewCoinbaseFaker(), vm.Config{}, common.Hash{}, false)
			tooBigInitCode = [params.MaxInitCodeSize + 1]byte{}
			smallInitCode  = [320]byte{}
		)
		defer blockchain.Stop()
		for i, tt := range []struct {
			txs  []*types.Transaction
			want string
		}{
			{ // ErrMaxInitCodeSizeExceeded
				txs: []*types.Transaction{
					mkDynamicCreationTx(0, 500000, common.Big0, big.NewInt(params.TestInitialBaseFee), tooBigInitCode[:]),
				},
				want: "could not apply tx 0 [0x18a05f40f29ff16d5287f6f88b21c9f3c7fbc268f707251144996294552c4cd6]: max initcode size exceeded: code size 49153 limit 49152",
			},
			{ // ErrIntrinsicGas: Not enough gas to cover init code
				txs: []*types.Transaction{
					mkDynamicCreationTx(0, 54299, common.Big0, big.NewInt(params.TestInitialBaseFee), smallInitCode[:]),
				},
				want: "could not apply tx 0 [0x849278f616d51ab56bba399551317213ce7a10e4d9cbc3d14bb663e50cb7ab99]: intrinsic gas too low: have 54299, want 54300",
			},
		} {
			block := GenerateBadBlock(gspec.ToBlock(), dummy.NewCoinbaseFaker(), tt.txs, gspec.Config)
			_, err := blockchain.InsertChain(types.Blocks{block})
			if err == nil {
				t.Fatal("block imported without errors")
			}
			if have, want := err.Error(), tt.want; have != want {
				t.Errorf("test %d:\nhave \"%v\"\nwant \"%v\"\n", i, have, want)
			}
		}
	}
}

// TestBadTxAllowListBlock tests the output generated when the
// blockchain imports a bad block with a transaction from a
// non-whitelisted TX Allow List address.
func TestBadTxAllowListBlock(t *testing.T) {
	var (
		db       = rawdb.NewMemoryDatabase()
		testAddr = common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7")

		config = &params.ChainConfig{
			ChainID:             big.NewInt(1),
			FeeConfig:           params.DefaultFeeConfig,
			HomesteadBlock:      big.NewInt(0),
			EIP150Block:         big.NewInt(0),
			EIP155Block:         big.NewInt(0),
			EIP158Block:         big.NewInt(0),
			ByzantiumBlock:      big.NewInt(0),
			ConstantinopleBlock: big.NewInt(0),
			PetersburgBlock:     big.NewInt(0),
			IstanbulBlock:       big.NewInt(0),
			MuirGlacierBlock:    big.NewInt(0),
			MandatoryNetworkUpgrades: params.MandatoryNetworkUpgrades{
				SubnetEVMTimestamp: utils.NewUint64(0),
			},
			GenesisPrecompiles: params.Precompiles{
				txallowlist.ConfigKey: txallowlist.NewConfig(utils.NewUint64(0), nil, nil, nil),
			},
		}
		signer     = types.LatestSigner(config)
		testKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")

		gspec = &Genesis{
			Config: config,
			Alloc: GenesisAlloc{
				testAddr: GenesisAccount{
					Balance: big.NewInt(1000000000000000000), // 1 ether
					Nonce:   0,
				},
			},
			GasLimit: config.FeeConfig.GasLimit.Uint64(),
		}
		blockchain, _ = NewBlockChain(db, DefaultCacheConfig, gspec, dummy.NewCoinbaseFaker(), vm.Config{}, common.Hash{}, false)
	)
	defer blockchain.Stop()

	mkDynamicTx := func(nonce uint64, to common.Address, gasLimit uint64, gasTipCap, gasFeeCap *big.Int) *types.Transaction {
		tx, _ := types.SignTx(types.NewTx(&types.DynamicFeeTx{
			Nonce:     nonce,
			GasTipCap: gasTipCap,
			GasFeeCap: gasFeeCap,
			Gas:       gasLimit,
			To:        &to,
			Value:     big.NewInt(0),
		}), signer, testKey)
		return tx
	}

	defer blockchain.Stop()
	for i, tt := range []struct {
		txs  []*types.Transaction
		want string
	}{
		{ // Nonwhitelisted address
			txs: []*types.Transaction{
				mkDynamicTx(0, common.Address{}, params.TxGas, big.NewInt(0), big.NewInt(225000000000)),
			},
			want: "could not apply tx 0 [0xc5725e8baac950b2925dd4fea446ccddead1cc0affdae18b31a7d910629d9225]: cannot issue transaction from non-allow listed address: 0x71562b71999873DB5b286dF957af199Ec94617F7",
		},
	} {
		block := GenerateBadBlock(gspec.ToBlock(), dummy.NewCoinbaseFaker(), tt.txs, gspec.Config)
		_, err := blockchain.InsertChain(types.Blocks{block})
		if err == nil {
			t.Fatal("block imported without errors")
		}
		if have, want := err.Error(), tt.want; have != want {
			t.Errorf("test %d:\nhave \"%v\"\nwant \"%v\"\n", i, have, want)
		}
	}
}

// GenerateBadBlock constructs a "block" which contains the transactions. The transactions are not expected to be
// valid, and no proper post-state can be made. But from the perspective of the blockchain, the block is sufficiently
// valid to be considered for import:
// - valid pow (fake), ancestry, difficulty, gaslimit etc
func GenerateBadBlock(parent *types.Block, engine consensus.Engine, txs types.Transactions, config *params.ChainConfig) *types.Block {
	header := &types.Header{
		ParentHash: parent.Hash(),
		Coinbase:   parent.Coinbase(),
		Difficulty: engine.CalcDifficulty(&fakeChainReader{config}, parent.Time()+10, &types.Header{
			Number:     parent.Number(),
			Time:       parent.Time(),
			Difficulty: parent.Difficulty(),
			UncleHash:  parent.UncleHash(),
		}),
		GasLimit:  parent.GasLimit(),
		Number:    new(big.Int).Add(parent.Number(), common.Big1),
		Time:      parent.Time() + 10,
		UncleHash: types.EmptyUncleHash,
	}

	if config.IsSubnetEVM(header.Time) {
		header.Extra, header.BaseFee, _ = dummy.CalcBaseFee(config, config.FeeConfig, parent.Header(), header.Time)
		header.BlockGasCost = big.NewInt(0)
	}
	var receipts []*types.Receipt
	// The post-state result doesn't need to be correct (this is a bad block), but we do need something there
	// Preferably something unique. So let's use a combo of blocknum + txhash
	hasher := sha3.NewLegacyKeccak256()
	hasher.Write(header.Number.Bytes())
	var cumulativeGas uint64
	for _, tx := range txs {
		txh := tx.Hash()
		hasher.Write(txh[:])
		receipt := types.NewReceipt(nil, false, cumulativeGas+tx.Gas())
		receipt.TxHash = tx.Hash()
		receipt.GasUsed = tx.Gas()
		receipts = append(receipts, receipt)
		cumulativeGas += tx.Gas()
	}
	header.Root = common.BytesToHash(hasher.Sum(nil))
	// Assemble and return the final block for sealing
	return types.NewBlock(header, txs, nil, receipts, trie.NewStackTrie(nil))
}