accounts/abi/bind: refactor transact method (#23719)

This fixes a bug where gas-related fields of the TransactOpts passed to transaction methods would be modified, skipping gas estimation for subsequent transactions. Co-authored-by: Yondon Fu <yondon.fu@gmail.com> Co-authored-by: Felix Lange <fjl@twurst.com>
blocknative · dmarzzz · Dec 9, 2021 · Aug 30, 2021 · Aug 31, 2021 · Aug 31, 2021
commit 79b727bc8aa19a70c0735141e60da003d3624472
diff --git a/accounts/abi/bind/base.go b/accounts/abi/bind/base.go
@@ -231,108 +231,158 @@ func (c *BoundContract) Transfer(opts *TransactOpts) (*types.Transaction, error)
 	return c.transact(opts, &c.address, nil)
 }
 
-// transact executes an actual transaction invocation, first deriving any missing
-// authorization fields, and then scheduling the transaction for execution.
-func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, input []byte) (*types.Transaction, error) {
-	var err error
-
-	// Ensure a valid value field and resolve the account nonce
+func (c *BoundContract) createDynamicTx(opts *TransactOpts, contract *common.Address, input []byte, head *types.Header) (*types.Transaction, error) {
+	// Normalize value
 	value := opts.Value
 	if value == nil {
 		value = new(big.Int)
 	}
-	var nonce uint64
-	if opts.Nonce == nil {
-		nonce, err = c.transactor.PendingNonceAt(ensureContext(opts.Context), opts.From)
+	// Estimate TipCap
+	gasTipCap := opts.GasTipCap
+	if gasTipCap == nil {
+		tip, err := c.transactor.SuggestGasTipCap(ensureContext(opts.Context))
 		if err != nil {
-			return nil, fmt.Errorf("failed to retrieve account nonce: %v", err)
+			return nil, err
 		}
-	} else {
-		nonce = opts.Nonce.Uint64()
+		gasTipCap = tip
 	}
-	// Figure out reasonable gas price values
-	if opts.GasPrice != nil && (opts.GasFeeCap != nil || opts.GasTipCap != nil) {
-		return nil, errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified")
+	// Estimate FeeCap
+	gasFeeCap := opts.GasFeeCap
+	if gasFeeCap == nil {
+		gasFeeCap = new(big.Int).Add(
+			gasTipCap,
+			new(big.Int).Mul(head.BaseFee, big.NewInt(2)),
+		)
 	}
-	head, err := c.transactor.HeaderByNumber(ensureContext(opts.Context), nil)
+	if gasFeeCap.Cmp(gasTipCap) < 0 {
+		return nil, fmt.Errorf("maxFeePerGas (%v) < maxPriorityFeePerGas (%v)", gasFeeCap, gasTipCap)
+	}
+	// Estimate GasLimit
+	gasLimit := opts.GasLimit
+	if opts.GasLimit == 0 {
+		var err error
+		gasLimit, err = c.estimateGasLimit(opts, contract, input, nil, gasTipCap, gasFeeCap, value)
+		if err != nil {
+			return nil, err
+		}
+	}
+	// create the transaction
+	nonce, err := c.getNonce(opts)
 	if err != nil {
 		return nil, err
 	}
-	if head.BaseFee != nil && opts.GasPrice == nil {
-		if opts.GasTipCap == nil {
-			tip, err := c.transactor.SuggestGasTipCap(ensureContext(opts.Context))
-			if err != nil {
-				return nil, err
-			}
-			opts.GasTipCap = tip
-		}
-		if opts.GasFeeCap == nil {
-			gasFeeCap := new(big.Int).Add(
-				opts.GasTipCap,
-				new(big.Int).Mul(head.BaseFee, big.NewInt(2)),
-			)
-			opts.GasFeeCap = gasFeeCap
-		}
-		if opts.GasFeeCap.Cmp(opts.GasTipCap) < 0 {
-			return nil, fmt.Errorf("maxFeePerGas (%v) < maxPriorityFeePerGas (%v)", opts.GasFeeCap, opts.GasTipCap)
-		}
-	} else {
-		if opts.GasFeeCap != nil || opts.GasTipCap != nil {
-			return nil, errors.New("maxFeePerGas or maxPriorityFeePerGas specified but london is not active yet")
-		}
-		if opts.GasPrice == nil {
-			price, err := c.transactor.SuggestGasPrice(ensureContext(opts.Context))
-			if err != nil {
-				return nil, err
-			}
-			opts.GasPrice = price
+	baseTx := &types.DynamicFeeTx{
+		To:        contract,
+		Nonce:     nonce,
+		GasFeeCap: gasFeeCap,
+		GasTipCap: gasTipCap,
+		Gas:       gasLimit,
+		Value:     value,
+		Data:      input,
+	}
+	return types.NewTx(baseTx), nil
+}
+
+func (c *BoundContract) createLegacyTx(opts *TransactOpts, contract *common.Address, input []byte) (*types.Transaction, error) {
+	if opts.GasFeeCap != nil || opts.GasTipCap != nil {
+		return nil, errors.New("maxFeePerGas or maxPriorityFeePerGas specified but london is not active yet")
+	}
+	// Normalize value
+	value := opts.Value
+	if value == nil {
+		value = new(big.Int)
+	}
+	// Estimate GasPrice
+	gasPrice := opts.GasPrice
+	if gasPrice == nil {
+		price, err := c.transactor.SuggestGasPrice(ensureContext(opts.Context))
+		if err != nil {
+			return nil, err
 		}
+		gasPrice = price
 	}
+	// Estimate GasLimit
 	gasLimit := opts.GasLimit
-	if gasLimit == 0 {
-		// Gas estimation cannot succeed without code for method invocations
-		if contract != nil {
-			if code, err := c.transactor.PendingCodeAt(ensureContext(opts.Context), c.address); err != nil {
-				return nil, err
-			} else if len(code) == 0 {
-				return nil, ErrNoCode
-			}
-		}
-		// If the contract surely has code (or code is not needed), estimate the transaction
-		msg := ethereum.CallMsg{From: opts.From, To: contract, GasPrice: opts.GasPrice, GasTipCap: opts.GasTipCap, GasFeeCap: opts.GasFeeCap, Value: value, Data: input}
-		gasLimit, err = c.transactor.EstimateGas(ensureContext(opts.Context), msg)
+	if opts.GasLimit == 0 {
+		var err error
+		gasLimit, err = c.estimateGasLimit(opts, contract, input, gasPrice, nil, nil, value)
 		if err != nil {
-			return nil, fmt.Errorf("failed to estimate gas needed: %v", err)
+			return nil, err
 		}
 	}
-	// Create the transaction, sign it and schedule it for execution
-	var rawTx *types.Transaction
-	if opts.GasFeeCap == nil {
-		baseTx := &types.LegacyTx{
-			Nonce:    nonce,
-			GasPrice: opts.GasPrice,
-			Gas:      gasLimit,
-			Value:    value,
-			Data:     input,
-		}
-		if contract != nil {
-			baseTx.To = &c.address
+	// create the transaction
+	nonce, err := c.getNonce(opts)
+	if err != nil {
+		return nil, err
+	}
+	baseTx := &types.LegacyTx{
+		To:       contract,
+		Nonce:    nonce,
+		GasPrice: gasPrice,
+		Gas:      gasLimit,
+		Value:    value,
+		Data:     input,
+	}
+	return types.NewTx(baseTx), nil
+}
+
+func (c *BoundContract) estimateGasLimit(opts *TransactOpts, contract *common.Address, input []byte, gasPrice, gasTipCap, gasFeeCap, value *big.Int) (uint64, error) {
+	if contract != nil {
+		// Gas estimation cannot succeed without code for method invocations.
+		if code, err := c.transactor.PendingCodeAt(ensureContext(opts.Context), c.address); err != nil {
+			return 0, err
+		} else if len(code) == 0 {
+			return 0, ErrNoCode
 		}
-		rawTx = types.NewTx(baseTx)
+	}
+	msg := ethereum.CallMsg{
+		From:      opts.From,
+		To:        contract,
+		GasPrice:  gasPrice,
+		GasTipCap: gasTipCap,
+		GasFeeCap: gasFeeCap,
+		Value:     value,
+		Data:      input,
+	}
+	return c.transactor.EstimateGas(ensureContext(opts.Context), msg)
+}
+
+func (c *BoundContract) getNonce(opts *TransactOpts) (uint64, error) {
+	if opts.Nonce == nil {
+		return c.transactor.PendingNonceAt(ensureContext(opts.Context), opts.From)
 	} else {
-		baseTx := &types.DynamicFeeTx{
-			Nonce:     nonce,
-			GasFeeCap: opts.GasFeeCap,
-			GasTipCap: opts.GasTipCap,
-			Gas:       gasLimit,
-			Value:     value,
-			Data:      input,
-		}
-		if contract != nil {
-			baseTx.To = &c.address
+		return opts.Nonce.Uint64(), nil
+	}
+}
+
+// transact executes an actual transaction invocation, first deriving any missing
+// authorization fields, and then scheduling the transaction for execution.
+func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, input []byte) (*types.Transaction, error) {
+	if opts.GasPrice != nil && (opts.GasFeeCap != nil || opts.GasTipCap != nil) {
+		return nil, errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified")
+	}
+	// Create the transaction
+	var (
+		rawTx *types.Transaction
+		err   error
+	)
+	if opts.GasPrice != nil {
+		rawTx, err = c.createLegacyTx(opts, contract, input)
+	} else {
+		// Only query for basefee if gasPrice not specified
+		if head, errHead := c.transactor.HeaderByNumber(ensureContext(opts.Context), nil); err != nil {
+			return nil, errHead
+		} else if head.BaseFee != nil {
+			rawTx, err = c.createDynamicTx(opts, contract, input, head)
+		} else {
+			// Chain is not London ready -> use legacy transaction
+			rawTx, err = c.createLegacyTx(opts, contract, input)
 		}
-		rawTx = types.NewTx(baseTx)
 	}
+	if err != nil {
+		return nil, err
+	}
+	// Sign the transaction and schedule it for execution
 	if opts.Signer == nil {
 		return nil, errors.New("no signer to authorize the transaction with")
 	}

diff --git a/accounts/abi/bind/base_test.go b/accounts/abi/bind/base_test.go
@@ -31,8 +31,49 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/stretchr/testify/assert"
 )
 
+func mockSign(addr common.Address, tx *types.Transaction) (*types.Transaction, error) { return tx, nil }
+
+type mockTransactor struct {
+	baseFee                *big.Int
+	gasTipCap              *big.Int
+	gasPrice               *big.Int
+	suggestGasTipCapCalled bool
+	suggestGasPriceCalled  bool
+}
+
+func (mt *mockTransactor) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
+	return &types.Header{BaseFee: mt.baseFee}, nil
+}
+
+func (mt *mockTransactor) PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error) {
+	return []byte{1}, nil
+}
+
+func (mt *mockTransactor) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
+	return 0, nil
+}
+
+func (mt *mockTransactor) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
+	mt.suggestGasPriceCalled = true
+	return mt.gasPrice, nil
+}
+
+func (mt *mockTransactor) SuggestGasTipCap(ctx context.Context) (*big.Int, error) {
+	mt.suggestGasTipCapCalled = true
+	return mt.gasTipCap, nil
+}
+
+func (mt *mockTransactor) EstimateGas(ctx context.Context, call ethereum.CallMsg) (gas uint64, err error) {
+	return 0, nil
+}
+
+func (mt *mockTransactor) SendTransaction(ctx context.Context, tx *types.Transaction) error {
+	return nil
+}
+
 type mockCaller struct {
 	codeAtBlockNumber         *big.Int
 	callContractBlockNumber   *big.Int
@@ -226,6 +267,51 @@ func TestUnpackIndexedBytesTyLogIntoMap(t *testing.T) {
 	unpackAndCheck(t, bc, expectedReceivedMap, mockLog)
 }
 
+func TestTransactGasFee(t *testing.T) {
+	assert := assert.New(t)
+
+	// GasTipCap and GasFeeCap
+	// When opts.GasTipCap and opts.GasFeeCap are nil
+	mt := &mockTransactor{baseFee: big.NewInt(100), gasTipCap: big.NewInt(5)}
+	bc := bind.NewBoundContract(common.Address{}, abi.ABI{}, nil, mt, nil)
+	opts := &bind.TransactOpts{Signer: mockSign}
+	tx, err := bc.Transact(opts, "")
+	assert.Nil(err)
+	assert.Equal(big.NewInt(5), tx.GasTipCap())
+	assert.Equal(big.NewInt(205), tx.GasFeeCap())
+	assert.Nil(opts.GasTipCap)
+	assert.Nil(opts.GasFeeCap)
+	assert.True(mt.suggestGasTipCapCalled)
+
+	// Second call to Transact should use latest suggested GasTipCap
+	mt.gasTipCap = big.NewInt(6)
+	mt.suggestGasTipCapCalled = false
+	tx, err = bc.Transact(opts, "")
+	assert.Nil(err)
+	assert.Equal(big.NewInt(6), tx.GasTipCap())
+	assert.Equal(big.NewInt(206), tx.GasFeeCap())
+	assert.True(mt.suggestGasTipCapCalled)
+
+	// GasPrice
+	// When opts.GasPrice is nil
+	mt = &mockTransactor{gasPrice: big.NewInt(5)}
+	bc = bind.NewBoundContract(common.Address{}, abi.ABI{}, nil, mt, nil)
+	opts = &bind.TransactOpts{Signer: mockSign}
+	tx, err = bc.Transact(opts, "")
+	assert.Nil(err)
+	assert.Equal(big.NewInt(5), tx.GasPrice())
+	assert.Nil(opts.GasPrice)
+	assert.True(mt.suggestGasPriceCalled)
+
+	// Second call to Transact should use latest suggested GasPrice
+	mt.gasPrice = big.NewInt(6)
+	mt.suggestGasPriceCalled = false
+	tx, err = bc.Transact(opts, "")
+	assert.Nil(err)
+	assert.Equal(big.NewInt(6), tx.GasPrice())
+	assert.True(mt.suggestGasPriceCalled)
+}
+
 func unpackAndCheck(t *testing.T, bc *bind.BoundContract, expected map[string]interface{}, mockLog types.Log) {
 	received := make(map[string]interface{})
 	if err := bc.UnpackLogIntoMap(received, "received", mockLog); err != nil {