feat(evm): OpCodesHooks for CREATE and CALL opcodes (#28)

Co-authored-by: Tom <54514587+GAtom22@users.noreply.github.com>

core/vm/evm.go

@@ -97,28 +97,23 @@ type EVM struct {
 	// activePrecompiles defines the precompiles that are currently active
 	activePrecompiles []common.Address
 
-	// preExecuteCallback is a callback function that is called before executing
-	// CALL, CALLCODE, DELEGATECALL and STATICCALL opcodes.
-	preExecuteCallback preExecuteCallbackType
-}
-
-type preExecuteCallbackType func(evm *EVM, addr common.Address) error
-
-func dummyCallback(evm *EVM, addr common.Address) error {
-	return nil
+	// hooks is a set of functions that can be used to intercept and modify the
+	// behavior of the EVM when executing certain opcodes.
+	// The hooks are called before the execution of the respective opcodes.
+	hooks OpCodeHooks
 }
 
 // NewEVM returns a new EVM. The returned EVM is not thread safe and should
 // only ever be used *once*.
 func NewEVM(blockCtx BlockContext, txCtx TxContext, statedb StateDB, chainConfig *params.ChainConfig, config Config) *EVM {
 	evm := &EVM{
-		Context:            blockCtx,
-		TxContext:          txCtx,
-		StateDB:            statedb,
-		Config:             config,
-		chainConfig:        chainConfig,
-		chainRules:         chainConfig.Rules(blockCtx.BlockNumber, blockCtx.Random != nil),
-		preExecuteCallback: dummyCallback,
+		Context:     blockCtx,
+		TxContext:   txCtx,
+		StateDB:     statedb,
+		Config:      config,
+		chainConfig: chainConfig,
+		chainRules:  chainConfig.Rules(blockCtx.BlockNumber, blockCtx.Random != nil),
+		hooks:       newNoopOpCodeHooks(),
 	}
 	// set the default precompiles
 	evm.activePrecompiles = DefaultActivePrecompiles(evm.chainRules)
@@ -128,17 +123,17 @@ func NewEVM(blockCtx BlockContext, txCtx TxContext, statedb StateDB, chainConfig
 	return evm
 }
 
-// NewEVMWithCallback returns a new EVM and takes a custom preExecuteCallback. The returned EVM is
+// NewEVMWithHooks returns a new EVM and takes a custom OpCodeHooks. The returned EVM is
 // not thread safe and should only ever be used *once*.
-func NewEVMWithCallback(callback preExecuteCallbackType, blockCtx BlockContext, txCtx TxContext, statedb StateDB, chainConfig *params.ChainConfig, config Config) *EVM {
+func NewEVMWithHooks(hooks OpCodeHooks, blockCtx BlockContext, txCtx TxContext, statedb StateDB, chainConfig *params.ChainConfig, config Config) *EVM {
 	evm := &EVM{
-		Context:            blockCtx,
-		TxContext:          txCtx,
-		StateDB:            statedb,
-		Config:             config,
-		chainConfig:        chainConfig,
-		chainRules:         chainConfig.Rules(blockCtx.BlockNumber, blockCtx.Random != nil),
-		preExecuteCallback: callback,
+		Context:     blockCtx,
+		TxContext:   txCtx,
+		StateDB:     statedb,
+		Config:      config,
+		chainConfig: chainConfig,
+		chainRules:  chainConfig.Rules(blockCtx.BlockNumber, blockCtx.Random != nil),
+		hooks:       hooks,
 	}
 	// set the default precompiles
 	evm.activePrecompiles = DefaultActivePrecompiles(evm.chainRules)
@@ -181,8 +176,7 @@ func (evm *EVM) WithInterpreter(interpreter Interpreter) {
 // the necessary steps to create accounts and reverses the state in case of an
 // execution error or failed value transfer.
 func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
-	err = evm.preExecuteCallback(evm, addr)
-	if err != nil {
+	if err = evm.hooks.CallHook(evm, caller.Address(), addr); err != nil {
 		return nil, gas, err
 	}
 
@@ -274,8 +268,7 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 // CallCode differs from Call in the sense that it executes the given address'
 // code with the caller as context.
 func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
-	err = evm.preExecuteCallback(evm, addr)
-	if err != nil {
+	if err = evm.hooks.CallHook(evm, caller.Address(), addr); err != nil {
 		return nil, gas, err
 	}
 
@@ -327,8 +320,7 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
 // DelegateCall differs from CallCode in the sense that it executes the given address'
 // code with the caller as context and the caller is set to the caller of the caller.
 func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
-	err = evm.preExecuteCallback(evm, addr)
-	if err != nil {
+	if err = evm.hooks.CallHook(evm, caller.Address(), addr); err != nil {
 		return nil, gas, err
 	}
 
@@ -371,8 +363,7 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
 // Opcodes that attempt to perform such modifications will result in exceptions
 // instead of performing the modifications.
 func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
-	err = evm.preExecuteCallback(evm, addr)
-	if err != nil {
+	if err = evm.hooks.CallHook(evm, caller.Address(), addr); err != nil {
 		return nil, gas, err
 	}
 
@@ -535,6 +526,9 @@ func (evm *EVM) create(caller ContractRef, codeAndHash *codeAndHash, gas uint64,
 
 // Create creates a new contract using code as deployment code.
 func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
+	if err = evm.hooks.CreateHook(evm, caller.Address()); err != nil {
+		return nil, common.Address{}, gas, err
+	}
 	contractAddr = crypto.CreateAddress(caller.Address(), evm.StateDB.GetNonce(caller.Address()))
 	return evm.create(caller, &codeAndHash{code: code}, gas, value, contractAddr, CREATE)
 }
@@ -544,6 +538,9 @@ func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.I
 // The different between Create2 with Create is Create2 uses keccak256(0xff ++ msg.sender ++ salt ++ keccak256(init_code))[12:]
 // instead of the usual sender-and-nonce-hash as the address where the contract is initialized at.
 func (evm *EVM) Create2(caller ContractRef, code []byte, gas uint64, endowment *big.Int, salt *uint256.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
+	if err = evm.hooks.CreateHook(evm, caller.Address()); err != nil {
+		return nil, common.Address{}, gas, err
+	}
 	codeAndHash := &codeAndHash{code: code}
 	contractAddr = crypto.CreateAddress2(caller.Address(), salt.Bytes32(), codeAndHash.Hash().Bytes())
 	return evm.create(caller, codeAndHash, gas, endowment, contractAddr, CREATE2)

core/vm/opcode_hooks.go

@@ -0,0 +1,48 @@
+// Copyright 2014 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 vm
+
+import "github.com/ethereum/go-ethereum/common"
+
+// OpCodeHooks is a set of hooks that can be used to intercept and modify the
+// behavior of the EVM when executing certain opcodes.
+// The hooks are called before the execution of the respective opcodes.
+type OpCodeHooks interface {
+	// CallHook is called before executing a CALL, CALLCODE, DELEGATECALL and STATICCALL opcodes.
+	CallHook(evm *EVM, caller common.Address, recipient common.Address) error
+	// CreateHook is called before executing a CREATE and CREATE2 opcodes.
+	CreateHook(evm *EVM, caller common.Address) error
+}
+
+type NoopOpCodeHooks struct {
+}
+
+func (NoopOpCodeHooks) CallHook(evm *EVM, caller common.Address, recipient common.Address) error {
+	return nil
+}
+
+func (NoopOpCodeHooks) CreateHook(evm *EVM, caller common.Address) error {
+	return nil
+}
+
+func newNoopOpCodeHooks() OpCodeHooks {
+	return NoopOpCodeHooks{}
+}
+
+func NewDefaultOpCodeHooks() OpCodeHooks {
+	return newNoopOpCodeHooks()
+}