// 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 ( "errors" "math/big" "sync/atomic" "time" "github.com/ava-labs/coreth/params" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/crypto" "github.com/holiman/uint256" ) // emptyCodeHash is used by create to ensure deployment is disallowed to already // deployed contract addresses (relevant after the account abstraction). var emptyCodeHash = crypto.Keccak256Hash(nil) type ( // CanTransferFunc is the signature of a transfer guard function CanTransferFunc func(StateDB, common.Address, *big.Int) bool CanTransferMCFunc func(StateDB, common.Address, common.Address, *common.Hash, *big.Int) int // TransferFunc is the signature of a transfer function TransferFunc func(StateDB, common.Address, common.Address, *big.Int) TransferMCFunc func(StateDB, common.Address, common.Address, *common.Hash, *big.Int) // GetHashFunc returns the n'th block hash in the blockchain // and is used by the BLOCKHASH EVM op code. GetHashFunc func(uint64) common.Hash ) func (evm *EVM) precompile(addr common.Address) (PrecompiledContract, bool) { var precompiles map[common.Address]PrecompiledContract switch { case evm.chainRules.IsYoloV1: precompiles = PrecompiledContractsYoloV1 case evm.chainRules.IsIstanbul: precompiles = PrecompiledContractsIstanbul case evm.chainRules.IsByzantium: precompiles = PrecompiledContractsByzantium default: precompiles = PrecompiledContractsHomestead } p, ok := precompiles[addr] return p, ok } // run runs the given contract and takes care of running precompiles with a fallback to the byte code interpreter. func run(evm *EVM, contract *Contract, input []byte, readOnly bool) ([]byte, error) { for _, interpreter := range evm.interpreters { if interpreter.CanRun(contract.Code) { if evm.interpreter != interpreter { // Ensure that the interpreter pointer is set back // to its current value upon return. defer func(i Interpreter) { evm.interpreter = i }(evm.interpreter) evm.interpreter = interpreter } return interpreter.Run(contract, input, readOnly) } } return nil, errors.New("no compatible interpreter") } // Context provides the EVM with auxiliary information. Once provided // it shouldn't be modified. type Context struct { // CanTransfer returns whether the account contains // sufficient ether to transfer the value CanTransfer CanTransferFunc CanTransferMC CanTransferMCFunc // Transfer transfers ether from one account to the other Transfer TransferFunc TransferMultiCoin TransferMCFunc // GetHash returns the hash corresponding to n GetHash GetHashFunc // Message information Origin common.Address // Provides information for ORIGIN GasPrice *big.Int // Provides information for GASPRICE // Block information Coinbase common.Address // Provides information for COINBASE GasLimit uint64 // Provides information for GASLIMIT BlockNumber *big.Int // Provides information for NUMBER Time *big.Int // Provides information for TIME Difficulty *big.Int // Provides information for DIFFICULTY } // EVM is the Ethereum Virtual Machine base object and provides // the necessary tools to run a contract on the given state with // the provided context. It should be noted that any error // generated through any of the calls should be considered a // revert-state-and-consume-all-gas operation, no checks on // specific errors should ever be performed. The interpreter makes // sure that any errors generated are to be considered faulty code. // // The EVM should never be reused and is not thread safe. type EVM struct { // Context provides auxiliary blockchain related information Context // StateDB gives access to the underlying state StateDB StateDB // Depth is the current call stack depth int // chainConfig contains information about the current chain chainConfig *params.ChainConfig // chain rules contains the chain rules for the current epoch chainRules params.Rules // virtual machine configuration options used to initialise the // evm. vmConfig Config // global (to this context) ethereum virtual machine // used throughout the execution of the tx. interpreters []Interpreter interpreter Interpreter // abort is used to abort the EVM calling operations // NOTE: must be set atomically abort int32 // callGasTemp holds the gas available for the current call. This is needed because the // available gas is calculated in gasCall* according to the 63/64 rule and later // applied in opCall*. callGasTemp uint64 } // NewEVM returns a new EVM. The returned EVM is not thread safe and should // only ever be used *once*. func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM { evm := &EVM{ Context: ctx, StateDB: statedb, vmConfig: vmConfig, chainConfig: chainConfig, chainRules: chainConfig.Rules(ctx.BlockNumber), interpreters: make([]Interpreter, 0, 1), } if chainConfig.IsEWASM(ctx.BlockNumber) { // to be implemented by EVM-C and Wagon PRs. // if vmConfig.EWASMInterpreter != "" { // extIntOpts := strings.Split(vmConfig.EWASMInterpreter, ":") // path := extIntOpts[0] // options := []string{} // if len(extIntOpts) > 1 { // options = extIntOpts[1..] // } // evm.interpreters = append(evm.interpreters, NewEVMVCInterpreter(evm, vmConfig, options)) // } else { // evm.interpreters = append(evm.interpreters, NewEWASMInterpreter(evm, vmConfig)) // } panic("No supported ewasm interpreter yet.") } // vmConfig.EVMInterpreter will be used by EVM-C, it won't be checked here // as we always want to have the built-in EVM as the failover option. evm.interpreters = append(evm.interpreters, NewEVMInterpreter(evm, vmConfig)) evm.interpreter = evm.interpreters[0] return evm } // Cancel cancels any running EVM operation. This may be called concurrently and // it's safe to be called multiple times. func (evm *EVM) Cancel() { atomic.StoreInt32(&evm.abort, 1) } // Cancelled returns true if Cancel has been called func (evm *EVM) Cancelled() bool { return atomic.LoadInt32(&evm.abort) == 1 } // Interpreter returns the current interpreter func (evm *EVM) Interpreter() Interpreter { return evm.interpreter } // Call executes the contract associated with the addr with the given input as // parameters. It also handles any necessary value transfer required and takes // 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) { if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, gas, nil } // Fail if we're trying to execute above the call depth limit if evm.depth > int(params.CallCreateDepth) { return nil, gas, ErrDepth } // Fail if we're trying to transfer more than the available balance if value.Sign() != 0 && !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) { return nil, gas, ErrInsufficientBalance } snapshot := evm.StateDB.Snapshot() p, isPrecompile := evm.precompile(addr) if !evm.StateDB.Exist(addr) { if !isPrecompile && evm.chainRules.IsEIP158 && value.Sign() == 0 { // Calling a non existing account, don't do anything, but ping the tracer if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value) evm.vmConfig.Tracer.CaptureEnd(ret, 0, 0, nil) } return nil, gas, nil } evm.StateDB.CreateAccount(addr) } evm.Transfer(evm.StateDB, caller.Address(), addr, value) // Capture the tracer start/end events in debug mode if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value) defer func(startGas uint64, startTime time.Time) { // Lazy evaluation of the parameters evm.vmConfig.Tracer.CaptureEnd(ret, startGas-gas, time.Since(startTime), err) }(gas, time.Now()) } if isPrecompile { ret, gas, err = RunPrecompiledContract(p, input, gas) } else { // Initialise a new contract and set the code that is to be used by the EVM. // The contract is a scoped environment for this execution context only. code := evm.StateDB.GetCode(addr) if len(code) == 0 { ret, err = nil, nil // gas is unchanged } else { addrCopy := addr // If the account has no code, we can abort here // The depth-check is already done, and precompiles handled above contract := NewContract(caller, AccountRef(addrCopy), value, gas) contract.SetCallCode(&addrCopy, evm.StateDB.GetCodeHash(addrCopy), code) ret, err = run(evm, contract, input, false) gas = contract.Gas } } // When an error was returned by the EVM or when setting the creation code // above we revert to the snapshot and consume any gas remaining. Additionally // when we're in homestead this also counts for code storage gas errors. if err != nil { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { gas = 0 } // TODO: consider clearing up unused snapshots: //} else { // evm.StateDB.DiscardSnapshot(snapshot) } return ret, gas, err } // This allows the user transfer balance of a specified coinId in addition to a normal Call(). func (evm *EVM) CallExpert(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int, coinID *common.Hash, value2 *big.Int) (ret []byte, leftOverGas uint64, err error) { if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, gas, nil } // Fail if we're trying to execute above the call depth limit if evm.depth > int(params.CallCreateDepth) { return nil, gas, ErrDepth } // Fail if we're trying to transfer more than the available balance if value.Sign() != 0 && !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) { return nil, gas, ErrInsufficientBalance } var to = AccountRef(addr) mcerr := evm.Context.CanTransferMC(evm.StateDB, caller.Address(), to.Address(), coinID, value2) if mcerr == 1 { return nil, gas, ErrInsufficientBalance } else if mcerr != 0 { return nil, gas, ErrIncompatibleAccount } snapshot := evm.StateDB.Snapshot() p, isPrecompile := evm.precompile(addr) if !evm.StateDB.Exist(addr) { if !isPrecompile && evm.chainRules.IsEIP158 && value.Sign() == 0 { // Calling a non existing account, don't do anything, but ping the tracer if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value) evm.vmConfig.Tracer.CaptureEnd(ret, 0, 0, nil) } return nil, gas, nil } evm.StateDB.CreateAccount(addr) } evm.Transfer(evm.StateDB, caller.Address(), addr, value) evm.TransferMultiCoin(evm.StateDB, caller.Address(), addr, coinID, value2) // Capture the tracer start/end events in debug mode if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value) defer func(startGas uint64, startTime time.Time) { // Lazy evaluation of the parameters evm.vmConfig.Tracer.CaptureEnd(ret, startGas-gas, time.Since(startTime), err) }(gas, time.Now()) } if isPrecompile { ret, gas, err = RunPrecompiledContract(p, input, gas) } else { // Initialise a new contract and set the code that is to be used by the EVM. // The contract is a scoped environment for this execution context only. code := evm.StateDB.GetCode(addr) if len(code) == 0 { ret, err = nil, nil // gas is unchanged } else { addrCopy := addr // If the account has no code, we can abort here // The depth-check is already done, and precompiles handled above contract := NewContract(caller, AccountRef(addrCopy), value, gas) contract.SetCallCode(&addrCopy, evm.StateDB.GetCodeHash(addrCopy), code) ret, err = run(evm, contract, input, false) gas = contract.Gas } } // When an error was returned by the EVM or when setting the creation code // above we revert to the snapshot and consume any gas remaining. Additionally // when we're in homestead this also counts for code storage gas errors. if err != nil { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { gas = 0 } // TODO: consider clearing up unused snapshots: //} else { // evm.StateDB.DiscardSnapshot(snapshot) } return ret, gas, err } // CallCode executes the contract associated with the addr with the given input // as parameters. It also handles any necessary value transfer required and takes // the necessary steps to create accounts and reverses the state in case of an // execution error or failed value transfer. // // 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) { if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, gas, nil } // Fail if we're trying to execute above the call depth limit if evm.depth > int(params.CallCreateDepth) { return nil, gas, ErrDepth } // Fail if we're trying to transfer more than the available balance // Note although it's noop to transfer X ether to caller itself. But // if caller doesn't have enough balance, it would be an error to allow // over-charging itself. So the check here is necessary. if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) { return nil, gas, ErrInsufficientBalance } var snapshot = evm.StateDB.Snapshot() // It is allowed to call precompiles, even via delegatecall if p, isPrecompile := evm.precompile(addr); isPrecompile { ret, gas, err = RunPrecompiledContract(p, input, gas) } else { addrCopy := addr // Initialise a new contract and set the code that is to be used by the EVM. // The contract is a scoped environment for this execution context only. contract := NewContract(caller, AccountRef(caller.Address()), value, gas) contract.SetCallCode(&addrCopy, evm.StateDB.GetCodeHash(addrCopy), evm.StateDB.GetCode(addrCopy)) ret, err = run(evm, contract, input, false) gas = contract.Gas } if err != nil { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { gas = 0 } } return ret, gas, err } // DelegateCall executes the contract associated with the addr with the given input // as parameters. It reverses the state in case of an execution error. // // 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) { if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, gas, nil } // Fail if we're trying to execute above the call depth limit if evm.depth > int(params.CallCreateDepth) { return nil, gas, ErrDepth } var snapshot = evm.StateDB.Snapshot() // It is allowed to call precompiles, even via delegatecall if p, isPrecompile := evm.precompile(addr); isPrecompile { ret, gas, err = RunPrecompiledContract(p, input, gas) } else { addrCopy := addr // Initialise a new contract and make initialise the delegate values contract := NewContract(caller, AccountRef(caller.Address()), nil, gas).AsDelegate() contract.SetCallCode(&addrCopy, evm.StateDB.GetCodeHash(addrCopy), evm.StateDB.GetCode(addrCopy)) ret, err = run(evm, contract, input, false) gas = contract.Gas } if err != nil { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { gas = 0 } } return ret, gas, err } // StaticCall executes the contract associated with the addr with the given input // as parameters while disallowing any modifications to the state during the call. // 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) { if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, gas, nil } // Fail if we're trying to execute above the call depth limit if evm.depth > int(params.CallCreateDepth) { return nil, gas, ErrDepth } // We take a snapshot here. This is a bit counter-intuitive, and could probably be skipped. // However, even a staticcall is considered a 'touch'. On mainnet, static calls were introduced // after all empty accounts were deleted, so this is not required. However, if we omit this, // then certain tests start failing; stRevertTest/RevertPrecompiledTouchExactOOG.json. // We could change this, but for now it's left for legacy reasons var snapshot = evm.StateDB.Snapshot() // We do an AddBalance of zero here, just in order to trigger a touch. // This doesn't matter on Mainnet, where all empties are gone at the time of Byzantium, // but is the correct thing to do and matters on other networks, in tests, and potential // future scenarios evm.StateDB.AddBalance(addr, big0) if p, isPrecompile := evm.precompile(addr); isPrecompile { ret, gas, err = RunPrecompiledContract(p, input, gas) } else { // At this point, we use a copy of address. If we don't, the go compiler will // leak the 'contract' to the outer scope, and make allocation for 'contract' // even if the actual execution ends on RunPrecompiled above. addrCopy := addr // Initialise a new contract and set the code that is to be used by the EVM. // The contract is a scoped environment for this execution context only. contract := NewContract(caller, AccountRef(addrCopy), new(big.Int), gas) contract.SetCallCode(&addrCopy, evm.StateDB.GetCodeHash(addrCopy), evm.StateDB.GetCode(addrCopy)) // When an error was returned by the EVM or when setting the creation code // above we revert to the snapshot and consume any gas remaining. Additionally // when we're in Homestead this also counts for code storage gas errors. ret, err = run(evm, contract, input, true) gas = contract.Gas } if err != nil { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { gas = 0 } } return ret, gas, err } type codeAndHash struct { code []byte hash common.Hash } func (c *codeAndHash) Hash() common.Hash { if c.hash == (common.Hash{}) { c.hash = crypto.Keccak256Hash(c.code) } return c.hash } // create creates a new contract using code as deployment code. func (evm *EVM) create(caller ContractRef, codeAndHash *codeAndHash, gas uint64, value *big.Int, address common.Address) ([]byte, common.Address, uint64, error) { // Depth check execution. Fail if we're trying to execute above the // limit. if evm.depth > int(params.CallCreateDepth) { return nil, common.Address{}, gas, ErrDepth } if !evm.CanTransfer(evm.StateDB, caller.Address(), value) { return nil, common.Address{}, gas, ErrInsufficientBalance } nonce := evm.StateDB.GetNonce(caller.Address()) evm.StateDB.SetNonce(caller.Address(), nonce+1) // Ensure there's no existing contract already at the designated address contractHash := evm.StateDB.GetCodeHash(address) if evm.StateDB.GetNonce(address) != 0 || (contractHash != (common.Hash{}) && contractHash != emptyCodeHash) { return nil, common.Address{}, 0, ErrContractAddressCollision } // Create a new account on the state snapshot := evm.StateDB.Snapshot() evm.StateDB.CreateAccount(address) if evm.chainRules.IsEIP158 { evm.StateDB.SetNonce(address, 1) } evm.Transfer(evm.StateDB, caller.Address(), address, value) // Initialise a new contract and set the code that is to be used by the EVM. // The contract is a scoped environment for this execution context only. contract := NewContract(caller, AccountRef(address), value, gas) contract.SetCodeOptionalHash(&address, codeAndHash) if evm.vmConfig.NoRecursion && evm.depth > 0 { return nil, address, gas, nil } if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureStart(caller.Address(), address, true, codeAndHash.code, gas, value) } start := time.Now() ret, err := run(evm, contract, nil, false) // check whether the max code size has been exceeded maxCodeSizeExceeded := evm.chainRules.IsEIP158 && len(ret) > params.MaxCodeSize // if the contract creation ran successfully and no errors were returned // calculate the gas required to store the code. If the code could not // be stored due to not enough gas set an error and let it be handled // by the error checking condition below. if err == nil && !maxCodeSizeExceeded { createDataGas := uint64(len(ret)) * params.CreateDataGas if contract.UseGas(createDataGas) { evm.StateDB.SetCode(address, ret) } else { err = ErrCodeStoreOutOfGas } } // When an error was returned by the EVM or when setting the creation code // above we revert to the snapshot and consume any gas remaining. Additionally // when we're in homestead this also counts for code storage gas errors. if maxCodeSizeExceeded || (err != nil && (evm.chainRules.IsHomestead || err != ErrCodeStoreOutOfGas)) { evm.StateDB.RevertToSnapshot(snapshot) if err != ErrExecutionReverted { contract.UseGas(contract.Gas) } } // Assign err if contract code size exceeds the max while the err is still empty. if maxCodeSizeExceeded && err == nil { err = ErrMaxCodeSizeExceeded } if evm.vmConfig.Debug && evm.depth == 0 { evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err) } return ret, address, contract.Gas, err } // 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) { contractAddr = crypto.CreateAddress(caller.Address(), evm.StateDB.GetNonce(caller.Address())) return evm.create(caller, &codeAndHash{code: code}, gas, value, contractAddr) } // Create2 creates a new contract using code as deployment code. // // The different between Create2 with Create is Create2 uses sha3(0xff ++ msg.sender ++ salt ++ sha3(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) { codeAndHash := &codeAndHash{code: code} contractAddr = crypto.CreateAddress2(caller.Address(), common.Hash(salt.Bytes32()), codeAndHash.Hash().Bytes()) return evm.create(caller, codeAndHash, gas, endowment, contractAddr) } // ChainConfig returns the environment's chain configuration func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }