// 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
}
mcerr := evm.Context.CanTransferMC(evm.StateDB, caller.Address(), addr, 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 }