// 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 (
"math/big"
"sync/atomic"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/params"
)
type (
CanTransferFunc func(StateDB, common.Address, *big.Int) bool
TransferFunc func(StateDB, common.Address, common.Address, *big.Int)
// GetHashFunc returns the nth block hash in the blockchain
// and is used by the BLOCKHASH EVM op code.
GetHashFunc func(uint64) common.Hash
)
// 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
// Transfer transfers ether from one account to the other
Transfer TransferFunc
// 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 *big.Int // 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 provides information about external sources for the EVM
//
// 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
// 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.
interpreter *Interpreter
// abort is used to abort the EVM calling operations
// NOTE: must be set atomically
abort int32
}
// NewEVM retutrns a new EVM evmironment.
func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
evm := &EVM{
Context: ctx,
StateDB: statedb,
vmConfig: vmConfig,
chainConfig: chainConfig,
}
evm.interpreter = NewInterpreter(evm, vmConfig)
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)
}
// 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
}
// Depth check execution. Fail if we're trying to execute above the
// limit.
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
return nil, gas, ErrInsufficientBalance
}
var (
to = AccountRef(addr)
snapshot = evm.StateDB.Snapshot()
)
if !evm.StateDB.Exist(addr) {
if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
return nil, gas, nil
}
evm.StateDB.CreateAccount(addr)
}
evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
// initialise a new contract and set the code that is to be used by the
// E The contract is a scoped evmironment for this execution context
// only.
contract := NewContract(caller, to, value, gas)
contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
ret, err = evm.interpreter.Run(contract, input)
// 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 {
contract.UseGas(contract.Gas)
evm.StateDB.RevertToSnapshot(snapshot)
}
return ret, contract.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
}
// Depth check execution. Fail if we're trying to execute above the
// limit.
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
return nil, gas, ErrInsufficientBalance
}
var (
snapshot = evm.StateDB.Snapshot()
to = AccountRef(caller.Address())
)
// initialise a new contract and set the code that is to be used by the
// E The contract is a scoped evmironment for this execution context
// only.
contract := NewContract(caller, to, value, gas)
contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
ret, err = evm.interpreter.Run(contract, input)
if err != nil {
contract.UseGas(contract.Gas)
evm.StateDB.RevertToSnapshot(snapshot)
}
return ret, contract.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
}
// Depth check execution. Fail if we're trying to execute above the
// limit.
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
var (
snapshot = evm.StateDB.Snapshot()
to = AccountRef(caller.Address())
)
// Iinitialise a new contract and make initialise the delegate values
contract := NewContract(caller, to, nil, gas).AsDelegate()
contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
ret, err = evm.interpreter.Run(contract, input)
if err != nil {
contract.UseGas(contract.Gas)
evm.StateDB.RevertToSnapshot(snapshot)
}
return ret, 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) {
if evm.vmConfig.NoRecursion && evm.depth > 0 {
return nil, common.Address{}, gas, nil
}
// 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
}
// Create a new account on the state
nonce := evm.StateDB.GetNonce(caller.Address())
evm.StateDB.SetNonce(caller.Address(), nonce+1)
snapshot := evm.StateDB.Snapshot()
contractAddr = crypto.CreateAddress(caller.Address(), nonce)
evm.StateDB.CreateAccount(contractAddr)
if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
evm.StateDB.SetNonce(contractAddr, 1)
}
evm.Transfer(evm.StateDB, caller.Address(), contractAddr, value)
// initialise a new contract and set the code that is to be used by the
// E The contract is a scoped evmironment for this execution context
// only.
contract := NewContract(caller, AccountRef(contractAddr), value, gas)
contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
ret, err = evm.interpreter.Run(contract, nil)
// check whether the max code size has been exceeded
maxCodeSizeExceeded := 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(contractAddr, 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.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
evm.StateDB.RevertToSnapshot(snapshot)
// Nothing should be returned when an error is thrown.
return nil, contractAddr, 0, err
}
// If the vm returned with an error the return value should be set to nil.
// This isn't consensus critical but merely to for behaviour reasons such as
// tests, RPC calls, etc.
if err != nil {
ret = nil
}
return ret, contractAddr, contract.Gas, err
}
// ChainConfig returns the evmironment's chain configuration
func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
// Interpreter returns the EVM interpreter
func (evm *EVM) Interpreter() *Interpreter { return evm.interpreter }