ae992a5d73
Makes Interface interface a bit more stateless and abstract. Obviously this change is dictated by EVMC design. The EVMC tries to keep the responsibility for EVM features totally inside the VMs, if feasible. This makes VM "stateless" because VM does not need to pass any information between executions, all information is included in parameters of the execute function.
432 lines
16 KiB
Go
432 lines
16 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math/big"
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"sync/atomic"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/params"
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)
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// emptyCodeHash is used by create to ensure deployment is disallowed to already
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// deployed contract addresses (relevant after the account abstraction).
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var emptyCodeHash = crypto.Keccak256Hash(nil)
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type (
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// CanTransferFunc is the signature of a transfer guard function
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CanTransferFunc func(StateDB, common.Address, *big.Int) bool
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// TransferFunc is the signature of a transfer function
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TransferFunc func(StateDB, common.Address, common.Address, *big.Int)
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// GetHashFunc returns the nth block hash in the blockchain
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// and is used by the BLOCKHASH EVM op code.
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GetHashFunc func(uint64) common.Hash
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)
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// run runs the given contract and takes care of running precompiles with a fallback to the byte code interpreter.
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func run(evm *EVM, contract *Contract, input []byte, readOnly bool) ([]byte, error) {
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if contract.CodeAddr != nil {
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precompiles := PrecompiledContractsHomestead
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if evm.ChainConfig().IsByzantium(evm.BlockNumber) {
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precompiles = PrecompiledContractsByzantium
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}
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if p := precompiles[*contract.CodeAddr]; p != nil {
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return RunPrecompiledContract(p, input, contract)
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}
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}
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for _, interpreter := range evm.interpreters {
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if interpreter.CanRun(contract.Code) {
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if evm.interpreter != interpreter {
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// Ensure that the interpreter pointer is set back
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// to its current value upon return.
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defer func(i Interpreter) {
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evm.interpreter = i
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}(evm.interpreter)
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evm.interpreter = interpreter
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}
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return interpreter.Run(contract, input, readOnly)
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}
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}
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return nil, ErrNoCompatibleInterpreter
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}
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// Context provides the EVM with auxiliary information. Once provided
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// it shouldn't be modified.
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type Context struct {
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// CanTransfer returns whether the account contains
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// sufficient ether to transfer the value
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CanTransfer CanTransferFunc
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// Transfer transfers ether from one account to the other
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Transfer TransferFunc
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// GetHash returns the hash corresponding to n
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GetHash GetHashFunc
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// Message information
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Origin common.Address // Provides information for ORIGIN
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GasPrice *big.Int // Provides information for GASPRICE
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// Block information
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Coinbase common.Address // Provides information for COINBASE
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GasLimit uint64 // Provides information for GASLIMIT
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BlockNumber *big.Int // Provides information for NUMBER
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Time *big.Int // Provides information for TIME
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Difficulty *big.Int // Provides information for DIFFICULTY
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}
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// EVM is the Ethereum Virtual Machine base object and provides
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// the necessary tools to run a contract on the given state with
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// the provided context. It should be noted that any error
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// generated through any of the calls should be considered a
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// revert-state-and-consume-all-gas operation, no checks on
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// specific errors should ever be performed. The interpreter makes
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// sure that any errors generated are to be considered faulty code.
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//
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// The EVM should never be reused and is not thread safe.
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type EVM struct {
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// Context provides auxiliary blockchain related information
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Context
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// StateDB gives access to the underlying state
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StateDB StateDB
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// Depth is the current call stack
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depth int
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// chainConfig contains information about the current chain
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chainConfig *params.ChainConfig
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// chain rules contains the chain rules for the current epoch
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chainRules params.Rules
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// virtual machine configuration options used to initialise the
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// evm.
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vmConfig Config
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// global (to this context) ethereum virtual machine
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// used throughout the execution of the tx.
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interpreters []Interpreter
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interpreter Interpreter
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// abort is used to abort the EVM calling operations
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// NOTE: must be set atomically
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abort int32
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// callGasTemp holds the gas available for the current call. This is needed because the
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// available gas is calculated in gasCall* according to the 63/64 rule and later
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// applied in opCall*.
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callGasTemp uint64
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}
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// NewEVM returns a new EVM. The returned EVM is not thread safe and should
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// only ever be used *once*.
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func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
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evm := &EVM{
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Context: ctx,
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StateDB: statedb,
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vmConfig: vmConfig,
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chainConfig: chainConfig,
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chainRules: chainConfig.Rules(ctx.BlockNumber),
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interpreters: make([]Interpreter, 1),
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}
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evm.interpreters[0] = NewEVMInterpreter(evm, vmConfig)
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evm.interpreter = evm.interpreters[0]
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return evm
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}
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// Cancel cancels any running EVM operation. This may be called concurrently and
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// it's safe to be called multiple times.
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func (evm *EVM) Cancel() {
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atomic.StoreInt32(&evm.abort, 1)
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}
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// Interpreter returns the current interpreter
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func (evm *EVM) Interpreter() Interpreter {
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return evm.interpreter
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}
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// Call executes the contract associated with the addr with the given input as
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// parameters. It also handles any necessary value transfer required and takes
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// the necessary steps to create accounts and reverses the state in case of an
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// execution error or failed value transfer.
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func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Fail if we're trying to execute above the call depth limit
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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// Fail if we're trying to transfer more than the available balance
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if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, gas, ErrInsufficientBalance
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}
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var (
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to = AccountRef(addr)
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snapshot = evm.StateDB.Snapshot()
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)
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if !evm.StateDB.Exist(addr) {
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precompiles := PrecompiledContractsHomestead
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if evm.ChainConfig().IsByzantium(evm.BlockNumber) {
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precompiles = PrecompiledContractsByzantium
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}
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if precompiles[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
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// Calling a non existing account, don't do anything, but ping the tracer
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if evm.vmConfig.Debug && evm.depth == 0 {
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evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value)
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evm.vmConfig.Tracer.CaptureEnd(ret, 0, 0, nil)
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}
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return nil, gas, nil
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}
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evm.StateDB.CreateAccount(addr)
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}
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evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
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// Initialise a new contract and set the code that is to be used by the EVM.
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// The contract is a scoped environment for this execution context only.
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contract := NewContract(caller, to, value, gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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start := time.Now()
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// Capture the tracer start/end events in debug mode
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if evm.vmConfig.Debug && evm.depth == 0 {
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evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value)
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defer func() { // Lazy evaluation of the parameters
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evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
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}()
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}
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ret, err = run(evm, contract, input, false)
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in homestead this also counts for code storage gas errors.
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if err != nil {
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evm.StateDB.RevertToSnapshot(snapshot)
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if err != errExecutionReverted {
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contract.UseGas(contract.Gas)
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}
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}
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return ret, contract.Gas, err
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}
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// CallCode executes the contract associated with the addr with the given input
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// as parameters. It also handles any necessary value transfer required and takes
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// the necessary steps to create accounts and reverses the state in case of an
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// execution error or failed value transfer.
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//
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// CallCode differs from Call in the sense that it executes the given address'
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// code with the caller as context.
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func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Fail if we're trying to execute above the call depth limit
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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// Fail if we're trying to transfer more than the available balance
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if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, gas, ErrInsufficientBalance
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}
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var (
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snapshot = evm.StateDB.Snapshot()
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to = AccountRef(caller.Address())
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)
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// initialise a new contract and set the code that is to be used by the
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// EVM. The contract is a scoped environment for this execution context
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// only.
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contract := NewContract(caller, to, value, gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = run(evm, contract, input, false)
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if err != nil {
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evm.StateDB.RevertToSnapshot(snapshot)
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if err != errExecutionReverted {
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contract.UseGas(contract.Gas)
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}
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}
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return ret, contract.Gas, err
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}
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// DelegateCall executes the contract associated with the addr with the given input
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// as parameters. It reverses the state in case of an execution error.
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//
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// DelegateCall differs from CallCode in the sense that it executes the given address'
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// code with the caller as context and the caller is set to the caller of the caller.
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func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Fail if we're trying to execute above the call depth limit
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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var (
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snapshot = evm.StateDB.Snapshot()
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to = AccountRef(caller.Address())
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)
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// Initialise a new contract and make initialise the delegate values
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contract := NewContract(caller, to, nil, gas).AsDelegate()
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = run(evm, contract, input, false)
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if err != nil {
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evm.StateDB.RevertToSnapshot(snapshot)
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if err != errExecutionReverted {
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contract.UseGas(contract.Gas)
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}
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}
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return ret, contract.Gas, err
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}
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// StaticCall executes the contract associated with the addr with the given input
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// as parameters while disallowing any modifications to the state during the call.
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// Opcodes that attempt to perform such modifications will result in exceptions
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// instead of performing the modifications.
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func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Fail if we're trying to execute above the call depth limit
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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var (
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to = AccountRef(addr)
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snapshot = evm.StateDB.Snapshot()
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)
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// Initialise a new contract and set the code that is to be used by the
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// EVM. The contract is a scoped environment for this execution context
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// only.
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contract := NewContract(caller, to, new(big.Int), gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in Homestead this also counts for code storage gas errors.
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ret, err = run(evm, contract, input, true)
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if err != nil {
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evm.StateDB.RevertToSnapshot(snapshot)
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if err != errExecutionReverted {
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contract.UseGas(contract.Gas)
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}
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}
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return ret, contract.Gas, err
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}
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// create creates a new contract using code as deployment code.
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func (evm *EVM) create(caller ContractRef, code []byte, gas uint64, value *big.Int, address common.Address) ([]byte, common.Address, uint64, error) {
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, common.Address{}, gas, ErrDepth
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}
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if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, common.Address{}, gas, ErrInsufficientBalance
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}
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nonce := evm.StateDB.GetNonce(caller.Address())
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evm.StateDB.SetNonce(caller.Address(), nonce+1)
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// Ensure there's no existing contract already at the designated address
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contractHash := evm.StateDB.GetCodeHash(address)
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if evm.StateDB.GetNonce(address) != 0 || (contractHash != (common.Hash{}) && contractHash != emptyCodeHash) {
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return nil, common.Address{}, 0, ErrContractAddressCollision
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}
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// Create a new account on the state
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snapshot := evm.StateDB.Snapshot()
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evm.StateDB.CreateAccount(address)
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if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
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evm.StateDB.SetNonce(address, 1)
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}
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evm.Transfer(evm.StateDB, caller.Address(), address, value)
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// initialise a new contract and set the code that is to be used by the
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// EVM. The contract is a scoped environment for this execution context
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// only.
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contract := NewContract(caller, AccountRef(address), value, gas)
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contract.SetCallCode(&address, crypto.Keccak256Hash(code), code)
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, address, gas, nil
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}
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if evm.vmConfig.Debug && evm.depth == 0 {
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evm.vmConfig.Tracer.CaptureStart(caller.Address(), address, true, code, gas, value)
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}
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start := time.Now()
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ret, err := run(evm, contract, nil, false)
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// check whether the max code size has been exceeded
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maxCodeSizeExceeded := evm.ChainConfig().IsEIP158(evm.BlockNumber) && len(ret) > params.MaxCodeSize
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// if the contract creation ran successfully and no errors were returned
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// calculate the gas required to store the code. If the code could not
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// be stored due to not enough gas set an error and let it be handled
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// by the error checking condition below.
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if err == nil && !maxCodeSizeExceeded {
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createDataGas := uint64(len(ret)) * params.CreateDataGas
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if contract.UseGas(createDataGas) {
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evm.StateDB.SetCode(address, ret)
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} else {
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err = ErrCodeStoreOutOfGas
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}
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}
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in homestead this also counts for code storage gas errors.
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if maxCodeSizeExceeded || (err != nil && (evm.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
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evm.StateDB.RevertToSnapshot(snapshot)
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if err != errExecutionReverted {
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contract.UseGas(contract.Gas)
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}
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}
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// Assign err if contract code size exceeds the max while the err is still empty.
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if maxCodeSizeExceeded && err == nil {
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err = errMaxCodeSizeExceeded
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}
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if evm.vmConfig.Debug && evm.depth == 0 {
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evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
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}
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return ret, address, contract.Gas, err
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}
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// Create creates a new contract using code as deployment code.
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func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
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contractAddr = crypto.CreateAddress(caller.Address(), evm.StateDB.GetNonce(caller.Address()))
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return evm.create(caller, code, gas, value, contractAddr)
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}
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// Create2 creates a new contract using code as deployment code.
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//
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// The different between Create2 with Create is Create2 uses sha3(0xff ++ msg.sender ++ salt ++ sha3(init_code))[12:]
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// instead of the usual sender-and-nonce-hash as the address where the contract is initialized at.
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func (evm *EVM) Create2(caller ContractRef, code []byte, gas uint64, endowment *big.Int, salt *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
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contractAddr = crypto.CreateAddress2(caller.Address(), common.BigToHash(salt), code)
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return evm.create(caller, code, gas, endowment, contractAddr)
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}
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// ChainConfig returns the environment's chain configuration
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func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
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