evm.go

// 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 tinywasm

import (
	"errors"
	"math/big"
	"sync/atomic"
	"time"

	"github.com/tinychain/tinychain/common"
	"github.com/tinychain/tinychain/core/vm"
	"github.com/tinychain/tinychain/core/vm/evm/crypto"
)

// 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)
	errWriteProtection       = errors.New("evm: write protection")
	errReturnDataOutOfBounds = errors.New("evm: return data out of bounds")
	errExecutionReverted     = errors.New("evm: execution reverted")
	errMaxCodeSizeExceeded   = errors.New("evm: max code size exceeded")
)

type (
	// CanTransferFunc is the signature of a transfer guard function
	CanTransferFunc func(vm.StateDB, common.Address, *big.Int) bool
	// TransferFunc is the signature of a transfer function
	TransferFunc func(vm.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
)

// 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) ([]byte, error) {
	if contract.CodeAddr != nil {
		precompiles := PrecompiledContractsByzantium
		if p := precompiles[*contract.CodeAddr]; p != nil {
			return RunPrecompiledContract(p, input, contract)
		}
	}

	if evm.interpreter.CanRun(contract.Code) {

		return evm.interpreter.Run(contract, input)
	}
	return nil, vm.ErrNoCompatibleInterpreter
}

// Config are the configuration options for the Interpreter
type Config struct {
	// Debug enabled debugging Interpreter options
	Debug bool
	// Tracer is the op code logger
	Tracer Tracer
	// NoRecursion disabled Interpreter call, callcode,
	// delegate call and create.
	NoRecursion bool
	// Enable recording of SHA3/keccak preimages
	EnablePreimageRecording bool
	// Type of the EWASM interpreter
	EWASMInterpreter string
	// Type of the EVM interpreter
	EVMInterpreter string
}

// Interpreter is used to run Ethereum based contracts and will utilise the
// passed environment to query external sources for state information.
// The Interpreter will run the byte code VM based on the passed
// configuration.
type Interpreter interface {
	// Run loops and evaluates the contract's code with the given input data and returns
	// the return byte-slice and an error if one occurred.
	Run(contract *Contract, input []byte) ([]byte, error)
	// CanRun tells if the contract, passed as an argument, can be
	// run by the current interpreter. This is meant so that the
	// caller can do something like:
	//
	// ```golang
	// for _, interpreter := range interpreters {
	//   if interpreter.CanRun(contract.code) {
	//     interpreter.Run(contract.code, input)
	//   }
	// }
	// ```
	CanRun([]byte) bool
	// IsReadOnly reports if the interpreter is in read only mode.
	IsReadOnly() bool
	// SetReadOnly sets (or unsets) read only mode in the interpreter.
	SetReadOnly(bool)
}

// 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
	// vm.StateDB gives access to the underlying state
	StateDB vm.StateDB
	// Depth is the current call stack
	depth int
	// 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
	// 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 vm.StateDB, vmConfig Config) *EVM {
	evm := &EVM{
		Context:  ctx,
		StateDB:  StateDB,
		vmConfig: vmConfig,
	}

	evm.interpreter = NewWasmIntptr(evm)

	return evm
}

func (evm *EVM) DB() vm.StateDB {
	return evm.StateDB
}

// Coinbase returns the address of block producer
func (evm *EVM) Coinbase() common.Address {
	return evm.Context.Coinbase
}

// 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)
}

// 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 vm.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(maxCallDepth) {
		return nil, gas, vm.ErrDepth
	}
	// Fail if we're trying to transfer more than the available balance
	if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
		return nil, gas, vm.ErrInsufficientBalance
	}

	var (
		to       = AccountRef(addr)
		snapshot = evm.StateDB.Snapshot()
	)
	if !evm.StateDB.Exist(addr) {
		precompiles := PrecompiledContractsByzantium
		if precompiles[addr] == nil && 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(), to.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, to, value, gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	start := time.Now()

	// 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() { // Lazy evaluation of the parameters
			evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
		}()
	}
	ret, err = run(evm, 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 {
		evm.StateDB.RevertToSnapshot(snapshot)
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	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 vm.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(maxCallDepth) {
		return nil, gas, vm.ErrDepth
	}
	// Fail if we're trying to transfer more than the available balance
	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
		return nil, gas, vm.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
	// EVM. The contract is a scoped environment for this execution context
	// only.
	contract := NewContract(caller, to, value, gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	ret, err = run(evm, contract, input)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot)
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	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 vm.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 > maxCallDepth {
		return nil, gas, vm.ErrDepth
	}

	var (
		snapshot = evm.StateDB.Snapshot()
		to       = AccountRef(caller.Address())
	)

	// Initialise 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 = run(evm, contract, input)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot)
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.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 vm.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'r  e trying to execute above the call depth limit
	if evm.depth > maxCallDepth {
		return nil, gas, vm.ErrDepth
	}
	// Make sure the readonly is only set if we aren't in readonly yet
	// this makes also sure that the readonly flag isn't removed for
	// child calls.
	if !evm.interpreter.IsReadOnly() {
		evm.interpreter.SetReadOnly(true)
		defer func() { evm.interpreter.SetReadOnly(false) }()
	}

	var (
		to       = AccountRef(addr)
		snapshot = evm.StateDB.Snapshot()
	)
	// 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, to, new(big.Int), gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	// 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)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot)
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.Gas, err
}

// create creates a new contract using code as deployment code.
func (evm *EVM) create(caller vm.ContractRef, code []byte, 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 > maxCallDepth {
		return nil, common.Address{}, gas, vm.ErrDepth
	}
	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
		return nil, common.Address{}, gas, vm.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, vm.ErrContractAddressCollision
	}
	// Create a new account on the state
	snapshot := evm.StateDB.Snapshot()
	evm.StateDB.CreateAccount(address)
	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.SetCallCode(&address, crypto.Keccak256Hash(code), code)

	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, code, gas, value)
	}
	start := time.Now()

	ret, err := run(evm, contract, nil)

	// check whether the max code size has been exceeded
	maxCodeSizeExceeded := len(ret) > 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)) * GasCostCreateData
		if contract.UseGas(createDataGas) {
			evm.StateDB.SetCode(address, ret)
		} else {
			err = vm.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 && err != vm.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 vm.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, 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 vm.ContractRef, code []byte, gas uint64, endowment *big.Int, salt *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
	contractAddr = crypto.CreateAddress2(caller.Address(), common.BigToHash(salt), code)
	return evm.create(caller, code, gas, endowment, contractAddr)
}