plugeth/core/state_transition.go
Jeffrey Wilcke c12f4df910 params: core, core/vm, miner: 64bit gas instructions
Reworked the EVM gas instructions to use 64bit integers rather than
arbitrary size big ints. All gas operations, be it additions,
multiplications or divisions, are checked and guarded against 64 bit
integer overflows.

In additon, most of the protocol paramaters in the params package have
been converted to uint64 and are now constants rather than variables.

* common/math: added overflow check ops
* core: vmenv, env renamed to evm
* eth, internal/ethapi, les: unmetered eth_call and cancel methods
* core/vm: implemented big.Int pool for evm instructions
* core/vm: unexported intPool methods & verification methods
* core/vm: added memoryGasCost overflow check and test
2017-02-13 21:44:25 +01:00

292 lines
8.0 KiB
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 core
import (
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/params"
)
var (
Big0 = big.NewInt(0)
)
/*
The State Transitioning Model
A state transition is a change made when a transaction is applied to the current world state
The state transitioning model does all all the necessary work to work out a valid new state root.
1) Nonce handling
2) Pre pay gas
3) Create a new state object if the recipient is \0*32
4) Value transfer
== If contract creation ==
4a) Attempt to run transaction data
4b) If valid, use result as code for the new state object
== end ==
5) Run Script section
6) Derive new state root
*/
type StateTransition struct {
gp *GasPool
msg Message
gas uint64
gasPrice *big.Int
initialGas *big.Int
value *big.Int
data []byte
state vm.StateDB
evm *vm.EVM
}
// Message represents a message sent to a contract.
type Message interface {
From() common.Address
//FromFrontier() (common.Address, error)
To() *common.Address
GasPrice() *big.Int
Gas() *big.Int
Value() *big.Int
Nonce() uint64
CheckNonce() bool
Data() []byte
}
func MessageCreatesContract(msg Message) bool {
return msg.To() == nil
}
// IntrinsicGas computes the 'intrinsic gas' for a message
// with the given data.
//
// TODO convert to uint64
func IntrinsicGas(data []byte, contractCreation, homestead bool) *big.Int {
igas := new(big.Int)
if contractCreation && homestead {
igas.SetUint64(params.TxGasContractCreation)
} else {
igas.SetUint64(params.TxGas)
}
if len(data) > 0 {
var nz int64
for _, byt := range data {
if byt != 0 {
nz++
}
}
m := big.NewInt(nz)
m.Mul(m, new(big.Int).SetUint64(params.TxDataNonZeroGas))
igas.Add(igas, m)
m.SetInt64(int64(len(data)) - nz)
m.Mul(m, new(big.Int).SetUint64(params.TxDataZeroGas))
igas.Add(igas, m)
}
return igas
}
// NewStateTransition initialises and returns a new state transition object.
func NewStateTransition(evm *vm.EVM, msg Message, gp *GasPool) *StateTransition {
return &StateTransition{
gp: gp,
evm: evm,
msg: msg,
gasPrice: msg.GasPrice(),
initialGas: new(big.Int),
value: msg.Value(),
data: msg.Data(),
state: evm.StateDB,
}
}
// ApplyMessage computes the new state by applying the given message
// against the old state within the environment.
//
// ApplyMessage returns the bytes returned by any EVM execution (if it took place),
// the gas used (which includes gas refunds) and an error if it failed. An error always
// indicates a core error meaning that the message would always fail for that particular
// state and would never be accepted within a block.
func ApplyMessage(evm *vm.EVM, msg Message, gp *GasPool) ([]byte, *big.Int, error) {
st := NewStateTransition(evm, msg, gp)
ret, _, gasUsed, err := st.TransitionDb()
return ret, gasUsed, err
}
func (self *StateTransition) from() vm.Account {
f := self.msg.From()
if !self.state.Exist(f) {
return self.state.CreateAccount(f)
}
return self.state.GetAccount(f)
}
func (self *StateTransition) to() vm.Account {
if self.msg == nil {
return nil
}
to := self.msg.To()
if to == nil {
return nil // contract creation
}
if !self.state.Exist(*to) {
return self.state.CreateAccount(*to)
}
return self.state.GetAccount(*to)
}
func (self *StateTransition) useGas(amount uint64) error {
if self.gas < amount {
return vm.ErrOutOfGas
}
self.gas -= amount
return nil
}
func (self *StateTransition) buyGas() error {
mgas := self.msg.Gas()
if mgas.BitLen() > 64 {
return vm.ErrOutOfGas
}
mgval := new(big.Int).Mul(mgas, self.gasPrice)
sender := self.from()
if sender.Balance().Cmp(mgval) < 0 {
return fmt.Errorf("insufficient ETH for gas (%x). Req %v, has %v", sender.Address().Bytes()[:4], mgval, sender.Balance())
}
if err := self.gp.SubGas(mgas); err != nil {
return err
}
self.gas += mgas.Uint64()
self.initialGas.Set(mgas)
sender.SubBalance(mgval)
return nil
}
func (self *StateTransition) preCheck() (err error) {
msg := self.msg
sender := self.from()
// Make sure this transaction's nonce is correct
if msg.CheckNonce() {
if n := self.state.GetNonce(sender.Address()); n != msg.Nonce() {
return NonceError(msg.Nonce(), n)
}
}
// Pre-pay gas
if err = self.buyGas(); err != nil {
if IsGasLimitErr(err) {
return err
}
return InvalidTxError(err)
}
return nil
}
// TransitionDb will transition the state by applying the current message and returning the result
// including the required gas for the operation as well as the used gas. It returns an error if it
// failed. An error indicates a consensus issue.
func (self *StateTransition) TransitionDb() (ret []byte, requiredGas, usedGas *big.Int, err error) {
if err = self.preCheck(); err != nil {
return
}
msg := self.msg
sender := self.from() // err checked in preCheck
homestead := self.evm.ChainConfig().IsHomestead(self.evm.BlockNumber)
contractCreation := MessageCreatesContract(msg)
// Pay intrinsic gas
// TODO convert to uint64
intrinsicGas := IntrinsicGas(self.data, contractCreation, homestead)
if intrinsicGas.BitLen() > 64 {
return nil, nil, nil, InvalidTxError(vm.ErrOutOfGas)
}
if err = self.useGas(intrinsicGas.Uint64()); err != nil {
return nil, nil, nil, InvalidTxError(err)
}
var (
evm = self.evm
// vm errors do not effect consensus and are therefor
// not assigned to err, except for insufficient balance
// error.
vmerr error
)
if contractCreation {
ret, _, self.gas, vmerr = evm.Create(sender, self.data, self.gas, self.value)
} else {
// Increment the nonce for the next transaction
self.state.SetNonce(sender.Address(), self.state.GetNonce(sender.Address())+1)
ret, self.gas, vmerr = evm.Call(sender, self.to().Address(), self.data, self.gas, self.value)
}
if vmerr != nil {
glog.V(logger.Core).Infoln("vm returned with error:", err)
// The only possible consensus-error would be if there wasn't
// sufficient balance to make the transfer happen. The first
// balance transfer may never fail.
if vmerr == vm.ErrInsufficientBalance {
return nil, nil, nil, InvalidTxError(vmerr)
}
}
requiredGas = new(big.Int).Set(self.gasUsed())
self.refundGas()
self.state.AddBalance(self.evm.Coinbase, new(big.Int).Mul(self.gasUsed(), self.gasPrice))
return ret, requiredGas, self.gasUsed(), err
}
func (self *StateTransition) refundGas() {
// Return eth for remaining gas to the sender account,
// exchanged at the original rate.
sender := self.from() // err already checked
remaining := new(big.Int).Mul(new(big.Int).SetUint64(self.gas), self.gasPrice)
sender.AddBalance(remaining)
// Apply refund counter, capped to half of the used gas.
uhalf := remaining.Div(self.gasUsed(), common.Big2)
refund := common.BigMin(uhalf, self.state.GetRefund())
self.gas += refund.Uint64()
self.state.AddBalance(sender.Address(), refund.Mul(refund, self.gasPrice))
// Also return remaining gas to the block gas counter so it is
// available for the next transaction.
self.gp.AddGas(new(big.Int).SetUint64(self.gas))
}
func (self *StateTransition) gasUsed() *big.Int {
return new(big.Int).Sub(self.initialGas, new(big.Int).SetUint64(self.gas))
}