Official Go implementation of the Ethereum protocol
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go-ethereum/core/state_transition.go

260 lines
6.8 KiB

// 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/state"
"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"
)
/*
* 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 / buy gas of the coinbase (miner)
* 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, gasPrice *big.Int
initialGas *big.Int
value *big.Int
data []byte
state *state.StateDB
env vm.Environment
}
// Message represents a message sent to a contract.
type Message interface {
From() (common.Address, error)
To() *common.Address
GasPrice() *big.Int
Gas() *big.Int
Value() *big.Int
Nonce() uint64
Data() []byte
}
func MessageCreatesContract(msg Message) bool {
return msg.To() == nil
}
// IntrinsicGas computes the 'intrisic gas' for a message
// with the given data.
func IntrinsicGas(data []byte) *big.Int {
igas := new(big.Int).Set(params.TxGas)
if len(data) > 0 {
var nz int64
for _, byt := range data {
if byt != 0 {
nz++
}
}
m := big.NewInt(nz)
m.Mul(m, params.TxDataNonZeroGas)
igas.Add(igas, m)
m.SetInt64(int64(len(data)) - nz)
m.Mul(m, params.TxDataZeroGas)
igas.Add(igas, m)
}
return igas
}
func ApplyMessage(env vm.Environment, msg Message, gp GasPool) ([]byte, *big.Int, error) {
return NewStateTransition(env, msg, gp).transitionState()
}
func NewStateTransition(env vm.Environment, msg Message, gp GasPool) *StateTransition {
return &StateTransition{
gp: gp,
env: env,
msg: msg,
gas: new(big.Int),
gasPrice: msg.GasPrice(),
initialGas: new(big.Int),
value: msg.Value(),
data: msg.Data(),
state: env.State(),
}
}
func (self *StateTransition) From() (*state.StateObject, error) {
f, err := self.msg.From()
if err != nil {
return nil, err
}
return self.state.GetOrNewStateObject(f), nil
}
func (self *StateTransition) To() *state.StateObject {
if self.msg == nil {
return nil
}
to := self.msg.To()
if to == nil {
return nil // contract creation
}
return self.state.GetOrNewStateObject(*to)
}
func (self *StateTransition) UseGas(amount *big.Int) error {
if self.gas.Cmp(amount) < 0 {
return vm.OutOfGasError
}
self.gas.Sub(self.gas, amount)
return nil
}
func (self *StateTransition) AddGas(amount *big.Int) {
self.gas.Add(self.gas, amount)
}
func (self *StateTransition) BuyGas() error {
mgas := self.msg.Gas()
mgval := new(big.Int).Mul(mgas, self.gasPrice)
sender, err := self.From()
if err != nil {
return err
}
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, self.gasPrice); err != nil {
return err
}
self.AddGas(mgas)
self.initialGas.Set(mgas)
sender.SubBalance(mgval)
return nil
}
func (self *StateTransition) preCheck() (err error) {
msg := self.msg
sender, err := self.From()
if err != nil {
return err
}
// Make sure this transaction's nonce is correct
if sender.Nonce() != msg.Nonce() {
return NonceError(msg.Nonce(), sender.Nonce())
}
// Pre-pay gas / Buy gas of the coinbase account
if err = self.BuyGas(); err != nil {
if state.IsGasLimitErr(err) {
return err
}
return InvalidTxError(err)
}
return nil
}
func (self *StateTransition) transitionState() (ret []byte, usedGas *big.Int, err error) {
if err = self.preCheck(); err != nil {
return
}
msg := self.msg
sender, _ := self.From() // err checked in preCheck
// Pay intrinsic gas
if err = self.UseGas(IntrinsicGas(self.data)); err != nil {
return nil, nil, InvalidTxError(err)
}
vmenv := self.env
var ref vm.ContextRef
if MessageCreatesContract(msg) {
ret, err, ref = vmenv.Create(sender, self.data, self.gas, self.gasPrice, self.value)
if err == nil {
dataGas := big.NewInt(int64(len(ret)))
dataGas.Mul(dataGas, params.CreateDataGas)
if err := self.UseGas(dataGas); err == nil {
ref.SetCode(ret)
} else {
ret = nil // does not affect consensus but useful for StateTests validations
glog.V(logger.Core).Infoln("Insufficient gas for creating code. Require", dataGas, "and have", self.gas)
}
}
glog.V(logger.Core).Infoln("VM create err:", err)
} else {
// Increment the nonce for the next transaction
self.state.SetNonce(sender.Address(), sender.Nonce()+1)
ret, err = vmenv.Call(sender, self.To().Address(), self.data, self.gas, self.gasPrice, self.value)
glog.V(logger.Core).Infoln("VM call err:", err)
}
if err != nil && IsValueTransferErr(err) {
return nil, nil, InvalidTxError(err)
}
// We aren't interested in errors here. Errors returned by the VM are non-consensus errors and therefor shouldn't bubble up
if err != nil {
err = nil
}
if vm.Debug {
vm.StdErrFormat(vmenv.StructLogs())
}
self.refundGas()
self.state.AddBalance(self.env.Coinbase(), new(big.Int).Mul(self.gasUsed(), self.gasPrice))
return ret, self.gasUsed(), err
}
func (self *StateTransition) refundGas() {
sender, _ := self.From() // err already checked
// Return remaining gas
remaining := new(big.Int).Mul(self.gas, self.gasPrice)
sender.AddBalance(remaining)
uhalf := remaining.Div(self.gasUsed(), common.Big2)
refund := common.BigMin(uhalf, self.state.Refunds())
self.gas.Add(self.gas, refund)
self.state.AddBalance(sender.Address(), refund.Mul(refund, self.gasPrice))
self.gp.AddGas(self.gas, self.gasPrice)
}
func (self *StateTransition) gasUsed() *big.Int {
return new(big.Int).Sub(self.initialGas, self.gas)
}