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/crypto"
"github.com/ethereum/go-ethereum/params"
)
const tryJit = false
var ()
/*
* 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 {
coinbase common.Address
msg Message
gas, gasPrice *big.Int
initialGas *big.Int
value *big.Int
data []byte
state *state.StateDB
cb, rec, sen *state.StateObject
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 AddressFromMessage(msg Message) common.Address {
from, _ := msg.From()
return crypto.CreateAddress(from, msg.Nonce())
}
func MessageCreatesContract(msg Message) bool {
return msg.To() == nil
}
func MessageGasValue(msg Message) *big.Int {
return new(big.Int).Mul(msg.Gas(), msg.GasPrice())
}
func ApplyMessage(env vm.Environment, msg Message, coinbase *state.StateObject) ([]byte, *big.Int, error) {
return NewStateTransition(env, msg, coinbase).transitionState()
}
func NewStateTransition(env vm.Environment, msg Message, coinbase *state.StateObject) *StateTransition {
return &StateTransition{
coinbase: coinbase.Address(),
env: env,
msg: msg,
gas: new(big.Int),
gasPrice: new(big.Int).Set(msg.GasPrice()),
initialGas: new(big.Int),
value: msg.Value(),
data: msg.Data(),
state: env.State(),
cb: coinbase,
}
}
func (self *StateTransition) Coinbase() *state.StateObject {
return self.state.GetOrNewStateObject(self.coinbase)
}
func (self *StateTransition) From() *state.StateObject {
f, _ := self.msg.From()
return self.state.GetOrNewStateObject(f)
}
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 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 {
var err error
sender := self.From()
if sender.Balance().Cmp(MessageGasValue(self.msg)) < 0 {
return fmt.Errorf("insufficient ETH for gas (%x). Req %v, has %v", sender.Address().Bytes()[:4], MessageGasValue(self.msg), sender.Balance())
}
coinbase := self.Coinbase()
err = coinbase.BuyGas(self.msg.Gas(), self.msg.GasPrice())
if err != nil {
return err
}
self.AddGas(self.msg.Gas())
self.initialGas.Set(self.msg.Gas())
sender.SubBalance(MessageGasValue(self.msg))
return nil
}
func (self *StateTransition) preCheck() (err error) {
var (
msg = self.msg
sender = self.From()
)
// 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) {
// statelogger.Debugf("(~) %x\n", self.msg.Hash())
// XXX Transactions after this point are considered valid.
if err = self.preCheck(); err != nil {
return
}
var (
msg = self.msg
sender = self.From()
)
// Transaction gas
if err = self.UseGas(params.TxGas); err != nil {
return nil, nil, InvalidTxError(err)
}
// Pay data gas
dgas := new(big.Int)
for _, byt := range self.data {
if byt != 0 {
dgas.Add(dgas, params.TxDataNonZeroGas)
} else {
dgas.Add(dgas, params.TxDataZeroGas)
}
}
if err = self.UseGas(dgas); err != nil {
return nil, nil, InvalidTxError(err)
}
vmenv := self.env
var ref vm.ContextRef
if MessageCreatesContract(msg) {
ret, err, ref = vmenv.Create(sender, self.msg.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 {
statelogger.Infoln("Insufficient gas for creating code. Require", dataGas, "and have", self.gas)
}
}
} else {
// Increment the nonce for the next transaction
self.state.SetNonce(sender.Address(), sender.Nonce()+1)
ret, err = vmenv.Call(self.From(), self.To().Address(), self.msg.Data(), self.gas, self.gasPrice, self.value)
}
if err != nil && IsValueTransferErr(err) {
return nil, nil, InvalidTxError(err)
}
self.refundGas()
self.state.AddBalance(self.coinbase, new(big.Int).Mul(self.gasUsed(), self.gasPrice))
return ret, self.gasUsed(), err
}
func (self *StateTransition) refundGas() {
coinbase, sender := self.Coinbase(), self.From()
// Return remaining gas
remaining := new(big.Int).Mul(self.gas, self.msg.GasPrice())
sender.AddBalance(remaining)
uhalf := new(big.Int).Div(self.gasUsed(), common.Big2)
for addr, ref := range self.state.Refunds() {
refund := common.BigMin(uhalf, ref)
self.gas.Add(self.gas, refund)
self.state.AddBalance(common.StringToAddress(addr), refund.Mul(refund, self.msg.GasPrice()))
}
coinbase.RefundGas(self.gas, self.msg.GasPrice())
}
func (self *StateTransition) gasUsed() *big.Int {
return new(big.Int).Sub(self.initialGas, self.gas)
}
// Converts an message in to a state object
func makeContract(msg Message, state *state.StateDB) *state.StateObject {
faddr, _ := msg.From()
addr := crypto.CreateAddress(faddr, msg.Nonce())
contract := state.GetOrNewStateObject(addr)
contract.SetInitCode(msg.Data())
return contract
}