plugeth/ethchain/state_transition.go
2014-10-08 11:59:44 +02:00

297 lines
7.4 KiB
Go

package ethchain
import (
"fmt"
"math/big"
"github.com/ethereum/eth-go/ethstate"
"github.com/ethereum/eth-go/ethtrie"
"github.com/ethereum/eth-go/ethutil"
"github.com/ethereum/eth-go/ethvm"
)
/*
* 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, receiver []byte
tx *Transaction
gas, gasPrice *big.Int
value *big.Int
data []byte
state *ethstate.State
block *Block
cb, rec, sen *ethstate.StateObject
}
func NewStateTransition(coinbase *ethstate.StateObject, tx *Transaction, state *ethstate.State, block *Block) *StateTransition {
return &StateTransition{coinbase.Address(), tx.Recipient, tx, new(big.Int), new(big.Int).Set(tx.GasPrice), tx.Value, tx.Data, state, block, coinbase, nil, nil}
}
func (self *StateTransition) Coinbase() *ethstate.StateObject {
if self.cb != nil {
return self.cb
}
self.cb = self.state.GetOrNewStateObject(self.coinbase)
return self.cb
}
func (self *StateTransition) Sender() *ethstate.StateObject {
if self.sen != nil {
return self.sen
}
self.sen = self.state.GetOrNewStateObject(self.tx.Sender())
return self.sen
}
func (self *StateTransition) Receiver() *ethstate.StateObject {
if self.tx != nil && self.tx.CreatesContract() {
return nil
}
if self.rec != nil {
return self.rec
}
self.rec = self.state.GetOrNewStateObject(self.tx.Recipient)
return self.rec
}
func (self *StateTransition) MakeStateObject(state *ethstate.State, tx *Transaction) *ethstate.StateObject {
contract := MakeContract(tx, state)
return contract
}
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.Sender()
if sender.Balance.Cmp(self.tx.GasValue()) < 0 {
return fmt.Errorf("Insufficient funds to pre-pay gas. Req %v, has %v", self.tx.GasValue(), sender.Balance)
}
coinbase := self.Coinbase()
err = coinbase.BuyGas(self.tx.Gas, self.tx.GasPrice)
if err != nil {
return err
}
self.AddGas(self.tx.Gas)
sender.SubAmount(self.tx.GasValue())
return nil
}
func (self *StateTransition) RefundGas() {
coinbase, sender := self.Coinbase(), self.Sender()
coinbase.RefundGas(self.gas, self.tx.GasPrice)
// Return remaining gas
remaining := new(big.Int).Mul(self.gas, self.tx.GasPrice)
sender.AddAmount(remaining)
}
func (self *StateTransition) preCheck() (err error) {
var (
tx = self.tx
sender = self.Sender()
)
// Make sure this transaction's nonce is correct
if sender.Nonce != tx.Nonce {
return NonceError(tx.Nonce, sender.Nonce)
}
// Pre-pay gas / Buy gas of the coinbase account
if err = self.BuyGas(); err != nil {
return err
}
return nil
}
func (self *StateTransition) TransitionState() (err error) {
statelogger.Debugf("(~) %x\n", self.tx.Hash())
defer func() {
if r := recover(); r != nil {
statelogger.Infoln(r)
err = fmt.Errorf("state transition err %v", r)
}
}()
// XXX Transactions after this point are considered valid.
if err = self.preCheck(); err != nil {
return
}
var (
tx = self.tx
sender = self.Sender()
receiver *ethstate.StateObject
)
defer self.RefundGas()
// Increment the nonce for the next transaction
sender.Nonce += 1
// Transaction gas
if err = self.UseGas(ethvm.GasTx); err != nil {
return
}
// Pay data gas
dataPrice := big.NewInt(int64(len(self.data)))
dataPrice.Mul(dataPrice, ethvm.GasData)
if err = self.UseGas(dataPrice); err != nil {
return
}
if sender.Balance.Cmp(self.value) < 0 {
return fmt.Errorf("Insufficient funds to transfer value. Req %v, has %v", self.value, sender.Balance)
}
var snapshot *ethstate.State
// If the receiver is nil it's a contract (\0*32).
if tx.CreatesContract() {
// Subtract the (irreversible) amount from the senders account
sender.SubAmount(self.value)
snapshot = self.state.Copy()
// Create a new state object for the contract
receiver = self.MakeStateObject(self.state, tx)
self.rec = receiver
if receiver == nil {
return fmt.Errorf("Unable to create contract")
}
// Add the amount to receivers account which should conclude this transaction
receiver.AddAmount(self.value)
} else {
receiver = self.Receiver()
// Subtract the amount from the senders account
sender.SubAmount(self.value)
// Add the amount to receivers account which should conclude this transaction
receiver.AddAmount(self.value)
snapshot = self.state.Copy()
}
msg := self.state.Manifest().AddMessage(&ethstate.Message{
To: receiver.Address(), From: sender.Address(),
Input: self.tx.Data,
Origin: sender.Address(),
Block: self.block.Hash(), Timestamp: self.block.Time, Coinbase: self.block.Coinbase, Number: self.block.Number,
Value: self.value,
})
// Process the init code and create 'valid' contract
if IsContractAddr(self.receiver) {
// Evaluate the initialization script
// and use the return value as the
// script section for the state object.
self.data = nil
code, err := self.Eval(msg, receiver.Init(), receiver, "init")
if err != nil {
self.state.Set(snapshot)
return fmt.Errorf("Error during init execution %v", err)
}
receiver.Code = code
msg.Output = code
} else {
if len(receiver.Code) > 0 {
ret, err := self.Eval(msg, receiver.Code, receiver, "code")
if err != nil {
self.state.Set(snapshot)
return fmt.Errorf("Error during code execution %v", err)
}
msg.Output = ret
}
}
return
}
func (self *StateTransition) transferValue(sender, receiver *ethstate.StateObject) error {
if sender.Balance.Cmp(self.value) < 0 {
return fmt.Errorf("Insufficient funds to transfer value. Req %v, has %v", self.value, sender.Balance)
}
// Subtract the amount from the senders account
sender.SubAmount(self.value)
// Add the amount to receivers account which should conclude this transaction
receiver.AddAmount(self.value)
return nil
}
func (self *StateTransition) Eval(msg *ethstate.Message, script []byte, context *ethstate.StateObject, typ string) (ret []byte, err error) {
var (
transactor = self.Sender()
state = self.state
env = NewEnv(state, self.tx, self.block)
callerClosure = ethvm.NewClosure(msg, transactor, context, script, self.gas, self.gasPrice)
)
vm := ethvm.New(env)
vm.Verbose = true
vm.Fn = typ
ret, _, err = callerClosure.Call(vm, self.tx.Data)
return
}
// Converts an transaction in to a state object
func MakeContract(tx *Transaction, state *ethstate.State) *ethstate.StateObject {
// Create contract if there's no recipient
if tx.IsContract() {
addr := tx.CreationAddress(state)
contract := state.GetOrNewStateObject(addr)
contract.InitCode = tx.Data
contract.State = ethstate.New(ethtrie.New(ethutil.Config.Db, ""))
return contract
}
return nil
}