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state_processor.go
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/
state_processor.go
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/*
* Copyright 2018 KardiaChain
* This file is part of the go-kardia library.
*
* The go-kardia 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-kardia 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-kardia library. If not, see <http://www.gnu.org/licenses/>.
*/
package blockchain
import (
"math/big"
"github.com/kardiachain/go-kardia/configs"
"github.com/kardiachain/go-kardia/kai/state"
"github.com/kardiachain/go-kardia/kvm"
"github.com/kardiachain/go-kardia/lib/common"
"github.com/kardiachain/go-kardia/lib/crypto"
"github.com/kardiachain/go-kardia/lib/log"
vm "github.com/kardiachain/go-kardia/mainchain/kvm"
"github.com/kardiachain/go-kardia/mainchain/tx_pool"
"github.com/kardiachain/go-kardia/types"
)
// StateProcessor is a basic Processor, which takes care of transitioning
// state from one point to another.
//
// StateProcessor implements Processor.
type StateProcessor struct {
logger log.Logger
bc *BlockChain // Canonical blockchain
}
// NewStateProcessor initialises a new StateProcessor.
func NewStateProcessor(bc *BlockChain) *StateProcessor {
return &StateProcessor{
logger: log.New(),
bc: bc,
}
}
// Process processes the state changes according to the Kardia rules by running
// the transaction messages using the statedb.
//
// Process returns the receipts and logs accumulated during the process and
// returns the amount of gas that was used in the process. If any of the
// transactions failed to execute due to insufficient gas it will return an error.
func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg kvm.Config) (types.Receipts, []*types.Log, uint64, error) {
var (
receipts types.Receipts
usedGas = new(uint64)
header = block.Header()
allLogs []*types.Log
gp = new(types.GasPool).AddGas(block.GasLimit())
)
// Iterate over and process the individual transactions
for i, tx := range block.Transactions() {
statedb.Prepare(tx.Hash(), block.Hash(), i)
receipt, _, err := ApplyTransaction(p.bc.chainConfig, p.logger, p.bc, gp, statedb, header, tx, usedGas, cfg)
if err != nil {
return nil, nil, 0, err
}
receipts = append(receipts, receipt)
allLogs = append(allLogs, receipt.Logs...)
}
return receipts, allLogs, *usedGas, nil
}
// ApplyTransaction attempts to apply a transaction to the given state database
// and uses the input parameters for its environment. It returns the receipt
// for the transaction, gas used and an error if the transaction failed,
// indicating the block was invalid.
func ApplyTransaction(config *configs.ChainConfig, logger log.Logger, bc vm.ChainContext, gp *types.GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *uint64, cfg kvm.Config) (*types.Receipt, uint64, error) {
msg, err := tx.AsMessage(types.MakeSigner(config, &header.Height))
if err != nil {
return nil, 0, err
}
logger.Trace("Apply transaction", "hash", tx.Hash().Hex(), "nonce", msg.Nonce(), "from", msg.From().Hex())
// Create a new context to be used in the KVM environment
context := vm.NewKVMContext(msg, header, bc)
txContext := NewKVMTxContext(msg)
// Create a new environment which holds all relevant information
// about the transaction and calling mechanisms.
vmenv := kvm.NewKVM(context, txContext, statedb, bc.Config(), cfg)
vmenv.Reset(txContext, statedb)
// Apply the transaction to the current state (included in the env)
result, err := ApplyMessage(vmenv, msg, gp)
if err != nil {
return nil, 0, err
}
// Update the state with pending changes
statedb.Finalise(true)
*usedGas += result.UsedGas
// Create a new receipt for the transaction, storing the intermediate root and gas used by the tx,
// we're passing whether the root touch-delete accounts.
receipt := types.NewReceipt(result.Failed(), *usedGas)
receipt.TxHash = tx.Hash()
receipt.GasUsed = result.UsedGas
// if the transaction created a contract, store the creation address in the receipt.
if msg.To() == nil {
receipt.ContractAddress = crypto.CreateAddress(vmenv.TxContext.Origin, tx.Nonce())
}
// Set the receipt logs and create a bloom for filtering
receipt.Logs = statedb.GetLogs(tx.Hash(), header.Height, header.Hash())
receipt.Bloom = types.CreateBloom(types.Receipts{receipt})
return receipt, result.UsedGas, err
}
/*
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 *types.GasPool
msg Message
gas uint64
gasPrice *big.Int
initialGas uint64
value *big.Int
data []byte
state kvm.StateDB
vm *kvm.KVM
}
// Message represents a message sent to a contract.
type Message interface {
From() common.Address
To() *common.Address
GasPrice() *big.Int
Gas() uint64
Value() *big.Int
Nonce() uint64
CheckNonce() bool
Data() []byte
}
// NewStateTransition initialises and returns a new state transition object.
func NewStateTransition(kvm *kvm.KVM, msg Message, gp *types.GasPool) *StateTransition {
return &StateTransition{
gp: gp,
vm: kvm,
msg: msg,
gasPrice: msg.GasPrice(),
value: msg.Value(),
data: msg.Data(),
state: kvm.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 KVM 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(kvm *kvm.KVM, msg Message, gp *types.GasPool) (*kvm.ExecutionResult, error) {
return NewStateTransition(kvm, msg, gp).TransitionDb()
}
// to returns the recipient of the message.
func (st *StateTransition) to() common.Address {
if st.msg == nil || st.msg.To() == nil /* contract creation */ {
return common.Address{}
}
return *st.msg.To()
}
func (st *StateTransition) buyGas() error {
mgval := new(big.Int).Mul(new(big.Int).SetUint64(st.msg.Gas()), st.gasPrice)
if st.state.GetBalance(st.msg.From()).Cmp(mgval) < 0 {
return tx_pool.ErrInsufficientFunds
}
if err := st.gp.SubGas(st.msg.Gas()); err != nil {
return err
}
st.gas += st.msg.Gas()
st.initialGas = st.msg.Gas()
st.state.SubBalance(st.msg.From(), mgval)
return nil
}
func (st *StateTransition) preCheck() error {
// Make sure this transaction's nonce is correct.
if st.msg.CheckNonce() {
nonce := st.state.GetNonce(st.msg.From())
if nonce < st.msg.Nonce() {
return tx_pool.ErrNonceTooHigh
} else if nonce > st.msg.Nonce() {
return tx_pool.ErrNonceTooLow
}
}
return st.buyGas()
}
// TransitionDb will transition the state by applying the current message and
// returning the result including the the used gas. It returns an error if it
// failed. An error indicates a consensus issue.
func (st *StateTransition) TransitionDb() (*kvm.ExecutionResult, error) {
// First check this message satisfies all consensus rules before
// applying the message. The rules include these clauses
//
// 1. the nonce of the message caller is correct
// 2. caller has enough balance to cover transaction fee(gaslimit * gasprice)
// 3. the amount of gas required is available in the block
// 4. the purchased gas is enough to cover intrinsic usage
// 5. there is no overflow when calculating intrinsic gas
// 6. caller has enough balance to cover asset transfer for **topmost** call
// Check clauses 1-3, buy gas if everything is correct
if err := st.preCheck(); err != nil {
return nil, err
}
msg := st.msg
sender := kvm.AccountRef(msg.From())
contractCreation := msg.To() == nil
var (
height = st.vm.BlockContext.BlockHeight.Uint64()
)
// Check clauses 4-5, subtract intrinsic gas if everything is correct
isGalaxias := st.vm.ChainConfig().IsGalaxias(&height)
gas, err := tx_pool.IntrinsicGas(st.data, contractCreation, !isGalaxias)
if err != nil {
return nil, err
}
if st.gas < gas {
return nil, tx_pool.ErrIntrinsicGas
}
st.gas -= gas
// Check clause 6
if msg.Value().Sign() > 0 && !st.vm.CanTransfer(st.state, msg.From(), msg.Value()) {
return nil, tx_pool.ErrInsufficientFundsForTransfer
}
var (
ret []byte
vmerr error
)
if contractCreation {
ret, _, st.gas, vmerr = st.vm.Create(sender, st.data, st.gas, st.value)
} else {
// Increment the nonce for the next transaction
st.state.SetNonce(msg.From(), st.state.GetNonce(sender.Address())+1)
ret, st.gas, vmerr = st.vm.Call(sender, st.to(), st.data, st.gas, st.value)
}
st.refundGas()
st.state.AddBalance(st.vm.Coinbase, new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), st.gasPrice))
return &kvm.ExecutionResult{
UsedGas: st.gasUsed(),
Err: vmerr,
ReturnData: ret,
}, nil
}
func (st *StateTransition) refundGas() {
// Apply refund counter, capped to half of the used gas.
refund := st.gasUsed() / 2
if refund > st.state.GetRefund() {
refund = st.state.GetRefund()
}
st.gas += refund
// Return KAI for remaining gas, exchanged at the original rate.
remaining := new(big.Int).Mul(new(big.Int).SetUint64(st.gas), st.gasPrice)
st.state.AddBalance(st.msg.From(), remaining)
// Also return remaining gas to the block gas counter so it is
// available for the next transaction.
st.gp.AddGas(st.gas)
}
// gasUsed returns the amount of gas used up by the state transition.
func (st *StateTransition) gasUsed() uint64 {
return st.initialGas - st.gas
}
// NewEVMBlockContext creates a new context for use in the EVM.
func NewKVMBlockContext(header *types.Header, chain vm.ChainContext, author *common.Address) kvm.BlockContext {
return kvm.BlockContext{
CanTransfer: vm.CanTransfer,
Transfer: vm.Transfer,
GetHash: vm.GetHashFn(header, chain),
Coinbase: *author,
BlockHeight: new(big.Int).SetUint64(header.Height),
Time: new(big.Int).SetInt64(header.Time.Unix()),
GasLimit: header.GasLimit,
}
}
// NewKVMTxContext creates a new transaction context for a single transaction.
func NewKVMTxContext(msg Message) kvm.TxContext {
return kvm.TxContext{
Origin: msg.From(),
GasPrice: new(big.Int).Set(msg.GasPrice()),
}
}