/
state_transition.go
270 lines (223 loc) · 7.68 KB
/
state_transition.go
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package types
import (
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
ethtypes "github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/core/vm"
sdk "github.com/cosmos/cosmos-sdk/types"
sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
)
// StateTransition defines data to transitionDB in evm
type StateTransition struct {
// TxData fields
AccountNonce uint64
Price *big.Int
GasLimit uint64
Recipient *common.Address
Amount *big.Int
Payload []byte
ChainID *big.Int
Csdb *CommitStateDB
TxHash *common.Hash
Sender common.Address
Simulate bool // i.e CheckTx execution
}
// GasInfo returns the gas limit, gas consumed and gas refunded from the EVM transition
// execution
type GasInfo struct {
GasLimit uint64
GasConsumed uint64
GasRefunded uint64
}
// ExecutionResult represents what's returned from a transition
type ExecutionResult struct {
Logs []*ethtypes.Log
Bloom *big.Int
Result *sdk.Result
GasInfo GasInfo
}
// GetHashFn implements vm.GetHashFunc for Ethermint. It handles 3 cases:
// 1. The requested height matches the current height (and thus same epoch number)
// 2. The requested height is from an previous height from the same chain epoch
// 3. The requested height is from a height greater than the latest one
func GetHashFn(ctx sdk.Context, csdb *CommitStateDB) vm.GetHashFunc {
return func(height uint64) common.Hash {
switch {
case ctx.BlockHeight() == int64(height):
// Case 1: The requested height matches the one from the CommitStateDB so we can retrieve the block
// hash directly from the CommitStateDB.
return csdb.bhash
case ctx.BlockHeight() > int64(height):
// Case 2: if the chain is not the current height we need to retrieve the hash from the store for the
// current chain epoch. This only applies if the current height is greater than the requested height.
return csdb.WithContext(ctx).GetHeightHash(height)
default:
// Case 3: heights greater than the current one returns an empty hash.
return common.Hash{}
}
}
}
func (st StateTransition) newEVM(
ctx sdk.Context,
csdb *CommitStateDB,
gasLimit uint64,
gasPrice *big.Int,
config ChainConfig,
extraEIPs []int64,
) *vm.EVM {
// Create contexts for evm
blockCtx := vm.BlockContext{
CanTransfer: core.CanTransfer,
Transfer: core.Transfer,
GetHash: GetHashFn(ctx, csdb),
Coinbase: common.Address{}, // there's no beneficiary since we're not mining
BlockNumber: big.NewInt(ctx.BlockHeight()),
Time: big.NewInt(ctx.BlockHeader().Time.Unix()),
Difficulty: big.NewInt(0), // unused. Only required in PoW context
GasLimit: gasLimit,
}
txCtx := vm.TxContext{
Origin: st.Sender,
GasPrice: gasPrice,
}
eips := make([]int, len(extraEIPs))
for i, eip := range extraEIPs {
eips[i] = int(eip)
}
vmConfig := vm.Config{
ExtraEips: eips,
}
return vm.NewEVM(blockCtx, txCtx, csdb, config.EthereumConfig(st.ChainID), vmConfig)
}
// TransitionDb will transition the state by applying the current transaction and
// returning the evm execution result.
// NOTE: State transition checks are run during AnteHandler execution.
func (st StateTransition) TransitionDb(ctx sdk.Context, config ChainConfig) (*ExecutionResult, error) {
contractCreation := st.Recipient == nil
cost, err := core.IntrinsicGas(st.Payload, contractCreation, config.IsHomestead(), config.IsIstanbul())
if err != nil {
return nil, sdkerrors.Wrap(err, "invalid intrinsic gas for transaction")
}
// This gas limit the the transaction gas limit with intrinsic gas subtracted
gasLimit := st.GasLimit - ctx.GasMeter().GasConsumed()
csdb := st.Csdb.WithContext(ctx)
if st.Simulate {
// gasLimit is set here because stdTxs incur gaskv charges in the ante handler, but for eth_call
// the cost needs to be the same as an Ethereum transaction sent through the web3 API
consumedGas := ctx.GasMeter().GasConsumed()
gasLimit = st.GasLimit - cost
if consumedGas < cost {
// If Cosmos standard tx ante handler cost is less than EVM intrinsic cost
// gas must be consumed to match to accurately simulate an Ethereum transaction
ctx.GasMeter().ConsumeGas(cost-consumedGas, "Intrinsic gas match")
}
csdb = st.Csdb.Copy()
}
// This gas meter is set up to consume gas from gaskv during evm execution and be ignored
currentGasMeter := ctx.GasMeter()
evmGasMeter := sdk.NewInfiniteGasMeter()
csdb.WithContext(ctx.WithGasMeter(evmGasMeter))
// Clear cache of accounts to handle changes outside of the EVM
csdb.UpdateAccounts()
params := csdb.GetParams()
gasPrice := ctx.MinGasPrices().AmountOf(params.EvmDenom)
if gasPrice.IsNil() {
return nil, errors.New("gas price cannot be nil")
}
evm := st.newEVM(ctx, csdb, gasLimit, gasPrice.Int, config, params.ExtraEIPs)
var (
ret []byte
leftOverGas uint64
contractAddress common.Address
recipientLog string
senderRef = vm.AccountRef(st.Sender)
)
// Get nonce of account outside of the EVM
currentNonce := csdb.GetNonce(st.Sender)
// Set nonce of sender account before evm state transition for usage in generating Create address
csdb.SetNonce(st.Sender, st.AccountNonce)
// create contract or execute call
switch contractCreation {
case true:
if !params.EnableCreate {
return nil, ErrCreateDisabled
}
ret, contractAddress, leftOverGas, err = evm.Create(senderRef, st.Payload, gasLimit, st.Amount)
recipientLog = fmt.Sprintf("contract address %s", contractAddress.String())
default:
if !params.EnableCall {
return nil, ErrCallDisabled
}
// Increment the nonce for the next transaction (just for evm state transition)
csdb.SetNonce(st.Sender, csdb.GetNonce(st.Sender)+1)
ret, leftOverGas, err = evm.Call(senderRef, *st.Recipient, st.Payload, gasLimit, st.Amount)
recipientLog = fmt.Sprintf("recipient address %s", st.Recipient.String())
}
gasConsumed := gasLimit - leftOverGas
if err != nil {
// Consume gas before returning
ctx.GasMeter().ConsumeGas(gasConsumed, "evm execution consumption")
return nil, err
}
// Resets nonce to value pre state transition
csdb.SetNonce(st.Sender, currentNonce)
// Generate bloom filter to be saved in tx receipt data
bloomInt := big.NewInt(0)
var (
bloomFilter ethtypes.Bloom
logs []*ethtypes.Log
)
if st.TxHash != nil && !st.Simulate {
logs, err = csdb.GetLogs(*st.TxHash)
if err != nil {
return nil, err
}
bloomInt = big.NewInt(0).SetBytes(ethtypes.LogsBloom(logs))
bloomFilter = ethtypes.BytesToBloom(bloomInt.Bytes())
}
if !st.Simulate {
// Finalise state if not a simulated transaction
// TODO: change to depend on config
if err := csdb.Finalise(true); err != nil {
return nil, err
}
}
// Encode all necessary data into slice of bytes to return in sdk result
resultData := ResultData{
Bloom: bloomFilter,
Logs: logs,
Ret: ret,
TxHash: *st.TxHash,
}
if contractCreation {
resultData.ContractAddress = contractAddress
}
resBz, err := EncodeResultData(resultData)
if err != nil {
return nil, err
}
resultLog := fmt.Sprintf(
"executed EVM state transition; sender address %s; %s", st.Sender.String(), recipientLog,
)
executionResult := &ExecutionResult{
Logs: logs,
Bloom: bloomInt,
Result: &sdk.Result{
Data: resBz,
Log: resultLog,
},
GasInfo: GasInfo{
GasConsumed: gasConsumed,
GasLimit: gasLimit,
GasRefunded: leftOverGas,
},
}
// TODO: Refund unused gas here, if intended in future
// Consume gas from evm execution
// Out of gas check does not need to be done here since it is done within the EVM execution
ctx.WithGasMeter(currentGasMeter).GasMeter().ConsumeGas(gasConsumed, "EVM execution consumption")
return executionResult, nil
}