go-ethereum/internal/ethapi/simulate.go

419 lines
14 KiB
Go

// Copyright 2023 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 ethapi
import (
"context"
"encoding/json"
"errors"
"fmt"
"maps"
"math/big"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
"github.com/ethereum/go-ethereum/consensus/misc/eip4844"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rpc"
"github.com/ethereum/go-ethereum/trie"
)
const (
// maxSimulateBlocks is the maximum number of blocks that can be simulated
// in a single request.
maxSimulateBlocks = 256
// timestampIncrement is the default increment between block timestamps.
timestampIncrement = 1
)
// simBlock is a batch of calls to be simulated sequentially.
type simBlock struct {
BlockOverrides *BlockOverrides
StateOverrides *StateOverride
Calls []TransactionArgs
}
// simCallResult is the result of a simulated call.
type simCallResult struct {
ReturnValue hexutil.Bytes `json:"returnData"`
Logs []*types.Log `json:"logs"`
GasUsed hexutil.Uint64 `json:"gasUsed"`
Status hexutil.Uint64 `json:"status"`
Error *callError `json:"error,omitempty"`
}
func (r *simCallResult) MarshalJSON() ([]byte, error) {
type callResultAlias simCallResult
// Marshal logs to be an empty array instead of nil when empty
if r.Logs == nil {
r.Logs = []*types.Log{}
}
return json.Marshal((*callResultAlias)(r))
}
// simOpts are the inputs to eth_simulateV1.
type simOpts struct {
BlockStateCalls []simBlock
TraceTransfers bool
Validation bool
ReturnFullTransactions bool
}
// simulator is a stateful object that simulates a series of blocks.
// it is not safe for concurrent use.
type simulator struct {
b Backend
state *state.StateDB
base *types.Header
chainConfig *params.ChainConfig
gp *core.GasPool
traceTransfers bool
validate bool
fullTx bool
}
// execute runs the simulation of a series of blocks.
func (sim *simulator) execute(ctx context.Context, blocks []simBlock) ([]map[string]interface{}, error) {
if err := ctx.Err(); err != nil {
return nil, err
}
var (
cancel context.CancelFunc
timeout = sim.b.RPCEVMTimeout()
)
if timeout > 0 {
ctx, cancel = context.WithTimeout(ctx, timeout)
} else {
ctx, cancel = context.WithCancel(ctx)
}
// Make sure the context is cancelled when the call has completed
// this makes sure resources are cleaned up.
defer cancel()
var err error
blocks, err = sim.sanitizeChain(blocks)
if err != nil {
return nil, err
}
// Prepare block headers with preliminary fields for the response.
headers, err := sim.makeHeaders(blocks)
if err != nil {
return nil, err
}
var (
results = make([]map[string]interface{}, len(blocks))
parent = sim.base
)
for bi, block := range blocks {
result, callResults, err := sim.processBlock(ctx, &block, headers[bi], parent, headers[:bi], timeout)
if err != nil {
return nil, err
}
enc := RPCMarshalBlock(result, true, sim.fullTx, sim.chainConfig)
enc["calls"] = callResults
results[bi] = enc
parent = headers[bi]
}
return results, nil
}
func (sim *simulator) processBlock(ctx context.Context, block *simBlock, header, parent *types.Header, headers []*types.Header, timeout time.Duration) (*types.Block, []simCallResult, error) {
// Set header fields that depend only on parent block.
// Parent hash is needed for evm.GetHashFn to work.
header.ParentHash = parent.Hash()
if sim.chainConfig.IsLondon(header.Number) {
// In non-validation mode base fee is set to 0 if it is not overridden.
// This is because it creates an edge case in EVM where gasPrice < baseFee.
// Base fee could have been overridden.
if header.BaseFee == nil {
if sim.validate {
header.BaseFee = eip1559.CalcBaseFee(sim.chainConfig, parent)
} else {
header.BaseFee = big.NewInt(0)
}
}
}
if sim.chainConfig.IsCancun(header.Number, header.Time) {
var excess uint64
if sim.chainConfig.IsCancun(parent.Number, parent.Time) {
excess = eip4844.CalcExcessBlobGas(*parent.ExcessBlobGas, *parent.BlobGasUsed)
} else {
excess = eip4844.CalcExcessBlobGas(0, 0)
}
header.ExcessBlobGas = &excess
}
blockContext := core.NewEVMBlockContext(header, sim.newSimulatedChainContext(ctx, headers), nil)
if block.BlockOverrides.BlobBaseFee != nil {
blockContext.BlobBaseFee = block.BlockOverrides.BlobBaseFee.ToInt()
}
precompiles := sim.activePrecompiles(sim.base)
// State overrides are applied prior to execution of a block
if err := block.StateOverrides.Apply(sim.state, precompiles); err != nil {
return nil, nil, err
}
var (
gasUsed, blobGasUsed uint64
txes = make([]*types.Transaction, len(block.Calls))
callResults = make([]simCallResult, len(block.Calls))
receipts = make([]*types.Receipt, len(block.Calls))
// Block hash will be repaired after execution.
tracer = newTracer(sim.traceTransfers, blockContext.BlockNumber.Uint64(), common.Hash{}, common.Hash{}, 0)
vmConfig = &vm.Config{
NoBaseFee: !sim.validate,
Tracer: tracer.Hooks(),
}
)
var tracingStateDB = vm.StateDB(sim.state)
if hooks := tracer.Hooks(); hooks != nil {
tracingStateDB = state.NewHookedState(sim.state, hooks)
}
evm := vm.NewEVM(blockContext, tracingStateDB, sim.chainConfig, *vmConfig)
// It is possible to override precompiles with EVM bytecode, or
// move them to another address.
if precompiles != nil {
evm.SetPrecompiles(precompiles)
}
for i, call := range block.Calls {
if err := ctx.Err(); err != nil {
return nil, nil, err
}
if err := sim.sanitizeCall(&call, sim.state, header, blockContext, &gasUsed); err != nil {
return nil, nil, err
}
tx := call.ToTransaction(types.DynamicFeeTxType)
txes[i] = tx
tracer.reset(tx.Hash(), uint(i))
// EoA check is always skipped, even in validation mode.
msg := call.ToMessage(header.BaseFee, !sim.validate, true)
evm.SetTxContext(core.NewEVMTxContext(msg))
result, err := applyMessageWithEVM(ctx, evm, msg, timeout, sim.gp)
if err != nil {
txErr := txValidationError(err)
return nil, nil, txErr
}
// Update the state with pending changes.
var root []byte
if sim.chainConfig.IsByzantium(blockContext.BlockNumber) {
tracingStateDB.Finalise(true)
} else {
root = sim.state.IntermediateRoot(sim.chainConfig.IsEIP158(blockContext.BlockNumber)).Bytes()
}
gasUsed += result.UsedGas
receipts[i] = core.MakeReceipt(evm, result, sim.state, blockContext.BlockNumber, common.Hash{}, tx, gasUsed, root)
blobGasUsed += receipts[i].BlobGasUsed
logs := tracer.Logs()
callRes := simCallResult{ReturnValue: result.Return(), Logs: logs, GasUsed: hexutil.Uint64(result.UsedGas)}
if result.Failed() {
callRes.Status = hexutil.Uint64(types.ReceiptStatusFailed)
if errors.Is(result.Err, vm.ErrExecutionReverted) {
// If the result contains a revert reason, try to unpack it.
revertErr := newRevertError(result.Revert())
callRes.Error = &callError{Message: revertErr.Error(), Code: errCodeReverted, Data: revertErr.ErrorData().(string)}
} else {
callRes.Error = &callError{Message: result.Err.Error(), Code: errCodeVMError}
}
} else {
callRes.Status = hexutil.Uint64(types.ReceiptStatusSuccessful)
}
callResults[i] = callRes
}
header.Root = sim.state.IntermediateRoot(true)
header.GasUsed = gasUsed
if sim.chainConfig.IsCancun(header.Number, header.Time) {
header.BlobGasUsed = &blobGasUsed
}
var withdrawals types.Withdrawals
if sim.chainConfig.IsShanghai(header.Number, header.Time) {
withdrawals = make([]*types.Withdrawal, 0)
}
b := types.NewBlock(header, &types.Body{Transactions: txes, Withdrawals: withdrawals}, receipts, trie.NewStackTrie(nil))
repairLogs(callResults, b.Hash())
return b, callResults, nil
}
// repairLogs updates the block hash in the logs present in the result of
// a simulated block. This is needed as during execution when logs are collected
// the block hash is not known.
func repairLogs(calls []simCallResult, hash common.Hash) {
for i := range calls {
for j := range calls[i].Logs {
calls[i].Logs[j].BlockHash = hash
}
}
}
func (sim *simulator) sanitizeCall(call *TransactionArgs, state vm.StateDB, header *types.Header, blockContext vm.BlockContext, gasUsed *uint64) error {
if call.Nonce == nil {
nonce := state.GetNonce(call.from())
call.Nonce = (*hexutil.Uint64)(&nonce)
}
// Let the call run wild unless explicitly specified.
if call.Gas == nil {
remaining := blockContext.GasLimit - *gasUsed
call.Gas = (*hexutil.Uint64)(&remaining)
}
if *gasUsed+uint64(*call.Gas) > blockContext.GasLimit {
return &blockGasLimitReachedError{fmt.Sprintf("block gas limit reached: %d >= %d", gasUsed, blockContext.GasLimit)}
}
if err := call.CallDefaults(sim.gp.Gas(), header.BaseFee, sim.chainConfig.ChainID); err != nil {
return err
}
return nil
}
func (sim *simulator) activePrecompiles(base *types.Header) vm.PrecompiledContracts {
var (
isMerge = (base.Difficulty.Sign() == 0)
rules = sim.chainConfig.Rules(base.Number, isMerge, base.Time)
)
return maps.Clone(vm.ActivePrecompiledContracts(rules))
}
// sanitizeChain checks the chain integrity. Specifically it checks that
// block numbers and timestamp are strictly increasing, setting default values
// when necessary. Gaps in block numbers are filled with empty blocks.
// Note: It modifies the block's override object.
func (sim *simulator) sanitizeChain(blocks []simBlock) ([]simBlock, error) {
var (
res = make([]simBlock, 0, len(blocks))
base = sim.base
prevNumber = base.Number
prevTimestamp = base.Time
)
for _, block := range blocks {
if block.BlockOverrides == nil {
block.BlockOverrides = new(BlockOverrides)
}
if block.BlockOverrides.Number == nil {
n := new(big.Int).Add(prevNumber, big.NewInt(1))
block.BlockOverrides.Number = (*hexutil.Big)(n)
}
diff := new(big.Int).Sub(block.BlockOverrides.Number.ToInt(), prevNumber)
if diff.Cmp(common.Big0) <= 0 {
return nil, &invalidBlockNumberError{fmt.Sprintf("block numbers must be in order: %d <= %d", block.BlockOverrides.Number.ToInt().Uint64(), prevNumber)}
}
if total := new(big.Int).Sub(block.BlockOverrides.Number.ToInt(), base.Number); total.Cmp(big.NewInt(maxSimulateBlocks)) > 0 {
return nil, &clientLimitExceededError{message: "too many blocks"}
}
if diff.Cmp(big.NewInt(1)) > 0 {
// Fill the gap with empty blocks.
gap := new(big.Int).Sub(diff, big.NewInt(1))
// Assign block number to the empty blocks.
for i := uint64(0); i < gap.Uint64(); i++ {
n := new(big.Int).Add(prevNumber, big.NewInt(int64(i+1)))
t := prevTimestamp + timestampIncrement
b := simBlock{BlockOverrides: &BlockOverrides{Number: (*hexutil.Big)(n), Time: (*hexutil.Uint64)(&t)}}
prevTimestamp = t
res = append(res, b)
}
}
// Only append block after filling a potential gap.
prevNumber = block.BlockOverrides.Number.ToInt()
var t uint64
if block.BlockOverrides.Time == nil {
t = prevTimestamp + timestampIncrement
block.BlockOverrides.Time = (*hexutil.Uint64)(&t)
} else {
t = uint64(*block.BlockOverrides.Time)
if t <= prevTimestamp {
return nil, &invalidBlockTimestampError{fmt.Sprintf("block timestamps must be in order: %d <= %d", t, prevTimestamp)}
}
}
prevTimestamp = t
res = append(res, block)
}
return res, nil
}
// makeHeaders makes header object with preliminary fields based on a simulated block.
// Some fields have to be filled post-execution.
// It assumes blocks are in order and numbers have been validated.
func (sim *simulator) makeHeaders(blocks []simBlock) ([]*types.Header, error) {
var (
res = make([]*types.Header, len(blocks))
base = sim.base
header = base
)
for bi, block := range blocks {
if block.BlockOverrides == nil || block.BlockOverrides.Number == nil {
return nil, errors.New("empty block number")
}
overrides := block.BlockOverrides
var withdrawalsHash *common.Hash
if sim.chainConfig.IsShanghai(overrides.Number.ToInt(), (uint64)(*overrides.Time)) {
withdrawalsHash = &types.EmptyWithdrawalsHash
}
var parentBeaconRoot *common.Hash
if sim.chainConfig.IsCancun(overrides.Number.ToInt(), (uint64)(*overrides.Time)) {
parentBeaconRoot = &common.Hash{}
}
header = overrides.MakeHeader(&types.Header{
UncleHash: types.EmptyUncleHash,
ReceiptHash: types.EmptyReceiptsHash,
TxHash: types.EmptyTxsHash,
Coinbase: header.Coinbase,
Difficulty: header.Difficulty,
GasLimit: header.GasLimit,
WithdrawalsHash: withdrawalsHash,
ParentBeaconRoot: parentBeaconRoot,
})
res[bi] = header
}
return res, nil
}
func (sim *simulator) newSimulatedChainContext(ctx context.Context, headers []*types.Header) *ChainContext {
return NewChainContext(ctx, &simBackend{base: sim.base, b: sim.b, headers: headers})
}
type simBackend struct {
b ChainContextBackend
base *types.Header
headers []*types.Header
}
func (b *simBackend) Engine() consensus.Engine {
return b.b.Engine()
}
func (b *simBackend) HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error) {
if uint64(number) == b.base.Number.Uint64() {
return b.base, nil
}
if uint64(number) < b.base.Number.Uint64() {
// Resolve canonical header.
return b.b.HeaderByNumber(ctx, number)
}
// Simulated block.
for _, header := range b.headers {
if header.Number.Uint64() == uint64(number) {
return header, nil
}
}
return nil, errors.New("header not found")
}