300 lines
9.0 KiB
Go
300 lines
9.0 KiB
Go
// Copyright 2022 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package native
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import (
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"bytes"
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"encoding/json"
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"math/big"
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"sync/atomic"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/hexutil"
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"github.com/ethereum/go-ethereum/core/vm"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/eth/tracers"
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"github.com/ethereum/go-ethereum/log"
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)
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//go:generate go run github.com/fjl/gencodec -type account -field-override accountMarshaling -out gen_account_json.go
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func init() {
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tracers.DefaultDirectory.Register("prestateTracer", newPrestateTracer, false)
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}
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type state = map[common.Address]*account
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type account struct {
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Balance *big.Int `json:"balance,omitempty"`
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Code []byte `json:"code,omitempty"`
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Nonce uint64 `json:"nonce,omitempty"`
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Storage map[common.Hash]common.Hash `json:"storage,omitempty"`
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}
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func (a *account) exists() bool {
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return a.Nonce > 0 || len(a.Code) > 0 || len(a.Storage) > 0 || (a.Balance != nil && a.Balance.Sign() != 0)
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}
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type accountMarshaling struct {
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Balance *hexutil.Big
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Code hexutil.Bytes
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}
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type prestateTracer struct {
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noopTracer
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env *vm.EVM
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pre state
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post state
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create bool
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to common.Address
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gasLimit uint64 // Amount of gas bought for the whole tx
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config prestateTracerConfig
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interrupt atomic.Bool // Atomic flag to signal execution interruption
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reason error // Textual reason for the interruption
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created map[common.Address]bool
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deleted map[common.Address]bool
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}
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type prestateTracerConfig struct {
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DiffMode bool `json:"diffMode"` // If true, this tracer will return state modifications
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}
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func newPrestateTracer(ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
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var config prestateTracerConfig
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if cfg != nil {
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if err := json.Unmarshal(cfg, &config); err != nil {
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return nil, err
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}
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}
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return &prestateTracer{
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pre: state{},
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post: state{},
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config: config,
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created: make(map[common.Address]bool),
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deleted: make(map[common.Address]bool),
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}, nil
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}
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// CaptureStart implements the EVMLogger interface to initialize the tracing operation.
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func (t *prestateTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
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t.env = env
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t.create = create
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t.to = to
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t.lookupAccount(from)
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t.lookupAccount(to)
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t.lookupAccount(env.Context.Coinbase)
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// The recipient balance includes the value transferred.
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toBal := new(big.Int).Sub(t.pre[to].Balance, value)
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t.pre[to].Balance = toBal
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// The sender balance is after reducing: value and gasLimit.
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// We need to re-add them to get the pre-tx balance.
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fromBal := new(big.Int).Set(t.pre[from].Balance)
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gasPrice := env.TxContext.GasPrice
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consumedGas := new(big.Int).Mul(gasPrice, new(big.Int).SetUint64(t.gasLimit))
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fromBal.Add(fromBal, new(big.Int).Add(value, consumedGas))
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t.pre[from].Balance = fromBal
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t.pre[from].Nonce--
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if create && t.config.DiffMode {
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t.created[to] = true
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}
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}
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// CaptureEnd is called after the call finishes to finalize the tracing.
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func (t *prestateTracer) CaptureEnd(output []byte, gasUsed uint64, err error) {
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if t.config.DiffMode {
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return
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}
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if t.create {
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// Keep existing account prior to contract creation at that address
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if s := t.pre[t.to]; s != nil && !s.exists() {
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// Exclude newly created contract.
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delete(t.pre, t.to)
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}
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}
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}
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// CaptureState implements the EVMLogger interface to trace a single step of VM execution.
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func (t *prestateTracer) CaptureState(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
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if err != nil {
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return
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}
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// Skip if tracing was interrupted
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if t.interrupt.Load() {
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return
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}
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stack := scope.Stack
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stackData := stack.Data()
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stackLen := len(stackData)
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caller := scope.Contract.Address()
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switch {
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case stackLen >= 1 && (op == vm.SLOAD || op == vm.SSTORE):
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slot := common.Hash(stackData[stackLen-1].Bytes32())
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t.lookupStorage(caller, slot)
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case stackLen >= 1 && (op == vm.EXTCODECOPY || op == vm.EXTCODEHASH || op == vm.EXTCODESIZE || op == vm.BALANCE || op == vm.SELFDESTRUCT):
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addr := common.Address(stackData[stackLen-1].Bytes20())
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t.lookupAccount(addr)
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if op == vm.SELFDESTRUCT {
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t.deleted[caller] = true
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}
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case stackLen >= 5 && (op == vm.DELEGATECALL || op == vm.CALL || op == vm.STATICCALL || op == vm.CALLCODE):
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addr := common.Address(stackData[stackLen-2].Bytes20())
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t.lookupAccount(addr)
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case op == vm.CREATE:
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nonce := t.env.StateDB.GetNonce(caller)
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addr := crypto.CreateAddress(caller, nonce)
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t.lookupAccount(addr)
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t.created[addr] = true
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case stackLen >= 4 && op == vm.CREATE2:
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offset := stackData[stackLen-2]
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size := stackData[stackLen-3]
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init, err := tracers.GetMemoryCopyPadded(scope.Memory, int64(offset.Uint64()), int64(size.Uint64()))
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if err != nil {
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log.Warn("failed to copy CREATE2 input", "err", err, "tracer", "prestateTracer", "offset", offset, "size", size)
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return
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}
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inithash := crypto.Keccak256(init)
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salt := stackData[stackLen-4]
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addr := crypto.CreateAddress2(caller, salt.Bytes32(), inithash)
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t.lookupAccount(addr)
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t.created[addr] = true
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}
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}
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func (t *prestateTracer) CaptureTxStart(gasLimit uint64) {
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t.gasLimit = gasLimit
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}
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func (t *prestateTracer) CaptureTxEnd(restGas uint64) {
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if !t.config.DiffMode {
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return
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}
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for addr, state := range t.pre {
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// The deleted account's state is pruned from `post` but kept in `pre`
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if _, ok := t.deleted[addr]; ok {
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continue
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}
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modified := false
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postAccount := &account{Storage: make(map[common.Hash]common.Hash)}
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newBalance := t.env.StateDB.GetBalance(addr)
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newNonce := t.env.StateDB.GetNonce(addr)
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newCode := t.env.StateDB.GetCode(addr)
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if newBalance.Cmp(t.pre[addr].Balance) != 0 {
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modified = true
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postAccount.Balance = newBalance
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}
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if newNonce != t.pre[addr].Nonce {
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modified = true
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postAccount.Nonce = newNonce
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}
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if !bytes.Equal(newCode, t.pre[addr].Code) {
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modified = true
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postAccount.Code = newCode
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}
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for key, val := range state.Storage {
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// don't include the empty slot
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if val == (common.Hash{}) {
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delete(t.pre[addr].Storage, key)
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}
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newVal := t.env.StateDB.GetState(addr, key)
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if val == newVal {
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// Omit unchanged slots
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delete(t.pre[addr].Storage, key)
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} else {
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modified = true
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if newVal != (common.Hash{}) {
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postAccount.Storage[key] = newVal
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}
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}
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}
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if modified {
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t.post[addr] = postAccount
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} else {
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// if state is not modified, then no need to include into the pre state
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delete(t.pre, addr)
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}
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}
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// the new created contracts' prestate were empty, so delete them
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for a := range t.created {
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// the created contract maybe exists in statedb before the creating tx
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if s := t.pre[a]; s != nil && !s.exists() {
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delete(t.pre, a)
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}
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}
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}
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func (t *prestateTracer) CaptureSystemTxEnd(intrinsicGas uint64) {}
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// GetResult returns the json-encoded nested list of call traces, and any
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// error arising from the encoding or forceful termination (via `Stop`).
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func (t *prestateTracer) GetResult() (json.RawMessage, error) {
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var res []byte
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var err error
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if t.config.DiffMode {
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res, err = json.Marshal(struct {
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Post state `json:"post"`
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Pre state `json:"pre"`
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}{t.post, t.pre})
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} else {
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res, err = json.Marshal(t.pre)
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}
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if err != nil {
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return nil, err
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}
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return json.RawMessage(res), t.reason
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}
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// Stop terminates execution of the tracer at the first opportune moment.
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func (t *prestateTracer) Stop(err error) {
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t.reason = err
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t.interrupt.Store(true)
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}
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// lookupAccount fetches details of an account and adds it to the prestate
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// if it doesn't exist there.
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func (t *prestateTracer) lookupAccount(addr common.Address) {
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if _, ok := t.pre[addr]; ok {
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return
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}
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t.pre[addr] = &account{
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Balance: t.env.StateDB.GetBalance(addr),
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Nonce: t.env.StateDB.GetNonce(addr),
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Code: t.env.StateDB.GetCode(addr),
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Storage: make(map[common.Hash]common.Hash),
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}
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}
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// lookupStorage fetches the requested storage slot and adds
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// it to the prestate of the given contract. It assumes `lookupAccount`
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// has been performed on the contract before.
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func (t *prestateTracer) lookupStorage(addr common.Address, key common.Hash) {
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if _, ok := t.pre[addr].Storage[key]; ok {
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return
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}
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t.pre[addr].Storage[key] = t.env.StateDB.GetState(addr, key)
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}
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