core, eth, internal/ethapi: create access list RPC API (#22550)

* core/vm: implement AccessListTracer

* eth: implement debug.createAccessList

* core/vm: fixed nil panics in accessListTracer

* eth: better error messages for createAccessList

* eth: some fixes on CreateAccessList

* eth: allow for provided accesslists

* eth: pass accesslist by value

* eth: remove created acocunt from accesslist

* core/vm: simplify access list tracer

* core/vm: unexport accessListTracer

* eth: return best guess if al iteration times out

* eth: return best guess if al iteration times out

* core: docstring, unexport methods

* eth: typo

* internal/ethapi: move createAccessList to eth package

* internal/ethapi: remove reexec from createAccessList

* internal/ethapi: break if al is equal to last run, not if gas is equal

* internal/web3ext: fixed arguments

* core/types: fixed equality check for accesslist

* core/types: no hardcoded vals

* core, internal: simplify access list generation, make it precise

* core/vm: fix typo

Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Péter Szilágyi <peterke@gmail.com>

core/state_transition.go

@@ -259,10 +259,9 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 	}
 
 	// Set up the initial access list.
-	if st.evm.ChainConfig().IsBerlin(st.evm.Context.BlockNumber) {
-		st.state.PrepareAccessList(msg.From(), msg.To(), st.evm.ActivePrecompiles(), msg.AccessList())
+	if rules := st.evm.ChainConfig().Rules(st.evm.Context.BlockNumber); rules.IsBerlin {
+		st.state.PrepareAccessList(msg.From(), msg.To(), vm.ActivePrecompiles(rules), msg.AccessList())
 	}
-
 	var (
 		ret   []byte
 		vmerr error // vm errors do not effect consensus and are therefore not assigned to err

core/vm/access_list_tracer.go

@@ -0,0 +1,177 @@
+// Copyright 2021 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 vm
+
+import (
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+// accessList is an accumulator for the set of accounts and storage slots an EVM
+// contract execution touches.
+type accessList map[common.Address]accessListSlots
+
+// accessListSlots is an accumulator for the set of storage slots within a single
+// contract that an EVM contract execution touches.
+type accessListSlots map[common.Hash]struct{}
+
+// newAccessList creates a new accessList.
+func newAccessList() accessList {
+	return make(map[common.Address]accessListSlots)
+}
+
+// addAddress adds an address to the accesslist.
+func (al accessList) addAddress(address common.Address) {
+	// Set address if not previously present
+	if _, present := al[address]; !present {
+		al[address] = make(map[common.Hash]struct{})
+	}
+}
+
+// addSlot adds a storage slot to the accesslist.
+func (al accessList) addSlot(address common.Address, slot common.Hash) {
+	// Set address if not previously present
+	al.addAddress(address)
+
+	// Set the slot on the surely existent storage set
+	al[address][slot] = struct{}{}
+}
+
+// equal checks if the content of the current access list is the same as the
+// content of the other one.
+func (al accessList) equal(other accessList) bool {
+	// Cross reference the accounts first
+	if len(al) != len(other) {
+		return false
+	}
+	for addr := range al {
+		if _, ok := other[addr]; !ok {
+			return false
+		}
+	}
+	for addr := range other {
+		if _, ok := al[addr]; !ok {
+			return false
+		}
+	}
+	// Accounts match, cross reference the storage slots too
+	for addr, slots := range al {
+		otherslots := other[addr]
+
+		if len(slots) != len(otherslots) {
+			return false
+		}
+		for hash := range slots {
+			if _, ok := otherslots[hash]; !ok {
+				return false
+			}
+		}
+		for hash := range otherslots {
+			if _, ok := slots[hash]; !ok {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// accesslist converts the accesslist to a types.AccessList.
+func (al accessList) accessList() types.AccessList {
+	acl := make(types.AccessList, 0, len(al))
+	for addr, slots := range al {
+		tuple := types.AccessTuple{Address: addr}
+		for slot := range slots {
+			tuple.StorageKeys = append(tuple.StorageKeys, slot)
+		}
+		acl = append(acl, tuple)
+	}
+	return acl
+}
+
+// AccessListTracer is a tracer that accumulates touched accounts and storage
+// slots into an internal set.
+type AccessListTracer struct {
+	excl map[common.Address]struct{} // Set of account to exclude from the list
+	list accessList                  // Set of accounts and storage slots touched
+}
+
+// NewAccessListTracer creates a new tracer that can generate AccessLists.
+// An optional AccessList can be specified to occupy slots and addresses in
+// the resulting accesslist.
+func NewAccessListTracer(acl types.AccessList, from, to common.Address, precompiles []common.Address) *AccessListTracer {
+	excl := map[common.Address]struct{}{
+		from: {}, to: {},
+	}
+	for _, addr := range precompiles {
+		excl[addr] = struct{}{}
+	}
+	list := newAccessList()
+	for _, al := range acl {
+		if _, ok := excl[al.Address]; !ok {
+			list.addAddress(al.Address)
+		}
+		for _, slot := range al.StorageKeys {
+			list.addSlot(al.Address, slot)
+		}
+	}
+	return &AccessListTracer{
+		excl: excl,
+		list: list,
+	}
+}
+
+func (a *AccessListTracer) CaptureStart(env *EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
+}
+
+// CaptureState captures all opcodes that touch storage or addresses and adds them to the accesslist.
+func (a *AccessListTracer) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, scope *ScopeContext, rData []byte, depth int, err error) {
+	stack := scope.Stack
+	if (op == SLOAD || op == SSTORE) && stack.len() >= 1 {
+		slot := common.Hash(stack.data[stack.len()-1].Bytes32())
+		a.list.addSlot(scope.Contract.Address(), slot)
+	}
+	if (op == EXTCODECOPY || op == EXTCODEHASH || op == EXTCODESIZE || op == BALANCE || op == SELFDESTRUCT) && stack.len() >= 1 {
+		addr := common.Address(stack.data[stack.len()-1].Bytes20())
+		if _, ok := a.excl[addr]; !ok {
+			a.list.addAddress(addr)
+		}
+	}
+	if (op == DELEGATECALL || op == CALL || op == STATICCALL || op == CALLCODE) && stack.len() >= 5 {
+		addr := common.Address(stack.data[stack.len()-2].Bytes20())
+		if _, ok := a.excl[addr]; !ok {
+			a.list.addAddress(addr)
+		}
+	}
+}
+
+func (*AccessListTracer) CaptureFault(env *EVM, pc uint64, op OpCode, gas, cost uint64, scope *ScopeContext, depth int, err error) {
+}
+
+func (*AccessListTracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) {}
+
+// AccessList returns the current accesslist maintained by the tracer.
+func (a *AccessListTracer) AccessList() types.AccessList {
+	return a.list.accessList()
+}
+
+// Equal returns if the content of two access list traces are equal.
+func (a *AccessListTracer) Equal(other *AccessListTracer) bool {
+	return a.list.equal(other.list)
+}

core/vm/contracts.go

@@ -128,6 +128,20 @@ func init() {
 	}
 }
 
+// ActivePrecompiles returns the precompiles enabled with the current configuration.
+func ActivePrecompiles(rules params.Rules) []common.Address {
+	switch {
+	case rules.IsBerlin:
+		return PrecompiledAddressesBerlin
+	case rules.IsIstanbul:
+		return PrecompiledAddressesIstanbul
+	case rules.IsByzantium:
+		return PrecompiledAddressesByzantium
+	default:
+		return PrecompiledAddressesHomestead
+	}
+}
+
 // RunPrecompiledContract runs and evaluates the output of a precompiled contract.
 // It returns
 // - the returned bytes,

core/vm/evm.go

@@ -42,21 +42,6 @@ type (
 	GetHashFunc func(uint64) common.Hash
 )
 
-// ActivePrecompiles returns the addresses of the precompiles enabled with the current
-// configuration
-func (evm *EVM) ActivePrecompiles() []common.Address {
-	switch {
-	case evm.chainRules.IsBerlin:
-		return PrecompiledAddressesBerlin
-	case evm.chainRules.IsIstanbul:
-		return PrecompiledAddressesIstanbul
-	case evm.chainRules.IsByzantium:
-		return PrecompiledAddressesByzantium
-	default:
-		return PrecompiledAddressesHomestead
-	}
-}
-
 func (evm *EVM) precompile(addr common.Address) (PrecompiledContract, bool) {
 	var precompiles map[common.Address]PrecompiledContract
 	switch {

core/vm/runtime/runtime.go

@@ -114,8 +114,8 @@ func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
 		vmenv   = NewEnv(cfg)
 		sender  = vm.AccountRef(cfg.Origin)
 	)
-	if cfg.ChainConfig.IsBerlin(vmenv.Context.BlockNumber) {
-		cfg.State.PrepareAccessList(cfg.Origin, &address, vmenv.ActivePrecompiles(), nil)
+	if rules := cfg.ChainConfig.Rules(vmenv.Context.BlockNumber); rules.IsBerlin {
+		cfg.State.PrepareAccessList(cfg.Origin, &address, vm.ActivePrecompiles(rules), nil)
 	}
 	cfg.State.CreateAccount(address)
 	// set the receiver's (the executing contract) code for execution.
@@ -146,10 +146,9 @@ func Create(input []byte, cfg *Config) ([]byte, common.Address, uint64, error) {
 		vmenv  = NewEnv(cfg)
 		sender = vm.AccountRef(cfg.Origin)
 	)
-	if cfg.ChainConfig.IsBerlin(vmenv.Context.BlockNumber) {
-		cfg.State.PrepareAccessList(cfg.Origin, nil, vmenv.ActivePrecompiles(), nil)
+	if rules := cfg.ChainConfig.Rules(vmenv.Context.BlockNumber); rules.IsBerlin {
+		cfg.State.PrepareAccessList(cfg.Origin, nil, vm.ActivePrecompiles(rules), nil)
 	}
-
 	// Call the code with the given configuration.
 	code, address, leftOverGas, err := vmenv.Create(
 		sender,
@@ -172,10 +171,10 @@ func Call(address common.Address, input []byte, cfg *Config) ([]byte, uint64, er
 
 	sender := cfg.State.GetOrNewStateObject(cfg.Origin)
 	statedb := cfg.State
-	if cfg.ChainConfig.IsBerlin(vmenv.Context.BlockNumber) {
-		statedb.PrepareAccessList(cfg.Origin, &address, vmenv.ActivePrecompiles(), nil)
-	}
 
+	if rules := cfg.ChainConfig.Rules(vmenv.Context.BlockNumber); rules.IsBerlin {
+		statedb.PrepareAccessList(cfg.Origin, &address, vm.ActivePrecompiles(rules), nil)
+	}
 	// Call the code with the given configuration.
 	ret, leftOverGas, err := vmenv.Call(
 		sender,
@@ -184,6 +183,5 @@ func Call(address common.Address, input []byte, cfg *Config) ([]byte, uint64, er
 		cfg.GasLimit,
 		cfg.Value,
 	)
-
 	return ret, leftOverGas, err
 }

eth/api_backend.go

@@ -192,12 +192,14 @@ func (b *EthAPIBackend) GetTd(ctx context.Context, hash common.Hash) *big.Int {
 	return b.eth.blockchain.GetTdByHash(hash)
 }
 
-func (b *EthAPIBackend) GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header) (*vm.EVM, func() error, error) {
+func (b *EthAPIBackend) GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header, vmConfig *vm.Config) (*vm.EVM, func() error, error) {
 	vmError := func() error { return nil }
-
+	if vmConfig == nil {
+		vmConfig = b.eth.blockchain.GetVMConfig()
+	}
 	txContext := core.NewEVMTxContext(msg)
 	context := core.NewEVMBlockContext(header, b.eth.BlockChain(), nil)
-	return vm.NewEVM(context, txContext, state, b.eth.blockchain.Config(), *b.eth.blockchain.GetVMConfig()), vmError, nil
+	return vm.NewEVM(context, txContext, state, b.eth.blockchain.Config(), *vmConfig), vmError, nil
 }
 
 func (b *EthAPIBackend) SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription {

internal/ethapi/api.go

@@ -865,7 +865,7 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 
 	// Get a new instance of the EVM.
 	msg := args.ToMessage(globalGasCap)
-	evm, vmError, err := b.GetEVM(ctx, msg, state, header)
+	evm, vmError, err := b.GetEVM(ctx, msg, state, header, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -1303,6 +1303,106 @@ func newRPCTransactionFromBlockHash(b *types.Block, hash common.Hash) *RPCTransa
 	return nil
 }
 
+// accessListResult returns an optional accesslist
+// Its the result of the `debug_createAccessList` RPC call.
+// It contains an error if the transaction itself failed.
+type accessListResult struct {
+	Accesslist *types.AccessList `json:"accessList"`
+	Error      string            `json:"error,omitempty"`
+	GasUsed    hexutil.Uint64    `json:"gasUsed"`
+}
+
+// CreateAccessList creates a EIP-2930 type AccessList for the given transaction.
+// Reexec and BlockNrOrHash can be specified to create the accessList on top of a certain state.
+func (s *PublicBlockChainAPI) CreateAccessList(ctx context.Context, args SendTxArgs, blockNrOrHash *rpc.BlockNumberOrHash) (*accessListResult, error) {
+	bNrOrHash := rpc.BlockNumberOrHashWithNumber(rpc.PendingBlockNumber)
+	if blockNrOrHash != nil {
+		bNrOrHash = *blockNrOrHash
+	}
+	acl, gasUsed, vmerr, err := AccessList(ctx, s.b, bNrOrHash, args)
+	if err != nil {
+		return nil, err
+	}
+	result := &accessListResult{Accesslist: &acl, GasUsed: hexutil.Uint64(gasUsed)}
+	if vmerr != nil {
+		result.Error = vmerr.Error()
+	}
+	return result, nil
+}
+
+// AccessList creates an access list for the given transaction.
+// If the accesslist creation fails an error is returned.
+// If the transaction itself fails, an vmErr is returned.
+func AccessList(ctx context.Context, b Backend, blockNrOrHash rpc.BlockNumberOrHash, args SendTxArgs) (acl types.AccessList, gasUsed uint64, vmErr error, err error) {
+	// Retrieve the execution context
+	db, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
+	if db == nil || err != nil {
+		return nil, 0, nil, err
+	}
+	// If the gas amount is not set, extract this as it will depend on access
+	// lists and we'll need to reestimate every time
+	nogas := args.Gas == nil
+
+	// Ensure any missing fields are filled, extract the recipient and input data
+	if err := args.setDefaults(ctx, b); err != nil {
+		return nil, 0, nil, err
+	}
+	var to common.Address
+	if args.To != nil {
+		to = *args.To
+	} else {
+		to = crypto.CreateAddress(args.From, uint64(*args.Nonce))
+	}
+	var input []byte
+	if args.Input != nil {
+		input = *args.Input
+	} else if args.Data != nil {
+		input = *args.Data
+	}
+	// Retrieve the precompiles since they don't need to be added to the access list
+	precompiles := vm.ActivePrecompiles(b.ChainConfig().Rules(header.Number))
+
+	// Create an initial tracer
+	prevTracer := vm.NewAccessListTracer(nil, args.From, to, precompiles)
+	if args.AccessList != nil {
+		prevTracer = vm.NewAccessListTracer(*args.AccessList, args.From, to, precompiles)
+	}
+	for {
+		// Retrieve the current access list to expand
+		accessList := prevTracer.AccessList()
+		log.Trace("Creating access list", "input", accessList)
+
+		// If no gas amount was specified, each unique access list needs it's own
+		// gas calculation. This is quite expensive, but we need to be accurate
+		// and it's convered by the sender only anyway.
+		if nogas {
+			args.Gas = nil
+			if err := args.setDefaults(ctx, b); err != nil {
+				return nil, 0, nil, err // shouldn't happen, just in case
+			}
+		}
+		// Copy the original db so we don't modify it
+		statedb := db.Copy()
+		msg := types.NewMessage(args.From, args.To, uint64(*args.Nonce), args.Value.ToInt(), uint64(*args.Gas), args.GasPrice.ToInt(), input, accessList, false)
+
+		// Apply the transaction with the access list tracer
+		tracer := vm.NewAccessListTracer(accessList, args.From, to, precompiles)
+		config := vm.Config{Tracer: tracer, Debug: true}
+		vmenv, _, err := b.GetEVM(ctx, msg, statedb, header, &config)
+		if err != nil {
+			return nil, 0, nil, err
+		}
+		res, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(msg.Gas()))
+		if err != nil {
+			return nil, 0, nil, fmt.Errorf("failed to apply transaction: %v err: %v", args.toTransaction().Hash(), err)
+		}
+		if tracer.Equal(prevTracer) {
+			return accessList, res.UsedGas, res.Err, nil
+		}
+		prevTracer = tracer
+	}
+}
+
 // PublicTransactionPoolAPI exposes methods for the RPC interface
 type PublicTransactionPoolAPI struct {
 	b         Backend
@@ -1539,7 +1639,6 @@ func (args *SendTxArgs) setDefaults(ctx context.Context, b Backend) error {
 			return errors.New(`contract creation without any data provided`)
 		}
 	}
-
 	// Estimate the gas usage if necessary.
 	if args.Gas == nil {
 		// For backwards-compatibility reason, we try both input and data
@@ -1580,7 +1679,6 @@ func (args *SendTxArgs) toTransaction() *types.Transaction {
 	} else if args.Data != nil {
 		input = *args.Data
 	}
-
 	var data types.TxData
 	if args.AccessList == nil {
 		data = &types.LegacyTx{

internal/ethapi/backend.go

@@ -63,7 +63,7 @@ type Backend interface {
 	StateAndHeaderByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*state.StateDB, *types.Header, error)
 	GetReceipts(ctx context.Context, hash common.Hash) (types.Receipts, error)
 	GetTd(ctx context.Context, hash common.Hash) *big.Int
-	GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header) (*vm.EVM, func() error, error)
+	GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header, vmConfig *vm.Config) (*vm.EVM, func() error, error)
 	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
 	SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription
 	SubscribeChainSideEvent(ch chan<- core.ChainSideEvent) event.Subscription

internal/web3ext/web3ext.go

@@ -575,6 +575,12 @@ web3._extend({
 			params: 3,
 			inputFormatter: [web3._extend.formatters.inputAddressFormatter, null, web3._extend.formatters.inputBlockNumberFormatter]
 		}),
+		new web3._extend.Method({
+			name: 'createAccessList',
+			call: 'eth_createAccessList',
+			params: 2,
+			inputFormatter: [null, web3._extend.formatters.inputBlockNumberFormatter],
+		}),
 	],
 	properties: [
 		new web3._extend.Property({

les/api_backend.go

@@ -171,10 +171,13 @@ func (b *LesApiBackend) GetTd(ctx context.Context, hash common.Hash) *big.Int {
 	return nil
 }
 
-func (b *LesApiBackend) GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header) (*vm.EVM, func() error, error) {
+func (b *LesApiBackend) GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header, vmConfig *vm.Config) (*vm.EVM, func() error, error) {
+	if vmConfig == nil {
+		vmConfig = new(vm.Config)
+	}
 	txContext := core.NewEVMTxContext(msg)
 	context := core.NewEVMBlockContext(header, b.eth.blockchain, nil)
-	return vm.NewEVM(context, txContext, state, b.eth.chainConfig, vm.Config{}), state.Error, nil
+	return vm.NewEVM(context, txContext, state, b.eth.chainConfig, *vmConfig), state.Error, nil
 }
 
 func (b *LesApiBackend) SendTx(ctx context.Context, signedTx *types.Transaction) error {