eth, internal: extend the TraceCall API (#22245)

Adds an an optional parameter `overrides *map[common.Address]account` to the `eth_call` API in order for the caller to  can customize the state.

eth/tracers/api.go

@@ -161,6 +161,16 @@ type TraceConfig struct {
 	Reexec  *uint64
 }
 
+// TraceCallConfig is the config for traceCall API. It holds one more
+// field to override the state for tracing.
+type TraceCallConfig struct {
+	*vm.LogConfig
+	Tracer         *string
+	Timeout        *string
+	Reexec         *uint64
+	StateOverrides *ethapi.StateOverride
+}
+
 // StdTraceConfig holds extra parameters to standard-json trace functions.
 type StdTraceConfig struct {
 	vm.LogConfig
@@ -720,7 +730,7 @@ func (api *API) TraceTransaction(ctx context.Context, hash common.Hash, config *
 // created during the execution of EVM if the given transaction was added on
 // top of the provided block and returns them as a JSON object.
 // You can provide -2 as a block number to trace on top of the pending block.
-func (api *API) TraceCall(ctx context.Context, args ethapi.CallArgs, blockNrOrHash rpc.BlockNumberOrHash, config *TraceConfig) (interface{}, error) {
+func (api *API) TraceCall(ctx context.Context, args ethapi.CallArgs, blockNrOrHash rpc.BlockNumberOrHash, config *TraceCallConfig) (interface{}, error) {
 	// Try to retrieve the specified block
 	var (
 		err   error
@@ -730,6 +740,8 @@ func (api *API) TraceCall(ctx context.Context, args ethapi.CallArgs, blockNrOrHa
 		block, err = api.blockByHash(ctx, hash)
 	} else if number, ok := blockNrOrHash.Number(); ok {
 		block, err = api.blockByNumber(ctx, number)
+	} else {
+		return nil, errors.New("invalid arguments; neither block nor hash specified")
 	}
 	if err != nil {
 		return nil, err
@@ -743,11 +755,26 @@ func (api *API) TraceCall(ctx context.Context, args ethapi.CallArgs, blockNrOrHa
 	if err != nil {
 		return nil, err
 	}
+	// Apply the customized state rules if required.
+	if config != nil {
+		if err := config.StateOverrides.Apply(statedb); err != nil {
+			return nil, err
+		}
+	}
 	// Execute the trace
 	msg := args.ToMessage(api.backend.RPCGasCap())
 	vmctx := core.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)
 
-	return api.traceTx(ctx, msg, new(txTraceContext), vmctx, statedb, config)
+	var traceConfig *TraceConfig
+	if config != nil {
+		traceConfig = &TraceConfig{
+			LogConfig: config.LogConfig,
+			Tracer:    config.Tracer,
+			Timeout:   config.Timeout,
+			Reexec:    config.Reexec,
+		}
+	}
+	return api.traceTx(ctx, msg, new(txTraceContext), vmctx, statedb, traceConfig)
 }
 
 // traceTx configures a new tracer according to the provided configuration, and
@@ -797,7 +824,7 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *txTrac
 
 	result, err := core.ApplyMessage(vmenv, message, new(core.GasPool).AddGas(message.Gas()))
 	if err != nil {
-		return nil, fmt.Errorf("tracing failed: %v", err)
+		return nil, fmt.Errorf("tracing failed: %w", err)
 	}
 
 	// Depending on the tracer type, format and return the output.

eth/tracers/api_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	"crypto/ecdsa"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math/big"
@@ -198,7 +199,7 @@ func TestTraceCall(t *testing.T) {
 	var testSuite = []struct {
 		blockNumber rpc.BlockNumber
 		call        ethapi.CallArgs
-		config      *TraceConfig
+		config      *TraceCallConfig
 		expectErr   error
 		expect      interface{}
 	}{
@@ -305,6 +306,147 @@ func TestTraceCall(t *testing.T) {
 	}
 }
 
+func TestOverridenTraceCall(t *testing.T) {
+	t.Parallel()
+
+	// Initialize test accounts
+	accounts := newAccounts(3)
+	genesis := &core.Genesis{Alloc: core.GenesisAlloc{
+		accounts[0].addr: {Balance: big.NewInt(params.Ether)},
+		accounts[1].addr: {Balance: big.NewInt(params.Ether)},
+		accounts[2].addr: {Balance: big.NewInt(params.Ether)},
+	}}
+	genBlocks := 10
+	signer := types.HomesteadSigner{}
+	api := NewAPI(newTestBackend(t, genBlocks, genesis, func(i int, b *core.BlockGen) {
+		// Transfer from account[0] to account[1]
+		//    value: 1000 wei
+		//    fee:   0 wei
+		tx, _ := types.SignTx(types.NewTransaction(uint64(i), accounts[1].addr, big.NewInt(1000), params.TxGas, big.NewInt(0), nil), signer, accounts[0].key)
+		b.AddTx(tx)
+	}))
+	randomAccounts, tracer := newAccounts(3), "callTracer"
+
+	var testSuite = []struct {
+		blockNumber rpc.BlockNumber
+		call        ethapi.CallArgs
+		config      *TraceCallConfig
+		expectErr   error
+		expect      *callTrace
+	}{
+		// Succcessful call with state overriding
+		{
+			blockNumber: rpc.PendingBlockNumber,
+			call: ethapi.CallArgs{
+				From:  &randomAccounts[0].addr,
+				To:    &randomAccounts[1].addr,
+				Value: (*hexutil.Big)(big.NewInt(1000)),
+			},
+			config: &TraceCallConfig{
+				Tracer: &tracer,
+				StateOverrides: &ethapi.StateOverride{
+					randomAccounts[0].addr: ethapi.OverrideAccount{Balance: newRPCBalance(new(big.Int).Mul(big.NewInt(1), big.NewInt(params.Ether)))},
+				},
+			},
+			expectErr: nil,
+			expect: &callTrace{
+				Type:    "CALL",
+				From:    randomAccounts[0].addr,
+				To:      randomAccounts[1].addr,
+				Gas:     newRPCUint64(24979000),
+				GasUsed: newRPCUint64(0),
+				Value:   (*hexutil.Big)(big.NewInt(1000)),
+			},
+		},
+		// Invalid call without state overriding
+		{
+			blockNumber: rpc.PendingBlockNumber,
+			call: ethapi.CallArgs{
+				From:  &randomAccounts[0].addr,
+				To:    &randomAccounts[1].addr,
+				Value: (*hexutil.Big)(big.NewInt(1000)),
+			},
+			config: &TraceCallConfig{
+				Tracer: &tracer,
+			},
+			expectErr: core.ErrInsufficientFundsForTransfer,
+			expect:    nil,
+		},
+		// Sucessful simple contract call
+		//
+		// // SPDX-License-Identifier: GPL-3.0
+		//
+		//  pragma solidity >=0.7.0 <0.8.0;
+		//
+		//  /**
+		//   * @title Storage
+		//   * @dev Store & retrieve value in a variable
+		//   */
+		//  contract Storage {
+		//      uint256 public number;
+		//      constructor() {
+		//          number = block.number;
+		//      }
+		//  }
+		{
+			blockNumber: rpc.PendingBlockNumber,
+			call: ethapi.CallArgs{
+				From: &randomAccounts[0].addr,
+				To:   &randomAccounts[2].addr,
+				Data: newRPCBytes(common.Hex2Bytes("8381f58a")), // call number()
+			},
+			config: &TraceCallConfig{
+				Tracer: &tracer,
+				StateOverrides: &ethapi.StateOverride{
+					randomAccounts[2].addr: ethapi.OverrideAccount{
+						Code:      newRPCBytes(common.Hex2Bytes("6080604052348015600f57600080fd5b506004361060285760003560e01c80638381f58a14602d575b600080fd5b60336049565b6040518082815260200191505060405180910390f35b6000548156fea2646970667358221220eab35ffa6ab2adfe380772a48b8ba78e82a1b820a18fcb6f59aa4efb20a5f60064736f6c63430007040033")),
+						StateDiff: newStates([]common.Hash{{}}, []common.Hash{common.BigToHash(big.NewInt(123))}),
+					},
+				},
+			},
+			expectErr: nil,
+			expect: &callTrace{
+				Type:    "CALL",
+				From:    randomAccounts[0].addr,
+				To:      randomAccounts[2].addr,
+				Input:   hexutil.Bytes(common.Hex2Bytes("8381f58a")),
+				Output:  hexutil.Bytes(common.BigToHash(big.NewInt(123)).Bytes()),
+				Gas:     newRPCUint64(24978936),
+				GasUsed: newRPCUint64(2283),
+				Value:   (*hexutil.Big)(big.NewInt(0)),
+			},
+		},
+	}
+	for _, testspec := range testSuite {
+		result, err := api.TraceCall(context.Background(), testspec.call, rpc.BlockNumberOrHash{BlockNumber: &testspec.blockNumber}, testspec.config)
+		if testspec.expectErr != nil {
+			if err == nil {
+				t.Errorf("Expect error %v, get nothing", testspec.expectErr)
+				continue
+			}
+			if !errors.Is(err, testspec.expectErr) {
+				t.Errorf("Error mismatch, want %v, get %v", testspec.expectErr, err)
+			}
+		} else {
+			if err != nil {
+				t.Errorf("Expect no error, get %v", err)
+				continue
+			}
+			ret := new(callTrace)
+			if err := json.Unmarshal(result.(json.RawMessage), ret); err != nil {
+				t.Fatalf("failed to unmarshal trace result: %v", err)
+			}
+			if !jsonEqual(ret, testspec.expect) {
+				// uncomment this for easier debugging
+				//have, _ := json.MarshalIndent(ret, "", " ")
+				//want, _ := json.MarshalIndent(testspec.expect, "", " ")
+				//t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", string(have), string(want))
+				t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", ret, testspec.expect)
+			}
+		}
+	}
+}
+
 func TestTraceTransaction(t *testing.T) {
 	t.Parallel()
 
@@ -469,3 +611,29 @@ func newAccounts(n int) (accounts Accounts) {
 	sort.Sort(accounts)
 	return accounts
 }
+
+func newRPCBalance(balance *big.Int) **hexutil.Big {
+	rpcBalance := (*hexutil.Big)(balance)
+	return &rpcBalance
+}
+
+func newRPCUint64(number uint64) *hexutil.Uint64 {
+	rpcUint64 := hexutil.Uint64(number)
+	return &rpcUint64
+}
+
+func newRPCBytes(bytes []byte) *hexutil.Bytes {
+	rpcBytes := hexutil.Bytes(bytes)
+	return &rpcBytes
+}
+
+func newStates(keys []common.Hash, vals []common.Hash) *map[common.Hash]common.Hash {
+	if len(keys) != len(vals) {
+		panic("invalid input")
+	}
+	m := make(map[common.Hash]common.Hash)
+	for i := 0; i < len(keys); i++ {
+		m[keys[i]] = vals[i]
+	}
+	return &m
+}

internal/ethapi/api.go

@@ -36,6 +36,7 @@ import (
 	"github.com/ethereum/go-ethereum/consensus/clique"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"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/crypto"
@@ -802,13 +803,13 @@ func (args *CallArgs) ToMessage(globalGasCap uint64) types.Message {
 	return msg
 }
 
-// account indicates the overriding fields of account during the execution of
-// a message call.
+// OverrideAccount indicates the overriding fields of account during the execution
+// of a message call.
 // Note, state and stateDiff can't be specified at the same time. If state is
 // set, message execution will only use the data in the given state. Otherwise
 // if statDiff is set, all diff will be applied first and then execute the call
 // message.
-type account struct {
+type OverrideAccount struct {
 	Nonce     *hexutil.Uint64              `json:"nonce"`
 	Code      *hexutil.Bytes               `json:"code"`
 	Balance   **hexutil.Big                `json:"balance"`
@@ -816,15 +817,15 @@ type account struct {
 	StateDiff *map[common.Hash]common.Hash `json:"stateDiff"`
 }
 
-func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides map[common.Address]account, vmCfg vm.Config, timeout time.Duration, globalGasCap uint64) (*core.ExecutionResult, error) {
-	defer func(start time.Time) { log.Debug("Executing EVM call finished", "runtime", time.Since(start)) }(time.Now())
+// StateOverride is the collection of overriden accounts.
+type StateOverride map[common.Address]OverrideAccount
 
-	state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
-	if state == nil || err != nil {
-		return nil, err
+// Apply overrides the fields of specified accounts into the given state.
+func (diff *StateOverride) Apply(state *state.StateDB) error {
+	if diff == nil {
+		return nil
 	}
-	// Override the fields of specified contracts before execution.
-	for addr, account := range overrides {
+	for addr, account := range *diff {
 		// Override account nonce.
 		if account.Nonce != nil {
 			state.SetNonce(addr, uint64(*account.Nonce))
@@ -838,7 +839,7 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 			state.SetBalance(addr, (*big.Int)(*account.Balance))
 		}
 		if account.State != nil && account.StateDiff != nil {
-			return nil, fmt.Errorf("account %s has both 'state' and 'stateDiff'", addr.Hex())
+			return fmt.Errorf("account %s has both 'state' and 'stateDiff'", addr.Hex())
 		}
 		// Replace entire state if caller requires.
 		if account.State != nil {
@@ -851,6 +852,19 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 			}
 		}
 	}
+	return nil
+}
+
+func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride, vmCfg vm.Config, timeout time.Duration, globalGasCap uint64) (*core.ExecutionResult, error) {
+	defer func(start time.Time) { log.Debug("Executing EVM call finished", "runtime", time.Since(start)) }(time.Now())
+
+	state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash)
+	if state == nil || err != nil {
+		return nil, err
+	}
+	if err := overrides.Apply(state); err != nil {
+		return nil, err
+	}
 	// Setup context so it may be cancelled the call has completed
 	// or, in case of unmetered gas, setup a context with a timeout.
 	var cancel context.CancelFunc
@@ -929,12 +943,8 @@ func (e *revertError) ErrorData() interface{} {
 //
 // Note, this function doesn't make and changes in the state/blockchain and is
 // useful to execute and retrieve values.
-func (s *PublicBlockChainAPI) Call(ctx context.Context, args CallArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *map[common.Address]account) (hexutil.Bytes, error) {
-	var accounts map[common.Address]account
-	if overrides != nil {
-		accounts = *overrides
-	}
-	result, err := DoCall(ctx, s.b, args, blockNrOrHash, accounts, vm.Config{}, 5*time.Second, s.b.RPCGasCap())
+func (s *PublicBlockChainAPI) Call(ctx context.Context, args CallArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride) (hexutil.Bytes, error) {
+	result, err := DoCall(ctx, s.b, args, blockNrOrHash, overrides, vm.Config{}, 5*time.Second, s.b.RPCGasCap())
 	if err != nil {
 		return nil, err
 	}