eth/tracers: add onlyTopCall option to callTracer (#25430)

This PR allows users to pass in a config object directly to the tracers. Previously only the struct logger was configurable.

It also adds an option to the call tracer which if enabled makes it ignore any subcall and collect only information about the top-level call. See #25419 for discussion.

The tracers will silently ignore if they are passed a config they don't care about.

core/vm/runtime/runtime_test.go

@@ -333,7 +333,7 @@ func benchmarkNonModifyingCode(gas uint64, code []byte, name string, tracerCode
 	cfg.State, _ = state.New(common.Hash{}, state.NewDatabase(rawdb.NewMemoryDatabase()), nil)
 	cfg.GasLimit = gas
 	if len(tracerCode) > 0 {
-		tracer, err := tracers.New(tracerCode, new(tracers.Context))
+		tracer, err := tracers.New(tracerCode, new(tracers.Context), nil)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -832,7 +832,7 @@ func TestRuntimeJSTracer(t *testing.T) {
 			statedb.SetCode(common.HexToAddress("0xee"), calleeCode)
 			statedb.SetCode(common.HexToAddress("0xff"), depressedCode)
 
-			tracer, err := tracers.New(jsTracer, new(tracers.Context))
+			tracer, err := tracers.New(jsTracer, new(tracers.Context), nil)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -868,7 +868,7 @@ func TestJSTracerCreateTx(t *testing.T) {
 	code := []byte{byte(vm.PUSH1), 0, byte(vm.PUSH1), 0, byte(vm.RETURN)}
 
 	statedb, _ := state.New(common.Hash{}, state.NewDatabase(rawdb.NewMemoryDatabase()), nil)
-	tracer, err := tracers.New(jsTracer, new(tracers.Context))
+	tracer, err := tracers.New(jsTracer, new(tracers.Context), nil)
 	if err != nil {
 		t.Fatal(err)
 	}

eth/tracers/api.go

@@ -20,6 +20,7 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
@@ -169,15 +170,15 @@ type TraceConfig struct {
 	Tracer  *string
 	Timeout *string
 	Reexec  *uint64
+	// Config specific to given tracer. Note struct logger
+	// config are historically embedded in main object.
+	TracerConfig json.RawMessage
 }
 
 // TraceCallConfig is the config for traceCall API. It holds one more
 // field to override the state for tracing.
 type TraceCallConfig struct {
-	*logger.Config
+	TraceConfig
-	Tracer         *string
-	Timeout        *string
-	Reexec         *uint64
 	StateOverrides *ethapi.StateOverride
 	BlockOverrides *ethapi.BlockOverrides
 }
@@ -882,7 +883,7 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Contex
 	// Default tracer is the struct logger
 	tracer = logger.NewStructLogger(config.Config)
 	if config.Tracer != nil {
-		tracer, err = New(*config.Tracer, txctx)
+		tracer, err = New(*config.Tracer, txctx, config.TracerConfig)
 		if err != nil {
 			return nil, err
 		}

eth/tracers/internal/tracetest/calltrace_test.go

@@ -121,6 +121,7 @@ type callTracerTest struct {
 	Genesis      *core.Genesis   `json:"genesis"`
 	Context      *callContext    `json:"context"`
 	Input        string          `json:"input"`
+	TracerConfig json.RawMessage `json:"tracerConfig"`
 	Result       *callTrace      `json:"result"`
 }
 
@@ -179,7 +180,7 @@ func testCallTracer(tracerName string, dirPath string, t *testing.T) {
 				}
 				_, statedb = tests.MakePreState(rawdb.NewMemoryDatabase(), test.Genesis.Alloc, false)
 			)
-			tracer, err := tracers.New(tracerName, new(tracers.Context))
+			tracer, err := tracers.New(tracerName, new(tracers.Context), test.TracerConfig)
 			if err != nil {
 				t.Fatalf("failed to create call tracer: %v", err)
 			}
@@ -293,7 +294,7 @@ func benchTracer(tracerName string, test *callTracerTest, b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		tracer, err := tracers.New(tracerName, new(tracers.Context))
+		tracer, err := tracers.New(tracerName, new(tracers.Context), nil)
 		if err != nil {
 			b.Fatalf("failed to create call tracer: %v", err)
 		}
@@ -359,7 +360,7 @@ func TestZeroValueToNotExitCall(t *testing.T) {
 	}
 	_, statedb := tests.MakePreState(rawdb.NewMemoryDatabase(), alloc, false)
 	// Create the tracer, the EVM environment and run it
-	tracer, err := tracers.New("callTracer", nil)
+	tracer, err := tracers.New("callTracer", nil, nil)
 	if err != nil {
 		t.Fatalf("failed to create call tracer: %v", err)
 	}

eth/tracers/internal/tracetest/testdata/call_tracer/simple_onlytop.json

@@ -0,0 +1,72 @@
+{
+  "context": {
+    "difficulty": "3502894804",
+    "gasLimit": "4722976",
+    "miner": "0x1585936b53834b021f68cc13eeefdec2efc8e724",
+    "number": "2289806",
+    "timestamp": "1513601314"
+  },
+  "genesis": {
+    "alloc": {
+      "0x0024f658a46fbb89d8ac105e98d7ac7cbbaf27c5": {
+        "balance": "0x0",
+        "code": "0x",
+        "nonce": "22",
+        "storage": {}
+      },
+      "0x3b873a919aa0512d5a0f09e6dcceaa4a6727fafe": {
+        "balance": "0x4d87094125a369d9bd5",
+        "code": "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",
+        "nonce": "1",
+        "storage": {
+          "0x0000000000000000000000000000000000000000000000000000000000000000": "0x000000000000000000000001b436ba50d378d4bbc8660d312a13df6af6e89dfb",
+          "0x0000000000000000000000000000000000000000000000000000000000000001": "0x00000000000000000000000000000000000000000000000006f05b59d3b20000",
+          "0x0000000000000000000000000000000000000000000000000000000000000002": "0x000000000000000000000000000000000000000000000000000000000000003c",
+          "0x0000000000000000000000000000000000000000000000000000000000000003": "0x000000000000000000000000000000000000000000000000000000005a37b834"
+        }
+      },
+      "0xb436ba50d378d4bbc8660d312a13df6af6e89dfb": {
+        "balance": "0x1780d77678137ac1b775",
+        "code": "0x",
+        "nonce": "29072",
+        "storage": {}
+      }
+    },
+    "config": {
+      "byzantiumBlock": 1700000,
+      "chainId": 3,
+      "daoForkSupport": true,
+      "eip150Block": 0,
+      "eip150Hash": "0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d",
+      "eip155Block": 10,
+      "eip158Block": 10,
+      "ethash": {},
+      "homesteadBlock": 0
+    },
+    "difficulty": "3509749784",
+    "extraData": "0x4554482e45544846414e532e4f52472d4641313738394444",
+    "gasLimit": "4727564",
+    "hash": "0x609948ac3bd3c00b7736b933248891d6c901ee28f066241bddb28f4e00a9f440",
+    "miner": "0xbbf5029fd710d227630c8b7d338051b8e76d50b3",
+    "mixHash": "0xb131e4507c93c7377de00e7c271bf409ec7492767142ff0f45c882f8068c2ada",
+    "nonce": "0x4eb12e19c16d43da",
+    "number": "2289805",
+    "stateRoot": "0xc7f10f352bff82fac3c2999d3085093d12652e19c7fd32591de49dc5d91b4f1f",
+    "timestamp": "1513601261",
+    "totalDifficulty": "7143276353481064"
+  },
+  "input": "0xf88b8271908506fc23ac0083015f90943b873a919aa0512d5a0f09e6dcceaa4a6727fafe80a463e4bff40000000000000000000000000024f658a46fbb89d8ac105e98d7ac7cbbaf27c52aa0bdce0b59e8761854e857fe64015f06dd08a4fbb7624f6094893a79a72e6ad6bea01d9dde033cff7bb235a3163f348a6d7ab8d6b52bc0963a95b91612e40ca766a4",
+  "tracerConfig": {
+      "onlyTopCall": true
+  },
+  "result": {
+    "from": "0xb436ba50d378d4bbc8660d312a13df6af6e89dfb",
+    "gas": "0x10738",
+    "gasUsed": "0x3ef9",
+    "input": "0x63e4bff40000000000000000000000000024f658a46fbb89d8ac105e98d7ac7cbbaf27c5",
+    "output": "0x0000000000000000000000000000000000000000000000000000000000000001",
+    "to": "0x3b873a919aa0512d5a0f09e6dcceaa4a6727fafe",
+    "type": "CALL",
+    "value": "0x0"
+  }
+}

eth/tracers/js/goja.go

@@ -125,7 +125,7 @@ type jsTracer struct {
 // The methods `result` and `fault` are required to be present.
 // The methods `step`, `enter`, and `exit` are optional, but note that
 // `enter` and `exit` always go together.
-func newJsTracer(code string, ctx *tracers.Context) (tracers.Tracer, error) {
+func newJsTracer(code string, ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
 	if c, ok := assetTracers[code]; ok {
 		code = c
 	}
@@ -177,6 +177,17 @@ func newJsTracer(code string, ctx *tracers.Context) (tracers.Tracer, error) {
 	t.exit = exit
 	t.result = result
 	t.fault = fault
+
+	// Pass in config
+	if setup, ok := goja.AssertFunction(obj.Get("setup")); ok {
+		cfgStr := "{}"
+		if cfg != nil {
+			cfgStr = string(cfg)
+		}
+		if _, err := setup(obj, vm.ToValue(cfgStr)); err != nil {
+			return nil, err
+		}
+	}
 	// Setup objects carrying data to JS. These are created once and re-used.
 	t.log = &steplog{
 		vm:       vm,

eth/tracers/js/tracer_test.go

@@ -85,7 +85,7 @@ func runTrace(tracer tracers.Tracer, vmctx *vmContext, chaincfg *params.ChainCon
 func TestTracer(t *testing.T) {
 	execTracer := func(code string) ([]byte, string) {
 		t.Helper()
-		tracer, err := newJsTracer(code, nil)
+		tracer, err := newJsTracer(code, nil, nil)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -149,7 +149,7 @@ func TestTracer(t *testing.T) {
 
 func TestHalt(t *testing.T) {
 	timeout := errors.New("stahp")
-	tracer, err := newJsTracer("{step: function() { while(1); }, result: function() { return null; }, fault: function(){}}", nil)
+	tracer, err := newJsTracer("{step: function() { while(1); }, result: function() { return null; }, fault: function(){}}", nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -163,7 +163,7 @@ func TestHalt(t *testing.T) {
 }
 
 func TestHaltBetweenSteps(t *testing.T) {
-	tracer, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }}", nil)
+	tracer, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }}", nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -187,7 +187,7 @@ func TestHaltBetweenSteps(t *testing.T) {
 func TestNoStepExec(t *testing.T) {
 	execTracer := func(code string) []byte {
 		t.Helper()
-		tracer, err := newJsTracer(code, nil)
+		tracer, err := newJsTracer(code, nil, nil)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -221,7 +221,7 @@ func TestIsPrecompile(t *testing.T) {
 	chaincfg.IstanbulBlock = big.NewInt(200)
 	chaincfg.BerlinBlock = big.NewInt(300)
 	txCtx := vm.TxContext{GasPrice: big.NewInt(100000)}
-	tracer, err := newJsTracer("{addr: toAddress('0000000000000000000000000000000000000009'), res: null, step: function() { this.res = isPrecompiled(this.addr); }, fault: function() {}, result: function() { return this.res; }}", nil)
+	tracer, err := newJsTracer("{addr: toAddress('0000000000000000000000000000000000000009'), res: null, step: function() { this.res = isPrecompiled(this.addr); }, fault: function() {}, result: function() { return this.res; }}", nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -235,7 +235,7 @@ func TestIsPrecompile(t *testing.T) {
 		t.Errorf("tracer should not consider blake2f as precompile in byzantium")
 	}
 
-	tracer, _ = newJsTracer("{addr: toAddress('0000000000000000000000000000000000000009'), res: null, step: function() { this.res = isPrecompiled(this.addr); }, fault: function() {}, result: function() { return this.res; }}", nil)
+	tracer, _ = newJsTracer("{addr: toAddress('0000000000000000000000000000000000000009'), res: null, step: function() { this.res = isPrecompiled(this.addr); }, fault: function() {}, result: function() { return this.res; }}", nil, nil)
 	blockCtx = vm.BlockContext{BlockNumber: big.NewInt(250)}
 	res, err = runTrace(tracer, &vmContext{blockCtx, txCtx}, chaincfg)
 	if err != nil {
@@ -248,14 +248,14 @@ func TestIsPrecompile(t *testing.T) {
 
 func TestEnterExit(t *testing.T) {
 	// test that either both or none of enter() and exit() are defined
-	if _, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }, enter: function() {}}", new(tracers.Context)); err == nil {
+	if _, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }, enter: function() {}}", new(tracers.Context), nil); err == nil {
 		t.Fatal("tracer creation should've failed without exit() definition")
 	}
-	if _, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }, enter: function() {}, exit: function() {}}", new(tracers.Context)); err != nil {
+	if _, err := newJsTracer("{step: function() {}, fault: function() {}, result: function() { return null; }, enter: function() {}, exit: function() {}}", new(tracers.Context), nil); err != nil {
 		t.Fatal(err)
 	}
 	// test that the enter and exit method are correctly invoked and the values passed
-	tracer, err := newJsTracer("{enters: 0, exits: 0, enterGas: 0, gasUsed: 0, step: function() {}, fault: function() {}, result: function() { return {enters: this.enters, exits: this.exits, enterGas: this.enterGas, gasUsed: this.gasUsed} }, enter: function(frame) { this.enters++; this.enterGas = frame.getGas(); }, exit: function(res) { this.exits++; this.gasUsed = res.getGasUsed(); }}", new(tracers.Context))
+	tracer, err := newJsTracer("{enters: 0, exits: 0, enterGas: 0, gasUsed: 0, step: function() {}, fault: function() {}, result: function() { return {enters: this.enters, exits: this.exits, enterGas: this.enterGas, gasUsed: this.gasUsed} }, enter: function(frame) { this.enters++; this.enterGas = frame.getGas(); }, exit: function(res) { this.exits++; this.gasUsed = res.getGasUsed(); }}", new(tracers.Context), nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -274,3 +274,33 @@ func TestEnterExit(t *testing.T) {
 		t.Errorf("Number of invocations of enter() and exit() is wrong. Have %s, want %s\n", have, want)
 	}
 }
+
+func TestSetup(t *testing.T) {
+	// Test empty config
+	_, err := newJsTracer(`{setup: function(cfg) { if (cfg !== "{}") { throw("invalid empty config") } }, fault: function() {}, result: function() {}}`, new(tracers.Context), nil)
+	if err != nil {
+		t.Error(err)
+	}
+
+	cfg, err := json.Marshal(map[string]string{"foo": "bar"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Test no setup func
+	_, err = newJsTracer(`{fault: function() {}, result: function() {}}`, new(tracers.Context), cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Test config value
+	tracer, err := newJsTracer("{config: null, setup: function(cfg) { this.config = JSON.parse(cfg) }, step: function() {}, fault: function() {}, result: function() { return this.config.foo }}", new(tracers.Context), cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	have, err := tracer.GetResult()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(have) != `"bar"` {
+		t.Errorf("tracer returned wrong result. have: %s, want: \"bar\"\n", string(have))
+	}
+}

eth/tracers/native/4byte.go

@@ -55,11 +55,11 @@ type fourByteTracer struct {
 
 // newFourByteTracer returns a native go tracer which collects
 // 4 byte-identifiers of a tx, and implements vm.EVMLogger.
-func newFourByteTracer(ctx *tracers.Context) tracers.Tracer {
+func newFourByteTracer(ctx *tracers.Context, _ json.RawMessage) (tracers.Tracer, error) {
 	t := &fourByteTracer{
 		ids: make(map[string]int),
 	}
-	return t
+	return t, nil
 }
 
 // isPrecompiled returns whether the addr is a precompile. Logic borrowed from newJsTracer in eth/tracers/js/tracer.go

eth/tracers/native/call.go

@@ -50,16 +50,27 @@ type callFrame struct {
 type callTracer struct {
 	env       *vm.EVM
 	callstack []callFrame
+	config    callTracerConfig
 	interrupt uint32 // Atomic flag to signal execution interruption
 	reason    error  // Textual reason for the interruption
 }
 
+type callTracerConfig struct {
+	OnlyTopCall bool `json:"onlyTopCall"` // If true, call tracer won't collect any subcalls
+}
+
 // newCallTracer returns a native go tracer which tracks
 // call frames of a tx, and implements vm.EVMLogger.
-func newCallTracer(ctx *tracers.Context) tracers.Tracer {
+func newCallTracer(ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
+	var config callTracerConfig
+	if cfg != nil {
+		if err := json.Unmarshal(cfg, &config); err != nil {
+			return nil, err
+		}
+	}
 	// First callframe contains tx context info
 	// and is populated on start and end.
-	return &callTracer{callstack: make([]callFrame, 1)}
+	return &callTracer{callstack: make([]callFrame, 1), config: config}, nil
 }
 
 // CaptureStart implements the EVMLogger interface to initialize the tracing operation.
@@ -101,6 +112,9 @@ func (t *callTracer) CaptureFault(pc uint64, op vm.OpCode, gas, cost uint64, _ *
 
 // CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct).
 func (t *callTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
+	if t.config.OnlyTopCall {
+		return
+	}
 	// Skip if tracing was interrupted
 	if atomic.LoadUint32(&t.interrupt) > 0 {
 		t.env.Cancel()
@@ -121,6 +135,9 @@ func (t *callTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.
 // CaptureExit is called when EVM exits a scope, even if the scope didn't
 // execute any code.
 func (t *callTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
+	if t.config.OnlyTopCall {
+		return
+	}
 	size := len(t.callstack)
 	if size <= 1 {
 		return

eth/tracers/native/noop.go

@@ -35,8 +35,8 @@ func init() {
 type noopTracer struct{}
 
 // newNoopTracer returns a new noop tracer.
-func newNoopTracer(ctx *tracers.Context) tracers.Tracer {
+func newNoopTracer(ctx *tracers.Context, _ json.RawMessage) (tracers.Tracer, error) {
-	return &noopTracer{}
+	return &noopTracer{}, nil
 }
 
 // CaptureStart implements the EVMLogger interface to initialize the tracing operation.

eth/tracers/native/prestate.go

@@ -51,10 +51,10 @@ type prestateTracer struct {
 	reason    error  // Textual reason for the interruption
 }
 
-func newPrestateTracer(ctx *tracers.Context) tracers.Tracer {
+func newPrestateTracer(ctx *tracers.Context, _ json.RawMessage) (tracers.Tracer, error) {
 	// First callframe contains tx context info
 	// and is populated on start and end.
-	return &prestateTracer{prestate: prestate{}}
+	return &prestateTracer{prestate: prestate{}}, nil
 }
 
 // CaptureStart implements the EVMLogger interface to initialize the tracing operation.

eth/tracers/native/revertreason.go

@@ -46,8 +46,8 @@ type revertReasonTracer struct {
 }
 
 // newRevertReasonTracer returns a new revert reason tracer.
-func newRevertReasonTracer(_ *tracers.Context) tracers.Tracer {
+func newRevertReasonTracer(_ *tracers.Context, _ json.RawMessage) (tracers.Tracer, error) {
-	return &revertReasonTracer{}
+	return &revertReasonTracer{}, nil
 }
 
 // CaptureStart implements the EVMLogger interface to initialize the tracing operation.

eth/tracers/native/tracer.go

@@ -35,6 +35,7 @@ func init() {
 package native
 
 import (
+	"encoding/json"
 	"errors"
 
 	"github.com/ethereum/go-ethereum/eth/tracers"
@@ -46,7 +47,7 @@ func init() {
 }
 
 // ctorFn is the constructor signature of a native tracer.
-type ctorFn = func(*tracers.Context) tracers.Tracer
+type ctorFn = func(*tracers.Context, json.RawMessage) (tracers.Tracer, error)
 
 /*
 ctors is a map of package-local tracer constructors.
@@ -71,12 +72,12 @@ func register(name string, ctor ctorFn) {
 }
 
 // lookup returns a tracer, if one can be matched to the given name.
-func lookup(name string, ctx *tracers.Context) (tracers.Tracer, error) {
+func lookup(name string, ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
 	if ctors == nil {
 		ctors = make(map[string]ctorFn)
 	}
 	if ctor, ok := ctors[name]; ok {
-		return ctor(ctx), nil
+		return ctor(ctx, cfg)
 	}
 	return nil, errors.New("no tracer found")
 }

eth/tracers/tracers.go

@@ -42,7 +42,7 @@ type Tracer interface {
 	Stop(err error)
 }
 
-type lookupFunc func(string, *Context) (Tracer, error)
+type lookupFunc func(string, *Context, json.RawMessage) (Tracer, error)
 
 var (
 	lookups []lookupFunc
@@ -62,9 +62,9 @@ func RegisterLookup(wildcard bool, lookup lookupFunc) {
 
 // New returns a new instance of a tracer, by iterating through the
 // registered lookups.
-func New(code string, ctx *Context) (Tracer, error) {
+func New(code string, ctx *Context, cfg json.RawMessage) (Tracer, error) {
 	for _, lookup := range lookups {
-		if tracer, err := lookup(code, ctx); err == nil {
+		if tracer, err := lookup(code, ctx, cfg); err == nil {
 			return tracer, nil
 		}
 	}