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core,eth: call frame tracing (#23087)

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This change introduces 2 new optional methods; `enter()` and `exit()` for js tracers, and makes `step()` optiona. The two new methods are invoked when entering and exiting a call frame (but not invoked for the outermost scope, which has it's own methods). Currently these are the data fields passed to each of them:

    enter: type (opcode), from, to, input, gas, value
    exit: output, gasUsed, error

The PR also comes with a re-write of the callTracer. As a backup we keep the previous tracing script under the name `callTracerLegacy`. Behaviour of both tracers are equivalent for the most part, although there are some small differences (improvements), where the new tracer is more correct / has more information.
This commit is contained in:
Sina Mahmoodi
2021-09-17 09:31:22 +02:00
committed by GitHub
parent 7ada89d4e6
commit 401354976b
37 changed files with 2290 additions and 286 deletions
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235
eth/tracers/tracer.go
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@@ -284,6 +284,85 @@ func (cw *contractWrapper) pushObject(vm *duktape.Context) {
vm.PutPropString(obj, "getInput")
}
type frame struct {
typ *string
from *common.Address
to *common.Address
input []byte
gas *uint
value *big.Int
}
func newFrame() *frame {
return &frame{
typ: new(string),
from: new(common.Address),
to: new(common.Address),
gas: new(uint),
}
}
func (f *frame) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, *f.typ); return 1 })
vm.PutPropString(obj, "getType")
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, *f.from); return 1 })
vm.PutPropString(obj, "getFrom")
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, *f.to); return 1 })
vm.PutPropString(obj, "getTo")
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, f.input); return 1 })
vm.PutPropString(obj, "getInput")
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, *f.gas); return 1 })
vm.PutPropString(obj, "getGas")
vm.PushGoFunction(func(ctx *duktape.Context) int {
if f.value != nil {
pushValue(ctx, f.value)
} else {
ctx.PushUndefined()
}
return 1
})
vm.PutPropString(obj, "getValue")
}
type frameResult struct {
gasUsed *uint
output []byte
errorValue *string
}
func newFrameResult() *frameResult {
return &frameResult{
gasUsed: new(uint),
}
}
func (r *frameResult) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, *r.gasUsed); return 1 })
vm.PutPropString(obj, "getGasUsed")
vm.PushGoFunction(func(ctx *duktape.Context) int { pushValue(ctx, r.output); return 1 })
vm.PutPropString(obj, "getOutput")
vm.PushGoFunction(func(ctx *duktape.Context) int {
if r.errorValue != nil {
pushValue(ctx, *r.errorValue)
} else {
ctx.PushUndefined()
}
return 1
})
vm.PutPropString(obj, "getError")
}
// Tracer provides an implementation of Tracer that evaluates a Javascript
// function for each VM execution step.
type Tracer struct {
@@ -305,6 +384,9 @@ type Tracer struct {
errorValue *string // Swappable error value wrapped by a log accessor
refundValue *uint // Swappable refund value wrapped by a log accessor
frame *frame // Represents entry into call frame. Fields are swappable
frameResult *frameResult // Represents exit from a call frame. Fields are swappable
ctx map[string]interface{} // Transaction context gathered throughout execution
err error // Error, if one has occurred
@@ -312,6 +394,8 @@ type Tracer struct {
reason error // Textual reason for the interruption
activePrecompiles []common.Address // Updated on CaptureStart based on given rules
traceSteps bool // When true, will invoke step() on each opcode
traceCallFrames bool // When true, will invoke enter() and exit() js funcs
}
// Context contains some contextual infos for a transaction execution that is not
@@ -343,6 +427,8 @@ func New(code string, ctx *Context) (*Tracer, error) {
costValue: new(uint),
depthValue: new(uint),
refundValue: new(uint),
frame: newFrame(),
frameResult: newFrameResult(),
}
if ctx.BlockHash != (common.Hash{}) {
tracer.ctx["blockHash"] = ctx.BlockHash
@@ -450,9 +536,7 @@ func New(code string, ctx *Context) (*Tracer, error) {
}
tracer.tracerObject = 0 // yeah, nice, eval can't return the index itself
if !tracer.vm.GetPropString(tracer.tracerObject, "step") {
return nil, fmt.Errorf("trace object must expose a function step()")
}
hasStep := tracer.vm.GetPropString(tracer.tracerObject, "step")
tracer.vm.Pop()
if !tracer.vm.GetPropString(tracer.tracerObject, "fault") {
@@ -465,6 +549,23 @@ func New(code string, ctx *Context) (*Tracer, error) {
}
tracer.vm.Pop()
hasEnter := tracer.vm.GetPropString(tracer.tracerObject, "enter")
tracer.vm.Pop()
hasExit := tracer.vm.GetPropString(tracer.tracerObject, "exit")
tracer.vm.Pop()
if hasEnter != hasExit {
return nil, fmt.Errorf("trace object must expose either both or none of enter() and exit()")
}
if !hasStep {
// If there's no step function, the enter and exit must be present
if !hasEnter {
return nil, fmt.Errorf("trace object must expose either step() or both enter() and exit()")
}
}
tracer.traceCallFrames = hasEnter
tracer.traceSteps = hasStep
// Tracer is valid, inject the big int library to access large numbers
tracer.vm.EvalString(bigIntegerJS)
tracer.vm.PutGlobalString("bigInt")
@@ -513,6 +614,12 @@ func New(code string, ctx *Context) (*Tracer, error) {
tracer.vm.PutPropString(tracer.stateObject, "log")
tracer.frame.pushObject(tracer.vm)
tracer.vm.PutPropString(tracer.stateObject, "frame")
tracer.frameResult.pushObject(tracer.vm)
tracer.vm.PutPropString(tracer.stateObject, "frameResult")
tracer.dbWrapper.pushObject(tracer.vm)
tracer.vm.PutPropString(tracer.stateObject, "db")
@@ -594,6 +701,9 @@ func (jst *Tracer) CaptureStart(env *vm.EVM, from common.Address, to common.Addr
// CaptureState implements the Tracer interface to trace a single step of VM execution.
func (jst *Tracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
if !jst.traceSteps {
return
}
if jst.err != nil {
return
}
@@ -650,41 +760,70 @@ func (jst *Tracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, er
}
}
// CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct).
func (jst *Tracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
if !jst.traceCallFrames {
return
}
if jst.err != nil {
return
}
// If tracing was interrupted, set the error and stop
if atomic.LoadUint32(&jst.interrupt) > 0 {
jst.err = jst.reason
return
}
*jst.frame.typ = typ.String()
*jst.frame.from = from
*jst.frame.to = to
jst.frame.input = common.CopyBytes(input)
*jst.frame.gas = uint(gas)
jst.frame.value = nil
if value != nil {
jst.frame.value = new(big.Int).SetBytes(value.Bytes())
}
if _, err := jst.call(true, "enter", "frame"); err != nil {
jst.err = wrapError("enter", err)
}
}
// CaptureExit is called when EVM exits a scope, even if the scope didn't
// execute any code.
func (jst *Tracer) CaptureExit(output []byte, gasUsed uint64, err error) {
if !jst.traceCallFrames {
return
}
if jst.err != nil {
return
}
// If tracing was interrupted, set the error and stop
if atomic.LoadUint32(&jst.interrupt) > 0 {
jst.err = jst.reason
return
}
jst.frameResult.output = common.CopyBytes(output)
*jst.frameResult.gasUsed = uint(gasUsed)
jst.frameResult.errorValue = nil
if err != nil {
jst.frameResult.errorValue = new(string)
*jst.frameResult.errorValue = err.Error()
}
if _, err := jst.call(true, "exit", "frameResult"); err != nil {
jst.err = wrapError("exit", err)
}
}
// GetResult calls the Javascript 'result' function and returns its value, or any accumulated error
func (jst *Tracer) GetResult() (json.RawMessage, error) {
// Transform the context into a JavaScript object and inject into the state
obj := jst.vm.PushObject()
for key, val := range jst.ctx {
switch val := val.(type) {
case uint64:
jst.vm.PushUint(uint(val))
case string:
jst.vm.PushString(val)
case []byte:
ptr := jst.vm.PushFixedBuffer(len(val))
copy(makeSlice(ptr, uint(len(val))), val)
case common.Address:
ptr := jst.vm.PushFixedBuffer(20)
copy(makeSlice(ptr, 20), val[:])
case *big.Int:
pushBigInt(val, jst.vm)
case int:
jst.vm.PushInt(val)
case common.Hash:
ptr := jst.vm.PushFixedBuffer(32)
copy(makeSlice(ptr, 32), val[:])
default:
panic(fmt.Sprintf("unsupported type: %T", val))
}
jst.vm.PutPropString(obj, key)
jst.addToObj(obj, key, val)
}
jst.vm.PutPropString(jst.stateObject, "ctx")
@@ -699,3 +838,35 @@ func (jst *Tracer) GetResult() (json.RawMessage, error) {
return result, jst.err
}
// addToObj pushes a field to a JS object.
func (jst *Tracer) addToObj(obj int, key string, val interface{}) {
pushValue(jst.vm, val)
jst.vm.PutPropString(obj, key)
}
func pushValue(ctx *duktape.Context, val interface{}) {
switch val := val.(type) {
case uint64:
ctx.PushUint(uint(val))
case string:
ctx.PushString(val)
case []byte:
ptr := ctx.PushFixedBuffer(len(val))
copy(makeSlice(ptr, uint(len(val))), val)
case common.Address:
ptr := ctx.PushFixedBuffer(20)
copy(makeSlice(ptr, 20), val[:])
case *big.Int:
pushBigInt(val, ctx)
case int:
ctx.PushInt(val)
case uint:
ctx.PushUint(val)
case common.Hash:
ptr := ctx.PushFixedBuffer(32)
copy(makeSlice(ptr, 32), val[:])
default:
panic(fmt.Sprintf("unsupported type: %T", val))
}
}