plugeth/eth/tracers/js/tracer.go

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// Copyright 2017 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 js is a collection of tracers written in javascript.
package js
import (
"encoding/json"
"errors"
"fmt"
"math/big"
"strings"
"sync/atomic"
"time"
"unicode"
"unsafe"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/crypto"
tracers2 "github.com/ethereum/go-ethereum/eth/tracers"
"github.com/ethereum/go-ethereum/eth/tracers/js/internal/tracers"
"github.com/ethereum/go-ethereum/log"
"gopkg.in/olebedev/go-duktape.v3"
)
// camel converts a snake cased input string into a camel cased output.
func camel(str string) string {
pieces := strings.Split(str, "_")
for i := 1; i < len(pieces); i++ {
pieces[i] = string(unicode.ToUpper(rune(pieces[i][0]))) + pieces[i][1:]
}
return strings.Join(pieces, "")
}
var assetTracers = make(map[string]string)
// init retrieves the JavaScript transaction tracers included in go-ethereum.
func init() {
for _, file := range tracers.AssetNames() {
name := camel(strings.TrimSuffix(file, ".js"))
assetTracers[name] = string(tracers.MustAsset(file))
}
tracers2.RegisterLookup(true, newJsTracer)
}
// makeSlice convert an unsafe memory pointer with the given type into a Go byte
// slice.
//
// Note, the returned slice uses the same memory area as the input arguments.
// If those are duktape stack items, popping them off **will** make the slice
// contents change.
func makeSlice(ptr unsafe.Pointer, size uint) []byte {
var sl = struct {
addr uintptr
len int
cap int
}{uintptr(ptr), int(size), int(size)}
return *(*[]byte)(unsafe.Pointer(&sl))
}
// popSlice pops a buffer off the JavaScript stack and returns it as a slice.
func popSlice(ctx *duktape.Context) []byte {
blob := common.CopyBytes(makeSlice(ctx.GetBuffer(-1)))
ctx.Pop()
return blob
}
// pushBigInt create a JavaScript BigInteger in the VM.
func pushBigInt(n *big.Int, ctx *duktape.Context) {
ctx.GetGlobalString("bigInt")
ctx.PushString(n.String())
ctx.Call(1)
}
// opWrapper provides a JavaScript wrapper around OpCode.
type opWrapper struct {
op vm.OpCode
}
// pushObject assembles a JSVM object wrapping a swappable opcode and pushes it
// onto the VM stack.
func (ow *opWrapper) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushInt(int(ow.op)); return 1 })
vm.PutPropString(obj, "toNumber")
vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushString(ow.op.String()); return 1 })
vm.PutPropString(obj, "toString")
vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushBoolean(ow.op.IsPush()); return 1 })
vm.PutPropString(obj, "isPush")
}
// memoryWrapper provides a JavaScript wrapper around vm.Memory.
type memoryWrapper struct {
memory *vm.Memory
}
// slice returns the requested range of memory as a byte slice.
func (mw *memoryWrapper) slice(begin, end int64) []byte {
if end == begin {
return []byte{}
}
if end < begin || begin < 0 {
// TODO(karalabe): We can't js-throw from Go inside duktape inside Go. The Go
// runtime goes belly up https://github.com/golang/go/issues/15639.
log.Warn("Tracer accessed out of bound memory", "offset", begin, "end", end)
return nil
}
if mw.memory.Len() < int(end) {
// TODO(karalabe): We can't js-throw from Go inside duktape inside Go. The Go
// runtime goes belly up https://github.com/golang/go/issues/15639.
log.Warn("Tracer accessed out of bound memory", "available", mw.memory.Len(), "offset", begin, "size", end-begin)
return nil
}
return mw.memory.GetCopy(begin, end-begin)
}
// getUint returns the 32 bytes at the specified address interpreted as a uint.
func (mw *memoryWrapper) getUint(addr int64) *big.Int {
if mw.memory.Len() < int(addr)+32 || addr < 0 {
// TODO(karalabe): We can't js-throw from Go inside duktape inside Go. The Go
// runtime goes belly up https://github.com/golang/go/issues/15639.
log.Warn("Tracer accessed out of bound memory", "available", mw.memory.Len(), "offset", addr, "size", 32)
return new(big.Int)
}
return new(big.Int).SetBytes(mw.memory.GetPtr(addr, 32))
}
// pushObject assembles a JSVM object wrapping a swappable memory and pushes it
// onto the VM stack.
func (mw *memoryWrapper) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
// Generate the `slice` method which takes two ints and returns a buffer
vm.PushGoFunction(func(ctx *duktape.Context) int {
blob := mw.slice(int64(ctx.GetInt(-2)), int64(ctx.GetInt(-1)))
ctx.Pop2()
ptr := ctx.PushFixedBuffer(len(blob))
copy(makeSlice(ptr, uint(len(blob))), blob)
return 1
})
vm.PutPropString(obj, "slice")
// Generate the `getUint` method which takes an int and returns a bigint
vm.PushGoFunction(func(ctx *duktape.Context) int {
offset := int64(ctx.GetInt(-1))
ctx.Pop()
pushBigInt(mw.getUint(offset), ctx)
return 1
})
vm.PutPropString(obj, "getUint")
}
// stackWrapper provides a JavaScript wrapper around vm.Stack.
type stackWrapper struct {
stack *vm.Stack
}
// peek returns the nth-from-the-top element of the stack.
func (sw *stackWrapper) peek(idx int) *big.Int {
if len(sw.stack.Data()) <= idx || idx < 0 {
// TODO(karalabe): We can't js-throw from Go inside duktape inside Go. The Go
// runtime goes belly up https://github.com/golang/go/issues/15639.
log.Warn("Tracer accessed out of bound stack", "size", len(sw.stack.Data()), "index", idx)
return new(big.Int)
}
return sw.stack.Back(idx).ToBig()
}
// pushObject assembles a JSVM object wrapping a swappable stack and pushes it
// onto the VM stack.
func (sw *stackWrapper) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushInt(len(sw.stack.Data())); return 1 })
vm.PutPropString(obj, "length")
// Generate the `peek` method which takes an int and returns a bigint
vm.PushGoFunction(func(ctx *duktape.Context) int {
offset := ctx.GetInt(-1)
ctx.Pop()
pushBigInt(sw.peek(offset), ctx)
return 1
})
vm.PutPropString(obj, "peek")
}
// dbWrapper provides a JavaScript wrapper around vm.Database.
type dbWrapper struct {
db vm.StateDB
}
// pushObject assembles a JSVM object wrapping a swappable database and pushes it
// onto the VM stack.
func (dw *dbWrapper) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
// Push the wrapper for statedb.GetBalance
vm.PushGoFunction(func(ctx *duktape.Context) int {
pushBigInt(dw.db.GetBalance(common.BytesToAddress(popSlice(ctx))), ctx)
return 1
})
vm.PutPropString(obj, "getBalance")
// Push the wrapper for statedb.GetNonce
vm.PushGoFunction(func(ctx *duktape.Context) int {
ctx.PushInt(int(dw.db.GetNonce(common.BytesToAddress(popSlice(ctx)))))
return 1
})
vm.PutPropString(obj, "getNonce")
// Push the wrapper for statedb.GetCode
vm.PushGoFunction(func(ctx *duktape.Context) int {
code := dw.db.GetCode(common.BytesToAddress(popSlice(ctx)))
ptr := ctx.PushFixedBuffer(len(code))
copy(makeSlice(ptr, uint(len(code))), code)
return 1
})
vm.PutPropString(obj, "getCode")
// Push the wrapper for statedb.GetState
vm.PushGoFunction(func(ctx *duktape.Context) int {
hash := popSlice(ctx)
addr := popSlice(ctx)
state := dw.db.GetState(common.BytesToAddress(addr), common.BytesToHash(hash))
ptr := ctx.PushFixedBuffer(len(state))
copy(makeSlice(ptr, uint(len(state))), state[:])
return 1
})
vm.PutPropString(obj, "getState")
// Push the wrapper for statedb.Exists
vm.PushGoFunction(func(ctx *duktape.Context) int {
ctx.PushBoolean(dw.db.Exist(common.BytesToAddress(popSlice(ctx))))
return 1
})
vm.PutPropString(obj, "exists")
}
// contractWrapper provides a JavaScript wrapper around vm.Contract
type contractWrapper struct {
contract *vm.Contract
}
// pushObject assembles a JSVM object wrapping a swappable contract and pushes it
// onto the VM stack.
func (cw *contractWrapper) pushObject(vm *duktape.Context) {
obj := vm.PushObject()
// Push the wrapper for contract.Caller
vm.PushGoFunction(func(ctx *duktape.Context) int {
ptr := ctx.PushFixedBuffer(20)
copy(makeSlice(ptr, 20), cw.contract.Caller().Bytes())
return 1
})
vm.PutPropString(obj, "getCaller")
// Push the wrapper for contract.Address
vm.PushGoFunction(func(ctx *duktape.Context) int {
ptr := ctx.PushFixedBuffer(20)
copy(makeSlice(ptr, 20), cw.contract.Address().Bytes())
return 1
})
vm.PutPropString(obj, "getAddress")
// Push the wrapper for contract.Value
vm.PushGoFunction(func(ctx *duktape.Context) int {
pushBigInt(cw.contract.Value(), ctx)
return 1
})
vm.PutPropString(obj, "getValue")
// Push the wrapper for contract.Input
vm.PushGoFunction(func(ctx *duktape.Context) int {
blob := cw.contract.Input
ptr := ctx.PushFixedBuffer(len(blob))
copy(makeSlice(ptr, uint(len(blob))), blob)
return 1
})
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")
}
// jsTracer provides an implementation of Tracer that evaluates a Javascript
// function for each VM execution step.
type jsTracer struct {
vm *duktape.Context // Javascript VM instance
env *vm.EVM // EVM instance executing the code being traced
tracerObject int // Stack index of the tracer JavaScript object
stateObject int // Stack index of the global state to pull arguments from
opWrapper *opWrapper // Wrapper around the VM opcode
stackWrapper *stackWrapper // Wrapper around the VM stack
memoryWrapper *memoryWrapper // Wrapper around the VM memory
contractWrapper *contractWrapper // Wrapper around the contract object
dbWrapper *dbWrapper // Wrapper around the VM environment
pcValue *uint // Swappable pc value wrapped by a log accessor
gasValue *uint // Swappable gas value wrapped by a log accessor
costValue *uint // Swappable cost value wrapped by a log accessor
depthValue *uint // Swappable depth value wrapped by a log accessor
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
interrupt uint32 // Atomic flag to signal execution interruption
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
}
// New instantiates a new tracer instance. code specifies a Javascript snippet,
// which must evaluate to an expression returning an object with 'step', 'fault'
// and 'result' functions.
func newJsTracer(code string, ctx *tracers2.Context) (tracers2.Tracer, error) {
if c, ok := assetTracers[code]; ok {
code = c
}
if ctx == nil {
ctx = new(tracers2.Context)
}
tracer := &jsTracer{
vm: duktape.New(),
ctx: make(map[string]interface{}),
opWrapper: new(opWrapper),
stackWrapper: new(stackWrapper),
memoryWrapper: new(memoryWrapper),
contractWrapper: new(contractWrapper),
dbWrapper: new(dbWrapper),
pcValue: new(uint),
gasValue: new(uint),
costValue: new(uint),
depthValue: new(uint),
refundValue: new(uint),
frame: newFrame(),
frameResult: newFrameResult(),
}
if ctx.BlockHash != (common.Hash{}) {
tracer.ctx["blockHash"] = ctx.BlockHash
if ctx.TxHash != (common.Hash{}) {
tracer.ctx["txIndex"] = ctx.TxIndex
tracer.ctx["txHash"] = ctx.TxHash
}
}
// Set up builtins for this environment
tracer.vm.PushGlobalGoFunction("toHex", func(ctx *duktape.Context) int {
ctx.PushString(hexutil.Encode(popSlice(ctx)))
return 1
})
tracer.vm.PushGlobalGoFunction("toWord", func(ctx *duktape.Context) int {
var word common.Hash
if ptr, size := ctx.GetBuffer(-1); ptr != nil {
word = common.BytesToHash(makeSlice(ptr, size))
} else {
word = common.HexToHash(ctx.GetString(-1))
}
ctx.Pop()
copy(makeSlice(ctx.PushFixedBuffer(32), 32), word[:])
return 1
})
tracer.vm.PushGlobalGoFunction("toAddress", func(ctx *duktape.Context) int {
var addr common.Address
if ptr, size := ctx.GetBuffer(-1); ptr != nil {
addr = common.BytesToAddress(makeSlice(ptr, size))
} else {
addr = common.HexToAddress(ctx.GetString(-1))
}
ctx.Pop()
copy(makeSlice(ctx.PushFixedBuffer(20), 20), addr[:])
return 1
})
tracer.vm.PushGlobalGoFunction("toContract", func(ctx *duktape.Context) int {
var from common.Address
if ptr, size := ctx.GetBuffer(-2); ptr != nil {
from = common.BytesToAddress(makeSlice(ptr, size))
} else {
from = common.HexToAddress(ctx.GetString(-2))
}
nonce := uint64(ctx.GetInt(-1))
ctx.Pop2()
contract := crypto.CreateAddress(from, nonce)
copy(makeSlice(ctx.PushFixedBuffer(20), 20), contract[:])
return 1
})
tracer.vm.PushGlobalGoFunction("toContract2", func(ctx *duktape.Context) int {
var from common.Address
if ptr, size := ctx.GetBuffer(-3); ptr != nil {
from = common.BytesToAddress(makeSlice(ptr, size))
} else {
from = common.HexToAddress(ctx.GetString(-3))
}
// Retrieve salt hex string from js stack
salt := common.HexToHash(ctx.GetString(-2))
// Retrieve code slice from js stack
var code []byte
if ptr, size := ctx.GetBuffer(-1); ptr != nil {
code = common.CopyBytes(makeSlice(ptr, size))
} else {
code = common.FromHex(ctx.GetString(-1))
}
codeHash := crypto.Keccak256(code)
ctx.Pop3()
contract := crypto.CreateAddress2(from, salt, codeHash)
copy(makeSlice(ctx.PushFixedBuffer(20), 20), contract[:])
return 1
})
tracer.vm.PushGlobalGoFunction("isPrecompiled", func(ctx *duktape.Context) int {
addr := common.BytesToAddress(popSlice(ctx))
for _, p := range tracer.activePrecompiles {
if p == addr {
ctx.PushBoolean(true)
return 1
}
}
ctx.PushBoolean(false)
return 1
})
tracer.vm.PushGlobalGoFunction("slice", func(ctx *duktape.Context) int {
start, end := ctx.GetInt(-2), ctx.GetInt(-1)
ctx.Pop2()
blob := popSlice(ctx)
size := end - start
if start < 0 || start > end || end > len(blob) {
// TODO(karalabe): We can't js-throw from Go inside duktape inside Go. The Go
// runtime goes belly up https://github.com/golang/go/issues/15639.
log.Warn("Tracer accessed out of bound memory", "available", len(blob), "offset", start, "size", size)
ctx.PushFixedBuffer(0)
return 1
}
copy(makeSlice(ctx.PushFixedBuffer(size), uint(size)), blob[start:end])
return 1
})
// Push the JavaScript tracer as object #0 onto the JSVM stack and validate it
if err := tracer.vm.PevalString("(" + code + ")"); err != nil {
log.Warn("Failed to compile tracer", "err", err)
return nil, err
}
tracer.tracerObject = 0 // yeah, nice, eval can't return the index itself
hasStep := tracer.vm.GetPropString(tracer.tracerObject, "step")
tracer.vm.Pop()
if !tracer.vm.GetPropString(tracer.tracerObject, "fault") {
return nil, fmt.Errorf("trace object must expose a function fault()")
}
tracer.vm.Pop()
if !tracer.vm.GetPropString(tracer.tracerObject, "result") {
return nil, fmt.Errorf("trace object must expose a function result()")
}
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()")
}
tracer.traceCallFrames = hasEnter && hasExit
tracer.traceSteps = hasStep
// Tracer is valid, inject the big int library to access large numbers
tracer.vm.EvalString(bigIntegerJS)
tracer.vm.PutGlobalString("bigInt")
// Push the global environment state as object #1 into the JSVM stack
tracer.stateObject = tracer.vm.PushObject()
logObject := tracer.vm.PushObject()
tracer.opWrapper.pushObject(tracer.vm)
tracer.vm.PutPropString(logObject, "op")
tracer.stackWrapper.pushObject(tracer.vm)
tracer.vm.PutPropString(logObject, "stack")
tracer.memoryWrapper.pushObject(tracer.vm)
tracer.vm.PutPropString(logObject, "memory")
tracer.contractWrapper.pushObject(tracer.vm)
tracer.vm.PutPropString(logObject, "contract")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.pcValue); return 1 })
tracer.vm.PutPropString(logObject, "getPC")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.gasValue); return 1 })
tracer.vm.PutPropString(logObject, "getGas")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.costValue); return 1 })
tracer.vm.PutPropString(logObject, "getCost")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.depthValue); return 1 })
tracer.vm.PutPropString(logObject, "getDepth")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.refundValue); return 1 })
tracer.vm.PutPropString(logObject, "getRefund")
tracer.vm.PushGoFunction(func(ctx *duktape.Context) int {
if tracer.errorValue != nil {
ctx.PushString(*tracer.errorValue)
} else {
ctx.PushUndefined()
}
return 1
})
tracer.vm.PutPropString(logObject, "getError")
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")
return tracer, nil
}
// Stop terminates execution of the tracer at the first opportune moment.
func (jst *jsTracer) Stop(err error) {
jst.reason = err
atomic.StoreUint32(&jst.interrupt, 1)
}
// call executes a method on a JS object, catching any errors, formatting and
// returning them as error objects.
func (jst *jsTracer) call(noret bool, method string, args ...string) (json.RawMessage, error) {
// Execute the JavaScript call and return any error
jst.vm.PushString(method)
for _, arg := range args {
jst.vm.GetPropString(jst.stateObject, arg)
}
code := jst.vm.PcallProp(jst.tracerObject, len(args))
defer jst.vm.Pop()
if code != 0 {
err := jst.vm.SafeToString(-1)
return nil, errors.New(err)
}
// No error occurred, extract return value and return
if noret {
return nil, nil
}
// Push a JSON marshaller onto the stack. We can't marshal from the out-
// side because duktape can crash on large nestings and we can't catch
// C++ exceptions ourselves from Go. TODO(karalabe): Yuck, why wrap?!
jst.vm.PushString("(JSON.stringify)")
jst.vm.Eval()
jst.vm.Swap(-1, -2)
if code = jst.vm.Pcall(1); code != 0 {
err := jst.vm.SafeToString(-1)
return nil, errors.New(err)
}
return json.RawMessage(jst.vm.SafeToString(-1)), nil
}
func wrapError(context string, err error) error {
return fmt.Errorf("%v in server-side tracer function '%v'", err, context)
}
// CaptureStart implements the Tracer interface to initialize the tracing operation.
func (jst *jsTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
jst.env = env
jst.ctx["type"] = "CALL"
if create {
jst.ctx["type"] = "CREATE"
}
jst.ctx["from"] = from
jst.ctx["to"] = to
jst.ctx["input"] = input
jst.ctx["gas"] = gas
jst.ctx["gasPrice"] = env.TxContext.GasPrice
jst.ctx["value"] = value
// Initialize the context
jst.ctx["block"] = env.Context.BlockNumber.Uint64()
jst.dbWrapper.db = env.StateDB
// Update list of precompiles based on current block
rules := env.ChainConfig().Rules(env.Context.BlockNumber)
jst.activePrecompiles = vm.ActivePrecompiles(rules)
// Compute intrinsic gas
isHomestead := env.ChainConfig().IsHomestead(env.Context.BlockNumber)
isIstanbul := env.ChainConfig().IsIstanbul(env.Context.BlockNumber)
intrinsicGas, err := core.IntrinsicGas(input, nil, jst.ctx["type"] == "CREATE", isHomestead, isIstanbul)
if err != nil {
return
}
jst.ctx["intrinsicGas"] = intrinsicGas
}
// CaptureState implements the Tracer interface to trace a single step of VM execution.
func (jst *jsTracer) CaptureState(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
}
// If tracing was interrupted, set the error and stop
if atomic.LoadUint32(&jst.interrupt) > 0 {
jst.err = jst.reason
jst.env.Cancel()
return
}
jst.opWrapper.op = op
jst.stackWrapper.stack = scope.Stack
jst.memoryWrapper.memory = scope.Memory
jst.contractWrapper.contract = scope.Contract
*jst.pcValue = uint(pc)
*jst.gasValue = uint(gas)
*jst.costValue = uint(cost)
*jst.depthValue = uint(depth)
*jst.refundValue = uint(jst.env.StateDB.GetRefund())
jst.errorValue = nil
if err != nil {
jst.errorValue = new(string)
*jst.errorValue = err.Error()
}
if _, err := jst.call(true, "step", "log", "db"); err != nil {
jst.err = wrapError("step", err)
}
}
// CaptureFault implements the Tracer interface to trace an execution fault
func (jst *jsTracer) CaptureFault(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, depth int, err error) {
if jst.err != nil {
return
}
// Apart from the error, everything matches the previous invocation
jst.errorValue = new(string)
*jst.errorValue = err.Error()
if _, err := jst.call(true, "fault", "log", "db"); err != nil {
jst.err = wrapError("fault", err)
}
}
// CaptureEnd is called after the call finishes to finalize the tracing.
func (jst *jsTracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) {
jst.ctx["output"] = output
jst.ctx["time"] = t.String()
jst.ctx["gasUsed"] = gasUsed
if err != nil {
jst.ctx["error"] = err.Error()
}
}
// CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct).
func (jst *jsTracer) 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 *jsTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
if !jst.traceCallFrames {
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 *jsTracer) 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 {
jst.addToObj(obj, key, val)
}
jst.vm.PutPropString(jst.stateObject, "ctx")
// Finalize the trace and return the results
result, err := jst.call(false, "result", "ctx", "db")
if err != nil {
jst.err = wrapError("result", err)
}
// Clean up the JavaScript environment
jst.vm.DestroyHeap()
jst.vm.Destroy()
return result, jst.err
}
// addToObj pushes a field to a JS object.
func (jst *jsTracer) 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))
}
}