github.com/ethereum/go-ethereum@v1.16.1/eth/tracers/native/4byte.go (about)

     1  // Copyright 2021 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package native
    18  
    19  import (
    20  	"encoding/json"
    21  	"math/big"
    22  	"strconv"
    23  	"sync/atomic"
    24  
    25  	"github.com/ethereum/go-ethereum/common"
    26  	"github.com/ethereum/go-ethereum/core/tracing"
    27  	"github.com/ethereum/go-ethereum/core/types"
    28  	"github.com/ethereum/go-ethereum/core/vm"
    29  	"github.com/ethereum/go-ethereum/eth/tracers"
    30  	"github.com/ethereum/go-ethereum/params"
    31  )
    32  
    33  func init() {
    34  	tracers.DefaultDirectory.Register("4byteTracer", newFourByteTracer, false)
    35  }
    36  
    37  // fourByteTracer searches for 4byte-identifiers, and collects them for post-processing.
    38  // It collects the methods identifiers along with the size of the supplied data, so
    39  // a reversed signature can be matched against the size of the data.
    40  //
    41  // Example:
    42  //
    43  //	> debug.traceTransaction( "0x214e597e35da083692f5386141e69f47e973b2c56e7a8073b1ea08fd7571e9de", {tracer: "4byteTracer"})
    44  //	{
    45  //	  0x27dc297e-128: 1,
    46  //	  0x38cc4831-0: 2,
    47  //	  0x524f3889-96: 1,
    48  //	  0xadf59f99-288: 1,
    49  //	  0xc281d19e-0: 1
    50  //	}
    51  type fourByteTracer struct {
    52  	ids               map[string]int // ids aggregates the 4byte ids found
    53  	interrupt         atomic.Bool    // Atomic flag to signal execution interruption
    54  	reason            error          // Textual reason for the interruption
    55  	chainConfig       *params.ChainConfig
    56  	activePrecompiles []common.Address // Updated on tx start based on given rules
    57  }
    58  
    59  // newFourByteTracer returns a native go tracer which collects
    60  // 4 byte-identifiers of a tx, and implements vm.EVMLogger.
    61  func newFourByteTracer(ctx *tracers.Context, cfg json.RawMessage, chainConfig *params.ChainConfig) (*tracers.Tracer, error) {
    62  	t := &fourByteTracer{
    63  		ids:         make(map[string]int),
    64  		chainConfig: chainConfig,
    65  	}
    66  	return &tracers.Tracer{
    67  		Hooks: &tracing.Hooks{
    68  			OnTxStart: t.OnTxStart,
    69  			OnEnter:   t.OnEnter,
    70  		},
    71  		GetResult: t.GetResult,
    72  		Stop:      t.Stop,
    73  	}, nil
    74  }
    75  
    76  // isPrecompiled returns whether the addr is a precompile. Logic borrowed from newJsTracer in eth/tracers/js/tracer.go
    77  func (t *fourByteTracer) isPrecompiled(addr common.Address) bool {
    78  	for _, p := range t.activePrecompiles {
    79  		if p == addr {
    80  			return true
    81  		}
    82  	}
    83  	return false
    84  }
    85  
    86  // store saves the given identifier and datasize.
    87  func (t *fourByteTracer) store(id []byte, size int) {
    88  	key := bytesToHex(id) + "-" + strconv.Itoa(size)
    89  	t.ids[key] += 1
    90  }
    91  
    92  func (t *fourByteTracer) OnTxStart(env *tracing.VMContext, tx *types.Transaction, from common.Address) {
    93  	// Update list of precompiles based on current block
    94  	rules := t.chainConfig.Rules(env.BlockNumber, env.Random != nil, env.Time)
    95  	t.activePrecompiles = vm.ActivePrecompiles(rules)
    96  }
    97  
    98  // OnEnter is called when EVM enters a new scope (via call, create or selfdestruct).
    99  func (t *fourByteTracer) OnEnter(depth int, opcode byte, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
   100  	// Skip if tracing was interrupted
   101  	if t.interrupt.Load() {
   102  		return
   103  	}
   104  	if len(input) < 4 {
   105  		return
   106  	}
   107  	op := vm.OpCode(opcode)
   108  	// primarily we want to avoid CREATE/CREATE2/SELFDESTRUCT
   109  	if op != vm.DELEGATECALL && op != vm.STATICCALL &&
   110  		op != vm.CALL && op != vm.CALLCODE {
   111  		return
   112  	}
   113  	// Skip any pre-compile invocations, those are just fancy opcodes
   114  	if t.isPrecompiled(to) {
   115  		return
   116  	}
   117  	t.store(input[0:4], len(input)-4)
   118  }
   119  
   120  // GetResult returns the json-encoded nested list of call traces, and any
   121  // error arising from the encoding or forceful termination (via `Stop`).
   122  func (t *fourByteTracer) GetResult() (json.RawMessage, error) {
   123  	res, err := json.Marshal(t.ids)
   124  	if err != nil {
   125  		return nil, err
   126  	}
   127  	return res, t.reason
   128  }
   129  
   130  // Stop terminates execution of the tracer at the first opportune moment.
   131  func (t *fourByteTracer) Stop(err error) {
   132  	t.reason = err
   133  	t.interrupt.Store(true)
   134  }
   135  
   136  func bytesToHex(s []byte) string {
   137  	return "0x" + common.Bytes2Hex(s)
   138  }