github.com/haliliceylan/bsc@v1.1.10-0.20220501224556-eb78d644ebcb/tests/fuzzers/difficulty/difficulty-fuzz.go (about)

     1  // Copyright 2020 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 difficulty
    18  
    19  import (
    20  	"bytes"
    21  	"encoding/binary"
    22  	"fmt"
    23  	"io"
    24  	"math/big"
    25  
    26  	"github.com/ethereum/go-ethereum/consensus/ethash"
    27  	"github.com/ethereum/go-ethereum/core/types"
    28  )
    29  
    30  type fuzzer struct {
    31  	input     io.Reader
    32  	exhausted bool
    33  	debugging bool
    34  }
    35  
    36  func (f *fuzzer) read(size int) []byte {
    37  	out := make([]byte, size)
    38  	if _, err := f.input.Read(out); err != nil {
    39  		f.exhausted = true
    40  	}
    41  	return out
    42  }
    43  
    44  func (f *fuzzer) readSlice(min, max int) []byte {
    45  	var a uint16
    46  	binary.Read(f.input, binary.LittleEndian, &a)
    47  	size := min + int(a)%(max-min)
    48  	out := make([]byte, size)
    49  	if _, err := f.input.Read(out); err != nil {
    50  		f.exhausted = true
    51  	}
    52  	return out
    53  }
    54  
    55  func (f *fuzzer) readUint64(min, max uint64) uint64 {
    56  	if min == max {
    57  		return min
    58  	}
    59  	var a uint64
    60  	if err := binary.Read(f.input, binary.LittleEndian, &a); err != nil {
    61  		f.exhausted = true
    62  	}
    63  	a = min + a%(max-min)
    64  	return a
    65  }
    66  func (f *fuzzer) readBool() bool {
    67  	return f.read(1)[0]&0x1 == 0
    68  }
    69  
    70  // The function must return
    71  // 1 if the fuzzer should increase priority of the
    72  //    given input during subsequent fuzzing (for example, the input is lexically
    73  //    correct and was parsed successfully);
    74  // -1 if the input must not be added to corpus even if gives new coverage; and
    75  // 0  otherwise
    76  // other values are reserved for future use.
    77  func Fuzz(data []byte) int {
    78  	f := fuzzer{
    79  		input:     bytes.NewReader(data),
    80  		exhausted: false,
    81  	}
    82  	return f.fuzz()
    83  }
    84  
    85  var minDifficulty = big.NewInt(0x2000)
    86  
    87  type calculator func(time uint64, parent *types.Header) *big.Int
    88  
    89  func (f *fuzzer) fuzz() int {
    90  	// A parent header
    91  	header := &types.Header{}
    92  	if f.readBool() {
    93  		header.UncleHash = types.EmptyUncleHash
    94  	}
    95  	// Difficulty can range between 0x2000 (2 bytes) and up to 32 bytes
    96  	{
    97  		diff := new(big.Int).SetBytes(f.readSlice(2, 32))
    98  		if diff.Cmp(minDifficulty) < 0 {
    99  			diff.Set(minDifficulty)
   100  		}
   101  		header.Difficulty = diff
   102  	}
   103  	// Number can range between 0 and up to 32 bytes (but not so that the child exceeds it)
   104  	{
   105  		// However, if we use astronomic numbers, then the bomb exp karatsuba calculation
   106  		// in the legacy methods)
   107  		// times out, so we limit it to fit within reasonable bounds
   108  		number := new(big.Int).SetBytes(f.readSlice(0, 4)) // 4 bytes: 32 bits: block num max 4 billion
   109  		header.Number = number
   110  	}
   111  	// Both parent and child time must fit within uint64
   112  	var time uint64
   113  	{
   114  		childTime := f.readUint64(1, 0xFFFFFFFFFFFFFFFF)
   115  		//fmt.Printf("childTime: %x\n",childTime)
   116  		delta := f.readUint64(1, childTime)
   117  		//fmt.Printf("delta: %v\n", delta)
   118  		pTime := childTime - delta
   119  		header.Time = pTime
   120  		time = childTime
   121  	}
   122  	// Bomb delay will never exceed uint64
   123  	bombDelay := new(big.Int).SetUint64(f.readUint64(1, 0xFFFFFFFFFFFFFFFe))
   124  
   125  	if f.exhausted {
   126  		return 0
   127  	}
   128  
   129  	for i, pair := range []struct {
   130  		bigFn  calculator
   131  		u256Fn calculator
   132  	}{
   133  		{ethash.FrontierDifficultyCalulator, ethash.CalcDifficultyFrontierU256},
   134  		{ethash.HomesteadDifficultyCalulator, ethash.CalcDifficultyHomesteadU256},
   135  		{ethash.DynamicDifficultyCalculator(bombDelay), ethash.MakeDifficultyCalculatorU256(bombDelay)},
   136  	} {
   137  		want := pair.bigFn(time, header)
   138  		have := pair.u256Fn(time, header)
   139  		if want.Cmp(have) != 0 {
   140  			panic(fmt.Sprintf("pair %d: want %x have %x\nparent.Number: %x\np.Time: %x\nc.Time: %x\nBombdelay: %v\n", i, want, have,
   141  				header.Number, header.Time, time, bombDelay))
   142  		}
   143  	}
   144  	return 1
   145  }