path: root/params/config.go

// Copyright 2016 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 params

import (
    "fmt"
    "math/big"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/common/math"
)

// Genesis hashes to enforce below configs on.
var (
    MainnetGenesisHash = common.HexToHash("0x81abe3e66f63afe3806b64e7529d2a3f2ae9be7ba3e6fca2a561808bf7875a03")
    TestnetGenesisHash = common.HexToHash("0x3fe7a48aca63addc5e502fe60a37a865b454c649e106d07d3cd810e086e1fc6d")
)

var (
    // MainnetChainConfig is the chain parameters to run a node on the main network.
    MainnetChainConfig = &ChainConfig{
        ChainID:             big.NewInt(237),
        HomesteadBlock:      big.NewInt(0),
        DAOForkBlock:        big.NewInt(0),
        DAOForkSupport:      true,
        EIP150Block:         big.NewInt(0),
        EIP150Hash:          common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000000"),
        EIP155Block:         big.NewInt(0),
        EIP158Block:         big.NewInt(0),
        ByzantiumBlock:      big.NewInt(0),
        ConstantinopleBlock: big.NewInt(0),
        PetersburgBlock:     big.NewInt(0),
        Dexcon: &DexconConfig{
            GenesisCRSText:   "In DEXON, we trust.",
            Owner:            common.HexToAddress("BF8C48A620bacc46907f9B89732D25E47A2D7Cf7"),
            MinStake:         new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            LockupPeriod:     86400 * 3 * 1000,
            BlockReward:      big.NewInt(1e18),
            BlockGasLimit:    40000000,
            NumChains:        4,
            LambdaBA:         250,
            LambdaDKG:        2500,
            K:                0,
            PhiRatio:         0.667,
            NotarySetSize:    4,
            DKGSetSize:       4,
            RoundInterval:    600000,
            MinBlockInterval: 900,
            FineValues: []*big.Int{
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            },
        },
    }

    // MainnetTrustedCheckpoint contains the light client trusted checkpoint for the main network.
    MainnetTrustedCheckpoint = &TrustedCheckpoint{
        Name:         "mainnet",
        SectionIndex: 216,
        SectionHead:  common.HexToHash("0xae3e551c8d60d06fd411a8e6008e90625d3bb0cbbf664b65d5ed90b318553541"),
        CHTRoot:      common.HexToHash("0xeea7d2ab3545a37deecc66fc43c9556ae337c3ea1c6893e401428207bdb8e434"),
        BloomRoot:    common.HexToHash("0xb0d4176d160d67b99a9f963281e52bce0583a566b74b4497fe3ed24ae04004ff"),
    }

    // TestnetChainConfig contains the chain parameters to run a node on the Taiwan test network.
    TestnetChainConfig = &ChainConfig{
        ChainID:             big.NewInt(238),
        HomesteadBlock:      big.NewInt(0),
        DAOForkBlock:        nil,
        DAOForkSupport:      true,
        EIP150Block:         big.NewInt(0),
        EIP155Block:         big.NewInt(0),
        EIP158Block:         big.NewInt(0),
        ByzantiumBlock:      big.NewInt(0),
        ConstantinopleBlock: big.NewInt(0),
        PetersburgBlock:     big.NewInt(0),
        Dexcon: &DexconConfig{
            GenesisCRSText:   "In DEXON, we trust.",
            Owner:            common.HexToAddress("BF8C48A620bacc46907f9B89732D25E47A2D7Cf7"),
            MinStake:         new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            LockupPeriod:     86400 * 3 * 1000,
            BlockReward:      big.NewInt(1e18),
            BlockGasLimit:    40000000,
            NumChains:        6,
            LambdaBA:         250,
            LambdaDKG:        2500,
            K:                0,
            PhiRatio:         0.667,
            NotarySetSize:    4,
            DKGSetSize:       4,
            RoundInterval:    600000,
            MinBlockInterval: 900,
            FineValues: []*big.Int{
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            },
        },
    }

    // TaipeiChainConfig contains the chain parameters to run a node on the Taipei test network.
    TaipeiChainConfig = &ChainConfig{
        ChainID:             big.NewInt(239),
        HomesteadBlock:      big.NewInt(0),
        DAOForkBlock:        nil,
        DAOForkSupport:      true,
        EIP150Block:         big.NewInt(0),
        EIP155Block:         big.NewInt(0),
        EIP158Block:         big.NewInt(0),
        ByzantiumBlock:      big.NewInt(0),
        ConstantinopleBlock: big.NewInt(0),
        PetersburgBlock:     big.NewInt(0),
        Dexcon: &DexconConfig{
            GenesisCRSText:   "In DEXON, we trust.",
            Owner:            common.HexToAddress("BF8C48A620bacc46907f9B89732D25E47A2D7Cf7"),
            MinStake:         new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            LockupPeriod:     86400 * 3 * 1000,
            BlockReward:      big.NewInt(1e18),
            BlockGasLimit:    40000000,
            NumChains:        6,
            LambdaBA:         400,
            LambdaDKG:        10000,
            K:                0,
            PhiRatio:         0.667,
            NotarySetSize:    21,
            DKGSetSize:       13,
            RoundInterval:    3600000,
            MinBlockInterval: 900,
            FineValues: []*big.Int{
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e4)),
                new(big.Int).Mul(big.NewInt(1e18), big.NewInt(1e5)),
            },
        },
    }

    // TestnetTrustedCheckpoint contains the light client trusted checkpoint for the Ropsten test network.
    TestnetTrustedCheckpoint = &TrustedCheckpoint{
        Name:         "testnet",
        SectionIndex: 148,
        SectionHead:  common.HexToHash("0x4d3181bedb6aa96a6f3efa866c71f7802400d0fb4a6906946c453630d850efc0"),
        CHTRoot:      common.HexToHash("0x25df2f9d63a5f84b2852988f0f0f7af5a7877da061c11b85c812780b5a27a5ec"),
        BloomRoot:    common.HexToHash("0x0584834e5222471a06c669d210e302ca602780eaaddd04634fd65471c2a91419"),
    }

    // AllEthashProtocolChanges contains every protocol change (EIPs) introduced
    // and accepted by the Ethereum core developers into the Ethash consensus.
    //
    // This configuration is intentionally not using keyed fields to force anyone
    // adding flags to the config to also have to set these fields.
    AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}

    // AllCliqueProtocolChanges contains every protocol change (EIPs) introduced
    // and accepted by the Ethereum core developers into the Clique consensus.
    //
    // This configuration is intentionally not using keyed fields to force anyone
    // adding flags to the config to also have to set these fields.
    AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}, nil}

    AllDexconProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, new(DexconConfig)}

    TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}
    TestRules       = TestChainConfig.Rules(new(big.Int))

    // Ethereum MainnetChainConfig is the chain parameters to run a node on the main network.
    EthereumMainnetChainConfig = &ChainConfig{
        ChainID:             big.NewInt(1),
        HomesteadBlock:      big.NewInt(1150000),
        DAOForkBlock:        big.NewInt(1920000),
        DAOForkSupport:      true,
        EIP150Block:         big.NewInt(2463000),
        EIP150Hash:          common.HexToHash("0x2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0"),
        EIP155Block:         big.NewInt(2675000),
        EIP158Block:         big.NewInt(2675000),
        ByzantiumBlock:      big.NewInt(4370000),
        ConstantinopleBlock: nil,
        Ethash:              new(EthashConfig),
    }

    // Ethereum TestnetChainConfig contains the chain parameters to run a node on the Ropsten test network.
    EthereumTestnetChainConfig = &ChainConfig{
        ChainID:             big.NewInt(3),
        HomesteadBlock:      big.NewInt(0),
        DAOForkBlock:        nil,
        DAOForkSupport:      true,
        EIP150Block:         big.NewInt(0),
        EIP150Hash:          common.HexToHash("0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d"),
        EIP155Block:         big.NewInt(10),
        EIP158Block:         big.NewInt(10),
        ByzantiumBlock:      big.NewInt(1700000),
        ConstantinopleBlock: big.NewInt(4230000),
        Ethash:              new(EthashConfig),
    }
)

// TrustedCheckpoint represents a set of post-processed trie roots (CHT and
// BloomTrie) associated with the appropriate section index and head hash. It is
// used to start light syncing from this checkpoint and avoid downloading the
// entire header chain while still being able to securely access old headers/logs.
type TrustedCheckpoint struct {
    Name         string      `json:"-"`
    SectionIndex uint64      `json:"sectionIndex"`
    SectionHead  common.Hash `json:"sectionHead"`
    CHTRoot      common.Hash `json:"chtRoot"`
    BloomRoot    common.Hash `json:"bloomRoot"`
}

// ChainConfig is the core config which determines the blockchain settings.
//
// ChainConfig is stored in the database on a per block basis. This means
// that any network, identified by its genesis block, can have its own
// set of configuration options.
type ChainConfig struct {
    ChainID *big.Int `json:"chainId"` // chainId identifies the current chain and is used for replay protection

    HomesteadBlock *big.Int `json:"homesteadBlock,omitempty"` // Homestead switch block (nil = no fork, 0 = already homestead)

    DAOForkBlock   *big.Int `json:"daoForkBlock,omitempty"`   // TheDAO hard-fork switch block (nil = no fork)
    DAOForkSupport bool     `json:"daoForkSupport,omitempty"` // Whether the nodes supports or opposes the DAO hard-fork

    // EIP150 implements the Gas price changes (https://github.com/ethereum/EIPs/issues/150)
    EIP150Block *big.Int    `json:"eip150Block,omitempty"` // EIP150 HF block (nil = no fork)
    EIP150Hash  common.Hash `json:"eip150Hash,omitempty"`  // EIP150 HF hash (needed for header only clients as only gas pricing changed)

    EIP155Block *big.Int `json:"eip155Block,omitempty"` // EIP155 HF block
    EIP158Block *big.Int `json:"eip158Block,omitempty"` // EIP158 HF block

    ByzantiumBlock      *big.Int `json:"byzantiumBlock,omitempty"`      // Byzantium switch block (nil = no fork, 0 = already on byzantium)
    ConstantinopleBlock *big.Int `json:"constantinopleBlock,omitempty"` // Constantinople switch block (nil = no fork, 0 = already activated)
    PetersburgBlock     *big.Int `json:"petersburgBlock,omitempty"`     // Petersburg switch block (nil = same as Constantinople)
    EWASMBlock          *big.Int `json:"ewasmBlock,omitempty"`          // EWASM switch block (nil = no fork, 0 = already activated)

    // Various consensus engines
    Ethash *EthashConfig `json:"ethash,omitempty"`
    Clique *CliqueConfig `json:"clique,omitempty"`
    Dexcon *DexconConfig `json:"dexcon,omitempty"`
}

// EthashConfig is the consensus engine configs for proof-of-work based sealing.
type EthashConfig struct{}

// String implements the stringer interface, returning the consensus engine details.
func (c *EthashConfig) String() string {
    return "ethash"
}

// CliqueConfig is the consensus engine configs for proof-of-authority based sealing.
type CliqueConfig struct {
    Period uint64 `json:"period"` // Number of seconds between blocks to enforce
    Epoch  uint64 `json:"epoch"`  // Epoch length to reset votes and checkpoint
}

// String implements the stringer interface, returning the consensus engine details.
func (c *CliqueConfig) String() string {
    return "clique"
}

//go:generate gencodec -type DexconConfig -field-override dexconConfigSpecMarshaling -out gen_dexcon_config.go

// DexconConfig is the consensus engine configs for DEXON consensus.
type DexconConfig struct {
    GenesisCRSText   string         `json:"genesisCRSText"`
    Owner            common.Address `json:"owner"`
    MinStake         *big.Int       `json:"minStake"`
    LockupPeriod     uint64         `json:"lockupPeriod"`
    BlockReward      *big.Int       `json:"blockReward"`
    BlockGasLimit    uint64         `json:"blockGasLimit"`
    NumChains        uint32         `json:"numChains"`
    LambdaBA         uint64         `json:"lambdaBA"`
    LambdaDKG        uint64         `json:"lambdaDKG"`
    K                uint32         `json:"k"`
    PhiRatio         float32        `json:"phiRatio"`
    NotarySetSize    uint32         `json:"notarySetSize"`
    DKGSetSize       uint32         `json:"dkgSetSize"`
    RoundInterval    uint64         `json:"roundInterval"`
    MinBlockInterval uint64         `json:"minBlockInterval"`
    FineValues       []*big.Int     `json:"fineValues"`
}

type dexconConfigSpecMarshaling struct {
    MinStake    *math.HexOrDecimal256
    BlockReward *math.HexOrDecimal256
    FineValues  []*math.HexOrDecimal256
}

// String implements the stringer interface, returning the consensus engine details.
func (d *DexconConfig) String() string {
    return fmt.Sprintf("{GenesisCRSText: %v Owner: %v MinStake: %v LockupPeriod: %v BlockReward: %v BlockGasLimit: %v NumChains: %v LambdaBA: %v LambdaDKG: %v K: %v PhiRatio: %v NotarySetSize: %v DKGSetSize: %v RoundInterval: %v MinBlockInterval: %v FineValues: %v}",
        d.GenesisCRSText,
        d.Owner,
        d.MinStake,
        d.LockupPeriod,
        d.BlockReward,
        d.BlockGasLimit,
        d.NumChains,
        d.LambdaBA,
        d.LambdaDKG,
        d.K,
        d.PhiRatio,
        d.NotarySetSize,
        d.DKGSetSize,
        d.RoundInterval,
        d.MinBlockInterval,
        d.FineValues,
    )
}

// String implements the fmt.Stringer interface.
func (c *ChainConfig) String() string {
    var engine interface{}
    switch {
    case c.Ethash != nil:
        engine = c.Ethash
    case c.Clique != nil:
        engine = c.Clique
    default:
        engine = "unknown"
    }
    return fmt.Sprintf("{ChainID: %v Homestead: %v DAO: %v DAOSupport: %v EIP150: %v EIP155: %v EIP158: %v Byzantium: %v Constantinople: %v  ConstantinopleFix: %v Engine: %v}",
        c.ChainID,
        c.HomesteadBlock,
        c.DAOForkBlock,
        c.DAOForkSupport,
        c.EIP150Block,
        c.EIP155Block,
        c.EIP158Block,
        c.ByzantiumBlock,
        c.ConstantinopleBlock,
        c.PetersburgBlock,
        engine,
    )
}

// IsHomestead returns whether num is either equal to the homestead block or greater.
func (c *ChainConfig) IsHomestead(num *big.Int) bool {
    return isForked(c.HomesteadBlock, num)
}

// IsDAOFork returns whether num is either equal to the DAO fork block or greater.
func (c *ChainConfig) IsDAOFork(num *big.Int) bool {
    return isForked(c.DAOForkBlock, num)
}

// IsEIP150 returns whether num is either equal to the EIP150 fork block or greater.
func (c *ChainConfig) IsEIP150(num *big.Int) bool {
    return isForked(c.EIP150Block, num)
}

// IsEIP155 returns whether num is either equal to the EIP155 fork block or greater.
func (c *ChainConfig) IsEIP155(num *big.Int) bool {
    return isForked(c.EIP155Block, num)
}

// IsEIP158 returns whether num is either equal to the EIP158 fork block or greater.
func (c *ChainConfig) IsEIP158(num *big.Int) bool {
    return isForked(c.EIP158Block, num)
}

// IsByzantium returns whether num is either equal to the Byzantium fork block or greater.
func (c *ChainConfig) IsByzantium(num *big.Int) bool {
    return isForked(c.ByzantiumBlock, num)
}

// IsConstantinople returns whether num is either equal to the Constantinople fork block or greater.
func (c *ChainConfig) IsConstantinople(num *big.Int) bool {
    return isForked(c.ConstantinopleBlock, num)
}

// IsPetersburg returns whether num is either
// - equal to or greater than the PetersburgBlock fork block,
// - OR is nil, and Constantinople is active
func (c *ChainConfig) IsPetersburg(num *big.Int) bool {
    return isForked(c.PetersburgBlock, num) || c.PetersburgBlock == nil && isForked(c.ConstantinopleBlock, num)
}

// IsEWASM returns whether num represents a block number after the EWASM fork
func (c *ChainConfig) IsEWASM(num *big.Int) bool {
    return isForked(c.EWASMBlock, num)
}

// GasTable returns the gas table corresponding to the current phase (homestead or homestead reprice).
//
// The returned GasTable's fields shouldn't, under any circumstances, be changed.
func (c *ChainConfig) GasTable(num *big.Int) GasTable {
    if num == nil {
        return GasTableHomestead
    }
    switch {
    case c.IsConstantinople(num):
        return GasTableConstantinople
    case c.IsEIP158(num):
        return GasTableEIP158
    case c.IsEIP150(num):
        return GasTableEIP150
    default:
        return GasTableHomestead
    }
}

// CheckCompatible checks whether scheduled fork transitions have been imported
// with a mismatching chain configuration.
func (c *ChainConfig) CheckCompatible(newcfg *ChainConfig, height uint64) *ConfigCompatError {
    bhead := new(big.Int).SetUint64(height)

    // Iterate checkCompatible to find the lowest conflict.
    var lasterr *ConfigCompatError
    for {
        err := c.checkCompatible(newcfg, bhead)
        if err == nil || (lasterr != nil && err.RewindTo == lasterr.RewindTo) {
            break
        }
        lasterr = err
        bhead.SetUint64(err.RewindTo)
    }
    return lasterr
}

func (c *ChainConfig) checkCompatible(newcfg *ChainConfig, head *big.Int) *ConfigCompatError {
    if isForkIncompatible(c.HomesteadBlock, newcfg.HomesteadBlock, head) {
        return newCompatError("Homestead fork block", c.HomesteadBlock, newcfg.HomesteadBlock)
    }
    if isForkIncompatible(c.DAOForkBlock, newcfg.DAOForkBlock, head) {
        return newCompatError("DAO fork block", c.DAOForkBlock, newcfg.DAOForkBlock)
    }
    if c.IsDAOFork(head) && c.DAOForkSupport != newcfg.DAOForkSupport {
        return newCompatError("DAO fork support flag", c.DAOForkBlock, newcfg.DAOForkBlock)
    }
    if isForkIncompatible(c.EIP150Block, newcfg.EIP150Block, head) {
        return newCompatError("EIP150 fork block", c.EIP150Block, newcfg.EIP150Block)
    }
    if isForkIncompatible(c.EIP155Block, newcfg.EIP155Block, head) {
        return newCompatError("EIP155 fork block", c.EIP155Block, newcfg.EIP155Block)
    }
    if isForkIncompatible(c.EIP158Block, newcfg.EIP158Block, head) {
        return newCompatError("EIP158 fork block", c.EIP158Block, newcfg.EIP158Block)
    }
    if c.IsEIP158(head) && !configNumEqual(c.ChainID, newcfg.ChainID) {
        return newCompatError("EIP158 chain ID", c.EIP158Block, newcfg.EIP158Block)
    }
    if isForkIncompatible(c.ByzantiumBlock, newcfg.ByzantiumBlock, head) {
        return newCompatError("Byzantium fork block", c.ByzantiumBlock, newcfg.ByzantiumBlock)
    }
    if isForkIncompatible(c.ConstantinopleBlock, newcfg.ConstantinopleBlock, head) {
        return newCompatError("Constantinople fork block", c.ConstantinopleBlock, newcfg.ConstantinopleBlock)
    }
    if isForkIncompatible(c.PetersburgBlock, newcfg.PetersburgBlock, head) {
        return newCompatError("ConstantinopleFix fork block", c.PetersburgBlock, newcfg.PetersburgBlock)
    }
    if isForkIncompatible(c.EWASMBlock, newcfg.EWASMBlock, head) {
        return newCompatError("ewasm fork block", c.EWASMBlock, newcfg.EWASMBlock)
    }
    return nil
}

// isForkIncompatible returns true if a fork scheduled at s1 cannot be rescheduled to
// block s2 because head is already past the fork.
func isForkIncompatible(s1, s2, head *big.Int) bool {
    return (isForked(s1, head) || isForked(s2, head)) && !configNumEqual(s1, s2)
}

// isForked returns whether a fork scheduled at block s is active at the given head block.
func isForked(s, head *big.Int) bool {
    if s == nil || head == nil {
        return false
    }

    return s.Cmp(head) <= 0
}

func configNumEqual(x, y *big.Int) bool {
    if x == nil {
        return y == nil
    }
    if y == nil {
        return x == nil
    }
    return x.Cmp(y) == 0
}

// ConfigCompatError is raised if the locally-stored blockchain is initialised with a
// ChainConfig that would alter the past.
type ConfigCompatError struct {
    What string
    // block numbers of the stored and new configurations
    StoredConfig, NewConfig *big.Int
    // the block number to which the local chain must be rewound to correct the error
    RewindTo uint64
}

func newCompatError(what string, storedblock, newblock *big.Int) *ConfigCompatError {
    var rew *big.Int
    switch {
    case storedblock == nil:
        rew = newblock
    case newblock == nil || storedblock.Cmp(newblock) < 0:
        rew = storedblock
    default:
        rew = newblock
    }
    err := &ConfigCompatError{what, storedblock, newblock, 0}
    if rew != nil && rew.Sign() > 0 {
        err.RewindTo = rew.Uint64() - 1
    }
    return err
}

func (err *ConfigCompatError) Error() string {
    return fmt.Sprintf("mismatching %s in database (have %d, want %d, rewindto %d)", err.What, err.StoredConfig, err.NewConfig, err.RewindTo)
}

// Rules wraps ChainConfig and is merely syntactic sugar or can be used for functions
// that do not have or require information about the block.
//
// Rules is a one time interface meaning that it shouldn't be used in between transition
// phases.
type Rules struct {
    ChainID                                     *big.Int
    IsHomestead, IsEIP150, IsEIP155, IsEIP158   bool
    IsByzantium, IsConstantinople, IsPetersburg bool
}

// Rules ensures c's ChainID is not nil.
func (c *ChainConfig) Rules(num *big.Int) Rules {
    chainID := c.ChainID
    if chainID == nil {
        chainID = new(big.Int)
    }
    return Rules{
        ChainID:          new(big.Int).Set(chainID),
        IsHomestead:      c.IsHomestead(num),
        IsEIP150:         c.IsEIP150(num),
        IsEIP155:         c.IsEIP155(num),
        IsEIP158:         c.IsEIP158(num),
        IsByzantium:      c.IsByzantium(num),
        IsConstantinople: c.IsConstantinople(num),
        IsPetersburg:     c.IsPetersburg(num),
    }
}