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 (
	"encoding/binary"
	"fmt"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"golang.org/x/crypto/sha3"
)

// 主链和测试链的创世块哈希

// Genesis hashes to enforce below configs on.
var (
	MainnetGenesisHash = common.HexToHash("0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3")
	RopstenGenesisHash = common.HexToHash("0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d")
	SepoliaGenesisHash = common.HexToHash("0x25a5cc106eea7138acab33231d7160d69cb777ee0c2c553fcddf5138993e6dd9")
	RinkebyGenesisHash = common.HexToHash("0x6341fd3daf94b748c72ced5a5b26028f2474f5f00d824504e4fa37a75767e177")
	GoerliGenesisHash  = common.HexToHash("0xbf7e331f7f7c1dd2e05159666b3bf8bc7a8a3a9eb1d518969eab529dd9b88c1a")
)

//不同链对应的创世哈希对应的创世检查点映射（类比创世区块的定义）

// TrustedCheckpoints associates each known checkpoint with the genesis hash of
// the chain it belongs to.
var TrustedCheckpoints = map[common.Hash]*TrustedCheckpoint{
	MainnetGenesisHash: MainnetTrustedCheckpoint,
	RopstenGenesisHash: RopstenTrustedCheckpoint,
	SepoliaGenesisHash: SepoliaTrustedCheckpoint,
	RinkebyGenesisHash: RinkebyTrustedCheckpoint,
	GoerliGenesisHash:  GoerliTrustedCheckpoint,
}

//创世哈希对应的检查点预言机

// CheckpointOracles associates each known checkpoint oracles with the genesis hash of
// the chain it belongs to.
var CheckpointOracles = map[common.Hash]*CheckpointOracleConfig{
	MainnetGenesisHash: MainnetCheckpointOracle,
	RopstenGenesisHash: RopstenCheckpointOracle,
	RinkebyGenesisHash: RinkebyCheckpointOracle,
	GoerliGenesisHash:  GoerliCheckpointOracle,
}

var (
	// MainnetChainConfig is the chain parameters to run a node on the main network.
	MainnetChainConfig = &ChainConfig{
		ChainID:             big.NewInt(1),         //EIP-155 提出的防止重放攻击
		HomesteadBlock:      big.NewInt(1_150_000), //以太坊 homestead 版本硬分叉高度，因为共识机制变更
		DAOForkBlock:        big.NewInt(1_920_000), //DAO 攻击硬分叉
		DAOForkSupport:      true,                  //客户端是否接受 DAO 硬分叉
		EIP150Block:         big.NewInt(2_463_000), //EIP-150,为解决拒绝服务攻击，提高 IO 操作相关的 Gas。
		EIP150Hash:          common.HexToHash("0x2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0"),
		EIP155Block:         big.NewInt(2_675_000),  //应用 EIP-155 的区块高度
		EIP158Block:         big.NewInt(2_675_000),  //应用 EIP-158 的区块高度
		ByzantiumBlock:      big.NewInt(4_370_000),  //Byzantium的硬分叉
		ConstantinopleBlock: big.NewInt(7_280_000),  //君士坦丁堡版本启用区块高度，增加 EIP-145 按位移位、EIP-1014 创建时地址加盐、EIP-1052 增加提取字节码哈希值的操作码、EIP-1283 优化操作码 SSTORE 的 gas 计算方式、EIP-1234 推迟难度炸弹
		PetersburgBlock:     big.NewInt(7_280_000),  //彼得斯堡版本启用区块高度,EIP-1283 可能存在代码漏洞，因此进行硬分叉
		IstanbulBlock:       big.NewInt(9_069_000),  //Istanbul 版本启用区块
		MuirGlacierBlock:    big.NewInt(9_200_000),  //EIP-2384 难度炸弹推迟
		BerlinBlock:         big.NewInt(12_244_000), //Berlin 版本启用区块
		LondonBlock:         big.NewInt(12_965_000), //London 版本启用区块
		ArrowGlacierBlock:   big.NewInt(13_773_000), //EIP-4345 难度炸弹推迟
		Ethash:              new(EthashConfig),
	}

	// MainnetTrustedCheckpoint contains the light client trusted checkpoint for the main network.
	MainnetTrustedCheckpoint = &TrustedCheckpoint{
		SectionIndex: 413,
		SectionHead:  common.HexToHash("0x8aa8e64ceadcdc5f23bc41d2acb7295a261a5cf680bb00a34f0e01af08200083"),
		CHTRoot:      common.HexToHash("0x008af584d385a2610706c5a439d39f15ddd4b691c5d42603f65ae576f703f477"),
		BloomRoot:    common.HexToHash("0x5a081af71a588f4d90bced242545b08904ad4fb92f7effff2ceb6e50e6dec157"),
	}

	// MainnetCheckpointOracle contains a set of configs for the main network oracle.
	MainnetCheckpointOracle = &CheckpointOracleConfig{
		Address: common.HexToAddress("0x9a9070028361F7AAbeB3f2F2Dc07F82C4a98A02a"),
		Signers: []common.Address{
			common.HexToAddress("0x1b2C260efc720BE89101890E4Db589b44E950527"), // Peter
			common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin
			common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt
			common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary
			common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume
		},
		Threshold: 2,
	}

	// RopstenChainConfig contains the chain parameters to run a node on the Ropsten test network.
	RopstenChainConfig = &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(1_700_000),
		ConstantinopleBlock: big.NewInt(4_230_000),
		PetersburgBlock:     big.NewInt(4_939_394),
		IstanbulBlock:       big.NewInt(6_485_846),
		MuirGlacierBlock:    big.NewInt(7_117_117),
		BerlinBlock:         big.NewInt(9_812_189),
		LondonBlock:         big.NewInt(10_499_401),
		Ethash:              new(EthashConfig),
	}

	// RopstenTrustedCheckpoint contains the light client trusted checkpoint for the Ropsten test network.
	RopstenTrustedCheckpoint = &TrustedCheckpoint{
		SectionIndex: 346,
		SectionHead:  common.HexToHash("0xafa0384ebd13a751fb7475aaa7fc08ac308925c8b2e2195bca2d4ab1878a7a84"),
		CHTRoot:      common.HexToHash("0x522ae1f334bfa36033b2315d0b9954052780700b69448ecea8d5877e0f7ee477"),
		BloomRoot:    common.HexToHash("0x4093fd53b0d2cc50181dca353fe66f03ae113e7cb65f869a4dfb5905de6a0493"),
	}

	// RopstenCheckpointOracle contains a set of configs for the Ropsten test network oracle.
	RopstenCheckpointOracle = &CheckpointOracleConfig{
		Address: common.HexToAddress("0xEF79475013f154E6A65b54cB2742867791bf0B84"),
		Signers: []common.Address{
			common.HexToAddress("0x32162F3581E88a5f62e8A61892B42C46E2c18f7b"), // Peter
			common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin
			common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt
			common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary
			common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume
		},
		Threshold: 2,
	}

	// SepoliaChainConfig contains the chain parameters to run a node on the Sepolia test network.
	SepoliaChainConfig = &ChainConfig{
		ChainID:             big.NewInt(11155111),
		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),
		IstanbulBlock:       big.NewInt(0),
		MuirGlacierBlock:    big.NewInt(0),
		BerlinBlock:         big.NewInt(0),
		LondonBlock:         big.NewInt(0),
		Ethash:              new(EthashConfig),
	}

	// SepoliaTrustedCheckpoint contains the light client trusted checkpoint for the Sepolia test network.
	SepoliaTrustedCheckpoint = &TrustedCheckpoint{
		SectionIndex: 1,
		SectionHead:  common.HexToHash("0x5dde65e28745b10ff9e9b86499c3a3edc03587b27a06564a4342baf3a37de869"),
		CHTRoot:      common.HexToHash("0x042a0d914f7baa4f28f14d12291e5f346e88c5b9d95127bf5422a8afeacd27e8"),
		BloomRoot:    common.HexToHash("0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"),
	}

	// RinkebyChainConfig contains the chain parameters to run a node on the Rinkeby test network.
	RinkebyChainConfig = &ChainConfig{
		ChainID:             big.NewInt(4),
		HomesteadBlock:      big.NewInt(1),
		DAOForkBlock:        nil,
		DAOForkSupport:      true,
		EIP150Block:         big.NewInt(2),
		EIP150Hash:          common.HexToHash("0x9b095b36c15eaf13044373aef8ee0bd3a382a5abb92e402afa44b8249c3a90e9"),
		EIP155Block:         big.NewInt(3),
		EIP158Block:         big.NewInt(3),
		ByzantiumBlock:      big.NewInt(1_035_301),
		ConstantinopleBlock: big.NewInt(3_660_663),
		PetersburgBlock:     big.NewInt(4_321_234),
		IstanbulBlock:       big.NewInt(5_435_345),
		MuirGlacierBlock:    nil,
		BerlinBlock:         big.NewInt(8_290_928),
		LondonBlock:         big.NewInt(8_897_988),
		ArrowGlacierBlock:   nil,
		Clique: &CliqueConfig{
			Period: 15,
			Epoch:  30000,
		},
	}

	// RinkebyTrustedCheckpoint contains the light client trusted checkpoint for the Rinkeby test network.
	RinkebyTrustedCheckpoint = &TrustedCheckpoint{
		SectionIndex: 292,
		SectionHead:  common.HexToHash("0x4185c2f1bb85ecaa04409d1008ff0761092ea2e94e8a71d64b1a5abc37b81414"),
		CHTRoot:      common.HexToHash("0x03b0191e6140effe0b88bb7c97bfb794a275d3543cb3190662fb72d9beea423c"),
		BloomRoot:    common.HexToHash("0x3d5f6edccc87536dcbc0dd3aae97a318205c617dd3957b4261470c71481629e2"),
	}

	// RinkebyCheckpointOracle contains a set of configs for the Rinkeby test network oracle.
	RinkebyCheckpointOracle = &CheckpointOracleConfig{
		Address: common.HexToAddress("0xebe8eFA441B9302A0d7eaECc277c09d20D684540"),
		Signers: []common.Address{
			common.HexToAddress("0xd9c9cd5f6779558b6e0ed4e6acf6b1947e7fa1f3"), // Peter
			common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin
			common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt
			common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary
		},
		Threshold: 2,
	}

	// GoerliChainConfig contains the chain parameters to run a node on the Görli test network.
	GoerliChainConfig = &ChainConfig{
		ChainID:             big.NewInt(5),
		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),
		IstanbulBlock:       big.NewInt(1_561_651),
		MuirGlacierBlock:    nil,
		BerlinBlock:         big.NewInt(4_460_644),
		LondonBlock:         big.NewInt(5_062_605),
		ArrowGlacierBlock:   nil,
		Clique: &CliqueConfig{
			Period: 15,
			Epoch:  30000,
		},
	}

	// GoerliTrustedCheckpoint contains the light client trusted checkpoint for the Görli test network.
	GoerliTrustedCheckpoint = &TrustedCheckpoint{
		SectionIndex: 176,
		SectionHead:  common.HexToHash("0x2de018858528434f93adb40b1f03f2304a86d31b4ef2b1f930da0134f5c32427"),
		CHTRoot:      common.HexToHash("0x8c17e497d38088321c147abe4acbdfb3c0cab7d7a2b97e07404540f04d12747e"),
		BloomRoot:    common.HexToHash("0x02a41b6606bd3f741bd6ae88792d75b1ad8cf0ea5e28fbaa03bc8b95cbd20034"),
	}

	// GoerliCheckpointOracle contains a set of configs for the Goerli test network oracle.
	GoerliCheckpointOracle = &CheckpointOracleConfig{
		Address: common.HexToAddress("0x18CA0E045F0D772a851BC7e48357Bcaab0a0795D"),
		Signers: []common.Address{
			common.HexToAddress("0x4769bcaD07e3b938B7f43EB7D278Bc7Cb9efFb38"), // Peter
			common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin
			common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt
			common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary
			common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume
		},
		Threshold: 2,
	}

	// 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), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), 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), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}}

	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), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil}
	TestRules       = TestChainConfig.Rules(new(big.Int)) //测试链规则
)

// 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 {
	SectionIndex uint64      `json:"sectionIndex"`
	SectionHead  common.Hash `json:"sectionHead"`
	CHTRoot      common.Hash `json:"chtRoot"`
	BloomRoot    common.Hash `json:"bloomRoot"`
}

// HashEqual returns an indicator comparing the itself hash with given one.
func (c *TrustedCheckpoint) HashEqual(hash common.Hash) bool {
	if c.Empty() {
		return hash == common.Hash{}
	}
	return c.Hash() == hash
}

// Hash returns the hash of checkpoint's four key fields(index, sectionHead, chtRoot and bloomTrieRoot).
func (c *TrustedCheckpoint) Hash() common.Hash {
	var sectionIndex [8]byte
	binary.BigEndian.PutUint64(sectionIndex[:], c.SectionIndex) //将第二个参数的二进制表示每八位一组，按大端序分配到第一个参数中

	w := sha3.NewLegacyKeccak256() //兼容的 keccak256 接口，用于计算哈希
	//写入下面四个字段，准备集散哈希
	w.Write(sectionIndex[:])
	w.Write(c.SectionHead[:])
	w.Write(c.CHTRoot[:])
	w.Write(c.BloomRoot[:])

	var h common.Hash
	w.Sum(h[:0]) //在空切片上用 append 完成赋值
	return h
}

// Empty returns an indicator whether the checkpoint is regarded as empty.
func (c *TrustedCheckpoint) Empty() bool {
	return c.SectionHead == (common.Hash{}) || c.CHTRoot == (common.Hash{}) || c.BloomRoot == (common.Hash{})
}

// CheckpointOracleConfig represents a set of checkpoint contract(which acts as an oracle)
// config which used for light client checkpoint syncing.
type CheckpointOracleConfig struct {
	Address   common.Address   `json:"address"`
	Signers   []common.Address `json:"signers"`
	Threshold uint64           `json:"threshold"`
}

// 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)
	IstanbulBlock       *big.Int `json:"istanbulBlock,omitempty"`       // Istanbul switch block (nil = no fork, 0 = already on istanbul)
	MuirGlacierBlock    *big.Int `json:"muirGlacierBlock,omitempty"`    // Eip-2384 (bomb delay) switch block (nil = no fork, 0 = already activated)
	BerlinBlock         *big.Int `json:"berlinBlock,omitempty"`         // Berlin switch block (nil = no fork, 0 = already on berlin)
	LondonBlock         *big.Int `json:"londonBlock,omitempty"`         // London switch block (nil = no fork, 0 = already on london)
	ArrowGlacierBlock   *big.Int `json:"arrowGlacierBlock,omitempty"`   // Eip-4345 (bomb delay) switch block (nil = no fork, 0 = already activated)

	// TerminalTotalDifficulty is the amount of total difficulty reached by
	// the network that triggers the consensus upgrade.
	TerminalTotalDifficulty *big.Int `json:"terminalTotalDifficulty,omitempty"`

	// Various consensus engines
	Ethash *EthashConfig `json:"ethash,omitempty"` //可选的配置项, Ethash 共识的 EIP 提出的更改
	Clique *CliqueConfig `json:"clique,omitempty"` //可选的配置项, Clique 共识的 EIP 提出的更改
}

// 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"
}

// 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 Petersburg: %v Istanbul: %v, Muir Glacier: %v, Berlin: %v, London: %v, Arrow Glacier: %v, Engine: %v}",
		c.ChainID,
		c.HomesteadBlock,
		c.DAOForkBlock,
		c.DAOForkSupport,
		c.EIP150Block,
		c.EIP155Block,
		c.EIP158Block,
		c.ByzantiumBlock,
		c.ConstantinopleBlock,
		c.PetersburgBlock,
		c.IstanbulBlock,
		c.MuirGlacierBlock,
		c.BerlinBlock,
		c.LondonBlock,
		c.ArrowGlacierBlock,
		engine,
	)
}

//num 的区块高度是否已启用了这个分叉

// 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)
}

// IsMuirGlacier returns whether num is either equal to the Muir Glacier (EIP-2384) fork block or greater.
func (c *ChainConfig) IsMuirGlacier(num *big.Int) bool {
	return isForked(c.MuirGlacierBlock, 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)
}

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

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

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

// IsArrowGlacier returns whether num is either equal to the Arrow Glacier (EIP-4345) fork block or greater.
func (c *ChainConfig) IsArrowGlacier(num *big.Int) bool {
	return isForked(c.ArrowGlacierBlock, num)
}

// IsTerminalPoWBlock returns whether the given block is the last block of PoW stage.
func (c *ChainConfig) IsTerminalPoWBlock(parentTotalDiff *big.Int, totalDiff *big.Int) bool {
	if c.TerminalTotalDifficulty == nil {
		return false
	}
	return parentTotalDiff.Cmp(c.TerminalTotalDifficulty) < 0 && totalDiff.Cmp(c.TerminalTotalDifficulty) >= 0
}

//检查新的配置是否

// 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) //新建 math/big 包中的 Int 类型

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

//检查分叉配置的顺序，如果某个分叉产生，那么他之前的分叉也必须按顺序产生

// CheckConfigForkOrder checks that we don't "skip" any forks, geth isn't pluggable enough
// to guarantee that forks can be implemented in a different order than on official networks
func (c *ChainConfig) CheckConfigForkOrder() error {
	type fork struct {
		name     string
		block    *big.Int
		optional bool // if true, the fork may be nil and next fork is still allowed
	}
	var lastFork fork
	for _, cur := range []fork{ //数组的 range 会按顺序排列
		{name: "homesteadBlock", block: c.HomesteadBlock},
		{name: "daoForkBlock", block: c.DAOForkBlock, optional: true},
		{name: "eip150Block", block: c.EIP150Block},
		{name: "eip155Block", block: c.EIP155Block},
		{name: "eip158Block", block: c.EIP158Block},
		{name: "byzantiumBlock", block: c.ByzantiumBlock},
		{name: "constantinopleBlock", block: c.ConstantinopleBlock},
		{name: "petersburgBlock", block: c.PetersburgBlock},
		{name: "istanbulBlock", block: c.IstanbulBlock},
		{name: "muirGlacierBlock", block: c.MuirGlacierBlock, optional: true},
		{name: "berlinBlock", block: c.BerlinBlock},
		{name: "londonBlock", block: c.LondonBlock},
		{name: "arrowGlacierBlock", block: c.ArrowGlacierBlock, optional: true},
	} {
		if lastFork.name != "" { //避免第一次运行
			// Next one must be higher number
			if lastFork.block == nil && cur.block != nil { //当前分叉开始，但是之前的分叉没有配置
				return fmt.Errorf("unsupported fork ordering: %v not enabled, but %v enabled at %v",
					lastFork.name, cur.name, cur.block)
			}
			if lastFork.block != nil && cur.block != nil { //分叉的顺序错误
				if lastFork.block.Cmp(cur.block) > 0 {
					return fmt.Errorf("unsupported fork ordering: %v enabled at %v, but %v enabled at %v",
						lastFork.name, lastFork.block, cur.name, cur.block)
				}
			}
		}

		//如果不是可选项或者没有忽略，就记录这一项

		// If it was optional and not set, then ignore it
		if !cur.optional || cur.block != nil {
			lastFork = cur
		}
	}
	return nil
}

//用于保证配置文件更新后能够兼容原来的配置文件
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) {
		// the only case where we allow Petersburg to be set in the past is if it is equal to Constantinople
		// mainly to satisfy fork ordering requirements which state that Petersburg fork be set if Constantinople fork is set
		if isForkIncompatible(c.ConstantinopleBlock, newcfg.PetersburgBlock, head) {
			return newCompatError("Petersburg fork block", c.PetersburgBlock, newcfg.PetersburgBlock)
		}
	}
	if isForkIncompatible(c.IstanbulBlock, newcfg.IstanbulBlock, head) {
		return newCompatError("Istanbul fork block", c.IstanbulBlock, newcfg.IstanbulBlock)
	}
	if isForkIncompatible(c.MuirGlacierBlock, newcfg.MuirGlacierBlock, head) {
		return newCompatError("Muir Glacier fork block", c.MuirGlacierBlock, newcfg.MuirGlacierBlock)
	}
	if isForkIncompatible(c.BerlinBlock, newcfg.BerlinBlock, head) {
		return newCompatError("Berlin fork block", c.BerlinBlock, newcfg.BerlinBlock)
	}
	if isForkIncompatible(c.LondonBlock, newcfg.LondonBlock, head) {
		return newCompatError("London fork block", c.LondonBlock, newcfg.LondonBlock)
	}
	if isForkIncompatible(c.ArrowGlacierBlock, newcfg.ArrowGlacierBlock, head) {
		return newCompatError("Arrow Glacier fork block", c.ArrowGlacierBlock, newcfg.ArrowGlacierBlock)
	}
	return nil
}

//head 高度处，s1 或者 s2 已经分叉，而且分叉的高度不相等，这时返回 true，表示配置不兼容。
//实际上，用于限制更改后新的配置文件必须兼容老的配置文件。
//如果老的配置文件中无某个分叉，那么新的也不能有。如果老的有某个分叉，新的必须在相同的位置有。

// 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

	//新配置和原来的配置中对应的某个分叉所在的区块高度

	// block numbers of the stored and new configurations
	StoredConfig, NewConfig *big.Int

	// 需要回退到的区块高度

	// the block number to which the local chain must be rewound to correct the error
	RewindTo uint64
}

//storedblock 原来区块的分叉的高度，newblock 原来区块的分叉的高度
func newCompatError(what string, storedblock, newblock *big.Int) *ConfigCompatError {
	var rew *big.Int
	switch {
	case storedblock == nil: //原来的配置为空，表示新产生的配置
		rew = newblock
	case newblock == nil || storedblock.Cmp(newblock) < 0: //原配置不为空且其中的该分叉的区块高度小
		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)
}

//用于表示主要的链配置，如一些链ID、主要的分叉是否采用，但是无法在更新配置时使用

// 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, IsIstanbul bool
	IsBerlin, IsLondon                                      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),
		IsIstanbul:       c.IsIstanbul(num),
		IsBerlin:         c.IsBerlin(num),
		IsLondon:         c.IsLondon(num),
	}
}