304 lines
11 KiB
Go
304 lines
11 KiB
Go
// Copyright 2019 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 forkid implements EIP-2124 (https://eips.ethereum.org/EIPS/eip-2124).
|
|
package forkid
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"errors"
|
|
"hash/crc32"
|
|
"math"
|
|
"math/big"
|
|
"reflect"
|
|
"strings"
|
|
|
|
"github.com/ethereum/go-ethereum/core/types"
|
|
"github.com/ethereum/go-ethereum/log"
|
|
"github.com/ethereum/go-ethereum/params"
|
|
"golang.org/x/exp/slices"
|
|
)
|
|
|
|
var (
|
|
// ErrRemoteStale is returned by the validator if a remote fork checksum is a
|
|
// subset of our already applied forks, but the announced next fork block is
|
|
// not on our already passed chain.
|
|
ErrRemoteStale = errors.New("remote needs update")
|
|
|
|
// ErrLocalIncompatibleOrStale is returned by the validator if a remote fork
|
|
// checksum does not match any local checksum variation, signalling that the
|
|
// two chains have diverged in the past at some point (possibly at genesis).
|
|
ErrLocalIncompatibleOrStale = errors.New("local incompatible or needs update")
|
|
)
|
|
|
|
// timestampThreshold is the Ethereum mainnet genesis timestamp. It is used to
|
|
// differentiate if a forkid.next field is a block number or a timestamp. Whilst
|
|
// very hacky, something's needed to split the validation during the transition
|
|
// period (block forks -> time forks).
|
|
const timestampThreshold = 1438269973
|
|
|
|
// Blockchain defines all necessary method to build a forkID.
|
|
type Blockchain interface {
|
|
// Config retrieves the chain's fork configuration.
|
|
Config() *params.ChainConfig
|
|
|
|
// Genesis retrieves the chain's genesis block.
|
|
Genesis() *types.Block
|
|
|
|
// CurrentHeader retrieves the current head header of the canonical chain.
|
|
CurrentHeader() *types.Header
|
|
}
|
|
|
|
// ID is a fork identifier as defined by EIP-2124.
|
|
type ID struct {
|
|
Hash [4]byte // CRC32 checksum of the genesis block and passed fork block numbers
|
|
Next uint64 // Block number of the next upcoming fork, or 0 if no forks are known
|
|
}
|
|
|
|
// Filter is a fork id filter to validate a remotely advertised ID.
|
|
type Filter func(id ID) error
|
|
|
|
// NewID calculates the Ethereum fork ID from the chain config, genesis hash, head and time.
|
|
func NewID(config *params.ChainConfig, genesis *types.Block, head, time uint64) ID {
|
|
// Calculate the starting checksum from the genesis hash
|
|
hash := crc32.ChecksumIEEE(genesis.Hash().Bytes())
|
|
|
|
// Calculate the current fork checksum and the next fork block
|
|
forksByBlock, forksByTime := gatherForks(config, genesis.Time())
|
|
for _, fork := range forksByBlock {
|
|
if fork <= head {
|
|
// Fork already passed, checksum the previous hash and the fork number
|
|
hash = checksumUpdate(hash, fork)
|
|
continue
|
|
}
|
|
return ID{Hash: checksumToBytes(hash), Next: fork}
|
|
}
|
|
for _, fork := range forksByTime {
|
|
if fork <= time {
|
|
// Fork already passed, checksum the previous hash and fork timestamp
|
|
hash = checksumUpdate(hash, fork)
|
|
continue
|
|
}
|
|
return ID{Hash: checksumToBytes(hash), Next: fork}
|
|
}
|
|
return ID{Hash: checksumToBytes(hash), Next: 0}
|
|
}
|
|
|
|
// NewIDWithChain calculates the Ethereum fork ID from an existing chain instance.
|
|
func NewIDWithChain(chain Blockchain) ID {
|
|
head := chain.CurrentHeader()
|
|
|
|
return NewID(
|
|
chain.Config(),
|
|
chain.Genesis(),
|
|
head.Number.Uint64(),
|
|
head.Time,
|
|
)
|
|
}
|
|
|
|
// NewFilter creates a filter that returns if a fork ID should be rejected or not
|
|
// based on the local chain's status.
|
|
func NewFilter(chain Blockchain) Filter {
|
|
return newFilter(
|
|
chain.Config(),
|
|
chain.Genesis(),
|
|
func() (uint64, uint64) {
|
|
head := chain.CurrentHeader()
|
|
return head.Number.Uint64(), head.Time
|
|
},
|
|
)
|
|
}
|
|
|
|
// NewStaticFilter creates a filter at block zero.
|
|
func NewStaticFilter(config *params.ChainConfig, genesis *types.Block) Filter {
|
|
head := func() (uint64, uint64) { return 0, 0 }
|
|
return newFilter(config, genesis, head)
|
|
}
|
|
|
|
// newFilter is the internal version of NewFilter, taking closures as its arguments
|
|
// instead of a chain. The reason is to allow testing it without having to simulate
|
|
// an entire blockchain.
|
|
func newFilter(config *params.ChainConfig, genesis *types.Block, headfn func() (uint64, uint64)) Filter {
|
|
// Calculate the all the valid fork hash and fork next combos
|
|
var (
|
|
forksByBlock, forksByTime = gatherForks(config, genesis.Time())
|
|
forks = append(append([]uint64{}, forksByBlock...), forksByTime...)
|
|
sums = make([][4]byte, len(forks)+1) // 0th is the genesis
|
|
)
|
|
hash := crc32.ChecksumIEEE(genesis.Hash().Bytes())
|
|
sums[0] = checksumToBytes(hash)
|
|
for i, fork := range forks {
|
|
hash = checksumUpdate(hash, fork)
|
|
sums[i+1] = checksumToBytes(hash)
|
|
}
|
|
// Add two sentries to simplify the fork checks and don't require special
|
|
// casing the last one.
|
|
forks = append(forks, math.MaxUint64) // Last fork will never be passed
|
|
if len(forksByTime) == 0 {
|
|
// In purely block based forks, avoid the sentry spilling into timestapt territory
|
|
forksByBlock = append(forksByBlock, math.MaxUint64) // Last fork will never be passed
|
|
}
|
|
// Create a validator that will filter out incompatible chains
|
|
return func(id ID) error {
|
|
// Run the fork checksum validation ruleset:
|
|
// 1. If local and remote FORK_CSUM matches, compare local head to FORK_NEXT.
|
|
// The two nodes are in the same fork state currently. They might know
|
|
// of differing future forks, but that's not relevant until the fork
|
|
// triggers (might be postponed, nodes might be updated to match).
|
|
// 1a. A remotely announced but remotely not passed block is already passed
|
|
// locally, disconnect, since the chains are incompatible.
|
|
// 1b. No remotely announced fork; or not yet passed locally, connect.
|
|
// 2. If the remote FORK_CSUM is a subset of the local past forks and the
|
|
// remote FORK_NEXT matches with the locally following fork block number,
|
|
// connect.
|
|
// Remote node is currently syncing. It might eventually diverge from
|
|
// us, but at this current point in time we don't have enough information.
|
|
// 3. If the remote FORK_CSUM is a superset of the local past forks and can
|
|
// be completed with locally known future forks, connect.
|
|
// Local node is currently syncing. It might eventually diverge from
|
|
// the remote, but at this current point in time we don't have enough
|
|
// information.
|
|
// 4. Reject in all other cases.
|
|
block, time := headfn()
|
|
for i, fork := range forks {
|
|
// Pick the head comparison based on fork progression
|
|
head := block
|
|
if i >= len(forksByBlock) {
|
|
head = time
|
|
}
|
|
// If our head is beyond this fork, continue to the next (we have a dummy
|
|
// fork of maxuint64 as the last item to always fail this check eventually).
|
|
if head >= fork {
|
|
continue
|
|
}
|
|
// Found the first unpassed fork block, check if our current state matches
|
|
// the remote checksum (rule #1).
|
|
if sums[i] == id.Hash {
|
|
// Fork checksum matched, check if a remote future fork block already passed
|
|
// locally without the local node being aware of it (rule #1a).
|
|
if id.Next > 0 && (head >= id.Next || (id.Next > timestampThreshold && time >= id.Next)) {
|
|
return ErrLocalIncompatibleOrStale
|
|
}
|
|
// Haven't passed locally a remote-only fork, accept the connection (rule #1b).
|
|
return nil
|
|
}
|
|
// The local and remote nodes are in different forks currently, check if the
|
|
// remote checksum is a subset of our local forks (rule #2).
|
|
for j := 0; j < i; j++ {
|
|
if sums[j] == id.Hash {
|
|
// Remote checksum is a subset, validate based on the announced next fork
|
|
if forks[j] != id.Next {
|
|
return ErrRemoteStale
|
|
}
|
|
return nil
|
|
}
|
|
}
|
|
// Remote chain is not a subset of our local one, check if it's a superset by
|
|
// any chance, signalling that we're simply out of sync (rule #3).
|
|
for j := i + 1; j < len(sums); j++ {
|
|
if sums[j] == id.Hash {
|
|
// Yay, remote checksum is a superset, ignore upcoming forks
|
|
return nil
|
|
}
|
|
}
|
|
// No exact, subset or superset match. We are on differing chains, reject.
|
|
return ErrLocalIncompatibleOrStale
|
|
}
|
|
log.Error("Impossible fork ID validation", "id", id)
|
|
return nil // Something's very wrong, accept rather than reject
|
|
}
|
|
}
|
|
|
|
// checksumUpdate calculates the next IEEE CRC32 checksum based on the previous
|
|
// one and a fork block number (equivalent to CRC32(original-blob || fork)).
|
|
func checksumUpdate(hash uint32, fork uint64) uint32 {
|
|
var blob [8]byte
|
|
binary.BigEndian.PutUint64(blob[:], fork)
|
|
return crc32.Update(hash, crc32.IEEETable, blob[:])
|
|
}
|
|
|
|
// checksumToBytes converts a uint32 checksum into a [4]byte array.
|
|
func checksumToBytes(hash uint32) [4]byte {
|
|
var blob [4]byte
|
|
binary.BigEndian.PutUint32(blob[:], hash)
|
|
return blob
|
|
}
|
|
|
|
// gatherForks gathers all the known forks and creates two sorted lists out of
|
|
// them, one for the block number based forks and the second for the timestamps.
|
|
func gatherForks(config *params.ChainConfig, genesis uint64) ([]uint64, []uint64) {
|
|
|
|
// Gather all the fork block numbers via reflection
|
|
kind := reflect.TypeOf(params.ChainConfig{})
|
|
conf := reflect.ValueOf(config).Elem()
|
|
x := uint64(0)
|
|
var (
|
|
forksByBlock []uint64
|
|
forksByTime []uint64
|
|
)
|
|
for i := 0; i < kind.NumField(); i++ {
|
|
// Fetch the next field and skip non-fork rules
|
|
field := kind.Field(i)
|
|
|
|
time := strings.HasSuffix(field.Name, "Time")
|
|
if !time && !strings.HasSuffix(field.Name, "Block") {
|
|
continue
|
|
}
|
|
|
|
// Extract the fork rule block number or timestamp and aggregate it
|
|
if field.Type == reflect.TypeOf(&x) {
|
|
if rule := conf.Field(i).Interface().(*uint64); rule != nil {
|
|
forksByTime = append(forksByTime, *rule)
|
|
}
|
|
}
|
|
if field.Type == reflect.TypeOf(new(big.Int)) {
|
|
if rule := conf.Field(i).Interface().(*big.Int); rule != nil {
|
|
forksByBlock = append(forksByBlock, rule.Uint64())
|
|
}
|
|
}
|
|
}
|
|
slices.Sort(forksByBlock)
|
|
slices.Sort(forksByTime)
|
|
|
|
// Deduplicate fork identifiers applying multiple forks
|
|
for i := 1; i < len(forksByBlock); i++ {
|
|
if forksByBlock[i] == forksByBlock[i-1] {
|
|
forksByBlock = append(forksByBlock[:i], forksByBlock[i+1:]...)
|
|
i--
|
|
}
|
|
}
|
|
for i := 1; i < len(forksByTime); i++ {
|
|
if forksByTime[i] == forksByTime[i-1] {
|
|
forksByTime = append(forksByTime[:i], forksByTime[i+1:]...)
|
|
i--
|
|
}
|
|
}
|
|
// Skip any forks in block 0, that's the genesis ruleset
|
|
if len(forksByBlock) > 0 && forksByBlock[0] == 0 {
|
|
forksByBlock = forksByBlock[1:]
|
|
}
|
|
// Skip any forks before genesis.
|
|
for len(forksByTime) > 0 && forksByTime[0] <= genesis {
|
|
forksByTime = forksByTime[1:]
|
|
}
|
|
// begin PluGeth injection
|
|
if byBlock, byTime, ok := pluginForkIDs(forksByBlock, forksByTime); ok {
|
|
return byBlock, byTime
|
|
}
|
|
// end PluGeth injection
|
|
return forksByBlock, forksByTime
|
|
}
|