mirror of
https://gitlab.com/pulsechaincom/erigon-pulse.git
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245 lines
8.9 KiB
Go
245 lines
8.9 KiB
Go
// Copyright 2019 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package forkid implements EIP-2124 (https://eips.ethereum.org/EIPS/eip-2124).
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package forkid
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import (
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"encoding/binary"
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"errors"
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"hash/crc32"
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"math"
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"math/big"
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"reflect"
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"sort"
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"strings"
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"github.com/ledgerwatch/erigon/common"
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"github.com/ledgerwatch/erigon/params"
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"github.com/ledgerwatch/log/v3"
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)
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var (
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// ErrRemoteStale is returned by the validator if a remote fork checksum is a
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// subset of our already applied forks, but the announced next fork block is
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// not on our already passed chain.
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ErrRemoteStale = errors.New("remote needs update")
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// ErrLocalIncompatibleOrStale is returned by the validator if a remote fork
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// checksum does not match any local checksum variation, signalling that the
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// two chains have diverged in the past at some point (possibly at genesis).
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ErrLocalIncompatibleOrStale = errors.New("local incompatible or needs update")
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)
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// ID is a fork identifier as defined by EIP-2124.
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type ID struct {
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Hash [4]byte // CRC32 checksum of the genesis block and passed fork block numbers
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Next uint64 // Block number of the next upcoming fork, or 0 if no forks are known
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}
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// Filter is a fork id filter to validate a remotely advertised ID.
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type Filter func(id ID) error
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// NewID calculates the Ethereum fork ID from the chain config, genesis hash, and head.
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func NewID(config *params.ChainConfig, genesis common.Hash, head uint64) ID {
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return NewIDFromForks(GatherForks(config), genesis, head)
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}
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func NewIDFromForks(forks []uint64, genesis common.Hash, head uint64) ID {
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// Calculate the starting checksum from the genesis hash
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hash := crc32.ChecksumIEEE(genesis[:])
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// Calculate the current fork checksum and the next fork block
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var next uint64
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for _, fork := range forks {
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if fork <= head {
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// Fork already passed, checksum the previous hash and the fork number
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hash = checksumUpdate(hash, fork)
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continue
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}
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next = fork
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break
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}
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return ID{Hash: checksumToBytes(hash), Next: next}
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}
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// NewFilter creates a filter that returns if a fork ID should be rejected or notI
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// based on the local chain's status.
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func NewFilter(config *params.ChainConfig, genesis common.Hash, head func() uint64) Filter {
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forks := GatherForks(config)
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return newFilter(
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forks,
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genesis,
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head,
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)
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}
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func NewFilterFromForks(forks []uint64, genesis common.Hash, headNumber uint64) Filter {
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head := func() uint64 { return headNumber }
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return newFilter(forks, genesis, head)
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}
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// NewStaticFilter creates a filter at block zero.
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func NewStaticFilter(config *params.ChainConfig, genesis common.Hash) Filter {
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head := func() uint64 { return 0 }
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forks := GatherForks(config)
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return newFilter(forks, genesis, head)
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}
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// newFilter is the internal version of NewFilter, taking closures as its arguments
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// instead of a chain. The reason is to allow testing it without having to simulate
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// an entire blockchain.
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func newFilter(forks []uint64, genesis common.Hash, headfn func() uint64) Filter {
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// Calculate the all the valid fork hash and fork next combos
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var (
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sums = make([][4]byte, len(forks)+1) // 0th is the genesis
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)
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hash := crc32.ChecksumIEEE(genesis[:])
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sums[0] = checksumToBytes(hash)
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for i, fork := range forks {
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hash = checksumUpdate(hash, fork)
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sums[i+1] = checksumToBytes(hash)
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}
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// Add two sentries to simplify the fork checks and don't require special
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// casing the last one.
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forks = append(forks, math.MaxUint64) // Last fork will never be passed
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// Create a validator that will filter out incompatible chains
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return func(id ID) error {
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if genesis == params.SokolGenesisHash {
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return nil
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}
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// Run the fork checksum validation ruleset:
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// 1. If local and remote FORK_CSUM matches, compare local head to FORK_NEXT.
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// The two nodes are in the same fork state currently. They might know
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// of differing future forks, but that's not relevant until the fork
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// triggers (might be postponed, nodes might be updated to match).
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// 1a. A remotely announced but remotely not passed block is already passed
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// locally, disconnect, since the chains are incompatible.
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// 1b. No remotely announced fork; or not yet passed locally, connect.
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// 2. If the remote FORK_CSUM is a subset of the local past forks and the
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// remote FORK_NEXT matches with the locally following fork block number,
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// connect.
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// Remote node is currently syncing. It might eventually diverge from
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// us, but at this current point in time we don't have enough information.
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// 3. If the remote FORK_CSUM is a superset of the local past forks and can
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// be completed with locally known future forks, connect.
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// Local node is currently syncing. It might eventually diverge from
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// the remote, but at this current point in time we don't have enough
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// information.
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// 4. Reject in all other cases.
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head := headfn()
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for i, fork := range forks {
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// If our head is beyond this fork, continue to the next (we have a dummy
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// fork of maxuint64 as the last item to always fail this check eventually).
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if head > fork {
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continue
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}
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// Found the first unpassed fork block, check if our current state matches
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// the remote checksum (rule #1).
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if sums[i] == id.Hash {
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// Fork checksum matched, check if a remote future fork block already passed
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// locally without the local node being aware of it (rule #1a).
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if id.Next > 0 && head >= id.Next {
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return ErrLocalIncompatibleOrStale
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}
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// Haven't passed locally a remote-only fork, accept the connection (rule #1b).
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return nil
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}
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// The local and remote nodes are in different forks currently, check if the
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// remote checksum is a subset of our local forks (rule #2).
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for j := 0; j < i; j++ {
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if sums[j] == id.Hash {
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// Remote checksum is a subset, validate based on the announced next fork
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if forks[j] != id.Next {
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return ErrRemoteStale
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}
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return nil
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}
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}
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// Remote chain is not a subset of our local one, check if it's a superset by
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// any chance, signalling that we're simply out of sync (rule #3).
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for j := i + 1; j < len(sums); j++ {
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if sums[j] == id.Hash {
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// Yay, remote checksum is a superset, ignore upcoming forks
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return nil
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}
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}
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// No exact, subset or superset match. We are on differing chains, reject.
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return ErrLocalIncompatibleOrStale
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}
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log.Error("Impossible fork ID validation", "id", id)
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return nil // Something's very wrong, accept rather than reject
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}
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}
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// checksumUpdate calculates the next IEEE CRC32 checksum based on the previous
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// one and a fork block number (equivalent to CRC32(original-blob || fork)).
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func checksumUpdate(hash uint32, fork uint64) uint32 {
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var blob [8]byte
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binary.BigEndian.PutUint64(blob[:], fork)
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return crc32.Update(hash, crc32.IEEETable, blob[:])
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}
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// checksumToBytes converts a uint32 checksum into a [4]byte array.
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func checksumToBytes(hash uint32) [4]byte {
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var blob [4]byte
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binary.BigEndian.PutUint32(blob[:], hash)
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return blob
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}
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// GatherForks gathers all the known forks and creates a sorted list out of them.
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func GatherForks(config *params.ChainConfig) []uint64 {
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if config.ChainID.Uint64() == 77 {
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return []uint64{6464300, 7026400, 12095200, 21050600}
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}
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// Gather all the fork block numbers via reflection
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kind := reflect.TypeOf(params.ChainConfig{})
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conf := reflect.ValueOf(config).Elem()
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forks := make(map[uint64]struct{})
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for i := 0; i < kind.NumField(); i++ {
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// Fetch the next field and skip non-fork rules
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field := kind.Field(i)
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if !strings.HasSuffix(field.Name, "Block") {
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continue
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}
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if field.Type != reflect.TypeOf(new(big.Int)) {
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continue
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}
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// Extract the fork rule block number and aggregate it
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rule := conf.Field(i).Interface().(*big.Int)
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if rule != nil {
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forks[rule.Uint64()] = struct{}{}
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}
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}
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// Sort the fork block numbers to permit chronological XOR
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forkBlocks := make([]uint64, 0, len(forks))
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for num := range forks {
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forkBlocks = append(forkBlocks, num)
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}
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sort.SliceStable(forkBlocks, func(i, j int) bool {
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return forkBlocks[i] < forkBlocks[j]
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})
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// Skip any forks in block 0, that's the genesis ruleset
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if len(forkBlocks) > 0 && forkBlocks[0] == 0 {
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forkBlocks = forkBlocks[1:]
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}
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return forkBlocks
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}
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