Official Go implementation of the Ethereum protocol
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go-ethereum/eth/downloader/downloader.go

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68 KiB

// Copyright 2015 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 downloader contains the manual full chain synchronisation.
package downloader
import (
"errors"
"fmt"
"math/big"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/state/snapshot"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/protocols/snap"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/trie"
)
var (
MaxBlockFetch = 128 // Amount of blocks to be fetched per retrieval request
MaxHeaderFetch = 192 // Amount of block headers to be fetched per retrieval request
MaxSkeletonSize = 128 // Number of header fetches to need for a skeleton assembly
MaxReceiptFetch = 256 // Amount of transaction receipts to allow fetching per request
maxQueuedHeaders = 32 * 1024 // [eth/62] Maximum number of headers to queue for import (DOS protection)
maxHeadersProcess = 2048 // Number of header download results to import at once into the chain
maxResultsProcess = 2048 // Number of content download results to import at once into the chain
fullMaxForkAncestry uint64 = params.FullImmutabilityThreshold // Maximum chain reorganisation (locally redeclared so tests can reduce it)
lightMaxForkAncestry uint64 = params.LightImmutabilityThreshold // Maximum chain reorganisation (locally redeclared so tests can reduce it)
reorgProtThreshold = 48 // Threshold number of recent blocks to disable mini reorg protection
reorgProtHeaderDelay = 2 // Number of headers to delay delivering to cover mini reorgs
fsHeaderSafetyNet = 2048 // Number of headers to discard in case a chain violation is detected
fsHeaderContCheck = 3 * time.Second // Time interval to check for header continuations during state download
fsMinFullBlocks = 64 // Number of blocks to retrieve fully even in snap sync
)
var (
errBusy = errors.New("busy")
errUnknownPeer = errors.New("peer is unknown or unhealthy")
errBadPeer = errors.New("action from bad peer ignored")
errStallingPeer = errors.New("peer is stalling")
errUnsyncedPeer = errors.New("unsynced peer")
errNoPeers = errors.New("no peers to keep download active")
errTimeout = errors.New("timeout")
errEmptyHeaderSet = errors.New("empty header set by peer")
errPeersUnavailable = errors.New("no peers available or all tried for download")
errInvalidAncestor = errors.New("retrieved ancestor is invalid")
errInvalidChain = errors.New("retrieved hash chain is invalid")
errInvalidBody = errors.New("retrieved block body is invalid")
errInvalidReceipt = errors.New("retrieved receipt is invalid")
errCancelStateFetch = errors.New("state data download canceled (requested)")
errCancelContentProcessing = errors.New("content processing canceled (requested)")
errCanceled = errors.New("syncing canceled (requested)")
errTooOld = errors.New("peer's protocol version too old")
errNoAncestorFound = errors.New("no common ancestor found")
errNoPivotHeader = errors.New("pivot header is not found")
ErrMergeTransition = errors.New("legacy sync reached the merge")
)
// peerDropFn is a callback type for dropping a peer detected as malicious.
type peerDropFn func(id string)
// badBlockFn is a callback for the async beacon sync to notify the caller that
// the origin header requested to sync to, produced a chain with a bad block.
type badBlockFn func(invalid *types.Header, origin *types.Header)
// headerTask is a set of downloaded headers to queue along with their precomputed
// hashes to avoid constant rehashing.
type headerTask struct {
headers []*types.Header
hashes []common.Hash
}
type Downloader struct {
mode atomic.Uint32 // Synchronisation mode defining the strategy used (per sync cycle), use d.getMode() to get the SyncMode
mux *event.TypeMux // Event multiplexer to announce sync operation events
genesis uint64 // Genesis block number to limit sync to (e.g. light client CHT)
queue *queue // Scheduler for selecting the hashes to download
peers *peerSet // Set of active peers from which download can proceed
stateDB ethdb.Database // Database to state sync into (and deduplicate via)
// Statistics
syncStatsChainOrigin uint64 // Origin block number where syncing started at
syncStatsChainHeight uint64 // Highest block number known when syncing started
syncStatsLock sync.RWMutex // Lock protecting the sync stats fields
lightchain LightChain
blockchain BlockChain
// Callbacks
dropPeer peerDropFn // Drops a peer for misbehaving
badBlock badBlockFn // Reports a block as rejected by the chain
// Status
synchroniseMock func(id string, hash common.Hash) error // Replacement for synchronise during testing
synchronising atomic.Bool
notified atomic.Bool
committed atomic.Bool
ancientLimit uint64 // The maximum block number which can be regarded as ancient data.
// Channels
headerProcCh chan *headerTask // Channel to feed the header processor new tasks
// Skeleton sync
skeleton *skeleton // Header skeleton to backfill the chain with (eth2 mode)
// State sync
pivotHeader *types.Header // Pivot block header to dynamically push the syncing state root
pivotLock sync.RWMutex // Lock protecting pivot header reads from updates
SnapSyncer *snap.Syncer // TODO(karalabe): make private! hack for now
stateSyncStart chan *stateSync
// Cancellation and termination
cancelPeer string // Identifier of the peer currently being used as the master (cancel on drop)
cancelCh chan struct{} // Channel to cancel mid-flight syncs
cancelLock sync.RWMutex // Lock to protect the cancel channel and peer in delivers
cancelWg sync.WaitGroup // Make sure all fetcher goroutines have exited.
quitCh chan struct{} // Quit channel to signal termination
quitLock sync.Mutex // Lock to prevent double closes
// Testing hooks
syncInitHook func(uint64, uint64) // Method to call upon initiating a new sync run
bodyFetchHook func([]*types.Header) // Method to call upon starting a block body fetch
receiptFetchHook func([]*types.Header) // Method to call upon starting a receipt fetch
chainInsertHook func([]*fetchResult) // Method to call upon inserting a chain of blocks (possibly in multiple invocations)
// Progress reporting metrics
syncStartBlock uint64 // Head snap block when Geth was started
syncStartTime time.Time // Time instance when chain sync started
syncLogTime time.Time // Time instance when status was last reported
}
// LightChain encapsulates functions required to synchronise a light chain.
type LightChain interface {
// HasHeader verifies a header's presence in the local chain.
HasHeader(common.Hash, uint64) bool
// GetHeaderByHash retrieves a header from the local chain.
GetHeaderByHash(common.Hash) *types.Header
// CurrentHeader retrieves the head header from the local chain.
CurrentHeader() *types.Header
// GetTd returns the total difficulty of a local block.
GetTd(common.Hash, uint64) *big.Int
// InsertHeaderChain inserts a batch of headers into the local chain.
InsertHeaderChain([]*types.Header) (int, error)
// SetHead rewinds the local chain to a new head.
SetHead(uint64) error
}
// BlockChain encapsulates functions required to sync a (full or snap) blockchain.
type BlockChain interface {
LightChain
// HasBlock verifies a block's presence in the local chain.
HasBlock(common.Hash, uint64) bool
// HasFastBlock verifies a snap block's presence in the local chain.
HasFastBlock(common.Hash, uint64) bool
// GetBlockByHash retrieves a block from the local chain.
GetBlockByHash(common.Hash) *types.Block
// CurrentBlock retrieves the head block from the local chain.
CurrentBlock() *types.Header
// CurrentSnapBlock retrieves the head snap block from the local chain.
CurrentSnapBlock() *types.Header
// SnapSyncCommitHead directly commits the head block to a certain entity.
SnapSyncCommitHead(common.Hash) error
// InsertChain inserts a batch of blocks into the local chain.
InsertChain(types.Blocks) (int, error)
// InsertReceiptChain inserts a batch of receipts into the local chain.
InsertReceiptChain(types.Blocks, []types.Receipts, uint64) (int, error)
// Snapshots returns the blockchain snapshot tree to paused it during sync.
Snapshots() *snapshot.Tree
// TrieDB retrieves the low level trie database used for interacting
// with trie nodes.
TrieDB() *trie.Database
}
// New creates a new downloader to fetch hashes and blocks from remote peers.
func New(stateDb ethdb.Database, mux *event.TypeMux, chain BlockChain, lightchain LightChain, dropPeer peerDropFn, success func()) *Downloader {
if lightchain == nil {
lightchain = chain
}
dl := &Downloader{
stateDB: stateDb,
mux: mux,
queue: newQueue(blockCacheMaxItems, blockCacheInitialItems),
peers: newPeerSet(),
blockchain: chain,
lightchain: lightchain,
dropPeer: dropPeer,
headerProcCh: make(chan *headerTask, 1),
quitCh: make(chan struct{}),
SnapSyncer: snap.NewSyncer(stateDb, chain.TrieDB().Scheme()),
stateSyncStart: make(chan *stateSync),
syncStartBlock: chain.CurrentSnapBlock().Number.Uint64(),
}
// Create the post-merge skeleton syncer and start the process
dl.skeleton = newSkeleton(stateDb, dl.peers, dropPeer, newBeaconBackfiller(dl, success))
go dl.stateFetcher()
return dl
}
// Progress retrieves the synchronisation boundaries, specifically the origin
// block where synchronisation started at (may have failed/suspended); the block
// or header sync is currently at; and the latest known block which the sync targets.
//
// In addition, during the state download phase of snap synchronisation the number
// of processed and the total number of known states are also returned. Otherwise
// these are zero.
func (d *Downloader) Progress() ethereum.SyncProgress {
// Lock the current stats and return the progress
d.syncStatsLock.RLock()
defer d.syncStatsLock.RUnlock()
current := uint64(0)
mode := d.getMode()
switch {
case d.blockchain != nil && mode == FullSync:
current = d.blockchain.CurrentBlock().Number.Uint64()
case d.blockchain != nil && mode == SnapSync:
current = d.blockchain.CurrentSnapBlock().Number.Uint64()
case d.lightchain != nil:
current = d.lightchain.CurrentHeader().Number.Uint64()
default:
log.Error("Unknown downloader chain/mode combo", "light", d.lightchain != nil, "full", d.blockchain != nil, "mode", mode)
}
progress, pending := d.SnapSyncer.Progress()
return ethereum.SyncProgress{
StartingBlock: d.syncStatsChainOrigin,
CurrentBlock: current,
HighestBlock: d.syncStatsChainHeight,
SyncedAccounts: progress.AccountSynced,
SyncedAccountBytes: uint64(progress.AccountBytes),
SyncedBytecodes: progress.BytecodeSynced,
SyncedBytecodeBytes: uint64(progress.BytecodeBytes),
SyncedStorage: progress.StorageSynced,
SyncedStorageBytes: uint64(progress.StorageBytes),
HealedTrienodes: progress.TrienodeHealSynced,
HealedTrienodeBytes: uint64(progress.TrienodeHealBytes),
HealedBytecodes: progress.BytecodeHealSynced,
HealedBytecodeBytes: uint64(progress.BytecodeHealBytes),
HealingTrienodes: pending.TrienodeHeal,
HealingBytecode: pending.BytecodeHeal,
}
}
// RegisterPeer injects a new download peer into the set of block source to be
// used for fetching hashes and blocks from.
func (d *Downloader) RegisterPeer(id string, version uint, peer Peer) error {
var logger log.Logger
if len(id) < 16 {
// Tests use short IDs, don't choke on them
logger = log.New("peer", id)
} else {
logger = log.New("peer", id[:8])
}
logger.Trace("Registering sync peer")
if err := d.peers.Register(newPeerConnection(id, version, peer, logger)); err != nil {
logger.Error("Failed to register sync peer", "err", err)
return err
}
return nil
}
// UnregisterPeer remove a peer from the known list, preventing any action from
// the specified peer. An effort is also made to return any pending fetches into
// the queue.
func (d *Downloader) UnregisterPeer(id string) error {
// Unregister the peer from the active peer set and revoke any fetch tasks
var logger log.Logger
if len(id) < 16 {
// Tests use short IDs, don't choke on them
logger = log.New("peer", id)
} else {
logger = log.New("peer", id[:8])
}
logger.Trace("Unregistering sync peer")
if err := d.peers.Unregister(id); err != nil {
logger.Error("Failed to unregister sync peer", "err", err)
return err
}
d.queue.Revoke(id)
return nil
}
// LegacySync tries to sync up our local block chain with a remote peer, both
// adding various sanity checks as well as wrapping it with various log entries.
func (d *Downloader) LegacySync(id string, head common.Hash, td, ttd *big.Int, mode SyncMode) error {
err := d.synchronise(id, head, td, ttd, mode, false, nil)
switch err {
case nil, errBusy, errCanceled:
return err
}
if errors.Is(err, errInvalidChain) || errors.Is(err, errBadPeer) || errors.Is(err, errTimeout) ||
errors.Is(err, errStallingPeer) || errors.Is(err, errUnsyncedPeer) || errors.Is(err, errEmptyHeaderSet) ||
errors.Is(err, errPeersUnavailable) || errors.Is(err, errTooOld) || errors.Is(err, errInvalidAncestor) {
log.Warn("Synchronisation failed, dropping peer", "peer", id, "err", err)
if d.dropPeer == nil {
// The dropPeer method is nil when `--copydb` is used for a local copy.
// Timeouts can occur if e.g. compaction hits at the wrong time, and can be ignored
log.Warn("Downloader wants to drop peer, but peerdrop-function is not set", "peer", id)
} else {
d.dropPeer(id)
}
return err
}
if errors.Is(err, ErrMergeTransition) {
return err // This is an expected fault, don't keep printing it in a spin-loop
}
log.Warn("Synchronisation failed, retrying", "err", err)
return err
}
// synchronise will select the peer and use it for synchronising. If an empty string is given
// it will use the best peer possible and synchronize if its TD is higher than our own. If any of the
// checks fail an error will be returned. This method is synchronous
func (d *Downloader) synchronise(id string, hash common.Hash, td, ttd *big.Int, mode SyncMode, beaconMode bool, beaconPing chan struct{}) error {
// The beacon header syncer is async. It will start this synchronization and
// will continue doing other tasks. However, if synchronization needs to be
// cancelled, the syncer needs to know if we reached the startup point (and
// inited the cancel channel) or not yet. Make sure that we'll signal even in
// case of a failure.
if beaconPing != nil {
defer func() {
select {
case <-beaconPing: // already notified
default:
close(beaconPing) // weird exit condition, notify that it's safe to cancel (the nothing)
}
}()
}
// Mock out the synchronisation if testing
if d.synchroniseMock != nil {
return d.synchroniseMock(id, hash)
}
// Make sure only one goroutine is ever allowed past this point at once
if !d.synchronising.CompareAndSwap(false, true) {
return errBusy
}
defer d.synchronising.Store(false)
// Post a user notification of the sync (only once per session)
if d.notified.CompareAndSwap(false, true) {
log.Info("Block synchronisation started")
}
if mode == SnapSync {
// Snap sync will directly modify the persistent state, making the entire
// trie database unusable until the state is fully synced. To prevent any
// subsequent state reads, explicitly disable the trie database and state
// syncer is responsible to address and correct any state missing.
if d.blockchain.TrieDB().Scheme() == rawdb.PathScheme {
if err := d.blockchain.TrieDB().Disable(); err != nil {
return err
}
}
// Snap sync uses the snapshot namespace to store potentially flaky data until
// sync completely heals and finishes. Pause snapshot maintenance in the mean-
// time to prevent access.
if snapshots := d.blockchain.Snapshots(); snapshots != nil { // Only nil in tests
snapshots.Disable()
}
}
// Reset the queue, peer set and wake channels to clean any internal leftover state
d.queue.Reset(blockCacheMaxItems, blockCacheInitialItems)
d.peers.Reset()
for _, ch := range []chan bool{d.queue.blockWakeCh, d.queue.receiptWakeCh} {
select {
case <-ch:
default:
}
}
for empty := false; !empty; {
select {
case <-d.headerProcCh:
default:
empty = true
}
}
// Create cancel channel for aborting mid-flight and mark the master peer
d.cancelLock.Lock()
d.cancelCh = make(chan struct{})
d.cancelPeer = id
d.cancelLock.Unlock()
defer d.Cancel() // No matter what, we can't leave the cancel channel open
// Atomically set the requested sync mode
d.mode.Store(uint32(mode))
// Retrieve the origin peer and initiate the downloading process
var p *peerConnection
if !beaconMode { // Beacon mode doesn't need a peer to sync from
p = d.peers.Peer(id)
if p == nil {
return errUnknownPeer
}
}
if beaconPing != nil {
close(beaconPing)
}
return d.syncWithPeer(p, hash, td, ttd, beaconMode)
}
func (d *Downloader) getMode() SyncMode {
return SyncMode(d.mode.Load())
}
// syncWithPeer starts a block synchronization based on the hash chain from the
// specified peer and head hash.
func (d *Downloader) syncWithPeer(p *peerConnection, hash common.Hash, td, ttd *big.Int, beaconMode bool) (err error) {
d.mux.Post(StartEvent{})
defer func() {
// reset on error
if err != nil {
d.mux.Post(FailedEvent{err})
} else {
latest := d.lightchain.CurrentHeader()
d.mux.Post(DoneEvent{latest})
}
}()
mode := d.getMode()
if !beaconMode {
log.Debug("Synchronising with the network", "peer", p.id, "eth", p.version, "head", hash, "td", td, "mode", mode)
} else {
log.Debug("Backfilling with the network", "mode", mode)
}
defer func(start time.Time) {
log.Debug("Synchronisation terminated", "elapsed", common.PrettyDuration(time.Since(start)))
}(time.Now())
// Look up the sync boundaries: the common ancestor and the target block
var latest, pivot, final *types.Header
if !beaconMode {
// In legacy mode, use the master peer to retrieve the headers from
latest, pivot, err = d.fetchHead(p)
if err != nil {
return err
}
} else {
// In beacon mode, use the skeleton chain to retrieve the headers from
latest, _, final, err = d.skeleton.Bounds()
if err != nil {
return err
}
if latest.Number.Uint64() > uint64(fsMinFullBlocks) {
number := latest.Number.Uint64() - uint64(fsMinFullBlocks)
// Retrieve the pivot header from the skeleton chain segment but
// fallback to local chain if it's not found in skeleton space.
if pivot = d.skeleton.Header(number); pivot == nil {
_, oldest, _, _ := d.skeleton.Bounds() // error is already checked
if number < oldest.Number.Uint64() {
count := int(oldest.Number.Uint64() - number) // it's capped by fsMinFullBlocks
headers := d.readHeaderRange(oldest, count)
if len(headers) == count {
pivot = headers[len(headers)-1]
log.Warn("Retrieved pivot header from local", "number", pivot.Number, "hash", pivot.Hash(), "latest", latest.Number, "oldest", oldest.Number)
}
}
}
// Print an error log and return directly in case the pivot header
// is still not found. It means the skeleton chain is not linked
// correctly with local chain.
if pivot == nil {
log.Error("Pivot header is not found", "number", number)
return errNoPivotHeader
}
}
}
// If no pivot block was returned, the head is below the min full block
// threshold (i.e. new chain). In that case we won't really snap sync
// anyway, but still need a valid pivot block to avoid some code hitting
// nil panics on access.
if mode == SnapSync && pivot == nil {
pivot = d.blockchain.CurrentBlock()
}
height := latest.Number.Uint64()
var origin uint64
if !beaconMode {
// In legacy mode, reach out to the network and find the ancestor
origin, err = d.findAncestor(p, latest)
if err != nil {
return err
}
} else {
// In beacon mode, use the skeleton chain for the ancestor lookup
origin, err = d.findBeaconAncestor()
if err != nil {
return err
}
}
d.syncStatsLock.Lock()
if d.syncStatsChainHeight <= origin || d.syncStatsChainOrigin > origin {
d.syncStatsChainOrigin = origin
}
d.syncStatsChainHeight = height
d.syncStatsLock.Unlock()
// Ensure our origin point is below any snap sync pivot point
if mode == SnapSync {
if height <= uint64(fsMinFullBlocks) {
origin = 0
} else {
pivotNumber := pivot.Number.Uint64()
if pivotNumber <= origin {
origin = pivotNumber - 1
}
// Write out the pivot into the database so a rollback beyond it will
// reenable snap sync
rawdb.WriteLastPivotNumber(d.stateDB, pivotNumber)
}
}
d.committed.Store(true)
if mode == SnapSync && pivot.Number.Uint64() != 0 {
d.committed.Store(false)
}
if mode == SnapSync {
// Set the ancient data limitation. If we are running snap sync, all block
// data older than ancientLimit will be written to the ancient store. More
// recent data will be written to the active database and will wait for the
// freezer to migrate.
//
// If the network is post-merge, use either the last announced finalized
// block as the ancient limit, or if we haven't yet received one, the head-
// a max fork ancestry limit. One quirky case if we've already passed the
// finalized block, in which case the skeleton.Bounds will return nil and
// we'll revert to head - 90K. That's fine, we're finishing sync anyway.
//
// For non-merged networks, if there is a checkpoint available, then calculate
// the ancientLimit through that. Otherwise calculate the ancient limit through
// the advertised height of the remote peer. This most is mostly a fallback for
// legacy networks, but should eventually be droppped. TODO(karalabe).
if beaconMode {
// Beacon sync, use the latest finalized block as the ancient limit
// or a reasonable height if no finalized block is yet announced.
if final != nil {
d.ancientLimit = final.Number.Uint64()
} else if height > fullMaxForkAncestry+1 {
d.ancientLimit = height - fullMaxForkAncestry - 1
} else {
d.ancientLimit = 0
}
} else {
// Legacy sync, use the best announcement we have from the remote peer.
// TODO(karalabe): Drop this pathway.
if height > fullMaxForkAncestry+1 {
d.ancientLimit = height - fullMaxForkAncestry - 1
} else {
d.ancientLimit = 0
}
}
frozen, _ := d.stateDB.Ancients() // Ignore the error here since light client can also hit here.
// If a part of blockchain data has already been written into active store,
// disable the ancient style insertion explicitly.
if origin >= frozen && frozen != 0 {
d.ancientLimit = 0
log.Info("Disabling direct-ancient mode", "origin", origin, "ancient", frozen-1)
} else if d.ancientLimit > 0 {
log.Debug("Enabling direct-ancient mode", "ancient", d.ancientLimit)
}
// Rewind the ancient store and blockchain if reorg happens.
if origin+1 < frozen {
if err := d.lightchain.SetHead(origin); err != nil {
return err
}
}
}
// Initiate the sync using a concurrent header and content retrieval algorithm
d.queue.Prepare(origin+1, mode)
if d.syncInitHook != nil {
d.syncInitHook(origin, height)
}
var headerFetcher func() error
if !beaconMode {
// In legacy mode, headers are retrieved from the network
headerFetcher = func() error { return d.fetchHeaders(p, origin+1, latest.Number.Uint64()) }
} else {
// In beacon mode, headers are served by the skeleton syncer
headerFetcher = func() error { return d.fetchBeaconHeaders(origin + 1) }
}
fetchers := []func() error{
headerFetcher, // Headers are always retrieved
func() error { return d.fetchBodies(origin+1, beaconMode) }, // Bodies are retrieved during normal and snap sync
func() error { return d.fetchReceipts(origin+1, beaconMode) }, // Receipts are retrieved during snap sync
func() error { return d.processHeaders(origin+1, td, ttd, beaconMode) },
}
if mode == SnapSync {
d.pivotLock.Lock()
d.pivotHeader = pivot
d.pivotLock.Unlock()
fetchers = append(fetchers, func() error { return d.processSnapSyncContent() })
} else if mode == FullSync {
fetchers = append(fetchers, func() error { return d.processFullSyncContent(ttd, beaconMode) })
}
return d.spawnSync(fetchers)
}
// spawnSync runs d.process and all given fetcher functions to completion in
// separate goroutines, returning the first error that appears.
func (d *Downloader) spawnSync(fetchers []func() error) error {
errc := make(chan error, len(fetchers))
d.cancelWg.Add(len(fetchers))
for _, fn := range fetchers {
fn := fn
go func() { defer d.cancelWg.Done(); errc <- fn() }()
}
// Wait for the first error, then terminate the others.
var err error
for i := 0; i < len(fetchers); i++ {
if i == len(fetchers)-1 {
// Close the queue when all fetchers have exited.
// This will cause the block processor to end when
// it has processed the queue.
d.queue.Close()
}
if got := <-errc; got != nil {
err = got
if got != errCanceled {
break // receive a meaningful error, bubble it up
}
}
}
d.queue.Close()
d.Cancel()
return err
}
// cancel aborts all of the operations and resets the queue. However, cancel does
// not wait for the running download goroutines to finish. This method should be
// used when cancelling the downloads from inside the downloader.
func (d *Downloader) cancel() {
// Close the current cancel channel
d.cancelLock.Lock()
defer d.cancelLock.Unlock()
if d.cancelCh != nil {
select {
case <-d.cancelCh:
// Channel was already closed
default:
close(d.cancelCh)
}
}
}
// Cancel aborts all of the operations and waits for all download goroutines to
// finish before returning.
func (d *Downloader) Cancel() {
d.cancel()
d.cancelWg.Wait()
}
// Terminate interrupts the downloader, canceling all pending operations.
// The downloader cannot be reused after calling Terminate.
func (d *Downloader) Terminate() {
// Close the termination channel (make sure double close is allowed)
d.quitLock.Lock()
select {
case <-d.quitCh:
default:
close(d.quitCh)
// Terminate the internal beacon syncer
d.skeleton.Terminate()
}
d.quitLock.Unlock()
// Cancel any pending download requests
d.Cancel()
}
// fetchHead retrieves the head header and prior pivot block (if available) from
// a remote peer.
func (d *Downloader) fetchHead(p *peerConnection) (head *types.Header, pivot *types.Header, err error) {
p.log.Debug("Retrieving remote chain head")
mode := d.getMode()
// Request the advertised remote head block and wait for the response
latest, _ := p.peer.Head()
fetch := 1
if mode == SnapSync {
fetch = 2 // head + pivot headers
}
headers, hashes, err := d.fetchHeadersByHash(p, latest, fetch, fsMinFullBlocks-1, true)
if err != nil {
return nil, nil, err
}
// Make sure the peer gave us at least one and at most the requested headers
if len(headers) == 0 || len(headers) > fetch {
return nil, nil, fmt.Errorf("%w: returned headers %d != requested %d", errBadPeer, len(headers), fetch)
}
// The first header needs to be the head, validate against the request. If
// only 1 header was returned, make sure there's no pivot or there was not
// one requested.
head = headers[0]
if len(headers) == 1 {
if mode == SnapSync && head.Number.Uint64() > uint64(fsMinFullBlocks) {
return nil, nil, fmt.Errorf("%w: no pivot included along head header", errBadPeer)
}
p.log.Debug("Remote head identified, no pivot", "number", head.Number, "hash", hashes[0])
return head, nil, nil
}
// At this point we have 2 headers in total and the first is the
// validated head of the chain. Check the pivot number and return,
pivot = headers[1]
if pivot.Number.Uint64() != head.Number.Uint64()-uint64(fsMinFullBlocks) {
return nil, nil, fmt.Errorf("%w: remote pivot %d != requested %d", errInvalidChain, pivot.Number, head.Number.Uint64()-uint64(fsMinFullBlocks))
}
return head, pivot, nil
}
// calculateRequestSpan calculates what headers to request from a peer when trying to determine the
// common ancestor.
// It returns parameters to be used for peer.RequestHeadersByNumber:
//
// from - starting block number
// count - number of headers to request
// skip - number of headers to skip
//
// and also returns 'max', the last block which is expected to be returned by the remote peers,
// given the (from,count,skip)
func calculateRequestSpan(remoteHeight, localHeight uint64) (int64, int, int, uint64) {
var (
from int
count int
MaxCount = MaxHeaderFetch / 16
)
// requestHead is the highest block that we will ask for. If requestHead is not offset,
// the highest block that we will get is 16 blocks back from head, which means we
// will fetch 14 or 15 blocks unnecessarily in the case the height difference
// between us and the peer is 1-2 blocks, which is most common
requestHead := int(remoteHeight) - 1
if requestHead < 0 {
requestHead = 0
}
// requestBottom is the lowest block we want included in the query
// Ideally, we want to include the one just below our own head
requestBottom := int(localHeight - 1)
if requestBottom < 0 {
requestBottom = 0
}
totalSpan := requestHead - requestBottom
span := 1 + totalSpan/MaxCount
if span < 2 {
span = 2
}
if span > 16 {
span = 16
}
count = 1 + totalSpan/span
if count > MaxCount {
count = MaxCount
}
if count < 2 {
count = 2
}
from = requestHead - (count-1)*span
if from < 0 {
from = 0
}
max := from + (count-1)*span
return int64(from), count, span - 1, uint64(max)
}
// findAncestor tries to locate the common ancestor link of the local chain and
// a remote peers blockchain. In the general case when our node was in sync and
// on the correct chain, checking the top N links should already get us a match.
// In the rare scenario when we ended up on a long reorganisation (i.e. none of
// the head links match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor(p *peerConnection, remoteHeader *types.Header) (uint64, error) {
// Figure out the valid ancestor range to prevent rewrite attacks
var (
floor = int64(-1)
localHeight uint64
remoteHeight = remoteHeader.Number.Uint64()
)
mode := d.getMode()
switch mode {
case FullSync:
localHeight = d.blockchain.CurrentBlock().Number.Uint64()
case SnapSync:
localHeight = d.blockchain.CurrentSnapBlock().Number.Uint64()
default:
localHeight = d.lightchain.CurrentHeader().Number.Uint64()
}
p.log.Debug("Looking for common ancestor", "local", localHeight, "remote", remoteHeight)
// Recap floor value for binary search
maxForkAncestry := fullMaxForkAncestry
if d.getMode() == LightSync {
maxForkAncestry = lightMaxForkAncestry
}
if localHeight >= maxForkAncestry {
// We're above the max reorg threshold, find the earliest fork point
floor = int64(localHeight - maxForkAncestry)
}
// If we're doing a light sync, ensure the floor doesn't go below the CHT, as
// all headers before that point will be missing.
if mode == LightSync {
// If we don't know the current CHT position, find it
if d.genesis == 0 {
header := d.lightchain.CurrentHeader()
for header != nil {
d.genesis = header.Number.Uint64()
if floor >= int64(d.genesis)-1 {
break
}
header = d.lightchain.GetHeaderByHash(header.ParentHash)
}
}
// We already know the "genesis" block number, cap floor to that
if floor < int64(d.genesis)-1 {
floor = int64(d.genesis) - 1
}
}
ancestor, err := d.findAncestorSpanSearch(p, mode, remoteHeight, localHeight, floor)
if err == nil {
return ancestor, nil
}
// The returned error was not nil.
// If the error returned does not reflect that a common ancestor was not found, return it.
// If the error reflects that a common ancestor was not found, continue to binary search,
// where the error value will be reassigned.
if !errors.Is(err, errNoAncestorFound) {
return 0, err
}
ancestor, err = d.findAncestorBinarySearch(p, mode, remoteHeight, floor)
if err != nil {
return 0, err
}
return ancestor, nil
}
func (d *Downloader) findAncestorSpanSearch(p *peerConnection, mode SyncMode, remoteHeight, localHeight uint64, floor int64) (uint64, error) {
from, count, skip, max := calculateRequestSpan(remoteHeight, localHeight)
p.log.Trace("Span searching for common ancestor", "count", count, "from", from, "skip", skip)
headers, hashes, err := d.fetchHeadersByNumber(p, uint64(from), count, skip, false)
if err != nil {
return 0, err
}
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
// Make sure the peer actually gave something valid
if len(headers) == 0 {
p.log.Warn("Empty head header set")
return 0, errEmptyHeaderSet
}
// Make sure the peer's reply conforms to the request
for i, header := range headers {
expectNumber := from + int64(i)*int64(skip+1)
if number := header.Number.Int64(); number != expectNumber {
p.log.Warn("Head headers broke chain ordering", "index", i, "requested", expectNumber, "received", number)
return 0, fmt.Errorf("%w: %v", errInvalidChain, errors.New("head headers broke chain ordering"))
}
}
// Check if a common ancestor was found
for i := len(headers) - 1; i >= 0; i-- {
// Skip any headers that underflow/overflow our requested set
if headers[i].Number.Int64() < from || headers[i].Number.Uint64() > max {
continue
}
// Otherwise check if we already know the header or not
h := hashes[i]
n := headers[i].Number.Uint64()
var known bool
switch mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case SnapSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if known {
number, hash = n, h
break
}
}
// If the head fetch already found an ancestor, return
if hash != (common.Hash{}) {
if int64(number) <= floor {
p.log.Warn("Ancestor below allowance", "number", number, "hash", hash, "allowance", floor)
return 0, errInvalidAncestor
}
p.log.Debug("Found common ancestor", "number", number, "hash", hash)
return number, nil
}
return 0, errNoAncestorFound
}
func (d *Downloader) findAncestorBinarySearch(p *peerConnection, mode SyncMode, remoteHeight uint64, floor int64) (uint64, error) {
hash := common.Hash{}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), remoteHeight
if floor > 0 {
start = uint64(floor)
}
p.log.Trace("Binary searching for common ancestor", "start", start, "end", end)
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
headers, hashes, err := d.fetchHeadersByNumber(p, check, 1, 0, false)
if err != nil {
return 0, err
}
// Make sure the peer actually gave something valid
if len(headers) != 1 {
p.log.Warn("Multiple headers for single request", "headers", len(headers))
return 0, fmt.Errorf("%w: multiple headers (%d) for single request", errBadPeer, len(headers))
}
// Modify the search interval based on the response
h := hashes[0]
n := headers[0].Number.Uint64()
var known bool
switch mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case SnapSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if !known {
end = check
continue
}
header := d.lightchain.GetHeaderByHash(h) // Independent of sync mode, header surely exists
if header.Number.Uint64() != check {
p.log.Warn("Received non requested header", "number", header.Number, "hash", header.Hash(), "request", check)
return 0, fmt.Errorf("%w: non-requested header (%d)", errBadPeer, header.Number)
}
start = check
hash = h
}
// Ensure valid ancestry and return
if int64(start) <= floor {
p.log.Warn("Ancestor below allowance", "number", start, "hash", hash, "allowance", floor)
return 0, errInvalidAncestor
}
p.log.Debug("Found common ancestor", "number", start, "hash", hash)
return start, nil
}
// fetchHeaders keeps retrieving headers concurrently from the number
// requested, until no more are returned, potentially throttling on the way. To
// facilitate concurrency but still protect against malicious nodes sending bad
// headers, we construct a header chain skeleton using the "origin" peer we are
// syncing with, and fill in the missing headers using anyone else. Headers from
// other peers are only accepted if they map cleanly to the skeleton. If no one
// can fill in the skeleton - not even the origin peer - it's assumed invalid and
// the origin is dropped.
func (d *Downloader) fetchHeaders(p *peerConnection, from uint64, head uint64) error {
p.log.Debug("Directing header downloads", "origin", from)
defer p.log.Debug("Header download terminated")
// Start pulling the header chain skeleton until all is done
var (
skeleton = true // Skeleton assembly phase or finishing up
pivoting = false // Whether the next request is pivot verification
ancestor = from
mode = d.getMode()
)
for {
// Pull the next batch of headers, it either:
// - Pivot check to see if the chain moved too far
// - Skeleton retrieval to permit concurrent header fetches
// - Full header retrieval if we're near the chain head
var (
headers []*types.Header
hashes []common.Hash
err error
)
switch {
case pivoting:
d.pivotLock.RLock()
pivot := d.pivotHeader.Number.Uint64()
d.pivotLock.RUnlock()
p.log.Trace("Fetching next pivot header", "number", pivot+uint64(fsMinFullBlocks))
headers, hashes, err = d.fetchHeadersByNumber(p, pivot+uint64(fsMinFullBlocks), 2, fsMinFullBlocks-9, false) // move +64 when it's 2x64-8 deep
case skeleton:
p.log.Trace("Fetching skeleton headers", "count", MaxHeaderFetch, "from", from)
headers, hashes, err = d.fetchHeadersByNumber(p, from+uint64(MaxHeaderFetch)-1, MaxSkeletonSize, MaxHeaderFetch-1, false)
default:
p.log.Trace("Fetching full headers", "count", MaxHeaderFetch, "from", from)
headers, hashes, err = d.fetchHeadersByNumber(p, from, MaxHeaderFetch, 0, false)
}
switch err {
case nil:
// Headers retrieved, continue with processing
case errCanceled:
// Sync cancelled, no issue, propagate up
return err
default:
// Header retrieval either timed out, or the peer failed in some strange way
// (e.g. disconnect). Consider the master peer bad and drop
d.dropPeer(p.id)
// Finish the sync gracefully instead of dumping the gathered data though
for _, ch := range []chan bool{d.queue.blockWakeCh, d.queue.receiptWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
select {
case d.headerProcCh <- nil:
case <-d.cancelCh:
}
return fmt.Errorf("%w: header request failed: %v", errBadPeer, err)
}
// If the pivot is being checked, move if it became stale and run the real retrieval
var pivot uint64
d.pivotLock.RLock()
if d.pivotHeader != nil {
pivot = d.pivotHeader.Number.Uint64()
}
d.pivotLock.RUnlock()
if pivoting {
if len(headers) == 2 {
if have, want := headers[0].Number.Uint64(), pivot+uint64(fsMinFullBlocks); have != want {
log.Warn("Peer sent invalid next pivot", "have", have, "want", want)
return fmt.Errorf("%w: next pivot number %d != requested %d", errInvalidChain, have, want)
}
if have, want := headers[1].Number.Uint64(), pivot+2*uint64(fsMinFullBlocks)-8; have != want {
log.Warn("Peer sent invalid pivot confirmer", "have", have, "want", want)
return fmt.Errorf("%w: next pivot confirmer number %d != requested %d", errInvalidChain, have, want)
}
log.Warn("Pivot seemingly stale, moving", "old", pivot, "new", headers[0].Number)
pivot = headers[0].Number.Uint64()
d.pivotLock.Lock()
d.pivotHeader = headers[0]
d.pivotLock.Unlock()
// Write out the pivot into the database so a rollback beyond
// it will reenable snap sync and update the state root that
// the state syncer will be downloading.
rawdb.WriteLastPivotNumber(d.stateDB, pivot)
}
// Disable the pivot check and fetch the next batch of headers
pivoting = false
continue
}
// If the skeleton's finished, pull any remaining head headers directly from the origin
if skeleton && len(headers) == 0 {
// A malicious node might withhold advertised headers indefinitely
if from+uint64(MaxHeaderFetch)-1 <= head {
p.log.Warn("Peer withheld skeleton headers", "advertised", head, "withheld", from+uint64(MaxHeaderFetch)-1)
return fmt.Errorf("%w: withheld skeleton headers: advertised %d, withheld #%d", errStallingPeer, head, from+uint64(MaxHeaderFetch)-1)
}
p.log.Debug("No skeleton, fetching headers directly")
skeleton = false
continue
}
// If no more headers are inbound, notify the content fetchers and return
if len(headers) == 0 {
// Don't abort header fetches while the pivot is downloading
if !d.committed.Load() && pivot <= from {
p.log.Debug("No headers, waiting for pivot commit")
select {
case <-time.After(fsHeaderContCheck):
continue
case <-d.cancelCh:
return errCanceled
}
}
// Pivot done (or not in snap sync) and no more headers, terminate the process
p.log.Debug("No more headers available")
select {
case d.headerProcCh <- nil:
return nil
case <-d.cancelCh:
return errCanceled
}
}
// If we received a skeleton batch, resolve internals concurrently
var progressed bool
if skeleton {
filled, hashset, proced, err := d.fillHeaderSkeleton(from, headers)
if err != nil {
p.log.Debug("Skeleton chain invalid", "err", err)
return fmt.Errorf("%w: %v", errInvalidChain, err)
}
headers = filled[proced:]
hashes = hashset[proced:]
progressed = proced > 0
from += uint64(proced)
} else {
// A malicious node might withhold advertised headers indefinitely
if n := len(headers); n < MaxHeaderFetch && headers[n-1].Number.Uint64() < head {
p.log.Warn("Peer withheld headers", "advertised", head, "delivered", headers[n-1].Number.Uint64())
return fmt.Errorf("%w: withheld headers: advertised %d, delivered %d", errStallingPeer, head, headers[n-1].Number.Uint64())
}
// If we're closing in on the chain head, but haven't yet reached it, delay
// the last few headers so mini reorgs on the head don't cause invalid hash
// chain errors.
if n := len(headers); n > 0 {
// Retrieve the current head we're at
var head uint64
if mode == LightSync {
head = d.lightchain.CurrentHeader().Number.Uint64()
} else {
head = d.blockchain.CurrentSnapBlock().Number.Uint64()
if full := d.blockchain.CurrentBlock().Number.Uint64(); head < full {
head = full
}
}
// If the head is below the common ancestor, we're actually deduplicating
// already existing chain segments, so use the ancestor as the fake head.
// Otherwise, we might end up delaying header deliveries pointlessly.
if head < ancestor {
head = ancestor
}
// If the head is way older than this batch, delay the last few headers
if head+uint64(reorgProtThreshold) < headers[n-1].Number.Uint64() {
delay := reorgProtHeaderDelay
if delay > n {
delay = n
}
headers = headers[:n-delay]
hashes = hashes[:n-delay]
}
}
}
// If no headers have been delivered, or all of them have been delayed,
// sleep a bit and retry. Take care with headers already consumed during
// skeleton filling
if len(headers) == 0 && !progressed {
p.log.Trace("All headers delayed, waiting")
select {
case <-time.After(fsHeaderContCheck):
continue
case <-d.cancelCh:
return errCanceled
}
}
// Insert any remaining new headers and fetch the next batch
if len(headers) > 0 {
p.log.Trace("Scheduling new headers", "count", len(headers), "from", from)
select {
case d.headerProcCh <- &headerTask{
headers: headers,
hashes: hashes,
}:
case <-d.cancelCh:
return errCanceled
}
from += uint64(len(headers))
}
// If we're still skeleton filling snap sync, check pivot staleness
// before continuing to the next skeleton filling
if skeleton && pivot > 0 {
pivoting = true
}
}
}
// fillHeaderSkeleton concurrently retrieves headers from all our available peers
// and maps them to the provided skeleton header chain.
//
// Any partial results from the beginning of the skeleton is (if possible) forwarded
// immediately to the header processor to keep the rest of the pipeline full even
// in the case of header stalls.
//
// The method returns the entire filled skeleton and also the number of headers
// already forwarded for processing.
func (d *Downloader) fillHeaderSkeleton(from uint64, skeleton []*types.Header) ([]*types.Header, []common.Hash, int, error) {
log.Debug("Filling up skeleton", "from", from)
d.queue.ScheduleSkeleton(from, skeleton)
err := d.concurrentFetch((*headerQueue)(d), false)
if err != nil {
log.Debug("Skeleton fill failed", "err", err)
}
filled, hashes, proced := d.queue.RetrieveHeaders()
if err == nil {
log.Debug("Skeleton fill succeeded", "filled", len(filled), "processed", proced)
}
return filled, hashes, proced, err
}
// fetchBodies iteratively downloads the scheduled block bodies, taking any
// available peers, reserving a chunk of blocks for each, waiting for delivery
// and also periodically checking for timeouts.
func (d *Downloader) fetchBodies(from uint64, beaconMode bool) error {
log.Debug("Downloading block bodies", "origin", from)
err := d.concurrentFetch((*bodyQueue)(d), beaconMode)
log.Debug("Block body download terminated", "err", err)
return err
}
// fetchReceipts iteratively downloads the scheduled block receipts, taking any
// available peers, reserving a chunk of receipts for each, waiting for delivery
// and also periodically checking for timeouts.
func (d *Downloader) fetchReceipts(from uint64, beaconMode bool) error {
log.Debug("Downloading receipts", "origin", from)
err := d.concurrentFetch((*receiptQueue)(d), beaconMode)
log.Debug("Receipt download terminated", "err", err)
return err
}
// processHeaders takes batches of retrieved headers from an input channel and
// keeps processing and scheduling them into the header chain and downloader's
// queue until the stream ends or a failure occurs.
func (d *Downloader) processHeaders(origin uint64, td, ttd *big.Int, beaconMode bool) error {
var (
mode = d.getMode()
gotHeaders = false // Wait for batches of headers to process
)
for {
select {
case <-d.cancelCh:
return errCanceled
case task := <-d.headerProcCh:
// Terminate header processing if we synced up
if task == nil || len(task.headers) == 0 {
// Notify everyone that headers are fully processed
for _, ch := range []chan bool{d.queue.blockWakeCh, d.queue.receiptWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
// If we're in legacy sync mode, we need to check total difficulty
// violations from malicious peers. That is not needed in beacon
// mode and we can skip to terminating sync.
if !beaconMode {
// If no headers were retrieved at all, the peer violated its TD promise that it had a
// better chain compared to ours. The only exception is if its promised blocks were
// already imported by other means (e.g. fetcher):
//
// R <remote peer>, L <local node>: Both at block 10
// R: Mine block 11, and propagate it to L
// L: Queue block 11 for import
// L: Notice that R's head and TD increased compared to ours, start sync
// L: Import of block 11 finishes
// L: Sync begins, and finds common ancestor at 11
// L: Request new headers up from 11 (R's TD was higher, it must have something)
// R: Nothing to give
if mode != LightSync {
head := d.blockchain.CurrentBlock()
if !gotHeaders && td.Cmp(d.blockchain.GetTd(head.Hash(), head.Number.Uint64())) > 0 {
return errStallingPeer
}
}
// If snap or light syncing, ensure promised headers are indeed delivered. This is
// needed to detect scenarios where an attacker feeds a bad pivot and then bails out
// of delivering the post-pivot blocks that would flag the invalid content.
//
// This check cannot be executed "as is" for full imports, since blocks may still be
// queued for processing when the header download completes. However, as long as the
// peer gave us something useful, we're already happy/progressed (above check).
if mode == SnapSync || mode == LightSync {
head := d.lightchain.CurrentHeader()
if td.Cmp(d.lightchain.GetTd(head.Hash(), head.Number.Uint64())) > 0 {
return errStallingPeer
}
}
}
return nil
}
// Otherwise split the chunk of headers into batches and process them
headers, hashes := task.headers, task.hashes
gotHeaders = true
for len(headers) > 0 {
// Terminate if something failed in between processing chunks
select {
case <-d.cancelCh:
return errCanceled
default:
}
// Select the next chunk of headers to import
limit := maxHeadersProcess
if limit > len(headers) {
limit = len(headers)
}
chunkHeaders := headers[:limit]
chunkHashes := hashes[:limit]
// In case of header only syncing, validate the chunk immediately
if mode == SnapSync || mode == LightSync {
// Although the received headers might be all valid, a legacy
// PoW/PoA sync must not accept post-merge headers. Make sure
// that any transition is rejected at this point.
var (
rejected []*types.Header
td *big.Int
)
if !beaconMode && ttd != nil {
td = d.blockchain.GetTd(chunkHeaders[0].ParentHash, chunkHeaders[0].Number.Uint64()-1)
if td == nil {
// This should never really happen, but handle gracefully for now
log.Error("Failed to retrieve parent header TD", "number", chunkHeaders[0].Number.Uint64()-1, "hash", chunkHeaders[0].ParentHash)
return fmt.Errorf("%w: parent TD missing", errInvalidChain)
}
for i, header := range chunkHeaders {
td = new(big.Int).Add(td, header.Difficulty)
if td.Cmp(ttd) >= 0 {
// Terminal total difficulty reached, allow the last header in
if new(big.Int).Sub(td, header.Difficulty).Cmp(ttd) < 0 {
chunkHeaders, rejected = chunkHeaders[:i+1], chunkHeaders[i+1:]
if len(rejected) > 0 {
// Make a nicer user log as to the first TD truly rejected
td = new(big.Int).Add(td, rejected[0].Difficulty)
}
} else {
chunkHeaders, rejected = chunkHeaders[:i], chunkHeaders[i:]
}
break
}
}
}
if len(chunkHeaders) > 0 {
if n, err := d.lightchain.InsertHeaderChain(chunkHeaders); err != nil {
log.Warn("Invalid header encountered", "number", chunkHeaders[n].Number, "hash", chunkHashes[n], "parent", chunkHeaders[n].ParentHash, "err", err)
return fmt.Errorf("%w: %v", errInvalidChain, err)
}
}
if len(rejected) != 0 {
log.Info("Legacy sync reached merge threshold", "number", rejected[0].Number, "hash", rejected[0].Hash(), "td", td, "ttd", ttd)
return ErrMergeTransition
}
}
// Unless we're doing light chains, schedule the headers for associated content retrieval
if mode == FullSync || mode == SnapSync {
// If we've reached the allowed number of pending headers, stall a bit
for d.queue.PendingBodies() >= maxQueuedHeaders || d.queue.PendingReceipts() >= maxQueuedHeaders {
select {
case <-d.cancelCh:
return errCanceled
case <-time.After(time.Second):
}
}
// Otherwise insert the headers for content retrieval
inserts := d.queue.Schedule(chunkHeaders, chunkHashes, origin)
if len(inserts) != len(chunkHeaders) {
return fmt.Errorf("%w: stale headers", errBadPeer)
}
}
headers = headers[limit:]
hashes = hashes[limit:]
origin += uint64(limit)
}
// Update the highest block number we know if a higher one is found.
d.syncStatsLock.Lock()
if d.syncStatsChainHeight < origin {
d.syncStatsChainHeight = origin - 1
}
d.syncStatsLock.Unlock()
// Signal the content downloaders of the availability of new tasks
for _, ch := range []chan bool{d.queue.blockWakeCh, d.queue.receiptWakeCh} {
select {
case ch <- true:
default:
}
}
}
}
}
// processFullSyncContent takes fetch results from the queue and imports them into the chain.
func (d *Downloader) processFullSyncContent(ttd *big.Int, beaconMode bool) error {
for {
results := d.queue.Results(true)
if len(results) == 0 {
return nil
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
// Although the received blocks might be all valid, a legacy PoW/PoA sync
// must not accept post-merge blocks. Make sure that pre-merge blocks are
// imported, but post-merge ones are rejected.
var (
rejected []*fetchResult
td *big.Int
)
if !beaconMode && ttd != nil {
td = d.blockchain.GetTd(results[0].Header.ParentHash, results[0].Header.Number.Uint64()-1)
if td == nil {
// This should never really happen, but handle gracefully for now
log.Error("Failed to retrieve parent block TD", "number", results[0].Header.Number.Uint64()-1, "hash", results[0].Header.ParentHash)
return fmt.Errorf("%w: parent TD missing", errInvalidChain)
}
for i, result := range results {
td = new(big.Int).Add(td, result.Header.Difficulty)
if td.Cmp(ttd) >= 0 {
// Terminal total difficulty reached, allow the last block in
if new(big.Int).Sub(td, result.Header.Difficulty).Cmp(ttd) < 0 {
results, rejected = results[:i+1], results[i+1:]
if len(rejected) > 0 {
// Make a nicer user log as to the first TD truly rejected
td = new(big.Int).Add(td, rejected[0].Header.Difficulty)
}
} else {
results, rejected = results[:i], results[i:]
}
break
}
}
}
if err := d.importBlockResults(results); err != nil {
return err
}
if len(rejected) != 0 {
log.Info("Legacy sync reached merge threshold", "number", rejected[0].Header.Number, "hash", rejected[0].Header.Hash(), "td", td, "ttd", ttd)
return ErrMergeTransition
}
}
}
func (d *Downloader) importBlockResults(results []*fetchResult) error {
// Check for any early termination requests
if len(results) == 0 {
return nil
}
select {
case <-d.quitCh:
return errCancelContentProcessing
default:
}
// Retrieve a batch of results to import
first, last := results[0].Header, results[len(results)-1].Header
log.Debug("Inserting downloaded chain", "items", len(results),
"firstnum", first.Number, "firsthash", first.Hash(),
"lastnum", last.Number, "lasthash", last.Hash(),
)
blocks := make([]*types.Block, len(results))
for i, result := range results {
blocks[i] = types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles).WithWithdrawals(result.Withdrawals)
}
// Downloaded blocks are always regarded as trusted after the
// transition. Because the downloaded chain is guided by the
// consensus-layer.
if index, err := d.blockchain.InsertChain(blocks); err != nil {
if index < len(results) {
log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
// In post-merge, notify the engine API of encountered bad chains
if d.badBlock != nil {
head, _, _, err := d.skeleton.Bounds()
if err != nil {
log.Error("Failed to retrieve beacon bounds for bad block reporting", "err", err)
} else {
d.badBlock(blocks[index].Header(), head)
}
}
} else {
// The InsertChain method in blockchain.go will sometimes return an out-of-bounds index,
// when it needs to preprocess blocks to import a sidechain.
// The importer will put together a new list of blocks to import, which is a superset
// of the blocks delivered from the downloader, and the indexing will be off.
log.Debug("Downloaded item processing failed on sidechain import", "index", index, "err", err)
}
return fmt.Errorf("%w: %v", errInvalidChain, err)
}
return nil
}
// processSnapSyncContent takes fetch results from the queue and writes them to the
// database. It also controls the synchronisation of state nodes of the pivot block.
func (d *Downloader) processSnapSyncContent() error {
// Start syncing state of the reported head block. This should get us most of
// the state of the pivot block.
d.pivotLock.RLock()
sync := d.syncState(d.pivotHeader.Root)
d.pivotLock.RUnlock()
defer func() {
// The `sync` object is replaced every time the pivot moves. We need to
// defer close the very last active one, hence the lazy evaluation vs.
// calling defer sync.Cancel() !!!
sync.Cancel()
}()
closeOnErr := func(s *stateSync) {
if err := s.Wait(); err != nil && err != errCancelStateFetch && err != errCanceled && err != snap.ErrCancelled {
d.queue.Close() // wake up Results
}
}
go closeOnErr(sync)
// To cater for moving pivot points, track the pivot block and subsequently
// accumulated download results separately.
//
// These will be nil up to the point where we reach the pivot, and will only
// be set temporarily if the synced blocks are piling up, but the pivot is
// still busy downloading. In that case, we need to occasionally check for
// pivot moves, so need to unblock the loop. These fields will accumulate
// the results in the meantime.
//
// Note, there's no issue with memory piling up since after 64 blocks the
// pivot will forcefully move so these accumulators will be dropped.
var (
oldPivot *fetchResult // Locked in pivot block, might change eventually
oldTail []*fetchResult // Downloaded content after the pivot
)
for {
// Wait for the next batch of downloaded data to be available. If we have
// not yet reached the pivot point, wait blockingly as there's no need to
// spin-loop check for pivot moves. If we reached the pivot but have not
// yet processed it, check for results async, so we might notice pivot
// moves while state syncing. If the pivot was passed fully, block again
// as there's no more reason to check for pivot moves at all.
results := d.queue.Results(oldPivot == nil)
if len(results) == 0 {
// If pivot sync is done, stop
if d.committed.Load() {
d.reportSnapSyncProgress(true)
return sync.Cancel()
}
// If sync failed, stop
select {
case <-d.cancelCh:
sync.Cancel()
return errCanceled
default:
}
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
d.reportSnapSyncProgress(false)
// If we haven't downloaded the pivot block yet, check pivot staleness
// notifications from the header downloader
d.pivotLock.RLock()
pivot := d.pivotHeader
d.pivotLock.RUnlock()
if oldPivot == nil { // no results piling up, we can move the pivot
if !d.committed.Load() { // not yet passed the pivot, we can move the pivot
if pivot.Root != sync.root { // pivot position changed, we can move the pivot
sync.Cancel()
sync = d.syncState(pivot.Root)
go closeOnErr(sync)
}
}
} else { // results already piled up, consume before handling pivot move
results = append(append([]*fetchResult{oldPivot}, oldTail...), results...)
}
// Split around the pivot block and process the two sides via snap/full sync
if !d.committed.Load() {
latest := results[len(results)-1].Header
// If the height is above the pivot block by 2 sets, it means the pivot
// become stale in the network, and it was garbage collected, move to a
// new pivot.
//
// Note, we have `reorgProtHeaderDelay` number of blocks withheld, Those
// need to be taken into account, otherwise we're detecting the pivot move
// late and will drop peers due to unavailable state!!!
if height := latest.Number.Uint64(); height >= pivot.Number.Uint64()+2*uint64(fsMinFullBlocks)-uint64(reorgProtHeaderDelay) {
log.Warn("Pivot became stale, moving", "old", pivot.Number.Uint64(), "new", height-uint64(fsMinFullBlocks)+uint64(reorgProtHeaderDelay))
pivot = results[len(results)-1-fsMinFullBlocks+reorgProtHeaderDelay].Header // must exist as lower old pivot is uncommitted
d.pivotLock.Lock()
d.pivotHeader = pivot
d.pivotLock.Unlock()
// Write out the pivot into the database so a rollback beyond it will
// reenable snap sync
rawdb.WriteLastPivotNumber(d.stateDB, pivot.Number.Uint64())
}
}
P, beforeP, afterP := splitAroundPivot(pivot.Number.Uint64(), results)
if err := d.commitSnapSyncData(beforeP, sync); err != nil {
return err
}
if P != nil {
// If new pivot block found, cancel old state retrieval and restart
if oldPivot != P {
sync.Cancel()
sync = d.syncState(P.Header.Root)
go closeOnErr(sync)
oldPivot = P
}
// Wait for completion, occasionally checking for pivot staleness
select {
case <-sync.done:
if sync.err != nil {
return sync.err
}
if err := d.commitPivotBlock(P); err != nil {
return err
}
oldPivot = nil
case <-time.After(time.Second):
oldTail = afterP
continue
}
}
// Fast sync done, pivot commit done, full import
if err := d.importBlockResults(afterP); err != nil {
return err
}
}
}
func splitAroundPivot(pivot uint64, results []*fetchResult) (p *fetchResult, before, after []*fetchResult) {
if len(results) == 0 {
return nil, nil, nil
}
if lastNum := results[len(results)-1].Header.Number.Uint64(); lastNum < pivot {
// the pivot is somewhere in the future
return nil, results, nil
}
// This can also be optimized, but only happens very seldom
for _, result := range results {
num := result.Header.Number.Uint64()
switch {
case num < pivot:
before = append(before, result)
case num == pivot:
p = result
default:
after = append(after, result)
}
}
return p, before, after
}
func (d *Downloader) commitSnapSyncData(results []*fetchResult, stateSync *stateSync) error {
// Check for any early termination requests
if len(results) == 0 {
return nil
}
select {
case <-d.quitCh:
return errCancelContentProcessing
case <-stateSync.done:
if err := stateSync.Wait(); err != nil {
return err
}
default:
}
// Retrieve the batch of results to import
first, last := results[0].Header, results[len(results)-1].Header
log.Debug("Inserting snap-sync blocks", "items", len(results),
"firstnum", first.Number, "firsthash", first.Hash(),
"lastnumn", last.Number, "lasthash", last.Hash(),
)
blocks := make([]*types.Block, len(results))
receipts := make([]types.Receipts, len(results))
for i, result := range results {
blocks[i] = types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles).WithWithdrawals(result.Withdrawals)
receipts[i] = result.Receipts
}
if index, err := d.blockchain.InsertReceiptChain(blocks, receipts, d.ancientLimit); err != nil {
log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
return fmt.Errorf("%w: %v", errInvalidChain, err)
}
return nil
}
func (d *Downloader) commitPivotBlock(result *fetchResult) error {
block := types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles).WithWithdrawals(result.Withdrawals)
log.Debug("Committing snap sync pivot as new head", "number", block.Number(), "hash", block.Hash())
// Commit the pivot block as the new head, will require full sync from here on
if _, err := d.blockchain.InsertReceiptChain([]*types.Block{block}, []types.Receipts{result.Receipts}, d.ancientLimit); err != nil {
return err
}
if err := d.blockchain.SnapSyncCommitHead(block.Hash()); err != nil {
return err
}
d.committed.Store(true)
return nil
}
// DeliverSnapPacket is invoked from a peer's message handler when it transmits a
// data packet for the local node to consume.
func (d *Downloader) DeliverSnapPacket(peer *snap.Peer, packet snap.Packet) error {
switch packet := packet.(type) {
case *snap.AccountRangePacket:
hashes, accounts, err := packet.Unpack()
if err != nil {
return err
}
return d.SnapSyncer.OnAccounts(peer, packet.ID, hashes, accounts, packet.Proof)
case *snap.StorageRangesPacket:
hashset, slotset := packet.Unpack()
return d.SnapSyncer.OnStorage(peer, packet.ID, hashset, slotset, packet.Proof)
case *snap.ByteCodesPacket:
return d.SnapSyncer.OnByteCodes(peer, packet.ID, packet.Codes)
case *snap.TrieNodesPacket:
return d.SnapSyncer.OnTrieNodes(peer, packet.ID, packet.Nodes)
default:
return fmt.Errorf("unexpected snap packet type: %T", packet)
}
}
// readHeaderRange returns a list of headers, using the given last header as the base,
// and going backwards towards genesis. This method assumes that the caller already has
// placed a reasonable cap on count.
func (d *Downloader) readHeaderRange(last *types.Header, count int) []*types.Header {
var (
current = last
headers []*types.Header
)
for {
parent := d.lightchain.GetHeaderByHash(current.ParentHash)
if parent == nil {
break // The chain is not continuous, or the chain is exhausted
}
headers = append(headers, parent)
if len(headers) >= count {
break
}
current = parent
}
return headers
}
// reportSnapSyncProgress calculates various status reports and provides it to the user.
func (d *Downloader) reportSnapSyncProgress(force bool) {
// Initialize the sync start time if it's the first time we're reporting
if d.syncStartTime.IsZero() {
d.syncStartTime = time.Now().Add(-time.Millisecond) // -1ms offset to avoid division by zero
}
// Don't report all the events, just occasionally
if !force && time.Since(d.syncLogTime) < 8*time.Second {
return
}
// Don't report anything until we have a meaningful progress
var (
headerBytes, _ = d.stateDB.AncientSize(rawdb.ChainFreezerHeaderTable)
bodyBytes, _ = d.stateDB.AncientSize(rawdb.ChainFreezerBodiesTable)
receiptBytes, _ = d.stateDB.AncientSize(rawdb.ChainFreezerReceiptTable)
)
syncedBytes := common.StorageSize(headerBytes + bodyBytes + receiptBytes)
if syncedBytes == 0 {
return
}
var (
header = d.blockchain.CurrentHeader()
block = d.blockchain.CurrentSnapBlock()
)
syncedBlocks := block.Number.Uint64() - d.syncStartBlock
if syncedBlocks == 0 {
return
}
// Retrieve the current chain head and calculate the ETA
latest, _, _, err := d.skeleton.Bounds()
if err != nil {
// We're going to cheat for non-merged networks, but that's fine
latest = d.pivotHeader
}
if latest == nil {
// This should really never happen, but add some defensive code for now.
// TODO(karalabe): Remove it eventually if we don't see it blow.
log.Error("Nil latest block in sync progress report")
return
}
var (
left = latest.Number.Uint64() - block.Number.Uint64()
eta = time.Since(d.syncStartTime) / time.Duration(syncedBlocks) * time.Duration(left)
progress = fmt.Sprintf("%.2f%%", float64(block.Number.Uint64())*100/float64(latest.Number.Uint64()))
headers = fmt.Sprintf("%v@%v", log.FormatLogfmtUint64(header.Number.Uint64()), common.StorageSize(headerBytes).TerminalString())
bodies = fmt.Sprintf("%v@%v", log.FormatLogfmtUint64(block.Number.Uint64()), common.StorageSize(bodyBytes).TerminalString())
receipts = fmt.Sprintf("%v@%v", log.FormatLogfmtUint64(block.Number.Uint64()), common.StorageSize(receiptBytes).TerminalString())
)
log.Info("Syncing: chain download in progress", "synced", progress, "chain", syncedBytes, "headers", headers, "bodies", bodies, "receipts", receipts, "eta", common.PrettyDuration(eta))
d.syncLogTime = time.Now()
}