plugeth/les/downloader/downloader.go
Péter Szilágyi dde2da0efb
all: remove ethash pow, only retain shims needed for consensus and tests (#27178)
* all: remove ethash pow, only retain shims needed for consensus and tests

* all: thank you linter

* all: disallow launching Geth in legacy PoW mode

* cmd/env/internal/t8ntool: remove dangling ethash flag
2023-05-03 12:58:39 +03:00

1980 lines
73 KiB
Go

// 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 is a temporary package whilst working on the eth/66 blocking refactors.
// After that work is done, les needs to be refactored to use the new package,
// or alternatively use a stripped down version of it. Either way, we need to
// keep the changes scoped so duplicating temporarily seems the sanest.
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/eth"
"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/metrics"
"github.com/ethereum/go-ethereum/params"
)
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
MaxStateFetch = 384 // Amount of node state values 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 fast 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)")
errNoSyncActive = errors.New("no sync active")
errTooOld = errors.New("peer's protocol version too old")
errNoAncestorFound = errors.New("no common ancestor found")
)
type Downloader struct {
mode 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
checkpoint uint64 // Checkpoint block number to enforce head against (e.g. fast sync)
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
syncStatsState stateSyncStats
syncStatsLock sync.RWMutex // Lock protecting the sync stats fields
lightchain LightChain
blockchain BlockChain
// Callbacks
dropPeer peerDropFn // Drops a peer for misbehaving
// Status
synchroniseMock func(id string, hash common.Hash) error // Replacement for synchronise during testing
synchronising int32
notified int32
committed int32
ancientLimit uint64 // The maximum block number which can be regarded as ancient data.
// Channels
headerCh chan dataPack // Channel receiving inbound block headers
bodyCh chan dataPack // Channel receiving inbound block bodies
receiptCh chan dataPack // Channel receiving inbound receipts
bodyWakeCh chan bool // Channel to signal the block body fetcher of new tasks
receiptWakeCh chan bool // Channel to signal the receipt fetcher of new tasks
headerProcCh chan []*types.Header // Channel to feed the header processor new tasks
// 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
snapSync bool // Whether to run state sync over the snap protocol
SnapSyncer *snap.Syncer // TODO(karalabe): make private! hack for now
stateSyncStart chan *stateSync
trackStateReq chan *stateReq
stateCh chan dataPack // Channel receiving inbound node state data
// 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)
}
// 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 fast) blockchain.
type BlockChain interface {
LightChain
// HasBlock verifies a block's presence in the local chain.
HasBlock(common.Hash, uint64) bool
// HasFastBlock verifies a fast 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.Block
// CurrentFastBlock retrieves the head fast block from the local chain.
CurrentFastBlock() *types.Block
// FastSyncCommitHead directly commits the head block to a certain entity.
FastSyncCommitHead(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
}
// New creates a new downloader to fetch hashes and blocks from remote peers.
func New(checkpoint uint64, stateDb ethdb.Database, mux *event.TypeMux, chain BlockChain, lightchain LightChain, dropPeer peerDropFn) *Downloader {
if lightchain == nil {
lightchain = chain
}
dl := &Downloader{
stateDB: stateDb,
mux: mux,
checkpoint: checkpoint,
queue: newQueue(blockCacheMaxItems, blockCacheInitialItems),
peers: newPeerSet(),
blockchain: chain,
lightchain: lightchain,
dropPeer: dropPeer,
headerCh: make(chan dataPack, 1),
bodyCh: make(chan dataPack, 1),
receiptCh: make(chan dataPack, 1),
bodyWakeCh: make(chan bool, 1),
receiptWakeCh: make(chan bool, 1),
headerProcCh: make(chan []*types.Header, 1),
quitCh: make(chan struct{}),
stateCh: make(chan dataPack),
SnapSyncer: snap.NewSyncer(stateDb, rawdb.HashScheme),
stateSyncStart: make(chan *stateSync),
//syncStatsState: stateSyncStats{
// processed: rawdb.ReadFastTrieProgress(stateDb),
//},
trackStateReq: make(chan *stateReq),
}
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 fast 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().NumberU64()
case d.blockchain != nil && mode == FastSync:
current = d.blockchain.CurrentFastBlock().NumberU64()
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)
}
return ethereum.SyncProgress{
StartingBlock: d.syncStatsChainOrigin,
CurrentBlock: current,
HighestBlock: d.syncStatsChainHeight,
//PulledStates: d.syncStatsState.processed,
//KnownStates: d.syncStatsState.processed + d.syncStatsState.pending,
}
}
// Synchronising returns whether the downloader is currently retrieving blocks.
func (d *Downloader) Synchronising() bool {
return atomic.LoadInt32(&d.synchronising) > 0
}
// 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
}
// RegisterLightPeer injects a light client peer, wrapping it so it appears as a regular peer.
func (d *Downloader) RegisterLightPeer(id string, version uint, peer LightPeer) error {
return d.RegisterPeer(id, version, &lightPeerWrapper{peer})
}
// 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
}
// Synchronise 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) Synchronise(id string, head common.Hash, td *big.Int, mode SyncMode) error {
err := d.synchronise(id, head, td, mode)
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
}
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 *big.Int, mode SyncMode) error {
// 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 !atomic.CompareAndSwapInt32(&d.synchronising, 0, 1) {
return errBusy
}
defer atomic.StoreInt32(&d.synchronising, 0)
// Post a user notification of the sync (only once per session)
if atomic.CompareAndSwapInt32(&d.notified, 0, 1) {
log.Info("Block synchronisation started")
}
// If snap sync was requested, create the snap scheduler and switch to fast
// sync mode. Long term we could drop fast sync or merge the two together,
// but until snap becomes prevalent, we should support both. TODO(karalabe).
if mode == SnapSync {
if !d.snapSync {
// Snap sync uses the snapshot namespace to store potentially flakey 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()
}
log.Warn("Enabling snapshot sync prototype")
d.snapSync = true
}
mode = FastSync
}
// 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.bodyWakeCh, d.receiptWakeCh} {
select {
case <-ch:
default:
}
}
for _, ch := range []chan dataPack{d.headerCh, d.bodyCh, d.receiptCh} {
for empty := false; !empty; {
select {
case <-ch:
default:
empty = true
}
}
}
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
atomic.StoreUint32(&d.mode, uint32(mode))
// Retrieve the origin peer and initiate the downloading process
p := d.peers.Peer(id)
if p == nil {
return errUnknownPeer
}
return d.syncWithPeer(p, hash, td)
}
func (d *Downloader) getMode() SyncMode {
return SyncMode(atomic.LoadUint32(&d.mode))
}
// 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 *big.Int) (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})
}
}()
if p.version < eth.ETH66 {
return fmt.Errorf("%w: advertized %d < required %d", errTooOld, p.version, eth.ETH66)
}
mode := d.getMode()
log.Debug("Synchronising with the network", "peer", p.id, "eth", p.version, "head", hash, "td", td, "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
latest, pivot, err := d.fetchHead(p)
if err != nil {
return err
}
if mode == FastSync && pivot == nil {
// 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 fast sync
// anyway, but still need a valid pivot block to avoid some code hitting
// nil panics on an access.
pivot = d.blockchain.CurrentBlock().Header()
}
height := latest.Number.Uint64()
origin, err := d.findAncestor(p, latest)
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 fast sync pivot point
if mode == FastSync {
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 fast sync
rawdb.WriteLastPivotNumber(d.stateDB, pivotNumber)
}
}
d.committed = 1
if mode == FastSync && pivot.Number.Uint64() != 0 {
d.committed = 0
}
if mode == FastSync {
// Set the ancient data limitation.
// If we are running fast 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 there is a checkpoint available, then calculate the ancientLimit through
// that. Otherwise calculate the ancient limit through the advertised height
// of the remote peer.
//
// The reason for picking checkpoint first is that a malicious peer can give us
// a fake (very high) height, forcing the ancient limit to also be very high.
// The peer would start to feed us valid blocks until head, resulting in all of
// the blocks might be written into the ancient store. A following mini-reorg
// could cause issues.
if d.checkpoint != 0 && d.checkpoint > fullMaxForkAncestry+1 {
d.ancientLimit = d.checkpoint
} else 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 + 1); 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)
}
fetchers := []func() error{
func() error { return d.fetchHeaders(p, origin+1) }, // Headers are always retrieved
func() error { return d.fetchBodies(origin + 1) }, // Bodies are retrieved during normal and fast sync
func() error { return d.fetchReceipts(origin + 1) }, // Receipts are retrieved during fast sync
func() error { return d.processHeaders(origin+1, td) },
}
if mode == FastSync {
d.pivotLock.Lock()
d.pivotHeader = pivot
d.pivotLock.Unlock()
fetchers = append(fetchers, func() error { return d.processFastSyncContent() })
} else if mode == FullSync {
fetchers = append(fetchers, d.processFullSyncContent)
}
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 err = <-errc; err != nil && err != errCanceled {
break
}
}
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)
}
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 == FastSync {
fetch = 2 // head + pivot headers
}
go p.peer.RequestHeadersByHash(latest, fetch, fsMinFullBlocks-1, true)
ttl := d.peers.rates.TargetTimeout()
timeout := time.After(ttl)
for {
select {
case <-d.cancelCh:
return nil, nil, errCanceled
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
log.Debug("Received headers from incorrect peer", "peer", packet.PeerId())
break
}
// Make sure the peer gave us at least one and at most the requested headers
headers := packet.(*headerPack).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 checkpoint
// and request. If only 1 header was returned, make sure there's no pivot
// or there was not one requested.
head := headers[0]
if (mode == FastSync || mode == LightSync) && head.Number.Uint64() < d.checkpoint {
return nil, nil, fmt.Errorf("%w: remote head %d below checkpoint %d", errUnsyncedPeer, head.Number, d.checkpoint)
}
if len(headers) == 1 {
if mode == FastSync && 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", head.Hash())
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
case <-timeout:
p.log.Debug("Waiting for head header timed out", "elapsed", ttl)
return nil, nil, errTimeout
case <-d.bodyCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
}
// 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().NumberU64()
case FastSync:
localHeight = d.blockchain.CurrentFastBlock().NumberU64()
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) (commonAncestor uint64, err error) {
from, count, skip, max := calculateRequestSpan(remoteHeight, localHeight)
p.log.Trace("Span searching for common ancestor", "count", count, "from", from, "skip", skip)
go p.peer.RequestHeadersByNumber(uint64(from), count, skip, false)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
ttl := d.peers.rates.TargetTimeout()
timeout := time.After(ttl)
for finished := false; !finished; {
select {
case <-d.cancelCh:
return 0, errCanceled
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
log.Debug("Received headers from incorrect peer", "peer", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
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
finished = true
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 := headers[i].Hash()
n := headers[i].Number.Uint64()
var known bool
switch mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case FastSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if known {
number, hash = n, h
break
}
}
case <-timeout:
p.log.Debug("Waiting for head header timed out", "elapsed", ttl)
return 0, errTimeout
case <-d.bodyCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
// 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) (commonAncestor uint64, err 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
ttl := d.peers.rates.TargetTimeout()
timeout := time.After(ttl)
go p.peer.RequestHeadersByNumber(check, 1, 0, false)
// Wait until a reply arrives to this request
for arrived := false; !arrived; {
select {
case <-d.cancelCh:
return 0, errCanceled
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
log.Debug("Received headers from incorrect peer", "peer", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
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))
}
arrived = true
// Modify the search interval based on the response
h := headers[0].Hash()
n := headers[0].Number.Uint64()
var known bool
switch mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case FastSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if !known {
end = check
break
}
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
case <-timeout:
p.log.Debug("Waiting for search header timed out", "elapsed", ttl)
return 0, errTimeout
case <-d.bodyCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
}
// 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) error {
p.log.Debug("Directing header downloads", "origin", from)
defer p.log.Debug("Header download terminated")
// Create a timeout timer, and the associated header fetcher
skeleton := true // Skeleton assembly phase or finishing up
pivoting := false // Whether the next request is pivot verification
request := time.Now() // time of the last skeleton fetch request
timeout := time.NewTimer(0) // timer to dump a non-responsive active peer
<-timeout.C // timeout channel should be initially empty
defer timeout.Stop()
var ttl time.Duration
getHeaders := func(from uint64) {
request = time.Now()
ttl = d.peers.rates.TargetTimeout()
timeout.Reset(ttl)
if skeleton {
p.log.Trace("Fetching skeleton headers", "count", MaxHeaderFetch, "from", from)
go p.peer.RequestHeadersByNumber(from+uint64(MaxHeaderFetch)-1, MaxSkeletonSize, MaxHeaderFetch-1, false)
} else {
p.log.Trace("Fetching full headers", "count", MaxHeaderFetch, "from", from)
go p.peer.RequestHeadersByNumber(from, MaxHeaderFetch, 0, false)
}
}
getNextPivot := func() {
pivoting = true
request = time.Now()
ttl = d.peers.rates.TargetTimeout()
timeout.Reset(ttl)
d.pivotLock.RLock()
pivot := d.pivotHeader.Number.Uint64()
d.pivotLock.RUnlock()
p.log.Trace("Fetching next pivot header", "number", pivot+uint64(fsMinFullBlocks))
go p.peer.RequestHeadersByNumber(pivot+uint64(fsMinFullBlocks), 2, fsMinFullBlocks-9, false) // move +64 when it's 2x64-8 deep
}
// Start pulling the header chain skeleton until all is done
ancestor := from
getHeaders(from)
mode := d.getMode()
for {
select {
case <-d.cancelCh:
return errCanceled
case packet := <-d.headerCh:
// Make sure the active peer is giving us the skeleton headers
if packet.PeerId() != p.id {
log.Debug("Received skeleton from incorrect peer", "peer", packet.PeerId())
break
}
headerReqTimer.UpdateSince(request)
timeout.Stop()
// 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 packet.Items() == 2 {
// Retrieve the headers and do some sanity checks, just in case
headers := packet.(*headerPack).headers
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 fast sync and update the state root that
// the state syncer will be downloading.
rawdb.WriteLastPivotNumber(d.stateDB, pivot)
}
pivoting = false
getHeaders(from)
continue
}
// If the skeleton's finished, pull any remaining head headers directly from the origin
if skeleton && packet.Items() == 0 {
skeleton = false
getHeaders(from)
continue
}
// If no more headers are inbound, notify the content fetchers and return
if packet.Items() == 0 {
// Don't abort header fetches while the pivot is downloading
if atomic.LoadInt32(&d.committed) == 0 && pivot <= from {
p.log.Debug("No headers, waiting for pivot commit")
select {
case <-time.After(fsHeaderContCheck):
getHeaders(from)
continue
case <-d.cancelCh:
return errCanceled
}
}
// Pivot done (or not in fast 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
}
}
headers := packet.(*headerPack).headers
// If we received a skeleton batch, resolve internals concurrently
if skeleton {
filled, 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:]
from += uint64(proced)
} else {
// 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.CurrentFastBlock().NumberU64()
if full := d.blockchain.CurrentBlock().NumberU64(); 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]
}
}
}
// Insert all the 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 <- headers:
case <-d.cancelCh:
return errCanceled
}
from += uint64(len(headers))
// If we're still skeleton filling fast sync, check pivot staleness
// before continuing to the next skeleton filling
if skeleton && pivot > 0 {
getNextPivot()
} else {
getHeaders(from)
}
} else {
// No headers delivered, or all of them being delayed, sleep a bit and retry
p.log.Trace("All headers delayed, waiting")
select {
case <-time.After(fsHeaderContCheck):
getHeaders(from)
continue
case <-d.cancelCh:
return errCanceled
}
}
case <-timeout.C:
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
p.log.Warn("Downloader wants to drop peer, but peerdrop-function is not set", "peer", p.id)
break
}
// Header retrieval timed out, consider the peer bad and drop
p.log.Debug("Header request timed out", "elapsed", ttl)
headerTimeoutMeter.Mark(1)
d.dropPeer(p.id)
// Finish the sync gracefully instead of dumping the gathered data though
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
select {
case d.headerProcCh <- nil:
case <-d.cancelCh:
}
return fmt.Errorf("%w: header request timed out", errBadPeer)
}
}
}
// 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, int, error) {
log.Debug("Filling up skeleton", "from", from)
d.queue.ScheduleSkeleton(from, skeleton)
var (
deliver = func(packet dataPack) (int, error) {
pack := packet.(*headerPack)
return d.queue.DeliverHeaders(pack.peerID, pack.headers, d.headerProcCh)
}
expire = func() map[string]int { return d.queue.ExpireHeaders(d.peers.rates.TargetTimeout()) }
reserve = func(p *peerConnection, count int) (*fetchRequest, bool, bool) {
return d.queue.ReserveHeaders(p, count), false, false
}
fetch = func(p *peerConnection, req *fetchRequest) error { return p.FetchHeaders(req.From, MaxHeaderFetch) }
capacity = func(p *peerConnection) int { return p.HeaderCapacity(d.peers.rates.TargetRoundTrip()) }
setIdle = func(p *peerConnection, accepted int, deliveryTime time.Time) {
p.SetHeadersIdle(accepted, deliveryTime)
}
)
err := d.fetchParts(d.headerCh, deliver, d.queue.headerContCh, expire,
d.queue.PendingHeaders, d.queue.InFlightHeaders, reserve,
nil, fetch, d.queue.CancelHeaders, capacity, d.peers.HeaderIdlePeers, setIdle, "headers")
log.Debug("Skeleton fill terminated", "err", err)
filled, proced := d.queue.RetrieveHeaders()
return filled, 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) error {
log.Debug("Downloading block bodies", "origin", from)
var (
deliver = func(packet dataPack) (int, error) {
pack := packet.(*bodyPack)
return d.queue.DeliverBodies(pack.peerID, pack.transactions, pack.uncles)
}
expire = func() map[string]int { return d.queue.ExpireBodies(d.peers.rates.TargetTimeout()) }
fetch = func(p *peerConnection, req *fetchRequest) error { return p.FetchBodies(req) }
capacity = func(p *peerConnection) int { return p.BlockCapacity(d.peers.rates.TargetRoundTrip()) }
setIdle = func(p *peerConnection, accepted int, deliveryTime time.Time) { p.SetBodiesIdle(accepted, deliveryTime) }
)
err := d.fetchParts(d.bodyCh, deliver, d.bodyWakeCh, expire,
d.queue.PendingBlocks, d.queue.InFlightBlocks, d.queue.ReserveBodies,
d.bodyFetchHook, fetch, d.queue.CancelBodies, capacity, d.peers.BodyIdlePeers, setIdle, "bodies")
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) error {
log.Debug("Downloading transaction receipts", "origin", from)
var (
deliver = func(packet dataPack) (int, error) {
pack := packet.(*receiptPack)
return d.queue.DeliverReceipts(pack.peerID, pack.receipts)
}
expire = func() map[string]int { return d.queue.ExpireReceipts(d.peers.rates.TargetTimeout()) }
fetch = func(p *peerConnection, req *fetchRequest) error { return p.FetchReceipts(req) }
capacity = func(p *peerConnection) int { return p.ReceiptCapacity(d.peers.rates.TargetRoundTrip()) }
setIdle = func(p *peerConnection, accepted int, deliveryTime time.Time) {
p.SetReceiptsIdle(accepted, deliveryTime)
}
)
err := d.fetchParts(d.receiptCh, deliver, d.receiptWakeCh, expire,
d.queue.PendingReceipts, d.queue.InFlightReceipts, d.queue.ReserveReceipts,
d.receiptFetchHook, fetch, d.queue.CancelReceipts, capacity, d.peers.ReceiptIdlePeers, setIdle, "receipts")
log.Debug("Transaction receipt download terminated", "err", err)
return err
}
// fetchParts iteratively downloads scheduled block parts, taking any available
// peers, reserving a chunk of fetch requests for each, waiting for delivery and
// also periodically checking for timeouts.
//
// As the scheduling/timeout logic mostly is the same for all downloaded data
// types, this method is used by each for data gathering and is instrumented with
// various callbacks to handle the slight differences between processing them.
//
// The instrumentation parameters:
// - errCancel: error type to return if the fetch operation is cancelled (mostly makes logging nicer)
// - deliveryCh: channel from which to retrieve downloaded data packets (merged from all concurrent peers)
// - deliver: processing callback to deliver data packets into type specific download queues (usually within `queue`)
// - wakeCh: notification channel for waking the fetcher when new tasks are available (or sync completed)
// - expire: task callback method to abort requests that took too long and return the faulty peers (traffic shaping)
// - pending: task callback for the number of requests still needing download (detect completion/non-completability)
// - inFlight: task callback for the number of in-progress requests (wait for all active downloads to finish)
// - throttle: task callback to check if the processing queue is full and activate throttling (bound memory use)
// - reserve: task callback to reserve new download tasks to a particular peer (also signals partial completions)
// - fetchHook: tester callback to notify of new tasks being initiated (allows testing the scheduling logic)
// - fetch: network callback to actually send a particular download request to a physical remote peer
// - cancel: task callback to abort an in-flight download request and allow rescheduling it (in case of lost peer)
// - capacity: network callback to retrieve the estimated type-specific bandwidth capacity of a peer (traffic shaping)
// - idle: network callback to retrieve the currently (type specific) idle peers that can be assigned tasks
// - setIdle: network callback to set a peer back to idle and update its estimated capacity (traffic shaping)
// - kind: textual label of the type being downloaded to display in log messages
func (d *Downloader) fetchParts(deliveryCh chan dataPack, deliver func(dataPack) (int, error), wakeCh chan bool,
expire func() map[string]int, pending func() int, inFlight func() bool, reserve func(*peerConnection, int) (*fetchRequest, bool, bool),
fetchHook func([]*types.Header), fetch func(*peerConnection, *fetchRequest) error, cancel func(*fetchRequest), capacity func(*peerConnection) int,
idle func() ([]*peerConnection, int), setIdle func(*peerConnection, int, time.Time), kind string) error {
// Create a ticker to detect expired retrieval tasks
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
update := make(chan struct{}, 1)
// Prepare the queue and fetch block parts until the block header fetcher's done
finished := false
for {
select {
case <-d.cancelCh:
return errCanceled
case packet := <-deliveryCh:
deliveryTime := time.Now()
// If the peer was previously banned and failed to deliver its pack
// in a reasonable time frame, ignore its message.
if peer := d.peers.Peer(packet.PeerId()); peer != nil {
// Deliver the received chunk of data and check chain validity
accepted, err := deliver(packet)
if errors.Is(err, errInvalidChain) {
return err
}
// Unless a peer delivered something completely else than requested (usually
// caused by a timed out request which came through in the end), set it to
// idle. If the delivery's stale, the peer should have already been idled.
if !errors.Is(err, errStaleDelivery) {
setIdle(peer, accepted, deliveryTime)
}
// Issue a log to the user to see what's going on
switch {
case err == nil && packet.Items() == 0:
peer.log.Trace("Requested data not delivered", "type", kind)
case err == nil:
peer.log.Trace("Delivered new batch of data", "type", kind, "count", packet.Stats())
default:
peer.log.Debug("Failed to deliver retrieved data", "type", kind, "err", err)
}
}
// Blocks assembled, try to update the progress
select {
case update <- struct{}{}:
default:
}
case cont := <-wakeCh:
// The header fetcher sent a continuation flag, check if it's done
if !cont {
finished = true
}
// Headers arrive, try to update the progress
select {
case update <- struct{}{}:
default:
}
case <-ticker.C:
// Sanity check update the progress
select {
case update <- struct{}{}:
default:
}
case <-update:
// Short circuit if we lost all our peers
if d.peers.Len() == 0 {
return errNoPeers
}
// Check for fetch request timeouts and demote the responsible peers
for pid, fails := range expire() {
if peer := d.peers.Peer(pid); peer != nil {
// If a lot of retrieval elements expired, we might have overestimated the remote peer or perhaps
// ourselves. Only reset to minimal throughput but don't drop just yet. If even the minimal times
// out that sync wise we need to get rid of the peer.
//
// The reason the minimum threshold is 2 is because the downloader tries to estimate the bandwidth
// and latency of a peer separately, which requires pushing the measures capacity a bit and seeing
// how response times reacts, to it always requests one more than the minimum (i.e. min 2).
if fails > 2 {
peer.log.Trace("Data delivery timed out", "type", kind)
setIdle(peer, 0, time.Now())
} else {
peer.log.Debug("Stalling delivery, dropping", "type", kind)
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
peer.log.Warn("Downloader wants to drop peer, but peerdrop-function is not set", "peer", pid)
} else {
d.dropPeer(pid)
// If this peer was the master peer, abort sync immediately
d.cancelLock.RLock()
master := pid == d.cancelPeer
d.cancelLock.RUnlock()
if master {
d.cancel()
return errTimeout
}
}
}
}
}
// If there's nothing more to fetch, wait or terminate
if pending() == 0 {
if !inFlight() && finished {
log.Debug("Data fetching completed", "type", kind)
return nil
}
break
}
// Send a download request to all idle peers, until throttled
progressed, throttled, running := false, false, inFlight()
idles, total := idle()
pendCount := pending()
for _, peer := range idles {
// Short circuit if throttling activated
if throttled {
break
}
// Short circuit if there is no more available task.
if pendCount = pending(); pendCount == 0 {
break
}
// Reserve a chunk of fetches for a peer. A nil can mean either that
// no more headers are available, or that the peer is known not to
// have them.
request, progress, throttle := reserve(peer, capacity(peer))
if progress {
progressed = true
}
if throttle {
throttled = true
throttleCounter.Inc(1)
}
if request == nil {
continue
}
if request.From > 0 {
peer.log.Trace("Requesting new batch of data", "type", kind, "from", request.From)
} else {
peer.log.Trace("Requesting new batch of data", "type", kind, "count", len(request.Headers), "from", request.Headers[0].Number)
}
// Fetch the chunk and make sure any errors return the hashes to the queue
if fetchHook != nil {
fetchHook(request.Headers)
}
if err := fetch(peer, request); err != nil {
// Although we could try and make an attempt to fix this, this error really
// means that we've double allocated a fetch task to a peer. If that is the
// case, the internal state of the downloader and the queue is very wrong so
// better hard crash and note the error instead of silently accumulating into
// a much bigger issue.
panic(fmt.Sprintf("%v: %s fetch assignment failed", peer, kind))
}
running = true
}
// Make sure that we have peers available for fetching. If all peers have been tried
// and all failed throw an error
if !progressed && !throttled && !running && len(idles) == total && pendCount > 0 {
return errPeersUnavailable
}
}
}
}
// 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 *big.Int) error {
// Keep a count of uncertain headers to roll back
var (
rollback uint64 // Zero means no rollback (fine as you can't unroll the genesis)
rollbackErr error
mode = d.getMode()
)
defer func() {
if rollback > 0 {
lastHeader, lastFastBlock, lastBlock := d.lightchain.CurrentHeader().Number, common.Big0, common.Big0
if mode != LightSync {
lastFastBlock = d.blockchain.CurrentFastBlock().Number()
lastBlock = d.blockchain.CurrentBlock().Number()
}
if err := d.lightchain.SetHead(rollback - 1); err != nil { // -1 to target the parent of the first uncertain block
// We're already unwinding the stack, only print the error to make it more visible
log.Error("Failed to roll back chain segment", "head", rollback-1, "err", err)
}
curFastBlock, curBlock := common.Big0, common.Big0
if mode != LightSync {
curFastBlock = d.blockchain.CurrentFastBlock().Number()
curBlock = d.blockchain.CurrentBlock().Number()
}
log.Warn("Rolled back chain segment",
"header", fmt.Sprintf("%d->%d", lastHeader, d.lightchain.CurrentHeader().Number),
"fast", fmt.Sprintf("%d->%d", lastFastBlock, curFastBlock),
"block", fmt.Sprintf("%d->%d", lastBlock, curBlock), "reason", rollbackErr)
}
}()
// Wait for batches of headers to process
gotHeaders := false
for {
select {
case <-d.cancelCh:
rollbackErr = errCanceled
return errCanceled
case headers := <-d.headerProcCh:
// Terminate header processing if we synced up
if len(headers) == 0 {
// Notify everyone that headers are fully processed
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
// 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.NumberU64())) > 0 {
return errStallingPeer
}
}
// If fast 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 == FastSync || mode == LightSync {
head := d.lightchain.CurrentHeader()
if td.Cmp(d.lightchain.GetTd(head.Hash(), head.Number.Uint64())) > 0 {
return errStallingPeer
}
}
// Disable any rollback and return
rollback = 0
return nil
}
// Otherwise split the chunk of headers into batches and process them
gotHeaders = true
for len(headers) > 0 {
// Terminate if something failed in between processing chunks
select {
case <-d.cancelCh:
rollbackErr = errCanceled
return errCanceled
default:
}
// Select the next chunk of headers to import
limit := maxHeadersProcess
if limit > len(headers) {
limit = len(headers)
}
chunk := headers[:limit]
// In case of header only syncing, validate the chunk immediately
if mode == FastSync || mode == LightSync {
if n, err := d.lightchain.InsertHeaderChain(chunk); err != nil {
rollbackErr = err
// If some headers were inserted, track them as uncertain
if mode == FastSync && n > 0 && rollback == 0 {
rollback = chunk[0].Number.Uint64()
}
log.Warn("Invalid header encountered", "number", chunk[n].Number, "hash", chunk[n].Hash(), "parent", chunk[n].ParentHash, "err", err)
return fmt.Errorf("%w: %v", errInvalidChain, err)
}
// All verifications passed, track all headers within the allotted limits
if mode == FastSync {
head := chunk[len(chunk)-1].Number.Uint64()
if head-rollback > uint64(fsHeaderSafetyNet) {
rollback = head - uint64(fsHeaderSafetyNet)
} else {
rollback = 1
}
}
}
// Unless we're doing light chains, schedule the headers for associated content retrieval
if mode == FullSync || mode == FastSync {
// If we've reached the allowed number of pending headers, stall a bit
for d.queue.PendingBlocks() >= maxQueuedHeaders || d.queue.PendingReceipts() >= maxQueuedHeaders {
select {
case <-d.cancelCh:
rollbackErr = errCanceled
return errCanceled
case <-time.After(time.Second):
}
}
// Otherwise insert the headers for content retrieval
inserts := d.queue.Schedule(chunk, origin)
if len(inserts) != len(chunk) {
rollbackErr = fmt.Errorf("stale headers: len inserts %v len(chunk) %v", len(inserts), len(chunk))
return fmt.Errorf("%w: stale headers", errBadPeer)
}
}
headers = headers[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.bodyWakeCh, d.receiptWakeCh} {
select {
case ch <- true:
default:
}
}
}
}
}
// processFullSyncContent takes fetch results from the queue and imports them into the chain.
func (d *Downloader) processFullSyncContent() error {
for {
results := d.queue.Results(true)
if len(results) == 0 {
return nil
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
if err := d.importBlockResults(results); err != nil {
return err
}
}
}
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 the 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)
}
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)
} 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
}
// processFastSyncContent 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) processFastSyncContent() 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.
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, and if the pivot
// block became stale, move the goalpost
results := d.queue.Results(oldPivot == nil) // Block if we're not monitoring pivot staleness
if len(results) == 0 {
// If pivot sync is done, stop
if oldPivot == nil {
return sync.Cancel()
}
// If sync failed, stop
select {
case <-d.cancelCh:
sync.Cancel()
return errCanceled
default:
}
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
// 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 {
if pivot.Root != sync.root {
sync.Cancel()
sync = d.syncState(pivot.Root)
go closeOnErr(sync)
}
} else {
results = append(append([]*fetchResult{oldPivot}, oldTail...), results...)
}
// Split around the pivot block and process the two sides via fast/full sync
if atomic.LoadInt32(&d.committed) == 0 {
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 fast sync
rawdb.WriteLastPivotNumber(d.stateDB, pivot.Number.Uint64())
}
}
P, beforeP, afterP := splitAroundPivot(pivot.Number.Uint64(), results)
if err := d.commitFastSyncData(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) commitFastSyncData(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 a batch of results to import
first, last := results[0].Header, results[len(results)-1].Header
log.Debug("Inserting fast-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)
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)
log.Debug("Committing fast 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.FastSyncCommitHead(block.Hash()); err != nil {
return err
}
atomic.StoreInt32(&d.committed, 1)
return nil
}
// DeliverHeaders injects a new batch of block headers received from a remote
// node into the download schedule.
func (d *Downloader) DeliverHeaders(id string, headers []*types.Header) error {
return d.deliver(d.headerCh, &headerPack{id, headers}, headerInMeter, headerDropMeter)
}
// DeliverBodies injects a new batch of block bodies received from a remote node.
func (d *Downloader) DeliverBodies(id string, transactions [][]*types.Transaction, uncles [][]*types.Header) error {
return d.deliver(d.bodyCh, &bodyPack{id, transactions, uncles}, bodyInMeter, bodyDropMeter)
}
// DeliverReceipts injects a new batch of receipts received from a remote node.
func (d *Downloader) DeliverReceipts(id string, receipts [][]*types.Receipt) error {
return d.deliver(d.receiptCh, &receiptPack{id, receipts}, receiptInMeter, receiptDropMeter)
}
// DeliverNodeData injects a new batch of node state data received from a remote node.
func (d *Downloader) DeliverNodeData(id string, data [][]byte) error {
return d.deliver(d.stateCh, &statePack{id, data}, stateInMeter, stateDropMeter)
}
// 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)
}
}
// deliver injects a new batch of data received from a remote node.
func (d *Downloader) deliver(destCh chan dataPack, packet dataPack, inMeter, dropMeter metrics.Meter) (err error) {
// Update the delivery metrics for both good and failed deliveries
inMeter.Mark(int64(packet.Items()))
defer func() {
if err != nil {
dropMeter.Mark(int64(packet.Items()))
}
}()
// Deliver or abort if the sync is canceled while queuing
d.cancelLock.RLock()
cancel := d.cancelCh
d.cancelLock.RUnlock()
if cancel == nil {
return errNoSyncActive
}
select {
case destCh <- packet:
return nil
case <-cancel:
return errNoSyncActive
}
}