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op-geth/eth/downloader/downloader.go

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// 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 (
"crypto/rand"
"errors"
"fmt"
"math"
"math/big"
"strings"
"sync"
"sync/atomic"
"time"
ethereum "github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/trie"
"github.com/rcrowley/go-metrics"
)
var (
MaxHashFetch = 512 // Amount of hashes to be fetched per retrieval request
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
MaxBodyFetch = 128 // Amount of block bodies to be fetched per retrieval request
MaxReceiptFetch = 256 // Amount of transaction receipts to allow fetching per request
MaxStateFetch = 384 // Amount of node state values to allow fetching per request
MaxForkAncestry = 3 * params.EpochDuration.Uint64() // Maximum chain reorganisation
rttMinEstimate = 2 * time.Second // Minimum round-trip time to target for download requests
rttMaxEstimate = 20 * time.Second // Maximum rount-trip time to target for download requests
rttMinConfidence = 0.1 // Worse confidence factor in our estimated RTT value
ttlScaling = 3 // Constant scaling factor for RTT -> TTL conversion
ttlLimit = time.Minute // Maximum TTL allowance to prevent reaching crazy timeouts
qosTuningPeers = 5 // Number of peers to tune based on (best peers)
qosConfidenceCap = 10 // Number of peers above which not to modify RTT confidence
qosTuningImpact = 0.25 // Impact that a new tuning target has on the previous value
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
fsHeaderCheckFrequency = 100 // Verification frequency of the downloaded headers during fast sync
fsHeaderSafetyNet = 2048 // Number of headers to discard in case a chain violation is detected
fsHeaderForceVerify = 24 // Number of headers to verify before and after the pivot to accept it
fsPivotInterval = 256 // Number of headers out of which to randomize the pivot point
fsMinFullBlocks = 64 // Number of blocks to retrieve fully even in fast sync
fsCriticalTrials = uint32(32) // Number of times to retry in the cricical section before bailing
)
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")
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")
errInvalidBlock = errors.New("retrieved block is invalid")
errInvalidBody = errors.New("retrieved block body is invalid")
errInvalidReceipt = errors.New("retrieved receipt is invalid")
errCancelBlockFetch = errors.New("block download canceled (requested)")
errCancelHeaderFetch = errors.New("block header download canceled (requested)")
errCancelBodyFetch = errors.New("block body download canceled (requested)")
errCancelReceiptFetch = errors.New("receipt download canceled (requested)")
errCancelStateFetch = errors.New("state data download canceled (requested)")
errCancelHeaderProcessing = errors.New("header processing canceled (requested)")
errCancelContentProcessing = errors.New("content processing canceled (requested)")
errNoSyncActive = errors.New("no sync active")
errTooOld = errors.New("peer doesn't speak recent enough protocol version (need version >= 62)")
)
type Downloader struct {
mode SyncMode // Synchronisation mode defining the strategy used (per sync cycle)
mux *event.TypeMux // Event multiplexer to announce sync operation events
queue *queue // Scheduler for selecting the hashes to download
peers *peerSet // Set of active peers from which download can proceed
fsPivotLock *types.Header // Pivot header on critical section entry (cannot change between retries)
fsPivotFails uint32 // Number of subsequent fast sync failures in the critical section
rttEstimate uint64 // Round trip time to target for download requests
rttConfidence uint64 // Confidence in the estimated RTT (unit: millionths to allow atomic ops)
// Statistics
syncStatsChainOrigin uint64 // Origin block number where syncing started at
syncStatsChainHeight uint64 // Highest block number known when syncing started
syncStatsStateDone uint64 // Number of state trie entries already pulled
syncStatsLock sync.RWMutex // Lock protecting the sync stats fields
// Callbacks
hasHeader headerCheckFn // Checks if a header is present in the chain
hasBlockAndState blockAndStateCheckFn // Checks if a block and associated state is present in the chain
getHeader headerRetrievalFn // Retrieves a header from the chain
getBlock blockRetrievalFn // Retrieves a block from the chain
headHeader headHeaderRetrievalFn // Retrieves the head header from the chain
headBlock headBlockRetrievalFn // Retrieves the head block from the chain
headFastBlock headFastBlockRetrievalFn // Retrieves the head fast-sync block from the chain
commitHeadBlock headBlockCommitterFn // Commits a manually assembled block as the chain head
getTd tdRetrievalFn // Retrieves the TD of a block from the chain
insertHeaders headerChainInsertFn // Injects a batch of headers into the chain
insertBlocks blockChainInsertFn // Injects a batch of blocks into the chain
insertReceipts receiptChainInsertFn // Injects a batch of blocks and their receipts into the chain
rollback chainRollbackFn // Removes a batch of recently added chain links
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
// Channels
newPeerCh chan *peer
headerCh chan dataPack // [eth/62] Channel receiving inbound block headers
bodyCh chan dataPack // [eth/62] Channel receiving inbound block bodies
receiptCh chan dataPack // [eth/63] Channel receiving inbound receipts
stateCh chan dataPack // [eth/63] Channel receiving inbound node state data
bodyWakeCh chan bool // [eth/62] Channel to signal the block body fetcher of new tasks
receiptWakeCh chan bool // [eth/63] Channel to signal the receipt fetcher of new tasks
stateWakeCh chan bool // [eth/63] Channel to signal the state fetcher of new tasks
headerProcCh chan []*types.Header // [eth/62] Channel to feed the header processor new tasks
// 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
quitCh chan struct{} // Quit channel to signal termination
quitLock sync.RWMutex // 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)
}
// New creates a new downloader to fetch hashes and blocks from remote peers.
func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, hasBlockAndState blockAndStateCheckFn,
getHeader headerRetrievalFn, getBlock blockRetrievalFn, headHeader headHeaderRetrievalFn, headBlock headBlockRetrievalFn,
headFastBlock headFastBlockRetrievalFn, commitHeadBlock headBlockCommitterFn, getTd tdRetrievalFn, insertHeaders headerChainInsertFn,
insertBlocks blockChainInsertFn, insertReceipts receiptChainInsertFn, rollback chainRollbackFn, dropPeer peerDropFn) *Downloader {
dl := &Downloader{
mode: mode,
mux: mux,
queue: newQueue(stateDb),
peers: newPeerSet(),
rttEstimate: uint64(rttMaxEstimate),
rttConfidence: uint64(1000000),
hasHeader: hasHeader,
hasBlockAndState: hasBlockAndState,
getHeader: getHeader,
getBlock: getBlock,
headHeader: headHeader,
headBlock: headBlock,
headFastBlock: headFastBlock,
commitHeadBlock: commitHeadBlock,
getTd: getTd,
insertHeaders: insertHeaders,
insertBlocks: insertBlocks,
insertReceipts: insertReceipts,
rollback: rollback,
dropPeer: dropPeer,
newPeerCh: make(chan *peer, 1),
headerCh: make(chan dataPack, 1),
bodyCh: make(chan dataPack, 1),
receiptCh: make(chan dataPack, 1),
stateCh: make(chan dataPack, 1),
bodyWakeCh: make(chan bool, 1),
receiptWakeCh: make(chan bool, 1),
stateWakeCh: make(chan bool, 1),
headerProcCh: make(chan []*types.Header, 1),
quitCh: make(chan struct{}),
}
go dl.qosTuner()
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 {
// Fetch the pending state count outside of the lock to prevent unforeseen deadlocks
pendingStates := uint64(d.queue.PendingNodeData())
// Lock the current stats and return the progress
d.syncStatsLock.RLock()
defer d.syncStatsLock.RUnlock()
current := uint64(0)
switch d.mode {
case FullSync:
current = d.headBlock().NumberU64()
case FastSync:
current = d.headFastBlock().NumberU64()
case LightSync:
current = d.headHeader().Number.Uint64()
}
return ethereum.SyncProgress{
StartingBlock: d.syncStatsChainOrigin,
CurrentBlock: current,
HighestBlock: d.syncStatsChainHeight,
PulledStates: d.syncStatsStateDone,
KnownStates: d.syncStatsStateDone + pendingStates,
}
}
// 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 int, currentHead currentHeadRetrievalFn,
getRelHeaders relativeHeaderFetcherFn, getAbsHeaders absoluteHeaderFetcherFn, getBlockBodies blockBodyFetcherFn,
getReceipts receiptFetcherFn, getNodeData stateFetcherFn) error {
glog.V(logger.Detail).Infoln("Registering peer", id)
if err := d.peers.Register(newPeer(id, version, currentHead, getRelHeaders, getAbsHeaders, getBlockBodies, getReceipts, getNodeData)); err != nil {
glog.V(logger.Error).Infoln("Register failed:", err)
return err
}
d.qosReduceConfidence()
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
glog.V(logger.Detail).Infoln("Unregistering peer", id)
if err := d.peers.Unregister(id); err != nil {
glog.V(logger.Error).Infoln("Unregister failed:", err)
return err
}
d.queue.Revoke(id)
// If this peer was the master peer, abort sync immediately
d.cancelLock.RLock()
master := id == d.cancelPeer
d.cancelLock.RUnlock()
if master {
d.cancel()
}
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 {
glog.V(logger.Detail).Infof("Attempting synchronisation: %v, head [%x…], TD %v", id, head[:4], td)
err := d.synchronise(id, head, td, mode)
switch err {
case nil:
glog.V(logger.Detail).Infof("Synchronisation completed")
case errBusy:
glog.V(logger.Detail).Infof("Synchronisation already in progress")
case errTimeout, errBadPeer, errStallingPeer,
errEmptyHeaderSet, errPeersUnavailable, errTooOld,
errInvalidAncestor, errInvalidChain:
glog.V(logger.Debug).Infof("Removing peer %v: %v", id, err)
d.dropPeer(id)
default:
glog.V(logger.Warn).Infof("Synchronisation failed: %v", 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 it's 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) {
glog.V(logger.Info).Infoln("Block synchronisation started")
}
// Reset the queue, peer set and wake channels to clean any internal leftover state
d.queue.Reset()
d.peers.Reset()
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
select {
case <-ch:
default:
}
}
for _, ch := range []chan dataPack{d.headerCh, d.bodyCh, d.receiptCh, d.stateCh} {
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
// Set the requested sync mode, unless it's forbidden
d.mode = mode
if d.mode == FastSync && atomic.LoadUint32(&d.fsPivotFails) >= fsCriticalTrials {
d.mode = FullSync
}
// 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)
}
// syncWithPeer starts a block synchronization based on the hash chain from the
// specified peer and head hash.
func (d *Downloader) syncWithPeer(p *peer, 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 {
d.mux.Post(DoneEvent{})
}
}()
if p.version < 62 {
return errTooOld
}
glog.V(logger.Debug).Infof("Synchronising with the network using: %s [eth/%d]", p.id, p.version)
defer func(start time.Time) {
glog.V(logger.Debug).Infof("Synchronisation terminated after %v", time.Since(start))
}(time.Now())
// Look up the sync boundaries: the common ancestor and the target block
latest, err := d.fetchHeight(p)
if err != nil {
return err
}
height := latest.Number.Uint64()
origin, err := d.findAncestor(p, height)
if err != nil {
return err
}
d.syncStatsLock.Lock()
if d.syncStatsChainHeight <= origin || d.syncStatsChainOrigin > origin {
d.syncStatsChainOrigin = origin
}
d.syncStatsChainHeight = height
d.syncStatsLock.Unlock()
// Initiate the sync using a concurrent header and content retrieval algorithm
pivot := uint64(0)
switch d.mode {
case LightSync:
pivot = height
case FastSync:
// Calculate the new fast/slow sync pivot point
if d.fsPivotLock == nil {
pivotOffset, err := rand.Int(rand.Reader, big.NewInt(int64(fsPivotInterval)))
if err != nil {
panic(fmt.Sprintf("Failed to access crypto random source: %v", err))
}
if height > uint64(fsMinFullBlocks)+pivotOffset.Uint64() {
pivot = height - uint64(fsMinFullBlocks) - pivotOffset.Uint64()
}
} else {
// Pivot point locked in, use this and do not pick a new one!
pivot = d.fsPivotLock.Number.Uint64()
}
// If the point is below the origin, move origin back to ensure state download
if pivot < origin {
if pivot > 0 {
origin = pivot - 1
} else {
origin = 0
}
}
glog.V(logger.Debug).Infof("Fast syncing until pivot block #%d", pivot)
}
d.queue.Prepare(origin+1, d.mode, pivot, latest)
if d.syncInitHook != nil {
d.syncInitHook(origin, height)
}
return d.spawnSync(origin+1,
func() error { return d.fetchHeaders(p, origin+1) }, // Headers are always retrieved
func() error { return d.processHeaders(origin+1, td) }, // 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.fetchNodeData() }, // Node state data is retrieved during fast sync
)
}
// spawnSync runs d.process and all given fetcher functions to completion in
// separate goroutines, returning the first error that appears.
func (d *Downloader) spawnSync(origin uint64, fetchers ...func() error) error {
var wg sync.WaitGroup
errc := make(chan error, len(fetchers)+1)
wg.Add(len(fetchers) + 1)
go func() { defer wg.Done(); errc <- d.processContent() }()
for _, fn := range fetchers {
fn := fn
go func() { defer wg.Done(); errc <- fn() }()
}
// Wait for the first error, then terminate the others.
var err error
for i := 0; i < len(fetchers)+1; i++ {
if i == len(fetchers) {
// 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 {
break
}
}
d.queue.Close()
d.cancel()
wg.Wait()
// If sync failed in the critical section, bump the fail counter
if err != nil && d.mode == FastSync && d.fsPivotLock != nil {
atomic.AddUint32(&d.fsPivotFails, 1)
}
return err
}
// cancel cancels all of the operations and resets the queue. It returns true
// if the cancel operation was completed.
func (d *Downloader) cancel() {
// Close the current cancel channel
d.cancelLock.Lock()
if d.cancelCh != nil {
select {
case <-d.cancelCh:
// Channel was already closed
default:
close(d.cancelCh)
}
}
d.cancelLock.Unlock()
}
// 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()
}
// fetchHeight retrieves the head header of the remote peer to aid in estimating
// the total time a pending synchronisation would take.
func (d *Downloader) fetchHeight(p *peer) (*types.Header, error) {
glog.V(logger.Debug).Infof("%v: retrieving remote chain height", p)
// Request the advertised remote head block and wait for the response
head, _ := p.currentHead()
go p.getRelHeaders(head, 1, 0, false)
timeout := time.After(d.requestTTL())
for {
select {
case <-d.cancelCh:
return nil, errCancelBlockFetch
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
if len(headers) != 1 {
glog.V(logger.Debug).Infof("%v: invalid number of head headers: %d != 1", p, len(headers))
return nil, errBadPeer
}
return headers[0], nil
case <-timeout:
glog.V(logger.Debug).Infof("%v: head header timeout", p)
return nil, errTimeout
case <-d.bodyCh:
case <-d.stateCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
}
// 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 *peer, height uint64) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor (remote height %d)", p, height)
// Figure out the valid ancestor range to prevent rewrite attacks
floor, ceil := int64(-1), d.headHeader().Number.Uint64()
if d.mode == FullSync {
ceil = d.headBlock().NumberU64()
} else if d.mode == FastSync {
ceil = d.headFastBlock().NumberU64()
}
if ceil >= MaxForkAncestry {
floor = int64(ceil - MaxForkAncestry)
}
// Request the topmost blocks to short circuit binary ancestor lookup
head := ceil
if head > height {
head = height
}
from := int64(head) - int64(MaxHeaderFetch)
if from < 0 {
from = 0
}
// Span out with 15 block gaps into the future to catch bad head reports
limit := 2 * MaxHeaderFetch / 16
count := 1 + int((int64(ceil)-from)/16)
if count > limit {
count = limit
}
go p.getAbsHeaders(uint64(from), count, 15, false)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
timeout := time.After(d.requestTTL())
for finished := false; !finished; {
select {
case <-d.cancelCh:
return 0, errCancelHeaderFetch
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
if len(headers) == 0 {
glog.V(logger.Warn).Infof("%v: empty head header set", p)
return 0, errEmptyHeaderSet
}
// Make sure the peer's reply conforms to the request
for i := 0; i < len(headers); i++ {
if number := headers[i].Number.Int64(); number != from+int64(i)*16 {
glog.V(logger.Warn).Infof("%v: head header set (item %d) broke chain ordering: requested %d, got %d", p, i, from+int64(i)*16, number)
return 0, errInvalidChain
}
}
// 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() > ceil {
continue
}
// Otherwise check if we already know the header or not
if (d.mode == FullSync && d.hasBlockAndState(headers[i].Hash())) || (d.mode != FullSync && d.hasHeader(headers[i].Hash())) {
number, hash = headers[i].Number.Uint64(), headers[i].Hash()
// If every header is known, even future ones, the peer straight out lied about its head
if number > height && i == limit-1 {
glog.V(logger.Warn).Infof("%v: lied about chain head: reported %d, found above %d", p, height, number)
return 0, errStallingPeer
}
break
}
}
case <-timeout:
glog.V(logger.Debug).Infof("%v: head header timeout", p)
return 0, errTimeout
case <-d.bodyCh:
case <-d.stateCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
if int64(number) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, number, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
if floor > 0 {
start = uint64(floor)
}
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
timeout := time.After(d.requestTTL())
go p.getAbsHeaders(uint64(check), 1, 0, false)
// Wait until a reply arrives to this request
for arrived := false; !arrived; {
select {
case <-d.cancelCh:
return 0, errCancelHeaderFetch
case packer := <-d.headerCh:
// Discard anything not from the origin peer
if packer.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packer.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packer.(*headerPack).headers
if len(headers) != 1 {
glog.V(logger.Debug).Infof("%v: invalid search header set (%d)", p, len(headers))
return 0, errBadPeer
}
arrived = true
// Modify the search interval based on the response
if (d.mode == FullSync && !d.hasBlockAndState(headers[0].Hash())) || (d.mode != FullSync && !d.hasHeader(headers[0].Hash())) {
end = check
break
}
header := d.getHeader(headers[0].Hash()) // Independent of sync mode, header surely exists
if header.Number.Uint64() != check {
glog.V(logger.Debug).Infof("%v: non requested header #%d [%x…], instead of #%d", p, header.Number, header.Hash().Bytes()[:4], check)
return 0, errBadPeer
}
start = check
case <-timeout:
glog.V(logger.Debug).Infof("%v: search header timeout", p)
return 0, errTimeout
case <-d.bodyCh:
case <-d.stateCh:
case <-d.receiptCh:
// Out of bounds delivery, ignore
}
}
}
// Ensure valid ancestry and return
if int64(start) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, start, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, start, hash[:4])
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 *peer, from uint64) error {
glog.V(logger.Debug).Infof("%v: directing header downloads from #%d", p, from)
defer glog.V(logger.Debug).Infof("%v: header download terminated", p)
// Create a timeout timer, and the associated header fetcher
skeleton := true // Skeleton assembly phase or finishing up
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()
getHeaders := func(from uint64) {
request = time.Now()
timeout.Reset(d.requestTTL())
if skeleton {
glog.V(logger.Detail).Infof("%v: fetching %d skeleton headers from #%d", p, MaxHeaderFetch, from)
go p.getAbsHeaders(from+uint64(MaxHeaderFetch)-1, MaxSkeletonSize, MaxHeaderFetch-1, false)
} else {
glog.V(logger.Detail).Infof("%v: fetching %d full headers from #%d", p, MaxHeaderFetch, from)
go p.getAbsHeaders(from, MaxHeaderFetch, 0, false)
}
}
// Start pulling the header chain skeleton until all is done
getHeaders(from)
for {
select {
case <-d.cancelCh:
return errCancelHeaderFetch
case packet := <-d.headerCh:
// Make sure the active peer is giving us the skeleton headers
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received skeleton headers from incorrect peer (%s)", packet.PeerId())
break
}
headerReqTimer.UpdateSince(request)
timeout.Stop()
// If the skeleton's finished, pull any remaining head headers directly from the origin
if packet.Items() == 0 && skeleton {
skeleton = false
getHeaders(from)
continue
}
// If no more headers are inbound, notify the content fetchers and return
if packet.Items() == 0 {
glog.V(logger.Debug).Infof("%v: no available headers", p)
select {
case d.headerProcCh <- nil:
return nil
case <-d.cancelCh:
return errCancelHeaderFetch
}
}
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 {
glog.V(logger.Debug).Infof("%v: skeleton chain invalid: %v", p, err)
return errInvalidChain
}
headers = filled[proced:]
from += uint64(proced)
}
// Insert all the new headers and fetch the next batch
if len(headers) > 0 {
glog.V(logger.Detail).Infof("%v: schedule %d headers from #%d", p, len(headers), from)
select {
case d.headerProcCh <- headers:
case <-d.cancelCh:
return errCancelHeaderFetch
}
from += uint64(len(headers))
}
getHeaders(from)
case <-timeout.C:
// Header retrieval timed out, consider the peer bad and drop
glog.V(logger.Debug).Infof("%v: header request timed out", p)
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, d.stateWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
select {
case d.headerProcCh <- nil:
case <-d.cancelCh:
}
return 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 returs 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) {
glog.V(logger.Debug).Infof("Filling up skeleton from #%d", 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.requestTTL()) }
throttle = func() bool { return false }
reserve = func(p *peer, count int) (*fetchRequest, bool, error) {
return d.queue.ReserveHeaders(p, count), false, nil
}
fetch = func(p *peer, req *fetchRequest) error { return p.FetchHeaders(req.From, MaxHeaderFetch) }
capacity = func(p *peer) int { return p.HeaderCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetHeadersIdle(accepted) }
)
err := d.fetchParts(errCancelHeaderFetch, d.headerCh, deliver, d.queue.headerContCh, expire,
d.queue.PendingHeaders, d.queue.InFlightHeaders, throttle, reserve,
nil, fetch, d.queue.CancelHeaders, capacity, d.peers.HeaderIdlePeers, setIdle, "Header")
glog.V(logger.Debug).Infof("Skeleton fill terminated: %v", 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 {
glog.V(logger.Debug).Infof("Downloading block bodies from #%d", 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.requestTTL()) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchBodies(req) }
capacity = func(p *peer) int { return p.BlockCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetBodiesIdle(accepted) }
)
err := d.fetchParts(errCancelBodyFetch, d.bodyCh, deliver, d.bodyWakeCh, expire,
d.queue.PendingBlocks, d.queue.InFlightBlocks, d.queue.ShouldThrottleBlocks, d.queue.ReserveBodies,
d.bodyFetchHook, fetch, d.queue.CancelBodies, capacity, d.peers.BodyIdlePeers, setIdle, "Body")
glog.V(logger.Debug).Infof("Block body download terminated: %v", 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 {
glog.V(logger.Debug).Infof("Downloading receipts from #%d", 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.requestTTL()) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchReceipts(req) }
capacity = func(p *peer) int { return p.ReceiptCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetReceiptsIdle(accepted) }
)
err := d.fetchParts(errCancelReceiptFetch, d.receiptCh, deliver, d.receiptWakeCh, expire,
d.queue.PendingReceipts, d.queue.InFlightReceipts, d.queue.ShouldThrottleReceipts, d.queue.ReserveReceipts,
d.receiptFetchHook, fetch, d.queue.CancelReceipts, capacity, d.peers.ReceiptIdlePeers, setIdle, "Receipt")
glog.V(logger.Debug).Infof("Receipt download terminated: %v", err)
return err
}
// fetchNodeData iteratively downloads the scheduled state trie nodes, taking any
// available peers, reserving a chunk of nodes for each, waiting for delivery and
// also periodically checking for timeouts.
func (d *Downloader) fetchNodeData() error {
glog.V(logger.Debug).Infof("Downloading node state data")
var (
deliver = func(packet dataPack) (int, error) {
start := time.Now()
return d.queue.DeliverNodeData(packet.PeerId(), packet.(*statePack).states, func(delivered int, progressed bool, err error) {
// If the peer returned old-requested data, forgive
if err == trie.ErrNotRequested {
glog.V(logger.Debug).Infof("peer %s: replied to stale state request, forgiving", packet.PeerId())
return
}
if err != nil {
// If the node data processing failed, the root hash is very wrong, abort
glog.V(logger.Error).Infof("peer %d: state processing failed: %v", packet.PeerId(), err)
d.cancel()
return
}
// Processing succeeded, notify state fetcher of continuation
pending := d.queue.PendingNodeData()
if pending > 0 {
select {
case d.stateWakeCh <- true:
default:
}
}
d.syncStatsLock.Lock()
d.syncStatsStateDone += uint64(delivered)
syncStatsStateDone := d.syncStatsStateDone // Thread safe copy for the log below
d.syncStatsLock.Unlock()
// If real database progress was made, reset any fast-sync pivot failure
if progressed && atomic.LoadUint32(&d.fsPivotFails) > 1 {
glog.V(logger.Debug).Infof("fast-sync progressed, resetting fail counter from %d", atomic.LoadUint32(&d.fsPivotFails))
atomic.StoreUint32(&d.fsPivotFails, 1) // Don't ever reset to 0, as that will unlock the pivot block
}
// Log a message to the user and return
if delivered > 0 {
glog.V(logger.Info).Infof("imported %3d state entries in %9v: processed %d, pending at least %d", delivered, common.PrettyDuration(time.Since(start)), syncStatsStateDone, pending)
}
})
}
expire = func() map[string]int { return d.queue.ExpireNodeData(d.requestTTL()) }
throttle = func() bool { return false }
reserve = func(p *peer, count int) (*fetchRequest, bool, error) {
return d.queue.ReserveNodeData(p, count), false, nil
}
fetch = func(p *peer, req *fetchRequest) error { return p.FetchNodeData(req) }
capacity = func(p *peer) int { return p.NodeDataCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetNodeDataIdle(accepted) }
)
err := d.fetchParts(errCancelStateFetch, d.stateCh, deliver, d.stateWakeCh, expire,
d.queue.PendingNodeData, d.queue.InFlightNodeData, throttle, reserve, nil, fetch,
d.queue.CancelNodeData, capacity, d.peers.NodeDataIdlePeers, setIdle, "State")
glog.V(logger.Debug).Infof("Node state data download terminated: %v", 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 retreive 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 mesages
func (d *Downloader) fetchParts(errCancel error, deliveryCh chan dataPack, deliver func(dataPack) (int, error), wakeCh chan bool,
expire func() map[string]int, pending func() int, inFlight func() bool, throttle func() bool, reserve func(*peer, int) (*fetchRequest, bool, error),
fetchHook func([]*types.Header), fetch func(*peer, *fetchRequest) error, cancel func(*fetchRequest), capacity func(*peer) int,
idle func() ([]*peer, int), setIdle func(*peer, int), 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 errCancel
case packet := <-deliveryCh:
// If the peer was previously banned and failed to deliver it's pack
// in a reasonable time frame, ignore it's 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 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 err != errStaleDelivery {
setIdle(peer, accepted)
}
// Issue a log to the user to see what's going on
switch {
case err == nil && packet.Items() == 0:
glog.V(logger.Detail).Infof("%s: no %s delivered", peer, strings.ToLower(kind))
case err == nil:
glog.V(logger.Detail).Infof("%s: delivered %s %s(s)", peer, packet.Stats(), strings.ToLower(kind))
default:
glog.V(logger.Detail).Infof("%s: %s delivery failed: %v", peer, strings.ToLower(kind), 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 {
glog.V(logger.Detail).Infof("%s: %s delivery timeout", peer, strings.ToLower(kind))
setIdle(peer, 0)
} else {
glog.V(logger.Debug).Infof("%s: stalling %s delivery, dropping", peer, strings.ToLower(kind))
d.dropPeer(pid)
}
}
}
// If there's nothing more to fetch, wait or terminate
if pending() == 0 {
if !inFlight() && finished {
glog.V(logger.Debug).Infof("%s fetching completed", kind)
return nil
}
break
}
// Send a download request to all idle peers, until throttled
progressed, throttled, running := false, false, inFlight()
idles, total := idle()
for _, peer := range idles {
// Short circuit if throttling activated
if throttle() {
throttled = true
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, err := reserve(peer, capacity(peer))
if err != nil {
return err
}
if progress {
progressed = true
}
if request == nil {
continue
}
if glog.V(logger.Detail) {
if request.From > 0 {
glog.Infof("%s: requesting %s(s) from #%d", peer, strings.ToLower(kind), request.From)
} else if len(request.Headers) > 0 {
glog.Infof("%s: requesting %d %s(s), first at #%d", peer, len(request.Headers), strings.ToLower(kind), request.Headers[0].Number)
} else {
glog.Infof("%s: requesting %d %s(s)", peer, len(request.Hashes), strings.ToLower(kind))
}
}
// 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, strings.ToLower(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 && pending() > 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 {
// Calculate the pivoting point for switching from fast to slow sync
pivot := d.queue.FastSyncPivot()
// Keep a count of uncertain headers to roll back
rollback := []*types.Header{}
defer func() {
if len(rollback) > 0 {
// Flatten the headers and roll them back
hashes := make([]common.Hash, len(rollback))
for i, header := range rollback {
hashes[i] = header.Hash()
}
lastHeader, lastFastBlock, lastBlock := d.headHeader().Number, common.Big0, common.Big0
if d.headFastBlock != nil {
lastFastBlock = d.headFastBlock().Number()
}
if d.headBlock != nil {
lastBlock = d.headBlock().Number()
}
d.rollback(hashes)
curFastBlock, curBlock := common.Big0, common.Big0
if d.headFastBlock != nil {
curFastBlock = d.headFastBlock().Number()
}
if d.headBlock != nil {
curBlock = d.headBlock().Number()
}
glog.V(logger.Warn).Infof("Rolled back %d headers (LH: %d->%d, FB: %d->%d, LB: %d->%d)",
len(hashes), lastHeader, d.headHeader().Number, lastFastBlock, curFastBlock, lastBlock, curBlock)
// If we're already past the pivot point, this could be an attack, thread carefully
if rollback[len(rollback)-1].Number.Uint64() > pivot {
// If we didn't ever fail, lock in te pivot header (must! not! change!)
if atomic.LoadUint32(&d.fsPivotFails) == 0 {
for _, header := range rollback {
if header.Number.Uint64() == pivot {
glog.V(logger.Warn).Infof("Fast-sync critical section failure, locked pivot to header #%d [%x…]", pivot, header.Hash().Bytes()[:4])
d.fsPivotLock = header
}
}
}
}
}
}()
// Wait for batches of headers to process
gotHeaders := false
for {
select {
case <-d.cancelCh:
return errCancelHeaderProcessing
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, d.stateWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
// If no headers were retrieved at all, the peer violated it's TD promise that it had a
// better chain compared to ours. The only exception is if it's promised blocks were
// already imported by other means (e.g. fecher):
//
// 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 d.mode != LightSync {
if !gotHeaders && td.Cmp(d.getTd(d.headBlock().Hash())) > 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 d.mode == FastSync || d.mode == LightSync {
if td.Cmp(d.getTd(d.headHeader().Hash())) > 0 {
return errStallingPeer
}
}
// Disable any rollback and return
rollback = nil
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:
return errCancelHeaderProcessing
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 d.mode == FastSync || d.mode == LightSync {
// Collect the yet unknown headers to mark them as uncertain
unknown := make([]*types.Header, 0, len(headers))
for _, header := range chunk {
if !d.hasHeader(header.Hash()) {
unknown = append(unknown, header)
}
}
// If we're importing pure headers, verify based on their recentness
frequency := fsHeaderCheckFrequency
if chunk[len(chunk)-1].Number.Uint64()+uint64(fsHeaderForceVerify) > pivot {
frequency = 1
}
if n, err := d.insertHeaders(chunk, frequency); err != nil {
// If some headers were inserted, add them too to the rollback list
if n > 0 {
rollback = append(rollback, chunk[:n]...)
}
glog.V(logger.Debug).Infof("invalid header #%d [%x…]: %v", chunk[n].Number, chunk[n].Hash().Bytes()[:4], err)
return errInvalidChain
}
// All verifications passed, store newly found uncertain headers
rollback = append(rollback, unknown...)
if len(rollback) > fsHeaderSafetyNet {
rollback = append(rollback[:0], rollback[len(rollback)-fsHeaderSafetyNet:]...)
}
}
// If we're fast syncing and just pulled in the pivot, make sure it's the one locked in
if d.mode == FastSync && d.fsPivotLock != nil && chunk[0].Number.Uint64() <= pivot && chunk[len(chunk)-1].Number.Uint64() >= pivot {
if pivot := chunk[int(pivot-chunk[0].Number.Uint64())]; pivot.Hash() != d.fsPivotLock.Hash() {
glog.V(logger.Warn).Infof("Pivot doesn't match locked in version: have #%v [%x…], want #%v [%x…]", pivot.Number, pivot.Hash().Bytes()[:4], d.fsPivotLock.Number, d.fsPivotLock.Hash().Bytes()[:4])
return errInvalidChain
}
}
// Unless we're doing light chains, schedule the headers for associated content retrieval
if d.mode == FullSync || d.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:
return errCancelHeaderProcessing
case <-time.After(time.Second):
}
}
// Otherwise insert the headers for content retrieval
inserts := d.queue.Schedule(chunk, origin)
if len(inserts) != len(chunk) {
glog.V(logger.Debug).Infof("stale headers")
return errBadPeer
}
}
headers = headers[limit:]
origin += uint64(limit)
}
// Signal the content downloaders of the availablility of new tasks
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
select {
case ch <- true:
default:
}
}
}
}
}
// processContent takes fetch results from the queue and tries to import them
// into the chain. The type of import operation will depend on the result contents.
func (d *Downloader) processContent() error {
pivot := d.queue.FastSyncPivot()
for {
results := d.queue.WaitResults()
if len(results) == 0 {
return nil // queue empty
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
// Actually import the blocks
if glog.V(logger.Debug) {
first, last := results[0].Header, results[len(results)-1].Header
glog.Infof("Inserting chain with %d items (#%d [%x…] - #%d [%x…])", len(results), first.Number, first.Hash().Bytes()[:4], last.Number, last.Hash().Bytes()[:4])
}
for len(results) != 0 {
// Check for any termination requests
select {
case <-d.quitCh:
return errCancelContentProcessing
default:
}
// Retrieve the a batch of results to import
var (
blocks = make([]*types.Block, 0, maxResultsProcess)
receipts = make([]types.Receipts, 0, maxResultsProcess)
)
items := int(math.Min(float64(len(results)), float64(maxResultsProcess)))
for _, result := range results[:items] {
switch {
case d.mode == FullSync:
blocks = append(blocks, types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles))
case d.mode == FastSync:
blocks = append(blocks, types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles))
if result.Header.Number.Uint64() <= pivot {
receipts = append(receipts, result.Receipts)
}
}
}
// Try to process the results, aborting if there's an error
var (
err error
index int
)
switch {
case len(receipts) > 0:
index, err = d.insertReceipts(blocks, receipts)
if err == nil && blocks[len(blocks)-1].NumberU64() == pivot {
glog.V(logger.Debug).Infof("Committing block #%d [%x…] as the new head", blocks[len(blocks)-1].Number(), blocks[len(blocks)-1].Hash().Bytes()[:4])
index, err = len(blocks)-1, d.commitHeadBlock(blocks[len(blocks)-1].Hash())
}
default:
index, err = d.insertBlocks(blocks)
}
if err != nil {
glog.V(logger.Debug).Infof("Result #%d [%x…] processing failed: %v", results[index].Header.Number, results[index].Header.Hash().Bytes()[:4], err)
return errInvalidChain
}
// Shift the results to the next batch
results = results[items:]
}
}
}
// 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) (err error) {
return d.deliver(id, 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) (err error) {
return d.deliver(id, 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) (err error) {
return d.deliver(id, 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) (err error) {
return d.deliver(id, d.stateCh, &statePack{id, data}, stateInMeter, stateDropMeter)
}
// deliver injects a new batch of data received from a remote node.
func (d *Downloader) deliver(id string, 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
}
}
// qosTuner is the quality of service tuning loop that occasionally gathers the
// peer latency statistics and updates the estimated request round trip time.
func (d *Downloader) qosTuner() {
for {
// Retrieve the current median RTT and integrate into the previoust target RTT
rtt := time.Duration(float64(1-qosTuningImpact)*float64(atomic.LoadUint64(&d.rttEstimate)) + qosTuningImpact*float64(d.peers.medianRTT()))
atomic.StoreUint64(&d.rttEstimate, uint64(rtt))
// A new RTT cycle passed, increase our confidence in the estimated RTT
conf := atomic.LoadUint64(&d.rttConfidence)
conf = conf + (1000000-conf)/2
atomic.StoreUint64(&d.rttConfidence, conf)
// Log the new QoS values and sleep until the next RTT
glog.V(logger.Debug).Infof("Quality of service: rtt %v, conf %.3f, ttl %v", rtt, float64(conf)/1000000.0, d.requestTTL())
select {
case <-d.quitCh:
return
case <-time.After(rtt):
}
}
}
// qosReduceConfidence is meant to be called when a new peer joins the downloader's
// peer set, needing to reduce the confidence we have in out QoS estimates.
func (d *Downloader) qosReduceConfidence() {
// If we have a single peer, confidence is always 1
peers := uint64(d.peers.Len())
if peers == 1 {
atomic.StoreUint64(&d.rttConfidence, 1000000)
return
}
// If we have a ton of peers, don't drop confidence)
if peers >= uint64(qosConfidenceCap) {
return
}
// Otherwise drop the confidence factor
conf := atomic.LoadUint64(&d.rttConfidence) * (peers - 1) / peers
if float64(conf)/1000000 < rttMinConfidence {
conf = uint64(rttMinConfidence * 1000000)
}
atomic.StoreUint64(&d.rttConfidence, conf)
rtt := time.Duration(atomic.LoadUint64(&d.rttEstimate))
glog.V(logger.Debug).Infof("Quality of service: rtt %v, conf %.3f, ttl %v", rtt, float64(conf)/1000000.0, d.requestTTL())
}
// requestRTT returns the current target round trip time for a download request
// to complete in.
//
// Note, the returned RTT is .9 of the actually estimated RTT. The reason is that
// the downloader tries to adapt queries to the RTT, so multiple RTT values can
// be adapted to, but smaller ones are preffered (stabler download stream).
func (d *Downloader) requestRTT() time.Duration {
return time.Duration(atomic.LoadUint64(&d.rttEstimate)) * 9 / 10
}
// requestTTL returns the current timeout allowance for a single download request
// to finish under.
func (d *Downloader) requestTTL() time.Duration {
var (
rtt = time.Duration(atomic.LoadUint64(&d.rttEstimate))
conf = float64(atomic.LoadUint64(&d.rttConfidence)) / 1000000.0
)
ttl := time.Duration(ttlScaling) * time.Duration(float64(rtt)/conf)
if ttl > ttlLimit {
ttl = ttlLimit
}
return ttl
}
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