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go-ethereum/eth/handler.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 eth
import (
"errors"
"math"
"math/big"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/consensus/beacon"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/forkid"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/eth/fetcher"
"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/p2p"
"github.com/ethereum/go-ethereum/params"
)
const (
// txChanSize is the size of channel listening to NewTxsEvent.
// The number is referenced from the size of tx pool.
txChanSize = 4096
)
var (
syncChallengeTimeout = 15 * time.Second // Time allowance for a node to reply to the sync progress challenge
)
// txPool defines the methods needed from a transaction pool implementation to
// support all the operations needed by the Ethereum chain protocols.
type txPool interface {
// Has returns an indicator whether txpool has a transaction
// cached with the given hash.
Has(hash common.Hash) bool
// Get retrieves the transaction from local txpool with given
// tx hash.
Get(hash common.Hash) *types.Transaction
// AddRemotes should add the given transactions to the pool.
AddRemotes([]*types.Transaction) []error
// Pending should return pending transactions.
// The slice should be modifiable by the caller.
Pending(enforceTips bool) map[common.Address]types.Transactions
// SubscribeNewTxsEvent should return an event subscription of
// NewTxsEvent and send events to the given channel.
SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription
}
// handlerConfig is the collection of initialization parameters to create a full
// node network handler.
type handlerConfig struct {
Database ethdb.Database // Database for direct sync insertions
Chain *core.BlockChain // Blockchain to serve data from
TxPool txPool // Transaction pool to propagate from
Merger *consensus.Merger // The manager for eth1/2 transition
Network uint64 // Network identifier to adfvertise
Sync downloader.SyncMode // Whether to snap or full sync
BloomCache uint64 // Megabytes to alloc for snap sync bloom
EventMux *event.TypeMux // Legacy event mux, deprecate for `feed`
Checkpoint *params.TrustedCheckpoint // Hard coded checkpoint for sync challenges
RequiredBlocks map[uint64]common.Hash // Hard coded map of required block hashes for sync challenges
}
type handler struct {
networkID uint64
forkFilter forkid.Filter // Fork ID filter, constant across the lifetime of the node
snapSync uint32 // Flag whether snap sync is enabled (gets disabled if we already have blocks)
acceptTxs uint32 // Flag whether we're considered synchronised (enables transaction processing)
checkpointNumber uint64 // Block number for the sync progress validator to cross reference
checkpointHash common.Hash // Block hash for the sync progress validator to cross reference
database ethdb.Database
txpool txPool
chain *core.BlockChain
maxPeers int
downloader *downloader.Downloader
blockFetcher *fetcher.BlockFetcher
txFetcher *fetcher.TxFetcher
peers *peerSet
merger *consensus.Merger
eventMux *event.TypeMux
txsCh chan core.NewTxsEvent
txsSub event.Subscription
minedBlockSub *event.TypeMuxSubscription
requiredBlocks map[uint64]common.Hash
// channels for fetcher, syncer, txsyncLoop
quitSync chan struct{}
chainSync *chainSyncer
wg sync.WaitGroup
peerWG sync.WaitGroup
}
// newHandler returns a handler for all Ethereum chain management protocol.
func newHandler(config *handlerConfig) (*handler, error) {
// Create the protocol manager with the base fields
if config.EventMux == nil {
config.EventMux = new(event.TypeMux) // Nicety initialization for tests
}
h := &handler{
networkID: config.Network,
forkFilter: forkid.NewFilter(config.Chain),
eventMux: config.EventMux,
database: config.Database,
txpool: config.TxPool,
chain: config.Chain,
peers: newPeerSet(),
merger: config.Merger,
requiredBlocks: config.RequiredBlocks,
quitSync: make(chan struct{}),
}
if config.Sync == downloader.FullSync {
// The database seems empty as the current block is the genesis. Yet the snap
// block is ahead, so snap sync was enabled for this node at a certain point.
// The scenarios where this can happen is
// * if the user manually (or via a bad block) rolled back a snap sync node
// below the sync point.
// * the last snap sync is not finished while user specifies a full sync this
// time. But we don't have any recent state for full sync.
// In these cases however it's safe to reenable snap sync.
fullBlock, fastBlock := h.chain.CurrentBlock(), h.chain.CurrentFastBlock()
if fullBlock.NumberU64() == 0 && fastBlock.NumberU64() > 0 {
h.snapSync = uint32(1)
log.Warn("Switch sync mode from full sync to snap sync")
}
} else {
if h.chain.CurrentBlock().NumberU64() > 0 {
// Print warning log if database is not empty to run snap sync.
log.Warn("Switch sync mode from snap sync to full sync")
} else {
// If snap sync was requested and our database is empty, grant it
h.snapSync = uint32(1)
}
}
// If we have trusted checkpoints, enforce them on the chain
if config.Checkpoint != nil {
h.checkpointNumber = (config.Checkpoint.SectionIndex+1)*params.CHTFrequency - 1
h.checkpointHash = config.Checkpoint.SectionHead
}
// If sync succeeds, pass a callback to potentially disable snap sync mode
// and enable transaction propagation.
success := func() {
// If we were running snap sync and it finished, disable doing another
// round on next sync cycle
if atomic.LoadUint32(&h.snapSync) == 1 {
log.Info("Snap sync complete, auto disabling")
atomic.StoreUint32(&h.snapSync, 0)
}
// If we've successfully finished a sync cycle and passed any required
// checkpoint, enable accepting transactions from the network
head := h.chain.CurrentBlock()
if head.NumberU64() >= h.checkpointNumber {
// Checkpoint passed, sanity check the timestamp to have a fallback mechanism
// for non-checkpointed (number = 0) private networks.
if head.Time() >= uint64(time.Now().AddDate(0, -1, 0).Unix()) {
atomic.StoreUint32(&h.acceptTxs, 1)
}
}
}
// Construct the downloader (long sync) and its backing state bloom if snap
// sync is requested. The downloader is responsible for deallocating the state
// bloom when it's done.
h.downloader = downloader.New(h.checkpointNumber, config.Database, h.eventMux, h.chain, nil, h.removePeer, success)
// Construct the fetcher (short sync)
validator := func(header *types.Header) error {
// All the block fetcher activities should be disabled
// after the transition. Print the warning log.
if h.merger.PoSFinalized() {
log.Warn("Unexpected validation activity", "hash", header.Hash(), "number", header.Number)
return errors.New("unexpected behavior after transition")
}
// Reject all the PoS style headers in the first place. No matter
// the chain has finished the transition or not, the PoS headers
// should only come from the trusted consensus layer instead of
// p2p network.
if beacon, ok := h.chain.Engine().(*beacon.Beacon); ok {
if beacon.IsPoSHeader(header) {
return errors.New("unexpected post-merge header")
}
}
return h.chain.Engine().VerifyHeader(h.chain, header, true)
}
heighter := func() uint64 {
return h.chain.CurrentBlock().NumberU64()
}
inserter := func(blocks types.Blocks) (int, error) {
// All the block fetcher activities should be disabled
// after the transition. Print the warning log.
if h.merger.PoSFinalized() {
var ctx []interface{}
ctx = append(ctx, "blocks", len(blocks))
if len(blocks) > 0 {
ctx = append(ctx, "firsthash", blocks[0].Hash())
ctx = append(ctx, "firstnumber", blocks[0].Number())
ctx = append(ctx, "lasthash", blocks[len(blocks)-1].Hash())
ctx = append(ctx, "lastnumber", blocks[len(blocks)-1].Number())
}
log.Warn("Unexpected insertion activity", ctx...)
return 0, errors.New("unexpected behavior after transition")
}
// If sync hasn't reached the checkpoint yet, deny importing weird blocks.
//
// Ideally we would also compare the head block's timestamp and similarly reject
// the propagated block if the head is too old. Unfortunately there is a corner
// case when starting new networks, where the genesis might be ancient (0 unix)
// which would prevent full nodes from accepting it.
if h.chain.CurrentBlock().NumberU64() < h.checkpointNumber {
log.Warn("Unsynced yet, discarded propagated block", "number", blocks[0].Number(), "hash", blocks[0].Hash())
return 0, nil
}
// If snap sync is running, deny importing weird blocks. This is a problematic
// clause when starting up a new network, because snap-syncing miners might not
// accept each others' blocks until a restart. Unfortunately we haven't figured
// out a way yet where nodes can decide unilaterally whether the network is new
// or not. This should be fixed if we figure out a solution.
if atomic.LoadUint32(&h.snapSync) == 1 {
log.Warn("Snap syncing, discarded propagated block", "number", blocks[0].Number(), "hash", blocks[0].Hash())
return 0, nil
}
if h.merger.TDDReached() {
// The blocks from the p2p network is regarded as untrusted
// after the transition. In theory block gossip should be disabled
// entirely whenever the transition is started. But in order to
// handle the transition boundary reorg in the consensus-layer,
// the legacy blocks are still accepted, but only for the terminal
// pow blocks. Spec: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-3675.md#halt-the-importing-of-pow-blocks
for i, block := range blocks {
ptd := h.chain.GetTd(block.ParentHash(), block.NumberU64()-1)
if ptd == nil {
return 0, nil
}
td := new(big.Int).Add(ptd, block.Difficulty())
if !h.chain.Config().IsTerminalPoWBlock(ptd, td) {
log.Info("Filtered out non-termimal pow block", "number", block.NumberU64(), "hash", block.Hash())
return 0, nil
}
if err := h.chain.InsertBlockWithoutSetHead(block); err != nil {
return i, err
}
}
return 0, nil
}
n, err := h.chain.InsertChain(blocks)
if err == nil {
atomic.StoreUint32(&h.acceptTxs, 1) // Mark initial sync done on any fetcher import
}
return n, err
}
h.blockFetcher = fetcher.NewBlockFetcher(false, nil, h.chain.GetBlockByHash, validator, h.BroadcastBlock, heighter, nil, inserter, h.removePeer)
fetchTx := func(peer string, hashes []common.Hash) error {
p := h.peers.peer(peer)
if p == nil {
return errors.New("unknown peer")
}
return p.RequestTxs(hashes)
}
h.txFetcher = fetcher.NewTxFetcher(h.txpool.Has, h.txpool.AddRemotes, fetchTx)
h.chainSync = newChainSyncer(h)
return h, nil
}
// runEthPeer registers an eth peer into the joint eth/snap peerset, adds it to
// various subsystems and starts handling messages.
func (h *handler) runEthPeer(peer *eth.Peer, handler eth.Handler) error {
// If the peer has a `snap` extension, wait for it to connect so we can have
// a uniform initialization/teardown mechanism
snap, err := h.peers.waitSnapExtension(peer)
if err != nil {
peer.Log().Error("Snapshot extension barrier failed", "err", err)
return err
}
// TODO(karalabe): Not sure why this is needed
if !h.chainSync.handlePeerEvent(peer) {
return p2p.DiscQuitting
}
h.peerWG.Add(1)
defer h.peerWG.Done()
// Execute the Ethereum handshake
var (
genesis = h.chain.Genesis()
head = h.chain.CurrentHeader()
hash = head.Hash()
number = head.Number.Uint64()
td = h.chain.GetTd(hash, number)
)
forkID := forkid.NewID(h.chain.Config(), h.chain.Genesis().Hash(), h.chain.CurrentHeader().Number.Uint64())
if err := peer.Handshake(h.networkID, td, hash, genesis.Hash(), forkID, h.forkFilter); err != nil {
peer.Log().Debug("Ethereum handshake failed", "err", err)
return err
}
reject := false // reserved peer slots
if atomic.LoadUint32(&h.snapSync) == 1 {
if snap == nil {
// If we are running snap-sync, we want to reserve roughly half the peer
// slots for peers supporting the snap protocol.
// The logic here is; we only allow up to 5 more non-snap peers than snap-peers.
if all, snp := h.peers.len(), h.peers.snapLen(); all-snp > snp+5 {
reject = true
}
}
}
// Ignore maxPeers if this is a trusted peer
if !peer.Peer.Info().Network.Trusted {
if reject || h.peers.len() >= h.maxPeers {
return p2p.DiscTooManyPeers
}
}
peer.Log().Debug("Ethereum peer connected", "name", peer.Name())
// Register the peer locally
if err := h.peers.registerPeer(peer, snap); err != nil {
peer.Log().Error("Ethereum peer registration failed", "err", err)
return err
}
defer h.unregisterPeer(peer.ID())
p := h.peers.peer(peer.ID())
if p == nil {
return errors.New("peer dropped during handling")
}
// Register the peer in the downloader. If the downloader considers it banned, we disconnect
if err := h.downloader.RegisterPeer(peer.ID(), peer.Version(), peer); err != nil {
peer.Log().Error("Failed to register peer in eth syncer", "err", err)
return err
}
if snap != nil {
if err := h.downloader.SnapSyncer.Register(snap); err != nil {
peer.Log().Error("Failed to register peer in snap syncer", "err", err)
return err
}
}
h.chainSync.handlePeerEvent(peer)
// Propagate existing transactions. new transactions appearing
// after this will be sent via broadcasts.
h.syncTransactions(peer)
// Create a notification channel for pending requests if the peer goes down
dead := make(chan struct{})
defer close(dead)
// If we have a trusted CHT, reject all peers below that (avoid fast sync eclipse)
if h.checkpointHash != (common.Hash{}) {
// Request the peer's checkpoint header for chain height/weight validation
resCh := make(chan *eth.Response)
if _, err := peer.RequestHeadersByNumber(h.checkpointNumber, 1, 0, false, resCh); err != nil {
return err
}
// Start a timer to disconnect if the peer doesn't reply in time
go func() {
timeout := time.NewTimer(syncChallengeTimeout)
defer timeout.Stop()
select {
case res := <-resCh:
headers := ([]*types.Header)(*res.Res.(*eth.BlockHeadersPacket))
if len(headers) == 0 {
// If we're doing a snap sync, we must enforce the checkpoint
// block to avoid eclipse attacks. Unsynced nodes are welcome
// to connect after we're done joining the network.
if atomic.LoadUint32(&h.snapSync) == 1 {
peer.Log().Warn("Dropping unsynced node during sync", "addr", peer.RemoteAddr(), "type", peer.Name())
res.Done <- errors.New("unsynced node cannot serve sync")
return
}
res.Done <- nil
return
}
// Validate the header and either drop the peer or continue
if len(headers) > 1 {
res.Done <- errors.New("too many headers in checkpoint response")
return
}
if headers[0].Hash() != h.checkpointHash {
res.Done <- errors.New("checkpoint hash mismatch")
return
}
res.Done <- nil
case <-timeout.C:
peer.Log().Warn("Checkpoint challenge timed out, dropping", "addr", peer.RemoteAddr(), "type", peer.Name())
h.removePeer(peer.ID())
case <-dead:
// Peer handler terminated, abort all goroutines
}
}()
}
// If we have any explicit peer required block hashes, request them
for number, hash := range h.requiredBlocks {
resCh := make(chan *eth.Response)
if _, err := peer.RequestHeadersByNumber(number, 1, 0, false, resCh); err != nil {
return err
}
go func(number uint64, hash common.Hash) {
timeout := time.NewTimer(syncChallengeTimeout)
defer timeout.Stop()
select {
case res := <-resCh:
headers := ([]*types.Header)(*res.Res.(*eth.BlockHeadersPacket))
if len(headers) == 0 {
// Required blocks are allowed to be missing if the remote
// node is not yet synced
res.Done <- nil
return
}
// Validate the header and either drop the peer or continue
if len(headers) > 1 {
res.Done <- errors.New("too many headers in required block response")
return
}
if headers[0].Number.Uint64() != number || headers[0].Hash() != hash {
peer.Log().Info("Required block mismatch, dropping peer", "number", number, "hash", headers[0].Hash(), "want", hash)
res.Done <- errors.New("required block mismatch")
return
}
peer.Log().Debug("Peer required block verified", "number", number, "hash", hash)
res.Done <- nil
case <-timeout.C:
peer.Log().Warn("Required block challenge timed out, dropping", "addr", peer.RemoteAddr(), "type", peer.Name())
h.removePeer(peer.ID())
}
}(number, hash)
}
// Handle incoming messages until the connection is torn down
return handler(peer)
}
// runSnapExtension registers a `snap` peer into the joint eth/snap peerset and
// starts handling inbound messages. As `snap` is only a satellite protocol to
// `eth`, all subsystem registrations and lifecycle management will be done by
// the main `eth` handler to prevent strange races.
func (h *handler) runSnapExtension(peer *snap.Peer, handler snap.Handler) error {
h.peerWG.Add(1)
defer h.peerWG.Done()
if err := h.peers.registerSnapExtension(peer); err != nil {
peer.Log().Warn("Snapshot extension registration failed", "err", err)
return err
}
return handler(peer)
}
// removePeer requests disconnection of a peer.
func (h *handler) removePeer(id string) {
peer := h.peers.peer(id)
if peer != nil {
peer.Peer.Disconnect(p2p.DiscUselessPeer)
}
}
// unregisterPeer removes a peer from the downloader, fetchers and main peer set.
func (h *handler) unregisterPeer(id string) {
// Create a custom logger to avoid printing the entire id
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])
}
// Abort if the peer does not exist
peer := h.peers.peer(id)
if peer == nil {
logger.Error("Ethereum peer removal failed", "err", errPeerNotRegistered)
return
}
// Remove the `eth` peer if it exists
logger.Debug("Removing Ethereum peer", "snap", peer.snapExt != nil)
// Remove the `snap` extension if it exists
if peer.snapExt != nil {
h.downloader.SnapSyncer.Unregister(id)
}
h.downloader.UnregisterPeer(id)
h.txFetcher.Drop(id)
if err := h.peers.unregisterPeer(id); err != nil {
logger.Error("Ethereum peer removal failed", "err", err)
}
}
func (h *handler) Start(maxPeers int) {
h.maxPeers = maxPeers
// broadcast transactions
h.wg.Add(1)
h.txsCh = make(chan core.NewTxsEvent, txChanSize)
h.txsSub = h.txpool.SubscribeNewTxsEvent(h.txsCh)
go h.txBroadcastLoop()
// broadcast mined blocks
h.wg.Add(1)
h.minedBlockSub = h.eventMux.Subscribe(core.NewMinedBlockEvent{})
go h.minedBroadcastLoop()
// start sync handlers
h.wg.Add(1)
go h.chainSync.loop()
}
func (h *handler) Stop() {
h.txsSub.Unsubscribe() // quits txBroadcastLoop
h.minedBlockSub.Unsubscribe() // quits blockBroadcastLoop
// Quit chainSync and txsync64.
// After this is done, no new peers will be accepted.
close(h.quitSync)
h.wg.Wait()
// Disconnect existing sessions.
// This also closes the gate for any new registrations on the peer set.
// sessions which are already established but not added to h.peers yet
// will exit when they try to register.
h.peers.close()
h.peerWG.Wait()
log.Info("Ethereum protocol stopped")
}
// BroadcastBlock will either propagate a block to a subset of its peers, or
// will only announce its availability (depending what's requested).
func (h *handler) BroadcastBlock(block *types.Block, propagate bool) {
// Disable the block propagation if the chain has already entered the PoS
// stage. The block propagation is delegated to the consensus layer.
if h.merger.PoSFinalized() {
return
}
// Disable the block propagation if it's the post-merge block.
if beacon, ok := h.chain.Engine().(*beacon.Beacon); ok {
if beacon.IsPoSHeader(block.Header()) {
return
}
}
hash := block.Hash()
peers := h.peers.peersWithoutBlock(hash)
// If propagation is requested, send to a subset of the peer
if propagate {
// Calculate the TD of the block (it's not imported yet, so block.Td is not valid)
var td *big.Int
if parent := h.chain.GetBlock(block.ParentHash(), block.NumberU64()-1); parent != nil {
td = new(big.Int).Add(block.Difficulty(), h.chain.GetTd(block.ParentHash(), block.NumberU64()-1))
} else {
log.Error("Propagating dangling block", "number", block.Number(), "hash", hash)
return
}
// Send the block to a subset of our peers
transfer := peers[:int(math.Sqrt(float64(len(peers))))]
for _, peer := range transfer {
peer.AsyncSendNewBlock(block, td)
}
log.Trace("Propagated block", "hash", hash, "recipients", len(transfer), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
return
}
// Otherwise if the block is indeed in out own chain, announce it
if h.chain.HasBlock(hash, block.NumberU64()) {
for _, peer := range peers {
peer.AsyncSendNewBlockHash(block)
}
log.Trace("Announced block", "hash", hash, "recipients", len(peers), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
}
}
// BroadcastTransactions will propagate a batch of transactions
// - To a square root of all peers
// - And, separately, as announcements to all peers which are not known to
// already have the given transaction.
func (h *handler) BroadcastTransactions(txs types.Transactions) {
var (
annoCount int // Count of announcements made
annoPeers int
directCount int // Count of the txs sent directly to peers
directPeers int // Count of the peers that were sent transactions directly
txset = make(map[*ethPeer][]common.Hash) // Set peer->hash to transfer directly
annos = make(map[*ethPeer][]common.Hash) // Set peer->hash to announce
)
// Broadcast transactions to a batch of peers not knowing about it
for _, tx := range txs {
peers := h.peers.peersWithoutTransaction(tx.Hash())
// Send the tx unconditionally to a subset of our peers
numDirect := int(math.Sqrt(float64(len(peers))))
for _, peer := range peers[:numDirect] {
txset[peer] = append(txset[peer], tx.Hash())
}
// For the remaining peers, send announcement only
for _, peer := range peers[numDirect:] {
annos[peer] = append(annos[peer], tx.Hash())
}
}
for peer, hashes := range txset {
directPeers++
directCount += len(hashes)
peer.AsyncSendTransactions(hashes)
}
for peer, hashes := range annos {
annoPeers++
annoCount += len(hashes)
peer.AsyncSendPooledTransactionHashes(hashes)
}
log.Debug("Transaction broadcast", "txs", len(txs),
"announce packs", annoPeers, "announced hashes", annoCount,
"tx packs", directPeers, "broadcast txs", directCount)
}
// minedBroadcastLoop sends mined blocks to connected peers.
func (h *handler) minedBroadcastLoop() {
defer h.wg.Done()
for obj := range h.minedBlockSub.Chan() {
if ev, ok := obj.Data.(core.NewMinedBlockEvent); ok {
h.BroadcastBlock(ev.Block, true) // First propagate block to peers
h.BroadcastBlock(ev.Block, false) // Only then announce to the rest
}
}
}
// txBroadcastLoop announces new transactions to connected peers.
func (h *handler) txBroadcastLoop() {
defer h.wg.Done()
for {
select {
case event := <-h.txsCh:
h.BroadcastTransactions(event.Txs)
case <-h.txsSub.Err():
return
}
}
}
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