Official Go implementation of the Ethereum protocol
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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/core"
"github.com/ethereum/go-ethereum/core/forkid"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/txpool"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/crypto"
"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/metrics"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/triedb/pathdb"
)
const (
// txChanSize is the size of channel listening to NewTxsEvent.
// The number is referenced from the size of tx pool.
txChanSize = 4096
// txMaxBroadcastSize is the max size of a transaction that will be broadcasted.
// All transactions with a higher size will be announced and need to be fetched
// by the peer.
txMaxBroadcastSize = 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
// Add should add the given transactions to the pool.
Add(txs []*types.Transaction, local bool, sync bool) []error
// Pending should return pending transactions.
// The slice should be modifiable by the caller.
Pending(filter txpool.PendingFilter) map[common.Address][]*txpool.LazyTransaction
// SubscribeTransactions subscribes to new transaction events. The subscriber
// can decide whether to receive notifications only for newly seen transactions
// or also for reorged out ones.
SubscribeTransactions(ch chan<- core.NewTxsEvent, reorgs bool) event.Subscription
}
// handlerConfig is the collection of initialization parameters to create a full
// node network handler.
type handlerConfig struct {
NodeID enode.ID // P2P node ID used for tx propagation topology
Database ethdb.Database // Database for direct sync insertions
Chain *core.BlockChain // Blockchain to serve data from
TxPool txPool // Transaction pool to propagate from
Network uint64 // Network identifier to advertise
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`
RequiredBlocks map[uint64]common.Hash // Hard coded map of required block hashes for sync challenges
}
type handler struct {
nodeID enode.ID
networkID uint64
forkFilter forkid.Filter // Fork ID filter, constant across the lifetime of the node
snapSync atomic.Bool // Flag whether snap sync is enabled (gets disabled if we already have blocks)
synced atomic.Bool // Flag whether we're considered synchronised (enables transaction processing)
database ethdb.Database
txpool txPool
chain *core.BlockChain
maxPeers int
downloader *downloader.Downloader
txFetcher *fetcher.TxFetcher
peers *peerSet
eventMux *event.TypeMux
txsCh chan core.NewTxsEvent
txsSub event.Subscription
requiredBlocks map[uint64]common.Hash
// channels for fetcher, syncer, txsyncLoop
quitSync chan struct{}
wg sync.WaitGroup
handlerStartCh chan struct{}
handlerDoneCh chan struct{}
}
// 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{
nodeID: config.NodeID,
networkID: config.Network,
forkFilter: forkid.NewFilter(config.Chain),
eventMux: config.EventMux,
database: config.Database,
txpool: config.TxPool,
chain: config.Chain,
peers: newPeerSet(),
requiredBlocks: config.RequiredBlocks,
quitSync: make(chan struct{}),
handlerDoneCh: make(chan struct{}),
handlerStartCh: 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, snapBlock := h.chain.CurrentBlock(), h.chain.CurrentSnapBlock()
if fullBlock.Number.Uint64() == 0 && snapBlock.Number.Uint64() > 0 {
h.snapSync.Store(true)
log.Warn("Switch sync mode from full sync to snap sync", "reason", "snap sync incomplete")
} else if !h.chain.HasState(fullBlock.Root) {
h.snapSync.Store(true)
log.Warn("Switch sync mode from full sync to snap sync", "reason", "head state missing")
}
} else {
head := h.chain.CurrentBlock()
if head.Number.Uint64() > 0 && h.chain.HasState(head.Root) {
// Print warning log if database is not empty to run snap sync.
log.Warn("Switch sync mode from snap sync to full sync", "reason", "snap sync complete")
} else {
// If snap sync was requested and our database is empty, grant it
h.snapSync.Store(true)
log.Info("Enabled snap sync", "head", head.Number, "hash", head.Hash())
}
}
// If snap sync is requested but snapshots are disabled, fail loudly
if h.snapSync.Load() && config.Chain.Snapshots() == nil {
return nil, errors.New("snap sync not supported with snapshots disabled")
}
// Construct the downloader (long sync)
h.downloader = downloader.New(config.Database, h.eventMux, h.chain, h.removePeer, h.enableSyncedFeatures)
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)
}
addTxs := func(txs []*types.Transaction) []error {
return h.txpool.Add(txs, false, false)
}
h.txFetcher = fetcher.NewTxFetcher(h.txpool.Has, addTxs, fetchTx, h.removePeer)
return h, nil
}
// protoTracker tracks the number of active protocol handlers.
func (h *handler) protoTracker() {
defer h.wg.Done()
var active int
for {
select {
case <-h.handlerStartCh:
active++
case <-h.handlerDoneCh:
active--
case <-h.quitSync:
// Wait for all active handlers to finish.
for ; active > 0; active-- {
<-h.handlerDoneCh
}
return
}
}
}
// incHandlers signals to increment the number of active handlers if not
// quitting.
func (h *handler) incHandlers() bool {
select {
case h.handlerStartCh <- struct{}{}:
return true
case <-h.quitSync:
return false
}
}
// decHandlers signals to decrement the number of active handlers.
func (h *handler) decHandlers() {
h.handlerDoneCh <- struct{}{}
}
// 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 !h.incHandlers() {
return p2p.DiscQuitting
}
defer h.decHandlers()
// 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
}
// 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(), genesis, number, head.Time)
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 h.snapSync.Load() {
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
}
}
// 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 any explicit peer required block hashes, request them
for number, hash := range h.requiredBlocks {
resCh := make(chan *eth.Response)
req, err := peer.RequestHeadersByNumber(number, 1, 0, false, resCh)
if err != nil {
return err
}
go func(number uint64, hash common.Hash, req *eth.Request) {
// Ensure the request gets cancelled in case of error/drop
defer req.Close()
timeout := time.NewTimer(syncChallengeTimeout)
defer timeout.Stop()
select {
case res := <-resCh:
headers := ([]*types.Header)(*res.Res.(*eth.BlockHeadersRequest))
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, req)
}
// 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 {
if !h.incHandlers() {
return p2p.DiscQuitting
}
defer h.decHandlers()
if err := h.peers.registerSnapExtension(peer); err != nil {
if metrics.Enabled {
if peer.Inbound() {
snap.IngressRegistrationErrorMeter.Mark(1)
} else {
snap.EgressRegistrationErrorMeter.Mark(1)
}
}
peer.Log().Debug("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 and announce transactions (only new ones, not resurrected ones)
h.wg.Add(1)
h.txsCh = make(chan core.NewTxsEvent, txChanSize)
h.txsSub = h.txpool.SubscribeTransactions(h.txsCh, false)
go h.txBroadcastLoop()
// start sync handlers
h.txFetcher.Start()
// start peer handler tracker
h.wg.Add(1)
go h.protoTracker()
}
func (h *handler) Stop() {
h.txsSub.Unsubscribe() // quits txBroadcastLoop
h.txFetcher.Stop()
h.downloader.Terminate()
// Quit chainSync and txsync64.
// After this is done, no new peers will be accepted.
close(h.quitSync)
// 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.wg.Wait()
log.Info("Ethereum protocol stopped")
}
// BroadcastTransactions will propagate a batch of transactions
// - To a square root of all peers for non-blob transactions
// - 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 (
blobTxs int // Number of blob transactions to announce only
largeTxs int // Number of large transactions to announce only
directCount int // Number of transactions sent directly to peers (duplicates included)
annCount int // Number of transactions announced across all peers (duplicates included)
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
direct := big.NewInt(int64(math.Sqrt(float64(h.peers.len())))) // Approximate number of peers to broadcast to
if direct.BitLen() == 0 {
direct = big.NewInt(1)
}
total := new(big.Int).Exp(direct, big.NewInt(2), nil) // Stabilise total peer count a bit based on sqrt peers
var (
signer = types.LatestSignerForChainID(h.chain.Config().ChainID) // Don't care about chain status, we just need *a* sender
hasher = crypto.NewKeccakState()
hash = make([]byte, 32)
)
for _, tx := range txs {
var maybeDirect bool
switch {
case tx.Type() == types.BlobTxType:
blobTxs++
case tx.Size() > txMaxBroadcastSize:
largeTxs++
default:
maybeDirect = true
}
// Send the transaction (if it's small enough) directly to a subset of
// the peers that have not received it yet, ensuring that the flow of
// transactions is grouped by account to (try and) avoid nonce gaps.
//
// To do this, we hash the local enode IW with together with a peer's
// enode ID together with the transaction sender and broadcast if
// `sha(self, peer, sender) mod peers < sqrt(peers)`.
for _, peer := range h.peers.peersWithoutTransaction(tx.Hash()) {
var broadcast bool
if maybeDirect {
hasher.Reset()
hasher.Write(h.nodeID.Bytes())
hasher.Write(peer.Node().ID().Bytes())
from, _ := types.Sender(signer, tx) // Ignore error, we only use the addr as a propagation target splitter
hasher.Write(from.Bytes())
hasher.Read(hash)
if new(big.Int).Mod(new(big.Int).SetBytes(hash), total).Cmp(direct) < 0 {
broadcast = true
}
}
if broadcast {
txset[peer] = append(txset[peer], tx.Hash())
} else {
annos[peer] = append(annos[peer], tx.Hash())
}
}
}
for peer, hashes := range txset {
directCount += len(hashes)
peer.AsyncSendTransactions(hashes)
}
for peer, hashes := range annos {
annCount += len(hashes)
peer.AsyncSendPooledTransactionHashes(hashes)
}
log.Debug("Distributed transactions", "plaintxs", len(txs)-blobTxs-largeTxs, "blobtxs", blobTxs, "largetxs", largeTxs,
"bcastpeers", len(txset), "bcastcount", directCount, "annpeers", len(annos), "anncount", annCount)
}
// 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
}
}
}
// enableSyncedFeatures enables the post-sync functionalities when the initial
// sync is finished.
func (h *handler) enableSyncedFeatures() {
// Mark the local node as synced.
h.synced.Store(true)
// If we were running snap sync and it finished, disable doing another
// round on next sync cycle
if h.snapSync.Load() {
log.Info("Snap sync complete, auto disabling")
h.snapSync.Store(false)
}
if h.chain.TrieDB().Scheme() == rawdb.PathScheme {
h.chain.TrieDB().SetBufferSize(pathdb.DefaultBufferSize)
}
}