plugeth/p2p/discover/table.go
Martin Holst Swende b8d44ed98b
log: remove lazy, remove unused interfaces, unexport methods (#28622)
This change 

- Removes interface `log.Format`, 
- Removes method `log.FormatFunc`, 
- unexports `TerminalHandler.TerminalFormat` formatting methods (renamed to `TerminalHandler.format`)
- removes the notion of `log.Lazy` values


The lazy handler was useful in the old log package, since it
could defer the evaluation of costly attributes until later in the
log pipeline: thus, if the logging was done at 'Trace', we could
skip evaluation if logging only was set to 'Info'.

With the move to slog, this way of deferring evaluation is no longer
needed, since slog introduced 'Enabled': the caller can thus do
the evaluate-or-not decision at the callsite, which is much more
straight-forward than dealing with lazy reflect-based evaluation.

Also, lazy evaluation would not work with 'native' slog, as in, these
two statements would be evaluated differently:

```golang
  log.Info("foo", "my lazy", lazyObj)
  slog.Info("foo", "my lazy", lazyObj)
```
2023-12-05 11:54:44 +01:00

735 lines
20 KiB
Go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package discover implements the Node Discovery Protocol.
//
// The Node Discovery protocol provides a way to find RLPx nodes that
// can be connected to. It uses a Kademlia-like protocol to maintain a
// distributed database of the IDs and endpoints of all listening
// nodes.
package discover
import (
"context"
crand "crypto/rand"
"encoding/binary"
"fmt"
mrand "math/rand"
"net"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/netutil"
)
const (
alpha = 3 // Kademlia concurrency factor
bucketSize = 16 // Kademlia bucket size
maxReplacements = 10 // Size of per-bucket replacement list
// We keep buckets for the upper 1/15 of distances because
// it's very unlikely we'll ever encounter a node that's closer.
hashBits = len(common.Hash{}) * 8
nBuckets = hashBits / 15 // Number of buckets
bucketMinDistance = hashBits - nBuckets // Log distance of closest bucket
// IP address limits.
bucketIPLimit, bucketSubnet = 2, 24 // at most 2 addresses from the same /24
tableIPLimit, tableSubnet = 10, 24
copyNodesInterval = 30 * time.Second
seedMinTableTime = 5 * time.Minute
seedCount = 30
seedMaxAge = 5 * 24 * time.Hour
)
// Table is the 'node table', a Kademlia-like index of neighbor nodes. The table keeps
// itself up-to-date by verifying the liveness of neighbors and requesting their node
// records when announcements of a new record version are received.
type Table struct {
mutex sync.Mutex // protects buckets, bucket content, nursery, rand
buckets [nBuckets]*bucket // index of known nodes by distance
nursery []*node // bootstrap nodes
rand *mrand.Rand // source of randomness, periodically reseeded
ips netutil.DistinctNetSet
db *enode.DB // database of known nodes
net transport
cfg Config
log log.Logger
// loop channels
refreshReq chan chan struct{}
initDone chan struct{}
closeReq chan struct{}
closed chan struct{}
nodeAddedHook func(*bucket, *node)
nodeRemovedHook func(*bucket, *node)
}
// transport is implemented by the UDP transports.
type transport interface {
Self() *enode.Node
RequestENR(*enode.Node) (*enode.Node, error)
lookupRandom() []*enode.Node
lookupSelf() []*enode.Node
ping(*enode.Node) (seq uint64, err error)
}
// bucket contains nodes, ordered by their last activity. the entry
// that was most recently active is the first element in entries.
type bucket struct {
entries []*node // live entries, sorted by time of last contact
replacements []*node // recently seen nodes to be used if revalidation fails
ips netutil.DistinctNetSet
index int
}
func newTable(t transport, db *enode.DB, cfg Config) (*Table, error) {
cfg = cfg.withDefaults()
tab := &Table{
net: t,
db: db,
cfg: cfg,
log: cfg.Log,
refreshReq: make(chan chan struct{}),
initDone: make(chan struct{}),
closeReq: make(chan struct{}),
closed: make(chan struct{}),
rand: mrand.New(mrand.NewSource(0)),
ips: netutil.DistinctNetSet{Subnet: tableSubnet, Limit: tableIPLimit},
}
if err := tab.setFallbackNodes(cfg.Bootnodes); err != nil {
return nil, err
}
for i := range tab.buckets {
tab.buckets[i] = &bucket{
index: i,
ips: netutil.DistinctNetSet{Subnet: bucketSubnet, Limit: bucketIPLimit},
}
}
tab.seedRand()
tab.loadSeedNodes()
return tab, nil
}
func newMeteredTable(t transport, db *enode.DB, cfg Config) (*Table, error) {
tab, err := newTable(t, db, cfg)
if err != nil {
return nil, err
}
if metrics.Enabled {
tab.nodeAddedHook = func(b *bucket, n *node) {
bucketsCounter[b.index].Inc(1)
}
tab.nodeRemovedHook = func(b *bucket, n *node) {
bucketsCounter[b.index].Dec(1)
}
}
return tab, nil
}
// Nodes returns all nodes contained in the table.
func (tab *Table) Nodes() []*enode.Node {
if !tab.isInitDone() {
return nil
}
tab.mutex.Lock()
defer tab.mutex.Unlock()
var nodes []*enode.Node
for _, b := range &tab.buckets {
for _, n := range b.entries {
nodes = append(nodes, unwrapNode(n))
}
}
return nodes
}
func (tab *Table) self() *enode.Node {
return tab.net.Self()
}
func (tab *Table) seedRand() {
var b [8]byte
crand.Read(b[:])
tab.mutex.Lock()
tab.rand.Seed(int64(binary.BigEndian.Uint64(b[:])))
tab.mutex.Unlock()
}
// getNode returns the node with the given ID or nil if it isn't in the table.
func (tab *Table) getNode(id enode.ID) *enode.Node {
tab.mutex.Lock()
defer tab.mutex.Unlock()
b := tab.bucket(id)
for _, e := range b.entries {
if e.ID() == id {
return unwrapNode(e)
}
}
return nil
}
// close terminates the network listener and flushes the node database.
func (tab *Table) close() {
close(tab.closeReq)
<-tab.closed
}
// setFallbackNodes sets the initial points of contact. These nodes
// are used to connect to the network if the table is empty and there
// are no known nodes in the database.
func (tab *Table) setFallbackNodes(nodes []*enode.Node) error {
nursery := make([]*node, 0, len(nodes))
for _, n := range nodes {
if err := n.ValidateComplete(); err != nil {
return fmt.Errorf("bad bootstrap node %q: %v", n, err)
}
if tab.cfg.NetRestrict != nil && !tab.cfg.NetRestrict.Contains(n.IP()) {
tab.log.Error("Bootstrap node filtered by netrestrict", "id", n.ID(), "ip", n.IP())
continue
}
nursery = append(nursery, wrapNode(n))
}
tab.nursery = nursery
return nil
}
// isInitDone returns whether the table's initial seeding procedure has completed.
func (tab *Table) isInitDone() bool {
select {
case <-tab.initDone:
return true
default:
return false
}
}
func (tab *Table) refresh() <-chan struct{} {
done := make(chan struct{})
select {
case tab.refreshReq <- done:
case <-tab.closeReq:
close(done)
}
return done
}
// loop schedules runs of doRefresh, doRevalidate and copyLiveNodes.
func (tab *Table) loop() {
var (
revalidate = time.NewTimer(tab.nextRevalidateTime())
refresh = time.NewTimer(tab.nextRefreshTime())
copyNodes = time.NewTicker(copyNodesInterval)
refreshDone = make(chan struct{}) // where doRefresh reports completion
revalidateDone chan struct{} // where doRevalidate reports completion
waiting = []chan struct{}{tab.initDone} // holds waiting callers while doRefresh runs
)
defer refresh.Stop()
defer revalidate.Stop()
defer copyNodes.Stop()
// Start initial refresh.
go tab.doRefresh(refreshDone)
loop:
for {
select {
case <-refresh.C:
tab.seedRand()
if refreshDone == nil {
refreshDone = make(chan struct{})
go tab.doRefresh(refreshDone)
}
case req := <-tab.refreshReq:
waiting = append(waiting, req)
if refreshDone == nil {
refreshDone = make(chan struct{})
go tab.doRefresh(refreshDone)
}
case <-refreshDone:
for _, ch := range waiting {
close(ch)
}
waiting, refreshDone = nil, nil
refresh.Reset(tab.nextRefreshTime())
case <-revalidate.C:
revalidateDone = make(chan struct{})
go tab.doRevalidate(revalidateDone)
case <-revalidateDone:
revalidate.Reset(tab.nextRevalidateTime())
revalidateDone = nil
case <-copyNodes.C:
go tab.copyLiveNodes()
case <-tab.closeReq:
break loop
}
}
if refreshDone != nil {
<-refreshDone
}
for _, ch := range waiting {
close(ch)
}
if revalidateDone != nil {
<-revalidateDone
}
close(tab.closed)
}
// doRefresh performs a lookup for a random target to keep buckets full. seed nodes are
// inserted if the table is empty (initial bootstrap or discarded faulty peers).
func (tab *Table) doRefresh(done chan struct{}) {
defer close(done)
// Load nodes from the database and insert
// them. This should yield a few previously seen nodes that are
// (hopefully) still alive.
tab.loadSeedNodes()
// Run self lookup to discover new neighbor nodes.
tab.net.lookupSelf()
// The Kademlia paper specifies that the bucket refresh should
// perform a lookup in the least recently used bucket. We cannot
// adhere to this because the findnode target is a 512bit value
// (not hash-sized) and it is not easily possible to generate a
// sha3 preimage that falls into a chosen bucket.
// We perform a few lookups with a random target instead.
for i := 0; i < 3; i++ {
tab.net.lookupRandom()
}
}
func (tab *Table) loadSeedNodes() {
seeds := wrapNodes(tab.db.QuerySeeds(seedCount, seedMaxAge))
seeds = append(seeds, tab.nursery...)
for i := range seeds {
seed := seeds[i]
if tab.log.Enabled(context.Background(), log.LevelTrace) {
age := time.Since(tab.db.LastPongReceived(seed.ID(), seed.IP()))
tab.log.Trace("Found seed node in database", "id", seed.ID(), "addr", seed.addr(), "age", age)
}
tab.addSeenNode(seed)
}
}
// doRevalidate checks that the last node in a random bucket is still live and replaces or
// deletes the node if it isn't.
func (tab *Table) doRevalidate(done chan<- struct{}) {
defer func() { done <- struct{}{} }()
last, bi := tab.nodeToRevalidate()
if last == nil {
// No non-empty bucket found.
return
}
// Ping the selected node and wait for a pong.
remoteSeq, err := tab.net.ping(unwrapNode(last))
// Also fetch record if the node replied and returned a higher sequence number.
if last.Seq() < remoteSeq {
n, err := tab.net.RequestENR(unwrapNode(last))
if err != nil {
tab.log.Debug("ENR request failed", "id", last.ID(), "addr", last.addr(), "err", err)
} else {
last = &node{Node: *n, addedAt: last.addedAt, livenessChecks: last.livenessChecks}
}
}
tab.mutex.Lock()
defer tab.mutex.Unlock()
b := tab.buckets[bi]
if err == nil {
// The node responded, move it to the front.
last.livenessChecks++
tab.log.Debug("Revalidated node", "b", bi, "id", last.ID(), "checks", last.livenessChecks)
tab.bumpInBucket(b, last)
return
}
// No reply received, pick a replacement or delete the node if there aren't
// any replacements.
if r := tab.replace(b, last); r != nil {
tab.log.Debug("Replaced dead node", "b", bi, "id", last.ID(), "ip", last.IP(), "checks", last.livenessChecks, "r", r.ID(), "rip", r.IP())
} else {
tab.log.Debug("Removed dead node", "b", bi, "id", last.ID(), "ip", last.IP(), "checks", last.livenessChecks)
}
}
// nodeToRevalidate returns the last node in a random, non-empty bucket.
func (tab *Table) nodeToRevalidate() (n *node, bi int) {
tab.mutex.Lock()
defer tab.mutex.Unlock()
for _, bi = range tab.rand.Perm(len(tab.buckets)) {
b := tab.buckets[bi]
if len(b.entries) > 0 {
last := b.entries[len(b.entries)-1]
return last, bi
}
}
return nil, 0
}
func (tab *Table) nextRevalidateTime() time.Duration {
tab.mutex.Lock()
defer tab.mutex.Unlock()
return time.Duration(tab.rand.Int63n(int64(tab.cfg.PingInterval)))
}
func (tab *Table) nextRefreshTime() time.Duration {
tab.mutex.Lock()
defer tab.mutex.Unlock()
half := tab.cfg.RefreshInterval / 2
return half + time.Duration(tab.rand.Int63n(int64(half)))
}
// copyLiveNodes adds nodes from the table to the database if they have been in the table
// longer than seedMinTableTime.
func (tab *Table) copyLiveNodes() {
tab.mutex.Lock()
defer tab.mutex.Unlock()
now := time.Now()
for _, b := range &tab.buckets {
for _, n := range b.entries {
if n.livenessChecks > 0 && now.Sub(n.addedAt) >= seedMinTableTime {
tab.db.UpdateNode(unwrapNode(n))
}
}
}
}
// findnodeByID returns the n nodes in the table that are closest to the given id.
// This is used by the FINDNODE/v4 handler.
//
// The preferLive parameter says whether the caller wants liveness-checked results. If
// preferLive is true and the table contains any verified nodes, the result will not
// contain unverified nodes. However, if there are no verified nodes at all, the result
// will contain unverified nodes.
func (tab *Table) findnodeByID(target enode.ID, nresults int, preferLive bool) *nodesByDistance {
tab.mutex.Lock()
defer tab.mutex.Unlock()
// Scan all buckets. There might be a better way to do this, but there aren't that many
// buckets, so this solution should be fine. The worst-case complexity of this loop
// is O(tab.len() * nresults).
nodes := &nodesByDistance{target: target}
liveNodes := &nodesByDistance{target: target}
for _, b := range &tab.buckets {
for _, n := range b.entries {
nodes.push(n, nresults)
if preferLive && n.livenessChecks > 0 {
liveNodes.push(n, nresults)
}
}
}
if preferLive && len(liveNodes.entries) > 0 {
return liveNodes
}
return nodes
}
// len returns the number of nodes in the table.
func (tab *Table) len() (n int) {
tab.mutex.Lock()
defer tab.mutex.Unlock()
for _, b := range &tab.buckets {
n += len(b.entries)
}
return n
}
// bucketLen returns the number of nodes in the bucket for the given ID.
func (tab *Table) bucketLen(id enode.ID) int {
tab.mutex.Lock()
defer tab.mutex.Unlock()
return len(tab.bucket(id).entries)
}
// bucket returns the bucket for the given node ID hash.
func (tab *Table) bucket(id enode.ID) *bucket {
d := enode.LogDist(tab.self().ID(), id)
return tab.bucketAtDistance(d)
}
func (tab *Table) bucketAtDistance(d int) *bucket {
if d <= bucketMinDistance {
return tab.buckets[0]
}
return tab.buckets[d-bucketMinDistance-1]
}
// addSeenNode adds a node which may or may not be live to the end of a bucket. If the
// bucket has space available, adding the node succeeds immediately. Otherwise, the node is
// added to the replacements list.
//
// The caller must not hold tab.mutex.
func (tab *Table) addSeenNode(n *node) {
if n.ID() == tab.self().ID() {
return
}
tab.mutex.Lock()
defer tab.mutex.Unlock()
b := tab.bucket(n.ID())
if contains(b.entries, n.ID()) {
// Already in bucket, don't add.
return
}
if len(b.entries) >= bucketSize {
// Bucket full, maybe add as replacement.
tab.addReplacement(b, n)
return
}
if !tab.addIP(b, n.IP()) {
// Can't add: IP limit reached.
return
}
// Add to end of bucket:
b.entries = append(b.entries, n)
b.replacements = deleteNode(b.replacements, n)
n.addedAt = time.Now()
if tab.nodeAddedHook != nil {
tab.nodeAddedHook(b, n)
}
}
// addVerifiedNode adds a node whose existence has been verified recently to the front of a
// bucket. If the node is already in the bucket, it is moved to the front. If the bucket
// has no space, the node is added to the replacements list.
//
// There is an additional safety measure: if the table is still initializing the node
// is not added. This prevents an attack where the table could be filled by just sending
// ping repeatedly.
//
// The caller must not hold tab.mutex.
func (tab *Table) addVerifiedNode(n *node) {
if !tab.isInitDone() {
return
}
if n.ID() == tab.self().ID() {
return
}
tab.mutex.Lock()
defer tab.mutex.Unlock()
b := tab.bucket(n.ID())
if tab.bumpInBucket(b, n) {
// Already in bucket, moved to front.
return
}
if len(b.entries) >= bucketSize {
// Bucket full, maybe add as replacement.
tab.addReplacement(b, n)
return
}
if !tab.addIP(b, n.IP()) {
// Can't add: IP limit reached.
return
}
// Add to front of bucket.
b.entries, _ = pushNode(b.entries, n, bucketSize)
b.replacements = deleteNode(b.replacements, n)
n.addedAt = time.Now()
if tab.nodeAddedHook != nil {
tab.nodeAddedHook(b, n)
}
}
// delete removes an entry from the node table. It is used to evacuate dead nodes.
func (tab *Table) delete(node *node) {
tab.mutex.Lock()
defer tab.mutex.Unlock()
tab.deleteInBucket(tab.bucket(node.ID()), node)
}
func (tab *Table) addIP(b *bucket, ip net.IP) bool {
if len(ip) == 0 {
return false // Nodes without IP cannot be added.
}
if netutil.IsLAN(ip) {
return true
}
if !tab.ips.Add(ip) {
tab.log.Debug("IP exceeds table limit", "ip", ip)
return false
}
if !b.ips.Add(ip) {
tab.log.Debug("IP exceeds bucket limit", "ip", ip)
tab.ips.Remove(ip)
return false
}
return true
}
func (tab *Table) removeIP(b *bucket, ip net.IP) {
if netutil.IsLAN(ip) {
return
}
tab.ips.Remove(ip)
b.ips.Remove(ip)
}
func (tab *Table) addReplacement(b *bucket, n *node) {
for _, e := range b.replacements {
if e.ID() == n.ID() {
return // already in list
}
}
if !tab.addIP(b, n.IP()) {
return
}
var removed *node
b.replacements, removed = pushNode(b.replacements, n, maxReplacements)
if removed != nil {
tab.removeIP(b, removed.IP())
}
}
// replace removes n from the replacement list and replaces 'last' with it if it is the
// last entry in the bucket. If 'last' isn't the last entry, it has either been replaced
// with someone else or became active.
func (tab *Table) replace(b *bucket, last *node) *node {
if len(b.entries) == 0 || b.entries[len(b.entries)-1].ID() != last.ID() {
// Entry has moved, don't replace it.
return nil
}
// Still the last entry.
if len(b.replacements) == 0 {
tab.deleteInBucket(b, last)
return nil
}
r := b.replacements[tab.rand.Intn(len(b.replacements))]
b.replacements = deleteNode(b.replacements, r)
b.entries[len(b.entries)-1] = r
tab.removeIP(b, last.IP())
return r
}
// bumpInBucket moves the given node to the front of the bucket entry list
// if it is contained in that list.
func (tab *Table) bumpInBucket(b *bucket, n *node) bool {
for i := range b.entries {
if b.entries[i].ID() == n.ID() {
if !n.IP().Equal(b.entries[i].IP()) {
// Endpoint has changed, ensure that the new IP fits into table limits.
tab.removeIP(b, b.entries[i].IP())
if !tab.addIP(b, n.IP()) {
// It doesn't, put the previous one back.
tab.addIP(b, b.entries[i].IP())
return false
}
}
// Move it to the front.
copy(b.entries[1:], b.entries[:i])
b.entries[0] = n
return true
}
}
return false
}
func (tab *Table) deleteInBucket(b *bucket, n *node) {
// Check if the node is actually in the bucket so the removed hook
// isn't called multiple times for the same node.
if !contains(b.entries, n.ID()) {
return
}
b.entries = deleteNode(b.entries, n)
tab.removeIP(b, n.IP())
if tab.nodeRemovedHook != nil {
tab.nodeRemovedHook(b, n)
}
}
func contains(ns []*node, id enode.ID) bool {
for _, n := range ns {
if n.ID() == id {
return true
}
}
return false
}
// pushNode adds n to the front of list, keeping at most max items.
func pushNode(list []*node, n *node, max int) ([]*node, *node) {
if len(list) < max {
list = append(list, nil)
}
removed := list[len(list)-1]
copy(list[1:], list)
list[0] = n
return list, removed
}
// deleteNode removes n from list.
func deleteNode(list []*node, n *node) []*node {
for i := range list {
if list[i].ID() == n.ID() {
return append(list[:i], list[i+1:]...)
}
}
return list
}
// nodesByDistance is a list of nodes, ordered by distance to target.
type nodesByDistance struct {
entries []*node
target enode.ID
}
// push adds the given node to the list, keeping the total size below maxElems.
func (h *nodesByDistance) push(n *node, maxElems int) {
ix := sort.Search(len(h.entries), func(i int) bool {
return enode.DistCmp(h.target, h.entries[i].ID(), n.ID()) > 0
})
end := len(h.entries)
if len(h.entries) < maxElems {
h.entries = append(h.entries, n)
}
if ix < end {
// Slide existing entries down to make room.
// This will overwrite the entry we just appended.
copy(h.entries[ix+1:], h.entries[ix:])
h.entries[ix] = n
}
}