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p2p/discover: improve table addition code (#18974) 

This change clears up confusion around the two ways in which nodes
can be added to the table.

When a neighbors packet is received as a reply to findnode, the nodes
contained in the reply are added as 'seen' entries if sufficient space
is available.

When a ping is received and the endpoint verification has taken place,
the remote node is added as a 'verified' entry or moved to the front of
the bucket if present. This also updates the node's IP address and port
if they have changed.
This commit is contained in:
Felix Lange 2019-01-31 11:48:54 +01:00 committed by Felix Lange
parent d9a07fba67
commit 86ec742f97
4 changed files with 175 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

117
p2p/discover/table.go
View File

@ -328,7 +328,7 @@ func (tab *Table) findnode(n *node, targetKey encPubkey, reply chan<- []*node) {
// Grab as many nodes as possible. Some of them might not be alive anymore, but we'll
// just remove those again during revalidation.
for _, n := range r {
tab.add(n)
tab.addSeenNode(n)
}
reply <- r
}
@ -443,7 +443,7 @@ func (tab *Table) loadSeedNodes() {
seed := seeds[i]
age := log.Lazy{Fn: func() interface{} { return time.Since(tab.db.LastPongReceived(seed.ID(), seed.IP())) }}
log.Trace("Found seed node in database", "id", seed.ID(), "addr", seed.addr(), "age", age)
tab.add(seed)
tab.addSeenNode(seed)
}
}
@ -468,7 +468,7 @@ func (tab *Table) doRevalidate(done chan<- struct{}) {
// The node responded, move it to the front.
last.livenessChecks++
log.Debug("Revalidated node", "b", bi, "id", last.ID(), "checks", last.livenessChecks)
b.bump(last)
tab.bumpInBucket(b, last)
return
}
// No reply received, pick a replacement or delete the node if there aren't
@ -551,12 +551,12 @@ func (tab *Table) bucket(id enode.ID) *bucket {
return tab.buckets[d-bucketMinDistance-1]
}
// add attempts to add the given node to its corresponding bucket. If the bucket has space
// available, adding the node succeeds immediately. Otherwise, the node is added if the
// least recently active node in the bucket does not respond to a ping packet.
// 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) add(n *node) {
func (tab *Table) addSeenNode(n *node) {
if n.ID() == tab.self().ID() {
return
}
@ -564,23 +564,68 @@ func (tab *Table) add(n *node) {
tab.mutex.Lock()
defer tab.mutex.Unlock()
b := tab.bucket(n.ID())
if !tab.bumpOrAdd(b, n) {
// Node is not in table. Add it to the replacement list.
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(n)
}
}
// addThroughPing adds the given node to the table. Compared to plain
// 'add' 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.
// 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) addThroughPing(n *node) {
func (tab *Table) addVerifiedNode(n *node) {
if !tab.isInitDone() {
return
}
tab.add(n)
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(n)
}
}
// delete removes an entry from the node table. It is used to evacuate dead nodes.
@ -651,12 +696,21 @@ func (tab *Table) replace(b *bucket, last *node) *node {
return r
}
// bump moves the given node to the front of the bucket entry list
// bumpInBucket moves the given node to the front of the bucket entry list
// if it is contained in that list.
func (b *bucket) bump(n *node) bool {
func (tab *Table) bumpInBucket(b *bucket, n *node) bool {
for i := range b.entries {
if b.entries[i].ID() == n.ID() {
// move it to the front
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
@ -665,29 +719,20 @@ func (b *bucket) bump(n *node) bool {
return false
}
// bumpOrAdd moves n to the front of the bucket entry list or adds it if the list isn't
// full. The return value is true if n is in the bucket.
func (tab *Table) bumpOrAdd(b *bucket, n *node) bool {
if b.bump(n) {
return true
}
if len(b.entries) >= bucketSize || !tab.addIP(b, n.IP()) {
return false
}
b.entries, _ = pushNode(b.entries, n, bucketSize)
b.replacements = deleteNode(b.replacements, n)
n.addedAt = time.Now()
if tab.nodeAddedHook != nil {
tab.nodeAddedHook(n)
}
return true
}
func (tab *Table) deleteInBucket(b *bucket, n *node) {
b.entries = deleteNode(b.entries, n)
tab.removeIP(b, n.IP())
}
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 {

96
p2p/discover/table_test.go
View File

@ -30,6 +30,7 @@ import (
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/enr"
"github.com/ethereum/go-ethereum/p2p/netutil"
)
func TestTable_pingReplace(t *testing.T) {
@ -64,7 +65,7 @@ func testPingReplace(t *testing.T, newNodeIsResponding, lastInBucketIsResponding
// its bucket if it is unresponsive. Revalidate again to ensure that
transport.dead[last.ID()] = !lastInBucketIsResponding
transport.dead[pingSender.ID()] = !newNodeIsResponding
tab.add(pingSender)
tab.addSeenNode(pingSender)
tab.doRevalidate(make(chan struct{}, 1))
tab.doRevalidate(make(chan struct{}, 1))
@ -114,10 +115,14 @@ func TestBucket_bumpNoDuplicates(t *testing.T) {
}
prop := func(nodes []*node, bumps []int) (ok bool) {
tab, db := newTestTable(newPingRecorder())
defer db.Close()
defer tab.Close()
b := &bucket{entries: make([]*node, len(nodes))}
copy(b.entries, nodes)
for i, pos := range bumps {
b.bump(b.entries[pos])
tab.bumpInBucket(b, b.entries[pos])
if hasDuplicates(b.entries) {
t.Logf("bucket has duplicates after %d/%d bumps:", i+1, len(bumps))
for _, n := range b.entries {
@ -126,6 +131,7 @@ func TestBucket_bumpNoDuplicates(t *testing.T) {
return false
}
}
checkIPLimitInvariant(t, tab)
return true
}
if err := quick.Check(prop, cfg); err != nil {
@ -142,11 +148,12 @@ func TestTable_IPLimit(t *testing.T) {
for i := 0; i < tableIPLimit+1; i++ {
n := nodeAtDistance(tab.self().ID(), i, net.IP{172, 0, 1, byte(i)})
tab.add(n)
tab.addSeenNode(n)
}
if tab.len() > tableIPLimit {
t.Errorf("too many nodes in table")
}
checkIPLimitInvariant(t, tab)
}
// This checks that the per-bucket IP limit is applied correctly.
@ -159,11 +166,28 @@ func TestTable_BucketIPLimit(t *testing.T) {
d := 3
for i := 0; i < bucketIPLimit+1; i++ {
n := nodeAtDistance(tab.self().ID(), d, net.IP{172, 0, 1, byte(i)})
tab.add(n)
tab.addSeenNode(n)
}
if tab.len() > bucketIPLimit {
t.Errorf("too many nodes in table")
}
checkIPLimitInvariant(t, tab)
}
// checkIPLimitInvariant checks that ip limit sets contain an entry for every
// node in the table and no extra entries.
func checkIPLimitInvariant(t *testing.T, tab *Table) {
t.Helper()
tabset := netutil.DistinctNetSet{Subnet: tableSubnet, Limit: tableIPLimit}
for _, b := range tab.buckets {
for _, n := range b.entries {
tabset.Add(n.IP())
}
}
if tabset.String() != tab.ips.String() {
t.Errorf("table IP set is incorrect:\nhave: %v\nwant: %v", tab.ips, tabset)
}
}
func TestTable_closest(t *testing.T) {
@ -281,6 +305,69 @@ func (*closeTest) Generate(rand *rand.Rand, size int) reflect.Value {
return reflect.ValueOf(t)
}
func TestTable_addVerifiedNode(t *testing.T) {
tab, db := newTestTable(newPingRecorder())
<-tab.initDone
defer db.Close()
defer tab.Close()
// Insert two nodes.
n1 := nodeAtDistance(tab.self().ID(), 256, net.IP{88, 77, 66, 1})
n2 := nodeAtDistance(tab.self().ID(), 256, net.IP{88, 77, 66, 2})
tab.addSeenNode(n1)
tab.addSeenNode(n2)
// Verify bucket content:
bcontent := []*node{n1, n2}
if !reflect.DeepEqual(tab.bucket(n1.ID()).entries, bcontent) {
t.Fatalf("wrong bucket content: %v", tab.bucket(n1.ID()).entries)
}
// Add a changed version of n2.
newrec := n2.Record()
newrec.Set(enr.IP{99, 99, 99, 99})
newn2 := wrapNode(enode.SignNull(newrec, n2.ID()))
tab.addVerifiedNode(newn2)
// Check that bucket is updated correctly.
newBcontent := []*node{newn2, n1}
if !reflect.DeepEqual(tab.bucket(n1.ID()).entries, newBcontent) {
t.Fatalf("wrong bucket content after update: %v", tab.bucket(n1.ID()).entries)
}
checkIPLimitInvariant(t, tab)
}
func TestTable_addSeenNode(t *testing.T) {
tab, db := newTestTable(newPingRecorder())
<-tab.initDone
defer db.Close()
defer tab.Close()
// Insert two nodes.
n1 := nodeAtDistance(tab.self().ID(), 256, net.IP{88, 77, 66, 1})
n2 := nodeAtDistance(tab.self().ID(), 256, net.IP{88, 77, 66, 2})
tab.addSeenNode(n1)
tab.addSeenNode(n2)
// Verify bucket content:
bcontent := []*node{n1, n2}
if !reflect.DeepEqual(tab.bucket(n1.ID()).entries, bcontent) {
t.Fatalf("wrong bucket content: %v", tab.bucket(n1.ID()).entries)
}
// Add a changed version of n2.
newrec := n2.Record()
newrec.Set(enr.IP{99, 99, 99, 99})
newn2 := wrapNode(enode.SignNull(newrec, n2.ID()))
tab.addSeenNode(newn2)
// Check that bucket content is unchanged.
if !reflect.DeepEqual(tab.bucket(n1.ID()).entries, bcontent) {
t.Fatalf("wrong bucket content after update: %v", tab.bucket(n1.ID()).entries)
}
checkIPLimitInvariant(t, tab)
}
func TestTable_Lookup(t *testing.T) {
tab, db := newTestTable(lookupTestnet)
defer db.Close()
@ -535,7 +622,6 @@ func (tn *preminedTestnet) findnode(toid enode.ID, toaddr *net.UDPAddr, target e
}
func (*preminedTestnet) close() {}
func (*preminedTestnet) waitping(from enode.ID) error { return nil }
func (*preminedTestnet) ping(toid enode.ID, toaddr *net.UDPAddr) error { return nil }
// mine generates a testnet struct literal with nodes at

20
p2p/discover/table_util_test.go
View File

@ -86,17 +86,8 @@ func fillBucket(tab *Table, n *node) (last *node) {
// fillTable adds nodes the table to the end of their corresponding bucket
// if the bucket is not full. The caller must not hold tab.mutex.
func fillTable(tab *Table, nodes []*node) {
tab.mutex.Lock()
defer tab.mutex.Unlock()
for _, n := range nodes {
if n.ID() == tab.self().ID() {
continue // don't add self
}
b := tab.bucket(n.ID())
if len(b.entries) < bucketSize {
tab.bumpOrAdd(b, n)
}
tab.addSeenNode(n)
}
}
@ -154,15 +145,6 @@ func hasDuplicates(slice []*node) bool {
return false
}
func contains(ns []*node, id enode.ID) bool {
for _, n := range ns {
if n.ID() == id {
return true
}
}
return false
}
func sortedByDistanceTo(distbase enode.ID, slice []*node) bool {
var last enode.ID
for i, e := range slice {

4
p2p/discover/udp.go
View File

@ -661,10 +661,10 @@ func (req *ping) handle(t *udp, from *net.UDPAddr, fromID enode.ID, mac []byte)
n := wrapNode(enode.NewV4(req.senderKey, from.IP, int(req.From.TCP), from.Port))
if time.Since(t.db.LastPongReceived(n.ID(), from.IP)) > bondExpiration {
t.sendPing(fromID, from, func() {
t.tab.addThroughPing(n)
t.tab.addVerifiedNode(n)
})
} else {
t.tab.addThroughPing(n)
t.tab.addVerifiedNode(n)
}
// Update node database and endpoint predictor.