p2p/discover: add Table configuration and Nodes method (ethereum#27387)

* p2p/discover: remove ReadRandomNodes

Even though it's public, this method is not callable by code outside of
package p2p/discover because one can't get a valid instance of Table.

* p2p/discover: add Table.Nodes

* p2p/discover: make Table settings configurable

In unit tests and externally developed cmd/devp2p test runs, it can be
useful to tune the timer intervals used by Table.

p2p/discover/common.go

@@ -19,6 +19,7 @@ package discover
 import (
 	"crypto/ecdsa"
 	"net"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/log"
@@ -35,29 +36,39 @@ type UDPConn interface {
 	LocalAddr() net.Addr
 }
 
-type V5Config struct {
-	ProtocolID *[6]byte
-}
-
 // Config holds settings for the discovery listener.
 type Config struct {
 	// These settings are required and configure the UDP listener:
 	PrivateKey *ecdsa.PrivateKey
 
-	// These settings are optional:
+	// All remaining settings are optional.
+
+	// Packet handling configuration:
 	NetRestrict *netutil.Netlist  // list of allowed IP networks
-	Bootnodes   []*enode.Node     // list of bootstrap nodes
 	Unhandled   chan<- ReadPacket // unhandled packets are sent on this channel
-	Log         log.Logger        // if set, log messages go here
 
-	// V5ProtocolID configures the discv5 protocol identifier.
-	V5ProtocolID *[6]byte
+	// Node table configuration:
+	Bootnodes       []*enode.Node // list of bootstrap nodes
+	PingInterval    time.Duration // speed of node liveness check
+	RefreshInterval time.Duration // used in bucket refresh
 
+	// The options below are useful in very specific cases, like in unit tests.
+	V5ProtocolID *[6]byte
+	Log          log.Logger         // if set, log messages go here
 	ValidSchemes enr.IdentityScheme // allowed identity schemes
 	Clock        mclock.Clock
 }
 
 func (cfg Config) withDefaults() Config {
+	// Node table configuration:
+	if cfg.PingInterval == 0 {
+		cfg.PingInterval = 10 * time.Second
+	}
+	if cfg.RefreshInterval == 0 {
+		cfg.RefreshInterval = 30 * time.Minute
+	}
+
+	// Debug/test settings:
 	if cfg.Log == nil {
 		cfg.Log = log.Root()
 	}

p2p/discover/table.go

@@ -53,12 +53,10 @@ const (
 	bucketIPLimit, bucketSubnet = 2, 24 // at most 2 addresses from the same /24
 	tableIPLimit, tableSubnet   = 10, 24
 
-	refreshInterval    = 30 * time.Minute
-	revalidateInterval = 10 * time.Second
-	copyNodesInterval  = 30 * time.Second
-	seedMinTableTime   = 5 * time.Minute
-	seedCount          = 30
-	seedMaxAge         = 5 * 24 * time.Hour
+	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
@@ -71,9 +69,12 @@ type Table struct {
 	rand    *mrand.Rand       // source of randomness, periodically reseeded
 	ips     netutil.DistinctNetSet
 
-	log        log.Logger
-	db         *enode.DB // database of known nodes
-	net        transport
+	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{}
@@ -99,19 +100,21 @@ type bucket struct {
 	ips          netutil.DistinctNetSet
 }
 
-func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger) (*Table, error) {
+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},
-		log:        log,
 	}
-	if err := tab.setFallbackNodes(bootnodes); err != nil {
+	if err := tab.setFallbackNodes(cfg.Bootnodes); err != nil {
 		return nil, err
 	}
 	for i := range tab.buckets {
@@ -125,25 +128,12 @@ func newTable(t transport, db *enode.DB, bootnodes []*enode.Node, log log.Logger
 	return tab, nil
 }
 
-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()
-}
-
-// ReadRandomNodes fills the given slice with random nodes from the table. The results
-// are guaranteed to be unique for a single invocation, no node will appear twice.
-func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int) {
+// Nodes returns all nodes contained in the table.
+func (tab *Table) Nodes() []*enode.Node {
 	if !tab.isInitDone() {
-		return 0
+		return nil
 	}
+
 	tab.mutex.Lock()
 	defer tab.mutex.Unlock()
 
@@ -153,12 +143,20 @@ func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int) {
 			nodes = append(nodes, unwrapNode(n))
 		}
 	}
-	// Shuffle.
-	for i := 0; i < len(nodes); i++ {
-		j := tab.rand.Intn(len(nodes))
-		nodes[i], nodes[j] = nodes[j], nodes[i]
-	}
-	return copy(buf, nodes)
+	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.
@@ -218,7 +216,7 @@ func (tab *Table) refresh() <-chan struct{} {
 func (tab *Table) loop() {
 	var (
 		revalidate     = time.NewTimer(tab.nextRevalidateTime())
-		refresh        = time.NewTicker(refreshInterval)
+		refresh        = time.NewTimer(tab.nextRefreshTime())
 		copyNodes      = time.NewTicker(copyNodesInterval)
 		refreshDone    = make(chan struct{})           // where doRefresh reports completion
 		revalidateDone chan struct{}                   // where doRevalidate reports completion
@@ -251,6 +249,7 @@ loop:
 				close(ch)
 			}
 			waiting, refreshDone = nil, nil
+			refresh.Reset(tab.nextRefreshTime())
 		case <-revalidate.C:
 			revalidateDone = make(chan struct{})
 			go tab.doRevalidate(revalidateDone)
@@ -373,7 +372,15 @@ func (tab *Table) nextRevalidateTime() time.Duration {
 	tab.mutex.Lock()
 	defer tab.mutex.Unlock()
 
-	return time.Duration(tab.rand.Int63n(int64(revalidateInterval)))
+	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
@@ -481,10 +488,12 @@ func (tab *Table) addSeenNode(n *node) {
 		// 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)
 	}
@@ -523,10 +532,12 @@ func (tab *Table) addVerifiedNode(n *node) {
 		// 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)
 	}

p2p/discover/table_test.go

@@ -247,41 +247,6 @@ func TestTable_findnodeByID(t *testing.T) {
 	}
 }
 
-func TestTable_ReadRandomNodesGetAll(t *testing.T) {
-	cfg := &quick.Config{
-		MaxCount: 200,
-		Rand:     rand.New(rand.NewSource(time.Now().Unix())),
-		Values: func(args []reflect.Value, rand *rand.Rand) {
-			args[0] = reflect.ValueOf(make([]*enode.Node, rand.Intn(1000)))
-		},
-	}
-	test := func(buf []*enode.Node) bool {
-		transport := newPingRecorder()
-		tab, db := newTestTable(transport)
-		defer db.Close()
-		defer tab.close()
-		<-tab.initDone
-
-		for i := 0; i < len(buf); i++ {
-			ld := cfg.Rand.Intn(len(tab.buckets))
-			fillTable(tab, []*node{nodeAtDistance(tab.self().ID(), ld, intIP(ld))})
-		}
-		gotN := tab.ReadRandomNodes(buf)
-		if gotN != tab.len() {
-			t.Errorf("wrong number of nodes, got %d, want %d", gotN, tab.len())
-			return false
-		}
-		if hasDuplicates(wrapNodes(buf[:gotN])) {
-			t.Errorf("result contains duplicates")
-			return false
-		}
-		return true
-	}
-	if err := quick.Check(test, cfg); err != nil {
-		t.Error(err)
-	}
-}
-
 type closeTest struct {
 	Self   enode.ID
 	Target enode.ID

p2p/discover/table_util_test.go

@@ -28,7 +28,6 @@ import (
 	"sync"
 
 	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/p2p/enr"
 )
@@ -42,8 +41,9 @@ func init() {
 }
 
 func newTestTable(t transport) (*Table, *enode.DB) {
+	cfg := Config{}
 	db, _ := enode.OpenDB("")
-	tab, _ := newTable(t, db, nil, log.Root())
+	tab, _ := newTable(t, db, cfg)
 	go tab.loop()
 	return tab, db
 }

p2p/discover/v4_udp.go

@@ -142,7 +142,7 @@ func ListenV4(c UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv4, error) {
 		log:             cfg.Log,
 	}
 
-	tab, err := newTable(t, ln.Database(), cfg.Bootnodes, t.log)
+	tab, err := newTable(t, ln.Database(), cfg)
 	if err != nil {
 		return nil, err
 	}

p2p/discover/v5_udp.go

@@ -174,7 +174,7 @@ func newUDPv5(conn UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv5, error) {
 		cancelCloseCtx: cancelCloseCtx,
 	}
 	t.talk = newTalkSystem(t)
-	tab, err := newTable(t, t.db, cfg.Bootnodes, cfg.Log)
+	tab, err := newTable(t, t.db, cfg)
 	if err != nil {
 		return nil, err
 	}