p2p/discover: new package implementing the Node Discovery Protocol

1 files changed, 403 insertions, 0 deletions

diff --git a/p2p/discover/table_test.go b/p2p/discover/table_test.go
new file mode 100644
index 000000000..88563fe65
--- /dev/null
+++ b/p2p/discover/table_test.go
@@ -0,0 +1,403 @@
+package discover
+
+import (
+	"crypto/ecdsa"
+	"errors"
+	"fmt"
+	"math/big"
+	"math/rand"
+	"net"
+	"reflect"
+	"testing"
+	"testing/quick"
+	"time"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+var (
+	quickrand = rand.New(rand.NewSource(time.Now().Unix()))
+	quickcfg  = &quick.Config{MaxCount: 5000, Rand: quickrand}
+)
+
+func TestHexID(t *testing.T) {
+	ref := NodeID{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128, 106, 217, 182, 31, 165, 174, 1, 67, 7, 235, 220, 150, 66, 83, 173, 205, 159, 44, 10, 57, 42, 161, 26, 188}
+	id1 := HexID("0x000000000000000000000000000000000000000000000000000000000000000000000000000000806ad9b61fa5ae014307ebdc964253adcd9f2c0a392aa11abc")
+	id2 := HexID("000000000000000000000000000000000000000000000000000000000000000000000000000000806ad9b61fa5ae014307ebdc964253adcd9f2c0a392aa11abc")
+
+	if id1 != ref {
+		t.Errorf("wrong id1\ngot  %v\nwant %v", id1[:], ref[:])
+	}
+	if id2 != ref {
+		t.Errorf("wrong id2\ngot  %v\nwant %v", id2[:], ref[:])
+	}
+}
+
+func TestNodeID_recover(t *testing.T) {
+	prv := newkey()
+	hash := make([]byte, 32)
+	sig, err := crypto.Sign(hash, prv)
+	if err != nil {
+		t.Fatalf("signing error: %v", err)
+	}
+
+	pub := newNodeID(prv)
+	recpub, err := recoverNodeID(hash, sig)
+	if err != nil {
+		t.Fatalf("recovery error: %v", err)
+	}
+	if pub != recpub {
+		t.Errorf("recovered wrong pubkey:\ngot:  %v\nwant: %v", recpub, pub)
+	}
+}
+
+func TestNodeID_distcmp(t *testing.T) {
+	distcmpBig := func(target, a, b NodeID) int {
+		tbig := new(big.Int).SetBytes(target[:])
+		abig := new(big.Int).SetBytes(a[:])
+		bbig := new(big.Int).SetBytes(b[:])
+		return new(big.Int).Xor(tbig, abig).Cmp(new(big.Int).Xor(tbig, bbig))
+	}
+	if err := quick.CheckEqual(distcmp, distcmpBig, quickcfg); err != nil {
+		t.Error(err)
+	}
+}
+
+// the random tests is likely to miss the case where they're equal.
+func TestNodeID_distcmpEqual(t *testing.T) {
+	base := NodeID{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+	x := NodeID{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}
+	if distcmp(base, x, x) != 0 {
+		t.Errorf("distcmp(base, x, x) != 0")
+	}
+}
+
+func TestNodeID_logdist(t *testing.T) {
+	logdistBig := func(a, b NodeID) int {
+		abig, bbig := new(big.Int).SetBytes(a[:]), new(big.Int).SetBytes(b[:])
+		return new(big.Int).Xor(abig, bbig).BitLen()
+	}
+	if err := quick.CheckEqual(logdist, logdistBig, quickcfg); err != nil {
+		t.Error(err)
+	}
+}
+
+// the random tests is likely to miss the case where they're equal.
+func TestNodeID_logdistEqual(t *testing.T) {
+	x := NodeID{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+	if logdist(x, x) != 0 {
+		t.Errorf("logdist(x, x) != 0")
+	}
+}
+
+func TestNodeID_randomID(t *testing.T) {
+	// we don't use quick.Check here because its output isn't
+	// very helpful when the test fails.
+	for i := 0; i < quickcfg.MaxCount; i++ {
+		a := gen(NodeID{}, quickrand).(NodeID)
+		dist := quickrand.Intn(len(NodeID{}) * 8)
+		result := randomID(a, dist)
+		actualdist := logdist(result, a)
+
+		if dist != actualdist {
+			t.Log("a:     ", a)
+			t.Log("result:", result)
+			t.Fatalf("#%d: distance of result is %d, want %d", i, actualdist, dist)
+		}
+	}
+}
+
+func (NodeID) Generate(rand *rand.Rand, size int) reflect.Value {
+	var id NodeID
+	m := rand.Intn(len(id))
+	for i := len(id) - 1; i > m; i-- {
+		id[i] = byte(rand.Uint32())
+	}
+	return reflect.ValueOf(id)
+}
+
+func TestTable_bumpOrAddPingReplace(t *testing.T) {
+	pingC := make(pingC)
+	tab := newTable(pingC, NodeID{}, &net.UDPAddr{})
+	last := fillBucket(tab, 200)
+
+	// this bumpOrAdd should not replace the last node
+	// because the node replies to ping.
+	new := tab.bumpOrAdd(randomID(tab.self.ID, 200), nil)
+
+	pinged := <-pingC
+	if pinged != last.ID {
+		t.Fatalf("pinged wrong node: %v\nwant %v", pinged, last.ID)
+	}
+
+	tab.mutex.Lock()
+	defer tab.mutex.Unlock()
+	if l := len(tab.buckets[200].entries); l != bucketSize {
+		t.Errorf("wrong bucket size after bumpOrAdd: got %d, want %d", bucketSize, l)
+	}
+	if !contains(tab.buckets[200].entries, last.ID) {
+		t.Error("last entry was removed")
+	}
+	if contains(tab.buckets[200].entries, new.ID) {
+		t.Error("new entry was added")
+	}
+}
+
+func TestTable_bumpOrAddPingTimeout(t *testing.T) {
+	tab := newTable(pingC(nil), NodeID{}, &net.UDPAddr{})
+	last := fillBucket(tab, 200)
+
+	// this bumpOrAdd should replace the last node
+	// because the node does not reply to ping.
+	new := tab.bumpOrAdd(randomID(tab.self.ID, 200), nil)
+
+	// wait for async bucket update. damn. this needs to go away.
+	time.Sleep(2 * time.Millisecond)
+
+	tab.mutex.Lock()
+	defer tab.mutex.Unlock()
+	if l := len(tab.buckets[200].entries); l != bucketSize {
+		t.Errorf("wrong bucket size after bumpOrAdd: got %d, want %d", bucketSize, l)
+	}
+	if contains(tab.buckets[200].entries, last.ID) {
+		t.Error("last entry was not removed")
+	}
+	if !contains(tab.buckets[200].entries, new.ID) {
+		t.Error("new entry was not added")
+	}
+}
+
+func fillBucket(tab *Table, ld int) (last *Node) {
+	b := tab.buckets[ld]
+	for len(b.entries) < bucketSize {
+		b.entries = append(b.entries, &Node{ID: randomID(tab.self.ID, ld)})
+	}
+	return b.entries[bucketSize-1]
+}
+
+type pingC chan NodeID
+
+func (t pingC) findnode(n *Node, target NodeID) ([]*Node, error) {
+	panic("findnode called on pingRecorder")
+}
+func (t pingC) close() {
+	panic("close called on pingRecorder")
+}
+func (t pingC) ping(n *Node) error {
+	if t == nil {
+		return errTimeout
+	}
+	t <- n.ID
+	return nil
+}
+
+func TestTable_bump(t *testing.T) {
+	tab := newTable(nil, NodeID{}, &net.UDPAddr{})
+
+	// add an old entry and two recent ones
+	oldactive := time.Now().Add(-2 * time.Minute)
+	old := &Node{ID: randomID(tab.self.ID, 200), active: oldactive}
+	others := []*Node{
+		&Node{ID: randomID(tab.self.ID, 200), active: time.Now()},
+		&Node{ID: randomID(tab.self.ID, 200), active: time.Now()},
+	}
+	tab.add(append(others, old))
+	if tab.buckets[200].entries[0] == old {
+		t.Fatal("old entry is at front of bucket")
+	}
+
+	// bumping the old entry should move it to the front
+	tab.bump(old.ID)
+	if old.active == oldactive {
+		t.Error("activity timestamp not updated")
+	}
+	if tab.buckets[200].entries[0] != old {
+		t.Errorf("bumped entry did not move to the front of bucket")
+	}
+}
+
+func TestTable_closest(t *testing.T) {
+	t.Parallel()
+
+	test := func(test *closeTest) bool {
+		// for any node table, Target and N
+		tab := newTable(nil, test.Self, &net.UDPAddr{})
+		tab.add(test.All)
+
+		// check that doClosest(Target, N) returns nodes
+		result := tab.closest(test.Target, test.N).entries
+		if hasDuplicates(result) {
+			t.Errorf("result contains duplicates")
+			return false
+		}
+		if !sortedByDistanceTo(test.Target, result) {
+			t.Errorf("result is not sorted by distance to target")
+			return false
+		}
+
+		// check that the number of results is min(N, tablen)
+		wantN := test.N
+		if tlen := tab.len(); tlen < test.N {
+			wantN = tlen
+		}
+		if len(result) != wantN {
+			t.Errorf("wrong number of nodes: got %d, want %d", len(result), wantN)
+			return false
+		} else if len(result) == 0 {
+			return true // no need to check distance
+		}
+
+		// check that the result nodes have minimum distance to target.
+		for _, b := range tab.buckets {
+			for _, n := range b.entries {
+				if contains(result, n.ID) {
+					continue // don't run the check below for nodes in result
+				}
+				farthestResult := result[len(result)-1].ID
+				if distcmp(test.Target, n.ID, farthestResult) < 0 {
+					t.Errorf("table contains node that is closer to target but it's not in result")
+					t.Logf("  Target:          %v", test.Target)
+					t.Logf("  Farthest Result: %v", farthestResult)
+					t.Logf("  ID:              %v", n.ID)
+					return false
+				}
+			}
+		}
+		return true
+	}
+	if err := quick.Check(test, quickcfg); err != nil {
+		t.Error(err)
+	}
+}
+
+type closeTest struct {
+	Self   NodeID
+	Target NodeID
+	All    []*Node
+	N      int
+}
+
+func (*closeTest) Generate(rand *rand.Rand, size int) reflect.Value {
+	t := &closeTest{
+		Self:   gen(NodeID{}, rand).(NodeID),
+		Target: gen(NodeID{}, rand).(NodeID),
+		N:      rand.Intn(bucketSize),
+	}
+	for _, id := range gen([]NodeID{}, rand).([]NodeID) {
+		t.All = append(t.All, &Node{ID: id})
+	}
+	return reflect.ValueOf(t)
+}
+
+func TestTable_Lookup(t *testing.T) {
+	self := gen(NodeID{}, quickrand).(NodeID)
+	target := randomID(self, 200)
+	transport := findnodeOracle{t, target}
+	tab := newTable(transport, self, &net.UDPAddr{})
+
+	// lookup on empty table returns no nodes
+	if results := tab.Lookup(target); len(results) > 0 {
+		t.Fatalf("lookup on empty table returned %d results: %#v", len(results), results)
+	}
+	// seed table with initial node (otherwise lookup will terminate immediately)
+	tab.bumpOrAdd(randomID(target, 200), &net.UDPAddr{Port: 200})
+
+	results := tab.Lookup(target)
+	t.Logf("results:")
+	for _, e := range results {
+		t.Logf("  ld=%d, %v", logdist(target, e.ID), e.ID)
+	}
+	if len(results) != bucketSize {
+		t.Errorf("wrong number of results: got %d, want %d", len(results), bucketSize)
+	}
+	if hasDuplicates(results) {
+		t.Errorf("result set contains duplicate entries")
+	}
+	if !sortedByDistanceTo(target, results) {
+		t.Errorf("result set not sorted by distance to target")
+	}
+	if !contains(results, target) {
+		t.Errorf("result set does not contain target")
+	}
+}
+
+// findnode on this transport always returns at least one node
+// that is one bucket closer to the target.
+type findnodeOracle struct {
+	t      *testing.T
+	target NodeID
+}
+
+func (t findnodeOracle) findnode(n *Node, target NodeID) ([]*Node, error) {
+	t.t.Logf("findnode query at dist %d", n.Addr.Port)
+	// current log distance is encoded in port number
+	var result []*Node
+	switch port := n.Addr.Port; port {
+	case 0:
+		panic("query to node at distance 0")
+	case 1:
+		result = append(result, &Node{ID: t.target, Addr: &net.UDPAddr{Port: 0}})
+	default:
+		// TODO: add more randomness to distances
+		port--
+		for i := 0; i < bucketSize; i++ {
+			result = append(result, &Node{ID: randomID(t.target, port), Addr: &net.UDPAddr{Port: port}})
+		}
+	}
+	return result, nil
+}
+
+func (t findnodeOracle) close() {}
+
+func (t findnodeOracle) ping(n *Node) error {
+	return errors.New("ping is not supported by this transport")
+}
+
+func hasDuplicates(slice []*Node) bool {
+	seen := make(map[NodeID]bool)
+	for _, e := range slice {
+		if seen[e.ID] {
+			return true
+		}
+		seen[e.ID] = true
+	}
+	return false
+}
+
+func sortedByDistanceTo(distbase NodeID, slice []*Node) bool {
+	var last NodeID
+	for i, e := range slice {
+		if i > 0 && distcmp(distbase, e.ID, last) < 0 {
+			return false
+		}
+		last = e.ID
+	}
+	return true
+}
+
+func contains(ns []*Node, id NodeID) bool {
+	for _, n := range ns {
+		if n.ID == id {
+			return true
+		}
+	}
+	return false
+}
+
+// gen wraps quick.Value so it's easier to use.
+// it generates a random value of the given value's type.
+func gen(typ interface{}, rand *rand.Rand) interface{} {
+	v, ok := quick.Value(reflect.TypeOf(typ), rand)
+	if !ok {
+		panic(fmt.Sprintf("couldn't generate random value of type %T", typ))
+	}
+	return v.Interface()
+}
+
+func newkey() *ecdsa.PrivateKey {
+	key, err := crypto.GenerateKey()
+	if err != nil {
+		panic("couldn't generate key: " + err.Error())
+	}
+	return key
+}