added routing table saving, bitmap operations, lots of tests

dht/bitmap.go

@@ -1,8 +1,10 @@
 package dht
 
 import (
+	"bytes"
 	"crypto/rand"
 	"encoding/hex"
+	"strings"
 
 	"github.com/lbryio/errors.go"
 	"github.com/lyoshenka/bencode"
@@ -14,6 +16,19 @@ func (b Bitmap) RawString() string {
 	return string(b[:])
 }
 
+// BString returns the bitmap as a string of 0s and 1s
+func (b Bitmap) BString() string {
+	var buf bytes.Buffer
+	for i := 0; i < nodeIDBits; i++ {
+		if b.Get(i) {
+			buf.WriteString("1")
+		} else {
+			buf.WriteString("0")
+		}
+	}
+	return buf.String()
+}
+
 func (b Bitmap) Hex() string {
 	return hex.EncodeToString(b[:])
 }
@@ -22,6 +37,14 @@ func (b Bitmap) HexShort() string {
 	return hex.EncodeToString(b[:4])
 }
 
+func (b Bitmap) HexSimplified() string {
+	simple := strings.TrimLeft(b.Hex(), "0")
+	if simple == "" {
+		simple = "0"
+	}
+	return simple
+}
+
 func (b Bitmap) Equals(other Bitmap) bool {
 	for k := range b {
 		if b[k] != other[k] {
@@ -40,6 +63,35 @@ func (b Bitmap) Less(other interface{}) bool {
 	return false
 }
 
+func (b Bitmap) LessOrEqual(other interface{}) bool {
+	if bm, ok := other.(Bitmap); ok && b.Equals(bm) {
+		return true
+	}
+	return b.Less(other)
+}
+
+func (b Bitmap) Greater(other interface{}) bool {
+	for k := range b {
+		if b[k] != other.(Bitmap)[k] {
+			return b[k] > other.(Bitmap)[k]
+		}
+	}
+	return false
+}
+
+func (b Bitmap) GreaterOrEqual(other interface{}) bool {
+	if bm, ok := other.(Bitmap); ok && b.Equals(bm) {
+		return true
+	}
+	return b.Greater(other)
+}
+
+func (b Bitmap) Copy() Bitmap {
+	var ret Bitmap
+	copy(ret[:], b[:])
+	return ret
+}
+
 func (b Bitmap) Xor(other Bitmap) Bitmap {
 	var ret Bitmap
 	for k := range b {
@@ -48,6 +100,69 @@ func (b Bitmap) Xor(other Bitmap) Bitmap {
 	return ret
 }
 
+func (b Bitmap) And(other Bitmap) Bitmap {
+	var ret Bitmap
+	for k := range b {
+		ret[k] = b[k] & other[k]
+	}
+	return ret
+}
+
+func (b Bitmap) Or(other Bitmap) Bitmap {
+	var ret Bitmap
+	for k := range b {
+		ret[k] = b[k] | other[k]
+	}
+	return ret
+}
+
+func (b Bitmap) Not() Bitmap {
+	var ret Bitmap
+	for k := range b {
+		ret[k] = ^b[k]
+	}
+	return ret
+}
+
+func (b Bitmap) add(other Bitmap) (Bitmap, bool) {
+	var ret Bitmap
+	carry := false
+	for i := nodeIDBits - 1; i >= 0; i-- {
+		bBit := getBit(b[:], i)
+		oBit := getBit(other[:], i)
+		setBit(ret[:], i, bBit != oBit != carry)
+		carry = (bBit && oBit) || (bBit && carry) || (oBit && carry)
+	}
+	return ret, carry
+}
+
+func (b Bitmap) Add(other Bitmap) Bitmap {
+	ret, carry := b.add(other)
+	if carry {
+		panic("overflow in bitmap addition")
+	}
+	return ret
+}
+
+func (b Bitmap) Sub(other Bitmap) Bitmap {
+	if b.Less(other) {
+		panic("negative bitmaps not supported")
+	}
+	complement, _ := other.Not().add(BitmapFromShortHexP("1"))
+	ret, _ := b.add(complement)
+	return ret
+}
+
+func (b Bitmap) Get(n int) bool {
+	return getBit(b[:], n)
+}
+
+func (b Bitmap) Set(n int, one bool) Bitmap {
+	ret := b.Copy()
+	setBit(ret[:], n, one)
+	return ret
+}
+
 // PrefixLen returns the number of leading 0 bits
 func (b Bitmap) PrefixLen() int {
 	for i := range b {
@@ -57,20 +172,46 @@ func (b Bitmap) PrefixLen() int {
 			}
 		}
 	}
-	return numBuckets
+	return nodeIDBits
 }
 
-// ZeroPrefix returns a copy of b with the first n bits set to 0
+// Prefix returns a copy of b with the first n bits set to 1 (if `one` is true) or 0 (if `one` is false)
 // https://stackoverflow.com/a/23192263/182709
-func (b Bitmap) ZeroPrefix(n int) Bitmap {
+func (b Bitmap) Prefix(n int, one bool) Bitmap {
-	var ret Bitmap
+	ret := b.Copy()
-	copy(ret[:], b[:])
 
 Outer:
 	for i := range ret {
 		for j := 0; j < 8; j++ {
 			if i*8+j < n {
-				ret[i] &= ^(1 << uint(7-j))
+				if one {
+					ret[i] |= 1 << uint(7-j)
+				} else {
+					ret[i] &= ^(1 << uint(7-j))
+				}
+			} else {
+				break Outer
+			}
+		}
+	}
+
+	return ret
+}
+
+// Syffix returns a copy of b with the last n bits set to 1 (if `one` is true) or 0 (if `one` is false)
+// https://stackoverflow.com/a/23192263/182709
+func (b Bitmap) Suffix(n int, one bool) Bitmap {
+	ret := b.Copy()
+
+Outer:
+	for i := len(ret) - 1; i >= 0; i-- {
+		for j := 7; j >= 0; j-- {
+			if i*8+j >= nodeIDBits-n {
+				if one {
+					ret[i] |= 1 << uint(7-j)
+				} else {
+					ret[i] &= ^(1 << uint(7-j))
+				}
 			} else {
 				break Outer
 			}
@@ -145,6 +286,18 @@ func BitmapFromHexP(hexStr string) Bitmap {
 	return bmp
 }
 
+func BitmapFromShortHex(hexStr string) (Bitmap, error) {
+	return BitmapFromHex(strings.Repeat("0", nodeIDLength*2-len(hexStr)) + hexStr)
+}
+
+func BitmapFromShortHexP(hexStr string) Bitmap {
+	bmp, err := BitmapFromShortHex(hexStr)
+	if err != nil {
+		panic(err)
+	}
+	return bmp
+}
+
 func RandomBitmapP() Bitmap {
 	var id Bitmap
 	_, err := rand.Read(id[:])
@@ -153,3 +306,28 @@ func RandomBitmapP() Bitmap {
 	}
 	return id
 }
+
+func RandomBitmapInRangeP(low, high Bitmap) Bitmap {
+	diff := high.Sub(low)
+	r := RandomBitmapP()
+	for r.Greater(diff) {
+		r = r.Sub(diff)
+	}
+	return r.Add(low)
+}
+
+func getBit(b []byte, n int) bool {
+	i := n / 8
+	j := n % 8
+	return b[i]&(1<<uint(7-j)) > 0
+}
+
+func setBit(b []byte, n int, one bool) {
+	i := n / 8
+	j := n % 8
+	if one {
+		b[i] |= 1 << uint(7-j)
+	} else {
+		b[i] &= ^(1 << uint(7-j))
+	}
+}

dht/bitmap_test.go

@@ -1,6 +1,7 @@
 package dht
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/lyoshenka/bencode"
@@ -51,6 +52,84 @@ func TestBitmap(t *testing.T) {
 	}
 }
 
+func TestBitmap_GetBit(t *testing.T) {
+	tt := []struct {
+		hex      string
+		bit      int
+		expected bool
+		panic    bool
+	}{
+		//{hex: "0", bit: 385, one: true, expected: "1", panic:true}, // should error
+		//{hex: "0", bit: 384, one: true, expected: "1", panic:true},
+		{bit: 383, expected: false, panic: false},
+		{bit: 382, expected: true, panic: false},
+		{bit: 381, expected: false, panic: false},
+		{bit: 380, expected: true, panic: false},
+	}
+
+	b := BitmapFromShortHexP("a")
+
+	for _, test := range tt {
+		actual := getBit(b[:], test.bit)
+		if test.expected != actual {
+			t.Errorf("getting bit %d of %s: expected %t, got %t", test.bit, b.HexSimplified(), test.expected, actual)
+		}
+	}
+}
+
+func TestBitmap_SetBit(t *testing.T) {
+	tt := []struct {
+		hex      string
+		bit      int
+		one      bool
+		expected string
+		panic    bool
+	}{
+		{hex: "0", bit: 383, one: true, expected: "1", panic: false},
+		{hex: "0", bit: 382, one: true, expected: "2", panic: false},
+		{hex: "0", bit: 381, one: true, expected: "4", panic: false},
+		{hex: "0", bit: 385, one: true, expected: "1", panic: true},
+		{hex: "0", bit: 384, one: true, expected: "1", panic: true},
+	}
+
+	for _, test := range tt {
+		expected := BitmapFromShortHexP(test.expected)
+		actual := BitmapFromShortHexP(test.hex)
+		if test.panic {
+			assertPanic(t, fmt.Sprintf("setting bit %d to %t", test.bit, test.one), func() { setBit(actual[:], test.bit, test.one) })
+		} else {
+			setBit(actual[:], test.bit, test.one)
+			if !expected.Equals(actual) {
+				t.Errorf("setting bit %d to %t: expected %s, got %s", test.bit, test.one, test.expected, actual.HexSimplified())
+			}
+
+		}
+	}
+}
+
+func TestBitmap_FromHexShort(t *testing.T) {
+	tt := []struct {
+		short string
+		long  string
+	}{
+		{short: "", long: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{short: "0", long: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{short: "00000", long: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{short: "9473745bc", long: "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000009473745bc"},
+		{short: "09473745bc", long: "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000009473745bc"},
+		{short: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+			long: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"},
+	}
+
+	for _, test := range tt {
+		short := BitmapFromShortHexP(test.short)
+		long := BitmapFromHexP(test.long)
+		if !short.Equals(long) {
+			t.Errorf("short hex %s: expected %s, got %s", test.short, long.Hex(), short.Hex())
+		}
+	}
+}
+
 func TestBitmapMarshal(t *testing.T) {
 	b := BitmapFromStringP("123456789012345678901234567890123456789012345678")
 	encoded, err := bencode.EncodeBytes(b)
@@ -120,10 +199,10 @@ func TestBitmap_PrefixLen(t *testing.T) {
 	}
 }
 
-func TestBitmap_ZeroPrefix(t *testing.T) {
+func TestBitmap_Prefix(t *testing.T) {
-	original := BitmapFromHexP("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
+	allOne := BitmapFromHexP("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
 
-	tt := []struct {
+	zerosTT := []struct {
 		zeros    int
 		expected string
 	}{
@@ -136,18 +215,162 @@ func TestBitmap_ZeroPrefix(t *testing.T) {
 		{zeros: 400, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
 	}
 
-	for _, test := range tt {
+	for _, test := range zerosTT {
 		expected := BitmapFromHexP(test.expected)
-		actual := original.ZeroPrefix(test.zeros)
+		actual := allOne.Prefix(test.zeros, false)
 		if !actual.Equals(expected) {
 			t.Errorf("%d zeros: got %s; expected %s", test.zeros, actual.Hex(), expected.Hex())
 		}
 	}
 
 	for i := 0; i < nodeIDLength*8; i++ {
-		b := original.ZeroPrefix(i)
+		b := allOne.Prefix(i, false)
 		if b.PrefixLen() != i {
 			t.Errorf("got prefix len %d; expected %d for %s", b.PrefixLen(), i, b.Hex())
 		}
 	}
+
+	allZero := BitmapFromHexP("000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
+
+	onesTT := []struct {
+		ones     int
+		expected string
+	}{
+		{ones: -123, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 0, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 1, expected: "800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 69, expected: "fffffffffffffffff8000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 383, expected: "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe"},
+		{ones: 384, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+		{ones: 400, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+	}
+
+	for _, test := range onesTT {
+		expected := BitmapFromHexP(test.expected)
+		actual := allZero.Prefix(test.ones, true)
+		if !actual.Equals(expected) {
+			t.Errorf("%d ones: got %s; expected %s", test.ones, actual.Hex(), expected.Hex())
+		}
+	}
+}
+
+func TestBitmap_Suffix(t *testing.T) {
+	allOne := BitmapFromHexP("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
+
+	zerosTT := []struct {
+		zeros    int
+		expected string
+	}{
+		{zeros: -123, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+		{zeros: 0, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+		{zeros: 1, expected: "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe"},
+		{zeros: 69, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe00000000000000000"},
+		{zeros: 383, expected: "800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{zeros: 384, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{zeros: 400, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+	}
+
+	for _, test := range zerosTT {
+		expected := BitmapFromHexP(test.expected)
+		actual := allOne.Suffix(test.zeros, false)
+		if !actual.Equals(expected) {
+			t.Errorf("%d zeros: got %s; expected %s", test.zeros, actual.Hex(), expected.Hex())
+		}
+	}
+
+	for i := 0; i < nodeIDLength*8; i++ {
+		b := allOne.Prefix(i, false)
+		if b.PrefixLen() != i {
+			t.Errorf("got prefix len %d; expected %d for %s", b.PrefixLen(), i, b.Hex())
+		}
+	}
+
+	allZero := BitmapFromHexP("000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
+
+	onesTT := []struct {
+		ones     int
+		expected string
+	}{
+		{ones: -123, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 0, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{ones: 1, expected: "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001"},
+		{ones: 69, expected: "0000000000000000000000000000000000000000000000000000000000000000000000000000001fffffffffffffffff"},
+		{ones: 383, expected: "7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+		{ones: 384, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+		{ones: 400, expected: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"},
+	}
+
+	for _, test := range onesTT {
+		expected := BitmapFromHexP(test.expected)
+		actual := allZero.Suffix(test.ones, true)
+		if !actual.Equals(expected) {
+			t.Errorf("%d ones: got %s; expected %s", test.ones, actual.Hex(), expected.Hex())
+		}
+	}
+}
+
+func TestBitmap_Add(t *testing.T) {
+	tt := []struct {
+		a, b, sum string
+		panic     bool
+	}{
+		{"0", "0", "0", false},
+		{"0", "1", "1", false},
+		{"1", "0", "1", false},
+		{"1", "1", "2", false},
+		{"8", "4", "c", false},
+		{"1000", "0010", "1010", false},
+		{"1111", "1111", "2222", false},
+		{"ffff", "1", "10000", false},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "0", "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", false},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "1", "", true},
+	}
+
+	for _, test := range tt {
+		a := BitmapFromShortHexP(test.a)
+		b := BitmapFromShortHexP(test.b)
+		expected := BitmapFromShortHexP(test.sum)
+		if test.panic {
+			assertPanic(t, fmt.Sprintf("adding %s and %s", test.a, test.b), func() { a.Add(b) })
+		} else {
+			actual := a.Add(b)
+			if !expected.Equals(actual) {
+				t.Errorf("adding %s and %s; expected %s, got %s", test.a, test.b, test.sum, actual.HexSimplified())
+			}
+		}
+	}
+}
+
+func TestBitmap_Sub(t *testing.T) {
+	tt := []struct {
+		a, b, sum string
+		panic     bool
+	}{
+		{"0", "0", "0", false},
+		{"1", "0", "1", false},
+		{"1", "1", "0", false},
+		{"8", "4", "4", false},
+		{"f", "9", "6", false},
+		{"f", "e", "1", false},
+		{"10", "f", "1", false},
+		{"2222", "1111", "1111", false},
+		{"ffff", "1", "fffe", false},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "0", "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", false},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "0", false},
+		{"0", "1", "", true},
+	}
+
+	for _, test := range tt {
+		a := BitmapFromShortHexP(test.a)
+		b := BitmapFromShortHexP(test.b)
+		expected := BitmapFromShortHexP(test.sum)
+		if test.panic {
+			assertPanic(t, fmt.Sprintf("subtracting %s - %s", test.a, test.b), func() { a.Sub(b) })
+		} else {
+			actual := a.Sub(b)
+			if !expected.Equals(actual) {
+				t.Errorf("subtracting %s - %s; expected %s, got %s", test.a, test.b, test.sum, actual.HexSimplified())
+			}
+		}
+	}
 }

dht/bootstrap.go

@@ -1,7 +1,6 @@
 package dht
 
 import (
-	"context"
 	"math/rand"
 	"net"
 	"sync"
@@ -14,25 +13,6 @@ const (
 	bootstrapDefaultRefreshDuration = 15 * time.Minute
 )
 
-type nullStore struct{}
-
-func (n nullStore) Upsert(id Bitmap, c Contact) {}
-func (n nullStore) Get(id Bitmap) []Contact     { return nil }
-func (n nullStore) CountStoredHashes() int      { return 0 }
-
-type nullRoutingTable struct{}
-
-// TODO: the bootstrap logic *could* be implemented just in the routing table, without a custom request handler
-// TODO: the only tricky part is triggering the ping when Fresh is called, as the rt doesnt have access to the node
-
-func (n nullRoutingTable) Update(c Contact)                          {}             // this
-func (n nullRoutingTable) Fresh(c Contact)                           {}             // this
-func (n nullRoutingTable) Fail(c Contact)                            {}             // this
-func (n nullRoutingTable) GetClosest(id Bitmap, limit int) []Contact { return nil } // this
-func (n nullRoutingTable) Count() int                                { return 0 }
-func (n nullRoutingTable) GetIDsForRefresh(d time.Duration) []Bitmap { return nil }
-func (n nullRoutingTable) BucketInfo() string                        { return "" }
-
 type BootstrapNode struct {
 	Node
 
@@ -57,8 +37,6 @@ func NewBootstrapNode(id Bitmap, initialPingInterval, rePingInterval time.Durati
 		nodeKeys: make(map[Bitmap]int),
 	}
 
-	b.rt = &nullRoutingTable{}
-	b.store = &nullStore{}
 	b.requestHandler = b.handleRequest
 
 	return b
@@ -98,14 +76,14 @@ func (b *BootstrapNode) upsert(c Contact) {
 	b.nlock.Lock()
 	defer b.nlock.Unlock()
 
-	if i, exists := b.nodeKeys[c.id]; exists {
+	if i, exists := b.nodeKeys[c.ID]; exists {
-		log.Debugf("[%s] bootstrap: touching contact %s", b.id.HexShort(), b.nodes[i].contact.id.HexShort())
+		log.Debugf("[%s] bootstrap: touching contact %s", b.id.HexShort(), b.nodes[i].Contact.ID.HexShort())
 		b.nodes[i].Touch()
 		return
 	}
 
-	log.Debugf("[%s] bootstrap: adding new contact %s", b.id.HexShort(), c.id.HexShort())
+	log.Debugf("[%s] bootstrap: adding new contact %s", b.id.HexShort(), c.ID.HexShort())
-	b.nodeKeys[c.id] = len(b.nodes)
+	b.nodeKeys[c.ID] = len(b.nodes)
 	b.nodes = append(b.nodes, peer{c, time.Now(), 0})
 }
 
@@ -114,14 +92,14 @@ func (b *BootstrapNode) remove(c Contact) {
 	b.nlock.Lock()
 	defer b.nlock.Unlock()
 
-	i, exists := b.nodeKeys[c.id]
+	i, exists := b.nodeKeys[c.ID]
 	if !exists {
 		return
 	}
 
-	log.Debugf("[%s] bootstrap: removing contact %s", b.id.HexShort(), c.id.HexShort())
+	log.Debugf("[%s] bootstrap: removing contact %s", b.id.HexShort(), c.ID.HexShort())
 	b.nodes = append(b.nodes[:i], b.nodes[i+1:]...)
-	delete(b.nodeKeys, c.id)
+	delete(b.nodeKeys, c.ID)
 }
 
 // get returns up to `limit` random contacts from the list
@@ -135,7 +113,7 @@ func (b *BootstrapNode) get(limit int) []Contact {
 
 	ret := make([]Contact, limit)
 	for i, k := range randKeys(len(b.nodes))[:limit] {
-		ret[i] = b.nodes[k].contact
+		ret[i] = b.nodes[k].Contact
 	}
 
 	return ret
@@ -146,8 +124,7 @@ func (b *BootstrapNode) ping(c Contact) {
 	b.stopWG.Add(1)
 	defer b.stopWG.Done()
 
-	ctx, cancel := context.WithCancel(context.Background())
+	resCh, cancel := b.SendCancelable(c, Request{Method: pingMethod})
-	resCh := b.SendAsync(ctx, c, Request{Method: pingMethod})
 
 	var res *Response
 
@@ -171,7 +148,7 @@ func (b *BootstrapNode) check() {
 
 	for i := range b.nodes {
 		if !b.nodes[i].ActiveInLast(b.checkInterval) {
-			go b.ping(b.nodes[i].contact)
+			go b.ping(b.nodes[i].Contact)
 		}
 	}
 }
@@ -196,7 +173,7 @@ func (b *BootstrapNode) handleRequest(addr *net.UDPAddr, request Request) {
 	go func() {
 		log.Debugf("[%s] bootstrap: queuing %s to ping", b.id.HexShort(), request.NodeID.HexShort())
 		<-time.After(b.initialPingInterval)
-		b.ping(Contact{id: request.NodeID, ip: addr.IP, port: addr.Port})
+		b.ping(Contact{ID: request.NodeID, IP: addr.IP, Port: addr.Port})
 	}()
 }
 

dht/dht.go

@@ -1,7 +1,6 @@
 package dht
 
 import (
-	"context"
 	"fmt"
 	"net"
 	"strings"
@@ -25,10 +24,11 @@ const (
 
 	// TODO: all these constants should be defaults, and should be used to set values in the standard Config. then the code should use values in the config
 	// TODO: alternatively, have a global Config for constants. at least that way tests can modify the values
-	alpha           = 3  // this is the constant alpha in the spec
+	alpha           = 3                // this is the constant alpha in the spec
-	bucketSize      = 8  // this is the constant k in the spec
+	bucketSize      = 8                // this is the constant k in the spec
-	nodeIDLength    = 48 // bytes. this is the constant B in the spec
+	nodeIDLength    = 48               // bytes. this is the constant B in the spec
-	messageIDLength = 20 // bytes.
+	nodeIDBits      = nodeIDLength * 8 // number of bits in node ID
+	messageIDLength = 20               // bytes.
 
 	udpRetry            = 3
 	udpTimeout          = 5 * time.Second
@@ -42,7 +42,6 @@ const (
 	tRepublish   = 24 * time.Hour   // the time after which the original publisher must republish a key/value pair
 	tNodeRefresh = 15 * time.Minute // the time after which a good node becomes questionable if it has not messaged us
 
-	numBuckets            = nodeIDLength * 8
 	compactNodeInfoLength = nodeIDLength + 6 // nodeID + 4 for IP + 2 for port
 
 	tokenSecretRotationInterval = 5 * time.Minute // how often the token-generating secret is rotated
@@ -102,7 +101,7 @@ func New(config *Config) (*DHT, error) {
 	d := &DHT{
 		conf:    config,
 		contact: contact,
-		node:    NewNode(contact.id),
+		node:    NewNode(contact.ID),
 		stop:    stopOnce.New(),
 		stopWG:  &sync.WaitGroup{},
 		joined:  make(chan struct{}),
@@ -181,7 +180,7 @@ func (dht *DHT) Ping(addr string) error {
 		return err
 	}
 
-	tmpNode := Contact{id: RandomBitmapP(), ip: raddr.IP, port: raddr.Port}
+	tmpNode := Contact{ID: RandomBitmapP(), IP: raddr.IP, Port: raddr.Port}
 	res := dht.node.Send(tmpNode, Request{Method: pingMethod})
 	if res == nil {
 		return errors.Err("no response from node %s", addr)
@@ -214,19 +213,25 @@ func (dht *DHT) Announce(hash Bitmap) error {
 
 	// TODO: if this node is closer than farthest peer, store locally and pop farthest peer
 
-	for _, node := range res.Contacts {
+	wg := &sync.WaitGroup{}
-		go dht.storeOnNode(hash, node)
+	for _, c := range res.Contacts {
+		wg.Add(1)
+		go func(c Contact) {
+			dht.storeOnNode(hash, c)
+			wg.Done()
+		}(c)
 	}
 
+	wg.Wait()
+
 	return nil
 }
 
-func (dht *DHT) storeOnNode(hash Bitmap, node Contact) {
+func (dht *DHT) storeOnNode(hash Bitmap, c Contact) {
 	dht.stopWG.Add(1)
 	defer dht.stopWG.Done()
 
-	ctx, cancel := context.WithCancel(context.Background())
+	resCh, cancel := dht.node.SendCancelable(c, Request{
-	resCh := dht.node.SendAsync(ctx, node, Request{
 		Method: findValueMethod,
 		Arg:    &hash,
 	})
@@ -244,15 +249,14 @@ func (dht *DHT) storeOnNode(hash Bitmap, node Contact) {
 		return // request timed out
 	}
 
-	ctx, cancel = context.WithCancel(context.Background())
+	resCh, cancel = dht.node.SendCancelable(c, Request{
-	resCh = dht.node.SendAsync(ctx, node, Request{
 		Method: storeMethod,
 		StoreArgs: &storeArgs{
 			BlobHash: hash,
 			Value: storeArgsValue{
 				Token:  res.Token,
-				LbryID: dht.contact.id,
+				LbryID: dht.contact.ID,
-				Port:   dht.contact.port,
+				Port:   dht.contact.Port,
 			},
 		},
 	})
@@ -276,18 +280,12 @@ func (dht *DHT) PrintState() {
 	}
 }
 
-func printNodeList(list []Contact) {
-	for i, n := range list {
-		log.Printf("%d) %s", i, n.String())
-	}
-}
-
 func getContact(nodeID, addr string) (Contact, error) {
 	var c Contact
 	if nodeID == "" {
-		c.id = RandomBitmapP()
+		c.ID = RandomBitmapP()
 	} else {
-		c.id = BitmapFromHexP(nodeID)
+		c.ID = BitmapFromHexP(nodeID)
 	}
 
 	ip, port, err := net.SplitHostPort(addr)
@@ -299,12 +297,12 @@ func getContact(nodeID, addr string) (Contact, error) {
 		return c, errors.Err("address does not contain a port")
 	}
 
-	c.ip = net.ParseIP(ip)
+	c.IP = net.ParseIP(ip)
-	if c.ip == nil {
+	if c.IP == nil {
 		return c, errors.Err("invalid ip")
 	}
 
-	c.port, err = cast.ToIntE(port)
+	c.Port, err = cast.ToIntE(port)
 	if err != nil {
 		return c, errors.Err(err)
 	}

dht/dht_test.go

@@ -36,13 +36,13 @@ func TestNodeFinder_FindNodes(t *testing.T) {
 	foundTwo := false
 
 	for _, n := range foundNodes {
-		if n.id.Equals(bs.id) {
+		if n.ID.Equals(bs.id) {
 			foundBootstrap = true
 		}
-		if n.id.Equals(dhts[0].node.id) {
+		if n.ID.Equals(dhts[0].node.id) {
 			foundOne = true
 		}
-		if n.id.Equals(dhts[1].node.id) {
+		if n.ID.Equals(dhts[1].node.id) {
 			foundTwo = true
 		}
 	}
@@ -83,7 +83,7 @@ func TestNodeFinder_FindValue(t *testing.T) {
 	}()
 
 	blobHashToFind := RandomBitmapP()
-	nodeToFind := Contact{id: RandomBitmapP(), ip: net.IPv4(1, 2, 3, 4), port: 5678}
+	nodeToFind := Contact{ID: RandomBitmapP(), IP: net.IPv4(1, 2, 3, 4), Port: 5678}
 	dhts[0].node.store.Upsert(blobHashToFind, nodeToFind)
 
 	nf := newContactFinder(dhts[2].node, blobHashToFind, true)
@@ -101,8 +101,8 @@ func TestNodeFinder_FindValue(t *testing.T) {
 		t.Fatalf("expected one node, found %d", len(foundNodes))
 	}
 
-	if !foundNodes[0].id.Equals(nodeToFind.id) {
+	if !foundNodes[0].ID.Equals(nodeToFind.ID) {
-		t.Fatalf("found node id %s, expected %s", foundNodes[0].id.Hex(), nodeToFind.id.Hex())
+		t.Fatalf("found node id %s, expected %s", foundNodes[0].ID.Hex(), nodeToFind.ID.Hex())
 	}
 }
 
@@ -139,7 +139,7 @@ func TestDHT_LargeDHT(t *testing.T) {
 			c := d2.node.rt.GetClosest(d.node.id, 1)
 			if len(c) > 1 {
 				t.Error("rt returned more than one node when only one requested")
-			} else if len(c) == 1 && c[0].id.Equals(d.node.id) {
+			} else if len(c) == 1 && c[0].ID.Equals(d.node.id) {
 				rtCounts[d.node.id]++
 			}
 		}

dht/message.go

@@ -240,7 +240,7 @@ func (r Response) ArgsDebug() string {
 
 	str += "|"
 	for _, c := range r.Contacts {
-		str += c.Addr().String() + ":" + c.id.HexShort() + ","
+		str += c.Addr().String() + ":" + c.ID.HexShort() + ","
 	}
 	str = strings.TrimRight(str, ",") + "|"
 

dht/message_test.go

@@ -78,8 +78,8 @@ func TestBencodeFindNodesResponse(t *testing.T) {
 		ID:     newMessageID(),
 		NodeID: RandomBitmapP(),
 		Contacts: []Contact{
-			{id: RandomBitmapP(), ip: net.IPv4(1, 2, 3, 4).To4(), port: 5678},
+			{ID: RandomBitmapP(), IP: net.IPv4(1, 2, 3, 4).To4(), Port: 5678},
-			{id: RandomBitmapP(), ip: net.IPv4(4, 3, 2, 1).To4(), port: 8765},
+			{ID: RandomBitmapP(), IP: net.IPv4(4, 3, 2, 1).To4(), Port: 8765},
 		},
 	}
 
@@ -104,7 +104,7 @@ func TestBencodeFindValueResponse(t *testing.T) {
 		FindValueKey: RandomBitmapP().RawString(),
 		Token:        "arst",
 		Contacts: []Contact{
-			{id: RandomBitmapP(), ip: net.IPv4(1, 2, 3, 4).To4(), port: 5678},
+			{ID: RandomBitmapP(), IP: net.IPv4(1, 2, 3, 4).To4(), Port: 5678},
 		},
 	}
 

dht/node.go

@@ -48,9 +48,9 @@ type Node struct {
 	transactions map[messageID]*transaction
 
 	// routing table
-	rt RoutingTable
+	rt *routingTable
 	// data store
-	store Store
+	store *contactStore
 
 	// overrides for request handlers
 	requestHandler RequestHandlerFunc
@@ -238,7 +238,7 @@ func (n *Node) handleRequest(addr *net.UDPAddr, request Request) {
 		// TODO: we should be sending the IP in the request, not just using the sender's IP
 		// TODO: should we be using StoreArgs.NodeID or StoreArgs.Value.LbryID ???
 		if n.tokens.Verify(request.StoreArgs.Value.Token, request.NodeID, addr) {
-			n.store.Upsert(request.StoreArgs.BlobHash, Contact{id: request.StoreArgs.NodeID, ip: addr.IP, port: request.StoreArgs.Value.Port})
+			n.store.Upsert(request.StoreArgs.BlobHash, Contact{ID: request.StoreArgs.NodeID, IP: addr.IP, Port: request.StoreArgs.Value.Port})
 			n.sendMessage(addr, Response{ID: request.ID, NodeID: n.id, Data: storeSuccessResponse})
 		} else {
 			n.sendMessage(addr, Error{ID: request.ID, NodeID: n.id, ExceptionType: "invalid-token"})
@@ -280,7 +280,7 @@ func (n *Node) handleRequest(addr *net.UDPAddr, request Request) {
 	// the routing table must only contain "good" nodes, which are nodes that reply to our requests
 	// if a node is already good (aka in the table), its fine to refresh it
 	// http://www.bittorrent.org/beps/bep_0005.html#routing-table
-	n.rt.Fresh(Contact{id: request.NodeID, ip: addr.IP, port: addr.Port})
+	n.rt.Fresh(Contact{ID: request.NodeID, IP: addr.IP, Port: addr.Port})
 }
 
 // handleResponse handles responses received from udp.
@@ -290,13 +290,13 @@ func (n *Node) handleResponse(addr *net.UDPAddr, response Response) {
 		tx.res <- response
 	}
 
-	n.rt.Update(Contact{id: response.NodeID, ip: addr.IP, port: addr.Port})
+	n.rt.Update(Contact{ID: response.NodeID, IP: addr.IP, Port: addr.Port})
 }
 
 // handleError handles errors received from udp.
 func (n *Node) handleError(addr *net.UDPAddr, e Error) {
 	spew.Dump(e)
-	n.rt.Fresh(Contact{id: e.NodeID, ip: addr.IP, port: addr.Port})
+	n.rt.Fresh(Contact{ID: e.NodeID, IP: addr.IP, Port: addr.Port})
 }
 
 // send sends data to a udp address
@@ -361,7 +361,7 @@ func (n *Node) txFind(id messageID, addr *net.UDPAddr) *transaction {
 // SendAsync sends a transaction and returns a channel that will eventually contain the transaction response
 // The response channel is closed when the transaction is completed or times out.
 func (n *Node) SendAsync(ctx context.Context, contact Contact, req Request) <-chan *Response {
-	if contact.id.Equals(n.id) {
+	if contact.ID.Equals(n.id) {
 		log.Error("sending query to self")
 		return nil
 	}
@@ -413,6 +413,12 @@ func (n *Node) Send(contact Contact, req Request) *Response {
 	return <-n.SendAsync(context.Background(), contact, req)
 }
 
+// SendCancelable sends the transaction asynchronously and allows the transaction to be canceled
+func (n *Node) SendCancelable(contact Contact, req Request) (<-chan *Response, context.CancelFunc) {
+	ctx, cancel := context.WithCancel(context.Background())
+	return n.SendAsync(ctx, contact, req), cancel
+}
+
 // Count returns the number of transactions in the manager
 func (n *Node) CountActiveTransactions() int {
 	n.txLock.Lock()

dht/node_finder.go

@@ -1,7 +1,6 @@
 package dht
 
 import (
-	"context"
 	"sort"
 	"sync"
 	"time"
@@ -113,7 +112,7 @@ func (cf *contactFinder) iterationWorker(num int) {
 		} else {
 			contact := *maybeContact
 
-			if contact.id.Equals(cf.node.id) {
+			if contact.ID.Equals(cf.node.id) {
 				continue // cannot contact self
 			}
 
@@ -124,13 +123,12 @@ func (cf *contactFinder) iterationWorker(num int) {
 				req.Method = findNodeMethod
 			}
 
-			log.Debugf("[%s] worker %d: contacting %s", cf.node.id.HexShort(), num, contact.id.HexShort())
+			log.Debugf("[%s] worker %d: contacting %s", cf.node.id.HexShort(), num, contact.ID.HexShort())
 
 			cf.incrementOutstanding()
 
 			var res *Response
-			ctx, cancel := context.WithCancel(context.Background())
+			resCh, cancel := cf.node.SendCancelable(contact, req)
-			resCh := cf.node.SendAsync(ctx, contact, req)
 			select {
 			case res = <-resCh:
 			case <-cf.done.Chan():
@@ -141,7 +139,7 @@ func (cf *contactFinder) iterationWorker(num int) {
 
 			if res == nil {
 				// nothing to do, response timed out
-				log.Debugf("[%s] worker %d: search canceled or timed out waiting for %s", cf.node.id.HexShort(), num, contact.id.HexShort())
+				log.Debugf("[%s] worker %d: search canceled or timed out waiting for %s", cf.node.id.HexShort(), num, contact.ID.HexShort())
 			} else if cf.findValue && res.FindValueKey != "" {
 				log.Debugf("[%s] worker %d: got value", cf.node.id.HexShort(), num)
 				cf.findValueMutex.Lock()
@@ -171,9 +169,9 @@ func (cf *contactFinder) appendNewToShortlist(contacts []Contact) {
 	defer cf.shortlistMutex.Unlock()
 
 	for _, c := range contacts {
-		if _, ok := cf.shortlistAdded[c.id]; !ok {
+		if _, ok := cf.shortlistAdded[c.ID]; !ok {
 			cf.shortlist = append(cf.shortlist, c)
-			cf.shortlistAdded[c.id] = true
+			cf.shortlistAdded[c.ID] = true
 		}
 	}
 
@@ -199,7 +197,7 @@ func (cf *contactFinder) insertIntoActiveList(contact Contact) {
 
 	inserted := false
 	for i, n := range cf.activeContacts {
-		if contact.id.Xor(cf.target).Less(n.id.Xor(cf.target)) {
+		if contact.ID.Xor(cf.target).Less(n.ID.Xor(cf.target)) {
 			cf.activeContacts = append(cf.activeContacts[:i], append([]Contact{contact}, cf.activeContacts[i:]...)...)
 			inserted = true
 			break
@@ -232,7 +230,7 @@ func (cf *contactFinder) isSearchFinished() bool {
 		cf.activeContactsMutex.Lock()
 		defer cf.activeContactsMutex.Unlock()
 
-		if len(cf.activeContacts) >= bucketSize && cf.activeContacts[bucketSize-1].id.Xor(cf.target).Less(cf.shortlist[0].id.Xor(cf.target)) {
+		if len(cf.activeContacts) >= bucketSize && cf.activeContacts[bucketSize-1].ID.Xor(cf.target).Less(cf.shortlist[0].ID.Xor(cf.target)) {
 			// we have at least K active contacts, and we don't have any closer contacts to ping
 			return true
 		}
@@ -263,7 +261,7 @@ func sortInPlace(contacts []Contact, target Bitmap) {
 	toSort := make([]sortedContact, len(contacts))
 
 	for i, n := range contacts {
-		toSort[i] = sortedContact{n, n.id.Xor(target)}
+		toSort[i] = sortedContact{n, n.ID.Xor(target)}
 	}
 
 	sort.Sort(byXorDistance(toSort))

dht/node_test.go

@@ -198,7 +198,7 @@ func TestStore(t *testing.T) {
 	if len(items) != 1 {
 		t.Error("list created in store, but nothing in list")
 	}
-	if !items[0].id.Equals(testNodeID) {
+	if !items[0].ID.Equals(testNodeID) {
 		t.Error("wrong value stored")
 	}
 }
@@ -223,7 +223,7 @@ func TestFindNode(t *testing.T) {
 	nodesToInsert := 3
 	var nodes []Contact
 	for i := 0; i < nodesToInsert; i++ {
-		n := Contact{id: RandomBitmapP(), ip: net.ParseIP("127.0.0.1"), port: 10000 + i}
+		n := Contact{ID: RandomBitmapP(), IP: net.ParseIP("127.0.0.1"), Port: 10000 + i}
 		nodes = append(nodes, n)
 		dht.node.rt.Update(n)
 	}
@@ -292,7 +292,7 @@ func TestFindValueExisting(t *testing.T) {
 	nodesToInsert := 3
 	var nodes []Contact
 	for i := 0; i < nodesToInsert; i++ {
-		n := Contact{id: RandomBitmapP(), ip: net.ParseIP("127.0.0.1"), port: 10000 + i}
+		n := Contact{ID: RandomBitmapP(), IP: net.ParseIP("127.0.0.1"), Port: 10000 + i}
 		nodes = append(nodes, n)
 		dht.node.rt.Update(n)
 	}
@@ -302,7 +302,7 @@ func TestFindValueExisting(t *testing.T) {
 	messageID := newMessageID()
 	valueToFind := RandomBitmapP()
 
-	nodeToFind := Contact{id: RandomBitmapP(), ip: net.ParseIP("1.2.3.4"), port: 1286}
+	nodeToFind := Contact{ID: RandomBitmapP(), IP: net.ParseIP("1.2.3.4"), Port: 1286}
 	dht.node.store.Upsert(valueToFind, nodeToFind)
 	dht.node.store.Upsert(valueToFind, nodeToFind)
 	dht.node.store.Upsert(valueToFind, nodeToFind)
@@ -378,7 +378,7 @@ func TestFindValueFallbackToFindNode(t *testing.T) {
 	nodesToInsert := 3
 	var nodes []Contact
 	for i := 0; i < nodesToInsert; i++ {
-		n := Contact{id: RandomBitmapP(), ip: net.ParseIP("127.0.0.1"), port: 10000 + i}
+		n := Contact{ID: RandomBitmapP(), IP: net.ParseIP("127.0.0.1"), Port: 10000 + i}
 		nodes = append(nodes, n)
 		dht.node.rt.Update(n)
 	}

dht/routing_table.go

@@ -2,10 +2,11 @@ package dht
 
 import (
 	"bytes"
-	"container/list"
+	"encoding/json"
 	"fmt"
 	"net"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -16,32 +17,32 @@ import (
 )
 
 type Contact struct {
-	id   Bitmap
+	ID   Bitmap
-	ip   net.IP
+	IP   net.IP
-	port int
+	Port int
 }
 
 func (c Contact) Addr() *net.UDPAddr {
-	return &net.UDPAddr{IP: c.ip, Port: c.port}
+	return &net.UDPAddr{IP: c.IP, Port: c.Port}
 }
 
 func (c Contact) String() string {
-	return c.id.HexShort() + "@" + c.Addr().String()
+	return c.ID.HexShort() + "@" + c.Addr().String()
 }
 
 func (c Contact) MarshalCompact() ([]byte, error) {
-	if c.ip.To4() == nil {
+	if c.IP.To4() == nil {
 		return nil, errors.Err("ip not set")
 	}
-	if c.port < 0 || c.port > 65535 {
+	if c.Port < 0 || c.Port > 65535 {
 		return nil, errors.Err("invalid port")
 	}
 
 	var buf bytes.Buffer
-	buf.Write(c.ip.To4())
+	buf.Write(c.IP.To4())
-	buf.WriteByte(byte(c.port >> 8))
+	buf.WriteByte(byte(c.Port >> 8))
-	buf.WriteByte(byte(c.port))
+	buf.WriteByte(byte(c.Port))
-	buf.Write(c.id[:])
+	buf.Write(c.ID[:])
 
 	if buf.Len() != compactNodeInfoLength {
 		return nil, errors.Err("i dont know how this happened")
@@ -54,14 +55,14 @@ func (c *Contact) UnmarshalCompact(b []byte) error {
 	if len(b) != compactNodeInfoLength {
 		return errors.Err("invalid compact length")
 	}
-	c.ip = net.IPv4(b[0], b[1], b[2], b[3]).To4()
+	c.IP = net.IPv4(b[0], b[1], b[2], b[3]).To4()
-	c.port = int(uint16(b[5]) | uint16(b[4])<<8)
+	c.Port = int(uint16(b[5]) | uint16(b[4])<<8)
-	c.id = BitmapFromBytesP(b[6:])
+	c.ID = BitmapFromBytesP(b[6:])
 	return nil
 }
 
 func (c Contact) MarshalBencode() ([]byte, error) {
-	return bencode.EncodeBytes([]interface{}{c.id, c.ip.String(), c.port})
+	return bencode.EncodeBytes([]interface{}{c.ID, c.IP.String(), c.Port})
 }
 
 func (c *Contact) UnmarshalBencode(b []byte) error {
@@ -75,7 +76,7 @@ func (c *Contact) UnmarshalBencode(b []byte) error {
 		return errors.Err("contact must have 3 elements; got %d", len(raw))
 	}
 
-	err = bencode.DecodeBytes(raw[0], &c.id)
+	err = bencode.DecodeBytes(raw[0], &c.ID)
 	if err != nil {
 		return err
 	}
@@ -85,12 +86,12 @@ func (c *Contact) UnmarshalBencode(b []byte) error {
 	if err != nil {
 		return err
 	}
-	c.ip = net.ParseIP(ipStr).To4()
+	c.IP = net.ParseIP(ipStr).To4()
-	if c.ip == nil {
+	if c.IP == nil {
 		return errors.Err("invalid IP")
 	}
 
-	err = bencode.DecodeBytes(raw[2], &c.port)
+	err = bencode.DecodeBytes(raw[2], &c.Port)
 	if err != nil {
 		return err
 	}
@@ -113,52 +114,38 @@ func (a byXorDistance) Less(i, j int) bool {
 
 // peer is a contact with extra freshness information
 type peer struct {
-	contact      Contact
+	Contact      Contact
-	lastActivity time.Time
+	LastActivity time.Time
-	numFailures  int
+	NumFailures  int
 	//<lastPublished>,
 	//<originallyPublished>
 	//	<originalPublisherID>
 }
 
 func (p *peer) Touch() {
-	p.lastActivity = time.Now()
+	p.LastActivity = time.Now()
-	p.numFailures = 0
+	p.NumFailures = 0
 }
 
 // ActiveSince returns whether a peer has responded in the last `d` duration
 // this is used to check if the peer is "good", meaning that we believe the peer will respond to our requests
 func (p *peer) ActiveInLast(d time.Duration) bool {
-	return time.Now().Sub(p.lastActivity) > d
+	return time.Now().Sub(p.LastActivity) > d
 }
 
 // IsBad returns whether a peer is "bad", meaning that it has failed to respond to multiple pings in a row
 func (p *peer) IsBad(maxFalures int) bool {
-	return p.numFailures >= maxFalures
+	return p.NumFailures >= maxFalures
 }
 
 // Fail marks a peer as having failed to respond. It returns whether or not the peer should be removed from the routing table
 func (p *peer) Fail() {
-	p.numFailures++
+	p.NumFailures++
-}
-
-// toPeer converts a generic *list.Element into a *peer
-// this (along with newPeer) keeps all conversions between *list.Element and peer in one place
-func toPeer(el *list.Element) *peer {
-	return el.Value.(*peer)
-}
-
-// newPeer creates a new peer from a contact
-// this (along with toPeer) keeps all conversions between *list.Element and peer in one place
-func newPeer(c Contact) peer {
-	return peer{
-		contact: c,
-	}
 }
 
 type bucket struct {
 	lock       *sync.RWMutex
-	peers      *list.List
+	peers      []peer
 	lastUpdate time.Time
 }
 
@@ -166,16 +153,16 @@ type bucket struct {
 func (b bucket) Len() int {
 	b.lock.RLock()
 	defer b.lock.RUnlock()
-	return b.peers.Len()
+	return len(b.peers)
 }
 
 // Contacts returns a slice of the bucket's contacts
 func (b bucket) Contacts() []Contact {
 	b.lock.RLock()
 	defer b.lock.RUnlock()
-	contacts := make([]Contact, b.peers.Len())
+	contacts := make([]Contact, len(b.peers))
-	for i, curr := 0, b.peers.Front(); curr != nil; i, curr = i+1, curr.Next() {
+	for i := range b.peers {
-		contacts[i] = toPeer(curr).contact
+		contacts[i] = b.peers[i].Contact
 	}
 	return contacts
 }
@@ -185,21 +172,21 @@ func (b *bucket) UpdateContact(c Contact, insertIfNew bool) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 
-	element := find(c.id, b.peers)
+	peerIndex := find(c.ID, b.peers)
-	if element != nil {
+	if peerIndex >= 0 {
 		b.lastUpdate = time.Now()
-		toPeer(element).Touch()
+		b.peers[peerIndex].Touch()
-		b.peers.MoveToBack(element)
+		moveToBack(b.peers, peerIndex)
 
 	} else if insertIfNew {
 		hasRoom := true
 
-		if b.peers.Len() >= bucketSize {
+		if len(b.peers) >= bucketSize {
 			hasRoom = false
-			for curr := b.peers.Front(); curr != nil; curr = curr.Next() {
+			for i := range b.peers {
-				if toPeer(curr).IsBad(maxPeerFails) {
+				if b.peers[i].IsBad(maxPeerFails) {
 					// TODO: Ping contact first. Only remove if it does not respond
-					b.peers.Remove(curr)
+					b.peers = append(b.peers[:i], b.peers[i+1:]...)
 					hasRoom = true
 					break
 				}
@@ -208,9 +195,9 @@ func (b *bucket) UpdateContact(c Contact, insertIfNew bool) {
 
 		if hasRoom {
 			b.lastUpdate = time.Now()
-			peer := newPeer(c)
+			peer := peer{Contact: c}
 			peer.Touch()
-			b.peers.PushBack(&peer)
+			b.peers = append(b.peers, peer)
 		}
 	}
 }
@@ -219,21 +206,21 @@ func (b *bucket) UpdateContact(c Contact, insertIfNew bool) {
 func (b *bucket) FailContact(id Bitmap) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
-	element := find(id, b.peers)
+	i := find(id, b.peers)
-	if element != nil {
+	if i >= 0 {
 		// BEP5 says not to remove the contact until the bucket is full and you try to insert
-		toPeer(element).Fail()
+		b.peers[i].Fail()
 	}
 }
 
 // find returns the contact in the bucket, or nil if the bucket does not contain the contact
-func find(id Bitmap, peers *list.List) *list.Element {
+func find(id Bitmap, peers []peer) int {
-	for curr := peers.Front(); curr != nil; curr = curr.Next() {
+	for i := range peers {
-		if toPeer(curr).contact.id.Equals(id) {
+		if peers[i].Contact.ID.Equals(id) {
-			return curr
+			return i
 		}
 	}
-	return nil
+	return -1
 }
 
 // NeedsRefresh returns true if bucket has not been updated in the last `refreshInterval`, false otherwise
@@ -243,41 +230,31 @@ func (b *bucket) NeedsRefresh(refreshInterval time.Duration) bool {
 	return time.Now().Sub(b.lastUpdate) > refreshInterval
 }
 
-type RoutingTable interface {
+type routingTable struct {
-	Update(Contact)
-	Fresh(Contact)
-	Fail(Contact)
-	GetClosest(Bitmap, int) []Contact
-	Count() int
-	GetIDsForRefresh(time.Duration) []Bitmap
-	BucketInfo() string // for debugging
-}
-
-type routingTableImpl struct {
 	id      Bitmap
-	buckets [numBuckets]bucket
+	buckets [nodeIDBits]bucket
 }
 
-func newRoutingTable(id Bitmap) *routingTableImpl {
+func newRoutingTable(id Bitmap) *routingTable {
-	var rt routingTableImpl
+	var rt routingTable
 	rt.id = id
 	for i := range rt.buckets {
 		rt.buckets[i] = bucket{
-			peers: list.New(),
+			peers: make([]peer, 0, bucketSize),
 			lock:  &sync.RWMutex{},
 		}
 	}
 	return &rt
 }
 
-func (rt *routingTableImpl) BucketInfo() string {
+func (rt *routingTable) BucketInfo() string {
 	var bucketInfo []string
 	for i, b := range rt.buckets {
 		if b.Len() > 0 {
 			contacts := b.Contacts()
 			s := make([]string, len(contacts))
 			for j, c := range contacts {
-				s[j] = c.id.HexShort()
+				s[j] = c.ID.HexShort()
 			}
 			bucketInfo = append(bucketInfo, fmt.Sprintf("Bucket %d: (%d) %s", i, len(contacts), strings.Join(s, ", ")))
 		}
@@ -289,23 +266,23 @@ func (rt *routingTableImpl) BucketInfo() string {
 }
 
 // Update inserts or refreshes a contact
-func (rt *routingTableImpl) Update(c Contact) {
+func (rt *routingTable) Update(c Contact) {
-	rt.bucketFor(c.id).UpdateContact(c, true)
+	rt.bucketFor(c.ID).UpdateContact(c, true)
 }
 
 // Fresh refreshes a contact if its already in the routing table
-func (rt *routingTableImpl) Fresh(c Contact) {
+func (rt *routingTable) Fresh(c Contact) {
-	rt.bucketFor(c.id).UpdateContact(c, false)
+	rt.bucketFor(c.ID).UpdateContact(c, false)
 }
 
 // FailContact marks a contact as having failed, and removes it if it failed too many times
-func (rt *routingTableImpl) Fail(c Contact) {
+func (rt *routingTable) Fail(c Contact) {
-	rt.bucketFor(c.id).FailContact(c.id)
+	rt.bucketFor(c.ID).FailContact(c.ID)
 }
 
 // GetClosest returns the closest `limit` contacts from the routing table
 // It marks each bucket it accesses as having been accessed
-func (rt *routingTableImpl) GetClosest(target Bitmap, limit int) []Contact {
+func (rt *routingTable) GetClosest(target Bitmap, limit int) []Contact {
 	var toSort []sortedContact
 	var bucketNum int
 
@@ -317,11 +294,11 @@ func (rt *routingTableImpl) GetClosest(target Bitmap, limit int) []Contact {
 
 	toSort = appendContacts(toSort, rt.buckets[bucketNum], target)
 
-	for i := 1; (bucketNum-i >= 0 || bucketNum+i < numBuckets) && len(toSort) < limit; i++ {
+	for i := 1; (bucketNum-i >= 0 || bucketNum+i < nodeIDBits) && len(toSort) < limit; i++ {
 		if bucketNum-i >= 0 {
 			toSort = appendContacts(toSort, rt.buckets[bucketNum-i], target)
 		}
-		if bucketNum+i < numBuckets {
+		if bucketNum+i < nodeIDBits {
 			toSort = appendContacts(toSort, rt.buckets[bucketNum+i], target)
 		}
 	}
@@ -341,13 +318,13 @@ func (rt *routingTableImpl) GetClosest(target Bitmap, limit int) []Contact {
 
 func appendContacts(contacts []sortedContact, b bucket, target Bitmap) []sortedContact {
 	for _, contact := range b.Contacts() {
-		contacts = append(contacts, sortedContact{contact, contact.id.Xor(target)})
+		contacts = append(contacts, sortedContact{contact, contact.ID.Xor(target)})
 	}
 	return contacts
 }
 
 // Count returns the number of contacts in the routing table
-func (rt *routingTableImpl) Count() int {
+func (rt *routingTable) Count() int {
 	count := 0
 	for _, bucket := range rt.buckets {
 		count = bucket.Len()
@@ -355,27 +332,99 @@ func (rt *routingTableImpl) Count() int {
 	return count
 }
 
-func (rt *routingTableImpl) bucketNumFor(target Bitmap) int {
+type Range struct {
+	start Bitmap
+	end   Bitmap
+}
+
+// BucketRanges returns a slice of ranges, where the `start` of each range is the smallest id that can
+// go in that bucket, and the `end` is the largest id
+func (rt *routingTable) BucketRanges() []Range {
+	ranges := make([]Range, len(rt.buckets))
+	for i := range rt.buckets {
+		ranges[i] = Range{
+			rt.id.Suffix(i, false).Set(nodeIDBits-1-i, !rt.id.Get(nodeIDBits-1-i)),
+			rt.id.Suffix(i, true).Set(nodeIDBits-1-i, !rt.id.Get(nodeIDBits-1-i)),
+		}
+	}
+	return ranges
+}
+
+func (rt *routingTable) bucketNumFor(target Bitmap) int {
 	if rt.id.Equals(target) {
 		panic("routing table does not have a bucket for its own id")
 	}
-	return numBuckets - 1 - target.Xor(rt.id).PrefixLen()
+	return nodeIDBits - 1 - target.Xor(rt.id).PrefixLen()
 }
 
-func (rt *routingTableImpl) bucketFor(target Bitmap) *bucket {
+func (rt *routingTable) bucketFor(target Bitmap) *bucket {
 	return &rt.buckets[rt.bucketNumFor(target)]
 }
 
-func (rt *routingTableImpl) GetIDsForRefresh(refreshInterval time.Duration) []Bitmap {
+func (rt *routingTable) GetIDsForRefresh(refreshInterval time.Duration) []Bitmap {
 	var bitmaps []Bitmap
 	for i, bucket := range rt.buckets {
 		if bucket.NeedsRefresh(refreshInterval) {
-			bitmaps = append(bitmaps, RandomBitmapP().ZeroPrefix(i))
+			bitmaps = append(bitmaps, RandomBitmapP().Prefix(i, false))
 		}
 	}
 	return bitmaps
 }
 
+const rtContactSep = "-"
+
+type rtSave struct {
+	ID       string   `json:"id"`
+	Contacts []string `json:"contacts"`
+}
+
+func (rt *routingTable) MarshalJSON() ([]byte, error) {
+	var data rtSave
+	data.ID = rt.id.Hex()
+	for _, b := range rt.buckets {
+		for _, c := range b.Contacts() {
+			data.Contacts = append(data.Contacts, strings.Join([]string{c.ID.Hex(), c.IP.String(), strconv.Itoa(c.Port)}, rtContactSep))
+		}
+	}
+	return json.Marshal(data)
+}
+
+func (rt *routingTable) UnmarshalJSON(b []byte) error {
+	var data rtSave
+	err := json.Unmarshal(b, &data)
+	if err != nil {
+		return err
+	}
+
+	rt.id, err = BitmapFromHex(data.ID)
+	if err != nil {
+		return errors.Prefix("decoding ID", err)
+	}
+
+	for _, s := range data.Contacts {
+		parts := strings.Split(s, rtContactSep)
+		if len(parts) != 3 {
+			return errors.Err("decoding contact %s: wrong number of parts", s)
+		}
+		var c Contact
+		c.ID, err = BitmapFromHex(parts[0])
+		if err != nil {
+			return errors.Err("decoding contact %s: invalid ID: %s", s, err)
+		}
+		c.IP = net.ParseIP(parts[1])
+		if c.IP == nil {
+			return errors.Err("decoding contact %s: invalid IP", s)
+		}
+		c.Port, err = strconv.Atoi(parts[2])
+		if err != nil {
+			return errors.Err("decoding contact %s: invalid port: %s", s, err)
+		}
+		rt.Update(c)
+	}
+
+	return nil
+}
+
 // RoutingTableRefresh refreshes any buckets that need to be refreshed
 // It returns a channel that will be closed when the refresh is done
 func RoutingTableRefresh(n *Node, refreshInterval time.Duration, cancel <-chan struct{}) <-chan struct{} {
@@ -411,3 +460,14 @@ func RoutingTableRefresh(n *Node, refreshInterval time.Duration, cancel <-chan s
 
 	return done
 }
+
+func moveToBack(peers []peer, index int) {
+	if index < 0 || len(peers) <= index+1 {
+		return
+	}
+	p := peers[index]
+	for i := index; i < len(peers)-1; i++ {
+		peers[i] = peers[i+1]
+	}
+	peers[len(peers)-1] = p
+}

dht/routing_table_test.go

@@ -1,9 +1,14 @@
 package dht
 
 import (
+	"encoding/json"
 	"net"
 	"reflect"
+	"strconv"
+	"strings"
 	"testing"
+
+	"github.com/sebdah/goldie"
 )
 
 func TestRoutingTable_bucketFor(t *testing.T) {
@@ -31,7 +36,7 @@ func TestRoutingTable_bucketFor(t *testing.T) {
 	}
 }
 
-func TestRoutingTable(t *testing.T) {
+func TestRoutingTable_GetClosest(t *testing.T) {
 	n1 := BitmapFromHexP("FFFFFFFF0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
 	n2 := BitmapFromHexP("FFFFFFF00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
 	n3 := BitmapFromHexP("111111110000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
@@ -44,7 +49,7 @@ func TestRoutingTable(t *testing.T) {
 		t.Fail()
 		return
 	}
-	if !contacts[0].id.Equals(n3) {
+	if !contacts[0].ID.Equals(n3) {
 		t.Error(contacts[0])
 	}
 
@@ -53,19 +58,19 @@ func TestRoutingTable(t *testing.T) {
 		t.Error(len(contacts))
 		return
 	}
-	if !contacts[0].id.Equals(n2) {
+	if !contacts[0].ID.Equals(n2) {
 		t.Error(contacts[0])
 	}
-	if !contacts[1].id.Equals(n3) {
+	if !contacts[1].ID.Equals(n3) {
 		t.Error(contacts[1])
 	}
 }
 
 func TestCompactEncoding(t *testing.T) {
 	c := Contact{
-		id:   BitmapFromHexP("1c8aff71b99462464d9eeac639595ab99664be3482cb91a29d87467515c7d9158fe72aa1f1582dab07d8f8b5db277f41"),
+		ID:   BitmapFromHexP("1c8aff71b99462464d9eeac639595ab99664be3482cb91a29d87467515c7d9158fe72aa1f1582dab07d8f8b5db277f41"),
-		ip:   net.ParseIP("1.2.3.4"),
+		IP:   net.ParseIP("1.2.3.4"),
-		port: int(55<<8 + 66),
+		Port: int(55<<8 + 66),
 	}
 
 	var compact []byte
@@ -78,11 +83,117 @@ func TestCompactEncoding(t *testing.T) {
 		t.Fatalf("got length of %d; expected %d", len(compact), compactNodeInfoLength)
 	}
 
-	if !reflect.DeepEqual(compact, append([]byte{1, 2, 3, 4, 55, 66}, c.id[:]...)) {
+	if !reflect.DeepEqual(compact, append([]byte{1, 2, 3, 4, 55, 66}, c.ID[:]...)) {
 		t.Errorf("compact bytes not encoded correctly")
 	}
 }
 
-func TestRoutingTableRefresh(t *testing.T) {
+func TestRoutingTable_Refresh(t *testing.T) {
 	t.Skip("TODO: test routing table refreshing")
 }
+
+func TestRoutingTable_MoveToBack(t *testing.T) {
+	tt := map[string]struct {
+		data     []peer
+		index    int
+		expected []peer
+	}{
+		"simpleMove": {
+			data:     []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+			index:    1,
+			expected: []peer{{NumFailures: 0}, {NumFailures: 2}, {NumFailures: 3}, {NumFailures: 1}},
+		},
+		"moveFirst": {
+			data:     []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+			index:    0,
+			expected: []peer{{NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}, {NumFailures: 0}},
+		},
+		"moveLast": {
+			data:     []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+			index:    3,
+			expected: []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+		},
+		"largeIndex": {
+			data:     []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+			index:    27,
+			expected: []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+		},
+		"negativeIndex": {
+			data:     []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+			index:    -12,
+			expected: []peer{{NumFailures: 0}, {NumFailures: 1}, {NumFailures: 2}, {NumFailures: 3}},
+		},
+	}
+
+	for name, test := range tt {
+		moveToBack(test.data, test.index)
+		expected := make([]string, len(test.expected))
+		actual := make([]string, len(test.data))
+		for i := range actual {
+			actual[i] = strconv.Itoa(test.data[i].NumFailures)
+			expected[i] = strconv.Itoa(test.expected[i].NumFailures)
+		}
+
+		expJoin := strings.Join(expected, ",")
+		actJoin := strings.Join(actual, ",")
+
+		if actJoin != expJoin {
+			t.Errorf("%s failed: got %s; expected %s", name, actJoin, expJoin)
+		}
+	}
+}
+
+func TestRoutingTable_BucketRanges(t *testing.T) {
+	id := BitmapFromHexP("1c8aff71b99462464d9eeac639595ab99664be3482cb91a29d87467515c7d9158fe72aa1f1582dab07d8f8b5db277f41")
+	ranges := newRoutingTable(id).BucketRanges()
+	if !ranges[0].start.Equals(ranges[0].end) {
+		t.Error("first bucket should only fit exactly one id")
+	}
+	for i := 0; i < 1000; i++ {
+		randID := RandomBitmapP()
+		found := -1
+		for i, r := range ranges {
+			if r.start.LessOrEqual(randID) && r.end.GreaterOrEqual(randID) {
+				if found >= 0 {
+					t.Errorf("%s appears in buckets %d and %d", randID.Hex(), found, i)
+				} else {
+					found = i
+				}
+			}
+		}
+		if found < 0 {
+			t.Errorf("%s did not appear in any bucket", randID.Hex())
+		}
+	}
+}
+
+func TestRoutingTable_Save(t *testing.T) {
+	id := BitmapFromHexP("1c8aff71b99462464d9eeac639595ab99664be3482cb91a29d87467515c7d9158fe72aa1f1582dab07d8f8b5db277f41")
+	rt := newRoutingTable(id)
+
+	ranges := rt.BucketRanges()
+
+	for i, r := range ranges {
+		for j := 0; j < bucketSize; j++ {
+			toAdd := r.start.Add(BitmapFromShortHexP(strconv.Itoa(j)))
+			if toAdd.LessOrEqual(r.end) {
+				rt.Update(Contact{
+					ID:   r.start.Add(BitmapFromShortHexP(strconv.Itoa(j))),
+					IP:   net.ParseIP("1.2.3." + strconv.Itoa(j)),
+					Port: 1 + i*bucketSize + j,
+				})
+			}
+		}
+	}
+
+	data, err := json.MarshalIndent(rt, "", "  ")
+	if err != nil {
+		t.Error(err)
+	}
+
+	goldie.Assert(t, t.Name(), data)
+}
+
+func TestRoutingTable_Load(t *testing.T) {
+	t.Skip("TODO")
+}

dht/store.go

@@ -2,13 +2,7 @@ package dht
 
 import "sync"
 
-type Store interface {
+type contactStore struct {
-	Upsert(Bitmap, Contact)
-	Get(Bitmap) []Contact
-	CountStoredHashes() int
-}
-
-type storeImpl struct {
 	// map of blob hashes to (map of node IDs to bools)
 	hashes map[Bitmap]map[Bitmap]bool
 	// stores the peers themselves, so they can be updated in one place
@@ -16,25 +10,25 @@ type storeImpl struct {
 	lock     sync.RWMutex
 }
 
-func newStore() *storeImpl {
+func newStore() *contactStore {
-	return &storeImpl{
+	return &contactStore{
 		hashes:   make(map[Bitmap]map[Bitmap]bool),
 		contacts: make(map[Bitmap]Contact),
 	}
 }
 
-func (s *storeImpl) Upsert(blobHash Bitmap, contact Contact) {
+func (s *contactStore) Upsert(blobHash Bitmap, contact Contact) {
 	s.lock.Lock()
 	defer s.lock.Unlock()
 
 	if _, ok := s.hashes[blobHash]; !ok {
 		s.hashes[blobHash] = make(map[Bitmap]bool)
 	}
-	s.hashes[blobHash][contact.id] = true
+	s.hashes[blobHash][contact.ID] = true
-	s.contacts[contact.id] = contact
+	s.contacts[contact.ID] = contact
 }
 
-func (s *storeImpl) Get(blobHash Bitmap) []Contact {
+func (s *contactStore) Get(blobHash Bitmap) []Contact {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
 
@@ -51,11 +45,11 @@ func (s *storeImpl) Get(blobHash Bitmap) []Contact {
 	return contacts
 }
 
-func (s *storeImpl) RemoveTODO(contact Contact) {
+func (s *contactStore) RemoveTODO(contact Contact) {
 	// TODO: remove peer from everywhere
 }
 
-func (s *storeImpl) CountStoredHashes() int {
+func (s *contactStore) CountStoredHashes() int {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
 	return len(s.hashes)

dht/testing.go

@@ -215,7 +215,7 @@ func verifyContacts(t *testing.T, contacts []interface{}, nodes []Contact) {
 				continue
 			}
 			for _, n := range nodes {
-				if n.id.RawString() == id {
+				if n.ID.RawString() == id {
 					currNode = n
 					currNodeFound = true
 					foundNodes[id] = true
@@ -231,15 +231,15 @@ func verifyContacts(t *testing.T, contacts []interface{}, nodes []Contact) {
 		ip, ok := contact[1].(string)
 		if !ok {
 			t.Error("contact IP is not a string")
-		} else if !currNode.ip.Equal(net.ParseIP(ip)) {
+		} else if !currNode.IP.Equal(net.ParseIP(ip)) {
-			t.Errorf("contact IP mismatch. got %s; expected %s", ip, currNode.ip.String())
+			t.Errorf("contact IP mismatch. got %s; expected %s", ip, currNode.IP.String())
 		}
 
 		port, ok := contact[2].(int64)
 		if !ok {
 			t.Error("contact port is not an int")
-		} else if int(port) != currNode.port {
+		} else if int(port) != currNode.Port {
-			t.Errorf("contact port mismatch. got %d; expected %d", port, currNode.port)
+			t.Errorf("contact port mismatch. got %d; expected %d", port, currNode.Port)
 		}
 	}
 }
@@ -269,29 +269,38 @@ func verifyCompactContacts(t *testing.T, contacts []interface{}, nodes []Contact
 		var currNode Contact
 		currNodeFound := false
 
-		if _, ok := foundNodes[contact.id.Hex()]; ok {
+		if _, ok := foundNodes[contact.ID.Hex()]; ok {
-			t.Errorf("contact %s appears multiple times", contact.id.Hex())
+			t.Errorf("contact %s appears multiple times", contact.ID.Hex())
 			continue
 		}
 		for _, n := range nodes {
-			if n.id.Equals(contact.id) {
+			if n.ID.Equals(contact.ID) {
 				currNode = n
 				currNodeFound = true
-				foundNodes[contact.id.Hex()] = true
+				foundNodes[contact.ID.Hex()] = true
 				break
 			}
 		}
 		if !currNodeFound {
-			t.Errorf("unexpected contact %s", contact.id.Hex())
+			t.Errorf("unexpected contact %s", contact.ID.Hex())
 			continue
 		}
 
-		if !currNode.ip.Equal(contact.ip) {
+		if !currNode.IP.Equal(contact.IP) {
-			t.Errorf("contact IP mismatch. got %s; expected %s", contact.ip.String(), currNode.ip.String())
+			t.Errorf("contact IP mismatch. got %s; expected %s", contact.IP.String(), currNode.IP.String())
 		}
 
-		if contact.port != currNode.port {
+		if contact.Port != currNode.Port {
-			t.Errorf("contact port mismatch. got %d; expected %d", contact.port, currNode.port)
+			t.Errorf("contact port mismatch. got %d; expected %d", contact.Port, currNode.Port)
 		}
 	}
 }
+
+func assertPanic(t *testing.T, text string, f func()) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("%s: did not panic as expected", text)
+		}
+	}()
+	f()
+}