all: use Go 1.22 range-over-int

Updates #11058

Change-Id: I35e7ef9b90e83cac04ca93fd964ad00ed5b48430
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

client/web/auth.go

@@ -223,7 +223,7 @@ func (s *Server) awaitUserAuth(ctx context.Context, session *browserSession) err
 
 func (s *Server) newSessionID() (string, error) {
 	raw := make([]byte, 16)
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		if _, err := rand.Read(raw); err != nil {
 			return "", err
 		}

clientupdate/clientupdate.go

@@ -436,7 +436,7 @@ func (up *Updater) updateDebLike() error {
 		return fmt.Errorf("apt-get update failed: %w; output:\n%s", err, out)
 	}
 
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		out, err := exec.Command("apt-get", "install", "--yes", "--allow-downgrades", "tailscale="+ver).CombinedOutput()
 		if err != nil {
 			if !bytes.Contains(out, []byte(`dpkg was interrupted`)) {

clientupdate/clientupdate_test.go

@@ -663,7 +663,7 @@ func genTarball(t *testing.T, path string, files map[string]string) {
 
 func TestWriteFileOverwrite(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "test")
-	for i := 0; i < 2; i++ {
+	for i := range 2 {
 		content := fmt.Sprintf("content %d", i)
 		if err := writeFile(strings.NewReader(content), path, 0600); err != nil {
 			t.Fatal(err)

clientupdate/distsign/distsign_test.go

@@ -445,7 +445,7 @@ type testServer struct {
 
 func newTestServer(t *testing.T) *testServer {
 	var roots []rootKeyPair
-	for i := 0; i < 3; i++ {
+	for range 3 {
 		roots = append(roots, newRootKeyPair(t))
 	}
 

cmd/cloner/cloner.go

@@ -102,7 +102,7 @@ func gen(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named) {
 	writef("}")
 	writef("dst := new(%s)", name)
 	writef("*dst = *src")
-	for i := 0; i < t.NumFields(); i++ {
+	for i := range t.NumFields() {
 		fname := t.Field(i).Name()
 		ft := t.Field(i).Type()
 		if !codegen.ContainsPointers(ft) || codegen.HasNoClone(t.Tag(i)) {

cmd/k8s-operator/testutils_test.go

@@ -522,7 +522,7 @@ func expectEvents(t *testing.T, rec *record.FakeRecorder, wantsEvents []string)
 	t.Helper()
 	// Events are not expected to arrive in order.
 	seenEvents := make([]string, 0)
-	for i := 0; i < len(wantsEvents); i++ {
+	for range len(wantsEvents) {
 		timer := time.NewTimer(time.Second * 5)
 		defer timer.Stop()
 		select {

cmd/netlogfmt/main.go

@@ -314,7 +314,7 @@ func mustMakeNamesByAddr() map[netip.Addr]string {
 	seen := make(map[string]bool)
 	namesByAddr := make(map[netip.Addr]string)
 retry:
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		clear(seen)
 		clear(namesByAddr)
 		for _, d := range m.Devices {
@@ -354,7 +354,7 @@ func fieldPrefix(s string, n int) string {
 }
 
 func appendRepeatByte(b []byte, c byte, n int) []byte {
-	for i := 0; i < n; i++ {
+	for range n {
 		b = append(b, c)
 	}
 	return b

cmd/proxy-to-grafana/proxy-to-grafana.go

@@ -88,7 +88,7 @@ func main() {
 
 		go func() {
 			// wait for tailscale to start before trying to fetch cert names
-			for i := 0; i < 60; i++ {
+			for range 60 {
 				st, err := localClient.Status(context.Background())
 				if err != nil {
 					log.Printf("error retrieving tailscale status; retrying: %v", err)

cmd/sniproxy/sniproxy_test.go

@@ -158,7 +158,7 @@ func TestSNIProxyWithNetmapConfig(t *testing.T) {
 		t.Fatal(err)
 	}
 	gotConfigured := false
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		s, err := l.StatusWithoutPeers(ctx)
 		if err != nil {
 			t.Fatal(err)

cmd/tailscale/cli/cli_test.go

@@ -831,7 +831,7 @@ func TestPrefFlagMapping(t *testing.T) {
 	}
 
 	prefType := reflect.TypeFor[ipn.Prefs]()
-	for i := 0; i < prefType.NumField(); i++ {
+	for i := range prefType.NumField() {
 		prefName := prefType.Field(i).Name
 		if prefHasFlag[prefName] {
 			continue

cmd/tailscale/cli/network-lock.go

@@ -148,7 +148,7 @@ func runNetworkLockInit(ctx context.Context, args []string) error {
 	}
 
 	fmt.Printf("%d disablement secrets have been generated and are printed below. Take note of them now, they WILL NOT be shown again.\n", nlInitArgs.numDisablements)
-	for i := 0; i < nlInitArgs.numDisablements; i++ {
+	for range nlInitArgs.numDisablements {
 		var secret [32]byte
 		if _, err := rand.Read(secret[:]); err != nil {
 			return err

cmd/tailscale/cli/serve_legacy.go

@@ -387,7 +387,7 @@ func isProxyTarget(source string) bool {
 // allNumeric reports whether s only comprises of digits
 // and has at least one digit.
 func allNumeric(s string) bool {
-	for i := 0; i < len(s); i++ {
+	for i := range len(s) {
 		if s[i] < '0' || s[i] > '9' {
 			return false
 		}

cmd/testcontrol/testcontrol.go

@@ -29,7 +29,7 @@ func main() {
 		DERPMap:         derpMap,
 		ExplicitBaseURL: "http://127.0.0.1:9911",
 	}
-	for i := 0; i < *flagNFake; i++ {
+	for range *flagNFake {
 		control.AddFakeNode()
 	}
 	mux := http.NewServeMux()

cmd/viewer/viewer.go

@@ -149,7 +149,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 		}
 	}
 	writeTemplate("common")
-	for i := 0; i < t.NumFields(); i++ {
+	for i := range t.NumFields() {
 		f := t.Field(i)
 		fname := f.Name()
 		if !f.Exported() {
@@ -292,7 +292,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 		}
 		writeTemplate("unsupportedField")
 	}
-	for i := 0; i < typ.NumMethods(); i++ {
+	for i := range typ.NumMethods() {
 		f := typ.Method(i)
 		if !f.Exported() {
 			continue

control/controlbase/conn_test.go

@@ -91,7 +91,7 @@ func TestFastPath(t *testing.T) {
 
 	const packets = 10
 	s := "test"
-	for i := 0; i < packets; i++ {
+	for range packets {
 		// Many separate writes, to force separate Noise frames that
 		// all get buffered up and then all sent as a single slice to
 		// the server.
@@ -251,7 +251,7 @@ func TestConnMemoryOverhead(t *testing.T) {
 	}
 	defer closeAll()
 
-	for i := 0; i < num; i++ {
+	for range num {
 		client, server := pair(t)
 		closers = append(closers, client, server)
 		go func() {

control/controlbase/handshake_test.go

@@ -64,7 +64,7 @@ func TestNoReuse(t *testing.T) {
 		serverHandshakes = map[[48]byte]bool{}
 		packets          = map[[32]byte]bool{}
 	)
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		var (
 			clientRaw, serverRaw = memnet.NewConn("noise", 128000)
 			clientBuf, serverBuf bytes.Buffer
@@ -162,7 +162,7 @@ func (r *tamperReader) Read(bs []byte) (int, error) {
 
 func TestTampering(t *testing.T) {
 	// Tamper with every byte of the client initiation message.
-	for i := 0; i < 101; i++ {
+	for i := range 101 {
 		var (
 			clientConn, serverRaw = memnet.NewConn("noise", 128000)
 			serverConn            = &readerConn{serverRaw, &tamperReader{serverRaw, i, 0}}
@@ -190,7 +190,7 @@ func TestTampering(t *testing.T) {
 	}
 
 	// Tamper with every byte of the server response message.
-	for i := 0; i < 51; i++ {
+	for i := range 51 {
 		var (
 			clientRaw, serverConn = memnet.NewConn("noise", 128000)
 			clientConn            = &readerConn{clientRaw, &tamperReader{clientRaw, i, 0}}
@@ -215,7 +215,7 @@ func TestTampering(t *testing.T) {
 	}
 
 	// Tamper with every byte of the first server>client transport message.
-	for i := 0; i < 30; i++ {
+	for i := range 30 {
 		var (
 			clientRaw, serverConn = memnet.NewConn("noise", 128000)
 			clientConn            = &readerConn{clientRaw, &tamperReader{clientRaw, 51 + i, 0}}
@@ -256,7 +256,7 @@ func TestTampering(t *testing.T) {
 	}
 
 	// Tamper with every byte of the first client>server transport message.
-	for i := 0; i < 30; i++ {
+	for i := range 30 {
 		var (
 			clientConn, serverRaw = memnet.NewConn("noise", 128000)
 			serverConn            = &readerConn{serverRaw, &tamperReader{serverRaw, 101 + i, 0}}

control/controlclient/controlclient_test.go

@@ -9,7 +9,7 @@
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
-	for i := 0; i < t.NumField(); i++ {
+	for i := range t.NumField() {
 		if name := t.Field(i).Name; name != "_" {
 			fields = append(fields, name)
 		}

control/controlclient/map.go

@@ -563,7 +563,7 @@ func (ms *mapSession) patchifyPeersChanged(resp *tailcfg.MapResponse) {
 func getNodeFields() []string {
 	rt := reflect.TypeFor[tailcfg.Node]()
 	ret := make([]string, rt.NumField())
-	for i := 0; i < rt.NumField(); i++ {
+	for i := range rt.NumField() {
 		ret[i] = rt.Field(i).Name
 	}
 	return ret

control/controlclient/map_test.go

@@ -1019,7 +1019,7 @@ func BenchmarkMapSessionDelta(b *testing.B) {
 					Name: "foo.bar.ts.net.",
 				},
 			}
-			for i := 0; i < size; i++ {
+			for i := range size {
 				res.Peers = append(res.Peers, &tailcfg.Node{
 					ID:         tailcfg.NodeID(i + 2),
 					Name:       fmt.Sprintf("peer%d.bar.ts.net.", i),
@@ -1046,7 +1046,7 @@ func BenchmarkMapSessionDelta(b *testing.B) {
 
 			// Now for the core of the benchmark loop, just toggle
 			// a single node's online status.
-			for i := 0; i < b.N; i++ {
+			for i := range b.N {
 				if err := ms.HandleNonKeepAliveMapResponse(ctx, &tailcfg.MapResponse{
 					OnlineChange: map[tailcfg.NodeID]bool{
 						2: i%2 == 0,

control/controlhttp/http_test.go

@@ -729,7 +729,7 @@ func (d *closeTrackDialer) Done() {
 	// Sleep/wait a few times on the assumption that things will close
 	// "eventually".
 	const iters = 100
-	for i := 0; i < iters; i++ {
+	for i := range iters {
 		d.mu.Lock()
 		if len(d.conns) == 0 {
 			d.mu.Unlock()

derp/derp_test.go

@@ -56,7 +56,7 @@ func TestSendRecv(t *testing.T) {
 	const numClients = 3
 	var clientPrivateKeys []key.NodePrivate
 	var clientKeys []key.NodePublic
-	for i := 0; i < numClients; i++ {
+	for range numClients {
 		priv := key.NewNode()
 		clientPrivateKeys = append(clientPrivateKeys, priv)
 		clientKeys = append(clientKeys, priv.Public())
@@ -73,7 +73,7 @@ func TestSendRecv(t *testing.T) {
 	var recvChs []chan []byte
 	errCh := make(chan error, 3)
 
-	for i := 0; i < numClients; i++ {
+	for i := range numClients {
 		t.Logf("Connecting client %d ...", i)
 		cout, err := net.Dial("tcp", ln.Addr().String())
 		if err != nil {
@@ -111,7 +111,7 @@ func TestSendRecv(t *testing.T) {
 	var peerGoneCountNotHere expvar.Int
 
 	t.Logf("Starting read loops")
-	for i := 0; i < numClients; i++ {
+	for i := range numClients {
 		go func(i int) {
 			for {
 				m, err := clients[i].Recv()
@@ -233,7 +233,7 @@ func TestSendRecv(t *testing.T) {
 	wantUnknownPeers(1)
 
 	// PeerGoneNotHere is rate-limited to 3 times a second
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		if err := clients[1].Send(neKey, callMe); err != nil {
 			t.Fatal(err)
 		}
@@ -389,7 +389,7 @@ func TestSendFreeze(t *testing.T) {
 		// if any tokens remain in the channel, they
 		// must have been generated after drainAny was
 		// called.
-		for i := 0; i < cap(ch); i++ {
+		for range cap(ch) {
 			select {
 			case <-ch:
 			default:
@@ -456,7 +456,7 @@ func TestSendFreeze(t *testing.T) {
 	aliceConn.Close()
 	cathyConn.Close()
 
-	for i := 0; i < cap(errCh); i++ {
+	for range cap(errCh) {
 		err := <-errCh
 		if err != nil {
 			if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) {
@@ -891,7 +891,7 @@ func TestMultiForwarder(t *testing.T) {
 	// run long enough concurrently with {Add,Remove}PacketForwarder loop above.
 	numMsgs := 5000
 	var fwd PacketForwarder
-	for i := 0; i < numMsgs; i++ {
+	for i := range numMsgs {
 		s.mu.Lock()
 		fwd = s.clientsMesh[u]
 		s.mu.Unlock()
@@ -1288,7 +1288,7 @@ func TestServerDupClients(t *testing.T) {
 
 func TestLimiter(t *testing.T) {
 	rl := rate.NewLimiter(rate.Every(time.Minute), 100)
-	for i := 0; i < 200; i++ {
+	for i := range 200 {
 		r := rl.Reserve()
 		d := r.Delay()
 		t.Logf("i=%d, allow=%v, d=%v", i, r.OK(), d)
@@ -1352,7 +1352,7 @@ func benchmarkSendRecvSize(b *testing.B, packetSize int) {
 	b.SetBytes(int64(len(msg)))
 	b.ReportAllocs()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		if err := client.Send(clientKey, msg); err != nil {
 			b.Fatal(err)
 		}
@@ -1363,7 +1363,7 @@ func BenchmarkWriteUint32(b *testing.B) {
 	w := bufio.NewWriter(io.Discard)
 	b.ReportAllocs()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		writeUint32(w, 0x0ba3a)
 	}
 }
@@ -1381,7 +1381,7 @@ func BenchmarkReadUint32(b *testing.B) {
 	var err error
 	b.ReportAllocs()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sinkU32, err = readUint32(r)
 		if err != nil {
 			b.Fatal(err)
@@ -1454,7 +1454,7 @@ func TestClientSendRateLimiting(t *testing.T) {
 
 	// Flood should all succeed.
 	cw.ResetStats()
-	for i := 0; i < 1000; i++ {
+	for range 1000 {
 		if err := c.send(key.NodePublic{}, pkt); err != nil {
 			t.Fatal(err)
 		}
@@ -1473,7 +1473,7 @@ func TestClientSendRateLimiting(t *testing.T) {
 		TokenBucketBytesPerSecond: 1,
 		TokenBucketBytesBurst:     int(bytes1 * 2),
 	})
-	for i := 0; i < 1000; i++ {
+	for range 1000 {
 		if err := c.send(key.NodePublic{}, pkt); err != nil {
 			t.Fatal(err)
 		}

derp/derphttp/derphttp_test.go

@@ -25,7 +25,7 @@ func TestSendRecv(t *testing.T) {
 	const numClients = 3
 	var clientPrivateKeys []key.NodePrivate
 	var clientKeys []key.NodePublic
-	for i := 0; i < numClients; i++ {
+	for range numClients {
 		priv := key.NewNode()
 		clientPrivateKeys = append(clientPrivateKeys, priv)
 		clientKeys = append(clientKeys, priv.Public())
@@ -66,7 +66,7 @@ func TestSendRecv(t *testing.T) {
 		}
 		wg.Wait()
 	}()
-	for i := 0; i < numClients; i++ {
+	for i := range numClients {
 		key := clientPrivateKeys[i]
 		c, err := NewClient(key, serverURL, t.Logf)
 		if err != nil {
@@ -311,7 +311,7 @@ func TestBreakWatcherConnRecv(t *testing.T) {
 
 	// Wait for the watcher to run, then break the connection and check if it
 	// reconnected and received peer updates.
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		select {
 		case peers := <-watcherChan:
 			if peers != 1 {
@@ -384,7 +384,7 @@ func TestBreakWatcherConn(t *testing.T) {
 
 	// Wait for the watcher to run, then break the connection and check if it
 	// reconnected and received peer updates.
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		select {
 		case peers := <-watcherChan:
 			if peers != 1 {

health/health_test.go

@@ -15,7 +15,7 @@
 func TestAppendWarnableDebugFlags(t *testing.T) {
 	resetWarnables()
 
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		w := NewWarnable(WithMapDebugFlag(fmt.Sprint(i)))
 		if i%2 == 0 {
 			w.Set(errors.New("boom"))
@@ -25,7 +25,7 @@ func TestAppendWarnableDebugFlags(t *testing.T) {
 	want := []string{"z", "y", "0", "2", "4", "6", "8"}
 
 	var got []string
-	for i := 0; i < 20; i++ {
+	for range 20 {
 		got = append(got[:0], "z", "y")
 		got = AppendWarnableDebugFlags(got)
 		if !reflect.DeepEqual(got, want) {

ipn/ipnlocal/drive.go

@@ -93,7 +93,7 @@ func (b *LocalBackend) driveSetShareLocked(share *drive.Share) (views.SliceView[
 
 	addedShare := false
 	var shares []*drive.Share
-	for i := 0; i < existingShares.Len(); i++ {
+	for i := range existingShares.Len() {
 		existing := existingShares.At(i)
 		if existing.Name() != share.Name {
 			if !addedShare && existing.Name() > share.Name {
@@ -152,7 +152,7 @@ func (b *LocalBackend) driveRenameShareLocked(oldName, newName string) (views.Sl
 
 	found := false
 	var shares []*drive.Share
-	for i := 0; i < existingShares.Len(); i++ {
+	for i := range existingShares.Len() {
 		existing := existingShares.At(i)
 		if existing.Name() == newName {
 			return existingShares, os.ErrExist
@@ -213,7 +213,7 @@ func (b *LocalBackend) driveRemoveShareLocked(name string) (views.SliceView[*dri
 
 	found := false
 	var shares []*drive.Share
-	for i := 0; i < existingShares.Len(); i++ {
+	for i := range existingShares.Len() {
 		existing := existingShares.At(i)
 		if existing.Name() != name {
 			shares = append(shares, existing.AsStruct())
@@ -281,7 +281,7 @@ func driveShareViewsEqual(a *views.SliceView[*drive.Share, drive.ShareView], b v
 		return false
 	}
 
-	for i := 0; i < a.Len(); i++ {
+	for i := range a.Len() {
 		if !drive.ShareViewsEqual(a.At(i), b.At(i)) {
 			return false
 		}

ipn/ipnlocal/local.go

@@ -446,7 +446,7 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, sys *tsd.System, lo
 		currentShares := b.pm.prefs.DriveShares()
 		if currentShares.Len() > 0 {
 			var shares []*drive.Share
-			for i := 0; i < currentShares.Len(); i++ {
+			for i := range currentShares.Len() {
 				shares = append(shares, currentShares.At(i).AsStruct())
 			}
 			fs.SetShares(shares)
@@ -1855,7 +1855,7 @@ func (b *LocalBackend) updateFilterLocked(netMap *netmap.NetworkMap, prefs ipn.P
 	}
 	if prefs.Valid() {
 		ar := prefs.AdvertiseRoutes()
-		for i := 0; i < ar.Len(); i++ {
+		for i := range ar.Len() {
 			r := ar.At(i)
 			if r.Bits() == 0 {
 				// When offering a default route to the world, we
@@ -5418,7 +5418,7 @@ func (b *LocalBackend) OfferingExitNode() bool {
 	}
 	var def4, def6 bool
 	ar := b.pm.CurrentPrefs().AdvertiseRoutes()
-	for i := 0; i < ar.Len(); i++ {
+	for i := range ar.Len() {
 		r := ar.At(i)
 		if r.Bits() != 0 {
 			continue

ipn/ipnlocal/local_test.go

@@ -949,7 +949,7 @@ func TestUpdateNetmapDelta(t *testing.T) {
 	}
 
 	b.netMap = &netmap.NetworkMap{}
-	for i := 0; i < 5; i++ {
+	for i := range 5 {
 		b.netMap.Peers = append(b.netMap.Peers, (&tailcfg.Node{ID: (tailcfg.NodeID(i) + 1)}).View())
 	}
 	b.updatePeersFromNetmapLocked(b.netMap)

ipn/ipnlocal/loglines_test.go

@@ -39,7 +39,7 @@ func TestLocalLogLines(t *testing.T) {
 
 	logid := func(hex byte) logid.PublicID {
 		var ret logid.PublicID
-		for i := 0; i < len(ret); i++ {
+		for i := range len(ret) {
 			ret[i] = hex
 		}
 		return ret

ipn/ipnlocal/network-lock.go

@@ -338,7 +338,7 @@ func (b *LocalBackend) tkaBootstrapFromGenesisLocked(g tkatype.MarshaledAUM, per
 		}
 		bootstrapStateID := fmt.Sprintf("%d:%d", genesis.State.StateID1, genesis.State.StateID2)
 
-		for i := 0; i < persist.DisallowedTKAStateIDs().Len(); i++ {
+		for i := range persist.DisallowedTKAStateIDs().Len() {
 			stateID := persist.DisallowedTKAStateIDs().At(i)
 			if stateID == bootstrapStateID {
 				return fmt.Errorf("TKA with stateID of %q is disallowed on this node", stateID)
@@ -439,7 +439,7 @@ func (b *LocalBackend) NetworkLockStatus() *ipnstate.NetworkLockStatus {
 	}
 
 	filtered := make([]*ipnstate.TKAFilteredPeer, len(b.tka.filtered))
-	for i := 0; i < len(filtered); i++ {
+	for i := range len(filtered) {
 		filtered[i] = b.tka.filtered[i].Clone()
 	}
 
@@ -765,7 +765,7 @@ func (b *LocalBackend) NetworkLockLog(maxEntries int) ([]ipnstate.NetworkLockUpd
 
 	var out []ipnstate.NetworkLockUpdate
 	cursor := b.tka.authority.Head()
-	for i := 0; i < maxEntries; i++ {
+	for range maxEntries {
 		aum, err := b.tka.storage.AUM(cursor)
 		if err != nil {
 			if err == os.ErrNotExist {

ipn/ipnlocal/peerapi_test.go

@@ -109,7 +109,7 @@ func fileHasContents(name string, want string) check {
 
 func hexAll(v string) string {
 	var sb strings.Builder
-	for i := 0; i < len(v); i++ {
+	for i := range len(v) {
 		fmt.Fprintf(&sb, "%%%02x", v[i])
 	}
 	return sb.String()
@@ -604,7 +604,7 @@ func TestFileDeleteRace(t *testing.T) {
 		ps: ps,
 	}
 	buf := make([]byte, 2<<20)
-	for i := 0; i < 30; i++ {
+	for range 30 {
 		rr := httptest.NewRecorder()
 		ph.ServeHTTP(rr, httptest.NewRequest("PUT", "http://100.100.100.101:123/v0/put/foo.txt", bytes.NewReader(buf[:rand.Intn(len(buf))])))
 		if res := rr.Result(); res.StatusCode != 200 {

ipn/ipnlocal/serve.go

@@ -868,7 +868,7 @@ func expandProxyArg(s string) (targetURL string, insecureSkipVerify bool) {
 }
 
 func allNumeric(s string) bool {
-	for i := 0; i < len(s); i++ {
+	for i := range len(s) {
 		if s[i] < '0' || s[i] > '9' {
 			return false
 		}

ipn/ipnlocal/state_test.go

@@ -70,7 +70,7 @@ func (nt *notifyThrottler) drain(count int) []ipn.Notify {
 	nt.mu.Unlock()
 
 	nn := []ipn.Notify{}
-	for i := 0; i < count; i++ {
+	for i := range count {
 		select {
 		case n := <-ch:
 			nn = append(nn, n)
@@ -1039,7 +1039,7 @@ func TestWGEngineStatusRace(t *testing.T) {
 	// we would end up in state ipn.Running.
 	// The same should thus be true if these callbacks occur concurrently.
 	var wg sync.WaitGroup
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		wg.Add(1)
 		go func(i int) {
 			defer wg.Done()

ipn/ipnserver/server.go

@@ -342,7 +342,7 @@ func userIDFromString(v string) string {
 }
 
 func isAllDigit(s string) bool {
-	for i := 0; i < len(s); i++ {
+	for i := range len(s) {
 		if b := s[i]; b < '0' || b > '9' {
 			return false
 		}

ipn/localapi/debugderp.go

@@ -247,7 +247,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 		// Next, repeatedly get the server key to see if the node is
 		// behind a load balancer (incorrectly).
 		serverPubKeys := make(map[key.NodePublic]bool)
-		for i := 0; i < 5; i++ {
+		for i := range 5 {
 			func() {
 				rc := derphttp.NewRegionClient(fakePrivKey, h.logf, h.netMon, func() *tailcfg.DERPRegion {
 					return &tailcfg.DERPRegion{

ipn/localapi/localapi.go

@@ -903,7 +903,7 @@ type result struct {
 	}
 
 	wg.Wait()
-	for i := 0; i < len(dialers); i++ {
+	for range len(dialers) {
 		res := <-results
 		fmt.Fprintf(w, "[%s] connected=%v err=%v\n", res.name, res.conn != nil, res.err)
 		if res.conn != nil {

ipn/prefs.go

@@ -363,7 +363,7 @@ func applyPrefsEdits(src, dst reflect.Value, mask map[string]reflect.Value) {
 
 func maskFields(v reflect.Value) map[string]reflect.Value {
 	mask := make(map[string]reflect.Value)
-	for i := 0; i < v.NumField(); i++ {
+	for i := range v.NumField() {
 		f := v.Type().Field(i).Name
 		if !strings.HasSuffix(f, "Set") {
 			continue

ipn/prefs_test.go

@@ -26,7 +26,7 @@
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
-	for i := 0; i < t.NumField(); i++ {
+	for i := range t.NumField() {
 		fields = append(fields, t.Field(i).Name)
 	}
 	return
@@ -661,7 +661,7 @@ func TestMaskedPrefsFields(t *testing.T) {
 	// ApplyEdits assumes.
 	pt := reflect.TypeFor[Prefs]()
 	mt := reflect.TypeFor[MaskedPrefs]()
-	for i := 0; i < mt.NumField(); i++ {
+	for i := range mt.NumField() {
 		name := mt.Field(i).Name
 		if i == 0 {
 			if name != "Prefs" {

logtail/filch/filch_test.go

@@ -75,11 +75,11 @@ func TestDropOldLogs(t *testing.T) {
 			f := newFilchTest(t, filePrefix, Options{ReplaceStderr: false, MaxFileSize: 1000})
 			defer f.close(t)
 			// Make filch rotate the logs 3 times
-			for i := 0; i < tc.write; i++ {
+			for range tc.write {
 				f.write(t, line1)
 			}
 			// We should only be able to read the last 150 lines
-			for i := 0; i < tc.read; i++ {
+			for i := range tc.read {
 				f.read(t, line1)
 				if t.Failed() {
 					t.Logf("could only read %d lines", i)

logtail/logtail_test.go

@@ -77,7 +77,7 @@ func(w http.ResponseWriter, r *http.Request) {
 func TestDrainPendingMessages(t *testing.T) {
 	ts, l := NewLogtailTestHarness(t)
 
-	for i := 0; i < logLines; i++ {
+	for range logLines {
 		l.Write([]byte("log line"))
 	}
 
@@ -540,7 +540,7 @@ func BenchmarkWriteText(b *testing.B) {
 	l.clock = tstime.StdClock{}
 	l.buffer = discardBuffer{}
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		must.Get(l.Write(testdataTextLog))
 	}
 }
@@ -550,7 +550,7 @@ func BenchmarkWriteJSON(b *testing.B) {
 	l.clock = tstime.StdClock{}
 	l.buffer = discardBuffer{}
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		must.Get(l.Write(testdataJSONLog))
 	}
 }

metrics/metrics_test.go

@@ -41,7 +41,7 @@ func TestCurrentFileDescriptors(t *testing.T) {
 
 	// Open some FDs.
 	const extra = 10
-	for i := 0; i < extra; i++ {
+	for i := range extra {
 		f, err := os.Open("/proc/self/stat")
 		if err != nil {
 			t.Fatal(err)
@@ -58,7 +58,7 @@ func TestCurrentFileDescriptors(t *testing.T) {
 
 func BenchmarkCurrentFileDescriptors(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		_ = CurrentFDs()
 	}
 }

metrics/multilabelmap.go

@@ -61,7 +61,7 @@ func labelString(k any) string {
 	var sb strings.Builder
 	sb.WriteString("{")
 
-	for i := 0; i < t.NumField(); i++ {
+	for i := range t.NumField() {
 		if i > 0 {
 			sb.WriteString(",")
 		}

net/art/stride_table_test.go

@@ -18,7 +18,7 @@
 
 func TestInversePrefix(t *testing.T) {
 	t.Parallel()
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		for len := 0; len < 9; len++ {
 			addr := i & (0xFF << (8 - len))
 			idx := prefixIndex(uint8(addr), len)
@@ -32,7 +32,7 @@ func TestInversePrefix(t *testing.T) {
 
 func TestHostIndex(t *testing.T) {
 	t.Parallel()
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		got := hostIndex(uint8(i))
 		want := prefixIndex(uint8(i), 8)
 		if got != want {
@@ -63,7 +63,7 @@ func TestStrideTableInsert(t *testing.T) {
 		}
 	}
 
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		addr := uint8(i)
 		slowVal, slowOK := slow.get(addr)
 		fastVal, fastOK := fast.get(addr)
@@ -103,7 +103,7 @@ func TestStrideTableInsertShuffled(t *testing.T) {
 
 	// Order of insertion should not affect the final shape of the stride table.
 	routes2 := append([]slowEntry[int](nil), routes...) // dup so we can print both slices on fail
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		rand.Shuffle(len(routes2), func(i, j int) { routes2[i], routes2[j] = routes2[j], routes2[i] })
 		rt2 := strideTable[int]{}
 		for _, route := range routes2 {
@@ -152,7 +152,7 @@ func TestStrideTableDelete(t *testing.T) {
 		t.Fatalf("slowTable has %d entries after deletes, want 50", cnt)
 	}
 
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		addr := uint8(i)
 		slowVal, slowOK := slow.get(addr)
 		fastVal, fastOK := fast.get(addr)
@@ -188,7 +188,7 @@ func TestStrideTableDeleteShuffle(t *testing.T) {
 
 	// Order of deletion should not affect the final shape of the stride table.
 	toDelete2 := append([]slowEntry[int](nil), toDelete...) // dup so we can print both slices on fail
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		rand.Shuffle(len(toDelete2), func(i, j int) { toDelete2[i], toDelete2[j] = toDelete2[j], toDelete2[i] })
 		rt2 := strideTable[int]{}
 		for _, route := range routes {
@@ -262,7 +262,7 @@ func forStrideCountAndOrdering(b *testing.B, fn func(b *testing.B, routes []slow
 func BenchmarkStrideTableInsertion(b *testing.B) {
 	forStrideCountAndOrdering(b, func(b *testing.B, routes []slowEntry[int]) {
 		val := 0
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			var rt strideTable[int]
 			for _, route := range routes {
 				rt.insert(route.addr, route.len, val)
@@ -285,7 +285,7 @@ func BenchmarkStrideTableDeletion(b *testing.B) {
 		}
 
 		b.ResetTimer()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			rt2 := rt
 			for _, route := range routes {
 				rt2.delete(route.addr, route.len)
@@ -311,7 +311,7 @@ func BenchmarkStrideTableGet(b *testing.B) {
 	}
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for i := range b.N {
 		writeSink, _ = rt.get(uint8(i))
 	}
 	gets := float64(b.N)

net/art/table_test.go

@@ -594,7 +594,7 @@ func TestInsertCompare(t *testing.T) {
 
 	seenVals4 := map[int]bool{}
 	seenVals6 := map[int]bool{}
-	for i := 0; i < 10_000; i++ {
+	for range 10_000 {
 		a := randomAddr()
 		slowVal, slowOK := slow.get(a)
 		fastVal, fastOK := fast.Get(a)
@@ -644,12 +644,12 @@ func TestInsertShuffled(t *testing.T) {
 		}
 	}()
 
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		pfxs2 := append([]slowPrefixEntry[int](nil), pfxs...)
 		rand.Shuffle(len(pfxs2), func(i, j int) { pfxs2[i], pfxs2[j] = pfxs2[j], pfxs2[i] })
 
 		addrs := make([]netip.Addr, 0, 10_000)
-		for i := 0; i < 10_000; i++ {
+		for range 10_000 {
 			addrs = append(addrs, randomAddr())
 		}
 
@@ -723,7 +723,7 @@ func TestDeleteCompare(t *testing.T) {
 
 	seenVals4 := map[int]bool{}
 	seenVals6 := map[int]bool{}
-	for i := 0; i < numProbes; i++ {
+	for range numProbes {
 		a := randomAddr()
 		slowVal, slowOK := slow.get(a)
 		fastVal, fastOK := fast.Get(a)
@@ -789,7 +789,7 @@ func TestDeleteShuffled(t *testing.T) {
 		rt.Delete(pfx.pfx)
 	}
 
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		pfxs2 := append([]slowPrefixEntry[int](nil), pfxs...)
 		toDelete2 := append([]slowPrefixEntry[int](nil), toDelete...)
 		rand.Shuffle(len(toDelete2), func(i, j int) { toDelete2[i], toDelete2[j] = toDelete2[j], toDelete2[i] })
@@ -806,7 +806,7 @@ func TestDeleteShuffled(t *testing.T) {
 
 		// Diffing a deep tree of tables gives cmp.Diff a nervous breakdown, so
 		// test for equivalence statistically with random probes instead.
-		for i := 0; i < numProbes; i++ {
+		for range numProbes {
 			a := randomAddr()
 			val1, ok1 := rt.Get(a)
 			val2, ok2 := rt2.Get(a)
@@ -909,7 +909,7 @@ func BenchmarkTableInsertion(b *testing.B) {
 		var startMem, endMem runtime.MemStats
 		runtime.ReadMemStats(&startMem)
 		b.StartTimer()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			var rt Table[int]
 			for _, route := range routes {
 				rt.Insert(route.pfx, route.val)
@@ -944,7 +944,7 @@ func BenchmarkTableDelete(b *testing.B) {
 
 		var t runningTimer
 		allocs, bytes := getMemCost(func() {
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				var rt Table[int]
 				for _, route := range routes {
 					rt.Insert(route.pfx, route.val)
@@ -983,7 +983,7 @@ func BenchmarkTableGet(b *testing.B) {
 			// cost is 16 bytes - presumably due to some amortized costs in
 			// the memory allocator? Either way, empirically 100 iterations
 			// reliably reports the correct cost.
-			for i := 0; i < 100; i++ {
+			for range 100 {
 				_ = genAddr()
 			}
 		})
@@ -991,7 +991,7 @@ func BenchmarkTableGet(b *testing.B) {
 		addrBytes /= 100
 		var t runningTimer
 		allocs, bytes := getMemCost(func() {
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				addr := genAddr()
 				t.Start()
 				writeSink, _ = rt.Get(addr)

net/connstats/stats_test.go

@@ -169,7 +169,7 @@ func Benchmark(b *testing.B) {
 		p := testPacketV4(ipproto.UDP, [4]byte{192, 168, 0, 1}, [4]byte{192, 168, 0, 2}, 123, 456, 789)
 		b.ResetTimer()
 		b.ReportAllocs()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			s := NewStatistics(0, 0, nil)
 			for j := 0; j < 1e3; j++ {
 				s.UpdateTxVirtual(p)
@@ -180,7 +180,7 @@ func Benchmark(b *testing.B) {
 		p := testPacketV4(ipproto.UDP, [4]byte{}, [4]byte{}, 0, 0, 789)
 		b.ResetTimer()
 		b.ReportAllocs()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			s := NewStatistics(0, 0, nil)
 			for j := 0; j < 1e3; j++ {
 				binary.BigEndian.PutUint32(p[20:], uint32(j)) // unique port combination
@@ -192,7 +192,7 @@ func Benchmark(b *testing.B) {
 		p := testPacketV4(ipproto.UDP, [4]byte{192, 168, 0, 1}, [4]byte{192, 168, 0, 2}, 123, 456, 789)
 		b.ResetTimer()
 		b.ReportAllocs()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			s := NewStatistics(0, 0, nil)
 			var group sync.WaitGroup
 			for j := 0; j < runtime.NumCPU(); j++ {
@@ -214,7 +214,7 @@ func Benchmark(b *testing.B) {
 		}
 		b.ResetTimer()
 		b.ReportAllocs()
-		for i := 0; i < b.N; i++ {
+		for range b.N {
 			s := NewStatistics(0, 0, nil)
 			var group sync.WaitGroup
 			for j := 0; j < runtime.NumCPU(); j++ {

net/dns/manager_tcp_test.go

@@ -115,7 +115,7 @@ func TestDNSOverTCP(t *testing.T) {
 	}
 
 	results := map[dnsname.FQDN]string{}
-	for i := 0; i < len(wantResults); i++ {
+	for range len(wantResults) {
 		var respLength uint16
 		if err := binary.Read(c, binary.BigEndian, &respLength); err != nil {
 			t.Fatalf("reading len: %v", err)

net/dns/manager_windows.go

@@ -198,7 +198,7 @@ func (m *windowsManager) setHosts(hosts []*HostEntry) error {
 
 	// This can fail spuriously with an access denied error, so retry it a
 	// few times.
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		if err = atomicfile.WriteFile(hostsFile, outB, fileMode); err == nil {
 			return nil
 		}

net/dns/recursive/recursive_test.go

@@ -613,7 +613,7 @@ func TestRecursionLimit(t *testing.T) {
 	// Fill out a CNAME chain equal to our recursion limit; we won't get
 	// this far since each CNAME is more than 1 level "deep", but this
 	// ensures that we have more than the limit.
-	for i := 0; i < maxDepth+1; i++ {
+	for i := range maxDepth + 1 {
 		curr := fmt.Sprintf("%d-tailscale.com.", i)
 
 		tailscaleNameservers := &dns.Msg{

net/dns/resolver/debug.go

@@ -67,7 +67,7 @@ func (fl *fwdLog) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	fmt.Fprintf(w, "<html><h1>DNS forwards</h1>")
 	now := time.Now()
-	for i := 0; i < len(fl.ent); i++ {
+	for i := range len(fl.ent) {
 		ent := fl.ent[(i+fl.pos)%len(fl.ent)]
 		if ent.Domain == "" {
 			continue

net/dns/resolver/forwarder_test.go

@@ -199,7 +199,7 @@ func BenchmarkNameFromQuery(b *testing.B) {
 	}
 	b.ResetTimer()
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		_, err := nameFromQuery(msg)
 		if err != nil {
 			b.Fatal(err)
@@ -413,7 +413,7 @@ func makeLargeResponse(tb testing.TB, domain string) (request, response []byte)
 		Class: dns.ClassINET,
 	})
 	builder.StartAnswers()
-	for i := 0; i < 120; i++ {
+	for i := range 120 {
 		builder.AResource(dns.ResourceHeader{
 			Name:  name,
 			Class: dns.ClassINET,

net/dns/resolver/tsdns_test.go

@@ -976,7 +976,7 @@ func BenchmarkFull(b *testing.B) {
 	for _, tt := range tests {
 		b.Run(tt.name, func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				syncRespond(r, tt.request)
 			}
 		})

net/interfaces/interfaces_darwin_test.go

@@ -103,7 +103,7 @@ func likelyHomeRouterIPDarwinExec() (ret netip.Addr, netif string, ok bool) {
 
 func TestFetchRoutingTable(t *testing.T) {
 	// Issue 1345: this used to be flaky on darwin.
-	for i := 0; i < 20; i++ {
+	for range 20 {
 		_, err := fetchRoutingTable()
 		if err != nil {
 			t.Fatal(err)

net/interfaces/interfaces_linux_test.go

@@ -97,7 +97,7 @@ func TestAwsAppRunnerDefaultRouteInterface(t *testing.T) {
 
 func BenchmarkDefaultRouteInterface(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		if _, err := DefaultRouteInterface(); err != nil {
 			b.Fatal(err)
 		}

net/interfaces/interfaces_windows_test.go

@@ -7,7 +7,7 @@
 
 func BenchmarkGetPACWindows(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for i := range b.N {
 		v := getPACWindows()
 		if i == 0 {
 			b.Logf("Got: %q", v)

net/packet/packet_test.go

@@ -512,7 +512,7 @@ func BenchmarkDecode(b *testing.B) {
 	for _, bench := range benches {
 		b.Run(bench.name, func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				var p Parsed
 				p.Decode(bench.buf)
 			}
@@ -624,7 +624,7 @@ func BenchmarkString(b *testing.B) {
 			var p Parsed
 			p.Decode(bench.buf)
 			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				sinkString = p.String()
 			}
 		})

net/portmapper/portmapper_test.go

@@ -21,7 +21,7 @@ func TestCreateOrGetMapping(t *testing.T) {
 	c := NewClient(t.Logf, nil, nil, new(controlknobs.Knobs), nil)
 	defer c.Close()
 	c.SetLocalPort(1234)
-	for i := 0; i < 2; i++ {
+	for i := range 2 {
 		if i > 0 {
 			time.Sleep(100 * time.Millisecond)
 		}
@@ -36,7 +36,7 @@ func TestClientProbe(t *testing.T) {
 	}
 	c := NewClient(t.Logf, nil, nil, new(controlknobs.Knobs), nil)
 	defer c.Close()
-	for i := 0; i < 3; i++ {
+	for i := range 3 {
 		if i > 0 {
 			time.Sleep(100 * time.Millisecond)
 		}

net/portmapper/upnp_test.go

@@ -597,7 +597,7 @@ func TestGetUPnPPortMapping(t *testing.T) {
 			firstResponse netip.AddrPort
 			prevPort      uint16
 		)
-		for i := 0; i < 2; i++ {
+		for i := range 2 {
 			sawRequestWithLease.Store(false)
 			res, err := c.Probe(ctx)
 			if err != nil {

net/sockstats/sockstats_tsgo_test.go

@@ -62,7 +62,7 @@ func(tt *testTime, rm *radioMonitor) {
 			"400 iterations: 2 sec active, 1 min idle",
 			func(tt *testTime, rm *radioMonitor) {
 				// 400 iterations to ensure values loop back around rm.usage array
-				for i := 0; i < 400; i++ {
+				for range 400 {
 					rm.active()
 					tt.Add(1 * time.Second)
 					rm.active()

net/stunserver/stunserver_test.go

@@ -76,7 +76,7 @@ func BenchmarkServerSTUN(b *testing.B) {
 
 	tx := stun.NewTxID()
 	req := stun.Request(tx)
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		if _, err := cc.WriteToUDP(req, addr); err != nil {
 			b.Fatal(err)
 		}

net/tcpinfo/tcpinfo_test.go

@@ -45,7 +45,7 @@ func TestRTT(t *testing.T) {
 	// Write a bunch of data to the conn to force TCP session establishment
 	// and a few packets.
 	junkData := bytes.Repeat([]byte("hello world\n"), 1024*1024)
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		if _, err := conn.Write(junkData); err != nil {
 			t.Fatalf("error writing junk data [%d]: %v", i, err)
 		}

net/tsaddr/tsaddr_test.go

@@ -99,7 +99,7 @@ func TestNewContainsIPFunc(t *testing.T) {
 
 func BenchmarkTailscaleServiceAddr(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sinkIP = TailscaleServiceIP()
 	}
 }

net/tshttpproxy/tshttpproxy_test.go

@@ -64,7 +64,7 @@ func TestProxyFromEnvironment_setNoProxyUntil(t *testing.T) {
 	os.Setenv("HTTPS_PROXY", fakeProxyEnv)
 
 	req := &http.Request{URL: must.Get(url.Parse("https://example.com/"))}
-	for i := 0; i < 3; i++ {
+	for i := range 3 {
 		switch i {
 		case 1:
 			setNoProxyUntil(time.Minute)

net/tstun/wrap_test.go

@@ -222,7 +222,7 @@ func TestReadAndInject(t *testing.T) {
 	var seen = make(map[string]bool)
 	sizes := make([]int, 1)
 	// We expect the same packets back, in no particular order.
-	for i := 0; i < len(written)+len(injected); i++ {
+	for i := range len(written) + len(injected) {
 		packet := buf[:]
 		buffs := [][]byte{packet}
 		numPackets, err := tun.Read(buffs, sizes, 0)
@@ -283,7 +283,7 @@ func TestWriteAndInject(t *testing.T) {
 
 	seen := make(map[string]bool)
 	// We expect the same packets back, in no particular order.
-	for i := 0; i < len(written)+len(injected); i++ {
+	for i := range len(written) + len(injected) {
 		packet := <-chtun.Inbound
 		got := string(packet)
 		t.Logf("read %d: got %s", i, got)
@@ -470,7 +470,7 @@ func BenchmarkWrite(b *testing.B) {
 	defer tun.Close()
 
 	packet := [][]byte{udp4("5.6.7.8", "1.2.3.4", 89, 89)}
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		_, err := ftun.Write(packet, 0)
 		if err != nil {
 			b.Errorf("err = %v; want nil", err)
@@ -902,7 +902,7 @@ type captureRecord struct {
 			pkt:  []byte("InjectOutboundPacketBuffer"),
 		},
 	}
-	for i := 0; i < len(want); i++ {
+	for i := range len(want) {
 		want[i].now = now
 	}
 	if !reflect.DeepEqual(captured, want) {

paths/paths_unix.go

@@ -45,7 +45,7 @@ func stateFileUnix() string {
 	}
 
 	try := path
-	for i := 0; i < 3; i++ { // check writability of the file, /var/lib/tailscale, and /var/lib
+	for range 3 { // check writability of the file, /var/lib/tailscale, and /var/lib
 		err := unix.Access(try, unix.O_RDWR)
 		if err == nil {
 			return path

portlist/portlist_linux_test.go

@@ -114,7 +114,7 @@ func BenchmarkParsePorts(b *testing.B) {
    1: 00000000000000000000000000000000:1F91 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000  1000        0 142240557 1 0000000000000000 100 0 0 10 0
    2: 00000000000000000000000000000000:0016 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 34064 1 0000000000000000 100 0 0 10 0
 `)
-	for i := 0; i < 50000; i++ {
+	for range 50000 {
 		contents.WriteString("   3: 69050120005716BC64906EBE009ECD4D:D506 0047062600000000000000006E171268:01BB 01 00000000:00000000 02:0000009E 00000000  1000        0 151042856 2 0000000000000000 21 4 28 10 -1\n")
 	}
 
@@ -123,7 +123,7 @@ func BenchmarkParsePorts(b *testing.B) {
 	r := bytes.NewReader(contents.Bytes())
 	br := bufio.NewReader(&contents)
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		r.Seek(0, io.SeekStart)
 		br.Reset(r)
 		err := li.parseProcNetFile(br, "tcp6")
@@ -142,7 +142,7 @@ func BenchmarkFindProcessNames(b *testing.B) {
 	need := map[string]*portMeta{
 		"something-we'll-never-find": new(portMeta),
 	}
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		if err := li.findProcessNames(need); err != nil {
 			b.Fatal(err)
 		}

portlist/portlist_test.go

@@ -205,7 +205,7 @@ func benchmarkGetList(b *testing.B, incremental bool) {
 		b.Skip(p.initErr)
 	}
 	b.Cleanup(func() { p.Close() })
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		pl, err := p.getList()
 		if err != nil {
 			b.Fatal(err)

prober/derp_test.go

@@ -186,7 +186,7 @@ func Test_packetsForSize(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			hashes := make(map[string]int)
-			for i := 0; i < 5; i++ {
+			for range 5 {
 				pkts := packetsForSize(int64(tt.size))
 				if len(pkts) != tt.wantPackets {
 					t.Errorf("packetsForSize(%d) got %d packets, want %d", tt.size, len(pkts), tt.wantPackets)

prober/prober_test.go

@@ -155,7 +155,7 @@ func TestProberRun(t *testing.T) {
 	const startingProbes = 100
 	var probes []*Probe
 
-	for i := 0; i < startingProbes; i++ {
+	for i := range startingProbes {
 		probes = append(probes, p.Run(fmt.Sprintf("probe%d", i), probeInterval, nil, FuncProbe(func(context.Context) error {
 			mu.Lock()
 			defer mu.Unlock()

safesocket/basic_test.go

@@ -76,7 +76,7 @@ func TestBasics(t *testing.T) {
 		errs <- nil
 	}()
 
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		if err := <-errs; err != nil {
 			t.Fatal(err)
 		}

safesocket/pipe_windows_test.go

@@ -99,7 +99,7 @@ func TestExpectedWindowsTypes(t *testing.T) {
 		errs <- nil
 	}()
 
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		if err := <-errs; err != nil {
 			t.Fatal(err)
 		}

smallzstd/zstd_test.go

@@ -54,7 +54,7 @@ func benchEncoder(b *testing.B, mk func() (*zstd.Encoder, error)) {
 	}
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		e.EncodeAll(in, out)
 	}
 }
@@ -66,7 +66,7 @@ func benchEncoderWithConstruction(b *testing.B, mk func() (*zstd.Encoder, error)
 	out := make([]byte, 0, 10<<10) // 10kiB
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		e, err := mk()
 		if err != nil {
 			b.Fatalf("making encoder: %v", err)
@@ -88,7 +88,7 @@ func benchDecoder(b *testing.B, mk func() (*zstd.Decoder, error)) {
 	}
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		d.DecodeAll(in, out)
 	}
 }
@@ -100,7 +100,7 @@ func benchDecoderWithConstruction(b *testing.B, mk func() (*zstd.Decoder, error)
 	out := make([]byte, 0, 10<<10)
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		d, err := mk()
 		if err != nil {
 			b.Fatalf("creating decoder: %v", err)

ssh/tailssh/tailssh_test.go

@@ -1016,7 +1016,7 @@ func TestPublicKeyFetching(t *testing.T) {
 		pubKeyHTTPClient: ts.Client(),
 		timeNow:          clock.Now,
 	}
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		got, err := srv.fetchPublicKeysURL(keys + "/alice.keys")
 		if err != nil {
 			t.Fatal(err)

syncs/syncs_test.go

@@ -45,7 +45,7 @@ func TestWaitGroupChan(t *testing.T) {
 
 func TestClosedChan(t *testing.T) {
 	ch := ClosedChan()
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		select {
 		case <-ch:
 		default:

tailcfg/tailcfg_test.go

@@ -23,7 +23,7 @@
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
-	for i := 0; i < t.NumField(); i++ {
+	for i := range t.NumField() {
 		fields = append(fields, t.Field(i).Name)
 	}
 	return

tempfork/heap/heap_test.go

@@ -118,7 +118,7 @@ func Test(t *testing.T) {
 
 func TestRemove0(t *testing.T) {
 	h := new(myHeap[int])
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		h.Push(i)
 	}
 	h.verify(t, 0)
@@ -135,7 +135,7 @@ func TestRemove0(t *testing.T) {
 
 func TestRemove1(t *testing.T) {
 	h := new(myHeap[int])
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		h.Push(i)
 	}
 	h.verify(t, 0)
@@ -153,7 +153,7 @@ func TestRemove2(t *testing.T) {
 	N := 10
 
 	h := new(myHeap[int])
-	for i := 0; i < N; i++ {
+	for i := range N {
 		h.Push(i)
 	}
 	h.verify(t, 0)
@@ -167,7 +167,7 @@ func TestRemove2(t *testing.T) {
 	if len(m) != N {
 		t.Errorf("len(m) = %d; want %d", len(m), N)
 	}
-	for i := 0; i < len(m); i++ {
+	for i := range len(m) {
 		if !m[i] {
 			t.Errorf("m[%d] doesn't exist", i)
 		}
@@ -177,7 +177,7 @@ func TestRemove2(t *testing.T) {
 func BenchmarkDup(b *testing.B) {
 	const n = 10000
 	h := make(myHeap[int], 0, n)
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		for j := 0; j < n; j++ {
 			Push[int](&h, 0) // all elements are the same
 		}

tka/chaintest_test.go

@@ -209,7 +209,7 @@ func (c *testChain) buildChain() {
 	// in O(n+1) where n is the number of AUMs.
 	c.AUMs = make(map[string]AUM, len(c.Nodes))
 	c.AUMHashes = make(map[string]AUMHash, len(c.Nodes))
-	for i := 0; i < len(c.Nodes)+1; i++ {
+	for range len(c.Nodes) + 1 {
 		if len(pending) == 0 {
 			return
 		}

tka/sig_test.go

@@ -143,7 +143,7 @@ func TestSigNested_DeepNesting(t *testing.T) {
 
 	outer := nestedSig
 	var lastNodeKey key.NodePrivate
-	for i := 0; i < 15; i++ { // 15 = max nesting level for CBOR
+	for range 15 { // 15 = max nesting level for CBOR
 		lastNodeKey = key.NewNode()
 		nodeKeyPub, _ := lastNodeKey.Public().MarshalBinary()
 

tka/sync.go

@@ -142,7 +142,7 @@ func computeSyncIntersection(storage Chonk, localOffer, remoteOffer SyncOffer) (
 
 	if hasRemoteHead {
 		curs := localOffer.Head
-		for i := 0; i < maxSyncHeadIntersectionIter; i++ {
+		for range maxSyncHeadIntersectionIter {
 			parent, err := storage.AUM(curs)
 			if err != nil {
 				if err != os.ErrNotExist {

tka/tailchonk.go

@@ -587,7 +587,7 @@ func markActiveChain(storage Chonk, verdict map[AUMHash]retainState, minChain in
 		return AUMHash{}, err
 	}
 
-	for i := 0; i < minChain; i++ {
+	for i := range minChain {
 		h := next.Hash()
 		verdict[h] |= retainStateActive
 

tka/tka.go

@@ -213,7 +213,7 @@ func fastForwardWithAdvancer(
 
 	curs := nextAUM
 	state := startState
-	for i := 0; i < maxIter; i++ {
+	for range maxIter {
 		if done != nil && done(curs, state) {
 			return curs, state, nil
 		}

tsnet/tsnet_test.go

@@ -730,7 +730,7 @@ func TestCapturePcap(t *testing.T) {
 	const pcapHeaderSize = 24
 
 	// there is a lag before the io.Copy writes a packet to the pcap files
-	for i := 0; i < (timeLimit * 10); i++ {
+	for range timeLimit * 10 {
 		time.Sleep(100 * time.Millisecond)
 		if (fileSize(s1Pcap) > pcapHeaderSize) && (fileSize(s2Pcap) > pcapHeaderSize) {
 			break

tstest/clock_test.go

@@ -153,7 +153,7 @@ func TestZeroInitClock(t *testing.T) {
 		t.Errorf("clock has step %v, want 0", step)
 	}
 
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		if got := clock.Now(); !got.Equal(start) {
 			t.Errorf("step %v: clock.Now() = %v, want %v", i, got, start)
 		}

tstest/integration/vms/vm_setup_test.go

@@ -50,7 +50,7 @@ func (vm *vmInstance) running() bool {
 
 func (vm *vmInstance) waitStartup(t *testing.T) {
 	t.Helper()
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		if vm.running() {
 			break
 		}

tstest/integration/vms/vms_steps_test.go

@@ -23,7 +23,7 @@ func retry(t *testing.T, fn func() error) {
 	t.Helper()
 	const tries = 3
 	var err error
-	for i := 0; i < tries; i++ {
+	for i := range tries {
 		err = fn()
 		if err != nil {
 			t.Logf("%dth invocation failed, trying again: %v", i, err)

tstest/integration/vms/vms_test.go

@@ -321,7 +321,7 @@ func (h *Harness) setupSSHShell(t *testing.T, d Distro, ipm ipMapping) (*ssh.Cli
 	// don't use socket activation.
 	const maxRetries = 5
 	var working bool
-	for i := 0; i < maxRetries; i++ {
+	for range maxRetries {
 		cli, err := ssh.Dial("tcp", hostport, ccfg)
 		if err == nil {
 			working = true

tstest/natlab/natlab_test.go

@@ -17,7 +17,7 @@
 func TestAllocIPs(t *testing.T) {
 	n := NewInternet()
 	saw := map[netip.Addr]bool{}
-	for i := 0; i < 255; i++ {
+	for range 255 {
 		for _, f := range []func(*Interface) netip.Addr{n.allocIPv4, n.allocIPv6} {
 			ip := f(nil)
 			if saw[ip] {

tstest/resource.go

@@ -33,7 +33,7 @@ func ResourceCheck(tb testing.TB) {
 			return
 		}
 		// Goroutines might be still exiting.
-		for i := 0; i < 300; i++ {
+		for range 300 {
 			if runtime.NumGoroutine() <= startN {
 				return
 			}

tstime/jitter_test.go

@@ -14,7 +14,7 @@ func TestRandomDurationBetween(t *testing.T) {
 	}
 	const min = 1 * time.Second
 	const max = 10 * time.Second
-	for i := 0; i < 500; i++ {
+	for range 500 {
 		if got := RandomDurationBetween(min, max); got < min || got >= max {
 			t.Fatalf("%v (%d) out of range", got, got)
 		}

tstime/mono/mono_test.go

@@ -50,14 +50,14 @@ func TestJSONRoundtrip(t *testing.T) {
 
 func BenchmarkMonoNow(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		Now()
 	}
 }
 
 func BenchmarkTimeNow(b *testing.B) {
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		time.Now()
 	}
 }

tstime/rate/rate_test.go

@@ -7,8 +7,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.7
-
 package rate
 
 import (
@@ -138,7 +136,7 @@ func TestSimultaneousRequests(t *testing.T) {
 	}
 
 	wg.Add(numRequests)
-	for i := 0; i < numRequests; i++ {
+	for range numRequests {
 		go f()
 	}
 	wg.Wait()

tstime/rate/value_test.go

@@ -43,7 +43,7 @@ func TestValue(t *testing.T) {
 		c := qt.New(t)
 		var v Value
 		var now mono.Time
-		for i := 0; i < numStep; i++ {
+		for range numStep {
 			v.addNow(now, float64(step))
 			now += step
 		}
@@ -232,7 +232,7 @@ func stats(fs []float64) (mean, stddev float64) {
 func BenchmarkValue(b *testing.B) {
 	b.ReportAllocs()
 	v := Value{HalfLife: time.Second}
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		v.Add(1)
 	}
 }

tsweb/tsweb_test.go

@@ -521,7 +521,7 @@ func BenchmarkLogNot200(b *testing.B) {
 	h := StdHandler(rh, HandlerOptions{QuietLoggingIfSuccessful: true})
 	req := httptest.NewRequest("GET", "/", nil)
 	rw := new(httptest.ResponseRecorder)
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		*rw = httptest.ResponseRecorder{}
 		h.ServeHTTP(rw, req)
 	}
@@ -536,7 +536,7 @@ func BenchmarkLog(b *testing.B) {
 	h := StdHandler(rh, HandlerOptions{})
 	req := httptest.NewRequest("GET", "/", nil)
 	rw := new(httptest.ResponseRecorder)
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		*rw = httptest.ResponseRecorder{}
 		h.ServeHTTP(rw, req)
 	}

types/ipproto/ipproto_test.go

@@ -49,7 +49,7 @@ func TestAcceptedNamesContainsPreferredNames(t *testing.T) {
 }
 
 func TestProtoTextEncodingRoundTrip(t *testing.T) {
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		text := must.Get(Proto(i).MarshalText())
 		var p Proto
 		must.Do(p.UnmarshalText(text))
@@ -67,7 +67,7 @@ func TestProtoUnmarshalText(t *testing.T) {
 		t.Fatalf("empty input, got err=%v, p=%v, want nil, 0", err, p)
 	}
 
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		var p Proto
 		must.Do(p.UnmarshalText([]byte(fmt.Sprintf("%d", i))))
 		if got, want := p, Proto(i); got != want {
@@ -93,7 +93,7 @@ func TestProtoUnmarshalText(t *testing.T) {
 }
 
 func TestProtoMarshalText(t *testing.T) {
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		text := must.Get(Proto(i).MarshalText())
 
 		if wantName, ok := preferredNames[Proto(i)]; ok {
@@ -110,7 +110,7 @@ func TestProtoMarshalText(t *testing.T) {
 }
 
 func TestProtoMarshalJSON(t *testing.T) {
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		j := must.Get(Proto(i).MarshalJSON())
 		if got, want := string(j), fmt.Sprintf(`%d`, i); got != want {
 			t.Errorf("Proto(%d).MarshalJSON() = %q, want %q", i, got, want)
@@ -121,7 +121,7 @@ func TestProtoMarshalJSON(t *testing.T) {
 func TestProtoUnmarshalJSON(t *testing.T) {
 	var p Proto
 
-	for i := 0; i < 256; i++ {
+	for i := range 256 {
 		j := []byte(fmt.Sprintf(`%d`, i))
 		must.Do(json.Unmarshal(j, &p))
 		if got, want := p, Proto(i); got != want {

types/key/node_test.go

@@ -162,7 +162,7 @@ func TestChallenge(t *testing.T) {
 func TestShard(t *testing.T) {
 	const N = 1_000
 	var shardCount [256]int
-	for i := 0; i < N; i++ {
+	for range N {
 		shardCount[NewNode().Public().Shard()]++
 	}
 	e := float64(N) / 256 // expected

types/key/util_test.go

@@ -22,7 +22,7 @@ func TestRand(t *testing.T) {
 }
 
 func TestClamp25519Private(t *testing.T) {
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		var k [32]byte
 		rand(k[:])
 		clamp25519Private(k[:])

types/lazy/sync_test.go

@@ -89,7 +89,7 @@ func TestSyncValueConcurrent(t *testing.T) {
 		routines = 10000
 	)
 	wg.Add(routines)
-	for i := 0; i < routines; i++ {
+	for range routines {
 		go func() {
 			defer wg.Done()
 			// Every goroutine waits for the go signal, so that more of them

types/logger/logger_test.go

@@ -70,7 +70,7 @@ func TestRateLimiter(t *testing.T) {
 	lgtest := logTester(want, t, &testsRun)
 	lg := RateLimitedFnWithClock(lgtest, 1*time.Minute, 2, 50, nowf)
 	var prefixed Logf
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		lg("boring string with constant formatting %s", "(constant)")
 		lg("templated format string no. %d", i)
 		if i == 4 {
@@ -121,7 +121,7 @@ func TestLogOnChange(t *testing.T) {
 	lgtest := logTester(want, t, &testsRun)
 	lg := LogOnChange(lgtest, 5*time.Second, timeNow)
 
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		lg("%s", "1 2 3 4 5 6")
 	}
 	lg("1 2 3 4 5 7")

types/netmap/netmap.go

@@ -137,7 +137,7 @@ func (nm *NetworkMap) PeerByTailscaleIP(ip netip.Addr) (peer tailcfg.NodeView, o
 	}
 	for _, n := range nm.Peers {
 		ad := n.Addresses()
-		for i := 0; i < ad.Len(); i++ {
+		for i := range ad.Len() {
 			a := ad.At(i)
 			if a.Addr() == ip {
 				return n, true

types/netmap/nodemut.go

@@ -73,7 +73,7 @@ func (m NodeMutationLastSeen) Apply(n *tailcfg.Node) {
 var peerChangeFields = sync.OnceValue(func() []reflect.StructField {
 	var fields []reflect.StructField
 	rt := reflect.TypeFor[tailcfg.PeerChange]()
-	for i := 0; i < rt.NumField(); i++ {
+	for i := range rt.NumField() {
 		fields = append(fields, rt.Field(i))
 	}
 	return fields

types/netmap/nodemut_test.go

@@ -44,7 +44,7 @@ func TestMapResponseContainsNonPatchFields(t *testing.T) {
 	}
 
 	rt := reflect.TypeFor[tailcfg.MapResponse]()
-	for i := 0; i < rt.NumField(); i++ {
+	for i := range rt.NumField() {
 		f := rt.Field(i)
 
 		var want bool

types/persist/persist_test.go

@@ -12,7 +12,7 @@
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
-	for i := 0; i < t.NumField(); i++ {
+	for i := range t.NumField() {
 		if name := t.Field(i).Name; name != "_" {
 			fields = append(fields, name)
 		}

types/views/views.go

@@ -262,7 +262,7 @@ func (v Slice[T]) AsSlice() []T {
 //
 // As it runs in O(n) time, use with care.
 func (v Slice[T]) IndexFunc(f func(T) bool) int {
-	for i := 0; i < v.Len(); i++ {
+	for i := range v.Len() {
 		if f(v.At(i)) {
 			return i
 		}