lint: enable intrange linter (#7331)

Enable intrange linter to enforce modern Go range syntax over
traditional for loops, by converting:

for i := 0; i < n; i++

to:

for i := range n

Adding type conversions where needed for compatibility
with existing uint64 parameters.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

.golangci.yml

@@ -6,6 +6,7 @@ linters:
     - copyloopvar
     - govet
     - ineffassign
+    - intrange
     - staticcheck
     - unconvert
     - unused

core/dnsserver/server_test.go

@@ -116,7 +116,7 @@ func BenchmarkCoreServeDNS(b *testing.B) {
 
 	b.ReportAllocs()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		s.ServeDNS(ctx, w, m)
 	}
 }

plugin/azure/setup.go

@@ -73,7 +73,7 @@ func parse(c *caddy.Controller) (auth.EnvironmentSettings, map[string][]string,
 	for c.Next() {
 		args := c.RemainingArgs()
 
-		for i := 0; i < len(args); i++ {
+		for i := range args {
 			parts := strings.SplitN(args[i], ":", 2)
 			if len(parts) != 2 {
 				return env, resourceGroupMapping, accessMap, fall, c.Errf("invalid resource group/zone: %q", args[i])

plugin/cache/cache_test.go

@@ -603,7 +603,7 @@ func BenchmarkCacheResponse(b *testing.B) {
 	b.StartTimer()
 
 	j := 0
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		req := reqs[j]
 		c.ServeDNS(ctx, &test.ResponseWriter{}, req)
 		j = (j + 1) % 5

plugin/clouddns/clouddns.go

@@ -211,7 +211,7 @@ func (h *CloudDNS) updateZones(ctx context.Context) error {
 	// Collect errors (if any). This will also sync on all zones updates
 	// completion.
 	var errs []string
-	for i := 0; i < len(h.zones); i++ {
+	for range len(h.zones) {
 		err := <-errc
 		if err != nil {
 			errs = append(errs, err.Error())

plugin/clouddns/setup.go

@@ -43,7 +43,7 @@ func setup(c *caddy.Controller) error {
 
 		args := c.RemainingArgs()
 
-		for i := 0; i < len(args); i++ {
+		for i := range args {
 			parts := strings.SplitN(args[i], ":", 3)
 			if len(parts) != 3 {
 				return plugin.Error("clouddns", c.Errf("invalid zone %q", args[i]))

plugin/debug/pcap.go

@@ -57,7 +57,7 @@ func hexdump(data []byte) []byte {
 	b := new(bytes.Buffer)
 
 	newline := ""
-	for i := 0; i < len(data); i++ {
+	for i := range data {
 		if i%16 == 0 {
 			fmt.Fprintf(b, "%s%s%06x", newline, prefix, i)
 			newline = "\n"

plugin/dnstap/io_test.go

@@ -30,7 +30,7 @@ func accept(t *testing.T, l net.Listener, count int) {
 		t.Fatalf("Server decoder: %s", err)
 	}
 
-	for i := 0; i < count; i++ {
+	for range count {
 		if _, err := dec.Decode(); err != nil {
 			t.Errorf("Server decode: %s", err)
 		}
@@ -96,7 +96,7 @@ func TestRace(t *testing.T) {
 	defer dio.close()
 
 	wg.Add(count)
-	for i := 0; i < count; i++ {
+	for range count {
 		go func() {
 			tmsg := tap.Dnstap_MESSAGE
 			dio.Dnstap(&tap.Dnstap{Type: &tmsg})
@@ -147,7 +147,7 @@ func TestReconnect(t *testing.T) {
 		wg.Done()
 	}()
 
-	for i := 0; i < count; i++ {
+	for range count {
 		time.Sleep(100 * time.Millisecond)
 		dio.Dnstap(&tmsg)
 	}

plugin/erratic/erratic.go

@@ -57,7 +57,7 @@ func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 		rr.Header().Name = state.QName()
 		m.Answer = append(m.Answer, &rr)
 		if e.large {
-			for i := 0; i < 29; i++ {
+			for range 29 {
 				m.Answer = append(m.Answer, &rr)
 			}
 		}

plugin/errors/benchmark_test.go

@@ -18,7 +18,7 @@ func BenchmarkServeDNS(b *testing.B) {
 	w := &test.ResponseWriter{}
 	ctx := context.TODO()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		_, err := h.ServeDNS(ctx, w, r)
 		if err != nil {
 			b.Errorf("ServeDNS returned error: %s", err)

plugin/etcd/msg/service.go

@@ -164,7 +164,7 @@ func split255(s string) []string {
 // targetStrip strips "targetstrip" labels from the left side of the fully qualified name.
 func targetStrip(name string, targetStrip int) string {
 	offset, end := 0, false
-	for i := 0; i < targetStrip; i++ {
+	for range targetStrip {
 		offset, end = dns.NextLabel(name, offset)
 	}
 	if end {

plugin/etcd/msg/service_test.go

@@ -8,7 +8,7 @@ func TestSplit255(t *testing.T) {
 		t.Errorf("Failure to split abc")
 	}
 	s := ""
-	for i := 0; i < 255; i++ {
+	for range 255 {
 		s += "a"
 	}
 	xs = split255(s)
@@ -20,7 +20,7 @@ func TestSplit255(t *testing.T) {
 	if len(xs) != 2 || xs[1] != "b" {
 		t.Errorf("Failure to split 256 char long string: %d", len(xs))
 	}
-	for i := 0; i < 255; i++ {
+	for range 255 {
 		s += "a"
 	}
 	xs = split255(s)

plugin/file/dnssec_test.go

@@ -169,7 +169,7 @@ func BenchmarkFileLookupDNSSEC(b *testing.B) {
 
 	b.ResetTimer()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		fm.ServeDNS(ctx, rec, m)
 	}
 }

plugin/file/file_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func BenchmarkFileParseInsert(b *testing.B) {
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		Parse(strings.NewReader(dbMiekENTNL), testzone, "stdin", 0)
 	}
 }

plugin/file/lookup_test.go

@@ -318,7 +318,7 @@ func BenchmarkFileLookup(b *testing.B) {
 
 	b.ResetTimer()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		fm.ServeDNS(ctx, rec, m)
 	}
 }

plugin/file/tree/less_test.go

@@ -63,7 +63,7 @@ Tests:
 		}
 
 		sort.Sort(set(test.in))
-		for i := 0; i < len(test.in); i++ {
+		for i := range len(test.in) {
 			if test.in[i] != test.out[i] {
 				t.Errorf("Test %d: expected %s, got %s", j, test.out[i], test.in[i])
 				n := ""

plugin/forward/setup.go

@@ -176,7 +176,7 @@ func parseBlock(c *caddy.Controller, f *Forward) error {
 		if len(ignore) == 0 {
 			return c.ArgErr()
 		}
-		for i := 0; i < len(ignore); i++ {
+		for i := range ignore {
 			f.ignored = append(f.ignored, plugin.Host(ignore[i]).NormalizeExact()...)
 		}
 	case "max_fails":

plugin/grpc/setup.go

@@ -103,7 +103,7 @@ func parseBlock(c *caddy.Controller, g *GRPC) error {
 		if len(ignore) == 0 {
 			return c.ArgErr()
 		}
-		for i := 0; i < len(ignore); i++ {
+		for i := range ignore {
 			g.ignored = append(g.ignored, plugin.Host(ignore[i]).NormalizeExact()...)
 		}
 	case "tls":

plugin/kubernetes/controller_test.go

@@ -70,7 +70,7 @@ func BenchmarkController(b *testing.B) {
 	m.SetQuestion("svc1.testns.svc.cluster.local.", dns.TypeA)
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		k.ServeDNS(ctx, rw, m)
 	}
 }

plugin/kubernetes/xfr.go

@@ -259,7 +259,7 @@ func emitAddressRecord(c chan<- []dns.RR, s msg.Service) string {
 func calcSRVWeight(numservices int) uint16 {
 	var services []msg.Service
 
-	for i := 0; i < numservices; i++ {
+	for range numservices {
 		services = append(services, msg.Service{})
 	}
 

plugin/loadbalance/loadbalance.go

@@ -72,7 +72,7 @@ func roundRobinShuffle(records []dns.RR) {
 			records[0], records[1] = records[1], records[0]
 		}
 	default:
-		for j := 0; j < l; j++ {
+		for j := range l {
 			p := j + (int(dns.Id()) % (l - j))
 			if j == p {
 				continue

plugin/log/log_test.go

@@ -274,7 +274,7 @@ func BenchmarkLogged(b *testing.B) {
 	rec := dnstest.NewRecorder(&test.ResponseWriter{})
 
 	b.StartTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		logger.ServeDNS(ctx, rec, r)
 	}
 }

plugin/pkg/cache/cache.go

@@ -38,7 +38,7 @@ func New(size int) *Cache {
 	c := &Cache{}
 
 	// Initialize all the shards
-	for i := 0; i < shardSize; i++ {
+	for i := range shardSize {
 		c.shards[i] = newShard(ssize)
 	}
 	return c

plugin/pkg/cache/cache_test.go

@@ -13,10 +13,10 @@ func TestCacheAddAndGet(t *testing.T) {
 		t.Fatal("Failed to find inserted record")
 	}
 
-	for i := 0; i < N; i++ {
+	for i := range N {
 		c.Add(uint64(i), 1)
 	}
-	for i := 0; i < N; i++ {
+	for i := range N {
 		c.Add(uint64(i), 1)
 		if c.Len() != N {
 			t.Fatal("A item was unnecessarily evicted from the cache")
@@ -45,7 +45,7 @@ func TestCacheLen(t *testing.T) {
 
 func TestCacheSharding(t *testing.T) {
 	c := New(shardSize)
-	for i := 0; i < shardSize*2; i++ {
+	for i := range shardSize * 2 {
 		c.Add(uint64(i), 1)
 	}
 	for i, s := range c.shards {
@@ -58,7 +58,7 @@ func TestCacheSharding(t *testing.T) {
 func TestCacheWalk(t *testing.T) {
 	c := New(10)
 	exp := make([]int, 10*2)
-	for i := 0; i < 10*2; i++ {
+	for i := range 10 * 2 {
 		c.Add(uint64(i), 1)
 		exp[i] = 1
 	}
@@ -78,7 +78,7 @@ func BenchmarkCache(b *testing.B) {
 	b.ReportAllocs()
 
 	c := New(4)
-	for n := 0; n < b.N; n++ {
+	for range b.N {
 		c.Add(1, 1)
 		c.Get(1)
 	}

plugin/pkg/cache/shard_test.go

@@ -26,11 +26,11 @@ func TestAddEvict(t *testing.T) {
 	const size = 1024
 	s := newShard(size)
 
-	for i := uint64(0); i < size; i++ {
-		s.Add(i, 1)
+	for i := range size {
+		s.Add(uint64(i), 1)
 	}
-	for i := uint64(0); i < size; i++ {
-		s.Add(i, 1)
+	for i := range size {
+		s.Add(uint64(i), 1)
 		if s.Len() != size {
 			t.Fatal("A item was unnecessarily evicted from the cache")
 		}
@@ -86,7 +86,7 @@ func TestShardLenEvict(t *testing.T) {
 
 	// Make sure we don't accidentally evict an element when
 	// we the key is already stored.
-	for i := 0; i < 4; i++ {
+	for range 4 {
 		s.Add(5, 1)
 		if l := s.Len(); l != 4 {
 			t.Fatalf("Shard size should %d, got %d", 4, l)
@@ -96,12 +96,12 @@ func TestShardLenEvict(t *testing.T) {
 
 func TestShardEvictParallel(t *testing.T) {
 	s := newShard(shardSize)
-	for i := uint64(0); i < shardSize; i++ {
-		s.Add(i, struct{}{})
+	for i := range shardSize {
+		s.Add(uint64(i), struct{}{})
 	}
 	start := make(chan struct{})
 	var wg sync.WaitGroup
-	for i := 0; i < shardSize; i++ {
+	for range shardSize {
 		wg.Add(1)
 		go func() {
 			<-start
@@ -119,7 +119,7 @@ func TestShardEvictParallel(t *testing.T) {
 func BenchmarkShard(b *testing.B) {
 	s := newShard(shardSize)
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for i := range b.N {
 		k := uint64(i) % shardSize * 2
 		s.Add(k, 1)
 		s.Get(k)

plugin/pkg/cidr/cidr.go

@@ -71,7 +71,7 @@ func Reverse(nets []string) []string {
 		nearest := (bits - ones) + mod
 		offset := 0
 		var end bool
-		for i := 0; i < nearest/sizeDigit; i++ {
+		for range nearest / sizeDigit {
 			offset, end = dns.NextLabel(r, offset)
 			if end {
 				break

plugin/pkg/dnstest/server.go

@@ -28,7 +28,7 @@ func NewServer(f dns.HandlerFunc) *Server {
 	s1 := &dns.Server{} // udp
 	s2 := &dns.Server{} // tcp
 
-	for i := 0; i < 5; i++ { // 5 attempts
+	for range 5 { // 5 attempts
 		s2.Listener, _ = reuseport.Listen("tcp", ":0")
 		if s2.Listener == nil {
 			continue

plugin/pkg/dnsutil/reverse.go

@@ -43,7 +43,7 @@ func IsReverse(name string) int {
 }
 
 func reverse(slice []string) string {
-	for i := 0; i < len(slice)/2; i++ {
+	for i := range len(slice) / 2 {
 		j := len(slice) - i - 1
 		slice[i], slice[j] = slice[j], slice[i]
 	}
@@ -58,12 +58,12 @@ func reverse(slice []string) string {
 // b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2
 // is reversed to 2001:db8::567:89ab
 func reverse6(slice []string) string {
-	for i := 0; i < len(slice)/2; i++ {
+	for i := range len(slice) / 2 {
 		j := len(slice) - i - 1
 		slice[i], slice[j] = slice[j], slice[i]
 	}
 	slice6 := []string{}
-	for i := 0; i < len(slice)/4; i++ {
+	for i := range len(slice) / 4 {
 		slice6 = append(slice6, strings.Join(slice[i*4:i*4+4], ""))
 	}
 	ip := net.ParseIP(strings.Join(slice6, ":")).To16()

plugin/pkg/dnsutil/ttl_test.go

@@ -63,7 +63,7 @@ func BenchmarkMinimalTTL(b *testing.B) {
 	mt, _ := response.Typify(m, utc)
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		dur := MinimalTTL(m, mt)
 		if dur != 1000*time.Second {
 			b.Fatalf("Wrong MinimalTTL %d, expected %d", dur, 1000*time.Second)

plugin/pkg/proxy/connect_test.go

@@ -242,7 +242,7 @@ func TestDial_MultipleCallsAfterStop(t *testing.T) {
 	tr.Stop()
 	time.Sleep(50 * time.Millisecond)
 
-	for i := 0; i < 3; i++ {
+	for i := range 3 {
 		_, _, err := tr.Dial("udp")
 		if err == nil {
 			t.Errorf("Attempt %d: %s: %s", i+1, testMsgExpectedError, testMsgUnexpectedNilError)

plugin/pkg/rand/rand_test.go

@@ -47,7 +47,7 @@ func TestIntDeterministic(t *testing.T) {
 	r2 := New(seed)
 
 	// They should produce the same sequence
-	for i := 0; i < 10; i++ {
+	for i := range 10 {
 		val1 := r1.Int()
 		val2 := r2.Int()
 		if val1 != val2 {
@@ -123,11 +123,11 @@ func TestConcurrentAccess(t *testing.T) {
 	errors := make(chan error, numGoroutines*numOperations)
 
 	// Test concurrent Int() calls
-	for i := 0; i < numGoroutines; i++ {
+	for range numGoroutines {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			for j := 0; j < numOperations; j++ {
+			for range numOperations {
 				val := r.Int()
 				if val < 0 {
 					errors <- nil
@@ -137,11 +137,11 @@ func TestConcurrentAccess(t *testing.T) {
 	}
 
 	// Test concurrent Perm() calls
-	for i := 0; i < numGoroutines; i++ {
+	for range numGoroutines {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			for j := 0; j < numOperations; j++ {
+			for range numOperations {
 				perm := r.Perm(5)
 				if len(perm) != 5 {
 					errors <- nil
@@ -172,11 +172,11 @@ func TestConcurrentMixedOperations(t *testing.T) {
 	errors := make(chan error, numGoroutines*numOperations)
 
 	// Mix of Int() and Perm() operations running concurrently
-	for i := 0; i < numGoroutines; i++ {
+	for i := range numGoroutines {
 		wg.Add(1)
 		go func(id int) {
 			defer wg.Done()
-			for j := 0; j < numOperations; j++ {
+			for j := range numOperations {
 				if j%2 == 0 {
 					val := r.Int()
 					if val < 0 {

plugin/pkg/replacer/replacer_test.go

@@ -276,7 +276,7 @@ func BenchmarkReplacer(b *testing.B) {
 	b.ReportAllocs()
 
 	replacer := New()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		replacer.Replace(context.TODO(), state, nil, "{type} {name} {size}")
 	}
 }
@@ -297,13 +297,13 @@ func BenchmarkReplacer_CommonLogFormat(b *testing.B) {
 
 	b.ResetTimer()
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		replacer.Replace(ctxt, state, w, CommonLogFormat)
 	}
 }
 
 func BenchmarkParseFormat(b *testing.B) {
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		parseFormat(CommonLogFormat)
 	}
 }

plugin/pkg/singleflight/singleflight_test.go

@@ -63,7 +63,7 @@ func TestDoDupSuppress(t *testing.T) {
 
 	const n = 10
 	var wg sync.WaitGroup
-	for i := 0; i < n; i++ {
+	for range n {
 		wg.Add(1)
 		go func() {
 			v, err := g.Do(1, fn)

plugin/rewrite/name.go

@@ -428,7 +428,7 @@ func hasClosingDot(s string) bool {
 // getSubExprUsage returns the number of subexpressions used in s.
 func getSubExprUsage(s string) int {
 	subExprUsage := 0
-	for i := 0; i <= 100; i++ {
+	for i := range 101 {
 		if strings.Contains(s, "{"+strconv.Itoa(i)+"}") {
 			subExprUsage++
 		}

plugin/route53/route53.go

@@ -278,7 +278,7 @@ func (h *Route53) updateZones(ctx context.Context) error {
 	// Collect errors (if any). This will also sync on all zones updates
 	// completion.
 	var errs []string
-	for i := 0; i < len(h.zones); i++ {
+	for range len(h.zones) {
 		err := <-errc
 		if err != nil {
 			errs = append(errs, err.Error())

plugin/route53/setup.go

@@ -50,7 +50,7 @@ func setup(c *caddy.Controller) error {
 
 		args := c.RemainingArgs()
 
-		for i := 0; i < len(args); i++ {
+		for i := range args {
 			parts := strings.SplitN(args[i], ":", 2)
 			if len(parts) != 2 {
 				return plugin.Error("route53", c.Errf("invalid zone %q", args[i]))

plugin/transfer/notify.go

@@ -41,7 +41,7 @@ func sendNotify(c *dns.Client, m *dns.Msg, s string) error {
 	var err error
 
 	code := dns.RcodeServerFailure
-	for i := 0; i < 3; i++ {
+	for range 3 {
 		ret, _, err := c.Exchange(m, s)
 		if err != nil {
 			continue

request/request_test.go

@@ -257,15 +257,15 @@ func TestTruncation(t *testing.T) {
 		reply := new(dns.Msg)
 		reply.SetReply(m)
 
-		for i := 0; i < 61; i++ {
+		for i := range 61 {
 			reply.Answer = append(reply.Answer, test.SRV(fmt.Sprintf("http.service.tcp.srv.k8s.example.org. 5 IN SRV 0 0 80 10-144-230-%d.default.pod.k8s.example.org.", i)))
 		}
 
-		for i := 0; i < 5; i++ {
+		for i := range 5 {
 			reply.Extra = append(reply.Extra, test.A(fmt.Sprintf("ip-10-10-52-5%d.subdomain.example.org. 5 IN A 10.10.52.5%d", i, i)))
 		}
 
-		for i := 0; i < 5; i++ {
+		for i := range 5 {
 			reply.Ns = append(reply.Ns, test.NS(fmt.Sprintf("srv.subdomain.example.org. 5 IN NS ip-10-10-33-6%d.subdomain.example.org.", i)))
 		}
 
@@ -319,7 +319,7 @@ func TestRequestMatch(t *testing.T) {
 func BenchmarkRequestDo(b *testing.B) {
 	st := testRequest()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		st.Do()
 	}
 }
@@ -327,7 +327,7 @@ func BenchmarkRequestDo(b *testing.B) {
 func BenchmarkRequestSize(b *testing.B) {
 	st := testRequest()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		st.Size()
 	}
 }
@@ -347,7 +347,7 @@ func BenchmarkRequestScrub(b *testing.B) {
 	}
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		st.Scrub(reply.Copy())
 	}
 }

test/compression_scrub_test.go

@@ -46,7 +46,7 @@ func TestCompressScrub(t *testing.T) {
 	// compression. This means we're looking for a combo where the pointers is detected and the offset is 12
 	// the position of the first name after the header. The erratic plugin adds 30 RRs that should all be compressed.
 	found := 0
-	for i := 0; i < len(buf)-1; i++ {
+	for i := range len(buf) - 1 {
 		if buf[i]&0xC0 == 0xC0 {
 			off := (int(buf[i])^0xC0)<<8 | int(buf[i+1])
 			if off == 12 {

test/file_xfr_test.go

@@ -17,7 +17,7 @@ func TestLargeAXFR(t *testing.T) {
 	const numAAAAs = 6553
 	sb.WriteString("example.com. IN SOA . . 1 60 60 60 60\n")
 	sb.WriteString("example.com. IN NS ns.example.\n")
-	for i := 0; i < numAAAAs; i++ {
+	for i := range numAAAAs {
 		sb.WriteString(fmt.Sprintf("%d.example.com. IN AAAA 2001:db8::1\n", i))
 	}
 

test/metrics_test.go

@@ -163,7 +163,7 @@ func TestMetricsRewriteRequestSize(t *testing.T) {
 	}
 
 	// Send multiple requests
-	for i := 0; i < numRequests; i++ {
+	for range numRequests {
 		if _, err = dns.Exchange(m, udp); err != nil {
 			t.Fatalf("Could not send message: %s", err)
 		}
@@ -195,7 +195,7 @@ func TestMetricsRewriteRequestSize(t *testing.T) {
 	defer srv2.Stop()
 
 	// Send the same requests with rewrite
-	for i := 0; i < numRequests; i++ {
+	for range numRequests {
 		if _, err = dns.Exchange(m, udp2); err != nil {
 			t.Fatalf("Could not send message: %s", err)
 		}

test/proxy_health_test.go

@@ -65,7 +65,7 @@ func TestProxyThreeWay(t *testing.T) {
 	c := new(dns.Client)
 	c.Timeout = 10 * time.Millisecond
 
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		r, _, err := c.Exchange(m, addr)
 		if err != nil {
 			continue

test/proxy_test.go

@@ -71,7 +71,7 @@ func BenchmarkProxyLookup(b *testing.B) {
 	m.SetQuestion("example.org.", dns.TypeA)
 
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		if _, err := dns.Exchange(m, udp); err != nil {
 			b.Fatal("Expected to receive reply, but didn't")
 		}

test/quic_test.go

@@ -157,7 +157,7 @@ func TestQUICStreamLimits(t *testing.T) {
 	streamsMu := sync.Mutex{}
 
 	// Attempt to open exactly the configured number of streams
-	for i := 0; i < streamCount; i++ {
+	for i := range streamCount {
 		wg.Add(1)
 		go func(idx int) {
 			defer wg.Done()
@@ -237,7 +237,7 @@ func TestQUICStreamLimits(t *testing.T) {
 	done := make(chan struct{})
 
 	// Launch goroutines to attempt opening additional streams
-	for i := 0; i < extraCount; i++ {
+	for i := range extraCount {
 		extraWg.Add(1)
 		go func(idx int) {
 			defer extraWg.Done()

test/reload_test.go

@@ -181,7 +181,7 @@ func TestReloadSeveralTimeMetrics(t *testing.T) {
 		t.Errorf("Prometheus is not listening : %s", err)
 	}
 	reloadCount := 2
-	for i := 0; i < reloadCount; i++ {
+	for i := range reloadCount {
 		serverReload, err := serverWithMetrics.Restart(
 			NewInput(corefileWithMetrics),
 		)
@@ -305,7 +305,7 @@ func TestMetricsAvailableAfterReloadAndFailedReload(t *testing.T) {
 		t.Errorf("Could not scrap one of expected stats : %s", err)
 	}
 
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		// now provide a failed reload
 		invInst, err := inst.Restart(
 			NewInput(invalidCorefileWithMetrics),

test/secondary_test.go

@@ -72,7 +72,7 @@ func TestSecondaryZoneTransfer(t *testing.T) {
 
 	var r *dns.Msg
 	// This is now async; we need to wait for it to be transferred.
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		r, _ = dns.Exchange(m, udp)
 		if len(r.Answer) != 0 {
 			break
@@ -114,7 +114,7 @@ func TestIxfrResponse(t *testing.T) {
 	c := new(dns.Client)
 	c.Net = "tcp"
 	// This is now async; we need to wait for it to be transferred.
-	for i := 0; i < 10; i++ {
+	for range 10 {
 		r, _, _ = c.Exchange(m, tcp)
 		if len(r.Answer) != 0 {
 			break

test/server_test.go

@@ -127,7 +127,7 @@ func TestMultiZoneBlockConfigs(t *testing.T) {
 		server *caddy.Instance
 		err    error
 	)
-	for j := 0; j < 3; j++ {
+	for j := range 3 {
 		corefile := `.:%d .:%d .:%d {
 		debug
 	}`
@@ -150,7 +150,7 @@ func TestMultiZoneBlockConfigs(t *testing.T) {
 	configs := reflect.ValueOf(ctxVal2.Interface()).Elem().FieldByName("configs")
 	configs2 := reflect.NewAt(configs.Type(), unsafe.Pointer(configs.UnsafeAddr())).Elem()
 
-	for i := 0; i < 3; i++ {
+	for i := range 3 {
 		v := configs2.Index(i)
 		config := v.Interface().(*dnsserver.Config)
 		if !config.Debug {