Merge pull request 'Update actions' (#368) from atolstikhin/micro:v3 into v3

Reviewed-on: #368

.gitea/workflows/job_lint.yml

@@ -1,24 +1,26 @@
 name: lint
+
 on:
   pull_request:
+    types: [opened, reopened, closed, synchronize]
     branches:
     - master
     - v3
+    - v4
+
 jobs:
   lint:
-    name: lint
     runs-on: ubuntu-latest
     steps:
     - name: setup-go
-      uses: actions/setup-go@v3
+      uses: actions/setup-go@v5
       with:
-        go-version: 1.21
+        go-version: 'stable'
     - name: checkout
       uses: actions/checkout@v3
     - name: deps
       run: go get -v -d ./...
     - name: lint
-      uses: https://github.com/golangci/golangci-lint-action@v3.4.0
-      continue-on-error: true
+      uses: https://github.com/golangci/golangci-lint-action@v6
       with:
-        version: v1.52
+        version: v1.62.2

.gitea/workflows/job_test.yml

@@ -1,22 +1,30 @@
-name: pr
+name: test
+
 on:
   pull_request:
+    types: [opened, reopened, closed, synchronize]
     branches:
     - master
     - v3
+    - v4
+  push:
+    branches:
+    - master
+    - v3
+    - v4
+
 jobs:
   test:
-    name: test
     runs-on: ubuntu-latest
     steps:
+    - name: setup-go
+      uses: actions/setup-go@v5
+      with:
+        go-version: 'stable'
     - name: checkout
       uses: actions/checkout@v3
-    - name: setup-go
-      uses: actions/setup-go@v3
-      with:
-        go-version: 1.21
     - name: deps
-      run: go get -v -t -d ./...
+      run: go get -v -d ./...
     - name: test
       env:
         INTEGRATION_TESTS: yes

.golangci.yml

@@ -1,44 +1,5 @@
 run:
-  concurrency: 4
+  concurrency: 8
   deadline: 5m
   issues-exit-code: 1
   tests: true
-
-linters-settings:
-  govet:
-    check-shadowing: true
-    enable:
-      - fieldalignment
-
-linters:
-  enable:
-    - govet
-    - deadcode
-    - errcheck
-    - govet
-    - ineffassign
-    - staticcheck
-    - structcheck
-    - typecheck
-    - unused
-    - varcheck
-    - bodyclose
-    - gci
-    - goconst
-    - gocritic
-    - gosimple
-    - gofmt
-    - gofumpt
-    - goimports
-    - revive
-    - gosec
-    - makezero
-    - misspell
-    - nakedret
-    - nestif
-    - nilerr
-    - noctx
-    - prealloc
-    - unconvert
-    - unparam
-  disable-all: false

client/noop.go

@@ -298,7 +298,7 @@ func (n *noopClient) fnCall(ctx context.Context, req Request, rsp interface{}, o
 		// call backoff first. Someone may want an initial start delay
 		t, err := callOpts.Backoff(ctx, req, i)
 		if err != nil {
-			return errors.InternalServerError("go.micro.client", err.Error())
+			return errors.InternalServerError("go.micro.client", "%s", err.Error())
 		}
 
 		// only sleep if greater than 0
@@ -312,7 +312,7 @@ func (n *noopClient) fnCall(ctx context.Context, req Request, rsp interface{}, o
 			// TODO apply any filtering here
 			routes, err = n.opts.Lookup(ctx, req, callOpts)
 			if err != nil {
-				return errors.InternalServerError("go.micro.client", err.Error())
+				return errors.InternalServerError("go.micro.client", "%s", err.Error())
 			}
 
 			// balance the list of nodes
@@ -466,7 +466,7 @@ func (n *noopClient) fnStream(ctx context.Context, req Request, opts ...CallOpti
 		// call backoff first. Someone may want an initial start delay
 		t, cerr := callOpts.Backoff(ctx, req, i)
 		if cerr != nil {
-			return nil, errors.InternalServerError("go.micro.client", cerr.Error())
+			return nil, errors.InternalServerError("go.micro.client", "%s", cerr.Error())
 		}
 
 		// only sleep if greater than 0
@@ -480,7 +480,7 @@ func (n *noopClient) fnStream(ctx context.Context, req Request, opts ...CallOpti
 			// TODO apply any filtering here
 			routes, err = n.opts.Lookup(ctx, req, callOpts)
 			if err != nil {
-				return nil, errors.InternalServerError("go.micro.client", err.Error())
+				return nil, errors.InternalServerError("go.micro.client", "%s", err.Error())
 			}
 
 			// balance the list of nodes
@@ -609,13 +609,13 @@ func (n *noopClient) publish(ctx context.Context, ps []Message, opts ...PublishO
 			// use codec for payload
 			cf, err := n.newCodec(p.ContentType())
 			if err != nil {
-				return errors.InternalServerError("go.micro.client", err.Error())
+				return errors.InternalServerError("go.micro.client", "%s", err.Error())
 			}
 
 			// set the body
 			b, err := cf.Marshal(p.Payload())
 			if err != nil {
-				return errors.InternalServerError("go.micro.client", err.Error())
+				return errors.InternalServerError("go.micro.client", "%s", err.Error())
 			}
 			body = b
 		}

errors/errors_test.go

@@ -2,6 +2,7 @@ package errors
 
 import (
 	"encoding/json"
+	"errors"
 	er "errors"
 	"fmt"
 	"net/http"
@@ -26,7 +27,7 @@ func TestMarshalJSON(t *testing.T) {
 func TestEmpty(t *testing.T) {
 	msg := "test"
 	var err *Error
-	err = FromError(fmt.Errorf(msg))
+	err = FromError(errors.New(msg))
 	if err.Detail != msg {
 		t.Fatalf("invalid error %v", err)
 	}

logger/slog/slog.go

@@ -46,11 +46,11 @@ func (h *wrapper) Handle(ctx context.Context, rec slog.Record) error {
 }
 
 func (h *wrapper) WithAttrs(attrs []slog.Attr) slog.Handler {
-	return h.WithAttrs(attrs)
+	return h.h.WithAttrs(attrs)
 }
 
 func (h *wrapper) WithGroup(name string) slog.Handler {
-	return h.WithGroup(name)
+	return h.h.WithGroup(name)
 }
 
 func (s *slogLogger) renameAttr(_ []string, a slog.Attr) slog.Attr {
@@ -89,7 +89,6 @@ func (s *slogLogger) renameAttr(_ []string, a slog.Attr) slog.Attr {
 }
 
 type slogLogger struct {
-	leveler *slog.LevelVar
 	handler *wrapper
 	opts    logger.Options
 	mu      sync.RWMutex

logger/unwrap/unwrap.go

@@ -36,14 +36,14 @@ var (
 	circularShortBytes = []byte("<shown>")
 	invalidAngleBytes  = []byte("<invalid>")
 	filteredBytes      = []byte("<filtered>")
-	openBracketBytes   = []byte("[")
-	closeBracketBytes  = []byte("]")
-	percentBytes       = []byte("%")
-	precisionBytes     = []byte(".")
-	openAngleBytes     = []byte("<")
-	closeAngleBytes    = []byte(">")
-	openMapBytes       = []byte("{")
-	closeMapBytes      = []byte("}")
+	// openBracketBytes   = []byte("[")
+	// closeBracketBytes  = []byte("]")
+	percentBytes    = []byte("%")
+	precisionBytes  = []byte(".")
+	openAngleBytes  = []byte("<")
+	closeAngleBytes = []byte(">")
+	openMapBytes    = []byte("{")
+	closeMapBytes   = []byte("}")
 )
 
 type protoMessage interface {

logger/unwrap/unwrap_test.go

@@ -82,12 +82,12 @@ func TestTagged(t *testing.T) {
 func TestTaggedNested(t *testing.T) {
 	type val struct {
 		key string `logger:"take"`
-		val string `logger:"omit"`
+		// val string `logger:"omit"`
 		unk string
 	}
 	type str struct {
-		key string `logger:"omit"`
-		val *val   `logger:"take"`
+		// key string `logger:"omit"`
+		val *val `logger:"take"`
 	}
 
 	var iface interface{}

metadata/context.go

@@ -55,10 +55,7 @@ func NewContext(ctx context.Context, md Metadata) context.Context {
 	if ctx == nil {
 		ctx = context.Background()
 	}
-	ctx = context.WithValue(ctx, mdKey{}, &rawMetadata{md})
-	ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{})
-	ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{})
-	return ctx
+	return context.WithValue(ctx, mdKey{}, &rawMetadata{md})
 }
 
 // SetOutgoingContext modify outgoing context with given metadata
@@ -90,11 +87,7 @@ func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
 	if ctx == nil {
 		ctx = context.Background()
 	}
-	ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{md})
-	if v, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata); !ok || v == nil {
-		ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{})
-	}
-	return ctx
+	return context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{md})
 }
 
 // NewOutgoingContext creates a new context with outcoming metadata attached
@@ -102,11 +95,7 @@ func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
 	if ctx == nil {
 		ctx = context.Background()
 	}
-	ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{md})
-	if v, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata); !ok || v == nil {
-		ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{})
-	}
-	return ctx
+	return context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{md})
 }
 
 // AppendOutgoingContext apends new md to context

metadata/metadata_test.go

@@ -80,6 +80,14 @@ func TestPassing(t *testing.T) {
 	ctx = NewIncomingContext(ctx, md1)
 	testCtx(ctx)
 	md, ok := FromOutgoingContext(ctx)
+	if ok {
+		t.Fatalf("create outgoing context")
+	}
+	_ = md
+
+	ctx = NewOutgoingContext(ctx, New(1))
+	testCtx(ctx)
+	md, ok = FromOutgoingContext(ctx)
 	if !ok {
 		t.Fatalf("missing metadata from outgoing context")
 	}

micro.go

@@ -65,6 +65,8 @@ func As(b any, target any) bool {
 			break
 		case targetType.Implements(routerType):
 			break
+		case targetType.Implements(tracerType):
+			break
 		default:
 			return false
 		}
@@ -76,19 +78,21 @@ func As(b any, target any) bool {
 	return false
 }
 
-var brokerType = reflect.TypeOf((*broker.Broker)(nil)).Elem()
-var loggerType = reflect.TypeOf((*logger.Logger)(nil)).Elem()
-var clientType = reflect.TypeOf((*client.Client)(nil)).Elem()
-var serverType = reflect.TypeOf((*server.Server)(nil)).Elem()
-var codecType = reflect.TypeOf((*codec.Codec)(nil)).Elem()
-var flowType = reflect.TypeOf((*flow.Flow)(nil)).Elem()
-var fsmType = reflect.TypeOf((*fsm.FSM)(nil)).Elem()
-var meterType = reflect.TypeOf((*meter.Meter)(nil)).Elem()
-var registerType = reflect.TypeOf((*register.Register)(nil)).Elem()
-var resolverType = reflect.TypeOf((*resolver.Resolver)(nil)).Elem()
-var routerType = reflect.TypeOf((*router.Router)(nil)).Elem()
-var selectorType = reflect.TypeOf((*selector.Selector)(nil)).Elem()
-var storeType = reflect.TypeOf((*store.Store)(nil)).Elem()
-var syncType = reflect.TypeOf((*sync.Sync)(nil)).Elem()
-var tracerType = reflect.TypeOf((*tracer.Tracer)(nil)).Elem()
-var serviceType = reflect.TypeOf((*Service)(nil)).Elem()
+var (
+	brokerType   = reflect.TypeOf((*broker.Broker)(nil)).Elem()
+	loggerType   = reflect.TypeOf((*logger.Logger)(nil)).Elem()
+	clientType   = reflect.TypeOf((*client.Client)(nil)).Elem()
+	serverType   = reflect.TypeOf((*server.Server)(nil)).Elem()
+	codecType    = reflect.TypeOf((*codec.Codec)(nil)).Elem()
+	flowType     = reflect.TypeOf((*flow.Flow)(nil)).Elem()
+	fsmType      = reflect.TypeOf((*fsm.FSM)(nil)).Elem()
+	meterType    = reflect.TypeOf((*meter.Meter)(nil)).Elem()
+	registerType = reflect.TypeOf((*register.Register)(nil)).Elem()
+	resolverType = reflect.TypeOf((*resolver.Resolver)(nil)).Elem()
+	routerType   = reflect.TypeOf((*router.Router)(nil)).Elem()
+	selectorType = reflect.TypeOf((*selector.Selector)(nil)).Elem()
+	storeType    = reflect.TypeOf((*store.Store)(nil)).Elem()
+	syncType     = reflect.TypeOf((*sync.Sync)(nil)).Elem()
+	tracerType   = reflect.TypeOf((*tracer.Tracer)(nil)).Elem()
+	serviceType  = reflect.TypeOf((*Service)(nil)).Elem()
+)

options.go

@@ -269,7 +269,7 @@ func Logger(l logger.Logger, opts ...LoggerOption) Option {
 				}
 			}
 		}
-		
+
 		for _, trc := range o.Tracers {
 			for _, ot := range lopts.tracers {
 				if trc.Name() == ot || all {
@@ -294,8 +294,8 @@ type loggerOptions struct {
 	brokers   []string
 	registers []string
 	stores    []string
-	meters    []string
-	tracers   []string
+	// meters    []string
+	tracers []string
 }
 
 /*

register/memory/memory.go

@@ -469,9 +469,7 @@ func serviceToRecord(s *register.Service, ttl time.Duration) *record {
 	}
 
 	endpoints := make([]*register.Endpoint, len(s.Endpoints))
-	for i, e := range s.Endpoints {
-		endpoints[i] = e
-	}
+	copy(endpoints, s.Endpoints)
 
 	return &record{
 		Name:      s.Name,

register/memory/memory_test.go

@@ -290,27 +290,25 @@ func TestWatcher(t *testing.T) {
 
 	ctx := context.TODO()
 	m := NewRegister()
-	m.Init()
-	m.Connect(ctx)
+	_ = m.Init()
+	_ = m.Connect(ctx)
 	wc, err := m.Watch(ctx)
 	if err != nil {
 		t.Fatalf("cant watch: %v", err)
 	}
 	defer wc.Stop()
 
+	cherr := make(chan error, 10)
 	var wg sync.WaitGroup
 	wg.Add(1)
 	go func() {
-		for {
-			_, err := wc.Next()
-			if err != nil {
-				t.Fatal("unexpected err", err)
-			}
-			// t.Logf("changes %#+v", ch.Service)
-			wc.Stop()
-			wg.Done()
-			return
+		_, err := wc.Next()
+		if err != nil {
+			cherr <- fmt.Errorf("unexpected err %v", err)
 		}
+		// t.Logf("changes %#+v", ch.Service)
+		wc.Stop()
+		wg.Done()
 	}()
 
 	if err := m.Register(ctx, testSrv); err != nil {

resolver/dns/dns.go

@@ -12,9 +12,9 @@ import (
 
 // Resolver is a DNS network resolve
 type Resolver struct {
-	sync.RWMutex
 	goresolver *net.Resolver
 	Address    string
+	mu         sync.RWMutex
 }
 
 // Resolve tries to resolve endpoint address
@@ -39,12 +39,12 @@ func (r *Resolver) Resolve(name string) ([]*resolver.Record, error) {
 		return []*resolver.Record{rec}, nil
 	}
 
-	r.RLock()
+	r.mu.RLock()
 	goresolver := r.goresolver
-	r.RUnlock()
+	r.mu.RUnlock()
 
 	if goresolver == nil {
-		r.Lock()
+		r.mu.Lock()
 		r.goresolver = &net.Resolver{
 			Dial: func(ctx context.Context, _ string, _ string) (net.Conn, error) {
 				d := net.Dialer{
@@ -53,7 +53,7 @@ func (r *Resolver) Resolve(name string) ([]*resolver.Record, error) {
 				return d.DialContext(ctx, "udp", r.Address)
 			},
 		}
-		r.Unlock()
+		r.mu.Unlock()
 	}
 
 	addrs, err := goresolver.LookupIP(context.TODO(), "ip", host)

server/noop.go

@@ -171,7 +171,6 @@ type rpcMessage struct {
 	header      metadata.Metadata
 	topic       string
 	contentType string
-	body        []byte
 }
 
 func (r *rpcMessage) ContentType() string {

server/noop_test.go

@@ -38,7 +38,7 @@ func TestNoopSub(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	logger.DefaultLogger.Init(logger.WithLevel(logger.ErrorLevel))
+	_ = logger.DefaultLogger.Init(logger.WithLevel(logger.ErrorLevel))
 	s := server.NewServer(
 		server.Broker(b),
 		server.Codec("application/octet-stream", codec.NewCodec()),

service.go

@@ -3,7 +3,9 @@ package micro
 
 import (
 	"fmt"
+	"net"
 	"sync"
+	"time"
 
 	"github.com/KimMachineGun/automemlimit/memlimit"
 	"go.uber.org/automaxprocs/maxprocs"
@@ -17,11 +19,12 @@ import (
 	"go.unistack.org/micro/v3/server"
 	"go.unistack.org/micro/v3/store"
 	"go.unistack.org/micro/v3/tracer"
+	utildns "go.unistack.org/micro/v3/util/dns"
 )
 
 func init() {
-	maxprocs.Set()
-	memlimit.SetGoMemLimitWithOpts(
+	_, _ = maxprocs.Set()
+	_, _ = memlimit.SetGoMemLimitWithOpts(
 		memlimit.WithRatio(0.9),
 		memlimit.WithProvider(
 			memlimit.ApplyFallback(
@@ -30,6 +33,8 @@ func init() {
 			),
 		),
 	)
+
+	net.DefaultResolver = utildns.NewNetResolver(utildns.Timeout(1 * time.Second))
 }
 
 // Service is an interface that wraps the lower level components.

store/store.go

@@ -105,3 +105,7 @@ func NewWatchOptions(opts ...WatchOption) (WatchOptions, error) {
 
 	return options, err
 }
+
+func Watch(context.Context) (Watcher, error) {
+	return nil, nil
+}

util/dns/cache.go

@@ -0,0 +1,377 @@
+package dns
+
+import (
+	"context"
+	"math"
+	"net"
+	"sync"
+	"time"
+)
+
+// DialFunc is a [net.Resolver.Dial] function.
+type DialFunc func(ctx context.Context, network, address string) (net.Conn, error)
+
+// NewNetResolver creates a caching [net.Resolver] that uses parent to resolve names.
+func NewNetResolver(opts ...Option) *net.Resolver {
+	options := Options{Resolver: &net.Resolver{}}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return &net.Resolver{
+		PreferGo:     true,
+		StrictErrors: options.Resolver.StrictErrors,
+		Dial:         NewNetDialer(options.Resolver.Dial, append(opts, Resolver(options.Resolver))...),
+	}
+}
+
+// NewNetDialer adds caching to a [net.Resolver.Dial] function.
+func NewNetDialer(parent DialFunc, opts ...Option) DialFunc {
+	cache := cache{dial: parent, opts: Options{}}
+	for _, o := range opts {
+		o(&cache.opts)
+	}
+	if cache.opts.MaxCacheEntries == 0 {
+		cache.opts.MaxCacheEntries = DefaultMaxCacheEntries
+	}
+	return func(ctx context.Context, network, address string) (net.Conn, error) {
+		conn := &dnsConn{}
+		conn.roundTrip = cachingRoundTrip(&cache, network, address)
+		return conn, nil
+	}
+}
+
+const DefaultMaxCacheEntries = 300
+
+// A Option customizes the resolver cache.
+type Option func(*Options)
+
+type Options struct {
+	Resolver        *net.Resolver
+	MaxCacheEntries int
+	MaxCacheTTL     time.Duration
+	MinCacheTTL     time.Duration
+	NegativeCache   bool
+	PreferIPV4      bool
+	PreferIPV6      bool
+	Timeout         time.Duration
+}
+
+// MaxCacheEntries sets the maximum number of entries to cache.
+// If zero, [DefaultMaxCacheEntries] is used; negative means no limit.
+func MaxCacheEntries(n int) Option {
+	return func(o *Options) {
+		o.MaxCacheEntries = n
+	}
+}
+
+// MaxCacheTTL sets the maximum time-to-live for entries in the cache.
+func MaxCacheTTL(td time.Duration) Option {
+	return func(o *Options) {
+		o.MaxCacheTTL = td
+	}
+}
+
+// MinCacheTTL sets the minimum time-to-live for entries in the cache.
+func MinCacheTTL(td time.Duration) Option {
+	return func(o *Options) {
+		o.MinCacheTTL = td
+	}
+}
+
+// NegativeCache sets whether to cache negative responses.
+func NegativeCache(b bool) Option {
+	return func(o *Options) {
+		o.NegativeCache = b
+	}
+}
+
+// Timeout sets upstream *net.Resolver timeout
+func Timeout(td time.Duration) Option {
+	return func(o *Options) {
+		o.Timeout = td
+	}
+}
+
+// Resolver sets upstream *net.Resolver.
+func Resolver(r *net.Resolver) Option {
+	return func(o *Options) {
+		o.Resolver = r
+	}
+}
+
+// PreferIPV4 resolve ipv4 records.
+func PreferIPV4(b bool) Option {
+	return func(o *Options) {
+		o.PreferIPV4 = b
+	}
+}
+
+// PreferIPV6 resolve ipv4 records.
+func PreferIPV6(b bool) Option {
+	return func(o *Options) {
+		o.PreferIPV6 = b
+	}
+}
+
+type cache struct {
+	sync.RWMutex
+
+	dial    DialFunc
+	entries map[string]cacheEntry
+
+	opts Options
+}
+
+type cacheEntry struct {
+	deadline time.Time
+	value    string
+}
+
+func (c *cache) put(req string, res string) {
+	// ignore uncacheable/unparseable answers
+	if invalid(req, res) {
+		return
+	}
+
+	// ignore errors (if requested)
+	if nameError(res) && !c.opts.NegativeCache {
+		return
+	}
+
+	// ignore uncacheable/unparseable answers
+	ttl := getTTL(res)
+	if ttl <= 0 {
+		return
+	}
+
+	// adjust TTL
+	if ttl < c.opts.MinCacheTTL {
+		ttl = c.opts.MinCacheTTL
+	}
+	// maxTTL overrides minTTL
+	if ttl > c.opts.MaxCacheTTL && c.opts.MaxCacheTTL != 0 {
+		ttl = c.opts.MaxCacheTTL
+	}
+
+	c.Lock()
+	defer c.Unlock()
+	if c.entries == nil {
+		c.entries = make(map[string]cacheEntry)
+	}
+
+	// do some cache evition
+	var tested, evicted int
+	for k, e := range c.entries {
+		if time.Until(e.deadline) <= 0 {
+			// delete expired entry
+			delete(c.entries, k)
+			evicted++
+		}
+		tested++
+
+		if tested < 8 {
+			continue
+		}
+		if evicted == 0 && c.opts.MaxCacheEntries > 0 && len(c.entries) >= c.opts.MaxCacheEntries {
+			// delete at least one entry
+			delete(c.entries, k)
+		}
+		break
+	}
+
+	// remove message IDs
+	c.entries[req[2:]] = cacheEntry{
+		deadline: time.Now().Add(ttl),
+		value:    res[2:],
+	}
+}
+
+func (c *cache) get(req string) (res string) {
+	// ignore invalid messages
+	if len(req) < 12 {
+		return ""
+	}
+	if req[2] >= 0x7f {
+		return ""
+	}
+
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.entries == nil {
+		return ""
+	}
+
+	// remove message ID
+	entry, ok := c.entries[req[2:]]
+	if ok && time.Until(entry.deadline) > 0 {
+		// prepend correct ID
+		return req[:2] + entry.value
+	}
+	return ""
+}
+
+func invalid(req string, res string) bool {
+	if len(req) < 12 || len(res) < 12 { // header size
+		return true
+	}
+	if req[0] != res[0] || req[1] != res[1] { // IDs match
+		return true
+	}
+	if req[2] >= 0x7f || res[2] < 0x7f { // query, response
+		return true
+	}
+	if req[2]&0x7a != 0 || res[2]&0x7a != 0 { // standard query, not truncated
+		return true
+	}
+	if res[3]&0xf != 0 && res[3]&0xf != 3 { // no error, or name error
+		return true
+	}
+	return false
+}
+
+func nameError(res string) bool {
+	return res[3]&0xf == 3
+}
+
+func getTTL(msg string) time.Duration {
+	ttl := math.MaxInt32
+
+	qdcount := getUint16(msg[4:])
+	ancount := getUint16(msg[6:])
+	nscount := getUint16(msg[8:])
+	arcount := getUint16(msg[10:])
+	rdcount := ancount + nscount + arcount
+
+	msg = msg[12:] // skip header
+
+	// skip questions
+	for i := 0; i < qdcount; i++ {
+		name := getNameLen(msg)
+		if name < 0 || name+4 > len(msg) {
+			return -1
+		}
+		msg = msg[name+4:]
+	}
+
+	// parse records
+	for i := 0; i < rdcount; i++ {
+		name := getNameLen(msg)
+		if name < 0 || name+10 > len(msg) {
+			return -1
+		}
+		rtyp := getUint16(msg[name+0:])
+		rttl := getUint32(msg[name+4:])
+		rlen := getUint16(msg[name+8:])
+		if name+10+rlen > len(msg) {
+			return -1
+		}
+		// skip EDNS OPT since it doesn't have a TTL
+		if rtyp != 41 && rttl < ttl {
+			ttl = rttl
+		}
+		msg = msg[name+10+rlen:]
+	}
+
+	return time.Duration(ttl) * time.Second
+}
+
+func getNameLen(msg string) int {
+	i := 0
+	for i < len(msg) {
+		if msg[i] == 0 {
+			// end of name
+			i += 1
+			break
+		}
+		if msg[i] >= 0xc0 {
+			// compressed name
+			i += 2
+			break
+		}
+		if msg[i] >= 0x40 {
+			// reserved
+			return -1
+		}
+		i += int(msg[i] + 1)
+	}
+	return i
+}
+
+func getUint16(s string) int {
+	return int(s[1]) | int(s[0])<<8
+}
+
+func getUint32(s string) int {
+	return int(s[3]) | int(s[2])<<8 | int(s[1])<<16 | int(s[0])<<24
+}
+
+func cachingRoundTrip(cache *cache, network, address string) roundTripper {
+	return func(ctx context.Context, req string) (res string, err error) {
+		// check cache
+		if res := cache.get(req); res != "" {
+			return res, nil
+		}
+
+		switch {
+		case cache.opts.PreferIPV4 && cache.opts.PreferIPV6:
+			network = "udp"
+		case cache.opts.PreferIPV4:
+			network = "udp4"
+		case cache.opts.PreferIPV6:
+			network = "udp6"
+		default:
+			network = "udp"
+		}
+
+		if cache.opts.Timeout > 0 {
+			var cancel func()
+			ctx, cancel = context.WithTimeout(ctx, cache.opts.Timeout)
+			defer cancel()
+		}
+
+		// dial connection
+		var conn net.Conn
+		if cache.dial != nil {
+			conn, err = cache.dial(ctx, network, address)
+		} else {
+			var d net.Dialer
+			conn, err = d.DialContext(ctx, network, address)
+		}
+		if err != nil {
+			return "", err
+		}
+
+		ctx, cancel := context.WithCancel(ctx)
+		go func() {
+			<-ctx.Done()
+			conn.Close()
+		}()
+		defer cancel()
+
+		if t, ok := ctx.Deadline(); ok {
+			err = conn.SetDeadline(t)
+			if err != nil {
+				return "", err
+			}
+		}
+
+		// send request
+		err = writeMessage(conn, req)
+		if err != nil {
+			return "", err
+		}
+
+		// read response
+		res, err = readMessage(conn)
+		if err != nil {
+			return "", err
+		}
+
+		// cache response
+		cache.put(req, res)
+		return res, nil
+	}
+}

util/dns/cache_test.go

@@ -0,0 +1,16 @@
+package dns
+
+import (
+	"net"
+	"testing"
+)
+
+func TestCache(t *testing.T) {
+	net.DefaultResolver = NewNetResolver(PreferIPV4(true))
+
+	addrs, err := net.LookupHost("unistack.org")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("addrs %v", addrs)
+}

util/dns/conn.go

@@ -0,0 +1,183 @@
+package dns
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net"
+	"strings"
+	"sync"
+	"time"
+)
+
+type dnsConn struct {
+	sync.Mutex
+
+	ibuf bytes.Buffer
+	obuf bytes.Buffer
+
+	ctx       context.Context
+	cancel    context.CancelFunc
+	deadline  time.Time
+	roundTrip roundTripper
+}
+
+type roundTripper func(ctx context.Context, req string) (res string, err error)
+
+func (c *dnsConn) Read(b []byte) (n int, err error) {
+	imsg, n, err := c.drainBuffers(b)
+	if n != 0 || err != nil {
+		return n, err
+	}
+
+	ctx, cancel := c.childContext()
+	omsg, err := c.roundTrip(ctx, imsg)
+	cancel()
+	if err != nil {
+		return 0, err
+	}
+
+	return c.fillBuffer(b, omsg)
+}
+
+func (c *dnsConn) Write(b []byte) (n int, err error) {
+	c.Lock()
+	defer c.Unlock()
+	return c.ibuf.Write(b)
+}
+
+func (c *dnsConn) Close() error {
+	c.Lock()
+	cancel := c.cancel
+	c.Unlock()
+
+	if cancel != nil {
+		cancel()
+	}
+	return nil
+}
+
+func (c *dnsConn) LocalAddr() net.Addr {
+	return nil
+}
+
+func (c *dnsConn) RemoteAddr() net.Addr {
+	return nil
+}
+
+func (c *dnsConn) SetDeadline(t time.Time) error {
+	var err error
+	if err = c.SetReadDeadline(t); err != nil {
+		return err
+	}
+	if err = c.SetWriteDeadline(t); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (c *dnsConn) SetReadDeadline(t time.Time) error {
+	c.Lock()
+	defer c.Unlock()
+	c.deadline = t
+	return nil
+}
+
+func (c *dnsConn) SetWriteDeadline(t time.Time) error {
+	// writes do not timeout
+	return nil
+}
+
+func (c *dnsConn) drainBuffers(b []byte) (string, int, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	// drain the output buffer
+	if c.obuf.Len() > 0 {
+		n, err := c.obuf.Read(b)
+		return "", n, err
+	}
+
+	// otherwise, get the next message from the input buffer
+	sz := c.ibuf.Next(2)
+	if len(sz) < 2 {
+		return "", 0, io.ErrUnexpectedEOF
+	}
+
+	size := int64(sz[0])<<8 | int64(sz[1])
+
+	var str strings.Builder
+	_, err := io.CopyN(&str, &c.ibuf, size)
+	if err == io.EOF {
+		return "", 0, io.ErrUnexpectedEOF
+	}
+	if err != nil {
+		return "", 0, err
+	}
+	return str.String(), 0, nil
+}
+
+func (c *dnsConn) fillBuffer(b []byte, str string) (int, error) {
+	c.Lock()
+	defer c.Unlock()
+	c.obuf.WriteByte(byte(len(str) >> 8))
+	c.obuf.WriteByte(byte(len(str)))
+	c.obuf.WriteString(str)
+	return c.obuf.Read(b)
+}
+
+func (c *dnsConn) childContext() (context.Context, context.CancelFunc) {
+	c.Lock()
+	defer c.Unlock()
+	if c.ctx == nil {
+		c.ctx, c.cancel = context.WithCancel(context.Background())
+	}
+	return context.WithDeadline(c.ctx, c.deadline)
+}
+
+func writeMessage(conn net.Conn, msg string) error {
+	var buf []byte
+	if _, ok := conn.(net.PacketConn); ok {
+		buf = []byte(msg)
+	} else {
+		buf = make([]byte, len(msg)+2)
+		buf[0] = byte(len(msg) >> 8)
+		buf[1] = byte(len(msg))
+		copy(buf[2:], msg)
+	}
+	// SHOULD do a single write on TCP (RFC 7766, section 8).
+	// MUST do a single write on UDP.
+	_, err := conn.Write(buf)
+	return err
+}
+
+func readMessage(c net.Conn) (string, error) {
+	if _, ok := c.(net.PacketConn); ok {
+		// RFC 1035 specifies 512 as the maximum message size for DNS over UDP.
+		// RFC 6891 OTOH suggests 4096 as the maximum payload size for EDNS.
+		b := make([]byte, 4096)
+		n, err := c.Read(b)
+		if err != nil {
+			return "", err
+		}
+		return string(b[:n]), nil
+	} else {
+		var sz [2]byte
+		_, err := io.ReadFull(c, sz[:])
+		if err != nil {
+			return "", err
+		}
+
+		size := int64(sz[0])<<8 | int64(sz[1])
+
+		var str strings.Builder
+		_, err = io.CopyN(&str, c, size)
+		if err == io.EOF {
+			return "", io.ErrUnexpectedEOF
+		}
+		if err != nil {
+			return "", err
+		}
+		return str.String(), nil
+	}
+}

util/jitter/ticker.go

@@ -16,7 +16,6 @@ type Ticker struct {
 	C    chan time.Time
 	min  int64
 	max  int64
-	exp  int64
 	exit bool
 	rng  rand.Rand
 }

util/reflect/reflect.go

@@ -91,7 +91,7 @@ func Merge(dst interface{}, mp map[string]interface{}, opts ...Option) error {
 	}
 
 	if mapper, ok := dst.(map[string]interface{}); ok {
-		dst = mergeMap(mapper, mp, 0)
+		mergeMap(mapper, mp, 0)
 		return nil
 	}
 

util/reflect/reflect_test.go

@@ -1,9 +1,38 @@
 package reflect
 
 import (
+	"fmt"
 	"testing"
 )
 
+func TestMergeMapStringInterface(t *testing.T) {
+	var dst interface{} //nolint:gosimple
+	dst = map[string]interface{}{
+		"xx": 11,
+	}
+
+	src := map[string]interface{}{
+		"zz": "aa",
+	}
+
+	if err := Merge(dst, src); err != nil {
+		t.Fatal(err)
+	}
+
+	mp, ok := dst.(map[string]interface{})
+	if !ok || mp == nil {
+		t.Fatalf("xxx %#+v\n", dst)
+	}
+
+	if fmt.Sprintf("%v", mp["xx"]) != "11" {
+		t.Fatalf("xxx zzzz %#+v", mp)
+	}
+
+	if fmt.Sprintf("%v", mp["zz"]) != "aa" {
+		t.Fatalf("xxx zzzz %#+v", mp)
+	}
+}
+
 func TestMergeMap(t *testing.T) {
 	src := map[string]interface{}{
 		"skey1": "sval1",

util/structfs/metadata_digitalocean.go

@@ -56,7 +56,7 @@ type DigitalOceanMetadata struct {
 func (stfs *DigitalOceanMetadata) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch r.URL.Path {
 	case "/metadata/v1.json":
-		json.NewEncoder(w).Encode(stfs.Metadata.V1)
+		_ = json.NewEncoder(w).Encode(stfs.Metadata.V1)
 	default:
 		fs := FileServer(stfs, "json", time.Now())
 		idx := strings.Index(r.URL.Path[1:], "/")

util/structfs/metadata_ec2.go

@@ -12,7 +12,7 @@ type EC2Metadata struct {
 			InstanceType       string   `json:"instance-type"`
 			LocalHostname      string   `json:"local-hostname"`
 			LocalIPv4          string   `json:"local-ipv4"`
-			kernelID           int      `json:"kernel-id"`
+			KernelID           int      `json:"kernel-id"`
 			Placement          string   `json:"placement"`
 			AvailabilityZone   string   `json:"availability-zone"`
 			ProductCodes       string   `json:"product-codes"`

util/structfs/structfs.go

@@ -27,7 +27,7 @@ func (fs *fs) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	f, err := fs.Open(r.URL.Path)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		w.Write([]byte(err.Error()))
+		_, _ = w.Write([]byte(err.Error()))
 		return
 	}
 	w.Header().Set("Content-Type", "application/octet-stream")
@@ -67,9 +67,9 @@ func (fi *fileInfo) Name() string {
 
 func (fi *fileInfo) Mode() os.FileMode {
 	if strings.HasSuffix(fi.name, "/") {
-		return os.FileMode(0755) | os.ModeDir
+		return os.FileMode(0o755) | os.ModeDir
 	}
-	return os.FileMode(0644)
+	return os.FileMode(0o644)
 }
 
 func (fi *fileInfo) IsDir() bool {
@@ -112,15 +112,14 @@ func (f *file) Readdir(count int) ([]os.FileInfo, error) {
 func (f *file) Seek(offset int64, whence int) (int64, error) {
 	//	log.Printf("seek %d %d %s\n", offset, whence, f.name)
 	switch whence {
-	case os.SEEK_SET:
+	case io.SeekStart:
 		f.offset = offset
-	case os.SEEK_CUR:
+	case io.SeekCurrent:
 		f.offset += offset
-	case os.SEEK_END:
+	case io.SeekEnd:
 		f.offset = int64(len(f.data)) + offset
 	}
 	return f.offset, nil
-
 }
 
 func (f *file) Stat() (os.FileInfo, error) {
@@ -222,6 +221,7 @@ func getValue(name string, iface interface{}, tag string) ([]byte, error) {
 	return nil, fmt.Errorf("failed to find %s in interface %T", name, iface)
 }
 
+/*
 func hasValidType(obj interface{}, types []reflect.Kind) bool {
 	for _, t := range types {
 		if reflect.TypeOf(obj).Kind() == t {
@@ -231,6 +231,7 @@ func hasValidType(obj interface{}, types []reflect.Kind) bool {
 
 	return false
 }
+*/
 
 func reflectValue(obj interface{}) reflect.Value {
 	var val reflect.Value

util/structfs/structfs_test.go

@@ -2,7 +2,7 @@ package structfs
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"reflect"
 	"testing"
@@ -61,7 +61,7 @@ var doOrig = []byte(`{
 }
 `)
 
-func server(t *testing.T) {
+func server(t *testing.T, ch chan error) {
 	stfs := DigitalOceanMetadata{}
 	err := json.Unmarshal(doOrig, &stfs.Metadata.V1)
 	if err != nil {
@@ -71,7 +71,7 @@ func server(t *testing.T) {
 	http.Handle("/metadata/v1/", FileServer(&stfs, "json", time.Now()))
 	http.Handle("/metadata/v1.json", &stfs)
 	go func() {
-		t.Fatal(http.ListenAndServe("127.0.0.1:8080", nil))
+		ch <- http.ListenAndServe("127.0.0.1:8080", nil)
 	}()
 	time.Sleep(2 * time.Second)
 }
@@ -82,13 +82,14 @@ func get(path string) ([]byte, error) {
 		return nil, err
 	}
 	defer res.Body.Close()
-	return ioutil.ReadAll(res.Body)
+	return io.ReadAll(res.Body)
 }
 
 func TestAll(t *testing.T) {
-	server(t)
+	ch := make(chan error)
+	server(t, ch)
 
-	var tests = []struct {
+	tests := []struct {
 		in  string
 		out string
 	}{
@@ -100,34 +101,44 @@ func TestAll(t *testing.T) {
 	}
 
 	for _, tt := range tests {
-		buf, err := get(tt.in)
+		select {
+		case err := <-ch:
+			t.Fatal(err)
+		default:
+			buf, err := get(tt.in)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if string(buf) != tt.out {
+				t.Errorf("req %s output %s not match requested %s", tt.in, string(buf), tt.out)
+			}
+		}
+	}
+
+	select {
+	case err := <-ch:
+		t.Fatal(err)
+	default:
+		doTest, err := get("http://127.0.0.1:8080/metadata/v1.json")
 		if err != nil {
 			t.Fatal(err)
 		}
-		if string(buf) != tt.out {
-			t.Errorf("req %s output %s not match requested %s", tt.in, string(buf), tt.out)
+
+		oSt := DigitalOceanMetadata{}
+		err = json.Unmarshal(doOrig, &oSt.Metadata.V1)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		nSt := DigitalOceanMetadata{}
+
+		err = json.Unmarshal(doTest, &nSt.Metadata.V1)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if !reflect.DeepEqual(oSt, nSt) {
+			t.Fatalf("%v not match %v", oSt, nSt)
 		}
 	}
-
-	doTest, err := get("http://127.0.0.1:8080/metadata/v1.json")
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	oSt := DigitalOceanMetadata{}
-	err = json.Unmarshal(doOrig, &oSt.Metadata.V1)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	nSt := DigitalOceanMetadata{}
-
-	err = json.Unmarshal(doTest, &nSt.Metadata.V1)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if !reflect.DeepEqual(oSt, nSt) {
-		t.Fatalf("%v not match %v", oSt, nSt)
-	}
 }

util/time/duration.go

@@ -14,7 +14,7 @@ type Duration int64
 
 func ParseDuration(s string) (time.Duration, error) {
 	if s == "" {
-		return 0, fmt.Errorf(`time: invalid duration "` + s + `"`)
+		return 0, errors.New(`time: invalid duration "` + s + `"`)
 	}
 
 	var p int

util/xpool/pool.go

@@ -39,19 +39,16 @@ func newStatsMeter() {
 	ticker := time.NewTicker(meter.DefaultMeterStatsInterval)
 	defer ticker.Stop()
 
-	for {
-		select {
-		case <-ticker.C:
-			poolsMu.Lock()
-			for _, st := range pools {
-				stats := st.Stats()
-				meter.DefaultMeter.Counter(semconv.PoolGetTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Get)
-				meter.DefaultMeter.Counter(semconv.PoolPutTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Put)
-				meter.DefaultMeter.Counter(semconv.PoolMisTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Mis)
-				meter.DefaultMeter.Counter(semconv.PoolRetTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Ret)
-			}
-			poolsMu.Unlock()
+	for range ticker.C {
+		poolsMu.Lock()
+		for _, st := range pools {
+			stats := st.Stats()
+			meter.DefaultMeter.Counter(semconv.PoolGetTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Get)
+			meter.DefaultMeter.Counter(semconv.PoolPutTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Put)
+			meter.DefaultMeter.Counter(semconv.PoolMisTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Mis)
+			meter.DefaultMeter.Counter(semconv.PoolRetTotal, "capacity", strconv.Itoa(st.Cap())).Set(stats.Ret)
 		}
+		poolsMu.Unlock()
 	}
 }