chore: import upstream snapshot with attribution

2026-07-13 12:40:33 +08:00
commit e071084ebe
982 changed files with 160368 additions and 0 deletions
@@ -0,0 +1,165 @@
+// addr provides functions to retrieve local IP addresses from device interfaces.
+package addr
+
+import (
+	"net"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	// ErrIPNotFound no IP address found, and explicit IP not provided.
+	ErrIPNotFound = errors.New("no IP address found, and explicit IP not provided")
+)
+
+// IsLocal checks whether an IP belongs to one of the device's interfaces.
+func IsLocal(addr string) bool {
+	// Extract the host
+	host, _, err := net.SplitHostPort(addr)
+	if err == nil {
+		addr = host
+	}
+
+	if addr == "localhost" {
+		return true
+	}
+
+	// Check against all local ips
+	for _, ip := range IPs() {
+		if addr == ip {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Extract returns a valid IP address. If the address provided is a valid
+// address, it will be returned directly. Otherwise, the available interfaces
+// will be iterated over to find an IP address, preferably private.
+func Extract(addr string) (string, error) {
+	// if addr is already specified then it's directly returned
+	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]" && addr != "::") {
+		return addr, nil
+	}
+
+	var (
+		addrs   []net.Addr
+		loAddrs []net.Addr
+	)
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", errors.Wrap(err, "failed to get interfaces")
+	}
+
+	for _, iface := range ifaces {
+		ifaceAddrs, err := iface.Addrs()
+		if err != nil {
+			// ignore error, interface can disappear from system
+			continue
+		}
+
+		if iface.Flags&net.FlagLoopback != 0 {
+			loAddrs = append(loAddrs, ifaceAddrs...)
+			continue
+		}
+
+		addrs = append(addrs, ifaceAddrs...)
+	}
+
+	// Add loopback addresses to the end of the list
+	addrs = append(addrs, loAddrs...)
+
+	// Try to find private IP in list, public IP otherwise
+	ip, err := findIP(addrs)
+	if err != nil {
+		return "", err
+	}
+
+	return ip.String(), nil
+}
+
+// IPs returns all available interface IP addresses.
+func IPs() []string {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil
+	}
+
+	var ipAddrs []string
+
+	for _, i := range ifaces {
+		addrs, err := i.Addrs()
+		if err != nil {
+			continue
+		}
+
+		for _, addr := range addrs {
+			var ip net.IP
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+
+			if ip == nil {
+				continue
+			}
+
+			ipAddrs = append(ipAddrs, ip.String())
+		}
+	}
+
+	return ipAddrs
+}
+
+// findIP will return the first private IP available in the list.
+// If no private IP is available it will return the first public IP, if present.
+// If no public IP is available, it will return the first loopback IP, if present.
+func findIP(addresses []net.Addr) (net.IP, error) {
+	var publicIP net.IP
+	var localIP net.IP
+
+	for _, rawAddr := range addresses {
+		var ip net.IP
+		switch addr := rawAddr.(type) {
+		case *net.IPAddr:
+			ip = addr.IP
+		case *net.IPNet:
+			ip = addr.IP
+		default:
+			continue
+		}
+
+		if ip.IsLoopback() {
+			if localIP == nil {
+				localIP = ip
+			}
+			continue
+		}
+
+		if !ip.IsPrivate() {
+			if publicIP == nil {
+				publicIP = ip
+			}
+			continue
+		}
+
+		// Return private IP if available
+		return ip, nil
+	}
+
+	// Return public or virtual IP
+	if len(publicIP) > 0 {
+		return publicIP, nil
+	}
+
+	// Return local IP
+	if len(localIP) > 0 {
+		return localIP, nil
+	}
+
+	return nil, ErrIPNotFound
+}
@@ -0,0 +1,132 @@
+package addr
+
+import (
+	"github.com/stretchr/testify/assert"
+	"net"
+	"testing"
+)
+
+func TestIsLocal(t *testing.T) {
+	testData := []struct {
+		addr   string
+		expect bool
+	}{
+		{"localhost", true},
+		{"localhost:8080", true},
+		{"127.0.0.1", true},
+		{"127.0.0.1:1001", true},
+		{"80.1.1.1", false},
+	}
+
+	for _, d := range testData {
+		res := IsLocal(d.addr)
+		if res != d.expect {
+			t.Fatalf("expected %t got %t", d.expect, res)
+		}
+	}
+}
+
+func TestExtractor(t *testing.T) {
+	testData := []struct {
+		addr   string
+		expect string
+		parse  bool
+	}{
+		{"127.0.0.1", "127.0.0.1", false},
+		{"10.0.0.1", "10.0.0.1", false},
+		{"", "", true},
+		{"0.0.0.0", "", true},
+		{"[::]", "", true},
+	}
+
+	for _, d := range testData {
+		addr, err := Extract(d.addr)
+		if err != nil {
+			t.Errorf("Unexpected error %v", err)
+		}
+
+		if d.parse {
+			ip := net.ParseIP(addr)
+			if ip == nil {
+				t.Error("Unexpected nil IP")
+			}
+		} else if addr != d.expect {
+			t.Errorf("Expected %s got %s", d.expect, addr)
+		}
+	}
+}
+
+func TestFindIP(t *testing.T) {
+	localhost, _ := net.ResolveIPAddr("ip", "127.0.0.1")
+	localhostIPv6, _ := net.ResolveIPAddr("ip", "::1")
+	privateIP, _ := net.ResolveIPAddr("ip", "10.0.0.1")
+	publicIP, _ := net.ResolveIPAddr("ip", "100.0.0.1")
+	publicIPv6, _ := net.ResolveIPAddr("ip", "2001:0db8:85a3:0000:0000:8a2e:0370:7334")
+
+	testCases := []struct {
+		addrs  []net.Addr
+		ip     net.IP
+		errMsg string
+	}{
+		{
+			addrs:  []net.Addr{},
+			ip:     nil,
+			errMsg: ErrIPNotFound.Error(),
+		},
+		{
+			addrs: []net.Addr{localhost},
+			ip:    localhost.IP,
+		},
+		{
+			addrs: []net.Addr{localhost, localhostIPv6},
+			ip:    localhost.IP,
+		},
+		{
+			addrs: []net.Addr{localhostIPv6},
+			ip:    localhostIPv6.IP,
+		},
+		{
+			addrs: []net.Addr{privateIP, localhost},
+			ip:    privateIP.IP,
+		},
+		{
+			addrs: []net.Addr{privateIP, publicIP, localhost},
+			ip:    privateIP.IP,
+		},
+		{
+			addrs: []net.Addr{publicIP, privateIP, localhost},
+			ip:    privateIP.IP,
+		},
+		{
+			addrs: []net.Addr{publicIP, localhost},
+			ip:    publicIP.IP,
+		},
+		{
+			addrs: []net.Addr{publicIP, localhostIPv6},
+			ip:    publicIP.IP,
+		},
+		{
+			addrs: []net.Addr{localhostIPv6, publicIP},
+			ip:    publicIP.IP,
+		},
+		{
+			addrs: []net.Addr{localhostIPv6, publicIPv6, publicIP},
+			ip:    publicIPv6.IP,
+		},
+		{
+			addrs: []net.Addr{publicIP, publicIPv6},
+			ip:    publicIP.IP,
+		},
+	}
+
+	for _, tc := range testCases {
+		ip, err := findIP(tc.addrs)
+		if tc.errMsg == "" {
+			assert.Nil(t, err)
+			assert.Equal(t, tc.ip.String(), ip.String())
+		} else {
+			assert.NotNil(t, err)
+			assert.Equal(t, tc.errMsg, err.Error())
+		}
+	}
+}
@@ -0,0 +1,16 @@
+// Package backoff provides backoff functionality
+package backoff
+
+import (
+	"math"
+	"time"
+)
+
+// Do is a function x^e multiplied by a factor of 0.1 second.
+// Result is limited to 2 minute.
+func Do(attempts int) time.Duration {
+	if attempts > 13 {
+		return 2 * time.Minute
+	}
+	return time.Duration(math.Pow(float64(attempts), math.E)) * time.Millisecond * 100
+}
@@ -0,0 +1,21 @@
+package buf
+
+import (
+	"bytes"
+)
+
+type buffer struct {
+	*bytes.Buffer
+}
+
+func (b *buffer) Close() error {
+	b.Reset()
+	return nil
+}
+
+func New(b *bytes.Buffer) *buffer {
+	if b == nil {
+		b = bytes.NewBuffer(nil)
+	}
+	return &buffer{b}
+}
@@ -0,0 +1,57 @@
+package grpc
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ServiceMethod converts a gRPC method to a Go method
+// Input:
+// Foo.Bar, /Foo/Bar, /package.Foo/Bar, /a.package.Foo/Bar
+// Output:
+// [Foo, Bar].
+func ServiceMethod(m string) (string, string, error) {
+	if len(m) == 0 {
+		return "", "", fmt.Errorf("malformed method name: %q", m)
+	}
+
+	// grpc method
+	if m[0] == '/' {
+		// [ , Foo, Bar]
+		// [ , package.Foo, Bar]
+		// [ , a.package.Foo, Bar]
+		parts := strings.Split(m, "/")
+		if len(parts) != 3 || len(parts[1]) == 0 || len(parts[2]) == 0 {
+			return "", "", fmt.Errorf("malformed method name: %q", m)
+		}
+		service := strings.Split(parts[1], ".")
+		return service[len(service)-1], parts[2], nil
+	}
+
+	// non grpc method
+	parts := strings.Split(m, ".")
+
+	// expect [Foo, Bar]
+	if len(parts) != 2 {
+		return "", "", fmt.Errorf("malformed method name: %q", m)
+	}
+
+	return parts[0], parts[1], nil
+}
+
+// ServiceFromMethod returns the service
+// /service.Foo/Bar => service.
+func ServiceFromMethod(m string) string {
+	if len(m) == 0 {
+		return m
+	}
+	if m[0] != '/' {
+		return m
+	}
+	parts := strings.Split(m, "/")
+	if len(parts) < 3 {
+		return m
+	}
+	parts = strings.Split(parts[1], ".")
+	return strings.Join(parts[:len(parts)-1], ".")
+}
@@ -0,0 +1,46 @@
+package grpc
+
+import (
+	"testing"
+)
+
+func TestServiceMethod(t *testing.T) {
+	type testCase struct {
+		input   string
+		service string
+		method  string
+		err     bool
+	}
+
+	methods := []testCase{
+		{"Foo.Bar", "Foo", "Bar", false},
+		{"/Foo/Bar", "Foo", "Bar", false},
+		{"/package.Foo/Bar", "Foo", "Bar", false},
+		{"/a.package.Foo/Bar", "Foo", "Bar", false},
+		{"a.package.Foo/Bar", "", "", true},
+		{"/Foo/Bar/Baz", "", "", true},
+		{"Foo.Bar.Baz", "", "", true},
+	}
+	for _, test := range methods {
+		service, method, err := ServiceMethod(test.input)
+		if err != nil && test.err == true {
+			continue
+		}
+		// unexpected error
+		if err != nil && test.err == false {
+			t.Fatalf("unexpected err %v for %+v", err, test)
+		}
+		// expecter error
+		if test.err == true && err == nil {
+			t.Fatalf("expected error for %+v: got service: %s method: %s", test, service, method)
+		}
+
+		if service != test.service {
+			t.Fatalf("wrong service for %+v: got service: %s method: %s", test, service, method)
+		}
+
+		if method != test.method {
+			t.Fatalf("wrong method for %+v: got service: %s method: %s", test, service, method)
+		}
+	}
+}
@@ -0,0 +1,72 @@
+package http
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"go-micro.dev/v6/logger"
+	"go-micro.dev/v6/metadata"
+	"go-micro.dev/v6/registry"
+	"go-micro.dev/v6/selector"
+)
+
+// Write sets the status and body on a http ResponseWriter.
+func Write(w http.ResponseWriter, contentType string, status int, body string) {
+	w.Header().Set("Content-Length", fmt.Sprintf("%v", len(body)))
+	w.Header().Set("Content-Type", contentType)
+	w.WriteHeader(status)
+	fmt.Fprintf(w, `%v`, body)
+}
+
+// WriteBadRequestError sets a 400 status code.
+func WriteBadRequestError(w http.ResponseWriter, err error) {
+	rawBody, err := json.Marshal(map[string]string{
+		"error": err.Error(),
+	})
+	if err != nil {
+		WriteInternalServerError(w, err)
+		return
+	}
+	Write(w, "application/json", 400, string(rawBody))
+}
+
+// WriteInternalServerError sets a 500 status code.
+func WriteInternalServerError(w http.ResponseWriter, err error) {
+	rawBody, err := json.Marshal(map[string]string{
+		"error": err.Error(),
+	})
+	if err != nil {
+		logger.Log(logger.ErrorLevel, err)
+		return
+	}
+	Write(w, "application/json", 500, string(rawBody))
+}
+
+func NewRoundTripper(opts ...Option) http.RoundTripper {
+	options := Options{
+		Registry: registry.DefaultRegistry,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return &roundTripper{
+		rt:   http.DefaultTransport,
+		st:   selector.Random,
+		opts: options,
+	}
+}
+
+// RequestToContext puts the `Authorization` header bearer token into context
+// so calls to services will be authorized.
+func RequestToContext(r *http.Request) context.Context {
+	ctx := context.Background()
+	md := make(metadata.Metadata)
+	for k, v := range r.Header {
+		md[k] = strings.Join(v, ",")
+	}
+	return metadata.NewContext(ctx, md)
+}
@@ -0,0 +1,80 @@
+package http
+
+import (
+	"io"
+	"net"
+	"net/http"
+	"testing"
+
+	"go-micro.dev/v6/registry"
+)
+
+func TestRoundTripper(t *testing.T) {
+	m := registry.NewMemoryRegistry()
+
+	rt := NewRoundTripper(
+		WithRegistry(m),
+	)
+
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(`hello world`))
+	})
+
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer l.Close()
+
+	go http.Serve(l, nil)
+
+	m.Register(&registry.Service{
+		Name: "example.com",
+		Nodes: []*registry.Node{
+			{
+				Id:      "1",
+				Address: l.Addr().String(),
+			},
+		},
+	})
+
+	req, err := http.NewRequest(http.MethodGet, "http://example.com", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	w, err := rt.RoundTrip(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	b, err := io.ReadAll(w.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w.Body.Close()
+
+	if string(b) != "hello world" {
+		t.Fatal("response is", string(b))
+	}
+
+	// test http request
+	c := &http.Client{
+		Transport: rt,
+	}
+
+	rsp, err := c.Get("http://example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	b, err = io.ReadAll(rsp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rsp.Body.Close()
+
+	if string(b) != "hello world" {
+		t.Fatal("response is", string(b))
+	}
+}
@@ -0,0 +1,17 @@
+package http
+
+import (
+	"go-micro.dev/v6/registry"
+)
+
+type Options struct {
+	Registry registry.Registry
+}
+
+type Option func(*Options)
+
+func WithRegistry(r registry.Registry) Option {
+	return func(o *Options) {
+		o.Registry = r
+	}
+}
@@ -0,0 +1,39 @@
+package http
+
+import (
+	"errors"
+	"net/http"
+
+	"go-micro.dev/v6/selector"
+)
+
+type roundTripper struct {
+	rt   http.RoundTripper
+	st   selector.Strategy
+	opts Options
+}
+
+func (r *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	s, err := r.opts.Registry.GetService(req.URL.Host)
+	if err != nil {
+		return nil, err
+	}
+
+	next := r.st(s)
+
+	// rudimentary retry 3 times
+	for i := 0; i < 3; i++ {
+		n, err := next()
+		if err != nil {
+			continue
+		}
+		req.URL.Host = n.Address
+		w, err := r.rt.RoundTrip(req)
+		if err != nil {
+			continue
+		}
+		return w, nil
+	}
+
+	return nil, errors.New("failed request")
+}
@@ -0,0 +1,17 @@
+// Package jitter provides a random jitter
+package jitter
+
+import (
+	"math/rand"
+	"time"
+)
+
+var (
+	r = rand.New(rand.NewSource(time.Now().UnixNano()))
+)
+
+// Do returns a random time to jitter with max cap specified.
+func Do(d time.Duration) time.Duration {
+	v := r.Float64() * float64(d.Nanoseconds())
+	return time.Duration(v)
+}
@@ -0,0 +1,23 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
@@ -0,0 +1,507 @@
+package mdns
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/miekg/dns"
+	"go-micro.dev/v6/logger"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
+)
+
+// ServiceEntry is returned after we query for a service.
+type ServiceEntry struct {
+	Name       string
+	Host       string
+	Info       string
+	AddrV4     net.IP
+	AddrV6     net.IP
+	InfoFields []string
+
+	Addr net.IP // @Deprecated
+
+	Port int
+	TTL  int
+	Type uint16
+
+	hasTXT bool
+	sent   bool
+}
+
+// complete is used to check if we have all the info we need.
+func (s *ServiceEntry) complete() bool {
+	return (len(s.AddrV4) > 0 || len(s.AddrV6) > 0 || len(s.Addr) > 0) && s.Port != 0 && s.hasTXT
+}
+
+// QueryParam is used to customize how a Lookup is performed.
+type QueryParam struct {
+	Context             context.Context      // Context
+	Interface           *net.Interface       // Multicast interface to use
+	Entries             chan<- *ServiceEntry // Entries Channel
+	Service             string               // Service to lookup
+	Domain              string               // Lookup domain, default "local"
+	Timeout             time.Duration        // Lookup timeout, default 1 second. Ignored if Context is provided
+	Type                uint16               // Lookup type, defaults to dns.TypePTR
+	WantUnicastResponse bool                 // Unicast response desired, as per 5.4 in RFC
+}
+
+// DefaultParams is used to return a default set of QueryParam's.
+func DefaultParams(service string) *QueryParam {
+	return &QueryParam{
+		Service:             service,
+		Domain:              "local",
+		Timeout:             time.Second,
+		Entries:             make(chan *ServiceEntry),
+		WantUnicastResponse: false, // TODO(reddaly): Change this default.
+	}
+}
+
+// Query looks up a given service, in a domain, waiting at most
+// for a timeout before finishing the query. The results are streamed
+// to a channel. Sends will not block, so clients should make sure to
+// either read or buffer.
+func Query(params *QueryParam) error {
+	// Create a new client
+	client, err := newClient()
+	if err != nil {
+		return err
+	}
+	defer client.Close()
+
+	// Set the multicast interface
+	if params.Interface != nil {
+		if err := client.setInterface(params.Interface, false); err != nil {
+			return err
+		}
+	}
+
+	// Ensure defaults are set
+	if params.Domain == "" {
+		params.Domain = "local"
+	}
+
+	if params.Context == nil {
+		if params.Timeout == 0 {
+			params.Timeout = time.Second
+		}
+		var cancel context.CancelFunc
+		params.Context, cancel = context.WithTimeout(context.Background(), params.Timeout)
+		defer cancel()
+	}
+
+	// Run the query
+	return client.query(params)
+}
+
+// Listen listens indefinitely for multicast updates.
+func Listen(entries chan<- *ServiceEntry, exit chan struct{}) error {
+	// Create a new client
+	client, err := newClient()
+	if err != nil {
+		return err
+	}
+	defer client.Close()
+
+	_ = client.setInterface(nil, true)
+
+	// Start listening for response packets
+	msgCh := make(chan *dns.Msg, 32)
+
+	go client.recv(client.ipv4UnicastConn, msgCh)
+	go client.recv(client.ipv6UnicastConn, msgCh)
+	go client.recv(client.ipv4MulticastConn, msgCh)
+	go client.recv(client.ipv6MulticastConn, msgCh)
+
+	ip := make(map[string]*ServiceEntry)
+
+	for {
+		select {
+		case <-exit:
+			return nil
+		case <-client.closedCh:
+			return nil
+		case m := <-msgCh:
+			e := messageToEntry(m, ip)
+			if e == nil {
+				continue
+			}
+
+			// Check if this entry is complete
+			if e.complete() {
+				if e.sent {
+					continue
+				}
+				e.sent = true
+				entries <- e
+				ip = make(map[string]*ServiceEntry)
+			} else {
+				// Fire off a node specific query
+				m := new(dns.Msg)
+				m.SetQuestion(e.Name, dns.TypePTR)
+				m.RecursionDesired = false
+				if err := client.sendQuery(m); err != nil {
+					logger.Logf(logger.ErrorLevel, "[mdns] failed to query instance %s: %v", e.Name, err)
+				}
+			}
+		}
+	}
+
+}
+
+// Lookup is the same as Query, however it uses all the default parameters.
+func Lookup(service string, entries chan<- *ServiceEntry) error {
+	params := DefaultParams(service)
+	params.Entries = entries
+	return Query(params)
+}
+
+// Client provides a query interface that can be used to
+// search for service providers using mDNS.
+type client struct {
+	ipv4UnicastConn *net.UDPConn
+	ipv6UnicastConn *net.UDPConn
+
+	ipv4MulticastConn *net.UDPConn
+	ipv6MulticastConn *net.UDPConn
+
+	closedCh  chan struct{} // TODO(reddaly): This doesn't appear to be used.
+	closeLock sync.Mutex
+
+	closed bool
+}
+
+// NewClient creates a new mdns Client that can be used to query
+// for records.
+func newClient() (*client, error) {
+	// TODO(reddaly): At least attempt to bind to the port required in the spec.
+	// Create a IPv4 listener
+	uconn4, err4 := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	uconn6, err6 := net.ListenUDP("udp6", &net.UDPAddr{IP: net.IPv6zero, Port: 0})
+	if err4 != nil && err6 != nil {
+		logger.Logf(logger.ErrorLevel, "[mdns] failed to bind to udp port: %v %v", err4, err6)
+	}
+
+	if uconn4 == nil && uconn6 == nil {
+		return nil, fmt.Errorf("failed to bind to any unicast udp port")
+	}
+
+	if uconn4 == nil {
+		uconn4 = &net.UDPConn{}
+	}
+
+	if uconn6 == nil {
+		uconn6 = &net.UDPConn{}
+	}
+
+	mconn4, err4 := net.ListenUDP("udp4", mdnsWildcardAddrIPv4)
+	mconn6, err6 := net.ListenUDP("udp6", mdnsWildcardAddrIPv6)
+	if err4 != nil && err6 != nil {
+		logger.Logf(logger.ErrorLevel, "[mdns] failed to bind to udp port: %v %v", err4, err6)
+	}
+
+	if mconn4 == nil && mconn6 == nil {
+		return nil, fmt.Errorf("failed to bind to any multicast udp port")
+	}
+
+	if mconn4 == nil {
+		mconn4 = &net.UDPConn{}
+	}
+
+	if mconn6 == nil {
+		mconn6 = &net.UDPConn{}
+	}
+
+	p1 := ipv4.NewPacketConn(mconn4)
+	p2 := ipv6.NewPacketConn(mconn6)
+	_ = p1.SetMulticastLoopback(true)
+	_ = p2.SetMulticastLoopback(true)
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	var errCount1, errCount2 int
+
+	for _, iface := range ifaces {
+		if err := p1.JoinGroup(&iface, &net.UDPAddr{IP: mdnsGroupIPv4}); err != nil {
+			errCount1++
+		}
+		if err := p2.JoinGroup(&iface, &net.UDPAddr{IP: mdnsGroupIPv6}); err != nil {
+			errCount2++
+		}
+	}
+
+	if len(ifaces) == errCount1 && len(ifaces) == errCount2 {
+		return nil, fmt.Errorf("failed to join multicast group on all interfaces")
+	}
+
+	c := &client{
+		ipv4MulticastConn: mconn4,
+		ipv6MulticastConn: mconn6,
+		ipv4UnicastConn:   uconn4,
+		ipv6UnicastConn:   uconn6,
+		closedCh:          make(chan struct{}),
+	}
+	return c, nil
+}
+
+// Close is used to cleanup the client.
+func (c *client) Close() error {
+	c.closeLock.Lock()
+	defer c.closeLock.Unlock()
+
+	if c.closed {
+		return nil
+	}
+	c.closed = true
+
+	close(c.closedCh)
+
+	if c.ipv4UnicastConn != nil {
+		c.ipv4UnicastConn.Close()
+	}
+	if c.ipv6UnicastConn != nil {
+		c.ipv6UnicastConn.Close()
+	}
+	if c.ipv4MulticastConn != nil {
+		c.ipv4MulticastConn.Close()
+	}
+	if c.ipv6MulticastConn != nil {
+		c.ipv6MulticastConn.Close()
+	}
+
+	return nil
+}
+
+// setInterface is used to set the query interface, uses system
+// default if not provided.
+func (c *client) setInterface(iface *net.Interface, loopback bool) error {
+	p := ipv4.NewPacketConn(c.ipv4UnicastConn)
+	if err := p.JoinGroup(iface, &net.UDPAddr{IP: mdnsGroupIPv4}); err != nil {
+		return err
+	}
+	p2 := ipv6.NewPacketConn(c.ipv6UnicastConn)
+	if err := p2.JoinGroup(iface, &net.UDPAddr{IP: mdnsGroupIPv6}); err != nil {
+		return err
+	}
+	p = ipv4.NewPacketConn(c.ipv4MulticastConn)
+	if err := p.JoinGroup(iface, &net.UDPAddr{IP: mdnsGroupIPv4}); err != nil {
+		return err
+	}
+	p2 = ipv6.NewPacketConn(c.ipv6MulticastConn)
+	if err := p2.JoinGroup(iface, &net.UDPAddr{IP: mdnsGroupIPv6}); err != nil {
+		return err
+	}
+
+	if loopback {
+		_ = p.SetMulticastLoopback(true)
+		_ = p2.SetMulticastLoopback(true)
+	}
+
+	return nil
+}
+
+// query is used to perform a lookup and stream results.
+func (c *client) query(params *QueryParam) error {
+	// Create the service name
+	serviceAddr := fmt.Sprintf("%s.%s.", trimDot(params.Service), trimDot(params.Domain))
+
+	// Start listening for response packets
+	msgCh := make(chan *dns.Msg, 32)
+	go c.recv(c.ipv4UnicastConn, msgCh)
+	go c.recv(c.ipv6UnicastConn, msgCh)
+	go c.recv(c.ipv4MulticastConn, msgCh)
+	go c.recv(c.ipv6MulticastConn, msgCh)
+
+	// Send the query
+	m := new(dns.Msg)
+	if params.Type == dns.TypeNone {
+		m.SetQuestion(serviceAddr, dns.TypePTR)
+	} else {
+		m.SetQuestion(serviceAddr, params.Type)
+	}
+	// RFC 6762, section 18.12.  Repurposing of Top Bit of qclass in Question
+	// Section
+	//
+	// In the Question Section of a Multicast DNS query, the top bit of the qclass
+	// field is used to indicate that unicast responses are preferred for this
+	// particular question.  (See Section 5.4.)
+	if params.WantUnicastResponse {
+		m.Question[0].Qclass |= 1 << 15
+	}
+	m.RecursionDesired = false
+	if err := c.sendQuery(m); err != nil {
+		return err
+	}
+
+	// Map the in-progress responses
+	inprogress := make(map[string]*ServiceEntry)
+
+	for {
+		select {
+		case resp := <-msgCh:
+			inp := messageToEntry(resp, inprogress)
+
+			if inp == nil {
+				continue
+			}
+			if len(resp.Question) == 0 || resp.Question[0].Name != m.Question[0].Name {
+				// discard anything which we've not asked for
+				continue
+			}
+
+			// Check if this entry is complete
+			if inp.complete() {
+				if inp.sent {
+					continue
+				}
+
+				inp.sent = true
+				select {
+				case params.Entries <- inp:
+				case <-params.Context.Done():
+					return nil
+				}
+			} else {
+				// Fire off a node specific query
+				m := new(dns.Msg)
+				m.SetQuestion(inp.Name, inp.Type)
+				m.RecursionDesired = false
+				if err := c.sendQuery(m); err != nil {
+					logger.Logf(logger.ErrorLevel, "[mdns] failed to query instance %s: %v", inp.Name, err)
+				}
+			}
+		case <-params.Context.Done():
+			return nil
+		}
+	}
+}
+
+// sendQuery is used to multicast a query out.
+func (c *client) sendQuery(q *dns.Msg) error {
+	buf, err := q.Pack()
+	if err != nil {
+		return err
+	}
+	if c.ipv4UnicastConn != nil {
+		_, _ = c.ipv4UnicastConn.WriteToUDP(buf, ipv4Addr)
+	}
+	if c.ipv6UnicastConn != nil {
+		_, _ = c.ipv6UnicastConn.WriteToUDP(buf, ipv6Addr)
+	}
+	return nil
+}
+
+// recv is used to receive until we get a shutdown.
+func (c *client) recv(l *net.UDPConn, msgCh chan *dns.Msg) {
+	if l == nil {
+		return
+	}
+	buf := make([]byte, 65536)
+	for {
+		c.closeLock.Lock()
+		if c.closed {
+			c.closeLock.Unlock()
+			return
+		}
+		c.closeLock.Unlock()
+		n, err := l.Read(buf)
+		if err != nil {
+			continue
+		}
+		msg := new(dns.Msg)
+		if err := msg.Unpack(buf[:n]); err != nil {
+			continue
+		}
+		select {
+		case msgCh <- msg:
+		case <-c.closedCh:
+			return
+		}
+	}
+}
+
+// ensureName is used to ensure the named node is in progress.
+func ensureName(inprogress map[string]*ServiceEntry, name string, typ uint16) *ServiceEntry {
+	if inp, ok := inprogress[name]; ok {
+		return inp
+	}
+	inp := &ServiceEntry{
+		Name: name,
+		Type: typ,
+	}
+	inprogress[name] = inp
+	return inp
+}
+
+// alias is used to setup an alias between two entries.
+func alias(inprogress map[string]*ServiceEntry, src, dst string, typ uint16) {
+	srcEntry := ensureName(inprogress, src, typ)
+	inprogress[dst] = srcEntry
+}
+
+func messageToEntry(m *dns.Msg, inprogress map[string]*ServiceEntry) *ServiceEntry {
+	var inp *ServiceEntry
+
+	for _, answer := range append(m.Answer, m.Extra...) {
+		// TODO(reddaly): Check that response corresponds to serviceAddr?
+		switch rr := answer.(type) {
+		case *dns.PTR:
+			// Create new entry for this
+			inp = ensureName(inprogress, rr.Ptr, rr.Hdr.Rrtype)
+			if inp.complete() {
+				continue
+			}
+		case *dns.SRV:
+			// Check for a target mismatch
+			if rr.Target != rr.Hdr.Name {
+				alias(inprogress, rr.Hdr.Name, rr.Target, rr.Hdr.Rrtype)
+			}
+
+			// Get the port
+			inp = ensureName(inprogress, rr.Hdr.Name, rr.Hdr.Rrtype)
+			if inp.complete() {
+				continue
+			}
+			inp.Host = rr.Target
+			inp.Port = int(rr.Port)
+		case *dns.TXT:
+			// Pull out the txt
+			inp = ensureName(inprogress, rr.Hdr.Name, rr.Hdr.Rrtype)
+			if inp.complete() {
+				continue
+			}
+			inp.Info = strings.Join(rr.Txt, "|")
+			inp.InfoFields = rr.Txt
+			inp.hasTXT = true
+		case *dns.A:
+			// Pull out the IP
+			inp = ensureName(inprogress, rr.Hdr.Name, rr.Hdr.Rrtype)
+			if inp.complete() {
+				continue
+			}
+			inp.Addr = rr.A // @Deprecated
+			inp.AddrV4 = rr.A
+		case *dns.AAAA:
+			// Pull out the IP
+			inp = ensureName(inprogress, rr.Hdr.Name, rr.Hdr.Rrtype)
+			if inp.complete() {
+				continue
+			}
+			inp.Addr = rr.AAAA // @Deprecated
+			inp.AddrV6 = rr.AAAA
+		}
+
+		if inp != nil {
+			inp.TTL = int(answer.Header().Ttl)
+		}
+	}
+
+	return inp
+}
@@ -0,0 +1,85 @@
+package mdns
+
+import "github.com/miekg/dns"
+
+// DNSSDService is a service that complies with the DNS-SD (RFC 6762) and MDNS
+// (RFC 6762) specs for local, multicast-DNS-based discovery.
+//
+// DNSSDService implements the Zone interface and wraps an MDNSService instance.
+// To deploy an mDNS service that is compliant with DNS-SD, it's recommended to
+// register only the wrapped instance with the server.
+//
+// Example usage:
+//
+//	    service := &mdns.DNSSDService{
+//	      MDNSService: &mdns.MDNSService{
+//		       Instance: "My Foobar Service",
+//		       Service: "_foobar._tcp",
+//		       Port:    8000,
+//	       }
+//	     }
+//	     server, err := mdns.NewServer(&mdns.Config{Zone: service})
+//	     if err != nil {
+//	       log.Fatalf("Error creating server: %v", err)
+//	     }
+//	     defer server.Shutdown()
+type DNSSDService struct {
+	MDNSService *MDNSService
+}
+
+// Records returns DNS records in response to a DNS question.
+//
+// This function returns the DNS response of the underlying MDNSService
+// instance.  It also returns a PTR record for a request for "
+// _services._dns-sd._udp.<Domain>", as described in section 9 of RFC 6763
+// ("Service Type Enumeration"), to allow browsing of the underlying MDNSService
+// instance.
+func (s *DNSSDService) Records(q dns.Question) []dns.RR {
+	var recs []dns.RR
+	if q.Name == "_services._dns-sd._udp."+s.MDNSService.Domain+"." {
+		recs = s.dnssdMetaQueryRecords(q)
+	}
+	return append(recs, s.MDNSService.Records(q)...)
+}
+
+// dnssdMetaQueryRecords returns the DNS records in response to a "meta-query"
+// issued to browse for DNS-SD services, as per section 9. of RFC6763.
+//
+// A meta-query has a name of the form "_services._dns-sd._udp.<Domain>" where
+// Domain is a fully-qualified domain, such as "local.".
+func (s *DNSSDService) dnssdMetaQueryRecords(q dns.Question) []dns.RR {
+	// Intended behavior, as described in the RFC:
+	//     ...it may be useful for network administrators to find the list of
+	//     advertised service types on the network, even if those Service Names
+	//     are just opaque identifiers and not particularly informative in
+	//     isolation.
+	//
+	//     For this purpose, a special meta-query is defined.  A DNS query for PTR
+	//     records with the name "_services._dns-sd._udp.<Domain>" yields a set of
+	//     PTR records, where the rdata of each PTR record is the two-abel
+	//     <Service> name, plus the same domain, e.g., "_http._tcp.<Domain>".
+	//     Including the domain in the PTR rdata allows for slightly better name
+	//     compression in Unicast DNS responses, but only the first two labels are
+	//     relevant for the purposes of service type enumeration.  These two-label
+	//     service types can then be used to construct subsequent Service Instance
+	//     Enumeration PTR queries, in this <Domain> or others, to discover
+	//     instances of that service type.
+	return []dns.RR{
+		&dns.PTR{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypePTR,
+				Class:  dns.ClassINET,
+				Ttl:    defaultTTL,
+			},
+			Ptr: s.MDNSService.serviceAddr,
+		},
+	}
+}
+
+// Announcement returns DNS records that should be broadcast during the initial
+// availability of the service, as described in section 8.3 of RFC 6762.
+// TODO(reddaly): Add this when Announcement is added to the mdns.Zone interface.
+// func (s *DNSSDService) Announcement() []dns.RR {
+//	return s.MDNSService.Announcement()
+//}
@@ -0,0 +1,39 @@
+package mdns
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/miekg/dns"
+)
+
+func TestDNSSDServiceRecords(t *testing.T) {
+	s := &DNSSDService{
+		MDNSService: &MDNSService{
+			serviceAddr: "_foobar._tcp.local.",
+			Domain:      "local",
+		},
+	}
+	q := dns.Question{
+		Name:   "_services._dns-sd._udp.local.",
+		Qtype:  dns.TypePTR,
+		Qclass: dns.ClassINET,
+	}
+	recs := s.Records(q)
+	if got, want := len(recs), 1; got != want {
+		t.Fatalf("s.Records(%v) returned %v records, want %v", q, got, want)
+	}
+
+	want := dns.RR(&dns.PTR{
+		Hdr: dns.RR_Header{
+			Name:   "_services._dns-sd._udp.local.",
+			Rrtype: dns.TypePTR,
+			Class:  dns.ClassINET,
+			Ttl:    defaultTTL,
+		},
+		Ptr: "_foobar._tcp.local.",
+	})
+	if got := recs[0]; !reflect.DeepEqual(got, want) {
+		t.Errorf("s.Records()[0] = %v, want %v", got, want)
+	}
+}
@@ -0,0 +1,518 @@
+package mdns
+
+import (
+	"fmt"
+	"math/rand"
+	"net"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/miekg/dns"
+	log "go-micro.dev/v6/logger"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
+)
+
+var (
+	mdnsGroupIPv4 = net.ParseIP("224.0.0.251")
+	mdnsGroupIPv6 = net.ParseIP("ff02::fb")
+
+	// mDNS wildcard addresses.
+	mdnsWildcardAddrIPv4 = &net.UDPAddr{
+		IP:   net.ParseIP("224.0.0.0"),
+		Port: 5353,
+	}
+	mdnsWildcardAddrIPv6 = &net.UDPAddr{
+		IP:   net.ParseIP("ff02::"),
+		Port: 5353,
+	}
+
+	// mDNS endpoint addresses.
+	ipv4Addr = &net.UDPAddr{
+		IP:   mdnsGroupIPv4,
+		Port: 5353,
+	}
+	ipv6Addr = &net.UDPAddr{
+		IP:   mdnsGroupIPv6,
+		Port: 5353,
+	}
+)
+
+// GetMachineIP is a func which returns the outbound IP of this machine.
+// Used by the server to determine whether to attempt send the response on a local address.
+type GetMachineIP func() net.IP
+
+// Config is used to configure the mDNS server.
+type Config struct {
+	// Zone must be provided to support responding to queries
+	Zone Zone
+
+	// Iface if provided binds the multicast listener to the given
+	// interface. If not provided, the system default multicase interface
+	// is used.
+	Iface *net.Interface
+
+	// GetMachineIP is a function to return the IP of the local machine
+	GetMachineIP GetMachineIP
+
+	// Port If it is not 0, replace the port 5353 with this port number.
+	Port int
+
+	// LocalhostChecking if enabled asks the server to also send responses to 0.0.0.0 if the target IP
+	// is this host (as defined by GetMachineIP). Useful in case machine is on a VPN which blocks comms on non standard ports
+	LocalhostChecking bool
+}
+
+// Server is an mDNS server used to listen for mDNS queries and respond if we
+// have a matching local record.
+type Server struct {
+	config *Config
+
+	ipv4List *net.UDPConn
+	ipv6List *net.UDPConn
+
+	shutdownCh chan struct{}
+
+	outboundIP net.IP
+	wg         sync.WaitGroup
+
+	shutdownLock sync.Mutex
+
+	shutdown bool
+}
+
+// NewServer is used to create a new mDNS server from a config.
+func NewServer(config *Config) (*Server, error) {
+	setCustomPort(config.Port)
+
+	// Create the listeners
+	// Create wildcard connections (because :5353 can be already taken by other apps)
+	ipv4List, _ := net.ListenUDP("udp4", mdnsWildcardAddrIPv4)
+	ipv6List, _ := net.ListenUDP("udp6", mdnsWildcardAddrIPv6)
+	if ipv4List == nil && ipv6List == nil {
+		return nil, fmt.Errorf("[ERR] mdns: Failed to bind to any udp port")
+	}
+
+	if ipv4List == nil {
+		ipv4List = &net.UDPConn{}
+	}
+	if ipv6List == nil {
+		ipv6List = &net.UDPConn{}
+	}
+
+	// Join multicast groups to receive announcements
+	p1 := ipv4.NewPacketConn(ipv4List)
+	p2 := ipv6.NewPacketConn(ipv6List)
+	_ = p1.SetMulticastLoopback(true)
+	_ = p2.SetMulticastLoopback(true)
+
+	if config.Iface != nil {
+		if err := p1.JoinGroup(config.Iface, &net.UDPAddr{IP: mdnsGroupIPv4}); err != nil {
+			return nil, err
+		}
+		if err := p2.JoinGroup(config.Iface, &net.UDPAddr{IP: mdnsGroupIPv6}); err != nil {
+			return nil, err
+		}
+	} else {
+		ifaces, err := net.Interfaces()
+		if err != nil {
+			return nil, err
+		}
+		errCount1, errCount2 := 0, 0
+		for _, iface := range ifaces {
+			if err := p1.JoinGroup(&iface, &net.UDPAddr{IP: mdnsGroupIPv4}); err != nil {
+				errCount1++
+			}
+			if err := p2.JoinGroup(&iface, &net.UDPAddr{IP: mdnsGroupIPv6}); err != nil {
+				errCount2++
+			}
+		}
+		if len(ifaces) == errCount1 && len(ifaces) == errCount2 {
+			return nil, fmt.Errorf("failed to join multicast group on all interfaces")
+		}
+	}
+
+	ipFunc := getOutboundIP
+	if config.GetMachineIP != nil {
+		ipFunc = config.GetMachineIP
+	}
+
+	s := &Server{
+		config:     config,
+		ipv4List:   ipv4List,
+		ipv6List:   ipv6List,
+		shutdownCh: make(chan struct{}),
+		outboundIP: ipFunc(),
+	}
+
+	go s.recv(s.ipv4List)
+	go s.recv(s.ipv6List)
+
+	s.wg.Add(1)
+	go s.probe()
+
+	return s, nil
+}
+
+// Shutdown is used to shutdown the listener.
+func (s *Server) Shutdown() error {
+	s.shutdownLock.Lock()
+	defer s.shutdownLock.Unlock()
+
+	if s.shutdown {
+		return nil
+	}
+
+	s.shutdown = true
+	close(s.shutdownCh)
+	_ = s.unregister()
+
+	if s.ipv4List != nil {
+		s.ipv4List.Close()
+	}
+	if s.ipv6List != nil {
+		s.ipv6List.Close()
+	}
+
+	s.wg.Wait()
+	return nil
+}
+
+// recv is a long running routine to receive packets from an interface.
+func (s *Server) recv(c *net.UDPConn) {
+	if c == nil {
+		return
+	}
+	buf := make([]byte, 65536)
+	for {
+		s.shutdownLock.Lock()
+		if s.shutdown {
+			s.shutdownLock.Unlock()
+			return
+		}
+		s.shutdownLock.Unlock()
+		n, from, err := c.ReadFrom(buf)
+		if err != nil {
+			continue
+		}
+		if err := s.parsePacket(buf[:n], from); err != nil {
+			log.Errorf("[ERR] mdns: Failed to handle query: %v", err)
+		}
+	}
+}
+
+// parsePacket is used to parse an incoming packet.
+func (s *Server) parsePacket(packet []byte, from net.Addr) error {
+	var msg dns.Msg
+	if err := msg.Unpack(packet); err != nil {
+		log.Errorf("[ERR] mdns: Failed to unpack packet: %v", err)
+		return err
+	}
+	// TODO: This is a bit of a hack
+	// We decided to ignore some mDNS answers for the time being
+	// See: https://tools.ietf.org/html/rfc6762#section-7.2
+	msg.Truncated = false
+	return s.handleQuery(&msg, from)
+}
+
+// handleQuery is used to handle an incoming query.
+func (s *Server) handleQuery(query *dns.Msg, from net.Addr) error {
+	if query.Opcode != dns.OpcodeQuery {
+		// "In both multicast query and multicast response messages, the OPCODE MUST
+		// be zero on transmission (only standard queries are currently supported
+		// over multicast).  Multicast DNS messages received with an OPCODE other
+		// than zero MUST be silently ignored."  Note: OpcodeQuery == 0
+		return fmt.Errorf("mdns: received query with non-zero Opcode %v: %v", query.Opcode, *query)
+	}
+	if query.Rcode != 0 {
+		// "In both multicast query and multicast response messages, the Response
+		// Code MUST be zero on transmission.  Multicast DNS messages received with
+		// non-zero Response Codes MUST be silently ignored."
+		return fmt.Errorf("mdns: received query with non-zero Rcode %v: %v", query.Rcode, *query)
+	}
+
+	// TODO(reddaly): Handle "TC (Truncated) Bit":
+	//    In query messages, if the TC bit is set, it means that additional
+	//    Known-Answer records may be following shortly.  A responder SHOULD
+	//    record this fact, and wait for those additional Known-Answer records,
+	//    before deciding whether to respond.  If the TC bit is clear, it means
+	//    that the querying host has no additional Known Answers.
+	if query.Truncated {
+		return fmt.Errorf("[ERR] mdns: support for DNS requests with high truncated bit not implemented: %v", *query)
+	}
+
+	var unicastAnswer, multicastAnswer []dns.RR
+
+	// Handle each question
+	for _, q := range query.Question {
+		mrecs, urecs := s.handleQuestion(q)
+		multicastAnswer = append(multicastAnswer, mrecs...)
+		unicastAnswer = append(unicastAnswer, urecs...)
+	}
+
+	// See section 18 of RFC 6762 for rules about DNS headers.
+	resp := func(unicast bool) *dns.Msg {
+		// 18.1: ID (Query Identifier)
+		// 0 for multicast response, query.Id for unicast response
+		id := uint16(0)
+		if unicast {
+			id = query.Id
+		}
+
+		var answer []dns.RR
+		if unicast {
+			answer = unicastAnswer
+		} else {
+			answer = multicastAnswer
+		}
+		if len(answer) == 0 {
+			return nil
+		}
+
+		return &dns.Msg{
+			MsgHdr: dns.MsgHdr{
+				Id: id,
+
+				// 18.2: QR (Query/Response) Bit - must be set to 1 in response.
+				Response: true,
+
+				// 18.3: OPCODE - must be zero in response (OpcodeQuery == 0)
+				Opcode: dns.OpcodeQuery,
+
+				// 18.4: AA (Authoritative Answer) Bit - must be set to 1
+				Authoritative: true,
+
+				// The following fields must all be set to 0:
+				// 18.5: TC (TRUNCATED) Bit
+				// 18.6: RD (Recursion Desired) Bit
+				// 18.7: RA (Recursion Available) Bit
+				// 18.8: Z (Zero) Bit
+				// 18.9: AD (Authentic Data) Bit
+				// 18.10: CD (Checking Disabled) Bit
+				// 18.11: RCODE (Response Code)
+			},
+			// 18.12 pertains to questions (handled by handleQuestion)
+			// 18.13 pertains to resource records (handled by handleQuestion)
+
+			// 18.14: Name Compression - responses should be compressed (though see
+			// caveats in the RFC), so set the Compress bit (part of the dns library
+			// API, not part of the DNS packet) to true.
+			Compress: true,
+			Question: query.Question,
+			Answer:   answer,
+		}
+	}
+
+	if mresp := resp(false); mresp != nil {
+		if err := s.sendResponse(mresp, from); err != nil {
+			return fmt.Errorf("mdns: error sending multicast response: %v", err)
+		}
+	}
+	if uresp := resp(true); uresp != nil {
+		if err := s.sendResponse(uresp, from); err != nil {
+			return fmt.Errorf("mdns: error sending unicast response: %v", err)
+		}
+	}
+	return nil
+}
+
+// handleQuestion is used to handle an incoming question
+//
+// The response to a question may be transmitted over multicast, unicast, or
+// both.  The return values are DNS records for each transmission type.
+func (s *Server) handleQuestion(q dns.Question) (multicastRecs, unicastRecs []dns.RR) {
+	records := s.config.Zone.Records(q)
+	if len(records) == 0 {
+		return nil, nil
+	}
+
+	// Handle unicast and multicast responses.
+	// TODO(reddaly): The decision about sending over unicast vs. multicast is not
+	// yet fully compliant with RFC 6762.  For example, the unicast bit should be
+	// ignored if the records in question are close to TTL expiration.  For now,
+	// we just use the unicast bit to make the decision, as per the spec:
+	//     RFC 6762, section 18.12.  Repurposing of Top Bit of qclass in Question
+	//     Section
+	//
+	//     In the Question Section of a Multicast DNS query, the top bit of the
+	//     qclass field is used to indicate that unicast responses are preferred
+	//     for this particular question.  (See Section 5.4.)
+	if q.Qclass&(1<<15) != 0 {
+		return nil, records
+	}
+	return records, nil
+}
+
+func (s *Server) probe() {
+	defer s.wg.Done()
+
+	sd, ok := s.config.Zone.(*MDNSService)
+	if !ok {
+		return
+	}
+
+	name := fmt.Sprintf("%s.%s.%s.", sd.Instance, trimDot(sd.Service), trimDot(sd.Domain))
+
+	q := new(dns.Msg)
+	q.SetQuestion(name, dns.TypePTR)
+	q.RecursionDesired = false
+
+	srv := &dns.SRV{
+		Hdr: dns.RR_Header{
+			Name:   name,
+			Rrtype: dns.TypeSRV,
+			Class:  dns.ClassINET,
+			Ttl:    defaultTTL,
+		},
+		Priority: 0,
+		Weight:   0,
+		Port:     uint16(sd.Port),
+		Target:   sd.HostName,
+	}
+	txt := &dns.TXT{
+		Hdr: dns.RR_Header{
+			Name:   name,
+			Rrtype: dns.TypeTXT,
+			Class:  dns.ClassINET,
+			Ttl:    defaultTTL,
+		},
+		Txt: sd.TXT,
+	}
+	q.Ns = []dns.RR{srv, txt}
+
+	randomizer := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+	for i := 0; i < 3; i++ {
+		if err := s.SendMulticast(q); err != nil {
+			log.Errorf("[ERR] mdns: failed to send probe:", err.Error())
+		}
+		time.Sleep(time.Duration(randomizer.Intn(250)) * time.Millisecond)
+	}
+
+	resp := new(dns.Msg)
+	resp.Response = true
+
+	// set for query
+	q.SetQuestion(name, dns.TypeANY)
+
+	resp.Answer = append(resp.Answer, s.config.Zone.Records(q.Question[0])...)
+
+	// reset
+	q.SetQuestion(name, dns.TypePTR)
+
+	// From RFC6762
+	//    The Multicast DNS responder MUST send at least two unsolicited
+	//    responses, one second apart. To provide increased robustness against
+	//    packet loss, a responder MAY send up to eight unsolicited responses,
+	//    provided that the interval between unsolicited responses increases by
+	//    at least a factor of two with every response sent.
+	timeout := 1 * time.Second
+	timer := time.NewTimer(timeout)
+	for i := 0; i < 3; i++ {
+		if err := s.SendMulticast(resp); err != nil {
+			log.Errorf("[ERR] mdns: failed to send announcement:", err.Error())
+		}
+		select {
+		case <-timer.C:
+			timeout *= 2
+			timer.Reset(timeout)
+		case <-s.shutdownCh:
+			timer.Stop()
+			return
+		}
+	}
+}
+
+// SendMulticast us used to send a multicast response packet.
+func (s *Server) SendMulticast(msg *dns.Msg) error {
+	buf, err := msg.Pack()
+	if err != nil {
+		return err
+	}
+	if s.ipv4List != nil {
+		_, _ = s.ipv4List.WriteToUDP(buf, ipv4Addr)
+	}
+	if s.ipv6List != nil {
+		_, _ = s.ipv6List.WriteToUDP(buf, ipv6Addr)
+	}
+	return nil
+}
+
+// sendResponse is used to send a response packet.
+func (s *Server) sendResponse(resp *dns.Msg, from net.Addr) error {
+	// TODO(reddaly): Respect the unicast argument, and allow sending responses
+	// over multicast.
+	buf, err := resp.Pack()
+	if err != nil {
+		return err
+	}
+
+	// Determine the socket to send from
+	addr := from.(*net.UDPAddr)
+	conn := s.ipv4List
+	backupTarget := net.IPv4zero
+
+	if addr.IP.To4() == nil {
+		conn = s.ipv6List
+		backupTarget = net.IPv6zero
+	}
+	_, err = conn.WriteToUDP(buf, addr)
+	// If the address we're responding to is this machine then we can also attempt sending on 0.0.0.0
+	// This covers the case where this machine is using a VPN and certain ports are blocked so the response never gets there
+	// Sending two responses is OK
+	if s.config.LocalhostChecking && addr.IP.Equal(s.outboundIP) {
+		// ignore any errors, this is best efforts
+		_, _ = conn.WriteToUDP(buf, &net.UDPAddr{IP: backupTarget, Port: addr.Port})
+	}
+	return err
+}
+
+func (s *Server) unregister() error {
+	sd, ok := s.config.Zone.(*MDNSService)
+	if !ok {
+		return nil
+	}
+
+	atomic.StoreUint32(&sd.TTL, 0)
+	name := fmt.Sprintf("%s.%s.%s.", sd.Instance, trimDot(sd.Service), trimDot(sd.Domain))
+
+	q := new(dns.Msg)
+	q.SetQuestion(name, dns.TypeANY)
+
+	resp := new(dns.Msg)
+	resp.Response = true
+	resp.Answer = append(resp.Answer, s.config.Zone.Records(q.Question[0])...)
+
+	return s.SendMulticast(resp)
+}
+
+func setCustomPort(port int) {
+	if port != 0 {
+		if mdnsWildcardAddrIPv4.Port != port {
+			mdnsWildcardAddrIPv4.Port = port
+		}
+		if mdnsWildcardAddrIPv6.Port != port {
+			mdnsWildcardAddrIPv6.Port = port
+		}
+		if ipv4Addr.Port != port {
+			ipv4Addr.Port = port
+		}
+		if ipv6Addr.Port != port {
+			ipv6Addr.Port = port
+		}
+	}
+}
+
+func getOutboundIP() net.IP {
+	conn, err := net.Dial("udp", "8.8.8.8:80")
+	if err != nil {
+		// no net connectivity maybe so fallback
+		return nil
+	}
+	defer conn.Close()
+
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+
+	return localAddr.IP
+}
@@ -0,0 +1,61 @@
+package mdns
+
+import (
+	"testing"
+	"time"
+)
+
+func TestServer_StartStop(t *testing.T) {
+	s := makeService(t)
+	serv, err := NewServer(&Config{Zone: s, LocalhostChecking: true})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	defer serv.Shutdown()
+}
+
+func TestServer_Lookup(t *testing.T) {
+	serv, err := NewServer(&Config{Zone: makeServiceWithServiceName(t, "_foobar._tcp"), LocalhostChecking: true})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	defer serv.Shutdown()
+
+	entries := make(chan *ServiceEntry, 1)
+	found := false
+	doneCh := make(chan struct{})
+	go func() {
+		select {
+		case e := <-entries:
+			if e.Name != "hostname._foobar._tcp.local." {
+				t.Errorf("bad: %v", e)
+			}
+			if e.Port != 80 {
+				t.Errorf("bad: %v", e)
+			}
+			if e.Info != "Local web server" {
+				t.Errorf("bad: %v", e)
+			}
+			found = true
+
+		case <-time.After(80 * time.Millisecond):
+			t.Errorf("timeout")
+		}
+		close(doneCh)
+	}()
+
+	params := &QueryParam{
+		Service: "_foobar._tcp",
+		Domain:  "local",
+		Timeout: 50 * time.Millisecond,
+		Entries: entries,
+	}
+	err = Query(params)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	<-doneCh
+	if !found {
+		t.Fatalf("record not found")
+	}
+}
@@ -0,0 +1,309 @@
+package mdns
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strings"
+	"sync/atomic"
+
+	"github.com/miekg/dns"
+)
+
+const (
+	// defaultTTL is the default TTL value in returned DNS records in seconds.
+	defaultTTL = 120
+)
+
+// Zone is the interface used to integrate with the server and
+// to serve records dynamically.
+type Zone interface {
+	// Records returns DNS records in response to a DNS question.
+	Records(q dns.Question) []dns.RR
+}
+
+// MDNSService is used to export a named service by implementing a Zone.
+type MDNSService struct {
+	Instance     string   // Instance name (e.g. "hostService name")
+	Service      string   // Service name (e.g. "_http._tcp.")
+	Domain       string   // If blank, assumes "local"
+	HostName     string   // Host machine DNS name (e.g. "mymachine.net.")
+	serviceAddr  string   // Fully qualified service address
+	instanceAddr string   // Fully qualified instance address
+	enumAddr     string   // _services._dns-sd._udp.<domain>
+	IPs          []net.IP // IP addresses for the service's host
+	TXT          []string // Service TXT records
+	Port         int      // Service Port
+	TTL          uint32
+}
+
+// validateFQDN returns an error if the passed string is not a fully qualified
+// hdomain name (more specifically, a hostname).
+func validateFQDN(s string) error {
+	if len(s) == 0 {
+		return fmt.Errorf("FQDN must not be blank")
+	}
+	if s[len(s)-1] != '.' {
+		return fmt.Errorf("FQDN must end in period: %s", s)
+	}
+	// TODO(reddaly): Perform full validation.
+
+	return nil
+}
+
+// NewMDNSService returns a new instance of MDNSService.
+//
+// If domain, hostName, or ips is set to the zero value, then a default value
+// will be inferred from the operating system.
+//
+// TODO(reddaly): This interface may need to change to account for "unique
+// record" conflict rules of the mDNS protocol.  Upon startup, the server should
+// check to ensure that the instance name does not conflict with other instance
+// names, and, if required, select a new name.  There may also be conflicting
+// hostName A/AAAA records.
+func NewMDNSService(instance, service, domain, hostName string, port int, ips []net.IP, txt []string) (*MDNSService, error) {
+	// Sanity check inputs
+	if instance == "" {
+		return nil, fmt.Errorf("missing service instance name")
+	}
+	if service == "" {
+		return nil, fmt.Errorf("missing service name")
+	}
+	if port == 0 {
+		return nil, fmt.Errorf("missing service port")
+	}
+
+	// Set default domain
+	if domain == "" {
+		domain = "local."
+	}
+	if err := validateFQDN(domain); err != nil {
+		return nil, fmt.Errorf("domain %q is not a fully-qualified domain name: %v", domain, err)
+	}
+
+	// Get host information if no host is specified.
+	if hostName == "" {
+		var err error
+		hostName, err = os.Hostname()
+		if err != nil {
+			return nil, fmt.Errorf("could not determine host: %v", err)
+		}
+		hostName = fmt.Sprintf("%s.", hostName)
+	}
+	if err := validateFQDN(hostName); err != nil {
+		return nil, fmt.Errorf("hostName %q is not a fully-qualified domain name: %v", hostName, err)
+	}
+
+	if len(ips) == 0 {
+		var err error
+		ips, err = net.LookupIP(trimDot(hostName))
+		if err != nil {
+			// Try appending the host domain suffix and lookup again
+			// (required for Linux-based hosts)
+			tmpHostName := fmt.Sprintf("%s%s", hostName, domain)
+
+			ips, err = net.LookupIP(trimDot(tmpHostName))
+
+			if err != nil {
+				return nil, fmt.Errorf("could not determine host IP addresses for %s", hostName)
+			}
+		}
+	}
+	for _, ip := range ips {
+		if ip.To4() == nil && ip.To16() == nil {
+			return nil, fmt.Errorf("invalid IP address in IPs list: %v", ip)
+		}
+	}
+
+	return &MDNSService{
+		Instance:     instance,
+		Service:      service,
+		Domain:       domain,
+		HostName:     hostName,
+		Port:         port,
+		IPs:          ips,
+		TXT:          txt,
+		TTL:          defaultTTL,
+		serviceAddr:  fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
+		instanceAddr: fmt.Sprintf("%s.%s.%s.", instance, trimDot(service), trimDot(domain)),
+		enumAddr:     fmt.Sprintf("_services._dns-sd._udp.%s.", trimDot(domain)),
+	}, nil
+}
+
+// trimDot is used to trim the dots from the start or end of a string.
+func trimDot(s string) string {
+	return strings.Trim(s, ".")
+}
+
+// Records returns DNS records in response to a DNS question.
+func (m *MDNSService) Records(q dns.Question) []dns.RR {
+	switch q.Name {
+	case m.enumAddr:
+		return m.serviceEnum(q)
+	case m.serviceAddr:
+		return m.serviceRecords(q)
+	case m.instanceAddr:
+		return m.instanceRecords(q)
+	case m.HostName:
+		if q.Qtype == dns.TypeA || q.Qtype == dns.TypeAAAA {
+			return m.instanceRecords(q)
+		}
+		fallthrough
+	default:
+		return nil
+	}
+}
+
+func (m *MDNSService) serviceEnum(q dns.Question) []dns.RR {
+	switch q.Qtype {
+	case dns.TypeANY:
+		fallthrough
+	case dns.TypePTR:
+		rr := &dns.PTR{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypePTR,
+				Class:  dns.ClassINET,
+				Ttl:    atomic.LoadUint32(&m.TTL),
+			},
+			Ptr: m.serviceAddr,
+		}
+		return []dns.RR{rr}
+	default:
+		return nil
+	}
+}
+
+// serviceRecords is called when the query matches the service name.
+func (m *MDNSService) serviceRecords(q dns.Question) []dns.RR {
+	switch q.Qtype {
+	case dns.TypeANY:
+		fallthrough
+	case dns.TypePTR:
+		// Build a PTR response for the service
+		rr := &dns.PTR{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypePTR,
+				Class:  dns.ClassINET,
+				Ttl:    atomic.LoadUint32(&m.TTL),
+			},
+			Ptr: m.instanceAddr,
+		}
+		servRec := []dns.RR{rr}
+
+		// Get the instance records
+		instRecs := m.instanceRecords(dns.Question{
+			Name:  m.instanceAddr,
+			Qtype: dns.TypeANY,
+		})
+
+		// Return the service record with the instance records
+		return append(servRec, instRecs...)
+	default:
+		return nil
+	}
+}
+
+// serviceRecords is called when the query matches the instance name.
+func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
+	switch q.Qtype {
+	case dns.TypeANY:
+		// Get the SRV, which includes A and AAAA
+		recs := m.instanceRecords(dns.Question{
+			Name:  m.instanceAddr,
+			Qtype: dns.TypeSRV,
+		})
+
+		// Add the TXT record
+		recs = append(recs, m.instanceRecords(dns.Question{
+			Name:  m.instanceAddr,
+			Qtype: dns.TypeTXT,
+		})...)
+		return recs
+
+	case dns.TypeA:
+		var rr []dns.RR
+		for _, ip := range m.IPs {
+			if ip4 := ip.To4(); ip4 != nil {
+				rr = append(rr, &dns.A{
+					Hdr: dns.RR_Header{
+						Name:   m.HostName,
+						Rrtype: dns.TypeA,
+						Class:  dns.ClassINET,
+						Ttl:    atomic.LoadUint32(&m.TTL),
+					},
+					A: ip4,
+				})
+			}
+		}
+		return rr
+
+	case dns.TypeAAAA:
+		var rr []dns.RR
+		for _, ip := range m.IPs {
+			if ip.To4() != nil {
+				// TODO(reddaly): IPv4 addresses could be encoded in IPv6 format and
+				// putinto AAAA records, but the current logic puts ipv4-encodable
+				// addresses into the A records exclusively.  Perhaps this should be
+				// configurable?
+				continue
+			}
+
+			if ip16 := ip.To16(); ip16 != nil {
+				rr = append(rr, &dns.AAAA{
+					Hdr: dns.RR_Header{
+						Name:   m.HostName,
+						Rrtype: dns.TypeAAAA,
+						Class:  dns.ClassINET,
+						Ttl:    atomic.LoadUint32(&m.TTL),
+					},
+					AAAA: ip16,
+				})
+			}
+		}
+		return rr
+
+	case dns.TypeSRV:
+		// Create the SRV Record
+		srv := &dns.SRV{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypeSRV,
+				Class:  dns.ClassINET,
+				Ttl:    atomic.LoadUint32(&m.TTL),
+			},
+			Priority: 10,
+			Weight:   1,
+			Port:     uint16(m.Port),
+			Target:   m.HostName,
+		}
+		recs := []dns.RR{srv}
+
+		// Add the A record
+		recs = append(recs, m.instanceRecords(dns.Question{
+			Name:  m.instanceAddr,
+			Qtype: dns.TypeA,
+		})...)
+
+		// Add the AAAA record
+		recs = append(recs, m.instanceRecords(dns.Question{
+			Name:  m.instanceAddr,
+			Qtype: dns.TypeAAAA,
+		})...)
+		return recs
+
+	case dns.TypeTXT:
+		txt := &dns.TXT{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypeTXT,
+				Class:  dns.ClassINET,
+				Ttl:    atomic.LoadUint32(&m.TTL),
+			},
+			Txt: m.TXT,
+		}
+		return []dns.RR{txt}
+	}
+	return nil
+}
@@ -0,0 +1,275 @@
+package mdns
+
+import (
+	"bytes"
+	"net"
+	"reflect"
+	"testing"
+
+	"github.com/miekg/dns"
+)
+
+func makeService(t *testing.T) *MDNSService {
+	return makeServiceWithServiceName(t, "_http._tcp")
+}
+
+func makeServiceWithServiceName(t *testing.T, service string) *MDNSService {
+	m, err := NewMDNSService(
+		"hostname",
+		service,
+		"local.",
+		"testhost.",
+		80, // port
+		[]net.IP{net.IP([]byte{192, 168, 0, 42}), net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")},
+		[]string{"Local web server"}) // TXT
+
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	return m
+}
+
+func TestNewMDNSService_BadParams(t *testing.T) {
+	for _, test := range []struct {
+		testName string
+		hostName string
+		domain   string
+	}{
+		{
+			"NewMDNSService should fail when passed hostName that is not a legal fully-qualified domain name",
+			"hostname", // not legal FQDN - should be "hostname." or "hostname.local.", etc.
+			"local.",   // legal
+		},
+		{
+			"NewMDNSService should fail when passed domain that is not a legal fully-qualified domain name",
+			"hostname.", // legal
+			"local",     // should be "local."
+		},
+	} {
+		_, err := NewMDNSService(
+			"instance name",
+			"_http._tcp",
+			test.domain,
+			test.hostName,
+			80, // port
+			[]net.IP{net.IP([]byte{192, 168, 0, 42})},
+			[]string{"Local web server"}) // TXT
+		if err == nil {
+			t.Fatalf("%s: error expected, but got none", test.testName)
+		}
+	}
+}
+
+func TestMDNSService_BadAddr(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "random",
+		Qtype: dns.TypeANY,
+	}
+	recs := s.Records(q)
+	if len(recs) != 0 {
+		t.Fatalf("bad: %v", recs)
+	}
+}
+
+func TestMDNSService_ServiceAddr(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "_http._tcp.local.",
+		Qtype: dns.TypeANY,
+	}
+	recs := s.Records(q)
+	if got, want := len(recs), 5; got != want {
+		t.Fatalf("got %d records, want %d: %v", got, want, recs)
+	}
+
+	if ptr, ok := recs[0].(*dns.PTR); !ok {
+		t.Errorf("recs[0] should be PTR record, got: %v, all records: %v", recs[0], recs)
+	} else if got, want := ptr.Ptr, "hostname._http._tcp.local."; got != want {
+		t.Fatalf("bad PTR record %v: got %v, want %v", ptr, got, want)
+	}
+
+	if _, ok := recs[1].(*dns.SRV); !ok {
+		t.Errorf("recs[1] should be SRV record, got: %v, all reccords: %v", recs[1], recs)
+	}
+	if _, ok := recs[2].(*dns.A); !ok {
+		t.Errorf("recs[2] should be A record, got: %v, all records: %v", recs[2], recs)
+	}
+	if _, ok := recs[3].(*dns.AAAA); !ok {
+		t.Errorf("recs[3] should be AAAA record, got: %v, all records: %v", recs[3], recs)
+	}
+	if _, ok := recs[4].(*dns.TXT); !ok {
+		t.Errorf("recs[4] should be TXT record, got: %v, all records: %v", recs[4], recs)
+	}
+
+	q.Qtype = dns.TypePTR
+	if recs2 := s.Records(q); !reflect.DeepEqual(recs, recs2) {
+		t.Fatalf("PTR question should return same result as ANY question: ANY => %v, PTR => %v", recs, recs2)
+	}
+}
+
+func TestMDNSService_InstanceAddr_ANY(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "hostname._http._tcp.local.",
+		Qtype: dns.TypeANY,
+	}
+	recs := s.Records(q)
+	if len(recs) != 4 {
+		t.Fatalf("bad: %v", recs)
+	}
+	if _, ok := recs[0].(*dns.SRV); !ok {
+		t.Fatalf("bad: %v", recs[0])
+	}
+	if _, ok := recs[1].(*dns.A); !ok {
+		t.Fatalf("bad: %v", recs[1])
+	}
+	if _, ok := recs[2].(*dns.AAAA); !ok {
+		t.Fatalf("bad: %v", recs[2])
+	}
+	if _, ok := recs[3].(*dns.TXT); !ok {
+		t.Fatalf("bad: %v", recs[3])
+	}
+}
+
+func TestMDNSService_InstanceAddr_SRV(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "hostname._http._tcp.local.",
+		Qtype: dns.TypeSRV,
+	}
+	recs := s.Records(q)
+	if len(recs) != 3 {
+		t.Fatalf("bad: %v", recs)
+	}
+	srv, ok := recs[0].(*dns.SRV)
+	if !ok {
+		t.Fatalf("bad: %v", recs[0])
+	}
+	if _, ok := recs[1].(*dns.A); !ok {
+		t.Fatalf("bad: %v", recs[1])
+	}
+	if _, ok := recs[2].(*dns.AAAA); !ok {
+		t.Fatalf("bad: %v", recs[2])
+	}
+
+	if srv.Port != uint16(s.Port) {
+		t.Fatalf("bad: %v", recs[0])
+	}
+}
+
+func TestMDNSService_InstanceAddr_A(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "hostname._http._tcp.local.",
+		Qtype: dns.TypeA,
+	}
+	recs := s.Records(q)
+	if len(recs) != 1 {
+		t.Fatalf("bad: %v", recs)
+	}
+	a, ok := recs[0].(*dns.A)
+	if !ok {
+		t.Fatalf("bad: %v", recs[0])
+	}
+	if !bytes.Equal(a.A, []byte{192, 168, 0, 42}) {
+		t.Fatalf("bad: %v", recs[0])
+	}
+}
+
+func TestMDNSService_InstanceAddr_AAAA(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "hostname._http._tcp.local.",
+		Qtype: dns.TypeAAAA,
+	}
+	recs := s.Records(q)
+	if len(recs) != 1 {
+		t.Fatalf("bad: %v", recs)
+	}
+	a4, ok := recs[0].(*dns.AAAA)
+	if !ok {
+		t.Fatalf("bad: %v", recs[0])
+	}
+	ip6 := net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")
+	if got := len(ip6); got != net.IPv6len {
+		t.Fatalf("test IP failed to parse (len = %d, want %d)", got, net.IPv6len)
+	}
+	if !a4.AAAA.Equal(ip6) {
+		t.Fatalf("bad: %v", recs[0])
+	}
+}
+
+func TestMDNSService_InstanceAddr_TXT(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "hostname._http._tcp.local.",
+		Qtype: dns.TypeTXT,
+	}
+	recs := s.Records(q)
+	if len(recs) != 1 {
+		t.Fatalf("bad: %v", recs)
+	}
+	txt, ok := recs[0].(*dns.TXT)
+	if !ok {
+		t.Fatalf("bad: %v", recs[0])
+	}
+	if got, want := txt.Txt, s.TXT; !reflect.DeepEqual(got, want) {
+		t.Fatalf("TXT record mismatch for %v: got %v, want %v", recs[0], got, want)
+	}
+}
+
+func TestMDNSService_HostNameQuery(t *testing.T) {
+	s := makeService(t)
+	for _, test := range []struct {
+		q    dns.Question
+		want []dns.RR
+	}{
+		{
+			dns.Question{Name: "testhost.", Qtype: dns.TypeA},
+			[]dns.RR{&dns.A{
+				Hdr: dns.RR_Header{
+					Name:   "testhost.",
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+					Ttl:    120,
+				},
+				A: net.IP([]byte{192, 168, 0, 42}),
+			}},
+		},
+		{
+			dns.Question{Name: "testhost.", Qtype: dns.TypeAAAA},
+			[]dns.RR{&dns.AAAA{
+				Hdr: dns.RR_Header{
+					Name:   "testhost.",
+					Rrtype: dns.TypeAAAA,
+					Class:  dns.ClassINET,
+					Ttl:    120,
+				},
+				AAAA: net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc"),
+			}},
+		},
+	} {
+		if got := s.Records(test.q); !reflect.DeepEqual(got, test.want) {
+			t.Errorf("hostname query failed: s.Records(%v) = %v, want %v", test.q, got, test.want)
+		}
+	}
+}
+
+func TestMDNSService_serviceEnum_PTR(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "_services._dns-sd._udp.local.",
+		Qtype: dns.TypePTR,
+	}
+	recs := s.Records(q)
+	if len(recs) != 1 {
+		t.Fatalf("bad: %v", recs)
+	}
+	if ptr, ok := recs[0].(*dns.PTR); !ok {
+		t.Errorf("recs[0] should be PTR record, got: %v, all records: %v", recs[0], recs)
+	} else if got, want := ptr.Ptr, "_http._tcp.local."; got != want {
+		t.Fatalf("bad PTR record %v: got %v, want %v", ptr, got, want)
+	}
+}
@@ -0,0 +1,119 @@
+package net
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// HostPort format addr and port suitable for dial.
+func HostPort(addr string, port interface{}) string {
+	host := addr
+	if strings.Count(addr, ":") > 0 {
+		host = fmt.Sprintf("[%s]", addr)
+	}
+	// when port is blank or 0, host is a queue name
+	if v, ok := port.(string); ok && v == "" {
+		return host
+	} else if v, ok := port.(int); ok && v == 0 && net.ParseIP(host) == nil {
+		return host
+	}
+
+	return fmt.Sprintf("%s:%v", host, port)
+}
+
+// Listen takes addr:portmin-portmax and binds to the first available port
+// Example: Listen("localhost:5000-6000", fn).
+func Listen(addr string, fn func(string) (net.Listener, error)) (net.Listener, error) {
+	if strings.Count(addr, ":") == 1 && strings.Count(addr, "-") == 0 {
+		return fn(addr)
+	}
+
+	// host:port || host:min-max
+	host, ports, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	// try to extract port range
+	prange := strings.Split(ports, "-")
+
+	// single port
+	if len(prange) < 2 {
+		return fn(addr)
+	}
+
+	// we have a port range
+
+	// extract min port
+	min, err := strconv.Atoi(prange[0])
+	if err != nil {
+		return nil, errors.New("unable to extract port range")
+	}
+
+	// extract max port
+	max, err := strconv.Atoi(prange[1])
+	if err != nil {
+		return nil, errors.New("unable to extract port range")
+	}
+
+	// range the ports
+	for port := min; port <= max; port++ {
+		// try bind to host:port
+		ln, err := fn(HostPort(host, port))
+		if err == nil {
+			return ln, nil
+		}
+
+		// hit max port
+		if port == max {
+			return nil, err
+		}
+	}
+
+	// why are we here?
+	return nil, fmt.Errorf("unable to bind to %s", addr)
+}
+
+// Proxy returns the proxy and the address if it exits.
+func Proxy(service string, address []string) (string, []string, bool) {
+	var hasProxy bool
+
+	// get proxy. we parse out address if present
+	if prx := os.Getenv("MICRO_PROXY"); len(prx) > 0 {
+		// default name
+		if prx == "service" {
+			prx = "go.micro.proxy"
+			address = nil
+		}
+
+		// check if its an address
+		if v := strings.Split(prx, ":"); len(v) > 1 {
+			address = []string{prx}
+		}
+
+		service = prx
+		hasProxy = true
+
+		return service, address, hasProxy
+	}
+
+	if prx := os.Getenv("MICRO_NETWORK"); len(prx) > 0 {
+		// default name
+		if prx == "service" {
+			prx = "go.micro.network"
+		}
+		service = prx
+		hasProxy = true
+	}
+
+	if prx := os.Getenv("MICRO_NETWORK_ADDRESS"); len(prx) > 0 {
+		address = []string{prx}
+		hasProxy = true
+	}
+
+	return service, address, hasProxy
+}
@@ -0,0 +1,61 @@
+package net
+
+import (
+	"net"
+	"os"
+	"testing"
+)
+
+func TestListen(t *testing.T) {
+	fn := func(addr string) (net.Listener, error) {
+		return net.Listen("tcp", addr)
+	}
+
+	// try to create a number of listeners
+	for i := 0; i < 10; i++ {
+		l, err := Listen("localhost:10000-11000", fn)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer l.Close()
+	}
+
+	// TODO nats case test
+	// natsAddr := "_INBOX.bID2CMRvlNp0vt4tgNBHWf"
+	// Expect addr DO NOT has extra ":" at the end!
+}
+
+// TestProxyEnv checks whether we have proxy/network settings in env.
+func TestProxyEnv(t *testing.T) {
+	service := "foo"
+	address := []string{"bar"}
+
+	s, a, ok := Proxy(service, address)
+	if ok {
+		t.Fatal("Should not have proxy", s, a, ok)
+	}
+
+	test := func(key, val, expectSrv, expectAddr string) {
+		// set env
+		os.Setenv(key, val)
+
+		s, a, ok := Proxy(service, address)
+		if !ok {
+			t.Fatal("Expected proxy")
+		}
+		if len(expectSrv) > 0 && s != expectSrv {
+			t.Fatal("Expected proxy service", expectSrv, "got", s)
+		}
+		if len(expectAddr) > 0 {
+			if len(a) == 0 || a[0] != expectAddr {
+				t.Fatal("Expected proxy address", expectAddr, "got", a)
+			}
+		}
+
+		os.Unsetenv(key)
+	}
+
+	test("MICRO_PROXY", "service", "go.micro.proxy", "")
+	test("MICRO_NETWORK", "service", "go.micro.network", "")
+	test("MICRO_NETWORK_ADDRESS", "10.0.0.1:8081", "", "10.0.0.1:8081")
+}
@@ -0,0 +1,159 @@
+package pool
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+
+	"go-micro.dev/v6/transport"
+)
+
+type pool struct {
+	tr transport.Transport
+
+	closeTimeout time.Duration
+	conns        map[string][]*poolConn
+	mu           sync.Mutex
+	size         int
+	ttl          time.Duration
+}
+
+type poolConn struct {
+	transport.Client
+
+	closeTimeout time.Duration
+	created      time.Time
+	id           string
+}
+
+func newPool(options Options) *pool {
+	return &pool{
+		size:         options.Size,
+		tr:           options.Transport,
+		ttl:          options.TTL,
+		closeTimeout: options.CloseTimeout,
+		conns:        make(map[string][]*poolConn),
+	}
+}
+
+func (p *pool) Close() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	var err error
+
+	for k, c := range p.conns {
+		for _, conn := range c {
+			if nerr := conn.close(); nerr != nil {
+				err = nerr
+			}
+		}
+
+		delete(p.conns, k)
+	}
+
+	return err
+}
+
+// NoOp the Close since we manage it.
+func (p *poolConn) Close() error {
+	return nil
+}
+
+func (p *poolConn) Id() string {
+	return p.id
+}
+
+func (p *poolConn) Created() time.Time {
+	return p.created
+}
+
+func (p *pool) Get(addr string, opts ...transport.DialOption) (Conn, error) {
+	p.mu.Lock()
+	conns := p.conns[addr]
+
+	// While we have conns check age and then return one
+	// otherwise we'll create a new conn
+	for len(conns) > 0 {
+		conn := conns[len(conns)-1]
+		conns = conns[:len(conns)-1]
+		p.conns[addr] = conns
+
+		// If conn is old kill it and move on
+		if d := time.Since(conn.Created()); d > p.ttl {
+			if err := conn.close(); err != nil {
+				p.mu.Unlock()
+				c, errConn := p.newConn(addr, opts)
+				if errConn != nil {
+					return nil, errConn
+				}
+				return c, err
+			}
+
+			continue
+		}
+
+		// We got a good conn, lets unlock and return it
+		p.mu.Unlock()
+
+		return conn, nil
+	}
+
+	p.mu.Unlock()
+
+	return p.newConn(addr, opts)
+}
+
+func (p *pool) newConn(addr string, opts []transport.DialOption) (Conn, error) {
+	// create new conn
+	c, err := p.tr.Dial(addr, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &poolConn{
+		Client:       c,
+		id:           uuid.New().String(),
+		closeTimeout: p.closeTimeout,
+		created:      time.Now(),
+	}, nil
+}
+
+func (p *pool) Release(conn Conn, err error) error {
+	// don't store the conn if it has errored
+	if err != nil {
+		return conn.(*poolConn).close()
+	}
+
+	// otherwise put it back for reuse
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	conns := p.conns[conn.Remote()]
+	if len(conns) >= p.size {
+		return conn.(*poolConn).close()
+	}
+
+	p.conns[conn.Remote()] = append(conns, conn.(*poolConn))
+
+	return nil
+}
+
+func (p *poolConn) close() error {
+	ch := make(chan error)
+	go func() {
+		defer close(ch)
+		ch <- p.Client.Close()
+	}()
+	t := time.NewTimer(p.closeTimeout)
+	var err error
+	select {
+	case <-t.C:
+		err = errors.New("unable to close in time")
+	case err = <-ch:
+		t.Stop()
+	}
+	return err
+}
@@ -0,0 +1,88 @@
+package pool
+
+import (
+	"testing"
+	"time"
+
+	"go-micro.dev/v6/transport"
+)
+
+func testPool(t *testing.T, size int, ttl time.Duration) {
+	// mock transport
+	tr := transport.NewMemoryTransport()
+
+	options := Options{
+		TTL:       ttl,
+		Size:      size,
+		Transport: tr,
+	}
+	// zero pool
+	p := newPool(options)
+
+	// listen
+	l, err := tr.Listen(":0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer l.Close()
+
+	// accept loop
+	go func() {
+		for {
+			if err := l.Accept(func(s transport.Socket) {
+				for {
+					var msg transport.Message
+					if err := s.Recv(&msg); err != nil {
+						return
+					}
+					if err := s.Send(&msg); err != nil {
+						return
+					}
+				}
+			}); err != nil {
+				return
+			}
+		}
+	}()
+
+	for i := 0; i < 10; i++ {
+		// get a conn
+		c, err := p.Get(l.Addr())
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		msg := &transport.Message{
+			Body: []byte(`hello world`),
+		}
+
+		if err := c.Send(msg); err != nil {
+			t.Fatal(err)
+		}
+
+		var rcv transport.Message
+
+		if err := c.Recv(&rcv); err != nil {
+			t.Fatal(err)
+		}
+
+		if string(rcv.Body) != string(msg.Body) {
+			t.Fatalf("got %v, expected %v", rcv.Body, msg.Body)
+		}
+
+		// release the conn
+		p.Release(c, nil)
+
+		p.mu.Lock()
+		if i := len(p.conns[l.Addr()]); i > size {
+			p.mu.Unlock()
+			t.Fatalf("pool size %d is greater than expected %d", i, size)
+		}
+		p.mu.Unlock()
+	}
+}
+
+func TestClientPool(t *testing.T) {
+	testPool(t, 0, time.Minute)
+	testPool(t, 2, time.Minute)
+}
@@ -0,0 +1,40 @@
+package pool
+
+import (
+	"time"
+
+	"go-micro.dev/v6/transport"
+)
+
+type Options struct {
+	Transport    transport.Transport
+	TTL          time.Duration
+	CloseTimeout time.Duration
+	Size         int
+}
+
+type Option func(*Options)
+
+func Size(i int) Option {
+	return func(o *Options) {
+		o.Size = i
+	}
+}
+
+func Transport(t transport.Transport) Option {
+	return func(o *Options) {
+		o.Transport = t
+	}
+}
+
+func TTL(t time.Duration) Option {
+	return func(o *Options) {
+		o.TTL = t
+	}
+}
+
+func CloseTimeout(t time.Duration) Option {
+	return func(o *Options) {
+		o.CloseTimeout = t
+	}
+}
@@ -0,0 +1,38 @@
+// Package pool is a connection pool
+package pool
+
+import (
+	"time"
+
+	"go-micro.dev/v6/transport"
+)
+
+// Pool is an interface for connection pooling.
+type Pool interface {
+	// Close the pool
+	Close() error
+	// Get a connection
+	Get(addr string, opts ...transport.DialOption) (Conn, error)
+	// Release the connection
+	Release(c Conn, status error) error
+}
+
+// Conn interface represents a pool connection.
+type Conn interface {
+	// unique id of connection
+	Id() string
+	// time it was created
+	Created() time.Time
+	// embedded connection
+	transport.Client
+}
+
+// NewPool will return a new pool object.
+func NewPool(opts ...Option) Pool {
+	var options Options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return newPool(options)
+}
@@ -0,0 +1,148 @@
+package registry
+
+import (
+	"go-micro.dev/v6/registry"
+)
+
+func addNodes(old, neu []*registry.Node) []*registry.Node {
+	nodes := make([]*registry.Node, len(neu))
+	// add all new nodes
+	for i, n := range neu {
+		node := *n
+		nodes[i] = &node
+	}
+
+	// look at old nodes
+	for _, o := range old {
+		var exists bool
+
+		// check against new nodes
+		for _, n := range nodes {
+			// ids match then skip
+			if o.Id == n.Id {
+				exists = true
+				break
+			}
+		}
+
+		// keep old node
+		if !exists {
+			node := *o
+			nodes = append(nodes, &node)
+		}
+	}
+
+	return nodes
+}
+
+func delNodes(old, del []*registry.Node) []*registry.Node {
+	var nodes []*registry.Node
+	for _, o := range old {
+		var rem bool
+		for _, n := range del {
+			if o.Id == n.Id {
+				rem = true
+				break
+			}
+		}
+		if !rem {
+			nodes = append(nodes, o)
+		}
+	}
+	return nodes
+}
+
+// CopyService make a copy of service.
+func CopyService(service *registry.Service) *registry.Service {
+	// copy service
+	s := new(registry.Service)
+	*s = *service
+
+	// copy nodes
+	nodes := make([]*registry.Node, len(service.Nodes))
+	for j, node := range service.Nodes {
+		n := new(registry.Node)
+		*n = *node
+		nodes[j] = n
+	}
+	s.Nodes = nodes
+
+	// copy endpoints
+	eps := make([]*registry.Endpoint, len(service.Endpoints))
+	for j, ep := range service.Endpoints {
+		e := new(registry.Endpoint)
+		*e = *ep
+		eps[j] = e
+	}
+	s.Endpoints = eps
+	return s
+}
+
+// Copy makes a copy of services.
+func Copy(current []*registry.Service) []*registry.Service {
+	services := make([]*registry.Service, len(current))
+	for i, service := range current {
+		services[i] = CopyService(service)
+	}
+	return services
+}
+
+// Merge merges two lists of services and returns a new copy.
+func Merge(olist []*registry.Service, nlist []*registry.Service) []*registry.Service {
+	var srv []*registry.Service
+
+	for _, n := range nlist {
+		var seen bool
+		for _, o := range olist {
+			if o.Version == n.Version {
+				sp := new(registry.Service)
+				// make copy
+				*sp = *o
+				// set nodes
+				sp.Nodes = addNodes(o.Nodes, n.Nodes)
+
+				// mark as seen
+				seen = true
+				srv = append(srv, sp)
+				break
+			} else {
+				sp := new(registry.Service)
+				// make copy
+				*sp = *o
+				srv = append(srv, sp)
+			}
+		}
+		if !seen {
+			srv = append(srv, Copy([]*registry.Service{n})...)
+		}
+	}
+	return srv
+}
+
+// Remove removes services and returns a new copy.
+func Remove(old, del []*registry.Service) []*registry.Service {
+	var services []*registry.Service
+
+	for _, o := range old {
+		srv := new(registry.Service)
+		*srv = *o
+
+		var rem bool
+
+		for _, s := range del {
+			if srv.Version == s.Version {
+				srv.Nodes = delNodes(srv.Nodes, s.Nodes)
+
+				if len(srv.Nodes) == 0 {
+					rem = true
+				}
+			}
+		}
+
+		if !rem {
+			services = append(services, srv)
+		}
+	}
+
+	return services
+}
@@ -0,0 +1,78 @@
+package registry
+
+import (
+	"os"
+	"testing"
+
+	"go-micro.dev/v6/registry"
+)
+
+func TestRemove(t *testing.T) {
+	services := []*registry.Service{
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost:9999",
+				},
+			},
+		},
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost:6666",
+				},
+			},
+		},
+	}
+
+	servs := Remove([]*registry.Service{services[0]}, []*registry.Service{services[1]})
+	if i := len(servs); i > 0 {
+		t.Errorf("Expected 0 nodes, got %d: %+v", i, servs)
+	}
+	if len(os.Getenv("IN_TRAVIS_CI")) == 0 {
+		t.Logf("Services %+v", servs)
+	}
+}
+
+func TestRemoveNodes(t *testing.T) {
+	services := []*registry.Service{
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost:9999",
+				},
+				{
+					Id:      "foo-321",
+					Address: "localhost:6666",
+				},
+			},
+		},
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost:6666",
+				},
+			},
+		},
+	}
+
+	nodes := delNodes(services[0].Nodes, services[1].Nodes)
+	if i := len(nodes); i != 1 {
+		t.Errorf("Expected only 1 node, got %d: %+v", i, nodes)
+	}
+	if len(os.Getenv("IN_TRAVIS_CI")) == 0 {
+		t.Logf("Nodes %+v", nodes)
+	}
+}
@@ -0,0 +1,139 @@
+// Package ring provides a simple ring buffer for storing local data
+package ring
+
+import (
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// Buffer is ring buffer.
+type Buffer struct {
+	streams map[string]*Stream
+	vals    []*Entry
+	size    int
+
+	sync.RWMutex
+}
+
+// Entry is ring buffer data entry.
+type Entry struct {
+	Value     interface{}
+	Timestamp time.Time
+}
+
+// Stream is used to stream the buffer.
+type Stream struct {
+	// Buffered entries
+	Entries chan *Entry
+	// Stop channel
+	Stop chan bool
+	// Id of the stream
+	Id string
+}
+
+// Put adds a new value to ring buffer.
+func (b *Buffer) Put(v interface{}) {
+	b.Lock()
+	defer b.Unlock()
+
+	// append to values
+	entry := &Entry{
+		Value:     v,
+		Timestamp: time.Now(),
+	}
+	b.vals = append(b.vals, entry)
+
+	// trim if bigger than size required
+	if len(b.vals) > b.size {
+		b.vals = b.vals[1:]
+	}
+
+	// send to every stream
+	for _, stream := range b.streams {
+		select {
+		case <-stream.Stop:
+			delete(b.streams, stream.Id)
+			close(stream.Entries)
+		case stream.Entries <- entry:
+		}
+	}
+}
+
+// Get returns the last n entries.
+func (b *Buffer) Get(n int) []*Entry {
+	b.RLock()
+	defer b.RUnlock()
+
+	// reset any invalid values
+	if n > len(b.vals) || n < 0 {
+		n = len(b.vals)
+	}
+
+	// create a delta
+	delta := len(b.vals) - n
+
+	// return the delta set
+	return b.vals[delta:]
+}
+
+// Return the entries since a specific time.
+func (b *Buffer) Since(t time.Time) []*Entry {
+	b.RLock()
+	defer b.RUnlock()
+
+	// return all the values
+	if t.IsZero() {
+		return b.vals
+	}
+
+	// if its in the future return nothing
+	if time.Since(t).Seconds() < 0.0 {
+		return nil
+	}
+
+	for i, v := range b.vals {
+		// find the starting point
+		d := v.Timestamp.Sub(t)
+
+		// return the values
+		if d.Seconds() > 0.0 {
+			return b.vals[i:]
+		}
+	}
+
+	return nil
+}
+
+// Stream logs from the buffer
+// Close the channel when you want to stop.
+func (b *Buffer) Stream() (<-chan *Entry, chan bool) {
+	b.Lock()
+	defer b.Unlock()
+
+	entries := make(chan *Entry, 128)
+	id := uuid.New().String()
+	stop := make(chan bool)
+
+	b.streams[id] = &Stream{
+		Id:      id,
+		Entries: entries,
+		Stop:    stop,
+	}
+
+	return entries, stop
+}
+
+// Size returns the size of the ring buffer.
+func (b *Buffer) Size() int {
+	return b.size
+}
+
+// New returns a new buffer of the given size.
+func New(i int) *Buffer {
+	return &Buffer{
+		size:    i,
+		streams: make(map[string]*Stream),
+	}
+}
@@ -0,0 +1,79 @@
+package ring
+
+import (
+	"testing"
+	"time"
+)
+
+func TestBuffer(t *testing.T) {
+	b := New(10)
+
+	// test one value
+	b.Put("foo")
+	v := b.Get(1)
+
+	if val := v[0].Value.(string); val != "foo" {
+		t.Fatalf("expected foo got %v", val)
+	}
+
+	b = New(10)
+
+	// test 10 values
+	for i := 0; i < 10; i++ {
+		b.Put(i)
+	}
+
+	d := time.Now()
+	v = b.Get(10)
+
+	for i := 0; i < 10; i++ {
+		val := v[i].Value.(int)
+
+		if val != i {
+			t.Fatalf("expected %d got %d", i, val)
+		}
+	}
+
+	// test more values
+
+	for i := 0; i < 10; i++ {
+		v := i * 2
+		b.Put(v)
+	}
+
+	v = b.Get(10)
+
+	for i := 0; i < 10; i++ {
+		val := v[i].Value.(int)
+		expect := i * 2
+		if val != expect {
+			t.Fatalf("expected %d got %d", expect, val)
+		}
+	}
+
+	// sleep 100 ms
+	time.Sleep(time.Millisecond * 100)
+
+	// assume we'll get everything
+	v = b.Since(d)
+
+	if len(v) != 10 {
+		t.Fatalf("expected 10 entries but got %d", len(v))
+	}
+
+	// write 1 more entry
+	d = time.Now()
+	b.Put(100)
+
+	// sleep 100 ms
+	time.Sleep(time.Millisecond * 100)
+
+	v = b.Since(d)
+	if len(v) != 1 {
+		t.Fatalf("expected 1 entries but got %d", len(v))
+	}
+
+	if v[0].Value.(int) != 100 {
+		t.Fatalf("expected value 100 got %v", v[0])
+	}
+}
@@ -0,0 +1,13 @@
+package signal
+
+import (
+	"os"
+	"syscall"
+)
+
+// ShutDownSingals returns all the signals that are being watched for to shut down services.
+func Shutdown() []os.Signal {
+	return []os.Signal{
+		syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGKILL,
+	}
+}
@@ -0,0 +1,62 @@
+package socket
+
+import (
+	"sync"
+)
+
+type Pool struct {
+	pool map[string]*Socket
+	sync.RWMutex
+}
+
+func (p *Pool) Get(id string) (*Socket, bool) {
+	// attempt to get existing socket
+	p.RLock()
+	socket, ok := p.pool[id]
+	if ok {
+		p.RUnlock()
+		return socket, ok
+	}
+	p.RUnlock()
+
+	// save socket
+	p.Lock()
+	defer p.Unlock()
+	// double checked locking
+	socket, ok = p.pool[id]
+	if ok {
+		return socket, ok
+	}
+	// create new socket
+	socket = New(id)
+	p.pool[id] = socket
+
+	// return socket
+	return socket, false
+}
+
+func (p *Pool) Release(s *Socket) {
+	p.Lock()
+	defer p.Unlock()
+
+	// close the socket
+	s.Close()
+	delete(p.pool, s.id)
+}
+
+// Close the pool and delete all the sockets.
+func (p *Pool) Close() {
+	p.Lock()
+	defer p.Unlock()
+	for id, sock := range p.pool {
+		sock.Close()
+		delete(p.pool, id)
+	}
+}
+
+// NewPool returns a new socket pool.
+func NewPool() *Pool {
+	return &Pool{
+		pool: make(map[string]*Socket),
+	}
+}
@@ -0,0 +1,117 @@
+// Package socket provides a pseudo socket
+package socket
+
+import (
+	"io"
+
+	"go-micro.dev/v6/transport"
+)
+
+// Socket is our pseudo socket for transport.Socket.
+type Socket struct {
+	// closed
+	closed chan bool
+	// send chan
+	send chan *transport.Message
+	// recv chan
+	recv chan *transport.Message
+	id   string
+	// remote addr
+	remote string
+	// local addr
+	local string
+}
+
+func (s *Socket) SetLocal(l string) {
+	s.local = l
+}
+
+func (s *Socket) SetRemote(r string) {
+	s.remote = r
+}
+
+// Accept passes a message to the socket which will be processed by the call to Recv.
+func (s *Socket) Accept(m *transport.Message) error {
+	select {
+	case s.recv <- m:
+		return nil
+	case <-s.closed:
+		return io.EOF
+	}
+}
+
+// Process takes the next message off the send queue created by a call to Send.
+func (s *Socket) Process(m *transport.Message) error {
+	select {
+	case msg := <-s.send:
+		*m = *msg
+	case <-s.closed:
+		// see if we need to drain
+		select {
+		case msg := <-s.send:
+			*m = *msg
+			return nil
+		default:
+			return io.EOF
+		}
+	}
+	return nil
+}
+
+func (s *Socket) Remote() string {
+	return s.remote
+}
+
+func (s *Socket) Local() string {
+	return s.local
+}
+
+func (s *Socket) Send(m *transport.Message) error {
+	// send a message
+	select {
+	case s.send <- m:
+	case <-s.closed:
+		return io.EOF
+	}
+
+	return nil
+}
+
+func (s *Socket) Recv(m *transport.Message) error {
+	// receive a message
+	select {
+	case msg := <-s.recv:
+		// set message
+		*m = *msg
+	case <-s.closed:
+		return io.EOF
+	}
+
+	// return nil
+	return nil
+}
+
+// Close closes the socket.
+func (s *Socket) Close() error {
+	select {
+	case <-s.closed:
+		// no op
+	default:
+		close(s.closed)
+	}
+	return nil
+}
+
+// New returns a new pseudo socket which can be used in the place of a transport socket.
+// Messages are sent to the socket via Accept and receives from the socket via Process.
+// SetLocal/SetRemote should be called before using the socket.
+func New(id string) *Socket {
+	return &Socket{
+		id:     id,
+		closed: make(chan bool),
+		local:  "local",
+		remote: "remote",
+		send:   make(chan *transport.Message, 128),
+		recv:   make(chan *transport.Message, 128),
+	}
+}
@@ -0,0 +1,58 @@
+package test
+
+import (
+	"go-micro.dev/v6/registry"
+)
+
+var (
+	// Data is a set of mock registry data.
+	Data = map[string][]*registry.Service{
+		"foo": {
+			{
+				Name:    "foo",
+				Version: "1.0.0",
+				Nodes: []*registry.Node{
+					{
+						Id:      "foo-1.0.0-123",
+						Address: "localhost:9999",
+					},
+					{
+						Id:      "foo-1.0.0-321",
+						Address: "localhost:9999",
+					},
+				},
+			},
+			{
+				Name:    "foo",
+				Version: "1.0.1",
+				Nodes: []*registry.Node{
+					{
+						Id:      "foo-1.0.1-321",
+						Address: "localhost:6666",
+					},
+				},
+			},
+			{
+				Name:    "foo",
+				Version: "1.0.3",
+				Nodes: []*registry.Node{
+					{
+						Id:      "foo-1.0.3-345",
+						Address: "localhost:8888",
+					},
+				},
+			},
+		},
+	}
+)
+
+// EmptyChannel will empty out a error channel by checking if an error is
+// present, and if so return the error.
+func EmptyChannel(c chan error) error {
+	select {
+	case err := <-c:
+		return err
+	default:
+		return nil
+	}
+}
@@ -0,0 +1,123 @@
+// Package tls provides TLS utilities for go-micro.
+package tls
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"math/big"
+	"net"
+	"os"
+	"time"
+)
+
+// Config returns the default TLS config.
+//
+// As of v6, certificate verification is ON by default (secure by default).
+// This is the safe choice now that an agent — not just a human on a
+// trusted network — can reach an endpoint.
+//
+// For development against self-signed certificates, set
+// MICRO_TLS_INSECURE=true to skip verification, or call InsecureConfig()
+// directly. (In v5 the default was the reverse: insecure unless
+// MICRO_TLS_SECURE=true was set. That env var is no longer needed.)
+func Config() *tls.Config {
+	// Opt out of verification for local/dev against self-signed certs.
+	if os.Getenv("MICRO_TLS_INSECURE") == "true" {
+		return &tls.Config{
+			InsecureSkipVerify: true,
+			MinVersion:         tls.VersionTLS12,
+		}
+	}
+
+	// Secure by default.
+	return &tls.Config{
+		InsecureSkipVerify: false,
+		MinVersion:         tls.VersionTLS12,
+	}
+}
+
+// SecureConfig returns a TLS config with certificate verification enabled.
+// Use this when you have proper CA-signed certificates.
+func SecureConfig() *tls.Config {
+	return &tls.Config{
+		InsecureSkipVerify: false,
+		MinVersion:         tls.VersionTLS12,
+	}
+}
+
+// InsecureConfig returns a TLS config with certificate verification disabled.
+// WARNING: Only use for development/testing.
+func InsecureConfig() *tls.Config {
+	return &tls.Config{
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS12,
+	}
+}
+
+// Certificate generates a self-signed certificate for the given hosts.
+// Note: These certs are for development only. For production, use proper
+// CA-signed certificates or a service mesh.
+func Certificate(host ...string) (tls.Certificate, error) {
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return tls.Certificate{}, err
+	}
+
+	notBefore := time.Now()
+	notAfter := notBefore.Add(time.Hour * 24 * 365)
+
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		return tls.Certificate{}, err
+	}
+
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"Micro"},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notAfter,
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	for _, h := range host {
+		if ip := net.ParseIP(h); ip != nil {
+			template.IPAddresses = append(template.IPAddresses, ip)
+		} else {
+			template.DNSNames = append(template.DNSNames, h)
+		}
+	}
+
+	template.IsCA = true
+	template.KeyUsage |= x509.KeyUsageCertSign
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	if err != nil {
+		return tls.Certificate{}, err
+	}
+
+	// create public key
+	certOut := bytes.NewBuffer(nil)
+	_ = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+
+	// create private key
+	keyOut := bytes.NewBuffer(nil)
+	b, err := x509.MarshalECPrivateKey(priv)
+	if err != nil {
+		return tls.Certificate{}, err
+	}
+	_ = pem.Encode(keyOut, &pem.Block{Type: "EC PRIVATE KEY", Bytes: b})
+
+	return tls.X509KeyPair(certOut.Bytes(), keyOut.Bytes())
+}
@@ -0,0 +1,103 @@
+package tls
+
+import (
+	"os"
+	"testing"
+)
+
+func TestConfig(t *testing.T) {
+	tests := []struct {
+		name         string
+		envVar       string
+		envValue     string
+		wantInsecure bool
+		description  string
+	}{
+		{
+			name:         "secure_by_default",
+			envVar:       "",
+			envValue:     "",
+			wantInsecure: false,
+			description:  "v6: certificate verification is on by default",
+		},
+		{
+			name:         "insecure_opt_out",
+			envVar:       "MICRO_TLS_INSECURE",
+			envValue:     "true",
+			wantInsecure: true,
+			description:  "MICRO_TLS_INSECURE=true skips verification (dev/self-signed)",
+		},
+		{
+			name:         "insecure_disabled_stays_secure",
+			envVar:       "MICRO_TLS_INSECURE",
+			envValue:     "false",
+			wantInsecure: false,
+			description:  "MICRO_TLS_INSECURE=false stays secure",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Clean up environment
+			os.Unsetenv("MICRO_TLS_SECURE")
+			os.Unsetenv("MICRO_TLS_INSECURE")
+			// Suppress warning in tests
+			os.Setenv("IN_TRAVIS_CI", "yes")
+			defer os.Unsetenv("IN_TRAVIS_CI")
+
+			// Set environment variable if specified
+			if tt.envVar != "" {
+				os.Setenv(tt.envVar, tt.envValue)
+				defer os.Unsetenv(tt.envVar)
+			}
+
+			config := Config()
+
+			if config == nil {
+				t.Fatal("Config() returned nil")
+			}
+
+			if config.InsecureSkipVerify != tt.wantInsecure {
+				t.Errorf("%s: InsecureSkipVerify = %v, want %v",
+					tt.description, config.InsecureSkipVerify, tt.wantInsecure)
+			}
+
+			// Verify MinVersion is set correctly
+			if config.MinVersion == 0 {
+				t.Error("MinVersion should be set")
+			}
+		})
+	}
+}
+
+func TestSecureConfig(t *testing.T) {
+	config := SecureConfig()
+
+	if config == nil {
+		t.Fatal("SecureConfig() returned nil")
+	}
+
+	if config.InsecureSkipVerify {
+		t.Error("SecureConfig should have InsecureSkipVerify set to false")
+	}
+
+	if config.MinVersion == 0 {
+		t.Error("MinVersion should be set")
+	}
+}
+
+func TestInsecureConfig(t *testing.T) {
+	config := InsecureConfig()
+
+	if config == nil {
+		t.Fatal("InsecureConfig() returned nil")
+	}
+
+	if !config.InsecureSkipVerify {
+		t.Error("InsecureConfig should have InsecureSkipVerify set to true")
+	}
+
+	if config.MinVersion == 0 {
+		t.Error("MinVersion should be set")
+	}
+}
@@ -0,0 +1,173 @@
+package wrapper
+
+import (
+	"context"
+	"strings"
+
+	"go-micro.dev/v6/auth"
+	"go-micro.dev/v6/client"
+	"go-micro.dev/v6/debug/stats"
+	"go-micro.dev/v6/debug/trace"
+	"go-micro.dev/v6/metadata"
+	"go-micro.dev/v6/server"
+	"go-micro.dev/v6/transport/headers"
+)
+
+type fromServiceWrapper struct {
+	client.Client
+
+	// headers to inject
+	headers metadata.Metadata
+}
+
+func (f *fromServiceWrapper) setHeaders(ctx context.Context) context.Context {
+	// don't overwrite keys
+	return metadata.MergeContext(ctx, f.headers, false)
+}
+
+func (f *fromServiceWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+	ctx = f.setHeaders(ctx)
+	return f.Client.Call(ctx, req, rsp, opts...)
+}
+
+func (f *fromServiceWrapper) Stream(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
+	ctx = f.setHeaders(ctx)
+	return f.Client.Stream(ctx, req, opts...)
+}
+
+func (f *fromServiceWrapper) Publish(ctx context.Context, p client.Message, opts ...client.PublishOption) error {
+	ctx = f.setHeaders(ctx)
+	return f.Client.Publish(ctx, p, opts...)
+}
+
+// FromService wraps a client to inject service and auth metadata.
+func FromService(name string, c client.Client) client.Client {
+	return &fromServiceWrapper{
+		c,
+		metadata.Metadata{
+			headers.Prefix + "From-Service": name,
+		},
+	}
+}
+
+// HandlerStats wraps a server handler to generate request/error stats.
+func HandlerStats(stats stats.Stats) server.HandlerWrapper {
+	// return a handler wrapper
+	return func(h server.HandlerFunc) server.HandlerFunc {
+		// return a function that returns a function
+		return func(ctx context.Context, req server.Request, rsp interface{}) error {
+			// execute the handler
+			err := h(ctx, req, rsp)
+			// record the stats
+			_ = stats.Record(err)
+			// return the error
+			return err
+		}
+	}
+}
+
+type traceWrapper struct {
+	client.Client
+
+	trace trace.Tracer
+
+	name string
+}
+
+func (c *traceWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+	newCtx, s := c.trace.Start(ctx, req.Service()+"."+req.Endpoint())
+
+	s.Type = trace.SpanTypeRequestOutbound
+	err := c.Client.Call(newCtx, req, rsp, opts...)
+	if err != nil {
+		s.Metadata["error"] = err.Error()
+	}
+
+	// finish the trace
+	_ = c.trace.Finish(s)
+
+	return err
+}
+
+// TraceCall is a call tracing wrapper.
+func TraceCall(name string, t trace.Tracer, c client.Client) client.Client {
+	return &traceWrapper{
+		name:   name,
+		trace:  t,
+		Client: c,
+	}
+}
+
+// TraceHandler wraps a server handler to perform tracing.
+func TraceHandler(t trace.Tracer) server.HandlerWrapper {
+	// return a handler wrapper
+	return func(h server.HandlerFunc) server.HandlerFunc {
+		// return a function that returns a function
+		return func(ctx context.Context, req server.Request, rsp interface{}) error {
+			// don't store traces for debug
+			if strings.HasPrefix(req.Endpoint(), "Debug.") {
+				return h(ctx, req, rsp)
+			}
+
+			// get the span
+			newCtx, s := t.Start(ctx, req.Service()+"."+req.Endpoint())
+			s.Type = trace.SpanTypeRequestInbound
+
+			err := h(newCtx, req, rsp)
+			if err != nil {
+				s.Metadata["error"] = err.Error()
+			}
+
+			// finish
+			_ = t.Finish(s)
+
+			return err
+		}
+	}
+}
+
+func AuthCall(a func() auth.Auth, c client.Client) client.Client {
+	return &authWrapper{Client: c, auth: a}
+}
+
+type authWrapper struct {
+	client.Client
+	auth func() auth.Auth
+}
+
+func (a *authWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+	// parse the options
+	var options client.CallOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// check to see if the authorization header has already been set.
+	// We dont't override the header unless the ServiceToken option has
+	// been specified or the header wasn't provided
+	if _, ok := metadata.Get(ctx, "Authorization"); ok && !options.ServiceToken {
+		return a.Client.Call(ctx, req, rsp, opts...)
+	}
+
+	// if auth is nil we won't be able to get an access token, so we execute
+	// the request without one.
+	aa := a.auth()
+	if aa == nil {
+		return a.Client.Call(ctx, req, rsp, opts...)
+	}
+
+	// set the namespace header if it has not been set (e.g. on a service to service request)
+	if _, ok := metadata.Get(ctx, headers.Namespace); !ok {
+		ctx = metadata.Set(ctx, headers.Namespace, aa.Options().Namespace)
+	}
+
+	// check to see if we have a valid access token
+	aaOpts := aa.Options()
+	if aaOpts.Token != nil && !aaOpts.Token.Expired() {
+		ctx = metadata.Set(ctx, "Authorization", auth.BearerScheme+aaOpts.Token.AccessToken)
+		return a.Client.Call(ctx, req, rsp, opts...)
+	}
+
+	// call without an auth token
+	return a.Client.Call(ctx, req, rsp, opts...)
+}
@@ -0,0 +1,52 @@
+package wrapper
+
+import (
+	"context"
+	"testing"
+
+	"go-micro.dev/v6/metadata"
+)
+
+func TestWrapper(t *testing.T) {
+	testData := []struct {
+		existing  metadata.Metadata
+		headers   metadata.Metadata
+		overwrite bool
+	}{
+		{
+			existing: metadata.Metadata{},
+			headers: metadata.Metadata{
+				"Foo": "bar",
+			},
+			overwrite: true,
+		},
+		{
+			existing: metadata.Metadata{
+				"Foo": "bar",
+			},
+			headers: metadata.Metadata{
+				"Foo": "baz",
+			},
+			overwrite: false,
+		},
+	}
+
+	for _, d := range testData {
+		c := &fromServiceWrapper{
+			headers: d.headers,
+		}
+
+		ctx := metadata.NewContext(context.Background(), d.existing)
+		ctx = c.setHeaders(ctx)
+		md, _ := metadata.FromContext(ctx)
+
+		for k, v := range d.headers {
+			if d.overwrite && md[k] != v {
+				t.Fatalf("Expected %s=%s got %s=%s", k, v, k, md[k])
+			}
+			if !d.overwrite && md[k] != d.existing[k] {
+				t.Fatalf("Expected %s=%s got %s=%s", k, d.existing[k], k, md[k])
+			}
+		}
+	}
+}