NoEcho Option Support

.travis.yml

@@ -3,7 +3,6 @@ sudo: false
 go:
 - 1.10.x
 - 1.9.x
-- 1.8.x
 install:
 - go get -t ./...
 - go get github.com/nats-io/gnatsd
@@ -17,5 +16,5 @@ before_script:
 - misspell -error -locale US .
 - megacheck -ignore "$(cat staticcheck.ignore)" ./...
 script:
-- go test -i -race ./... 
+- go test -i -race ./...
 - if [[ "$TRAVIS_GO_VERSION" == 1.9.* ]]; then ./scripts/cov.sh TRAVIS; else go test -v -race ./...; fi

nats.go

@@ -88,6 +88,7 @@ var (
 	ErrInvalidMsg           = errors.New("nats: invalid message or message nil")
 	ErrInvalidArg           = errors.New("nats: invalid argument")
 	ErrInvalidContext       = errors.New("nats: invalid context")
+	ErrNoEchoNotSupported   = errors.New("nats: no echo option not supported by this server")
 	ErrStaleConnection      = errors.New("nats: " + STALE_CONNECTION)
 )
 
@@ -167,6 +168,11 @@ type Options struct {
 	// server pool.
 	NoRandomize bool
 
+	// NoEcho configures whether the server will echo back messages
+	// that are sent on this connection if we also have matching subscriptions.
+	// Note this is supported on servers >= version 1.2. Proto 1 or greater.
+	NoEcho bool
+
 	// Name is an optional name label which will be sent to the server
 	// on CONNECT to identify the client.
 	Name string
@@ -408,6 +414,7 @@ type serverInfo struct {
 	TLSRequired  bool     `json:"tls_required"`
 	MaxPayload   int64    `json:"max_payload"`
 	ConnectURLs  []string `json:"connect_urls,omitempty"`
+	Proto        int      `json:"proto,omitempty"`
 }
 
 const (
@@ -430,6 +437,7 @@ type connectInfo struct {
 	Lang     string `json:"lang"`
 	Version  string `json:"version"`
 	Protocol int    `json:"protocol"`
+	Echo     bool   `json:"echo"`
 }
 
 // MsgHandler is a callback function that processes messages delivered to
@@ -539,6 +547,15 @@ func DontRandomize() Option {
 	}
 }
 
+// NoEcho is an Option to turn off messages echoing back from a server.
+// Note this is supported on servers >= version 1.2. Proto 1 or greater.
+func NoEcho() Option {
+	return func(o *Options) error {
+		o.NoEcho = true
+		return nil
+	}
+}
+
 // ReconnectWait is an Option to set the wait time between reconnect attempts.
 func ReconnectWait(t time.Duration) Option {
 	return func(o *Options) error {
@@ -1044,7 +1061,7 @@ func (nc *Conn) setup() {
 // Process a connected connection and initialize properly.
 func (nc *Conn) processConnectInit() error {
 
-	// Set out deadline for the whole connect process
+	// Set our deadline for the whole connect process
 	nc.conn.SetDeadline(time.Now().Add(nc.Opts.Timeout))
 	defer nc.conn.SetDeadline(time.Time{})
 
@@ -1203,18 +1220,25 @@ func (nc *Conn) connectProto() (string, error) {
 			pass, _ = u.Password()
 		}
 	} else {
-		// Take from options (pssibly all empty strings)
+		// Take from options (possibly all empty strings)
 		user = nc.Opts.User
 		pass = nc.Opts.Password
 		token = nc.Opts.Token
 	}
-	cinfo := connectInfo{o.Verbose, o.Pedantic,
-		user, pass, token,
-		o.Secure, o.Name, LangString, Version, clientProtoInfo}
+
+	cinfo := connectInfo{o.Verbose, o.Pedantic, user, pass, token,
+		o.Secure, o.Name, LangString, Version, clientProtoInfo, !o.NoEcho}
+
 	b, err := json.Marshal(cinfo)
 	if err != nil {
 		return _EMPTY_, ErrJsonParse
 	}
+
+	// Check if NoEcho is set and we have a server that supports it.
+	if o.NoEcho && nc.info.Proto < 1 {
+		return _EMPTY_, ErrNoEchoNotSupported
+	}
+
 	return fmt.Sprintf(conProto, b), nil
 }
 

nats_test.go

@@ -28,6 +28,7 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -1164,3 +1165,60 @@ func TestPingTimerLeakedOnClose(t *testing.T) {
 		t.Fatal("Pinger timer should not be set")
 	}
 }
+
+func TestNoEcho(t *testing.T) {
+	s := RunServerOnPort(TEST_PORT)
+	defer s.Shutdown()
+
+	url := fmt.Sprintf("nats://127.0.0.1:%d", TEST_PORT)
+
+	nc, err := Connect(url, NoEcho())
+	if err != nil {
+		t.Fatalf("Error on connect: %v", err)
+	}
+	defer nc.Close()
+
+	r := int32(0)
+	_, err = nc.Subscribe("foo", func(m *Msg) {
+		atomic.AddInt32(&r, 1)
+	})
+	if err != nil {
+		t.Fatalf("Error on subscribe: %v", err)
+	}
+
+	err = nc.Publish("foo", []byte("Hello World"))
+	if err != nil {
+		t.Fatalf("Error on publish: %v", err)
+	}
+	nc.Flush()
+	nc.Flush()
+
+	if nr := atomic.LoadInt32(&r); nr != 0 {
+		t.Fatalf("Expected no messages echoed back, received %d\n", nr)
+	}
+}
+
+func TestNoEchoOldServer(t *testing.T) {
+	opts := GetDefaultOptions()
+	opts.Url = DefaultURL
+	opts.NoEcho = true
+
+	nc := &Conn{Opts: opts}
+	if err := nc.setupServerPool(); err != nil {
+		t.Fatalf("Problem setting up Server Pool: %v\n", err)
+	}
+
+	// Old style with no proto, meaning 0. We need Proto:1 for NoEcho support.
+	oldInfo := "{\"server_id\":\"22\",\"version\":\"1.1.0\",\"go\":\"go1.10.2\",\"port\":4222,\"max_payload\":1048576}"
+
+	err := nc.processInfo(oldInfo)
+	if err != nil {
+		t.Fatalf("Error processing old style INFO: %v\n", err)
+	}
+
+	// Make sure connectProto generates an error.
+	_, err = nc.connectProto()
+	if err == nil {
+		t.Fatalf("Expected an error but got none\n")
+	}
+}

test/auth_test.go

@@ -186,7 +186,7 @@ func TestPermViolation(t *testing.T) {
 	opts := test.DefaultTestOptions
 	opts.Port = 8232
 	opts.Users = []*server.User{
-		&server.User{
+		{
 			Username: "ivan",
 			Password: "pwd",
 			Permissions: &server.Permissions{

test/conn_test.go

@@ -1364,8 +1364,8 @@ func TestUseCustomDialer(t *testing.T) {
 	// should take precedence. That means that the connection
 	// should fail for these two set of options.
 	options := []*nats.Options{
-		&nats.Options{Dialer: dialer, CustomDialer: cdialer},
-		&nats.Options{CustomDialer: cdialer},
+		{Dialer: dialer, CustomDialer: cdialer},
+		{CustomDialer: cdialer},
 	}
 	for _, o := range options {
 		o.Servers = []string{nats.DefaultURL}
@@ -1386,8 +1386,8 @@ func TestUseCustomDialer(t *testing.T) {
 	}
 	// Same with variadic
 	foptions := [][]nats.Option{
-		[]nats.Option{nats.Dialer(dialer), nats.SetCustomDialer(cdialer)},
-		[]nats.Option{nats.SetCustomDialer(cdialer)},
+		{nats.Dialer(dialer), nats.SetCustomDialer(cdialer)},
+		{nats.SetCustomDialer(cdialer)},
 	}
 	for _, fos := range foptions {
 		nc, err := nats.Connect(nats.DefaultURL, fos...)