Replace the grpc header key to NetBird specific

client/internal/engine.go

@@ -888,7 +888,6 @@ func (e *Engine) receiveSignalEvents() {
 		err := e.signal.Receive(func(msg *sProto.Message) error {
 			e.syncMsgMux.Lock()
 			defer e.syncMsgMux.Unlock()
-
 			conn := e.peerConns[msg.Key]
 			if conn == nil {
 				return fmt.Errorf("wrongly addressed message %s", msg.Key)

keepalive/client.go

@@ -0,0 +1,5 @@
+package keepalive
+
+func IsKeepAliveMsg(body []byte) bool {
+	return len(body) == 0
+}

keepalive/keep_alive.go

@@ -0,0 +1,155 @@
+package keepalive
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+const (
+	GrpcVersionHeaderKey = "x-netbird-version"
+
+	reversProxyHeaderKey = "x-netbird-peer"
+	keepAliveInterval    = 30 * time.Second
+)
+
+type KeepAlive struct {
+	sync.RWMutex
+	ticker       *time.Ticker
+	done         chan struct{}
+	streams      map[string]*ioMonitor
+	keepAliveMsg interface{}
+}
+
+func NewKeepAlive(keepAliveMsg interface{}) *KeepAlive {
+	ka := &KeepAlive{
+		ticker:       time.NewTicker(1 * time.Second),
+		done:         make(chan struct{}),
+		streams:      make(map[string]*ioMonitor),
+		keepAliveMsg: keepAliveMsg,
+	}
+	go ka.start()
+	return ka
+}
+
+func (k *KeepAlive) StreamInterceptor() grpc.StreamServerInterceptor {
+	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		address, supported := k.keepAliveIsSupported(stream.Context())
+		if !supported {
+			return handler(srv, stream)
+		}
+
+		m := &ioMonitor{
+			sync.Mutex{},
+			sync.Mutex{},
+			stream,
+			time.Now(),
+		}
+
+		k.addIoMonitor(address, m)
+
+		return handler(srv, m)
+	}
+}
+
+func (k *KeepAlive) UnaryInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
+		address, supported := k.keepAliveIsSupported(ctx)
+		if supported {
+			k.updateLastSeen(address)
+		}
+		return handler(ctx, req)
+	}
+}
+
+func (k *KeepAlive) Stop() {
+	select {
+	case k.done <- struct{}{}:
+		k.ticker.Stop()
+		return
+	default:
+	}
+}
+
+func (k *KeepAlive) start() {
+	for {
+		select {
+		case <-k.done:
+			return
+		case t := <-k.ticker.C:
+			k.checkKeepAlive(t)
+		}
+	}
+}
+
+func (k *KeepAlive) checkKeepAlive(now time.Time) {
+	k.Lock()
+	defer k.Unlock()
+	for addr, m := range k.streams {
+		if k.isKeepAliveOutDated(now, m) {
+			continue
+		}
+		err := k.sendKeepAlive(m)
+		if err != nil {
+			log.Debugf("stop keepalive for: %s", addr)
+			delete(k.streams, addr)
+		}
+	}
+}
+
+func (k *KeepAlive) keepAliveIsSupported(ctx context.Context) (string, bool) {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		log.Warnf("metadata not found")
+		return "", false
+	}
+
+	peerAddress := k.addressFromHeader(md)
+	if peerAddress == "" {
+		log.Debugf("peer is not using reverse proxy")
+		return "", false
+	}
+
+	if len(md.Get(GrpcVersionHeaderKey)) == 0 {
+		log.Debugf("version info not found")
+		return "", false
+	}
+	return peerAddress, true
+}
+
+func (k *KeepAlive) addIoMonitor(address string, m *ioMonitor) {
+	k.Lock()
+	defer k.Unlock()
+	log.Debugf("add stream address for keepalive list: %s", address)
+	k.streams[address] = m
+}
+
+func (k *KeepAlive) sendKeepAlive(m *ioMonitor) error {
+	return m.sendMsg(k.keepAliveMsg)
+}
+
+func (k *KeepAlive) updateLastSeen(address string) {
+	k.RLock()
+	m, ok := k.streams[address]
+	k.RUnlock()
+	if !ok {
+		return
+	}
+	m.updateLastSeen()
+}
+
+func (k *KeepAlive) addressFromHeader(md metadata.MD) string {
+	peer := md.Get(reversProxyHeaderKey)
+	if len(peer) == 0 {
+		return ""
+	}
+	return peer[0]
+}
+
+func (k *KeepAlive) isKeepAliveOutDated(now time.Time, m *ioMonitor) bool {
+	return now.Sub(m.getLastSeen()) < keepAliveInterval
+}

keepalive/monitor.go

@@ -0,0 +1,35 @@
+package keepalive
+
+import (
+	"sync"
+	"time"
+
+	"google.golang.org/grpc"
+)
+
+type ioMonitor struct {
+	mu         sync.Mutex
+	streamLock sync.Mutex
+	grpc.ServerStream
+	lastSeen time.Time
+}
+
+func (l *ioMonitor) sendMsg(m interface{}) error {
+	l.updateLastSeen()
+	l.streamLock.Lock()
+	defer l.streamLock.Unlock()
+	return l.ServerStream.SendMsg(m)
+}
+
+func (l *ioMonitor) updateLastSeen() {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.lastSeen = time.Now()
+}
+
+func (l *ioMonitor) getLastSeen() time.Time {
+	l.mu.Lock()
+	t := l.lastSeen
+	l.mu.Unlock()
+	return t
+}

management/client/grpc.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 	gstatus "google.golang.org/grpc/status"
 
 	log "github.com/sirupsen/logrus"
@@ -23,7 +24,9 @@ import (
 
 	"github.com/netbirdio/netbird/client/system"
 	"github.com/netbirdio/netbird/encryption"
+	appKeepAlive "github.com/netbirdio/netbird/keepalive"
 	"github.com/netbirdio/netbird/management/proto"
+	"github.com/netbirdio/netbird/version"
 )
 
 // ConnStateNotifier is a wrapper interface of the status recorders
@@ -67,6 +70,9 @@ func NewClient(ctx context.Context, addr string, ourPrivateKey wgtypes.Key, tlsE
 
 	realClient := proto.NewManagementServiceClient(conn)
 
+	md := metadata.Pairs(appKeepAlive.GrpcVersionHeaderKey, version.NetbirdVersion())
+	ctx = metadata.NewOutgoingContext(ctx, md)
+
 	return &GrpcClient{
 		key:                   ourPrivateKey,
 		realClient:            realClient,
@@ -131,6 +137,7 @@ func (c *GrpcClient) Sync(msgHandler func(msg *proto.SyncResponse) error) error
 
 		ctx, cancelStream := context.WithCancel(c.ctx)
 		defer cancelStream()
+
 		stream, err := c.connectToStream(ctx, *serverPubKey)
 		if err != nil {
 			log.Debugf("failed to open Management Service stream: %s", err)
@@ -246,6 +253,10 @@ func (c *GrpcClient) receiveEvents(stream proto.ManagementService_SyncClient, se
 			return err
 		}
 
+		if appKeepAlive.IsKeepAliveMsg(update.Body) {
+			continue
+		}
+
 		log.Debugf("got an update message from Management Service")
 		decryptedResp := &proto.SyncResponse{}
 		err = encryption.DecryptMessage(serverPubKey, c.key, update.Body, decryptedResp)

management/cmd/management.go

@@ -40,6 +40,7 @@ import (
 	"google.golang.org/grpc/keepalive"
 
 	"github.com/netbirdio/netbird/encryption"
+	grpcKeepAlive "github.com/netbirdio/netbird/keepalive"
 	mgmtProto "github.com/netbirdio/netbird/management/proto"
 )
 
@@ -202,11 +203,17 @@ var (
 				return fmt.Errorf("failed creating HTTP API handler: %v", err)
 			}
 
-			gRPCAPIHandler := grpc.NewServer(gRPCOpts...)
 			srv, err := server.NewServer(config, accountManager, peersUpdateManager, turnManager, appMetrics)
 			if err != nil {
 				return fmt.Errorf("failed creating gRPC API handler: %v", err)
 			}
+
+			ka := grpcKeepAlive.NewKeepAlive(&mgmtProto.KeepAlive{})
+			defer ka.Stop()
+			sInterc := grpc.StreamInterceptor(ka.StreamInterceptor())
+			uInterc := grpc.UnaryInterceptor(ka.UnaryInterceptor())
+			gRPCOpts = append(gRPCOpts, sInterc, uInterc)
+			gRPCAPIHandler := grpc.NewServer(gRPCOpts...)
 			mgmtProto.RegisterManagementServiceServer(gRPCAPIHandler, srv)
 
 			installationID, err := getInstallationID(store)

management/proto/management.proto

@@ -329,3 +329,5 @@ message FirewallRule {
     ICMP = 4;
   }
 }
+
+message KeepAlive {}

signal/client/grpc.go

@@ -21,7 +21,9 @@ import (
 	"google.golang.org/grpc/status"
 
 	"github.com/netbirdio/netbird/encryption"
+	appKeepAlive "github.com/netbirdio/netbird/keepalive"
 	"github.com/netbirdio/netbird/signal/proto"
+	"github.com/netbirdio/netbird/version"
 )
 
 const defaultSendTimeout = 5 * time.Second
@@ -73,6 +75,7 @@ func NewClient(ctx context.Context, addr string, key wgtypes.Key, tlsEnabled boo
 
 	sigCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
 	defer cancel()
+
 	conn, err := grpc.DialContext(
 		sigCtx,
 		addr,
@@ -87,9 +90,14 @@ func NewClient(ctx context.Context, addr string, key wgtypes.Key, tlsEnabled boo
 		log.Errorf("failed to connect to the signalling server %v", err)
 		return nil, err
 	}
-
 	log.Debugf("connected to Signal Service: %v", conn.Target())
 
+	md := metadata.New(map[string]string{
+		proto.HeaderId:                    key.PublicKey().String(), // add key fingerprint to the request header to be identified on the server side
+		appKeepAlive.GrpcVersionHeaderKey: version.NetbirdVersion(), // add version info to ensure keep alive is supported
+	})
+	ctx = metadata.NewOutgoingContext(ctx, md)
+
 	return &GrpcClient{
 		realClient:            proto.NewSignalExchangeClient(conn),
 		ctx:                   ctx,
@@ -146,7 +154,7 @@ func (c *GrpcClient) Receive(msgHandler func(msg *proto.Message) error) error {
 		// todo once the key rotation logic has been implemented, consider changing to some other identifier (received from management)
 		ctx, cancelStream := context.WithCancel(c.ctx)
 		defer cancelStream()
-		stream, err := c.connect(ctx, c.key.PublicKey().String())
+		stream, err := c.connect(ctx)
 		if err != nil {
 			log.Warnf("disconnected from the Signal Exchange due to an error: %v", err)
 			return err
@@ -208,13 +216,9 @@ func (c *GrpcClient) getStreamStatusChan() <-chan struct{} {
 	return c.connectedCh
 }
 
-func (c *GrpcClient) connect(ctx context.Context, key string) (proto.SignalExchange_ConnectStreamClient, error) {
+func (c *GrpcClient) connect(ctx context.Context) (proto.SignalExchange_ConnectStreamClient, error) {
 	c.stream = nil
-
+	stream, err := c.realClient.ConnectStream(ctx, grpc.WaitForReady(true))
-	// add key fingerprint to the request header to be identified on the server side
-	md := metadata.New(map[string]string{proto.HeaderId: key})
-	metaCtx := metadata.NewOutgoingContext(ctx, md)
-	stream, err := c.realClient.ConnectStream(metaCtx, grpc.WaitForReady(true))
 	c.stream = stream
 	if err != nil {
 		return nil, err
@@ -366,6 +370,12 @@ func (c *GrpcClient) receive(stream proto.SignalExchange_ConnectStreamClient,
 		} else if err != nil {
 			return err
 		}
+
+		if appKeepAlive.IsKeepAliveMsg(msg.Body) {
+			log.Tracef("received keepalive")
+			continue
+		}
+
 		log.Tracef("received a new message from Peer [fingerprint: %s]", msg.Key)
 
 		decryptedMessage, err := c.decryptMessage(msg)

signal/cmd/run.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"golang.org/x/crypto/acme/autocert"
 	"io"
 	"io/fs"
 	"net"
@@ -14,15 +13,18 @@ import (
 	"strings"
 	"time"
 
-	"github.com/netbirdio/netbird/encryption"
-	"github.com/netbirdio/netbird/signal/proto"
-	"github.com/netbirdio/netbird/signal/server"
-	"github.com/netbirdio/netbird/util"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"golang.org/x/crypto/acme/autocert"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
+
+	"github.com/netbirdio/netbird/encryption"
+	appKeepAlive "github.com/netbirdio/netbird/keepalive"
+	"github.com/netbirdio/netbird/signal/proto"
+	"github.com/netbirdio/netbird/signal/server"
+	"github.com/netbirdio/netbird/util"
 )
 
 var (
@@ -93,6 +95,13 @@ var (
 			}
 
 			opts = append(opts, signalKaep, signalKasp)
+
+			ka := appKeepAlive.NewKeepAlive(&proto.KeepAlive{})
+			defer ka.Stop()
+			sInterc := grpc.StreamInterceptor(ka.StreamInterceptor())
+			uInterc := grpc.UnaryInterceptor(ka.UnaryInterceptor())
+			opts = append(opts, sInterc, uInterc)
+
 			grpcServer := grpc.NewServer(opts...)
 			proto.RegisterSignalExchangeServer(grpcServer, server.NewServer())
 

signal/proto/signalexchange.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.26.0
-// 	protoc        v3.21.9
+// 	protoc        v3.21.12
 // source: signalexchange.proto
 
 package proto
@@ -347,6 +347,44 @@ func (x *Mode) GetDirect() bool {
 	return false
 }
 
+type KeepAlive struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+}
+
+func (x *KeepAlive) Reset() {
+	*x = KeepAlive{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_signalexchange_proto_msgTypes[4]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *KeepAlive) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*KeepAlive) ProtoMessage() {}
+
+func (x *KeepAlive) ProtoReflect() protoreflect.Message {
+	mi := &file_signalexchange_proto_msgTypes[4]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use KeepAlive.ProtoReflect.Descriptor instead.
+func (*KeepAlive) Descriptor() ([]byte, []int) {
+	return file_signalexchange_proto_rawDescGZIP(), []int{4}
+}
+
 var File_signalexchange_proto protoreflect.FileDescriptor
 
 var file_signalexchange_proto_rawDesc = []byte{
@@ -388,20 +426,20 @@ var file_signalexchange_proto_rawDesc = []byte{
 	0x45, 0x10, 0x04, 0x22, 0x2e, 0x0a, 0x04, 0x4d, 0x6f, 0x64, 0x65, 0x12, 0x1b, 0x0a, 0x06, 0x64,
 	0x69, 0x72, 0x65, 0x63, 0x74, 0x18, 0x01, 0x20, 0x01, 0x28, 0x08, 0x48, 0x00, 0x52, 0x06, 0x64,
 	0x69, 0x72, 0x65, 0x63, 0x74, 0x88, 0x01, 0x01, 0x42, 0x09, 0x0a, 0x07, 0x5f, 0x64, 0x69, 0x72,
-	0x65, 0x63, 0x74, 0x32, 0xb9, 0x01, 0x0a, 0x0e, 0x53, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x45, 0x78,
+	0x65, 0x63, 0x74, 0x22, 0x0b, 0x0a, 0x09, 0x4b, 0x65, 0x65, 0x70, 0x41, 0x6c, 0x69, 0x76, 0x65,
-	0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x12, 0x4c, 0x0a, 0x04, 0x53, 0x65, 0x6e, 0x64, 0x12, 0x20,
+	0x32, 0xb9, 0x01, 0x0a, 0x0e, 0x53, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x45, 0x78, 0x63, 0x68, 0x61,
-	0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e,
+	0x6e, 0x67, 0x65, 0x12, 0x4c, 0x0a, 0x04, 0x53, 0x65, 0x6e, 0x64, 0x12, 0x20, 0x2e, 0x73, 0x69,
-	0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65,
+	0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e, 0x45, 0x6e, 0x63,
-	0x1a, 0x20, 0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63, 0x68, 0x61, 0x6e, 0x67,
+	0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x1a, 0x20, 0x2e,
-	0x65, 0x2e, 0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d, 0x65, 0x73, 0x73, 0x61,
+	0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e, 0x45,
-	0x67, 0x65, 0x22, 0x00, 0x12, 0x59, 0x0a, 0x0d, 0x43, 0x6f, 0x6e, 0x6e, 0x65, 0x63, 0x74, 0x53,
+	0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x22,
-	0x74, 0x72, 0x65, 0x61, 0x6d, 0x12, 0x20, 0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78,
+	0x00, 0x12, 0x59, 0x0a, 0x0d, 0x43, 0x6f, 0x6e, 0x6e, 0x65, 0x63, 0x74, 0x53, 0x74, 0x72, 0x65,
-	0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e, 0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64,
+	0x61, 0x6d, 0x12, 0x20, 0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63, 0x68, 0x61,
-	0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x1a, 0x20, 0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c,
+	0x6e, 0x67, 0x65, 0x2e, 0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d, 0x65, 0x73,
-	0x65, 0x78, 0x63, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e, 0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74,
+	0x73, 0x61, 0x67, 0x65, 0x1a, 0x20, 0x2e, 0x73, 0x69, 0x67, 0x6e, 0x61, 0x6c, 0x65, 0x78, 0x63,
-	0x65, 0x64, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x22, 0x00, 0x28, 0x01, 0x30, 0x01, 0x42,
+	0x68, 0x61, 0x6e, 0x67, 0x65, 0x2e, 0x45, 0x6e, 0x63, 0x72, 0x79, 0x70, 0x74, 0x65, 0x64, 0x4d,
-	0x08, 0x5a, 0x06, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f,
+	0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x22, 0x00, 0x28, 0x01, 0x30, 0x01, 0x42, 0x08, 0x5a, 0x06,
-	0x33,
+	0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -417,13 +455,14 @@ func file_signalexchange_proto_rawDescGZIP() []byte {
 }
 
 var file_signalexchange_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_signalexchange_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_signalexchange_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_signalexchange_proto_goTypes = []interface{}{
 	(Body_Type)(0),           // 0: signalexchange.Body.Type
 	(*EncryptedMessage)(nil), // 1: signalexchange.EncryptedMessage
 	(*Message)(nil),          // 2: signalexchange.Message
 	(*Body)(nil),             // 3: signalexchange.Body
 	(*Mode)(nil),             // 4: signalexchange.Mode
+	(*KeepAlive)(nil),        // 5: signalexchange.KeepAlive
 }
 var file_signalexchange_proto_depIdxs = []int32{
 	3, // 0: signalexchange.Message.body:type_name -> signalexchange.Body
@@ -494,6 +533,18 @@ func file_signalexchange_proto_init() {
 				return nil
 			}
 		}
+		file_signalexchange_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*KeepAlive); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
 	}
 	file_signalexchange_proto_msgTypes[3].OneofWrappers = []interface{}{}
 	type x struct{}
@@ -502,7 +553,7 @@ func file_signalexchange_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_signalexchange_proto_rawDesc,
 			NumEnums:      1,
-			NumMessages:   4,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

signal/proto/signalexchange.proto

@@ -63,3 +63,5 @@ message Body {
 message Mode {
   optional bool direct = 1;
 }
+
+message KeepAlive {}