[client] Cache server key

shared/management/client/grpc.go

@@ -44,6 +44,9 @@ type GrpcClient struct {
 	conn                  *grpc.ClientConn
 	connStateCallback     ConnStateNotifier
 	connStateCallbackLock sync.RWMutex
+
+	srvKey   *wgtypes.Key
+	srvKeyMu sync.RWMutex
 }
 
 // NewClient creates a new client to Management service
@@ -122,11 +125,14 @@ func (c *GrpcClient) Sync(ctx context.Context, sysInfo *system.Info, msgHandler
 			return fmt.Errorf("connection to management is not ready and in %s state", connState)
 		}
 
-		serverPubKey, err := c.GetServerPublicKey()
+		serverPubKey, err := c.refreshServerKey()
 		if err != nil {
 			log.Debugf(errMsgMgmtPublicKey, err)
 			return err
 		}
+		c.srvKeyMu.Lock()
+		c.srvKey = serverPubKey
+		c.srvKeyMu.Unlock()
 
 		return c.handleStream(ctx, *serverPubKey, sysInfo, msgHandler)
 	}
@@ -270,20 +276,21 @@ func (c *GrpcClient) GetServerPublicKey() (*wgtypes.Key, error) {
 		return nil, errors.New(errMsgNoMgmtConnection)
 	}
 
-	mgmCtx, cancel := context.WithTimeout(c.ctx, 5*time.Second)
-	defer cancel()
-	resp, err := c.realClient.GetServerKey(mgmCtx, &proto.Empty{})
-	if err != nil {
-		log.Errorf("failed while getting Management Service public key: %v", err)
-		return nil, fmt.Errorf("failed while getting Management Service public key")
+	c.srvKeyMu.RLock()
+	if c.srvKey != nil {
+		c.srvKeyMu.RUnlock()
+		return c.srvKey, nil
 	}
+	c.srvKeyMu.RUnlock()
 
-	serverKey, err := wgtypes.ParseKey(resp.Key)
+	srvKey, err := c.refreshServerKey()
 	if err != nil {
 		return nil, err
 	}
-
-	return &serverKey, nil
+	c.srvKeyMu.Lock()
+	c.srvKey = srvKey
+	c.srvKeyMu.Unlock()
+	return srvKey, nil
 }
 
 // IsHealthy probes the gRPC connection and returns false on errors
@@ -312,6 +319,26 @@ func (c *GrpcClient) IsHealthy() bool {
 	return true
 }
 
+func (c *GrpcClient) refreshServerKey() (*wgtypes.Key, error) {
+	if !c.ready() {
+		return nil, errors.New(errMsgNoMgmtConnection)
+	}
+
+	mgmCtx, cancel := context.WithTimeout(c.ctx, 5*time.Second)
+	defer cancel()
+	resp, err := c.realClient.GetServerKey(mgmCtx, &proto.Empty{})
+	if err != nil {
+		log.Errorf("failed while getting Management Service public key: %v", err)
+		return nil, fmt.Errorf("failed while getting Management Service public key")
+	}
+
+	serverKey, err := wgtypes.ParseKey(resp.Key)
+	if err != nil {
+		return nil, err
+	}
+	return &serverKey, nil
+}
+
 func (c *GrpcClient) login(serverKey wgtypes.Key, req *proto.LoginRequest) (*proto.LoginResponse, error) {
 	if !c.ready() {
 		return nil, errors.New(errMsgNoMgmtConnection)