cmcd: set JSON arrays even if empty

Signed-off-by: Simon Ott <simon.ott@aisec.fraunhofer.de>

Author: smo4201

cmcd/coap.go

@@ -369,6 +369,8 @@ func (s CoapServer) PeerCache(w mux.ResponseWriter, r *mux.Message) {
 	c, ok := s.cmc.CachedPeerMetadata[req.Peer]
 	if ok {
 		resp.Cache = maps.Keys(c)
+	} else {
+		resp.Cache = []string{}
 	}
 
 	payload, err := ser.Marshal(&resp)

cmcd/grpc.go

@@ -301,6 +301,8 @@ func (s *GrpcServer) PeerCache(ctx context.Context, req *api.PeerCacheRequest) (
 	c, ok := s.cmc.CachedPeerMetadata[req.Peer]
 	if ok {
 		resp.Cache = maps.Keys(c)
+	} else {
+		resp.Cache = []string{}
 	}
 
 	log.Info("Served grpc request type 'PeerCache'")

cmcd/socket.go

@@ -407,6 +407,8 @@ func fetchPeerCache(conn net.Conn, payload []byte, cmc *c.Cmc, s ar.Serializer)
 	c, ok := cmc.CachedPeerMetadata[req.Peer]
 	if ok {
 		resp.Cache = maps.Keys(c)
+	} else {
+		resp.Cache = []string{}
 	}
 
 	log.Tracef("Collected peer cache with %v elements", len(cmc.CachedPeerMetadata[req.Peer]))