-extern bool send_add_subnet(struct connection_t *, struct subnet_t *);
-extern bool send_del_subnet(struct connection_t *, struct subnet_t *);
-extern bool send_add_edge(struct connection_t *, struct edge_t *);
-extern bool send_del_edge(struct connection_t *, struct edge_t *);
-extern bool send_key_changed(struct connection_t *, struct node_t *);
-extern bool send_req_key(struct connection_t *, struct node_t *, struct node_t *);
-extern bool send_ans_key(struct connection_t *, struct node_t *, struct node_t *);
+extern bool send_add_subnet(struct connection_t *, const struct subnet_t *);
+extern bool send_del_subnet(struct connection_t *, const struct subnet_t *);
+extern bool send_add_edge(struct connection_t *, const struct edge_t *);
+extern bool send_del_edge(struct connection_t *, const struct edge_t *);
+extern bool send_key_changed(struct connection_t *, const struct node_t *);
+extern bool send_req_key(struct connection_t *, const struct node_t *, const struct node_t *);
+extern bool send_ans_key(struct connection_t *, const struct node_t *, const struct node_t *);