extern void utcp_set_rcvbuf(struct utcp_connection *connection, size_t size);
extern size_t utcp_get_rcvbuf_free(struct utcp_connection *connection);
extern void utcp_set_rcvbuf(struct utcp_connection *connection, size_t size);
extern size_t utcp_get_rcvbuf_free(struct utcp_connection *connection);