val get_checksum : Cstruct.t -> Cstruct.uint16val set_checksum : Cstruct.t -> Cstruct.uint16 -> unitval cur_hop_limit_off : intval get_cur_hop_limit : Cstruct.t -> Cstruct.uint8val router_lifetime_off : intval get_router_lifetime : Cstruct.t -> Cstruct.uint16val reachable_time_off : intval get_reachable_time : Cstruct.t -> Cstruct.uint32val retrans_timer_off : intval get_retrans_timer : Cstruct.t -> Cstruct.uint32