val get_checksum : Cstruct.t -> Cstruct.uint16val set_checksum : Cstruct.t -> Cstruct.uint16 -> unitval get_reserved : Cstruct.t -> Cstruct.uint32val set_reserved : Cstruct.t -> Cstruct.uint32 -> unitval get_target : Cstruct.t -> Ipaddr.V6.tval set_target : Cstruct.t -> Ipaddr.V6.t -> unit