292                     let packet = wire::Ipv4Packet::new_unchecked(buf);  in read()  localVariable
296                             addr: wire::IpAddress::Ipv4(packet.src_addr()),  in read()
351                     let mut packet: wire::Ipv4Packet<&mut Vec<u8>> =  in write()  localVariable
355                     packet.set_version(4);  in write()
356                     packet.set_header_len(20);  in write()
357                     packet.set_total_len((20 + len) as u16);  in write()
358                     packet.set_src_addr(ipv4_src_addr);  in write()
359                     packet.set_dst_addr(ipv4_dst);  in write()
362                     packet.set_next_header(socket.ip_protocol().into());  in write()
365                     let payload: &mut [u8] = packet.payload_mut();  in write()
369                     packet.fill_checksum();  in write()