Enum nix::sys::socket::ControlMessageOwned

pub enum ControlMessageOwned {
    ScmRights(Vec<RawFd>),
    ScmTimestamp(TimeVal),
    Ipv6PacketInfo(in6_pktinfo),
    Ipv4RecvIf(sockaddr_dl),
    Ipv4RecvDstAddr(in_addr),
    // some variants omitted
}

A type-safe wrapper around a single control message, as used with recvmsg.

Further reading

Variants

ScmRights(Vec<RawFd>)

Received version of [ControlMessage::ScmRights][#enum.ControlMessage.html#variant.ScmRights]

ScmTimestamp(TimeVal)

A message of type SCM_TIMESTAMP, containing the time the packet was received by the kernel.

See the kernel's explanation in "SO_TIMESTAMP" of networking/timestamping.

Examples

// Set up
let message = "Ohayō!".as_bytes();
let in_socket = socket(
    AddressFamily::Inet,
    SockType::Datagram,
    SockFlag::empty(),
    None).unwrap();
setsockopt(in_socket, sockopt::ReceiveTimestamp, &true).unwrap();
let localhost = InetAddr::new(IpAddr::new_v4(127, 0, 0, 1), 0);
bind(in_socket, &SockAddr::new_inet(localhost)).unwrap();
let address = getsockname(in_socket).unwrap();
// Get initial time
let time0 = SystemTime::now();
// Send the message
let iov = [IoVec::from_slice(message)];
let flags = MsgFlags::empty();
let l = sendmsg(in_socket, &iov, &[], flags, Some(&address)).unwrap();
assert_eq!(message.len(), l);
// Receive the message
let mut buffer = vec![0u8; message.len()];
let mut cmsgspace = cmsg_space!(TimeVal);
let iov = [IoVec::from_mut_slice(&mut buffer)];
let r = recvmsg(in_socket, &iov, Some(&mut cmsgspace), flags).unwrap();
let rtime = match r.cmsgs().next() {
    Some(ControlMessageOwned::ScmTimestamp(rtime)) => rtime,
    Some(_) => panic!("Unexpected control message"),
    None => panic!("No control message")
};
// Check the final time
let time1 = SystemTime::now();
// the packet's received timestamp should lie in-between the two system
// times, unless the system clock was adjusted in the meantime.
let rduration = Duration::new(rtime.tv_sec() as u64,
                              rtime.tv_usec() as u32 * 1000);
assert!(time0.duration_since(UNIX_EPOCH).unwrap() <= rduration);
assert!(rduration <= time1.duration_since(UNIX_EPOCH).unwrap());
// Close socket
nix::unistd::close(in_socket).unwrap();

Ipv6PacketInfo(in6_pktinfo)

Ipv4RecvIf(sockaddr_dl)

Ipv4RecvDstAddr(in_addr)