#[non_exhaustive]
pub enum ControlMessageOwned { ScmRights(Vec<RawFd>), ScmTimestamp(TimeVal), RxqOvfl(u32), }
Expand description

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

Further reading

Variants (Non-exhaustive)§

This enum is marked as non-exhaustive
Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.
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ScmRights(Vec<RawFd>)

Received version of ControlMessage::ScmRights

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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 = SockaddrIn::from_str("127.0.0.1:0").unwrap();
bind(in_socket, &localhost).unwrap();
let address: SockaddrIn = getsockname(in_socket).unwrap();
// Get initial time
let time0 = SystemTime::now();
// Send the message
let iov = [IoSlice::new(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 mut iov = [IoSliceMut::new(&mut buffer)];
let r = recvmsg::<SockaddrIn>(in_socket, &mut 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();
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RxqOvfl(u32)

SO_RXQ_OVFL indicates that an unsigned 32 bit value ancilliary msg (cmsg) should be attached to recieved skbs indicating the number of packets dropped by the socket between the last recieved packet and this received packet.

RxqOvfl socket option should be enabled on a socket to allow receiving the drop counter.

Trait Implementations§

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impl Clone for ControlMessageOwned

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fn clone(&self) -> ControlMessageOwned

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for ControlMessageOwned

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl PartialEq for ControlMessageOwned

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fn eq(&self, other: &ControlMessageOwned) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Eq for ControlMessageOwned

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impl StructuralPartialEq for ControlMessageOwned

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.