Enum nix::sys::socket::ControlMessage

#[non_exhaustive]
pub enum ControlMessage<'a> {
    ScmRights(&'a [RawFd]),
    ScmCredentials(&'a UnixCredentials),
    AlgSetIv(&'a [u8]),
    AlgSetOp(&'a c_int),
    AlgSetAeadAssoclen(&'a u32),
    UdpGsoSegments(&'a u16),
    Ipv4PacketInfo(&'a in_pktinfo),
    Ipv6PacketInfo(&'a in6_pktinfo),
    Ipv6HopLimit(&'a c_int),
    RxqOvfl(&'a u32),
    TxTime(&'a u64),
}

A type-safe zero-copy wrapper around a single control message, as used with sendmsg. More types may be added to this enum; do not exhaustively pattern-match it.

Further reading

Variants (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.

ScmRights(&'a [RawFd])

A message of type SCM_RIGHTS, containing an array of file descriptors passed between processes.

See the description in the “Ancillary messages” section of the unix(7) man page.

Using multiple ScmRights messages for a single sendmsg call isn’t recommended since it causes platform-dependent behaviour: It might swallow all but the first ScmRights message or fail with EINVAL. Instead, you can put all fds to be passed into a single ScmRights message.

ScmCredentials(&'a UnixCredentials)

A message of type SCM_CREDENTIALS, containing the pid, uid and gid of a process connected to the socket.

This is similar to the socket option SO_PEERCRED, but requires a process to explicitly send its credentials. A process running as root is allowed to specify any credentials, while credentials sent by other processes are verified by the kernel.

For further information, please refer to the unix(7) man page.

AlgSetIv(&'a [u8])

Set IV for AF_ALG crypto API.

For further information, please refer to the documentation

AlgSetOp(&'a c_int)

Set crypto operation for AF_ALG crypto API. It may be one of ALG_OP_ENCRYPT or ALG_OP_DECRYPT

For further information, please refer to the documentation

AlgSetAeadAssoclen(&'a u32)

Set the length of associated authentication data (AAD) (applicable only to AEAD algorithms) for AF_ALG crypto API.

For further information, please refer to the documentation

UdpGsoSegments(&'a u16)

UDP GSO makes it possible for applications to generate network packets for a virtual MTU much greater than the real one. The length of the send data no longer matches the expected length on the wire. The size of the datagram payload as it should appear on the wire may be passed through this control message. Send buffer should consist of multiple fixed-size wire payloads following one by one, and the last, possibly smaller one.

Ipv4PacketInfo(&'a in_pktinfo)

Configure the sending addressing and interface for v4.

For further information, please refer to the ip(7) man page.

Ipv6PacketInfo(&'a in6_pktinfo)

Configure the sending addressing and interface for v6.

For further information, please refer to the ipv6(7) man page.

Ipv6HopLimit(&'a c_int)

Configure the hop limit for v6 multicast traffic.

Set the IPv6 hop limit for this message. The argument is an integer between 0 and 255. A value of -1 will set the hop limit to the route default if possible on the interface. Without this cmsg, packets sent with sendmsg have a hop limit of 1 and will not leave the local network. For further information, please refer to the ipv6(7) man page.

RxqOvfl(&'a 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.

TxTime(&'a u64)

Configure the transmission time of packets.

For further information, please refer to the tc-etf(8) man page.

Trait Implementations

impl<'a> Clone for ControlMessage<'a>

fn clone(&self) -> ControlMessage<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for ControlMessage<'a>

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

Formats the value using the given formatter.

impl<'a> PartialEq for ControlMessage<'a>

fn eq(&self, other: &ControlMessage<'a>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a> Copy for ControlMessage<'a>

impl<'a> Eq for ControlMessage<'a>

impl<'a> StructuralPartialEq for ControlMessage<'a>