pub struct SockRef<'s> { /* private fields */ }
Expand description

A reference to a Socket that can be used to configure socket types other than the Socket type itself.

This allows for example a TcpStream, found in the standard library, to be configured using all the additional methods found in the Socket API.

SockRef can be created from any socket type that implements AsRawFd (Unix) or AsRawSocket (Windows) using the From implementation, but the caller must ensure the file descriptor/socket is a valid.

Examples

Below is an example of converting a TcpStream into a SockRef.

use std::net::{TcpStream, SocketAddr};

use socket2::SockRef;

// Create `TcpStream` from the standard library.
let address: SocketAddr = "127.0.0.1:1234".parse()?;
let stream = TcpStream::connect(address)?;

// Create a `SockRef`erence to the stream.
let socket_ref = SockRef::from(&stream);
// Use `Socket::set_nodelay` on the stream.
socket_ref.set_nodelay(true)?;
drop(socket_ref);

assert_eq!(stream.nodelay()?, true);

Below is an example of incorrect usage of SockRef::from, which is currently possible (but not intended and will be fixed in future versions).

use socket2::SockRef;

/// THIS USAGE IS NOT VALID!
let socket_ref = SockRef::from(&123);
// The above line is overseen possibility when using `SockRef::from`, it
// uses the `RawFd` (on Unix), which is a type alias for `c_int`/`i32`,
// which implements `AsRawFd`. However it may be clear that this usage is
// invalid as it doesn't guarantee that `123` is a valid file descriptor.

// Using `Socket::set_nodelay` now will call it on a file descriptor we
// don't own! We don't even not if the file descriptor is valid or a socket.
socket_ref.set_nodelay(true)?;
drop(socket_ref);

Methods from Deref<Target = Socket>

Binds this socket to the specified address.

This function directly corresponds to the bind(2) function on Windows and Unix.

Initiate a connection on this socket to the specified address.

This function directly corresponds to the connect(2) function on Windows and Unix.

An error will be returned if listen or connect has already been called on this builder.

Notes

When using a non-blocking connect (by setting the socket into non-blocking mode before calling this function), socket option can’t be set while connecting. This will cause errors on Windows. Socket options can be safely set before and after connecting the socket.

Initiate a connection on this socket to the specified address, only only waiting for a certain period of time for the connection to be established.

Unlike many other methods on Socket, this does not correspond to a single C function. It sets the socket to nonblocking mode, connects via connect(2), and then waits for the connection to complete with poll(2) on Unix and select on Windows. When the connection is complete, the socket is set back to blocking mode. On Unix, this will loop over EINTR errors.

Warnings

The non-blocking state of the socket is overridden by this function - it will be returned in blocking mode on success, and in an indeterminate state on failure.

If the connection request times out, it may still be processing in the background - a second call to connect or connect_timeout may fail.

Mark a socket as ready to accept incoming connection requests using Socket::accept().

This function directly corresponds to the listen(2) function on Windows and Unix.

An error will be returned if listen or connect has already been called on this builder.

Accept a new incoming connection from this listener.

This function uses accept4(2) on platforms that support it and accept(2) platforms that do not.

This function sets the same flags as in done for Socket::new, Socket::accept_raw can be used if you don’t want to set those flags.

Accept a new incoming connection from this listener.

This function directly corresponds to the accept(2) function on Windows and Unix.

Returns the socket address of the local half of this socket.

Notes

Depending on the OS this may return an error if the socket is not bound.

Returns the socket address of the remote peer of this socket.

Notes

This returns an error if the socket is not connected.

Returns the Type of this socket by checking the SO_TYPE option on this socket.

Creates a new independently owned handle to the underlying socket.

Notes

On Unix this uses F_DUPFD_CLOEXEC and thus sets the FD_CLOEXEC on the returned socket.

On Windows this uses WSA_FLAG_NO_HANDLE_INHERIT setting inheriting to false.

On Windows this can not be used function cannot be used on a QOS-enabled socket, see https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-wsaduplicatesocketw.

Moves this TCP stream into or out of nonblocking mode.

Notes

On Unix this corresponds to calling fcntl (un)setting O_NONBLOCK.

On Windows this corresponds to calling ioctlsocket (un)setting FIONBIO.

Shuts down the read, write, or both halves of this connection.

This function will cause all pending and future I/O on the specified portions to return immediately with an appropriate value.

Receives data on the socket from the remote address to which it is connected.

The connect method will connect this socket to a remote address. This method might fail if the socket is not connected.

Safety

Normally casting a &mut [u8] to &mut [MaybeUninit<u8>] would be unsound, as that allows us to write uninitialised bytes to the buffer. However this implementation promises to not write uninitialised bytes to the buffer and passes it directly to recv(2) system call. This promise ensures that this function can be called using a buffer of type &mut [u8].

Note that the io::Read::read implementation calls this function with a buffer of type &mut [u8], allowing initialised buffers to be used without using unsafe.

Receives out-of-band (OOB) data on the socket from the remote address to which it is connected by setting the MSG_OOB flag for this call.

For more information, see recv, out_of_band_inline.

Identical to recv but allows for specification of arbitrary flags to the underlying recv call.

Receives data on the socket from the remote address to which it is connected. Unlike recv this allows passing multiple buffers.

The connect method will connect this socket to a remote address. This method might fail if the socket is not connected.

In addition to the number of bytes read, this function returns the flags for the received message. See RecvFlags for more information about the returned flags.

Safety

Normally casting a IoSliceMut to MaybeUninitSlice would be unsound, as that allows us to write uninitialised bytes to the buffer. However this implementation promises to not write uninitialised bytes to the bufs and passes it directly to recvmsg(2) system call. This promise ensures that this function can be called using bufs of type &mut [IoSliceMut].

Note that the io::Read::read_vectored implementation calls this function with bufs of type &mut [IoSliceMut], allowing initialised buffers to be used without using unsafe.

Identical to recv_vectored but allows for specification of arbitrary flags to the underlying recvmsg/WSARecv call.

Safety

recv_from_vectored makes the same safety guarantees regarding bufs as recv_vectored.

Receives data on the socket from the remote adress to which it is connected, without removing that data from the queue. On success, returns the number of bytes peeked.

Successive calls return the same data. This is accomplished by passing MSG_PEEK as a flag to the underlying recv system call.

Safety

peek makes the same safety guarantees regarding the buffer as recv.

Receives data from the socket. On success, returns the number of bytes read and the address from whence the data came.

Safety

recv_from makes the same safety guarantees regarding the buffer as recv.

Identical to recv_from but allows for specification of arbitrary flags to the underlying recvfrom call.

Receives data from the socket. Returns the amount of bytes read, the RecvFlags and the remote address from the data is coming. Unlike recv_from this allows passing multiple buffers.

Safety

recv_from_vectored makes the same safety guarantees regarding bufs as recv_vectored.

Identical to recv_from_vectored but allows for specification of arbitrary flags to the underlying recvmsg/WSARecvFrom call.

Safety

recv_from_vectored makes the same safety guarantees regarding bufs as recv_vectored.

Receives data from the socket, without removing it from the queue.

Successive calls return the same data. This is accomplished by passing MSG_PEEK as a flag to the underlying recvfrom system call.

On success, returns the number of bytes peeked and the address from whence the data came.

Safety

peek_from makes the same safety guarantees regarding the buffer as recv.

Sends data on the socket to a connected peer.

This is typically used on TCP sockets or datagram sockets which have been connected.

On success returns the number of bytes that were sent.

Identical to send but allows for specification of arbitrary flags to the underlying send call.

Send data to the connected peer. Returns the amount of bytes written.

Identical to send_vectored but allows for specification of arbitrary flags to the underlying sendmsg/WSASend call.

Sends out-of-band (OOB) data on the socket to connected peer by setting the MSG_OOB flag for this call.

For more information, see send, out_of_band_inline.

Sends data on the socket to the given address. On success, returns the number of bytes written.

This is typically used on UDP or datagram-oriented sockets.

Identical to send_to but allows for specification of arbitrary flags to the underlying sendto call.

Send data to a peer listening on addr. Returns the amount of bytes written.

Identical to send_to_vectored but allows for specification of arbitrary flags to the underlying sendmsg/WSASendTo call.

Get the value of the SO_BROADCAST option for this socket.

For more information about this option, see set_broadcast.

Set the value of the SO_BROADCAST option for this socket.

When enabled, this socket is allowed to send packets to a broadcast address.

Get the value of the SO_ERROR option on this socket.

This will retrieve the stored error in the underlying socket, clearing the field in the process. This can be useful for checking errors between calls.

Get the value of the SO_KEEPALIVE option on this socket.

For more information about this option, see set_keepalive.

Set value for the SO_KEEPALIVE option on this socket.

Enable sending of keep-alive messages on connection-oriented sockets.

Get the value of the SO_LINGER option on this socket.

For more information about this option, see set_linger.

Set value for the SO_LINGER option on this socket.

If linger is not None, a close(2) or shutdown(2) will not return until all queued messages for the socket have been successfully sent or the linger timeout has been reached. Otherwise, the call returns immediately and the closing is done in the background. When the socket is closed as part of exit(2), it always lingers in the background.

Notes

On most OSs the duration only has a precision of seconds and will be silently truncated.

On Apple platforms (e.g. macOS, iOS, etc) this uses SO_LINGER_SEC.

Get value for the SO_OOBINLINE option on this socket.

For more information about this option, see set_out_of_band_inline.

Set value for the SO_OOBINLINE option on this socket.

If this option is enabled, out-of-band data is directly placed into the receive data stream. Otherwise, out-of-band data is passed only when the MSG_OOB flag is set during receiving. As per RFC6093, TCP sockets using the Urgent mechanism are encouraged to set this flag.

Get value for the SO_RCVBUF option on this socket.

For more information about this option, see set_recv_buffer_size.

Set value for the SO_RCVBUF option on this socket.

Changes the size of the operating system’s receive buffer associated with the socket.

Get value for the SO_RCVTIMEO option on this socket.

If the returned timeout is None, then read and recv calls will block indefinitely.

Set value for the SO_RCVTIMEO option on this socket.

If timeout is None, then read and recv calls will block indefinitely.

Get the value of the SO_REUSEADDR option on this socket.

For more information about this option, see set_reuse_address.

Set value for the SO_REUSEADDR option on this socket.

This indicates that futher calls to bind may allow reuse of local addresses. For IPv4 sockets this means that a socket may bind even when there’s a socket already listening on this port.

Get the value of the SO_SNDBUF option on this socket.

For more information about this option, see set_send_buffer_size.

Set value for the SO_SNDBUF option on this socket.

Changes the size of the operating system’s send buffer associated with the socket.

Get value for the SO_SNDTIMEO option on this socket.

If the returned timeout is None, then write and send calls will block indefinitely.

Set value for the SO_SNDTIMEO option on this socket.

If timeout is None, then write and send calls will block indefinitely.

Get the value of the IP_TRANSPARENT option on this socket.

For more information about this option, see set_ip_transparent.

Set the value of the IP_TRANSPARENT option on this socket.

Setting this boolean option enables transparent proxying on this socket. This socket option allows the calling application to bind to a nonlocal IP address and operate both as a client and a server with the foreign address as the local endpoint. NOTE: this requires that routing be set up in a way that packets going to the foreign address are routed through the TProxy box (i.e., the system hosting the application that employs the IP_TRANSPARENT socket option). Enabling this socket option requires superuser privileges (the CAP_NET_ADMIN capability).

TProxy redirection with the iptables TPROXY target also requires that this option be set on the redirected socket.

Join a multicast group using IP_ADD_MEMBERSHIP option on this socket.

This function specifies a new multicast group for this socket to join. The address must be a valid multicast address, and interface is the address of the local interface with which the system should join the multicast group. If it’s Ipv4Addr::UNSPECIFIED (INADDR_ANY) then an appropriate interface is chosen by the system.

Leave a multicast group using IP_DROP_MEMBERSHIP option on this socket.

For more information about this option, see join_multicast_v4.

Get the value of the IP_MULTICAST_IF option for this socket.

For more information about this option, see set_multicast_if_v4.

Set the value of the IP_MULTICAST_IF option for this socket.

Specifies the interface to use for routing multicast packets.

Get the value of the IP_MULTICAST_LOOP option for this socket.

For more information about this option, see set_multicast_loop_v4.

Set the value of the IP_MULTICAST_LOOP option for this socket.

If enabled, multicast packets will be looped back to the local socket. Note that this may not have any affect on IPv6 sockets.

Get the value of the IP_MULTICAST_TTL option for this socket.

For more information about this option, see set_multicast_ttl_v4.

Set the value of the IP_MULTICAST_TTL option for this socket.

Indicates the time-to-live value of outgoing multicast packets for this socket. The default value is 1 which means that multicast packets don’t leave the local network unless explicitly requested.

Note that this may not have any affect on IPv6 sockets.

Get the value of the IP_TTL option for this socket.

For more information about this option, see set_ttl.

Set the value of the IP_TTL option for this socket.

This value sets the time-to-live field that is used in every packet sent from this socket.

Set the value of the IP_TOS option for this socket.

This value sets the type-of-service field that is used in every packet sent from this socket.

NOTE: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options documents that not all versions of windows support IP_TOS.

Get the value of the IP_TOS option for this socket.

For more information about this option, see [set_tos].

NOTE: https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options documents that not all versions of windows support IP_TOS. [set_tos]: Socket::set_tos

Join a multicast group using IPV6_ADD_MEMBERSHIP option on this socket.

Some OSs use IPV6_JOIN_GROUP for this option.

This function specifies a new multicast group for this socket to join. The address must be a valid multicast address, and interface is the index of the interface to join/leave (or 0 to indicate any interface).

Leave a multicast group using IPV6_DROP_MEMBERSHIP option on this socket.

Some OSs use IPV6_LEAVE_GROUP for this option.

For more information about this option, see join_multicast_v6.

Get the value of the IPV6_MULTICAST_HOPS option for this socket

For more information about this option, see set_multicast_hops_v6.

Set the value of the IPV6_MULTICAST_HOPS option for this socket

Indicates the number of “routers” multicast packets will transit for this socket. The default value is 1 which means that multicast packets don’t leave the local network unless explicitly requested.

Get the value of the IPV6_MULTICAST_IF option for this socket.

For more information about this option, see set_multicast_if_v6.

Set the value of the IPV6_MULTICAST_IF option for this socket.

Specifies the interface to use for routing multicast packets. Unlike ipv4, this is generally required in ipv6 contexts where network routing prefixes may overlap.

Get the value of the IPV6_MULTICAST_LOOP option for this socket.

For more information about this option, see set_multicast_loop_v6.

Set the value of the IPV6_MULTICAST_LOOP option for this socket.

Controls whether this socket sees the multicast packets it sends itself. Note that this may not have any affect on IPv4 sockets.

Get the value of the IPV6_UNICAST_HOPS option for this socket.

Specifies the hop limit for ipv6 unicast packets

Set the value for the IPV6_UNICAST_HOPS option on this socket.

Specifies the hop limit for ipv6 unicast packets

Get the value of the IPV6_V6ONLY option for this socket.

For more information about this option, see set_only_v6.

Set the value for the IPV6_V6ONLY option on this socket.

If this is set to true then the socket is restricted to sending and receiving IPv6 packets only. In this case two IPv4 and IPv6 applications can bind the same port at the same time.

If this is set to false then the socket can be used to send and receive packets from an IPv4-mapped IPv6 address.

Get the value of the TCP_KEEPIDLE option on this socket.

This returns the value of SO_KEEPALIVE on OpenBSD and Haiku, TCP_KEEPALIVE on macOS and iOS, and TCP_KEEPIDLE on all other Unix operating systems.

Get the value of the TCP_KEEPINTVL option on this socket.

For more information about this option, see set_tcp_keepalive.

Get the value of the TCP_KEEPCNT option on this socket.

For more information about this option, see set_tcp_keepalive.

Set parameters configuring TCP keepalive probes for this socket.

The supported parameters depend on the operating system, and are configured using the TcpKeepalive struct. At a minimum, all systems support configuring the keepalive time: the time after which the OS will start sending keepalive messages on an idle connection.

Notes
  • This will enable SO_KEEPALIVE on this socket, if it is not already enabled.
  • On some platforms, such as Windows, any keepalive parameters not configured by the TcpKeepalive struct passed to this function may be overwritten with their default values. Therefore, this function should either only be called once per socket, or the same parameters should be passed every time it is called.
Examples
use std::time::Duration;

use socket2::{Socket, TcpKeepalive, Domain, Type};

let socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
let keepalive = TcpKeepalive::new()
    .with_time(Duration::from_secs(4));
    // Depending on the target operating system, we may also be able to
    // configure the keepalive probe interval and/or the number of
    // retries here as well.

socket.set_tcp_keepalive(&keepalive)?;

Get the value of the TCP_NODELAY option on this socket.

For more information about this option, see set_nodelay.

Set the value of the TCP_NODELAY option on this socket.

If set, this option disables the Nagle algorithm. This means that segments are always sent as soon as possible, even if there is only a small amount of data. When not set, data is buffered until there is a sufficient amount to send out, thereby avoiding the frequent sending of small packets.

Accept a new incoming connection from this listener.

This function directly corresponds to the accept4(2) function.

This function will block the calling thread until a new connection is established. When established, the corresponding Socket and the remote peer’s address will be returned.

Sets CLOEXEC on the socket.

Notes

On supported platforms you can use Type::cloexec.

Sets SO_NOSIGPIPE on the socket.

Gets the value of the TCP_MAXSEG option on this socket.

For more information about this option, see set_mss.

Sets the value of the TCP_MAXSEG option on this socket.

The TCP_MAXSEG option denotes the TCP Maximum Segment Size and is only available on TCP sockets.

Returns true if listen(2) was called on this socket by checking the SO_ACCEPTCONN option on this socket.

Returns the Domain of this socket by checking the SO_DOMAIN option on this socket.

Returns the Protocol of this socket by checking the SO_PROTOCOL option on this socket.

Gets the value for the SO_MARK option on this socket.

This value gets the socket mark field for each packet sent through this socket.

On Linux this function requires the CAP_NET_ADMIN capability.

Sets the value for the SO_MARK option on this socket.

This value sets the socket mark field for each packet sent through this socket. Changing the mark can be used for mark-based routing without netfilter or for packet filtering.

On Linux this function requires the CAP_NET_ADMIN capability.

Gets the value for the SO_BINDTODEVICE option on this socket.

This value gets the socket binded device’s interface name.

Sets the value for the SO_BINDTODEVICE option on this socket.

If a socket is bound to an interface, only packets received from that particular interface are processed by the socket. Note that this only works for some socket types, particularly AF_INET sockets.

If interface is None or an empty string it removes the binding.

Get the value of the SO_INCOMING_CPU option on this socket.

For more information about this option, see set_cpu_affinity.

Set value for the SO_INCOMING_CPU option on this socket.

Sets the CPU affinity of the socket.

Get the value of the SO_REUSEPORT option on this socket.

For more information about this option, see set_reuse_port.

Set value for the SO_REUSEPORT option on this socket.

This indicates that further calls to bind may allow reuse of local addresses. For IPv4 sockets this means that a socket may bind even when there’s a socket already listening on this port.

Get the value of the IP_FREEBIND option on this socket.

For more information about this option, see set_freebind.

Set value for the IP_FREEBIND option on this socket.

If enabled, this boolean option allows binding to an IP address that is nonlocal or does not (yet) exist. This permits listening on a socket, without requiring the underlying network interface or the specified dynamic IP address to be up at the time that the application is trying to bind to it.

Copies data between a file and this socket using the sendfile(2) system call. Because this copying is done within the kernel, sendfile() is more efficient than the combination of read(2) and write(2), which would require transferring data to and from user space.

Different OSs support different kinds of files, see the OS documentation for what kind of files are supported. Generally regular files are supported by all OSs.

The offset is the absolute offset into the file to use as starting point.

Depending on the OS this function may change the offset of file. For the best results reset the offset of the file before using it again.

The length determines how many bytes to send, where a length of None means it will try to send all bytes.

Set the value of the TCP_USER_TIMEOUT option on this socket.

If set, this specifies the maximum amount of time that transmitted data may remain unacknowledged or buffered data may remain untransmitted before TCP will forcibly close the corresponding connection.

Setting timeout to None or a zero duration causes the system default timeouts to be used. If timeout in milliseconds is larger than c_uint::MAX, the timeout is clamped to c_uint::MAX. For example, when c_uint is a 32-bit value, this limits the timeout to approximately 49.71 days.

Get the value of the TCP_USER_TIMEOUT option on this socket.

For more information about this option, see set_tcp_user_timeout.

Trait Implementations

Formats the value using the given formatter. Read more

The resulting type after dereferencing.

Dereferences the value.

On Windows, a corresponding From<&impl AsRawSocket> implementation exists.

The caller must ensure S is actually a socket.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.