Struct AsyncDevice

pub struct AsyncDevice(/* private fields */);

Available on crate features async_io or async_tokio only.

An async Tun/Tap device wrapper around a Tun/Tap device.

This type does not provide a split method, because this functionality can be achieved by instead wrapping the socket in an Arc.

Streams

If you need to produce a Stream, you can look at DeviceFramed.

Note: DeviceFramed is only available when the async_framed feature is enabled.

Implementations

impl AsyncDevice

pub fn poll_readable(&self, cx: &mut Context<'_>) -> Poll<Result<()>>

Polls the I/O handle for readability.

Caveats

Note that on multiple calls to a poll_* method in the recv direction, only the Waker from the Context passed to the most recent call will be scheduled to receive a wakeup.

Return value

The function returns:

• Poll::Pending if the device is not ready for reading.
• Poll::Ready(Ok(())) if the device is ready for reading.
• Poll::Ready(Err(e)) if an error is encountered.

Errors

This function may encounter any standard I/O error except WouldBlock.

pub fn poll_recv( &self, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize>>

Attempts to receive a single packet from the device

Caveats

Note that on multiple calls to a poll_* method in the recv direction, only the Waker from the Context passed to the most recent call will be scheduled to receive a wakeup.

Return value

The function returns:

• Poll::Pending if the device is not ready to read
• Poll::Ready(Ok(())) reads data buf if the device is ready
• Poll::Ready(Err(e)) if an error is encountered.

Errors

This function may encounter any standard I/O error except WouldBlock.

pub fn poll_writable(&self, cx: &mut Context<'_>) -> Poll<Result<()>>

Polls the I/O handle for writability.

Caveats

Note that on multiple calls to a poll_* method in the send direction, only the Waker from the Context passed to the most recent call will be scheduled to receive a wakeup.

Return value

The function returns:

• Poll::Pending if the device is not ready for writing.
• Poll::Ready(Ok(())) if the device is ready for writing.
• Poll::Ready(Err(e)) if an error is encountered.

Errors

This function may encounter any standard I/O error except WouldBlock.

pub fn poll_send(&self, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize>>

Attempts to send packet to the device

Caveats

Note that on multiple calls to a poll_* method in the send direction, only the Waker from the Context passed to the most recent call will be scheduled to receive a wakeup.

Return value

The function returns:

• Poll::Pending if the device is not available to write
• Poll::Ready(Ok(n)) n is the number of bytes sent
• Poll::Ready(Err(e)) if an error is encountered.

Errors

This function may encounter any standard I/O error except WouldBlock.

impl AsyncDevice

pub fn new(device: SyncDevice) -> Result<AsyncDevice>

pub unsafe fn from_fd(fd: RawFd) -> Result<AsyncDevice>

Safety

This method is safe if the provided fd is valid Construct a AsyncDevice from an existing file descriptor

pub fn into_fd(self) -> Result<RawFd>

pub async fn readable(&self) -> Result<()>

Waits for the device to become readable.

This function is usually paired with try_recv().

The function may complete without the device being readable. This is a false-positive and attempting a try_recv() will return with io::ErrorKind::WouldBlock.

Cancel safety

This method is cancel safe. Once a readiness event occurs, the method will continue to return immediately until the readiness event is consumed by an attempt to read that fails with WouldBlock or Poll::Pending.

pub async fn writable(&self) -> Result<()>

Waits for the device to become writable.

This function is usually paired with try_send().

The function may complete without the device being writable. This is a false-positive and attempting a try_send() will return with io::ErrorKind::WouldBlock.

Cancel safety

This method is cancel safe. Once a readiness event occurs, the method will continue to return immediately until the readiness event is consumed by an attempt to write that fails with WouldBlock or Poll::Pending.

pub async fn recv(&self, buf: &mut [u8]) -> Result<usize>

Receives a single packet from the device. On success, returns the number of bytes read.

The function must be called with valid byte array buf of sufficient size to hold the message bytes. If a message is too long to fit in the supplied buffer, excess bytes may be discarded.

pub fn try_recv(&self, buf: &mut [u8]) -> Result<usize>

Tries to receive a single packet from the device. On success, returns the number of bytes read.

This method must be called with valid byte array buf of sufficient size to hold the message bytes. If a message is too long to fit in the supplied buffer, excess bytes may be discarded.

When there is no pending data, Err(io::ErrorKind::WouldBlock) is returned. This function is usually paired with readable().

pub async fn send(&self, buf: &[u8]) -> Result<usize>

Send a packet to the device

Return

On success, the number of bytes sent is returned, otherwise, the encountered error is returned.

pub fn try_send(&self, buf: &[u8]) -> Result<usize>

Tries to send packet to the device.

When the device buffer is full, Err(io::ErrorKind::WouldBlock) is returned. This function is usually paired with writable().

Returns

If successful, Ok(n) is returned, where n is the number of bytes sent. If the device is not ready to send data, Err(ErrorKind::WouldBlock) is returned.

pub async fn recv_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Receives a packet into multiple buffers (scatter read). Processes single packet per call.

pub fn try_recv_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Non-blocking version of recv_vectored.

pub async fn send_vectored(&self, bufs: &[IoSlice<'_>]) -> Result<usize>

Sends multiple buffers as a single packet (gather write).

pub fn try_send_vectored(&self, bufs: &[IoSlice<'_>]) -> Result<usize>

Non-blocking version of send_vectored.

impl AsyncDevice

pub fn try_clone(&self) -> Result<Self>

Prerequisites

• The IFF_MULTI_QUEUE flag must be enabled.
• The system must support network interface multi-queue functionality.

Description

When multi-queue is enabled, create a new queue by duplicating an existing one.

pub async fn recv_multiple<B: AsRef<[u8]> + AsMut<[u8]>>( &self, original_buffer: &mut [u8], bufs: &mut [B], sizes: &mut [usize], offset: usize, ) -> Result<usize>

Recv a packet from the device. If offload is enabled. This method can be used to obtain processed data.

original_buffer is used to store raw data, including the VirtioNetHdr and the unsplit IP packet. The recommended size is 10 + 65535. bufs and sizes are used to store the segmented IP packets. bufs.len == sizes.len > 65535/MTU offset: Starting position

pub async fn send_multiple<B: ExpandBuffer>( &self, gro_table: &mut GROTable, bufs: &mut [B], offset: usize, ) -> Result<usize>

send multiple fragmented data packets. GROTable can be reused, as it is used to assist in data merging. Offset is the starting position of the data. Need to meet offset>10.

Methods from Deref<Target = DeviceImpl>

pub fn if_index(&self) -> Result<u32>

Retrieves the interface index for the network interface.

This function converts the interface name (obtained via self.name()) into a C-compatible string (CString) and then calls the libc function if_nametoindex to retrieve the corresponding interface index.

pub fn addresses(&self) -> Result<Vec<IpAddr>>

Retrieves all IP addresses associated with the network interface.

This function calls getifaddrs with the interface name, then iterates over the returned list of interface addresses, extracting and collecting the IP addresses into a vector.

pub fn udp_gso(&self) -> bool

Returns whether UDP Generic Segmentation Offload (GSO) is enabled.

This is determined by the udp_gso flag in the device.

pub fn tcp_gso(&self) -> bool

Returns whether TCP Generic Segmentation Offload (GSO) is enabled.

In this implementation, this is represented by the vnet_hdr flag.

pub fn set_tx_queue_len(&self, tx_queue_len: u32) -> Result<()>

Sets the transmit queue length for the network interface.

This method constructs an interface request (ifreq) structure, assigns the desired transmit queue length to the ifru_metric field, and calls the change_tx_queue_len function using the control file descriptor. If the underlying operation fails, an I/O error is returned.

pub fn tx_queue_len(&self) -> Result<u32>

Retrieves the current transmit queue length for the network interface.

This function constructs an interface request structure and calls tx_queue_len to populate it with the current transmit queue length. The value is then returned.

pub fn persist(&self) -> Result<()>

Make the device persistent.

pub fn user(&self, value: i32) -> Result<()>

Set the owner of the device.

pub fn group(&self, value: i32) -> Result<()>

Set the group of the device.

pub fn send_multiple<B: ExpandBuffer>( &self, gro_table: &mut GROTable, bufs: &mut [B], offset: usize, ) -> Result<usize>

send multiple fragmented data packets. GROTable can be reused, as it is used to assist in data merging. Offset is the starting position of the data. Need to meet offset>=10.

pub fn recv_multiple<B: AsRef<[u8]> + AsMut<[u8]>>( &self, original_buffer: &mut [u8], bufs: &mut [B], sizes: &mut [usize], offset: usize, ) -> Result<usize>

Recv a packet from tun device. If offload is enabled. This method can be used to obtain processed data.

original_buffer is used to store raw data, including the VirtioNetHdr and the unsplit IP packet. The recommended size is 10 + 65535. bufs and sizes are used to store the segmented IP packets. bufs.len == sizes.len > 65535/MTU offset: Starting position

pub fn remove_address_v6(&self, addr: Ipv6Addr, prefix: u8) -> Result<()>

pub fn name(&self) -> Result<String>

Retrieves the name of the network interface.

pub fn set_name(&self, value: &str) -> Result<()>

Sets a new name for the network interface.

This function converts the provided name into a C-compatible string, checks that its length does not exceed the maximum allowed (IFNAMSIZ), and then copies it into an interface request structure. It then uses a system call (via siocsifname) to apply the new name.

pub fn is_running(&self) -> Result<bool>

Checks whether the network interface is currently running.

The interface is considered running if both the IFF_UP and IFF_RUNNING flags are set.

pub fn enabled(&self, value: bool) -> Result<()>

Enables or disables the network interface.

If value is true, the interface is enabled by setting the IFF_UP and IFF_RUNNING flags. If false, the IFF_UP flag is cleared. The change is applied using a system call.

pub fn broadcast(&self) -> Result<IpAddr>

Retrieves the broadcast address of the network interface.

This function populates an interface request with the broadcast address via a system call, converts it into a sockaddr structure, and then extracts the IP address.

pub fn set_broadcast(&self, value: IpAddr) -> Result<()>

Sets the broadcast address of the network interface.

This function converts the given IP address into a sockaddr structure (with a specified overwrite size) and then applies it to the interface via a system call.

pub fn set_network_address<IPv4: ToIpv4Address, Netmask: ToIpv4Netmask>( &self, address: IPv4, netmask: Netmask, destination: Option<IPv4>, ) -> Result<()>

Sets the IPv4 network address, netmask, and an optional destination address.

This function sets the interface’s address, netmask, and if provided, the destination address. It calls the helper methods set_address_v4, set_netmask, and set_destination respectively.

pub fn remove_address(&self, addr: IpAddr) -> Result<()>

Removes an IP address from the interface.

For IPv4 addresses, it iterates over the current addresses and if a match is found, resets the address to 0.0.0.0 (unspecified). For IPv6 addresses, it retrieves the interface addresses by name and removes the matching address, taking into account its prefix length.

pub fn add_address_v6<IPv6: ToIpv6Address, Netmask: ToIpv6Netmask>( &self, addr: IPv6, netmask: Netmask, ) -> Result<()>

Adds an IPv6 address to the interface.

This function creates an in6_ifreq structure, fills in the interface index, prefix length, and IPv6 address (converted into a sockaddr structure), and then applies it using a system call.

pub fn mtu(&self) -> Result<u16>

Retrieves the current MTU (Maximum Transmission Unit) for the interface.

This function constructs an interface request and uses a system call (via siocgifmtu) to obtain the MTU. The result is then converted to a u16.

pub fn set_mtu(&self, value: u16) -> Result<()>

Sets the MTU (Maximum Transmission Unit) for the interface.

This function creates an interface request, sets the ifru_mtu field to the new value, and then applies it via a system call.

pub fn set_mac_address(&self, eth_addr: [u8; 6]) -> Result<()>

Sets the MAC (hardware) address for the interface.

This function constructs an interface request and copies the provided MAC address into the hardware address field. It then applies the change via a system call. This operation is typically supported only for TAP devices.

pub fn mac_address(&self) -> Result<[u8; 6]>

Retrieves the MAC (hardware) address of the interface.

This function queries the MAC address by the interface name using a helper function. An error is returned if the MAC address cannot be found.

Trait Implementations

impl AsRawFd for AsyncDevice

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.

impl Deref for AsyncDevice

type Target = DeviceImpl

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl FromRawFd for AsyncDevice

unsafe fn from_raw_fd(fd: RawFd) -> Self

Constructs a new instance of Self from the given raw file descriptor.

impl IntoRawFd for AsyncDevice

fn into_raw_fd(self) -> RawFd

Consumes this object, returning the raw underlying file descriptor.