Function open_tap

net_util/src/open_tap.rs:110–147

Create a new virtio network device with the given IP address and netmask.

(
    if_name: Option<&str>,
    ip_addr: Option<IpAddr>,
    netmask: Option<IpAddr>,
    host_mac: &mut Option<MacAddr>,
    mtu: Option<u16>,
    num_rx_q: usize,
    flags: Option<i32>,
)

/// Create a new virtio network device with the given IP address and
/// netmask.
pub fn open_tap(
    if_name: Option<&str>,
    ip_addr: Option<IpAddr>,
    netmask: Option<IpAddr>,
    host_mac: &mut Option<MacAddr>,
    mtu: Option<u16>,
    num_rx_q: usize,
    flags: Option<i32>,
) -> Result<Vec<Tap>> {
    let mut taps: Vec<Tap> = Vec::new();
    let mut ifname: String = String::new();

    // In case the tap interface already exists, check if the number of
    // queues is appropriate. The tap might not support multiqueue while
    // the number of queues indicates the user expects multiple queues, or
    // on the contrary, the tap might support multiqueue while the number
    // of queues indicates the user doesn't expect multiple queues.
    check_mq_support(&if_name, num_rx_q)?;

    for i in 0..num_rx_q {
        let tap: Tap;
        if i == 0 {
            // Special handling is required for the first RX queue, such as
            // configuring the device. Subsequent iterations will then use the
            // same device.
            tap = open_tap_rx_q_0(if_name, ip_addr, netmask, host_mac, mtu, num_rx_q, flags)?;
            // Set the name of the tap device we open in subsequent iterations.
            ifname = tap.if_name_as_str().to_string();
        } else {
            tap = Tap::open_named(ifname.as_str(), num_rx_q, flags).map_err(Error::TapOpen)?;

            tap.set_vnet_hdr_size(vnet_hdr_len() as i32)
                .map_err(Error::TapSetVnetHdrSize)?;
        }
        taps.push(tap);
    }
    Ok(taps)
}