func setupVeth(
	netns ns.NetNS,
	br *netlink.Bridge,
	ifName string,
	mtu int,
	hairpinMode bool,
	vlanID int,
	vlans []int,
	preserveDefaultVlan bool,
	mac string,
	portIsolation bool,
) (*current.Interface, *current.Interface, error) {
	contIface := &current.Interface{}
	hostIface := &current.Interface{}

	err := netns.Do(func(hostNS ns.NetNS) error {
		// create the veth pair in the container and move host end into host netns
		hostVeth, containerVeth, err := ip.SetupVeth(ifName, mtu, mac, hostNS)
		if err != nil {
			return err
		}
		contIface.Name = containerVeth.Name
		contIface.Mac = containerVeth.HardwareAddr.String()
		contIface.Sandbox = netns.Path()
		hostIface.Name = hostVeth.Name
		return nil
	})
	if err != nil {
		return nil, nil, err
	}

	// need to lookup hostVeth again as its index has changed during ns move
	hostVeth, err := netlinksafe.LinkByName(hostIface.Name)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to lookup %q: %v", hostIface.Name, err)
	}
	hostIface.Mac = hostVeth.Attrs().HardwareAddr.String()

	// connect host veth end to the bridge
	if err := netlink.LinkSetMaster(hostVeth, br); err != nil {
		return nil, nil, fmt.Errorf("failed to connect %q to bridge %v: %v", hostVeth.Attrs().Name, br.Attrs().Name, err)
	}

Warm-up