func()

in plugins/vpc-branch-eni/plugin/commands.go [321:437]
89 lines of code
14 McCabe index (conditional complexity)

func (plugin *Plugin) createTAPLink(
	branch *eni.Branch,
	bridgeName string,
	tapLinkName string,
	tapCfg *config.TAPConfig) error {

	// Create the bridge link.
	la := netlink.NewLinkAttrs()
	la.Name = bridgeName
	la.MTU = vpc.JumboFrameMTU
	bridge := &netlink.Bridge{LinkAttrs: la}
	log.Infof("Creating bridge link %+v.", bridge)
	err := netlink.LinkAdd(bridge)
	if err != nil {
		log.Errorf("Failed to create bridge link: %v", err)
		return err
	}

	// Set bridge link MTU.
	err = netlink.LinkSetMTU(bridge, vpc.JumboFrameMTU)
	if err != nil {
		log.Errorf("Failed to set bridge link MTU: %v", err)
		return err
	}

	// In TAP mode, the branch ENI's MAC address is used exclusively by the consumer of the TAP
	// interface (e.g. a VM), so it shouldn't be assigned to the branch link itself. However, this
	// can happen if the branch link is being reused between successive invocations of the plugin.
	// Overriding the branch link's MAC address with that of the bridge prevents that.
	bridgeLink, err := netlink.LinkByIndex(bridge.Index)
	if err != nil {
		log.Errorf("Failed to find bridge link: %v", err)
		return err
	}

	err = branch.SetMACAddress(bridgeLink.Attrs().HardwareAddr)
	if err != nil {
		log.Errorf("Failed to set branch link MAC address: %v.", err)
		return err
	}

	// Set bridge link operational state up.
	err = netlink.LinkSetUp(bridge)
	if err != nil {
		log.Errorf("Failed to set bridge link state: %v", err)
		return err
	}

	// Connect branch link to the bridge.
	la = netlink.NewLinkAttrs()
	la.Name = branch.GetLinkName()
	branchLink := &netlink.Dummy{LinkAttrs: la}
	err = netlink.LinkSetMaster(branchLink, bridge)
	if err != nil {
		log.Errorf("Failed to set branch link master: %v", err)
		return err
	}

	// Create the TAP link.
	// Parse headers added by virtio_net implementation.
	la = netlink.NewLinkAttrs()
	la.Name = tapLinkName
	la.MasterIndex = bridge.Index
	la.MTU = vpc.JumboFrameMTU
	tapLink := &netlink.Tuntap{
		LinkAttrs: la,
		Mode:      netlink.TUNTAP_MODE_TAP,
		Flags:     netlink.TUNTAP_VNET_HDR,
		Queues:    tapCfg.Queues,
	}

	if tapCfg.Queues == 1 {
		tapLink.Flags |= netlink.TUNTAP_ONE_QUEUE
	}

	log.Infof("Creating TAP link %+v.", tapLink)
	err = netlink.LinkAdd(tapLink)
	if err != nil {
		log.Errorf("Failed to add TAP link: %v", err)
		return err
	}

	// Set TAP link MTU.
	err = netlink.LinkSetMTU(tapLink, vpc.JumboFrameMTU)
	if err != nil {
		log.Errorf("Failed to set TAP link MTU: %v", err)
		return err
	}

	// Set TAP link ownership.
	log.Infof("Setting TAP link owner to UID %d and GID %d.", tapCfg.Uid, tapCfg.Gid)
	for _, tapFd := range tapLink.Fds {
		fd := int(tapFd.Fd())

		err = unix.IoctlSetInt(fd, unix.TUNSETOWNER, tapCfg.Uid)
		if err != nil {
			log.Errorf("Failed to set TAP link UID: %v", err)
			return err
		}
		err = unix.IoctlSetInt(fd, unix.TUNSETGROUP, tapCfg.Gid)
		if err != nil {
			log.Errorf("Failed to set TAP link GID: %v", err)
			return err
		}

		tapFd.Close()
	}

	// Set TAP link operational state up.
	err = netlink.LinkSetUp(tapLink)
	if err != nil {
		log.Errorf("Failed to set TAP link state: %v", err)
		return err
	}

	return nil
}