First version CNI plugin
This commit is contained in:
Scott Yeager
249
main.go
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249
main.go
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@@ -0,0 +1,249 @@
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package main
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import (
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"encoding/json"
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"fmt"
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"net"
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"os"
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"path/filepath"
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"github.com/containernetworking/cni/pkg/skel"
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"github.com/containernetworking/cni/pkg/types"
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current "github.com/containernetworking/cni/pkg/types/100"
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"github.com/containernetworking/cni/pkg/version"
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"github.com/vishvananda/netlink"
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"github.com/vishvananda/netns"
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)
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const (
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PluginName = "mycelium-cni"
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MyceliumInterface = "mycelium"
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)
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type NetConf struct {
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types.NetConf
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MyceliumInterface string `json:"myceliumInterface,omitempty"`
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}
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func main() {
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skel.PluginMain(cmdAdd, cmdCheck, cmdDel, version.All, "mycelium CNI plugin")
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}
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func cmdAdd(args *skel.CmdArgs) error {
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conf, err := parseConfig(args.StdinData)
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if err != nil {
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return err
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}
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// Get container network namespace
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containerNS, err := netns.GetFromPath(args.Netns)
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if err != nil {
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return fmt.Errorf("failed to open container netns %q: %v", args.Netns, err)
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}
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defer containerNS.Close()
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// Get Mycelium interface and its IPv6 prefix
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myceliumIP, err := getMyceliumIP(conf.MyceliumInterface)
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if err != nil {
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return fmt.Errorf("failed to get Mycelium IP: %v", err)
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}
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// Create veth pair
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hostVethName := fmt.Sprintf("veth-%s", args.ContainerID[:8])
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containerVethName := "eth0"
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hostVeth, containerVeth, err := createVethPair(hostVethName, containerVethName)
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if err != nil {
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return fmt.Errorf("failed to create veth pair: %v", err)
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}
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// Move container veth to container namespace
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if err := netlink.LinkSetNsFd(containerVeth, int(containerNS)); err != nil {
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return fmt.Errorf("failed to move veth to container netns: %v", err)
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}
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// Configure container interface
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containerIP := generateContainerIP(myceliumIP, args.ContainerID)
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if err := configureContainerInterface(containerNS, containerVethName, containerIP, hostVethName); err != nil {
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return fmt.Errorf("failed to configure container interface: %v", err)
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}
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// Configure host interface and routing
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if err := configureHostInterface(hostVeth, containerIP); err != nil {
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return fmt.Errorf("failed to configure host interface: %v", err)
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}
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// Build result
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result := ¤t.Result{
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CNIVersion: current.ImplementedSpecVersion,
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Interfaces: []*current.Interface{
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{
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Name: hostVethName,
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},
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{
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Name: containerVethName,
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Sandbox: args.Netns,
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},
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},
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IPs: []*current.IPConfig{
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{
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Interface: current.Int(1), // container interface
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Address: net.IPNet{IP: containerIP, Mask: net.CIDRMask(64, 128)},
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},
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},
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}
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return types.PrintResult(result, conf.CNIVersion)
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}
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func cmdCheck(args *skel.CmdArgs) error {
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// Basic connectivity check could be implemented here
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return nil
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}
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func cmdDel(args *skel.CmdArgs) error {
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// Clean up veth pair (host side will be automatically removed)
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hostVethName := fmt.Sprintf("veth-%s", args.ContainerID[:8])
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link, err := netlink.LinkByName(hostVethName)
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if err != nil {
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// Interface might already be gone, which is fine
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return nil
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}
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return netlink.LinkDel(link)
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}
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func parseConfig(stdin []byte) (*NetConf, error) {
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conf := &NetConf{
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MyceliumInterface: MyceliumInterface,
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}
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if err := json.Unmarshal(stdin, conf); err != nil {
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return nil, fmt.Errorf("failed to parse network configuration: %v", err)
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}
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return conf, nil
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}
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func getMyceliumIP(interfaceName string) (net.IP, error) {
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link, err := netlink.LinkByName(interfaceName)
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if err != nil {
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return nil, fmt.Errorf("failed to find interface %s: %v", interfaceName, err)
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}
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addrs, err := netlink.AddrList(link, netlink.FAMILY_V6)
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if err != nil {
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return nil, fmt.Errorf("failed to get addresses for %s: %v", interfaceName, err)
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}
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for _, addr := range addrs {
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if addr.IP.IsGlobalUnicast() {
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// Return the /64 prefix
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return addr.IP.Mask(net.CIDRMask(64, 128)), nil
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}
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}
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return nil, fmt.Errorf("no global IPv6 address found on %s", interfaceName)
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}
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func generateContainerIP(myceliumPrefix net.IP, containerID string) net.IP {
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// Generate a container IP within the /64 prefix
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// Using simple approach: prefix + ::1 (could be made more sophisticated)
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containerIP := make(net.IP, len(myceliumPrefix))
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copy(containerIP, myceliumPrefix)
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containerIP[15] = 1 // Set last byte to 1
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return containerIP
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}
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func createVethPair(hostName, containerName string) (netlink.Link, netlink.Link, error) {
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veth := &netlink.Veth{
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LinkAttrs: netlink.LinkAttrs{Name: hostName},
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PeerName: containerName,
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}
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if err := netlink.LinkAdd(veth); err != nil {
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return nil, nil, err
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}
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hostVeth, err := netlink.LinkByName(hostName)
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if err != nil {
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return nil, nil, err
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}
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containerVeth, err := netlink.LinkByName(containerName)
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if err != nil {
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return nil, nil, err
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}
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// Bring up host side
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if err := netlink.LinkSetUp(hostVeth); err != nil {
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return nil, nil, err
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}
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return hostVeth, containerVeth, nil
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}
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func configureContainerInterface(containerNS netns.NsHandle, ifName string, containerIP net.IP, hostVethName string) error {
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return netns.Set(containerNS, func(ns netns.NsHandle) error {
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// Get the interface
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link, err := netlink.LinkByName(ifName)
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if err != nil {
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return err
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}
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// Bring interface up
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if err := netlink.LinkSetUp(link); err != nil {
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return err
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}
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// Add IP address
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addr := &netlink.Addr{
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IPNet: &net.IPNet{
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IP: containerIP,
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Mask: net.CIDRMask(64, 128),
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},
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}
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if err := netlink.AddrAdd(link, addr); err != nil {
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return err
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}
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// Get host veth link-local address for routing
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hostVeth, err := netlink.LinkByName(hostVethName)
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if err == nil {
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hostAddrs, err := netlink.AddrList(hostVeth, netlink.FAMILY_V6)
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if err == nil {
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for _, addr := range hostAddrs {
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if addr.IP.IsLinkLocalUnicast() {
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// Add route to Mycelium network via host veth
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route := &netlink.Route{
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Dst: &net.IPNet{
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IP: net.ParseIP("400::"),
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Mask: net.CIDRMask(7, 128),
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},
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Gw: addr.IP,
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LinkIndex: link.Attrs().Index,
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}
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netlink.RouteAdd(route)
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break
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}
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}
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}
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}
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return nil
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})
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}
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func configureHostInterface(hostVeth netlink.Link, containerIP net.IP) error {
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// Add route to container IP via host veth
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route := &netlink.Route{
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Dst: &net.IPNet{
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IP: containerIP,
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Mask: net.CIDRMask(128, 128),
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},
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LinkIndex: hostVeth.Attrs().Index,
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}
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return netlink.RouteAdd(route)
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}
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