configure mac address based on assigned ip

diff --git a/pkg/ipam/ipam.go b/pkg/ipam/ipam.go
index d9fbff7..7777e6f 100644 (file)
--- a/pkg/ipam/ipam.go
+++ b/pkg/ipam/ipam.go
@@ -23,6 +23,17 @@ import (
        "github.com/containernetworking/cni/pkg/types"
 
        "github.com/vishvananda/netlink"
+       "net"
+       "strconv"
+       "strings"
+)
+
+const (
+       // private mac prefix safe to use
+       privateMACPrefix = "0a:58"
+
+       // veth link dev type
+       vethLinkType = "veth"
 )
 
 func ExecAdd(plugin string, netconf []byte) (*types.Result, error) {
@@ -45,6 +56,17 @@ func ConfigureIface(ifName string, res *types.Result) error {
                return fmt.Errorf("failed to set %q UP: %v", ifName, err)
        }
 
+       // only set hardware address to veth when using ipv4
+       if link.Type() == vethLinkType && res.IP4 != nil {
+               hwAddr, err := generateHardwareAddr(res.IP4.IP.IP)
+               if err != nil {
+                       return fmt.Errorf("failed to generate hardware addr: %v", err)
+               }
+               if err = netlink.LinkSetHardwareAddr(link, hwAddr); err != nil {
+                       return fmt.Errorf("failed to add hardware addr to %q: %v", ifName, err)
+               }
+       }
+
        // TODO(eyakubovich): IPv6
        addr := &netlink.Addr{IPNet: &res.IP4.IP, Label: ""}
        if err = netlink.AddrAdd(link, addr); err != nil {
@@ -66,3 +88,21 @@ func ConfigureIface(ifName string, res *types.Result) error {
 
        return nil
 }
+
+// generateHardwareAddr generates 48 bit virtual mac addresses based on the IP input.
+func generateHardwareAddr(ip net.IP) (net.HardwareAddr, error) {
+       if ip.To4() == nil {
+               return nil, fmt.Errorf("generateHardwareAddr only support valid ipv4 address as input")
+       }
+       mac := privateMACPrefix
+       sections := strings.Split(ip.String(), ".")
+       for _, s := range sections {
+               i, _ := strconv.Atoi(s)
+               mac = mac + ":" + fmt.Sprintf("%02x", i)
+       }
+       hwAddr, err := net.ParseMAC(mac)
+       if err != nil {
+               return nil, fmt.Errorf("Failed to parse mac address %s generated based on ip %s due to: %v", mac, ip, err)
+       }
+       return hwAddr, nil
+}