plugins: set MAC addresses based on IP

This will give deterministic MAC addresses for all interfaces CNI
creates and manages the IP for:
* bridge: container veth and host bridge
* macvlan: container veth
* ptp: container veth and host veth

ip/link.go

@@ -21,6 +21,7 @@ import (
 	"os"
 
 	"github.com/containernetworking/cni/pkg/ns"
+	"github.com/containernetworking/cni/pkg/utils/hwaddr"
 	"github.com/vishvananda/netlink"
 )
 
@@ -151,3 +152,19 @@ func DelLinkByNameAddr(ifName string, family int) (*net.IPNet, error) {
 
 	return addrs[0].IPNet, nil
 }
+
+func SetHWAddrByIP(link netlink.Link, ip4 net.IP, ip6 net.IP) error {
+	if ip4 != nil {
+		hwAddr, err := hwaddr.GenerateHardwareAddr4(ip4, hwaddr.PrivateMACPrefix)
+		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", link.Attrs().Name, err)
+		}
+	}
+
+	// TODO: IPv6
+
+	return nil
+}