Introduce iplink(MTU MAC and promiscas) feature into tuning

This change adds 'ip link' command related feature into tuning
meta cni plugin. Currently MTU, MAC and promiscas mode are
supported.

plugins/meta/tuning/tuning.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"path/filepath"
 	"strings"
 
@@ -29,6 +30,7 @@ import (
 	"github.com/containernetworking/cni/pkg/types/current"
 	"github.com/containernetworking/cni/pkg/version"
 	"github.com/containernetworking/plugins/pkg/ns"
+	"github.com/vishvananda/netlink"
 )
 
 // TuningConf represents the network tuning configuration.
@@ -37,14 +39,35 @@ type TuningConf struct {
 	SysCtl        map[string]string      `json:"sysctl"`
 	RawPrevResult map[string]interface{} `json:"prevResult,omitempty"`
 	PrevResult    *current.Result        `json:"-"`
+	Mac           string                 `json:"mac,omitempty"`
+	Promisc       bool                   `json:"promisc,omitempty"`
+	Mtu           int                    `json:"mtu,omitempty"`
 }
 
-func parseConf(data []byte) (*TuningConf, error) {
-	conf := TuningConf{}
+type MACEnvArgs struct {
+	types.CommonArgs
+	MAC types.UnmarshallableString `json:"mac,omitempty"`
+}
+
+func parseConf(data []byte, envArgs string) (*TuningConf, error) {
+	conf := TuningConf{Promisc: false, Mtu: -1}
 	if err := json.Unmarshal(data, &conf); err != nil {
 		return nil, fmt.Errorf("failed to load netconf: %v", err)
 	}
 
+	// Parse custom MAC from both env args
+	if envArgs != "" {
+		e := MACEnvArgs{}
+		err := types.LoadArgs(envArgs, &e)
+		if err != nil {
+			return nil, err
+		}
+
+		if e.MAC != "" {
+			conf.Mac = string(e.MAC)
+		}
+	}
+
 	// Parse previous result.
 	if conf.RawPrevResult != nil {
 		resultBytes, err := json.Marshal(conf.RawPrevResult)
@@ -65,8 +88,59 @@ func parseConf(data []byte) (*TuningConf, error) {
 	return &conf, nil
 }
 
+func changeMacAddr(ifName string, newMacAddr string) error {
+	addr, err := net.ParseMAC(newMacAddr)
+	if err != nil {
+		return fmt.Errorf("invalid args %v for MAC addr: %v", newMacAddr, err)
+	}
+
+	link, err := netlink.LinkByName(ifName)
+	if err != nil {
+		return fmt.Errorf("failed to get %q: %v", ifName, err)
+	}
+
+	err = netlink.LinkSetDown(link)
+	if err != nil {
+		return fmt.Errorf("failed to set %q down: %v", ifName, err)
+	}
+	err = netlink.LinkSetHardwareAddr(link, addr)
+	if err != nil {
+		return fmt.Errorf("failed to set %q address to %q: %v", ifName, newMacAddr, err)
+	}
+	return netlink.LinkSetUp(link)
+}
+
+func updateResultsMacAddr(config TuningConf, ifName string, newMacAddr string) error {
+	for _, i := range config.PrevResult.Interfaces {
+		if i.Name == ifName {
+			i.Mac = newMacAddr
+		}
+	}
+	return nil
+}
+
+func changePromisc(ifName string, val bool) error {
+	link, err := netlink.LinkByName(ifName)
+	if err != nil {
+		return fmt.Errorf("failed to get %q: %v", ifName, err)
+	}
+
+	if val {
+		return netlink.SetPromiscOn(link)
+	}
+	return netlink.SetPromiscOff(link)
+}
+
+func changeMtu(ifName string, mtu int) error {
+	link, err := netlink.LinkByName(ifName)
+	if err != nil {
+		return fmt.Errorf("failed to get %q: %v", ifName, err)
+	}
+	return netlink.LinkSetMTU(link, mtu)
+}
+
 func cmdAdd(args *skel.CmdArgs) error {
-	tuningConf, err := parseConf(args.StdinData)
+	tuningConf, err := parseConf(args.StdinData, args.Args)
 	if err != nil {
 		return err
 	}
@@ -90,6 +164,26 @@ func cmdAdd(args *skel.CmdArgs) error {
 				return err
 			}
 		}
+
+		var err error
+
+		if tuningConf.Mac != "" {
+			if err = changeMacAddr(args.IfName, tuningConf.Mac); err == nil {
+				err = updateResultsMacAddr(*tuningConf, args.IfName, tuningConf.Mac)
+			}
+		}
+
+		if tuningConf.Promisc != false {
+			if err = changePromisc(args.IfName, true); err != nil {
+				return err
+			}
+		}
+
+		if tuningConf.Mtu != -1 {
+			if err = changeMtu(args.IfName, tuningConf.Mtu); err != nil {
+				return err
+			}
+		}
 		return nil
 	})
 	if err != nil {