example_netem_test.go

//go:build linux
// +build linux

package tc_test

import (
	"fmt"
	"net"
	"os"
	"time"

	"github.com/florianl/go-tc"
	"github.com/florianl/go-tc/core"
	"github.com/jsimonetti/rtnetlink"
	"golang.org/x/sys/unix"
)

func ExampleNetem() {
	tcIface := "ExampleNetem"

	rtnl, err := setupDummyInterface(tcIface)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not setup dummy interface: %v\n", err)
		return
	}
	defer rtnl.Close()

	devID, err := net.InterfaceByName(tcIface)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not get interface ID: %v\n", err)
		return
	}
	defer func(devID uint32, rtnl *rtnetlink.Conn) {
		if err := rtnl.Link.Delete(devID); err != nil {
			fmt.Fprintf(os.Stderr, "could not delete interface: %v\n", err)
		}
	}(uint32(devID.Index), rtnl)

	tcnl, err := tc.Open(&tc.Config{})
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not open rtnetlink socket: %v\n", err)
		return
	}
	defer func() {
		if err := tcnl.Close(); err != nil {
			fmt.Fprintf(os.Stderr, "could not close rtnetlink socket: %v\n", err)
		}
	}()

	var ecn uint32 = 1
	qdisc := tc.Object{
		tc.Msg{
			Family:  unix.AF_UNSPEC,
			Ifindex: uint32(devID.Index),
			Handle:  core.BuildHandle(0x1, 0x0),
			Parent:  tc.HandleRoot,
			Info:    0,
		},
		tc.Attribute{
			Kind: "netem",
			// tc qdisc replace dev tcDev root netem loss 1% ecn
			Netem: &tc.Netem{
				Qopt: tc.NetemQopt{
					Limit: 1000,
					Loss:  42949673,
				},
				Ecn: &ecn,
			},
		},
	}

	if err := tcnl.Qdisc().Replace(&qdisc); err != nil {
		fmt.Fprintf(os.Stderr, "could not assign qdisc netem to lo: %v\n", err)
		return
	}
	defer func() {
		if err := tcnl.Qdisc().Delete(&qdisc); err != nil {
			fmt.Fprintf(os.Stderr, "could not delete netem qdisc of lo: %v\n", err)
			return
		}
	}()
	qdiscs, err := tcnl.Qdisc().Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not get all qdiscs: %v\n", err)
	}

	for _, qdisc := range qdiscs {
		iface, err := net.InterfaceByIndex(int(qdisc.Ifindex))
		if err != nil {
			fmt.Fprintf(os.Stderr, "could not get interface from id %d: %v", qdisc.Ifindex, err)
			return
		}
		fmt.Printf("%20s\t%s\n", iface.Name, qdisc.Kind)
	}
}

func ExampleNetem_with_delay() {
	// Initialize clock parameters
	if err := core.InitializeClock(); err != nil {
		fmt.Fprintf(os.Stderr, "could not initialize clock: %v\n", err)
		return
	}

	tcIface := "ExampleNetemDelay"

	rtnl, err := setupDummyInterface(tcIface)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not setup dummy interface: %v\n", err)
		return
	}
	defer rtnl.Close()

	devID, err := net.InterfaceByName(tcIface)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not get interface ID: %v\n", err)
		return
	}
	defer func(devID uint32, rtnl *rtnetlink.Conn) {
		if err := rtnl.Link.Delete(devID); err != nil {
			fmt.Fprintf(os.Stderr, "could not delete interface: %v\n", err)
		}
	}(uint32(devID.Index), rtnl)

	tcnl, err := tc.Open(&tc.Config{})
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not open rtnetlink socket: %v\n", err)
		return
	}
	defer func() {
		if err := tcnl.Close(); err != nil {
			fmt.Fprintf(os.Stderr, "could not close rtnetlink socket: %v\n", err)
		}
	}()

	tcTime, err := core.Duration2TcTime(100 * time.Millisecond)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not convert duration to TC time: %v\n", err)
		return
	}
	ticks := core.Time2Tick(tcTime)

	qdisc := tc.Object{
		tc.Msg{
			Family:  unix.AF_UNSPEC,
			Ifindex: uint32(devID.Index),
			Handle:  core.BuildHandle(0x1, 0x0),
			Parent:  tc.HandleRoot,
			Info:    0,
		},
		tc.Attribute{
			Kind: "netem",
			// tc qdisc add dev tcDev root netem delay 100ms
			Netem: &tc.Netem{
				Qopt: tc.NetemQopt{
					Latency: ticks,
					Limit:   1000,
				},
			},
		},
	}

	if err := tcnl.Qdisc().Replace(&qdisc); err != nil {
		fmt.Fprintf(os.Stderr, "could not assign qdisc netem to lo: %v\n", err)
		return
	}
	defer func() {
		if err := tcnl.Qdisc().Delete(&qdisc); err != nil {
			fmt.Fprintf(os.Stderr, "could not delete netem qdisc of lo: %v\n", err)
			return
		}
	}()
	qdiscs, err := tcnl.Qdisc().Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not get all qdiscs: %v\n", err)
	}

	for _, qdisc := range qdiscs {
		iface, err := net.InterfaceByIndex(int(qdisc.Ifindex))
		if err != nil {
			fmt.Fprintf(os.Stderr, "could not get interface from id %d: %v", qdisc.Ifindex, err)
			return
		}
		fmt.Printf("%20s\t%s\n", iface.Name, qdisc.Kind)
	}
}