HTB qdisc with two classes

maing.o

package main

import (
	"fmt"
	"net"
	"os"

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

// setupDummyInterface installs a temporary dummy interface
func setupDummyInterface(iface string) (*rtnetlink.Conn, error) {
	con, err := rtnetlink.Dial(nil)
	if err != nil {
		return &rtnetlink.Conn{}, err
	}

	if err := con.Link.New(&rtnetlink.LinkMessage{
		Family: unix.AF_UNSPEC,
		Type:   unix.ARPHRD_NETROM,
		Index:  0,
		Flags:  unix.IFF_UP,
		Change: unix.IFF_UP,
		Attributes: &rtnetlink.LinkAttributes{
			Name: iface,
			Info: &rtnetlink.LinkInfo{Kind: "dummy"},
		},
	}); err != nil {
		return con, err
	}

	return con, err
}

func main() {
	tcIface := "tcDummyIface"

	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)
		}
	}()

	qdisc := tc.Object{
		Msg: tc.Msg{
			Family:  unix.AF_UNSPEC,
			Ifindex: uint32(devID.Index),
			Handle:  core.BuildHandle(0x1, 0x0),
			Parent:  tc.HandleRoot,
			Info:    0,
		},
		// configure a very basic hierarchy token bucket (htb) qdisc
		Attribute: tc.Attribute{
			Kind: "htb",
			Htb: &tc.Htb{
				Init: &tc.HtbGlob{
					Version:      0x3,
					Rate2Quantum: 0xa,
				},
			},
		},
	}

	// tc qdisc add dev <iface> root handle 1: htb
	if err := tcnl.Qdisc().Add(&qdisc); err != nil {
		fmt.Fprintf(os.Stderr, "could not assign htb to lo: %v\n", err)
		return
	}

	// delete the qdisc, if this program terminates
	defer func() {
		if err := tcnl.Qdisc().Delete(&qdisc); err != nil {
			fmt.Fprintf(os.Stderr, "could not delete htb 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)
	}

	// Parent Qdisc for HTB class
	parentQdisc := uint32(0)

	for _, qdisc := range qdiscs {
		if qdisc.Ifindex != uint32(devID.Index) {
			continue
		}
		parentQdisc = qdisc.Msg.Handle
	}
	if parentQdisc == 0 {
		fmt.Fprintf(os.Stderr, "failed to get parent qdisc for class")
		return
	}

	// tc class add dev <iface> parent 1: classid 10 htb rate 5mbit ceil 10mbit
	if err := tcnl.Class().Add(&tc.Object{
		Msg: tc.Msg{
			Family:  unix.AF_UNSPEC,
			Ifindex: uint32(devID.Index),
			Handle:  core.BuildHandle(0, 0x10),
			Parent:  parentQdisc,
		},
		Attribute: tc.Attribute{
			Kind: "htb",
			Htb: &tc.Htb{
				Parms: &tc.HtbOpt{
					Rate: tc.RateSpec{CellLog: 0x3, Linklayer: 0x1, Overhead: 0x0, CellAlign: 0xffff, Mpu: 0x0, Rate: 0x98968},
					Ceil: tc.RateSpec{CellLog: 0x3, Linklayer: 0x1, Overhead: 0x0, CellAlign: 0xffff, Mpu: 0x0, Rate: 0x1312d0},
				},
			},
		},
	}); err != nil {
		fmt.Fprintf(os.Stderr, "failed to create htb class 0x10: %v\n", err)
		return
	}

	// tc class add dev <iface> parent 1: classid 20 htb rate 2mbit ceil 3mbit
	if err := tcnl.Class().Add(&tc.Object{
		Msg: tc.Msg{
			Family:  unix.AF_UNSPEC,
			Ifindex: uint32(devID.Index),
			Handle:  core.BuildHandle(0, 0x20),
			Parent:  parentQdisc,
		},
		Attribute: tc.Attribute{
			Kind: "htb",
			Htb: &tc.Htb{
				Parms: &tc.HtbOpt{
					Rate: tc.RateSpec{CellLog: 0x3, Linklayer: 0x1, Overhead: 0x0, CellAlign: 0xffff, Mpu: 0x0, Rate: 0x3d090},
					Ceil: tc.RateSpec{CellLog: 0x3, Linklayer: 0x1, Overhead: 0x0, CellAlign: 0xffff, Mpu: 0x0, Rate: 0x5b8d8},
				},
			},
		},
	}); err != nil {
		fmt.Fprintf(os.Stderr, "failed to create htb class 0x20: %v\n", err)
		return
	}
}