package main

import (
	"fmt"
	"net"
	"os"

	"github.com/mdlayher/netlink"

	"github.com/florianl/go-tc"
)

func main() {
	// open a rtnetlink socket
	rtnl, 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 := rtnl.Close(); err != nil {
			fmt.Fprintf(os.Stderr, "could not close rtnetlink socket: %v\n", err)
		}
	}()

	// For enhanced error messages from the kernel, it is recommended to set
	// option `NETLINK_EXT_ACK`, which is supported since 4.12 kernel.
	//
	// If not supported, `unix.ENOPROTOOPT` is returned.

	err = rtnl.SetOption(netlink.ExtendedAcknowledge, true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not set option ExtendedAcknowledge: %v\n", err)
		return
	}

	// get all the qdiscs from all interfaces
	qdiscs, err := rtnl.Qdisc().Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not get qdiscs: %v\n", err)
		return
	}

	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)
	}
}