dhcpv4.go

package cmd

import (
	"errors"
	"github.com/google/gopacket"
	"github.com/google/gopacket/layers"
	"github.com/ipchama/dhammer/config"
	"github.com/ipchama/dhammer/hammer"
	"github.com/ipchama/dhammer/message"
	"github.com/ipchama/dhammer/socketeer"
	"github.com/spf13/cobra"
	"github.com/vishvananda/netlink"
	"golang.org/x/sys/unix"
	"net"
	"sync"
	"time"
)

func prepareCmd(cmd *cobra.Command) *cobra.Command {
	cmd.Flags().Bool("handshake", true, "Attempt full handshakes")
	cmd.Flags().Bool("info", false, "Send DHCPINFO packets. This requires a full handshake.")
	cmd.Flags().Bool("dhcp-broadcast", true, "Set the broadcast bit.")
	cmd.Flags().Bool("ethernet-broadcast", true, "Use ethernet broadcasting.")
	cmd.Flags().Bool("release", false, "Release leases after acquiring them.")

	cmd.Flags().Bool("decline", false, "Decline offers.")

	cmd.Flags().Int("rps", 0, "Max number of packets per second. 0 == unlimited.")
	cmd.Flags().Int("maxlife", 0, "How long to run. 0 == forever")
	cmd.Flags().Int("mac-count", 1, "Total number of MAC addresses to use. If the 'mac' option is used, mac-count - number of mac will be used to pad with additional pre-generated MAC addresses.")
	cmd.Flags().StringArray("mac", []string{}, "Optionally specified MAC address to be used for requesting leases. Can be used multiple times.")

	cmd.Flags().Int("stats-rate", 5, "How frequently to update stat calculations. (seconds).")

	cmd.Flags().Bool("arp", false, "Respond to arp requests for assigned IPs.")
	cmd.Flags().Bool("arp-fake-mac", false, "Respond to ARP requests with the generated MAC used to originally obtain the lease.  You might want to set arp_ignore to 1 or 3 for the interface sending packets. For full functionality, the --promisc option is needed.")
	cmd.Flags().Bool("bind", false, "Bind acquired IPs to the loopback device.  Combined with the --arp option, this will result in fully functioning IPs.")

	cmd.Flags().String("relay-source-ip", "", "Source IP for relayed requests.  relay-source-ip AND relay-target-server-ip must be set for relay mode.")
	cmd.Flags().String("relay-gateway-ip", "", "Gateway (giaddr) IP for relayed requests.  If not set, it will default to the relay source IP.")
	cmd.Flags().String("relay-target-server-ip", "", "Target/Destination IP for relayed requests.  relay-source-ip AND relay-target-server-ip must be set for relay mode.")
	cmd.Flags().Int("target-port", 67, "Target port for special cases.  Rarely would you want to use this.")

	cmd.Flags().StringArray("dhcp-option", []string{}, "Additional DHCP option to send out in the discover. Can be used multiple times. Format: <option num>:<RFC4648-base64-encoded-value>")

	cmd.Flags().String("interface", "eth0", "Interface name for listening and sending.")
	cmd.Flags().String("gateway-mac", "auto", "MAC of the gateway.")
	cmd.Flags().Bool("promisc", false, "Turn on promiscuous mode for the listening interface.")

	cmd.Flags().String("api-address", "", "IP for the API server to listen on.")
	cmd.Flags().Int("api-port", 8080, "Port for the API server to listen on.")

	return cmd
}

func getVal(i interface{}, err error) interface{} {
	if err != nil {
		panic(err)
	}

	return i
}

func arp(n string, l netlink.Link, i net.IP) (net.HardwareAddr, error) {

	srcAddr := getVal(netlink.AddrList(l, netlink.FAMILY_V4)).([]netlink.Addr)[0]

	s := socketeer.NewRawSocketeer(&config.SocketeerOptions{InterfaceName: n}, func(s string) bool { return true }, func(e error) bool { println(e); return true })

	if err := s.Init(); err != nil {
		return nil, err
	}

	arpReplies := make(chan net.HardwareAddr)

	s.SetReceiver(func(msg message.Message) bool {
		if msg.Packet.Layer(layers.LayerTypeARP) != nil {
			arpMsg := msg.Packet.Layer(layers.LayerTypeARP).(*layers.ARP)
			if arpMsg.Operation == layers.ARPReply {
				if net.IP(arpMsg.SourceProtAddress).String() == i.String() {
					select {
					case arpReplies <- arpMsg.SourceHwAddress:
					default:
					}
				}
			}
		}

		return true
	})

	var wg sync.WaitGroup

	wg.Add(1)
	go func() {
		s.RunWriter()
		wg.Done()

	}()
	wg.Add(1)
	go func() {
		s.RunListener()
		wg.Done()
	}()

	goPacketSerializeOpts := gopacket.SerializeOptions{FixLengths: true, ComputeChecksums: true}

	ethernetLayer := &layers.Ethernet{
		DstMAC:       layers.EthernetBroadcast,
		SrcMAC:       s.IfInfo.HardwareAddr,
		EthernetType: layers.EthernetTypeARP,
		Length:       0,
	}

	arpLayer := &layers.ARP{
		Operation:         layers.ARPRequest,
		DstHwAddress:      layers.EthernetBroadcast, // Broadcast
		DstProtAddress:    i,
		HwAddressSize:     6,
		AddrType:          1, // Netlink type: ethernet
		ProtAddressSize:   4,
		Protocol:          0x800, // Ipv4
		SourceHwAddress:   s.IfInfo.HardwareAddr,
		SourceProtAddress: srcAddr.IP,
	}
	buf := gopacket.NewSerializeBuffer()

	gopacket.SerializeLayers(buf, goPacketSerializeOpts,
		ethernetLayer,
		arpLayer,
	)

	s.AddPayload(buf.Bytes())

	timer := time.NewTimer(5 * time.Second)
	go func() {
		<-timer.C
		close(arpReplies)
	}()

	gwMac, ok := <-arpReplies

	timer.Stop()

	/*	Many things could happen here that we really don't need to care about and that could cause "false-positive" failures.
		Either we got an arp response or we didn't.  The !ok test below is all that should matter.  We just want output for debugging purposes.
		Still, revisit becasue this could still be handled better..
	*/
	if err := s.StopListener(); err != nil {
		println(err)
	}

	if err := s.StopWriter(); err != nil {
		println(err)
	}

	wg.Wait()

	if !ok {
		return nil, errors.New("Failed to get ARP response for default gateway probe during init.")
	}

	return gwMac, nil
}

func init() {

	rootCmd.AddCommand(prepareCmd(&cobra.Command{
		Use:   "dhcpv4",
		Short: "Run a dhcpv4 load test.",
		Long:  `Run a dhcpv4 load test.`,
		Run: func(cmd *cobra.Command, args []string) {

			options := &config.DhcpV4Options{}
			socketeerOptions := &config.SocketeerOptions{}

			var err error

			options.Handshake = getVal(cmd.Flags().GetBool("handshake")).(bool)

			options.DhcpInfo = getVal(cmd.Flags().GetBool("info")).(bool)
			options.DhcpBroadcast = getVal(cmd.Flags().GetBool("dhcp-broadcast")).(bool)
			options.EthernetBroadcast = getVal(cmd.Flags().GetBool("ethernet-broadcast")).(bool)
			options.DhcpRelease = getVal(cmd.Flags().GetBool("release")).(bool)
			options.DhcpDecline = getVal(cmd.Flags().GetBool("decline")).(bool)

			options.RequestsPerSecond = getVal(cmd.Flags().GetInt("rps")).(int)
			options.MaxLifetime = getVal(cmd.Flags().GetInt("maxlife")).(int)
			options.MacCount = getVal(cmd.Flags().GetInt("mac-count")).(int)
			options.SpecifiedMacs = getVal(cmd.Flags().GetStringArray("mac")).([]string)

			if options.MacCount <= 0 && len(options.SpecifiedMacs) == 0 {
				panic("At least one of mac-count or mac options must be used.")
			}

			options.StatsRate = getVal(cmd.Flags().GetInt("stats-rate")).(int)

			options.Arp = getVal(cmd.Flags().GetBool("arp")).(bool)
			options.ArpFakeMAC = getVal(cmd.Flags().GetBool("arp-fake-mac")).(bool)
			options.Bind = getVal(cmd.Flags().GetBool("bind")).(bool)

			relayIP := getVal(cmd.Flags().GetString("relay-source-ip")).(string)
			relayGatewayIP := getVal(cmd.Flags().GetString("relay-gateway-ip")).(string)

			targetServerIP := getVal(cmd.Flags().GetString("relay-target-server-ip")).(string)
			options.TargetPort = getVal(cmd.Flags().GetInt("target-port")).(int)
			options.AdditionalDhcpOptions = getVal(cmd.Flags().GetStringArray("dhcp-option")).([]string)

			socketeerOptions.InterfaceName = getVal(cmd.Flags().GetString("interface")).(string)
			gatewayMAC := getVal(cmd.Flags().GetString("gateway-mac")).(string)
			socketeerOptions.PromiscuousMode = getVal(cmd.Flags().GetBool("promisc")).(bool)

			ApiAddress := getVal(cmd.Flags().GetString("api-address")).(string)
			ApiPort := getVal(cmd.Flags().GetInt("api-port")).(int)

			options.RelaySourceIP = net.ParseIP(relayIP)
			options.RelayGatewayIP = net.ParseIP(relayGatewayIP)
			options.RelayTargetServerIP = net.ParseIP(targetServerIP)

			if options.RelayGatewayIP == nil {
				options.RelayGatewayIP = options.RelaySourceIP
			}

			if options.RelaySourceIP != nil && options.RelayTargetServerIP != nil {
				options.DhcpRelay = true
			}

			// netlink and arp to get the gw IP and then ARP to get the MAC
			if gatewayMAC == "auto" {
				link := getVal(netlink.LinkByName(socketeerOptions.InterfaceName)).(netlink.Link)
				routes := getVal(netlink.RouteList(link, netlink.FAMILY_V4)).([]netlink.Route)

				for _, r := range routes {
					if r.Dst == nil && r.Src == nil { // We've found the default route.
						socketeerOptions.GatewayMAC = getVal(arp(socketeerOptions.InterfaceName, link, r.Gw)).(net.HardwareAddr)
						break
					}
				}
			} else {
				socketeerOptions.GatewayMAC, err = net.ParseMAC(gatewayMAC)
				if err != nil {
					panic(err)
				}
			}

			if options.StatsRate <= 0 {
				options.StatsRate = 5
			}

			filter := [28]unix.SockFilter{{0x28, 0, 0, 0x0000000c}, // "arp or (port 67 or port 68)"
				{0x15, 24, 0, 0x00000806},
				{0x15, 0, 9, 0x000086dd},
				{0x30, 0, 0, 0x00000014},
				{0x15, 2, 0, 0x00000084},
				{0x15, 1, 0, 0x00000006},
				{0x15, 0, 20, 0x00000011},
				{0x28, 0, 0, 0x00000036},
				{0x15, 17, 0, 0x00000043},
				{0x15, 16, 0, 0x00000044},
				{0x28, 0, 0, 0x00000038},
				{0x15, 14, 13, 0x00000043},
				{0x15, 0, 14, 0x00000800},
				{0x30, 0, 0, 0x00000017},
				{0x15, 2, 0, 0x00000084},
				{0x15, 1, 0, 0x00000006},
				{0x15, 0, 10, 0x00000011},
				{0x28, 0, 0, 0x00000014},
				{0x45, 8, 0, 0x00001fff},
				{0xb1, 0, 0, 0x0000000e},
				{0x48, 0, 0, 0x0000000e},
				{0x15, 4, 0, 0x00000043},
				{0x15, 3, 0, 0x00000044},
				{0x48, 0, 0, 0x00000010},
				{0x15, 1, 0, 0x00000043},
				{0x15, 0, 1, 0x00000044},
				{0x6, 0, 0, 0x00040000},
				{0x6, 0, 0, 0x00000000}}

			socketeerOptions.EbpfFilter = &unix.SockFprog{28, &filter[0]}

			gHammer = hammer.New(socketeerOptions, options)

			err = gHammer.Init(ApiAddress, ApiPort)

			if err != nil {
				panic(err)
			}

			err = gHammer.Run()

			if err != nil {
				panic(err)
			}
		},
	}))

}