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Re: [Merge] ~cgrabowski/maas:go_network_discovery into maas:master

 


Diff comments:

> diff --git a/src/maasagent/cmd/netmon/main.go b/src/maasagent/cmd/netmon/main.go
> index e83655f..c88d9bf 100644
> --- a/src/maasagent/cmd/netmon/main.go
> +++ b/src/maasagent/cmd/netmon/main.go
> @@ -1,9 +1,84 @@
>  package main
>  
> +/*
> +	Copyright 2023 Canonical Ltd.  This software is licensed under the
> +	GNU Affero General Public License version 3 (see the file LICENSE).
> +*/
> +
>  import (
> +	"context"
> +	"encoding/json"
> +	"errors"
> +	"os"
> +
> +	"github.com/rs/zerolog"
> +	"github.com/rs/zerolog/log"
> +	"golang.org/x/sync/errgroup"
> +
>  	"launchpad.net/maas/maas/src/maasagent/internal/netmon"
>  )
>  
> +var (
> +	ErrMissingIface = errors.New("Missing interface argument")
> +)
> +
> +func Run() int {
> +	zerolog.SetGlobalLevel(zerolog.InfoLevel)
> +	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
> +
> +	if envLogLevel, ok := os.LookupEnv("LOG_LEVEL"); ok {
> +		if logLevel, err := zerolog.ParseLevel(envLogLevel); err != nil {
> +			log.Warn().Str("LOG_LEVEL", envLogLevel).Msg("Unknown log level, defaulting to INFO")
> +		} else {
> +			zerolog.SetGlobalLevel(logLevel)
> +		}
> +	}
> +
> +	if len(os.Args) < 2 {
> +		log.Error().Err(ErrMissingIface).Msg("Please provide an interface to monitor")

+1

> +		return 2
> +	}
> +	iface := os.Args[1]
> +
> +	ctx, cancel := context.WithCancel(context.Background())
> +
> +	sigC := make(chan os.Signal)
> +	resultC := make(chan netmon.Result)
> +
> +	g, ctx := errgroup.WithContext(ctx)
> +	g.SetLimit(2)
> +
> +	svc := netmon.NewService(iface)
> +	g.Go(func() error {
> +		return svc.Start(ctx, resultC)
> +	})
> +	g.Go(func() error {
> +		encoder := json.NewEncoder(os.Stdout)
> +		for {
> +			select {
> +			case <-sigC:
> +				cancel()
> +				return nil
> +			case res, ok := <-resultC:
> +				if !ok {
> +					log.Debug().Msg("result channel has been closed")
> +					return nil
> +				}
> +				err := encoder.Encode(res)
> +				if err != nil {
> +					return err
> +				}
> +			}
> +		}
> +	})
> +	log.Info().Msg("Service netmon started")
> +	if err := g.Wait(); err != nil {
> +		log.Error().Err(err).Send()
> +		return 1
> +	}
> +	return 0
> +}
> +
>  func main() {
> -	netmon.NewService()
> +	os.Exit(Run())
>  }
> diff --git a/src/maasagent/internal/arp/ethernet.go b/src/maasagent/internal/arp/ethernet.go
> new file mode 100644
> index 0000000..cb029aa
> --- /dev/null
> +++ b/src/maasagent/internal/arp/ethernet.go
> @@ -0,0 +1,142 @@
> +package arp

+1

> +
> +/*
> +	Copyright 2023 Canonical Ltd.  This software is licensed under the
> +	GNU Affero General Public License version 3 (see the file LICENSE).
> +*/
> +
> +import (
> +	"encoding/binary"
> +	"errors"
> +	"io"
> +	"net"
> +)
> +
> +const (
> +	minEthernetLen = 14
> +)
> +
> +const (
> +	// EthernetTypeLLC is a special ethernet type, if found the frame is truncated
> +	EthernetTypeLLC uint16 = 0
> +	// EthernetTypeIPv4 is the ethernet type for a frame containing an IPv4 packet
> +	EthernetTypeIPv4 uint16 = 0x0800
> +	// EthernetTypeARP is the ethernet type for a frame containing an ARP packet
> +	EthernetTypeARP uint16 = 0x0806
> +	// EthernetTypeIPv6 is the ethernet type for a frame containing an IPv6 packet
> +	EthernetTypeIPv6 uint16 = 0x86dd
> +	// EthernetTypeVLAN is the ethernet type for a frame containing a VLAN tag,
> +	// the VLAN tag bytes will indicate the actual type of packet the frame contains
> +	EthernetTypeVLAN uint16 = 0x8100
> +
> +	// NonStdLenEthernetTypes is a magic number to find any non-standard types
> +	// and mark them as EthernetTypeLLC
> +	NonStdLenEthernetTypes uint16 = 0x600
> +)
> +
> +var (
> +	// ErrNotVLAN is an error returned when calling EthernetFrame.ExtractVLAN
> +	// if the frame is not of type EthernetTypeVLAN
> +	ErrNotVLAN = errors.New("ethernet frame not of type VLAN")
> +	// ErrMalformedVLAN is an error returned when parsing a VLAN tag
> +	// that is malformed
> +	ErrMalformedVLAN = errors.New("VLAN tag is malformed")
> +	// ErrMalformedFrame is an error returned when parsing an ethernet frame
> +	// that is malformed
> +	ErrMalformedFrame = errors.New("malformed ethernet frame")
> +)
> +
> +// VLAN represents a VLAN tag within an ethernet frame
> +type VLAN struct {
> +	Priority     uint8
> +	DropEligible bool
> +	ID           uint16
> +	EthernetType uint16
> +}
> +
> +// UnmarshalBinary will take the ethernet frame's payload
> +// and extract a VLAN tag if one is present
> +func (v *VLAN) UnmarshalBinary(buf []byte) error {
> +	if len(buf) < 4 {
> +		return ErrMalformedVLAN
> +	}
> +
> +	// extract the first 3 bits
> +	v.Priority = (buf[0] & 0xe0) >> 5
> +	// extract the next bit and turn it into a bool
> +	v.DropEligible = buf[0]&0x10 != 0
> +	// extract the next 12 bits for an ID
> +	v.ID = binary.BigEndian.Uint16(buf[:2]) & 0x0fff
> +	// last 2 bytes are ethernet type
> +	v.EthernetType = binary.BigEndian.Uint16(buf[2:])
> +	return nil
> +}
> +
> +// EthernetFrame represents an ethernet frame
> +type EthernetFrame struct {
> +	SrcMAC       net.HardwareAddr
> +	DstMAC       net.HardwareAddr
> +	EthernetType uint16
> +	Len          uint16
> +	Payload      []byte
> +}
> +
> +// ExtractARPPacket will extract an ARP packet from the ethernet frame's
> +// payload
> +func (e *EthernetFrame) ExtractARPPacket() (*Packet, error) {
> +	var buf []byte
> +	if e.EthernetType == EthernetTypeVLAN {
> +		buf = e.Payload[4:]
> +	} else {
> +		buf = e.Payload
> +	}
> +	a := &Packet{}
> +	err := a.UnmarshalBinary(buf)
> +	if err != nil {
> +		return nil, err
> +	}
> +	return a, nil
> +}
> +
> +// ExtractVLAN will extract the VLAN tag from the ethernet frame's
> +// payload if one is present and return ErrNotVLAN if not
> +func (e *EthernetFrame) ExtractVLAN() (*VLAN, error) {
> +	if e.EthernetType != EthernetTypeVLAN {
> +		return nil, ErrNotVLAN
> +	}
> +	v := &VLAN{}
> +	err := v.UnmarshalBinary(e.Payload[0:4])
> +	if err != nil {
> +		return nil, err
> +	}
> +	return v, nil
> +}
> +
> +// UnmarshalBinary parses ethernet frame bytes into an EthernetFrame
> +func (eth *EthernetFrame) UnmarshalBinary(buf []byte) error {
> +	if len(buf) < minEthernetLen {
> +		if len(buf) == 0 {
> +			return io.ErrUnexpectedEOF
> +		}
> +		return ErrMalformedFrame
> +	}
> +
> +	eth.DstMAC = buf[0:6]
> +	eth.SrcMAC = buf[6:12]
> +	eth.EthernetType = binary.BigEndian.Uint16(buf[12:14])
> +	eth.Payload = buf[14:]
> +	if eth.EthernetType < NonStdLenEthernetTypes {
> +		// see IEEE 802.3, non-standard ethernet may contain padding
> +		// this calculation is used to truncate the payload to the length
> +		// specified for that ethernet type
> +		eth.Len = eth.EthernetType
> +		eth.EthernetType = EthernetTypeLLC
> +		cmp := len(eth.Payload) - int(eth.Len)
> +		if cmp < 0 {
> +			return ErrMalformedFrame
> +		} else if cmp > 0 {
> +			eth.Payload = eth.Payload[:len(eth.Payload)-cmp]
> +		}
> +	}
> +	return nil
> +}
> diff --git a/src/maasagent/internal/netmon/service.go b/src/maasagent/internal/netmon/service.go
> index 14ebdc6..8f8ef27 100644
> --- a/src/maasagent/internal/netmon/service.go
> +++ b/src/maasagent/internal/netmon/service.go
> @@ -1,3 +1,251 @@
>  package netmon
>  
> -func NewService() {}
> +/*
> +	Copyright 2023 Canonical Ltd.  This software is licensed under the
> +	GNU Affero General Public License version 3 (see the file LICENSE).
> +*/
> +
> +import (
> +	"bytes"
> +	"context"
> +	"errors"
> +	"fmt"
> +	"net"
> +	"net/netip"
> +	"time"
> +
> +	pcap "github.com/packetcap/go-pcap"
> +	"github.com/rs/zerolog/log"
> +
> +	"launchpad.net/maas/maas/src/maasagent/internal/arp"
> +)
> +
> +const (
> +	snapLen            int32         = 64
> +	timeout            time.Duration = -1
> +	seenAgainThreshold time.Duration = 600 * time.Second
> +)
> +
> +const (
> +	// EventNew is the Event value for a new Result
> +	EventNew = "NEW"
> +	// EventRefreshed is the Event value for a Result that is for
> +	// refreshed ARP values
> +	EventRefreshed = "REFRESHED"
> +	// EventMoved is the Event value for a Result where the IP has
> +	// changed its MAC address
> +	EventMoved = "MOVED"
> +)
> +
> +var (
> +	// ErrEmptyPacket is returned when a packet of 0 bytes has been received
> +	ErrEmptyPacket = errors.New("received an empty packet")
> +	// ErrPacketCaptureClosed is returned when the packet capture channel
> +	// has been closed unexpectedly
> +	ErrPacketCaptureClosed = errors.New("packet capture channel closed")
> +)
> +
> +// Binding represents the binding between an IP address and MAC address
> +type Binding struct {
> +	// IP is the IP a binding is tracking
> +	IP netip.Addr
> +	// MAC is the MAC address the IP is currently bound to
> +	MAC net.HardwareAddr
> +	// VID is the associated VLAN ID, if one exists
> +	VID *uint16
> +	// Time is the time the packet creating / updating the binding
> +	// was observed
> +	Time time.Time
> +}
> +
> +// Result is the result of observed ARP packets
> +type Result struct {
> +	// IP is the presentation format of an observed IP
> +	IP string `json:"ip"`
> +	// MAC is the presentation format of an observed MAC
> +	MAC string `json:"mac"`
> +	// Previous MAC is the presentation format of a previous MAC if
> +	// an EventMoved was observed
> +	PreviousMAC string `json:"previous_mac,omitempty"`
> +	// Event is the type of event the Result is
> +	Event string `json:"event"`
> +	// Time is the time the packet creating the Result was observed
> +	Time int64 `json:"time"`
> +	// VID is the VLAN ID if one exists
> +	VID *uint16 `json:"vid"`
> +}
> +
> +// Service is responsible for starting packet capture and
> +// converting observed ARP packets into discovered Results
> +type Service struct {
> +	iface    string
> +	bindings map[string]Binding
> +}
> +
> +// NewService returns a pointer to a Service. It
> +// takes the desired interface to observe's name as an argument
> +func NewService(iface string) *Service {
> +	return &Service{
> +		iface:    iface,
> +		bindings: make(map[string]Binding),
> +	}
> +}
> +
> +func (s *Service) updateBindings(pkt *arp.Packet, vid *uint16, timestamp time.Time) (res []Result) {
> +	if timestamp.IsZero() {
> +		timestamp = time.Now()
> +	}
> +
> +	var vidLabel int
> +	if vid != nil {
> +		vidLabel = int(*vid)
> +	}
> +
> +	discoveredBindings := []Binding{
> +		{
> +			IP:   pkt.SendIPAddr,
> +			MAC:  pkt.SendHwdAddr,
> +			VID:  vid,
> +			Time: timestamp,
> +		},
> +	}
> +	if pkt.OpCode == arp.OpReply {
> +		discoveredBindings = append(discoveredBindings, Binding{
> +			IP:   pkt.TgtIPAddr,
> +			MAC:  pkt.TgtHwdAddr,
> +			VID:  vid,
> +			Time: timestamp,
> +		})
> +	}
> +
> +	for _, discoveredBinding := range discoveredBindings {

well it's not a 1:1 length, a discoveredBinding may be for an existing binding that was discovered too recent to be considered a refresh. In this case, there is no result.

> +		key := fmt.Sprintf("%d_%s", vidLabel, discoveredBinding.IP.String())
> +		binding, ok := s.bindings[key]
> +		if ok {

+1

> +			if bytes.Compare(binding.MAC, discoveredBinding.MAC) != 0 {

+1

> +				s.bindings[key] = discoveredBinding

There's one case where we don't want this, and that's when the discoveredBinding is an existing one that has been seen too recently for a refresh.

> +				res = append(res, Result{

Well we only need to create a result if a binding is created or updated, this way we avoid allocating a result when it is not needed.

> +					IP:          discoveredBinding.IP.String(),
> +					PreviousMAC: binding.MAC.String(),
> +					MAC:         discoveredBinding.MAC.String(),
> +					VID:         discoveredBinding.VID,
> +					Time:        discoveredBinding.Time.Unix(),
> +					Event:       EventMoved,
> +				})
> +			} else if discoveredBinding.Time.Sub(binding.Time) >= seenAgainThreshold {
> +				s.bindings[key] = discoveredBinding
> +				res = append(res, Result{
> +					IP:    discoveredBinding.IP.String(),
> +					MAC:   discoveredBinding.MAC.String(),
> +					VID:   discoveredBinding.VID,
> +					Time:  discoveredBinding.Time.Unix(),
> +					Event: EventRefreshed,
> +				})
> +			}
> +		} else {
> +			s.bindings[key] = discoveredBinding
> +			res = append(res, Result{
> +				IP:    discoveredBinding.IP.String(),
> +				MAC:   discoveredBinding.MAC.String(),
> +				VID:   discoveredBinding.VID,
> +				Time:  discoveredBinding.Time.Unix(),
> +				Event: EventNew,
> +			})
> +		}
> +	}
> +
> +	return res
> +}
> +
> +func isValidARPPacket(pkt *arp.Packet) bool {
> +	if pkt.HardwareType != arp.HardwareTypeEthernet {
> +		return false
> +	}
> +	if pkt.ProtocolType != arp.ProtocolTypeIPv4 {
> +		return false
> +	}
> +	if pkt.HardwareAddrLen != 6 {
> +		return false
> +	}
> +	if pkt.ProtocolAddrLen != 4 {
> +		return false
> +	}
> +	return true
> +}
> +
> +func (s *Service) handlePacket(pkt pcap.Packet) ([]Result, error) {
> +	if pkt.Error != nil {
> +		return nil, pkt.Error
> +	}
> +	if len(pkt.B) == 0 {
> +		return nil, ErrEmptyPacket
> +	}
> +	eth := &arp.EthernetFrame{}
> +	err := eth.UnmarshalBinary(pkt.B)
> +	if err != nil {
> +		return nil, err
> +	}
> +
> +	if eth.EthernetType != arp.EthernetTypeVLAN && eth.EthernetType != arp.EthernetTypeARP {
> +		log.Debug().Msg("skipping non-ARP packet")
> +		return nil, nil
> +	}
> +
> +	var vid *uint16
> +	if eth.EthernetType == arp.EthernetTypeVLAN {
> +		vlan, err := eth.ExtractVLAN()
> +		if err != nil {
> +			return nil, err
> +		}
> +		vid = &vlan.ID
> +	}
> +
> +	arpPkt, err := eth.ExtractARPPacket()
> +	if err != nil {
> +		return nil, err
> +	}
> +
> +	if !isValidARPPacket(arpPkt) {

Because an ARP packet can be valid with regards for the protocol, in the event it is not, an error is returned. But `isValidARPPacket()` checks if the packet is valid with regards to what MAAS cares about.

> +		log.Debug().Msg("skipping non-ethernet+IPv4 ARP packet")
> +		return nil, nil
> +	}
> +	return s.updateBindings(arpPkt, vid, pkt.Info.Timestamp), nil
> +}
> +
> +func isRecoverableError(err error) bool {
> +	return errors.Is(err, arp.ErrMalformedPacket) || errors.Is(err, arp.ErrMalformedVLAN) || errors.Is(err, arp.ErrMalformedFrame)
> +}
> +
> +// Start will start packet capture and send results to a channel
> +func (s *Service) Start(ctx context.Context, resultC chan<- Result) error {
> +	defer close(resultC)
> +
> +	hndlr, err := pcap.OpenLive(s.iface, snapLen, false, timeout, true)
> +	if err != nil {
> +		return err
> +	}
> +	defer hndlr.Close()
> +	pkts := hndlr.Listen()
> +	for {
> +		select {
> +		case <-ctx.Done():
> +			return nil
> +		case pkt, ok := <-pkts:
> +			if !ok {
> +				log.Debug().Msg("packet capture has closed")
> +				return ErrPacketCaptureClosed
> +			}
> +			res, err := s.handlePacket(pkt)
> +			if err != nil {
> +				if isRecoverableError(err) {
> +					log.Error().Err(err).Send()
> +					continue
> +				}
> +				return err
> +			}
> +			for _, r := range res {
> +				resultC <- r
> +			}
> +		}
> +	}
> +}
> diff --git a/src/maasagent/internal/netmon/service_test.go b/src/maasagent/internal/netmon/service_test.go
> new file mode 100644
> index 0000000..158a651
> --- /dev/null
> +++ b/src/maasagent/internal/netmon/service_test.go
> @@ -0,0 +1,382 @@
> +package netmon
> +
> +/*
> +	Copyright 2023 Canonical Ltd.  This software is licensed under the
> +	GNU Affero General Public License version 3 (see the file LICENSE).
> +*/
> +
> +import (
> +	"net"
> +	"net/netip"
> +	"testing"
> +	"time"
> +
> +	"github.com/google/gopacket"
> +	pcap "github.com/packetcap/go-pcap"
> +	"github.com/stretchr/testify/assert"
> +
> +	"launchpad.net/maas/maas/src/maasagent/internal/arp"
> +)
> +
> +func uint16Pointer(v uint16) *uint16 {
> +	return &v
> +}
> +
> +type isValidARPPacketCase struct {
> +	Name string
> +	In   *arp.Packet
> +	Out  bool
> +}
> +
> +func TestIsValidARPPacket(t *testing.T) {
> +	table := []isValidARPPacketCase{

mostly as I was writing it the original way, I found I was repeating a lot of code, using a testCase struct in this case allowed me embed common fields and use the named type instead of the inline struct, reducing lines of code.

> +		{
> +			Name: "ValidARPPacket",
> +			In: &arp.Packet{
> +				HardwareType:    arp.HardwareTypeEthernet,
> +				ProtocolType:    arp.ProtocolTypeIPv4,
> +				HardwareAddrLen: 6,
> +				ProtocolAddrLen: 4,
> +			},
> +			Out: true,
> +		},
> +		{
> +			Name: "InvalidHardwareTypeARPPacket",
> +			In: &arp.Packet{
> +				HardwareType:    arp.HardwareTypeChaos,
> +				ProtocolType:    arp.ProtocolTypeIPv4,
> +				HardwareAddrLen: 6,
> +				ProtocolAddrLen: 4,
> +			},
> +			Out: false,
> +		},
> +		{
> +			Name: "InvalidProtocolTypeARPPacket",
> +			In: &arp.Packet{
> +				HardwareType:    arp.HardwareTypeEthernet,
> +				ProtocolType:    arp.ProtocolTypeIPv6,
> +				HardwareAddrLen: 6,
> +				ProtocolAddrLen: 4,
> +			},
> +			Out: false,
> +		},
> +		{
> +			Name: "InvalidHardwareAddrLenARPPacket",
> +			In: &arp.Packet{
> +				HardwareType:    arp.HardwareTypeEthernet,
> +				ProtocolType:    arp.ProtocolTypeIPv4,
> +				HardwareAddrLen: 8,
> +				ProtocolAddrLen: 4,
> +			},
> +			Out: false,
> +		},
> +		{
> +			Name: "InvalidProtocolAddrLenARPPacket",
> +			In: &arp.Packet{
> +				HardwareType:    arp.HardwareTypeEthernet,
> +				ProtocolType:    arp.ProtocolTypeIPv4,
> +				HardwareAddrLen: 6,
> +				ProtocolAddrLen: 16,
> +			},
> +			Out: false,
> +		},
> +	}
> +	for _, tcase := range table {
> +		t.Run(tcase.Name, func(tt *testing.T) {
> +			assert.Equalf(tt, tcase.Out, isValidARPPacket(tcase.In), "expected the result to be %v", tcase.Out)
> +		})
> +	}
> +}
> +
> +type updateBindingsArgs struct {
> +	Pkt  *arp.Packet
> +	VID  *uint16
> +	Time time.Time
> +}
> +
> +type updateBindingsCase struct {
> +	Name            string
> +	BindingsFixture map[string]Binding
> +	In              updateBindingsArgs
> +	Out             []Result
> +}
> +
> +func TestUpdateBindings(t *testing.T) {
> +	timestamp := time.Now()
> +	testIP1 := net.ParseIP("10.0.0.1").To4()
> +	testIP2 := net.ParseIP("10.0.0.2").To4()
> +	table := []updateBindingsCase{
> +		{
> +			Name: "NewRequestPacket",
> +			In: updateBindingsArgs{
> +				Pkt: &arp.Packet{
> +					HardwareType:    arp.HardwareTypeEthernet,
> +					ProtocolType:    arp.ProtocolTypeIPv4,
> +					HardwareAddrLen: 6,
> +					ProtocolAddrLen: 4,
> +					OpCode:          arp.OpRequest,
> +					SendHwdAddr:     net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					SendIPAddr:      netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					TgtIPAddr:       netip.AddrFrom4([4]byte{testIP2[0], testIP2[1], testIP2[2], testIP2[3]}),
> +				},
> +				Time: timestamp,
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "10.0.0.1",
> +					MAC:   "c0:ff:ee:15:c0:01",
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +			},
> +		},
> +		{
> +			Name: "NewReplyPacket",
> +			In: updateBindingsArgs{
> +				Pkt: &arp.Packet{
> +					HardwareType:    arp.HardwareTypeEthernet,
> +					ProtocolType:    arp.ProtocolTypeIPv4,
> +					HardwareAddrLen: 6,
> +					ProtocolAddrLen: 4,
> +					OpCode:          arp.OpReply,
> +					SendHwdAddr:     net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					SendIPAddr:      netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					TgtHwdAddr:      net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x1d},
> +					TgtIPAddr:       netip.AddrFrom4([4]byte{testIP2[0], testIP2[1], testIP2[2], testIP2[3]}),
> +				},
> +				Time: timestamp,
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "10.0.0.1",
> +					MAC:   "c0:ff:ee:15:c0:01",
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +				{
> +					IP:    "10.0.0.2",
> +					MAC:   "c0:ff:ee:15:c0:1d",
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +			},
> +		},
> +		{
> +			Name: "NewVLANPacket",
> +			In: updateBindingsArgs{
> +				Pkt: &arp.Packet{
> +					HardwareType:    arp.HardwareTypeEthernet,
> +					ProtocolType:    arp.ProtocolTypeIPv4,
> +					HardwareAddrLen: 6,
> +					ProtocolAddrLen: 4,
> +					OpCode:          arp.OpRequest,
> +					SendHwdAddr:     net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					SendIPAddr:      netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					TgtIPAddr:       netip.AddrFrom4([4]byte{testIP2[0], testIP2[1], testIP2[2], testIP2[3]}),
> +				},
> +				VID:  uint16Pointer(2),
> +				Time: timestamp,
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "10.0.0.1",
> +					MAC:   "c0:ff:ee:15:c0:01",
> +					Time:  timestamp.Unix(),
> +					VID:   uint16Pointer(2),
> +					Event: EventNew,
> +				},
> +			},
> +		},
> +		{
> +			Name: "Refresh",
> +			BindingsFixture: map[string]Binding{
> +				"0_10.0.0.1": Binding{
> +					IP:   netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					MAC:  net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					Time: timestamp,
> +				},
> +			},
> +			In: updateBindingsArgs{
> +				Pkt: &arp.Packet{
> +					HardwareType:    arp.HardwareTypeEthernet,
> +					ProtocolType:    arp.ProtocolTypeIPv4,
> +					HardwareAddrLen: 6,
> +					ProtocolAddrLen: 4,
> +					OpCode:          arp.OpRequest,
> +					SendHwdAddr:     net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					SendIPAddr:      netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					TgtIPAddr:       netip.AddrFrom4([4]byte{testIP2[0], testIP2[1], testIP2[2], testIP2[3]}),
> +				},
> +				Time: timestamp.Add(seenAgainThreshold + time.Second),
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "10.0.0.1",
> +					MAC:   "c0:ff:ee:15:c0:01",
> +					Time:  timestamp.Add(seenAgainThreshold + time.Second).Unix(),
> +					Event: EventRefreshed,
> +				},
> +			},
> +		},
> +		{
> +			Name: "Move",
> +			BindingsFixture: map[string]Binding{
> +				"0_10.0.0.1": Binding{
> +					IP:   netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					MAC:  net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x01},
> +					Time: timestamp,
> +				},
> +			},
> +			In: updateBindingsArgs{
> +				Pkt: &arp.Packet{
> +					HardwareType:    arp.HardwareTypeEthernet,
> +					ProtocolType:    arp.ProtocolTypeIPv4,
> +					HardwareAddrLen: 6,
> +					ProtocolAddrLen: 4,
> +					OpCode:          arp.OpRequest,
> +					SendHwdAddr:     net.HardwareAddr{0xc0, 0xff, 0xee, 0x15, 0xc0, 0x1d},
> +					SendIPAddr:      netip.AddrFrom4([4]byte{testIP1[0], testIP1[1], testIP1[2], testIP1[3]}),
> +					TgtIPAddr:       netip.AddrFrom4([4]byte{testIP2[0], testIP2[1], testIP2[2], testIP2[3]}),
> +				},
> +				Time: timestamp,
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "10.0.0.1",
> +					MAC:   "c0:ff:ee:15:c0:1d",
> +					Time:  timestamp.Unix(),
> +					Event: EventMoved,
> +				},
> +			},
> +		},
> +	}
> +	for _, tcase := range table {
> +		t.Run(tcase.Name, func(tt *testing.T) {
> +			svc := NewService("lo")
> +			if tcase.BindingsFixture != nil {
> +				svc.bindings = tcase.BindingsFixture
> +			}
> +			res := svc.updateBindings(tcase.In.Pkt, tcase.In.VID, tcase.In.Time)
> +			for i, expected := range tcase.Out {
> +				var expectedVID int
> +				if expected.VID != nil {
> +					expectedVID = int(*expected.VID)
> +				}
> +				assert.Equalf(tt, expected.IP, res[i].IP, "expected Result at index of %d to have the IP %s", i, expected.IP)
> +				assert.Equalf(tt, expected.MAC, res[i].MAC, "expected Result at index of %d to have the MAC %s", i, expected.MAC)
> +				assert.Equalf(tt, expected.VID, res[i].VID, "expected Result at index of %d to have the VID %d", i, expectedVID)
> +				assert.Equalf(tt, expected.Time, res[i].Time, "expected Result at index of %d to have the Time of %d", i, int(expected.Time))
> +				assert.Equalf(tt, expected.Event, res[i].Event, "expected Result at index of %d to have the Event of %s", i, expected.Event)
> +			}
> +		})
> +	}
> +}
> +
> +type handlePacketCase struct {
> +	Name string
> +	In   pcap.Packet
> +	Out  []Result
> +	Err  error
> +}
> +
> +func TestServiceHandlePacket(t *testing.T) {
> +	timestamp := time.Now()
> +	table := []handlePacketCase{
> +		{
> +			Name: "ValidRequestPacket",
> +			In: pcap.Packet{
> +				// generated from tcpdump
> +				B: []byte{
> +					0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x84, 0x39, 0xc0, 0x0b, 0x22, 0x25, 0x81, 0x00, 0x00, 0x02,
> +					0x08, 0x06, 0x00, 0x01, 0x08, 0x00, 0x06, 0x04, 0x00, 0x01, 0x84, 0x39, 0xc0, 0x0b, 0x22, 0x25,
> +					0xc0, 0xa8, 0x0a, 0x1a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xa8, 0x0a, 0x19, 0x00, 0x00,
> +					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> +				},
> +				Info: gopacket.CaptureInfo{
> +					Timestamp: timestamp,
> +				},
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "192.168.10.26",
> +					MAC:   "84:39:c0:0b:22:25",
> +					VID:   uint16Pointer(2),
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +			},
> +		},
> +		{
> +			Name: "ValidReplyPacket",
> +			In: pcap.Packet{
> +				B: []byte{
> +					0x24, 0x4b, 0xfe, 0xe1, 0xea, 0x26, 0x80, 0x61, 0x5f, 0x08, 0xfc, 0x16, 0x08, 0x06, 0x00, 0x01,
> +					0x08, 0x00, 0x06, 0x04, 0x00, 0x02, 0x80, 0x61, 0x5f, 0x08, 0xfc, 0x16, 0xc0, 0xa8, 0x01, 0x6c,
> +					0x24, 0x4b, 0xfe, 0xe1, 0xea, 0x26, 0xc0, 0xa8, 0x01, 0x50,
> +				},
> +			},
> +			Out: []Result{
> +				{
> +					IP:    "192.168.1.108",
> +					MAC:   "80:61:5f:08:fc:16",
> +					VID:   nil,
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +				{
> +					IP:    "192.168.1.80",
> +					MAC:   "24:4b:fe:e1:ea:26",
> +					VID:   nil,
> +					Time:  timestamp.Unix(),
> +					Event: EventNew,
> +				},
> +			},
> +		},
> +		{
> +			Name: "EmptyPacket",
> +			Err:  ErrEmptyPacket,
> +		},
> +		{
> +			Name: "MalformedPacket",
> +			In: pcap.Packet{
> +				B: []byte{
> +					0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x84, 0x39, 0xc0, 0x0b, 0x22,
> +					0x08, 0x06, 0x00, 0x01, 0x08, 0x06, 0x04, 0x00, 0x01, 0x84,
> +					0xc0, 0xa8, 0x0a, 0x1a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0,
> +					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> +				},
> +			},
> +			// should return nil, nil
> +		},
> +		{
> +			Name: "ShortPacket",
> +			In: pcap.Packet{
> +				B: []byte{
> +					0x24, 0x4b, 0xfe, 0xe1, 0xea, 0x26, 0x80, 0x61, 0x5f, 0x08, 0xfc, 0x16, 0x08, 0x06, 0x00, 0x01,
> +					0x08, 0x00, 0x06, 0x04, 0x00, 0x02, 0x80, 0xfc, 0x16, 0xc0, 0xa8, 0x01, 0x6c,
> +					0x24, 0x4b, 0xfe, 0xe1, 0xea, 0x26, 0xc0, 0xa8, 0x01, 0x50,
> +				},
> +			},
> +			Err: arp.ErrMalformedPacket,
> +		},
> +	}
> +
> +	svc := NewService("")
> +
> +	for _, tcase := range table {
> +		t.Run(tcase.Name, func(tt *testing.T) {
> +			res, err := svc.handlePacket(tcase.In)
> +			assert.ErrorIsf(tt, err, tcase.Err, "expected handlePacket to return an error of: %s", tcase.Err)
> +			if tcase.Out != nil {
> +				for i, expected := range tcase.Out {
> +					assert.Equalf(tt, expected.IP, res[i].IP, "expected result at index %d to have an IP address of %s", i, expected.IP)
> +					assert.Equalf(tt, expected.MAC, res[i].MAC, "expected result at index %d to have a MAC address of %s", i, expected.MAC)
> +					assert.Equalf(tt, expected.VID, res[i].VID, "expected result at index %d to have a VID of %v", i, expected.VID)
> +					assert.Equalf(tt, expected.Time, res[i].Time, "expected result at index %d to have a Time of %s", i, expected.Time)
> +				}
> +			} else {
> +				assert.Nil(tt, res)
> +			}
> +		})
> +	}
> +}


-- 
https://code.launchpad.net/~cgrabowski/maas/+git/maas/+merge/441702
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References