Pull request 1771: AG-20352-dhcpd-lease-netip-addr

Merge in DNS/adguard-home from AG-20352-dhcpd-lease-netip-addr to master

Squashed commit of the following:

commit 4acd094e2d6ed972bac99cdb671670f6d8e61721
Merge: 51f61c19 df61741f
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Thu Mar 23 16:44:17 2023 +0300

    Merge branch 'master' into AG-20352-dhcpd-lease-netip-addr

commit 51f61c193fdd31ee675be5598fc361228e407eb3
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Mar 22 18:25:30 2023 +0300

    dhcpd: fix typo

commit 2e64ad55475957925d2a3010c649e0adc5f18c4f
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Mar 22 17:20:31 2023 +0300

    dhcpd: add todo

commit 668d4f62fd
Merge: 0020006e 306c1983
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Mar 22 15:09:38 2023 +0300

    Merge branch 'master' into AG-20352-dhcpd-lease-netip-addr

commit 0020006e89
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Mar 22 15:08:58 2023 +0300

    all: imp code

commit 9a77f79869
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Mar 20 18:13:35 2023 +0300

    dhcpd: add todo

commit 638c4ce2af
Merge: c82b18f1 48431f8b
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Mar 20 13:57:19 2023 +0300

    Merge branch 'master' into AG-20352-dhcpd-lease-netip-addr

commit c82b18f140
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Mar 20 13:56:31 2023 +0300

    all: imp code

commit 27e5181200
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Mar 17 12:14:02 2023 +0300

    dhcpd: imp tests

commit 8e919b0ceb
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Mar 17 11:02:50 2023 +0300

    dhcpd: add tests

commit 78ddefa73a
Merge: c68e85c4 9f7a582d
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Thu Mar 16 14:15:24 2023 +0300

    Merge branch 'master' into AG-20352-dhcpd-lease-netip-addr

commit c68e85c409
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Thu Mar 16 14:14:43 2023 +0300

    all: add tests

commit f338086309
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Mar 15 12:44:06 2023 +0300

    all: dhcpd lease netip addr

internal/aghnet/hostgen.go

@@ -2,51 +2,13 @@ package aghnet
 
 import (
 	"fmt"
-	"net"
+	"net/netip"
-	"strconv"
 	"strings"
 
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/stringutil"
 )
 
-// The maximum lengths of generated hostnames for different IP versions.
-const (
-	ipv4HostnameMaxLen = len("192-168-100-100")
-	ipv6HostnameMaxLen = len("ff80-f076-0000-0000-0000-0000-0000-0010")
-)
-
-// generateIPv4Hostname generates the hostname by IP address version 4.
-func generateIPv4Hostname(ipv4 net.IP) (hostname string) {
-	hnData := make([]byte, 0, ipv4HostnameMaxLen)
-	for i, part := range ipv4 {
-		if i > 0 {
-			hnData = append(hnData, '-')
-		}
-		hnData = strconv.AppendUint(hnData, uint64(part), 10)
-	}
-
-	return string(hnData)
-}
-
-// generateIPv6Hostname generates the hostname by IP address version 6.
-func generateIPv6Hostname(ipv6 net.IP) (hostname string) {
-	hnData := make([]byte, 0, ipv6HostnameMaxLen)
-	for i, partsNum := 0, net.IPv6len/2; i < partsNum; i++ {
-		if i > 0 {
-			hnData = append(hnData, '-')
-		}
-		for _, val := range ipv6[i*2 : i*2+2] {
-			if val < 10 {
-				hnData = append(hnData, '0')
-			}
-			hnData = strconv.AppendUint(hnData, uint64(val), 16)
-		}
-	}
-
-	return string(hnData)
-}
-
 // GenerateHostname generates the hostname from ip.  In case of using IPv4 the
 // result should be like:
 //
@@ -57,12 +19,20 @@ func generateIPv6Hostname(ipv6 net.IP) (hostname string) {
 //	ff80-f076-0000-0000-0000-0000-0000-0010
 //
 // ip must be either an IPv4 or an IPv6.
-func GenerateHostname(ip net.IP) (hostname string) {
+func GenerateHostname(ip netip.Addr) (hostname string) {
-	if ipv4 := ip.To4(); ipv4 != nil {
+	if !ip.IsValid() {
-		return generateIPv4Hostname(ipv4)
+		// TODO(s.chzhen):  Get rid of it.
+		panic("aghnet generate hostname: invalid ip")
 	}
 
-	return generateIPv6Hostname(ip)
+	ip = ip.Unmap()
+	hostname = ip.StringExpanded()
+
+	if ip.Is4() {
+		return strings.Replace(hostname, ".", "-", -1)
+	}
+
+	return strings.Replace(hostname, ":", "-", -1)
 }
 
 // NewDomainNameSet returns nil and error, if list has duplicate or empty

internal/aghnet/hostgen_test.go

@@ -1,7 +1,7 @@
 package aghnet
 
 import (
-	"net"
+	"net/netip"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -12,19 +12,19 @@ func TestGenerateHostName(t *testing.T) {
 		testCases := []struct {
 			name string
 			want string
-			ip   net.IP
+			ip   netip.Addr
 		}{{
 			name: "good_ipv4",
 			want: "127-0-0-1",
-			ip:   net.IP{127, 0, 0, 1},
+			ip:   netip.MustParseAddr("127.0.0.1"),
 		}, {
 			name: "good_ipv6",
 			want: "fe00-0000-0000-0000-0000-0000-0000-0001",
-			ip:   net.ParseIP("fe00::1"),
+			ip:   netip.MustParseAddr("fe00::1"),
 		}, {
 			name: "4to6",
 			want: "1-2-3-4",
-			ip:   net.ParseIP("::ffff:1.2.3.4"),
+			ip:   netip.MustParseAddr("::ffff:1.2.3.4"),
 		}}
 
 		for _, tc := range testCases {
@@ -36,29 +36,6 @@ func TestGenerateHostName(t *testing.T) {
 	})
 
 	t.Run("invalid", func(t *testing.T) {
-		testCases := []struct {
+		assert.Panics(t, func() { GenerateHostname(netip.Addr{}) })
-			name string
-			ip   net.IP
-		}{{
-			name: "bad_ipv4",
-			ip:   net.IP{127, 0, 0, 1, 0},
-		}, {
-			name: "bad_ipv6",
-			ip: net.IP{
-				0xff, 0xff, 0xff, 0xff,
-				0xff, 0xff, 0xff, 0xff,
-				0xff, 0xff, 0xff, 0xff,
-				0xff, 0xff, 0xff,
-			},
-		}, {
-			name: "nil",
-			ip:   nil,
-		}}
-
-		for _, tc := range testCases {
-			t.Run(tc.name, func(t *testing.T) {
-				assert.Panics(t, func() { GenerateHostname(tc.ip) })
-			})
-		}
 	})
 }

internal/dhcpd/db.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net"
+	"net/netip"
 	"os"
 	"time"
 
@@ -32,6 +33,8 @@ func normalizeIP(ip net.IP) net.IP {
 }
 
 // Load lease table from DB
+//
+// TODO(s.chzhen):  Decrease complexity.
 func (s *server) dbLoad() (err error) {
 	dynLeases := []*Lease{}
 	staticLeases := []*Lease{}
@@ -57,14 +60,15 @@ func (s *server) dbLoad() (err error) {
 	for i := range obj {
 		obj[i].IP = normalizeIP(obj[i].IP)
 
-		if !(len(obj[i].IP) == 4 || len(obj[i].IP) == 16) {
+		ip, ok := netip.AddrFromSlice(obj[i].IP)
+		if !ok {
 			log.Info("dhcp: invalid IP: %s", obj[i].IP)
 			continue
 		}
 
 		lease := Lease{
 			HWAddr:   obj[i].HWAddr,
-			IP:       obj[i].IP,
+			IP:       ip,
 			Hostname: obj[i].Hostname,
 			Expiry:   time.Unix(obj[i].Expiry, 0),
 		}
@@ -145,7 +149,7 @@ func (s *server) dbStore() (err error) {
 
 		lease := leaseJSON{
 			HWAddr:   l.HWAddr,
-			IP:       l.IP,
+			IP:       l.IP.AsSlice(),
 			Hostname: l.Hostname,
 			Expiry:   l.Expiry.Unix(),
 		}
@@ -162,7 +166,7 @@ func (s *server) dbStore() (err error) {
 
 			lease := leaseJSON{
 				HWAddr:   l.HWAddr,
-				IP:       l.IP,
+				IP:       l.IP.AsSlice(),
 				Hostname: l.Hostname,
 				Expiry:   l.Expiry.Unix(),
 			}

internal/dhcpd/dhcpd.go

@@ -41,13 +41,16 @@ type Lease struct {
 	// of 1 means that this is a static lease.
 	Expiry time.Time `json:"expires"`
 
-	Hostname string           `json:"hostname"`
+	// Hostname of the client.
-	HWAddr   net.HardwareAddr `json:"mac"`
+	Hostname string `json:"hostname"`
+
+	// HWAddr is the physical hardware address (MAC address).
+	HWAddr net.HardwareAddr `json:"mac"`
 
 	// IP is the IP address leased to the client.
 	//
-	// TODO(a.garipov): Migrate leases.db and use netip.Addr.
+	// TODO(a.garipov): Migrate leases.db.
-	IP net.IP `json:"ip"`
+	IP netip.Addr `json:"ip"`
 }
 
 // Clone returns a deep copy of l.
@@ -60,7 +63,7 @@ func (l *Lease) Clone() (clone *Lease) {
 		Expiry:   l.Expiry,
 		Hostname: l.Hostname,
 		HWAddr:   slices.Clone(l.HWAddr),
-		IP:       slices.Clone(l.IP),
+		IP:       l.IP,
 	}
 }
 

internal/dhcpd/dhcpd_unix_test.go

@@ -48,11 +48,11 @@ func TestDB(t *testing.T) {
 		Expiry:   time.Now().Add(time.Hour),
 		Hostname: "static-1.local",
 		HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 100},
+		IP:       netip.MustParseAddr("192.168.10.100"),
 	}, {
 		Hostname: "static-2.local",
 		HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xBB},
-		IP:       net.IP{192, 168, 10, 101},
+		IP:       netip.MustParseAddr("192.168.10.101"),
 	}}
 
 	srv4, ok := s.srv4.(*v4Server)
@@ -96,7 +96,7 @@ func TestNormalizeLeases(t *testing.T) {
 
 	staticLeases := []*Lease{{
 		HWAddr: net.HardwareAddr{1, 2, 3, 4},
-		IP:     net.IP{0, 2, 3, 4},
+		IP:     netip.MustParseAddr("0.2.3.4"),
 	}, {
 		HWAddr: net.HardwareAddr{2, 2, 3, 4},
 	}}

internal/dhcpd/http_unix.go

@@ -496,18 +496,18 @@ func (s *server) handleDHCPAddStaticLease(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	if l.IP == nil {
+	if !l.IP.IsValid() {
 		aghhttp.Error(r, w, http.StatusBadRequest, "invalid IP")
 
 		return
 	}
 
+	l.IP = l.IP.Unmap()
+
 	var srv DHCPServer
-	if ip4 := l.IP.To4(); ip4 != nil {
+	if l.IP.Is4() {
-		l.IP = ip4
 		srv = s.srv4
 	} else {
-		l.IP = l.IP.To16()
 		srv = s.srv6
 	}
 
@@ -528,27 +528,22 @@ func (s *server) handleDHCPRemoveStaticLease(w http.ResponseWriter, r *http.Requ
 		return
 	}
 
-	if l.IP == nil {
+	if !l.IP.IsValid() {
 		aghhttp.Error(r, w, http.StatusBadRequest, "invalid IP")
 
 		return
 	}
 
-	ip4 := l.IP.To4()
+	l.IP = l.IP.Unmap()
 
-	if ip4 == nil {
+	var srv DHCPServer
-		l.IP = l.IP.To16()
+	if l.IP.Is4() {
-
+		srv = s.srv4
-		err = s.srv6.RemoveStaticLease(l)
+	} else {
-		if err != nil {
+		srv = s.srv6
-			aghhttp.Error(r, w, http.StatusBadRequest, "%s", err)
-		}
-
-		return
 	}
 
-	l.IP = ip4
+	err = srv.RemoveStaticLease(l)
-	err = s.srv4.RemoveStaticLease(l)
 	if err != nil {
 		aghhttp.Error(r, w, http.StatusBadRequest, "%s", err)
 

internal/dhcpd/http_unix_test.go

@@ -0,0 +1,161 @@
+//go:build darwin || freebsd || linux || openbsd
+
+package dhcpd
+
+import (
+	"bytes"
+	"encoding/json"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestServer_handleDHCPStatus(t *testing.T) {
+	const staticName = "static-client"
+
+	staticIP := netip.MustParseAddr("192.168.10.10")
+	staticMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
+
+	staticLease := &Lease{
+		Expiry:   time.Unix(leaseExpireStatic, 0),
+		Hostname: staticName,
+		HWAddr:   staticMAC,
+		IP:       staticIP,
+	}
+
+	s, err := Create(&ServerConfig{
+		Enabled:        true,
+		Conf4:          *defaultV4ServerConf(),
+		WorkDir:        t.TempDir(),
+		DBFilePath:     dbFilename,
+		ConfigModified: func() {},
+	})
+	require.NoError(t, err)
+
+	// checkStatus is a helper that asserts the response of
+	// [*server.handleDHCPStatus].
+	checkStatus := func(t *testing.T, want *dhcpStatusResponse) {
+		w := httptest.NewRecorder()
+		var req *http.Request
+		req, err = http.NewRequest(http.MethodGet, "", nil)
+		require.NoError(t, err)
+
+		b := &bytes.Buffer{}
+		err = json.NewEncoder(b).Encode(&want)
+		require.NoError(t, err)
+
+		s.handleDHCPStatus(w, req)
+		assert.Equal(t, http.StatusOK, w.Code)
+
+		assert.JSONEq(t, b.String(), w.Body.String())
+	}
+
+	// defaultResponse is a helper that returs the response with default
+	// configuration.
+	defaultResponse := func() *dhcpStatusResponse {
+		conf4 := defaultV4ServerConf()
+		conf4.LeaseDuration = 86400
+
+		resp := &dhcpStatusResponse{
+			V4:           *conf4,
+			V6:           V6ServerConf{},
+			Leases:       []*Lease{},
+			StaticLeases: []*Lease{},
+			Enabled:      true,
+		}
+
+		return resp
+	}
+
+	ok := t.Run("status", func(t *testing.T) {
+		resp := defaultResponse()
+
+		checkStatus(t, resp)
+	})
+	require.True(t, ok)
+
+	ok = t.Run("add_static_lease", func(t *testing.T) {
+		w := httptest.NewRecorder()
+
+		b := &bytes.Buffer{}
+		err = json.NewEncoder(b).Encode(staticLease)
+		require.NoError(t, err)
+
+		var r *http.Request
+		r, err = http.NewRequest(http.MethodPost, "", b)
+		require.NoError(t, err)
+
+		s.handleDHCPAddStaticLease(w, r)
+		assert.Equal(t, http.StatusOK, w.Code)
+
+		resp := defaultResponse()
+		resp.StaticLeases = []*Lease{staticLease}
+
+		checkStatus(t, resp)
+	})
+	require.True(t, ok)
+
+	ok = t.Run("add_invalid_lease", func(t *testing.T) {
+		w := httptest.NewRecorder()
+
+		b := &bytes.Buffer{}
+
+		err = json.NewEncoder(b).Encode(&Lease{})
+		require.NoError(t, err)
+
+		var r *http.Request
+		r, err = http.NewRequest(http.MethodPost, "", b)
+		require.NoError(t, err)
+
+		s.handleDHCPAddStaticLease(w, r)
+		assert.Equal(t, http.StatusBadRequest, w.Code)
+	})
+	require.True(t, ok)
+
+	ok = t.Run("remove_static_lease", func(t *testing.T) {
+		w := httptest.NewRecorder()
+
+		b := &bytes.Buffer{}
+		err = json.NewEncoder(b).Encode(staticLease)
+		require.NoError(t, err)
+
+		var r *http.Request
+		r, err = http.NewRequest(http.MethodPost, "", b)
+		require.NoError(t, err)
+
+		s.handleDHCPRemoveStaticLease(w, r)
+		assert.Equal(t, http.StatusOK, w.Code)
+
+		resp := defaultResponse()
+
+		checkStatus(t, resp)
+	})
+	require.True(t, ok)
+
+	ok = t.Run("set_config", func(t *testing.T) {
+		w := httptest.NewRecorder()
+
+		resp := defaultResponse()
+		resp.Enabled = false
+
+		b := &bytes.Buffer{}
+		err = json.NewEncoder(b).Encode(&resp)
+		require.NoError(t, err)
+
+		var r *http.Request
+		r, err = http.NewRequest(http.MethodPost, "", b)
+		require.NoError(t, err)
+
+		s.handleDHCPSetConfig(w, r)
+		assert.Equal(t, http.StatusOK, w.Code)
+
+		checkStatus(t, resp)
+	})
+	require.True(t, ok)
+}

internal/dhcpd/iprange.go

@@ -16,6 +16,8 @@ import (
 //
 // TODO(a.garipov): Perhaps create an optimized version with uint32 for IPv4
 // ranges?  Or use one of uint128 packages?
+//
+// TODO(e.burkov):  Use netip.Addr.
 type ipRange struct {
 	start *big.Int
 	end   *big.Int
@@ -27,8 +29,6 @@ const maxRangeLen = math.MaxUint32
 
 // newIPRange creates a new IP address range.  start must be less than end.  The
 // resulting range must not be greater than maxRangeLen.
-//
-// TODO(e.burkov):  Use netip.Addr.
 func newIPRange(start, end net.IP) (r *ipRange, err error) {
 	defer func() { err = errors.Annotate(err, "invalid ip range: %w") }()
 

internal/dhcpd/v4_unix.go

@@ -98,7 +98,7 @@ func normalizeHostname(hostname string) (norm string, err error) {
 // validHostnameForClient accepts the hostname sent by the client and its IP and
 // returns either a normalized version of that hostname, or a new hostname
 // generated from the IP address, or an empty string.
-func (s *v4Server) validHostnameForClient(cliHostname string, ip net.IP) (hostname string) {
+func (s *v4Server) validHostnameForClient(cliHostname string, ip netip.Addr) (hostname string) {
 	hostname, err := normalizeHostname(cliHostname)
 	if err != nil {
 		log.Info("dhcpv4: %s", err)
@@ -211,9 +211,8 @@ func (s *v4Server) FindMACbyIP(ip netip.Addr) (mac net.HardwareAddr) {
 		return nil
 	}
 
-	netIP := ip.AsSlice()
 	for _, l := range s.leases {
-		if l.IP.Equal(netIP) {
+		if l.IP == ip {
 			if l.Expiry.After(now) || l.IsStatic() {
 				return l.HWAddr
 			}
@@ -247,7 +246,8 @@ func (s *v4Server) rmLeaseByIndex(i int) {
 	s.leases = append(s.leases[:i], s.leases[i+1:]...)
 
 	r := s.conf.ipRange
-	offset, ok := r.offset(l.IP)
+	leaseIP := net.IP(l.IP.AsSlice())
+	offset, ok := r.offset(leaseIP)
 	if ok {
 		s.leasedOffsets.set(offset, false)
 	}
@@ -263,7 +263,7 @@ func (s *v4Server) rmDynamicLease(lease *Lease) (err error) {
 	for i, l := range s.leases {
 		isStatic := l.IsStatic()
 
-		if bytes.Equal(l.HWAddr, lease.HWAddr) || l.IP.Equal(lease.IP) {
+		if bytes.Equal(l.HWAddr, lease.HWAddr) || l.IP == lease.IP {
 			if isStatic {
 				return errors.Error("static lease already exists")
 			}
@@ -291,13 +291,13 @@ const ErrDupHostname = errors.Error("hostname is not unique")
 // addLease adds a dynamic or static lease.
 func (s *v4Server) addLease(l *Lease) (err error) {
 	r := s.conf.ipRange
-	offset, inOffset := r.offset(l.IP)
+	leaseIP := net.IP(l.IP.AsSlice())
+	offset, inOffset := r.offset(leaseIP)
 
 	if l.IsStatic() {
 		// TODO(a.garipov, d.seregin): Subnet can be nil when dhcp server is
 		// disabled.
-		addr := netip.AddrFrom4(*(*[4]byte)(l.IP.To4()))
+		if sn := s.conf.subnet; !sn.Contains(l.IP) {
-		if sn := s.conf.subnet; !sn.Contains(addr) {
 			return fmt.Errorf("subnet %s does not contain the ip %q", sn, l.IP)
 		}
 	} else if !inOffset {
@@ -325,7 +325,7 @@ func (s *v4Server) rmLease(lease *Lease) (err error) {
 	}
 
 	for i, l := range s.leases {
-		if l.IP.Equal(lease.IP) {
+		if l.IP == lease.IP {
 			if !bytes.Equal(l.HWAddr, lease.HWAddr) || l.Hostname != lease.Hostname {
 				return fmt.Errorf("lease for ip %s is different: %+v", lease.IP, l)
 			}
@@ -352,10 +352,11 @@ func (s *v4Server) AddStaticLease(l *Lease) (err error) {
 		return ErrUnconfigured
 	}
 
-	ip := l.IP.To4()
+	l.IP = l.IP.Unmap()
-	if ip == nil {
+
+	if !l.IP.Is4() {
 		return fmt.Errorf("invalid ip %q, only ipv4 is supported", l.IP)
-	} else if gwIP := s.conf.GatewayIP; gwIP == netip.AddrFrom4(*(*[4]byte)(ip)) {
+	} else if gwIP := s.conf.GatewayIP; gwIP == l.IP {
 		return fmt.Errorf("can't assign the gateway IP %s to the lease", gwIP)
 	}
 
@@ -396,7 +397,7 @@ func (s *v4Server) AddStaticLease(l *Lease) (err error) {
 		if err != nil {
 			err = fmt.Errorf(
 				"removing dynamic leases for %s (%s): %w",
-				ip,
+				l.IP,
 				l.HWAddr,
 				err,
 			)
@@ -406,7 +407,7 @@ func (s *v4Server) AddStaticLease(l *Lease) (err error) {
 
 		err = s.addLease(l)
 		if err != nil {
-			err = fmt.Errorf("adding static lease for %s (%s): %w", ip, l.HWAddr, err)
+			err = fmt.Errorf("adding static lease for %s (%s): %w", l.IP, l.HWAddr, err)
 
 			return
 		}
@@ -429,7 +430,7 @@ func (s *v4Server) RemoveStaticLease(l *Lease) (err error) {
 		return ErrUnconfigured
 	}
 
-	if len(l.IP) != 4 {
+	if !l.IP.Is4() {
 		return fmt.Errorf("invalid IP")
 	}
 
@@ -542,8 +543,8 @@ func (s *v4Server) findExpiredLease() int {
 func (s *v4Server) reserveLease(mac net.HardwareAddr) (l *Lease, err error) {
 	l = &Lease{HWAddr: slices.Clone(mac)}
 
-	l.IP = s.nextIP()
+	nextIP := s.nextIP()
-	if l.IP == nil {
+	if nextIP == nil {
 		i := s.findExpiredLease()
 		if i < 0 {
 			return nil, nil
@@ -554,6 +555,13 @@ func (s *v4Server) reserveLease(mac net.HardwareAddr) (l *Lease, err error) {
 		return s.leases[i], nil
 	}
 
+	netIP, ok := netip.AddrFromSlice(nextIP)
+	if !ok {
+		return nil, errors.Error("invalid ip")
+	}
+
+	l.IP = netIP
+
 	err = s.addLease(l)
 	if err != nil {
 		return nil, err
@@ -603,7 +611,8 @@ func (s *v4Server) allocateLease(mac net.HardwareAddr) (l *Lease, err error) {
 			return nil, nil
 		}
 
-		if s.addrAvailable(l.IP) {
+		leaseIP := l.IP.AsSlice()
+		if s.addrAvailable(leaseIP) {
 			return l, nil
 		}
 
@@ -623,8 +632,9 @@ func (s *v4Server) handleDiscover(req, resp *dhcpv4.DHCPv4) (l *Lease, err error
 	l = s.findLease(mac)
 	if l != nil {
 		reqIP := req.RequestedIPAddress()
-		if len(reqIP) != 0 && !reqIP.Equal(l.IP) {
+		leaseIP := net.IP(l.IP.AsSlice())
-			log.Debug("dhcpv4: different RequestedIP: %s != %s", reqIP, l.IP)
+		if len(reqIP) != 0 && !reqIP.Equal(leaseIP) {
+			log.Debug("dhcpv4: different RequestedIP: %s != %s", reqIP, leaseIP)
 		}
 
 		resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeOffer))
@@ -674,12 +684,19 @@ func (s *v4Server) checkLease(mac net.HardwareAddr, ip net.IP) (lease *Lease, mi
 	s.leasesLock.Lock()
 	defer s.leasesLock.Unlock()
 
+	netIP, ok := netip.AddrFromSlice(ip)
+	if !ok {
+		log.Info("check lease: invalid IP: %s", ip)
+
+		return nil, false
+	}
+
 	for _, l := range s.leases {
 		if !bytes.Equal(l.HWAddr, mac) {
 			continue
 		}
 
-		if l.IP.Equal(ip) {
+		if l.IP == netIP {
 			return l, false
 		}
 
@@ -878,9 +895,16 @@ func (s *v4Server) handleDecline(req, resp *dhcpv4.DHCPv4) (err error) {
 		reqIP = req.ClientIPAddr
 	}
 
+	netIP, ok := netip.AddrFromSlice(reqIP)
+	if !ok {
+		log.Info("dhcpv4: invalid IP: %s", reqIP)
+
+		return nil
+	}
+
 	var oldLease *Lease
 	for _, l := range s.leases {
-		if bytes.Equal(l.HWAddr, mac) && l.IP.Equal(reqIP) {
+		if bytes.Equal(l.HWAddr, mac) && l.IP == netIP {
 			oldLease = l
 
 			break
@@ -920,8 +944,7 @@ func (s *v4Server) handleDecline(req, resp *dhcpv4.DHCPv4) (err error) {
 
 	log.Info("dhcpv4: changed ip from %s to %s for %s", reqIP, newLease.IP, mac)
 
-	resp.YourIPAddr = make([]byte, 4)
+	resp.YourIPAddr = net.IP(newLease.IP.AsSlice())
-	copy(resp.YourIPAddr, newLease.IP)
 
 	resp.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeAck))
 
@@ -944,8 +967,15 @@ func (s *v4Server) handleRelease(req, resp *dhcpv4.DHCPv4) (err error) {
 	s.leasesLock.Lock()
 	defer s.leasesLock.Unlock()
 
+	netIP, ok := netip.AddrFromSlice(reqIP)
+	if !ok {
+		log.Info("dhcpv4: invalid IP: %s", reqIP)
+
+		return nil
+	}
+
 	for _, l := range s.leases {
-		if !bytes.Equal(l.HWAddr, mac) || !l.IP.Equal(reqIP) {
+		if !bytes.Equal(l.HWAddr, mac) || l.IP != netIP {
 			continue
 		}
 
@@ -1018,7 +1048,7 @@ func (s *v4Server) handle(req, resp *dhcpv4.DHCPv4) int {
 	}
 
 	if l != nil {
-		resp.YourIPAddr = slices.Clone(l.IP)
+		resp.YourIPAddr = net.IP(l.IP.AsSlice())
 	}
 
 	s.updateOptions(req, resp)

internal/dhcpd/v4_unix_test.go

@@ -62,7 +62,7 @@ func TestV4Server_leasing(t *testing.T) {
 		anotherName = "another-client"
 	)
 
-	staticIP := net.IP{192, 168, 10, 10}
+	staticIP := netip.MustParseAddr("192.168.10.10")
 	anotherIP := DefaultRangeStart
 	staticMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
 	anotherMAC := net.HardwareAddr{0xBB, 0xBB, 0xBB, 0xBB, 0xBB, 0xBB}
@@ -83,7 +83,7 @@ func TestV4Server_leasing(t *testing.T) {
 				Expiry:   time.Unix(leaseExpireStatic, 0),
 				Hostname: staticName,
 				HWAddr:   anotherMAC,
-				IP:       anotherIP.AsSlice(),
+				IP:       anotherIP,
 			})
 			assert.ErrorIs(t, err, ErrDupHostname)
 		})
@@ -97,7 +97,7 @@ func TestV4Server_leasing(t *testing.T) {
 				Expiry:   time.Unix(leaseExpireStatic, 0),
 				Hostname: anotherName,
 				HWAddr:   staticMAC,
-				IP:       anotherIP.AsSlice(),
+				IP:       anotherIP,
 			})
 			testutil.AssertErrorMsg(t, wantErrMsg, err)
 		})
@@ -124,13 +124,14 @@ func TestV4Server_leasing(t *testing.T) {
 		discoverAnOffer := func(
 			t *testing.T,
 			name string,
-			ip net.IP,
+			netIP netip.Addr,
 			mac net.HardwareAddr,
 		) (resp *dhcpv4.DHCPv4) {
 			testutil.CleanupAndRequireSuccess(t, func() (err error) {
 				return s.ResetLeases(s.GetLeases(LeasesStatic))
 			})
 
+			ip := net.IP(netIP.AsSlice())
 			req, err := dhcpv4.NewDiscovery(
 				mac,
 				dhcpv4.WithOption(dhcpv4.OptHostName(name)),
@@ -151,7 +152,7 @@ func TestV4Server_leasing(t *testing.T) {
 		}
 
 		t.Run("same_name", func(t *testing.T) {
-			resp := discoverAnOffer(t, staticName, anotherIP.AsSlice(), anotherMAC)
+			resp := discoverAnOffer(t, staticName, anotherIP, anotherMAC)
 
 			req, err := dhcpv4.NewRequestFromOffer(resp, dhcpv4.WithOption(
 				dhcpv4.OptHostName(staticName),
@@ -161,11 +162,15 @@ func TestV4Server_leasing(t *testing.T) {
 			res := s4.handle(req, resp)
 			require.Positive(t, res)
 
-			assert.Equal(t, aghnet.GenerateHostname(resp.YourIPAddr), resp.HostName())
+			var netIP netip.Addr
+			netIP, ok = netip.AddrFromSlice(resp.YourIPAddr)
+			require.True(t, ok)
+
+			assert.Equal(t, aghnet.GenerateHostname(netIP), resp.HostName())
 		})
 
 		t.Run("same_mac", func(t *testing.T) {
-			resp := discoverAnOffer(t, anotherName, anotherIP.AsSlice(), staticMAC)
+			resp := discoverAnOffer(t, anotherName, anotherIP, staticMAC)
 
 			req, err := dhcpv4.NewRequestFromOffer(resp, dhcpv4.WithOption(
 				dhcpv4.OptHostName(anotherName),
@@ -179,7 +184,8 @@ func TestV4Server_leasing(t *testing.T) {
 			require.Len(t, fqdnOptData, 3+len(staticName))
 			assert.Equal(t, []uint8(staticName), fqdnOptData[3:])
 
-			assert.Equal(t, staticIP, resp.YourIPAddr)
+			ip := net.IP(staticIP.AsSlice())
+			assert.Equal(t, ip, resp.YourIPAddr)
 		})
 
 		t.Run("same_ip", func(t *testing.T) {
@@ -212,7 +218,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "success.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-			IP:       net.IP{192, 168, 10, 150},
+			IP:       netip.MustParseAddr("192.168.10.150"),
 		},
 		name:       "success",
 		wantErrMsg: "",
@@ -220,7 +226,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "probably-router.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-			IP:       DefaultGatewayIP.AsSlice(),
+			IP:       DefaultGatewayIP,
 		},
 		name: "with_gateway_ip",
 		wantErrMsg: "dhcpv4: adding static lease: " +
@@ -229,7 +235,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "ip6.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-			IP:       net.ParseIP("ffff::1"),
+			IP:       netip.MustParseAddr("ffff::1"),
 		},
 		name: "ipv6",
 		wantErrMsg: `dhcpv4: adding static lease: ` +
@@ -238,7 +244,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "bad-mac.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA},
-			IP:       net.IP{192, 168, 10, 150},
+			IP:       netip.MustParseAddr("192.168.10.150"),
 		},
 		name: "bad_mac",
 		wantErrMsg: `dhcpv4: adding static lease: bad mac address "aa:aa": ` +
@@ -247,7 +253,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "bad-lbl-.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-			IP:       net.IP{192, 168, 10, 150},
+			IP:       netip.MustParseAddr("192.168.10.150"),
 		},
 		name: "bad_hostname",
 		wantErrMsg: `dhcpv4: adding static lease: validating hostname: ` +
@@ -289,11 +295,11 @@ func TestV4_AddReplace(t *testing.T) {
 	dynLeases := []Lease{{
 		Hostname: "dynamic-1.local",
 		HWAddr:   net.HardwareAddr{0x11, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 150},
+		IP:       netip.MustParseAddr("192.168.10.150"),
 	}, {
 		Hostname: "dynamic-2.local",
 		HWAddr:   net.HardwareAddr{0x22, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 151},
+		IP:       netip.MustParseAddr("192.168.10.151"),
 	}}
 
 	for i := range dynLeases {
@@ -304,11 +310,11 @@ func TestV4_AddReplace(t *testing.T) {
 	stLeases := []*Lease{{
 		Hostname: "static-1.local",
 		HWAddr:   net.HardwareAddr{0x33, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 150},
+		IP:       netip.MustParseAddr("192.168.10.150"),
 	}, {
 		Hostname: "static-2.local",
 		HWAddr:   net.HardwareAddr{0x22, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 152},
+		IP:       netip.MustParseAddr("192.168.10.152"),
 	}}
 
 	for _, l := range stLeases {
@@ -320,7 +326,7 @@ func TestV4_AddReplace(t *testing.T) {
 	require.Len(t, ls, 2)
 
 	for i, l := range ls {
-		assert.True(t, stLeases[i].IP.Equal(l.IP))
+		assert.Equal(t, stLeases[i].IP, l.IP)
 		assert.Equal(t, stLeases[i].HWAddr, l.HWAddr)
 		assert.True(t, l.IsStatic())
 	}
@@ -513,7 +519,7 @@ func TestV4StaticLease_Get(t *testing.T) {
 	l := &Lease{
 		Hostname: "static-1.local",
 		HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		IP:       net.IP{192, 168, 10, 150},
+		IP:       netip.MustParseAddr("192.168.10.150"),
 	}
 	err := s.AddStaticLease(l)
 	require.NoError(t, err)
@@ -539,7 +545,9 @@ func TestV4StaticLease_Get(t *testing.T) {
 	t.Run("offer", func(t *testing.T) {
 		assert.Equal(t, dhcpv4.MessageTypeOffer, resp.MessageType())
 		assert.Equal(t, mac, resp.ClientHWAddr)
-		assert.True(t, l.IP.Equal(resp.YourIPAddr))
+
+		ip := net.IP(l.IP.AsSlice())
+		assert.True(t, ip.Equal(resp.YourIPAddr))
 
 		assert.True(t, resp.Router()[0].Equal(s.conf.GatewayIP.AsSlice()))
 		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
@@ -564,7 +572,9 @@ func TestV4StaticLease_Get(t *testing.T) {
 	t.Run("ack", func(t *testing.T) {
 		assert.Equal(t, dhcpv4.MessageTypeAck, resp.MessageType())
 		assert.Equal(t, mac, resp.ClientHWAddr)
-		assert.True(t, l.IP.Equal(resp.YourIPAddr))
+
+		ip := net.IP(l.IP.AsSlice())
+		assert.True(t, ip.Equal(resp.YourIPAddr))
 
 		assert.True(t, resp.Router()[0].Equal(s.conf.GatewayIP.AsSlice()))
 		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
@@ -583,7 +593,7 @@ func TestV4StaticLease_Get(t *testing.T) {
 		ls := s.GetLeases(LeasesStatic)
 		require.Len(t, ls, 1)
 
-		assert.True(t, l.IP.Equal(ls[0].IP))
+		assert.Equal(t, l.IP, ls[0].IP)
 		assert.Equal(t, mac, ls[0].HWAddr)
 	})
 }
@@ -681,7 +691,8 @@ func TestV4DynamicLease_Get(t *testing.T) {
 		ls := s.GetLeases(LeasesDynamic)
 		require.Len(t, ls, 1)
 
-		assert.True(t, net.IP{192, 168, 10, 100}.Equal(ls[0].IP))
+		ip := netip.MustParseAddr("192.168.10.100")
+		assert.Equal(t, ip, ls[0].IP)
 		assert.Equal(t, mac, ls[0].HWAddr)
 	})
 }
@@ -862,3 +873,143 @@ func TestV4Server_Send(t *testing.T) {
 		assert.True(t, resp.IsBroadcast())
 	})
 }
+
+func TestV4Server_FindMACbyIP(t *testing.T) {
+	const (
+		staticName  = "static-client"
+		anotherName = "another-client"
+	)
+
+	staticIP := netip.MustParseAddr("192.168.10.10")
+	staticMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
+
+	anotherIP := netip.MustParseAddr("192.168.100.100")
+	anotherMAC := net.HardwareAddr{0xBB, 0xBB, 0xBB, 0xBB, 0xBB, 0xBB}
+
+	s := &v4Server{
+		leases: []*Lease{{
+			Expiry:   time.Unix(leaseExpireStatic, 0),
+			Hostname: staticName,
+			HWAddr:   staticMAC,
+			IP:       staticIP,
+		}, {
+			Expiry:   time.Unix(10, 0),
+			Hostname: anotherName,
+			HWAddr:   anotherMAC,
+			IP:       anotherIP,
+		}},
+	}
+
+	testCases := []struct {
+		want net.HardwareAddr
+		ip   netip.Addr
+		name string
+	}{{
+		name: "basic",
+		ip:   staticIP,
+		want: staticMAC,
+	}, {
+		name: "not_found",
+		ip:   netip.MustParseAddr("1.2.3.4"),
+		want: nil,
+	}, {
+		name: "expired",
+		ip:   anotherIP,
+		want: nil,
+	}, {
+		name: "v6",
+		ip:   netip.MustParseAddr("ffff::1"),
+		want: nil,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mac := s.FindMACbyIP(tc.ip)
+
+			require.Equal(t, tc.want, mac)
+		})
+	}
+}
+
+func TestV4Server_handleDecline(t *testing.T) {
+	const (
+		dynamicName = "dynamic-client"
+		anotherName = "another-client"
+	)
+
+	dynamicIP := netip.MustParseAddr("192.168.10.200")
+	dynamicMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
+
+	s := defaultSrv(t)
+
+	s4, ok := s.(*v4Server)
+	require.True(t, ok)
+
+	s4.leases = []*Lease{{
+		Hostname: dynamicName,
+		HWAddr:   dynamicMAC,
+		IP:       dynamicIP,
+	}}
+
+	req, err := dhcpv4.New(
+		dhcpv4.WithOption(dhcpv4.OptRequestedIPAddress(net.IP(dynamicIP.AsSlice()))),
+	)
+	require.NoError(t, err)
+
+	req.ClientIPAddr = net.IP(dynamicIP.AsSlice())
+	req.ClientHWAddr = dynamicMAC
+
+	resp := &dhcpv4.DHCPv4{}
+	err = s4.handleDecline(req, resp)
+	require.NoError(t, err)
+
+	wantResp := &dhcpv4.DHCPv4{
+		YourIPAddr: net.IP(s4.conf.RangeStart.AsSlice()),
+		Options: dhcpv4.OptionsFromList(
+			dhcpv4.OptMessageType(dhcpv4.MessageTypeAck),
+		),
+	}
+
+	require.Equal(t, wantResp, resp)
+}
+
+func TestV4Server_handleRelease(t *testing.T) {
+	const (
+		dynamicName = "dymamic-client"
+		anotherName = "another-client"
+	)
+
+	dynamicIP := netip.MustParseAddr("192.168.10.200")
+	dynamicMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
+
+	s := defaultSrv(t)
+
+	s4, ok := s.(*v4Server)
+	require.True(t, ok)
+
+	s4.leases = []*Lease{{
+		Hostname: dynamicName,
+		HWAddr:   dynamicMAC,
+		IP:       dynamicIP,
+	}}
+
+	req, err := dhcpv4.New(
+		dhcpv4.WithOption(dhcpv4.OptRequestedIPAddress(net.IP(dynamicIP.AsSlice()))),
+	)
+	require.NoError(t, err)
+
+	req.ClientIPAddr = net.IP(dynamicIP.AsSlice())
+	req.ClientHWAddr = dynamicMAC
+
+	resp := &dhcpv4.DHCPv4{}
+	err = s4.handleRelease(req, resp)
+	require.NoError(t, err)
+
+	wantResp := &dhcpv4.DHCPv4{
+		Options: dhcpv4.OptionsFromList(
+			dhcpv4.OptMessageType(dhcpv4.MessageTypeAck),
+		),
+	}
+
+	require.Equal(t, wantResp, resp)
+}

internal/dhcpd/v6_unix.go

@@ -61,13 +61,13 @@ func ip6InRange(start, ip net.IP) bool {
 
 // ResetLeases resets leases.
 func (s *v6Server) ResetLeases(leases []*Lease) (err error) {
-	defer func() { err = errors.Annotate(err, "dhcpv4: %w") }()
+	defer func() { err = errors.Annotate(err, "dhcpv6: %w") }()
 
 	s.leases = nil
 	for _, l := range leases {
-
+		ip := net.IP(l.IP.AsSlice())
 		if l.Expiry.Unix() != leaseExpireStatic &&
-			!ip6InRange(s.conf.ipStart, l.IP) {
+			!ip6InRange(s.conf.ipStart, ip) {
 
 			log.Debug("dhcpv6: skipping a lease with IP %v: not within current IP range", l.IP)
 
@@ -119,9 +119,8 @@ func (s *v6Server) FindMACbyIP(ip netip.Addr) (mac net.HardwareAddr) {
 		return nil
 	}
 
-	netIP := ip.AsSlice()
 	for _, l := range s.leases {
-		if l.IP.Equal(netIP) {
+		if l.IP == ip {
 			if l.Expiry.After(now) || l.IsStatic() {
 				return l.HWAddr
 			}
@@ -133,7 +132,8 @@ func (s *v6Server) FindMACbyIP(ip netip.Addr) (mac net.HardwareAddr) {
 
 // Remove (swap) lease by index
 func (s *v6Server) leaseRemoveSwapByIndex(i int) {
-	s.ipAddrs[s.leases[i].IP[15]] = 0
+	leaseIP := s.leases[i].IP.As16()
+	s.ipAddrs[leaseIP[15]] = 0
 	log.Debug("dhcpv6: removed lease %s", s.leases[i].HWAddr)
 
 	n := len(s.leases)
@@ -162,7 +162,7 @@ func (s *v6Server) rmDynamicLease(lease *Lease) (err error) {
 			l = s.leases[i]
 		}
 
-		if net.IP.Equal(l.IP, lease.IP) {
+		if l.IP == lease.IP {
 			if l.Expiry.Unix() == leaseExpireStatic {
 				return fmt.Errorf("static lease already exists")
 			}
@@ -178,7 +178,7 @@ func (s *v6Server) rmDynamicLease(lease *Lease) (err error) {
 func (s *v6Server) AddStaticLease(l *Lease) (err error) {
 	defer func() { err = errors.Annotate(err, "dhcpv6: %w") }()
 
-	if len(l.IP) != net.IPv6len {
+	if !l.IP.Is6() {
 		return fmt.Errorf("invalid IP")
 	}
 
@@ -210,7 +210,7 @@ func (s *v6Server) AddStaticLease(l *Lease) (err error) {
 func (s *v6Server) RemoveStaticLease(l *Lease) (err error) {
 	defer func() { err = errors.Annotate(err, "dhcpv6: %w") }()
 
-	if len(l.IP) != 16 {
+	if !l.IP.Is6() {
 		return fmt.Errorf("invalid IP")
 	}
 
@@ -234,14 +234,15 @@ func (s *v6Server) RemoveStaticLease(l *Lease) (err error) {
 // Add a lease
 func (s *v6Server) addLease(l *Lease) {
 	s.leases = append(s.leases, l)
-	s.ipAddrs[l.IP[15]] = 1
+	ip := l.IP.As16()
+	s.ipAddrs[ip[15]] = 1
 	log.Debug("dhcpv6: added lease %s <-> %s", l.IP, l.HWAddr)
 }
 
 // Remove a lease with the same properties
 func (s *v6Server) rmLease(lease *Lease) (err error) {
 	for i, l := range s.leases {
-		if net.IP.Equal(l.IP, lease.IP) {
+		if l.IP == lease.IP {
 			if !bytes.Equal(l.HWAddr, lease.HWAddr) ||
 				l.Hostname != lease.Hostname {
 				return fmt.Errorf("lease not found")
@@ -308,18 +309,27 @@ func (s *v6Server) reserveLease(mac net.HardwareAddr) *Lease {
 	s.leasesLock.Lock()
 	defer s.leasesLock.Unlock()
 
-	copy(l.IP, s.conf.ipStart)
+	ip := s.findFreeIP()
-	l.IP = s.findFreeIP()
+	if ip == nil {
-	if l.IP == nil {
 		i := s.findExpiredLease()
 		if i < 0 {
 			return nil
 		}
+
 		copy(s.leases[i].HWAddr, mac)
+
 		return s.leases[i]
 	}
 
+	netIP, ok := netip.AddrFromSlice(ip)
+	if !ok {
+		return nil
+	}
+
+	l.IP = netIP
+
 	s.addLease(&l)
+
 	return &l
 }
 
@@ -388,7 +398,8 @@ func (s *v6Server) checkIA(msg *dhcpv6.Message, lease *Lease) error {
 			return fmt.Errorf("no IANA.Addr option in %s", msg.Type().String())
 		}
 
-		if !oiaAddr.IPv6Addr.Equal(lease.IP) {
+		leaseIP := net.IP(lease.IP.AsSlice())
+		if !oiaAddr.IPv6Addr.Equal(leaseIP) {
 			return fmt.Errorf("invalid IANA.Addr option in %s", msg.Type().String())
 		}
 	}
@@ -475,7 +486,7 @@ func (s *v6Server) process(msg *dhcpv6.Message, req, resp dhcpv6.DHCPv6) bool {
 		copy(oia.IaId[:], []byte(valueIAID))
 	}
 	oiaAddr := &dhcpv6.OptIAAddress{
-		IPv6Addr:          lease.IP,
+		IPv6Addr:          net.IP(lease.IP.AsSlice()),
 		PreferredLifetime: lifetime,
 		ValidLifetime:     lifetime,
 	}

internal/dhcpd/v6_unix_test.go

@@ -4,7 +4,9 @@ package dhcpd
 
 import (
 	"net"
+	"net/netip"
 	"testing"
+	"time"
 
 	"github.com/insomniacslk/dhcp/dhcpv6"
 	"github.com/insomniacslk/dhcp/iana"
@@ -27,7 +29,7 @@ func TestV6_AddRemove_static(t *testing.T) {
 
 	// Add static lease.
 	l := &Lease{
-		IP:     net.ParseIP("2001::1"),
+		IP:     netip.MustParseAddr("2001::1"),
 		HWAddr: net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}
 	err = s.AddStaticLease(l)
@@ -46,7 +48,7 @@ func TestV6_AddRemove_static(t *testing.T) {
 
 	// Try to remove non-existent static lease.
 	err = s.RemoveStaticLease(&Lease{
-		IP:     net.ParseIP("2001::2"),
+		IP:     netip.MustParseAddr("2001::2"),
 		HWAddr: l.HWAddr,
 	})
 	require.Error(t, err)
@@ -71,10 +73,10 @@ func TestV6_AddReplace(t *testing.T) {
 
 	// Add dynamic leases.
 	dynLeases := []*Lease{{
-		IP:     net.ParseIP("2001::1"),
+		IP:     netip.MustParseAddr("2001::1"),
 		HWAddr: net.HardwareAddr{0x11, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}, {
-		IP:     net.ParseIP("2001::2"),
+		IP:     netip.MustParseAddr("2001::2"),
 		HWAddr: net.HardwareAddr{0x22, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}}
 
@@ -83,10 +85,10 @@ func TestV6_AddReplace(t *testing.T) {
 	}
 
 	stLeases := []*Lease{{
-		IP:     net.ParseIP("2001::1"),
+		IP:     netip.MustParseAddr("2001::1"),
 		HWAddr: net.HardwareAddr{0x33, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}, {
-		IP:     net.ParseIP("2001::3"),
+		IP:     netip.MustParseAddr("2001::3"),
 		HWAddr: net.HardwareAddr{0x22, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}}
 
@@ -99,7 +101,7 @@ func TestV6_AddReplace(t *testing.T) {
 	require.Len(t, ls, 2)
 
 	for i, l := range ls {
-		assert.True(t, stLeases[i].IP.Equal(l.IP))
+		assert.Equal(t, stLeases[i].IP, l.IP)
 		assert.Equal(t, stLeases[i].HWAddr, l.HWAddr)
 		assert.EqualValues(t, leaseExpireStatic, l.Expiry.Unix())
 	}
@@ -126,7 +128,7 @@ func TestV6GetLease(t *testing.T) {
 	}
 
 	l := &Lease{
-		IP:     net.ParseIP("2001::1"),
+		IP:     netip.MustParseAddr("2001::1"),
 		HWAddr: net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 	}
 	err = s.AddStaticLease(l)
@@ -158,7 +160,8 @@ func TestV6GetLease(t *testing.T) {
 		oia = resp.Options.OneIANA()
 		oiaAddr = oia.Options.OneAddress()
 
-		assert.Equal(t, l.IP, oiaAddr.IPv6Addr)
+		ip := net.IP(l.IP.AsSlice())
+		assert.Equal(t, ip, oiaAddr.IPv6Addr)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), oiaAddr.ValidLifetime.Seconds())
 	})
 
@@ -182,7 +185,8 @@ func TestV6GetLease(t *testing.T) {
 		oia = resp.Options.OneIANA()
 		oiaAddr = oia.Options.OneAddress()
 
-		assert.Equal(t, l.IP, oiaAddr.IPv6Addr)
+		ip := net.IP(l.IP.AsSlice())
+		assert.Equal(t, ip, oiaAddr.IPv6Addr)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), oiaAddr.ValidLifetime.Seconds())
 	})
 
@@ -308,3 +312,72 @@ func TestIP6InRange(t *testing.T) {
 		})
 	}
 }
+
+func TestV6_FindMACbyIP(t *testing.T) {
+	const (
+		staticName  = "static-client"
+		anotherName = "another-client"
+	)
+
+	staticIP := netip.MustParseAddr("2001::1")
+	staticMAC := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
+
+	anotherIP := netip.MustParseAddr("2001::100")
+	anotherMAC := net.HardwareAddr{0xBB, 0xBB, 0xBB, 0xBB, 0xBB, 0xBB}
+
+	s := &v6Server{
+		leases: []*Lease{{
+			Expiry:   time.Unix(leaseExpireStatic, 0),
+			Hostname: staticName,
+			HWAddr:   staticMAC,
+			IP:       staticIP,
+		}, {
+			Expiry:   time.Unix(10, 0),
+			Hostname: anotherName,
+			HWAddr:   anotherMAC,
+			IP:       anotherIP,
+		}},
+	}
+
+	s.leases = []*Lease{{
+		Expiry:   time.Unix(leaseExpireStatic, 0),
+		Hostname: staticName,
+		HWAddr:   staticMAC,
+		IP:       staticIP,
+	}, {
+		Expiry:   time.Unix(10, 0),
+		Hostname: anotherName,
+		HWAddr:   anotherMAC,
+		IP:       anotherIP,
+	}}
+
+	testCases := []struct {
+		want net.HardwareAddr
+		ip   netip.Addr
+		name string
+	}{{
+		name: "basic",
+		ip:   staticIP,
+		want: staticMAC,
+	}, {
+		name: "not_found",
+		ip:   netip.MustParseAddr("ffff::1"),
+		want: nil,
+	}, {
+		name: "expired",
+		ip:   anotherIP,
+		want: nil,
+	}, {
+		name: "v4",
+		ip:   netip.MustParseAddr("1.2.3.4"),
+		want: nil,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mac := s.FindMACbyIP(tc.ip)
+
+			require.Equal(t, tc.want, mac)
+		})
+	}
+}

internal/dnsforward/dns.go

@@ -243,17 +243,16 @@ func (s *Server) onDHCPLeaseChanged(flags int) {
 		lowhost := strings.ToLower(l.Hostname + "." + s.localDomainSuffix)
 
 		// Assume that we only process IPv4 now.
-		//
+		if !l.IP.Is4() {
-		// TODO(a.garipov):  Remove once we switch to netip.Addr more fully.
+			log.Debug("dnsforward: skipping invalid ip from dhcp: bad ipv4 net.IP %v", l.IP)
-		ip, err := netutil.IPToAddr(l.IP, netutil.AddrFamilyIPv4)
-		if err != nil {
-			log.Debug("dnsforward: skipping invalid ip %v from dhcp: %s", l.IP, err)
 
 			continue
 		}
 
-		ipToHost[ip] = lowhost
+		leaseIP := l.IP
-		hostToIP[lowhost] = ip
+
+		ipToHost[leaseIP] = lowhost
+		hostToIP[lowhost] = leaseIP
 	}
 
 	s.setTableHostToIP(hostToIP)

internal/dnsforward/dnsforward_test.go

@@ -1073,7 +1073,7 @@ var testDHCP = &dhcpd.MockInterface{
 	OnEnabled: func() (ok bool) { return true },
 	OnLeases: func(flags dhcpd.GetLeasesFlags) (leases []*dhcpd.Lease) {
 		return []*dhcpd.Lease{{
-			IP:       net.IP{192, 168, 12, 34},
+			IP:       netip.MustParseAddr("192.168.12.34"),
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
 			Hostname: "myhost",
 		}}

internal/home/clients.go

@@ -19,7 +19,6 @@ import (
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
-	"github.com/AdguardTeam/golibs/netutil"
 	"github.com/AdguardTeam/golibs/stringutil"
 	"golang.org/x/exp/maps"
 	"golang.org/x/exp/slices"
@@ -859,15 +858,7 @@ func (clients *clientsContainer) updateFromDHCP(add bool) {
 			continue
 		}
 
-		// TODO(a.garipov):  Remove once we switch to netip.Addr more fully.
+		ok := clients.addHostLocked(l.IP, l.Hostname, ClientSourceDHCP)
-		ipAddr, err := netutil.IPToAddrNoMapped(l.IP)
-		if err != nil {
-			log.Error("clients: bad client ip %v from dhcp: %s", l.IP, err)
-
-			continue
-		}
-
-		ok := clients.addHostLocked(ipAddr, l.Hostname, ClientSourceDHCP)
 		if ok {
 			n++
 		}

internal/home/clients_test.go

@@ -275,7 +275,7 @@ func TestClientsAddExisting(t *testing.T) {
 			t.Skip("skipping dhcp test on windows")
 		}
 
-		ip := net.IP{1, 2, 3, 4}
+		ip := netip.MustParseAddr("1.2.3.4")
 
 		// First, init a DHCP server with a single static lease.
 		config := &dhcpd.ServerConfig{