Pull request: Migrate to netip.Addr vol.1

Merge in DNS/adguard-home from 2926-lla-v6 to master

Updates #2926.
Updates #5035.

Squashed commit of the following:

commit 2e770d4b6d4e1ec3f7762f2f2466662983bf146c
Merge: 25c1afc5 893358ea
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Oct 14 15:14:56 2022 +0300

    Merge branch 'master' into 2926-lla-v6

commit 25c1afc5f0a5027fafac9dee77618886aefee29c
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Oct 13 18:24:20 2022 +0300

    all: imp code, docs

commit 59549c4f74ee17b10eae542d1f1828d4e59894c9
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Oct 11 18:49:09 2022 +0300

    dhcpd: use netip initially

commit 1af623096b0517d07752385540f2f750f7f5b3bb
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Sep 30 18:03:52 2022 +0300

    all: imp docs, code

commit e9faeb71dbc0e887b25a7f3d5b33a401805f2ae7
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Sep 29 14:56:37 2022 +0300

    all: use netip for web

commit 38305e555a6884c3bd1b0839330b942ce0e59093
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Sep 28 19:13:58 2022 +0300

    add basic lla

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to
 
 ## Added
 
+- The ability to serve DNS on link-local IPv6 addresses ([#2926]).
 - The ability to put [ClientIDs][clientid] into DNS-over-HTTPS hostnames as
   opposed to URL paths ([#3418]).  Note that AdGuard Home checks the server name
   only if the URL does not contain a ClientID.
@@ -33,6 +34,7 @@ and this project adheres to
   cached now ([#4942]).
 - Web UI not switching to HTTP/3 ([#4986], [#4993]).
 
+[#2926]: https://github.com/AdguardTeam/AdGuardHome/issues/2926
 [#3418]: https://github.com/AdguardTeam/AdGuardHome/issues/3418
 [#4942]: https://github.com/AdguardTeam/AdGuardHome/issues/4942
 [#4986]: https://github.com/AdguardTeam/AdGuardHome/issues/4986

internal/aghnet/dhcp_unix.go

@@ -6,6 +6,7 @@ import (
 	"bytes"
 	"fmt"
 	"net"
+	"net/netip"
 	"os"
 	"time"
 
@@ -38,48 +39,44 @@ func checkOtherDHCP(ifaceName string) (ok4, ok6 bool, err4, err6 error) {
 }
 
 // ifaceIPv4Subnet returns the first suitable IPv4 subnetwork iface has.
-func ifaceIPv4Subnet(iface *net.Interface) (subnet *net.IPNet, err error) {
+func ifaceIPv4Subnet(iface *net.Interface) (subnet netip.Prefix, err error) {
 	var addrs []net.Addr
 	if addrs, err = iface.Addrs(); err != nil {
-		return nil, err
+		return netip.Prefix{}, err
 	}
 
 	for _, a := range addrs {
+		var ip net.IP
+		var maskLen int
 		switch a := a.(type) {
 		case *net.IPAddr:
-			subnet = &net.IPNet{
+			ip = a.IP
-				IP:   a.IP,
+			maskLen, _ = ip.DefaultMask().Size()
-				Mask: a.IP.DefaultMask(),
-			}
 		case *net.IPNet:
-			subnet = a
+			ip = a.IP
+			maskLen, _ = a.Mask.Size()
 		default:
 			continue
 		}
 
-		if ip4 := subnet.IP.To4(); ip4 != nil {
+		if ip = ip.To4(); ip != nil {
-			subnet.IP = ip4
+			return netip.PrefixFrom(netip.AddrFrom4(*(*[4]byte)(ip)), maskLen), nil
-
-			return subnet, nil
 		}
 	}
 
-	return nil, fmt.Errorf("interface %s has no ipv4 addresses", iface.Name)
+	return netip.Prefix{}, fmt.Errorf("interface %s has no ipv4 addresses", iface.Name)
 }
 
 // checkOtherDHCPv4 sends a DHCP request to the specified network interface, and
 // waits for a response for a period defined by defaultDiscoverTime.
 func checkOtherDHCPv4(iface *net.Interface) (ok bool, err error) {
-	var subnet *net.IPNet
+	var subnet netip.Prefix
 	if subnet, err = ifaceIPv4Subnet(iface); err != nil {
 		return false, err
 	}
 
 	// Resolve broadcast addr.
-	dst := netutil.IPPort{
+	dst := netip.AddrPortFrom(BroadcastFromPref(subnet), 67).String()
-		IP:   BroadcastFromIPNet(subnet),
-		Port: 67,
-	}.String()
 	var dstAddr *net.UDPAddr
 	if dstAddr, err = net.ResolveUDPAddr("udp4", dst); err != nil {
 		return false, fmt.Errorf("couldn't resolve UDP address %s: %w", dst, err)

internal/aghnet/hostscontainer.go

@@ -106,9 +106,13 @@ type HostsContainer struct {
 	done chan struct{}
 
 	// updates is the channel for receiving updated hosts.
+	//
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	updates chan *netutil.IPMap
 
 	// last is the set of hosts that was cached within last detected change.
+	//
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	last *netutil.IPMap
 
 	// fsys is the working file system to read hosts files from.

internal/aghnet/net.go

@@ -7,12 +7,12 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"net/netip"
 	"syscall"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghos"
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
-	"github.com/AdguardTeam/golibs/netutil"
 )
 
 // Variables and functions to substitute in tests.
@@ -31,6 +31,12 @@ var (
 // the IP being static is available.
 const ErrNoStaticIPInfo errors.Error = "no information about static ip"
 
+// IPv4Localhost returns 127.0.0.1, which returns true for [netip.Addr.Is4].
+func IPv4Localhost() (ip netip.Addr) { return netip.AddrFrom4([4]byte{127, 0, 0, 1}) }
+
+// IPv6Localhost returns ::1, which returns true for [netip.Addr.Is6].
+func IPv6Localhost() (ip netip.Addr) { return netip.AddrFrom16([16]byte{15: 1}) }
+
 // IfaceHasStaticIP checks if interface is configured to have static IP address.
 // If it can't give a definitive answer, it returns false and an error for which
 // errors.Is(err, ErrNoStaticIPInfo) is true.
@@ -47,26 +53,31 @@ func IfaceSetStaticIP(ifaceName string) (err error) {
 //
 // TODO(e.burkov):  Investigate if the gateway address may be fetched in another
 // way since not every machine has the software installed.
-func GatewayIP(ifaceName string) (ip net.IP) {
+func GatewayIP(ifaceName string) (ip netip.Addr) {
 	code, out, err := aghosRunCommand("ip", "route", "show", "dev", ifaceName)
 	if err != nil {
 		log.Debug("%s", err)
 
-		return nil
+		return netip.Addr{}
 	} else if code != 0 {
 		log.Debug("fetching gateway ip: unexpected exit code: %d", code)
 
-		return nil
+		return netip.Addr{}
 	}
 
 	fields := bytes.Fields(out)
 	// The meaningful "ip route" command output should contain the word
 	// "default" at first field and default gateway IP address at third field.
 	if len(fields) < 3 || string(fields[0]) != "default" {
-		return nil
+		return netip.Addr{}
 	}
 
-	return net.ParseIP(string(fields[2]))
+	ip, err = netip.ParseAddr(string(fields[2]))
+	if err != nil {
+		return netip.Addr{}
+	}
+
+	return ip
 }
 
 // CanBindPrivilegedPorts checks if current process can bind to privileged
@@ -78,9 +89,9 @@ func CanBindPrivilegedPorts() (can bool, err error) {
 // NetInterface represents an entry of network interfaces map.
 type NetInterface struct {
 	// Addresses are the network interface addresses.
-	Addresses []net.IP `json:"ip_addresses,omitempty"`
+	Addresses []netip.Addr `json:"ip_addresses,omitempty"`
 	// Subnets are the IP networks for this network interface.
-	Subnets      []*net.IPNet     `json:"-"`
+	Subnets      []netip.Prefix   `json:"-"`
 	Name         string           `json:"name"`
 	HardwareAddr net.HardwareAddr `json:"hardware_address"`
 	Flags        net.Flags        `json:"flags"`
@@ -101,57 +112,79 @@ func (iface NetInterface) MarshalJSON() ([]byte, error) {
 	})
 }
 
+func NetInterfaceFrom(iface *net.Interface) (niface *NetInterface, err error) {
+	niface = &NetInterface{
+		Name:         iface.Name,
+		HardwareAddr: iface.HardwareAddr,
+		Flags:        iface.Flags,
+		MTU:          iface.MTU,
+	}
+
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get addresses for interface %s: %w", iface.Name, err)
+	}
+
+	// Collect network interface addresses.
+	for _, addr := range addrs {
+		n, ok := addr.(*net.IPNet)
+		if !ok {
+			// Should be *net.IPNet, this is weird.
+			return nil, fmt.Errorf("expected %[2]s to be %[1]T, got %[2]T", n, addr)
+		} else if ip4 := n.IP.To4(); ip4 != nil {
+			n.IP = ip4
+		}
+
+		ip, ok := netip.AddrFromSlice(n.IP)
+		if !ok {
+			return nil, fmt.Errorf("bad address %s", n.IP)
+		}
+
+		ip = ip.Unmap()
+		if ip.IsLinkLocalUnicast() {
+			// Ignore link-local IPv4.
+			if ip.Is4() {
+				continue
+			}
+
+			ip = ip.WithZone(iface.Name)
+		}
+
+		ones, _ := n.Mask.Size()
+		p := netip.PrefixFrom(ip, ones)
+
+		niface.Addresses = append(niface.Addresses, ip)
+		niface.Subnets = append(niface.Subnets, p)
+	}
+
+	return niface, nil
+}
+
 // GetValidNetInterfacesForWeb returns interfaces that are eligible for DNS and
 // WEB only we do not return link-local addresses here.
 //
 // TODO(e.burkov):  Can't properly test the function since it's nontrivial to
 // substitute net.Interface.Addrs and the net.InterfaceAddrs can't be used.
-func GetValidNetInterfacesForWeb() (netIfaces []*NetInterface, err error) {
+func GetValidNetInterfacesForWeb() (nifaces []*NetInterface, err error) {
 	ifaces, err := net.Interfaces()
 	if err != nil {
-		return nil, fmt.Errorf("couldn't get interfaces: %w", err)
+		return nil, fmt.Errorf("getting interfaces: %w", err)
 	} else if len(ifaces) == 0 {
-		return nil, errors.Error("couldn't find any legible interface")
+		return nil, errors.Error("no legible interfaces")
 	}
 
-	for _, iface := range ifaces {
+	for i := range ifaces {
-		var addrs []net.Addr
+		var niface *NetInterface
-		addrs, err = iface.Addrs()
+		niface, err = NetInterfaceFrom(&ifaces[i])
 		if err != nil {
-			return nil, fmt.Errorf("failed to get addresses for interface %s: %w", iface.Name, err)
+			return nil, err
-		}
+		} else if len(niface.Addresses) != 0 {
-
+			// Discard interfaces with no addresses.
-		netIface := &NetInterface{
+			nifaces = append(nifaces, niface)
-			MTU:          iface.MTU,
-			Name:         iface.Name,
-			HardwareAddr: iface.HardwareAddr,
-			Flags:        iface.Flags,
-		}
-
-		// Collect network interface addresses.
-		for _, addr := range addrs {
-			ipNet, ok := addr.(*net.IPNet)
-			if !ok {
-				// Should be net.IPNet, this is weird.
-				return nil, fmt.Errorf("got %s that is not net.IPNet, it is %T", addr, addr)
-			}
-
-			// Ignore link-local.
-			if ipNet.IP.IsLinkLocalUnicast() {
-				continue
-			}
-
-			netIface.Addresses = append(netIface.Addresses, ipNet.IP)
-			netIface.Subnets = append(netIface.Subnets, ipNet)
-		}
-
-		// Discard interfaces with no addresses.
-		if len(netIface.Addresses) != 0 {
-			netIfaces = append(netIfaces, netIface)
 		}
 	}
 
-	return netIfaces, nil
+	return nifaces, nil
 }
 
 // InterfaceByIP returns the name of the interface bound to ip.
@@ -160,7 +193,7 @@ func GetValidNetInterfacesForWeb() (netIfaces []*NetInterface, err error) {
 // IP address can be shared by multiple interfaces in some configurations.
 //
 // TODO(e.burkov):  See TODO on GetValidNetInterfacesForWeb.
-func InterfaceByIP(ip net.IP) (ifaceName string) {
+func InterfaceByIP(ip netip.Addr) (ifaceName string) {
 	ifaces, err := GetValidNetInterfacesForWeb()
 	if err != nil {
 		return ""
@@ -168,7 +201,7 @@ func InterfaceByIP(ip net.IP) (ifaceName string) {
 
 	for _, iface := range ifaces {
 		for _, addr := range iface.Addresses {
-			if ip.Equal(addr) {
+			if ip == addr {
 				return iface.Name
 			}
 		}
@@ -177,15 +210,16 @@ func InterfaceByIP(ip net.IP) (ifaceName string) {
 	return ""
 }
 
-// GetSubnet returns pointer to net.IPNet for the specified interface or nil if
+// GetSubnet returns the subnet corresponding to the interface of zero prefix if
 // the search fails.
 //
 // TODO(e.burkov):  See TODO on GetValidNetInterfacesForWeb.
-func GetSubnet(ifaceName string) *net.IPNet {
+func GetSubnet(ifaceName string) (p netip.Prefix) {
 	netIfaces, err := GetValidNetInterfacesForWeb()
 	if err != nil {
 		log.Error("Could not get network interfaces info: %v", err)
-		return nil
+
+		return p
 	}
 
 	for _, netIface := range netIfaces {
@@ -194,14 +228,14 @@ func GetSubnet(ifaceName string) *net.IPNet {
 		}
 	}
 
-	return nil
+	return p
 }
 
 // CheckPort checks if the port is available for binding.  network is expected
 // to be one of "udp" and "tcp".
-func CheckPort(network string, ip net.IP, port int) (err error) {
+func CheckPort(network string, ipp netip.AddrPort) (err error) {
 	var c io.Closer
-	addr := netutil.IPPort{IP: ip, Port: port}.String()
+	addr := ipp.String()
 	switch network {
 	case "tcp":
 		c, err = net.Listen(network, addr)
@@ -251,18 +285,23 @@ func CollectAllIfacesAddrs() (addrs []string, err error) {
 	return addrs, nil
 }
 
-// BroadcastFromIPNet calculates the broadcast IP address for n.
+// BroadcastFromPref calculates the broadcast IP address for p.
-func BroadcastFromIPNet(n *net.IPNet) (dc net.IP) {
+func BroadcastFromPref(p netip.Prefix) (bc netip.Addr) {
-	dc = netutil.CloneIP(n.IP)
+	bc = p.Addr().Unmap()
-
+	if !bc.IsValid() {
-	mask := n.Mask
+		return netip.Addr{}
-	if mask == nil {
-		mask = dc.DefaultMask()
 	}
 
-	for i, b := range mask {
+	maskLen, addrLen := p.Bits(), bc.BitLen()
-		dc[i] |= ^b
+	if maskLen == addrLen {
+		return bc
 	}
 
-	return dc
+	ipBytes := bc.AsSlice()
+	for i := maskLen; i < addrLen; i++ {
+		ipBytes[i/8] |= 1 << (7 - (i % 8))
+	}
+	bc, _ = netip.AddrFromSlice(ipBytes)
+
+	return bc
 }

internal/aghnet/net_linux.go

@@ -6,7 +6,7 @@ import (
 	"bufio"
 	"fmt"
 	"io"
-	"net"
+	"net/netip"
 	"os"
 	"strings"
 
@@ -151,7 +151,7 @@ func findIfaceLine(s *bufio.Scanner, name string) (ok bool) {
 // interface through dhcpcd.conf.
 func ifaceSetStaticIP(ifaceName string) (err error) {
 	ipNet := GetSubnet(ifaceName)
-	if ipNet.IP == nil {
+	if !ipNet.Addr().IsValid() {
 		return errors.Error("can't get IP address")
 	}
 
@@ -174,7 +174,7 @@ func ifaceSetStaticIP(ifaceName string) (err error) {
 
 // dhcpcdConfIface returns configuration lines for the dhcpdc.conf files that
 // configure the interface to have a static IP.
-func dhcpcdConfIface(ifaceName string, ipNet *net.IPNet, gwIP net.IP) (conf string) {
+func dhcpcdConfIface(ifaceName string, subnet netip.Prefix, gateway netip.Addr) (conf string) {
 	b := &strings.Builder{}
 	stringutil.WriteToBuilder(
 		b,
@@ -183,15 +183,15 @@ func dhcpcdConfIface(ifaceName string, ipNet *net.IPNet, gwIP net.IP) (conf stri
 		" added by AdGuard Home.\ninterface ",
 		ifaceName,
 		"\nstatic ip_address=",
-		ipNet.String(),
+		subnet.String(),
 		"\n",
 	)
 
-	if gwIP != nil {
+	if gateway != (netip.Addr{}) {
-		stringutil.WriteToBuilder(b, "static routers=", gwIP.String(), "\n")
+		stringutil.WriteToBuilder(b, "static routers=", gateway.String(), "\n")
 	}
 
-	stringutil.WriteToBuilder(b, "static domain_name_servers=", ipNet.IP.String(), "\n\n")
+	stringutil.WriteToBuilder(b, "static domain_name_servers=", subnet.Addr().String(), "\n\n")
 
 	return b.String()
 }

internal/aghnet/net_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io/fs"
 	"net"
+	"net/netip"
 	"os"
 	"strings"
 	"testing"
@@ -93,34 +94,29 @@ func TestGatewayIP(t *testing.T) {
 	const cmd = "ip route show dev " + ifaceName
 
 	testCases := []struct {
-		name  string
 		shell mapShell
-		want  net.IP
+		want  netip.Addr
+		name  string
 	}{{
-		name:  "success_v4",
 		shell: theOnlyCmd(cmd, 0, `default via 1.2.3.4 onlink`, nil),
-		want:  net.IP{1, 2, 3, 4}.To16(),
+		want:  netip.MustParseAddr("1.2.3.4"),
+		name:  "success_v4",
 	}, {
-		name:  "success_v6",
 		shell: theOnlyCmd(cmd, 0, `default via ::ffff onlink`, nil),
-		want: net.IP{
+		want:  netip.MustParseAddr("::ffff"),
-			0x0, 0x0, 0x0, 0x0,
+		name:  "success_v6",
-			0x0, 0x0, 0x0, 0x0,
-			0x0, 0x0, 0x0, 0x0,
-			0x0, 0x0, 0xFF, 0xFF,
-		},
 	}, {
-		name:  "bad_output",
 		shell: theOnlyCmd(cmd, 0, `non-default via 1.2.3.4 onlink`, nil),
-		want:  nil,
+		want:  netip.Addr{},
+		name:  "bad_output",
 	}, {
-		name:  "err_runcmd",
 		shell: theOnlyCmd(cmd, 0, "", errors.Error("can't run command")),
-		want:  nil,
+		want:  netip.Addr{},
+		name:  "err_runcmd",
 	}, {
-		name:  "bad_code",
 		shell: theOnlyCmd(cmd, 1, "", nil),
-		want:  nil,
+		want:  netip.Addr{},
+		name:  "bad_code",
 	}}
 
 	for _, tc := range testCases {
@@ -150,65 +146,64 @@ func TestInterfaceByIP(t *testing.T) {
 }
 
 func TestBroadcastFromIPNet(t *testing.T) {
-	known6 := net.IP{
+	known4 := netip.MustParseAddr("192.168.0.1")
-		1, 2, 3, 4,
+	fullBroadcast4 := netip.MustParseAddr("255.255.255.255")
-		5, 6, 7, 8,
+
-		9, 10, 11, 12,
+	known6 := netip.MustParseAddr("102:304:506:708:90a:b0c:d0e:f10")
-		13, 14, 15, 16,
-	}
 
 	testCases := []struct {
-		name   string
+		pref netip.Prefix
-		subnet *net.IPNet
+		want netip.Addr
-		want   net.IP
+		name string
 	}{{
+		pref: netip.PrefixFrom(known4, 0),
+		want: fullBroadcast4,
 		name: "full",
-		subnet: &net.IPNet{
-			IP:   net.IP{192, 168, 0, 1},
-			Mask: net.IPMask{255, 255, 15, 0},
-		},
-		want: net.IP{192, 168, 240, 255},
 	}, {
-		name: "ipv6_no_mask",
+		pref: netip.PrefixFrom(known4, 20),
-		subnet: &net.IPNet{
+		want: netip.MustParseAddr("192.168.15.255"),
-			IP: known6,
+		name: "full",
-		},
+	}, {
+		pref: netip.PrefixFrom(known6, netutil.IPv6BitLen),
 		want: known6,
+		name: "ipv6_no_mask",
 	}, {
+		pref: netip.PrefixFrom(known4, netutil.IPv4BitLen),
+		want: known4,
 		name: "ipv4_no_mask",
-		subnet: &net.IPNet{
-			IP: net.IP{192, 168, 1, 2},
-		},
-		want: net.IP{192, 168, 1, 255},
 	}, {
+		pref: netip.PrefixFrom(netip.IPv4Unspecified(), 0),
+		want: fullBroadcast4,
 		name: "unspecified",
-		subnet: &net.IPNet{
+	}, {
-			IP:   net.IP{0, 0, 0, 0},
+		pref: netip.Prefix{},
-			Mask: net.IPMask{0, 0, 0, 0},
+		want: netip.Addr{},
-		},
+		name: "invalid",
-		want: net.IPv4bcast,
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			bc := BroadcastFromIPNet(tc.subnet)
+			assert.Equal(t, tc.want, BroadcastFromPref(tc.pref))
-			assert.True(t, bc.Equal(tc.want), bc)
 		})
 	}
 }
 
 func TestCheckPort(t *testing.T) {
+	laddr := netip.AddrPortFrom(IPv4Localhost(), 0)
+
 	t.Run("tcp_bound", func(t *testing.T) {
-		l, err := net.Listen("tcp", "127.0.0.1:")
+		l, err := net.Listen("tcp", laddr.String())
 		require.NoError(t, err)
 		testutil.CleanupAndRequireSuccess(t, l.Close)
 
-		ipp := netutil.IPPortFromAddr(l.Addr())
+		addr := l.Addr()
-		require.NotNil(t, ipp)
+		require.IsType(t, new(net.TCPAddr), addr)
-		require.NotNil(t, ipp.IP)
-		require.NotZero(t, ipp.Port)
 
-		err = CheckPort("tcp", ipp.IP, ipp.Port)
+		ipp := addr.(*net.TCPAddr).AddrPort()
+		require.Equal(t, laddr.Addr(), ipp.Addr())
+		require.NotZero(t, ipp.Port())
+
+		err = CheckPort("tcp", ipp)
 		target := &net.OpError{}
 		require.ErrorAs(t, err, &target)
 
@@ -216,16 +211,18 @@ func TestCheckPort(t *testing.T) {
 	})
 
 	t.Run("udp_bound", func(t *testing.T) {
-		conn, err := net.ListenPacket("udp", "127.0.0.1:")
+		conn, err := net.ListenPacket("udp", laddr.String())
 		require.NoError(t, err)
 		testutil.CleanupAndRequireSuccess(t, conn.Close)
 
-		ipp := netutil.IPPortFromAddr(conn.LocalAddr())
+		addr := conn.LocalAddr()
-		require.NotNil(t, ipp)
+		require.IsType(t, new(net.UDPAddr), addr)
-		require.NotNil(t, ipp.IP)
-		require.NotZero(t, ipp.Port)
 
-		err = CheckPort("udp", ipp.IP, ipp.Port)
+		ipp := addr.(*net.UDPAddr).AddrPort()
+		require.Equal(t, laddr.Addr(), ipp.Addr())
+		require.NotZero(t, ipp.Port())
+
+		err = CheckPort("udp", ipp)
 		target := &net.OpError{}
 		require.ErrorAs(t, err, &target)
 
@@ -233,12 +230,12 @@ func TestCheckPort(t *testing.T) {
 	})
 
 	t.Run("bad_network", func(t *testing.T) {
-		err := CheckPort("bad_network", nil, 0)
+		err := CheckPort("bad_network", netip.AddrPortFrom(netip.Addr{}, 0))
 		assert.NoError(t, err)
 	})
 
 	t.Run("can_bind", func(t *testing.T) {
-		err := CheckPort("udp", net.IP{0, 0, 0, 0}, 0)
+		err := CheckPort("udp", netip.AddrPortFrom(netip.IPv4Unspecified(), 0))
 		assert.NoError(t, err)
 	})
 }
@@ -322,18 +319,18 @@ func TestNetInterface_MarshalJSON(t *testing.T) {
 		`"mtu":1500` +
 		`}` + "\n"
 
-	ip4, ip6 := net.IP{1, 2, 3, 4}, net.IP{0xAA, 0xAA, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
+	ip4, ok := netip.AddrFromSlice([]byte{1, 2, 3, 4})
-	mask4, mask6 := net.CIDRMask(24, netutil.IPv4BitLen), net.CIDRMask(8, netutil.IPv6BitLen)
+	require.True(t, ok)
+
+	ip6, ok := netip.AddrFromSlice([]byte{0xAA, 0xAA, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1})
+	require.True(t, ok)
+
+	net4 := netip.PrefixFrom(ip4, 24)
+	net6 := netip.PrefixFrom(ip6, 8)
 
 	iface := &NetInterface{
-		Addresses: []net.IP{ip4, ip6},
+		Addresses:    []netip.Addr{ip4, ip6},
-		Subnets: []*net.IPNet{{
+		Subnets:      []netip.Prefix{net4, net6},
-			IP:   ip4.Mask(mask4),
-			Mask: mask4,
-		}, {
-			IP:   ip6.Mask(mask6),
-			Mask: mask6,
-		}},
 		Name:         "iface0",
 		HardwareAddr: net.HardwareAddr{0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
 		Flags:        net.FlagUp | net.FlagMulticast,

internal/dhcpd/config.go

@@ -3,12 +3,12 @@ package dhcpd
 import (
 	"fmt"
 	"net"
+	"net/netip"
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
 	"github.com/AdguardTeam/golibs/errors"
-	"github.com/AdguardTeam/golibs/netutil"
 )
 
 // ServerConfig is the configuration for the DHCP server.  The order of YAML
@@ -65,16 +65,16 @@ type V4ServerConf struct {
 	Enabled       bool   `yaml:"-" json:"-"`
 	InterfaceName string `yaml:"-" json:"-"`
 
-	GatewayIP  net.IP `yaml:"gateway_ip" json:"gateway_ip"`
+	GatewayIP  netip.Addr `yaml:"gateway_ip" json:"gateway_ip"`
-	SubnetMask net.IP `yaml:"subnet_mask" json:"subnet_mask"`
+	SubnetMask netip.Addr `yaml:"subnet_mask" json:"subnet_mask"`
 	// broadcastIP is the broadcasting address pre-calculated from the
 	// configured gateway IP and subnet mask.
-	broadcastIP net.IP
+	broadcastIP netip.Addr
 
 	// The first & the last IP address for dynamic leases
 	// Bytes [0..2] of the last allowed IP address must match the first IP
-	RangeStart net.IP `yaml:"range_start" json:"range_start"`
+	RangeStart netip.Addr `yaml:"range_start" json:"range_start"`
-	RangeEnd   net.IP `yaml:"range_end" json:"range_end"`
+	RangeEnd   netip.Addr `yaml:"range_end" json:"range_end"`
 
 	LeaseDuration uint32 `yaml:"lease_duration" json:"lease_duration"` // in seconds
 
@@ -95,11 +95,11 @@ type V4ServerConf struct {
 	ipRange *ipRange
 
 	leaseTime  time.Duration // the time during which a dynamic lease is considered valid
-	dnsIPAddrs []net.IP      // IPv4 addresses to return to DHCP clients as DNS server addresses
+	dnsIPAddrs []netip.Addr  // IPv4 addresses to return to DHCP clients as DNS server addresses
 
 	// subnet contains the DHCP server's subnet.  The IP is the IP of the
 	// gateway.
-	subnet *net.IPNet
+	subnet netip.Prefix
 
 	// notify is a way to signal to other components that leases have been
 	// changed.  notify must be called outside of locked sections, since the
@@ -113,16 +113,12 @@ type V4ServerConf struct {
 // errNilConfig is an error returned by validation method if the config is nil.
 const errNilConfig errors.Error = "nil config"
 
-// ensureV4 returns a 4-byte version of ip.  An error is returned if the passed
+// ensureV4 returns an unmapped version of ip.  An error is returned if the
-// ip is not an IPv4.
+// passed ip is not an IPv4.
-func ensureV4(ip net.IP) (ip4 net.IP, err error) {
+func ensureV4(ip netip.Addr, kind string) (ip4 netip.Addr, err error) {
-	if ip == nil {
+	ip4 = ip.Unmap()
-		return nil, fmt.Errorf("%v is not an IP address", ip)
+	if !ip4.IsValid() || !ip4.Is4() {
-	}
+		return netip.Addr{}, fmt.Errorf("%v is not an IPv4 %s", ip, kind)
-
-	ip4 = ip.To4()
-	if ip4 == nil {
-		return nil, fmt.Errorf("%v is not an IPv4 address", ip)
 	}
 
 	return ip4, nil
@@ -139,33 +135,45 @@ func (c *V4ServerConf) Validate() (err error) {
 		return errNilConfig
 	}
 
-	var gatewayIP net.IP
+	gatewayIP, err := ensureV4(c.GatewayIP, "address")
-	gatewayIP, err = ensureV4(c.GatewayIP)
 	if err != nil {
-		// Don't wrap an errors since it's inforative enough as is and there is
+		// Don't wrap an errors since it's informative enough as is and there is
 		// an annotation deferred already.
 		return err
 	}
 
-	if c.SubnetMask == nil {
+	subnetMask, err := ensureV4(c.SubnetMask, "subnet mask")
-		return fmt.Errorf("invalid subnet mask: %v", c.SubnetMask)
-	}
-
-	subnetMask := net.IPMask(netutil.CloneIP(c.SubnetMask.To4()))
-	c.subnet = &net.IPNet{
-		IP:   gatewayIP,
-		Mask: subnetMask,
-	}
-	c.broadcastIP = aghnet.BroadcastFromIPNet(c.subnet)
-
-	c.ipRange, err = newIPRange(c.RangeStart, c.RangeEnd)
 	if err != nil {
-		// Don't wrap an errors since it's inforative enough as is and there is
+		// Don't wrap an errors since it's informative enough as is and there is
+		// an annotation deferred already.
+		return err
+	}
+	maskLen, _ := net.IPMask(subnetMask.AsSlice()).Size()
+
+	c.subnet = netip.PrefixFrom(gatewayIP, maskLen)
+	c.broadcastIP = aghnet.BroadcastFromPref(c.subnet)
+
+	rangeStart, err := ensureV4(c.RangeStart, "address")
+	if err != nil {
+		// Don't wrap an errors since it's informative enough as is and there is
+		// an annotation deferred already.
+		return err
+	}
+	rangeEnd, err := ensureV4(c.RangeEnd, "address")
+	if err != nil {
+		// Don't wrap an errors since it's informative enough as is and there is
 		// an annotation deferred already.
 		return err
 	}
 
-	if c.ipRange.contains(gatewayIP) {
+	c.ipRange, err = newIPRange(rangeStart.AsSlice(), rangeEnd.AsSlice())
+	if err != nil {
+		// Don't wrap an errors since it's informative enough as is and there is
+		// an annotation deferred already.
+		return err
+	}
+
+	if c.ipRange.contains(gatewayIP.AsSlice()) {
 		return fmt.Errorf("gateway ip %v in the ip range: %v-%v",
 			gatewayIP,
 			c.RangeStart,
@@ -173,14 +181,14 @@ func (c *V4ServerConf) Validate() (err error) {
 		)
 	}
 
-	if !c.subnet.Contains(c.RangeStart) {
+	if !c.subnet.Contains(rangeStart) {
 		return fmt.Errorf("range start %v is outside network %v",
 			c.RangeStart,
 			c.subnet,
 		)
 	}
 
-	if !c.subnet.Contains(c.RangeEnd) {
+	if !c.subnet.Contains(rangeEnd) {
 		return fmt.Errorf("range end %v is outside network %v",
 			c.RangeEnd,
 			c.subnet,

internal/dhcpd/conn_unix.go

@@ -73,10 +73,10 @@ func (s *v4Server) newDHCPConn(iface *net.Interface) (c net.PacketConn, err erro
 
 	return &dhcpConn{
 		udpConn: bcast,
-		bcastIP: s.conf.broadcastIP,
+		bcastIP: s.conf.broadcastIP.AsSlice(),
 		rawConn: ucast,
 		srcMAC:  iface.HardwareAddr,
-		srcIP:   s.conf.dnsIPAddrs[0],
+		srcIP:   s.conf.dnsIPAddrs[0].AsSlice(),
 	}, nil
 }
 

internal/dhcpd/dhcpd.go

@@ -242,7 +242,7 @@ func Create(conf *ServerConfig) (s *server, err error) {
 	v4conf := conf.Conf4
 	v4conf.InterfaceName = s.conf.InterfaceName
 	v4conf.notify = s.onNotify
-	v4conf.Enabled = s.conf.Enabled && len(v4conf.RangeStart) != 0
+	v4conf.Enabled = s.conf.Enabled && v4conf.RangeStart.IsValid()
 
 	s.srv4, err = v4Create(&v4conf)
 	if err != nil {

internal/dhcpd/dhcpd_unix_test.go

@@ -4,6 +4,7 @@ package dhcpd
 
 import (
 	"net"
+	"net/netip"
 	"os"
 	"testing"
 	"time"
@@ -33,10 +34,10 @@ func TestDB(t *testing.T) {
 
 	s.srv4, err = v4Create(&V4ServerConf{
 		Enabled:    true,
-		RangeStart: net.IP{192, 168, 10, 100},
+		RangeStart: netip.MustParseAddr("192.168.10.100"),
-		RangeEnd:   net.IP{192, 168, 10, 200},
+		RangeEnd:   netip.MustParseAddr("192.168.10.200"),
-		GatewayIP:  net.IP{192, 168, 10, 1},
+		GatewayIP:  netip.MustParseAddr("192.168.10.1"),
-		SubnetMask: net.IP{255, 255, 255, 0},
+		SubnetMask: netip.MustParseAddr("255.255.255.0"),
 		notify:     testNotify,
 	})
 	require.NoError(t, err)
@@ -113,35 +114,35 @@ func TestNormalizeLeases(t *testing.T) {
 func TestV4Server_badRange(t *testing.T) {
 	testCases := []struct {
 		name       string
+		gatewayIP  netip.Addr
+		subnetMask netip.Addr
 		wantErrMsg string
-		gatewayIP  net.IP
-		subnetMask net.IP
 	}{{
-		name: "gateway_in_range",
+		name:       "gateway_in_range",
+		gatewayIP:  netip.MustParseAddr("192.168.10.120"),
+		subnetMask: netip.MustParseAddr("255.255.255.0"),
 		wantErrMsg: "dhcpv4: gateway ip 192.168.10.120 in the ip range: " +
 			"192.168.10.20-192.168.10.200",
-		gatewayIP:  net.IP{192, 168, 10, 120},
-		subnetMask: net.IP{255, 255, 255, 0},
 	}, {
-		name: "outside_range_start",
+		name:       "outside_range_start",
+		gatewayIP:  netip.MustParseAddr("192.168.10.1"),
+		subnetMask: netip.MustParseAddr("255.255.255.240"),
 		wantErrMsg: "dhcpv4: range start 192.168.10.20 is outside network " +
 			"192.168.10.1/28",
-		gatewayIP:  net.IP{192, 168, 10, 1},
-		subnetMask: net.IP{255, 255, 255, 240},
 	}, {
-		name: "outside_range_end",
+		name:       "outside_range_end",
+		gatewayIP:  netip.MustParseAddr("192.168.10.1"),
+		subnetMask: netip.MustParseAddr("255.255.255.224"),
 		wantErrMsg: "dhcpv4: range end 192.168.10.200 is outside network " +
 			"192.168.10.1/27",
-		gatewayIP:  net.IP{192, 168, 10, 1},
-		subnetMask: net.IP{255, 255, 255, 224},
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			conf := V4ServerConf{
 				Enabled:    true,
-				RangeStart: net.IP{192, 168, 10, 20},
+				RangeStart: netip.MustParseAddr("192.168.10.20"),
-				RangeEnd:   net.IP{192, 168, 10, 200},
+				RangeEnd:   netip.MustParseAddr("192.168.10.200"),
 				GatewayIP:  tc.gatewayIP,
 				SubnetMask: tc.subnetMask,
 				notify:     testNotify,

internal/dhcpd/http_unix.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/netip"
 	"os"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
@@ -17,11 +18,11 @@ import (
 )
 
 type v4ServerConfJSON struct {
-	GatewayIP     net.IP `json:"gateway_ip"`
+	GatewayIP     netip.Addr `json:"gateway_ip"`
-	SubnetMask    net.IP `json:"subnet_mask"`
+	SubnetMask    netip.Addr `json:"subnet_mask"`
-	RangeStart    net.IP `json:"range_start"`
+	RangeStart    netip.Addr `json:"range_start"`
-	RangeEnd      net.IP `json:"range_end"`
+	RangeEnd      netip.Addr `json:"range_end"`
-	LeaseDuration uint32 `json:"lease_duration"`
+	LeaseDuration uint32     `json:"lease_duration"`
 }
 
 func (j *v4ServerConfJSON) toServerConf() *V4ServerConf {
@@ -39,8 +40,8 @@ func (j *v4ServerConfJSON) toServerConf() *V4ServerConf {
 }
 
 type v6ServerConfJSON struct {
-	RangeStart    net.IP `json:"range_start"`
+	RangeStart    netip.Addr `json:"range_start"`
-	LeaseDuration uint32 `json:"lease_duration"`
+	LeaseDuration uint32     `json:"lease_duration"`
 }
 
 func v6JSONToServerConf(j *v6ServerConfJSON) V6ServerConf {
@@ -49,7 +50,7 @@ func v6JSONToServerConf(j *v6ServerConfJSON) V6ServerConf {
 	}
 
 	return V6ServerConf{
-		RangeStart:    j.RangeStart,
+		RangeStart:    j.RangeStart.AsSlice(),
 		LeaseDuration: j.LeaseDuration,
 	}
 }
@@ -144,7 +145,7 @@ func (s *server) handleDHCPSetConfigV4(
 
 	v4Conf := conf.V4.toServerConf()
 	v4Conf.Enabled = conf.Enabled == aghalg.NBTrue
-	if len(v4Conf.RangeStart) == 0 {
+	if !v4Conf.RangeStart.IsValid() {
 		v4Conf.Enabled = false
 	}
 
@@ -275,12 +276,12 @@ func (s *server) setConfFromJSON(conf *dhcpServerConfigJSON, srv4, srv6 DHCPServ
 }
 
 type netInterfaceJSON struct {
-	Name         string   `json:"name"`
+	Name         string       `json:"name"`
-	HardwareAddr string   `json:"hardware_address"`
+	HardwareAddr string       `json:"hardware_address"`
-	Flags        string   `json:"flags"`
+	Flags        string       `json:"flags"`
-	GatewayIP    net.IP   `json:"gateway_ip"`
+	GatewayIP    netip.Addr   `json:"gateway_ip"`
-	Addrs4       []net.IP `json:"ipv4_addresses"`
+	Addrs4       []netip.Addr `json:"ipv4_addresses"`
-	Addrs6       []net.IP `json:"ipv6_addresses"`
+	Addrs6       []netip.Addr `json:"ipv6_addresses"`
 }
 
 func (s *server) handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
@@ -341,13 +342,18 @@ func (s *server) handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
 				return
 			}
 			// ignore link-local
+			//
+			// TODO(e.burkov):  Try to listen DHCP on LLA as well.
 			if ipnet.IP.IsLinkLocalUnicast() {
 				continue
 			}
-			if ipnet.IP.To4() != nil {
+
-				jsonIface.Addrs4 = append(jsonIface.Addrs4, ipnet.IP)
+			if ip4 := ipnet.IP.To4(); ip4 != nil {
+				addr := netip.AddrFrom4(*(*[4]byte)(ip4))
+				jsonIface.Addrs4 = append(jsonIface.Addrs4, addr)
 			} else {
-				jsonIface.Addrs6 = append(jsonIface.Addrs6, ipnet.IP)
+				addr := netip.AddrFrom16(*(*[16]byte)(ipnet.IP))
+				jsonIface.Addrs6 = append(jsonIface.Addrs6, addr)
 			}
 		}
 		if len(jsonIface.Addrs4)+len(jsonIface.Addrs6) != 0 {

internal/dhcpd/iprange.go

@@ -27,6 +27,8 @@ 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/options_unix.go

@@ -372,12 +372,9 @@ func (s *v4Server) prepareOptions() {
 		dhcpv4.OptGeneric(dhcpv4.OptionTCPKeepaliveGarbage, []byte{0x01}),
 
 		// Values From Configuration
+		dhcpv4.OptRouter(s.conf.GatewayIP.AsSlice()),
 
-		// Set the Router Option to working subnet's IP since it's initialized
+		dhcpv4.OptSubnetMask(s.conf.SubnetMask.AsSlice()),
-		// with the address of the gateway.
-		dhcpv4.OptRouter(s.conf.subnet.IP),
-
-		dhcpv4.OptSubnetMask(s.conf.subnet.Mask),
 	)
 
 	// Set values for explicitly configured options.

internal/dhcpd/options_unix_test.go

@@ -251,8 +251,6 @@ func TestPrepareOptions(t *testing.T) {
 	for _, tc := range testCases {
 		s := &v4Server{
 			conf: &V4ServerConf{
-				// Just to avoid nil pointer dereference.
-				subnet:  &net.IPNet{},
 				Options: tc.opts,
 			},
 		}

internal/dhcpd/v4_unix.go

@@ -6,6 +6,7 @@ import (
 	"bytes"
 	"fmt"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 	"time"
@@ -295,7 +296,8 @@ func (s *v4Server) addLease(l *Lease) (err error) {
 	if l.IsStatic() {
 		// TODO(a.garipov, d.seregin): Subnet can be nil when dhcp server is
 		// disabled.
-		if sn := s.conf.subnet; !sn.Contains(l.IP) {
+		addr := netip.AddrFrom4(*(*[4]byte)(l.IP.To4()))
+		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 {
@@ -353,7 +355,7 @@ func (s *v4Server) AddStaticLease(l *Lease) (err error) {
 	ip := l.IP.To4()
 	if ip == nil {
 		return fmt.Errorf("invalid ip %q, only ipv4 is supported", l.IP)
-	} else if gwIP := s.conf.GatewayIP; gwIP.Equal(ip) {
+	} else if gwIP := s.conf.GatewayIP; gwIP == netip.AddrFrom4(*(*[4]byte)(ip)) {
 		return fmt.Errorf("can't assign the gateway IP %s to the lease", gwIP)
 	}
 
@@ -701,7 +703,8 @@ func (s *v4Server) handleSelecting(
 	// Client inserts the address of the selected server in server identifier,
 	// ciaddr MUST be zero.
 	mac := req.ClientHWAddr
-	if !sid.Equal(s.conf.dnsIPAddrs[0]) {
+
+	if !sid.Equal(s.conf.dnsIPAddrs[0].AsSlice()) {
 		log.Debug("dhcpv4: bad server identifier in req msg for %s: %s", mac, sid)
 
 		return nil, false
@@ -733,7 +736,8 @@ func (s *v4Server) handleSelecting(
 func (s *v4Server) handleInitReboot(req *dhcpv4.DHCPv4, reqIP net.IP) (l *Lease, needsReply bool) {
 	mac := req.ClientHWAddr
 
-	if ip4 := reqIP.To4(); ip4 == nil {
+	ip4 := reqIP.To4()
+	if ip4 == nil {
 		log.Debug("dhcpv4: bad requested address in req msg for %s: %s", mac, reqIP)
 
 		return nil, false
@@ -747,7 +751,7 @@ func (s *v4Server) handleInitReboot(req *dhcpv4.DHCPv4, reqIP net.IP) (l *Lease,
 		return nil, false
 	}
 
-	if !s.conf.subnet.Contains(reqIP) {
+	if !s.conf.subnet.Contains(netip.AddrFrom4(*(*[4]byte)(ip4))) {
 		// If the DHCP server detects that the client is on the wrong net then
 		// the server SHOULD send a DHCPNAK message to the client.
 		log.Debug("dhcpv4: wrong subnet in init-reboot req msg for %s: %s", mac, reqIP)
@@ -972,7 +976,7 @@ func (s *v4Server) handle(req, resp *dhcpv4.DHCPv4) int {
 	// Include server's identifier option since any reply should contain it.
 	//
 	// See https://datatracker.ietf.org/doc/html/rfc2131#page-29.
-	resp.UpdateOption(dhcpv4.OptServerIdentifier(s.conf.dnsIPAddrs[0]))
+	resp.UpdateOption(dhcpv4.OptServerIdentifier(s.conf.dnsIPAddrs[0].AsSlice()))
 
 	// TODO(a.garipov): Refactor this into handlers.
 	var l *Lease
@@ -1188,7 +1192,14 @@ func (s *v4Server) Start() (err error) {
 		s.implicitOpts.Update(dhcpv4.OptDNS(dnsIPAddrs...))
 	}
 
-	s.conf.dnsIPAddrs = dnsIPAddrs
+	for _, ip := range dnsIPAddrs {
+		ip = ip.To4()
+		if ip == nil {
+			continue
+		}
+
+		s.conf.dnsIPAddrs = append(s.conf.dnsIPAddrs, netip.AddrFrom4(*(*[4]byte)(ip)))
+	}
 
 	var c net.PacketConn
 	if c, err = s.newDHCPConn(iface); err != nil {

internal/dhcpd/v4_unix_test.go

@@ -5,6 +5,7 @@ package dhcpd
 import (
 	"fmt"
 	"net"
+	"net/netip"
 	"strings"
 	"testing"
 	"time"
@@ -22,11 +23,11 @@ import (
 )
 
 var (
-	DefaultRangeStart = net.IP{192, 168, 10, 100}
+	DefaultRangeStart = netip.MustParseAddr("192.168.10.100")
-	DefaultRangeEnd   = net.IP{192, 168, 10, 200}
+	DefaultRangeEnd   = netip.MustParseAddr("192.168.10.200")
-	DefaultGatewayIP  = net.IP{192, 168, 10, 1}
+	DefaultGatewayIP  = netip.MustParseAddr("192.168.10.1")
-	DefaultSelfIP     = net.IP{192, 168, 10, 2}
+	DefaultSelfIP     = netip.MustParseAddr("192.168.10.2")
-	DefaultSubnetMask = net.IP{255, 255, 255, 0}
+	DefaultSubnetMask = netip.MustParseAddr("255.255.255.0")
 )
 
 // defaultV4ServerConf returns the default configuration for *v4Server to use in
@@ -39,7 +40,7 @@ func defaultV4ServerConf() (conf *V4ServerConf) {
 		GatewayIP:  DefaultGatewayIP,
 		SubnetMask: DefaultSubnetMask,
 		notify:     testNotify,
-		dnsIPAddrs: []net.IP{DefaultSelfIP},
+		dnsIPAddrs: []netip.Addr{DefaultSelfIP},
 	}
 }
 
@@ -82,7 +83,7 @@ func TestV4Server_leasing(t *testing.T) {
 				Expiry:   time.Unix(leaseExpireStatic, 0),
 				Hostname: staticName,
 				HWAddr:   anotherMAC,
-				IP:       anotherIP,
+				IP:       anotherIP.AsSlice(),
 			})
 			assert.ErrorIs(t, err, ErrDupHostname)
 		})
@@ -96,7 +97,7 @@ func TestV4Server_leasing(t *testing.T) {
 				Expiry:   time.Unix(leaseExpireStatic, 0),
 				Hostname: anotherName,
 				HWAddr:   staticMAC,
-				IP:       anotherIP,
+				IP:       anotherIP.AsSlice(),
 			})
 			testutil.AssertErrorMsg(t, wantErrMsg, err)
 		})
@@ -135,7 +136,7 @@ func TestV4Server_leasing(t *testing.T) {
 				dhcpv4.WithOption(dhcpv4.OptHostName(name)),
 				dhcpv4.WithOption(dhcpv4.OptRequestedIPAddress(ip)),
 				dhcpv4.WithOption(dhcpv4.OptClientIdentifier([]byte{1, 2, 3, 4, 5, 6, 8})),
-				dhcpv4.WithGatewayIP(DefaultGatewayIP),
+				dhcpv4.WithGatewayIP(DefaultGatewayIP.AsSlice()),
 			)
 			require.NoError(t, err)
 
@@ -150,7 +151,7 @@ func TestV4Server_leasing(t *testing.T) {
 		}
 
 		t.Run("same_name", func(t *testing.T) {
-			resp := discoverAnOffer(t, staticName, anotherIP, anotherMAC)
+			resp := discoverAnOffer(t, staticName, anotherIP.AsSlice(), anotherMAC)
 
 			req, err := dhcpv4.NewRequestFromOffer(resp, dhcpv4.WithOption(
 				dhcpv4.OptHostName(staticName),
@@ -164,7 +165,7 @@ func TestV4Server_leasing(t *testing.T) {
 		})
 
 		t.Run("same_mac", func(t *testing.T) {
-			resp := discoverAnOffer(t, anotherName, anotherIP, staticMAC)
+			resp := discoverAnOffer(t, anotherName, anotherIP.AsSlice(), staticMAC)
 
 			req, err := dhcpv4.NewRequestFromOffer(resp, dhcpv4.WithOption(
 				dhcpv4.OptHostName(anotherName),
@@ -219,7 +220,7 @@ func TestV4Server_AddRemove_static(t *testing.T) {
 		lease: &Lease{
 			Hostname: "probably-router.local",
 			HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-			IP:       DefaultGatewayIP,
+			IP:       DefaultGatewayIP.AsSlice(),
 		},
 		name: "with_gateway_ip",
 		wantErrMsg: "dhcpv4: adding static lease: " +
@@ -326,7 +327,7 @@ func TestV4_AddReplace(t *testing.T) {
 }
 
 func TestV4Server_handle_optionsPriority(t *testing.T) {
-	defaultIP := net.IP{192, 168, 1, 1}
+	defaultIP := netip.MustParseAddr("192.168.1.1")
 	knownIP := net.IP{1, 2, 3, 4}
 
 	// prepareSrv creates a *v4Server and sets the opt6IPs in the initial
@@ -343,14 +344,14 @@ func TestV4Server_handle_optionsPriority(t *testing.T) {
 			}
 			conf.Options = []string{b.String()}
 		} else {
-			defer func() { s.implicitOpts.Update(dhcpv4.OptDNS(defaultIP)) }()
+			defer func() { s.implicitOpts.Update(dhcpv4.OptDNS(defaultIP.AsSlice())) }()
 		}
 
 		var err error
 		s, err = v4Create(conf)
 		require.NoError(t, err)
 
-		s.conf.dnsIPAddrs = []net.IP{defaultIP}
+		s.conf.dnsIPAddrs = []netip.Addr{defaultIP}
 
 		return s
 	}
@@ -386,7 +387,7 @@ func TestV4Server_handle_optionsPriority(t *testing.T) {
 	t.Run("default", func(t *testing.T) {
 		s := prepareSrv(t, nil)
 
-		checkResp(t, s, []net.IP{defaultIP})
+		checkResp(t, s, []net.IP{defaultIP.AsSlice()})
 	})
 
 	t.Run("explicitly_configured", func(t *testing.T) {
@@ -506,8 +507,9 @@ func TestV4StaticLease_Get(t *testing.T) {
 	s, ok := sIface.(*v4Server)
 	require.True(t, ok)
 
-	s.conf.dnsIPAddrs = []net.IP{{192, 168, 10, 1}}
+	dnsAddr := netip.MustParseAddr("192.168.10.1")
-	s.implicitOpts.Update(dhcpv4.OptDNS(s.conf.dnsIPAddrs...))
+	s.conf.dnsIPAddrs = []netip.Addr{dnsAddr}
+	s.implicitOpts.Update(dhcpv4.OptDNS(dnsAddr.AsSlice()))
 
 	l := &Lease{
 		Hostname: "static-1.local",
@@ -539,9 +541,12 @@ func TestV4StaticLease_Get(t *testing.T) {
 		assert.Equal(t, dhcpv4.MessageTypeOffer, resp.MessageType())
 		assert.Equal(t, mac, resp.ClientHWAddr)
 		assert.True(t, l.IP.Equal(resp.YourIPAddr))
-		assert.True(t, s.conf.GatewayIP.Equal(resp.Router()[0]))
+
-		assert.True(t, s.conf.GatewayIP.Equal(resp.ServerIdentifier()))
+		assert.True(t, resp.Router()[0].Equal(s.conf.GatewayIP.AsSlice()))
-		assert.Equal(t, s.conf.subnet.Mask, resp.SubnetMask())
+		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
+
+		ones, _ := resp.SubnetMask().Size()
+		assert.Equal(t, s.conf.subnet.Bits(), ones)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), resp.IPAddressLeaseTime(-1).Seconds())
 	})
 
@@ -561,16 +566,19 @@ func TestV4StaticLease_Get(t *testing.T) {
 		assert.Equal(t, dhcpv4.MessageTypeAck, resp.MessageType())
 		assert.Equal(t, mac, resp.ClientHWAddr)
 		assert.True(t, l.IP.Equal(resp.YourIPAddr))
-		assert.True(t, s.conf.GatewayIP.Equal(resp.Router()[0]))
+
-		assert.True(t, s.conf.GatewayIP.Equal(resp.ServerIdentifier()))
+		assert.True(t, resp.Router()[0].Equal(s.conf.GatewayIP.AsSlice()))
-		assert.Equal(t, s.conf.subnet.Mask, resp.SubnetMask())
+		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
+
+		ones, _ := resp.SubnetMask().Size()
+		assert.Equal(t, s.conf.subnet.Bits(), ones)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), resp.IPAddressLeaseTime(-1).Seconds())
 	})
 
 	dnsAddrs := resp.DNS()
 	require.Len(t, dnsAddrs, 1)
 
-	assert.True(t, s.conf.GatewayIP.Equal(dnsAddrs[0]))
+	assert.True(t, dnsAddrs[0].Equal(s.conf.GatewayIP.AsSlice()))
 
 	t.Run("check_lease", func(t *testing.T) {
 		ls := s.GetLeases(LeasesStatic)
@@ -591,8 +599,8 @@ func TestV4DynamicLease_Get(t *testing.T) {
 	s, err := v4Create(conf)
 	require.NoError(t, err)
 
-	s.conf.dnsIPAddrs = []net.IP{{192, 168, 10, 1}}
+	s.conf.dnsIPAddrs = []netip.Addr{netip.MustParseAddr("192.168.10.1")}
-	s.implicitOpts.Update(dhcpv4.OptDNS(s.conf.dnsIPAddrs...))
+	s.implicitOpts.Update(dhcpv4.OptDNS(s.conf.dnsIPAddrs[0].AsSlice()))
 
 	var req, resp *dhcpv4.DHCPv4
 	mac := net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}
@@ -617,15 +625,16 @@ func TestV4DynamicLease_Get(t *testing.T) {
 		assert.Equal(t, dhcpv4.MessageTypeOffer, resp.MessageType())
 		assert.Equal(t, mac, resp.ClientHWAddr)
 
-		assert.Equal(t, s.conf.RangeStart, resp.YourIPAddr)
+		assert.True(t, resp.YourIPAddr.Equal(s.conf.RangeStart.AsSlice()))
-		assert.Equal(t, s.conf.GatewayIP, resp.ServerIdentifier())
+		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
 
 		router := resp.Router()
 		require.Len(t, router, 1)
 
-		assert.Equal(t, s.conf.GatewayIP, router[0])
+		assert.True(t, router[0].Equal(s.conf.GatewayIP.AsSlice()))
 
-		assert.Equal(t, s.conf.subnet.Mask, resp.SubnetMask())
+		ones, _ := resp.SubnetMask().Size()
+		assert.Equal(t, s.conf.subnet.Bits(), ones)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), resp.IPAddressLeaseTime(-1).Seconds())
 		assert.Equal(t, []byte("012"), resp.Options.Get(dhcpv4.OptionFQDN))
 
@@ -649,15 +658,17 @@ func TestV4DynamicLease_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, s.conf.RangeStart.Equal(resp.YourIPAddr))
+		assert.True(t, resp.YourIPAddr.Equal(s.conf.RangeStart.AsSlice()))
 
 		router := resp.Router()
 		require.Len(t, router, 1)
 
-		assert.Equal(t, s.conf.GatewayIP, router[0])
+		assert.True(t, router[0].Equal(s.conf.GatewayIP.AsSlice()))
 
-		assert.True(t, s.conf.GatewayIP.Equal(resp.ServerIdentifier()))
+		assert.True(t, resp.ServerIdentifier().Equal(s.conf.GatewayIP.AsSlice()))
-		assert.Equal(t, s.conf.subnet.Mask, resp.SubnetMask())
+
+		ones, _ := resp.SubnetMask().Size()
+		assert.Equal(t, s.conf.subnet.Bits(), ones)
 		assert.Equal(t, s.conf.leaseTime.Seconds(), resp.IPAddressLeaseTime(-1).Seconds())
 	})
 

internal/dnsforward/access.go

@@ -19,6 +19,7 @@ import (
 // accessCtx controls IP and client blocking that takes place before all other
 // processing.  An accessCtx is safe for concurrent use.
 type accessCtx struct {
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	allowedIPs *netutil.IPMap
 	blockedIPs *netutil.IPMap
 

internal/dnsforward/dnsforward.go

@@ -81,6 +81,7 @@ type Server struct {
 	tableHostToIP     hostToIPTable
 	tableHostToIPLock sync.Mutex
 
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	tableIPToHost     *netutil.IPMap
 	tableIPToHostLock sync.Mutex
 

internal/home/clients.go

@@ -119,6 +119,8 @@ type clientsContainer struct {
 	idIndex map[string]*Client // ID -> client
 
 	// ipToRC is the IP address to *RuntimeClient map.
+	//
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	ipToRC *netutil.IPMap
 
 	lock sync.Mutex

internal/home/clients_test.go

@@ -2,6 +2,7 @@ package home
 
 import (
 	"net"
+	"net/netip"
 	"os"
 	"runtime"
 	"testing"
@@ -287,10 +288,10 @@ func TestClientsAddExisting(t *testing.T) {
 			DBFilePath: "leases.db",
 			Conf4: dhcpd.V4ServerConf{
 				Enabled:    true,
-				GatewayIP:  net.IP{1, 2, 3, 1},
+				GatewayIP:  netip.MustParseAddr("1.2.3.1"),
-				SubnetMask: net.IP{255, 255, 255, 0},
+				SubnetMask: netip.MustParseAddr("255.255.255.0"),
-				RangeStart: net.IP{1, 2, 3, 2},
+				RangeStart: netip.MustParseAddr("1.2.3.2"),
-				RangeEnd:   net.IP{1, 2, 3, 10},
+				RangeEnd:   netip.MustParseAddr("1.2.3.10"),
 			},
 		}
 

internal/home/config.go

@@ -3,7 +3,7 @@ package home
 import (
 	"bytes"
 	"fmt"
-	"net"
+	"net/netip"
 	"os"
 	"path/filepath"
 	"sync"
@@ -85,19 +85,28 @@ type configuration struct {
 	// It's reset after config is parsed
 	fileData []byte
 
-	BindHost     net.IP    `yaml:"bind_host"`      // BindHost is the IP address of the HTTP server to bind to
+	// BindHost is the address for the web interface server to listen on.
-	BindPort     int       `yaml:"bind_port"`      // BindPort is the port the HTTP server
+	BindHost netip.Addr `yaml:"bind_host"`
-	BetaBindPort int       `yaml:"beta_bind_port"` // BetaBindPort is the port for new client
+	// BindPort is the port for the web interface server to listen on.
-	Users        []webUser `yaml:"users"`          // Users that can access HTTP server
+	BindPort int `yaml:"bind_port"`
+	// BetaBindPort is the port for the new client's web interface server to
+	// listen on.
+	BetaBindPort int `yaml:"beta_bind_port"`
+
+	// Users are the clients capable for accessing the web interface.
+	Users []webUser `yaml:"users"`
 	// AuthAttempts is the maximum number of failed login attempts a user
 	// can do before being blocked.
 	AuthAttempts uint `yaml:"auth_attempts"`
 	// AuthBlockMin is the duration, in minutes, of the block of new login
 	// attempts after AuthAttempts unsuccessful login attempts.
-	AuthBlockMin uint   `yaml:"block_auth_min"`
+	AuthBlockMin uint `yaml:"block_auth_min"`
-	ProxyURL     string `yaml:"http_proxy"`  // Proxy address for our HTTP client
+	// ProxyURL is the address of proxy server for the internal HTTP client.
-	Language     string `yaml:"language"`    // two-letter ISO 639-1 language code
+	ProxyURL string `yaml:"http_proxy"`
-	DebugPProf   bool   `yaml:"debug_pprof"` // Enable pprof HTTP server on port 6060
+	// Language is a two-letter ISO 639-1 language code.
+	Language string `yaml:"language"`
+	// DebugPProf defines if the profiling HTTP handler will listen on :6060.
+	DebugPProf bool `yaml:"debug_pprof"`
 
 	// TTL for a web session (in hours)
 	// An active session is automatically refreshed once a day.
@@ -112,7 +121,7 @@ type configuration struct {
 	//
 	// TODO(e.burkov):  Move all the filtering configuration fields into the
 	// only configuration subsection covering the changes with a single
-	// migration.
+	// migration.  Also keep the blocked services in mind.
 	Filters          []filtering.FilterYAML `yaml:"filters"`
 	WhitelistFilters []filtering.FilterYAML `yaml:"whitelist_filters"`
 	UserRules        []string               `yaml:"user_rules"`
@@ -135,18 +144,26 @@ type configuration struct {
 
 // field ordering is important -- yaml fields will mirror ordering from here
 type dnsConfig struct {
-	BindHosts []net.IP `yaml:"bind_hosts"`
+	BindHosts []netip.Addr `yaml:"bind_hosts"`
-	Port      int      `yaml:"port"`
+	Port      int          `yaml:"port"`
 
-	// time interval for statistics (in days)
+	// StatsInterval is the time interval for flushing statistics to the disk in
+	// days.
 	StatsInterval uint32 `yaml:"statistics_interval"`
 
-	QueryLogEnabled     bool `yaml:"querylog_enabled"`      // if true, query log is enabled
+	// QueryLogEnabled defines if the query log is enabled.
-	QueryLogFileEnabled bool `yaml:"querylog_file_enabled"` // if true, query log will be written to a file
+	QueryLogEnabled bool `yaml:"querylog_enabled"`
+	// QueryLogFileEnabled defines, if the query log is written to the file.
+	QueryLogFileEnabled bool `yaml:"querylog_file_enabled"`
 	// QueryLogInterval is the interval for query log's files rotation.
-	QueryLogInterval  timeutil.Duration `yaml:"querylog_interval"`
+	QueryLogInterval timeutil.Duration `yaml:"querylog_interval"`
-	QueryLogMemSize   uint32            `yaml:"querylog_size_memory"` // number of entries kept in memory before they are flushed to disk
+	// QueryLogMemSize is the number of entries kept in memory before they are
-	AnonymizeClientIP bool              `yaml:"anonymize_client_ip"`  // anonymize clients' IP addresses in logs and stats
+	// flushed to disk.
+	QueryLogMemSize uint32 `yaml:"querylog_size_memory"`
+
+	// AnonymizeClientIP defines if clients' IP addresses should be anonymized
+	// in query log and statistics.
+	AnonymizeClientIP bool `yaml:"anonymize_client_ip"`
 
 	dnsforward.FilteringConfig `yaml:",inline"`
 
@@ -211,12 +228,12 @@ type tlsConfigSettings struct {
 var config = &configuration{
 	BindPort:           3000,
 	BetaBindPort:       0,
-	BindHost:           net.IP{0, 0, 0, 0},
+	BindHost:           netip.IPv4Unspecified(),
 	AuthAttempts:       5,
 	AuthBlockMin:       15,
 	WebSessionTTLHours: 30 * 24,
 	DNS: dnsConfig{
-		BindHosts:           []net.IP{{0, 0, 0, 0}},
+		BindHosts:           []netip.Addr{netip.IPv4Unspecified()},
 		Port:                defaultPortDNS,
 		StatsInterval:       1,
 		QueryLogEnabled:     true,

internal/home/control.go

@@ -2,8 +2,8 @@ package home
 
 import (
 	"fmt"
-	"net"
 	"net/http"
+	"net/netip"
 	"net/url"
 	"runtime"
 	"strings"
@@ -20,11 +20,11 @@ import (
 
 // appendDNSAddrs is a convenient helper for appending a formatted form of DNS
 // addresses to a slice of strings.
-func appendDNSAddrs(dst []string, addrs ...net.IP) (res []string) {
+func appendDNSAddrs(dst []string, addrs ...netip.Addr) (res []string) {
 	for _, addr := range addrs {
 		var hostport string
 		if config.DNS.Port != defaultPortDNS {
-			hostport = netutil.JoinHostPort(addr.String(), config.DNS.Port)
+			hostport = netip.AddrPortFrom(addr, uint16(config.DNS.Port)).String()
 		} else {
 			hostport = addr.String()
 		}
@@ -38,7 +38,7 @@ func appendDNSAddrs(dst []string, addrs ...net.IP) (res []string) {
 // appendDNSAddrsWithIfaces formats and appends all DNS addresses from src to
 // dst.  It also adds the IP addresses of all network interfaces if src contains
 // an unspecified IP address.
-func appendDNSAddrsWithIfaces(dst []string, src []net.IP) (res []string, err error) {
+func appendDNSAddrsWithIfaces(dst []string, src []netip.Addr) (res []string, err error) {
 	ifacesAdded := false
 	for _, h := range src {
 		if !h.IsUnspecified() {
@@ -71,7 +71,9 @@ func appendDNSAddrsWithIfaces(dst []string, src []net.IP) (res []string, err err
 // on, including the addresses on all interfaces in cases of unspecified IPs.
 func collectDNSAddresses() (addrs []string, err error) {
 	if hosts := config.DNS.BindHosts; len(hosts) == 0 {
-		addrs = appendDNSAddrs(addrs, net.IP{127, 0, 0, 1})
+		addr := aghnet.IPv4Localhost()
+
+		addrs = appendDNSAddrs(addrs, addr)
 	} else {
 		addrs, err = appendDNSAddrsWithIfaces(addrs, hosts)
 		if err != nil {

internal/home/controlinstall.go

@@ -5,8 +5,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"net"
 	"net/http"
+	"net/netip"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -64,9 +64,9 @@ func (web *Web) handleInstallGetAddresses(w http.ResponseWriter, r *http.Request
 }
 
 type checkConfReqEnt struct {
-	IP      net.IP `json:"ip"`
+	IP      netip.Addr `json:"ip"`
-	Port    int    `json:"port"`
+	Port    int        `json:"port"`
-	Autofix bool   `json:"autofix"`
+	Autofix bool       `json:"autofix"`
 }
 
 type checkConfReq struct {
@@ -117,7 +117,7 @@ func (req *checkConfReq) validateWeb(tcpPorts aghalg.UniqChecker[tcpPort]) (err
 		// unbound after install.
 	}
 
-	return aghnet.CheckPort("tcp", req.Web.IP, portInt)
+	return aghnet.CheckPort("tcp", netip.AddrPortFrom(req.Web.IP, uint16(portInt)))
 }
 
 // validateDNS returns error if the DNS part of the initial configuration can't
@@ -142,13 +142,13 @@ func (req *checkConfReq) validateDNS(
 			return false, err
 		}
 
-		err = aghnet.CheckPort("tcp", req.DNS.IP, port)
+		err = aghnet.CheckPort("tcp", netip.AddrPortFrom(req.DNS.IP, uint16(port)))
 		if err != nil {
 			return false, err
 		}
 	}
 
-	err = aghnet.CheckPort("udp", req.DNS.IP, port)
+	err = aghnet.CheckPort("udp", netip.AddrPortFrom(req.DNS.IP, uint16(port)))
 	if !aghnet.IsAddrInUse(err) {
 		return false, err
 	}
@@ -160,7 +160,7 @@ func (req *checkConfReq) validateDNS(
 			log.Error("disabling DNSStubListener: %s", err)
 		}
 
-		err = aghnet.CheckPort("udp", req.DNS.IP, port)
+		err = aghnet.CheckPort("udp", netip.AddrPortFrom(req.DNS.IP, uint16(port)))
 		canAutofix = false
 	}
 
@@ -196,7 +196,7 @@ func (web *Web) handleInstallCheckConfig(w http.ResponseWriter, r *http.Request)
 // handleStaticIP - handles static IP request
 // It either checks if we have a static IP
 // Or if set=true, it tries to set it
-func handleStaticIP(ip net.IP, set bool) staticIPJSON {
+func handleStaticIP(ip netip.Addr, set bool) staticIPJSON {
 	resp := staticIPJSON{}
 
 	interfaceName := aghnet.InterfaceByIP(ip)
@@ -304,8 +304,8 @@ func disableDNSStubListener() error {
 }
 
 type applyConfigReqEnt struct {
-	IP   net.IP `json:"ip"`
+	IP   netip.Addr `json:"ip"`
-	Port int    `json:"port"`
+	Port int        `json:"port"`
 }
 
 type applyConfigReq struct {
@@ -397,14 +397,14 @@ func (web *Web) handleInstallConfigure(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	err = aghnet.CheckPort("udp", req.DNS.IP, req.DNS.Port)
+	err = aghnet.CheckPort("udp", netip.AddrPortFrom(req.DNS.IP, uint16(req.DNS.Port)))
 	if err != nil {
 		aghhttp.Error(r, w, http.StatusBadRequest, "%s", err)
 
 		return
 	}
 
-	err = aghnet.CheckPort("tcp", req.DNS.IP, req.DNS.Port)
+	err = aghnet.CheckPort("tcp", netip.AddrPortFrom(req.DNS.IP, uint16(req.DNS.Port)))
 	if err != nil {
 		aghhttp.Error(r, w, http.StatusBadRequest, "%s", err)
 
@@ -417,7 +417,7 @@ func (web *Web) handleInstallConfigure(w http.ResponseWriter, r *http.Request) {
 	Context.firstRun = false
 	config.BindHost = req.Web.IP
 	config.BindPort = req.Web.Port
-	config.DNS.BindHosts = []net.IP{req.DNS.IP}
+	config.DNS.BindHosts = []netip.Addr{req.DNS.IP}
 	config.DNS.Port = req.DNS.Port
 
 	// TODO(e.burkov): StartMods() should be put in a separate goroutine at the
@@ -490,9 +490,9 @@ func decodeApplyConfigReq(r io.Reader) (req *applyConfigReq, restartHTTP bool, e
 		return nil, false, errors.Error("ports cannot be 0")
 	}
 
-	restartHTTP = !config.BindHost.Equal(req.Web.IP) || config.BindPort != req.Web.Port
+	restartHTTP = config.BindHost != req.Web.IP || config.BindPort != req.Web.Port
 	if restartHTTP {
-		err = aghnet.CheckPort("tcp", req.Web.IP, req.Web.Port)
+		err = aghnet.CheckPort("tcp", netip.AddrPortFrom(req.Web.IP, uint16(req.Web.Port)))
 		if err != nil {
 			return nil, false, fmt.Errorf(
 				"checking address %s:%d: %w",
@@ -518,9 +518,9 @@ func (web *Web) registerInstallHandlers() {
 // TODO(e.burkov): This should removed with the API v1 when the appropriate
 // functionality will appear in default checkConfigReqEnt.
 type checkConfigReqEntBeta struct {
-	IP      []net.IP `json:"ip"`
+	IP      []netip.Addr `json:"ip"`
-	Port    int      `json:"port"`
+	Port    int          `json:"port"`
-	Autofix bool     `json:"autofix"`
+	Autofix bool         `json:"autofix"`
 }
 
 // checkConfigReqBeta is a struct representing new client's config check request
@@ -590,8 +590,8 @@ func (web *Web) handleInstallCheckConfigBeta(w http.ResponseWriter, r *http.Requ
 // TODO(e.burkov): This should removed with the API v1 when the appropriate
 // functionality will appear in default applyConfigReqEnt.
 type applyConfigReqEntBeta struct {
-	IP   []net.IP `json:"ip"`
+	IP   []netip.Addr `json:"ip"`
-	Port int      `json:"port"`
+	Port int          `json:"port"`
 }
 
 // applyConfigReqBeta is a struct representing new client's config setting

internal/home/dns.go

@@ -3,6 +3,7 @@ package home
 import (
 	"fmt"
 	"net"
+	"net/netip"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -164,33 +165,27 @@ func onDNSRequest(pctx *proxy.DNSContext) {
 	}
 }
 
-func ipsToTCPAddrs(ips []net.IP, port int) (tcpAddrs []*net.TCPAddr) {
+func ipsToTCPAddrs(ips []netip.Addr, port int) (tcpAddrs []*net.TCPAddr) {
 	if ips == nil {
 		return nil
 	}
 
-	tcpAddrs = make([]*net.TCPAddr, len(ips))
+	tcpAddrs = make([]*net.TCPAddr, 0, len(ips))
-	for i, ip := range ips {
+	for _, ip := range ips {
-		tcpAddrs[i] = &net.TCPAddr{
+		tcpAddrs = append(tcpAddrs, net.TCPAddrFromAddrPort(netip.AddrPortFrom(ip, uint16(port))))
-			IP:   ip,
-			Port: port,
-		}
 	}
 
 	return tcpAddrs
 }
 
-func ipsToUDPAddrs(ips []net.IP, port int) (udpAddrs []*net.UDPAddr) {
+func ipsToUDPAddrs(ips []netip.Addr, port int) (udpAddrs []*net.UDPAddr) {
 	if ips == nil {
 		return nil
 	}
 
-	udpAddrs = make([]*net.UDPAddr, len(ips))
+	udpAddrs = make([]*net.UDPAddr, 0, len(ips))
-	for i, ip := range ips {
+	for _, ip := range ips {
-		udpAddrs[i] = &net.UDPAddr{
+		udpAddrs = append(udpAddrs, net.UDPAddrFromAddrPort(netip.AddrPortFrom(ip, uint16(port))))
-			IP:   ip,
-			Port: port,
-		}
 	}
 
 	return udpAddrs
@@ -200,7 +195,7 @@ func generateServerConfig() (newConf dnsforward.ServerConfig, err error) {
 	dnsConf := config.DNS
 	hosts := dnsConf.BindHosts
 	if len(hosts) == 0 {
-		hosts = []net.IP{{127, 0, 0, 1}}
+		hosts = []netip.Addr{aghnet.IPv4Localhost()}
 	}
 
 	newConf = dnsforward.ServerConfig{
@@ -257,7 +252,7 @@ func generateServerConfig() (newConf dnsforward.ServerConfig, err error) {
 	return newConf, nil
 }
 
-func newDNSCrypt(hosts []net.IP, tlsConf tlsConfigSettings) (dnscc dnsforward.DNSCryptConfig, err error) {
+func newDNSCrypt(hosts []netip.Addr, tlsConf tlsConfigSettings) (dnscc dnsforward.DNSCryptConfig, err error) {
 	if tlsConf.DNSCryptConfigFile == "" {
 		return dnscc, errors.Error("no dnscrypt_config_file")
 	}

internal/home/home.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/pprof"
+	"net/netip"
 	"net/url"
 	"os"
 	"os/signal"
@@ -356,7 +357,7 @@ func setupConfig(opts options) (err error) {
 	}
 
 	// override bind host/port from the console
-	if opts.bindHost != nil {
+	if opts.bindHost.IsValid() {
 		config.BindHost = opts.bindHost
 	}
 	if len(opts.pidFile) != 0 && writePIDFile(opts.pidFile) {
@@ -556,7 +557,7 @@ func checkPermissions() {
 	}
 
 	// We should check if AdGuard Home is able to bind to port 53
-	err := aghnet.CheckPort("tcp", net.IP{127, 0, 0, 1}, defaultPortDNS)
+	err := aghnet.CheckPort("tcp", netip.AddrPortFrom(aghnet.IPv4Localhost(), defaultPortDNS))
 	if err != nil {
 		if errors.Is(err, os.ErrPermission) {
 			log.Fatal(`Permission check failed.

internal/home/mobileconfig_test.go

@@ -3,12 +3,11 @@ package home
 import (
 	"bytes"
 	"encoding/json"
-	"net"
 	"net/http"
 	"net/http/httptest"
+	"net/netip"
 	"testing"
 
-	"github.com/AdguardTeam/golibs/netutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"howett.net/plist"
@@ -28,7 +27,7 @@ func setupDNSIPs(t testing.TB) {
 
 	config = &configuration{
 		DNS: dnsConfig{
-			BindHosts: []net.IP{netutil.IPv4Zero()},
+			BindHosts: []netip.Addr{netip.IPv4Unspecified()},
 			Port:      defaultPortDNS,
 		},
 	}

internal/home/options.go

@@ -2,7 +2,7 @@ package home
 
 import (
 	"fmt"
-	"net"
+	"net/netip"
 	"os"
 	"strconv"
 	"strings"
@@ -35,7 +35,7 @@ type options struct {
 	serviceControlAction string
 
 	// bindHost is the address on which to serve the HTTP UI.
-	bindHost net.IP
+	bindHost netip.Addr
 
 	// bindPort is the port on which to serve the HTTP UI.
 	bindPort int
@@ -130,14 +130,15 @@ var cmdLineOpts = []cmdLineOpt{{
 	longName:        "work-dir",
 	shortName:       "w",
 }, {
-	updateWithValue: func(o options, v string) (options, error) {
+	updateWithValue: func(o options, v string) (oo options, err error) {
-		o.bindHost = net.ParseIP(v)
+		o.bindHost, err = netip.ParseAddr(v)
-		return o, nil
+
+		return o, err
 	},
 	updateNoValue: nil,
 	effect:        nil,
 	serialize: func(o options) (val string, ok bool) {
-		if o.bindHost == nil {
+		if !o.bindHost.IsValid() {
 			return "", false
 		}
 

internal/home/options_test.go

@@ -2,7 +2,7 @@ package home
 
 import (
 	"fmt"
-	"net"
+	"net/netip"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -56,11 +56,13 @@ func TestParseWorkDir(t *testing.T) {
 }
 
 func TestParseBindHost(t *testing.T) {
-	assert.Nil(t, testParseOK(t).bindHost, "empty is not host")
+	wantAddr := netip.MustParseAddr("1.2.3.4")
-	assert.Equal(t, net.IPv4(1, 2, 3, 4), testParseOK(t, "-h", "1.2.3.4").bindHost, "-h is host")
+
+	assert.Zero(t, testParseOK(t).bindHost, "empty is not host")
+	assert.Equal(t, wantAddr, testParseOK(t, "-h", "1.2.3.4").bindHost, "-h is host")
 	testParseParamMissing(t, "-h")
 
-	assert.Equal(t, net.IPv4(1, 2, 3, 4), testParseOK(t, "--host", "1.2.3.4").bindHost, "--host is host")
+	assert.Equal(t, wantAddr, testParseOK(t, "--host", "1.2.3.4").bindHost, "--host is host")
 	testParseParamMissing(t, "--host")
 }
 
@@ -149,8 +151,8 @@ func TestOptsToArgs(t *testing.T) {
 		opts: options{workDir: "path"},
 	}, {
 		name: "bind_host",
+		opts: options{bindHost: netip.MustParseAddr("1.2.3.4")},
 		args: []string{"-h", "1.2.3.4"},
-		opts: options{bindHost: net.IP{1, 2, 3, 4}},
 	}, {
 		name: "bind_port",
 		args: []string{"-p", "666"},

internal/home/web.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"crypto/tls"
 	"io/fs"
-	"net"
 	"net/http"
+	"net/netip"
 	"sync"
 	"time"
 
@@ -37,7 +37,7 @@ type webConfig struct {
 	clientFS     fs.FS
 	clientBetaFS fs.FS
 
-	BindHost     net.IP
+	BindHost     netip.Addr
 	BindPort     int
 	BetaBindPort int
 	PortHTTPS    int
@@ -135,8 +135,11 @@ func newWeb(conf *webConfig) (w *Web) {
 //
 // TODO(a.garipov): Adapt for HTTP/3.
 func webCheckPortAvailable(port int) (ok bool) {
-	return Context.web.httpsServer.server != nil ||
+	if Context.web.httpsServer.server != nil {
-		aghnet.CheckPort("tcp", config.BindHost, port) == nil
+		return true
+	}
+
+	return aghnet.CheckPort("tcp", netip.AddrPortFrom(config.BindHost, uint16(port))) == nil
 }
 
 // TLSConfigChanged updates the TLS configuration and restarts the HTTPS server