Pull request: 5035-netip-arp-hosts

Updates #5035.

Squashed commit of the following:

commit d1c4493ee4e28d05670c20532ebae1aa809d18da
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Oct 25 14:26:52 2022 +0300

    aghnet: imp hosts rec equal

commit 0a7f40a64a819245fba20d3b481b0fc34e0c60e6
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Oct 24 18:10:09 2022 +0300

    aghnet: move arp and hosts to netip.Addr

internal/aghnet/arpdb.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"fmt"
 	"net"
+	"net/netip"
 	"sync"
 
 	"github.com/AdguardTeam/golibs/errors"
@@ -54,7 +55,7 @@ type Neighbor struct {
 	Name string
 
 	// IP contains either IPv4 or IPv6.
-	IP net.IP
+	IP netip.Addr
 
 	// MAC contains the hardware address.
 	MAC net.HardwareAddr
@@ -64,7 +65,7 @@ type Neighbor struct {
 func (n Neighbor) Clone() (clone Neighbor) {
 	return Neighbor{
 		Name: n.Name,
-		IP:   slices.Clone(n.IP),
+		IP:   n.IP,
 		MAC:  slices.Clone(n.MAC),
 	}
 }

internal/aghnet/arpdb_bsd.go

@@ -5,6 +5,7 @@ package aghnet
 import (
 	"bufio"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 
@@ -47,22 +48,28 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		if ipStr := fields[1]; len(ipStr) < 2 {
 			continue
-		} else if ip := net.ParseIP(ipStr[1 : len(ipStr)-1]); ip == nil {
+		} else if ip, err := netip.ParseAddr(ipStr[1 : len(ipStr)-1]); err != nil {
+			log.Debug("arpdb: parsing arp output: ip: %s", err)
+
 			continue
 		} else {
 			n.IP = ip
 		}
 
 		hwStr := fields[3]
-		if mac, err := net.ParseMAC(hwStr); err != nil {
+		mac, err := net.ParseMAC(hwStr)
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: mac: %s", err)
+
 			continue
 		} else {
 			n.MAC = mac
 		}
 
 		host := fields[0]
-		if err := netutil.ValidateDomainName(host); err != nil {
+		err = netutil.ValidateDomainName(host)
-			log.Debug("parsing arp output: %s", err)
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: host: %s", err)
 		} else {
 			n.Name = host
 		}

internal/aghnet/arpdb_bsd_test.go

@@ -4,6 +4,7 @@ package aghnet
 
 import (
 	"net"
+	"net/netip"
 )
 
 const arpAOutput = `
@@ -17,14 +18,14 @@ hostname.two (::ffff:ffff) at ef:cd:ab:ef:cd:ab on em0 expires in 1198 seconds [
 
 var wantNeighs = []Neighbor{{
 	Name: "hostname.one",
-	IP:   net.IPv4(192, 168, 1, 2),
+	IP:   netip.MustParseAddr("192.168.1.2"),
 	MAC:  net.HardwareAddr{0xAB, 0xCD, 0xEF, 0xAB, 0xCD, 0xEF},
 }, {
 	Name: "hostname.two",
-	IP:   net.ParseIP("::ffff:ffff"),
+	IP:   netip.MustParseAddr("::ffff:ffff"),
 	MAC:  net.HardwareAddr{0xEF, 0xCD, 0xAB, 0xEF, 0xCD, 0xAB},
 }, {
 	Name: "",
-	IP:   net.ParseIP("::1234"),
+	IP:   netip.MustParseAddr("::1234"),
 	MAC:  net.HardwareAddr{0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
 }}

internal/aghnet/arpdb_linux.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io/fs"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 
@@ -94,7 +95,8 @@ func (arp *fsysARPDB) Refresh() (err error) {
 		}
 
 		n := Neighbor{}
-		if n.IP = net.ParseIP(fields[0]); n.IP == nil || n.IP.IsUnspecified() {
+		n.IP, err = netip.ParseAddr(fields[0])
+		if err != nil || n.IP.IsUnspecified() {
 			continue
 		} else if n.MAC, err = net.ParseMAC(fields[3]); err != nil {
 			continue
@@ -135,15 +137,19 @@ func parseArpAWrt(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		n := Neighbor{}
 
-		if ip := net.ParseIP(fields[0]); ip == nil || n.IP.IsUnspecified() {
+		ip, err := netip.ParseAddr(fields[0])
+		if err != nil || n.IP.IsUnspecified() {
+			log.Debug("arpdb: parsing arp output: ip: %s", err)
+
 			continue
 		} else {
 			n.IP = ip
 		}
 
 		hwStr := fields[3]
-		if mac, err := net.ParseMAC(hwStr); err != nil {
+		mac, err := net.ParseMAC(hwStr)
-			log.Debug("parsing arp output: %s", err)
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: mac: %s", err)
 
 			continue
 		} else {
@@ -174,7 +180,9 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		if ipStr := fields[1]; len(ipStr) < 2 {
 			continue
-		} else if ip := net.ParseIP(ipStr[1 : len(ipStr)-1]); ip == nil {
+		} else if ip, err := netip.ParseAddr(ipStr[1 : len(ipStr)-1]); err != nil {
+			log.Debug("arpdb: parsing arp output: ip: %s", err)
+
 			continue
 		} else {
 			n.IP = ip
@@ -182,7 +190,7 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		hwStr := fields[3]
 		if mac, err := net.ParseMAC(hwStr); err != nil {
-			log.Debug("parsing arp output: %s", err)
+			log.Debug("arpdb: parsing arp output: mac: %s", err)
 
 			continue
 		} else {
@@ -191,7 +199,7 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		host := fields[0]
 		if verr := netutil.ValidateDomainName(host); verr != nil {
-			log.Debug("parsing arp output: %s", verr)
+			log.Debug("arpdb: parsing arp output: host: %s", verr)
 		} else {
 			n.Name = host
 		}
@@ -218,14 +226,18 @@ func parseIPNeigh(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		n := Neighbor{}
 
-		if ip := net.ParseIP(fields[0]); ip == nil {
+		ip, err := netip.ParseAddr(fields[0])
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: ip: %s", err)
+
 			continue
 		} else {
 			n.IP = ip
 		}
 
-		if mac, err := net.ParseMAC(fields[4]); err != nil {
+		mac, err := net.ParseMAC(fields[4])
-			log.Debug("parsing arp output: %s", err)
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: mac: %s", err)
 
 			continue
 		} else {

internal/aghnet/arpdb_linux_test.go

@@ -4,6 +4,7 @@ package aghnet
 
 import (
 	"net"
+	"net/netip"
 	"sync"
 	"testing"
 	"testing/fstest"
@@ -33,10 +34,10 @@ const ipNeighOutput = `
 ::ffff:ffff dev enp0s3 lladdr ef:cd:ab:ef:cd:ab router STALE`
 
 var wantNeighs = []Neighbor{{
-	IP:  net.IPv4(192, 168, 1, 2),
+	IP:  netip.MustParseAddr("192.168.1.2"),
 	MAC: net.HardwareAddr{0xAB, 0xCD, 0xEF, 0xAB, 0xCD, 0xEF},
 }, {
-	IP:  net.ParseIP("::ffff:ffff"),
+	IP:  netip.MustParseAddr("::ffff:ffff"),
 	MAC: net.HardwareAddr{0xEF, 0xCD, 0xAB, 0xEF, 0xCD, 0xAB},
 }}
 

internal/aghnet/arpdb_openbsd.go

@@ -5,6 +5,7 @@ package aghnet
 import (
 	"bufio"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 
@@ -50,14 +51,18 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		n := Neighbor{}
 
-		if ip := net.ParseIP(fields[0]); ip == nil {
+		ip, err := netip.ParseAddr(fields[0])
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: ip: %s", err)
+
 			continue
 		} else {
 			n.IP = ip
 		}
 
-		if mac, err := net.ParseMAC(fields[1]); err != nil {
+		mac, err := net.ParseMAC(fields[1])
-			log.Debug("parsing arp output: %s", err)
+		if err != nil {
+			log.Debug("arpdb: parsing arp output: mac: %s", err)
 
 			continue
 		} else {

internal/aghnet/arpdb_openbsd_test.go

@@ -4,6 +4,7 @@ package aghnet
 
 import (
 	"net"
+	"net/netip"
 )
 
 const arpAOutput = `
@@ -15,9 +16,9 @@ Host        Ethernet Address  Netif Expire    Flags
 `
 
 var wantNeighs = []Neighbor{{
-	IP:  net.IPv4(192, 168, 1, 2),
+	IP:  netip.MustParseAddr("192.168.1.2"),
 	MAC: net.HardwareAddr{0xAB, 0xCD, 0xEF, 0xAB, 0xCD, 0xEF},
 }, {
-	IP:  net.ParseIP("::ffff:ffff"),
+	IP:  netip.MustParseAddr("::ffff:ffff"),
 	MAC: net.HardwareAddr{0xEF, 0xCD, 0xAB, 0xEF, 0xCD, 0xAB},
 }}

internal/aghnet/arpdb_test.go

@@ -2,6 +2,7 @@ package aghnet
 
 import (
 	"net"
+	"net/netip"
 	"sync"
 	"testing"
 
@@ -35,7 +36,7 @@ func (arp *TestARPDB) Neighbors() (ns []Neighbor) {
 }
 
 func TestARPDBS(t *testing.T) {
-	knownIP := net.IP{1, 2, 3, 4}
+	knownIP := netip.MustParseAddr("1.2.3.4")
 	knownMAC := net.HardwareAddr{0xAB, 0xCD, 0xEF, 0xAB, 0xCD, 0xEF}
 
 	succRefrCount, failRefrCount := 0, 0

internal/aghnet/arpdb_windows.go

@@ -5,6 +5,7 @@ package aghnet
 import (
 	"bufio"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 )
@@ -43,13 +44,15 @@ func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 
 		n := Neighbor{}
 
-		if ip := net.ParseIP(fields[0]); ip == nil {
+		ip, err := netip.ParseAddr(fields[0])
+		if err != nil {
 			continue
 		} else {
 			n.IP = ip
 		}
 
-		if mac, err := net.ParseMAC(fields[1]); err != nil {
+		mac, err := net.ParseMAC(fields[1])
+		if err != nil {
 			continue
 		} else {
 			n.MAC = mac

internal/aghnet/arpdb_windows_test.go

@@ -4,6 +4,7 @@ package aghnet
 
 import (
 	"net"
+	"net/netip"
 )
 
 const arpAOutput = `
@@ -14,9 +15,9 @@ Interface: 192.168.1.1 --- 0x7
   ::ffff:ffff           ef-cd-ab-ef-cd-ab     static`
 
 var wantNeighs = []Neighbor{{
-	IP:  net.IPv4(192, 168, 1, 2),
+	IP:  netip.MustParseAddr("192.168.1.2"),
 	MAC: net.HardwareAddr{0xAB, 0xCD, 0xEF, 0xAB, 0xCD, 0xEF},
 }, {
-	IP:  net.ParseIP("::ffff:ffff"),
+	IP:  netip.MustParseAddr("::ffff:ffff"),
 	MAC: net.HardwareAddr{0xEF, 0xCD, 0xAB, 0xEF, 0xCD, 0xAB},
 }}

internal/aghnet/hostscontainer.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"net"
+	"net/netip"
 	"path"
 	"strings"
 	"sync"
@@ -19,10 +19,9 @@ import (
 	"github.com/AdguardTeam/urlfilter/filterlist"
 	"github.com/AdguardTeam/urlfilter/rules"
 	"github.com/miekg/dns"
+	"golang.org/x/exp/maps"
 )
 
-//lint:file-ignore SA1019 TODO(a.garipov):  Replace [*netutil.IPMap].
-
 // DefaultHostsPaths returns the slice of paths default for the operating system
 // to files and directories which are containing the hosts database.  The result
 // is intended to be used within fs.FS so the initial slash is omitted.
@@ -108,14 +107,10 @@ type HostsContainer struct {
 	done chan struct{}
 
 	// updates is the channel for receiving updated hosts.
-	//
+	updates chan HostsRecords
-	// 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.
-	//
+	last HostsRecords
-	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
-	last *netutil.IPMap
 
 	// fsys is the working file system to read hosts files from.
 	fsys fs.FS
@@ -130,6 +125,25 @@ type HostsContainer struct {
 	listID int
 }
 
+// HostsRecords is a mapping of an IP address to its hosts data.
+type HostsRecords map[netip.Addr]*HostsRecord
+
+// HostsRecord represents a single hosts file record.
+type HostsRecord struct {
+	Aliases   *stringutil.Set
+	Canonical string
+}
+
+// equal returns true if all fields of rec are equal to field in other or they
+// both are nil.
+func (rec *HostsRecord) equal(other *HostsRecord) (ok bool) {
+	if rec == nil {
+		return other == nil
+	}
+
+	return rec.Canonical == other.Canonical && rec.Aliases.Equal(other.Aliases)
+}
+
 // ErrNoHostsPaths is returned when there are no valid paths to watch passed to
 // the HostsContainer.
 const ErrNoHostsPaths errors.Error = "no valid paths to hosts files provided"
@@ -164,7 +178,7 @@ func NewHostsContainer(
 		},
 		listID:   listID,
 		done:     make(chan struct{}, 1),
-		updates:  make(chan *netutil.IPMap, 1),
+		updates:  make(chan HostsRecords, 1),
 		fsys:     fsys,
 		w:        w,
 		patterns: patterns,
@@ -202,9 +216,8 @@ func (hc *HostsContainer) Close() (err error) {
 	return nil
 }
 
-// Upd returns the channel into which the updates are sent.  The receivable
+// Upd returns the channel into which the updates are sent.
-// map's values are guaranteed to be of type of *HostsRecord.
+func (hc *HostsContainer) Upd() (updates <-chan HostsRecords) {
-func (hc *HostsContainer) Upd() (updates <-chan *netutil.IPMap) {
 	return hc.updates
 }
 
@@ -270,7 +283,7 @@ type hostsParser struct {
 
 	// table stores only the unique IP-hostname pairs.  It's also sent to the
 	// updates channel afterwards.
-	table *netutil.IPMap
+	table HostsRecords
 }
 
 // newHostsParser creates a new *hostsParser with buffers of size taken from the
@@ -279,7 +292,7 @@ func (hc *HostsContainer) newHostsParser() (hp *hostsParser) {
 	return &hostsParser{
 		rulesBuilder: &strings.Builder{},
 		translations: map[string]string{},
-		table:        netutil.NewIPMap(hc.last.Len()),
+		table:        make(HostsRecords, len(hc.last)),
 	}
 }
 
@@ -291,7 +304,7 @@ func (hp *hostsParser) parseFile(r io.Reader) (patterns []string, cont bool, err
 	s := bufio.NewScanner(r)
 	for s.Scan() {
 		ip, hosts := hp.parseLine(s.Text())
-		if ip == nil || len(hosts) == 0 {
+		if ip == (netip.Addr{}) || len(hosts) == 0 {
 			continue
 		}
 
@@ -302,14 +315,15 @@ func (hp *hostsParser) parseFile(r io.Reader) (patterns []string, cont bool, err
 }
 
 // parseLine parses the line having the hosts syntax ignoring invalid ones.
-func (hp *hostsParser) parseLine(line string) (ip net.IP, hosts []string) {
+func (hp *hostsParser) parseLine(line string) (ip netip.Addr, hosts []string) {
 	fields := strings.Fields(line)
 	if len(fields) < 2 {
-		return nil, nil
+		return netip.Addr{}, nil
 	}
 
-	if ip = net.ParseIP(fields[0]); ip == nil {
+	ip, err := netip.ParseAddr(fields[0])
-		return nil, nil
+	if err != nil {
+		return netip.Addr{}, nil
 	}
 
 	for _, f := range fields[1:] {
@@ -327,7 +341,7 @@ func (hp *hostsParser) parseLine(line string) (ip net.IP, hosts []string) {
 		// See https://github.com/AdguardTeam/AdGuardHome/issues/3946.
 		//
 		// TODO(e.burkov):  Investigate if hosts may contain DNS-SD domains.
-		err := netutil.ValidateDomainName(f)
+		err = netutil.ValidateDomainName(f)
 		if err != nil {
 			log.Error("%s: host %q is invalid, ignoring", hostsContainerPref, f)
 
@@ -340,30 +354,13 @@ func (hp *hostsParser) parseLine(line string) (ip net.IP, hosts []string) {
 	return ip, hosts
 }
 
-// HostsRecord represents a single hosts file record.
-type HostsRecord struct {
-	Aliases   *stringutil.Set
-	Canonical string
-}
-
-// Equal returns true if all fields of rec are equal to field in other or they
-// both are nil.
-func (rec *HostsRecord) Equal(other *HostsRecord) (ok bool) {
-	if rec == nil {
-		return other == nil
-	}
-
-	return rec.Canonical == other.Canonical && rec.Aliases.Equal(other.Aliases)
-}
-
 // addRecord puts the record for the IP address to the rules builder if needed.
 // The first host is considered to be the canonical name for the IP address.
 // hosts must have at least one name.
-func (hp *hostsParser) addRecord(ip net.IP, hosts []string) {
+func (hp *hostsParser) addRecord(ip netip.Addr, hosts []string) {
 	line := strings.Join(append([]string{ip.String()}, hosts...), " ")
 
-	var rec *HostsRecord
+	rec, ok := hp.table[ip]
-	v, ok := hp.table.Get(ip)
 	if !ok {
 		rec = &HostsRecord{
 			Aliases: stringutil.NewSet(),
@@ -371,14 +368,7 @@ func (hp *hostsParser) addRecord(ip net.IP, hosts []string) {
 
 		rec.Canonical, hosts = hosts[0], hosts[1:]
 		hp.addRules(ip, rec.Canonical, line)
-		hp.table.Set(ip, rec)
+		hp.table[ip] = rec
-	} else {
-		rec, ok = v.(*HostsRecord)
-		if !ok {
-			log.Error("%s: adding pairs: unexpected type %T", hostsContainerPref, v)
-
-			return
-		}
 	}
 
 	for _, host := range hosts {
@@ -393,7 +383,7 @@ func (hp *hostsParser) addRecord(ip net.IP, hosts []string) {
 }
 
 // addRules adds rules and rule translations for the line.
-func (hp *hostsParser) addRules(ip net.IP, host, line string) {
+func (hp *hostsParser) addRules(ip netip.Addr, host, line string) {
 	rule, rulePtr := hp.writeRules(host, ip)
 	hp.translations[rule], hp.translations[rulePtr] = line, line
 
@@ -402,8 +392,9 @@ func (hp *hostsParser) addRules(ip net.IP, host, line string) {
 
 // writeRules writes the actual rule for the qtype and the PTR for the host-ip
 // pair into internal builders.
-func (hp *hostsParser) writeRules(host string, ip net.IP) (rule, rulePtr string) {
+func (hp *hostsParser) writeRules(host string, ip netip.Addr) (rule, rulePtr string) {
-	arpa, err := netutil.IPToReversedAddr(ip)
+	// TODO(a.garipov):  Add a netip.Addr version to netutil.
+	arpa, err := netutil.IPToReversedAddr(ip.AsSlice())
 	if err != nil {
 		return "", ""
 	}
@@ -421,7 +412,7 @@ func (hp *hostsParser) writeRules(host string, ip net.IP) (rule, rulePtr string)
 	var qtype string
 	// The validation of the IP address has been performed earlier so it is
 	// guaranteed to be either an IPv4 or an IPv6.
-	if ip.To4() != nil {
+	if ip.Is4() {
 		qtype = "A"
 	} else {
 		qtype = "AAAA"
@@ -448,51 +439,8 @@ func (hp *hostsParser) writeRules(host string, ip net.IP) (rule, rulePtr string)
 	return rule, rulePtr
 }
 
-// equalSet returns true if the internal hosts table just parsed equals target.
-// target's values must be of type *HostsRecord.
-func (hp *hostsParser) equalSet(target *netutil.IPMap) (ok bool) {
-	if target == nil {
-		// hp.table shouldn't appear nil since it's initialized on each refresh.
-		return target == hp.table
-	}
-
-	if hp.table.Len() != target.Len() {
-		return false
-	}
-
-	hp.table.Range(func(ip net.IP, recVal any) (cont bool) {
-		var targetVal any
-		targetVal, ok = target.Get(ip)
-		if !ok {
-			return false
-		}
-
-		var rec *HostsRecord
-		rec, ok = recVal.(*HostsRecord)
-		if !ok {
-			log.Error("%s: comparing: unexpected type %T", hostsContainerPref, recVal)
-
-			return false
-		}
-
-		var targetRec *HostsRecord
-		targetRec, ok = targetVal.(*HostsRecord)
-		if !ok {
-			log.Error("%s: comparing: target: unexpected type %T", hostsContainerPref, targetVal)
-
-			return false
-		}
-
-		ok = rec.Equal(targetRec)
-
-		return ok
-	})
-
-	return ok
-}
-
 // sendUpd tries to send the parsed data to the ch.
-func (hp *hostsParser) sendUpd(ch chan *netutil.IPMap) {
+func (hp *hostsParser) sendUpd(ch chan HostsRecords) {
 	log.Debug("%s: sending upd", hostsContainerPref)
 
 	upd := hp.table
@@ -530,14 +478,14 @@ func (hc *HostsContainer) refresh() (err error) {
 		return fmt.Errorf("refreshing : %w", err)
 	}
 
-	if hp.equalSet(hc.last) {
+	if maps.EqualFunc(hp.table, hc.last, (*HostsRecord).equal) {
 		log.Debug("%s: no changes detected", hostsContainerPref)
 
 		return nil
 	}
 	defer hp.sendUpd(hc.updates)
 
-	hc.last = hp.table.ShallowClone()
+	hc.last = maps.Clone(hp.table)
 
 	var rulesStrg *filterlist.RuleStorage
 	if rulesStrg, err = hp.newStrg(hc.listID); err != nil {

internal/aghnet/hostscontainer_test.go

@@ -3,6 +3,7 @@ package aghnet
 import (
 	"io/fs"
 	"net"
+	"net/netip"
 	"path"
 	"strings"
 	"sync/atomic"
@@ -13,6 +14,7 @@ import (
 	"github.com/AdguardTeam/AdGuardHome/internal/aghchan"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/netutil"
 	"github.com/AdguardTeam/golibs/stringutil"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/AdguardTeam/urlfilter"
@@ -135,7 +137,7 @@ func TestNewHostsContainer(t *testing.T) {
 func TestHostsContainer_refresh(t *testing.T) {
 	// TODO(e.burkov):  Test the case with no actual updates.
 
-	ip := net.IP{127, 0, 0, 1}
+	ip := netutil.IPv4Localhost()
 	ipStr := ip.String()
 
 	testFS := fstest.MapFS{"dir/file1": &fstest.MapFile{Data: []byte(ipStr + ` hostname` + nl)}}
@@ -167,17 +169,13 @@ func TestHostsContainer_refresh(t *testing.T) {
 		require.True(t, ok)
 		require.NotNil(t, upd)
 
-		assert.Equal(t, 1, upd.Len())
+		assert.Len(t, upd, 1)
 
-		v, ok := upd.Get(ip)
+		rec, ok := upd[ip]
 		require.True(t, ok)
-
-		require.IsType(t, (*HostsRecord)(nil), v)
-
-		rec, _ := v.(*HostsRecord)
 		require.NotNil(t, rec)
 
-		assert.Truef(t, rec.Equal(want), "%+v != %+v", rec, want)
+		assert.Truef(t, rec.equal(want), "%+v != %+v", rec, want)
 	}
 
 	t.Run("initial_refresh", func(t *testing.T) {
@@ -562,13 +560,13 @@ func TestHostsContainer(t *testing.T) {
 }
 
 func TestUniqueRules_ParseLine(t *testing.T) {
-	ip := net.IP{127, 0, 0, 1}
+	ip := netutil.IPv4Localhost()
 	ipStr := ip.String()
 
 	testCases := []struct {
 		name      string
 		line      string
-		wantIP    net.IP
+		wantIP    netip.Addr
 		wantHosts []string
 	}{{
 		name:      "simple",
@@ -583,7 +581,7 @@ func TestUniqueRules_ParseLine(t *testing.T) {
 	}, {
 		name:      "invalid_line",
 		line:      ipStr,
-		wantIP:    nil,
+		wantIP:    netip.Addr{},
 		wantHosts: nil,
 	}, {
 		name:      "invalid_line_hostname",
@@ -598,7 +596,7 @@ func TestUniqueRules_ParseLine(t *testing.T) {
 	}, {
 		name:      "whole_comment",
 		line:      `# ` + ipStr + ` hostname`,
-		wantIP:    nil,
+		wantIP:    netip.Addr{},
 		wantHosts: nil,
 	}, {
 		name:      "partial_comment",
@@ -608,7 +606,7 @@ func TestUniqueRules_ParseLine(t *testing.T) {
 	}, {
 		name:      "empty",
 		line:      ``,
-		wantIP:    nil,
+		wantIP:    netip.Addr{},
 		wantHosts: nil,
 	}}
 
@@ -616,7 +614,7 @@ func TestUniqueRules_ParseLine(t *testing.T) {
 		hp := hostsParser{}
 		t.Run(tc.name, func(t *testing.T) {
 			got, hosts := hp.parseLine(tc.line)
-			assert.True(t, tc.wantIP.Equal(got))
+			assert.Equal(t, tc.wantIP, got)
 			assert.Equal(t, tc.wantHosts, hosts)
 		})
 	}

internal/home/clients.go

@@ -332,8 +332,8 @@ func (clients *clientsContainer) onDHCPLeaseChanged(flags int) {
 	}
 }
 
-// Exists checks if client with this IP address already exists.
+// exists checks if client with this IP address already exists.
-func (clients *clientsContainer) Exists(ip net.IP, source clientSource) (ok bool) {
+func (clients *clientsContainer) exists(ip net.IP, source clientSource) (ok bool) {
 	clients.lock.Lock()
 	defer clients.lock.Unlock()
 
@@ -414,7 +414,7 @@ func (clients *clientsContainer) clientOrArtificial(
 	}
 
 	var rc *RuntimeClient
-	rc, ok = clients.FindRuntimeClient(ip)
+	rc, ok = clients.findRuntimeClient(ip)
 	if ok {
 		return &querylog.Client{
 			Name:  rc.Host,
@@ -551,8 +551,8 @@ func (clients *clientsContainer) findRuntimeClientLocked(ip net.IP) (rc *Runtime
 	return rc, ok
 }
 
-// FindRuntimeClient finds a runtime client by their IP.
+// findRuntimeClient finds a runtime client by their IP.
-func (clients *clientsContainer) FindRuntimeClient(ip net.IP) (rc *RuntimeClient, ok bool) {
+func (clients *clientsContainer) findRuntimeClient(ip net.IP) (rc *RuntimeClient, ok bool) {
 	if ip == nil {
 		return nil, false
 	}
@@ -749,8 +749,8 @@ func (clients *clientsContainer) Update(name string, c *Client) (err error) {
 	return nil
 }
 
-// SetWHOISInfo sets the WHOIS information for a client.
+// setWHOISInfo sets the WHOIS information for a client.
-func (clients *clientsContainer) SetWHOISInfo(ip net.IP, wi *RuntimeClientWHOISInfo) {
+func (clients *clientsContainer) setWHOISInfo(ip net.IP, wi *RuntimeClientWHOISInfo) {
 	clients.lock.Lock()
 	defer clients.lock.Unlock()
 
@@ -795,12 +795,23 @@ func (clients *clientsContainer) AddHost(ip net.IP, host string, src clientSourc
 	clients.lock.Lock()
 	defer clients.lock.Unlock()
 
-	return clients.addHostLocked(ip, host, src), nil
+	// TODO(a.garipov):  Remove once we switch to netip.Addr more fully.
+	ipAddr, err := netutil.IPToAddrNoMapped(ip)
+	if err != nil {
+		return false, fmt.Errorf("adding host: %w", err)
+	}
+
+	return clients.addHostLocked(ipAddr, host, src), nil
 }
 
-// addHostLocked adds a new IP-hostname pairing.  For internal use only.
+// addHostLocked adds a new IP-hostname pairing.  clients.lock is expected to be
-func (clients *clientsContainer) addHostLocked(ip net.IP, host string, src clientSource) (ok bool) {
+// locked.
-	rc, ok := clients.findRuntimeClientLocked(ip)
+func (clients *clientsContainer) addHostLocked(
+	ip netip.Addr,
+	host string,
+	src clientSource,
+) (ok bool) {
+	rc, ok := clients.ipToRC[ip]
 	if ok {
 		if rc.Source > src {
 			return false
@@ -815,15 +826,7 @@ func (clients *clientsContainer) addHostLocked(ip net.IP, host string, src clien
 			WHOISInfo: &RuntimeClientWHOISInfo{},
 		}
 
-		// TODO(a.garipov):  Remove once we switch to netip.Addr more fully.
+		clients.ipToRC[ip] = rc
-		ipAddr, err := netutil.IPToAddrNoMapped(ip)
-		if err != nil {
-			log.Error("clients: bad client ip %v: %s", ip, err)
-
-			return false
-		}
-
-		clients.ipToRC[ipAddr] = rc
 	}
 
 	log.Debug("clients: added %s -> %q [%d]", ip, host, len(clients.ipToRC))
@@ -846,28 +849,17 @@ func (clients *clientsContainer) rmHostsBySrc(src clientSource) {
 
 // addFromHostsFile fills the client-hostname pairing index from the system's
 // hosts files.
-//
+func (clients *clientsContainer) addFromHostsFile(hosts aghnet.HostsRecords) {
-//lint:ignore SA1019 TODO(a.garipov):  Replace [*netutil.IPMap].
-func (clients *clientsContainer) addFromHostsFile(hosts *netutil.IPMap) {
 	clients.lock.Lock()
 	defer clients.lock.Unlock()
 
 	clients.rmHostsBySrc(ClientSourceHostsFile)
 
 	n := 0
-	hosts.Range(func(ip net.IP, v any) (cont bool) {
+	for ip, rec := range hosts {
-		rec, ok := v.(*aghnet.HostsRecord)
-		if !ok {
-			log.Error("clients: bad type %T in hosts for %s", v, ip)
-
-			return true
-		}
-
 		clients.addHostLocked(ip, rec.Canonical, ClientSourceHostsFile)
 		n++
-
+	}
-		return true
-	})
 
 	log.Debug("clients: added %d client aliases from system hosts file", n)
 }
@@ -928,7 +920,15 @@ func (clients *clientsContainer) updateFromDHCP(add bool) {
 			continue
 		}
 
-		ok := clients.addHostLocked(l.IP, l.Hostname, ClientSourceDHCP)
+		// TODO(a.garipov):  Remove once we switch to netip.Addr more fully.
+		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

@@ -57,9 +57,9 @@ func TestClients(t *testing.T) {
 
 		assert.Equal(t, "client2", c.Name)
 
-		assert.False(t, clients.Exists(net.IP{1, 2, 3, 4}, ClientSourceHostsFile))
+		assert.False(t, clients.exists(net.IP{1, 2, 3, 4}, ClientSourceHostsFile))
-		assert.True(t, clients.Exists(net.IP{1, 1, 1, 1}, ClientSourceHostsFile))
+		assert.True(t, clients.exists(net.IP{1, 1, 1, 1}, ClientSourceHostsFile))
-		assert.True(t, clients.Exists(net.IP{2, 2, 2, 2}, ClientSourceHostsFile))
+		assert.True(t, clients.exists(net.IP{2, 2, 2, 2}, ClientSourceHostsFile))
 	})
 
 	t.Run("add_fail_name", func(t *testing.T) {
@@ -109,8 +109,8 @@ func TestClients(t *testing.T) {
 		})
 		require.NoError(t, err)
 
-		assert.False(t, clients.Exists(net.IP{1, 1, 1, 1}, ClientSourceHostsFile))
+		assert.False(t, clients.exists(net.IP{1, 1, 1, 1}, ClientSourceHostsFile))
-		assert.True(t, clients.Exists(net.IP{1, 1, 1, 2}, ClientSourceHostsFile))
+		assert.True(t, clients.exists(net.IP{1, 1, 1, 2}, ClientSourceHostsFile))
 
 		err = clients.Update("client1", &Client{
 			IDs:            []string{"1.1.1.2"},
@@ -139,7 +139,7 @@ func TestClients(t *testing.T) {
 		ok := clients.Del("client1-renamed")
 		require.True(t, ok)
 
-		assert.False(t, clients.Exists(net.IP{1, 1, 1, 2}, ClientSourceHostsFile))
+		assert.False(t, clients.exists(net.IP{1, 1, 1, 2}, ClientSourceHostsFile))
 	})
 
 	t.Run("del_fail", func(t *testing.T) {
@@ -165,7 +165,7 @@ func TestClients(t *testing.T) {
 
 		assert.True(t, ok)
 
-		assert.True(t, clients.Exists(ip, ClientSourceHostsFile))
+		assert.True(t, clients.exists(ip, ClientSourceHostsFile))
 	})
 
 	t.Run("dhcp_replaces_arp", func(t *testing.T) {
@@ -175,13 +175,13 @@ func TestClients(t *testing.T) {
 		require.NoError(t, err)
 
 		assert.True(t, ok)
-		assert.True(t, clients.Exists(ip, ClientSourceARP))
+		assert.True(t, clients.exists(ip, ClientSourceARP))
 
 		ok, err = clients.AddHost(ip, "from_dhcp", ClientSourceDHCP)
 		require.NoError(t, err)
 
 		assert.True(t, ok)
-		assert.True(t, clients.Exists(ip, ClientSourceDHCP))
+		assert.True(t, clients.exists(ip, ClientSourceDHCP))
 	})
 
 	t.Run("addhost_fail", func(t *testing.T) {
@@ -203,7 +203,7 @@ func TestClientsWHOIS(t *testing.T) {
 
 	t.Run("new_client", func(t *testing.T) {
 		ip := netip.MustParseAddr("1.1.1.255")
-		clients.SetWHOISInfo(ip.AsSlice(), whois)
+		clients.setWHOISInfo(ip.AsSlice(), whois)
 		rc := clients.ipToRC[ip]
 		require.NotNil(t, rc)
 
@@ -217,7 +217,7 @@ func TestClientsWHOIS(t *testing.T) {
 
 		assert.True(t, ok)
 
-		clients.SetWHOISInfo(ip.AsSlice(), whois)
+		clients.setWHOISInfo(ip.AsSlice(), whois)
 		rc := clients.ipToRC[ip]
 		require.NotNil(t, rc)
 
@@ -234,7 +234,7 @@ func TestClientsWHOIS(t *testing.T) {
 		require.NoError(t, err)
 		assert.True(t, ok)
 
-		clients.SetWHOISInfo(ip.AsSlice(), whois)
+		clients.setWHOISInfo(ip.AsSlice(), whois)
 		rc := clients.ipToRC[ip]
 		require.Nil(t, rc)
 

internal/home/clientshttp.go

@@ -241,7 +241,7 @@ func (clients *clientsContainer) handleFindClient(w http.ResponseWriter, r *http
 // /etc/hosts tables, DHCP leases, or blocklists.  cj is guaranteed to be
 // non-nil.
 func (clients *clientsContainer) findRuntime(ip net.IP, idStr string) (cj *clientJSON) {
-	rc, ok := clients.FindRuntimeClient(ip)
+	rc, ok := clients.findRuntimeClient(ip)
 	if !ok {
 		// It is still possible that the IP used to be in the runtime clients
 		// list, but then the server was reloaded.  So, check the DNS server's

internal/home/rdns.go

@@ -101,7 +101,7 @@ func (r *RDNS) isCached(ip net.IP) (ok bool) {
 func (r *RDNS) Begin(ip net.IP) {
 	r.ensurePrivateCache()
 
-	if r.isCached(ip) || r.clients.Exists(ip, ClientSourceRDNS) {
+	if r.isCached(ip) || r.clients.exists(ip, ClientSourceRDNS) {
 		return
 	}
 

internal/home/rdns_test.go

@@ -259,7 +259,7 @@ func TestRDNS_WorkerLoop(t *testing.T) {
 				return
 			}
 
-			assert.True(t, cc.Exists(tc.cliIP, ClientSourceRDNS))
+			assert.True(t, cc.exists(tc.cliIP, ClientSourceRDNS))
 		})
 	}
 }

internal/home/whois.go

@@ -252,6 +252,6 @@ func (w *WHOIS) workerLoop() {
 			continue
 		}
 
-		w.clients.SetWHOISInfo(ip, info)
+		w.clients.setWHOISInfo(ip, info)
 	}
 }