Pull request 2094: AG-27796 upd golibs

Squashed commit of the following:

commit a205c1302e3979d1c4270b11d253b6bc0d292216
Merge: de289ff4f 214175eb4
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Dec 7 16:36:53 2023 +0300

    Merge branch 'master' into AG-27796-upd-golibs

commit de289ff4f3199bc2dffb029a9804cabe86b3b886
Merge: b2322093c a0ec0b2b5
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Dec 6 12:12:35 2023 +0300

    Merge branch 'master' into AG-27796-upd-golibs

commit b2322093cea0ecdf34be66b56a9ab0fd7b32c7b9
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Dec 5 19:20:30 2023 +0300

    filtering: imp cognit

commit 563aa45824a2cc9d63d2c394f6a60f053e5d6d3b
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Dec 4 17:02:56 2023 +0300

    all: imp code

commit 064a00bce4340caa4cea052fa8234cedb8dcea01
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Nov 28 18:41:07 2023 +0300

    all: upd golibs

internal/aghchan/aghchan.go

@@ -1,33 +0,0 @@
-// Package aghchan contains channel utilities.
-package aghchan
-
-import (
-	"fmt"
-	"time"
-)
-
-// Receive returns an error if it cannot receive a value form c before timeout
-// runs out.
-func Receive[T any](c <-chan T, timeout time.Duration) (v T, ok bool, err error) {
-	var zero T
-	timeoutCh := time.After(timeout)
-	select {
-	case <-timeoutCh:
-		// TODO(a.garipov): Consider implementing [errors.Aser] for
-		// os.ErrTimeout.
-		return zero, false, fmt.Errorf("did not receive after %s", timeout)
-	case v, ok = <-c:
-		return v, ok, nil
-	}
-}
-
-// MustReceive panics if it cannot receive a value form c before timeout runs
-// out.
-func MustReceive[T any](c <-chan T, timeout time.Duration) (v T, ok bool) {
-	v, ok, err := Receive(c, timeout)
-	if err != nil {
-		panic(err)
-	}
-
-	return v, ok
-}

internal/aghnet/hostscontainer.go

@@ -1,65 +1,23 @@
 package aghnet
 
 import (
-	"context"
 	"fmt"
 	"io"
 	"io/fs"
 	"net/netip"
 	"path"
-	"strings"
 	"sync/atomic"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghos"
-	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/hostsfile"
 	"github.com/AdguardTeam/golibs/log"
-	"golang.org/x/exp/maps"
-	"golang.org/x/exp/slices"
 )
 
-// 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.
-func DefaultHostsPaths() (paths []string) {
-	return defaultHostsPaths()
-}
-
-// MatchAddr returns the records for the IP address.
-func (hc *HostsContainer) MatchAddr(ip netip.Addr) (recs []*hostsfile.Record) {
-	cur := hc.current.Load()
-	if cur == nil {
-		return nil
-	}
-
-	return cur.addrs[ip]
-}
-
-// MatchName returns the records for the hostname.
-func (hc *HostsContainer) MatchName(name string) (recs []*hostsfile.Record) {
-	cur := hc.current.Load()
-	if cur != nil {
-		recs = cur.names[name]
-	}
-
-	return recs
-}
-
 // hostsContainerPrefix is a prefix for logging and wrapping errors in
 // HostsContainer's methods.
 const hostsContainerPrefix = "hosts container"
 
-// Hosts is a map of IP addresses to the records, as it primarily stored in the
-// [HostsContainer].  It should not be accessed for writing since it may be read
-// concurrently, users should clone it before modifying.
-//
-// The order of records for each address is preserved from original files, but
-// the order of the addresses, being a map key, is not.
-//
-// TODO(e.burkov):  Probably, this should be a sorted slice of records.
-type Hosts map[netip.Addr][]*hostsfile.Record
-
 // HostsContainer stores the relevant hosts database provided by the OS and
 // processes both A/AAAA and PTR DNS requests for those.
 type HostsContainer struct {
@@ -67,10 +25,10 @@ type HostsContainer struct {
 	done chan struct{}
 
 	// updates is the channel for receiving updated hosts.
-	updates chan Hosts
+	updates chan *hostsfile.DefaultStorage
 
 	// current is the last set of hosts parsed.
-	current atomic.Pointer[hostsIndex]
+	current atomic.Pointer[hostsfile.DefaultStorage]
 
 	// fsys is the working file system to read hosts files from.
 	fsys fs.FS
@@ -111,7 +69,7 @@ func NewHostsContainer(
 
 	hc = &HostsContainer{
 		done:     make(chan struct{}, 1),
-		updates:  make(chan Hosts, 1),
+		updates:  make(chan *hostsfile.DefaultStorage, 1),
 		fsys:     fsys,
 		watcher:  w,
 		patterns: patterns,
@@ -152,11 +110,25 @@ func (hc *HostsContainer) Close() (err error) {
 	return err
 }
 
-// Upd returns the channel into which the updates are sent.
+// Upd returns the channel into which the updates are sent.  The updates
-func (hc *HostsContainer) Upd() (updates <-chan Hosts) {
+// themselves must not be modified.
+func (hc *HostsContainer) Upd() (updates <-chan *hostsfile.DefaultStorage) {
 	return hc.updates
 }
 
+// type check
+var _ hostsfile.Storage = (*HostsContainer)(nil)
+
+// ByAddr implements the [hostsfile.Storage] interface for *HostsContainer.
+func (hc *HostsContainer) ByAddr(addr netip.Addr) (names []string) {
+	return hc.current.Load().ByAddr(addr)
+}
+
+// ByName implements the [hostsfile.Storage] interface for *HostsContainer.
+func (hc *HostsContainer) ByName(name string) (addrs []netip.Addr) {
+	return hc.current.Load().ByName(name)
+}
+
 // pathsToPatterns converts paths into patterns compatible with fs.Glob.
 func pathsToPatterns(fsys fs.FS, paths []string) (patterns []string, err error) {
 	for i, p := range paths {
@@ -167,7 +139,7 @@ func pathsToPatterns(fsys fs.FS, paths []string) (patterns []string, err error)
 				continue
 			}
 
-			// Don't put a filename here since it's already added by fs.Stat.
+			// Don't put a filename here since it's already added by [fs.Stat].
 			return nil, fmt.Errorf("path at index %d: %w", i, err)
 		}
 
@@ -209,7 +181,7 @@ func (hc *HostsContainer) handleEvents() {
 }
 
 // sendUpd tries to send the parsed data to the ch.
-func (hc *HostsContainer) sendUpd(recs Hosts) {
+func (hc *HostsContainer) sendUpd(recs *hostsfile.DefaultStorage) {
 	log.Debug("%s: sending upd", hostsContainerPrefix)
 
 	ch := hc.updates
@@ -226,67 +198,6 @@ func (hc *HostsContainer) sendUpd(recs Hosts) {
 	}
 }
 
-// hostsIndex is a [hostsfile.Set] to enumerate all the records.
-type hostsIndex struct {
-	// addrs maps IP addresses to the records.
-	addrs Hosts
-
-	// names maps hostnames to the records.
-	names map[string][]*hostsfile.Record
-}
-
-// walk is a file walking function for hostsIndex.
-func (idx *hostsIndex) walk(r io.Reader) (patterns []string, cont bool, err error) {
-	return nil, true, hostsfile.Parse(idx, r, nil)
-}
-
-// type check
-var _ hostsfile.Set = (*hostsIndex)(nil)
-
-// Add implements the [hostsfile.Set] interface for *hostsIndex.
-func (idx *hostsIndex) Add(rec *hostsfile.Record) {
-	idx.addrs[rec.Addr] = append(idx.addrs[rec.Addr], rec)
-	for _, name := range rec.Names {
-		idx.names[name] = append(idx.names[name], rec)
-	}
-}
-
-// type check
-var _ hostsfile.HandleSet = (*hostsIndex)(nil)
-
-// HandleInvalid implements the [hostsfile.HandleSet] interface for *hostsIndex.
-func (idx *hostsIndex) HandleInvalid(src string, _ []byte, err error) {
-	lineErr := &hostsfile.LineError{}
-	if !errors.As(err, &lineErr) {
-		// Must not happen if idx passed to [hostsfile.Parse].
-		return
-	} else if errors.Is(lineErr, hostsfile.ErrEmptyLine) {
-		// Ignore empty lines.
-		return
-	}
-
-	log.Info("%s: warning: parsing %q: %s", hostsContainerPrefix, src, lineErr)
-}
-
-// equalRecs is an equality function for [*hostsfile.Record].
-func equalRecs(a, b *hostsfile.Record) (ok bool) {
-	return a.Addr == b.Addr && a.Source == b.Source && slices.Equal(a.Names, b.Names)
-}
-
-// equalRecSlices is an equality function for slices of [*hostsfile.Record].
-func equalRecSlices(a, b []*hostsfile.Record) (ok bool) { return slices.EqualFunc(a, b, equalRecs) }
-
-// Equal returns true if indexes are equal.
-func (idx *hostsIndex) Equal(other *hostsIndex) (ok bool) {
-	if idx == nil {
-		return other == nil
-	} else if other == nil {
-		return false
-	}
-
-	return maps.EqualFunc(idx.addrs, other.addrs, equalRecSlices)
-}
-
 // refresh gets the data from specified files and propagates the updates if
 // needed.
 //
@@ -294,63 +205,22 @@ func (idx *hostsIndex) Equal(other *hostsIndex) (ok bool) {
 func (hc *HostsContainer) refresh() (err error) {
 	log.Debug("%s: refreshing", hostsContainerPrefix)
 
-	var addrLen, nameLen int
+	// The error is always nil here since no readers passed.
-	last := hc.current.Load()
+	strg, _ := hostsfile.NewDefaultStorage()
-	if last != nil {
+	_, err = aghos.FileWalker(func(r io.Reader) (patterns []string, cont bool, err error) {
-		addrLen, nameLen = len(last.addrs), len(last.names)
+		// Don't wrap the error since it's already informative enough as is.
-	}
+		return nil, true, hostsfile.Parse(strg, r, nil)
-	idx := &hostsIndex{
+	}).Walk(hc.fsys, hc.patterns...)
-		addrs: make(Hosts, addrLen),
-		names: make(map[string][]*hostsfile.Record, nameLen),
-	}
-
-	_, err = aghos.FileWalker(idx.walk).Walk(hc.fsys, hc.patterns...)
 	if err != nil {
 		// Don't wrap the error since it's informative enough as is.
 		return err
 	}
 
-	// TODO(e.burkov):  Serialize updates using time.
+	// TODO(e.burkov):  Serialize updates using [time.Time].
-	if !last.Equal(idx) {
+	if !hc.current.Load().Equal(strg) {
-		hc.current.Store(idx)
+		hc.current.Store(strg)
-		hc.sendUpd(idx.addrs)
+		hc.sendUpd(strg)
 	}
 
 	return nil
 }
-
-// type check
-var _ upstream.Resolver = (*HostsContainer)(nil)
-
-// LookupNetIP implements the [upstream.Resolver] interface for *HostsContainer.
-func (hc *HostsContainer) LookupNetIP(
-	ctx context.Context,
-	network string,
-	hostname string,
-) (addrs []netip.Addr, err error) {
-	// TODO(e.burkov):  Think of extracting this logic to a golibs function if
-	// needed anywhere else.
-	var isDesiredProto func(ip netip.Addr) (ok bool)
-	switch network {
-	case "ip4":
-		isDesiredProto = (netip.Addr).Is4
-	case "ip6":
-		isDesiredProto = (netip.Addr).Is6
-	case "ip":
-		isDesiredProto = func(ip netip.Addr) (ok bool) { return true }
-	default:
-		return nil, fmt.Errorf("unsupported network: %q", network)
-	}
-
-	idx := hc.current.Load()
-	recs := idx.names[strings.ToLower(hostname)]
-
-	addrs = make([]netip.Addr, 0, len(recs))
-	for _, rec := range recs {
-		if isDesiredProto(rec.Addr) {
-			addrs = append(addrs, rec.Addr)
-		}
-	}
-
-	return slices.Clip(addrs), nil
-}

internal/aghnet/hostscontainer_linux.go

@@ -1,17 +0,0 @@
-//go:build linux
-
-package aghnet
-
-import (
-	"github.com/AdguardTeam/AdGuardHome/internal/aghos"
-)
-
-func defaultHostsPaths() (paths []string) {
-	paths = []string{"etc/hosts"}
-
-	if aghos.IsOpenWrt() {
-		paths = append(paths, "tmp/hosts")
-	}
-
-	return paths
-}

internal/aghnet/hostscontainer_others.go

@@ -1,7 +0,0 @@
-//go:build !(windows || linux)
-
-package aghnet
-
-func defaultHostsPaths() (paths []string) {
-	return []string{"etc/hosts"}
-}

internal/aghnet/hostscontainer_test.go

@@ -3,13 +3,11 @@ package aghnet_test
 import (
 	"net/netip"
 	"path"
-	"path/filepath"
 	"sync/atomic"
 	"testing"
 	"testing/fstest"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/aghchan"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/golibs/errors"
@@ -20,139 +18,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// nl is a newline character.
-const nl = "\n"
-
-// Variables mirroring the etc_hosts file from testdata.
-var (
-	addr1000 = netip.MustParseAddr("1.0.0.0")
-	addr1001 = netip.MustParseAddr("1.0.0.1")
-	addr1002 = netip.MustParseAddr("1.0.0.2")
-	addr1003 = netip.MustParseAddr("1.0.0.3")
-	addr1004 = netip.MustParseAddr("1.0.0.4")
-	addr1357 = netip.MustParseAddr("1.3.5.7")
-	addr4216 = netip.MustParseAddr("4.2.1.6")
-	addr7531 = netip.MustParseAddr("7.5.3.1")
-
-	addr0  = netip.MustParseAddr("::")
-	addr1  = netip.MustParseAddr("::1")
-	addr2  = netip.MustParseAddr("::2")
-	addr3  = netip.MustParseAddr("::3")
-	addr4  = netip.MustParseAddr("::4")
-	addr42 = netip.MustParseAddr("::42")
-	addr13 = netip.MustParseAddr("::13")
-	addr31 = netip.MustParseAddr("::31")
-
-	hostsSrc = "./" + filepath.Join("./testdata", "etc_hosts")
-
-	testHosts = map[netip.Addr][]*hostsfile.Record{
-		addr1000: {{
-			Addr:   addr1000,
-			Source: hostsSrc,
-			Names:  []string{"hello", "hello.world"},
-		}, {
-			Addr:   addr1000,
-			Source: hostsSrc,
-			Names:  []string{"hello.world.again"},
-		}, {
-			Addr:   addr1000,
-			Source: hostsSrc,
-			Names:  []string{"hello.world"},
-		}},
-		addr1001: {{
-			Addr:   addr1001,
-			Source: hostsSrc,
-			Names:  []string{"simplehost"},
-		}, {
-			Addr:   addr1001,
-			Source: hostsSrc,
-			Names:  []string{"simplehost"},
-		}},
-		addr1002: {{
-			Addr:   addr1002,
-			Source: hostsSrc,
-			Names:  []string{"a.whole", "lot.of", "aliases", "for.testing"},
-		}},
-		addr1003: {{
-			Addr:   addr1003,
-			Source: hostsSrc,
-			Names:  []string{"*"},
-		}},
-		addr1004: {{
-			Addr:   addr1004,
-			Source: hostsSrc,
-			Names:  []string{"*.com"},
-		}},
-		addr1357: {{
-			Addr:   addr1357,
-			Source: hostsSrc,
-			Names:  []string{"domain4", "domain4.alias"},
-		}},
-		addr7531: {{
-			Addr:   addr7531,
-			Source: hostsSrc,
-			Names:  []string{"domain4.alias", "domain4"},
-		}},
-		addr4216: {{
-			Addr:   addr4216,
-			Source: hostsSrc,
-			Names:  []string{"domain", "domain.alias"},
-		}},
-		addr0: {{
-			Addr:   addr0,
-			Source: hostsSrc,
-			Names:  []string{"hello", "hello.world"},
-		}, {
-			Addr:   addr0,
-			Source: hostsSrc,
-			Names:  []string{"hello.world.again"},
-		}, {
-			Addr:   addr0,
-			Source: hostsSrc,
-			Names:  []string{"hello.world"},
-		}},
-		addr1: {{
-			Addr:   addr1,
-			Source: hostsSrc,
-			Names:  []string{"simplehost"},
-		}, {
-			Addr:   addr1,
-			Source: hostsSrc,
-			Names:  []string{"simplehost"},
-		}},
-		addr2: {{
-			Addr:   addr2,
-			Source: hostsSrc,
-			Names:  []string{"a.whole", "lot.of", "aliases", "for.testing"},
-		}},
-		addr3: {{
-			Addr:   addr3,
-			Source: hostsSrc,
-			Names:  []string{"*"},
-		}},
-		addr4: {{
-			Addr:   addr4,
-			Source: hostsSrc,
-			Names:  []string{"*.com"},
-		}},
-		addr42: {{
-			Addr:   addr42,
-			Source: hostsSrc,
-			Names:  []string{"domain.alias", "domain"},
-		}},
-		addr13: {{
-			Addr:   addr13,
-			Source: hostsSrc,
-			Names:  []string{"domain6", "domain6.alias"},
-		}},
-		addr31: {{
-			Addr:   addr31,
-			Source: hostsSrc,
-			Names:  []string{"domain6.alias", "domain6"},
-		}},
-	}
-)
-
 func TestNewHostsContainer(t *testing.T) {
 	const dirname = "dir"
 	const filename = "file1"
@@ -267,7 +132,21 @@ func TestHostsContainer_refresh(t *testing.T) {
 	anotherIPStr := "1.2.3.4"
 	anotherIP := netip.MustParseAddr(anotherIPStr)
 
-	testFS := fstest.MapFS{"dir/file1": &fstest.MapFile{Data: []byte(ipStr + ` hostname` + nl)}}
+	r1 := &hostsfile.Record{
+		Addr:   ip,
+		Source: "file1",
+		Names:  []string{"hostname"},
+	}
+	r2 := &hostsfile.Record{
+		Addr:   anotherIP,
+		Source: "file2",
+		Names:  []string{"alias"},
+	}
+
+	r1Data, _ := r1.MarshalText()
+	r2Data, _ := r2.MarshalText()
+
+	testFS := fstest.MapFS{"dir/file1": &fstest.MapFile{Data: r1Data}}
 
 	// event is a convenient alias for an empty struct{} to emit test events.
 	type event = struct{}
@@ -289,172 +168,47 @@ func TestHostsContainer_refresh(t *testing.T) {
 	require.NoError(t, err)
 	testutil.CleanupAndRequireSuccess(t, hc.Close)
 
-	checkRefresh := func(t *testing.T, want aghnet.Hosts) {
+	strg, _ := hostsfile.NewDefaultStorage()
-		t.Helper()
+	strg.Add(r1)
-
-		upd, ok := aghchan.MustReceive(hc.Upd(), 1*time.Second)
-		require.True(t, ok)
-
-		assert.Equal(t, want, upd)
-	}
 
 	t.Run("initial_refresh", func(t *testing.T) {
-		checkRefresh(t, aghnet.Hosts{
+		upd, ok := testutil.RequireReceive(t, hc.Upd(), 1*time.Second)
-			ip: {{
+		require.True(t, ok)
-				Addr:   ip,
+
-				Source: "file1",
+		assert.True(t, strg.Equal(upd))
-				Names:  []string{"hostname"},
-			}},
-		})
 	})
 
+	strg.Add(r2)
+
 	t.Run("second_refresh", func(t *testing.T) {
-		testFS["dir/file2"] = &fstest.MapFile{Data: []byte(anotherIPStr + ` alias` + nl)}
+		testFS["dir/file2"] = &fstest.MapFile{Data: r2Data}
 		eventsCh <- event{}
 
-		checkRefresh(t, aghnet.Hosts{
+		upd, ok := testutil.RequireReceive(t, hc.Upd(), 1*time.Second)
-			ip: {{
+		require.True(t, ok)
-				Addr:   ip,
+
-				Source: "file1",
+		assert.True(t, strg.Equal(upd))
-				Names:  []string{"hostname"},
-			}},
-			anotherIP: {{
-				Addr:   anotherIP,
-				Source: "file2",
-				Names:  []string{"alias"},
-			}},
-		})
 	})
 
 	t.Run("double_refresh", func(t *testing.T) {
 		// Make a change once.
-		testFS["dir/file1"] = &fstest.MapFile{Data: []byte(ipStr + ` alias` + nl)}
+		testFS["dir/file1"] = &fstest.MapFile{Data: []byte(ipStr + " alias\n")}
 		eventsCh <- event{}
 
 		// Require the changes are written.
-		require.Eventually(t, func() bool {
+		current, ok := testutil.RequireReceive(t, hc.Upd(), 1*time.Second)
-			ips := hc.MatchName("hostname")
+		require.True(t, ok)
 
-			return len(ips) == 0
+		require.Empty(t, current.ByName("hostname"))
-		}, 5*time.Second, time.Second/2)
 
 		// Make a change again.
-		testFS["dir/file2"] = &fstest.MapFile{Data: []byte(ipStr + ` hostname` + nl)}
+		testFS["dir/file2"] = &fstest.MapFile{Data: []byte(ipStr + " hostname\n")}
 		eventsCh <- event{}
 
 		// Require the changes are written.
-		require.Eventually(t, func() bool {
+		current, ok = testutil.RequireReceive(t, hc.Upd(), 1*time.Second)
-			ips := hc.MatchName("hostname")
+		require.True(t, ok)
 
-			return len(ips) > 0
+		require.NotEmpty(t, current.ByName("hostname"))
-		}, 5*time.Second, time.Second/2)
-
-		assert.Len(t, hc.Upd(), 1)
 	})
 }
-
-func TestHostsContainer_MatchName(t *testing.T) {
-	require.NoError(t, fstest.TestFS(testdata, "etc_hosts"))
-
-	stubWatcher := aghtest.FSWatcher{
-		OnEvents: func() (e <-chan struct{}) { return nil },
-		OnAdd:    func(name string) (err error) { return nil },
-		OnClose:  func() (err error) { return nil },
-	}
-
-	testCases := []struct {
-		req  string
-		name string
-		want []*hostsfile.Record
-	}{{
-		req:  "simplehost",
-		name: "simple",
-		want: append(testHosts[addr1001], testHosts[addr1]...),
-	}, {
-		req:  "hello.world",
-		name: "hello_alias",
-		want: []*hostsfile.Record{
-			testHosts[addr1000][0],
-			testHosts[addr1000][2],
-			testHosts[addr0][0],
-			testHosts[addr0][2],
-		},
-	}, {
-		req:  "hello.world.again",
-		name: "other_line_alias",
-		want: []*hostsfile.Record{
-			testHosts[addr1000][1],
-			testHosts[addr0][1],
-		},
-	}, {
-		req:  "say.hello",
-		name: "hello_subdomain",
-		want: nil,
-	}, {
-		req:  "say.hello.world",
-		name: "hello_alias_subdomain",
-		want: nil,
-	}, {
-		req:  "for.testing",
-		name: "lots_of_aliases",
-		want: append(testHosts[addr1002], testHosts[addr2]...),
-	}, {
-		req:  "nonexistent.example",
-		name: "non-existing",
-		want: nil,
-	}, {
-		req:  "domain",
-		name: "issue_4216_4_6",
-		want: append(testHosts[addr4216], testHosts[addr42]...),
-	}, {
-		req:  "domain4",
-		name: "issue_4216_4",
-		want: append(testHosts[addr1357], testHosts[addr7531]...),
-	}, {
-		req:  "domain6",
-		name: "issue_4216_6",
-		want: append(testHosts[addr13], testHosts[addr31]...),
-	}}
-
-	hc, err := aghnet.NewHostsContainer(testdata, &stubWatcher, "etc_hosts")
-	require.NoError(t, err)
-	testutil.CleanupAndRequireSuccess(t, hc.Close)
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			recs := hc.MatchName(tc.req)
-			assert.Equal(t, tc.want, recs)
-		})
-	}
-}
-
-func TestHostsContainer_MatchAddr(t *testing.T) {
-	require.NoError(t, fstest.TestFS(testdata, "etc_hosts"))
-
-	stubWatcher := aghtest.FSWatcher{
-		OnEvents: func() (e <-chan struct{}) { return nil },
-		OnAdd:    func(name string) (err error) { return nil },
-		OnClose:  func() (err error) { return nil },
-	}
-
-	hc, err := aghnet.NewHostsContainer(testdata, &stubWatcher, "etc_hosts")
-	require.NoError(t, err)
-	testutil.CleanupAndRequireSuccess(t, hc.Close)
-
-	testCases := []struct {
-		req  netip.Addr
-		name string
-		want []*hostsfile.Record
-	}{{
-		req:  netip.AddrFrom4([4]byte{1, 0, 0, 1}),
-		name: "reverse",
-		want: testHosts[addr1001],
-	}}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			recs := hc.MatchAddr(tc.req)
-			assert.Equal(t, tc.want, recs)
-		})
-	}
-}

internal/aghnet/hostscontainer_windows.go

@@ -1,32 +0,0 @@
-//go:build windows
-
-package aghnet
-
-import (
-	"os"
-	"path"
-	"path/filepath"
-	"strings"
-
-	"github.com/AdguardTeam/golibs/log"
-	"golang.org/x/sys/windows"
-)
-
-func defaultHostsPaths() (paths []string) {
-	sysDir, err := windows.GetSystemDirectory()
-	if err != nil {
-		log.Error("aghnet: getting system directory: %s", err)
-
-		return []string{}
-	}
-
-	// Split all the elements of the path to join them afterwards.  This is
-	// needed to make the Windows-specific path string returned by
-	// windows.GetSystemDirectory to be compatible with fs.FS.
-	pathElems := strings.Split(sysDir, string(os.PathSeparator))
-	if len(pathElems) > 0 && pathElems[0] == filepath.VolumeName(sysDir) {
-		pathElems = pathElems[1:]
-	}
-
-	return []string{path.Join(append(pathElems, "drivers/etc/hosts")...)}
-}

internal/aghnet/net_test.go

@@ -1,11 +1,9 @@
 package aghnet_test
 
 import (
-	"io/fs"
 	"net"
 	"net/netip"
 	"net/url"
-	"os"
 	"testing"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
@@ -18,9 +16,6 @@ func TestMain(m *testing.M) {
 	testutil.DiscardLogOutput(m)
 }
 
-// testdata is the filesystem containing data for testing the package.
-var testdata fs.FS = os.DirFS("./testdata")
-
 func TestParseAddrPort(t *testing.T) {
 	const defaultPort = 1
 

internal/aghnet/testdata/etc_hosts

@@ -1,38 +0,0 @@
-#
-# Test /etc/hosts file
-#
-
-1.0.0.1 simplehost
-1.0.0.0 hello hello.world
-
-# See https://github.com/AdguardTeam/AdGuardHome/issues/3846.
-1.0.0.2 a.whole lot.of aliases for.testing
-
-# See https://github.com/AdguardTeam/AdGuardHome/issues/3946.
-1.0.0.3 *
-1.0.0.4 *.com
-
-# See https://github.com/AdguardTeam/AdGuardHome/issues/4079.
-1.0.0.0 hello.world.again
-
-# Duplicates of a main host and an alias.
-1.0.0.1 simplehost
-1.0.0.0 hello.world
-
-# Same for IPv6.
-::1 simplehost
-::  hello hello.world
-::2 a.whole lot.of aliases for.testing
-::3 *
-::4 *.com
-::  hello.world.again
-::1 simplehost
-::  hello.world
-
-# See https://github.com/AdguardTeam/AdGuardHome/issues/4216.
-4.2.1.6 domain domain.alias
-::42    domain.alias domain
-1.3.5.7 domain4 domain4.alias
-7.5.3.1 domain4.alias domain4
-::13    domain6 domain6.alias
-::31    domain6.alias domain6

internal/aghnet/testdata/ifaces

@@ -1 +0,0 @@
-iface sample_name inet static

internal/aghnet/testdata/include-subsources

@@ -1,5 +0,0 @@
-# The "testdata" part is added here because the test is actually run from the
-# parent directory.  Real interface files usually contain only absolute paths.
-
-source ./testdata/ifaces
-source ./testdata/*

internal/dnsforward/dnsforward.go

@@ -142,7 +142,7 @@ type Server struct {
 	// PTR resolving.
 	sysResolvers SystemResolvers
 
-	// etcHosts contains the data from the system's hosts files.
+	// etcHosts contains the current data from the system's hosts files.
 	etcHosts upstream.Resolver
 
 	// bootstrap is the resolver for upstreams' hostnames.
@@ -239,6 +239,11 @@ func NewServer(p DNSCreateParams) (s *Server, err error) {
 		p.Anonymizer = aghnet.NewIPMut(nil)
 	}
 
+	var etcHosts upstream.Resolver
+	if p.EtcHosts != nil {
+		etcHosts = upstream.NewHostsResolver(p.EtcHosts)
+	}
+
 	s = &Server{
 		dnsFilter:   p.DNSFilter,
 		dhcpServer:  p.DHCPServer,
@@ -247,6 +252,7 @@ func NewServer(p DNSCreateParams) (s *Server, err error) {
 		privateNets: p.PrivateNets,
 		// TODO(e.burkov):  Use some case-insensitive string comparison.
 		localDomainSuffix: strings.ToLower(localDomainSuffix),
+		etcHosts:          etcHosts,
 		recDetector:       newRecursionDetector(recursionTTL, cachedRecurrentReqNum),
 		clientIDCache: cache.New(cache.Config{
 			EnableLRU: true,
@@ -257,9 +263,6 @@ func NewServer(p DNSCreateParams) (s *Server, err error) {
 			ServePlainDNS: true,
 		},
 	}
-	if p.EtcHosts != nil {
-		s.etcHosts = p.EtcHosts
-	}
 
 	s.sysResolvers, err = sysresolv.NewSystemResolvers(nil, defaultPlainDNSPort)
 	if err != nil {

internal/dnsforward/http_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
 	"github.com/AdguardTeam/AdGuardHome/internal/filtering"
+	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/httphdr"
 	"github.com/AdguardTeam/golibs/netutil"
 	"github.com/AdguardTeam/golibs/testutil"
@@ -526,7 +527,7 @@ func TestServer_HandleTestUpstreamDNS(t *testing.T) {
 		},
 		ServePlainDNS: true,
 	}, nil)
-	srv.etcHosts = hc
+	srv.etcHosts = upstream.NewHostsResolver(hc)
 	startDeferStop(t, srv)
 
 	testCases := []struct {

internal/filtering/dnsrewrite.go

@@ -1,7 +1,6 @@
 package filtering
 
 import (
-	"github.com/AdguardTeam/golibs/hostsfile"
 	"github.com/AdguardTeam/urlfilter"
 	"github.com/AdguardTeam/urlfilter/rules"
 	"github.com/miekg/dns"
@@ -95,39 +94,3 @@ func (d *DNSFilter) processDNSResultRewrites(
 
 	return res
 }
-
-// appendRewriteResultFromHost appends the rewrite result from rec to vals and
-// resRules.
-func appendRewriteResultFromHost(
-	vals []rules.RRValue,
-	resRules []*ResultRule,
-	rec *hostsfile.Record,
-	qtype uint16,
-) (updatedVals []rules.RRValue, updatedRules []*ResultRule) {
-	switch qtype {
-	case dns.TypeA:
-		if !rec.Addr.Is4() {
-			return vals, resRules
-		}
-
-		vals = append(vals, rec.Addr)
-	case dns.TypeAAAA:
-		if !rec.Addr.Is6() {
-			return vals, resRules
-		}
-
-		vals = append(vals, rec.Addr)
-	case dns.TypePTR:
-		for _, name := range rec.Names {
-			vals = append(vals, name)
-		}
-	}
-
-	recText, _ := rec.MarshalText()
-	resRules = append(resRules, &ResultRule{
-		FilterListID: SysHostsListID,
-		Text:         string(recText),
-	})
-
-	return vals, resRules
-}

internal/filtering/dnsrewrite_test.go

@@ -220,15 +220,19 @@ func TestDNSFilter_CheckHost_hostsContainer(t *testing.T) {
 	addrv4 := netip.MustParseAddr("1.2.3.4")
 	addrv6 := netip.MustParseAddr("::1")
 	addrMapped := netip.MustParseAddr("::ffff:1.2.3.4")
+	addrv4Dup := netip.MustParseAddr("4.3.2.1")
 
 	data := fmt.Sprintf(
 		""+
-			"%s v4.host.example\n"+
+			"%[1]s v4.host.example\n"+
-			"%s v6.host.example\n"+
+			"%[2]s v6.host.example\n"+
-			"%s mapped.host.example\n",
+			"%[3]s mapped.host.example\n"+
+			"%[4]s v4.host.with-dup\n"+
+			"%[4]s v4.host.with-dup\n",
 		addrv4,
 		addrv6,
 		addrMapped,
+		addrv4Dup,
 	)
 
 	files := fstest.MapFS{
@@ -343,6 +347,15 @@ func TestDNSFilter_CheckHost_hostsContainer(t *testing.T) {
 		dtyp:      dns.TypeCNAME,
 		wantRules: nil,
 		wantResps: nil,
+	}, {
+		name: "v4_dup",
+		host: "v4.host.with-dup",
+		dtyp: dns.TypeA,
+		wantRules: []*ResultRule{{
+			Text:         "4.3.2.1 v4.host.with-dup",
+			FilterListID: SysHostsListID,
+		}},
+		wantResps: []rules.RRValue{addrv4Dup},
 	}}
 
 	for _, tc := range testCases {

internal/filtering/filtering.go

@@ -18,7 +18,6 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
-	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
 	"github.com/AdguardTeam/AdGuardHome/internal/filtering/rulelist"
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/hostsfile"
@@ -100,7 +99,7 @@ type Config struct {
 	// system configuration files (e.g. /etc/hosts).
 	//
 	// TODO(e.burkov):  Move it to dnsforward entirely.
-	EtcHosts *aghnet.HostsContainer `yaml:"-"`
+	EtcHosts hostsfile.Storage `yaml:"-"`
 
 	// Called when the configuration is changed by HTTP request
 	ConfigModified func() `yaml:"-"`
@@ -482,15 +481,6 @@ func (d *DNSFilter) SetProtectionEnabled(status bool) {
 	d.conf.ProtectionEnabled = status
 }
 
-// EtcHostsRecords returns the hosts records for the hostname.
-func (d *DNSFilter) EtcHostsRecords(hostname string) (recs []*hostsfile.Record) {
-	if d.conf.EtcHosts != nil {
-		return d.conf.EtcHosts.MatchName(hostname)
-	}
-
-	return recs
-}
-
 // SetBlockingMode sets blocking mode properties.
 func (d *DNSFilter) SetBlockingMode(mode BlockingMode, bIPv4, bIPv6 netip.Addr) {
 	d.confMu.Lock()
@@ -637,39 +627,10 @@ func (d *DNSFilter) matchSysHosts(
 ) (res Result, err error) {
 	// TODO(e.burkov):  Where else is this checked?
 	if !setts.FilteringEnabled || d.conf.EtcHosts == nil {
-		return res, nil
+		return Result{}, nil
-	}
-
-	var recs []*hostsfile.Record
-	switch qtype {
-	case dns.TypeA, dns.TypeAAAA:
-		recs = d.conf.EtcHosts.MatchName(host)
-	case dns.TypePTR:
-		var ip net.IP
-		ip, err = netutil.IPFromReversedAddr(host)
-		if err != nil {
-			log.Debug("filtering: failed to parse PTR record %q: %s", host, err)
-
-			return res, nil
-		}
-
-		addr, _ := netip.AddrFromSlice(ip)
-		recs = d.conf.EtcHosts.MatchAddr(addr)
-	default:
-		log.Debug("filtering: unsupported query type %s", dns.Type(qtype))
-	}
-
-	var vals []rules.RRValue
-	var resRules []*ResultRule
-	resRulesLen := 0
-	for _, rec := range recs {
-		vals, resRules = appendRewriteResultFromHost(vals, resRules, rec, qtype)
-		if len(resRules) > resRulesLen {
-			resRulesLen = len(resRules)
-			log.Debug("filtering: matched %s in %q", host, rec.Source)
-		}
 	}
 
+	vals, rs := hostsRewrites(qtype, host, d.conf.EtcHosts)
 	if len(vals) > 0 {
 		res.DNSRewriteResult = &DNSRewriteResult{
 			Response: DNSRewriteResultResponse{
@@ -677,13 +638,64 @@ func (d *DNSFilter) matchSysHosts(
 			},
 			RCode: dns.RcodeSuccess,
 		}
-		res.Rules = resRules
+		res.Rules = rs
-		res.Reason = RewrittenRule
+		res.Reason = RewrittenAutoHosts
 	}
 
 	return res, nil
 }
 
+// hostsRewrites returns values and rules matched by qt and host within hs.
+func hostsRewrites(
+	qtype uint16,
+	host string,
+	hs hostsfile.Storage,
+) (vals []rules.RRValue, rs []*ResultRule) {
+	var isValidProto func(netip.Addr) (ok bool)
+	switch qtype {
+	case dns.TypeA:
+		isValidProto = netip.Addr.Is4
+	case dns.TypeAAAA:
+		isValidProto = netip.Addr.Is6
+	case dns.TypePTR:
+		// TODO(e.burkov):  Add some [netip]-aware alternative to [netutil].
+		ip, err := netutil.IPFromReversedAddr(host)
+		if err != nil {
+			log.Debug("filtering: failed to parse PTR record %q: %s", host, err)
+
+			return nil, nil
+		}
+
+		addr, _ := netip.AddrFromSlice(ip)
+
+		for _, name := range hs.ByAddr(addr) {
+			vals = append(vals, name)
+			rs = append(rs, &ResultRule{
+				Text:         fmt.Sprintf("%s %s", addr, name),
+				FilterListID: SysHostsListID,
+			})
+		}
+
+		return vals, rs
+	default:
+		log.Debug("filtering: unsupported qtype %d", qtype)
+
+		return nil, nil
+	}
+
+	for _, addr := range hs.ByName(host) {
+		if isValidProto(addr) {
+			vals = append(vals, addr)
+			rs = append(rs, &ResultRule{
+				Text:         fmt.Sprintf("%s %s", addr, host),
+				FilterListID: SysHostsListID,
+			})
+		}
+	}
+
+	return vals, rs
+}
+
 // processRewrites performs filtering based on the legacy rewrite records.
 //
 // Firstly, it finds CNAME rewrites for host.  If the CNAME is the same as host,

internal/home/clients.go

@@ -20,6 +20,7 @@ import (
 	"github.com/AdguardTeam/dnsproxy/proxy"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/hostsfile"
 	"github.com/AdguardTeam/golibs/log"
 	"github.com/AdguardTeam/golibs/stringutil"
 	"golang.org/x/exp/maps"
@@ -139,6 +140,9 @@ func (clients *clientsContainer) Init(
 	return nil
 }
 
+// handleHostsUpdates receives the updates from the hosts container and adds
+// them to the clients container.  It's used to be called in a separate
+// goroutine.
 func (clients *clientsContainer) handleHostsUpdates() {
 	for upd := range clients.etcHosts.Upd() {
 		clients.addFromHostsFile(upd)
@@ -870,22 +874,25 @@ func (clients *clientsContainer) rmHostsBySrc(src client.Source) {
 
 // addFromHostsFile fills the client-hostname pairing index from the system's
 // hosts files.
-func (clients *clientsContainer) addFromHostsFile(hosts aghnet.Hosts) {
+func (clients *clientsContainer) addFromHostsFile(hosts *hostsfile.DefaultStorage) {
 	clients.lock.Lock()
 	defer clients.lock.Unlock()
 
 	clients.rmHostsBySrc(client.SourceHostsFile)
 
 	n := 0
-	for addr, rec := range hosts {
+	hosts.RangeNames(func(addr netip.Addr, names []string) (cont bool) {
 		// Only the first name of the first record is considered a canonical
 		// hostname for the IP address.
 		//
 		// TODO(e.burkov):  Consider using all the names from all the records.
-		clients.addHostLocked(addr, rec[0].Names[0], client.SourceHostsFile)
+		if clients.addHostLocked(addr, names[0], client.SourceHostsFile) {
 			n++
 		}
 
+		return true
+	})
+
 	log.Debug("clients: added %d client aliases from system hosts file", n)
 }
 

internal/home/home.go

@@ -35,8 +35,10 @@ import (
 	"github.com/AdguardTeam/AdGuardHome/internal/version"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/hostsfile"
 	"github.com/AdguardTeam/golibs/log"
 	"github.com/AdguardTeam/golibs/netutil"
+	"github.com/AdguardTeam/golibs/osutil"
 	"github.com/AdguardTeam/golibs/stringutil"
 	"golang.org/x/exp/slices"
 )
@@ -231,11 +233,12 @@ func setupHostsContainer() (err error) {
 		return fmt.Errorf("initing hosts watcher: %w", err)
 	}
 
-	Context.etcHosts, err = aghnet.NewHostsContainer(
+	paths, err := hostsfile.DefaultHostsPaths()
-		aghos.RootDirFS(),
+	if err != nil {
-		hostsWatcher,
+		return fmt.Errorf("getting default system hosts paths: %w", err)
-		aghnet.DefaultHostsPaths()...,
+	}
-	)
+
+	Context.etcHosts, err = aghnet.NewHostsContainer(osutil.RootDirFS(), hostsWatcher, paths...)
 	if err != nil {
 		closeErr := hostsWatcher.Close()
 		if errors.Is(err, aghnet.ErrNoHostsPaths) {

scripts/make/go-lint.sh

@@ -206,7 +206,6 @@ run_linter gocognit --over='11'\
 
 run_linter gocognit --over='10'\
 	./internal/aghalg/\
-	./internal/aghchan/\
 	./internal/aghhttp/\
 	./internal/aghrenameio/\
 	./internal/aghtest/\
@@ -244,7 +243,6 @@ run_linter nilness ./...
 # TODO(a.garipov): Enable for all.
 run_linter fieldalignment \
 	./internal/aghalg/\
-	./internal/aghchan/\
 	./internal/aghhttp/\
 	./internal/aghos/\
 	./internal/aghrenameio/\