Pull request 1973: 6132 fix hosts stratup

Merge in DNS/adguard-home from 6132-fix-hosts-startup to master

Updates #6132.

Squashed commit of the following:

commit 7495e62531f7c0bd775969195da1cbd446f018f7
Merge: c5d99bcef 4b04c620f
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 18:50:14 2023 +0300

    Merge branch 'master' into 6132-fix-hosts-startup

commit c5d99bcefa870ba0d2543158e97b3001f65be459
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 18:01:17 2023 +0300

    filtering: fix hosts results

commit b7acf266ad73520a0b795c495c8fc75c547ed993
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 17:34:43 2023 +0300

    all: revert changes of log of changes

commit 293240d5b1277cebd26732c535ad004af76df532
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 17:30:07 2023 +0300

    aghnet: imp logs

commit d1f7d73477a1a8fed5b1fb8b7f42d1c92acd919c
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 17:19:54 2023 +0300

    aghnet: impl handle set

commit b643793c537fcdd4ba00bae4d7207cb4f1d60d80
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Aug 23 17:00:05 2023 +0300

    aghnet: fix initial refresh

internal/aghnet/hostscontainer.go

@@ -201,7 +201,7 @@ func (hc *HostsContainer) handleEvents() {
 			}
 
 			if err := hc.refresh(); err != nil {
-				log.Error("%s: %s", hostsContainerPrefix, err)
+				log.Error("%s: warning: refreshing: %s", hostsContainerPrefix, err)
 			}
 		case _, ok = <-hc.done:
 			// Go on.
@@ -244,9 +244,7 @@ func (idx *hostsIndex) walk(r io.Reader) (patterns []string, cont bool, err erro
 // type check
 var _ hostsfile.Set = (*hostsIndex)(nil)
 
-// Add puts the record for the IP address to the rules builder if needed.
+// Add implements the [hostsfile.Set] interface for *hostsIndex.
-// The first host is considered to be the canonical name for the IP address.
-// hosts must have at least one name.
 func (idx *hostsIndex) Add(rec *hostsfile.Record) {
 	idx.addrs[rec.Addr] = append(idx.addrs[rec.Addr], rec)
 	for _, name := range rec.Names {
@@ -254,6 +252,23 @@ func (idx *hostsIndex) Add(rec *hostsfile.Record) {
 	}
 }
 
+// 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)
@@ -291,13 +306,9 @@ func (hc *HostsContainer) refresh() (err error) {
 	}
 
 	_, err = aghos.FileWalker(idx.walk).Walk(hc.fsys, hc.patterns...)
-
 	if err != nil {
-		if len(idx.addrs) == 0 {
+		// Don't wrap the error since it's informative enough as is.
-			return fmt.Errorf("refreshing : %w", err)
+		return err
-		} else {
-			log.Debug("%s: refreshing: %s", hostsContainerPrefix, err)
-		}
 	}
 
 	// TODO(e.burkov):  Serialize updates using time.

internal/filtering/dnsrewrite.go

@@ -1,8 +1,6 @@
 package filtering
 
 import (
-	"net"
-
 	"github.com/AdguardTeam/golibs/hostsfile"
 	"github.com/AdguardTeam/urlfilter"
 	"github.com/AdguardTeam/urlfilter/rules"
@@ -112,13 +110,13 @@ func appendRewriteResultFromHost(
 			return vals, resRules
 		}
 
-		vals = append(vals, net.IP(rec.Addr.AsSlice()))
+		vals = append(vals, rec.Addr)
 	case dns.TypeAAAA:
 		if !rec.Addr.Is6() {
 			return vals, resRules
 		}
 
-		vals = append(vals, net.IP(rec.Addr.AsSlice()))
+		vals = append(vals, rec.Addr)
 	case dns.TypePTR:
 		for _, name := range rec.Names {
 			vals = append(vals, name)

internal/filtering/dnsrewrite_test.go

@@ -2,7 +2,6 @@ package filtering
 
 import (
 	"fmt"
-	"net"
 	"net/netip"
 	"path"
 	"testing"
@@ -265,7 +264,7 @@ func TestDNSFilter_CheckHost_hostsContainer(t *testing.T) {
 			Text:         "1.2.3.4 v4.host.example",
 			FilterListID: SysHostsListID,
 		}},
-		wantResps: []rules.RRValue{net.IP(addrv4.AsSlice())},
+		wantResps: []rules.RRValue{addrv4},
 	}, {
 		name: "v6",
 		host: "v6.host.example",
@@ -274,7 +273,7 @@ func TestDNSFilter_CheckHost_hostsContainer(t *testing.T) {
 			Text:         "::1 v6.host.example",
 			FilterListID: SysHostsListID,
 		}},
-		wantResps: []rules.RRValue{net.IP(addrv6.AsSlice())},
+		wantResps: []rules.RRValue{addrv6},
 	}, {
 		name: "mapped",
 		host: "mapped.host.example",
@@ -283,7 +282,7 @@ func TestDNSFilter_CheckHost_hostsContainer(t *testing.T) {
 			Text:         "::ffff:1.2.3.4 mapped.host.example",
 			FilterListID: SysHostsListID,
 		}},
-		wantResps: []rules.RRValue{net.IP(addrMapped.AsSlice())},
+		wantResps: []rules.RRValue{addrMapped},
 	}, {
 		name: "ptr",
 		host: "4.3.2.1.in-addr.arpa",