Pull request 2200: 6312-client-ipv6-zone

Updates #6312.

Squashed commit of the following:

commit bd9146ee161a67fa41763070f985e1e73b85823b
Merge: 58d2fd98d 856cc40cf
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Apr 24 18:09:19 2024 +0300

    Merge branch 'master' into 6312-client-ipv6-zone

commit 58d2fd98d3e82c84638d58dd4d74d13a9a8fbca6
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Apr 24 18:00:56 2024 +0300

    client: imp naming

commit 922a14b036d829c2775feb7bb3e6beb6aa49692e
Merge: 6f4d58fe1 60f48e2d0
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Apr 24 14:29:00 2024 +0300

    Merge branch 'master' into 6312-client-ipv6-zone

commit 6f4d58fe1c42504e8345bff24dbb3f523e8c5f85
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Apr 24 14:27:55 2024 +0300

    client: imp docs

commit fa292eee828cd6f27f62b782675aa1f998e44518
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Apr 22 19:20:28 2024 +0300

    client: fix typo

commit 599414be0ccd3f9deb044e022a8ac0006c96b467
Merge: 502571756 762ef4a6d
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Apr 22 18:42:06 2024 +0300

    Merge branch 'master' into 6312-client-ipv6-zone

commit 502571756400a00445086b5ba412e03fca65e39f
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Apr 22 18:39:22 2024 +0300

    all: imp code; add tests

commit 155b2fef500a0d835f49957d9f30b0870712f6f2
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Tue Apr 16 19:56:00 2024 +0300

    all: upd chlog; imp code

commit 7a4426c5d0a511cd3865884c00328b8c130746bf
Merge: e9c1cbb85 48c6242a7
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Tue Apr 16 19:52:00 2024 +0300

    Merge branch 'master' into 6312-client-ipv6-zone

commit e9c1cbb85e4afa173969d5bedfaaaf92716b7fad
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Wed Apr 10 16:23:07 2024 +0300

    client: client ipv6 zone

CHANGELOG.md

@@ -34,6 +34,8 @@ NOTE: Add new changes BELOW THIS COMMENT.
 
 ### Fixed
 
+- Support for link-local subnets, i.e. `fe80::/16`, as client identifiers
+  ([#6312]).
 - Issues with QUIC and HTTP/3 upstreams on older Linux kernel versions
   ([#6422]).
 - YouTube restricted mode is not enforced by HTTPS queries on Firefox.
@@ -51,6 +53,7 @@ NOTE: Add new changes BELOW THIS COMMENT.
 [#5345]: https://github.com/AdguardTeam/AdGuardHome/issues/5345
 [#5812]: https://github.com/AdguardTeam/AdGuardHome/issues/5812
 [#6192]: https://github.com/AdguardTeam/AdGuardHome/issues/6192
+[#6312]: https://github.com/AdguardTeam/AdGuardHome/issues/6312
 [#6422]: https://github.com/AdguardTeam/AdGuardHome/issues/6422
 [#6854]: https://github.com/AdguardTeam/AdGuardHome/issues/6854
 [#6875]: https://github.com/AdguardTeam/AdGuardHome/issues/6875

internal/client/index.go

@@ -197,8 +197,10 @@ func (ci *Index) findByIP(ip netip.Addr) (c *Persistent, found bool) {
 		return ci.uidToClient[uid], true
 	}
 
+	ipWithoutZone := ip.WithZone("")
 	ci.subnetToUID.Range(func(pref netip.Prefix, id UID) (cont bool) {
-		if pref.Contains(ip) {
+		// Remove zone before checking because prefixes strip zones.
+		if pref.Contains(ipWithoutZone) {
 			uid, found = id, true
 
 			return false
@@ -214,6 +216,26 @@ func (ci *Index) findByIP(ip netip.Addr) (c *Persistent, found bool) {
 	return nil, false
 }
 
+// FindByIPWithoutZone finds a persistent client by IP address without zone.  It
+// strips the IPv6 zone index from the stored IP addresses before comparing,
+// because querylog entries don't have it.  See TODO on [querylog.logEntry.IP].
+//
+// Note that multiple clients can have the same IP address with different zones.
+// Therefore, the result of this method is indeterminate.
+func (ci *Index) FindByIPWithoutZone(ip netip.Addr) (c *Persistent) {
+	if (ip == netip.Addr{}) {
+		return nil
+	}
+
+	for addr, uid := range ci.ipToUID {
+		if addr.WithZone("") == ip {
+			return ci.uidToClient[uid]
+		}
+	}
+
+	return nil
+}
+
 // find finds persistent client by MAC.
 func (ci *Index) findByMAC(mac net.HardwareAddr) (c *Persistent, found bool) {
 	k := macToKey(mac)

internal/client/index_internal_test.go

@@ -35,27 +35,49 @@ func TestClientIndex(t *testing.T) {
 
 		cliID  = "client-id"
 		cliMAC = "11:11:11:11:11:11"
+
+		linkLocalIP     = "fe80::abcd:abcd:abcd:ab%eth0"
+		linkLocalSubnet = "fe80::/16"
 	)
 
-	clients := []*Persistent{{
-		Name: "client1",
-		IPs: []netip.Addr{
-			netip.MustParseAddr(cliIP1),
-			netip.MustParseAddr(cliIPv6),
-		},
-	}, {
-		Name:    "client2",
-		IPs:     []netip.Addr{netip.MustParseAddr(cliIP2)},
-		Subnets: []netip.Prefix{netip.MustParsePrefix(cliSubnet)},
-	}, {
-		Name: "client_with_mac",
-		MACs: []net.HardwareAddr{mustParseMAC(cliMAC)},
-	}, {
-		Name:      "client_with_id",
-		ClientIDs: []string{cliID},
-	}}
+	var (
+		clientWithBothFams = &Persistent{
+			Name: "client1",
+			IPs: []netip.Addr{
+				netip.MustParseAddr(cliIP1),
+				netip.MustParseAddr(cliIPv6),
+			},
+		}
 
-	ci := newIDIndex(clients)
+		clientWithSubnet = &Persistent{
+			Name:    "client2",
+			IPs:     []netip.Addr{netip.MustParseAddr(cliIP2)},
+			Subnets: []netip.Prefix{netip.MustParsePrefix(cliSubnet)},
+		}
+
+		clientWithMAC = &Persistent{
+			Name: "client_with_mac",
+			MACs: []net.HardwareAddr{mustParseMAC(cliMAC)},
+		}
+
+		clientWithID = &Persistent{
+			Name:      "client_with_id",
+			ClientIDs: []string{cliID},
+		}
+
+		clientLinkLocal = &Persistent{
+			Name:    "client_link_local",
+			Subnets: []netip.Prefix{netip.MustParsePrefix(linkLocalSubnet)},
+		}
+	)
+
+	ci := newIDIndex([]*Persistent{
+		clientWithBothFams,
+		clientWithSubnet,
+		clientWithMAC,
+		clientWithID,
+		clientLinkLocal,
+	})
 
 	testCases := []struct {
 		want *Persistent
@@ -64,19 +86,23 @@ func TestClientIndex(t *testing.T) {
 	}{{
 		name: "ipv4_ipv6",
 		ids:  []string{cliIP1, cliIPv6},
-		want: clients[0],
+		want: clientWithBothFams,
 	}, {
 		name: "ipv4_subnet",
 		ids:  []string{cliIP2, cliSubnetIP},
-		want: clients[1],
+		want: clientWithSubnet,
 	}, {
 		name: "mac",
 		ids:  []string{cliMAC},
-		want: clients[2],
+		want: clientWithMAC,
 	}, {
 		name: "client_id",
 		ids:  []string{cliID},
-		want: clients[3],
+		want: clientWithID,
+	}, {
+		name: "client_link_local_subnet",
+		ids:  []string{linkLocalIP},
+		want: clientLinkLocal,
 	}}
 
 	for _, tc := range testCases {
@@ -221,3 +247,52 @@ func TestMACToKey(t *testing.T) {
 		_ = macToKey(mac)
 	})
 }
+
+func TestIndex_FindByIPWithoutZone(t *testing.T) {
+	var (
+		ip         = netip.MustParseAddr("fe80::a098:7654:32ef:ff1")
+		ipWithZone = netip.MustParseAddr("fe80::1ff:fe23:4567:890a%eth2")
+	)
+
+	var (
+		clientNoZone = &Persistent{
+			Name: "client",
+			IPs:  []netip.Addr{ip},
+		}
+
+		clientWithZone = &Persistent{
+			Name: "client_with_zone",
+			IPs:  []netip.Addr{ipWithZone},
+		}
+	)
+
+	ci := newIDIndex([]*Persistent{
+		clientNoZone,
+		clientWithZone,
+	})
+
+	testCases := []struct {
+		ip   netip.Addr
+		want *Persistent
+		name string
+	}{{
+		name: "without_zone",
+		ip:   ip,
+		want: clientNoZone,
+	}, {
+		name: "with_zone",
+		ip:   ipWithZone,
+		want: clientWithZone,
+	}, {
+		name: "zero_address",
+		ip:   netip.Addr{},
+		want: nil,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			c := ci.FindByIPWithoutZone(tc.ip.WithZone(""))
+			require.Equal(t, tc.want, c)
+		})
+	}
+}

internal/home/clients.go

@@ -412,7 +412,11 @@ func (clients *clientsContainer) clientOrArtificial(
 	}()
 
 	cli, ok := clients.find(id)
-	if ok {
+	if !ok {
+		cli = clients.clientIndex.FindByIPWithoutZone(ip)
+	}
+
+	if cli != nil {
 		return &querylog.Client{
 			Name:           cli.Name,
 			IgnoreQueryLog: cli.IgnoreQueryLog,

internal/querylog/entry.go

@@ -31,6 +31,7 @@ type logEntry struct {
 	Answer     []byte `json:",omitempty"`
 	OrigAnswer []byte `json:",omitempty"`
 
+	// TODO(s.chzhen):  Use netip.Addr.
 	IP net.IP `json:"IP"`
 
 	Result filtering.Result