Pull request: all: use canonical names for hosts file runtime clients

Updates #4683.

Squashed commit of the following:

commit daa8fdaee574d4ac2171f6b13c5ce3f3fedd9801
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jul 7 19:13:29 2022 +0300

    all: use canonical names for hosts file runtime clients

CHANGELOG.md

@@ -23,7 +23,7 @@ and this project adheres to
 ### Added
 
 - Support for Discovery of Designated Resolvers (DDR) according to the [RFC
-  draft][ddr-draft-06] ([#4463]).
+  draft][ddr-draft] ([#4463]).
 - `windows/arm64` support ([#3057]).
 
 ### Deprecated
@@ -32,6 +32,7 @@ and this project adheres to
 
 ### Fixed
 
+- Inconsistent names of runtime clients from hosts files ([#4683]).
 - PTR requests for addresses leased by DHCP will now be resolved into hostnames
   under `dhcp.local_domain_name` ([#4699]).
 - Broken service installation on OpenWrt ([#4677]).
@@ -39,9 +40,10 @@ and this project adheres to
 [#2993]: https://github.com/AdguardTeam/AdGuardHome/issues/2993
 [#3057]: https://github.com/AdguardTeam/AdGuardHome/issues/3057
 [#4677]: https://github.com/AdguardTeam/AdGuardHome/issues/4677
+[#4683]: https://github.com/AdguardTeam/AdGuardHome/issues/4683
 [#4699]: https://github.com/AdguardTeam/AdGuardHome/issues/4699
 
-[ddr-draft-06]:   https://www.ietf.org/archive/id/draft-ietf-add-ddr-06.html
+[ddr-draft]: https://datatracker.ietf.org/doc/html/draft-ietf-add-ddr-08
 
 
 

internal/aghnet/hostscontainer.go

@@ -198,7 +198,7 @@ func (hc *HostsContainer) Close() (err error) {
 }
 
 // Upd returns the channel into which the updates are sent.  The receivable
-// map's values are guaranteed to be of type of *stringutil.Set.
+// map's values are guaranteed to be of type of *HostsRecord.
 func (hc *HostsContainer) Upd() (updates <-chan *netutil.IPMap) {
 	return hc.updates
 }
@@ -290,7 +290,7 @@ func (hp *hostsParser) parseFile(r io.Reader) (patterns []string, cont bool, err
 			continue
 		}
 
-		hp.addPairs(ip, hosts)
+		hp.addRecord(ip, hosts)
 	}
 
 	return nil, true, s.Err()
@@ -335,39 +335,66 @@ func (hp *hostsParser) parseLine(line string) (ip net.IP, hosts []string) {
 	return ip, hosts
 }
 
-// addPair puts the pair of ip and host to the rules builder if needed.  For
-// each ip the first member of hosts will become the main one.
-func (hp *hostsParser) addPairs(ip net.IP, hosts []string) {
-	v, ok := hp.table.Get(ip)
-	if !ok {
-		// This ip is added at the first time.
-		v = stringutil.NewSet()
-		hp.table.Set(ip, v)
+// HostsRecord represents a single hosts file record.
+type HostsRecord struct {
+	Aliases   *stringutil.Set
+	Canonical string
 }
 
-	var set *stringutil.Set
-	set, ok = v.(*stringutil.Set)
+// 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) {
+	line := strings.Join(append([]string{ip.String()}, hosts...), " ")
+
+	var rec *HostsRecord
+	v, ok := hp.table.Get(ip)
 	if !ok {
-		log.Debug("%s: adding pairs: unexpected value type %T", hostsContainerPref, v)
+		rec = &HostsRecord{
+			Aliases: stringutil.NewSet(),
+		}
+
+		rec.Canonical, hosts = hosts[0], hosts[1:]
+		hp.addRules(ip, rec.Canonical, line)
+		hp.table.Set(ip, rec)
+	} else {
+		rec, ok = v.(*HostsRecord)
+		if !ok {
+			log.Error("%s: adding pairs: unexpected type %T", hostsContainerPref, v)
 
 			return
 		}
+	}
 
-	processed := strings.Join(append([]string{ip.String()}, hosts...), " ")
-	for _, h := range hosts {
-		if set.Has(h) {
+	for _, host := range hosts {
+		if rec.Canonical == host || rec.Aliases.Has(host) {
 			continue
 		}
 
-		set.Add(h)
+		rec.Aliases.Add(host)
 
-		rule, rulePtr := hp.writeRules(h, ip)
-		hp.translations[rule], hp.translations[rulePtr] = processed, processed
-
-		log.Debug("%s: added ip-host pair %q-%q", hostsContainerPref, ip, h)
+		hp.addRules(ip, host, line)
 	}
 }
 
+// addRules adds rules and rule translations for the line.
+func (hp *hostsParser) addRules(ip net.IP, host, line string) {
+	rule, rulePtr := hp.writeRules(host, ip)
+	hp.translations[rule], hp.translations[rulePtr] = line, line
+
+	log.Debug("%s: added ip-host pair %q-%q", hostsContainerPref, ip, host)
+}
+
 // 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) {
@@ -417,6 +444,7 @@ func (hp *hostsParser) writeRules(host string, ip net.IP) (rule, rulePtr string)
 }
 
 // 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.
@@ -427,22 +455,35 @@ func (hp *hostsParser) equalSet(target *netutil.IPMap) (ok bool) {
 		return false
 	}
 
-	hp.table.Range(func(ip net.IP, b interface{}) (cont bool) {
-		// ok is set to true if the target doesn't contain ip or if the
-		// appropriate hosts set isn't equal to the checked one.
-		if a, hasIP := target.Get(ip); !hasIP {
-			ok = true
-		} else if hosts, aok := a.(*stringutil.Set); aok {
-			ok = !hosts.Equal(b.(*stringutil.Set))
+	hp.table.Range(func(ip net.IP, recVal interface{}) (cont bool) {
+		var targetVal interface{}
+		targetVal, ok = target.Get(ip)
+		if !ok {
+			return false
 		}
 
-		// Continue only if maps has no discrepancies.
-		return !ok
+		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 true if every value from the IP map has no discrepancies with the
-	// appropriate one from the target.
-	return !ok
+	return ok
 }
 
 // sendUpd tries to send the parsed data to the ch.

internal/aghnet/hostscontainer_test.go

@@ -12,6 +12,7 @@ import (
 
 	"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"
@@ -159,31 +160,47 @@ func TestHostsContainer_refresh(t *testing.T) {
 	require.NoError(t, err)
 	testutil.CleanupAndRequireSuccess(t, hc.Close)
 
-	checkRefresh := func(t *testing.T, wantHosts *stringutil.Set) {
-		upd, ok := <-hc.Upd()
+	checkRefresh := func(t *testing.T, want *HostsRecord) {
+		t.Helper()
+
+		var ok bool
+		var upd *netutil.IPMap
+		select {
+		case upd, ok = <-hc.Upd():
 			require.True(t, ok)
 			require.NotNil(t, upd)
+		case <-time.After(1 * time.Second):
+			t.Fatal("did not receive after 1s")
+		}
 
 		assert.Equal(t, 1, upd.Len())
 
 		v, ok := upd.Get(ip)
 		require.True(t, ok)
 
-		var set *stringutil.Set
-		set, ok = v.(*stringutil.Set)
-		require.True(t, ok)
+		require.IsType(t, (*HostsRecord)(nil), v)
 
-		assert.True(t, set.Equal(wantHosts))
+		rec, _ := v.(*HostsRecord)
+		require.NotNil(t, rec)
+
+		assert.Truef(t, rec.Equal(want), "%+v != %+v", rec, want)
 	}
 
 	t.Run("initial_refresh", func(t *testing.T) {
-		checkRefresh(t, stringutil.NewSet("hostname"))
+		checkRefresh(t, &HostsRecord{
+			Aliases:   stringutil.NewSet(),
+			Canonical: "hostname",
+		})
 	})
 
 	t.Run("second_refresh", func(t *testing.T) {
 		testFS["dir/file2"] = &fstest.MapFile{Data: []byte(ipStr + ` alias` + nl)}
 		eventsCh <- event{}
-		checkRefresh(t, stringutil.NewSet("hostname", "alias"))
+
+		checkRefresh(t, &HostsRecord{
+			Aliases:   stringutil.NewSet("alias"),
+			Canonical: "hostname",
+		})
 	})
 
 	t.Run("double_refresh", func(t *testing.T) {
@@ -363,10 +380,15 @@ func TestHostsContainer(t *testing.T) {
 	require.NoError(t, fstest.TestFS(testdata, "etc_hosts"))
 
 	testCases := []struct {
-		want []*rules.DNSRewrite
-		name string
 		req  *urlfilter.DNSRequest
+		name string
+		want []*rules.DNSRewrite
 	}{{
+		req: &urlfilter.DNSRequest{
+			Hostname: "simplehost",
+			DNSType:  dns.TypeA,
+		},
+		name: "simple",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			Value:  net.IPv4(1, 0, 0, 1),
@@ -376,27 +398,12 @@ func TestHostsContainer(t *testing.T) {
 			Value:  net.ParseIP("::1"),
 			RRType: dns.TypeAAAA,
 		}},
-		name: "simple",
-		req: &urlfilter.DNSRequest{
-			Hostname: "simplehost",
-			DNSType:  dns.TypeA,
-		},
 	}, {
-		want: []*rules.DNSRewrite{{
-			RCode:  dns.RcodeSuccess,
-			Value:  net.IPv4(1, 0, 0, 0),
-			RRType: dns.TypeA,
-		}, {
-			RCode:  dns.RcodeSuccess,
-			Value:  net.ParseIP("::"),
-			RRType: dns.TypeAAAA,
-		}},
-		name: "hello_alias",
 		req: &urlfilter.DNSRequest{
 			Hostname: "hello.world",
 			DNSType:  dns.TypeA,
 		},
-	}, {
+		name: "hello_alias",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			Value:  net.IPv4(1, 0, 0, 0),
@@ -406,26 +413,41 @@ func TestHostsContainer(t *testing.T) {
 			Value:  net.ParseIP("::"),
 			RRType: dns.TypeAAAA,
 		}},
-		name: "other_line_alias",
+	}, {
 		req: &urlfilter.DNSRequest{
 			Hostname: "hello.world.again",
 			DNSType:  dns.TypeA,
 		},
+		name: "other_line_alias",
+		want: []*rules.DNSRewrite{{
+			RCode:  dns.RcodeSuccess,
+			Value:  net.IPv4(1, 0, 0, 0),
+			RRType: dns.TypeA,
+		}, {
+			RCode:  dns.RcodeSuccess,
+			Value:  net.ParseIP("::"),
+			RRType: dns.TypeAAAA,
+		}},
 	}, {
-		want: []*rules.DNSRewrite{},
-		name: "hello_subdomain",
 		req: &urlfilter.DNSRequest{
 			Hostname: "say.hello",
 			DNSType:  dns.TypeA,
 		},
-	}, {
+		name: "hello_subdomain",
 		want: []*rules.DNSRewrite{},
-		name: "hello_alias_subdomain",
+	}, {
 		req: &urlfilter.DNSRequest{
 			Hostname: "say.hello.world",
 			DNSType:  dns.TypeA,
 		},
+		name: "hello_alias_subdomain",
+		want: []*rules.DNSRewrite{},
 	}, {
+		req: &urlfilter.DNSRequest{
+			Hostname: "for.testing",
+			DNSType:  dns.TypeA,
+		},
+		name: "lots_of_aliases",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			RRType: dns.TypeA,
@@ -435,37 +457,37 @@ func TestHostsContainer(t *testing.T) {
 			RRType: dns.TypeAAAA,
 			Value:  net.ParseIP("::2"),
 		}},
-		name: "lots_of_aliases",
-		req: &urlfilter.DNSRequest{
-			Hostname: "for.testing",
-			DNSType:  dns.TypeA,
-		},
 	}, {
+		req: &urlfilter.DNSRequest{
+			Hostname: "1.0.0.1.in-addr.arpa",
+			DNSType:  dns.TypePTR,
+		},
+		name: "reverse",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			RRType: dns.TypePTR,
 			Value:  "simplehost.",
 		}},
-		name: "reverse",
-		req: &urlfilter.DNSRequest{
-			Hostname: "1.0.0.1.in-addr.arpa",
-			DNSType:  dns.TypePTR,
-		},
 	}, {
-		want: []*rules.DNSRewrite{},
-		name: "non-existing",
 		req: &urlfilter.DNSRequest{
 			Hostname: "nonexisting",
 			DNSType:  dns.TypeA,
 		},
+		name: "non-existing",
+		want: []*rules.DNSRewrite{},
 	}, {
-		want: nil,
-		name: "bad_type",
 		req: &urlfilter.DNSRequest{
 			Hostname: "1.0.0.1.in-addr.arpa",
 			DNSType:  dns.TypeSRV,
 		},
+		name: "bad_type",
+		want: nil,
 	}, {
+		req: &urlfilter.DNSRequest{
+			Hostname: "domain",
+			DNSType:  dns.TypeA,
+		},
+		name: "issue_4216_4_6",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			RRType: dns.TypeA,
@@ -475,12 +497,12 @@ func TestHostsContainer(t *testing.T) {
 			RRType: dns.TypeAAAA,
 			Value:  net.ParseIP("::42"),
 		}},
-		name: "issue_4216_4_6",
+	}, {
 		req: &urlfilter.DNSRequest{
-			Hostname: "domain",
+			Hostname: "domain4",
 			DNSType:  dns.TypeA,
 		},
-	}, {
+		name: "issue_4216_4",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			RRType: dns.TypeA,
@@ -490,12 +512,12 @@ func TestHostsContainer(t *testing.T) {
 			RRType: dns.TypeA,
 			Value:  net.IPv4(1, 3, 5, 7),
 		}},
-		name: "issue_4216_4",
-		req: &urlfilter.DNSRequest{
-			Hostname: "domain4",
-			DNSType:  dns.TypeA,
-		},
 	}, {
+		req: &urlfilter.DNSRequest{
+			Hostname: "domain6",
+			DNSType:  dns.TypeAAAA,
+		},
+		name: "issue_4216_6",
 		want: []*rules.DNSRewrite{{
 			RCode:  dns.RcodeSuccess,
 			RRType: dns.TypeAAAA,
@@ -505,11 +527,6 @@ func TestHostsContainer(t *testing.T) {
 			RRType: dns.TypeAAAA,
 			Value:  net.ParseIP("::31"),
 		}},
-		name: "issue_4216_6",
-		req: &urlfilter.DNSRequest{
-			Hostname: "domain6",
-			DNSType:  dns.TypeAAAA,
-		},
 	}}
 
 	stubWatcher := aghtest.FSWatcher{

internal/aghnet/systemresolvers.go

@@ -19,7 +19,7 @@ type SystemResolvers interface {
 }
 
 // NewSystemResolvers returns a SystemResolvers with the cache refresh rate
-// defined by refreshIvl. It disables auto-resfreshing if refreshIvl is 0.  If
+// defined by refreshIvl. It disables auto-refreshing if refreshIvl is 0.  If
 // nil is passed for hostGenFunc, the default generator will be used.
 func NewSystemResolvers(
 	hostGenFunc HostGenFunc,

internal/home/clients.go

@@ -743,8 +743,7 @@ func (clients *clientsContainer) AddHost(ip net.IP, host string, src clientSourc
 
 // addHostLocked adds a new IP-hostname pairing.  For internal use only.
 func (clients *clientsContainer) addHostLocked(ip net.IP, host string, src clientSource) (ok bool) {
-	var rc *RuntimeClient
-	rc, ok = clients.findRuntimeClientLocked(ip)
+	rc, ok := clients.findRuntimeClientLocked(ip)
 	if ok {
 		if rc.Source > src {
 			return false
@@ -799,25 +798,20 @@ func (clients *clientsContainer) addFromHostsFile(hosts *netutil.IPMap) {
 
 	n := 0
 	hosts.Range(func(ip net.IP, v interface{}) (cont bool) {
-		hosts, ok := v.(*stringutil.Set)
+		rec, ok := v.(*aghnet.HostsRecord)
 		if !ok {
 			log.Error("dns: bad type %T in ipToRC for %s", v, ip)
 
 			return true
 		}
 
-		hosts.Range(func(name string) (cont bool) {
-			if clients.addHostLocked(ip, name, ClientSourceHostsFile) {
+		clients.addHostLocked(ip, rec.Canonical, ClientSourceHostsFile)
 		n++
-			}
 
 		return true
 	})
 
-		return true
-	})
-
-	log.Debug("clients: added %d client aliases from system hosts-file", n)
+	log.Debug("clients: added %d client aliases from system hosts file", n)
 }
 
 // addFromSystemARP adds the IP-hostname pairings from the output of the arp -a