Pull request: all: allow local non-top-level domains

Updates #2961.

Squashed commit of the following:

commit 207eeb85caf6caee81a669302daf4e10a5b61585
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 15 18:48:50 2021 +0300

    all: allow local non-top-level domains

internal/dnsforward/dns.go

@@ -264,7 +264,7 @@ func (s *Server) processInternalHosts(dctx *dnsContext) (rc resultCode) {
 	}
 
 	reqHost := strings.ToLower(q.Name)
-	host := strings.TrimSuffix(reqHost, s.autohostSuffix)
+	host := strings.TrimSuffix(reqHost, s.localDomainSuffix)
 	if host == reqHost {
 		return resultCodeSuccess
 	}

internal/dnsforward/dns_test.go

@@ -90,7 +90,7 @@ func TestServer_ProcessInternalHosts_localRestriction(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			s := &Server{
-				autohostSuffix: defaultAutohostSuffix,
+				localDomainSuffix: defaultLocalDomainSuffix,
 				tableHostToIP: hostToIPTable{
 					"example": knownIP,
 				},
@@ -157,35 +157,35 @@ func TestServer_ProcessInternalHosts(t *testing.T) {
 	}{{
 		name:    "success_external",
 		host:    examplecom,
-		suffix:  defaultAutohostSuffix,
+		suffix:  defaultLocalDomainSuffix,
 		wantIP:  nil,
 		wantRes: resultCodeSuccess,
 		qtyp:    dns.TypeA,
 	}, {
 		name:    "success_external_non_a",
 		host:    examplecom,
-		suffix:  defaultAutohostSuffix,
+		suffix:  defaultLocalDomainSuffix,
 		wantIP:  nil,
 		wantRes: resultCodeSuccess,
 		qtyp:    dns.TypeCNAME,
 	}, {
 		name:    "success_internal",
 		host:    examplelan,
-		suffix:  defaultAutohostSuffix,
+		suffix:  defaultLocalDomainSuffix,
 		wantIP:  knownIP,
 		wantRes: resultCodeSuccess,
 		qtyp:    dns.TypeA,
 	}, {
 		name:    "success_internal_unknown",
 		host:    "example-new.lan",
-		suffix:  defaultAutohostSuffix,
+		suffix:  defaultLocalDomainSuffix,
 		wantIP:  nil,
 		wantRes: resultCodeFinish,
 		qtyp:    dns.TypeA,
 	}, {
 		name:    "success_internal_aaaa",
 		host:    examplelan,
-		suffix:  defaultAutohostSuffix,
+		suffix:  defaultLocalDomainSuffix,
 		wantIP:  nil,
 		wantRes: resultCodeSuccess,
 		qtyp:    dns.TypeAAAA,
@@ -201,7 +201,7 @@ func TestServer_ProcessInternalHosts(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			s := &Server{
-				autohostSuffix: tc.suffix,
+				localDomainSuffix: tc.suffix,
 				tableHostToIP: hostToIPTable{
 					"example": knownIP,
 				},

internal/dnsforward/dnsforward.go

@@ -70,9 +70,9 @@ type Server struct {
 	stats      stats.Stats
 	access     *accessCtx
 
-	// autohostSuffix is the suffix used to detect internal hosts.  It must
-	// be a valid top-level domain plus dots on each side.
-	autohostSuffix string
+	// localDomainSuffix is the suffix used to detect internal hosts.  It
+	// must be a valid domain name plus dots on each side.
+	localDomainSuffix string
 
 	ipset          ipsetCtx
 	subnetDetector *aghnet.SubnetDetector
@@ -94,9 +94,11 @@ type Server struct {
 	conf ServerConfig
 }
 
-// defaultAutohostSuffix is the default suffix used to detect internal hosts
-// when no suffix is provided.  See the documentation for Server.autohostSuffix.
-const defaultAutohostSuffix = ".lan."
+// defaultLocalDomainSuffix is the default suffix used to detect internal hosts
+// when no suffix is provided.
+//
+// See the documentation for Server.localDomainSuffix.
+const defaultLocalDomainSuffix = ".lan."
 
 // DNSCreateParams are parameters to create a new server.
 type DNSCreateParams struct {
@@ -105,11 +107,11 @@ type DNSCreateParams struct {
 	QueryLog       querylog.QueryLog
 	DHCPServer     dhcpd.ServerInterface
 	SubnetDetector *aghnet.SubnetDetector
-	AutohostTLD    string
+	LocalDomain    string
 }
 
-// tldToSuffix converts a top-level domain into an autohost suffix.
-func tldToSuffix(tld string) (suffix string) {
+// domainNameToSuffix converts a domain name into a local domain suffix.
+func domainNameToSuffix(tld string) (suffix string) {
 	l := len(tld) + 2
 	b := make([]byte, l)
 	b[0] = '.'
@@ -122,24 +124,24 @@ func tldToSuffix(tld string) (suffix string) {
 // NewServer creates a new instance of the dnsforward.Server
 // Note: this function must be called only once
 func NewServer(p DNSCreateParams) (s *Server, err error) {
-	var autohostSuffix string
-	if p.AutohostTLD == "" {
-		autohostSuffix = defaultAutohostSuffix
+	var localDomainSuffix string
+	if p.LocalDomain == "" {
+		localDomainSuffix = defaultLocalDomainSuffix
 	} else {
-		err = aghnet.ValidateDomainNameLabel(p.AutohostTLD)
+		err = aghnet.ValidateDomainName(p.LocalDomain)
 		if err != nil {
-			return nil, fmt.Errorf("autohost tld: %w", err)
+			return nil, fmt.Errorf("local domain: %w", err)
 		}
 
-		autohostSuffix = tldToSuffix(p.AutohostTLD)
+		localDomainSuffix = domainNameToSuffix(p.LocalDomain)
 	}
 
 	s = &Server{
-		dnsFilter:      p.DNSFilter,
-		stats:          p.Stats,
-		queryLog:       p.QueryLog,
-		subnetDetector: p.SubnetDetector,
-		autohostSuffix: autohostSuffix,
+		dnsFilter:         p.DNSFilter,
+		stats:             p.Stats,
+		queryLog:          p.QueryLog,
+		subnetDetector:    p.SubnetDetector,
+		localDomainSuffix: localDomainSuffix,
 	}
 
 	if p.DHCPServer != nil {

internal/dnsforward/dnsforward_test.go

@@ -232,10 +232,10 @@ func sendTestMessages(t *testing.T, conn *dns.Conn) {
 	for i := 0; i < testMessagesCount; i++ {
 		req := createGoogleATestMessage()
 		err := conn.WriteMsg(req)
-		assert.Nilf(t, err, "cannot write message #%d: %s", i, err)
+		assert.NoErrorf(t, err, "cannot write message #%d: %s", i, err)
 
 		res, err := conn.ReadMsg()
-		assert.Nilf(t, err, "cannot read response to message #%d: %s", i, err)
+		assert.NoErrorf(t, err, "cannot read response to message #%d: %s", i, err)
 		assertGoogleAResponse(t, res)
 	}
 }
@@ -1088,7 +1088,6 @@ func TestPTRResponseFromHosts(t *testing.T) {
 	_, _ = hf.WriteString("  127.0.0.1   host # comment \n")
 	_, _ = hf.WriteString("  ::1   localhost#comment  \n")
 
-	// Init auto hosts.
 	c.EtcHosts.Init(hf.Name())
 	t.Cleanup(c.EtcHosts.Close)
 
@@ -1145,17 +1144,24 @@ func TestNewServer(t *testing.T) {
 		in:         DNSCreateParams{},
 		wantErrMsg: "",
 	}, {
-		name: "success_autohost_tld",
+		name: "success_local_tld",
 		in: DNSCreateParams{
-			AutohostTLD: "mynet",
+			LocalDomain: "mynet",
 		},
 		wantErrMsg: "",
 	}, {
-		name: "bad_autohost_tld",
+		name: "success_local_domain",
 		in: DNSCreateParams{
-			AutohostTLD: "!!!",
+			LocalDomain: "my.local.net",
 		},
-		wantErrMsg: `autohost tld: invalid char '!' at index 0 in "!!!"`,
+		wantErrMsg: "",
+	}, {
+		name: "bad_local_domain",
+		in: DNSCreateParams{
+			LocalDomain: "!!!",
+		},
+		wantErrMsg: `local domain: invalid domain name label at index 0: ` +
+			`invalid char '!' at index 0 in "!!!"`,
 	}}
 
 	for _, tc := range testCases {