Pull request: all: do not check local domains when dhcp srv is off

Updates AdguardTeam#3028.

Squashed commit of the following:

commit 49d3ca5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 29 15:35:32 2021 +0300

    all: do not check local domains when dhcp srv is off

CHANGELOG.md

@@ -19,11 +19,13 @@ and this project adheres to
 
 ### Fixed
 
+- Local domain name handling when the DHCP server is disabled ([#3028]).
 - Normalization of perviously-saved invalid static DHCP leases ([#3027]).
 - Validation of IPv6 addresses with zones in system resolvers ([#3022]).
 
 [#3022]: https://github.com/AdguardTeam/AdGuardHome/issues/3022
 [#3027]: https://github.com/AdguardTeam/AdGuardHome/issues/3027
+[#3028]: https://github.com/AdguardTeam/AdGuardHome/issues/3028
 
 
 

internal/dhcpd/dhcpd.go

@@ -133,6 +133,7 @@ type Server struct {
 
 // ServerInterface is an interface for servers.
 type ServerInterface interface {
+	Enabled() (ok bool)
 	Leases(flags int) []Lease
 	SetOnLeaseChanged(onLeaseChanged OnLeaseChangedT)
 }
@@ -207,6 +208,11 @@ func Create(conf ServerConfig) *Server {
 	return s
 }
 
+// Enabled returns true when the server is enabled.
+func (s *Server) Enabled() (ok bool) {
+	return s.conf.Enabled
+}
+
 // server calls this function after DB is updated
 func (s *Server) onNotify(flags uint32) {
 	if flags == LeaseChangedDBStore {

internal/dnsforward/dns.go

@@ -249,6 +249,10 @@ func (s *Server) hostToIP(host string) (ip net.IP, ok bool) {
 //
 // TODO(a.garipov): Adapt to AAAA as well.
 func (s *Server) processInternalHosts(dctx *dnsContext) (rc resultCode) {
+	if !s.dhcpServer.Enabled() {
+		return resultCodeSuccess
+	}
+
 	req := dctx.proxyCtx.Req
 	q := req.Question[0]
 

internal/dnsforward/dns_test.go

@@ -90,6 +90,7 @@ func TestServer_ProcessInternalHosts_localRestriction(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			s := &Server{
+				dhcpServer:        &testDHCP{},
 				localDomainSuffix: defaultLocalDomainSuffix,
 				tableHostToIP: hostToIPTable{
 					"example": knownIP,
@@ -201,6 +202,7 @@ func TestServer_ProcessInternalHosts(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			s := &Server{
+				dhcpServer:        &testDHCP{},
 				localDomainSuffix: tc.suffix,
 				tableHostToIP: hostToIPTable{
 					"example": knownIP,
@@ -318,7 +320,7 @@ func TestLocalRestriction(t *testing.T) {
 		}
 		t.Run(tc.name, func(t *testing.T) {
 			err = s.handleDNSRequest(nil, pctx)
-			require.Nil(t, err)
+			require.NoError(t, err)
 			require.NotNil(t, pctx.Res)
 			require.Len(t, pctx.Res.Answer, tc.wantLen)
 			if tc.wantLen > 0 {

internal/dnsforward/dnsforward_test.go

@@ -75,6 +75,7 @@ func createTestServer(
 	require.NotNil(t, snd)
 
 	s, err = NewServer(DNSCreateParams{
+		DHCPServer:     &testDHCP{},
 		DNSFilter:      f,
 		SubnetDetector: snd,
 	})
@@ -736,6 +737,7 @@ func TestBlockedCustomIP(t *testing.T) {
 
 	var s *Server
 	s, err = NewServer(DNSCreateParams{
+		DHCPServer:     &testDHCP{},
 		DNSFilter:      dnsfilter.New(&dnsfilter.Config{}, filters),
 		SubnetDetector: snd,
 	})
@@ -873,6 +875,7 @@ func TestRewrite(t *testing.T) {
 
 	var s *Server
 	s, err = NewServer(DNSCreateParams{
+		DHCPServer:     &testDHCP{},
 		DNSFilter:      f,
 		SubnetDetector: snd,
 	})
@@ -1016,11 +1019,13 @@ func TestMatchDNSName(t *testing.T) {
 
 type testDHCP struct{}
 
+func (d *testDHCP) Enabled() (ok bool) { return true }
+
 func (d *testDHCP) Leases(flags int) []dhcpd.Lease {
 	l := dhcpd.Lease{
-		IP:       net.IP{127, 0, 0, 1},
+		IP:       net.IP{192, 168, 12, 34},
 		HWAddr:   net.HardwareAddr{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA},
-		Hostname: "localhost",
+		Hostname: "myhost",
 	}
 
 	return []dhcpd.Lease{l}
@@ -1056,19 +1061,19 @@ func TestPTRResponseFromDHCPLeases(t *testing.T) {
 	})
 
 	addr := s.dnsProxy.Addr(proxy.ProtoUDP)
-	req := createTestMessageWithType("1.0.0.127.in-addr.arpa.", dns.TypePTR)
+	req := createTestMessageWithType("34.12.168.192.in-addr.arpa.", dns.TypePTR)
 
 	resp, err := dns.Exchange(req, addr.String())
 	require.NoError(t, err)
 
 	require.Len(t, resp.Answer, 1)
 
 	assert.Equal(t, dns.TypePTR, resp.Answer[0].Header().Rrtype)
-	assert.Equal(t, "1.0.0.127.in-addr.arpa.", resp.Answer[0].Header().Name)
+	assert.Equal(t, "34.12.168.192.in-addr.arpa.", resp.Answer[0].Header().Name)
 
 	ptr, ok := resp.Answer[0].(*dns.PTR)
 	require.True(t, ok)
-	assert.Equal(t, "localhost.", ptr.Ptr)
+	assert.Equal(t, "myhost.", ptr.Ptr)
 }
 
 func TestPTRResponseFromHosts(t *testing.T) {
@@ -1098,6 +1103,7 @@ func TestPTRResponseFromHosts(t *testing.T) {
 
 	var s *Server
 	s, err = NewServer(DNSCreateParams{
+		DHCPServer:     &testDHCP{},
 		DNSFilter:      dnsfilter.New(&c, nil),
 		SubnetDetector: snd,
 	})

internal/home/home.go

@@ -184,6 +184,10 @@ func setupConfig(args options) {
 
 	Context.dhcpServer = dhcpd.Create(config.DHCP)
 	if Context.dhcpServer == nil {
+		// TODO(a.garipov): There are a lot of places in the code right
+		// now which assume that the DHCP server can be nil despite this
+		// condition.  Inspect them and perhaps rewrite them to use
+		// Enabled() instead.
 		log.Fatalf("can't initialize dhcp module")
 	}