Merge: - DNS: "custom_ip" blocking mode didn't work after app restart

Close #1262

Squashed commit of the following:

commit bacd683ef5b52e275323a3c07b370ca08702403e
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 16 17:00:49 2019 +0300

    fix

commit 3d4f9626460de3e13a621f2b8e535e9e0939e2bb
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 16 16:54:23 2019 +0300

    fix

commit bf924bf90e9b705883bec88f8d7af11c39c1f322
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 16 16:45:41 2019 +0300

    add test

commit 43338ea3645a025d69dd838bc732344255960bed
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 16 16:07:51 2019 +0300

    - DNS: "custom_ip" blocking mode didn't work after app restart

commit 220f32e713a95d2c67355c61e419dd09df9d42b2
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 16 15:46:01 2019 +0300

    - first run: fix panic on stop in case initialization didn't complete

    e.g. when Stats module can't be initialized because of incompatible file system

dnsforward/dnsforward.go

@@ -233,6 +233,13 @@ func (s *Server) startInternal() error {
 func (s *Server) Prepare(config *ServerConfig) error {
 	if config != nil {
 		s.conf = *config
+		if s.conf.BlockingMode == "custom_ip" {
+			s.conf.BlockingIPAddrv4 = net.ParseIP(s.conf.BlockingIPv4)
+			s.conf.BlockingIPAddrv6 = net.ParseIP(s.conf.BlockingIPv6)
+			if s.conf.BlockingIPAddrv4 == nil || s.conf.BlockingIPAddrv6 == nil {
+				return fmt.Errorf("DNS: invalid custom blocking IP address specified")
+			}
+		}
 	}
 
 	if len(s.conf.UpstreamDNS) == 0 {

dnsforward/dnsforward_test.go

@@ -424,6 +424,55 @@ func TestNullBlockedRequest(t *testing.T) {
 	}
 }
 
+func TestBlockedCustomIP(t *testing.T) {
+	rules := "||nxdomain.example.org^\n||null.example.org^\n127.0.0.1	host.example.org\n@@||whitelist.example.org^\n||127.0.0.255\n"
+	filters := map[int]string{}
+	filters[0] = rules
+	c := dnsfilter.Config{}
+
+	f := dnsfilter.New(&c, filters)
+	s := NewServer(f, nil, nil)
+	conf := ServerConfig{}
+	conf.UDPListenAddr = &net.UDPAddr{Port: 0}
+	conf.TCPListenAddr = &net.TCPAddr{Port: 0}
+	conf.ProtectionEnabled = true
+	conf.BlockingMode = "custom_ip"
+	conf.BlockingIPv4 = "bad IP"
+	conf.UpstreamDNS = []string{"8.8.8.8:53", "8.8.4.4:53"}
+	err := s.Prepare(&conf)
+	assert.True(t, err != nil) // invalid BlockingIPv4
+
+	conf.BlockingIPv4 = "0.0.0.1"
+	conf.BlockingIPv6 = "::1"
+	err = s.Prepare(&conf)
+	assert.True(t, err == nil)
+	err = s.Start()
+	assert.True(t, err == nil, "%s", err)
+
+	addr := s.dnsProxy.Addr(proxy.ProtoUDP)
+
+	req := createTestMessageWithType("null.example.org.", dns.TypeA)
+	reply, err := dns.Exchange(req, addr.String())
+	assert.True(t, err == nil)
+	assert.True(t, len(reply.Answer) == 1)
+	a, ok := reply.Answer[0].(*dns.A)
+	assert.True(t, ok)
+	assert.True(t, a.A.String() == "0.0.0.1")
+
+	req = createTestMessageWithType("null.example.org.", dns.TypeAAAA)
+	reply, err = dns.Exchange(req, addr.String())
+	assert.True(t, err == nil)
+	assert.True(t, len(reply.Answer) == 1)
+	a6, ok := reply.Answer[0].(*dns.AAAA)
+	assert.True(t, ok)
+	assert.True(t, a6.AAAA.String() == "::1")
+
+	err = s.Stop()
+	if err != nil {
+		t.Fatalf("DNS server failed to stop: %s", err)
+	}
+}
+
 func TestBlockedByHosts(t *testing.T) {
 	s := createTestServer(t)
 	err := s.Start()
@@ -652,6 +701,16 @@ func createTestMessage(host string) *dns.Msg {
 	return &req
 }
 
+func createTestMessageWithType(host string, qtype uint16) *dns.Msg {
+	req := dns.Msg{}
+	req.Id = dns.Id()
+	req.RecursionDesired = true
+	req.Question = []dns.Question{
+		{Name: host, Qtype: qtype, Qclass: dns.ClassINET},
+	}
+	return &req
+}
+
 func assertGoogleAResponse(t *testing.T, reply *dns.Msg) {
 	assertResponse(t, reply, "8.8.8.8")
 }

home/dns.go

@@ -70,6 +70,9 @@ func initDNSServer() error {
 
 	sessFilename := filepath.Join(baseDir, "sessions.db")
 	config.auth = InitAuth(sessFilename, config.Users, config.WebSessionTTLHours*60*60)
+	if config.auth == nil {
+		return fmt.Errorf("Couldn't initialize Auth module")
+	}
 	config.Users = nil
 
 	Context.rdns = InitRDNS(Context.dnsServer, &Context.clients)
@@ -254,6 +257,10 @@ func reconfigureDNSServer() error {
 }
 
 func stopDNSServer() error {
+	if !isRunning() {
+		return nil
+	}
+
 	err := Context.dnsServer.Stop()
 	if err != nil {
 		return errorx.Decorate(err, "Couldn't stop forwarding DNS server")