Merge: dnsforward: support IPv6

Close #735

* commit 'e2579c72bdcafed41d5be1250fb38aeda0a8184e':
  * dnsfilter: fix tests
  + dnsforward: support IPv6 (AAAA response)
  * dnsfilter: return the correct IP address (host rules)

dnsfilter/dnsfilter.go

@@ -19,6 +19,7 @@ import (
 	"github.com/AdguardTeam/golibs/log"
 	"github.com/AdguardTeam/urlfilter"
 	"github.com/bluele/gcache"
+	"github.com/miekg/dns"
 	"golang.org/x/net/publicsuffix"
 )
 
@@ -147,7 +148,7 @@ func (r Reason) Matched() bool {
 }
 
 // CheckHost tries to match host against rules, then safebrowsing and parental if they are enabled
-func (d *Dnsfilter) CheckHost(host string) (Result, error) {
+func (d *Dnsfilter) CheckHost(host string, qtype uint16) (Result, error) {
 	// sometimes DNS clients will try to resolve ".", which is a request to get root servers
 	if host == "" {
 		return Result{Reason: NotFilteredNotFound}, nil
@@ -159,7 +160,7 @@ func (d *Dnsfilter) CheckHost(host string) (Result, error) {
 	}
 
 	// try filter lists first
-	result, err := d.matchHost(host)
+	result, err := d.matchHost(host, qtype)
 	if err != nil {
 		return result, err
 	}
@@ -517,7 +518,7 @@ func (d *Dnsfilter) initFiltering(filters map[int]string) error {
 }
 
 // matchHost is a low-level way to check only if hostname is filtered by rules, skipping expensive safebrowsing and parental lookups
-func (d *Dnsfilter) matchHost(host string) (Result, error) {
+func (d *Dnsfilter) matchHost(host string, qtype uint16) (Result, error) {
 	if d.filteringEngine == nil {
 		return Result{}, nil
 	}
@@ -527,6 +528,8 @@ func (d *Dnsfilter) matchHost(host string) (Result, error) {
 		return Result{}, nil
 	}
 
+	log.Tracef("%d rules matched for host '%s'", len(rules), host)
+
 	for _, rule := range rules {
 
 		log.Tracef("Found rule for host '%s': '%s'  list_id: %d",
@@ -548,8 +551,24 @@ func (d *Dnsfilter) matchHost(host string) (Result, error) {
 
 		} else if hostRule, ok := rule.(*urlfilter.HostRule); ok {
 
+			if qtype == dns.TypeA && hostRule.IP.To4() != nil {
+				// either IPv4 or IPv4-mapped IPv6 address
+				res.IP = hostRule.IP.To4()
+				return res, nil
+
+			} else if qtype == dns.TypeAAAA {
+				ip4 := hostRule.IP.To4()
+				if ip4 == nil {
 					res.IP = hostRule.IP
 					return res, nil
+				}
+				if bytes.Equal(ip4, []byte{0, 0, 0, 0}) {
+					// send IP="::" response for a rule "0.0.0.0 blockdomain"
+					res.IP = net.IPv6zero
+					return res, nil
+				}
+			}
+			continue
 
 		} else {
 			log.Tracef("Rule type is unsupported: '%s'  list_id: %d",

dnsfilter/dnsfilter_test.go

@@ -9,6 +9,8 @@ import (
 	"runtime"
 	"testing"
 	"time"
+
+	"github.com/miekg/dns"
 )
 
 // HELPERS
@@ -50,7 +52,7 @@ func NewForTestFilters(filters map[int]string) *Dnsfilter {
 
 func (d *Dnsfilter) checkMatch(t *testing.T, hostname string) {
 	t.Helper()
-	ret, err := d.CheckHost(hostname)
+	ret, err := d.CheckHost(hostname, dns.TypeA)
 	if err != nil {
 		t.Errorf("Error while matching host %s: %s", hostname, err)
 	}
@@ -59,9 +61,9 @@ func (d *Dnsfilter) checkMatch(t *testing.T, hostname string) {
 	}
 }
 
-func (d *Dnsfilter) checkMatchIP(t *testing.T, hostname string, ip string) {
+func (d *Dnsfilter) checkMatchIP(t *testing.T, hostname string, ip string, qtype uint16) {
 	t.Helper()
-	ret, err := d.CheckHost(hostname)
+	ret, err := d.CheckHost(hostname, qtype)
 	if err != nil {
 		t.Errorf("Error while matching host %s: %s", hostname, err)
 	}
@@ -75,7 +77,7 @@ func (d *Dnsfilter) checkMatchIP(t *testing.T, hostname string, ip string) {
 
 func (d *Dnsfilter) checkMatchEmpty(t *testing.T, hostname string) {
 	t.Helper()
-	ret, err := d.CheckHost(hostname)
+	ret, err := d.CheckHost(hostname, dns.TypeA)
 	if err != nil {
 		t.Errorf("Error while matching host %s: %s", hostname, err)
 	}
@@ -86,16 +88,25 @@ func (d *Dnsfilter) checkMatchEmpty(t *testing.T, hostname string) {
 
 func TestEtcHostsMatching(t *testing.T) {
 	addr := "216.239.38.120"
-	text := fmt.Sprintf("   %s  google.com www.google.com   # enforce google's safesearch   ", addr)
+	addr6 := "::1"
+	text := fmt.Sprintf("   %s  google.com www.google.com   # enforce google's safesearch   \n%s  google.com\n0.0.0.0 block.com\n",
+		addr, addr6)
 	filters := make(map[int]string)
 	filters[0] = text
 	d := NewForTestFilters(filters)
 	defer d.Destroy()
 
-	d.checkMatchIP(t, "google.com", addr)
+	d.checkMatchIP(t, "google.com", addr, dns.TypeA)
-	d.checkMatchIP(t, "www.google.com", addr)
+	d.checkMatchIP(t, "www.google.com", addr, dns.TypeA)
 	d.checkMatchEmpty(t, "subdomain.google.com")
 	d.checkMatchEmpty(t, "example.org")
+
+	// IPv6 address
+	d.checkMatchIP(t, "google.com", addr6, dns.TypeAAAA)
+
+	// block both IPv4 and IPv6
+	d.checkMatchIP(t, "block.com", "0.0.0.0", dns.TypeA)
+	d.checkMatchIP(t, "block.com", "::", dns.TypeAAAA)
 }
 
 // SAFE BROWSING
@@ -201,7 +212,7 @@ func TestCheckHostSafeSearchYandex(t *testing.T) {
 
 	// Check host for each domain
 	for _, host := range yandex {
-		result, err := d.CheckHost(host)
+		result, err := d.CheckHost(host, dns.TypeA)
 		if err != nil {
 			t.Errorf("SafeSearch doesn't work for yandex domain `%s` cause %s", host, err)
 		}
@@ -224,7 +235,7 @@ func TestCheckHostSafeSearchGoogle(t *testing.T) {
 
 	// Check host for each domain
 	for _, host := range googleDomains {
-		result, err := d.CheckHost(host)
+		result, err := d.CheckHost(host, dns.TypeA)
 		if err != nil {
 			t.Errorf("SafeSearch doesn't work for %s cause %s", host, err)
 		}
@@ -244,7 +255,7 @@ func TestSafeSearchCacheYandex(t *testing.T) {
 	var err error
 
 	// Check host with disabled safesearch
-	result, err = d.CheckHost(domain)
+	result, err = d.CheckHost(domain, dns.TypeA)
 	if err != nil {
 		t.Fatalf("Cannot check host due to %s", err)
 	}
@@ -254,7 +265,7 @@ func TestSafeSearchCacheYandex(t *testing.T) {
 
 	// Enable safesearch
 	d.SafeSearchEnabled = true
-	result, err = d.CheckHost(domain)
+	result, err = d.CheckHost(domain, dns.TypeA)
 	if err != nil {
 		t.Fatalf("CheckHost for safesearh domain %s failed cause %s", domain, err)
 	}
@@ -284,7 +295,7 @@ func TestSafeSearchCacheGoogle(t *testing.T) {
 	d := NewForTest()
 	defer d.Destroy()
 	domain := "www.google.ru"
-	result, err := d.CheckHost(domain)
+	result, err := d.CheckHost(domain, dns.TypeA)
 	if err != nil {
 		t.Fatalf("Cannot check host due to %s", err)
 	}
@@ -313,7 +324,7 @@ func TestSafeSearchCacheGoogle(t *testing.T) {
 		}
 	}
 
-	result, err = d.CheckHost(domain)
+	result, err = d.CheckHost(domain, dns.TypeA)
 	if err != nil {
 		t.Fatalf("CheckHost for safesearh domain %s failed cause %s", domain, err)
 	}
@@ -430,7 +441,7 @@ func TestMatching(t *testing.T) {
 			d := NewForTestFilters(filters)
 			defer d.Destroy()
 
-			ret, err := d.CheckHost(test.hostname)
+			ret, err := d.CheckHost(test.hostname, dns.TypeA)
 			if err != nil {
 				t.Errorf("Error while matching host %s: %s", test.hostname, err)
 			}
@@ -452,7 +463,7 @@ func BenchmarkSafeBrowsing(b *testing.B) {
 	d.SafeBrowsingEnabled = true
 	for n := 0; n < b.N; n++ {
 		hostname := "wmconvirus.narod.ru"
-		ret, err := d.CheckHost(hostname)
+		ret, err := d.CheckHost(hostname, dns.TypeA)
 		if err != nil {
 			b.Errorf("Error while matching host %s: %s", hostname, err)
 		}
@@ -469,7 +480,7 @@ func BenchmarkSafeBrowsingParallel(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
 			hostname := "wmconvirus.narod.ru"
-			ret, err := d.CheckHost(hostname)
+			ret, err := d.CheckHost(hostname, dns.TypeA)
 			if err != nil {
 				b.Errorf("Error while matching host %s: %s", hostname, err)
 			}

dnsforward/dnsforward.go

@@ -378,7 +378,7 @@ func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error
 	var res dnsfilter.Result
 	var err error
 
-	res, err = dnsFilter.CheckHost(host)
+	res, err = dnsFilter.CheckHost(host, d.Req.Question[0].Qtype)
 	if err != nil {
 		// Return immediately if there's an error
 		return nil, errorx.Decorate(err, "dnsfilter failed to check host '%s'", host)
@@ -394,7 +394,7 @@ func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error
 func (s *Server) genDNSFilterMessage(d *proxy.DNSContext, result *dnsfilter.Result) *dns.Msg {
 	m := d.Req
 
-	if m.Question[0].Qtype != dns.TypeA {
+	if m.Question[0].Qtype != dns.TypeA && m.Question[0].Qtype != dns.TypeAAAA {
 		return s.genNXDomain(m)
 	}
 
@@ -405,11 +405,25 @@ func (s *Server) genDNSFilterMessage(d *proxy.DNSContext, result *dnsfilter.Resu
 		return s.genBlockedHost(m, parentalBlockHost, d)
 	default:
 		if result.IP != nil {
+			if m.Question[0].Qtype == dns.TypeA {
 				return s.genARecord(m, result.IP)
+			} else if m.Question[0].Qtype == dns.TypeAAAA {
+				return s.genAAAARecord(m, result.IP)
+			}
+
+			// empty response
+			resp := dns.Msg{}
+			resp.SetReply(m)
+			return &resp
 		}
 
 		if s.conf.BlockingMode == "null_ip" {
-			return s.genARecord(m, net.IPv4zero)
+			switch m.Question[0].Qtype {
+			case dns.TypeA:
+				return s.genARecord(m, []byte{0, 0, 0, 0})
+			case dns.TypeAAAA:
+				return s.genAAAARecord(m, net.IPv6zero)
+			}
 		}
 
 		return s.genNXDomain(m)
@@ -426,15 +440,41 @@ func (s *Server) genServerFailure(request *dns.Msg) *dns.Msg {
 func (s *Server) genARecord(request *dns.Msg, ip net.IP) *dns.Msg {
 	resp := dns.Msg{}
 	resp.SetReply(request)
-	answer, err := dns.NewRR(fmt.Sprintf("%s %d A %s", request.Question[0].Name, s.conf.BlockedResponseTTL, ip.String()))
+	resp.Answer = append(resp.Answer, s.genAAnswer(request, ip))
-	if err != nil {
-		log.Printf("Couldn't generate A record for replacement host '%s': %s", ip.String(), err)
-		return s.genServerFailure(request)
-	}
-	resp.Answer = append(resp.Answer, answer)
 	return &resp
 }
 
+func (s *Server) genAAAARecord(request *dns.Msg, ip net.IP) *dns.Msg {
+	resp := dns.Msg{}
+	resp.SetReply(request)
+	resp.Answer = append(resp.Answer, s.genAAAAAnswer(request, ip))
+	return &resp
+}
+
+func (s *Server) genAAnswer(req *dns.Msg, ip net.IP) *dns.A {
+	answer := new(dns.A)
+	answer.Hdr = dns.RR_Header{
+		Name:   req.Question[0].Name,
+		Rrtype: dns.TypeA,
+		Ttl:    s.conf.BlockedResponseTTL,
+		Class:  dns.ClassINET,
+	}
+	answer.A = ip
+	return answer
+}
+
+func (s *Server) genAAAAAnswer(req *dns.Msg, ip net.IP) *dns.AAAA {
+	answer := new(dns.AAAA)
+	answer.Hdr = dns.RR_Header{
+		Name:   req.Question[0].Name,
+		Rrtype: dns.TypeAAAA,
+		Ttl:    s.conf.BlockedResponseTTL,
+		Class:  dns.ClassINET,
+	}
+	answer.AAAA = ip
+	return answer
+}
+
 func (s *Server) genBlockedHost(request *dns.Msg, newAddr string, d *proxy.DNSContext) *dns.Msg {
 	// look up the hostname, TODO: cache
 	replReq := dns.Msg{}