all: rewrites

internal/dnsforward/dnsforward_test.go

@@ -947,12 +947,11 @@ func TestRewrite(t *testing.T) {
 		reply, eerr = dns.Exchange(req, addr.String())
 		require.NoError(t, eerr)
 
-		// TODO (d.kolyshev): Investigate
+		require.Len(t, reply.Answer, 2)
-		// require.Len(t, reply.Answer, 2)
 
-		// assert.Equal(t, "test.com.", reply.Answer[0].(*dns.CNAME).Target)
+		assert.Equal(t, "test.com.", reply.Answer[0].(*dns.CNAME).Target)
-		// assert.True(t, net.IP{1, 2, 3, 4}.Equal(reply.Answer[1].(*dns.A).A))
+		assert.Equal(t, dns.TypeA, reply.Answer[1].Header().Rrtype)
-		assert.True(t, net.IP{1, 2, 3, 4}.Equal(reply.Answer[0].(*dns.A).A))
+		assert.True(t, net.IP{1, 2, 3, 4}.Equal(reply.Answer[1].(*dns.A).A))
 
 		req = createTestMessageWithType("my.alias.example.org.", dns.TypeA)
 		reply, eerr = dns.Exchange(req, addr.String())
@@ -963,11 +962,10 @@ func TestRewrite(t *testing.T) {
 
 		assert.Equal(t, "my.alias.example.org.", reply.Question[0].Name)
 
-		// TODO (d.kolyshev): Investigate
+		require.Len(t, reply.Answer, 2)
-		//require.Len(t, reply.Answer, 2)
+
-		//
+		assert.Equal(t, "example.org.", reply.Answer[0].(*dns.CNAME).Target)
-		//assert.Equal(t, "example.org.", reply.Answer[0].(*dns.CNAME).Target)
+		assert.Equal(t, dns.TypeA, reply.Answer[1].Header().Rrtype)
-		//assert.Equal(t, dns.TypeA, reply.Answer[1].Header().Rrtype)
 	}
 
 	for _, protect := range []bool{true, false} {

internal/filtering/filtering.go

@@ -577,6 +577,8 @@ func setRewriteResult(res *Result, host string, dnsr []*rules.DNSRewrite, qtype
 			res.IPList = append(res.IPList, ip)
 
 			log.Debug("rewrite: a/aaaa for %s is %s", host, ip)
+		} else if dnsRewrite.NewCNAME != "" {
+			res.CanonName = dnsRewrite.NewCNAME
 		}
 	}
 }

internal/filtering/rewrite/storage.go

@@ -87,25 +87,27 @@ func (s *DefaultStorage) MatchRequest(dReq *urlfilter.DNSRequest) (rws []*rules.
 	// TODO(a.garipov): Check cnames for cycles on initialisation.
 	cnames := stringutil.NewSet()
 	host := dReq.Hostname
+	var lastCNAMERule *rules.NetworkRule
 	for len(rrules) > 0 && rrules[0].DNSRewrite != nil && rrules[0].DNSRewrite.NewCNAME != "" {
-		rule := rrules[0]
+		lastCNAMERule = rrules[0]
-		rwAns := rule.DNSRewrite.NewCNAME
+		lastDNSRewrite := lastCNAMERule.DNSRewrite
+		rwAns := lastDNSRewrite.NewCNAME
 
 		log.Debug("rewrite: cname for %s is %s", host, rwAns)
 
 		if dReq.Hostname == rwAns {
-			// A request for the hostname itself is an exception rule.
+			// A request for the hostname itself is an exception lastCNAMERule.
 			// TODO(d.kolyshev): Check rewrite of a pattern onto itself.
 
 			return nil
 		}
 
-		if host == rwAns && isWildcard(rule.RuleText) {
+		if host == rwAns && isWildcard(lastCNAMERule.RuleText) {
 			// An "*.example.com → sub.example.com" rewrite matching in a loop.
 			//
 			// See https://github.com/AdguardTeam/AdGuardHome/issues/4016.
 
-			return []*rules.DNSRewrite{rule.DNSRewrite}
+			return []*rules.DNSRewrite{lastDNSRewrite}
 		}
 
 		if cnames.Has(rwAns) {
@@ -129,14 +131,19 @@ func (s *DefaultStorage) MatchRequest(dReq *urlfilter.DNSRequest) (rws []*rules.
 		host = rwAns
 	}
 
-	return s.collectDNSRewrites(rrules, dReq.DNSType)
+	return s.collectDNSRewrites(rrules, lastCNAMERule, dReq.DNSType)
 }
 
 // collectDNSRewrites filters DNSRewrite by question type.
 func (s *DefaultStorage) collectDNSRewrites(
 	rewrites []*rules.NetworkRule,
+	cnameRule *rules.NetworkRule,
 	qtyp uint16,
 ) (rws []*rules.DNSRewrite) {
+	if cnameRule != nil {
+		rewrites = append([]*rules.NetworkRule{cnameRule}, rewrites...)
+	}
+
 	for _, rewrite := range rewrites {
 		dnsRewrite := rewrite.DNSRewrite
 		if matchesQType(dnsRewrite, qtyp) {
@@ -224,16 +231,16 @@ func (s *DefaultStorage) resetRules() (err error) {
 
 // matchesQType returns true if dnsrewrite matches the question type qt.
 func matchesQType(dnsrr *rules.DNSRewrite, qt uint16) (ok bool) {
-	// Add CNAMEs, since they match for all types requests.
-	if dnsrr.RRType == dns.TypeCNAME || dnsrr.NewCNAME != "" {
-		return true
-	}
-
 	// Reject types other than A and AAAA.
 	if qt != dns.TypeA && qt != dns.TypeAAAA {
 		return false
 	}
 
+	// Add CNAMEs, since they match for all types requests.
+	if dnsrr.RRType == dns.TypeCNAME || dnsrr.NewCNAME != "" {
+		return true
+	}
+
 	return dnsrr.RRType == qt
 }
 

internal/filtering/rewrite/storage_test.go

@@ -123,6 +123,11 @@ func TestDefaultStorage_MatchRequest(t *testing.T) {
 		name: "rewritten_a",
 		host: "www.host.com",
 		wantDNSRewrites: []*rules.DNSRewrite{{
+			Value:    nil,
+			NewCNAME: "host.com",
+			RCode:    dns.RcodeSuccess,
+			RRType:   dns.TypeNone,
+		}, {
 			Value:    net.IP{1, 2, 3, 4}.To16(),
 			NewCNAME: "",
 			RCode:    dns.RcodeSuccess,
@@ -138,6 +143,11 @@ func TestDefaultStorage_MatchRequest(t *testing.T) {
 		name: "rewritten_aaaa",
 		host: "www.host.com",
 		wantDNSRewrites: []*rules.DNSRewrite{{
+			Value:    nil,
+			NewCNAME: "host.com",
+			RCode:    dns.RcodeSuccess,
+			RRType:   dns.TypeNone,
+		}, {
 			Value:    net.ParseIP("1:2:3::4"),
 			NewCNAME: "",
 			RCode:    dns.RcodeSuccess,
@@ -169,6 +179,11 @@ func TestDefaultStorage_MatchRequest(t *testing.T) {
 		name: "wildcard_cname_interaction",
 		host: "www.host2.com",
 		wantDNSRewrites: []*rules.DNSRewrite{{
+			Value:    nil,
+			NewCNAME: "host.com",
+			RCode:    dns.RcodeSuccess,
+			RRType:   dns.TypeNone,
+		}, {
 			Value:    net.IP{1, 2, 3, 4}.To16(),
 			NewCNAME: "",
 			RCode:    dns.RcodeSuccess,
@@ -184,6 +199,11 @@ func TestDefaultStorage_MatchRequest(t *testing.T) {
 		name: "two_cnames",
 		host: "b.host.com",
 		wantDNSRewrites: []*rules.DNSRewrite{{
+			Value:    nil,
+			NewCNAME: "somehost.com",
+			RCode:    dns.RcodeSuccess,
+			RRType:   dns.TypeNone,
+		}, {
 			Value:    net.IP{0, 0, 0, 0}.To16(),
 			NewCNAME: "",
 			RCode:    dns.RcodeSuccess,
@@ -194,6 +214,11 @@ func TestDefaultStorage_MatchRequest(t *testing.T) {
 		name: "two_cnames_and_wildcard",
 		host: "b.host3.com",
 		wantDNSRewrites: []*rules.DNSRewrite{{
+			Value:    nil,
+			NewCNAME: "x.host.com",
+			RCode:    dns.RcodeSuccess,
+			RRType:   dns.TypeNone,
+		}, {
 			Value:    net.IP{1, 2, 3, 5}.To16(),
 			NewCNAME: "",
 			RCode:    dns.RcodeSuccess,