filtering: wildcard interference

internal/filtering/dnsrewrite.go

@@ -3,6 +3,7 @@ package filtering
 import (
 	"github.com/AdguardTeam/urlfilter/rules"
 	"github.com/miekg/dns"
+	"golang.org/x/exp/slices"
 )
 
 // DNSRewriteResult is the result of application of $dnsrewrite rules.
@@ -24,7 +25,13 @@ func (d *DNSFilter) processDNSRewrites(dnsr []*rules.NetworkRule) (res Result) {
 		Response: DNSRewriteResultResponse{},
 	}
 
+	slices.SortFunc(dnsr, rewriteSortsBefore)
+
 	for _, nr := range dnsr {
+		if containsWildcard(nr) {
+			break
+		}
+
 		dr := nr.DNSRewrite
 		if dr.NewCNAME != "" {
 			// NewCNAME rules have a higher priority than other rules.
@@ -73,3 +80,19 @@ func (d *DNSFilter) processDNSRewrites(dnsr []*rules.NetworkRule) (res Result) {
 		Reason:           RewrittenRule,
 	}
 }
+
+func rewriteSortsBefore(a, b *rules.NetworkRule) (sortsBefore bool) {
+	return len(a.Shortcut) > len(b.Shortcut)
+}
+
+func containsWildcard(r *rules.NetworkRule) (ok bool) {
+	for _, c := range r.RuleText {
+		if c == '*' {
+			return true
+		} else if c == '^' {
+			break
+		}
+	}
+
+	return false
+}

internal/filtering/dnsrewrite_test.go

@@ -5,6 +5,7 @@ import (
 	"path"
 	"testing"
 
+	"github.com/AdguardTeam/urlfilter"
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -202,3 +203,32 @@ func TestDNSFilter_CheckHostRules_dnsrewrite(t *testing.T) {
 		assert.Equal(t, "new-ptr-with-dot.", ptr)
 	})
 }
+
+func TestDNSFilter_processDNSRewrites(t *testing.T) {
+	const text = `
+|www.example.com^$dnsrewrite=127.0.0.1
+|*.example.com^$dnsrewrite=127.0.0.2
+`
+
+	host := "www.example.com"
+	rrtype := dns.TypeA
+
+	f, _ := newForTest(t, nil, []Filter{{ID: 0, Data: []byte(text)}})
+	setts := &Settings{
+		FilteringEnabled: true,
+	}
+
+	ufReq := &urlfilter.DNSRequest{
+		Hostname:         host,
+		SortedClientTags: setts.ClientTags,
+		ClientIP:         setts.ClientIP.String(),
+		ClientName:       setts.ClientName,
+		DNSType:          rrtype,
+	}
+
+	dres, matched := f.filteringEngine.MatchRequest(ufReq)
+	require.False(t, matched)
+
+	res := f.processDNSResultRewrites(dres, host)
+	assert.Len(t, res.Rules, 1)
+}