Add native protocol service plugins

plugins/services/dns_test.go

@@ -0,0 +1,33 @@
+//go:build plugin_dns || !plugin_selective
+
+package services
+
+import (
+	"encoding/binary"
+	"strings"
+	"testing"
+)
+
+func TestDNSQueryAndResponse(t *testing.T) {
+	const id uint16 = 0x1234
+	query := buildDNSRootNSQuery(id)
+	if len(query) != 17 {
+		t.Fatalf("unexpected dns query length: %d", len(query))
+	}
+	if binary.BigEndian.Uint16(query[0:2]) != id || binary.BigEndian.Uint16(query[13:15]) != 2 {
+		t.Fatalf("unexpected dns query: %#v", query)
+	}
+
+	resp := make([]byte, 12)
+	binary.BigEndian.PutUint16(resp[0:2], id)
+	binary.BigEndian.PutUint16(resp[2:4], 0x8180)
+	binary.BigEndian.PutUint16(resp[4:6], 1)
+	binary.BigEndian.PutUint16(resp[6:8], 2)
+	binary.BigEndian.PutUint16(resp[8:10], 3)
+	binary.BigEndian.PutUint16(resp[10:12], 4)
+
+	banner, ok := parseDNSResponse(resp, id)
+	if !ok || !strings.Contains(banner, "rcode=0") || !strings.Contains(banner, "an=2") {
+		t.Fatalf("unexpected dns banner: %q ok=%v", banner, ok)
+	}
+}