1 // Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
2
3 package org.xbill.DNS;
4
5 /**
6 * Constants and functions relating to flags in the DNS header.
7 *
8 * @author Brian Wellington
9 */
10
11 public final class Flags {
12
13 private static Mnemonic flags = new Mnemonic("DNS Header Flag",
14 Mnemonic.CASE_LOWER);
15
16 /** query/response */
17 public static final byte QR = 0;
18
19 /** authoritative answer */
20 public static final byte AA = 5;
21
22 /** truncated */
23 public static final byte TC = 6;
24
25 /** recursion desired */
26 public static final byte RD = 7;
27
28 /** recursion available */
29 public static final byte RA = 8;
30
31 /** authenticated data */
32 public static final byte AD = 10;
33
34 /** (security) checking disabled */
35 public static final byte CD = 11;
36
37 /** dnssec ok (extended) */
38 public static final int DO = ExtendedFlags.DO;
39
40 static {
41 flags.setMaximum(0xF);
42 flags.setPrefix("FLAG");
43 flags.setNumericAllowed(true);
44
flags.add(QR, "qr")45 flags.add(QR, "qr");
flags.add(AA, "aa")46 flags.add(AA, "aa");
flags.add(TC, "tc")47 flags.add(TC, "tc");
flags.add(RD, "rd")48 flags.add(RD, "rd");
flags.add(RA, "ra")49 flags.add(RA, "ra");
flags.add(AD, "ad")50 flags.add(AD, "ad");
flags.add(CD, "cd")51 flags.add(CD, "cd");
52 }
53
54 private
Flags()55 Flags() {}
56
57 /** Converts a numeric Flag into a String */
58 public static String
string(int i)59 string(int i) {
60 return flags.getText(i);
61 }
62
63 /** Converts a String representation of an Flag into its numeric value */
64 public static int
value(String s)65 value(String s) {
66 return flags.getValue(s);
67 }
68
69 /**
70 * Indicates if a bit in the flags field is a flag or not. If it's part of
71 * the rcode or opcode, it's not.
72 */
73 public static boolean
isFlag(int index)74 isFlag(int index) {
75 flags.check(index);
76 if ((index >= 1 && index <= 4) || (index >= 12))
77 return false;
78 return true;
79 }
80
81 }
82