Shuyi Chen | d7955ce | 2013-05-22 14:51:55 -0700 | [diff] [blame] | 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 | |
| 45 | flags.add(QR, "qr"); |
| 46 | flags.add(AA, "aa"); |
| 47 | flags.add(TC, "tc"); |
| 48 | flags.add(RD, "rd"); |
| 49 | flags.add(RA, "ra"); |
| 50 | flags.add(AD, "ad"); |
| 51 | flags.add(CD, "cd"); |
| 52 | } |
| 53 | |
| 54 | private |
| 55 | Flags() {} |
| 56 | |
| 57 | /** Converts a numeric Flag into a String */ |
| 58 | public static String |
| 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 |
| 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 |
| 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 | } |