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// Copyright (c) 1999-2004 Brian Wellington ([email protected])
package org.xbill.DNS;
/**
* Constants and functions relating to flags in the DNS header.
*
* @author Brian Wellington
*/
public final class Flags {
private static Mnemonic flags = new Mnemonic("DNS Header Flag",
Mnemonic.CASE_LOWER);
/** query/response */
public static final byte QR = 0;
/** authoritative answer */
public static final byte AA = 5;
/** truncated */
public static final byte TC = 6;
/** recursion desired */
public static final byte RD = 7;
/** recursion available */
public static final byte RA = 8;
/** authenticated data */
public static final byte AD = 10;
/** (security) checking disabled */
public static final byte CD = 11;
/** dnssec ok (extended) */
public static final int DO = ExtendedFlags.DO;
static {
flags.setMaximum(0xF);
flags.setPrefix("FLAG");
flags.setNumericAllowed(true);
flags.add(QR, "qr");
flags.add(AA, "aa");
flags.add(TC, "tc");
flags.add(RD, "rd");
flags.add(RA, "ra");
flags.add(AD, "ad");
flags.add(CD, "cd");
}
private
Flags() {}
/** Converts a numeric Flag into a String */
public static String
string(int i) {
return flags.getText(i);
}
/** Converts a String representation of an Flag into its numeric value */
public static int
value(String s) {
return flags.getValue(s);
}
/**
* Indicates if a bit in the flags field is a flag or not. If it's part of
* the rcode or opcode, it's not.
*/
public static boolean
isFlag(int index) {
flags.check(index);
if ((index >= 1 && index <= 4) || (index >= 12))
return false;
return true;
}
}