/*
* Copied from the DnsJava project
*
* Copyright (c) 1998-2011, Brian Wellington.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package io.milton.dns.record;
import java.io.*;
import java.util.*;
/**
* A DNS message header
* @see Message
*
* @author Brian Wellington
*/
public class Header implements Cloneable {
private int id;
private int flags;
private int [] counts;
private static Random random = new Random();
/** The length of a DNS Header in wire format. */
public static final int LENGTH = 12;
private void
init() {
counts = new int[4];
flags = 0;
id = -1;
}
/**
* Create a new empty header.
* @param id The message id
*/
public
Header(int id) {
init();
setID(id);
}
/**
* Create a new empty header with a random message id
*/
public
Header() {
init();
}
/**
* Parses a Header from a stream containing DNS wire format.
*/
Header(DNSInput in) throws IOException {
this(in.readU16());
flags = in.readU16();
for (int i = 0; i < counts.length; i++)
counts[i] = in.readU16();
}
/**
* Creates a new Header from its DNS wire format representation
* @param b A byte array containing the DNS Header.
*/
public
Header(byte [] b) throws IOException {
this(new DNSInput(b));
}
void
toWire(DNSOutput out) {
out.writeU16(getID());
out.writeU16(flags);
for (int i = 0; i < counts.length; i++)
out.writeU16(counts[i]);
}
public byte []
toWire() {
DNSOutput out = new DNSOutput();
toWire(out);
return out.toByteArray();
}
static private boolean
validFlag(int bit) {
return (bit >= 0 && bit <= 0xF && Flags.isFlag(bit));
}
static private void
checkFlag(int bit) {
if (!validFlag(bit))
throw new IllegalArgumentException("invalid flag bit " + bit);
}
/**
* Sets a flag to the supplied value
* @see Flags
*/
public void
setFlag(int bit) {
checkFlag(bit);
// bits are indexed from left to right
flags |= (1 << (15 - bit));
}
/**
* Sets a flag to the supplied value
* @see Flags
*/
public void
unsetFlag(int bit) {
checkFlag(bit);
// bits are indexed from left to right
flags &= ~(1 << (15 - bit));
}
/**
* Retrieves a flag
* @see Flags
*/
public boolean
getFlag(int bit) {
checkFlag(bit);
// bits are indexed from left to right
return (flags & (1 << (15 - bit))) != 0;
}
boolean []
getFlags() {
boolean [] array = new boolean[16];
for (int i = 0; i < array.length; i++)
if (validFlag(i))
array[i] = getFlag(i);
return array;
}
/**
* Retrieves the message ID
*/
public int
getID() {
if (id >= 0)
return id;
synchronized (this) {
if (id < 0)
id = random.nextInt(0xffff);
return id;
}
}
/**
* Sets the message ID
*/
public void
setID(int id) {
if (id < 0 || id > 0xffff)
throw new IllegalArgumentException("DNS message ID " + id +
" is out of range");
this.id = id;
}
/**
* Sets the message's rcode
* @see Rcode
*/
public void
setRcode(int value) {
if (value < 0 || value > 0xF)
throw new IllegalArgumentException("DNS Rcode " + value +
" is out of range");
flags &= ~0xF;
flags |= value;
}
/**
* Retrieves the mesasge's rcode
* @see Rcode
*/
public int
getRcode() {
return flags & 0xF;
}
/**
* Sets the message's opcode
* @see Opcode
*/
public void
setOpcode(int value) {
if (value < 0 || value > 0xF)
throw new IllegalArgumentException("DNS Opcode " + value +
"is out of range");
flags &= 0x87FF;
flags |= (value << 11);
}
/**
* Retrieves the mesasge's opcode
* @see Opcode
*/
public int
getOpcode() {
return (flags >> 11) & 0xF;
}
void
setCount(int field, int value) {
if (value < 0 || value > 0xFFFF)
throw new IllegalArgumentException("DNS section count " +
value + " is out of range");
counts[field] = value;
}
public void
incCount(int field) {
if (counts[field] == 0xFFFF)
throw new IllegalStateException("DNS section count cannot " +
"be incremented");
counts[field]++;
}
public void
decCount(int field) {
if (counts[field] == 0)
throw new IllegalStateException("DNS section count cannot " +
"be decremented");
counts[field]--;
}
/**
* Retrieves the record count for the given section
* @see Section
*/
public int
getCount(int field) {
return counts[field];
}
/** Converts the header's flags into a String */
public String
printFlags() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 16; i++)
if (validFlag(i) && getFlag(i)) {
sb.append(Flags.string(i));
sb.append(" ");
}
return sb.toString();
}
String
toStringWithRcode(int newrcode) {
StringBuilder sb = new StringBuilder();
sb.append(";; ->>HEADER<<- ");
sb.append("opcode: ").append(Opcode.string(getOpcode()));
sb.append(", status: ").append(Rcode.string(newrcode));
sb.append(", id: ").append(getID());
sb.append("\n");
sb.append(";; flags: ").append(printFlags());
sb.append("; ");
for (int i = 0; i < 4; i++)
sb.append(Section.string(i)).append(": ").append(getCount(i)).append(" ");
return sb.toString();
}
/** Converts the header into a String */
public String
toString() {
return toStringWithRcode(getRcode());
}
/* Creates a new Header identical to the current one */
public Object
clone() {
Header h = new Header();
h.id = id;
h.flags = flags;
System.arraycopy(counts, 0, h.counts, 0, counts.length);
return h;
}
}