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The official Couchbase JVM Core IO Library
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 1999-2004 Brian Wellington ([email protected])
package com.couchbase.client.core.deps.org.xbill.DNS;
import java.io.IOException;
import java.security.SecureRandom;
import java.util.Random;
import lombok.SneakyThrows;
/**
* 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 final Random random = new SecureRandom();
/** The length of a DNS Header in wire format. */
public static final int LENGTH = 12;
/**
* Create a new empty header.
*
* @param id The message id
*/
public Header(int id) {
if (id < 0 || id > 0xffff) {
throw new IllegalArgumentException("DNS message ID " + id + " is out of range");
}
counts = new int[4];
flags = 0;
this.id = id;
}
/** Create a new empty header with a random message id */
public Header() {
this(random.nextInt(0xffff));
}
/** 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 count : counts) {
out.writeU16(count);
}
}
public byte[] toWire() {
DNSOutput out = new DNSOutput();
toWire(out);
return out.toByteArray();
}
private static boolean validFlag(int bit) {
return bit >= 0 && bit <= 0xF && Flags.isFlag(bit);
}
private static void checkFlag(int bit) {
if (!validFlag(bit)) {
throw new IllegalArgumentException("invalid flag bit " + bit);
}
}
static int setFlag(int flags, int bit, boolean value) {
checkFlag(bit);
// bits are indexed from left to right
if (value) {
return flags | (1 << (15 - bit));
} else {
return flags & ~(1 << (15 - bit));
}
}
/**
* Sets a flag to the supplied value
*
* @see Flags
*/
public void setFlag(int bit) {
checkFlag(bit);
flags = setFlag(flags, bit, true);
}
/**
* Sets a flag to the supplied value
*
* @see Flags
*/
public void unsetFlag(int bit) {
checkFlag(bit);
flags = setFlag(flags, bit, false);
}
/**
* 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() {
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;
}
void incCount(int field) {
if (counts[field] == 0xFFFF) {
throw new IllegalStateException("DNS section count cannot be incremented");
}
counts[field]++;
}
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];
}
int getFlagsByte() {
return flags;
}
/** Converts the header's flags into a String */
public String printFlags() {
StringBuilder sb = new StringBuilder();
printFlags(sb);
return sb.toString();
}
private void printFlags(StringBuilder sb) {
for (int i = 0; i < 16; i++) {
if (validFlag(i) && getFlag(i)) {
sb.append(Flags.string(i));
sb.append(" ");
}
}
}
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: ");
printFlags(sb);
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 */
@Override
public String toString() {
return toStringWithRcode(getRcode());
}
/* Creates a new Header identical to the current one */
@Override
@SneakyThrows(CloneNotSupportedException.class)
public Header clone() {
Header h = (Header) super.clone();
h.id = id;
h.flags = flags;
h.counts = new int[h.counts.length];
System.arraycopy(counts, 0, h.counts, 0, counts.length);
return h;
}
}