(No support for Auth-Name + Add-Name for simplicity)
This page hosts a formal specification of DNS (Domain Name Service) packet using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Java generated by Kaitai Struct depends on the Java runtime library. You have to install it before you can parse data.
The Java runtime library is published in the Maven Central Repository. Refer to the artifact page for instructions how to add it into your project with the build tool that you use.
Parse a local file and get structure in memory:
DnsPacket data = DnsPacket.fromFile("path/to/local/file.bin");
Or parse structure from a byte array:
byte[] someArray = new byte[] { ... };
DnsPacket data = new DnsPacket(new ByteBufferKaitaiStream(someArray));
After that, one can get various attributes from the structure by invoking getter methods like:
data.transactionId() // => ID to keep track of request/responces
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import io.kaitai.struct.ByteBufferKaitaiStream;
import io.kaitai.struct.KaitaiStruct;
import io.kaitai.struct.KaitaiStream;
import java.io.IOException;
import java.util.Map;
import java.util.HashMap;
import java.util.ArrayList;
import java.nio.charset.Charset;
/**
* (No support for Auth-Name + Add-Name for simplicity)
*/
public class DnsPacket extends KaitaiStruct {
public static DnsPacket fromFile(String fileName) throws IOException {
return new DnsPacket(new ByteBufferKaitaiStream(fileName));
}
public enum ClassType {
IN_CLASS(1),
CS(2),
CH(3),
HS(4);
private final long id;
ClassType(long id) { this.id = id; }
public long id() { return id; }
private static final Map<Long, ClassType> byId = new HashMap<Long, ClassType>(4);
static {
for (ClassType e : ClassType.values())
byId.put(e.id(), e);
}
public static ClassType byId(long id) { return byId.get(id); }
}
public enum TypeType {
A(1),
NS(2),
MD(3),
MF(4),
CNAME(5),
SOA(6),
MB(7),
MG(8),
MR(9),
NULL(10),
WKS(11),
PTR(12),
HINFO(13),
MINFO(14),
MX(15),
TXT(16),
AAAA(28),
SRV(33);
private final long id;
TypeType(long id) { this.id = id; }
public long id() { return id; }
private static final Map<Long, TypeType> byId = new HashMap<Long, TypeType>(18);
static {
for (TypeType e : TypeType.values())
byId.put(e.id(), e);
}
public static TypeType byId(long id) { return byId.get(id); }
}
public DnsPacket(KaitaiStream _io) {
this(_io, null, null);
}
public DnsPacket(KaitaiStream _io, KaitaiStruct _parent) {
this(_io, _parent, null);
}
public DnsPacket(KaitaiStream _io, KaitaiStruct _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root == null ? this : _root;
_read();
}
private void _read() {
this.transactionId = this._io.readU2be();
this.flags = new PacketFlags(this._io, this, _root);
if (flags().isOpcodeValid()) {
this.qdcount = this._io.readU2be();
}
if (flags().isOpcodeValid()) {
this.ancount = this._io.readU2be();
}
if (flags().isOpcodeValid()) {
this.nscount = this._io.readU2be();
}
if (flags().isOpcodeValid()) {
this.arcount = this._io.readU2be();
}
if (flags().isOpcodeValid()) {
this.queries = new ArrayList<Query>();
for (int i = 0; i < qdcount(); i++) {
this.queries.add(new Query(this._io, this, _root));
}
}
if (flags().isOpcodeValid()) {
this.answers = new ArrayList<Answer>();
for (int i = 0; i < ancount(); i++) {
this.answers.add(new Answer(this._io, this, _root));
}
}
if (flags().isOpcodeValid()) {
this.authorities = new ArrayList<Answer>();
for (int i = 0; i < nscount(); i++) {
this.authorities.add(new Answer(this._io, this, _root));
}
}
if (flags().isOpcodeValid()) {
this.additionals = new ArrayList<Answer>();
for (int i = 0; i < arcount(); i++) {
this.additionals.add(new Answer(this._io, this, _root));
}
}
}
public static class MxInfo extends KaitaiStruct {
public static MxInfo fromFile(String fileName) throws IOException {
return new MxInfo(new ByteBufferKaitaiStream(fileName));
}
public MxInfo(KaitaiStream _io) {
this(_io, null, null);
}
public MxInfo(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public MxInfo(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.preference = this._io.readU2be();
this.mx = new DomainName(this._io, this, _root);
}
private int preference;
private DomainName mx;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public int preference() { return preference; }
public DomainName mx() { return mx; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
public static class PointerStruct extends KaitaiStruct {
public static PointerStruct fromFile(String fileName) throws IOException {
return new PointerStruct(new ByteBufferKaitaiStream(fileName));
}
public PointerStruct(KaitaiStream _io) {
this(_io, null, null);
}
public PointerStruct(KaitaiStream _io, DnsPacket.Label _parent) {
this(_io, _parent, null);
}
public PointerStruct(KaitaiStream _io, DnsPacket.Label _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.value = this._io.readU1();
}
private DomainName contents;
public DomainName contents() {
if (this.contents != null)
return this.contents;
KaitaiStream io = _root()._io();
long _pos = io.pos();
io.seek((value() + ((_parent().length() - 192) << 8)));
this.contents = new DomainName(io, this, _root);
io.seek(_pos);
return this.contents;
}
private int value;
private DnsPacket _root;
private DnsPacket.Label _parent;
/**
* Read one byte, then offset to that position, read one domain-name and return
*/
public int value() { return value; }
public DnsPacket _root() { return _root; }
public DnsPacket.Label _parent() { return _parent; }
}
public static class Label extends KaitaiStruct {
public static Label fromFile(String fileName) throws IOException {
return new Label(new ByteBufferKaitaiStream(fileName));
}
public Label(KaitaiStream _io) {
this(_io, null, null);
}
public Label(KaitaiStream _io, DnsPacket.DomainName _parent) {
this(_io, _parent, null);
}
public Label(KaitaiStream _io, DnsPacket.DomainName _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.length = this._io.readU1();
if (isPointer()) {
this.pointer = new PointerStruct(this._io, this, _root);
}
if (!(isPointer())) {
this.name = new String(this._io.readBytes(length()), Charset.forName("utf-8"));
}
}
private Boolean isPointer;
public Boolean isPointer() {
if (this.isPointer != null)
return this.isPointer;
boolean _tmp = (boolean) (length() >= 192);
this.isPointer = _tmp;
return this.isPointer;
}
private int length;
private PointerStruct pointer;
private String name;
private DnsPacket _root;
private DnsPacket.DomainName _parent;
/**
* RFC1035 4.1.4: If the first two bits are raised it's a pointer-offset to a previously defined name
*/
public int length() { return length; }
public PointerStruct pointer() { return pointer; }
/**
* Otherwise its a string the length of the length value
*/
public String name() { return name; }
public DnsPacket _root() { return _root; }
public DnsPacket.DomainName _parent() { return _parent; }
}
public static class Query extends KaitaiStruct {
public static Query fromFile(String fileName) throws IOException {
return new Query(new ByteBufferKaitaiStream(fileName));
}
public Query(KaitaiStream _io) {
this(_io, null, null);
}
public Query(KaitaiStream _io, DnsPacket _parent) {
this(_io, _parent, null);
}
public Query(KaitaiStream _io, DnsPacket _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.name = new DomainName(this._io, this, _root);
this.type = DnsPacket.TypeType.byId(this._io.readU2be());
this.queryClass = DnsPacket.ClassType.byId(this._io.readU2be());
}
private DomainName name;
private TypeType type;
private ClassType queryClass;
private DnsPacket _root;
private DnsPacket _parent;
public DomainName name() { return name; }
public TypeType type() { return type; }
public ClassType queryClass() { return queryClass; }
public DnsPacket _root() { return _root; }
public DnsPacket _parent() { return _parent; }
}
public static class DomainName extends KaitaiStruct {
public static DomainName fromFile(String fileName) throws IOException {
return new DomainName(new ByteBufferKaitaiStream(fileName));
}
public DomainName(KaitaiStream _io) {
this(_io, null, null);
}
public DomainName(KaitaiStream _io, KaitaiStruct _parent) {
this(_io, _parent, null);
}
public DomainName(KaitaiStream _io, KaitaiStruct _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.name = new ArrayList<Label>();
{
Label _it;
int i = 0;
do {
_it = new Label(this._io, this, _root);
this.name.add(_it);
i++;
} while (!( ((_it.length() == 0) || (_it.length() >= 192)) ));
}
}
private ArrayList<Label> name;
private DnsPacket _root;
private KaitaiStruct _parent;
/**
* Repeat until the length is 0 or it is a pointer (bit-hack to get around lack of OR operator)
*/
public ArrayList<Label> name() { return name; }
public DnsPacket _root() { return _root; }
public KaitaiStruct _parent() { return _parent; }
}
public static class AddressV6 extends KaitaiStruct {
public static AddressV6 fromFile(String fileName) throws IOException {
return new AddressV6(new ByteBufferKaitaiStream(fileName));
}
public AddressV6(KaitaiStream _io) {
this(_io, null, null);
}
public AddressV6(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public AddressV6(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.ipV6 = this._io.readBytes(16);
}
private byte[] ipV6;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public byte[] ipV6() { return ipV6; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
public static class Service extends KaitaiStruct {
public static Service fromFile(String fileName) throws IOException {
return new Service(new ByteBufferKaitaiStream(fileName));
}
public Service(KaitaiStream _io) {
this(_io, null, null);
}
public Service(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public Service(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.priority = this._io.readU2be();
this.weight = this._io.readU2be();
this.port = this._io.readU2be();
this.target = new DomainName(this._io, this, _root);
}
private int priority;
private int weight;
private int port;
private DomainName target;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public int priority() { return priority; }
public int weight() { return weight; }
public int port() { return port; }
public DomainName target() { return target; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
public static class Txt extends KaitaiStruct {
public static Txt fromFile(String fileName) throws IOException {
return new Txt(new ByteBufferKaitaiStream(fileName));
}
public Txt(KaitaiStream _io) {
this(_io, null, null);
}
public Txt(KaitaiStream _io, DnsPacket.TxtBody _parent) {
this(_io, _parent, null);
}
public Txt(KaitaiStream _io, DnsPacket.TxtBody _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.length = this._io.readU1();
this.text = new String(this._io.readBytes(length()), Charset.forName("utf-8"));
}
private int length;
private String text;
private DnsPacket _root;
private DnsPacket.TxtBody _parent;
public int length() { return length; }
public String text() { return text; }
public DnsPacket _root() { return _root; }
public DnsPacket.TxtBody _parent() { return _parent; }
}
public static class TxtBody extends KaitaiStruct {
public static TxtBody fromFile(String fileName) throws IOException {
return new TxtBody(new ByteBufferKaitaiStream(fileName));
}
public TxtBody(KaitaiStream _io) {
this(_io, null, null);
}
public TxtBody(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public TxtBody(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.data = new ArrayList<Txt>();
{
int i = 0;
while (!this._io.isEof()) {
this.data.add(new Txt(this._io, this, _root));
i++;
}
}
}
private ArrayList<Txt> data;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public ArrayList<Txt> data() { return data; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
public static class Address extends KaitaiStruct {
public static Address fromFile(String fileName) throws IOException {
return new Address(new ByteBufferKaitaiStream(fileName));
}
public Address(KaitaiStream _io) {
this(_io, null, null);
}
public Address(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public Address(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.ip = this._io.readBytes(4);
}
private byte[] ip;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public byte[] ip() { return ip; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
public static class Answer extends KaitaiStruct {
public static Answer fromFile(String fileName) throws IOException {
return new Answer(new ByteBufferKaitaiStream(fileName));
}
public Answer(KaitaiStream _io) {
this(_io, null, null);
}
public Answer(KaitaiStream _io, DnsPacket _parent) {
this(_io, _parent, null);
}
public Answer(KaitaiStream _io, DnsPacket _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.name = new DomainName(this._io, this, _root);
this.type = DnsPacket.TypeType.byId(this._io.readU2be());
this.answerClass = DnsPacket.ClassType.byId(this._io.readU2be());
this.ttl = this._io.readS4be();
this.rdlength = this._io.readU2be();
{
TypeType on = type();
if (on != null) {
switch (type()) {
case SRV: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new Service(_io__raw_payload, this, _root);
break;
}
case A: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new Address(_io__raw_payload, this, _root);
break;
}
case CNAME: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new DomainName(_io__raw_payload, this, _root);
break;
}
case NS: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new DomainName(_io__raw_payload, this, _root);
break;
}
case SOA: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new AuthorityInfo(_io__raw_payload, this, _root);
break;
}
case MX: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new MxInfo(_io__raw_payload, this, _root);
break;
}
case TXT: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new TxtBody(_io__raw_payload, this, _root);
break;
}
case PTR: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new DomainName(_io__raw_payload, this, _root);
break;
}
case AAAA: {
this._raw_payload = this._io.readBytes(rdlength());
KaitaiStream _io__raw_payload = new ByteBufferKaitaiStream(_raw_payload);
this.payload = new AddressV6(_io__raw_payload, this, _root);
break;
}
default: {
this.payload = this._io.readBytes(rdlength());
break;
}
}
} else {
this.payload = this._io.readBytes(rdlength());
}
}
}
private DomainName name;
private TypeType type;
private ClassType answerClass;
private int ttl;
private int rdlength;
private Object payload;
private DnsPacket _root;
private DnsPacket _parent;
private byte[] _raw_payload;
public DomainName name() { return name; }
public TypeType type() { return type; }
public ClassType answerClass() { return answerClass; }
/**
* Time to live (in seconds)
*/
public int ttl() { return ttl; }
/**
* Length in octets of the following payload
*/
public int rdlength() { return rdlength; }
public Object payload() { return payload; }
public DnsPacket _root() { return _root; }
public DnsPacket _parent() { return _parent; }
public byte[] _raw_payload() { return _raw_payload; }
}
public static class PacketFlags extends KaitaiStruct {
public static PacketFlags fromFile(String fileName) throws IOException {
return new PacketFlags(new ByteBufferKaitaiStream(fileName));
}
public PacketFlags(KaitaiStream _io) {
this(_io, null, null);
}
public PacketFlags(KaitaiStream _io, DnsPacket _parent) {
this(_io, _parent, null);
}
public PacketFlags(KaitaiStream _io, DnsPacket _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.flag = this._io.readU2be();
}
private Integer qr;
public Integer qr() {
if (this.qr != null)
return this.qr;
int _tmp = (int) (((flag() & 32768) >> 15));
this.qr = _tmp;
return this.qr;
}
private Integer ra;
public Integer ra() {
if (this.ra != null)
return this.ra;
int _tmp = (int) (((flag() & 128) >> 7));
this.ra = _tmp;
return this.ra;
}
private Integer tc;
public Integer tc() {
if (this.tc != null)
return this.tc;
int _tmp = (int) (((flag() & 512) >> 9));
this.tc = _tmp;
return this.tc;
}
private Boolean isOpcodeValid;
public Boolean isOpcodeValid() {
if (this.isOpcodeValid != null)
return this.isOpcodeValid;
boolean _tmp = (boolean) ( ((opcode() == 0) || (opcode() == 1) || (opcode() == 2)) );
this.isOpcodeValid = _tmp;
return this.isOpcodeValid;
}
private Integer rcode;
public Integer rcode() {
if (this.rcode != null)
return this.rcode;
int _tmp = (int) (((flag() & 15) >> 0));
this.rcode = _tmp;
return this.rcode;
}
private Integer opcode;
public Integer opcode() {
if (this.opcode != null)
return this.opcode;
int _tmp = (int) (((flag() & 30720) >> 11));
this.opcode = _tmp;
return this.opcode;
}
private Integer aa;
public Integer aa() {
if (this.aa != null)
return this.aa;
int _tmp = (int) (((flag() & 1024) >> 10));
this.aa = _tmp;
return this.aa;
}
private Integer z;
public Integer z() {
if (this.z != null)
return this.z;
int _tmp = (int) (((flag() & 64) >> 6));
this.z = _tmp;
return this.z;
}
private Integer rd;
public Integer rd() {
if (this.rd != null)
return this.rd;
int _tmp = (int) (((flag() & 256) >> 8));
this.rd = _tmp;
return this.rd;
}
private Integer cd;
public Integer cd() {
if (this.cd != null)
return this.cd;
int _tmp = (int) (((flag() & 16) >> 4));
this.cd = _tmp;
return this.cd;
}
private Integer ad;
public Integer ad() {
if (this.ad != null)
return this.ad;
int _tmp = (int) (((flag() & 32) >> 5));
this.ad = _tmp;
return this.ad;
}
private int flag;
private DnsPacket _root;
private DnsPacket _parent;
public int flag() { return flag; }
public DnsPacket _root() { return _root; }
public DnsPacket _parent() { return _parent; }
}
public static class AuthorityInfo extends KaitaiStruct {
public static AuthorityInfo fromFile(String fileName) throws IOException {
return new AuthorityInfo(new ByteBufferKaitaiStream(fileName));
}
public AuthorityInfo(KaitaiStream _io) {
this(_io, null, null);
}
public AuthorityInfo(KaitaiStream _io, DnsPacket.Answer _parent) {
this(_io, _parent, null);
}
public AuthorityInfo(KaitaiStream _io, DnsPacket.Answer _parent, DnsPacket _root) {
super(_io);
this._parent = _parent;
this._root = _root;
_read();
}
private void _read() {
this.primaryNs = new DomainName(this._io, this, _root);
this.resoponsibleMailbox = new DomainName(this._io, this, _root);
this.serial = this._io.readU4be();
this.refreshInterval = this._io.readU4be();
this.retryInterval = this._io.readU4be();
this.expireLimit = this._io.readU4be();
this.minTtl = this._io.readU4be();
}
private DomainName primaryNs;
private DomainName resoponsibleMailbox;
private long serial;
private long refreshInterval;
private long retryInterval;
private long expireLimit;
private long minTtl;
private DnsPacket _root;
private DnsPacket.Answer _parent;
public DomainName primaryNs() { return primaryNs; }
public DomainName resoponsibleMailbox() { return resoponsibleMailbox; }
public long serial() { return serial; }
public long refreshInterval() { return refreshInterval; }
public long retryInterval() { return retryInterval; }
public long expireLimit() { return expireLimit; }
public long minTtl() { return minTtl; }
public DnsPacket _root() { return _root; }
public DnsPacket.Answer _parent() { return _parent; }
}
private int transactionId;
private PacketFlags flags;
private Integer qdcount;
private Integer ancount;
private Integer nscount;
private Integer arcount;
private ArrayList<Query> queries;
private ArrayList<Answer> answers;
private ArrayList<Answer> authorities;
private ArrayList<Answer> additionals;
private DnsPacket _root;
private KaitaiStruct _parent;
/**
* ID to keep track of request/responces
*/
public int transactionId() { return transactionId; }
public PacketFlags flags() { return flags; }
/**
* How many questions are there
*/
public Integer qdcount() { return qdcount; }
/**
* Number of resource records answering the question
*/
public Integer ancount() { return ancount; }
/**
* Number of resource records pointing toward an authority
*/
public Integer nscount() { return nscount; }
/**
* Number of resource records holding additional information
*/
public Integer arcount() { return arcount; }
public ArrayList<Query> queries() { return queries; }
public ArrayList<Answer> answers() { return answers; }
public ArrayList<Answer> authorities() { return authorities; }
public ArrayList<Answer> additionals() { return additionals; }
public DnsPacket _root() { return _root; }
public KaitaiStruct _parent() { return _parent; }
}