Package org.minidns.dnsmessage

Class DnsMessage

java.lang.Object

org.minidns.dnsmessage.DnsMessage

public class DnsMessage
extends Object

A DNS message as defined by RFC 1035. The message consists of a header and 4 sections: question, answer, nameserver and addition resource record section. A message can either be parsed (DnsMessage(byte[])) or serialized (toArray()).

See Also:

• RFC 1035

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	DnsMessage.Builder
static enum	DnsMessage.OPCODE	Symbolic DNS Opcode values.
static enum	DnsMessage.RESPONSE_CODE	Possible DNS response codes.

Field Summary

Fields

Modifier and Type	Field	Description
final List<Record<? extends Data>>	additionalSection	The additional section.
final List<Record<? extends Data>>	answerSection	The answers section records.
final boolean	authenticData	True if the server regarded the response as authentic.
final boolean	authoritativeAnswer	True if this is a authorative response.
final List<Record<? extends Data>>	authoritySection	The Authority Section.
final boolean	checkingDisabled	True if the server should not perform DNSSEC validation before returning the result.
final int	id	The DNS message id.
final DnsMessage.OPCODE	opcode	The DNS message opcode.
final int	optRrPosition
final boolean	qr	The QR flag of the DNS message header.
final List<Question>	questions	The question section content.
final long	receiveTimestamp	The receive timestamp.
final boolean	recursionAvailable	True if recursion is possible.
final boolean	recursionDesired	True if the server should recurse.
final DnsMessage.RESPONSE_CODE	responseCode	The response code of this dns message.
final boolean	truncated	True if message is truncated.

Constructor Summary

Constructors

Modifier	Constructor	Description
	DnsMessage(byte[] data)	Build a DNS Message based on a binary DNS message.
protected	DnsMessage(DnsMessage.Builder builder)

Method Summary

Modifier and Type	Method	Description
DnsMessage.Builder	asBuilder()
DatagramPacket	asDatagram(InetAddress address, int port)
DnsMessage	asNormalizedVersion()
String	asTerminalOutput()	Format the DnsMessage object in a way suitable for terminal output.
static DnsMessage.Builder	builder()
List<Record<? extends Data>>	copyAnswers()	Copy the records found in the answer section into a new list.
List<Record<? extends Data>>	copyAuthority()	Copy the records found in the authority section into a new list.
List<Question>	copyQuestions()	Copy the questions found in the question section.
boolean	equals(Object other)
<D extends Data> List<Record<D>>	filterAdditionalSectionBy(Class<D> type)
<D extends Data> List<Record<D>>	filterAnswerSectionBy(Class<D> type)
<D extends Data> List<Record<D>>	filterAuthoritySectionBy(Class<D> type)
<D extends Data> Set<D>	getAnswersFor(Question q)
long	getAnswersMinTtl()	Get the minimum TTL from all answers in seconds.
Edns	getEdns()
<D extends Data> Record<D>	getFirstOfTypeFromAdditionalSection(Class<D> type)
<D extends Data> Record<D>	getFirstOfTypeFromAnswerSection(Class<D> type)
<D extends Data> Record<D>	getFirstOfTypeFromAuthoritySection(Class<D> type)
ByteBuffer	getInByteBuffer()
Record<OPT>	getOptPseudoRecord()
Question	getQuestion()
DnsMessage.Builder	getResponseBuilder(DnsMessage.RESPONSE_CODE responseCode)
int	hashCode()
boolean	isDnssecOk()	Check if the EDNS DO (DNSSEC OK) flag is set.
byte[]	toArray()	Generate a binary dns packet out of this message.
String	toString()
void	writeTo(OutputStream outputStream)
void	writeTo(OutputStream outputStream, boolean writeLength)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

id

public final int id

The DNS message id.

opcode

public final DnsMessage.OPCODE opcode

The DNS message opcode.

responseCode

public final DnsMessage.RESPONSE_CODE responseCode

The response code of this dns message.

qr

public final boolean qr

The QR flag of the DNS message header. Note that this will be true if the message is a response and false if it is a query.

See Also:

• RFC 1035 § 4.1.1

authoritativeAnswer

public final boolean authoritativeAnswer

True if this is a authorative response. If set, the responding nameserver is an authority for the domain name in the question section. Note that the answer section may have multiple owner names because of aliases. This flag corresponds to the name which matches the query name, or the first owner name in the query section.

See Also:

• RFC 1035 § 4.1.1. Header section format

truncated

public final boolean truncated

True if message is truncated. Then TCP should be used.

recursionDesired

public final boolean recursionDesired

True if the server should recurse.

recursionAvailable

public final boolean recursionAvailable

True if recursion is possible.

authenticData

public final boolean authenticData

True if the server regarded the response as authentic.

checkingDisabled

public final boolean checkingDisabled

True if the server should not perform DNSSEC validation before returning the result.

questions

public final List<Question> questions

The question section content. Usually there will be only one question.

This list is unmodifiable.

answerSection

public final List<Record<? extends Data>> answerSection

The answers section records. Note that it is not guaranteed that all records found in this section will be direct answers to the question in the query. If DNSSEC is used, then this section also contains the RRSIG record.

This list is unmodifiable.

authoritySection

public final List<Record<? extends Data>> authoritySection

The Authority Section. Note that it is not guaranteed that this section only contains nameserver records. If DNSSEC is used, then this section could also contain a NSEC(3) record.

This list is unmodifiable.

additionalSection

public final List<Record<? extends Data>> additionalSection

The additional section. It eventually contains RRs which relate to the query.

This list is unmodifiable.

optRrPosition

public final int optRrPosition

receiveTimestamp

public final long receiveTimestamp

The receive timestamp. Set only if this message was created via parse. This should be used to evaluate TTLs.

Constructor Details

DnsMessage

protected DnsMessage(DnsMessage.Builder builder)

DnsMessage

public DnsMessage(byte[] data)
           throws IOException

Build a DNS Message based on a binary DNS message.

Parameters:

data - The DNS message data.

Throws:

IOException - On read errors.

Method Details

toArray

public byte[] toArray()

Generate a binary dns packet out of this message.

Returns:

byte[] the binary representation.

asDatagram

public DatagramPacket asDatagram(InetAddress address,
 int port)

writeTo

public void writeTo(OutputStream outputStream)
             throws IOException

Throws:

IOException

writeTo

public void writeTo(OutputStream outputStream,
 boolean writeLength)
             throws IOException

Throws:

IOException

getInByteBuffer

public ByteBuffer getInByteBuffer()

getQuestion

public Question getQuestion()

copyQuestions

public List<Question> copyQuestions()

Copy the questions found in the question section.

Returns:

a copy of the question section questions.

See Also:

• questions

copyAnswers

public List<Record<? extends Data>> copyAnswers()

Copy the records found in the answer section into a new list.

Returns:

a copy of the answer section records.

See Also:

• answerSection

copyAuthority

public List<Record<? extends Data>> copyAuthority()

Copy the records found in the authority section into a new list.

Returns:

a copy of the authority section records.

See Also:

• authoritySection

getEdns

public Edns getEdns()

getOptPseudoRecord

public Record<OPT> getOptPseudoRecord()

isDnssecOk

public boolean isDnssecOk()

Check if the EDNS DO (DNSSEC OK) flag is set.

Returns:

true if the DO flag is set.

toString

public String toString()

Overrides:

toString in class Object

asTerminalOutput

public String asTerminalOutput()

Format the DnsMessage object in a way suitable for terminal output. The format is loosely based on the output provided by dig.

Returns:

This message as a String suitable for terminal output.

getAnswersFor

public <D extends Data> Set<D> getAnswersFor(Question q)

getAnswersMinTtl

public long getAnswersMinTtl()

Get the minimum TTL from all answers in seconds.

Returns:

the minimum TTL from all answers in seconds.

asBuilder

public DnsMessage.Builder asBuilder()

asNormalizedVersion

public DnsMessage asNormalizedVersion()

getResponseBuilder

public DnsMessage.Builder getResponseBuilder(DnsMessage.RESPONSE_CODE responseCode)

hashCode

public int hashCode()

Overrides:

hashCode in class Object

filterAnswerSectionBy

public <D extends Data> List<Record<D>> filterAnswerSectionBy(Class<D> type)

filterAuthoritySectionBy

public <D extends Data> List<Record<D>> filterAuthoritySectionBy(Class<D> type)

filterAdditionalSectionBy

public <D extends Data> List<Record<D>> filterAdditionalSectionBy(Class<D> type)

getFirstOfTypeFromAnswerSection

public <D extends Data> Record<D> getFirstOfTypeFromAnswerSection(Class<D> type)

getFirstOfTypeFromAuthoritySection

public <D extends Data> Record<D> getFirstOfTypeFromAuthoritySection(Class<D> type)

getFirstOfTypeFromAdditionalSection

public <D extends Data> Record<D> getFirstOfTypeFromAdditionalSection(Class<D> type)

equals

public boolean equals(Object other)

Overrides:

equals in class Object

builder

public static DnsMessage.Builder builder()