org.xbill.DNS
Class Message

java.lang.Object
  org.xbill.DNS.Message

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

Update

public class Message
extends Object
implements Cloneable

A DNS Message. A message is the basic unit of communication between the client and server of a DNS operation. A message consists of a Header and 4 message sections.

Author:

Brian Wellington

See Also:

Resolver, Header, Section

Field Summary

static int

MAXLENGTH The maximum length of a message in wire format.

Constructor Summary

Message()
Creates a new Message with a random Message ID

Message(byte[] b)
Creates a new Message from its DNS wire format representation

Message(int id)
Creates a new Message with the specified Message ID

Method Summary

void	addRecord(Record r, int section) Adds a record to a section of the Message, and adjusts the header.
Object	clone() Creates a copy of this Message.
boolean	findRecord(Record r) Determines if the given record is already present in any section.
boolean	findRecord(Record r, int section) Determines if the given record is already present in the given section.
boolean	findRRset(Name name, int type) Determines if an RRset with the given name and type is already present in any section.
boolean	findRRset(Name name, int type, int section) Determines if an RRset with the given name and type is already present in the given section.
Header	getHeader() Retrieves the Header.
OPTRecord	getOPT() Returns the OPT record from the ADDITIONAL section, if one is present.
Record	getQuestion() Returns the first record in the QUESTION section.
int	getRcode() Returns the message's rcode (error code).
Record[]	getSectionArray(int section) Returns an array containing all records in the given section, or an empty array if the section is empty.
RRset[]	getSectionRRsets(int section) Returns an array containing all records in the given section grouped into RRsets.
TSIGRecord	getTSIG() Returns the TSIG record from the ADDITIONAL section, if one is present.
boolean	isSigned() Was this message signed by a TSIG?
boolean	isVerified() If this message was signed by a TSIG, was the TSIG verified?
static Message	newQuery(Record r) Creates a new Message with a random Message ID suitable for sending as a query.
static Message	newUpdate(Name zone) Creates a new Message to contain a dynamic update.
int	numBytes() Returns the size of the message.
void	removeAllRecords(int section) Removes all records from a section of the Message, and adjusts the header.
boolean	removeRecord(Record r, int section) Removes a record from a section of the Message, and adjusts the header.
String	sectionToString(int i) Converts the given section of the Message to a String.
void	setHeader(Header h) Replaces the Header with a new one.
void	setTSIG(TSIG key, int error, TSIGRecord querytsig) Sets the TSIG key and other necessary information to sign a message.
String	toString() Converts the Message to a String.
byte[]	toWire() Returns an array containing the wire format representation of the Message.
byte[]	toWire(int maxLength) Returns an array containing the wire format representation of the Message with the specified maximum length.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

MAXLENGTH

public static final int MAXLENGTH

The maximum length of a message in wire format.

See Also:

Constant Field Values

Constructor Detail

Message

public Message(int id)

Creates a new Message with the specified Message ID

Message

public Message()

Creates a new Message with a random Message ID

Message

public Message(byte[] b)
        throws IOException

Creates a new Message from its DNS wire format representation

Parameters:

b - A byte array containing the DNS Message.

Throws:

IOException

Method Detail

newQuery

public static Message newQuery(Record r)

Creates a new Message with a random Message ID suitable for sending as a query.

Parameters:

r - A record containing the question

newUpdate

public static Message newUpdate(Name zone)

Creates a new Message to contain a dynamic update. A random Message ID and the zone are filled in.

Parameters:

zone - The zone to be updated

setHeader

public void setHeader(Header h)

Replaces the Header with a new one.

See Also:

Header

getHeader

public Header getHeader()

Retrieves the Header.

See Also:

Header

addRecord

public void addRecord(Record r,
                      int section)

Adds a record to a section of the Message, and adjusts the header.

See Also:

Record, Section

removeRecord

public boolean removeRecord(Record r,
                            int section)

Removes a record from a section of the Message, and adjusts the header.

See Also:

Record, Section

removeAllRecords

public void removeAllRecords(int section)

Removes all records from a section of the Message, and adjusts the header.

See Also:

Record, Section

findRecord

public boolean findRecord(Record r,
                          int section)

Determines if the given record is already present in the given section.

See Also:

Record, Section

findRecord

public boolean findRecord(Record r)

Determines if the given record is already present in any section.

See Also:

Record, Section

findRRset

public boolean findRRset(Name name,
                         int type,
                         int section)

Determines if an RRset with the given name and type is already present in the given section.

See Also:

RRset, Section

findRRset

public boolean findRRset(Name name,
                         int type)

Determines if an RRset with the given name and type is already present in any section.

See Also:

RRset, Section

getQuestion

public Record getQuestion()

Returns the first record in the QUESTION section.

See Also:

Record, Section

getTSIG

public TSIGRecord getTSIG()

Returns the TSIG record from the ADDITIONAL section, if one is present.

See Also:

TSIGRecord, TSIG, Section

isSigned

public boolean isSigned()

Was this message signed by a TSIG?

See Also:

TSIG

isVerified

public boolean isVerified()

If this message was signed by a TSIG, was the TSIG verified?

See Also:

TSIG

getOPT

public OPTRecord getOPT()

Returns the OPT record from the ADDITIONAL section, if one is present.

See Also:

OPTRecord, Section

getRcode

public int getRcode()

Returns the message's rcode (error code). This incorporates the EDNS extended rcode.

getSectionArray

public Record[] getSectionArray(int section)

Returns an array containing all records in the given section, or an empty array if the section is empty.

See Also:

Record, Section

getSectionRRsets

public RRset[] getSectionRRsets(int section)

Returns an array containing all records in the given section grouped into RRsets.

See Also:

RRset, Section

toWire

public byte[] toWire()

Returns an array containing the wire format representation of the Message.

toWire

public byte[] toWire(int maxLength)

Returns an array containing the wire format representation of the Message with the specified maximum length. This will generate a truncated message (with the TC bit) if the message doesn't fit, and will also sign the message with the TSIG key set by a call to setTSIG(). This method may return null if the message could not be rendered at all; this could happen if maxLength is smaller than a DNS header, for example.

Parameters:

maxLength - The maximum length of the message.

Returns:

The wire format of the message, or null if the message could not be rendered into the specified length.

See Also:

Flags, TSIG

setTSIG

public void setTSIG(TSIG key,
                    int error,
                    TSIGRecord querytsig)

Sets the TSIG key and other necessary information to sign a message.

Parameters:

key - The TSIG key.

error - The value of the TSIG error field.

querytsig - If this is a response, the TSIG from the request.

numBytes

public int numBytes()

Returns the size of the message. Only valid if the message has been converted to or from wire format.

sectionToString

public String sectionToString(int i)

Converts the given section of the Message to a String.

See Also:

Section

toString

public String toString()

Converts the Message to a String.

Overrides:

toString in class Object

clone

public Object clone()

Creates a copy of this Message. This is done by the Resolver before adding TSIG and OPT records, for example.

Overrides:

clone in class Object

See Also:

Resolver, TSIGRecord, OPTRecord