org.apache.commons.net.tftp

Class TFTPPacket

java.lang.Object

org.apache.commons.net.tftp.TFTPPacket

Direct Known Subclasses:

TFTPAckPacket, TFTPDataPacket, TFTPErrorPacket, TFTPRequestPacket

public abstract class TFTPPacket
extends Object

TFTPPacket is an abstract class encapsulating the functionality common to the 5 types of TFTP packets. It also provides a static factory method that will create the correct TFTP packet instance from a datagram. This relieves the programmer from having to figure out what kind of TFTP packet is contained in a datagram and create it himself.

Details regarding the TFTP protocol and the format of TFTP packets can be found in RFC 783. But the point of these classes is to keep you from having to worry about the internals. Additionally, only very few people should have to care about any of the TFTPPacket classes or derived classes. Almost all users should only be concerned with the TFTPClient class receiveFile() and sendFile() methods.

See Also:

TFTPPacketException, TFTP

Field Summary

Fields

Modifier and Type	Field and Description
static int	ACKNOWLEDGEMENT This is the actual TFTP spec identifier and is equal to 4.
(package private) InetAddress	address The host the packet is going to be sent or where it came from.
static int	DATA This is the actual TFTP spec identifier and is equal to 3.
static int	ERROR This is the actual TFTP spec identifier and is equal to 5.
(package private) static int	MIN_PACKET_SIZE The minimum size of a packet.
static int	OACK TFTP spec identifier 6.
(package private) int	port The port the packet came from or is going to.
static int	READ_REQUEST This is the actual TFTP spec identifier and is equal to 1.
static int	SEGMENT_SIZE The TFTP data packet maximum segment size in bytes.
(package private) int	type The type of packet.
static int	WRITE_REQUEST This is the actual TFTP spec identifier and is equal to 2.

Constructor Summary

Constructors

Constructor and Description
TFTPPacket(int type, InetAddress address, int port) This constructor is not visible outside the package.

Method Summary

Modifier and Type	Method and Description
InetAddress	getAddress() Gets the address of the host where the packet is going to be sent or where it came from.
int	getPort() Gets the port where the packet is going to be sent or where it came from.
int	getType() Gets the type of the packet.
abstract DatagramPacket	newDatagram() Creates a UDP datagram containing all the TFTP packet data in the proper format.
(package private) abstract DatagramPacket	newDatagram(DatagramPacket datagram, byte[] data) This is an abstract method only available within the package for implementing efficient datagram transport by eliminating buffering.
static TFTPPacket	newTFTPPacket(DatagramPacket datagram) When you receive a datagram that you expect to be a TFTP packet, you use this factory method to create the proper TFTPPacket object encapsulating the data contained in that datagram.
void	setAddress(InetAddress address) Sets the host address where the packet is going to be sent.
void	setPort(int port) Sets the port where the packet is going to be sent.
String	toString() For debugging

Methods inherited from class java.lang.Object

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

Field Detail

ACKNOWLEDGEMENT

public static final int ACKNOWLEDGEMENT

This is the actual TFTP spec identifier and is equal to 4. Identifier returned by getType() indicating an acknowledgement packet.

See Also:

Constant Field Values

address

InetAddress address

The host the packet is going to be sent or where it came from.

DATA

public static final int DATA

This is the actual TFTP spec identifier and is equal to 3. Identifier returned by getType() indicating a data packet.

See Also:

Constant Field Values

ERROR

public static final int ERROR

This is the actual TFTP spec identifier and is equal to 5. Identifier returned by getType() indicating an error packet.

See Also:

Constant Field Values

MIN_PACKET_SIZE

static final int MIN_PACKET_SIZE

The minimum size of a packet. This is 4 bytes. It is enough to store the opcode and blocknumber or other required data depending on the packet type.

See Also:

Constant Field Values

OACK

public static final int OACK

TFTP spec identifier 6. Identifier returned by getType() indicating an options acknowledgement packet.

See Also:

Constant Field Values

port

int port

The port the packet came from or is going to.

READ_REQUEST

public static final int READ_REQUEST

This is the actual TFTP spec identifier and is equal to 1. Identifier returned by getType() indicating a read request packet.

See Also:

Constant Field Values

SEGMENT_SIZE

public static final int SEGMENT_SIZE

The TFTP data packet maximum segment size in bytes. This is 512 and is useful for those familiar with the TFTP protocol who want to use the TFTP class methods to implement their own TFTP servers or clients.

See Also:

Constant Field Values

type

int type

The type of packet.

WRITE_REQUEST

public static final int WRITE_REQUEST

This is the actual TFTP spec identifier and is equal to 2. Identifier returned by getType() indicating a write request packet.

See Also:

Constant Field Values

Constructor Detail

TFTPPacket

TFTPPacket(int type,
           InetAddress address,
           int port)

This constructor is not visible outside the package. It is used by subclasses within the package to initialize base data.

Parameters:

type - The type of the packet.

address - The host the packet came from or is going to be sent.

port - The port the packet came from or is going to be sent.

Method Detail

getAddress

public final InetAddress getAddress()

Gets the address of the host where the packet is going to be sent or where it came from.

Returns:

The type of the packet.

getPort

public final int getPort()

Gets the port where the packet is going to be sent or where it came from.

Returns:

The port where the packet came from or where it is going.

getType

public final int getType()

Gets the type of the packet.

Returns:

The type of the packet.

newDatagram

public abstract DatagramPacket newDatagram()

Creates a UDP datagram containing all the TFTP packet data in the proper format. This is an abstract method, exposed to the programmer in case he wants to implement his own TFTP client instead of using the TFTPClient class. Under normal circumstances, you should not have a need to call this method.

Returns:

A UDP datagram containing the TFTP packet.

newDatagram

abstract DatagramPacket newDatagram(DatagramPacket datagram,
                                    byte[] data)

This is an abstract method only available within the package for implementing efficient datagram transport by eliminating buffering. It takes a datagram as an argument, and a byte buffer in which to store the raw datagram data. Inside the method, the data should be set as the datagram's data and the datagram returned.

Parameters:

datagram - The datagram to create.

data - The buffer to store the packet and to use in the datagram.

Returns:

The datagram argument.

newTFTPPacket

public static final TFTPPacket newTFTPPacket(DatagramPacket datagram)
                                      throws TFTPPacketException

When you receive a datagram that you expect to be a TFTP packet, you use this factory method to create the proper TFTPPacket object encapsulating the data contained in that datagram. This method is the only way you can instantiate a TFTPPacket derived class from a datagram.

Parameters:

datagram - The datagram containing a TFTP packet.

Returns:

The TFTPPacket object corresponding to the datagram.

Throws:

TFTPPacketException - If the datagram does not contain a valid TFTP packet.

setAddress

public final void setAddress(InetAddress address)

Sets the host address where the packet is going to be sent.

Parameters:

address - the address to set

setPort

public final void setPort(int port)

Sets the port where the packet is going to be sent.

Parameters:

port - the port to set

toString

public String toString()

For debugging

Overrides:

toString in class Object