org.apache.commons.net.tftp

Class TFTP

public class TFTP extends DatagramSocketClient

The TFTP class exposes a set of methods to allow you to deal with the TFTP protocol directly, in case you want to write your own TFTP client or server. However, almost every user should only be concerend with the {@link org.apache.commons.net.DatagramSocketClient#open open() }, and {@link org.apache.commons.net.DatagramSocketClient#close close() }, methods. Additionally,the a {@link org.apache.commons.net.DatagramSocketClient#setDefaultTimeout setDefaultTimeout() } method may be of importance for performance tuning.

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.

Author: Daniel F. Savarese

See Also: DatagramSocketClient TFTPPacket TFTPPacketException

Field Summary
static intASCII_MODE
The ascii transfer mode.
static intBINARY_MODE
The binary transfer mode.
static intDEFAULT_PORT
The default TFTP port according to RFC 783 is 69.
static intDEFAULT_TIMEOUT
The default number of milliseconds to wait to receive a datagram before timing out.
static intIMAGE_MODE
The image transfer mode.
static intNETASCII_MODE
The netascii transfer mode.
static intOCTET_MODE
The octet transfer mode.
Constructor Summary
TFTP()
Creates a TFTP instance with a default timeout of DEFAULT_TIMEOUT, a null socket, and buffered operations disabled.
Method Summary
voidbeginBufferedOps()
Initializes the internal buffers.
TFTPPacketbufferedReceive()
This is a special method to perform a more efficient packet receive.
voidbufferedSend(TFTPPacket packet)
This is a special method to perform a more efficient packet send.
voiddiscardPackets()
This method synchronizes a connection by discarding all packets that may be in the local socket buffer.
voidendBufferedOps()
Releases the resources used to perform buffered sends and receives.
static StringgetModeName(int mode)
Returns the TFTP string representation of a TFTP transfer mode.
TFTPPacketreceive()
Receives a TFTPPacket.
voidsend(TFTPPacket packet)
Sends a TFTP packet to its destination.

Field Detail

ASCII_MODE

public static final int ASCII_MODE
The ascii transfer mode. Its value is 0 and equivalent to NETASCII_MODE

BINARY_MODE

public static final int BINARY_MODE
The binary transfer mode. Its value is 1 and equivalent to OCTET_MODE.

DEFAULT_PORT

public static final int DEFAULT_PORT
The default TFTP port according to RFC 783 is 69.

DEFAULT_TIMEOUT

public static final int DEFAULT_TIMEOUT
The default number of milliseconds to wait to receive a datagram before timing out. The default is 5000 milliseconds (5 seconds).

IMAGE_MODE

public static final int IMAGE_MODE
The image transfer mode. Its value is 1 and equivalent to OCTET_MODE.

NETASCII_MODE

public static final int NETASCII_MODE
The netascii transfer mode. Its value is 0.

OCTET_MODE

public static final int OCTET_MODE
The octet transfer mode. Its value is 1.

Constructor Detail

TFTP

public TFTP()
Creates a TFTP instance with a default timeout of DEFAULT_TIMEOUT, a null socket, and buffered operations disabled.

Method Detail

beginBufferedOps

public final void beginBufferedOps()
Initializes the internal buffers. Buffers are used by {@link #bufferedSend bufferedSend() } and {@link #bufferedReceive bufferedReceive() }. This method must be called before calling either one of those two methods. When you finish using buffered operations, you must call {@link #endBufferedOps endBufferedOps() }.

bufferedReceive

public final TFTPPacket bufferedReceive()
This is a special method to perform a more efficient packet receive. It should only be used after calling {@link #beginBufferedOps beginBufferedOps() }. beginBufferedOps() initializes a set of buffers used internally that prevent the new allocation of a DatagramPacket and byte array for each send and receive. To use these buffers you must call the bufferedReceive() and bufferedSend() methods instead of send() and receive(). You must also be certain that you don't manipulate the resulting packet in such a way that it interferes with future buffered operations. For example, a TFTPDataPacket received with bufferedReceive() will have a reference to the internal byte buffer. You must finish using this data before calling bufferedReceive() again, or else the data will be overwritten by the the call.

Returns: The TFTPPacket received.

Throws: InterruptedIOException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe. SocketException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe. IOException If some other I/O error occurs. TFTPPacketException If an invalid TFTP packet is received.

bufferedSend

public final void bufferedSend(TFTPPacket packet)
This is a special method to perform a more efficient packet send. It should only be used after calling {@link #beginBufferedOps beginBufferedOps() }. beginBufferedOps() initializes a set of buffers used internally that prevent the new allocation of a DatagramPacket and byte array for each send and receive. To use these buffers you must call the bufferedReceive() and bufferedSend() methods instead of send() and receive(). You must also be certain that you don't manipulate the resulting packet in such a way that it interferes with future buffered operations. For example, a TFTPDataPacket received with bufferedReceive() will have a reference to the internal byte buffer. You must finish using this data before calling bufferedReceive() again, or else the data will be overwritten by the the call.

Parameters: packet The TFTP packet to send.

Throws: IOException If some I/O error occurs.

discardPackets

public final void discardPackets()
This method synchronizes a connection by discarding all packets that may be in the local socket buffer. This method need only be called when you implement your own TFTP client or server.

Throws: IOException if an I/O error occurs.

endBufferedOps

public final void endBufferedOps()
Releases the resources used to perform buffered sends and receives.

getModeName

public static final String getModeName(int mode)
Returns the TFTP string representation of a TFTP transfer mode. Will throw an ArrayIndexOutOfBoundsException if an invalid transfer mode is specified.

Parameters: mode The TFTP transfer mode. One of the MODE constants.

Returns: The TFTP string representation of the TFTP transfer mode.

receive

public final TFTPPacket receive()
Receives a TFTPPacket.

Returns: The TFTPPacket received.

Throws: InterruptedIOException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe. SocketException If a socket timeout occurs. The Java documentation claims an InterruptedIOException is thrown on a DatagramSocket timeout, but in practice we find a SocketException is thrown. You should catch both to be safe. IOException If some other I/O error occurs. TFTPPacketException If an invalid TFTP packet is received.

send

public final void send(TFTPPacket packet)
Sends a TFTP packet to its destination.

Parameters: packet The TFTP packet to send.

Throws: IOException If some I/O error occurs.