org.apache.commons.net.tftp
Class TFTP

java.lang.Object
  extended by org.apache.commons.net.DatagramSocketClient
      extended by org.apache.commons.net.tftp.TFTP
Direct Known Subclasses:
TFTPClient

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 open() , and close() , methods. Additionally,the a 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, TFTPClient

Field Summary
static int ASCII_MODE
          The ascii transfer mode.
static int BINARY_MODE
          The binary transfer mode.
static int DEFAULT_PORT
          The default TFTP port according to RFC 783 is 69.
static int DEFAULT_TIMEOUT
          The default number of milliseconds to wait to receive a datagram before timing out.
static int IMAGE_MODE
          The image transfer mode.
static int NETASCII_MODE
          The netascii transfer mode.
static int OCTET_MODE
          The octet transfer mode.
 
Fields inherited from class org.apache.commons.net.DatagramSocketClient
_isOpen_, _socket_, _socketFactory_, _timeout_
 
Constructor Summary
TFTP()
          Creates a TFTP instance with a default timeout of DEFAULT_TIMEOUT, a null socket, and buffered operations disabled.
 
Method Summary
 void beginBufferedOps()
          Initializes the internal buffers.
 TFTPPacket bufferedReceive()
          This is a special method to perform a more efficient packet receive.
 void bufferedSend(TFTPPacket packet)
          This is a special method to perform a more efficient packet send.
 void discardPackets()
          This method synchronizes a connection by discarding all packets that may be in the local socket buffer.
 void endBufferedOps()
          Releases the resources used to perform buffered sends and receives.
static String getModeName(int mode)
          Returns the TFTP string representation of a TFTP transfer mode.
 TFTPPacket receive()
          Receives a TFTPPacket.
 void send(TFTPPacket packet)
          Sends a TFTP packet to its destination.
 
Methods inherited from class org.apache.commons.net.DatagramSocketClient
close, getDefaultTimeout, getLocalAddress, getLocalPort, getSoTimeout, isOpen, open, open, open, setDatagramSocketFactory, setDefaultTimeout, setSoTimeout
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

ASCII_MODE

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

See Also:
Constant Field Values

NETASCII_MODE

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

See Also:
Constant Field Values

BINARY_MODE

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

See Also:
Constant Field Values

IMAGE_MODE

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

See Also:
Constant Field Values

OCTET_MODE

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

See Also:
Constant Field Values

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).

See Also:
Constant Field Values

DEFAULT_PORT

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

See Also:
Constant Field Values
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

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.

discardPackets

public final void discardPackets()
                          throws IOException
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.

bufferedReceive

public final TFTPPacket bufferedReceive()
                                 throws IOException,
                                        InterruptedIOException,
                                        SocketException,
                                        TFTPPacketException
This is a special method to perform a more efficient packet receive. It should only be used after calling 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)
                        throws IOException
This is a special method to perform a more efficient packet send. It should only be used after calling 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.

beginBufferedOps

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


endBufferedOps

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


send

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

Parameters:
packet - The TFTP packet to send.
Throws:
IOException - If some I/O error occurs.

receive

public final TFTPPacket receive()
                         throws IOException,
                                InterruptedIOException,
                                SocketException,
                                TFTPPacketException
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.


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