Package org.apache.commons.net.tftp

Class TFTP

  • All Implemented Interfaces:
    java.lang.AutoCloseable
    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.

    See Also:
    DatagramSocketClient, TFTPPacket, TFTPPacketException, TFTPClient

    • 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

        @Deprecated
public static final int DEFAULT_TIMEOUT
        Deprecated.
        Use DEFAULT_TIMEOUT_DURATION.
        The default number of milliseconds to wait to receive a datagram before timing out. The default is 5,000 milliseconds (5 seconds).
        See Also:
        Constant Field Values

      • DEFAULT_TIMEOUT_DURATION

        public static final java.time.Duration DEFAULT_TIMEOUT_DURATION
        The default duration to wait to receive a datagram before timing out. The default is 5 seconds.
        Since:
        3.10.0

      • DEFAULT_PORT

        public static final int DEFAULT_PORT
        The default TFTP port according to RFC 783 is 69.
        See Also:
        Constant Field Values

      • PACKET_SIZE

        static final int PACKET_SIZE
        The size to use for TFTP packet buffers. Its 4 plus the TFTPPacket.SEGMENT_SIZE, i.e. 516.
        See Also:
        Constant Field Values

      • receiveBuffer

        private byte[] receiveBuffer
        A buffer used to accelerate receives in bufferedReceive()

      • receiveDatagram

        private java.net.DatagramPacket receiveDatagram
        A datagram used to minimize memory allocation in bufferedReceive()

      • sendDatagram

        private java.net.DatagramPacket sendDatagram
        A datagram used to minimize memory allocation in bufferedSend()

      • packetSize

        private int packetSize
        Internal packet size, which is the data octet size plus 4 (for TFTP header octets)

      • buffersInitialized

        private boolean buffersInitialized
        Internal state to track if the send/receive buffers are initialized

      • sendBuffer

        byte[] sendBuffer
        A buffer used to accelerate sends in bufferedSend(). It is left package visible so that TFTPClient may be slightly more efficient during file sends. It saves the creation of an additional buffer and prevents a buffer copy in _newDataPcket().

    • Constructor Detail

      • TFTP

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

    • Method Detail

      • getModeName

        public static final java.lang.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.

      • 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().

      • bufferedReceive

        public final TFTPPacket bufferedReceive()
                                 throws java.io.IOException,
                                        java.io.InterruptedIOException,
                                        java.net.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 call.
        Returns:
        The TFTPPacket received.
        Throws:
        java.io.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.
        java.net.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.
        java.io.IOException - If some other I/O error occurs.
        TFTPPacketException - If an invalid TFTP packet is received.

      • bufferedSend

        public final void bufferedSend​(TFTPPacket packet)
                        throws java.io.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 call.
        Parameters:
        packet - The TFTP packet to send.
        Throws:
        java.io.IOException - If some I/O error occurs.

      • discardPackets

        public final void discardPackets()
                          throws java.io.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:
        java.io.IOException - if an I/O error occurs.

      • endBufferedOps

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

      • receive

        public final TFTPPacket receive()
                         throws java.io.IOException,
                                java.io.InterruptedIOException,
                                java.net.SocketException,
                                TFTPPacketException
        Receives a TFTPPacket.
        Returns:
        The TFTPPacket received.
        Throws:
        java.io.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.
        java.net.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.
        java.io.IOException - If some other I/O error occurs.
        TFTPPacketException - If an invalid TFTP packet is received.

      • resetBuffersToSize

        public final void resetBuffersToSize​(int packetSize)
        Sets the size of the buffers used to receive and send packets. This method can be used to increase the size of the buffer to support `blksize`. For which valid values range between "8" and "65464" octets (RFC-2348). This only refers to the number of data octets, it does not include the four octets of TFTP header.
        Parameters:
        packetSize - The size of the data octets not including 4 octets for the header.
        Since:
        3.12.0

      • send

        public final void send​(TFTPPacket packet)
                throws java.io.IOException
        Sends a TFTP packet to its destination.
        Parameters:
        packet - The TFTP packet to send.
        Throws:
        java.io.IOException - If some I/O error occurs.

      • trace

        protected void trace​(java.lang.String direction,
                     TFTPPacket packet)
        Trace facility; this implementation does nothing.

        Override it to trace the data, for example:
        System.out.println(direction + " " + packet.toString());

        Parameters:
        direction - > or <
        packet - the packet to be sent or that has been received respectively
        Since:
        3.6