Class TFTPPacket

  • Direct Known Subclasses:
    TFTPAckPacket, TFTPDataPacket, TFTPErrorPacket, TFTPRequestPacket

    public abstract class TFTPPacket
    extends java.lang.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 Description
      static int ACKNOWLEDGEMENT
      This is the actual TFTP spec identifier and is equal to 4.
      (package private) java.net.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.
      (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 Description
      TFTPPacket​(int type, java.net.InetAddress address, int port)
      This constructor is not visible outside of the package.
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      java.net.InetAddress getAddress()
      Returns the address of the host where the packet is going to be sent or where it came from.
      int getPort()
      Returns the port where the packet is going to be sent or where it came from.
      int getType()
      Returns the type of the packet.
      abstract java.net.DatagramPacket newDatagram()
      Creates a UDP datagram containing all the TFTP packet data in the proper format.
      (package private) abstract java.net.DatagramPacket newDatagram​(java.net.DatagramPacket datagram, byte[] data)
      This is an abstract method only available within the package for implementing efficient datagram transport by elminating buffering.
      static TFTPPacket newTFTPPacket​(java.net.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​(java.net.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.
      java.lang.String toString()
      For debugging
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • 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
      • 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
      • 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
      • 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
      • 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
      • 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
      • 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.
      • port

        int port
        The port the packet came from or is going to.
      • address

        java.net.InetAddress address
        The host the packet is going to be sent or where it came from.
    • Constructor Detail

      • TFTPPacket

        TFTPPacket​(int type,
                   java.net.InetAddress address,
                   int port)
        This constructor is not visible outside of 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

      • newTFTPPacket

        public static final TFTPPacket newTFTPPacket​(java.net.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.
      • newDatagram

        abstract java.net.DatagramPacket newDatagram​(java.net.DatagramPacket datagram,
                                                     byte[] data)
        This is an abstract method only available within the package for implementing efficient datagram transport by elminating 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.
      • newDatagram

        public abstract java.net.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.
      • getType

        public final int getType()
        Returns the type of the packet.
        Returns:
        The type of the packet.
      • getAddress

        public final java.net.InetAddress getAddress()
        Returns 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()
        Returns 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.
      • setPort

        public final void setPort​(int port)
        Sets the port where the packet is going to be sent.
        Parameters:
        port - the port to set
      • setAddress

        public final void setAddress​(java.net.InetAddress address)
        Sets the host address where the packet is going to be sent.
        Parameters:
        address - the address to set
      • toString

        public java.lang.String toString()
        For debugging
        Overrides:
        toString in class java.lang.Object
        Since:
        3.6