org.acplt.oncrpc.XdrUdpEncodingStream Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of remotetea-oncrpc Show documentation
Show all versions of remotetea-oncrpc Show documentation
The runtime environment for ONC/RPC programs, both client and server side.
/*
* $Header: /home/harald/repos/remotetea.sf.net/remotetea/src/org/acplt/oncrpc/XdrUdpEncodingStream.java,v 1.2 2003/08/14 11:07:39 haraldalbrecht Exp $
*
* Copyright (c) 1999, 2000
* Lehrstuhl fuer Prozessleittechnik (PLT), RWTH Aachen
* D-52064 Aachen, Germany.
* All rights reserved.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program (see the file LICENSE.txt for more
* details); if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package org.acplt.oncrpc;
import java.io.*;
import java.net.*;
/**
* The XdrUdpDecodingStream class provides the necessary
* functionality to {@link XdrDecodingStream} to send XDR packets over the
* network using the datagram-oriented UDP/IP.
*
* @version $Revision: 1.2 $ $Date: 2003/08/14 11:07:39 $ $State: Exp $ $Locker: $
* @author Harald Albrecht
*/
public class XdrUdpEncodingStream extends XdrEncodingStream {
/**
* Creates a new UDP-based encoding XDR stream, associated with the
* given datagram socket.
*
* @param datagramSocket Datagram-based socket to use to get rid of
* encoded data.
* @param bufferSize Size of buffer to store encoded data before it
* is sent as one datagram.
*/
public XdrUdpEncodingStream(DatagramSocket datagramSocket,
int bufferSize) {
socket = datagramSocket;
//
// If the given buffer size is too small, start with a more sensible
// size. Next, if bufferSize is not a multiple of four, round it up to
// the next multiple of four.
//
if ( bufferSize < 1024 ) {
bufferSize = 1024;
}
if ( (bufferSize & 3) != 0 ) {
bufferSize = (bufferSize + 4) & ~3;
}
buffer = new byte[bufferSize];
bufferIndex = 0;
bufferHighmark = bufferSize - 4;
}
/**
* Begins encoding a new XDR record. This involves resetting this
* encoding XDR stream back into a known state.
*
* @param receiverAddress Indicates the receiver of the XDR data. This can be
* null for XDR streams connected permanently to a
* receiver (like in case of TCP/IP based XDR streams).
* @param receiverPort Port number of the receiver.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public void beginEncoding(InetAddress receiverAddress, int receiverPort)
throws OncRpcException, IOException {
this.receiverAddress = receiverAddress;
this.receiverPort = receiverPort;
bufferIndex = 0;
}
/**
* Flushes this encoding XDR stream and forces any buffered output bytes
* to be written out. The general contract of endEncoding is that
* calling it is an indication that the current record is finished and any
* bytes previously encoded should immediately be written to their intended
* destination.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public void endEncoding()
throws OncRpcException, IOException {
DatagramPacket packet = new DatagramPacket(buffer, bufferIndex,
receiverAddress,
receiverPort);
socket.send(packet);
}
/**
* Closes this encoding XDR stream and releases any system resources
* associated with this stream. The general contract of close
* is that it closes the encoding XDR stream. A closed XDR stream cannot
* perform encoding operations and cannot be reopened.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public void close()
throws OncRpcException, IOException {
buffer = null;
socket = null;
}
/**
* Encodes (aka "serializes") a "XDR int" value and writes it down a
* XDR stream. A XDR int is 32 bits wide -- the same width Java's "int"
* data type has. This method is one of the basic methods all other
* methods can rely on.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public void xdrEncodeInt(int value)
throws OncRpcException, IOException {
if ( bufferIndex <= bufferHighmark ) {
//
// There's enough space in the buffer, so encode this int as
// four bytes (french octets) in big endian order (that is, the
// most significant byte comes first.
//
buffer[bufferIndex++] = (byte)(value >>> 24);
buffer[bufferIndex++] = (byte)(value >>> 16);
buffer[bufferIndex++] = (byte)(value >>> 8);
buffer[bufferIndex++] = (byte) value;
} else {
throw(new OncRpcException(OncRpcException.RPC_BUFFEROVERFLOW));
}
}
/**
* Encodes (aka "serializes") a XDR opaque value, which is represented
* by a vector of byte values, and starts at offset with a
* length of length. Only the opaque value is encoded, but
* no length indication is preceeding the opaque value, so the receiver
* has to know how long the opaque value will be. The encoded data is
* always padded to be a multiple of four. If the given length is not a
* multiple of four, zero bytes will be used for padding.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public void xdrEncodeOpaque(byte [] value, int offset, int length)
throws OncRpcException, IOException {
//
// First calculate the number of bytes needed for padding.
//
int padding = (4 - (length & 3)) & 3;
if ( bufferIndex <= bufferHighmark - (length + padding) ) {
System.arraycopy(value, offset, buffer, bufferIndex, length);
bufferIndex += length;
if ( padding != 0 ) {
//
// If the length of the opaque data was not a multiple, then
// pad with zeros, so the write pointer (argh! how comes Java
// has a pointer...?!) points to a byte, which has an index
// of a multiple of four.
//
System.arraycopy(paddingZeros, 0, buffer, bufferIndex, padding);
bufferIndex += padding;
}
} else {
throw(new OncRpcException(OncRpcException.RPC_BUFFEROVERFLOW));
}
}
/**
* The datagram socket to be used when sending this XDR stream's
* buffer contents.
*/
private DatagramSocket socket;
/**
* Receiver address of current buffer contents when flushed.
*/
private InetAddress receiverAddress = null;
/**
* The receiver's port.
*/
private int receiverPort = 0;
/**
* The buffer which will receive the encoded information, before it
* is sent via a datagram socket.
*/
private byte [] buffer;
/**
* The write pointer is an index into the buffer.
*/
private int bufferIndex;
/**
* Index of the last four byte word in the buffer.
*/
private int bufferHighmark;
/**
* Some zeros, only needed for padding -- like in real life.
*/
private static final byte [] paddingZeros = { 0, 0, 0, 0 };
}
// End of XdrUdpEncodingStream