001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.net;
018
019import java.io.IOException;
020import java.io.OutputStream;
021import java.net.DatagramPacket;
022import java.net.DatagramSocket;
023import java.net.InetAddress;
024import java.net.SocketException;
025import java.net.UnknownHostException;
026
027import org.apache.logging.log4j.Logger;
028import org.apache.logging.log4j.core.appender.AppenderLoggingException;
029import org.apache.logging.log4j.status.StatusLogger;
030
031/**
032 * OutputStream for UDP connections.
033 */
034public class DatagramOutputStream extends OutputStream {
035
036    /**
037     * Allow subclasses access to the status logger without creating another instance.
038     */
039    protected static final Logger LOGGER = StatusLogger.getLogger();
040
041    private static final int SHIFT_1 = 8;
042    private static final int SHIFT_2 = 16;
043    private static final int SHIFT_3 = 24;
044
045    private DatagramSocket ds;
046    private final InetAddress address;
047    private final int port;
048
049    private byte[] data;
050
051    private final byte[] header;
052    private final byte[] footer;
053
054    /**
055     * The Constructor.
056     * @param host The host to connect to.
057     * @param port The port on the host.
058     */
059    public DatagramOutputStream(final String host, final int port, final byte[] header, final byte[] footer) {
060        this.port = port;
061        this.header = header;
062        this.footer = footer;
063        try {
064            address = InetAddress.getByName(host);
065        } catch (final UnknownHostException ex) {
066            final String msg = "Could not find host " + host;
067            LOGGER.error(msg, ex);
068            throw new AppenderLoggingException(msg, ex);
069        }
070
071        try {
072            ds = new DatagramSocket();
073        } catch (final SocketException ex) {
074            final String msg = "Could not instantiate DatagramSocket to " + host;
075            LOGGER.error(msg, ex);
076            throw new AppenderLoggingException(msg, ex);
077        }
078    }
079
080    @Override
081    public synchronized void write(final byte[] bytes, final int offset, final int length) throws IOException {
082        copy(bytes, offset, length);
083    }
084
085    @Override
086    public synchronized void write(final int i) throws IOException {
087        copy(new byte[] {(byte) (i >>> SHIFT_3), (byte) (i >>> SHIFT_2), (byte) (i >>> SHIFT_1), (byte) i}, 0, 4);
088    }
089
090    @Override
091    public synchronized void write(final byte[] bytes) throws IOException {
092        copy(bytes, 0, bytes.length);
093    }
094
095    @Override
096    public synchronized void flush() throws IOException {
097        try {
098            if (this.data != null && this.ds != null && this.address != null) {
099                if (footer != null) {
100                    copy(footer, 0, footer.length);
101                }
102                final DatagramPacket packet = new DatagramPacket(data, data.length, address, port);
103                ds.send(packet);
104            }
105        } finally {
106            data = null;
107            if (header != null) {
108                copy(header, 0, header.length);
109            }
110        }
111    }
112
113    @Override
114    public synchronized void close() throws IOException {
115        if (ds != null) {
116            if (data != null) {
117                flush();
118            }
119            ds.close();
120            ds = null;
121        }
122    }
123
124    private void copy(final byte[] bytes, final int offset, final int length) {
125        final int index = data == null ? 0 : data.length;
126        final byte[] copy = new byte[length + index];
127        if (data != null) {
128            System.arraycopy(data, 0, copy, 0, data.length);
129        }
130        System.arraycopy(bytes, offset, copy, index, length);
131        data = copy;
132    }
133}