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 */
017 package org.apache.logging.log4j.core.net;
018
019 import java.io.IOException;
020 import java.io.OutputStream;
021 import java.net.DatagramPacket;
022 import java.net.DatagramSocket;
023 import java.net.InetAddress;
024 import java.net.SocketException;
025 import java.net.UnknownHostException;
026
027 import org.apache.logging.log4j.Logger;
028 import org.apache.logging.log4j.core.appender.AppenderLoggingException;
029 import org.apache.logging.log4j.status.StatusLogger;
030
031 /**
032 * OutputStream for UDP connections.
033 */
034 public 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 }