Add syslog writer

tinylog-impl/src/main/java/org/tinylog/writers/AbstractFileBasedWriter.java

@@ -65,7 +65,7 @@ protected String getFileName() {
 	 *
 	 * @return Configured charset
 	 */
-	protected Charset getCharset() {
+	protected final Charset getCharset() {
 		String charsetName = getStringValue("charset");
 		try {
 			return charsetName == null ? Charset.defaultCharset() : Charset.forName(charsetName);

tinylog-impl/src/main/java/org/tinylog/writers/SyslogWriter.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2023 Piotr Karlowicz
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package org.tinylog.writers;
+
+import java.io.IOException;
+import java.util.Locale;
+import java.util.Map;
+
+import org.tinylog.core.LogEntry;
+import org.tinylog.writers.raw.AbstractSocketWriter;
+import org.tinylog.writers.raw.TcpSocketWriter;
+import org.tinylog.writers.raw.UdpSocketWriter;
+
+/**
+ * Writer for outputting log entries to syslog server.
+ */
+public final class SyslogWriter extends AbstractFormatPatternWriter {
+
+	private AbstractSocketWriter socketWriter;
+
+	/**
+	 * @param properties
+	 *            Configuration for writer
+	 *
+	 * @throws IOException
+	 *             Socket cannot be opened for write access
+	 * @throws IllegalArgumentException
+	 *             A property has an invalid value or is missing in configuration
+	 */
+	public SyslogWriter(final Map<String, String> properties) throws IllegalArgumentException, IOException {
+		super(properties);
+
+		String protocol = getStringValue("protocol");
+		if (protocol == null) {
+			throw new IllegalArgumentException("Missing protocol");
+		} else if (protocol.toUpperCase(Locale.ROOT).equals("UDP")) {
+			socketWriter = new UdpSocketWriter(properties);
+		} else if (protocol.toUpperCase(Locale.ROOT).equals("TCP")) {
+			socketWriter = new TcpSocketWriter(properties);
+		} else {
+			throw new IllegalArgumentException("Invalid protocol");
+		}
+	}
+
+	@Override
+	public void write(final LogEntry logEntry) throws Exception { 
+		socketWriter.write(logEntry);
+	}
+
+	@Override
+	public void flush() throws Exception {
+		socketWriter.flush();
+	}
+
+	@Override
+	public void close() throws Exception {
+		socketWriter.close();
+	}
+
+}

tinylog-impl/src/main/java/org/tinylog/writers/raw/AbstractSocketWriter.java

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2023 Piotr Karlowicz
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package org.tinylog.writers.raw;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.charset.Charset;
+import java.util.Map;
+
+import org.tinylog.Level;
+import org.tinylog.core.LogEntry;
+import org.tinylog.writers.AbstractFormatPatternWriter;
+
+/**
+ * Base writer for outputting log entries to syslog server.
+ */
+public abstract class AbstractSocketWriter extends AbstractFormatPatternWriter {
+
+	private static final String DEFAULT_HOST_NAME = "localhost";
+	private static final int DEFAULT_PORT_NUMBER = 514;
+	private static final String DEFAULT_FACILITY = "USER";
+	private static final int FACILITY_CODE_SHIFT = 3;
+	private static final String DEFAULT_SEVERITY = "INFO";
+
+	private final InetAddress inetAddress;
+	private final int port;
+	private final Charset charset;
+	private final String identification;
+
+	/**
+	 * @param properties
+	 *            Configuration for writer
+	 * 
+	 * @throws UnknownHostException 
+	 *            Host name cannot be identified
+	 */
+	public AbstractSocketWriter(final Map<String, String> properties) throws UnknownHostException {
+		super(properties);
+
+		String host = getStringValue("host");
+		if (host == null) {
+			host = DEFAULT_HOST_NAME;
+		}
+		inetAddress = InetAddress.getByName("localhost");
+		String portNumber = getStringValue("port");
+		if (portNumber == null) {
+			port = DEFAULT_PORT_NUMBER;
+		} else {
+			port = Integer.parseInt(portNumber);
+		}
+		charset = getCharset();
+		String identification = getStringValue("identification");
+		if (identification == null) {
+			this.identification = "";
+		} else {
+			this.identification = identification;
+		}
+	}
+
+	public final InetAddress getInetAddress() {
+		return inetAddress;
+	}
+
+	public final int getPort() {
+		return port;
+	}
+
+	/**
+	 * Return the priority code for facility and severity.
+	 * 
+	 * @param level
+	 *            Log level to use when severity is not specified.
+	 * 
+	 * @return The priority code calculated from facility and severity code.
+	 */
+	public int getCode(final Level level) {
+		String facility = getStringValue("facility");
+		String severity = getStringValue("severity");
+
+		if (facility == null) {
+			facility = DEFAULT_FACILITY;
+		}
+
+		int facilityCode = SyslogFacility.valueOf(facility).getCode();
+
+		if (severity == null) {
+			if (level != null) {
+				severity = SyslogSeverity.getSeverity(level).name();
+			} else {
+				severity = DEFAULT_SEVERITY;
+			}
+		}
+
+		int severityCode = SyslogSeverity.valueOf(severity).getCode();
+
+		return (facilityCode << FACILITY_CODE_SHIFT) + severityCode;
+	}
+
+	/**
+	 * Return the formated syslog message. 
+	 * 
+	 * @param logEntry
+	 *            Log entry for rendering.
+	 * 
+	 * @return The formated message.
+	 */
+	public byte[] formatMessage(final LogEntry logEntry) {
+
+		StringBuilder builder = new StringBuilder();
+		builder.append("<");
+		builder.append(getCode(logEntry.getLevel()));
+		builder.append(">");
+		builder.append(identification);
+		builder.append(": ");
+		builder.append(render(logEntry));
+		return builder.toString().getBytes(charset);
+	}
+}

tinylog-impl/src/main/java/org/tinylog/writers/raw/SyslogFacility.java

@@ -0,0 +1,154 @@
+/*
+ * Copyright 2023 Piotr Karlowicz
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package org.tinylog.writers.raw;
+
+/**
+ * Syslog Facility codes.
+ */
+public enum SyslogFacility {
+
+	/**
+	 * Kernel messages.
+	 */
+	KERN(0),
+
+	/**
+	 * User level messages.
+	 */
+	USER(1),
+
+	/**
+	 * Mail system.
+	 */
+	MAIL(2),
+
+	/**
+	 * System daemons.
+	 */
+	DAEMON(3),
+
+	/**
+	 * Security/Authorization messages.
+	 */
+	AUTH(4),
+
+	/**
+	 * Messages generated by syslogd.
+	 */
+	SYSLOG(5),
+
+	/**
+	 * Line printer subsystem.
+	 */
+	LPR(6),
+
+	/**
+	 * Network news subsystem.
+	 */
+	NEWS(7),
+
+	/**
+	 * UUCP subsystem.
+	 */
+	UUCP(8),
+
+	/**
+	 * Clock daemon.
+	 */
+	CRON(9),
+
+	/**
+	 * Security/Authorization messages.
+	 */
+	AUTHPRIV(10),
+
+	/**
+	 * FTP daemon.
+	 */
+	FTP(11),
+
+	/**
+	 * NTP subsystem.
+	 */
+	NTP(12),
+
+	/**
+	 * Log audit.
+	 */
+	LOG_AUDIT(13),
+
+	/**
+	 * Log alert.
+	 */
+	LOG_ALERT(14),
+
+	/**
+	 * Clock daemon.
+	 */
+	CLOCK(15),
+
+	/**
+	 * Local use 0.
+	 */
+	LOCAL0(16),
+
+	/**
+	 * Local use 1.
+	 */
+	LOCAL1(17),
+
+	/**
+	 * Local use 2.
+	 */
+	LOCAL2(18),
+
+	/**
+	 * Local use 3.
+	 */
+	LOCAL3(19),
+
+	/**
+	 * Local use 4.
+	 */
+	LOCAL4(20),
+
+	/**
+	 * Local use 5.
+	 */
+	LOCAL5(21),
+
+	/**
+	 * Local use 6.
+	 */
+	LOCAL6(22),
+
+	/**
+	 * Local use 7.
+	 */
+	LOCAL7(23);
+
+	private final int code;
+
+	SyslogFacility(final int code) {
+		this.code = code;
+	}
+
+	/**
+	 * Retrieve the value of the enumeration.
+	 * @return The value associated with the enumeration.
+	 */
+	public int getCode() {
+		return this.code;
+	}
+}