SyslogAppender

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.log4j.core.appender;

import java.io.Serializable;

import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.helpers.Booleans;
import org.apache.logging.log4j.core.layout.LoggerFields;
import org.apache.logging.log4j.core.layout.RFC5424Layout;
import org.apache.logging.log4j.core.layout.SyslogLayout;
import org.apache.logging.log4j.core.net.AbstractSocketManager;
import org.apache.logging.log4j.core.net.Advertiser;
import org.apache.logging.log4j.core.net.Protocol;
import org.apache.logging.log4j.util.EnglishEnums;

/**
 * The Syslog Appender.
 */
@Plugin(name = "Syslog", category = "Core", elementType = "appender", printObject = true)
public class SyslogAppender extends SocketAppender {

    protected static final String RFC5424 = "RFC5424";

    protected SyslogAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
                             final boolean ignoreExceptions, final boolean immediateFlush,
                             final AbstractSocketManager manager, final Advertiser advertiser) {
        super(name, layout, filter, manager, ignoreExceptions, immediateFlush, advertiser);

    }

    /**
     * Create a SyslogAppender.
     * @param host The name of the host to connect to.
     * @param portNum The port to connect to on the target host.
     * @param protocol The Protocol to use.
     * @param delay The interval in which failed writes should be retried.
     * @param immediateFail True if the write should fail if no socket is immediately available.
     * @param name The name of the Appender.
     * @param immediateFlush "true" if data should be flushed on each write.
     * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
     *               they are propagated to the caller.
     * @param facility The Facility is used to try to classify the message.
     * @param id The default structured data id to use when formatting according to RFC 5424.
     * @param ein The IANA enterprise number.
     * @param includeMDC Indicates whether data from the ThreadContextMap will be included in the RFC 5424 Syslog
     * record. Defaults to "true:.
     * @param mdcId The id to use for the MDC Structured Data Element.
     * @param mdcPrefix The prefix to add to MDC key names.
     * @param eventPrefix The prefix to add to event key names.
     * @param includeNL If true, a newline will be appended to the end of the syslog record. The default is false.
     * @param escapeNL String that should be used to replace newlines within the message text.
     * @param appName The value to use as the APP-NAME in the RFC 5424 syslog record.
     * @param msgId The default value to be used in the MSGID field of RFC 5424 syslog records.
     * @param excludes A comma separated list of mdc keys that should be excluded from the LogEvent.
     * @param includes A comma separated list of mdc keys that should be included in the FlumeEvent.
     * @param required A comma separated list of mdc keys that must be present in the MDC.
     * @param format If set to "RFC5424" the data will be formatted in accordance with RFC 5424. Otherwise,
     * it will be formatted as a BSD Syslog record.
     * @param filter A Filter to determine if the event should be handled by this Appender.
     * @param config The Configuration.
     * @param charsetName The character set to use when converting the syslog String to a byte array.
     * @param exceptionPattern The converter pattern to use for formatting exceptions.
     * @param loggerFields The logger fields
     * @param advertise Whether to advertise
     * @return A SyslogAppender.
     */
    @PluginFactory
    public static SyslogAppender createAppender(
            @PluginAttribute("host") final String host,
            @PluginAttribute("port") final String portNum,
            @PluginAttribute("protocol") final String protocol,
            @PluginAttribute("reconnectionDelay") final String delay,
            @PluginAttribute("immediateFail") final String immediateFail,
            @PluginAttribute("name") final String name,
            @PluginAttribute("immediateFlush") final String immediateFlush,
            @PluginAttribute("ignoreExceptions") final String ignore,
            @PluginAttribute("facility") final String facility,
            @PluginAttribute("id") final String id,
            @PluginAttribute("enterpriseNumber") final String ein,
            @PluginAttribute("includeMDC") final String includeMDC,
            @PluginAttribute("mdcId") final String mdcId,
            @PluginAttribute("mdcPrefix") final String mdcPrefix,
            @PluginAttribute("eventPrefix") final String eventPrefix,
            @PluginAttribute("newLine") final String includeNL,
            @PluginAttribute("newLineEscape") final String escapeNL,
            @PluginAttribute("appName") final String appName,
            @PluginAttribute("messageId") final String msgId,
            @PluginAttribute("mdcExcludes") final String excludes,
            @PluginAttribute("mdcIncludes") final String includes,
            @PluginAttribute("mdcRequired") final String required,
            @PluginAttribute("format") final String format,
            @PluginElement("Filters") final Filter filter,
            @PluginConfiguration final Configuration config,
            @PluginAttribute("charset") final String charsetName,
            @PluginAttribute("exceptionPattern") final String exceptionPattern,
            @PluginElement("LoggerFields") final LoggerFields[] loggerFields,
            @PluginAttribute("advertise") final String advertise) {

        final boolean isFlush = Booleans.parseBoolean(immediateFlush, true);
        final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
        final int reconnectDelay = AbstractAppender.parseInt(delay, 0);
        final boolean fail = Booleans.parseBoolean(immediateFail, true);
        final int port = AbstractAppender.parseInt(portNum, 0);
        final boolean isAdvertise = Boolean.parseBoolean(advertise);
        final Layout<? extends Serializable> layout = (RFC5424.equalsIgnoreCase(format) ?
            RFC5424Layout.createLayout(facility, id, ein, includeMDC, mdcId, mdcPrefix, eventPrefix, includeNL,
                escapeNL, appName, msgId, excludes, includes, required, exceptionPattern, "false", loggerFields,
                config) :
            SyslogLayout.createLayout(facility, includeNL, escapeNL, charsetName));

        if (name == null) {
            LOGGER.error("No name provided for SyslogAppender");
            return null;
        }
        final Protocol p = EnglishEnums.valueOf(Protocol.class, protocol);
        final AbstractSocketManager manager = createSocketManager(p, host, port, reconnectDelay, fail, layout);
        if (manager == null) {
            return null;
        }

        return new SyslogAppender(name, layout, filter, ignoreExceptions, isFlush, manager,
                isAdvertise ? config.getAdvertiser() : null);
    }
}