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.appender.rewrite;
018    
019    import java.util.HashMap;
020    import java.util.Map;
021    
022    import org.apache.logging.log4j.Logger;
023    import org.apache.logging.log4j.core.LogEvent;
024    import org.apache.logging.log4j.core.config.plugins.Plugin;
025    import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
026    import org.apache.logging.log4j.core.config.plugins.PluginElement;
027    import org.apache.logging.log4j.core.config.plugins.PluginFactory;
028    import org.apache.logging.log4j.core.impl.Log4jLogEvent;
029    import org.apache.logging.log4j.core.util.KeyValuePair;
030    import org.apache.logging.log4j.message.MapMessage;
031    import org.apache.logging.log4j.message.Message;
032    import org.apache.logging.log4j.status.StatusLogger;
033    
034    /**
035     * This policy modifies events by replacing or possibly adding keys and values to the MapMessage.
036     */
037    @Plugin(name = "MapRewritePolicy", category = "Core", elementType = "rewritePolicy", printObject = true)
038    public final class MapRewritePolicy implements RewritePolicy {
039        /**
040         * Allow subclasses access to the status logger without creating another instance.
041         */
042        protected static final Logger LOGGER = StatusLogger.getLogger();
043    
044        private final Map<String, String> map;
045    
046        private final Mode mode;
047    
048        private MapRewritePolicy(final Map<String, String> map, final Mode mode) {
049            this.map = map;
050            this.mode = mode;
051        }
052    
053        /**
054         * Rewrite the event.
055         * @param source a logging event that may be returned or
056         * used to create a new logging event.
057         * @return The LogEvent after rewriting.
058         */
059        @Override
060        public LogEvent rewrite(final LogEvent source) {
061            final Message msg = source.getMessage();
062            if (msg == null || !(msg instanceof MapMessage)) {
063                return source;
064            }
065    
066            final Map<String, String> newMap = new HashMap<String, String>(((MapMessage) msg).getData());
067            switch (mode) {
068                case Add: {
069                    newMap.putAll(map);
070                    break;
071                }
072                default: {
073                    for (final Map.Entry<String, String> entry : map.entrySet()) {
074                        if (newMap.containsKey(entry.getKey())) {
075                            newMap.put(entry.getKey(), entry.getValue());
076                        }
077                    }
078                }
079            }
080            final MapMessage message = ((MapMessage) msg).newInstance(newMap);
081            if (source instanceof Log4jLogEvent) {
082                final Log4jLogEvent event = (Log4jLogEvent) source;
083                return Log4jLogEvent.createEvent(event.getLoggerName(), event.getMarker(), event.getLoggerFqcn(),
084                    event.getLevel(), message, event.getThrown(), event.getThrownProxy(), event.getContextMap(), 
085                    event.getContextStack(), event.getThreadName(), event.getSource(), event.getTimeMillis());
086            }
087            return new Log4jLogEvent(source.getLoggerName(), source.getMarker(), source.getLoggerFqcn(), source.getLevel(),
088                message, source.getThrown(), source.getContextMap(), source.getContextStack(), source.getThreadName(),
089                source.getSource(), source.getTimeMillis());
090        }
091    
092        /**
093         * An enumeration to identify whether keys not in the MapMessage should be added or whether only existing
094         * keys should be updated.
095         */
096        public enum Mode {
097            /**
098             * Keys should be added.
099             */
100            Add,
101            /**
102             * Keys should be updated.
103             */
104            Update
105        }
106    
107        @Override
108        public String toString() {
109            final StringBuilder sb = new StringBuilder();
110            sb.append("mode=").append(mode);
111            sb.append(" {");
112            boolean first = true;
113            for (final Map.Entry<String, String> entry : map.entrySet()) {
114                if (!first) {
115                    sb.append(", ");
116                }
117                sb.append(entry.getKey()).append('=').append(entry.getValue());
118                first = false;
119            }
120            sb.append('}');
121            return sb.toString();
122        }
123    
124        /**
125         * The factory method to create the MapRewritePolicy.
126         * @param mode The string representation of the Mode.
127         * @param pairs key/value pairs for the new Map keys and values.
128         * @return The MapRewritePolicy.
129         */
130        @PluginFactory
131        public static MapRewritePolicy createPolicy(
132                @PluginAttribute("mode") final String mode,
133                @PluginElement("KeyValuePair") final KeyValuePair[] pairs) {
134            Mode op;
135            if (mode == null) {
136                op = Mode.Add;
137            } else {
138                op = Mode.valueOf(mode);
139                if (op == null) {
140                    LOGGER.error("Undefined mode " + mode);
141                    return null;
142                }
143            }
144            if (pairs == null || pairs.length == 0) {
145                LOGGER.error("keys and values must be specified for the MapRewritePolicy");
146                return null;
147            }
148            final Map<String, String> map = new HashMap<String, String>();
149            for (final KeyValuePair pair : pairs) {
150                final String key = pair.getKey();
151                if (key == null) {
152                    LOGGER.error("A null key is not valid in MapRewritePolicy");
153                    continue;
154                }
155                final String value = pair.getValue();
156                if (value == null) {
157                    LOGGER.error("A null value for key " + key + " is not allowed in MapRewritePolicy");
158                    continue;
159                }
160                map.put(pair.getKey(), pair.getValue());
161            }
162            if (map.isEmpty()) {
163                LOGGER.error("MapRewritePolicy is not configured with any valid key value pairs");
164                return null;
165            }
166            return new MapRewritePolicy(map, op);
167        }
168    }