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 org.apache.logging.log4j.Logger;
020    import org.apache.logging.log4j.core.LogEvent;
021    import org.apache.logging.log4j.core.config.plugins.Plugin;
022    import org.apache.logging.log4j.core.config.plugins.PluginAttr;
023    import org.apache.logging.log4j.core.config.plugins.PluginElement;
024    import org.apache.logging.log4j.core.config.plugins.PluginFactory;
025    import org.apache.logging.log4j.core.helpers.KeyValuePair;
026    import org.apache.logging.log4j.core.impl.Log4jLogEvent;
027    import org.apache.logging.log4j.message.MapMessage;
028    import org.apache.logging.log4j.message.Message;
029    import org.apache.logging.log4j.status.StatusLogger;
030    
031    import java.util.HashMap;
032    import java.util.Map;
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            return new Log4jLogEvent(source.getLoggerName(), source.getMarker(), source.getFQCN(), source.getLevel(),
082                message, source.getThrown(), source.getContextMap(), source.getContextStack(), source.getThreadName(),
083                source.getSource(), source.getMillis());
084        }
085    
086        /**
087         * An enumeration to identify whether keys not in the MapMessage should be added or whether only existing
088         * keys should be updated.
089         */
090        public enum Mode {
091            /**
092             * Keys should be added.
093             */
094            Add,
095            /**
096             * Keys should be updated.
097             */
098            Update
099        }
100    
101        @Override
102        public String toString() {
103            final StringBuilder sb = new StringBuilder();
104            sb.append("mode=").append(mode);
105            sb.append(" {");
106            boolean first = true;
107            for (final Map.Entry<String, String> entry : map.entrySet()) {
108                if (!first) {
109                    sb.append(", ");
110                }
111                sb.append(entry.getKey()).append("=").append(entry.getValue());
112                first = false;
113            }
114            sb.append("}");
115            return sb.toString();
116        }
117    
118        /**
119         * The factory method to create the MapRewritePolicy.
120         * @param mode The string representation of the Mode.
121         * @param pairs key/value pairs for the new Map keys and values.
122         * @return The MapRewritePolicy.
123         */
124        @PluginFactory
125        public static MapRewritePolicy createPolicy(@PluginAttr("mode") final String mode,
126                                                    @PluginElement("KeyValuePair") final KeyValuePair[] pairs) {
127            Mode op;
128            if (mode == null) {
129                op = Mode.Add;
130            } else {
131                op = Mode.valueOf(mode);
132                if (op == null) {
133                    LOGGER.error("Undefined mode " + mode);
134                    return null;
135                }
136            }
137            if (pairs == null || pairs.length == 0) {
138                LOGGER.error("keys and values must be specified for the MapRewritePolicy");
139                return null;
140            }
141            final Map<String, String> map = new HashMap<String, String>();
142            for (final KeyValuePair pair : pairs) {
143                final String key = pair.getKey();
144                if (key == null) {
145                    LOGGER.error("A null key is not valid in MapRewritePolicy");
146                    continue;
147                }
148                final String value = pair.getValue();
149                if (value == null) {
150                    LOGGER.error("A null value for key " + key + " is not allowed in MapRewritePolicy");
151                    continue;
152                }
153                map.put(pair.getKey(), pair.getValue());
154            }
155            if (map.size() == 0) {
156                LOGGER.error("MapRewritePolicy is not configured with any valid key value pairs");
157                return null;
158            }
159            return new MapRewritePolicy(map, op);
160        }
161    }