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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache license, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License. You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the license for the specific language governing permissions and
15   * limitations under the license.
16   */
17  package org.apache.logging.log4j.core.appender.rewrite;
18  
19  import org.apache.logging.log4j.Logger;
20  import org.apache.logging.log4j.core.LogEvent;
21  import org.apache.logging.log4j.core.config.plugins.Plugin;
22  import org.apache.logging.log4j.core.config.plugins.PluginAttr;
23  import org.apache.logging.log4j.core.config.plugins.PluginElement;
24  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
25  import org.apache.logging.log4j.core.helpers.KeyValuePair;
26  import org.apache.logging.log4j.core.impl.Log4jLogEvent;
27  import org.apache.logging.log4j.message.MapMessage;
28  import org.apache.logging.log4j.message.Message;
29  import org.apache.logging.log4j.status.StatusLogger;
30  
31  import java.util.HashMap;
32  import java.util.Map;
33  
34  /**
35   * This policy modifies events by replacing or possibly adding keys and values to the MapMessage.
36   */
37  @Plugin(name = "MapRewritePolicy", category = "Core", elementType = "rewritePolicy", printObject = true)
38  public final class MapRewritePolicy implements RewritePolicy {
39      /**
40       * Allow subclasses access to the status logger without creating another instance.
41       */
42      protected static final Logger LOGGER = StatusLogger.getLogger();
43  
44      private final Map<String, String> map;
45  
46      private final Mode mode;
47  
48      private MapRewritePolicy(final Map<String, String> map, final Mode mode) {
49          this.map = map;
50          this.mode = mode;
51      }
52  
53      /**
54       * Rewrite the event.
55       * @param source a logging event that may be returned or
56       * used to create a new logging event.
57       * @return The LogEvent after rewriting.
58       */
59      @Override
60      public LogEvent rewrite(final LogEvent source) {
61          final Message msg = source.getMessage();
62          if (msg == null || !(msg instanceof MapMessage)) {
63              return source;
64          }
65  
66          final Map<String, String> newMap = new HashMap<String, String>(((MapMessage) msg).getData());
67          switch (mode) {
68              case Add: {
69                  newMap.putAll(map);
70                  break;
71              }
72              default: {
73                  for (final Map.Entry<String, String> entry : map.entrySet()) {
74                      if (newMap.containsKey(entry.getKey())) {
75                          newMap.put(entry.getKey(), entry.getValue());
76                      }
77                  }
78              }
79          }
80          final MapMessage message = ((MapMessage) msg).newInstance(newMap);
81          return new Log4jLogEvent(source.getLoggerName(), source.getMarker(), source.getFQCN(), source.getLevel(),
82              message, source.getThrown(), source.getContextMap(), source.getContextStack(), source.getThreadName(),
83              source.getSource(), source.getMillis());
84      }
85  
86      /**
87       * An enumeration to identify whether keys not in the MapMessage should be added or whether only existing
88       * keys should be updated.
89       */
90      public enum Mode {
91          /**
92           * Keys should be added.
93           */
94          Add,
95          /**
96           * Keys should be updated.
97           */
98          Update
99      }
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 }