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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.lookup;
18  
19  import java.util.HashMap;
20  import java.util.List;
21  import java.util.Locale;
22  import java.util.Map;
23  
24  import org.apache.logging.log4j.Logger;
25  import org.apache.logging.log4j.core.LogEvent;
26  import org.apache.logging.log4j.core.config.ConfigurationAware;
27  import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
28  import org.apache.logging.log4j.core.config.plugins.util.PluginType;
29  import org.apache.logging.log4j.core.util.Loader;
30  import org.apache.logging.log4j.core.util.ReflectionUtil;
31  import org.apache.logging.log4j.status.StatusLogger;
32  import org.apache.logging.log4j.util.Constants;
33  
34  /**
35   * Proxies all the other {@link StrLookup}s.
36   */
37  public class Interpolator extends AbstractConfigurationAwareLookup {
38  
39      private static final String LOOKUP_KEY_WEB = "web";
40  
41      private static final String LOOKUP_KEY_JNDI = "jndi";
42  
43      private static final String LOOKUP_KEY_JVMRUNARGS = "jvmrunargs";
44  
45      private static final Logger LOGGER = StatusLogger.getLogger();
46  
47      /** Constant for the prefix separator. */
48      private static final char PREFIX_SEPARATOR = ':';
49  
50      private final Map<String, StrLookup> strLookupMap = new HashMap<>();
51  
52      private final StrLookup defaultLookup;
53  
54      public Interpolator(final StrLookup defaultLookup) {
55          this(defaultLookup, null);
56      }
57  
58      /**
59       * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
60       *
61       * @param defaultLookup  the default StrLookup to use as a fallback
62       * @param pluginPackages a list of packages to scan for Lookup plugins
63       * @since 2.1
64       */
65      public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
66          this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
67          final PluginManager manager = new PluginManager(CATEGORY);
68          manager.collectPlugins(pluginPackages);
69          final Map<String, PluginType<?>> plugins = manager.getPlugins();
70  
71          for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
72              try {
73                  final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
74                  strLookupMap.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
75              } catch (final Throwable t) {
76                  handleError(entry.getKey(), t);
77              }
78          }
79      }
80  
81      /**
82       * Create the default Interpolator using only Lookups that work without an event.
83       */
84      public Interpolator() {
85          this((Map<String, String>) null);
86      }
87  
88      /**
89       * Creates the Interpolator using only Lookups that work without an event and initial properties.
90       */
91      public Interpolator(final Map<String, String> properties) {
92          this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
93          // TODO: this ought to use the PluginManager
94          strLookupMap.put("log4j", new Log4jLookup());
95          strLookupMap.put("sys", new SystemPropertiesLookup());
96          strLookupMap.put("env", new EnvironmentLookup());
97          strLookupMap.put("main", MainMapLookup.MAIN_SINGLETON);
98          strLookupMap.put("marker", new MarkerLookup());
99          strLookupMap.put("java", new JavaLookup());
100         // JNDI
101         try {
102             // [LOG4J2-703] We might be on Android
103             strLookupMap.put(LOOKUP_KEY_JNDI,
104                 Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
105         } catch (final LinkageError | Exception e) {
106             handleError(LOOKUP_KEY_JNDI, e);
107         }
108         // JMX input args
109         try {
110             // We might be on Android
111             strLookupMap.put(LOOKUP_KEY_JVMRUNARGS,
112                 Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup",
113                         StrLookup.class));
114         } catch (final LinkageError | Exception e) {
115             handleError(LOOKUP_KEY_JVMRUNARGS, e);
116         }
117         strLookupMap.put("date", new DateLookup());
118         strLookupMap.put("ctx", new ContextMapLookup());
119         if (Constants.IS_WEB_APP) {
120             try {
121                 strLookupMap.put(LOOKUP_KEY_WEB,
122                     Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
123             } catch (final Exception ignored) {
124                 handleError(LOOKUP_KEY_WEB, ignored);
125             }
126         } else {
127             LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
128         }
129     }
130 
131     public Map<String, StrLookup> getStrLookupMap() {
132         return strLookupMap;
133     }
134 
135     private void handleError(final String lookupKey, final Throwable t) {
136         switch (lookupKey) {
137             case LOOKUP_KEY_JNDI:
138                 // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
139                 LOGGER.warn( // LOG4J2-1582 don't print the whole stack trace (it is just a warning...)
140                         "JNDI lookup class is not available because this JRE does not support JNDI." +
141                         " JNDI string lookups will not be available, continuing configuration. Ignoring " + t);
142                 break;
143             case LOOKUP_KEY_JVMRUNARGS:
144                 // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
145                 LOGGER.warn(
146                         "JMX runtime input lookup class is not available because this JRE does not support JMX. " +
147                         "JMX lookups will not be available, continuing configuration. Ignoring " + t);
148                 break;
149             case LOOKUP_KEY_WEB:
150                 LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
151                         "available. If you want better web container support, please add the log4j-web JAR to your " +
152                         "web archive or server lib directory.");
153                 break;
154             default:
155                 LOGGER.error("Unable to create Lookup for {}", lookupKey, t);
156         }
157     }
158 
159     /**
160      * Resolves the specified variable. This implementation will try to extract
161      * a variable prefix from the given variable name (the first colon (':') is
162      * used as prefix separator). It then passes the name of the variable with
163      * the prefix stripped to the lookup object registered for this prefix. If
164      * no prefix can be found or if the associated lookup object cannot resolve
165      * this variable, the default lookup object will be used.
166      *
167      * @param event The current LogEvent or null.
168      * @param var the name of the variable whose value is to be looked up
169      * @return the value of this variable or <b>null</b> if it cannot be
170      * resolved
171      */
172     @Override
173     public String lookup(final LogEvent event, String var) {
174         if (var == null) {
175             return null;
176         }
177 
178         final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
179         if (prefixPos >= 0) {
180             final String prefix = var.substring(0, prefixPos).toLowerCase(Locale.US);
181             final String name = var.substring(prefixPos + 1);
182             final StrLookup lookup = strLookupMap.get(prefix);
183             if (lookup instanceof ConfigurationAware) {
184                 ((ConfigurationAware) lookup).setConfiguration(configuration);
185             }
186             String value = null;
187             if (lookup != null) {
188                 value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
189             }
190 
191             if (value != null) {
192                 return value;
193             }
194             var = var.substring(prefixPos + 1);
195         }
196         if (defaultLookup != null) {
197             return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
198         }
199         return null;
200     }
201 
202     @Override
203     public String toString() {
204         final StringBuilder sb = new StringBuilder();
205         for (final String name : strLookupMap.keySet()) {
206             if (sb.length() == 0) {
207                 sb.append('{');
208             } else {
209                 sb.append(", ");
210             }
211 
212             sb.append(name);
213         }
214         if (sb.length() > 0) {
215             sb.append('}');
216         }
217         return sb.toString();
218     }
219 
220 }