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 */
017package org.apache.logging.log4j.core.lookup;
018
019import java.util.HashMap;
020import java.util.List;
021import java.util.Map;
022
023import org.apache.logging.log4j.Logger;
024import org.apache.logging.log4j.core.LogEvent;
025import org.apache.logging.log4j.core.config.ConfigurationAware;
026import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
027import org.apache.logging.log4j.core.config.plugins.util.PluginType;
028import org.apache.logging.log4j.core.util.Loader;
029import org.apache.logging.log4j.core.util.ReflectionUtil;
030import org.apache.logging.log4j.status.StatusLogger;
031
032/**
033 * Proxies all the other {@link StrLookup}s.
034 */
035public class Interpolator extends AbstractConfigurationAwareLookup {
036
037    private static final Logger LOGGER = StatusLogger.getLogger();
038
039    /** Constant for the prefix separator. */
040    private static final char PREFIX_SEPARATOR = ':';
041
042    private final Map<String, StrLookup> lookups = new HashMap<>();
043
044    private final StrLookup defaultLookup;
045
046    public Interpolator(final StrLookup defaultLookup) {
047        this(defaultLookup, null);
048    }
049
050    /**
051     * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
052     *
053     * @param defaultLookup  the default StrLookup to use as a fallback
054     * @param pluginPackages a list of packages to scan for Lookup plugins
055     * @since 2.1
056     */
057    public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
058        this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
059        final PluginManager manager = new PluginManager(CATEGORY);
060        manager.collectPlugins(pluginPackages);
061        final Map<String, PluginType<?>> plugins = manager.getPlugins();
062
063        for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
064            try {
065                final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
066                lookups.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
067            } catch (final Exception ex) {
068                LOGGER.error("Unable to create Lookup for {}", entry.getKey(), ex);
069            }
070        }
071    }
072
073    /**
074     * Create the default Interpolator using only Lookups that work without an event.
075     */
076    public Interpolator() {
077        this((Map<String, String>) null);
078    }
079
080    /**
081     * Creates the Interpolator using only Lookups that work without an event and initial properties.
082     */
083    public Interpolator(final Map<String, String> properties) {
084        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
085        // TODO: this ought to use the PluginManager
086        lookups.put("log4j", new Log4jLookup());
087        lookups.put("sys", new SystemPropertiesLookup());
088        lookups.put("env", new EnvironmentLookup());
089        lookups.put("main", MainMapLookup.MAIN_SINGLETON);
090        lookups.put("marker", new MarkerLookup());
091        lookups.put("java", new JavaLookup());
092        // JNDI
093        try {
094            // [LOG4J2-703] We might be on Android
095            lookups.put("jndi",
096                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
097        } catch (final Throwable e) {
098            // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
099            LOGGER.warn(
100                    "JNDI lookup class is not available because this JRE does not support JNDI. JNDI string lookups will not be available, continuing configuration.",
101                    e);
102        }
103        // JMX input args
104        try {
105            // We might be on Android
106            lookups.put("jvmrunargs",
107                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup", StrLookup.class));
108        } catch (final Throwable e) {
109            // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
110            LOGGER.warn(
111                    "JMX runtime input lookup class is not available because this JRE does not support JMX. JMX lookups will not be available, continuing configuration.",
112                    e);
113        }
114        lookups.put("date", new DateLookup());
115        lookups.put("ctx", new ContextMapLookup());
116        if (Loader.isClassAvailable("javax.servlet.ServletContext")) {
117            try {
118                lookups.put("web",
119                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
120            } catch (final Exception ignored) {
121                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
122                    "available. If you want better web container support, please add the log4j-web JAR to your " +
123                    "web archive or server lib directory.");
124            }
125        } else {
126            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
127        }
128    }
129
130    /**
131     * Resolves the specified variable. This implementation will try to extract
132     * a variable prefix from the given variable name (the first colon (':') is
133     * used as prefix separator). It then passes the name of the variable with
134     * the prefix stripped to the lookup object registered for this prefix. If
135     * no prefix can be found or if the associated lookup object cannot resolve
136     * this variable, the default lookup object will be used.
137     *
138     * @param event The current LogEvent or null.
139     * @param var the name of the variable whose value is to be looked up
140     * @return the value of this variable or <b>null</b> if it cannot be
141     * resolved
142     */
143    @Override
144    public String lookup(final LogEvent event, String var) {
145        if (var == null) {
146            return null;
147        }
148
149        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
150        if (prefixPos >= 0) {
151            final String prefix = var.substring(0, prefixPos);
152            final String name = var.substring(prefixPos + 1);
153            final StrLookup lookup = lookups.get(prefix);
154            if (lookup instanceof ConfigurationAware) {
155                ((ConfigurationAware) lookup).setConfiguration(configuration);
156            }
157            String value = null;
158            if (lookup != null) {
159                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
160            }
161
162            if (value != null) {
163                return value;
164            }
165            var = var.substring(prefixPos + 1);
166        }
167        if (defaultLookup != null) {
168            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
169        }
170        return null;
171    }
172
173    @Override
174    public String toString() {
175        final StringBuilder sb = new StringBuilder();
176        for (final String name : lookups.keySet()) {
177            if (sb.length() == 0) {
178                sb.append('{');
179            } else {
180                sb.append(", ");
181            }
182
183            sb.append(name);
184        }
185        if (sb.length() > 0) {
186            sb.append('}');
187        }
188        return sb.toString();
189    }
190}