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