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.net.JndiManager;
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 AbstractLookup {
036
037    private static final Logger LOGGER = StatusLogger.getLogger();
038
039    /** Constant for the prefix separator. */
040    static final char PREFIX_SEPARATOR = ':';
041
042    private final Map<String, StrLookup> lookups = new HashMap<String, StrLookup>();
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                if (!clazz.getName().equals("org.apache.logging.log4j.core.lookup.JndiLookup")
067                    || JndiManager.isJndiLookupEnabled()) {
068                    lookups.put(entry.getKey().toLowerCase(), ReflectionUtil.instantiate(clazz));
069                }
070            } catch (final Exception ex) {
071                LOGGER.error("Unable to create Lookup for {}", entry.getKey(), ex);
072            }
073        }
074    }
075
076    /**
077     * Create the default Interpolator using only Lookups that work without an event.
078     */
079    public Interpolator() {
080        this((Map<String, String>) null);
081    }
082
083    /**
084     * Creates the Interpolator using only Lookups that work without an event and initial properties.
085     */
086    public Interpolator(final Map<String, String> properties) {
087        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
088        // TODO: this ought to use the PluginManager
089        lookups.put("sys", new SystemPropertiesLookup());
090        lookups.put("env", new EnvironmentLookup());
091        lookups.put("main", MapLookup.MAIN_SINGLETON);
092        lookups.put("java", new JavaLookup());
093        // JNDI
094        if (JndiManager.isJndiLookupEnabled()) {
095            try {
096                // [LOG4J2-703] We might be on Android
097                lookups.put("jndi", Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
098            } catch (final Throwable e) {
099                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
100                LOGGER.warn(
101                    "JNDI lookup class is not available because this JRE does not support JNDI. JNDI string lookups will not be available, continuing configuration.",
102                    e);
103            }
104        }
105        // JMX input args
106        try {
107            // We might be on Android
108            lookups.put("jvmrunargs",
109                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup", StrLookup.class));
110        } catch (final Throwable e) {
111            // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
112            LOGGER.warn(
113                    "JMX runtime input lookup class is not available because this JRE does not support JMX. JMX lookups will not be available, continuing configuration.",
114                    e);
115        }
116        lookups.put("date", new DateLookup());
117        lookups.put("ctx", new ContextMapLookup());
118        if (Loader.isClassAvailable("javax.servlet.ServletContext")) {
119            try {
120                lookups.put("web",
121                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
122            } catch (final Exception ignored) {
123                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
124                    "available. If you want better web container support, please add the log4j-web JAR to your " +
125                    "web archive or server lib directory.");
126            }
127        } else {
128            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
129        }
130    }
131
132    /**
133     * Resolves the specified variable. This implementation will try to extract
134     * a variable prefix from the given variable name (the first colon (':') is
135     * used as prefix separator). It then passes the name of the variable with
136     * the prefix stripped to the lookup object registered for this prefix. If
137     * no prefix can be found or if the associated lookup object cannot resolve
138     * this variable, the default lookup object will be used.
139     *
140     * @param event The current LogEvent or null.
141     * @param var the name of the variable whose value is to be looked up
142     * @return the value of this variable or <b>null</b> if it cannot be
143     * resolved
144     */
145    @Override
146    public String lookup(final LogEvent event, String var) {
147        if (var == null) {
148            return null;
149        }
150
151        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
152        if (prefixPos >= 0) {
153            final String prefix = var.substring(0, prefixPos);
154            final String name = var.substring(prefixPos + 1);
155            final StrLookup lookup = lookups.get(prefix);
156            String value = null;
157            if (lookup != null) {
158                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
159            }
160
161            if (value != null) {
162                return value;
163            }
164            var = var.substring(prefixPos + 1);
165        }
166        if (defaultLookup != null) {
167            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
168        }
169        return null;
170    }
171
172    @Override
173    public String toString() {
174        final StringBuilder sb = new StringBuilder();
175        for (final String name : lookups.keySet()) {
176            if (sb.length() == 0) {
177                sb.append('{');
178            } else {
179                sb.append(", ");
180            }
181
182            sb.append(name);
183        }
184        if (sb.length() > 0) {
185            sb.append('}');
186        }
187        return sb.toString();
188    }
189}