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 String LOOKUP_KEY_WEB = "web";
038
039    private static final String LOOKUP_KEY_JNDI = "jndi";
040
041    private static final String LOOKUP_KEY_JVMRUNARGS = "jvmrunargs";
042
043    private static final Logger LOGGER = StatusLogger.getLogger();
044
045    /** Constant for the prefix separator. */
046    private static final char PREFIX_SEPARATOR = ':';
047
048    private final Map<String, StrLookup> lookups = new HashMap<>();
049
050    private final StrLookup defaultLookup;
051
052    public Interpolator(final StrLookup defaultLookup) {
053        this(defaultLookup, null);
054    }
055
056    /**
057     * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
058     *
059     * @param defaultLookup  the default StrLookup to use as a fallback
060     * @param pluginPackages a list of packages to scan for Lookup plugins
061     * @since 2.1
062     */
063    public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
064        this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
065        final PluginManager manager = new PluginManager(CATEGORY);
066        manager.collectPlugins(pluginPackages);
067        final Map<String, PluginType<?>> plugins = manager.getPlugins();
068
069        for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
070            try {
071                final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
072                lookups.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
073            } catch (final Throwable t) {
074                handleError(entry.getKey(), t);
075            }
076        }
077    }
078
079    /**
080     * Create the default Interpolator using only Lookups that work without an event.
081     */
082    public Interpolator() {
083        this((Map<String, String>) null);
084    }
085
086    /**
087     * Creates the Interpolator using only Lookups that work without an event and initial properties.
088     */
089    public Interpolator(final Map<String, String> properties) {
090        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
091        // TODO: this ought to use the PluginManager
092        lookups.put("log4j", new Log4jLookup());
093        lookups.put("sys", new SystemPropertiesLookup());
094        lookups.put("env", new EnvironmentLookup());
095        lookups.put("main", MainMapLookup.MAIN_SINGLETON);
096        lookups.put("marker", new MarkerLookup());
097        lookups.put("java", new JavaLookup());
098        // JNDI
099        try {
100            // [LOG4J2-703] We might be on Android
101            lookups.put(LOOKUP_KEY_JNDI,
102                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
103        } catch (final LinkageError | Exception e) {
104            handleError(LOOKUP_KEY_JNDI, e);
105        }
106        // JMX input args
107        try {
108            // We might be on Android
109            lookups.put(LOOKUP_KEY_JVMRUNARGS,
110                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup",
111                        StrLookup.class));
112        } catch (final LinkageError | Exception e) {
113            handleError(LOOKUP_KEY_JVMRUNARGS, e);
114        }
115        lookups.put("date", new DateLookup());
116        lookups.put("ctx", new ContextMapLookup());
117        if (Loader.isClassAvailable("javax.servlet.ServletContext")) {
118            try {
119                lookups.put(LOOKUP_KEY_WEB,
120                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
121            } catch (final Exception ignored) {
122                handleError(LOOKUP_KEY_WEB, ignored);
123            }
124        } else {
125            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
126        }
127    }
128
129    private void handleError(final String lookupKey, final Throwable t) {
130        switch (lookupKey) {
131            case LOOKUP_KEY_JNDI:
132                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
133                LOGGER.warn( // LOG4J2-1582 don't print the whole stack trace (it is just a warning...)
134                        "JNDI lookup class is not available because this JRE does not support JNDI." +
135                        " JNDI string lookups will not be available, continuing configuration. Ignoring " + t);
136                break;
137            case LOOKUP_KEY_JVMRUNARGS:
138                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
139                LOGGER.warn(
140                        "JMX runtime input lookup class is not available because this JRE does not support JMX. " +
141                        "JMX lookups will not be available, continuing configuration. Ignoring " + t);
142                break;
143            case LOOKUP_KEY_WEB:
144                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
145                        "available. If you want better web container support, please add the log4j-web JAR to your " +
146                        "web archive or server lib directory.");
147                break;
148            default:
149                LOGGER.error("Unable to create Lookup for {}", lookupKey, t);
150        }
151    }
152
153    /**
154     * Resolves the specified variable. This implementation will try to extract
155     * a variable prefix from the given variable name (the first colon (':') is
156     * used as prefix separator). It then passes the name of the variable with
157     * the prefix stripped to the lookup object registered for this prefix. If
158     * no prefix can be found or if the associated lookup object cannot resolve
159     * this variable, the default lookup object will be used.
160     *
161     * @param event The current LogEvent or null.
162     * @param var the name of the variable whose value is to be looked up
163     * @return the value of this variable or <b>null</b> if it cannot be
164     * resolved
165     */
166    @Override
167    public String lookup(final LogEvent event, String var) {
168        if (var == null) {
169            return null;
170        }
171
172        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
173        if (prefixPos >= 0) {
174            final String prefix = var.substring(0, prefixPos);
175            final String name = var.substring(prefixPos + 1);
176            final StrLookup lookup = lookups.get(prefix);
177            if (lookup instanceof ConfigurationAware) {
178                ((ConfigurationAware) lookup).setConfiguration(configuration);
179            }
180            String value = null;
181            if (lookup != null) {
182                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
183            }
184
185            if (value != null) {
186                return value;
187            }
188            var = var.substring(prefixPos + 1);
189        }
190        if (defaultLookup != null) {
191            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
192        }
193        return null;
194    }
195
196    @Override
197    public String toString() {
198        final StringBuilder sb = new StringBuilder();
199        for (final String name : lookups.keySet()) {
200            if (sb.length() == 0) {
201                sb.append('{');
202            } else {
203                sb.append(", ");
204            }
205
206            sb.append(name);
207        }
208        if (sb.length() > 0) {
209            sb.append('}');
210        }
211        return sb.toString();
212    }
213}