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.Locale;
022import java.util.Map;
023
024import org.apache.logging.log4j.Logger;
025import org.apache.logging.log4j.core.LogEvent;
026import org.apache.logging.log4j.core.config.ConfigurationAware;
027import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
028import org.apache.logging.log4j.core.config.plugins.util.PluginType;
029import org.apache.logging.log4j.core.util.Loader;
030import org.apache.logging.log4j.core.util.ReflectionUtil;
031import org.apache.logging.log4j.status.StatusLogger;
032
033/**
034 * Proxies all the other {@link StrLookup}s.
035 */
036public class Interpolator extends AbstractConfigurationAwareLookup {
037
038    private static final String LOOKUP_KEY_WEB = "web";
039
040    private static final String LOOKUP_KEY_JNDI = "jndi";
041
042    private static final String LOOKUP_KEY_JVMRUNARGS = "jvmrunargs";
043
044    private static final Logger LOGGER = StatusLogger.getLogger();
045
046    /** Constant for the prefix separator. */
047    private static final char PREFIX_SEPARATOR = ':';
048
049    private final Map<String, StrLookup> lookups = new HashMap<>();
050
051    private final StrLookup defaultLookup;
052
053    public Interpolator(final StrLookup defaultLookup) {
054        this(defaultLookup, null);
055    }
056
057    /**
058     * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
059     *
060     * @param defaultLookup  the default StrLookup to use as a fallback
061     * @param pluginPackages a list of packages to scan for Lookup plugins
062     * @since 2.1
063     */
064    public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
065        this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
066        final PluginManager manager = new PluginManager(CATEGORY);
067        manager.collectPlugins(pluginPackages);
068        final Map<String, PluginType<?>> plugins = manager.getPlugins();
069
070        for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
071            try {
072                final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
073                lookups.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
074            } catch (final Throwable t) {
075                handleError(entry.getKey(), t);
076            }
077        }
078    }
079
080    /**
081     * Create the default Interpolator using only Lookups that work without an event.
082     */
083    public Interpolator() {
084        this((Map<String, String>) null);
085    }
086
087    /**
088     * Creates the Interpolator using only Lookups that work without an event and initial properties.
089     */
090    public Interpolator(final Map<String, String> properties) {
091        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
092        // TODO: this ought to use the PluginManager
093        lookups.put("log4j", new Log4jLookup());
094        lookups.put("sys", new SystemPropertiesLookup());
095        lookups.put("env", new EnvironmentLookup());
096        lookups.put("main", MainMapLookup.MAIN_SINGLETON);
097        lookups.put("marker", new MarkerLookup());
098        lookups.put("java", new JavaLookup());
099        // JNDI
100        try {
101            // [LOG4J2-703] We might be on Android
102            lookups.put(LOOKUP_KEY_JNDI,
103                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
104        } catch (final LinkageError | Exception e) {
105            handleError(LOOKUP_KEY_JNDI, e);
106        }
107        // JMX input args
108        try {
109            // We might be on Android
110            lookups.put(LOOKUP_KEY_JVMRUNARGS,
111                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup",
112                        StrLookup.class));
113        } catch (final LinkageError | Exception e) {
114            handleError(LOOKUP_KEY_JVMRUNARGS, 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(LOOKUP_KEY_WEB,
121                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
122            } catch (final Exception ignored) {
123                handleError(LOOKUP_KEY_WEB, ignored);
124            }
125        } else {
126            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
127        }
128    }
129
130    private void handleError(final String lookupKey, final Throwable t) {
131        switch (lookupKey) {
132            case LOOKUP_KEY_JNDI:
133                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
134                LOGGER.warn( // LOG4J2-1582 don't print the whole stack trace (it is just a warning...)
135                        "JNDI lookup class is not available because this JRE does not support JNDI." +
136                        " JNDI string lookups will not be available, continuing configuration. Ignoring " + t);
137                break;
138            case LOOKUP_KEY_JVMRUNARGS:
139                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
140                LOGGER.warn(
141                        "JMX runtime input lookup class is not available because this JRE does not support JMX. " +
142                        "JMX lookups will not be available, continuing configuration. Ignoring " + t);
143                break;
144            case LOOKUP_KEY_WEB:
145                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
146                        "available. If you want better web container support, please add the log4j-web JAR to your " +
147                        "web archive or server lib directory.");
148                break;
149            default:
150                LOGGER.error("Unable to create Lookup for {}", lookupKey, t);
151        }
152    }
153
154    /**
155     * Resolves the specified variable. This implementation will try to extract
156     * a variable prefix from the given variable name (the first colon (':') is
157     * used as prefix separator). It then passes the name of the variable with
158     * the prefix stripped to the lookup object registered for this prefix. If
159     * no prefix can be found or if the associated lookup object cannot resolve
160     * this variable, the default lookup object will be used.
161     *
162     * @param event The current LogEvent or null.
163     * @param var the name of the variable whose value is to be looked up
164     * @return the value of this variable or <b>null</b> if it cannot be
165     * resolved
166     */
167    @Override
168    public String lookup(final LogEvent event, String var) {
169        if (var == null) {
170            return null;
171        }
172
173        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
174        if (prefixPos >= 0) {
175            final String prefix = var.substring(0, prefixPos).toLowerCase(Locale.US);
176            final String name = var.substring(prefixPos + 1);
177            final StrLookup lookup = lookups.get(prefix);
178            if (lookup instanceof ConfigurationAware) {
179                ((ConfigurationAware) lookup).setConfiguration(configuration);
180            }
181            String value = null;
182            if (lookup != null) {
183                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
184            }
185
186            if (value != null) {
187                return value;
188            }
189            var = var.substring(prefixPos + 1);
190        }
191        if (defaultLookup != null) {
192            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
193        }
194        return null;
195    }
196
197    @Override
198    public String toString() {
199        final StringBuilder sb = new StringBuilder();
200        for (final String name : lookups.keySet()) {
201            if (sb.length() == 0) {
202                sb.append('{');
203            } else {
204                sb.append(", ");
205            }
206
207            sb.append(name);
208        }
209        if (sb.length() > 0) {
210            sb.append('}');
211        }
212        return sb.toString();
213    }
214}