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.net.JndiManager;
030import org.apache.logging.log4j.core.util.Loader;
031import org.apache.logging.log4j.core.util.ReflectionUtil;
032import org.apache.logging.log4j.status.StatusLogger;
033import org.apache.logging.log4j.util.Constants;
034
035/**
036 * Proxies all the other {@link StrLookup}s.
037 */
038public class Interpolator extends AbstractConfigurationAwareLookup {
039
040    private static final String LOOKUP_KEY_WEB = "web";
041
042    private static final String LOOKUP_KEY_DOCKER = "docker";
043
044    private static final String LOOKUP_KEY_JNDI = "jndi";
045
046    private static final String LOOKUP_KEY_JVMRUNARGS = "jvmrunargs";
047
048    private static final Logger LOGGER = StatusLogger.getLogger();
049
050    /** Constant for the prefix separator. */
051    static final char PREFIX_SEPARATOR = ':';
052
053    private final Map<String, StrLookup> strLookupMap = new HashMap<>();
054
055    private final StrLookup defaultLookup;
056
057    public Interpolator(final StrLookup defaultLookup) {
058        this(defaultLookup, null);
059    }
060
061    /**
062     * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
063     *
064     * @param defaultLookup  the default StrLookup to use as a fallback
065     * @param pluginPackages a list of packages to scan for Lookup plugins
066     * @since 2.1
067     */
068    public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
069        this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
070        final PluginManager manager = new PluginManager(CATEGORY);
071        manager.collectPlugins(pluginPackages);
072        final Map<String, PluginType<?>> plugins = manager.getPlugins();
073
074        for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
075            try {
076                final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
077                if (!clazz.getName().equals("org.apache.logging.log4j.core.lookup.JndiLookup") || JndiManager.isJndiLookupEnabled()) {
078                    strLookupMap.put(entry.getKey().toLowerCase(), ReflectionUtil.instantiate(clazz));
079                }
080            } catch (final Throwable t) {
081                handleError(entry.getKey(), t);
082            }
083        }
084    }
085
086    /**
087     * Create the default Interpolator using only Lookups that work without an event.
088     */
089    public Interpolator() {
090        this((Map<String, String>) null);
091    }
092
093    /**
094     * Creates the Interpolator using only Lookups that work without an event and initial properties.
095     */
096    public Interpolator(final Map<String, String> properties) {
097        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
098        // TODO: this ought to use the PluginManager
099        strLookupMap.put("log4j", new Log4jLookup());
100        strLookupMap.put("sys", new SystemPropertiesLookup());
101        strLookupMap.put("env", new EnvironmentLookup());
102        strLookupMap.put("main", MainMapLookup.MAIN_SINGLETON);
103        strLookupMap.put("marker", new MarkerLookup());
104        strLookupMap.put("java", new JavaLookup());
105        // JNDI
106        if (JndiManager.isJndiLookupEnabled()) {
107            try {
108                // [LOG4J2-703] We might be on Android
109                strLookupMap.put(LOOKUP_KEY_JNDI,
110                        Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
111            } catch (final LinkageError | Exception e) {
112                handleError(LOOKUP_KEY_JNDI, e);
113            }
114        }
115        // JMX input args
116        try {
117            // We might be on Android
118            strLookupMap.put(LOOKUP_KEY_JVMRUNARGS,
119                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup",
120                        StrLookup.class));
121        } catch (final LinkageError | Exception e) {
122            handleError(LOOKUP_KEY_JVMRUNARGS, e);
123        }
124        strLookupMap.put("date", new DateLookup());
125        strLookupMap.put("ctx", new ContextMapLookup());
126        if (Constants.IS_WEB_APP) {
127            try {
128                strLookupMap.put(LOOKUP_KEY_WEB,
129                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
130            } catch (final Exception ignored) {
131                handleError(LOOKUP_KEY_WEB, ignored);
132            }
133        } else {
134            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
135        }
136        try {
137            strLookupMap.put(LOOKUP_KEY_DOCKER,
138                Loader.newCheckedInstanceOf("org.apache.logging.log4j.docker.DockerLookup", StrLookup.class));
139        } catch (final Exception ignored) {
140            handleError(LOOKUP_KEY_DOCKER, ignored);
141        }
142    }
143
144    public Map<String, StrLookup> getStrLookupMap() {
145        return strLookupMap;
146    }
147
148    private void handleError(final String lookupKey, final Throwable t) {
149        switch (lookupKey) {
150            case LOOKUP_KEY_JNDI:
151                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
152                LOGGER.warn( // LOG4J2-1582 don't print the whole stack trace (it is just a warning...)
153                        "JNDI lookup class is not available because this JRE does not support JNDI." +
154                        " JNDI string lookups will not be available, continuing configuration. Ignoring " + t);
155                break;
156            case LOOKUP_KEY_JVMRUNARGS:
157                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
158                LOGGER.warn(
159                        "JMX runtime input lookup class is not available because this JRE does not support JMX. " +
160                        "JMX lookups will not be available, continuing configuration. Ignoring " + t);
161                break;
162            case LOOKUP_KEY_WEB:
163                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
164                        "available. If you want better web container support, please add the log4j-web JAR to your " +
165                        "web archive or server lib directory.");
166                break;
167            case LOOKUP_KEY_DOCKER:
168                break;
169            default:
170                LOGGER.error("Unable to create Lookup for {}", lookupKey, t);
171        }
172    }
173
174    /**
175     * Resolves the specified variable. This implementation will try to extract
176     * a variable prefix from the given variable name (the first colon (':') is
177     * used as prefix separator). It then passes the name of the variable with
178     * the prefix stripped to the lookup object registered for this prefix. If
179     * no prefix can be found or if the associated lookup object cannot resolve
180     * this variable, the default lookup object will be used.
181     *
182     * @param event The current LogEvent or null.
183     * @param var the name of the variable whose value is to be looked up
184     * @return the value of this variable or <b>null</b> if it cannot be
185     * resolved
186     */
187    @Override
188    public String lookup(final LogEvent event, String var) {
189        if (var == null) {
190            return null;
191        }
192
193        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
194        if (prefixPos >= 0) {
195            final String prefix = var.substring(0, prefixPos).toLowerCase(Locale.US);
196            final String name = var.substring(prefixPos + 1);
197            final StrLookup lookup = strLookupMap.get(prefix);
198            if (lookup instanceof ConfigurationAware) {
199                ((ConfigurationAware) lookup).setConfiguration(configuration);
200            }
201            String value = null;
202            if (lookup != null) {
203                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
204            }
205
206            if (value != null) {
207                return value;
208            }
209            var = var.substring(prefixPos + 1);
210        }
211        if (defaultLookup != null) {
212            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
213        }
214        return null;
215    }
216
217    @Override
218    public String toString() {
219        final StringBuilder sb = new StringBuilder();
220        for (final String name : strLookupMap.keySet()) {
221            if (sb.length() == 0) {
222                sb.append('{');
223            } else {
224                sb.append(", ");
225            }
226
227            sb.append(name);
228        }
229        if (sb.length() > 0) {
230            sb.append('}');
231        }
232        return sb.toString();
233    }
234
235}