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 */
017
018package org.apache.logging.log4j.core.config.plugins.util;
019
020import java.lang.annotation.Annotation;
021import java.lang.reflect.AccessibleObject;
022import java.lang.reflect.Field;
023import java.lang.reflect.InvocationTargetException;
024import java.lang.reflect.Method;
025import java.lang.reflect.Modifier;
026import java.util.Collection;
027import java.util.List;
028import java.util.Map;
029import java.util.Objects;
030
031import org.apache.logging.log4j.Logger;
032import org.apache.logging.log4j.core.LogEvent;
033import org.apache.logging.log4j.core.config.Configuration;
034import org.apache.logging.log4j.core.config.ConfigurationException;
035import org.apache.logging.log4j.core.config.Node;
036import org.apache.logging.log4j.core.config.plugins.PluginAliases;
037import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
038import org.apache.logging.log4j.core.config.plugins.PluginFactory;
039import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidator;
040import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidators;
041import org.apache.logging.log4j.core.config.plugins.visitors.PluginVisitor;
042import org.apache.logging.log4j.core.config.plugins.visitors.PluginVisitors;
043import org.apache.logging.log4j.core.util.Builder;
044import org.apache.logging.log4j.core.util.ReflectionUtil;
045import org.apache.logging.log4j.core.util.TypeUtil;
046import org.apache.logging.log4j.status.StatusLogger;
047import org.apache.logging.log4j.util.StringBuilders;
048
049/**
050 * Builder class to instantiate and configure a Plugin object using a PluginFactory method or PluginBuilderFactory
051 * builder class.
052 */
053public class PluginBuilder implements Builder<Object> {
054
055    private static final Logger LOGGER = StatusLogger.getLogger();
056
057    private final PluginType<?> pluginType;
058    private final Class<?> clazz;
059
060    private Configuration configuration;
061    private Node node;
062    private LogEvent event;
063
064    /**
065     * Constructs a PluginBuilder for a given PluginType.
066     *
067     * @param pluginType type of plugin to configure
068     */
069    public PluginBuilder(final PluginType<?> pluginType) {
070        this.pluginType = pluginType;
071        this.clazz = pluginType.getPluginClass();
072    }
073
074    /**
075     * Specifies the Configuration to use for constructing the plugin instance.
076     *
077     * @param configuration the configuration to use.
078     * @return {@code this}
079     */
080    public PluginBuilder withConfiguration(final Configuration configuration) {
081        this.configuration = configuration;
082        return this;
083    }
084
085    /**
086     * Specifies the Node corresponding to the plugin object that will be created.
087     *
088     * @param node the plugin configuration node to use.
089     * @return {@code this}
090     */
091    public PluginBuilder withConfigurationNode(final Node node) {
092        this.node = node;
093        return this;
094    }
095
096    /**
097     * Specifies the LogEvent that may be used to provide extra context for string substitutions.
098     *
099     * @param event the event to use for extra information.
100     * @return {@code this}
101     */
102    public PluginBuilder forLogEvent(final LogEvent event) {
103        this.event = event;
104        return this;
105    }
106
107    /**
108     * Builds the plugin object.
109     *
110     * @return the plugin object or {@code null} if there was a problem creating it.
111     */
112    @Override
113    public Object build() {
114        verify();
115        // first try to use a builder class if one is available
116        try {
117            LOGGER.debug("Building Plugin[name={}, class={}]. Searching for builder factory method...", pluginType.getElementName(),
118                    pluginType.getPluginClass().getName());
119            final Builder<?> builder = createBuilder(this.clazz);
120            if (builder != null) {
121                injectFields(builder);
122                final Object result = builder.build();
123                LOGGER.debug("Built Plugin[name={}] OK from builder factory method.", pluginType.getElementName());
124                return result;
125            }
126        } catch (final Exception e) {
127            LOGGER.error("Unable to inject fields into builder class for plugin type {}, element {}.", this.clazz,
128                node.getName(), e);
129        }
130        // or fall back to factory method if no builder class is available
131        try {
132            LOGGER.debug("Still building Plugin[name={}, class={}]. Searching for factory method...",
133                    pluginType.getElementName(), pluginType.getPluginClass().getName());
134            final Method factory = findFactoryMethod(this.clazz);
135            final Object[] params = generateParameters(factory);
136            final Object plugin = factory.invoke(null, params);
137            LOGGER.debug("Built Plugin[name={}] OK from factory method.", pluginType.getElementName());
138            return plugin;
139        } catch (final Exception e) {
140            LOGGER.error("Unable to invoke factory method in class {} for element {}.", this.clazz, this.node.getName(),
141                e);
142            return null;
143        }
144    }
145
146    private void verify() {
147        Objects.requireNonNull(this.configuration, "No Configuration object was set.");
148        Objects.requireNonNull(this.node, "No Node object was set.");
149    }
150
151    private static Builder<?> createBuilder(final Class<?> clazz)
152        throws InvocationTargetException, IllegalAccessException {
153        for (final Method method : clazz.getDeclaredMethods()) {
154            if (method.isAnnotationPresent(PluginBuilderFactory.class) &&
155                Modifier.isStatic(method.getModifiers()) &&
156                TypeUtil.isAssignable(Builder.class, method.getGenericReturnType())) {
157                ReflectionUtil.makeAccessible(method);
158                @SuppressWarnings("unchecked")
159                final Builder<?> builder = (Builder<?>) method.invoke(null);
160                LOGGER.debug("Found builder factory method [{}]: {}.", method.getName(), method);
161                return builder;
162            }
163        }
164        LOGGER.debug("No builder factory method found in class {}. Going to try finding a factory method instead.",
165            clazz.getName());
166        return null;
167    }
168
169    private void injectFields(final Builder<?> builder) throws IllegalAccessException {
170        final Field[] fields = builder.getClass().getDeclaredFields();
171        AccessibleObject.setAccessible(fields, true);
172        final StringBuilder log = new StringBuilder();
173        boolean invalid = false;
174        for (final Field field : fields) {
175            log.append(log.length() == 0 ? "with params(" : ", ");
176            final Annotation[] annotations = field.getDeclaredAnnotations();
177            final String[] aliases = extractPluginAliases(annotations);
178            for (final Annotation a : annotations) {
179                if (a instanceof PluginAliases) {
180                    continue; // already processed
181                }
182                final PluginVisitor<? extends Annotation> visitor =
183                    PluginVisitors.findVisitor(a.annotationType());
184                if (visitor != null) {
185                    final Object value = visitor.setAliases(aliases)
186                        .setAnnotation(a)
187                        .setConversionType(field.getType())
188                        .setStrSubstitutor(configuration.getStrSubstitutor())
189                        .setMember(field)
190                        .visit(configuration, node, event, log);
191                    // don't overwrite default values if the visitor gives us no value to inject
192                    if (value != null) {
193                        field.set(builder, value);
194                    }
195                }
196            }
197            final Collection<ConstraintValidator<?>> validators =
198                ConstraintValidators.findValidators(annotations);
199            final Object value = field.get(builder);
200            for (final ConstraintValidator<?> validator : validators) {
201                if (!validator.isValid(value)) {
202                    invalid = true;
203                }
204            }
205        }
206        if (log.length() > 0) {
207            log.append(')');
208        }
209        LOGGER.debug("Calling build() on class {} for element {} {}", builder.getClass(), node.getName(),
210            log.toString());
211        if (invalid) {
212            throw new ConfigurationException("Arguments given for element " + node.getName() + " are invalid");
213        }
214        checkForRemainingAttributes();
215        verifyNodeChildrenUsed();
216    }
217
218    private static Method findFactoryMethod(final Class<?> clazz) {
219        for (final Method method : clazz.getDeclaredMethods()) {
220            if (method.isAnnotationPresent(PluginFactory.class) &&
221                Modifier.isStatic(method.getModifiers())) {
222                LOGGER.debug("Found factory method [{}]: {}.", method.getName(), method);
223                ReflectionUtil.makeAccessible(method);
224                return method;
225            }
226        }
227        throw new IllegalStateException("No factory method found for class " + clazz.getName());
228    }
229
230    private Object[] generateParameters(final Method factory) {
231        final StringBuilder log = new StringBuilder();
232        final Class<?>[] types = factory.getParameterTypes();
233        final Annotation[][] annotations = factory.getParameterAnnotations();
234        final Object[] args = new Object[annotations.length];
235        boolean invalid = false;
236        for (int i = 0; i < annotations.length; i++) {
237            log.append(log.length() == 0 ? "with params(" : ", ");
238            final String[] aliases = extractPluginAliases(annotations[i]);
239            for (final Annotation a : annotations[i]) {
240                if (a instanceof PluginAliases) {
241                    continue; // already processed
242                }
243                final PluginVisitor<? extends Annotation> visitor = PluginVisitors.findVisitor(
244                    a.annotationType());
245                if (visitor != null) {
246                    final Object value = visitor.setAliases(aliases)
247                        .setAnnotation(a)
248                        .setConversionType(types[i])
249                        .setStrSubstitutor(configuration.getStrSubstitutor())
250                        .setMember(factory)
251                        .visit(configuration, node, event, log);
252                    // don't overwrite existing values if the visitor gives us no value to inject
253                    if (value != null) {
254                        args[i] = value;
255                    }
256                }
257            }
258            final Collection<ConstraintValidator<?>> validators =
259                ConstraintValidators.findValidators(annotations[i]);
260            final Object value = args[i];
261            for (final ConstraintValidator<?> validator : validators) {
262                if (!validator.isValid(value)) {
263                    invalid = true;
264                }
265            }
266        }
267        if (log.length() > 0) {
268            log.append(')');
269        }
270        checkForRemainingAttributes();
271        verifyNodeChildrenUsed();
272        LOGGER.debug("Calling {} on class {} for element {} {}", factory.getName(), clazz.getName(), node.getName(),
273            log.toString());
274        if (invalid) {
275            throw new ConfigurationException("Arguments given for element " + node.getName() + " are invalid");
276        }
277        return args;
278    }
279
280    private static String[] extractPluginAliases(final Annotation... parmTypes) {
281        String[] aliases = null;
282        for (final Annotation a : parmTypes) {
283            if (a instanceof PluginAliases) {
284                aliases = ((PluginAliases) a).value();
285            }
286        }
287        return aliases;
288    }
289
290    private void checkForRemainingAttributes() {
291        final Map<String, String> attrs = node.getAttributes();
292        if (!attrs.isEmpty()) {
293            final StringBuilder sb = new StringBuilder();
294            for (final String key : attrs.keySet()) {
295                if (sb.length() == 0) {
296                    sb.append(node.getName());
297                    sb.append(" contains ");
298                    if (attrs.size() == 1) {
299                        sb.append("an invalid element or attribute ");
300                    } else {
301                        sb.append("invalid attributes ");
302                    }
303                } else {
304                    sb.append(", ");
305                }
306                StringBuilders.appendDqValue(sb, key);
307            }
308            LOGGER.error(sb.toString());
309        }
310    }
311
312    private void verifyNodeChildrenUsed() {
313        final List<Node> children = node.getChildren();
314        if (!(pluginType.isDeferChildren() || children.isEmpty())) {
315            for (final Node child : children) {
316                final String nodeType = node.getType().getElementName();
317                final String start = nodeType.equals(node.getName()) ? node.getName() : nodeType + ' ' + node.getName();
318                LOGGER.error("{} has no parameter that matches element {}", start, child.getName());
319            }
320        }
321    }
322}