Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.internal.impl.filter;
020
021import javax.inject.Inject;
022import javax.inject.Named;
023import javax.inject.Singleton;
024
025import java.io.BufferedReader;
026import java.io.FileNotFoundException;
027import java.io.IOException;
028import java.io.UncheckedIOException;
029import java.nio.charset.StandardCharsets;
030import java.nio.file.Files;
031import java.nio.file.Path;
032import java.util.ArrayList;
033import java.util.Arrays;
034import java.util.HashMap;
035import java.util.List;
036import java.util.concurrent.ConcurrentHashMap;
037
038import org.eclipse.aether.RepositorySystemSession;
039import org.eclipse.aether.artifact.Artifact;
040import org.eclipse.aether.metadata.Metadata;
041import org.eclipse.aether.repository.RemoteRepository;
042import org.eclipse.aether.spi.connector.filter.RemoteRepositoryFilter;
043import org.eclipse.aether.spi.connector.layout.RepositoryLayout;
044import org.eclipse.aether.spi.connector.layout.RepositoryLayoutProvider;
045import org.eclipse.aether.transfer.NoRepositoryLayoutException;
046import org.slf4j.Logger;
047import org.slf4j.LoggerFactory;
048
049import static java.util.Objects.requireNonNull;
050import static java.util.stream.Collectors.toList;
051
052/**
053 * Remote repository filter source filtering on path prefixes. It is backed by a file that lists all allowed path
054 * prefixes from remote repository. Artifact that layout converted path (using remote repository layout) results in
055 * path with no corresponding prefix present in this file is filtered out.
056 * <p>
057 * The file can be authored manually: format is one prefix per line, comments starting with "#" (hash) and empty lines
058 * for structuring are supported, The "/" (slash) character is used as file separator. Some remote repositories and
059 * MRMs publish these kind of files, they can be downloaded from corresponding URLs.
060 * <p>
061 * The prefix file is expected on path "${basedir}/prefixes-${repository.id}.txt".
062 * <p>
063 * The prefixes file is once loaded and cached, so in-flight prefixes file change during component existence are not
064 * noticed.
065 * <p>
066 * Examples of published prefix files:
067 * <ul>
068 *     <li>Central: <a href="https://repo.maven.apache.org/maven2/.meta/prefixes.txt">prefixes.txt</a></li>
069 *     <li>Apache Releases:
070 *     <a href="https://repository.apache.org/content/repositories/releases/.meta/prefixes.txt">prefixes.txt</a></li>
071 * </ul>
072 *
073 * @since 1.9.0
074 */
075@Singleton
076@Named(PrefixesRemoteRepositoryFilterSource.NAME)
077public final class PrefixesRemoteRepositoryFilterSource extends RemoteRepositoryFilterSourceSupport {
078    public static final String NAME = "prefixes";
079
080    static final String PREFIXES_FILE_PREFIX = "prefixes-";
081
082    static final String PREFIXES_FILE_SUFFIX = ".txt";
083
084    private static final Logger LOGGER = LoggerFactory.getLogger(PrefixesRemoteRepositoryFilterSource.class);
085
086    private final RepositoryLayoutProvider repositoryLayoutProvider;
087
088    private final ConcurrentHashMap<RemoteRepository, Node> prefixes;
089
090    private final ConcurrentHashMap<RemoteRepository, RepositoryLayout> layouts;
091
092    @Inject
093    public PrefixesRemoteRepositoryFilterSource(RepositoryLayoutProvider repositoryLayoutProvider) {
094        super(NAME);
095        this.repositoryLayoutProvider = requireNonNull(repositoryLayoutProvider);
096        this.prefixes = new ConcurrentHashMap<>();
097        this.layouts = new ConcurrentHashMap<>();
098    }
099
100    @Override
101    public RemoteRepositoryFilter getRemoteRepositoryFilter(RepositorySystemSession session) {
102        if (isEnabled(session)) {
103            return new PrefixesFilter(session, getBasedir(session, false));
104        }
105        return null;
106    }
107
108    /**
109     * Caches layout instances for remote repository. In case of unknown layout it returns {@code null}.
110     *
111     * @return the layout instance of {@code null} if layout not supported.
112     */
113    private RepositoryLayout cacheLayout(RepositorySystemSession session, RemoteRepository remoteRepository) {
114        return layouts.computeIfAbsent(remoteRepository, r -> {
115            try {
116                return repositoryLayoutProvider.newRepositoryLayout(session, remoteRepository);
117            } catch (NoRepositoryLayoutException e) {
118                return null;
119            }
120        });
121    }
122
123    /**
124     * Caches prefixes instances for remote repository.
125     */
126    private Node cacheNode(Path basedir, RemoteRepository remoteRepository) {
127        return prefixes.computeIfAbsent(remoteRepository, r -> loadRepositoryPrefixes(basedir, remoteRepository));
128    }
129
130    /**
131     * Loads prefixes file and preprocesses it into {@link Node} instance.
132     */
133    private Node loadRepositoryPrefixes(Path baseDir, RemoteRepository remoteRepository) {
134        Path filePath = baseDir.resolve(PREFIXES_FILE_PREFIX + remoteRepository.getId() + PREFIXES_FILE_SUFFIX);
135        if (Files.isReadable(filePath)) {
136            try (BufferedReader reader = Files.newBufferedReader(filePath, StandardCharsets.UTF_8)) {
137                LOGGER.debug(
138                        "Loading prefixes for remote repository {} from file '{}'", remoteRepository.getId(), filePath);
139                Node root = new Node("");
140                String prefix;
141                int lines = 0;
142                while ((prefix = reader.readLine()) != null) {
143                    if (!prefix.startsWith("#") && !prefix.trim().isEmpty()) {
144                        lines++;
145                        Node currentNode = root;
146                        for (String element : elementsOf(prefix)) {
147                            currentNode = currentNode.addSibling(element);
148                        }
149                    }
150                }
151                LOGGER.info("Loaded {} prefixes for remote repository {}", lines, remoteRepository.getId());
152                return root;
153            } catch (FileNotFoundException e) {
154                // strange: we tested for it above, still, we should not fail
155            } catch (IOException e) {
156                throw new UncheckedIOException(e);
157            }
158        }
159        LOGGER.debug("Prefix file for remote repository {} not found at '{}'", remoteRepository, filePath);
160        return NOT_PRESENT_NODE;
161    }
162
163    private class PrefixesFilter implements RemoteRepositoryFilter {
164        private final RepositorySystemSession session;
165
166        private final Path basedir;
167
168        private PrefixesFilter(RepositorySystemSession session, Path basedir) {
169            this.session = session;
170            this.basedir = basedir;
171        }
172
173        @Override
174        public Result acceptArtifact(RemoteRepository remoteRepository, Artifact artifact) {
175            RepositoryLayout repositoryLayout = cacheLayout(session, remoteRepository);
176            if (repositoryLayout == null) {
177                return new SimpleResult(true, "Unsupported layout: " + remoteRepository);
178            }
179            return acceptPrefix(
180                    remoteRepository,
181                    repositoryLayout.getLocation(artifact, false).getPath());
182        }
183
184        @Override
185        public Result acceptMetadata(RemoteRepository remoteRepository, Metadata metadata) {
186            RepositoryLayout repositoryLayout = cacheLayout(session, remoteRepository);
187            if (repositoryLayout == null) {
188                return new SimpleResult(true, "Unsupported layout: " + remoteRepository);
189            }
190            return acceptPrefix(
191                    remoteRepository,
192                    repositoryLayout.getLocation(metadata, false).getPath());
193        }
194
195        private Result acceptPrefix(RemoteRepository remoteRepository, String path) {
196            Node root = cacheNode(basedir, remoteRepository);
197            if (NOT_PRESENT_NODE == root) {
198                return NOT_PRESENT_RESULT;
199            }
200            List<String> prefix = new ArrayList<>();
201            final List<String> pathElements = elementsOf(path);
202            Node currentNode = root;
203            for (String pathElement : pathElements) {
204                prefix.add(pathElement);
205                currentNode = currentNode.getSibling(pathElement);
206                if (currentNode == null || currentNode.isLeaf()) {
207                    break;
208                }
209            }
210            if (currentNode != null && currentNode.isLeaf()) {
211                return new SimpleResult(
212                        true, "Prefix " + String.join("/", prefix) + " allowed from " + remoteRepository);
213            } else {
214                return new SimpleResult(
215                        false, "Prefix " + String.join("/", prefix) + " NOT allowed from " + remoteRepository);
216            }
217        }
218    }
219
220    private static final Node NOT_PRESENT_NODE = new Node("not-present-node");
221
222    private static final RemoteRepositoryFilter.Result NOT_PRESENT_RESULT =
223            new SimpleResult(true, "Prefix file not present");
224
225    private static class Node {
226        private final String name;
227
228        private final HashMap<String, Node> siblings;
229
230        private Node(String name) {
231            this.name = name;
232            this.siblings = new HashMap<>();
233        }
234
235        public String getName() {
236            return name;
237        }
238
239        public boolean isLeaf() {
240            return siblings.isEmpty();
241        }
242
243        public Node addSibling(String name) {
244            Node sibling = siblings.get(name);
245            if (sibling == null) {
246                sibling = new Node(name);
247                siblings.put(name, sibling);
248            }
249            return sibling;
250        }
251
252        public Node getSibling(String name) {
253            return siblings.get(name);
254        }
255    }
256
257    private static List<String> elementsOf(final String path) {
258        return Arrays.stream(path.split("/"))
259                .filter(e -> e != null && !e.isEmpty())
260                .collect(toList());
261    }
262}