    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 *      https://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.commons.io.input;
    018
    019import static org.apache.commons.io.IOUtils.EOF;
    020
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.util.Objects;
    024import java.util.zip.CheckedInputStream;
    025import java.util.zip.Checksum;
    026
    027/**
    028 * Automatically verifies a {@link Checksum} value once the stream is exhausted or the count threshold is reached.
    029 * <p>
    030 * If the {@link Checksum} does not meet the expected value when exhausted, then the input stream throws an
    031 * {@link IOException}.
    032 * </p>
    033 * <p>
    034 * If you do not need the verification or threshold feature, then use a plain {@link CheckedInputStream}.
    035 * </p>
    036 * <p>
    037 * To build an instance, use {@link Builder}.
    038 * </p>
    039 *
    040 * @see Builder
    041 * @since 2.16.0
    042 */
    043public final class ChecksumInputStream extends CountingInputStream {
    044
    045    // @formatter:off
    046    /**
    047     * Builds a new {@link ChecksumInputStream}.
    048     *
    049     * <p>
    050     * There is no default {@link Checksum}; you MUST provide one. This avoids any issue with a default {@link Checksum} being proven deficient or insecure
    051     * in the future.
    052     * </p>
    053     * <h2>Using NIO</h2>
    054     * <pre>{@code
    055     * ChecksumInputStream s = ChecksumInputStream.builder()
    056     *   .setPath(Paths.get("MyFile.xml"))
    057     *   .setChecksum(new CRC32())
    058     *   .setExpectedChecksumValue(12345)
    059     *   .get();
    060     * }</pre>
    061     * <h2>Using IO</h2>
    062     * <pre>{@code
    063     * ChecksumInputStream s = ChecksumInputStream.builder()
    064     *   .setFile(new File("MyFile.xml"))
    065     *   .setChecksum(new CRC32())
    066     *   .setExpectedChecksumValue(12345)
    067     *   .get();
    068     * }</pre>
    069     * <h2>Validating only part of an InputStream</h2>
    070     * <p>
    071     * The following validates the first 100 bytes of the given input.
    072     * </p>
    073     * <pre>{@code
    074     * ChecksumInputStream s = ChecksumInputStream.builder()
    075     *   .setPath(Paths.get("MyFile.xml"))
    076     *   .setChecksum(new CRC32())
    077     *   .setExpectedChecksumValue(12345)
    078     *   .setCountThreshold(100)
    079     *   .get();
    080     * }</pre>
    081     * <p>
    082     * To validate input <em>after</em> the beginning of a stream, build an instance with an InputStream starting where you want to validate.
    083     * </p>
    084     * <pre>{@code
    085     * InputStream inputStream = ...;
    086     * inputStream.read(...);
    087     * inputStream.skip(...);
    088     * ChecksumInputStream s = ChecksumInputStream.builder()
    089     *   .setInputStream(inputStream)
    090     *   .setChecksum(new CRC32())
    091     *   .setExpectedChecksumValue(12345)
    092     *   .setCountThreshold(100)
    093     *   .get();
    094     * }</pre>
    095     *
    096     * @see #get()
    097     */
    098    // @formatter:on
    099    public static class Builder extends AbstractBuilder<ChecksumInputStream, Builder> {
    100
    101        /**
    102         * There is no default {@link Checksum}, you MUST provide one. This avoids any issue with a default {@link Checksum} being proven deficient or insecure
    103         * in the future.
    104         */
    105        private Checksum checksum;
    106
    107        /**
    108         * The count threshold to limit how much input is consumed to update the {@link Checksum} before the input
    109         * stream validates its value.
    110         * <p>
    111         * By default, all input updates the {@link Checksum}.
    112         * </p>
    113         */
    114        private long countThreshold = -1;
    115
    116        /**
    117         * The expected {@link Checksum} value once the stream is exhausted or the count threshold is reached.
    118         */
    119        private long expectedChecksumValue;
    120
    121        /**
    122         * Constructs a new builder of {@link ChecksumInputStream}.
    123         */
    124        public Builder() {
    125            // empty
    126        }
    127
    128        /**
    129         * Builds a new {@link ChecksumInputStream}.
    130         * <p>
    131         * You must set an aspect that supports {@link #getInputStream()}, otherwise, this method throws an exception.
    132         * </p>
    133         * <p>
    134         * This builder uses the following aspects:
    135         * </p>
    136         * <ul>
    137         * <li>{@link #getInputStream()} gets the target aspect.</li>
    138         * <li>{@link Checksum}</li>
    139         * <li>expectedChecksumValue</li>
    140         * <li>countThreshold</li>
    141         * </ul>
    142         *
    143         * @return a new instance.
    144         * @throws IllegalStateException         if the {@code origin} is {@code null}.
    145         * @throws UnsupportedOperationException if the origin cannot be converted to an {@link InputStream}.
    146         * @throws IOException                   if an I/O error occurs converting to an {@link InputStream} using {@link #getInputStream()}.
    147         * @see #getInputStream()
    148         * @see #getUnchecked()
    149         */
    150        @Override
    151        public ChecksumInputStream get() throws IOException {
    152            return new ChecksumInputStream(this);
    153        }
    154
    155        /**
    156         * Sets the Checksum. There is no default {@link Checksum}, you MUST provide one. This avoids any issue with a default {@link Checksum} being proven
    157         * deficient or insecure in the future.
    158         *
    159         * @param checksum the Checksum.
    160         * @return {@code this} instance.
    161         */
    162        public Builder setChecksum(final Checksum checksum) {
    163            this.checksum = checksum;
    164            return this;
    165        }
    166
    167        /**
    168         * Sets the count threshold to limit how much input is consumed to update the {@link Checksum} before the input
    169         * stream validates its value.
    170         * <p>
    171         * By default, all input updates the {@link Checksum}.
    172         * </p>
    173         *
    174         * @param countThreshold the count threshold. A negative number means the threshold is unbound.
    175         * @return {@code this} instance.
    176         */
    177        public Builder setCountThreshold(final long countThreshold) {
    178            this.countThreshold = countThreshold;
    179            return this;
    180        }
    181
    182        /**
    183         * The expected {@link Checksum} value once the stream is exhausted or the count threshold is reached.
    184         *
    185         * @param expectedChecksumValue The expected Checksum value.
    186         * @return {@code this} instance.
    187         */
    188        public Builder setExpectedChecksumValue(final long expectedChecksumValue) {
    189            this.expectedChecksumValue = expectedChecksumValue;
    190            return this;
    191        }
    192
    193    }
    194
    195    /**
    196     * Constructs a new {@link Builder}.
    197     *
    198     * @return a new {@link Builder}.
    199     */
    200    public static Builder builder() {
    201        return new Builder();
    202    }
    203
    204    /** The expected checksum. */
    205    private final long expectedChecksumValue;
    206
    207    /**
    208     * The count threshold to limit how much input is consumed to update the {@link Checksum} before the input stream
    209     * validates its value.
    210     * <p>
    211     * By default, all input updates the {@link Checksum}.
    212     * </p>
    213     */
    214    private final long countThreshold;
    215
    216    /**
    217     * Constructs a new instance.
    218     *
    219     * @param builder build parameters.
    220     */
    221    @SuppressWarnings("resource")
    222    private ChecksumInputStream(final Builder builder) throws IOException {
    223        super(new CheckedInputStream(builder.getInputStream(), Objects.requireNonNull(builder.checksum, "builder.checksum")), builder);
    224        this.countThreshold = builder.countThreshold;
    225        this.expectedChecksumValue = builder.expectedChecksumValue;
    226    }
    227
    228    @Override
    229    protected synchronized void afterRead(final int n) throws IOException {
    230        super.afterRead(n);
    231        if ((countThreshold > 0 && getByteCount() >= countThreshold || n == EOF)
    232                && expectedChecksumValue != getChecksum().getValue()) {
    233            // Validate when past the threshold or at EOF
    234            throw new IOException("Checksum verification failed.");
    235        }
    236    }
    237
    238    /**
    239     * Gets the current checksum value.
    240     *
    241     * @return the current checksum value.
    242     */
    243    private Checksum getChecksum() {
    244        return ((CheckedInputStream) in).getChecksum();
    245    }
    246
    247    /**
    248     * Gets the byte count remaining to read.
    249     *
    250     * @return bytes remaining to read, a negative number means the threshold is unbound.
    251     */
    252    public long getRemaining() {
    253        return countThreshold - getByteCount();
    254    }
    255
    256}