    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.commons.io.input;
    018
    019import java.io.IOException;
    020import java.io.InputStream;
    021import java.security.MessageDigest;
    022import java.security.NoSuchAlgorithmException;
    023import java.security.Provider;
    024
    025import org.apache.commons.io.build.AbstractStreamBuilder;
    026
    027/**
    028 * This class is an example for using an {@link ObservableInputStream}. It creates its own {@link org.apache.commons.io.input.ObservableInputStream.Observer},
    029 * which calculates a checksum using a MessageDigest, for example an MD5 sum.
    030 * <p>
    031 * To build an instance, see {@link Builder}.
    032 * </p>
    033 * <p>
    034 * See the MessageDigest section in the <a href= "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#MessageDigest"> Java
    035 * Cryptography Architecture Standard Algorithm Name Documentation</a> for information about standard algorithm names.
    036 * </p>
    037 * <p>
    038 * <em>Note</em>: Neither {@link ObservableInputStream}, nor {@link MessageDigest}, are thread safe. So is {@link MessageDigestCalculatingInputStream}.
    039 * </p>
    040 * <p>
    041 * TODO Rename to MessageDigestInputStream in 3.0.
    042 * </p>
    043 */
    044public class MessageDigestCalculatingInputStream extends ObservableInputStream {
    045
    046    /**
    047     * Builds a new {@link MessageDigestCalculatingInputStream} instance.
    048     * <p>
    049     * For example:
    050     * </p>
    051     * <pre>{@code
    052     * MessageDigestCalculatingInputStream s = MessageDigestCalculatingInputStream.builder()
    053     *   .setPath(path)
    054     *   .setMessageDigest("SHA-512")
    055     *   .get();}
    056     * </pre>
    057     *
    058     * @since 2.12.0
    059     */
    060    public static class Builder extends AbstractStreamBuilder<MessageDigestCalculatingInputStream, Builder> {
    061
    062        private MessageDigest messageDigest;
    063
    064        public Builder() {
    065            try {
    066                this.messageDigest = getDefaultMessageDigest();
    067            } catch (final NoSuchAlgorithmException e) {
    068                // Should not happen.
    069                throw new IllegalStateException(e);
    070            }
    071        }
    072
    073        /**
    074         * Constructs a new instance.
    075         * <p>
    076         * This builder use the aspects InputStream, OpenOption[], and MessageDigest.
    077         * </p>
    078         * <p>
    079         * You must provide an origin that can be converted to an InputStream by this builder, otherwise, this call will throw an
    080         * {@link UnsupportedOperationException}.
    081         * </p>
    082         *
    083         * @return a new instance.
    084         * @throws UnsupportedOperationException if the origin cannot provide an InputStream.
    085         * @see #getInputStream()
    086         */
    087        @SuppressWarnings("resource")
    088        @Override
    089        public MessageDigestCalculatingInputStream get() throws IOException {
    090            return new MessageDigestCalculatingInputStream(getInputStream(), messageDigest);
    091        }
    092
    093        /**
    094         * Sets the message digest.
    095         *
    096         * @param messageDigest the message digest.
    097         */
    098        public void setMessageDigest(final MessageDigest messageDigest) {
    099            this.messageDigest = messageDigest;
    100        }
    101
    102        /**
    103         * Sets the name of the name of the message digest algorithm.
    104         *
    105         * @param algorithm the name of the algorithm. See the MessageDigest section in the
    106         *                  <a href= "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#MessageDigest"> Java Cryptography
    107         *                  Architecture Standard Algorithm Name Documentation</a> for information about standard algorithm names.
    108         * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation for the specified algorithm.
    109         */
    110        public void setMessageDigest(final String algorithm) throws NoSuchAlgorithmException {
    111            this.messageDigest = MessageDigest.getInstance(algorithm);
    112        }
    113
    114    }
    115
    116    /**
    117     * Maintains the message digest.
    118     */
    119    public static class MessageDigestMaintainingObserver extends Observer {
    120        private final MessageDigest messageDigest;
    121
    122        /**
    123         * Creates an MessageDigestMaintainingObserver for the given MessageDigest.
    124         *
    125         * @param messageDigest the message digest to use
    126         */
    127        public MessageDigestMaintainingObserver(final MessageDigest messageDigest) {
    128            this.messageDigest = messageDigest;
    129        }
    130
    131        @Override
    132        public void data(final byte[] input, final int offset, final int length) throws IOException {
    133            messageDigest.update(input, offset, length);
    134        }
    135
    136        @Override
    137        public void data(final int input) throws IOException {
    138            messageDigest.update((byte) input);
    139        }
    140    }
    141
    142    /**
    143     * The default message digest algorithm.
    144     * <p>
    145     * The MD5 cryptographic algorithm is weak and should not be used.
    146     * </p>
    147     */
    148    private static final String DEFAULT_ALGORITHM = "MD5";
    149
    150    /**
    151     * Constructs a new {@link Builder}.
    152     *
    153     * @return a new {@link Builder}.
    154     * @since 2.12.0
    155     */
    156    public static Builder builder() {
    157        return new Builder();
    158    }
    159
    160    /**
    161     * Gets a MessageDigest object that implements the default digest algorithm.
    162     *
    163     * @return a Message Digest object that implements the default algorithm.
    164     * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation.
    165     * @see Provider
    166     */
    167    static MessageDigest getDefaultMessageDigest() throws NoSuchAlgorithmException {
    168        return MessageDigest.getInstance(DEFAULT_ALGORITHM);
    169    }
    170
    171    private final MessageDigest messageDigest;
    172
    173    /**
    174     * Creates a new instance, which calculates a signature on the given stream, using a {@link MessageDigest} with the "MD5" algorithm.
    175     * <p>
    176     * The MD5 algorithm is weak and should not be used.
    177     * </p>
    178     *
    179     * @param inputStream the stream to calculate the message digest for
    180     * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation for the specified algorithm.
    181     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}.
    182     */
    183    @Deprecated
    184    public MessageDigestCalculatingInputStream(final InputStream inputStream) throws NoSuchAlgorithmException {
    185        this(inputStream, getDefaultMessageDigest());
    186    }
    187
    188    /**
    189     * Creates a new instance, which calculates a signature on the given stream, using the given {@link MessageDigest}.
    190     *
    191     * @param inputStream   the stream to calculate the message digest for
    192     * @param messageDigest the message digest to use
    193     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}.
    194     */
    195    @Deprecated
    196    public MessageDigestCalculatingInputStream(final InputStream inputStream, final MessageDigest messageDigest) {
    197        super(inputStream, new MessageDigestMaintainingObserver(messageDigest));
    198        this.messageDigest = messageDigest;
    199    }
    200
    201    /**
    202     * Creates a new instance, which calculates a signature on the given stream, using a {@link MessageDigest} with the given algorithm.
    203     *
    204     * @param inputStream the stream to calculate the message digest for
    205     * @param algorithm   the name of the algorithm requested. See the MessageDigest section in the
    206     *                    <a href= "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#MessageDigest"> Java Cryptography
    207     *                    Architecture Standard Algorithm Name Documentation</a> for information about standard algorithm names.
    208     * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation for the specified algorithm.
    209     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}.
    210     */
    211    @Deprecated
    212    public MessageDigestCalculatingInputStream(final InputStream inputStream, final String algorithm) throws NoSuchAlgorithmException {
    213        this(inputStream, MessageDigest.getInstance(algorithm));
    214    }
    215
    216    /**
    217     * Gets the {@link MessageDigest}, which is being used for generating the checksum.
    218     * <p>
    219     * <em>Note</em>: The checksum will only reflect the data, which has been read so far. This is probably not, what you expect. Make sure, that the complete
    220     * data has been read, if that is what you want. The easiest way to do so is by invoking {@link #consume()}.
    221     * </p>
    222     *
    223     * @return the message digest used
    224     */
    225    public MessageDigest getMessageDigest() {
    226        return messageDigest;
    227    }
    228}