    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 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import java.io.InputStream;
    021
    022import org.apache.commons.codec.CodecPolicy;
    023import org.apache.commons.codec.binary.BaseNCodecInputStream.AbstracBuilder; // NOPMD: Required by ECJ (Eclipse)
    024
    025/**
    026 * Provides Base64 decoding in a streaming fashion (unlimited size). When encoding the default lineLength is 76 characters and the default lineEnding is CRLF,
    027 * but these can be overridden by using the appropriate constructor.
    028 * <p>
    029 * The default behavior of the Base64InputStream is to DECODE, whereas the default behavior of the Base64OutputStream is to ENCODE, but this behavior can be
    030 * overridden by using a different constructor.
    031 * </p>
    032 * <p>
    033 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One:
    034 * Format of Internet Message Bodies</cite> by Freed and Borenstein.
    035 * </p>
    036 * <p>
    037 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are
    038 * compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
    039 * </p>
    040 * <p>
    041 * You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding. These can be bits that are
    042 * unused from the final character or entire characters. The default mode is lenient decoding.
    043 * </p>
    044 * <ul>
    045 * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
    046 * <li>Strict: The decoding will raise an {@link IllegalArgumentException} if trailing bits are not part of a valid encoding. Any unused bits from the final
    047 * character must be zero. Impossible counts of entire final characters are not allowed.
    048 * </ul>
    049 * <p>
    050 * When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches the original, i.e. no changes occur on
    051 * the final character. This requires that the input bytes use the same padding and alphabet as the encoder.
    052 * </p>
    053 *
    054 * @see Base64
    055 * @see <a href="https://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
    056 * @since 1.4
    057 */
    058public class Base64InputStream extends BaseNCodecInputStream<Base64, Base64InputStream, Base64InputStream.Builder> {
    059
    060    /**
    061     * Builds instances of Base64InputStream.
    062     */
    063    public static class Builder extends AbstracBuilder<Base64InputStream, Base64, Builder> {
    064
    065        /**
    066         * Constructs a new instance.
    067         */
    068        public Builder() {
    069            // empty
    070        }
    071
    072        @Override
    073        public Base64InputStream get() {
    074            return new Base64InputStream(this);
    075        }
    076
    077        @Override
    078        protected Base64 newBaseNCodec() {
    079            return new Base64();
    080        }
    081    }
    082
    083    /**
    084     * Constructs a new Builder.
    085     *
    086     * @return a new Builder.
    087     */
    088    public static Builder builder() {
    089        return new Builder();
    090    }
    091
    092    private Base64InputStream(final Builder builder) {
    093        super(builder);
    094    }
    095
    096    /**
    097     * Constructs a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
    098     *
    099     * @param inputStream InputStream to wrap.
    100     */
    101    public Base64InputStream(final InputStream inputStream) {
    102        super(builder().setInputStream(inputStream));
    103    }
    104
    105    /**
    106     * Constructs a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
    107     *
    108     * @param inputStream InputStream to wrap.
    109     * @param encode    true if we should encode all data read from us, false if we should decode.
    110     * @deprecated Use {@link #builder()} and {@link Builder}.
    111     */
    112    @Deprecated
    113    public Base64InputStream(final InputStream inputStream, final boolean encode) {
    114        super(builder().setInputStream(inputStream).setEncode(encode));
    115    }
    116
    117    /**
    118     * Constructs a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
    119     *
    120     * @param inputStream   InputStream to wrap.
    121     * @param encode      true if we should encode all data read from us, false if we should decode.
    122     * @param lineLength    If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to the nearest multiple of 4). If
    123     *                      lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode is false, lineLength is ignored.
    124     * @param lineSeparator If doEncode is true, each line of encoded data will be terminated with this byte sequence (for example \r\n). If lineLength &lt;= 0,
    125     *                      the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
    126     * @deprecated Use {@link #builder()} and {@link Builder}.
    127     */
    128    @Deprecated
    129    public Base64InputStream(final InputStream inputStream, final boolean encode, final int lineLength, final byte[] lineSeparator) {
    130        super(builder().setInputStream(inputStream).setEncode(encode)
    131                .setBaseNCodec(Base64.builder().setLineLength(lineLength).setLineSeparator(lineSeparator).get()));
    132    }
    133
    134    /**
    135     * Constructs a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
    136     *
    137     * @param inputStream    InputStream to wrap.
    138     * @param encode       true if we should encode all data read from us, false if we should decode.
    139     * @param lineLength     If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to the nearest multiple of 4). If
    140     *                       lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode is false, lineLength is ignored.
    141     * @param lineSeparator  If doEncode is true, each line of encoded data will be terminated with this byte sequence (for example \r\n). If lineLength &lt;=
    142     *                       0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
    143     * @param decodingPolicy The decoding policy.
    144     * @since 1.15
    145     * @deprecated Use {@link #builder()} and {@link Builder}.
    146     */
    147    @Deprecated
    148    public Base64InputStream(final InputStream inputStream, final boolean encode, final int lineLength, final byte[] lineSeparator,
    149            final CodecPolicy decodingPolicy) {
    150        super(builder().setInputStream(inputStream).setEncode(encode)
    151                .setBaseNCodec(Base64.builder().setLineLength(lineLength).setLineSeparator(lineSeparator).setDecodingPolicy(decodingPolicy).get()));
    152    }
    153}