1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.codec.binary;
19
20 import java.io.InputStream;
21
22 import org.apache.commons.codec.CodecPolicy;
23 import org.apache.commons.codec.binary.BaseNCodecInputStream.AbstracBuilder; // NOPMD: Required by ECJ (Eclipse)
24
25 /**
26 * Provides Base64 decoding in a streaming fashion (unlimited size). When encoding the default lineLength is 76 characters and the default lineEnding is CRLF,
27 * but these can be overridden by using the appropriate constructor.
28 * <p>
29 * The default behavior of the Base64InputStream is to DECODE, whereas the default behavior of the Base64OutputStream is to ENCODE, but this behavior can be
30 * overridden by using a different constructor.
31 * </p>
32 * <p>
33 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One:
34 * Format of Internet Message Bodies</cite> by Freed and Borenstein.
35 * </p>
36 * <p>
37 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are
38 * compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
39 * </p>
40 * <p>
41 * 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
42 * unused from the final character or entire characters. The default mode is lenient decoding.
43 * </p>
44 * <ul>
45 * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
46 * <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
47 * character must be zero. Impossible counts of entire final characters are not allowed.
48 * </ul>
49 * <p>
50 * 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
51 * the final character. This requires that the input bytes use the same padding and alphabet as the encoder.
52 * </p>
53 *
54 * @see Base64
55 * @see <a href="https://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
56 * @since 1.4
57 */
58 public class Base64InputStream extends BaseNCodecInputStream<Base64, Base64InputStream, Base64InputStream.Builder> {
59
60 /**
61 * Builds instances of Base64InputStream.
62 */
63 public static class Builder extends AbstracBuilder<Base64InputStream, Base64, Builder> {
64
65 /**
66 * Constructs a new instance.
67 */
68 public Builder() {
69 // empty
70 }
71
72 @Override
73 public Base64InputStream get() {
74 return new Base64InputStream(this);
75 }
76
77 @Override
78 protected Base64 newBaseNCodec() {
79 return new Base64();
80 }
81 }
82
83 /**
84 * Constructs a new Builder.
85 *
86 * @return a new Builder.
87 */
88 public static Builder builder() {
89 return new Builder();
90 }
91
92 private Base64InputStream(final Builder builder) {
93 super(builder);
94 }
95
96 /**
97 * Constructs a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
98 *
99 * @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 <= 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 <= 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 <= 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 <=
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 }