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 * http://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.net;
19
20 import java.io.UnsupportedEncodingException;
21 import java.nio.charset.Charset;
22 import java.nio.charset.StandardCharsets;
23
24 import org.apache.commons.codec.CodecPolicy;
25 import org.apache.commons.codec.DecoderException;
26 import org.apache.commons.codec.EncoderException;
27 import org.apache.commons.codec.StringDecoder;
28 import org.apache.commons.codec.StringEncoder;
29 import org.apache.commons.codec.binary.Base64;
30 import org.apache.commons.codec.binary.BaseNCodec;
31
32 /**
33 * Identical to the Base64 encoding defined by <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>
34 * and allows a character set to be specified.
35 * <p>
36 * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> describes techniques to allow the encoding of non-ASCII
37 * text in various portions of a RFC 822 [2] message header, in a manner which is unlikely to confuse existing message
38 * handling software.
39 * </p>
40 * <p>
41 * This class is immutable and thread-safe.
42 * </p>
43 *
44 * @see <a href="http://www.ietf.org/rfc/rfc1522.txt">MIME (Multipurpose Internet Mail Extensions) Part Two: Message
45 * Header Extensions for Non-ASCII Text</a>
46 *
47 * @since 1.3
48 */
49 public class BCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
50
51 /**
52 * The default decoding policy.
53 */
54 private static final CodecPolicy DECODING_POLICY_DEFAULT = CodecPolicy.LENIENT;
55
56 /**
57 * The default Charset used for string decoding and encoding.
58 */
59 private final Charset charset;
60
61 /**
62 * If true then decoding should throw an exception for impossible combinations of bits at the
63 * end of the byte input. The default is to decode as much of them as possible.
64 */
65 private final CodecPolicy decodingPolicy;
66
67 /**
68 * Default constructor.
69 */
70 public BCodec() {
71 this(StandardCharsets.UTF_8);
72 }
73
74 /**
75 * Constructor which allows for the selection of a default Charset
76 *
77 * @param charset
78 * the default string Charset to use.
79 *
80 * @see Charset
81 * @since 1.7
82 */
83 public BCodec(final Charset charset) {
84 this(charset, DECODING_POLICY_DEFAULT);
85 }
86
87 /**
88 * Constructor which allows for the selection of a default Charset.
89 *
90 * @param charset
91 * the default string Charset to use.
92 * @param decodingPolicy The decoding policy.
93 *
94 * @see Charset
95 * @since 1.15
96 */
97 public BCodec(final Charset charset, final CodecPolicy decodingPolicy) {
98 this.charset = charset;
99 this.decodingPolicy = decodingPolicy;
100 }
101
102 /**
103 * Constructor which allows for the selection of a default Charset
104 *
105 * @param charsetName
106 * the default Charset to use.
107 * @throws java.nio.charset.UnsupportedCharsetException
108 * If the named Charset is unavailable
109 * @since 1.7 throws UnsupportedCharsetException if the named Charset is unavailable
110 * @see Charset
111 */
112 public BCodec(final String charsetName) {
113 this(Charset.forName(charsetName));
114 }
115
116 /**
117 * Decodes a Base64 object into its original form. Escaped characters are converted back to their original
118 * representation.
119 *
120 * @param value
121 * Base64 object to convert into its original form
122 * @return original object
123 * @throws DecoderException
124 * Thrown if the argument is not a {@code String}. Thrown if a failure condition is encountered
125 * during the decode process.
126 */
127 @Override
128 public Object decode(final Object value) throws DecoderException {
129 if (value == null) {
130 return null;
131 }
132 if (value instanceof String) {
133 return decode((String) value);
134 }
135 throw new DecoderException("Objects of type " +
136 value.getClass().getName() +
137 " cannot be decoded using BCodec");
138 }
139
140 /**
141 * Decodes a Base64 string into its original form. Escaped characters are converted back to their original
142 * representation.
143 *
144 * @param value
145 * Base64 string to convert into its original form
146 * @return original string
147 * @throws DecoderException
148 * A decoder exception is thrown if a failure condition is encountered during the decode process.
149 */
150 @Override
151 public String decode(final String value) throws DecoderException {
152 if (value == null) {
153 return null;
154 }
155 try {
156 return this.decodeText(value);
157 } catch (final UnsupportedEncodingException | IllegalArgumentException e) {
158 throw new DecoderException(e.getMessage(), e);
159 }
160 }
161
162 @Override
163 protected byte[] doDecoding(final byte[] bytes) {
164 if (bytes == null) {
165 return null;
166 }
167 return new Base64(0, BaseNCodec.getChunkSeparator(), false, decodingPolicy).decode(bytes);
168 }
169
170 @Override
171 protected byte[] doEncoding(final byte[] bytes) {
172 if (bytes == null) {
173 return null;
174 }
175 return Base64.encodeBase64(bytes);
176 }
177
178 /**
179 * Encodes an object into its Base64 form using the default Charset. Unsafe characters are escaped.
180 *
181 * @param value
182 * object to convert to Base64 form
183 * @return Base64 object
184 * @throws EncoderException
185 * thrown if a failure condition is encountered during the encoding process.
186 */
187 @Override
188 public Object encode(final Object value) throws EncoderException {
189 if (value == null) {
190 return null;
191 }
192 if (value instanceof String) {
193 return encode((String) value);
194 }
195 throw new EncoderException("Objects of type " +
196 value.getClass().getName() +
197 " cannot be encoded using BCodec");
198 }
199
200 /**
201 * Encodes a string into its Base64 form using the default Charset. Unsafe characters are escaped.
202 *
203 * @param strSource
204 * string to convert to Base64 form
205 * @return Base64 string
206 * @throws EncoderException
207 * thrown if a failure condition is encountered during the encoding process.
208 */
209 @Override
210 public String encode(final String strSource) throws EncoderException {
211 if (strSource == null) {
212 return null;
213 }
214 return encode(strSource, this.getCharset());
215 }
216
217 /**
218 * Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
219 *
220 * @param strSource
221 * string to convert to Base64 form
222 * @param sourceCharset
223 * the Charset for {@code value}
224 * @return Base64 string
225 * @throws EncoderException
226 * thrown if a failure condition is encountered during the encoding process.
227 * @since 1.7
228 */
229 public String encode(final String strSource, final Charset sourceCharset) throws EncoderException {
230 if (strSource == null) {
231 return null;
232 }
233 return encodeText(strSource, sourceCharset);
234 }
235
236 /**
237 * Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
238 *
239 * @param strSource
240 * string to convert to Base64 form
241 * @param sourceCharset
242 * the Charset for {@code value}
243 * @return Base64 string
244 * @throws EncoderException
245 * thrown if a failure condition is encountered during the encoding process.
246 */
247 public String encode(final String strSource, final String sourceCharset) throws EncoderException {
248 if (strSource == null) {
249 return null;
250 }
251 try {
252 return this.encodeText(strSource, sourceCharset);
253 } catch (final UnsupportedEncodingException e) {
254 throw new EncoderException(e.getMessage(), e);
255 }
256 }
257
258 /**
259 * Gets the default Charset name used for string decoding and encoding.
260 *
261 * @return the default Charset name
262 * @since 1.7
263 */
264 public Charset getCharset() {
265 return this.charset;
266 }
267
268 /**
269 * Gets the default Charset name used for string decoding and encoding.
270 *
271 * @return the default Charset name
272 */
273 public String getDefaultCharset() {
274 return this.charset.name();
275 }
276
277 @Override
278 protected String getEncoding() {
279 return "B";
280 }
281
282 /**
283 * Returns true if decoding behavior is strict. Decoding will raise a
284 * {@link DecoderException} if trailing bits are not part of a valid Base64 encoding.
285 *
286 * <p>The default is false for lenient encoding. Decoding will compose trailing bits
287 * into 8-bit bytes and discard the remainder.
288 *
289 * @return true if using strict decoding
290 * @since 1.15
291 */
292 public boolean isStrictDecoding() {
293 return decodingPolicy == CodecPolicy.STRICT;
294 }
295 }