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 */
017
018package org.apache.commons.codec.net;
019
020import java.io.UnsupportedEncodingException;
021import java.nio.charset.Charset;
022import java.nio.charset.StandardCharsets;
023import java.util.BitSet;
024
025import org.apache.commons.codec.DecoderException;
026import org.apache.commons.codec.EncoderException;
027import org.apache.commons.codec.StringDecoder;
028import org.apache.commons.codec.StringEncoder;
029
030/**
031 * Similar to the Quoted-Printable content-transfer-encoding defined in
032 * <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a> and designed to allow text containing mostly ASCII
033 * characters to be decipherable on an ASCII terminal without decoding.
034 * <p>
035 * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> describes techniques to allow the encoding of non-ASCII
036 * text in various portions of a RFC 822 [2] message header, in a manner which is unlikely to confuse existing message
037 * handling software.
038 * </p>
039 * <p>
040 * This class is conditionally thread-safe.
041 * The instance field for encoding blanks is mutable {@link #setEncodeBlanks(boolean)}
042 * but is not volatile, and accesses are not synchronised.
043 * If an instance of the class is shared between threads, the caller needs to ensure that suitable synchronisation
044 * is used to ensure safe publication of the value between threads, and must not invoke
045 * {@link #setEncodeBlanks(boolean)} after initial setup.
046 * </p>
047 *
048 * @see <a href="http://www.ietf.org/rfc/rfc1522.txt">MIME (Multipurpose Internet Mail Extensions) Part Two: Message
049 *          Header Extensions for Non-ASCII Text</a>
050 *
051 * @since 1.3
052 */
053public class QCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
054    /**
055     * The default Charset used for string decoding and encoding.
056     */
057    private final Charset charset;
058
059    /**
060     * BitSet of printable characters as defined in RFC 1522.
061     */
062    private static final BitSet PRINTABLE_CHARS = new BitSet(256);
063    // Static initializer for printable chars collection
064    static {
065        // alpha characters
066        PRINTABLE_CHARS.set(' ');
067        PRINTABLE_CHARS.set('!');
068        PRINTABLE_CHARS.set('"');
069        PRINTABLE_CHARS.set('#');
070        PRINTABLE_CHARS.set('$');
071        PRINTABLE_CHARS.set('%');
072        PRINTABLE_CHARS.set('&');
073        PRINTABLE_CHARS.set('\'');
074        PRINTABLE_CHARS.set('(');
075        PRINTABLE_CHARS.set(')');
076        PRINTABLE_CHARS.set('*');
077        PRINTABLE_CHARS.set('+');
078        PRINTABLE_CHARS.set(',');
079        PRINTABLE_CHARS.set('-');
080        PRINTABLE_CHARS.set('.');
081        PRINTABLE_CHARS.set('/');
082        for (int i = '0'; i <= '9'; i++) {
083            PRINTABLE_CHARS.set(i);
084        }
085        PRINTABLE_CHARS.set(':');
086        PRINTABLE_CHARS.set(';');
087        PRINTABLE_CHARS.set('<');
088        PRINTABLE_CHARS.set('>');
089        PRINTABLE_CHARS.set('@');
090        for (int i = 'A'; i <= 'Z'; i++) {
091            PRINTABLE_CHARS.set(i);
092        }
093        PRINTABLE_CHARS.set('[');
094        PRINTABLE_CHARS.set('\\');
095        PRINTABLE_CHARS.set(']');
096        PRINTABLE_CHARS.set('^');
097        PRINTABLE_CHARS.set('`');
098        for (int i = 'a'; i <= 'z'; i++) {
099            PRINTABLE_CHARS.set(i);
100        }
101        PRINTABLE_CHARS.set('{');
102        PRINTABLE_CHARS.set('|');
103        PRINTABLE_CHARS.set('}');
104        PRINTABLE_CHARS.set('~');
105    }
106
107    private static final byte SPACE = 32;
108
109    private static final byte UNDERSCORE = 95;
110
111    private boolean encodeBlanks = false;
112
113    /**
114     * Default constructor.
115     */
116    public QCodec() {
117        this(StandardCharsets.UTF_8);
118    }
119
120    /**
121     * Constructor which allows for the selection of a default Charset.
122     *
123     * @param charset
124     *            the default string Charset to use.
125     *
126     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
127     * @since 1.7
128     */
129    public QCodec(final Charset charset) {
130        super();
131        this.charset = charset;
132    }
133
134    /**
135     * Constructor which allows for the selection of a default Charset.
136     *
137     * @param charsetName
138     *            the Charset to use.
139     * @throws java.nio.charset.UnsupportedCharsetException
140     *             If the named Charset is unavailable
141     * @since 1.7 throws UnsupportedCharsetException if the named Charset is unavailable
142     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
143     */
144    public QCodec(final String charsetName) {
145        this(Charset.forName(charsetName));
146    }
147
148    @Override
149    protected String getEncoding() {
150        return "Q";
151    }
152
153    @Override
154    protected byte[] doEncoding(final byte[] bytes) {
155        if (bytes == null) {
156            return null;
157        }
158        final byte[] data = QuotedPrintableCodec.encodeQuotedPrintable(PRINTABLE_CHARS, bytes);
159        if (this.encodeBlanks) {
160            for (int i = 0; i < data.length; i++) {
161                if (data[i] == SPACE) {
162                    data[i] = UNDERSCORE;
163                }
164            }
165        }
166        return data;
167    }
168
169    @Override
170    protected byte[] doDecoding(final byte[] bytes) throws DecoderException {
171        if (bytes == null) {
172            return null;
173        }
174        boolean hasUnderscores = false;
175        for (final byte b : bytes) {
176            if (b == UNDERSCORE) {
177                hasUnderscores = true;
178                break;
179            }
180        }
181        if (hasUnderscores) {
182            final byte[] tmp = new byte[bytes.length];
183            for (int i = 0; i < bytes.length; i++) {
184                final byte b = bytes[i];
185                if (b != UNDERSCORE) {
186                    tmp[i] = b;
187                } else {
188                    tmp[i] = SPACE;
189                }
190            }
191            return QuotedPrintableCodec.decodeQuotedPrintable(tmp);
192        }
193        return QuotedPrintableCodec.decodeQuotedPrintable(bytes);
194    }
195
196    /**
197     * Encodes a string into its quoted-printable form using the specified Charset. Unsafe characters are escaped.
198     *
199     * @param sourceStr
200     *            string to convert to quoted-printable form
201     * @param sourceCharset
202     *            the Charset for sourceStr
203     * @return quoted-printable string
204     * @throws EncoderException
205     *             thrown if a failure condition is encountered during the encoding process.
206     * @since 1.7
207     */
208    public String encode(final String sourceStr, final Charset sourceCharset) throws EncoderException {
209        if (sourceStr == null) {
210            return null;
211        }
212        return encodeText(sourceStr, sourceCharset);
213    }
214
215    /**
216     * Encodes a string into its quoted-printable form using the specified Charset. Unsafe characters are escaped.
217     *
218     * @param sourceStr
219     *            string to convert to quoted-printable form
220     * @param sourceCharset
221     *            the Charset for sourceStr
222     * @return quoted-printable string
223     * @throws EncoderException
224     *             thrown if a failure condition is encountered during the encoding process.
225     */
226    public String encode(final String sourceStr, final String sourceCharset) throws EncoderException {
227        if (sourceStr == null) {
228            return null;
229        }
230        try {
231            return encodeText(sourceStr, sourceCharset);
232        } catch (final UnsupportedEncodingException e) {
233            throw new EncoderException(e.getMessage(), e);
234        }
235    }
236
237    /**
238     * Encodes a string into its quoted-printable form using the default Charset. Unsafe characters are escaped.
239     *
240     * @param sourceStr
241     *            string to convert to quoted-printable form
242     * @return quoted-printable string
243     * @throws EncoderException
244     *             thrown if a failure condition is encountered during the encoding process.
245     */
246    @Override
247    public String encode(final String sourceStr) throws EncoderException {
248        if (sourceStr == null) {
249            return null;
250        }
251        return encode(sourceStr, getCharset());
252    }
253
254    /**
255     * Decodes a quoted-printable string into its original form. Escaped characters are converted back to their original
256     * representation.
257     *
258     * @param str
259     *            quoted-printable string to convert into its original form
260     * @return original string
261     * @throws DecoderException
262     *             A decoder exception is thrown if a failure condition is encountered during the decode process.
263     */
264    @Override
265    public String decode(final String str) throws DecoderException {
266        if (str == null) {
267            return null;
268        }
269        try {
270            return decodeText(str);
271        } catch (final UnsupportedEncodingException e) {
272            throw new DecoderException(e.getMessage(), e);
273        }
274    }
275
276    /**
277     * Encodes an object into its quoted-printable form using the default Charset. Unsafe characters are escaped.
278     *
279     * @param obj
280     *            object to convert to quoted-printable form
281     * @return quoted-printable object
282     * @throws EncoderException
283     *             thrown if a failure condition is encountered during the encoding process.
284     */
285    @Override
286    public Object encode(final Object obj) throws EncoderException {
287        if (obj == null) {
288            return null;
289        } else if (obj instanceof String) {
290            return encode((String) obj);
291        } else {
292            throw new EncoderException("Objects of type " +
293                  obj.getClass().getName() +
294                  " cannot be encoded using Q codec");
295        }
296    }
297
298    /**
299     * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original
300     * representation.
301     *
302     * @param obj
303     *            quoted-printable object to convert into its original form
304     * @return original object
305     * @throws DecoderException
306     *             Thrown if the argument is not a {@code String}. Thrown if a failure condition is encountered
307     *             during the decode process.
308     */
309    @Override
310    public Object decode(final Object obj) throws DecoderException {
311        if (obj == null) {
312            return null;
313        } else if (obj instanceof String) {
314            return decode((String) obj);
315        } else {
316            throw new DecoderException("Objects of type " +
317                  obj.getClass().getName() +
318                  " cannot be decoded using Q codec");
319        }
320    }
321
322    /**
323     * Gets the default Charset name used for string decoding and encoding.
324     *
325     * @return the default Charset name
326     * @since 1.7
327     */
328    public Charset getCharset() {
329        return this.charset;
330    }
331
332    /**
333     * Gets the default Charset name used for string decoding and encoding.
334     *
335     * @return the default Charset name
336     */
337    public String getDefaultCharset() {
338        return this.charset.name();
339    }
340
341    /**
342     * Tests if optional transformation of SPACE characters is to be used
343     *
344     * @return {@code true} if SPACE characters are to be transformed, {@code false} otherwise
345     */
346    public boolean isEncodeBlanks() {
347        return this.encodeBlanks;
348    }
349
350    /**
351     * Defines whether optional transformation of SPACE characters is to be used
352     *
353     * @param b
354     *            {@code true} if SPACE characters are to be transformed, {@code false} otherwise
355     */
356    public void setEncodeBlanks(final boolean b) {
357        this.encodeBlanks = b;
358    }
359}