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.ByteArrayOutputStream;
021import java.io.UnsupportedEncodingException;
022import java.nio.charset.Charset;
023import java.nio.charset.IllegalCharsetNameException;
024import java.nio.charset.UnsupportedCharsetException;
025import java.util.BitSet;
026
027import org.apache.commons.codec.BinaryDecoder;
028import org.apache.commons.codec.BinaryEncoder;
029import org.apache.commons.codec.Charsets;
030import org.apache.commons.codec.DecoderException;
031import org.apache.commons.codec.EncoderException;
032import org.apache.commons.codec.StringDecoder;
033import org.apache.commons.codec.StringEncoder;
034import org.apache.commons.codec.binary.StringUtils;
035
036/**
037 * Codec for the Quoted-Printable section of <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>.
038 * <p>
039 * The Quoted-Printable encoding is intended to represent data that largely consists of octets that correspond to
040 * printable characters in the ASCII character set. It encodes the data in such a way that the resulting octets are
041 * unlikely to be modified by mail transport. If the data being encoded are mostly ASCII text, the encoded form of the
042 * data remains largely recognizable by humans. A body which is entirely ASCII may also be encoded in Quoted-Printable
043 * to ensure the integrity of the data should the message pass through a character- translating, and/or line-wrapping
044 * gateway.
045 * <p>
046 * Note:
047 * <p>
048 * Rules #3, #4, and #5 of the quoted-printable spec are not implemented yet because the complete quoted-printable spec
049 * does not lend itself well into the byte[] oriented codec framework. Complete the codec once the streamable codec
050 * framework is ready. The motivation behind providing the codec in a partial form is that it can already come in handy
051 * for those applications that do not require quoted-printable line formatting (rules #3, #4, #5), for instance Q codec.
052 * <p>
053 * This class is immutable and thread-safe.
054 *
055 * @see <a href="http://www.ietf.org/rfc/rfc1521.txt"> RFC 1521 MIME (Multipurpose Internet Mail Extensions) Part One:
056 *          Mechanisms for Specifying and Describing the Format of Internet Message Bodies </a>
057 *
058 * @since 1.3
059 * @version $Id: QuotedPrintableCodec.html 891688 2013-12-24 20:49:46Z ggregory $
060 */
061public class QuotedPrintableCodec implements BinaryEncoder, BinaryDecoder, StringEncoder, StringDecoder {
062    /**
063     * The default charset used for string decoding and encoding.
064     */
065    private final Charset charset;
066
067    /**
068     * BitSet of printable characters as defined in RFC 1521.
069     */
070    private static final BitSet PRINTABLE_CHARS = new BitSet(256);
071
072    private static final byte ESCAPE_CHAR = '=';
073
074    private static final byte TAB = 9;
075
076    private static final byte SPACE = 32;
077    // Static initializer for printable chars collection
078    static {
079        // alpha characters
080        for (int i = 33; i <= 60; i++) {
081            PRINTABLE_CHARS.set(i);
082        }
083        for (int i = 62; i <= 126; i++) {
084            PRINTABLE_CHARS.set(i);
085        }
086        PRINTABLE_CHARS.set(TAB);
087        PRINTABLE_CHARS.set(SPACE);
088    }
089
090    /**
091     * Default constructor, assumes default charset of {@link Charsets#UTF_8}
092     */
093    public QuotedPrintableCodec() {
094        this(Charsets.UTF_8);
095    }
096
097    /**
098     * Constructor which allows for the selection of a default charset.
099     *
100     * @param charset
101     *            the default string charset to use.
102     * @since 1.7
103     */
104    public QuotedPrintableCodec(final Charset charset) {
105        this.charset = charset;
106    }
107
108    /**
109     * Constructor which allows for the selection of a default charset.
110     *
111     * @param charsetName
112     *            the default string charset to use.
113     * @throws UnsupportedCharsetException
114     *             If no support for the named charset is available
115     *             in this instance of the Java virtual machine
116     * @throws IllegalArgumentException
117     *             If the given charsetName is null
118     * @throws IllegalCharsetNameException
119     *             If the given charset name is illegal
120     *
121     * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
122     */
123    public QuotedPrintableCodec(final String charsetName)
124            throws IllegalCharsetNameException, IllegalArgumentException, UnsupportedCharsetException {
125        this(Charset.forName(charsetName));
126    }
127
128    /**
129     * Encodes byte into its quoted-printable representation.
130     *
131     * @param b
132     *            byte to encode
133     * @param buffer
134     *            the buffer to write to
135     */
136    private static final void encodeQuotedPrintable(final int b, final ByteArrayOutputStream buffer) {
137        buffer.write(ESCAPE_CHAR);
138        final char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, 16));
139        final char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, 16));
140        buffer.write(hex1);
141        buffer.write(hex2);
142    }
143
144    /**
145     * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped.
146     * <p>
147     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
148     * RFC 1521 and is suitable for encoding binary data and unformatted text.
149     *
150     * @param printable
151     *            bitset of characters deemed quoted-printable
152     * @param bytes
153     *            array of bytes to be encoded
154     * @return array of bytes containing quoted-printable data
155     */
156    public static final byte[] encodeQuotedPrintable(BitSet printable, final byte[] bytes) {
157        if (bytes == null) {
158            return null;
159        }
160        if (printable == null) {
161            printable = PRINTABLE_CHARS;
162        }
163        final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
164        for (final byte c : bytes) {
165            int b = c;
166            if (b < 0) {
167                b = 256 + b;
168            }
169            if (printable.get(b)) {
170                buffer.write(b);
171            } else {
172                encodeQuotedPrintable(b, buffer);
173            }
174        }
175        return buffer.toByteArray();
176    }
177
178    /**
179     * Decodes an array quoted-printable characters into an array of original bytes. Escaped characters are converted
180     * back to their original representation.
181     * <p>
182     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
183     * RFC 1521.
184     *
185     * @param bytes
186     *            array of quoted-printable characters
187     * @return array of original bytes
188     * @throws DecoderException
189     *             Thrown if quoted-printable decoding is unsuccessful
190     */
191    public static final byte[] decodeQuotedPrintable(final byte[] bytes) throws DecoderException {
192        if (bytes == null) {
193            return null;
194        }
195        final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
196        for (int i = 0; i < bytes.length; i++) {
197            final int b = bytes[i];
198            if (b == ESCAPE_CHAR) {
199                try {
200                    final int u = Utils.digit16(bytes[++i]);
201                    final int l = Utils.digit16(bytes[++i]);
202                    buffer.write((char) ((u << 4) + l));
203                } catch (final ArrayIndexOutOfBoundsException e) {
204                    throw new DecoderException("Invalid quoted-printable encoding", e);
205                }
206            } else {
207                buffer.write(b);
208            }
209        }
210        return buffer.toByteArray();
211    }
212
213    /**
214     * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped.
215     * <p>
216     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
217     * RFC 1521 and is suitable for encoding binary data and unformatted text.
218     *
219     * @param bytes
220     *            array of bytes to be encoded
221     * @return array of bytes containing quoted-printable data
222     */
223    @Override
224    public byte[] encode(final byte[] bytes) {
225        return encodeQuotedPrintable(PRINTABLE_CHARS, bytes);
226    }
227
228    /**
229     * Decodes an array of quoted-printable characters into an array of original bytes. Escaped characters are converted
230     * back to their original representation.
231     * <p>
232     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
233     * RFC 1521.
234     *
235     * @param bytes
236     *            array of quoted-printable characters
237     * @return array of original bytes
238     * @throws DecoderException
239     *             Thrown if quoted-printable decoding is unsuccessful
240     */
241    @Override
242    public byte[] decode(final byte[] bytes) throws DecoderException {
243        return decodeQuotedPrintable(bytes);
244    }
245
246    /**
247     * Encodes a string into its quoted-printable form using the default string charset. Unsafe characters are escaped.
248     * <p>
249     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
250     * RFC 1521 and is suitable for encoding binary data.
251     *
252     * @param str
253     *            string to convert to quoted-printable form
254     * @return quoted-printable string
255     * @throws EncoderException
256     *             Thrown if quoted-printable encoding is unsuccessful
257     *
258     * @see #getCharset()
259     */
260    @Override
261    public String encode(final String str) throws EncoderException {
262        return this.encode(str, getCharset());
263    }
264
265    /**
266     * Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters
267     * are converted back to their original representation.
268     *
269     * @param str
270     *            quoted-printable string to convert into its original form
271     * @param charset
272     *            the original string charset
273     * @return original string
274     * @throws DecoderException
275     *             Thrown if quoted-printable decoding is unsuccessful
276     * @since 1.7
277     */
278    public String decode(final String str, final Charset charset) throws DecoderException {
279        if (str == null) {
280            return null;
281        }
282        return new String(this.decode(StringUtils.getBytesUsAscii(str)), charset);
283    }
284
285    /**
286     * Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters
287     * are converted back to their original representation.
288     *
289     * @param str
290     *            quoted-printable string to convert into its original form
291     * @param charset
292     *            the original string charset
293     * @return original string
294     * @throws DecoderException
295     *             Thrown if quoted-printable decoding is unsuccessful
296     * @throws UnsupportedEncodingException
297     *             Thrown if charset is not supported
298     */
299    public String decode(final String str, final String charset) throws DecoderException, UnsupportedEncodingException {
300        if (str == null) {
301            return null;
302        }
303        return new String(decode(StringUtils.getBytesUsAscii(str)), charset);
304    }
305
306    /**
307     * Decodes a quoted-printable string into its original form using the default string charset. Escaped characters are
308     * converted back to their original representation.
309     *
310     * @param str
311     *            quoted-printable string to convert into its original form
312     * @return original string
313     * @throws DecoderException
314     *             Thrown if quoted-printable decoding is unsuccessful. Thrown if charset is not supported.
315     * @see #getCharset()
316     */
317    @Override
318    public String decode(final String str) throws DecoderException {
319        return this.decode(str, this.getCharset());
320    }
321
322    /**
323     * Encodes an object into its quoted-printable safe form. Unsafe characters are escaped.
324     *
325     * @param obj
326     *            string to convert to a quoted-printable form
327     * @return quoted-printable object
328     * @throws EncoderException
329     *             Thrown if quoted-printable encoding is not applicable to objects of this type or if encoding is
330     *             unsuccessful
331     */
332    @Override
333    public Object encode(final Object obj) throws EncoderException {
334        if (obj == null) {
335            return null;
336        } else if (obj instanceof byte[]) {
337            return encode((byte[]) obj);
338        } else if (obj instanceof String) {
339            return encode((String) obj);
340        } else {
341            throw new EncoderException("Objects of type " +
342                  obj.getClass().getName() +
343                  " cannot be quoted-printable encoded");
344        }
345    }
346
347    /**
348     * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original
349     * representation.
350     *
351     * @param obj
352     *            quoted-printable object to convert into its original form
353     * @return original object
354     * @throws DecoderException
355     *             Thrown if the argument is not a <code>String</code> or <code>byte[]</code>. Thrown if a failure
356     *             condition is encountered during the decode process.
357     */
358    @Override
359    public Object decode(final Object obj) throws DecoderException {
360        if (obj == null) {
361            return null;
362        } else if (obj instanceof byte[]) {
363            return decode((byte[]) obj);
364        } else if (obj instanceof String) {
365            return decode((String) obj);
366        } else {
367            throw new DecoderException("Objects of type " +
368                  obj.getClass().getName() +
369                  " cannot be quoted-printable decoded");
370        }
371    }
372
373    /**
374     * Gets the default charset name used for string decoding and encoding.
375     *
376     * @return the default charset name
377     * @since 1.7
378     */
379    public Charset getCharset() {
380        return this.charset;
381    }
382
383    /**
384     * Gets the default charset name used for string decoding and encoding.
385     *
386     * @return the default charset name
387     */
388    public String getDefaultCharset() {
389        return this.charset.name();
390    }
391
392    /**
393     * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
394     * <p>
395     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
396     * RFC 1521 and is suitable for encoding binary data and unformatted text.
397     *
398     * @param str
399     *            string to convert to quoted-printable form
400     * @param charset
401     *            the charset for str
402     * @return quoted-printable string
403     * @since 1.7
404     */
405    public String encode(final String str, final Charset charset) {
406        if (str == null) {
407            return null;
408        }
409        return StringUtils.newStringUsAscii(this.encode(str.getBytes(charset)));
410    }
411
412    /**
413     * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
414     * <p>
415     * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in
416     * RFC 1521 and is suitable for encoding binary data and unformatted text.
417     *
418     * @param str
419     *            string to convert to quoted-printable form
420     * @param charset
421     *            the charset for str
422     * @return quoted-printable string
423     * @throws UnsupportedEncodingException
424     *             Thrown if the charset is not supported
425     */
426    public String encode(final String str, final String charset) throws UnsupportedEncodingException {
427        if (str == null) {
428            return null;
429        }
430        return StringUtils.newStringUsAscii(encode(str.getBytes(charset)));
431    }
432}