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