    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.util.BitSet;
    023
    024import org.apache.commons.codec.Charsets;
    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 {@link #encodeBlanks} 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 * @version $Id: QCodec.java 1619948 2014-08-22 22:53:55Z ggregory $
    051 */
    052public class QCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
    053    /**
    054     * The default charset used for string decoding and encoding.
    055     */
    056    private final Charset charset;
    057
    058    /**
    059     * BitSet of printable characters as defined in RFC 1522.
    060     */
    061    private static final BitSet PRINTABLE_CHARS = new BitSet(256);
    062    // Static initializer for printable chars collection
    063    static {
    064        // alpha characters
    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        PRINTABLE_CHARS.set('/');
    081        for (int i = '0'; i <= '9'; i++) {
    082            PRINTABLE_CHARS.set(i);
    083        }
    084        PRINTABLE_CHARS.set(':');
    085        PRINTABLE_CHARS.set(';');
    086        PRINTABLE_CHARS.set('<');
    087        PRINTABLE_CHARS.set('>');
    088        PRINTABLE_CHARS.set('@');
    089        for (int i = 'A'; i <= 'Z'; i++) {
    090            PRINTABLE_CHARS.set(i);
    091        }
    092        PRINTABLE_CHARS.set('[');
    093        PRINTABLE_CHARS.set('\\');
    094        PRINTABLE_CHARS.set(']');
    095        PRINTABLE_CHARS.set('^');
    096        PRINTABLE_CHARS.set('`');
    097        for (int i = 'a'; i <= 'z'; i++) {
    098            PRINTABLE_CHARS.set(i);
    099        }
    100        PRINTABLE_CHARS.set('{');
    101        PRINTABLE_CHARS.set('|');
    102        PRINTABLE_CHARS.set('}');
    103        PRINTABLE_CHARS.set('~');
    104    }
    105
    106    private static final byte BLANK = 32;
    107
    108    private static final byte UNDERSCORE = 95;
    109
    110    private boolean encodeBlanks = false;
    111
    112    /**
    113     * Default constructor.
    114     */
    115    public QCodec() {
    116        this(Charsets.UTF_8);
    117    }
    118
    119    /**
    120     * Constructor which allows for the selection of a default charset.
    121     *
    122     * @param charset
    123     *            the default string charset to use.
    124     *
    125     * @see <a href="http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    126     * @since 1.7
    127     */
    128    public QCodec(final Charset charset) {
    129        super();
    130        this.charset = charset;
    131    }
    132
    133    /**
    134     * Constructor which allows for the selection of a default charset.
    135     *
    136     * @param charsetName
    137     *            the charset to use.
    138     * @throws java.nio.charset.UnsupportedCharsetException
    139     *             If the named charset is unavailable
    140     * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
    141     * @see <a href="http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    142     */
    143    public QCodec(final String charsetName) {
    144        this(Charset.forName(charsetName));
    145    }
    146
    147    @Override
    148    protected String getEncoding() {
    149        return "Q";
    150    }
    151
    152    @Override
    153    protected byte[] doEncoding(final byte[] bytes) {
    154        if (bytes == null) {
    155            return null;
    156        }
    157        final byte[] data = QuotedPrintableCodec.encodeQuotedPrintable(PRINTABLE_CHARS, bytes);
    158        if (this.encodeBlanks) {
    159            for (int i = 0; i < data.length; i++) {
    160                if (data[i] == BLANK) {
    161                    data[i] = UNDERSCORE;
    162                }
    163            }
    164        }
    165        return data;
    166    }
    167
    168    @Override
    169    protected byte[] doDecoding(final byte[] bytes) throws DecoderException {
    170        if (bytes == null) {
    171            return null;
    172        }
    173        boolean hasUnderscores = false;
    174        for (final byte b : bytes) {
    175            if (b == UNDERSCORE) {
    176                hasUnderscores = true;
    177                break;
    178            }
    179        }
    180        if (hasUnderscores) {
    181            final byte[] tmp = new byte[bytes.length];
    182            for (int i = 0; i < bytes.length; i++) {
    183                final byte b = bytes[i];
    184                if (b != UNDERSCORE) {
    185                    tmp[i] = b;
    186                } else {
    187                    tmp[i] = BLANK;
    188                }
    189            }
    190            return QuotedPrintableCodec.decodeQuotedPrintable(tmp);
    191        }
    192        return QuotedPrintableCodec.decodeQuotedPrintable(bytes);
    193    }
    194
    195    /**
    196     * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
    197     *
    198     * @param str
    199     *            string to convert to quoted-printable form
    200     * @param charset
    201     *            the charset for str
    202     * @return quoted-printable string
    203     * @throws EncoderException
    204     *             thrown if a failure condition is encountered during the encoding process.
    205     * @since 1.7
    206     */
    207    public String encode(final String str, final Charset charset) throws EncoderException {
    208        if (str == null) {
    209            return null;
    210        }
    211        return encodeText(str, charset);
    212    }
    213
    214    /**
    215     * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
    216     *
    217     * @param str
    218     *            string to convert to quoted-printable form
    219     * @param charset
    220     *            the charset for str
    221     * @return quoted-printable string
    222     * @throws EncoderException
    223     *             thrown if a failure condition is encountered during the encoding process.
    224     */
    225    public String encode(final String str, final String charset) throws EncoderException {
    226        if (str == null) {
    227            return null;
    228        }
    229        try {
    230            return encodeText(str, charset);
    231        } catch (final UnsupportedEncodingException e) {
    232            throw new EncoderException(e.getMessage(), e);
    233        }
    234    }
    235
    236    /**
    237     * Encodes a string into its quoted-printable form using the default charset. Unsafe characters are escaped.
    238     *
    239     * @param str
    240     *            string to convert to quoted-printable form
    241     * @return quoted-printable string
    242     * @throws EncoderException
    243     *             thrown if a failure condition is encountered during the encoding process.
    244     */
    245    @Override
    246    public String encode(final String str) throws EncoderException {
    247        if (str == null) {
    248            return null;
    249        }
    250        return encode(str, getCharset());
    251    }
    252
    253    /**
    254     * Decodes a quoted-printable string into its original form. Escaped characters are converted back to their original
    255     * representation.
    256     *
    257     * @param str
    258     *            quoted-printable string to convert into its original form
    259     * @return original string
    260     * @throws DecoderException
    261     *             A decoder exception is thrown if a failure condition is encountered during the decode process.
    262     */
    263    @Override
    264    public String decode(final String str) throws DecoderException {
    265        if (str == null) {
    266            return null;
    267        }
    268        try {
    269            return decodeText(str);
    270        } catch (final UnsupportedEncodingException e) {
    271            throw new DecoderException(e.getMessage(), e);
    272        }
    273    }
    274
    275    /**
    276     * Encodes an object into its quoted-printable form using the default charset. Unsafe characters are escaped.
    277     *
    278     * @param obj
    279     *            object to convert to quoted-printable form
    280     * @return quoted-printable object
    281     * @throws EncoderException
    282     *             thrown if a failure condition is encountered during the encoding process.
    283     */
    284    @Override
    285    public Object encode(final Object obj) throws EncoderException {
    286        if (obj == null) {
    287            return null;
    288        } else if (obj instanceof String) {
    289            return encode((String) obj);
    290        } else {
    291            throw new EncoderException("Objects of type " +
    292                  obj.getClass().getName() +
    293                  " cannot be encoded using Q codec");
    294        }
    295    }
    296
    297    /**
    298     * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original
    299     * representation.
    300     *
    301     * @param obj
    302     *            quoted-printable object to convert into its original form
    303     * @return original object
    304     * @throws DecoderException
    305     *             Thrown if the argument is not a <code>String</code>. Thrown if a failure condition is encountered
    306     *             during the decode process.
    307     */
    308    @Override
    309    public Object decode(final Object obj) throws DecoderException {
    310        if (obj == null) {
    311            return null;
    312        } else if (obj instanceof String) {
    313            return decode((String) obj);
    314        } else {
    315            throw new DecoderException("Objects of type " +
    316                  obj.getClass().getName() +
    317                  " cannot be decoded using Q codec");
    318        }
    319    }
    320
    321    /**
    322     * Gets the default charset name used for string decoding and encoding.
    323     *
    324     * @return the default charset name
    325     * @since 1.7
    326     */
    327    public Charset getCharset() {
    328        return this.charset;
    329    }
    330
    331    /**
    332     * Gets the default charset name used for string decoding and encoding.
    333     *
    334     * @return the default charset name
    335     */
    336    public String getDefaultCharset() {
    337        return this.charset.name();
    338    }
    339
    340    /**
    341     * Tests if optional transformation of SPACE characters is to be used
    342     *
    343     * @return <code>true</code> if SPACE characters are to be transformed, <code>false</code> otherwise
    344     */
    345    public boolean isEncodeBlanks() {
    346        return this.encodeBlanks;
    347    }
    348
    349    /**
    350     * Defines whether optional transformation of SPACE characters is to be used
    351     *
    352     * @param b
    353     *            <code>true</code> if SPACE characters are to be transformed, <code>false</code> otherwise
    354     */
    355    public void setEncodeBlanks(final boolean b) {
    356        this.encodeBlanks = b;
    357    }
    358}