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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.codec.net;

import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.StandardCharsets;
import java.nio.charset.UnsupportedCharsetException;
import java.util.BitSet;

import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;
import org.apache.commons.codec.StringDecoder;
import org.apache.commons.codec.StringEncoder;
import org.apache.commons.codec.binary.StringUtils;

/**
 * Codec for the Quoted-Printable section of RFC 1521.
 * 

* The Quoted-Printable encoding is intended to represent data that largely consists of octets that correspond to * printable characters in the ASCII character set. It encodes the data in such a way that the resulting octets are * unlikely to be modified by mail transport. If the data being encoded are mostly ASCII text, the encoded form of the * data remains largely recognizable by humans. A body which is entirely ASCII may also be encoded in Quoted-Printable * to ensure the integrity of the data should the message pass through a character- translating, and/or line-wrapping * gateway. *

*

* Note: *

*

* Depending on the selected {@code strict} parameter, this class will implement a different set of rules of the * quoted-printable spec: *

*
    *
  • {@code strict=false}: only rules #1 and #2 are implemented
  • *
  • {@code strict=true}: all rules #1 through #5 are implemented
  • *
*

* Originally, this class only supported the non-strict mode, but the codec in this partial form could already be used * for certain applications that do not require quoted-printable line formatting (rules #3, #4, #5), for instance * Q codec. The strict mode has been added in 1.10. *

*

* This class is immutable and thread-safe. *

* * @see RFC 1521 MIME (Multipurpose Internet Mail Extensions) Part One: * Mechanisms for Specifying and Describing the Format of Internet Message Bodies * * @since 1.3 */ public class QuotedPrintableCodec implements BinaryEncoder, BinaryDecoder, StringEncoder, StringDecoder { /** * The default Charset used for string decoding and encoding. */ private final Charset charset; /** * Indicates whether soft line breaks shall be used during encoding (rule #3-5). */ private final boolean strict; /** * BitSet of printable characters as defined in RFC 1521. */ private static final BitSet PRINTABLE_CHARS = new BitSet(256); private static final byte ESCAPE_CHAR = '='; private static final byte TAB = 9; private static final byte SPACE = 32; private static final byte CR = 13; private static final byte LF = 10; /** * Safe line length for quoted printable encoded text. */ private static final int SAFE_LENGTH = 73; // Static initializer for printable chars collection static { // alpha characters for (int i = 33; i <= 60; i++) { PRINTABLE_CHARS.set(i); } for (int i = 62; i <= 126; i++) { PRINTABLE_CHARS.set(i); } PRINTABLE_CHARS.set(TAB); PRINTABLE_CHARS.set(SPACE); } /** * Default constructor, assumes default Charset of {@link StandardCharsets#UTF_8} */ public QuotedPrintableCodec() { this(StandardCharsets.UTF_8, false); } /** * Constructor which allows for the selection of the strict mode. * * @param strict * if {@code true}, soft line breaks will be used * @since 1.10 */ public QuotedPrintableCodec(final boolean strict) { this(StandardCharsets.UTF_8, strict); } /** * Constructor which allows for the selection of a default Charset. * * @param charset * the default string Charset to use. * @since 1.7 */ public QuotedPrintableCodec(final Charset charset) { this(charset, false); } /** * Constructor which allows for the selection of a default Charset and strict mode. * * @param charset * the default string Charset to use. * @param strict * if {@code true}, soft line breaks will be used * @since 1.10 */ public QuotedPrintableCodec(final Charset charset, final boolean strict) { this.charset = charset; this.strict = strict; } /** * Constructor which allows for the selection of a default Charset. * * @param charsetName * the default string Charset to use. * @throws UnsupportedCharsetException * If no support for the named Charset is available * in this instance of the Java virtual machine * @throws IllegalArgumentException * If the given charsetName is null * @throws IllegalCharsetNameException * If the given Charset name is illegal * * @since 1.7 throws UnsupportedCharsetException if the named Charset is unavailable */ public QuotedPrintableCodec(final String charsetName) throws IllegalCharsetNameException, IllegalArgumentException, UnsupportedCharsetException { this(Charset.forName(charsetName), false); } /** * Encodes byte into its quoted-printable representation. * * @param b * byte to encode * @param buffer * the buffer to write to * @return The number of bytes written to the {@code buffer} */ private static final int encodeQuotedPrintable(final int b, final ByteArrayOutputStream buffer) { buffer.write(ESCAPE_CHAR); final char hex1 = Utils.hexDigit(b >> 4); final char hex2 = Utils.hexDigit(b); buffer.write(hex1); buffer.write(hex2); return 3; } /** * Return the byte at position {@code index} of the byte array and * make sure it is unsigned. * * @param index * position in the array * @param bytes * the byte array * @return the unsigned octet at position {@code index} from the array */ private static int getUnsignedOctet(final int index, final byte[] bytes) { int b = bytes[index]; if (b < 0) { b = 256 + b; } return b; } /** * Write a byte to the buffer. * * @param b * byte to write * @param encode * indicates whether the octet shall be encoded * @param buffer * the buffer to write to * @return the number of bytes that have been written to the buffer */ private static int encodeByte(final int b, final boolean encode, final ByteArrayOutputStream buffer) { if (encode) { return encodeQuotedPrintable(b, buffer); } buffer.write(b); return 1; } /** * Checks whether the given byte is whitespace. * * @param b * byte to be checked * @return {@code true} if the byte is either a space or tab character */ private static boolean isWhitespace(final int b) { return b == SPACE || b == TAB; } /** * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped. *

* This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param printable * bitset of characters deemed quoted-printable * @param bytes * array of bytes to be encoded * @return array of bytes containing quoted-printable data */ public static final byte[] encodeQuotedPrintable(final BitSet printable, final byte[] bytes) { return encodeQuotedPrintable(printable, bytes, false); } /** * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped. *

* Depending on the selection of the {@code strict} parameter, this function either implements the full ruleset * or only a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param printable * bitset of characters deemed quoted-printable * @param bytes * array of bytes to be encoded * @param strict * if {@code true} the full ruleset is used, otherwise only rule #1 and rule #2 * @return array of bytes containing quoted-printable data * @since 1.10 */ public static final byte[] encodeQuotedPrintable(BitSet printable, final byte[] bytes, final boolean strict) { if (bytes == null) { return null; } if (printable == null) { printable = PRINTABLE_CHARS; } final ByteArrayOutputStream buffer = new ByteArrayOutputStream(); if (strict) { int pos = 1; // encode up to buffer.length - 3, the last three octets will be treated // separately for simplification of note #3 for (int i = 0; i < bytes.length - 3; i++) { final int b = getUnsignedOctet(i, bytes); if (pos < SAFE_LENGTH) { // up to this length it is safe to add any byte, encoded or not pos += encodeByte(b, !printable.get(b), buffer); } else { // rule #3: whitespace at the end of a line *must* be encoded encodeByte(b, !printable.get(b) || isWhitespace(b), buffer); // rule #5: soft line break buffer.write(ESCAPE_CHAR); buffer.write(CR); buffer.write(LF); pos = 1; } } // rule #3: whitespace at the end of a line *must* be encoded // if we would do a soft break line after this octet, encode whitespace int b = getUnsignedOctet(bytes.length - 3, bytes); boolean encode = !printable.get(b) || (isWhitespace(b) && pos > SAFE_LENGTH - 5); pos += encodeByte(b, encode, buffer); // note #3: '=' *must not* be the ultimate or penultimate character // simplification: if < 6 bytes left, do a soft line break as we may need // exactly 6 bytes space for the last 2 bytes if (pos > SAFE_LENGTH - 2) { buffer.write(ESCAPE_CHAR); buffer.write(CR); buffer.write(LF); } for (int i = bytes.length - 2; i < bytes.length; i++) { b = getUnsignedOctet(i, bytes); // rule #3: trailing whitespace shall be encoded encode = !printable.get(b) || (i > bytes.length - 2 && isWhitespace(b)); encodeByte(b, encode, buffer); } } else { for (final byte c : bytes) { int b = c; if (b < 0) { b = 256 + b; } if (printable.get(b)) { buffer.write(b); } else { encodeQuotedPrintable(b, buffer); } } } return buffer.toByteArray(); } /** * Decodes an array quoted-printable characters into an array of original bytes. Escaped characters are converted * back to their original representation. *

* This function fully implements the quoted-printable encoding specification (rule #1 through rule #5) as * defined in RFC 1521. * * @param bytes * array of quoted-printable characters * @return array of original bytes * @throws DecoderException * Thrown if quoted-printable decoding is unsuccessful */ public static final byte[] decodeQuotedPrintable(final byte[] bytes) throws DecoderException { if (bytes == null) { return null; } final ByteArrayOutputStream buffer = new ByteArrayOutputStream(); for (int i = 0; i < bytes.length; i++) { final int b = bytes[i]; if (b == ESCAPE_CHAR) { try { // if the next octet is a CR we have found a soft line break if (bytes[++i] == CR) { continue; } final int u = Utils.digit16(bytes[i]); final int l = Utils.digit16(bytes[++i]); buffer.write((char) ((u << 4) + l)); } catch (final ArrayIndexOutOfBoundsException e) { throw new DecoderException("Invalid quoted-printable encoding", e); } } else if (b != CR && b != LF) { // every other octet is appended except for CR & LF buffer.write(b); } } return buffer.toByteArray(); } /** * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped. *

* Depending on the selection of the {@code strict} parameter, this function either implements the full ruleset * or only a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param bytes * array of bytes to be encoded * @return array of bytes containing quoted-printable data */ @Override public byte[] encode(final byte[] bytes) { return encodeQuotedPrintable(PRINTABLE_CHARS, bytes, strict); } /** * Decodes an array of quoted-printable characters into an array of original bytes. Escaped characters are converted * back to their original representation. *

* This function fully implements the quoted-printable encoding specification (rule #1 through rule #5) as * defined in RFC 1521. * * @param bytes * array of quoted-printable characters * @return array of original bytes * @throws DecoderException * Thrown if quoted-printable decoding is unsuccessful */ @Override public byte[] decode(final byte[] bytes) throws DecoderException { return decodeQuotedPrintable(bytes); } /** * Encodes a string into its quoted-printable form using the default string Charset. Unsafe characters are escaped. *

* Depending on the selection of the {@code strict} parameter, this function either implements the full ruleset * or only a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param sourceStr * string to convert to quoted-printable form * @return quoted-printable string * @throws EncoderException * Thrown if quoted-printable encoding is unsuccessful * * @see #getCharset() */ @Override public String encode(final String sourceStr) throws EncoderException { return this.encode(sourceStr, getCharset()); } /** * Decodes a quoted-printable string into its original form using the specified string Charset. Escaped characters * are converted back to their original representation. * * @param sourceStr * quoted-printable string to convert into its original form * @param sourceCharset * the original string Charset * @return original string * @throws DecoderException * Thrown if quoted-printable decoding is unsuccessful * @since 1.7 */ public String decode(final String sourceStr, final Charset sourceCharset) throws DecoderException { if (sourceStr == null) { return null; } return new String(this.decode(StringUtils.getBytesUsAscii(sourceStr)), sourceCharset); } /** * Decodes a quoted-printable string into its original form using the specified string Charset. Escaped characters * are converted back to their original representation. * * @param sourceStr * quoted-printable string to convert into its original form * @param sourceCharset * the original string Charset * @return original string * @throws DecoderException * Thrown if quoted-printable decoding is unsuccessful * @throws UnsupportedEncodingException * Thrown if Charset is not supported */ public String decode(final String sourceStr, final String sourceCharset) throws DecoderException, UnsupportedEncodingException { if (sourceStr == null) { return null; } return new String(decode(StringUtils.getBytesUsAscii(sourceStr)), sourceCharset); } /** * Decodes a quoted-printable string into its original form using the default string Charset. Escaped characters are * converted back to their original representation. * * @param sourceStr * quoted-printable string to convert into its original form * @return original string * @throws DecoderException * Thrown if quoted-printable decoding is unsuccessful. Thrown if Charset is not supported. * @see #getCharset() */ @Override public String decode(final String sourceStr) throws DecoderException { return this.decode(sourceStr, this.getCharset()); } /** * Encodes an object into its quoted-printable safe form. Unsafe characters are escaped. * * @param obj * string to convert to a quoted-printable form * @return quoted-printable object * @throws EncoderException * Thrown if quoted-printable encoding is not applicable to objects of this type or if encoding is * unsuccessful */ @Override public Object encode(final Object obj) throws EncoderException { if (obj == null) { return null; } else if (obj instanceof byte[]) { return encode((byte[]) obj); } else if (obj instanceof String) { return encode((String) obj); } else { throw new EncoderException("Objects of type " + obj.getClass().getName() + " cannot be quoted-printable encoded"); } } /** * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original * representation. * * @param obj * quoted-printable object to convert into its original form * @return original object * @throws DecoderException * Thrown if the argument is not a {@code String} or {@code byte[]}. Thrown if a failure * condition is encountered during the decode process. */ @Override public Object decode(final Object obj) throws DecoderException { if (obj == null) { return null; } else if (obj instanceof byte[]) { return decode((byte[]) obj); } else if (obj instanceof String) { return decode((String) obj); } else { throw new DecoderException("Objects of type " + obj.getClass().getName() + " cannot be quoted-printable decoded"); } } /** * Gets the default Charset name used for string decoding and encoding. * * @return the default Charset name * @since 1.7 */ public Charset getCharset() { return this.charset; } /** * Gets the default Charset name used for string decoding and encoding. * * @return the default Charset name */ public String getDefaultCharset() { return this.charset.name(); } /** * Encodes a string into its quoted-printable form using the specified Charset. Unsafe characters are escaped. *

* Depending on the selection of the {@code strict} parameter, this function either implements the full ruleset * or only a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param sourceStr * string to convert to quoted-printable form * @param sourceCharset * the Charset for sourceStr * @return quoted-printable string * @since 1.7 */ public String encode(final String sourceStr, final Charset sourceCharset) { if (sourceStr == null) { return null; } return StringUtils.newStringUsAscii(this.encode(sourceStr.getBytes(sourceCharset))); } /** * Encodes a string into its quoted-printable form using the specified Charset. Unsafe characters are escaped. *

* Depending on the selection of the {@code strict} parameter, this function either implements the full ruleset * or only a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in * RFC 1521 and is suitable for encoding binary data and unformatted text. * * @param sourceStr * string to convert to quoted-printable form * @param sourceCharset * the Charset for sourceStr * @return quoted-printable string * @throws UnsupportedEncodingException * Thrown if the Charset is not supported */ public String encode(final String sourceStr, final String sourceCharset) throws UnsupportedEncodingException { if (sourceStr == null) { return null; } return StringUtils.newStringUsAscii(encode(sourceStr.getBytes(sourceCharset))); } }





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