QuotedPrintableCodec.java
/*
* 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.UnsupportedCharsetException;
import java.util.BitSet;
import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.Charsets;
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 <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>.
* <p>
* 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.
* <p>
* Note:
* <p>
* Depending on the selected {@code strict} parameter, this class will implement a different set of rules of the
* quoted-printable spec:
* <ul>
* <li>{@code strict=false}: only rules #1 and #2 are implemented
* <li>{@code strict=true}: all rules #1 through #5 are implemented
* </ul>
* 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.
* <p>
* This class is immutable and thread-safe.
*
* @see <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521 MIME (Multipurpose Internet Mail Extensions) Part One:
* Mechanisms for Specifying and Describing the Format of Internet Message Bodies </a>
*
* @since 1.3
* @version $Id: QuotedPrintableCodec.java 1788792 2017-03-26 23:57:00Z sebb $
*/
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 Charsets#UTF_8}
*/
public QuotedPrintableCodec() {
this(Charsets.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(Charsets.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</code>
*/
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</code> 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</code> 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</code> 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.
* <p>
* 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.
* <p>
* 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.
* <p>
* 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.
* <p>
* 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.
* <p>
* 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.
* <p>
* 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 str
* 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 str) throws EncoderException {
return this.encode(str, 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 str
* quoted-printable string to convert into its original form
* @param charset
* the original string charset
* @return original string
* @throws DecoderException
* Thrown if quoted-printable decoding is unsuccessful
* @since 1.7
*/
public String decode(final String str, final Charset charset) throws DecoderException {
if (str == null) {
return null;
}
return new String(this.decode(StringUtils.getBytesUsAscii(str)), charset);
}
/**
* Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters
* are converted back to their original representation.
*
* @param str
* quoted-printable string to convert into its original form
* @param charset
* 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 str, final String charset) throws DecoderException, UnsupportedEncodingException {
if (str == null) {
return null;
}
return new String(decode(StringUtils.getBytesUsAscii(str)), charset);
}
/**
* Decodes a quoted-printable string into its original form using the default string charset. Escaped characters are
* converted back to their original representation.
*
* @param str
* 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 str) throws DecoderException {
return this.decode(str, 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</code> or <code>byte[]</code>. 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.
* <p>
* 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 str
* string to convert to quoted-printable form
* @param charset
* the charset for str
* @return quoted-printable string
* @since 1.7
*/
public String encode(final String str, final Charset charset) {
if (str == null) {
return null;
}
return StringUtils.newStringUsAscii(this.encode(str.getBytes(charset)));
}
/**
* Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
* <p>
* 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 str
* string to convert to quoted-printable form
* @param charset
* the charset for str
* @return quoted-printable string
* @throws UnsupportedEncodingException
* Thrown if the charset is not supported
*/
public String encode(final String str, final String charset) throws UnsupportedEncodingException {
if (str == null) {
return null;
}
return StringUtils.newStringUsAscii(encode(str.getBytes(charset)));
}
}