panda.codec.net.QuotedPrintableCodec Maven / Gradle / Ivy
package panda.codec.net;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.BitSet;
import panda.codec.BinaryDecoder;
import panda.codec.BinaryEncoder;
import panda.codec.DecoderException;
import panda.codec.EncoderException;
import panda.codec.StringDecoder;
import panda.codec.StringEncoder;
import panda.io.stream.ByteArrayOutputStream;
import panda.lang.Charsets;
import panda.lang.Strings;
/**
* 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
*/
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.CS_UTF_8, false);
}
/**
* Constructor which allows for the selection of the strict mode.
*
* @param strict if {@code true}, soft line breaks will be used
*/
public QuotedPrintableCodec(final boolean strict) {
this(Charsets.CS_UTF_8, strict);
}
/**
* Constructor which allows for the selection of a default charset.
*
* @param charset the default string charset to use.
*/
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
*/
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
*/
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 buffer
*/
private static final int encodeQuotedPrintable(final int b, final ByteArrayOutputStream buffer) {
buffer.write(ESCAPE_CHAR);
final char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, 16));
final char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, 16));
buffer.write(hex1);
buffer.write(hex2);
return 3;
}
/**
* Return the byte at position 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 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 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
*/
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;
}
@SuppressWarnings("resource")
final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int len = bytes.length;
for (int i = 0; i < len; i++) {
final int b = bytes[i];
if (b == ESCAPE_CHAR) {
if (i + 2 >= len) {
throw new DecoderException("Invalid quoted printable encoding; truncated escape sequence");
}
byte b1 = bytes[++i];
// if the next octet is a CR we have found a soft line break
if (b1 == CR) {
continue;
}
byte b2 = bytes[++i];
final int u = Utils.digit16(b1);
final int l = Utils.digit16(b2);
buffer.write((char)((u << 4) + l));
}
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 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
*/
public String decode(final String str, final Charset charset) throws DecoderException {
if (str == null) {
return null;
}
return new String(this.decode(Strings.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(Strings.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 String or
* 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
*/
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 str string to convert to quoted-printable form
* @param charset the charset for str
* @return quoted-printable string
*/
public String encode(final String str, final Charset charset) {
if (str == null) {
return null;
}
return Strings.newStringUsAscii(this.encode(str.getBytes(charset)));
}
/**
* 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 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 Strings.newStringUsAscii(encode(str.getBytes(charset)));
}
}