/*
* 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 eu.europa.ec.markt.dss.utils;
import eu.europa.ec.markt.dss.DSSUtils;
import eu.europa.ec.markt.dss.exception.DSSException;
/**
* Abstract superclass for Base-N encoders and decoders.
*
* <p>
* This class is not thread-safe.
* Each thread should use its own instance.
* </p>
*/
public abstract class BaseNCodec implements BinaryEncoder, BinaryDecoder {
/**
* MIME chunk size per RFC 2045 section 6.8.
*
* <p>
* The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
* equal signs.
* </p>
*
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
*/
public static final int MIME_CHUNK_SIZE = 76;
/**
* PEM chunk size per RFC 1421 section 4.3.2.4.
*
* <p>
* The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
* equal signs.
* </p>
*
* @see <a href="http://tools.ietf.org/html/rfc1421">RFC 1421 section 4.3.2.4</a>
*/
public static final int PEM_CHUNK_SIZE = 64;
private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
/**
* Defines the default buffer size - currently {@value}
* - must be large enough for at least one encoded block+separator
*/
private static final int DEFAULT_BUFFER_SIZE = 8192;
/**
* Mask used to extract 8 bits, used in decoding bytes
*/
protected static final int MASK_8BITS = 0xff;
/**
* Byte used to pad output.
*/
protected static final byte PAD_DEFAULT = '='; // Allow static access to default
protected final byte PAD = PAD_DEFAULT; // instance variable just in case it needs to vary later
/**
* Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32
*/
private final int unencodedBlockSize;
/**
* Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32
*/
private final int encodedBlockSize;
/**
* Chunksize for encoding. Not used when decoding.
* A value of zero or less implies no chunking of the encoded data.
* Rounded down to nearest multiple of encodedBlockSize.
*/
protected final int lineLength;
/**
* Size of chunk separator. Not used unless {@link #lineLength} > 0.
*/
private final int chunkSeparatorLength;
/**
* Buffer for streaming.
*/
protected byte[] buffer;
/**
* Position where next character should be written in the buffer.
*/
protected int pos;
/**
* Position where next character should be read from the buffer.
*/
private int readPos;
/**
* Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless,
* and must be thrown away.
*/
protected boolean eof;
/**
* Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
* make sure each encoded line never goes beyond lineLength (if lineLength > 0).
*/
protected int currentLinePos;
/**
* Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding.
* This variable helps track that.
*/
protected int modulus;
/**
* Note <code>lineLength</code> is rounded down to the nearest multiple of {@link #encodedBlockSize}
* If <code>chunkSeparatorLength</code> is zero, then chunking is disabled.
*
* @param unencodedBlockSize the size of an unencoded block (e.g. Base64 = 3)
* @param encodedBlockSize the size of an encoded block (e.g. Base64 = 4)
* @param lineLength if > 0, use chunking with a length <code>lineLength</code>
* @param chunkSeparatorLength the chunk separator length, if relevant
*/
protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength) {
this.unencodedBlockSize = unencodedBlockSize;
this.encodedBlockSize = encodedBlockSize;
this.lineLength = (lineLength > 0 && chunkSeparatorLength > 0) ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;
this.chunkSeparatorLength = chunkSeparatorLength;
}
/**
* Returns the amount of buffered data available for reading.
*
* @return The amount of buffered data available for reading.
*/
int available() { // package protected for access from I/O streams
return buffer != null ? pos - readPos : 0;
}
/**
* Get the default buffer size. Can be overridden.
*
* @return {@link #DEFAULT_BUFFER_SIZE}
*/
protected int getDefaultBufferSize() {
return DEFAULT_BUFFER_SIZE;
}
/**
* Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
*/
private void resizeBuffer() {
if (buffer == null) {
buffer = new byte[getDefaultBufferSize()];
pos = 0;
readPos = 0;
} else {
byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
System.arraycopy(buffer, 0, b, 0, buffer.length);
buffer = b;
}
}
/**
* Ensure that the buffer has room for <code>size</code> bytes
*
* @param size minimum spare space required
*/
protected void ensureBufferSize(int size) {
if ((buffer == null) || (buffer.length < pos + size)) {
resizeBuffer();
}
}
/**
* Extracts buffered data into the provided byte[] array, starting at position bPos,
* up to a maximum of bAvail bytes. Returns how many bytes were actually extracted.
*
* @param b byte[] array to extract the buffered data into.
* @param bPos position in byte[] array to start extraction at.
* @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
* @return The number of bytes successfully extracted into the provided byte[] array.
*/
int readResults(byte[] b, int bPos, int bAvail) { // package protected for access from I/O streams
if (buffer != null) {
int len = Math.min(available(), bAvail);
System.arraycopy(buffer, readPos, b, bPos, len);
readPos += len;
if (readPos >= pos) {
buffer = null; // so hasData() will return false, and this method can return -1
}
return len;
}
return eof ? -1 : 0;
}
/**
* Resets this object to its initial newly constructed state.
*/
private void reset() {
buffer = null;
pos = 0;
readPos = 0;
currentLinePos = 0;
modulus = 0;
eof = false;
}
/**
* Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the
* Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
*
* @param pObject Object to encode
* @return An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.
* @throws DSSException if the parameter supplied is not of type byte[]
*/
public Object encode(Object pObject) throws DSSException {
if (!(pObject instanceof byte[])) {
throw new DSSException("Parameter supplied to Base-N encode is not a byte[]");
}
return encode((byte[]) pObject);
}
/**
* Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the
* Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
*
* @param pObject Object to decode
* @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String supplied.
* @throws DSSException if the parameter supplied is not of type byte[]
*/
public Object decode(Object pObject) throws DSSException {
if (pObject instanceof byte[]) {
return decode((byte[]) pObject);
} else if (pObject instanceof String) {
return decode((String) pObject);
} else {
throw new DSSException("Parameter supplied to Base-N decode is not a byte[] or a String");
}
}
/**
* Decodes a String containing characters in the Base-N alphabet.
*
* @param pArray A String containing Base-N character data
* @return a byte array containing binary data
*/
public byte[] decode(String pArray) {
return decode(DSSUtils.getUtf8Bytes(pArray));
}
/**
* Decodes a byte[] containing characters in the Base-N alphabet.
*
* @param pArray A byte array containing Base-N character data
* @return a byte array containing binary data
*/
public byte[] decode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
decode(pArray, 0, pArray.length);
decode(pArray, 0, -1); // Notify decoder of EOF.
byte[] result = new byte[pos];
readResults(result, 0, result.length);
return result;
}
/**
* Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
*
* @param pArray a byte array containing binary data
* @return A byte array containing only the basen alphabetic character data
*/
public byte[] encode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
encode(pArray, 0, pArray.length);
encode(pArray, 0, -1); // Notify encoder of EOF.
byte[] buf = new byte[pos - readPos];
readResults(buf, 0, buf.length);
return buf;
}
abstract void encode(byte[] pArray, int i, int length); // package protected for access from I/O streams
abstract void decode(byte[] pArray, int i, int length); // package protected for access from I/O streams
/**
* Returns whether or not the <code>octet</code> is in the current alphabet.
* Does not allow whitespace or pad.
*
* @param value The value to test
* @return <code>true</code> if the value is defined in the current alphabet, <code>false</code> otherwise.
*/
protected abstract boolean isInAlphabet(byte value);
/**
* Tests a given byte array to see if it contains any characters within the alphabet or PAD.
*
* Intended for use in checking line-ending arrays
*
* @param arrayOctet byte array to test
* @return <code>true</code> if any byte is a valid character in the alphabet or PAD; <code>false</code> otherwise
*/
protected boolean containsAlphabetOrPad(byte[] arrayOctet) {
if (arrayOctet == null) {
return false;
}
for (byte element : arrayOctet) {
if (PAD == element || isInAlphabet(element)) {
return true;
}
}
return false;
}
/**
* Calculates the amount of space needed to encode the supplied array.
*
* @param pArray byte[] array which will later be encoded
* @return amount of space needed to encoded the supplied array.
* Returns a long since a max-len array will require > Integer.MAX_VALUE
*/
public long getEncodedLength(byte[] pArray) {
// Calculate non-chunked size - rounded up to allow for padding
// cast to long is needed to avoid possibility of overflow
long len = ((pArray.length + unencodedBlockSize - 1) / unencodedBlockSize) * (long) encodedBlockSize;
if (lineLength > 0) { // We're using chunking
// Round up to nearest multiple
len += ((len + lineLength - 1) / lineLength) * chunkSeparatorLength;
}
return len;
}
}