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/*
* Copyright (c) 2008, Harald Kuhr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.twelvemonkeys.io.enc;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
/**
* {@code Decoder} implementation for standard base64 encoding.
*
* @see RFC 1421
* @see RFC 2045
*
* @see Base64Encoder
*
* @author Harald Kuhr
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/enc/Base64Decoder.java#2 $
*/
public final class Base64Decoder implements Decoder {
/**
* This array maps the characters to their 6 bit values
*/
final static byte[] PEM_ARRAY = {
//0 1 2 3 4 5 6 7
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 0
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 1
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 2
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // 3
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 4
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // 5
'w', 'x', 'y', 'z', '0', '1', '2', '3', // 6
'4', '5', '6', '7', '8', '9', '+', '/' // 7
};
final static byte[] PEM_CONVERT_ARRAY;
private byte[] decodeBuffer = new byte[4];
static {
PEM_CONVERT_ARRAY = new byte[256];
for (int i = 0; i < 255; i++) {
PEM_CONVERT_ARRAY[i] = -1;
}
for (int i = 0; i < PEM_ARRAY.length; i++) {
PEM_CONVERT_ARRAY[PEM_ARRAY[i]] = (byte) i;
}
}
protected static int readFully(final InputStream pStream, final byte pBytes[], final int pOffset, final int pLength)
throws IOException
{
for (int i = 0; i < pLength; i++) {
int read = pStream.read();
if (read == -1) {
return i != 0 ? i : -1;
}
pBytes[i + pOffset] = (byte) read;
}
return pLength;
}
protected boolean decodeAtom(final InputStream pInput, final ByteBuffer pOutput, final int pLength)
throws IOException {
byte byte0 = -1;
byte byte1 = -1;
byte byte2 = -1;
byte byte3 = -1;
if (pLength < 2) {
throw new IOException("BASE64Decoder: Not enough bytes for an atom.");
}
int read;
// Skip line feeds
do {
read = pInput.read();
if (read == -1) {
return false;
}
} while (read == 10 || read == 13);
decodeBuffer[0] = (byte) read;
read = readFully(pInput, decodeBuffer, 1, pLength - 1);
if (read == -1) {
return false;
}
int length = pLength;
if (length > 3 && decodeBuffer[3] == 61) {
length = 3;
}
if (length > 2 && decodeBuffer[2] == 61) {
length = 2;
}
switch (length) {
case 4:
byte3 = PEM_CONVERT_ARRAY[decodeBuffer[3] & 255];
// fall through
case 3:
byte2 = PEM_CONVERT_ARRAY[decodeBuffer[2] & 255];
// fall through
case 2:
byte1 = PEM_CONVERT_ARRAY[decodeBuffer[1] & 255];
byte0 = PEM_CONVERT_ARRAY[decodeBuffer[0] & 255];
// fall through
default:
switch (length) {
case 2:
pOutput.put((byte) (byte0 << 2 & 252 | byte1 >>> 4 & 3));
break;
case 3:
pOutput.put((byte) (byte0 << 2 & 252 | byte1 >>> 4 & 3));
pOutput.put((byte) (byte1 << 4 & 240 | byte2 >>> 2 & 15));
break;
case 4:
pOutput.put((byte) (byte0 << 2 & 252 | byte1 >>> 4 & 3));
pOutput.put((byte) (byte1 << 4 & 240 | byte2 >>> 2 & 15));
pOutput.put((byte) (byte2 << 6 & 192 | byte3 & 63));
break;
}
break;
}
return true;
}
public int decode(final InputStream stream, final ByteBuffer buffer) throws IOException {
do {
int k = 72;
int i;
for (i = 0; i + 4 < k; i += 4) {
if(!decodeAtom(stream, buffer, 4)) {
break;
}
}
if (!decodeAtom(stream, buffer, k - i)) {
break;
}
}
while (buffer.remaining() > 54); // 72 char lines should produce no more than 54 bytes
return buffer.position();
}
}
