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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).
/*
* Copyright 2013-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.util;
import static com.amazonaws.util.CodecUtils.sanityCheckLastPos;
/**
* A Base 64 codec implementation.
*
* @author Hanson Char
*/
class Base64Codec implements Codec {
private static final int OFFSET_OF_a = 'a' - 26;
private static final int OFFSET_OF_0 = '0' - 52;
private static final int OFFSET_OF_PLUS = '+' - 62;
private static final int OFFSET_OF_SLASH = '/' - 63;
private static final int MASK_2BITS = (1 << 2) - 1;
private static final int MASK_4BITS = (1 << 4) - 1;
private static final int MASK_6BITS = (1 << 6) - 1;
// Alphabet as defined at http://www.ietf.org/rfc/rfc4648.txt
private static final byte PAD = '=';
private static class LazyHolder {
private static final byte[] DECODED = decodeTable();
private static byte[] decodeTable() {
final byte[] dest = new byte['z'+1];
for (int i=0; i <= 'z'; i++)
{
if (i >= 'A' && i <= 'Z')
dest[i] = (byte)(i - 'A');
else if (i >= '0' && i <= '9')
dest[i] = (byte)(i - OFFSET_OF_0);
else if (i == '+')
dest[i] = (byte)(i - OFFSET_OF_PLUS);
else if (i == '/')
dest[i] = (byte)(i - OFFSET_OF_SLASH);
else if (i >= 'a' && i <= 'z')
dest[i] = (byte)(i - OFFSET_OF_a);
else
dest[i] = -1;
}
return dest;
}
}
private final byte[] alphabets;
Base64Codec() {
this.alphabets = CodecUtils.toBytesDirect("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
}
protected Base64Codec(byte[] alphabets) {
this.alphabets = alphabets;
}
@Override
public byte[] encode(byte[] src) {
final int num3bytes = src.length / 3;
final int remainder = src.length % 3;
if (remainder == 0)
{
byte[] dest = new byte[num3bytes * 4];
for (int s=0,d=0; s < src.length; s+=3, d+=4)
encode3bytes(src, s, dest, d);
return dest;
}
byte[] dest = new byte[(num3bytes+1) * 4];
int s=0, d=0;
for (; s < src.length-remainder; s+=3, d+=4)
encode3bytes(src, s, dest, d);
switch(remainder) {
case 1:
encode1byte(src, s, dest, d);
break;
case 2:
encode2bytes(src, s, dest, d);
break;
default:
throw new IllegalStateException();
}
return dest;
}
void encode3bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 2 & MASK_6BITS]; // 6
dest[d++] = (byte)alphabets[(p & MASK_2BITS) << 4 | (p=src[s++]) >>> 4 & MASK_4BITS]; // 2 4
dest[d++] = (byte)alphabets[(p & MASK_4BITS) << 2 | (p=src[s]) >>> 6 & MASK_2BITS]; // 4 2
dest[d] = (byte)alphabets[p & MASK_6BITS]; // 6
return;
}
void encode2bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 2 & MASK_6BITS]; // 6
dest[d++] = (byte)alphabets[(p & MASK_2BITS) << 4 | (p=src[s]) >>> 4 & MASK_4BITS]; // 2 4
dest[d++] = (byte)alphabets[(p & MASK_4BITS) << 2]; // 4
dest[d] = PAD;
return;
}
void encode1byte(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s]) >>> 2 & MASK_6BITS]; // 6
dest[d++] = (byte)alphabets[(p & MASK_2BITS) << 4]; // 2
dest[d++] = PAD;
dest[d] = PAD;
return;
}
void decode4bytes(byte[] src, int s, byte[] dest, int d) {
int p=0;
// operator precedence in descending order: >>> or <<, &, |
dest[d++] = (byte)
(
pos(src[s++]) << 2
| (p=pos(src[s++])) >>> 4 & MASK_2BITS
)
; // 6 2
dest[d++] = (byte)
(
(p & MASK_4BITS) << 4
| (p=pos(src[s++])) >>> 2 & MASK_4BITS
)
; // 4 4
dest[d] = (byte)
(
(p & MASK_2BITS) << 6
| pos(src[s])
)
; // 2 6
return;
}
/**
* @param n the number of final quantum in bytes to decode into. Ranges from 1 to 3, inclusive.
*/
void decode1to3bytes(int n, byte[] src, int s, byte[] dest, int d) {
int p=0;
// operator precedence in descending order: >>> or <<, &, |
dest[d++] = (byte)
(
pos(src[s++]) << 2
| (p=pos(src[s++])) >>> 4 & MASK_2BITS
)
; // 6 2
if (n == 1) {
sanityCheckLastPos(p, MASK_4BITS);
return;
}
dest[d++] = (byte)
(
(p & MASK_4BITS) << 4
| (p=pos(src[s++])) >>> 2 & MASK_4BITS
)
; // 4 4
if (n == 2) {
sanityCheckLastPos(p, MASK_2BITS);
return;
}
dest[d] = (byte)
(
(p & MASK_2BITS) << 6
| pos(src[s])
)
; // 2 6
return;
}
@Override
public byte[] decode(byte[] src, final int length)
{
if (length % 4 != 0)
throw new IllegalArgumentException
("Input is expected to be encoded in multiple of 4 bytes but found: " + length);
int pads=0;
int last = length-1;
// max possible padding in b64 encoding is 2
for (; pads < 2 && last > -1; last--, pads++) {
if (src[last] != PAD)
break;
}
final int fq; // final quantum in unit of bytes
switch(pads) {
case 0:
fq=3;
break; // final quantum of encoding input is an integral multiple of 24 bits
case 1:
fq=2;
break; // final quantum of encoding input is exactly 16 bits
case 2:
fq=1;
break; // final quantum of encoding input is exactly 8 bits
default:
throw new Error("Impossible");
}
final byte[] dest = new byte[length / 4 * 3 - (3-fq)];
int s=0, d=0;
// % has a higher precedence than - than <
for (; d < dest.length - fq%3; s+=4,d+=3)
decode4bytes(src, s, dest, d);
if (fq < 3)
decode1to3bytes(fq, src, s, dest, d);
return dest;
}
protected int pos(byte in) {
int pos = LazyHolder.DECODED[in];
if (pos > -1)
return pos;
throw new IllegalArgumentException("Invalid base 64 character: \'" + (char)in + "\'");
}
}
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