/*******************************************************************************
* Copyright (c) 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Zend Technologies
*******************************************************************************/
package org.eclipse.php.internal.debug.core.xdebug.dbgp.protocol;
import java.io.UnsupportedEncodingException;
/* Base64 definition
5.2. Base64 Content-Transfer-Encoding
The Base64 Content-Transfer-Encoding is designed to represent
arbitrary sequences of octets in a form that need not be humanly
readable. The encoding and decoding algorithms are simple, but the
encoded data are consistently only about 33 percent larger than the
unencoded data. This encoding is virtually identical to the one used
in Privacy Enhanced Mail (PEM) applications, as defined in RFC 1421.
The base64 encoding is adapted from RFC 1421, with one change: base64
eliminates the "*" mechanism for embedded clear text.
A 65-character subset of US-ASCII is used, enabling 6 bits to be
represented per printable character. (The extra 65th character, "=",
is used to signify a special processing function.)
NOTE: This subset has the important property that it is
represented identically in all versions of ISO 646, including US
ASCII, and all characters in the subset are also represented
identically in all versions of EBCDIC. Other popular encodings,
such as the encoding used by the uuencode utility and the base85
encoding specified as part of Level 2 PostScript, do not share
these properties, and thus do not fulfill the portability
requirements a binary transport encoding for mail must meet.
The encoding process represents 24-bit groups of input bits as output
strings of 4 encoded characters. Proceeding from left to right, a
24-bit input group is formed by concatenating 3 8-bit input groups.
These 24 bits are then treated as 4 concatenated 6-bit groups, each
of which is translated into a single digit in the base64 alphabet.
When encoding a bit stream via the base64 encoding, the bit stream
must be presumed to be ordered with the most-significant-bit first.
Borenstein & Freed [Page 21]
RFC 1521 MIME September 1993
That is, the first bit in the stream will be the high-order bit in
the first byte, and the eighth bit will be the low-order bit in the
first byte, and so on.
Each 6-bit group is used as an index into an array of 64 printable
characters. The character referenced by the index is placed in the
output string. These characters, identified in Table 1, below, are
selected so as to be universally representable, and the set excludes
characters with particular significance to SMTP (e.g., ".", CR, LF)
and to the encapsulation boundaries defined in this document (e.g.,
"-").
Table 1: The Base64 Alphabet
Value Encoding Value Encoding Value Encoding Value Encoding
0 A 17 R 34 i 51 z
1 B 18 S 35 j 52 0
2 C 19 T 36 k 53 1
3 D 20 U 37 l 54 2
4 E 21 V 38 m 55 3
5 F 22 W 39 n 56 4
6 G 23 X 40 o 57 5
7 H 24 Y 41 p 58 6
8 I 25 Z 42 q 59 7
9 J 26 a 43 r 60 8
10 K 27 b 44 s 61 9
11 L 28 c 45 t 62 +
12 M 29 d 46 u 63 /
13 N 30 e 47 v
14 O 31 f 48 w (pad) =
15 P 32 g 49 x
16 Q 33 h 50 y
The output stream (encoded bytes) must be represented in lines of no
more than 76 characters each. All line breaks or other characters
not found in Table 1 must be ignored by decoding software. In base64
data, characters other than those in Table 1, line breaks, and other
white space probably indicate a transmission error, about which a
warning message or even a message rejection might be appropriate
under some circumstances.
Special processing is performed if fewer than 24 bits are available
at the end of the data being encoded. A full encoding quantum is
always completed at the end of a body. When fewer than 24 input bits
are available in an input group, zero bits are added (on the right)
to form an integral number of 6-bit groups. Padding at the end of
the data is performed using the '=' character. Since all base64
input is an integral number of octets, only the following cases can
Borenstein & Freed [Page 22]
RFC 1521 MIME September 1993
arise: (1) the final quantum of encoding input is an integral
multiple of 24 bits; here, the final unit of encoded output will be
an integral multiple of 4 characters with no "=" padding, (2) the
final quantum of encoding input is exactly 8 bits; here, the final
unit of encoded output will be two characters followed by two "="
padding characters, or (3) the final quantum of encoding input is
exactly 16 bits; here, the final unit of encoded output will be three
characters followed by one "=" padding character.
Because it is used only for padding at the end of the data, the
occurrence of any '=' characters may be taken as evidence that the
end of the data has been reached (without truncation in transit). No
such assurance is possible, however, when the number of octets
transmitted was a multiple of three.
Any characters outside of the base64 alphabet are to be ignored in
base64-encoded data. The same applies to any illegal sequence of
characters in the base64 encoding, such as "====="
Care must be taken to use the proper octets for line breaks if base64
encoding is applied directly to text material that has not been
converted to canonical form. In particular, text line breaks must be
converted into CRLF sequences prior to base64 encoding. The important
thing to note is that this may be done directly by the encoder rather
than in a prior canonicalization step in some implementations.
NOTE: There is no need to worry about quoting apparent
encapsulation boundaries within base64-encoded parts of multipart
entities because no hyphen characters are used in the base64
encoding.
*/
public class Base64 {
/**
*
*
*/
private Base64() {
}
// TODO: not a great way to do this, should work with chars not bytes.
// We convert utf-16 to ASCII and create conversion tables based on ASCII
// code points
private static final String INTERNAL_ENCODING = "ASCII"; //$NON-NLS-1$
private static String base64CharSetSequence = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; //$NON-NLS-1$
// Table to convert a number from 0-64 to an (Base64) ASCII byte equivalent
private static byte[] valToBase64CharTable;
// Table to convert an ascii byte to the Base64 number equivalent
private static int[] base64ToValTable;
static {
try {
valToBase64CharTable = base64CharSetSequence.getBytes(INTERNAL_ENCODING);
} catch (UnsupportedEncodingException e) {
}
base64ToValTable = new int[256];
for (int i = 0; i < 256; i++) {
base64ToValTable[i] = -1;
}
for (int i = 0; i < valToBase64CharTable.length; i++) {
base64ToValTable[valToBase64CharTable[i] & 0xFF] = i;
}
}
private static int[] three2four(byte a, byte b, byte c) {
/*
* aaaaaa|aabbbb|bbbbcc|cccccc
*/
int[] result = new int[4];
result[0] = a >>> 2 & 0x3f & 0xFF;
result[1] = ((a & 0x03) << 4) | ((b & 0xf0) >>> 4) & 0xFF;
result[2] = ((b & 0x0f) << 2) | ((c & 0xc0) >>> 6) & 0xFF;
result[3] = c & 0x3f;
return result;
}
public static String encode(byte[] input) {
byte[] result = encodeToBytes(input);
;
String strResult = null;
try {
strResult = new String(result, INTERNAL_ENCODING);
} catch (UnsupportedEncodingException e) {
strResult = new String(result);
}
return strResult;
}
public static byte[] decode(String input) {
byte[] byteInput = null;
try {
byteInput = input.getBytes(INTERNAL_ENCODING);
} catch (UnsupportedEncodingException e) {
byteInput = input.getBytes();
}
byte[] result = decode(byteInput);
return result;
}
private static byte[] encodeToBytes(byte[] input) {
int outsize = input.length / 3 * 4;
if (input.length % 3 != 0) {
outsize += 4;
}
byte[] encoded = new byte[outsize];
byte zero = (byte) 0;
byte[] data = new byte[4];
int pos = 0;
for (int i = 0; i < input.length; i += 3) {
switch (input.length - i) {
case 1:
// ok encode 1 byte into 2 and add '=='
int[] result = three2four(input[i], zero, zero);
data[0] = valToBase64CharTable[result[0]];
data[1] = valToBase64CharTable[result[1]];
data[2] = valToBase64CharTable[64];
data[3] = valToBase64CharTable[64];
break;
case 2:
result = three2four(input[i], input[i + 1], zero);
data[0] = valToBase64CharTable[result[0]];
data[1] = valToBase64CharTable[result[1]];
data[2] = valToBase64CharTable[result[2]];
data[3] = valToBase64CharTable[64];
// ok encode 2 bytes into 3 and add '='
break;
default:
result = three2four(input[i], input[i + 1], input[i + 2]);
data[0] = valToBase64CharTable[result[0]];
data[1] = valToBase64CharTable[result[1]];
data[2] = valToBase64CharTable[result[2]];
data[3] = valToBase64CharTable[result[3]];
// ok encode 3 bytes into 4
break;
}
for (int j = 0; j < 4; j++) {
encoded[pos] = data[j];
pos++;
}
}
return encoded;
}
/**
* decode a base64 stream.
*
* @param input
* base64 encoded byte array
* @return decoded byte array
*/
private static byte[] decode(byte[] input) {
// if this is a pure base64 encoded stream then
// the longest result is outsize (including the
// possibility of 2-3 extra bytes (and missing
// padding) will result in at most an extra 2 decoded
// bytes
int outsize = input.length / 4 * 3;
// if we have a dodgy stream (ie not multiples of 4 bytes)
// we will attempt to cater for this.
if (input.length % 4 != 0) {
outsize += input.length % 4 - 1;
} else {
// we have a proper base64 stream so we can adjust futher.
// note that if there are 2 pads at the end, reduce outsize by 2
// if there is 1 pad at end, reduce outsize by 1. Also need to
// handle
// situation where we have added crlfs to the output.
// if (input[input.length - 1] == valToBase64CharTable[64]) {
// outsize--;
// }
// if (input[input.length - 2] == valToBase64CharTable[64]) {
// outsize--;
// }
}
// return nothing if we have no allocation.
if (outsize == 0) {
return new byte[0];
}
// outsize could be too large. Will reduce the size at the end.
byte[] decoded = new byte[outsize];
int[] base64set = new int[4];
int outputPos = 0;
int decodepos = 0;
for (int i = 0; i < input.length; i++) {
// Get byte value and mask of any sign bit if byte > 0x7F
int byteVal = (int) input[i] & 0xFF;
if (base64ToValTable[byteVal] == -1) {
continue;
} else {
base64set[decodepos] = base64ToValTable[byteVal];
decodepos++;
// check to see if we have 4 entries now
if (decodepos == 4) {
decodepos = 0;
decoded[outputPos] = (byte) ((base64set[0] << 2) | ((base64set[1] & 0x30) >>> 4));
outputPos++;
if (base64set[2] != 64) {
decoded[outputPos] = (byte) (((base64set[1] & 0x0f) << 4) | ((base64set[2] & 0x3c) >>> 2));
outputPos++;
if (base64set[3] != 64) {
decoded[outputPos] = (byte) (((base64set[2] & 0x03) << 6 | base64set[3]));
outputPos++;
}
}
}
}
}
if (decodepos > 1) {
// we have some bits left over
decoded[outputPos] = (byte) ((base64set[0] << 2) | ((base64set[1] & 0x30) >>> 4));
outputPos++;
if (decodepos > 2 && base64set[2] != 64) {
decoded[outputPos] = (byte) (((base64set[1] & 0x0f) << 4) | ((base64set[2] & 0x3c) >>> 2));
outputPos++;
}
}
byte[] finalDecoded = decoded;
// reduce the returned byte array to contain just the relevant entries.
// outputPos contains the final length of the information
if (outsize > outputPos) {
if (outputPos > 0) {
finalDecoded = new byte[outputPos];
System.arraycopy(decoded, 0, finalDecoded, 0, outputPos);
} else {
return new byte[0];
}
}
return finalDecoded;
}
// private static byte[] decode(byte[] input) {
// int outsize = input.length;
// outsize = outsize / 4 * 3;
//
// if (input[input.length - 1] == valToBase64CharTable[64]) {
// outsize--;
// }
// if (input[input.length - 2] == valToBase64CharTable[64]) {
// outsize--;
// }
//
// // note that if there are 2 pads at the end, reduce outsize by 2
// // if there is 1 pad at end, reduce outsize by 1. Also need to handle
// // situation where we have added crlfs to the output.
//
// if (input.length % 4 != 0) {
// // error, but need to handle 76 character lines where crlfs have been
// added
// }
//
// byte[] decoded = new byte[outsize];
// for (int j = 0; j < outsize; j++) {
// decoded[j] = '?';
// }
// int[] base64set = new int[4];
//
// int outputPos = 0;
// int decodepos = 0;
//
// for (int i = 0; i < input.length; i++) {
// // Get byte value and mask of any sign bit if byte > 0x7F
// int byteVal = (int) input[i] & 0xFF;
// if (base64ToValTable[byteVal] == -1) {
// continue;
// } else {
// base64set[decodepos] = base64ToValTable[byteVal];
// decodepos++;
//
// // check to see if we have 4 entries now
// if (decodepos == 4) {
// decodepos = 0;
// decoded[outputPos] = (byte) ((base64set[0] << 2) | ((base64set[1] & 0x30)
// >>> 4));
// if (base64set[2] != 64) {
// decoded[outputPos + 1] = (byte) (((base64set[1] & 0x0f) << 4) |
// ((base64set[2] & 0x3c) >>> 2));
// if (base64set[3] != 64) {
// decoded[outputPos + 2] = (byte) (((base64set[2] & 0x03) << 6 |
// base64set[3]));
// }
// }
// outputPos += 3;
// }
// }
// }
// return decoded;
// }
}