// Portions Copyright 2009, Google, Inc.
//
// Licensed 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.
//
// This code was converted from code at http://iharder.sourceforge.net/base64/
// Many extraneous features were removed.
// The original code said:
//
// I am placing this code in the Public Domain. Do with it as you will.
// This software comes with no guarantees or warranties but with
// plenty of well-wishing instead!
// Please visit
// http://iharder.net/xmlizable
// periodically to check for updates or to contribute improvements.
//
// @author Robert Harder
// @author rharder@usa.net
// @version 1.3
package com.google.enterprise.connector.util;
/**
* Base64 converter class. This code is not a full-blown MIME encoder;
* it simply converts binary data to Base64 data and back.
*
* @since 2.8
*/
/*
* TODO(jlacey): Replace with Guava's BaseEncoding when we upgrade to r14?
* Need to be careful about the performance of Base64FilterInputStream.
*/
public class Base64 {
/** The equals sign (=) as a byte. */
private final static byte EQUALS_SIGN = (byte) '=';
/** The new line character (\n) as a byte. */
private final static byte NEW_LINE = (byte) '\n';
/** The 64 valid Base64 encoding characters. */
public final static byte[] ALPHABET =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
.getBytes();
/** The 64 valid web safe Base64 encoding characters. */
public final static byte[] WEBSAFE_ALPHABET =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
.getBytes();
/**
* Translates a Base64 value to either its 6-bit reconstruction value
* or a negative number indicating some other meaning. This can decode
* content that was endoded with either the standard ALPHABET or the
* WEBSAFE_ALPHABET.
*/
private final static byte[] DECODABET = {
-9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8
-5, -5, // Whitespace: Tab and Linefeed
-9, -9, // Decimal 11 - 12
-5, // Whitespace: Carriage Return
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
-9, -9, -9, -9, -9, // Decimal 27 - 31
-5, // Whitespace: Space
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
62, // Plus sign at decimal 43
-9, // Decimal 44
62, // Dash '-' sign at decimal 45 (from WebSafe encoding)
-9, // Decimal 46
63, // Slash at decimal 47
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
-9, -9, -9, // Decimal 58 - 60
-1, // Equals sign at decimal 61
-9, -9, -9, // Decimal 62 - 64
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
-9, -9, -9, -9, // Decimal 91-94
63, // Underscore '_' at decimal 95 (from WebSafe encoding)
-9, // Decimal 96
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
-9, -9, -9, -9, -9 // Decimal 123 - 127
};
// Indicates white space in encoding.
private final static byte WHITE_SPACE_ENC = -5;
// Indicates equals sign in encoding.
private final static byte EQUALS_SIGN_ENC = -1;
private Base64() {
// Defeats instantiation.
}
/* ******** E N C O D I N G M E T H O D S ******** */
/**
* Encodes up to three bytes of the array <var>source</var>
* and writes the resulting four Base64 bytes to <var>destination</var>.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* <var>srcOffset</var> and <var>destOffset</var>.
* This method does not check to make sure your arrays
* are large enough to accommodate <var>srcOffset</var> + 3 for
* the <var>source</var> array or <var>destOffset</var> + 4 for
* the <var>destination</var> array.
* The actual number of significant bytes in your array is
* given by <var>numSigBytes</var>.
*
* @param source the array to convert
* @param srcOffset the index where conversion begins
* @param numSigBytes the number of significant bytes in your array
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @param alphabet is the encoding alphabet
* @return the <var>destination</var> array
*/
static byte[] encode3to4(byte[] source, int srcOffset,
int numSigBytes, byte[] destination, int destOffset, byte[] alphabet) {
// 1 2 3
// 01234567890123456789012345678901 Bit position
// --------000000001111111122222222 Array position from threeBytes
// --------| || || || | Six bit groups to index alphabet
// >>18 >>12 >> 6 >> 0 Right shift necessary
// 0x3f 0x3f 0x3f Additional AND
// Create buffer with zero-padding if there are only one or two
// significant bytes passed in the array.
// We have to shift left 24 in order to flush out the 1's that appear
// when Java treats a value as negative that is cast from a byte to an int.
int inBuff =
(numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0)
| (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0)
| (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0);
switch (numSigBytes) {
case 3:
destination[destOffset] = alphabet[(inBuff >>> 18)];
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = alphabet[(inBuff >>> 6) & 0x3f];
destination[destOffset + 3] = alphabet[(inBuff) & 0x3f];
return destination;
case 2:
destination[destOffset] = alphabet[(inBuff >>> 18)];
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = alphabet[(inBuff >>> 6) & 0x3f];
destination[destOffset + 3] = EQUALS_SIGN;
return destination;
case 1:
destination[destOffset] = alphabet[(inBuff >>> 18)];
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = EQUALS_SIGN;
destination[destOffset + 3] = EQUALS_SIGN;
return destination;
default:
return destination;
} // end switch
} // end encode3to4
/**
* Encodes a byte array into Base64 notation. Equivalent to calling
* {@link #encode(byte[], int, int, byte[], boolean)
* encodeBytes(source, 0, source.length)}
*
* @param source the binary data to encode
* @return the Base64-encoded output String
*/
public static String encode(byte[] source) {
return encode(source, 0, source.length, ALPHABET, true);
}
/**
* Encodes a byte array into web safe Base64 notation.
*
* @param source the binary data to encode
* @param doPadding If {@code true}, pad the result with '=' chars
* if it does not fall on 3 byte boundaries.
* @return the Base64-encoded output String
*/
public static String encodeWebSafe(byte[] source, boolean doPadding) {
return encode(source, 0, source.length, WEBSAFE_ALPHABET, doPadding);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source the binary data to encode
* @param off offset in array where conversion should begin
* @param len length of data to convert
* @param alphabet the encoding alphabet
* @param doPadding If {@code true}, pad the result with '=' chars
* if it does not fall on 3 byte boundaries.
* @return the Base64-encoded output String
*/
public static String encode(byte[] source, int off, int len, byte[] alphabet,
boolean doPadding) {
byte[] outBuff = encode(source, off, len, alphabet, Integer.MAX_VALUE);
int outLen = outBuff.length;
// If doPadding is false, set length to truncate '='
// padding characters
while (doPadding == false && outLen > 0) {
if (outBuff[outLen - 1] != '=') {
break;
}
outLen -= 1;
}
return new String(outBuff, 0, outLen);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source the data to convert
* @param off offset in array where conversion should begin
* @param len length of data to convert
* @param alphabet the encoding alphabet
* @param maxLineLength the maximum length of each line of output
* @return a byte array containing the Base64-encoded output
*/
public static byte[] encode(byte[] source, int off, int len, byte[] alphabet,
int maxLineLength) {
int len43 = ((len + 2) / 3) * 4;
byte[] outBuff = new byte[len43 + (len43 / maxLineLength)];
encode(source, off, len, outBuff, 0, alphabet, maxLineLength);
return outBuff;
}
/**
* Encodes a byte array into Base64 notation into a destination byte array.
* <strong>Warning:</strong> No check is made to make sure the destination
* is big enough to hold the conversion.
* <p>
* This was optimally constructed for use by {@link Base64FilterInputStream}.
*
* @param source the data to convert
* @param sourceOffset offset in source array where conversion should begin
* @param sourceLength length of data to convert
* @param dest the destination array for converted data
* @param destOffset offset in destination array to write
* @param alphabet the encoding alphabet
* @param maxLineLength the maximum length of each line of output
* @return the number of bytes written to destination
*/
static int encode(byte[] source, int sourceOffset, int sourceLength,
byte[] dest, int destOffset, byte[] alphabet, int maxLineLength) {
int s = 0;
int d = destOffset;
int len = sourceLength - 2;
int lineLength = 0;
for (; s < len; s += 3, d += 4) {
// The following block of code is the same as
// encode3to4( source, s + off, 3, dest, d, alphabet );
// but inlined for faster encoding (~20% improvement)
int inBuff =
((source[s + sourceOffset] << 24) >>> 8)
| ((source[s + 1 + sourceOffset] << 24) >>> 16)
| ((source[s + 2 + sourceOffset] << 24) >>> 24);
dest[d] = alphabet[(inBuff >>> 18)];
dest[d + 1] = alphabet[(inBuff >>> 12) & 0x3f];
dest[d + 2] = alphabet[(inBuff >>> 6) & 0x3f];
dest[d + 3] = alphabet[(inBuff) & 0x3f];
if ((lineLength += 4) >= maxLineLength) {
dest[d + 4] = NEW_LINE;
d++;
lineLength = 0;
} // end if: end of line
} // end for: each piece of array
if (s < sourceLength) {
encode3to4(source, s + sourceOffset, sourceLength - s, dest, d, alphabet);
d += 4;
if ((lineLength += 4) >= maxLineLength) {
dest[d++] = NEW_LINE;
}
}
return d - destOffset;
}
/* ******** D E C O D I N G M E T H O D S ******** */
/**
* Decodes four bytes from array <var>source</var>
* and writes the resulting bytes (up to three of them)
* to <var>destination</var>.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* <var>srcOffset</var> and <var>destOffset</var>.
* This method does not check to make sure your arrays
* are large enough to accommodate <var>srcOffset</var> + 4 for
* the <var>source</var> array or <var>destOffset</var> + 3 for
* the <var>destination</var> array.
* This method returns the actual number of bytes that
* were converted from the Base64 encoding.
*
* @param source the Base64-encoded bytes to decode
* @param srcOffset the index into {@code source} where conversion begins
* @param destination the array to hold the conversion
* @param destOffset the index into {code @destination} where output will be put
* @param decodabet the decodabet for decoding Base64 content
* @return the number of decoded bytes converted
*/
private static int decode4to3(byte[] source, int srcOffset,
byte[] destination, int destOffset, byte[] decodabet) {
// Example: Dk==
if (source[srcOffset + 2] == EQUALS_SIGN) {
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6)
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12);
destination[destOffset] = (byte) (outBuff >>> 16);
return 1;
} else if (source[srcOffset + 3] == EQUALS_SIGN) {
// Example: DkL=
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6)
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12)
| ((decodabet[source[srcOffset + 2]] << 24) >>> 18);
destination[destOffset] = (byte) (outBuff >>> 16);
destination[destOffset + 1] = (byte) (outBuff >>> 8);
return 2;
} else {
// Example: DkLE
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6)
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12)
| ((decodabet[source[srcOffset + 2]] << 24) >>> 18)
| ((decodabet[source[srcOffset + 3]] << 24) >>> 24);
destination[destOffset] = (byte) (outBuff >> 16);
destination[destOffset + 1] = (byte) (outBuff >> 8);
destination[destOffset + 2] = (byte) (outBuff);
return 3;
}
} // end decodeToBytes
/**
* Decodes data from Base64 notation.
* Understands either standard or web-safe encoding.
*
* @param source the Base64-encoded String to decode
* @return a byte array containing the decoded data
* @throws Base64DecoderException if the source does not
* contain valid Base64-encoded data
*/
public static byte[] decode(String source) throws Base64DecoderException {
byte[] bytes = source.getBytes();
return decode(bytes, 0, bytes.length, DECODABET);
}
/**
* Decodes Base64 content in byte array format and returns
* the decoded byte array.
* Understands either standard or web-safe encoding.
*
* @param source the Base64-encoded data to decode
* @return a byte array containing the decoded data
* @throws Base64DecoderException if the source does not
* contain valid Base64-encoded data
*/
public static byte[] decode(byte[] source) throws Base64DecoderException {
return decode(source, 0, source.length, DECODABET);
}
/**
* Decodes Base64 content in byte array format and returns
* the decoded byte array.
* Understands either standard or web-safe encoding.
*
* @param source the Base64-encoded data to decode
* @param off the offset into {@code source} to begin decoding
* @param len the number of characters to decode
* @return a byte array containing the decoded data
* @throws Base64DecoderException if the source does not
* contain valid Base64-encoded data
*/
public static byte[] decode(byte[] source, int off, int len)
throws Base64DecoderException {
return decode(source, off, len, DECODABET);
}
/**
* Decodes Base64 content using the supplied decodabet and returns
* the decoded byte array.
*
* @param source the Base64-encoded data to decode
* @param off the offset into {@code source} to begin decoding
* @param len the number of characters to decode
* @param decodabet the decodabet for decoding Base64 content
* @return a byte array containing the decoded data
* @throws Base64DecoderException if the source does not
* contain valid Base64-encoded data
*/
private static byte[] decode(byte[] source, int off, int len,
byte[] decodabet) throws Base64DecoderException {
int len34 = len * 3 / 4;
byte[] outBuff = new byte[2 + len34]; // Upper limit on size of output
int outBuffPosn = 0;
byte[] b4 = new byte[4];
int b4Posn = 0;
int i = 0;
byte sbiCrop = 0;
byte sbiDecode = 0;
for (i = 0; i < len; i++) {
sbiCrop = (byte) (source[i + off] & 0x7f); // Only the low seven bits
sbiDecode = decodabet[sbiCrop];
if (sbiDecode >= WHITE_SPACE_ENC) { // White space Equals sign or better
if (sbiDecode >= EQUALS_SIGN_ENC) {
// An equals sign (for padding) must not occur at position 0 or 1
// and must be the last byte[s] in the encoded value.
if (sbiCrop == EQUALS_SIGN) {
int bytesLeft = len - i;
byte lastByte = (byte) (source[len - 1 + off] & 0x7f);
if (b4Posn == 0 || b4Posn == 1) {
throw new Base64DecoderException(
"invalid padding byte '=' at byte offset " + i);
} else if ((b4Posn == 3 && bytesLeft > 2)
|| (b4Posn == 4 && bytesLeft > 1)) {
throw new Base64DecoderException(
"padding byte '=' falsely signals end of encoded value "
+ "at offset " + i);
} else if (lastByte != EQUALS_SIGN && lastByte != NEW_LINE) {
throw new Base64DecoderException(
"encoded value has invalid trailing byte");
}
break;
}
b4[b4Posn++] = sbiCrop;
if (b4Posn == 4) {
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet);
b4Posn = 0;
}
}
} else {
throw new Base64DecoderException("Bad Base64 input character at " + i
+ ": " + source[i + off] + "(decimal)");
}
}
// Because web safe encoding allows non padding base64 encodes, we
// need to pad the rest of the b4 buffer with equal signs when
// b4Posn != 0. There can be at most 2 equal signs at the end of
// four characters, so the b4 buffer must have two or three
// characters. This also catches the case where the input is
// padded with EQUALS_SIGN.
if (b4Posn != 0) {
if (b4Posn == 1) {
throw new Base64DecoderException("single trailing character at offset "
+ (len - 1));
}
b4[b4Posn++] = EQUALS_SIGN;
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet);
}
byte[] out = new byte[outBuffPosn];
System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
return out;
}
}