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Utilities helping with reading writing and keeping various data
formats, including JSON, binary data and formatted text.
/*
* 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 net.morimekta.util;
import static java.nio.charset.StandardCharsets.US_ASCII;
import static java.nio.charset.StandardCharsets.UTF_8;
/**
* Minimal Base64 utility. Will always encode with standard base64 encoding, no
* padding, and no wrapping, but will parse both URL_SAFE and standard base64
* data (or even a mismatched mix).
*
* The code is optimized to have a low stack count, but be call safe using
* IllegalArgumentException on errors.
*
* It is a minimal port of the
* iharder Base64
* utility class.
*
* Note: This library should only be used when you have a controlled environment
* where you use base64 encoding, and it needs to be as fast as possible. If you
* need more functionality around base64, use the native encoder or decoder.
*/
public class Base64 {
/* ******** P R I V A T E F I E L D S ******** */
/** The equals sign (=) as a byte. */
private final static byte EQUALS_SIGN = (byte) '=';
private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding
/* ******** U R L S A F E B A S E 6 4 A L P H A B E T ******** */
/**
* Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548:
* http://www.faqs.org/rfcs/rfc3548.html.
* Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" and "slash."
*/
private final static byte[] ALPHABET = {
(byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H',
(byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P',
(byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X',
(byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
(byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n',
(byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v',
(byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
(byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) '+', (byte) '/'
};
/**
* Used in decoding URL- and Filename-safe dialects of Base64.
*/
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, // Minus sign at decimal 45
-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
-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
};
/** Defeats instantiation. */
private Base64() {
}
/* ******** E N C O D I N G M E T H O D S ******** */
/**
* Encodes up to three bytes of the array source
* and writes the resulting four Base64 bytes to destination.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* srcOffset and destOffset.
* This method does not check to make sure your arrays
* are large enough to accomodate srcOffset + 3 for
* the source array or destOffset + 4 for
* the destination array.
* The actual number of significant bytes in your array is
* given by numSigBytes.
* This is the lowest level of the encoding methods with
* all possible parameters.
*
* @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
* @return the destination array
* @since 1.3
*/
private static int encode3to4(byte[] source,
int srcOffset,
int numSigBytes,
byte[] destination,
int destOffset) {
// 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 1:
destination[destOffset] = ALPHABET[(inBuff >>> 18)];
destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
return 2;
case 2:
destination[destOffset] = ALPHABET[(inBuff >>> 18)];
destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
return 3;
default:
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 4;
}
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source The data to convert
* @return The Base64-encoded data as a String
* @throws NullPointerException if source array is null
* @since 2.0
*/
public static String encodeToString(final byte[] source) {
return encodeToString(source, 0, source.length);
}
/**
* Encodes a byte array into Base64 string.
*
* @param source The data to convert
* @param off The data offset of what to encode.
* @param len The number of bytes to encode.
* @return The Base64-encoded data as a String
* @throws NullPointerException if source array is null
* @since 2.0
*/
public static String encodeToString(final byte[] source, int off, int len) {
byte[] encoded = encode(source, off, len);
return new String(encoded, US_ASCII);
}
/**
* Encodes a byte array into Base64 data.
*
* @param source The data to convert
* @param off The data offset of what to encode.
* @param len The number of bytes to encode.
* @return The Base64-encoded data as a String
* @throws NullPointerException if source array is null
* @since 2.0
*/
public static byte[] encode(final byte[] source, final int off, final int len) {
if (source == null) {
throw new NullPointerException("Cannot serialize a null array.");
}
if (off < 0) {
throw new IllegalArgumentException("Cannot have negative offset: " + off);
}
if (len < 0) {
throw new IllegalArgumentException("Cannot have negative length: " + len);
}
if (off + len > source.length) {
throw new IllegalArgumentException(String.format(
"Cannot have offset of %d and length of %d with array of length %d",
off,
len,
source.length));
}
if (len == 0) {
return new byte[0];
}
//int len43 = len * 4 / 3;
//byte[] outBuff = new byte[ ( len43 ) // Main 4:3
// + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding
// + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
// Try to determine more precisely how big the array needs to be.
// If we get it right, we don't have to do an array copy, and
// we save a bunch of memory.
int blocks = len / 3;
int extra = len % 3;
int bufLen = blocks * 4 + (extra > 0 ? extra + 1 : 0); // Bytes needed for actual encoding
byte[] dest = new byte[bufLen];
int srcPos = 0;
int destPos = 0;
final int len2 = len - 2;
for (; srcPos < len2; srcPos += 3) {
destPos += encode3to4(source, srcPos + off, 3, dest, destPos);
}
if (srcPos < len) {
encode3to4(source, srcPos + off, len - srcPos, dest, destPos);
}
return dest;
}
/**
* Encodes a byte array into Base64 string.
*
* @param source The data to convert
* @return The Base64-encoded data.
* @throws NullPointerException if source array is null
* @since 2.0
*/
public static byte[] encode(byte[] source) {
return encode(source, 0, source.length);
}
/* ******** D E C O D I N G M E T H O D S ******** */
/**
* Decodes four bytes from array source
* and writes the resulting bytes (up to three of them)
* to destination.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* srcOffset and destOffset.
* This method does not check to make sure your arrays
* are large enough to accomodate srcOffset + 4 for
* the source array or destOffset + 3 for
* the destination array.
* This method returns the actual number of bytes that
* were converted from the Base64 encoding.
* This is the lowest level of the decoding methods with
* all possible parameters.
*
*
* @param src the array to convert
* @param dest the array to hold the conversion
* @param offset the index where output will be put
* @return the number of decoded bytes converted
*/
private static int decode4to3(byte[] src,
int len,
byte[] dest,
int offset) {
// Example: Dk or Dk==
if (len == 2 || (src[2] == EQUALS_SIGN && src[3] == EQUALS_SIGN)) {
int outBuff = (validate(src[0]) << 18) |
(validate(src[1]) << 12);
dest[offset] = (byte) (outBuff >>> 16);
return 1;
}
// Example: DkL or DkL=
if (len == 3 || src[3] == EQUALS_SIGN) {
int outBuff = (validate(src[0]) << 18) |
(validate(src[1]) << 12) |
(validate(src[2]) << 6);
dest[offset] = (byte) (outBuff >>> 16);
dest[offset + 1] = (byte) (outBuff >>> 8);
return 2;
}
// Example: DkLE
int outBuff = (validate(src[0]) << 18) |
(validate(src[1]) << 12) |
(validate(src[2]) << 6) |
(validate(src[3]));
dest[offset] = (byte) (outBuff >>> 16);
dest[offset + 1] = (byte) (outBuff >>> 8);
dest[offset + 2] = (byte) (outBuff);
return 3;
}
private static int validate(byte from) {
byte b = DECODABET[from & 0x7F];
if (b < 0) {
throw new IllegalArgumentException(String.format(
"Invalid base64 character '%s'",
Strings.escape((char) from)));
}
return b;
}
/**
* Decode the Base64-encoded data in input and return the data in a new
* byte array.
*
* The padding '=' characters at the end are considered optional, but if
* any are present, there must be the correct number of them.
*
* @param source The data to decode
* @return decoded data
*/
public static byte[] decode(byte[] source) {
return decode(source, 0, source.length);
}
/**
* Decode the Base64-encoded data in input and return the data in a new
* byte array.
*
* The padding '=' characters at the end are considered optional, but if
* any are present, there must be the correct number of them.
*
* @param source The data to decode
* @param off The offset within the input array at which to start
* @param len The number of byte sof input to decode.
* @return decoded data
*/
public static byte[] decode(final byte[] source,
final int off,
final int len) {
if (source == null) {
throw new NullPointerException("Cannot decode null source array.");
}
if (off < 0) {
throw new IllegalArgumentException("Cannot have negative offset: " + off);
}
if (len < 0) {
throw new IllegalArgumentException("Cannot have negative length: " + len);
}
if ((off + len) > source.length) {
throw new IllegalArgumentException(String.format(
"Source array with length %d cannot have offset of %d and process %d bytes.",
source.length,
off,
len));
}
if (len == 0) {
return new byte[0];
}
int len34 = len * 3 / 4; // Estimate on array size
byte[] outBuff = new byte[len34]; // Upper limit on size of output
int outBuffPosn = 0; // Keep track of where we're writing
byte[] b4 = new byte[4]; // Four byte buffer from source, eliminating white space
int b4Posn = 0; // Keep track of four byte input buffer
int i; // Source array counter
byte sbiDecode; // Special value from DECODABET
for (i = off; i < off + len; i++) { // Loop through source
sbiDecode = DECODABET[source[i] & 0x7F];
// White space, Equals sign, or legit Base64 character
// Note the values such as -5 and -9 in the
// DECODABET at the top of the file.
if (sbiDecode >= WHITE_SPACE_ENC) {
if (sbiDecode >= EQUALS_SIGN_ENC) {
b4[b4Posn++] = source[i];
if (b4Posn > 3) {
outBuffPosn += decode4to3(b4, 4, outBuff, outBuffPosn);
b4Posn = 0;
}
}
} else {
// There's a bad input character in the Base64 stream.
if (source[i] < 0) {
throw new IllegalArgumentException(String.format(
"Bad Base64 input decimal %d in array position %d",
0x100 + (int) source[i],
i));
}
throw new IllegalArgumentException(String.format(
"Bad Base64 input character '%s' in array position %d",
Strings.escape((char) source[i]),
i));
}
}
if (b4Posn > 0) {
outBuffPosn += decode4to3(b4, b4Posn, outBuff, outBuffPosn);
}
if (outBuffPosn < outBuff.length) {
byte[] out = new byte[outBuffPosn];
System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
return out;
}
return outBuff;
}
/**
* Decodes data from Base64 notation.
*
* @param s the string to decode
* @return the decoded data
* @throws NullPointerException if s is null
*/
public static byte[] decode(String s) {
if (s == null) {
throw new NullPointerException("Input string was null.");
}
byte[] bytes = s.getBytes(UTF_8);
return decode(bytes, 0, bytes.length);
}
}