com.alibaba.nacos.common.codec.Base64 Maven / Gradle / Ivy
/*
* Copyright 1999-2018 Alibaba Group Holding Ltd.
*
* 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.
*/
package com.alibaba.nacos.common.codec;
import java.nio.charset.StandardCharsets;
/**
* Provides Base64 encoding and decoding as defined by RFC 2045.
*
* This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045
*
* Multipurpose
* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.
* The class can be parameterized in the following manner with various constructors:
- URL-safe mode: Default
* off.
- Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being
* multiples of 4 in the encoded data.
- Line separator: Default is CRLF ("\r\n")
Since this class
* operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character
* encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
This
* class is not thread-safe. Each thread should use its own instance.
*
* @author Apache Software Foundation
* @version $Revision: 1080712 $
* @see RFC 2045
* @since 1.0
*/
public class Base64 {
/**
* BASE32 characters are 6 bits in length. They are formed by taking a block of 3 octets to form a 24-bit string,
* which is converted into 4 BASE64 characters.
*/
private static final int BITS_PER_ENCODED_BYTE = 6;
private static final int BYTES_PER_UNENCODED_BLOCK = 3;
private static final int BYTES_PER_ENCODED_BLOCK = 4;
/**
* Chunk separator per RFC 2045 section 2.1.
*
* N.B. The next major release may break compatibility and make this field private.
*
* @see RFC 2045 section 2.1
*/
static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
/**
* This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
* equivalents as specified in Table 1 of RFC 2045.
*
* Thanks to "commons" project in ws.apache.org for this code.
*
*
http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*/
private static final byte[] STANDARD_ENCODE_TABLE = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
'2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};
/**
* This is a copy of the STANDARD_ENCODE_TABLE above, but with + and / changed to - and _ to make the encoded Base64
* results more URL-SAFE. This table is only used when the Base64's mode is set to URL-SAFE.
*/
private static final byte[] URL_SAFE_ENCODE_TABLE = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
'2', '3', '4', '5', '6', '7', '8', '9', '-', '_'};
/**
* This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
* Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
* alphabet but fall within the bounds of the array are translated to -1.
*
*
Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles
* both URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
*
*
Thanks to "commons" project in ws.apache.org for this code.
*
*
http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*/
private static final byte[] DECODE_TABLE = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1,
62, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8,
9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51};
/**
* Base64 uses 6-bit fields. Mask used to extract 6 bits, used when encoding
*/
private static final int MASK_6BITS = 0x3f;
// The static final fields above are used for the original static byte[] methods on Base64.
// The private member fields below are used with the new streaming approach, which requires
// some state be preserved between calls of encode() and decode().
/**
* Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
* to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
* between the two modes.
*/
private final byte[] encodeTable;
/**
* Only one decode table currently; keep for consistency with Base32 code.
*/
private final byte[] decodeTable = DECODE_TABLE;
/**
* Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
*/
private final byte[] lineSeparator;
/**
* Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
* decodeSize = 3 + lineSeparator.length;
*/
private final int decodeSize;
/**
* Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
* encodeSize = 4 + lineSeparator.length;
*/
private final int encodeSize;
/**
* Place holder for the bytes we're dealing with for our based logic. Bitwise operations store and extract the
* encoding or decoding from this variable.
*/
private int bitWorkArea;
/**
* Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
When encoding the line
* length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.
*
* When decoding all variants are supported.
*/
public Base64() {
this(0, CHUNK_SEPARATOR, false);
}
/**
* Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode. When encoding the line
* length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
* Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
*
When decoding all variants are supported.
*
* @param lineLength Each line of encoded data will be at most of the given length (rounded down to nearest
* multiple of 4). If lineLength <= 0, then the output will not be divided into lines (chunks).
* Ignored when decoding.
* @param lineSeparator Each line of encoded data will end with this sequence of bytes.
* @param urlSafe Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to
* encode operations. Decoding seamlessly handles both modes.
* @throws IllegalArgumentException The provided lineSeparator included some base64 characters. That's not going to
* work!
* @since 1.4
*/
public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
chunkSeparatorLength = lineSeparator == null ? 0 : lineSeparator.length;
unencodedBlockSize = BYTES_PER_UNENCODED_BLOCK;
encodedBlockSize = BYTES_PER_ENCODED_BLOCK;
this.lineLength =
(lineLength > 0 && chunkSeparatorLength > 0) ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;
// TODO could be simplified if there is no requirement to reject invalid line sep when length <=0
// @see test case Base64Test.testConstructors()
if (lineSeparator != null) {
if (containsAlphabetOrPad(lineSeparator)) {
String sep = null;
sep = new String(lineSeparator, StandardCharsets.UTF_8);
throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
}
if (lineLength > 0) {
this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
this.lineSeparator = new byte[lineSeparator.length];
System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
} else {
this.encodeSize = BYTES_PER_ENCODED_BLOCK;
this.lineSeparator = null;
}
} else {
this.encodeSize = BYTES_PER_ENCODED_BLOCK;
this.lineSeparator = null;
}
this.decodeSize = this.encodeSize - 1;
this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
}
/**
* Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
*
* @param pArray a byte array containing binary data
* @return A byte array containing only the basen alphabetic character data
*/
private byte[] encode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
encode(pArray, 0, pArray.length);
encode(pArray, 0, -1);
byte[] buf = new byte[pos - readPos];
readResults(buf, 0, buf.length);
return buf;
}
/**
* Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once
* with the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush
* last remaining bytes (if not multiple of 3).
Thanks to "commons" project in ws.apache.org for the
* bitwise operations, and general approach. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*
*
* @param in byte[] array of binary data to base64 encode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for encoding.
*/
void encode(byte[] in, int inPos, int inAvail) {
if (eof) {
return;
}
if (inAvail < 0) {
eof = true;
if (0 == modulus && lineLength == 0) {
return;
}
ensureBufferSize(encodeSize);
int savedPos = pos;
switch (modulus) {
case 1:
buffer[pos++] = encodeTable[(bitWorkArea >> 2) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea << 4) & MASK_6BITS];
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
buffer[pos++] = PAD;
}
break;
case 2:
buffer[pos++] = encodeTable[(bitWorkArea >> 10) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 4) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea << 2) & MASK_6BITS];
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
}
break;
default:
break;
}
currentLinePos += pos - savedPos;
/*
if currentPos == 0 we are at the start of a line, so don't add CRLF
*/
if (lineLength > 0 && currentLinePos > 0) {
System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
pos += lineSeparator.length;
}
} else {
for (int i = 0; i < inAvail; i++) {
ensureBufferSize(encodeSize);
modulus = (modulus + 1) % BYTES_PER_UNENCODED_BLOCK;
int b = in[inPos++];
if (b < 0) {
b += 256;
}
bitWorkArea = (bitWorkArea << 8) + b;
if (0 == modulus) {
buffer[pos++] = encodeTable[(bitWorkArea >> 18) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 12) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 6) & MASK_6BITS];
buffer[pos++] = encodeTable[bitWorkArea & MASK_6BITS];
currentLinePos += BYTES_PER_ENCODED_BLOCK;
if (lineLength > 0 && lineLength <= currentLinePos) {
System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
pos += lineSeparator.length;
currentLinePos = 0;
}
}
}
}
}
/**
* Decodes a byte[] containing characters in the Base-N alphabet.
*
* @param pArray A byte array containing Base-N character data
* @return a byte array containing binary data
*/
private byte[] decode(byte[] pArray) {
reset();
if (pArray == null || pArray.length == 0) {
return pArray;
}
decode(pArray, 0, pArray.length);
decode(pArray, 0, -1);
byte[] result = new byte[pos];
readResults(result, 0, result.length);
return result;
}
/**
* Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice:
* once with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The
* "-1" call is not necessary when decoding, but it doesn't hurt, either.
Ignores all non-base64
* characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are silently ignored, but
* has implications for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will
* not check the provided data for validity.
Thanks to "commons" project in ws.apache.org for the bitwise
* operations, and general approach. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*
* @param in byte[] array of ascii data to base64 decode.
* @param inPos Position to start reading data from.
* @param inAvail Amount of bytes available from input for encoding.
*/
void decode(byte[] in, int inPos, int inAvail) {
if (eof) {
return;
}
if (inAvail < 0) {
eof = true;
}
for (int i = 0; i < inAvail; i++) {
ensureBufferSize(decodeSize);
byte b = in[inPos++];
if (b == PAD) {
// We're done.
eof = true;
break;
} else {
if (b >= 0 && b < DECODE_TABLE.length) {
int result = DECODE_TABLE[b];
if (result >= 0) {
modulus = (modulus + 1) % BYTES_PER_ENCODED_BLOCK;
bitWorkArea = (bitWorkArea << BITS_PER_ENCODED_BYTE) + result;
if (modulus == 0) {
buffer[pos++] = (byte) ((bitWorkArea >> 16) & MASK_8BITS);
buffer[pos++] = (byte) ((bitWorkArea >> 8) & MASK_8BITS);
buffer[pos++] = (byte) (bitWorkArea & MASK_8BITS);
}
}
}
}
}
// Two forms of EOF as far as base64 decoder is concerned: actual
// EOF (-1) and first time '=' character is encountered in stream.
// This approach makes the '=' padding characters completely optional.
if (eof && modulus != 0) {
ensureBufferSize(decodeSize);
// We have some spare bits remaining
// Output all whole multiples of 8 bits and ignore the rest
switch (modulus) {
// case 1: // 6 bits - ignore entirely
// break;
case 2:
bitWorkArea = bitWorkArea >> 4;
buffer[pos++] = (byte) ((bitWorkArea) & MASK_8BITS);
break;
case 3:
bitWorkArea = bitWorkArea >> 2;
buffer[pos++] = (byte) ((bitWorkArea >> 8) & MASK_8BITS);
buffer[pos++] = (byte) ((bitWorkArea) & MASK_8BITS);
break;
default:
break;
}
}
}
/**
* Encodes binary data using the base64 algorithm but does not chunk the output.
*
* @param binaryData binary data to encode
* @return byte[] containing Base64 characters in their UTF-8 representation.
*/
public static byte[] encodeBase64(byte[] binaryData) {
return encodeBase64(binaryData, false, false, Integer.MAX_VALUE);
}
/**
* Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if true this encoder will chunk the base64 output into 76 character blocks
* @param urlSafe if true this encoder will emit - and _ instead of the usual + and /
* characters.
* @param maxResultSize The maximum result size to accept.
* @return Base64-encoded data.
* @throws IllegalArgumentException Thrown when the input array needs an output array bigger than maxResultSize
* @since 1.4
*/
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize) {
if (binaryData == null || binaryData.length == 0) {
return binaryData;
}
// Create this so can use the super-class method
// Also ensures that the same roundings are performed by the ctor and the code
Base64 b64 = isChunked ? new Base64(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe)
: new Base64(0, CHUNK_SEPARATOR, urlSafe);
long len = b64.getEncodedLength(binaryData);
if (len > maxResultSize) {
throw new IllegalArgumentException("Input array too big, the output array would be bigger (" + len
+ ") than the specified maximum size of " + maxResultSize);
}
return b64.encode(binaryData);
}
/**
* Decodes Base64 data into octets.
*
* @param base64Data Byte array containing Base64 data
* @return Array containing decoded data.
*/
public static byte[] decodeBase64(byte[] base64Data) {
return new Base64().decode(base64Data);
}
/**
* Returns whether or not the octet is in the Base32 alphabet.
*
* @param octet The value to test
* @return true if the value is defined in the the Base32 alphabet false otherwise.
*/
protected boolean isInAlphabet(byte octet) {
return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
}
/**
* MIME chunk size per RFC 2045 section 6.8.
*
* The {@value} character limit does not count the trailing CRLF, but counts all other characters, including
* any equal signs.
*
* @see RFC 2045 section 6.8
*/
private static final int MIME_CHUNK_SIZE = 76;
private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
/**
* Defines the default buffer size - currently {@value} - must be large enough for at least one encoded
* block+separator.
*/
private static final int DEFAULT_BUFFER_SIZE = 8192;
/**
* Mask used to extract 8 bits, used in decoding bytes.
*/
private static final int MASK_8BITS = 0xff;
/**
* Byte used to pad output.
*/
private static final byte PAD_DEFAULT = '=';
private static final byte PAD = PAD_DEFAULT;
/**
* Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32
*/
private final int unencodedBlockSize;
/**
* Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32
*/
private final int encodedBlockSize;
/**
* Chunksize for encoding. Not used when decoding. A value of zero or less implies no chunking of the encoded data.
* Rounded down to nearest multiple of encodedBlockSize.
*/
private final int lineLength;
/**
* Size of chunk separator. Not used unless {@link #lineLength} > 0.
*/
private final int chunkSeparatorLength;
/**
* Buffer for streaming.
*/
private byte[] buffer;
/**
* Position where next character should be written in the buffer.
*/
private int pos;
/**
* Position where next character should be read from the buffer.
*/
private int readPos;
/**
* Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless, and
* must be thrown away.
*/
private boolean eof;
/**
* Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
* make sure each encoded line never goes beyond lineLength (if lineLength > 0).
*/
private int currentLinePos;
/**
* Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding. This
* variable helps track that.
*/
private int modulus;
/**
* Ensure that the buffer has room for size bytes.
*
* @param size minimum spare space required
*/
private void ensureBufferSize(int size) {
if ((buffer == null) || (buffer.length < pos + size)) {
if (buffer == null) {
buffer = new byte[DEFAULT_BUFFER_SIZE];
pos = 0;
readPos = 0;
} else {
byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
System.arraycopy(buffer, 0, b, 0, buffer.length);
buffer = b;
}
}
}
/**
* Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
* bytes. Returns how many bytes were actually extracted.
*
* @param b byte[] array to extract the buffered data into.
* @param bPos position in byte[] array to start extraction at.
* @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
* @return The number of bytes successfully extracted into the provided byte[] array.
*/
private int readResults(byte[] b, int bPos, int bAvail) {
if (buffer != null) {
int len = Math.min(pos - readPos, bAvail);
System.arraycopy(buffer, readPos, b, bPos, len);
readPos += len;
if (readPos >= pos) {
buffer = null;
}
return len;
}
return eof ? -1 : 0;
}
/**
* Resets this object to its initial newly constructed state.
*/
private void reset() {
buffer = null;
pos = 0;
readPos = 0;
currentLinePos = 0;
modulus = 0;
eof = false;
}
/**
* Tests a given byte array to see if it contains any characters within the alphabet or PAD.
*
* Intended for use in checking line-ending arrays
*
* @param arrayOctet byte array to test
* @return true if any byte is a valid character in the alphabet or PAD; false otherwise
*/
private boolean containsAlphabetOrPad(byte[] arrayOctet) {
if (arrayOctet == null) {
return false;
}
for (int i = 0; i < arrayOctet.length; i++) {
if (PAD == arrayOctet[i] || isInAlphabet(arrayOctet[i])) {
return true;
}
}
return false;
}
/**
* Calculates the amount of space needed to encode the supplied array.
*
* @param pArray byte[] array which will later be encoded
* @return amount of space needed to encoded the supplied array. Returns a long since a max-len array will require >
* Integer.MAX_VALUE
*/
private long getEncodedLength(byte[] pArray) {
// Calculate non-chunked size - rounded up to allow for padding
// cast to long is needed to avoid possibility of overflow
long len = ((pArray.length + unencodedBlockSize - 1) / unencodedBlockSize) * (long) encodedBlockSize;
if (lineLength > 0) {
/*
Round up to nearest multiple
*/
len += ((len + lineLength - 1) / lineLength) * chunkSeparatorLength;
}
return len;
}
}