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/*
* Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package java.util;
import java.io.FilterOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import sun.nio.cs.ISO_8859_1;
import jdk.internal.vm.annotation.IntrinsicCandidate;
/**
* This class consists exclusively of static methods for obtaining
* encoders and decoders for the Base64 encoding scheme. The
* implementation of this class supports the following types of Base64
* as specified in
* RFC 4648 and
* RFC 2045.
*
*
* - Basic
*
Uses "The Base64 Alphabet" as specified in Table 1 of
* RFC 4648 and RFC 2045 for encoding and decoding operation.
* The encoder does not add any line feed (line separator)
* character. The decoder rejects data that contains characters
* outside the base64 alphabet.
*
* - URL and Filename safe
*
Uses the "URL and Filename safe Base64 Alphabet" as specified
* in Table 2 of RFC 4648 for encoding and decoding. The
* encoder does not add any line feed (line separator) character.
* The decoder rejects data that contains characters outside the
* base64 alphabet.
*
* - MIME
*
Uses "The Base64 Alphabet" as specified in Table 1 of
* RFC 2045 for encoding and decoding operation. The encoded output
* must be represented in lines of no more than 76 characters each
* and uses a carriage return {@code '\r'} followed immediately by
* a linefeed {@code '\n'} as the line separator. No line separator
* is added to the end of the encoded output. All line separators
* or other characters not found in the base64 alphabet table are
* ignored in decoding operation.
*
*
* Unless otherwise noted, passing a {@code null} argument to a
* method of this class will cause a {@link java.lang.NullPointerException
* NullPointerException} to be thrown.
*
* @author Xueming Shen
* @since 1.8
*/
public class Base64 {
private Base64() {}
/**
* Returns a {@link Encoder} that encodes using the
* Basic type base64 encoding scheme.
*
* @return A Base64 encoder.
*/
public static Encoder getEncoder() {
return Encoder.RFC4648;
}
/**
* Returns a {@link Encoder} that encodes using the
* URL and Filename safe type base64
* encoding scheme.
*
* @return A Base64 encoder.
*/
public static Encoder getUrlEncoder() {
return Encoder.RFC4648_URLSAFE;
}
/**
* Returns a {@link Encoder} that encodes using the
* MIME type base64 encoding scheme.
*
* @return A Base64 encoder.
*/
public static Encoder getMimeEncoder() {
return Encoder.RFC2045;
}
/**
* Returns a {@link Encoder} that encodes using the
* MIME type base64 encoding scheme
* with specified line length and line separators.
*
* @param lineLength
* the length of each output line (rounded down to nearest multiple
* of 4). If the rounded down line length is not a positive value,
* the output will not be separated in lines
* @param lineSeparator
* the line separator for each output line
*
* @return A Base64 encoder.
*
* @throws IllegalArgumentException if {@code lineSeparator} includes any
* character of "The Base64 Alphabet" as specified in Table 1 of
* RFC 2045.
*/
public static Encoder getMimeEncoder(int lineLength, byte[] lineSeparator) {
Objects.requireNonNull(lineSeparator);
int[] base64 = Decoder.fromBase64;
for (byte b : lineSeparator) {
if (base64[b & 0xff] != -1)
throw new IllegalArgumentException(
"Illegal base64 line separator character 0x" + Integer.toString(b, 16));
}
// round down to nearest multiple of 4
lineLength &= ~0b11;
if (lineLength <= 0) {
return Encoder.RFC4648;
}
return new Encoder(false, lineSeparator, lineLength, true);
}
/**
* Returns a {@link Decoder} that decodes using the
* Basic type base64 encoding scheme.
*
* @return A Base64 decoder.
*/
public static Decoder getDecoder() {
return Decoder.RFC4648;
}
/**
* Returns a {@link Decoder} that decodes using the
* URL and Filename safe type base64
* encoding scheme.
*
* @return A Base64 decoder.
*/
public static Decoder getUrlDecoder() {
return Decoder.RFC4648_URLSAFE;
}
/**
* Returns a {@link Decoder} that decodes using the
* MIME type base64 decoding scheme.
*
* @return A Base64 decoder.
*/
public static Decoder getMimeDecoder() {
return Decoder.RFC2045;
}
/**
* This class implements an encoder for encoding byte data using
* the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
*
*
Instances of {@link Encoder} class are safe for use by
* multiple concurrent threads.
*
*
Unless otherwise noted, passing a {@code null} argument to
* a method of this class will cause a
* {@link java.lang.NullPointerException NullPointerException} to
* be thrown.
*
If the encoded byte output of the needed size can not
* be allocated, the encode methods of this class will
* cause an {@link java.lang.OutOfMemoryError OutOfMemoryError}
* to be thrown.
*
* @see Decoder
* @since 1.8
*/
public static class Encoder {
private final byte[] newline;
private final int linemax;
private final boolean isURL;
private final boolean doPadding;
private Encoder(boolean isURL, byte[] newline, int linemax, boolean doPadding) {
this.isURL = isURL;
this.newline = newline;
this.linemax = linemax;
this.doPadding = doPadding;
}
/**
* This array is a lookup table that translates 6-bit positive integer
* index values into their "Base64 Alphabet" equivalents as specified
* in "Table 1: The Base64 Alphabet" of RFC 2045 (and RFC 4648).
*/
private static final char[] toBase64 = {
'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', '+', '/'
};
/**
* It's the lookup table for "URL and Filename safe Base64" as specified
* in Table 2 of the RFC 4648, with the '+' and '/' changed to '-' and
* '_'. This table is used when BASE64_URL is specified.
*/
private static final char[] toBase64URL = {
'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', '-', '_'
};
private static final int MIMELINEMAX = 76;
private static final byte[] CRLF = new byte[] {'\r', '\n'};
static final Encoder RFC4648 = new Encoder(false, null, -1, true);
static final Encoder RFC4648_URLSAFE = new Encoder(true, null, -1, true);
static final Encoder RFC2045 = new Encoder(false, CRLF, MIMELINEMAX, true);
/**
* Calculates the length of the encoded output bytes.
*
* @param srclen length of the bytes to encode
* @param throwOOME if true, throws OutOfMemoryError if the length of
* the encoded bytes overflows; else returns the
* length
* @return length of the encoded bytes, or -1 if the length overflows
*
*/
private final int encodedOutLength(int srclen, boolean throwOOME) {
int len = 0;
try {
if (doPadding) {
len = Math.multiplyExact(4, (Math.addExact(srclen, 2) / 3));
} else {
int n = srclen % 3;
len = Math.addExact(Math.multiplyExact(4, (srclen / 3)), (n == 0 ? 0 : n + 1));
}
if (linemax > 0) { // line separators
len = Math.addExact(len, (len - 1) / linemax * newline.length);
}
} catch (ArithmeticException ex) {
if (throwOOME) {
throw new OutOfMemoryError("Encoded size is too large");
} else {
// let the caller know that encoded bytes length
// is too large
len = -1;
}
}
return len;
}
/**
* Encodes all bytes from the specified byte array into a newly-allocated
* byte array using the {@link Base64} encoding scheme. The returned byte
* array is of the length of the resulting bytes.
*
* @param src
* the byte array to encode
* @return A newly-allocated byte array containing the resulting
* encoded bytes.
*/
public byte[] encode(byte[] src) {
int len = encodedOutLength(src.length, true); // dst array size
byte[] dst = new byte[len];
int ret = encode0(src, 0, src.length, dst);
if (ret != dst.length)
return Arrays.copyOf(dst, ret);
return dst;
}
/**
* Encodes all bytes from the specified byte array using the
* {@link Base64} encoding scheme, writing the resulting bytes to the
* given output byte array, starting at offset 0.
*
*
It is the responsibility of the invoker of this method to make
* sure the output byte array {@code dst} has enough space for encoding
* all bytes from the input byte array. No bytes will be written to the
* output byte array if the output byte array is not big enough.
*
* @param src
* the byte array to encode
* @param dst
* the output byte array
* @return The number of bytes written to the output byte array
*
* @throws IllegalArgumentException if {@code dst} does not have enough
* space for encoding all input bytes.
*/
public int encode(byte[] src, byte[] dst) {
int len = encodedOutLength(src.length, false); // dst array size
if (dst.length < len || len == -1)
throw new IllegalArgumentException(
"Output byte array is too small for encoding all input bytes");
return encode0(src, 0, src.length, dst);
}
/**
* Encodes the specified byte array into a String using the {@link Base64}
* encoding scheme.
*
*
This method first encodes all input bytes into a base64 encoded
* byte array and then constructs a new String by using the encoded byte
* array and the {@link java.nio.charset.StandardCharsets#ISO_8859_1
* ISO-8859-1} charset.
*
*
In other words, an invocation of this method has exactly the same
* effect as invoking
* {@code new String(encode(src), StandardCharsets.ISO_8859_1)}.
*
* @param src
* the byte array to encode
* @return A String containing the resulting Base64 encoded characters
*/
@SuppressWarnings("deprecation")
public String encodeToString(byte[] src) {
byte[] encoded = encode(src);
return new String(encoded, 0, 0, encoded.length);
}
/**
* Encodes all remaining bytes from the specified byte buffer into
* a newly-allocated ByteBuffer using the {@link Base64} encoding
* scheme.
*
* Upon return, the source buffer's position will be updated to
* its limit; its limit will not have been changed. The returned
* output buffer's position will be zero and its limit will be the
* number of resulting encoded bytes.
*
* @param buffer
* the source ByteBuffer to encode
* @return A newly-allocated byte buffer containing the encoded bytes.
*/
public ByteBuffer encode(ByteBuffer buffer) {
int len = encodedOutLength(buffer.remaining(), true);
byte[] dst = new byte[len];
int ret = 0;
if (buffer.hasArray()) {
ret = encode0(buffer.array(),
buffer.arrayOffset() + buffer.position(),
buffer.arrayOffset() + buffer.limit(),
dst);
buffer.position(buffer.limit());
} else {
byte[] src = new byte[buffer.remaining()];
buffer.get(src);
ret = encode0(src, 0, src.length, dst);
}
if (ret != dst.length)
dst = Arrays.copyOf(dst, ret);
return ByteBuffer.wrap(dst);
}
/**
* Wraps an output stream for encoding byte data using the {@link Base64}
* encoding scheme.
*
*
It is recommended to promptly close the returned output stream after
* use, during which it will flush all possible leftover bytes to the underlying
* output stream. Closing the returned output stream will close the underlying
* output stream.
*
* @param os
* the output stream.
* @return the output stream for encoding the byte data into the
* specified Base64 encoded format
*/
public OutputStream wrap(OutputStream os) {
Objects.requireNonNull(os);
return new EncOutputStream(os, isURL ? toBase64URL : toBase64,
newline, linemax, doPadding);
}
/**
* Returns an encoder instance that encodes equivalently to this one,
* but without adding any padding character at the end of the encoded
* byte data.
*
*
The encoding scheme of this encoder instance is unaffected by
* this invocation. The returned encoder instance should be used for
* non-padding encoding operation.
*
* @return an equivalent encoder that encodes without adding any
* padding character at the end
*/
public Encoder withoutPadding() {
if (!doPadding)
return this;
return new Encoder(isURL, newline, linemax, false);
}
@IntrinsicCandidate
private void encodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL) {
char[] base64 = isURL ? toBase64URL : toBase64;
for (int sp0 = sp, dp0 = dp ; sp0 < sl; ) {
int bits = (src[sp0++] & 0xff) << 16 |
(src[sp0++] & 0xff) << 8 |
(src[sp0++] & 0xff);
dst[dp0++] = (byte)base64[(bits >>> 18) & 0x3f];
dst[dp0++] = (byte)base64[(bits >>> 12) & 0x3f];
dst[dp0++] = (byte)base64[(bits >>> 6) & 0x3f];
dst[dp0++] = (byte)base64[bits & 0x3f];
}
}
private int encode0(byte[] src, int off, int end, byte[] dst) {
char[] base64 = isURL ? toBase64URL : toBase64;
int sp = off;
int slen = (end - off) / 3 * 3;
int sl = off + slen;
if (linemax > 0 && slen > linemax / 4 * 3)
slen = linemax / 4 * 3;
int dp = 0;
while (sp < sl) {
int sl0 = Math.min(sp + slen, sl);
encodeBlock(src, sp, sl0, dst, dp, isURL);
int dlen = (sl0 - sp) / 3 * 4;
dp += dlen;
sp = sl0;
if (dlen == linemax && sp < end) {
for (byte b : newline){
dst[dp++] = b;
}
}
}
if (sp < end) { // 1 or 2 leftover bytes
int b0 = src[sp++] & 0xff;
dst[dp++] = (byte)base64[b0 >> 2];
if (sp == end) {
dst[dp++] = (byte)base64[(b0 << 4) & 0x3f];
if (doPadding) {
dst[dp++] = '=';
dst[dp++] = '=';
}
} else {
int b1 = src[sp++] & 0xff;
dst[dp++] = (byte)base64[(b0 << 4) & 0x3f | (b1 >> 4)];
dst[dp++] = (byte)base64[(b1 << 2) & 0x3f];
if (doPadding) {
dst[dp++] = '=';
}
}
}
return dp;
}
}
/**
* This class implements a decoder for decoding byte data using the
* Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
*
*
The Base64 padding character {@code '='} is accepted and
* interpreted as the end of the encoded byte data, but is not
* required. So if the final unit of the encoded byte data only has
* two or three Base64 characters (without the corresponding padding
* character(s) padded), they are decoded as if followed by padding
* character(s). If there is a padding character present in the
* final unit, the correct number of padding character(s) must be
* present, otherwise {@code IllegalArgumentException} (
* {@code IOException} when reading from a Base64 stream) is thrown
* during decoding.
*
*
Instances of {@link Decoder} class are safe for use by
* multiple concurrent threads.
*
*
Unless otherwise noted, passing a {@code null} argument to
* a method of this class will cause a
* {@link java.lang.NullPointerException NullPointerException} to
* be thrown.
*
If the decoded byte output of the needed size can not
* be allocated, the decode methods of this class will
* cause an {@link java.lang.OutOfMemoryError OutOfMemoryError}
* to be thrown.
*
* @see Encoder
* @since 1.8
*/
public static class Decoder {
private final boolean isURL;
private final boolean isMIME;
private Decoder(boolean isURL, boolean isMIME) {
this.isURL = isURL;
this.isMIME = isMIME;
}
/**
* Lookup table for decoding 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 encoded to -1.
*
*/
private static final int[] fromBase64 = new int[256];
static {
Arrays.fill(fromBase64, -1);
for (int i = 0; i < Encoder.toBase64.length; i++)
fromBase64[Encoder.toBase64[i]] = i;
fromBase64['='] = -2;
}
/**
* Lookup table for decoding "URL and Filename safe Base64 Alphabet"
* as specified in Table2 of the RFC 4648.
*/
private static final int[] fromBase64URL = new int[256];
static {
Arrays.fill(fromBase64URL, -1);
for (int i = 0; i < Encoder.toBase64URL.length; i++)
fromBase64URL[Encoder.toBase64URL[i]] = i;
fromBase64URL['='] = -2;
}
static final Decoder RFC4648 = new Decoder(false, false);
static final Decoder RFC4648_URLSAFE = new Decoder(true, false);
static final Decoder RFC2045 = new Decoder(false, true);
/**
* Decodes all bytes from the input byte array using the {@link Base64}
* encoding scheme, writing the results into a newly-allocated output
* byte array. The returned byte array is of the length of the resulting
* bytes.
*
* @param src
* the byte array to decode
*
* @return A newly-allocated byte array containing the decoded bytes.
*
* @throws IllegalArgumentException
* if {@code src} is not in valid Base64 scheme
*/
public byte[] decode(byte[] src) {
byte[] dst = new byte[decodedOutLength(src, 0, src.length)];
int ret = decode0(src, 0, src.length, dst);
if (ret != dst.length) {
dst = Arrays.copyOf(dst, ret);
}
return dst;
}
/**
* Decodes a Base64 encoded String into a newly-allocated byte array
* using the {@link Base64} encoding scheme.
*
*
An invocation of this method has exactly the same effect as invoking
* {@code decode(src.getBytes(StandardCharsets.ISO_8859_1))}
*
* @param src
* the string to decode
*
* @return A newly-allocated byte array containing the decoded bytes.
*
* @throws IllegalArgumentException
* if {@code src} is not in valid Base64 scheme
*/
public byte[] decode(String src) {
return decode(src.getBytes(ISO_8859_1.INSTANCE));
}
/**
* Decodes all bytes from the input byte array using the {@link Base64}
* encoding scheme, writing the results into the given output byte array,
* starting at offset 0.
*
*
It is the responsibility of the invoker of this method to make
* sure the output byte array {@code dst} has enough space for decoding
* all bytes from the input byte array. No bytes will be written to
* the output byte array if the output byte array is not big enough.
*
*
If the input byte array is not in valid Base64 encoding scheme
* then some bytes may have been written to the output byte array before
* IllegalargumentException is thrown.
*
* @param src
* the byte array to decode
* @param dst
* the output byte array
*
* @return The number of bytes written to the output byte array
*
* @throws IllegalArgumentException
* if {@code src} is not in valid Base64 scheme, or {@code dst}
* does not have enough space for decoding all input bytes.
*/
public int decode(byte[] src, byte[] dst) {
int len = decodedOutLength(src, 0, src.length);
if (dst.length < len || len == -1)
throw new IllegalArgumentException(
"Output byte array is too small for decoding all input bytes");
return decode0(src, 0, src.length, dst);
}
/**
* Decodes all bytes from the input byte buffer using the {@link Base64}
* encoding scheme, writing the results into a newly-allocated ByteBuffer.
*
*
Upon return, the source buffer's position will be updated to
* its limit; its limit will not have been changed. The returned
* output buffer's position will be zero and its limit will be the
* number of resulting decoded bytes
*
*
{@code IllegalArgumentException} is thrown if the input buffer
* is not in valid Base64 encoding scheme. The position of the input
* buffer will not be advanced in this case.
*
* @param buffer
* the ByteBuffer to decode
*
* @return A newly-allocated byte buffer containing the decoded bytes
*
* @throws IllegalArgumentException
* if {@code buffer} is not in valid Base64 scheme
*/
public ByteBuffer decode(ByteBuffer buffer) {
int pos0 = buffer.position();
try {
byte[] src;
int sp, sl;
if (buffer.hasArray()) {
src = buffer.array();
sp = buffer.arrayOffset() + buffer.position();
sl = buffer.arrayOffset() + buffer.limit();
buffer.position(buffer.limit());
} else {
src = new byte[buffer.remaining()];
buffer.get(src);
sp = 0;
sl = src.length;
}
byte[] dst = new byte[decodedOutLength(src, sp, sl)];
return ByteBuffer.wrap(dst, 0, decode0(src, sp, sl, dst));
} catch (IllegalArgumentException iae) {
buffer.position(pos0);
throw iae;
}
}
/**
* Returns an input stream for decoding {@link Base64} encoded byte stream.
*
*
The {@code read} methods of the returned {@code InputStream} will
* throw {@code IOException} when reading bytes that cannot be decoded.
*
*
Closing the returned input stream will close the underlying
* input stream.
*
* @param is
* the input stream
*
* @return the input stream for decoding the specified Base64 encoded
* byte stream
*/
public InputStream wrap(InputStream is) {
Objects.requireNonNull(is);
return new DecInputStream(is, isURL ? fromBase64URL : fromBase64, isMIME);
}
/**
* Calculates the length of the decoded output bytes.
*
* @param src the byte array to decode
* @param sp the source position
* @param sl the source limit
*
* @return length of the decoded bytes
*
*/
private int decodedOutLength(byte[] src, int sp, int sl) {
int[] base64 = isURL ? fromBase64URL : fromBase64;
int paddings = 0;
int len = sl - sp;
if (len == 0)
return 0;
if (len < 2) {
if (isMIME && base64[0] == -1)
return 0;
throw new IllegalArgumentException(
"Input byte[] should at least have 2 bytes for base64 bytes");
}
if (isMIME) {
// scan all bytes to fill out all non-alphabet. a performance
// trade-off of pre-scan or Arrays.copyOf
int n = 0;
while (sp < sl) {
int b = src[sp++] & 0xff;
if (b == '=') {
len -= (sl - sp + 1);
break;
}
if ((b = base64[b]) == -1)
n++;
}
len -= n;
} else {
if (src[sl - 1] == '=') {
paddings++;
if (src[sl - 2] == '=')
paddings++;
}
}
if (paddings == 0 && (len & 0x3) != 0)
paddings = 4 - (len & 0x3);
// If len is near to Integer.MAX_VALUE, (len + 3)
// can possibly overflow, perform this operation as
// long and cast it back to integer when the value comes under
// integer limit. The final value will always be in integer
// limits
return 3 * (int) ((len + 3L) / 4) - paddings;
}
/**
* Decodes base64 characters, and returns the number of data bytes
* written into the destination array.
*
* It is the fast path for full 4-byte to 3-byte decoding w/o errors.
*
* decodeBlock() can be overridden by an arch-specific intrinsic.
* decodeBlock can choose to decode all, none, or a variable-sized
* prefix of the src bytes. This allows the intrinsic to decode in
* chunks of the src that are of a favorable size for the specific
* processor it's running on.
*
* If the intrinsic function does not process all of the bytes in
* src, it must process a multiple of four of them, making the
* returned destination length a multiple of three.
*
* If any illegal base64 bytes are encountered in src by the
* intrinsic, the intrinsic must return the actual number of valid
* data bytes already written to dst. Note that the '=' pad
* character is treated as an illegal Base64 character by
* decodeBlock, so it will not process a block of 4 bytes
* containing pad characters.
*
* Given the parameters, no length check is possible on dst, so dst
* is assumed to be large enough to store the decoded bytes.
*
* @param src
* the source byte array of Base64 encoded bytes
* @param sp
* the offset into src array to begin reading
* @param sl
* the offset (exclusive) past the last byte to be converted.
* @param dst
* the destination byte array of decoded data bytes
* @param dp
* the offset into dst array to begin writing
* @param isURL
* boolean, when true decode RFC4648 URL-safe base64 characters
* @return the number of destination data bytes produced
*/
@IntrinsicCandidate
private int decodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL) {
int[] base64 = isURL ? fromBase64URL : fromBase64;
int sl0 = sp + ((sl - sp) & ~0b11);
int new_dp = dp;
while (sp < sl0) {
int b1 = base64[src[sp++] & 0xff];
int b2 = base64[src[sp++] & 0xff];
int b3 = base64[src[sp++] & 0xff];
int b4 = base64[src[sp++] & 0xff];
if ((b1 | b2 | b3 | b4) < 0) { // non base64 byte
return new_dp - dp;
}
int bits0 = b1 << 18 | b2 << 12 | b3 << 6 | b4;
dst[new_dp++] = (byte)(bits0 >> 16);
dst[new_dp++] = (byte)(bits0 >> 8);
dst[new_dp++] = (byte)(bits0);
}
return new_dp - dp;
}
private int decode0(byte[] src, int sp, int sl, byte[] dst) {
int[] base64 = isURL ? fromBase64URL : fromBase64;
int dp = 0;
int bits = 0;
int shiftto = 18; // pos of first byte of 4-byte atom
while (sp < sl) {
if (shiftto == 18 && sp < sl - 4) { // fast path
int dl = decodeBlock(src, sp, sl, dst, dp, isURL);
/*
* Calculate how many characters were processed by how many
* bytes of data were returned.
*/
int chars_decoded = (dl / 3) * 4;
sp += chars_decoded;
dp += dl;
}
if (sp >= sl) {
// we're done
break;
}
int b = src[sp++] & 0xff;
if ((b = base64[b]) < 0) {
if (b == -2) { // padding byte '='
// = shiftto==18 unnecessary padding
// x= shiftto==12 a dangling single x
// x to be handled together with non-padding case
// xx= shiftto==6&&sp==sl missing last =
// xx=y shiftto==6 last is not =
if (shiftto == 6 && (sp == sl || src[sp++] != '=') ||
shiftto == 18) {
throw new IllegalArgumentException(
"Input byte array has wrong 4-byte ending unit");
}
break;
}
if (isMIME) // skip if for rfc2045
continue;
else
throw new IllegalArgumentException(
"Illegal base64 character " +
Integer.toString(src[sp - 1], 16));
}
bits |= (b << shiftto);
shiftto -= 6;
if (shiftto < 0) {
dst[dp++] = (byte)(bits >> 16);
dst[dp++] = (byte)(bits >> 8);
dst[dp++] = (byte)(bits);
shiftto = 18;
bits = 0;
}
}
// reached end of byte array or hit padding '=' characters.
if (shiftto == 6) {
dst[dp++] = (byte)(bits >> 16);
} else if (shiftto == 0) {
dst[dp++] = (byte)(bits >> 16);
dst[dp++] = (byte)(bits >> 8);
} else if (shiftto == 12) {
// dangling single "x", incorrectly encoded.
throw new IllegalArgumentException(
"Last unit does not have enough valid bits");
}
// anything left is invalid, if is not MIME.
// if MIME, ignore all non-base64 character
while (sp < sl) {
if (isMIME && base64[src[sp++] & 0xff] < 0)
continue;
throw new IllegalArgumentException(
"Input byte array has incorrect ending byte at " + sp);
}
return dp;
}
}
/*
* An output stream for encoding bytes into the Base64.
*/
private static class EncOutputStream extends FilterOutputStream {
private int leftover = 0;
private int b0, b1, b2;
private boolean closed = false;
private final char[] base64; // byte->base64 mapping
private final byte[] newline; // line separator, if needed
private final int linemax;
private final boolean doPadding;// whether or not to pad
private int linepos = 0;
private byte[] buf;
EncOutputStream(OutputStream os, char[] base64,
byte[] newline, int linemax, boolean doPadding) {
super(os);
this.base64 = base64;
this.newline = newline;
this.linemax = linemax;
this.doPadding = doPadding;
this.buf = new byte[linemax <= 0 ? 8124 : linemax];
}
@Override
public void write(int b) throws IOException {
byte[] buf = new byte[1];
buf[0] = (byte)(b & 0xff);
write(buf, 0, 1);
}
private void checkNewline() throws IOException {
if (linepos == linemax) {
out.write(newline);
linepos = 0;
}
}
private void writeb4(char b1, char b2, char b3, char b4) throws IOException {
buf[0] = (byte)b1;
buf[1] = (byte)b2;
buf[2] = (byte)b3;
buf[3] = (byte)b4;
out.write(buf, 0, 4);
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
if (closed)
throw new IOException("Stream is closed");
if (off < 0 || len < 0 || len > b.length - off)
throw new ArrayIndexOutOfBoundsException();
if (len == 0)
return;
if (leftover != 0) {
if (leftover == 1) {
b1 = b[off++] & 0xff;
len--;
if (len == 0) {
leftover++;
return;
}
}
b2 = b[off++] & 0xff;
len--;
checkNewline();
writeb4(base64[b0 >> 2],
base64[(b0 << 4) & 0x3f | (b1 >> 4)],
base64[(b1 << 2) & 0x3f | (b2 >> 6)],
base64[b2 & 0x3f]);
linepos += 4;
}
int nBits24 = len / 3;
leftover = len - (nBits24 * 3);
while (nBits24 > 0) {
checkNewline();
int dl = linemax <= 0 ? buf.length : buf.length - linepos;
int sl = off + Math.min(nBits24, dl / 4) * 3;
int dp = 0;
for (int sp = off; sp < sl; ) {
int bits = (b[sp++] & 0xff) << 16 |
(b[sp++] & 0xff) << 8 |
(b[sp++] & 0xff);
buf[dp++] = (byte)base64[(bits >>> 18) & 0x3f];
buf[dp++] = (byte)base64[(bits >>> 12) & 0x3f];
buf[dp++] = (byte)base64[(bits >>> 6) & 0x3f];
buf[dp++] = (byte)base64[bits & 0x3f];
}
out.write(buf, 0, dp);
off = sl;
linepos += dp;
nBits24 -= dp / 4;
}
if (leftover == 1) {
b0 = b[off++] & 0xff;
} else if (leftover == 2) {
b0 = b[off++] & 0xff;
b1 = b[off++] & 0xff;
}
}
@Override
public void close() throws IOException {
if (!closed) {
closed = true;
if (leftover == 1) {
checkNewline();
out.write(base64[b0 >> 2]);
out.write(base64[(b0 << 4) & 0x3f]);
if (doPadding) {
out.write('=');
out.write('=');
}
} else if (leftover == 2) {
checkNewline();
out.write(base64[b0 >> 2]);
out.write(base64[(b0 << 4) & 0x3f | (b1 >> 4)]);
out.write(base64[(b1 << 2) & 0x3f]);
if (doPadding) {
out.write('=');
}
}
leftover = 0;
out.close();
}
}
}
/*
* An input stream for decoding Base64 bytes
*/
private static class DecInputStream extends InputStream {
private final InputStream is;
private final boolean isMIME;
private final int[] base64; // base64 -> byte mapping
private int bits = 0; // 24-bit buffer for decoding
/* writing bit pos inside bits; one of 24 (left, msb), 18, 12, 6, 0 */
private int wpos = 0;
/* reading bit pos inside bits: one of 24 (left, msb), 16, 8, 0 */
private int rpos = 0;
private boolean eof = false;
private boolean closed = false;
DecInputStream(InputStream is, int[] base64, boolean isMIME) {
this.is = is;
this.base64 = base64;
this.isMIME = isMIME;
}
private byte[] sbBuf = new byte[1];
@Override
public int read() throws IOException {
return read(sbBuf, 0, 1) == -1 ? -1 : sbBuf[0] & 0xff;
}
private int leftovers(byte[] b, int off, int pos, int limit) {
eof = true;
/*
* We use a loop here, as this method is executed only a few times.
* Unrolling the loop would probably not contribute much here.
*/
while (rpos - 8 >= wpos && pos != limit) {
rpos -= 8;
b[pos++] = (byte) (bits >> rpos);
}
return pos - off != 0 || rpos - 8 >= wpos ? pos - off : -1;
}
private int eof(byte[] b, int off, int pos, int limit) throws IOException {
/*
* pos != limit
*
* wpos == 18: x dangling single x, invalid unit
* accept ending xx or xxx without padding characters
*/
if (wpos == 18) {
throw new IOException("Base64 stream has one un-decoded dangling byte.");
}
rpos = 24;
return leftovers(b, off, pos, limit);
}
private int padding(byte[] b, int off, int pos, int limit) throws IOException {
/*
* pos != limit
*
* wpos == 24: = (unnecessary padding)
* wpos == 18: x= (dangling single x, invalid unit)
* wpos == 12 and missing last '=': xx= (invalid padding)
* wpos == 12 and last is not '=': xx=x (invalid padding)
*/
if (wpos >= 18 || wpos == 12 && is.read() != '=') {
throw new IOException("Illegal base64 ending sequence:" + wpos);
}
rpos = 24;
return leftovers(b, off, pos, limit);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (closed) {
throw new IOException("Stream is closed");
}
Objects.checkFromIndexSize(off, len, b.length);
if (len == 0) {
return 0;
}
/*
* Rather than keeping 2 running vars (e.g., off and len),
* we only keep one (pos), while definitely fixing the boundaries
* of the range [off, limit).
* More specifically, each use of pos as an index in b meets
* pos - off >= 0 & limit - pos > 0
*
* Note that limit can overflow to Integer.MIN_VALUE. However,
* as long as comparisons with pos are as coded, there's no harm.
*/
int pos = off;
final int limit = off + len;
if (eof) {
return leftovers(b, off, pos, limit);
}
/*
* Leftovers from previous invocation; here, wpos = 0.
* There can be at most 2 leftover bytes (rpos <= 16).
* Further, b has at least one free place.
*
* The logic could be coded as a loop, (as in method leftovers())
* but the explicit "unrolling" makes it possible to generate
* better byte extraction code.
*/
if (rpos == 16) {
b[pos++] = (byte) (bits >> 8);
rpos = 8;
if (pos == limit) {
return len;
}
}
if (rpos == 8) {
b[pos++] = (byte) bits;
rpos = 0;
if (pos == limit) {
return len;
}
}
bits = 0;
wpos = 24;
for (;;) {
/* pos != limit & rpos == 0 */
final int i = is.read();
if (i < 0) {
return eof(b, off, pos, limit);
}
final int v = base64[i];
if (v < 0) {
/*
* i not in alphabet, thus
* v == -2: i is '=', the padding
* v == -1: i is something else, typically CR or LF
*/
if (v == -1) {
if (isMIME) {
continue;
}
throw new IOException("Illegal base64 character 0x" +
Integer.toHexString(i));
}
return padding(b, off, pos, limit);
}
wpos -= 6;
bits |= v << wpos;
if (wpos != 0) {
continue;
}
if (limit - pos >= 3) {
/* frequently taken fast path, no need to track rpos */
b[pos++] = (byte) (bits >> 16);
b[pos++] = (byte) (bits >> 8);
b[pos++] = (byte) bits;
bits = 0;
wpos = 24;
if (pos == limit) {
return len;
}
continue;
}
/* b has either 1 or 2 free places */
b[pos++] = (byte) (bits >> 16);
if (pos == limit) {
rpos = 16;
return len;
}
b[pos++] = (byte) (bits >> 8);
/* pos == limit, no need for an if */
rpos = 8;
return len;
}
}
@Override
public int available() throws IOException {
if (closed)
throw new IOException("Stream is closed");
return is.available(); // TBD:
}
@Override
public void close() throws IOException {
if (!closed) {
closed = true;
is.close();
}
}
}
}