1 /*
2 * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util;
27
28 import java.io.FilterOutputStream;
29 import java.io.InputStream;
30 import java.io.IOException;
31 import java.io.OutputStream;
32 import java.nio.ByteBuffer;
33
34 import sun.nio.cs.ISO_8859_1;
35
36 import jdk.internal.HotSpotIntrinsicCandidate;
37
38 /**
39 * This class consists exclusively of static methods for obtaining
40 * encoders and decoders for the Base64 encoding scheme. The
41 * implementation of this class supports the following types of Base64
42 * as specified in
43 * <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a> and
44 * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
45 *
46 * <ul>
47 * <li><a id="basic"><b>Basic</b></a>
48 * <p> Uses "The Base64 Alphabet" as specified in Table 1 of
49 * RFC 4648 and RFC 2045 for encoding and decoding operation.
50 * The encoder does not add any line feed (line separator)
51 * character. The decoder rejects data that contains characters
52 * outside the base64 alphabet.</p></li>
53 *
54 * <li><a id="url"><b>URL and Filename safe</b></a>
55 * <p> Uses the "URL and Filename safe Base64 Alphabet" as specified
56 * in Table 2 of RFC 4648 for encoding and decoding. The
57 * encoder does not add any line feed (line separator) character.
58 * The decoder rejects data that contains characters outside the
59 * base64 alphabet.</p></li>
60 *
61 * <li><a id="mime"><b>MIME</b></a>
62 * <p> Uses "The Base64 Alphabet" as specified in Table 1 of
63 * RFC 2045 for encoding and decoding operation. The encoded output
64 * must be represented in lines of no more than 76 characters each
65 * and uses a carriage return {@code '\r'} followed immediately by
66 * a linefeed {@code '\n'} as the line separator. No line separator
67 * is added to the end of the encoded output. All line separators
68 * or other characters not found in the base64 alphabet table are
69 * ignored in decoding operation.</p></li>
70 * </ul>
71 *
72 * <p> Unless otherwise noted, passing a {@code null} argument to a
73 * method of this class will cause a {@link java.lang.NullPointerException
74 * NullPointerException} to be thrown.
75 *
76 * @author Xueming Shen
77 * @since 1.8
78 */
79
80 public class Base64 {
81
82 private Base64() {}
83
84 /**
85 * Returns a {@link Encoder} that encodes using the
86 * <a href="#basic">Basic</a> type base64 encoding scheme.
87 *
88 * @return A Base64 encoder.
89 */
90 public static Encoder getEncoder() {
91 return Encoder.RFC4648;
92 }
93
94 /**
95 * Returns a {@link Encoder} that encodes using the
96 * <a href="#url">URL and Filename safe</a> type base64
97 * encoding scheme.
98 *
99 * @return A Base64 encoder.
100 */
101 public static Encoder getUrlEncoder() {
102 return Encoder.RFC4648_URLSAFE;
103 }
104
105 /**
106 * Returns a {@link Encoder} that encodes using the
107 * <a href="#mime">MIME</a> type base64 encoding scheme.
108 *
109 * @return A Base64 encoder.
110 */
111 public static Encoder getMimeEncoder() {
112 return Encoder.RFC2045;
113 }
114
115 /**
116 * Returns a {@link Encoder} that encodes using the
117 * <a href="#mime">MIME</a> type base64 encoding scheme
118 * with specified line length and line separators.
119 *
120 * @param lineLength
121 * the length of each output line (rounded down to nearest multiple
122 * of 4). If the rounded down line length is not a positive value,
123 * the output will not be separated in lines
124 * @param lineSeparator
125 * the line separator for each output line
126 *
127 * @return A Base64 encoder.
128 *
129 * @throws IllegalArgumentException if {@code lineSeparator} includes any
130 * character of "The Base64 Alphabet" as specified in Table 1 of
131 * RFC 2045.
132 */
133 public static Encoder getMimeEncoder(int lineLength, byte[] lineSeparator) {
134 Objects.requireNonNull(lineSeparator);
135 int[] base64 = Decoder.fromBase64;
136 for (byte b : lineSeparator) {
137 if (base64[b & 0xff] != -1)
138 throw new IllegalArgumentException(
139 "Illegal base64 line separator character 0x" + Integer.toString(b, 16));
140 }
141 // round down to nearest multiple of 4
142 lineLength &= ~0b11;
143 if (lineLength <= 0) {
144 return Encoder.RFC4648;
145 }
146 return new Encoder(false, lineSeparator, lineLength, true);
147 }
148
149 /**
150 * Returns a {@link Decoder} that decodes using the
151 * <a href="#basic">Basic</a> type base64 encoding scheme.
152 *
153 * @return A Base64 decoder.
154 */
155 public static Decoder getDecoder() {
156 return Decoder.RFC4648;
157 }
158
159 /**
160 * Returns a {@link Decoder} that decodes using the
161 * <a href="#url">URL and Filename safe</a> type base64
162 * encoding scheme.
163 *
164 * @return A Base64 decoder.
165 */
166 public static Decoder getUrlDecoder() {
167 return Decoder.RFC4648_URLSAFE;
168 }
169
170 /**
171 * Returns a {@link Decoder} that decodes using the
172 * <a href="#mime">MIME</a> type base64 decoding scheme.
173 *
174 * @return A Base64 decoder.
175 */
176 public static Decoder getMimeDecoder() {
177 return Decoder.RFC2045;
178 }
179
180 /**
181 * This class implements an encoder for encoding byte data using
182 * the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
183 *
184 * <p> Instances of {@link Encoder} class are safe for use by
185 * multiple concurrent threads.
186 *
187 * <p> Unless otherwise noted, passing a {@code null} argument to
188 * a method of this class will cause a
189 * {@link java.lang.NullPointerException NullPointerException} to
190 * be thrown.
191 * <p> If the encoded byte output of the needed size can not
192 * be allocated, the encode methods of this class will
193 * cause an {@link java.lang.OutOfMemoryError OutOfMemoryError}
194 * to be thrown.
195 *
196 * @see Decoder
197 * @since 1.8
198 */
199 public static class Encoder {
200
201 private final byte[] newline;
202 private final int linemax;
203 private final boolean isURL;
204 private final boolean doPadding;
205
206 private Encoder(boolean isURL, byte[] newline, int linemax, boolean doPadding) {
207 this.isURL = isURL;
208 this.newline = newline;
209 this.linemax = linemax;
210 this.doPadding = doPadding;
211 }
212
213 /**
214 * This array is a lookup table that translates 6-bit positive integer
215 * index values into their "Base64 Alphabet" equivalents as specified
216 * in "Table 1: The Base64 Alphabet" of RFC 2045 (and RFC 4648).
217 */
218 private static final char[] toBase64 = {
219 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
220 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
221 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
222 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
223 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
224 };
225
226 /**
227 * It's the lookup table for "URL and Filename safe Base64" as specified
228 * in Table 2 of the RFC 4648, with the '+' and '/' changed to '-' and
229 * '_'. This table is used when BASE64_URL is specified.
230 */
231 private static final char[] toBase64URL = {
232 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
233 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
234 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
235 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
236 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
237 };
238
239 private static final int MIMELINEMAX = 76;
240 private static final byte[] CRLF = new byte[] {'\r', '\n'};
241
242 static final Encoder RFC4648 = new Encoder(false, null, -1, true);
243 static final Encoder RFC4648_URLSAFE = new Encoder(true, null, -1, true);
244 static final Encoder RFC2045 = new Encoder(false, CRLF, MIMELINEMAX, true);
245
246 /**
247 * Calculates the length of the encoded output bytes.
248 *
249 * @param srclen length of the bytes to encode
250 * @param throwOOME if true, throws OutOfMemoryError if the length of
251 * the encoded bytes overflows; else returns the
252 * length
253 * @return length of the encoded bytes, or -1 if the length overflows
254 *
255 */
256 private final int encodedOutLength(int srclen, boolean throwOOME) {
257 int len = 0;
258 try {
259 if (doPadding) {
260 len = Math.multiplyExact(4, (Math.addExact(srclen, 2) / 3));
261 } else {
262 int n = srclen % 3;
263 len = Math.addExact(Math.multiplyExact(4, (srclen / 3)), (n == 0 ? 0 : n + 1));
264 }
265 if (linemax > 0) { // line separators
266 len = Math.addExact(len, (len - 1) / linemax * newline.length);
267 }
268 } catch (ArithmeticException ex) {
269 if (throwOOME) {
270 throw new OutOfMemoryError("Encoded size is too large");
271 } else {
272 // let the caller know that encoded bytes length
273 // is too large
274 len = -1;
275 }
276 }
277 return len;
278 }
279
280 /**
281 * Encodes all bytes from the specified byte array into a newly-allocated
282 * byte array using the {@link Base64} encoding scheme. The returned byte
283 * array is of the length of the resulting bytes.
284 *
285 * @param src
286 * the byte array to encode
287 * @return A newly-allocated byte array containing the resulting
288 * encoded bytes.
289 */
290 public byte[] encode(byte[] src) {
291 int len = encodedOutLength(src.length, true); // dst array size
292 byte[] dst = new byte[len];
293 int ret = encode0(src, 0, src.length, dst);
294 if (ret != dst.length)
295 return Arrays.copyOf(dst, ret);
296 return dst;
297 }
298
299 /**
300 * Encodes all bytes from the specified byte array using the
301 * {@link Base64} encoding scheme, writing the resulting bytes to the
302 * given output byte array, starting at offset 0.
303 *
304 * <p> It is the responsibility of the invoker of this method to make
305 * sure the output byte array {@code dst} has enough space for encoding
306 * all bytes from the input byte array. No bytes will be written to the
307 * output byte array if the output byte array is not big enough.
308 *
309 * @param src
310 * the byte array to encode
311 * @param dst
312 * the output byte array
313 * @return The number of bytes written to the output byte array
314 *
315 * @throws IllegalArgumentException if {@code dst} does not have enough
316 * space for encoding all input bytes.
317 */
318 public int encode(byte[] src, byte[] dst) {
319 int len = encodedOutLength(src.length, false); // dst array size
320 if (dst.length < len || len == -1)
321 throw new IllegalArgumentException(
322 "Output byte array is too small for encoding all input bytes");
323 return encode0(src, 0, src.length, dst);
324 }
325
326 /**
327 * Encodes the specified byte array into a String using the {@link Base64}
328 * encoding scheme.
329 *
330 * <p> This method first encodes all input bytes into a base64 encoded
331 * byte array and then constructs a new String by using the encoded byte
332 * array and the {@link java.nio.charset.StandardCharsets#ISO_8859_1
333 * ISO-8859-1} charset.
334 *
335 * <p> In other words, an invocation of this method has exactly the same
336 * effect as invoking
337 * {@code new String(encode(src), StandardCharsets.ISO_8859_1)}.
338 *
339 * @param src
340 * the byte array to encode
341 * @return A String containing the resulting Base64 encoded characters
342 */
343 @SuppressWarnings("deprecation")
344 public String encodeToString(byte[] src) {
345 byte[] encoded = encode(src);
346 return new String(encoded, 0, 0, encoded.length);
347 }
348
349 /**
350 * Encodes all remaining bytes from the specified byte buffer into
351 * a newly-allocated ByteBuffer using the {@link Base64} encoding
352 * scheme.
353 *
354 * Upon return, the source buffer's position will be updated to
355 * its limit; its limit will not have been changed. The returned
356 * output buffer's position will be zero and its limit will be the
357 * number of resulting encoded bytes.
358 *
359 * @param buffer
360 * the source ByteBuffer to encode
361 * @return A newly-allocated byte buffer containing the encoded bytes.
362 */
363 public ByteBuffer encode(ByteBuffer buffer) {
364 int len = encodedOutLength(buffer.remaining(), true);
365 byte[] dst = new byte[len];
366 int ret = 0;
367 if (buffer.hasArray()) {
368 ret = encode0(buffer.array(),
369 buffer.arrayOffset() + buffer.position(),
370 buffer.arrayOffset() + buffer.limit(),
371 dst);
372 buffer.position(buffer.limit());
373 } else {
374 byte[] src = new byte[buffer.remaining()];
375 buffer.get(src);
376 ret = encode0(src, 0, src.length, dst);
377 }
378 if (ret != dst.length)
379 dst = Arrays.copyOf(dst, ret);
380 return ByteBuffer.wrap(dst);
381 }
382
383 /**
384 * Wraps an output stream for encoding byte data using the {@link Base64}
385 * encoding scheme.
386 *
387 * <p> It is recommended to promptly close the returned output stream after
388 * use, during which it will flush all possible leftover bytes to the underlying
389 * output stream. Closing the returned output stream will close the underlying
390 * output stream.
391 *
392 * @param os
393 * the output stream.
394 * @return the output stream for encoding the byte data into the
395 * specified Base64 encoded format
396 */
397 public OutputStream wrap(OutputStream os) {
398 Objects.requireNonNull(os);
399 return new EncOutputStream(os, isURL ? toBase64URL : toBase64,
400 newline, linemax, doPadding);
401 }
402
403 /**
404 * Returns an encoder instance that encodes equivalently to this one,
405 * but without adding any padding character at the end of the encoded
406 * byte data.
407 *
408 * <p> The encoding scheme of this encoder instance is unaffected by
409 * this invocation. The returned encoder instance should be used for
410 * non-padding encoding operation.
411 *
412 * @return an equivalent encoder that encodes without adding any
413 * padding character at the end
414 */
415 public Encoder withoutPadding() {
416 if (!doPadding)
417 return this;
418 return new Encoder(isURL, newline, linemax, false);
419 }
420
421 @HotSpotIntrinsicCandidate
422 private void encodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL) {
423 char[] base64 = isURL ? toBase64URL : toBase64;
424 for (int sp0 = sp, dp0 = dp ; sp0 < sl; ) {
425 int bits = (src[sp0++] & 0xff) << 16 |
426 (src[sp0++] & 0xff) << 8 |
427 (src[sp0++] & 0xff);
428 dst[dp0++] = (byte)base64[(bits >>> 18) & 0x3f];
429 dst[dp0++] = (byte)base64[(bits >>> 12) & 0x3f];
430 dst[dp0++] = (byte)base64[(bits >>> 6) & 0x3f];
431 dst[dp0++] = (byte)base64[bits & 0x3f];
432 }
433 }
434
435 private int encode0(byte[] src, int off, int end, byte[] dst) {
436 char[] base64 = isURL ? toBase64URL : toBase64;
437 int sp = off;
438 int slen = (end - off) / 3 * 3;
439 int sl = off + slen;
440 if (linemax > 0 && slen > linemax / 4 * 3)
441 slen = linemax / 4 * 3;
442 int dp = 0;
443 while (sp < sl) {
444 int sl0 = Math.min(sp + slen, sl);
445 encodeBlock(src, sp, sl0, dst, dp, isURL);
446 int dlen = (sl0 - sp) / 3 * 4;
447 dp += dlen;
448 sp = sl0;
449 if (dlen == linemax && sp < end) {
450 for (byte b : newline){
451 dst[dp++] = b;
452 }
453 }
454 }
455 if (sp < end) { // 1 or 2 leftover bytes
456 int b0 = src[sp++] & 0xff;
457 dst[dp++] = (byte)base64[b0 >> 2];
458 if (sp == end) {
459 dst[dp++] = (byte)base64[(b0 << 4) & 0x3f];
460 if (doPadding) {
461 dst[dp++] = '=';
462 dst[dp++] = '=';
463 }
464 } else {
465 int b1 = src[sp++] & 0xff;
466 dst[dp++] = (byte)base64[(b0 << 4) & 0x3f | (b1 >> 4)];
467 dst[dp++] = (byte)base64[(b1 << 2) & 0x3f];
468 if (doPadding) {
469 dst[dp++] = '=';
470 }
471 }
472 }
473 return dp;
474 }
475 }
476
477 /**
478 * This class implements a decoder for decoding byte data using the
479 * Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
480 *
481 * <p> The Base64 padding character {@code '='} is accepted and
482 * interpreted as the end of the encoded byte data, but is not
483 * required. So if the final unit of the encoded byte data only has
484 * two or three Base64 characters (without the corresponding padding
485 * character(s) padded), they are decoded as if followed by padding
486 * character(s). If there is a padding character present in the
487 * final unit, the correct number of padding character(s) must be
488 * present, otherwise {@code IllegalArgumentException} (
489 * {@code IOException} when reading from a Base64 stream) is thrown
490 * during decoding.
491 *
492 * <p> Instances of {@link Decoder} class are safe for use by
493 * multiple concurrent threads.
494 *
495 * <p> Unless otherwise noted, passing a {@code null} argument to
496 * a method of this class will cause a
497 * {@link java.lang.NullPointerException NullPointerException} to
498 * be thrown.
499 * <p> If the decoded byte output of the needed size can not
500 * be allocated, the decode methods of this class will
501 * cause an {@link java.lang.OutOfMemoryError OutOfMemoryError}
502 * to be thrown.
503 *
504 * @see Encoder
505 * @since 1.8
506 */
507 public static class Decoder {
508
509 private final boolean isURL;
510 private final boolean isMIME;
511
512 private Decoder(boolean isURL, boolean isMIME) {
513 this.isURL = isURL;
514 this.isMIME = isMIME;
515 }
516
517 /**
518 * Lookup table for decoding unicode characters drawn from the
519 * "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into
520 * their 6-bit positive integer equivalents. Characters that
521 * are not in the Base64 alphabet but fall within the bounds of
522 * the array are encoded to -1.
523 *
524 */
525 private static final int[] fromBase64 = new int[256];
526 static {
527 Arrays.fill(fromBase64, -1);
528 for (int i = 0; i < Encoder.toBase64.length; i++)
529 fromBase64[Encoder.toBase64[i]] = i;
530 fromBase64['='] = -2;
531 }
532
533 /**
534 * Lookup table for decoding "URL and Filename safe Base64 Alphabet"
535 * as specified in Table2 of the RFC 4648.
536 */
537 private static final int[] fromBase64URL = new int[256];
538
539 static {
540 Arrays.fill(fromBase64URL, -1);
541 for (int i = 0; i < Encoder.toBase64URL.length; i++)
542 fromBase64URL[Encoder.toBase64URL[i]] = i;
543 fromBase64URL['='] = -2;
544 }
545
546 static final Decoder RFC4648 = new Decoder(false, false);
547 static final Decoder RFC4648_URLSAFE = new Decoder(true, false);
548 static final Decoder RFC2045 = new Decoder(false, true);
549
550 /**
551 * Decodes all bytes from the input byte array using the {@link Base64}
552 * encoding scheme, writing the results into a newly-allocated output
553 * byte array. The returned byte array is of the length of the resulting
554 * bytes.
555 *
556 * @param src
557 * the byte array to decode
558 *
559 * @return A newly-allocated byte array containing the decoded bytes.
560 *
561 * @throws IllegalArgumentException
562 * if {@code src} is not in valid Base64 scheme
563 */
564 public byte[] decode(byte[] src) {
565 byte[] dst = new byte[decodedOutLength(src, 0, src.length)];
566 int ret = decode0(src, 0, src.length, dst);
567 if (ret != dst.length) {
568 dst = Arrays.copyOf(dst, ret);
569 }
570 return dst;
571 }
572
573 /**
574 * Decodes a Base64 encoded String into a newly-allocated byte array
575 * using the {@link Base64} encoding scheme.
576 *
577 * <p> An invocation of this method has exactly the same effect as invoking
578 * {@code decode(src.getBytes(StandardCharsets.ISO_8859_1))}
579 *
580 * @param src
581 * the string to decode
582 *
583 * @return A newly-allocated byte array containing the decoded bytes.
584 *
585 * @throws IllegalArgumentException
586 * if {@code src} is not in valid Base64 scheme
587 */
588 public byte[] decode(String src) {
589 return decode(src.getBytes(ISO_8859_1.INSTANCE));
590 }
591
592 /**
593 * Decodes all bytes from the input byte array using the {@link Base64}
594 * encoding scheme, writing the results into the given output byte array,
595 * starting at offset 0.
596 *
597 * <p> It is the responsibility of the invoker of this method to make
598 * sure the output byte array {@code dst} has enough space for decoding
599 * all bytes from the input byte array. No bytes will be written to
600 * the output byte array if the output byte array is not big enough.
601 *
602 * <p> If the input byte array is not in valid Base64 encoding scheme
603 * then some bytes may have been written to the output byte array before
604 * IllegalargumentException is thrown.
605 *
606 * @param src
607 * the byte array to decode
608 * @param dst
609 * the output byte array
610 *
611 * @return The number of bytes written to the output byte array
612 *
613 * @throws IllegalArgumentException
614 * if {@code src} is not in valid Base64 scheme, or {@code dst}
615 * does not have enough space for decoding all input bytes.
616 */
617 public int decode(byte[] src, byte[] dst) {
618 int len = decodedOutLength(src, 0, src.length);
619 if (dst.length < len || len == -1)
620 throw new IllegalArgumentException(
621 "Output byte array is too small for decoding all input bytes");
622 return decode0(src, 0, src.length, dst);
623 }
624
625 /**
626 * Decodes all bytes from the input byte buffer using the {@link Base64}
627 * encoding scheme, writing the results into a newly-allocated ByteBuffer.
628 *
629 * <p> Upon return, the source buffer's position will be updated to
630 * its limit; its limit will not have been changed. The returned
631 * output buffer's position will be zero and its limit will be the
632 * number of resulting decoded bytes
633 *
634 * <p> {@code IllegalArgumentException} is thrown if the input buffer
635 * is not in valid Base64 encoding scheme. The position of the input
636 * buffer will not be advanced in this case.
637 *
638 * @param buffer
639 * the ByteBuffer to decode
640 *
641 * @return A newly-allocated byte buffer containing the decoded bytes
642 *
643 * @throws IllegalArgumentException
644 * if {@code buffer} is not in valid Base64 scheme
645 */
646 public ByteBuffer decode(ByteBuffer buffer) {
647 int pos0 = buffer.position();
648 try {
649 byte[] src;
650 int sp, sl;
651 if (buffer.hasArray()) {
652 src = buffer.array();
653 sp = buffer.arrayOffset() + buffer.position();
654 sl = buffer.arrayOffset() + buffer.limit();
655 buffer.position(buffer.limit());
656 } else {
657 src = new byte[buffer.remaining()];
658 buffer.get(src);
659 sp = 0;
660 sl = src.length;
661 }
662 byte[] dst = new byte[decodedOutLength(src, sp, sl)];
663 return ByteBuffer.wrap(dst, 0, decode0(src, sp, sl, dst));
664 } catch (IllegalArgumentException iae) {
665 buffer.position(pos0);
666 throw iae;
667 }
668 }
669
670 /**
671 * Returns an input stream for decoding {@link Base64} encoded byte stream.
672 *
673 * <p> The {@code read} methods of the returned {@code InputStream} will
674 * throw {@code IOException} when reading bytes that cannot be decoded.
675 *
676 * <p> Closing the returned input stream will close the underlying
677 * input stream.
678 *
679 * @param is
680 * the input stream
681 *
682 * @return the input stream for decoding the specified Base64 encoded
683 * byte stream
684 */
685 public InputStream wrap(InputStream is) {
686 Objects.requireNonNull(is);
687 return new DecInputStream(is, isURL ? fromBase64URL : fromBase64, isMIME);
688 }
689
690 /**
691 * Calculates the length of the decoded output bytes.
692 *
693 * @param src the byte array to decode
694 * @param sp the source position
695 * @param sl the source limit
696 *
697 * @return length of the decoded bytes
698 *
699 */
700 private int decodedOutLength(byte[] src, int sp, int sl) {
701 int[] base64 = isURL ? fromBase64URL : fromBase64;
702 int paddings = 0;
703 int len = sl - sp;
704 if (len == 0)
705 return 0;
706 if (len < 2) {
707 if (isMIME && base64[0] == -1)
708 return 0;
709 throw new IllegalArgumentException(
710 "Input byte[] should at least have 2 bytes for base64 bytes");
711 }
712 if (isMIME) {
713 // scan all bytes to fill out all non-alphabet. a performance
714 // trade-off of pre-scan or Arrays.copyOf
715 int n = 0;
716 while (sp < sl) {
717 int b = src[sp++] & 0xff;
718 if (b == '=') {
719 len -= (sl - sp + 1);
720 break;
721 }
722 if ((b = base64[b]) == -1)
723 n++;
724 }
725 len -= n;
726 } else {
727 if (src[sl - 1] == '=') {
728 paddings++;
729 if (src[sl - 2] == '=')
730 paddings++;
731 }
732 }
733 if (paddings == 0 && (len & 0x3) != 0)
734 paddings = 4 - (len & 0x3);
735
736 // If len is near to Integer.MAX_VALUE, (len + 3)
737 // can possibly overflow, perform this operation as
738 // long and cast it back to integer when the value comes under
739 // integer limit. The final value will always be in integer
740 // limits
741 return 3 * (int) ((len + 3L) / 4) - paddings;
742 }
743
744 private int decode0(byte[] src, int sp, int sl, byte[] dst) {
745 int[] base64 = isURL ? fromBase64URL : fromBase64;
746 int dp = 0;
747 int bits = 0;
748 int shiftto = 18; // pos of first byte of 4-byte atom
749
750 while (sp < sl) {
751 if (shiftto == 18 && sp + 4 < sl) { // fast path
752 int sl0 = sp + ((sl - sp) & ~0b11);
753 while (sp < sl0) {
754 int b1 = base64[src[sp++] & 0xff];
755 int b2 = base64[src[sp++] & 0xff];
756 int b3 = base64[src[sp++] & 0xff];
757 int b4 = base64[src[sp++] & 0xff];
758 if ((b1 | b2 | b3 | b4) < 0) { // non base64 byte
759 sp -= 4;
760 break;
761 }
762 int bits0 = b1 << 18 | b2 << 12 | b3 << 6 | b4;
763 dst[dp++] = (byte)(bits0 >> 16);
764 dst[dp++] = (byte)(bits0 >> 8);
765 dst[dp++] = (byte)(bits0);
766 }
767 if (sp >= sl)
768 break;
769 }
770 int b = src[sp++] & 0xff;
771 if ((b = base64[b]) < 0) {
772 if (b == -2) { // padding byte '='
773 // = shiftto==18 unnecessary padding
774 // x= shiftto==12 a dangling single x
775 // x to be handled together with non-padding case
776 // xx= shiftto==6&&sp==sl missing last =
777 // xx=y shiftto==6 last is not =
778 if (shiftto == 6 && (sp == sl || src[sp++] != '=') ||
779 shiftto == 18) {
780 throw new IllegalArgumentException(
781 "Input byte array has wrong 4-byte ending unit");
782 }
783 break;
784 }
785 if (isMIME) // skip if for rfc2045
786 continue;
787 else
788 throw new IllegalArgumentException(
789 "Illegal base64 character " +
790 Integer.toString(src[sp - 1], 16));
791 }
792 bits |= (b << shiftto);
793 shiftto -= 6;
794 if (shiftto < 0) {
795 dst[dp++] = (byte)(bits >> 16);
796 dst[dp++] = (byte)(bits >> 8);
797 dst[dp++] = (byte)(bits);
798 shiftto = 18;
799 bits = 0;
800 }
801 }
802 // reached end of byte array or hit padding '=' characters.
803 if (shiftto == 6) {
804 dst[dp++] = (byte)(bits >> 16);
805 } else if (shiftto == 0) {
806 dst[dp++] = (byte)(bits >> 16);
807 dst[dp++] = (byte)(bits >> 8);
808 } else if (shiftto == 12) {
809 // dangling single "x", incorrectly encoded.
810 throw new IllegalArgumentException(
811 "Last unit does not have enough valid bits");
812 }
813 // anything left is invalid, if is not MIME.
814 // if MIME, ignore all non-base64 character
815 while (sp < sl) {
816 if (isMIME && base64[src[sp++] & 0xff] < 0)
817 continue;
818 throw new IllegalArgumentException(
819 "Input byte array has incorrect ending byte at " + sp);
820 }
821 return dp;
822 }
823 }
824
825 /*
826 * An output stream for encoding bytes into the Base64.
827 */
828 private static class EncOutputStream extends FilterOutputStream {
829
830 private int leftover = 0;
831 private int b0, b1, b2;
832 private boolean closed = false;
833
834 private final char[] base64; // byte->base64 mapping
835 private final byte[] newline; // line separator, if needed
836 private final int linemax;
837 private final boolean doPadding;// whether or not to pad
838 private int linepos = 0;
839 private byte[] buf;
840
841 EncOutputStream(OutputStream os, char[] base64,
842 byte[] newline, int linemax, boolean doPadding) {
843 super(os);
844 this.base64 = base64;
845 this.newline = newline;
846 this.linemax = linemax;
847 this.doPadding = doPadding;
848 this.buf = new byte[linemax <= 0 ? 8124 : linemax];
849 }
850
851 @Override
852 public void write(int b) throws IOException {
853 byte[] buf = new byte[1];
854 buf[0] = (byte)(b & 0xff);
855 write(buf, 0, 1);
856 }
857
858 private void checkNewline() throws IOException {
859 if (linepos == linemax) {
860 out.write(newline);
861 linepos = 0;
862 }
863 }
864
865 private void writeb4(char b1, char b2, char b3, char b4) throws IOException {
866 buf[0] = (byte)b1;
867 buf[1] = (byte)b2;
868 buf[2] = (byte)b3;
869 buf[3] = (byte)b4;
870 out.write(buf, 0, 4);
871 }
872
873 @Override
874 public void write(byte[] b, int off, int len) throws IOException {
875 if (closed)
876 throw new IOException("Stream is closed");
877 if (off < 0 || len < 0 || len > b.length - off)
878 throw new ArrayIndexOutOfBoundsException();
879 if (len == 0)
880 return;
881 if (leftover != 0) {
882 if (leftover == 1) {
883 b1 = b[off++] & 0xff;
884 len--;
885 if (len == 0) {
886 leftover++;
887 return;
888 }
889 }
890 b2 = b[off++] & 0xff;
891 len--;
892 checkNewline();
893 writeb4(base64[b0 >> 2],
894 base64[(b0 << 4) & 0x3f | (b1 >> 4)],
895 base64[(b1 << 2) & 0x3f | (b2 >> 6)],
896 base64[b2 & 0x3f]);
897 linepos += 4;
898 }
899 int nBits24 = len / 3;
900 leftover = len - (nBits24 * 3);
901
902 while (nBits24 > 0) {
903 checkNewline();
904 int dl = linemax <= 0 ? buf.length : buf.length - linepos;
905 int sl = off + Math.min(nBits24, dl / 4) * 3;
906 int dp = 0;
907 for (int sp = off; sp < sl; ) {
908 int bits = (b[sp++] & 0xff) << 16 |
909 (b[sp++] & 0xff) << 8 |
910 (b[sp++] & 0xff);
911 buf[dp++] = (byte)base64[(bits >>> 18) & 0x3f];
912 buf[dp++] = (byte)base64[(bits >>> 12) & 0x3f];
913 buf[dp++] = (byte)base64[(bits >>> 6) & 0x3f];
914 buf[dp++] = (byte)base64[bits & 0x3f];
915 }
916 out.write(buf, 0, dp);
917 off = sl;
918 linepos += dp;
919 nBits24 -= dp / 4;
920 }
921 if (leftover == 1) {
922 b0 = b[off++] & 0xff;
923 } else if (leftover == 2) {
924 b0 = b[off++] & 0xff;
925 b1 = b[off++] & 0xff;
926 }
927 }
928
929 @Override
930 public void close() throws IOException {
931 if (!closed) {
932 closed = true;
933 if (leftover == 1) {
934 checkNewline();
935 out.write(base64[b0 >> 2]);
936 out.write(base64[(b0 << 4) & 0x3f]);
937 if (doPadding) {
938 out.write('=');
939 out.write('=');
940 }
941 } else if (leftover == 2) {
942 checkNewline();
943 out.write(base64[b0 >> 2]);
944 out.write(base64[(b0 << 4) & 0x3f | (b1 >> 4)]);
945 out.write(base64[(b1 << 2) & 0x3f]);
946 if (doPadding) {
947 out.write('=');
948 }
949 }
950 leftover = 0;
951 out.close();
952 }
953 }
954 }
955
956 /*
957 * An input stream for decoding Base64 bytes
958 */
959 private static class DecInputStream extends InputStream {
960
961 private final InputStream is;
962 private final boolean isMIME;
963 private final int[] base64; // base64 -> byte mapping
964 private int bits = 0; // 24-bit buffer for decoding
965
966 /* writing bit pos inside bits; one of 24 (left, msb), 18, 12, 6, 0 */
967 private int wpos = 0;
968
969 /* reading bit pos inside bits: one of 24 (left, msb), 16, 8, 0 */
970 private int rpos = 0;
971
972 private boolean eof = false;
973 private boolean closed = false;
974
975 DecInputStream(InputStream is, int[] base64, boolean isMIME) {
976 this.is = is;
977 this.base64 = base64;
978 this.isMIME = isMIME;
979 }
980
981 private byte[] sbBuf = new byte[1];
982
983 @Override
984 public int read() throws IOException {
985 return read(sbBuf, 0, 1) == -1 ? -1 : sbBuf[0] & 0xff;
986 }
987
988 private int leftovers(byte[] b, int off, int pos, int limit) {
989 eof = true;
990
991 /*
992 * We use a loop here, as this method is executed only a few times.
993 * Unrolling the loop would probably not contribute much here.
994 */
995 while (rpos - 8 >= wpos && pos != limit) {
996 rpos -= 8;
997 b[pos++] = (byte) (bits >> rpos);
998 }
999 return pos - off != 0 || rpos - 8 >= wpos ? pos - off : -1;
1000 }
1001
1002 private int eof(byte[] b, int off, int pos, int limit) throws IOException {
1003 /*
1004 * pos != limit
1005 *
1006 * wpos == 18: x dangling single x, invalid unit
1007 * accept ending xx or xxx without padding characters
1008 */
1009 if (wpos == 18) {
1010 throw new IOException("Base64 stream has one un-decoded dangling byte.");
1011 }
1012 rpos = 24;
1013 return leftovers(b, off, pos, limit);
1014 }
1015
1016 private int padding(byte[] b, int off, int pos, int limit) throws IOException {
1017 /*
1018 * pos != limit
1019 *
1020 * wpos == 24: = (unnecessary padding)
1021 * wpos == 18: x= (dangling single x, invalid unit)
1022 * wpos == 12 and missing last '=': xx= (invalid padding)
1023 * wpos == 12 and last is not '=': xx=x (invalid padding)
1024 */
1025 if (wpos >= 18 || wpos == 12 && is.read() != '=') {
1026 throw new IOException("Illegal base64 ending sequence:" + wpos);
1027 }
1028 rpos = 24;
1029 return leftovers(b, off, pos, limit);
1030 }
1031
1032 @Override
1033 public int read(byte[] b, int off, int len) throws IOException {
1034 if (closed) {
1035 throw new IOException("Stream is closed");
1036 }
1037 Objects.checkFromIndexSize(off, len, b.length);
1038 if (len == 0) {
1039 return 0;
1040 }
1041
1042 /*
1043 * Rather than keeping 2 running vars (e.g., off and len),
1044 * we only keep one (pos), while definitely fixing the boundaries
1045 * of the range [off, limit).
1046 * More specifically, each use of pos as an index in b meets
1047 * pos - off >= 0 & limit - pos > 0
1048 *
1049 * Note that limit can overflow to Integer.MIN_VALUE. However,
1050 * as long as comparisons with pos are as coded, there's no harm.
1051 */
1052 int pos = off;
1053 final int limit = off + len;
1054 if (eof) {
1055 return leftovers(b, off, pos, limit);
1056 }
1057
1058 /*
1059 * Leftovers from previous invocation; here, wpos = 0.
1060 * There can be at most 2 leftover bytes (rpos <= 16).
1061 * Further, b has at least one free place.
1062 *
1063 * The logic could be coded as a loop, (as in method leftovers())
1064 * but the explicit "unrolling" makes it possible to generate
1065 * better byte extraction code.
1066 */
1067 if (rpos == 16) {
1068 b[pos++] = (byte) (bits >> 8);
1069 rpos = 8;
1070 if (pos == limit) {
1071 return len;
1072 }
1073 }
1074 if (rpos == 8) {
1075 b[pos++] = (byte) bits;
1076 rpos = 0;
1077 if (pos == limit) {
1078 return len;
1079 }
1080 }
1081
1082 bits = 0;
1083 wpos = 24;
1084 for (;;) {
1085 /* pos != limit & rpos == 0 */
1086 final int i = is.read();
1087 if (i < 0) {
1088 return eof(b, off, pos, limit);
1089 }
1090 final int v = base64[i];
1091 if (v < 0) {
1092 /*
1093 * i not in alphabet, thus
1094 * v == -2: i is '=', the padding
1095 * v == -1: i is something else, typically CR or LF
1096 */
1097 if (v == -1) {
1098 if (isMIME) {
1099 continue;
1100 }
1101 throw new IOException("Illegal base64 character 0x" +
1102 Integer.toHexString(i));
1103 }
1104 return padding(b, off, pos, limit);
1105 }
1106 wpos -= 6;
1107 bits |= v << wpos;
1108 if (wpos != 0) {
1109 continue;
1110 }
1111 if (limit - pos >= 3) {
1112 /* frequently taken fast path, no need to track rpos */
1113 b[pos++] = (byte) (bits >> 16);
1114 b[pos++] = (byte) (bits >> 8);
1115 b[pos++] = (byte) bits;
1116 bits = 0;
1117 wpos = 24;
1118 if (pos == limit) {
1119 return len;
1120 }
1121 continue;
1122 }
1123
1124 /* b has either 1 or 2 free places */
1125 b[pos++] = (byte) (bits >> 16);
1126 if (pos == limit) {
1127 rpos = 16;
1128 return len;
1129 }
1130 b[pos++] = (byte) (bits >> 8);
1131 /* pos == limit, no need for an if */
1132 rpos = 8;
1133 return len;
1134 }
1135 }
1136
1137 @Override
1138 public int available() throws IOException {
1139 if (closed)
1140 throw new IOException("Stream is closed");
1141 return is.available(); // TBD:
1142 }
1143
1144 @Override
1145 public void close() throws IOException {
1146 if (!closed) {
1147 closed = true;
1148 is.close();
1149 }
1150 }
1151 }
1152 }