1 /*
2 * Copyright (c) 2014, 2016, 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 package jdk.incubator.http.internal.hpack;
26
27 import java.io.IOException;
28 import java.io.UncheckedIOException;
29 import java.nio.ByteBuffer;
30
31 import static java.lang.String.format;
32
33 /**
34 * Huffman coding table.
35 *
36 * <p> Instances of this class are safe for use by multiple threads.
37 *
38 * @since 9
39 */
40 public final class Huffman {
41
42 // TODO: check if reset is done in both reader and writer
43
44 static final class Reader {
45
46 private Node curr; // position in the trie
47 private int len; // length of the path from the root to 'curr'
48 private int p; // byte probe
49
50 {
51 reset();
52 }
53
54 public void read(ByteBuffer source, Appendable destination,
55 boolean isLast) {
56 read(source, destination, true, isLast);
57 }
58
59 // Takes 'isLast' rather than returns whether the reading is done or
60 // not, for more informative exceptions.
61 void read(ByteBuffer source, Appendable destination, boolean reportEOS,
62 boolean isLast) {
63
64 Node c = curr;
65 int l = len;
66 /*
67 Since ByteBuffer is itself stateful, its position is
68 remembered here NOT as a part of Reader's state,
69 but to set it back in the case of a failure
70 */
71 int pos = source.position();
72
73 while (source.hasRemaining()) {
74 int d = source.get();
75 for (; p != 0; p >>= 1) {
76 c = c.getChild(p & d);
77 l++;
78 if (c.isLeaf()) {
79 if (reportEOS && c.isEOSPath) {
80 throw new IllegalArgumentException("Encountered EOS");
81 }
82 try {
83 destination.append(c.getChar());
84 } catch (RuntimeException | Error e) {
85 source.position(pos);
86 throw e;
87 } catch (IOException e) {
88 source.position(pos);
89 throw new UncheckedIOException(e);
90 }
91 c = INSTANCE.root;
92 l = 0;
93 }
94 curr = c;
95 len = l;
96 }
97 resetProbe();
98 pos++;
99 }
100 if (!isLast) {
101 return; // it's too early to jump to any conclusions, let's wait
102 }
103 if (c.isLeaf()) {
104 return; // it's perfectly ok, no extra padding bits
105 }
106 if (c.isEOSPath && len <= 7) {
107 return; // it's ok, some extra padding bits
108 }
109 if (c.isEOSPath) {
110 throw new IllegalArgumentException(
111 "Padding is too long (len=" + len + ") " +
112 "or unexpected end of data");
113 }
114 throw new IllegalArgumentException(
115 "Not a EOS prefix padding or unexpected end of data");
116 }
117
118 public void reset() {
119 curr = INSTANCE.root;
120 len = 0;
121 resetProbe();
122 }
123
124 private void resetProbe() {
125 p = 0x80;
126 }
127 }
128
129 static final class Writer {
130
131 private int pos; // position in 'source'
132 private int avail = 8; // number of least significant bits available in 'curr'
133 private int curr; // next byte to put to the destination
134 private int rem; // number of least significant bits in 'code' yet to be processed
135 private int code; // current code being written
136
137 private CharSequence source;
138 private int end;
139
140 public Writer from(CharSequence input, int start, int end) {
141 if (start < 0 || end < 0 || end > input.length() || start > end) {
142 throw new IndexOutOfBoundsException(
143 String.format("input.length()=%s, start=%s, end=%s",
144 input.length(), start, end));
145 }
146 pos = start;
147 this.end = end;
148 this.source = input;
149 return this;
150 }
151
152 public boolean write(ByteBuffer destination) {
153 for (; pos < end; pos++) {
154 if (rem == 0) {
155 Code desc = INSTANCE.codeOf(source.charAt(pos));
156 rem = desc.length;
157 code = desc.code;
158 }
159 while (rem > 0) {
160 if (rem < avail) {
161 curr |= (code << (avail - rem));
162 avail -= rem;
163 rem = 0;
164 } else {
165 int c = (curr | (code >>> (rem - avail)));
166 if (destination.hasRemaining()) {
167 destination.put((byte) c);
168 } else {
169 return false;
170 }
171 curr = c;
172 code <<= (32 - rem + avail); // throw written bits off the cliff (is this Sparta?)
173 code >>>= (32 - rem + avail); // return to the position
174 rem -= avail;
175 curr = 0;
176 avail = 8;
177 }
178 }
179 }
180
181 if (avail < 8) { // have to pad
182 if (destination.hasRemaining()) {
183 destination.put((byte) (curr | (INSTANCE.EOS.code >>> (INSTANCE.EOS.length - avail))));
184 avail = 8;
185 } else {
186 return false;
187 }
188 }
189
190 return true;
191 }
192
193 public Writer reset() {
194 source = null;
195 end = -1;
196 pos = -1;
197 avail = 8;
198 curr = 0;
199 code = 0;
200 return this;
201 }
202 }
203
204 /**
205 * Shared instance.
206 */
207 public static final Huffman INSTANCE = new Huffman();
208
209 private final Code EOS = new Code(0x3fffffff, 30);
210 private final Code[] codes = new Code[257];
211 private final Node root = new Node() {
212 @Override
213 public String toString() { return "root"; }
214 };
215
216 // TODO: consider builder and immutable trie
217 private Huffman() {
218 // @formatter:off
219 addChar(0, 0x1ff8, 13);
220 addChar(1, 0x7fffd8, 23);
221 addChar(2, 0xfffffe2, 28);
222 addChar(3, 0xfffffe3, 28);
223 addChar(4, 0xfffffe4, 28);
224 addChar(5, 0xfffffe5, 28);
225 addChar(6, 0xfffffe6, 28);
226 addChar(7, 0xfffffe7, 28);
227 addChar(8, 0xfffffe8, 28);
228 addChar(9, 0xffffea, 24);
229 addChar(10, 0x3ffffffc, 30);
230 addChar(11, 0xfffffe9, 28);
231 addChar(12, 0xfffffea, 28);
232 addChar(13, 0x3ffffffd, 30);
233 addChar(14, 0xfffffeb, 28);
234 addChar(15, 0xfffffec, 28);
235 addChar(16, 0xfffffed, 28);
236 addChar(17, 0xfffffee, 28);
237 addChar(18, 0xfffffef, 28);
238 addChar(19, 0xffffff0, 28);
239 addChar(20, 0xffffff1, 28);
240 addChar(21, 0xffffff2, 28);
241 addChar(22, 0x3ffffffe, 30);
242 addChar(23, 0xffffff3, 28);
243 addChar(24, 0xffffff4, 28);
244 addChar(25, 0xffffff5, 28);
245 addChar(26, 0xffffff6, 28);
246 addChar(27, 0xffffff7, 28);
247 addChar(28, 0xffffff8, 28);
248 addChar(29, 0xffffff9, 28);
249 addChar(30, 0xffffffa, 28);
250 addChar(31, 0xffffffb, 28);
251 addChar(32, 0x14, 6);
252 addChar(33, 0x3f8, 10);
253 addChar(34, 0x3f9, 10);
254 addChar(35, 0xffa, 12);
255 addChar(36, 0x1ff9, 13);
256 addChar(37, 0x15, 6);
257 addChar(38, 0xf8, 8);
258 addChar(39, 0x7fa, 11);
259 addChar(40, 0x3fa, 10);
260 addChar(41, 0x3fb, 10);
261 addChar(42, 0xf9, 8);
262 addChar(43, 0x7fb, 11);
263 addChar(44, 0xfa, 8);
264 addChar(45, 0x16, 6);
265 addChar(46, 0x17, 6);
266 addChar(47, 0x18, 6);
267 addChar(48, 0x0, 5);
268 addChar(49, 0x1, 5);
269 addChar(50, 0x2, 5);
270 addChar(51, 0x19, 6);
271 addChar(52, 0x1a, 6);
272 addChar(53, 0x1b, 6);
273 addChar(54, 0x1c, 6);
274 addChar(55, 0x1d, 6);
275 addChar(56, 0x1e, 6);
276 addChar(57, 0x1f, 6);
277 addChar(58, 0x5c, 7);
278 addChar(59, 0xfb, 8);
279 addChar(60, 0x7ffc, 15);
280 addChar(61, 0x20, 6);
281 addChar(62, 0xffb, 12);
282 addChar(63, 0x3fc, 10);
283 addChar(64, 0x1ffa, 13);
284 addChar(65, 0x21, 6);
285 addChar(66, 0x5d, 7);
286 addChar(67, 0x5e, 7);
287 addChar(68, 0x5f, 7);
288 addChar(69, 0x60, 7);
289 addChar(70, 0x61, 7);
290 addChar(71, 0x62, 7);
291 addChar(72, 0x63, 7);
292 addChar(73, 0x64, 7);
293 addChar(74, 0x65, 7);
294 addChar(75, 0x66, 7);
295 addChar(76, 0x67, 7);
296 addChar(77, 0x68, 7);
297 addChar(78, 0x69, 7);
298 addChar(79, 0x6a, 7);
299 addChar(80, 0x6b, 7);
300 addChar(81, 0x6c, 7);
301 addChar(82, 0x6d, 7);
302 addChar(83, 0x6e, 7);
303 addChar(84, 0x6f, 7);
304 addChar(85, 0x70, 7);
305 addChar(86, 0x71, 7);
306 addChar(87, 0x72, 7);
307 addChar(88, 0xfc, 8);
308 addChar(89, 0x73, 7);
309 addChar(90, 0xfd, 8);
310 addChar(91, 0x1ffb, 13);
311 addChar(92, 0x7fff0, 19);
312 addChar(93, 0x1ffc, 13);
313 addChar(94, 0x3ffc, 14);
314 addChar(95, 0x22, 6);
315 addChar(96, 0x7ffd, 15);
316 addChar(97, 0x3, 5);
317 addChar(98, 0x23, 6);
318 addChar(99, 0x4, 5);
319 addChar(100, 0x24, 6);
320 addChar(101, 0x5, 5);
321 addChar(102, 0x25, 6);
322 addChar(103, 0x26, 6);
323 addChar(104, 0x27, 6);
324 addChar(105, 0x6, 5);
325 addChar(106, 0x74, 7);
326 addChar(107, 0x75, 7);
327 addChar(108, 0x28, 6);
328 addChar(109, 0x29, 6);
329 addChar(110, 0x2a, 6);
330 addChar(111, 0x7, 5);
331 addChar(112, 0x2b, 6);
332 addChar(113, 0x76, 7);
333 addChar(114, 0x2c, 6);
334 addChar(115, 0x8, 5);
335 addChar(116, 0x9, 5);
336 addChar(117, 0x2d, 6);
337 addChar(118, 0x77, 7);
338 addChar(119, 0x78, 7);
339 addChar(120, 0x79, 7);
340 addChar(121, 0x7a, 7);
341 addChar(122, 0x7b, 7);
342 addChar(123, 0x7ffe, 15);
343 addChar(124, 0x7fc, 11);
344 addChar(125, 0x3ffd, 14);
345 addChar(126, 0x1ffd, 13);
346 addChar(127, 0xffffffc, 28);
347 addChar(128, 0xfffe6, 20);
348 addChar(129, 0x3fffd2, 22);
349 addChar(130, 0xfffe7, 20);
350 addChar(131, 0xfffe8, 20);
351 addChar(132, 0x3fffd3, 22);
352 addChar(133, 0x3fffd4, 22);
353 addChar(134, 0x3fffd5, 22);
354 addChar(135, 0x7fffd9, 23);
355 addChar(136, 0x3fffd6, 22);
356 addChar(137, 0x7fffda, 23);
357 addChar(138, 0x7fffdb, 23);
358 addChar(139, 0x7fffdc, 23);
359 addChar(140, 0x7fffdd, 23);
360 addChar(141, 0x7fffde, 23);
361 addChar(142, 0xffffeb, 24);
362 addChar(143, 0x7fffdf, 23);
363 addChar(144, 0xffffec, 24);
364 addChar(145, 0xffffed, 24);
365 addChar(146, 0x3fffd7, 22);
366 addChar(147, 0x7fffe0, 23);
367 addChar(148, 0xffffee, 24);
368 addChar(149, 0x7fffe1, 23);
369 addChar(150, 0x7fffe2, 23);
370 addChar(151, 0x7fffe3, 23);
371 addChar(152, 0x7fffe4, 23);
372 addChar(153, 0x1fffdc, 21);
373 addChar(154, 0x3fffd8, 22);
374 addChar(155, 0x7fffe5, 23);
375 addChar(156, 0x3fffd9, 22);
376 addChar(157, 0x7fffe6, 23);
377 addChar(158, 0x7fffe7, 23);
378 addChar(159, 0xffffef, 24);
379 addChar(160, 0x3fffda, 22);
380 addChar(161, 0x1fffdd, 21);
381 addChar(162, 0xfffe9, 20);
382 addChar(163, 0x3fffdb, 22);
383 addChar(164, 0x3fffdc, 22);
384 addChar(165, 0x7fffe8, 23);
385 addChar(166, 0x7fffe9, 23);
386 addChar(167, 0x1fffde, 21);
387 addChar(168, 0x7fffea, 23);
388 addChar(169, 0x3fffdd, 22);
389 addChar(170, 0x3fffde, 22);
390 addChar(171, 0xfffff0, 24);
391 addChar(172, 0x1fffdf, 21);
392 addChar(173, 0x3fffdf, 22);
393 addChar(174, 0x7fffeb, 23);
394 addChar(175, 0x7fffec, 23);
395 addChar(176, 0x1fffe0, 21);
396 addChar(177, 0x1fffe1, 21);
397 addChar(178, 0x3fffe0, 22);
398 addChar(179, 0x1fffe2, 21);
399 addChar(180, 0x7fffed, 23);
400 addChar(181, 0x3fffe1, 22);
401 addChar(182, 0x7fffee, 23);
402 addChar(183, 0x7fffef, 23);
403 addChar(184, 0xfffea, 20);
404 addChar(185, 0x3fffe2, 22);
405 addChar(186, 0x3fffe3, 22);
406 addChar(187, 0x3fffe4, 22);
407 addChar(188, 0x7ffff0, 23);
408 addChar(189, 0x3fffe5, 22);
409 addChar(190, 0x3fffe6, 22);
410 addChar(191, 0x7ffff1, 23);
411 addChar(192, 0x3ffffe0, 26);
412 addChar(193, 0x3ffffe1, 26);
413 addChar(194, 0xfffeb, 20);
414 addChar(195, 0x7fff1, 19);
415 addChar(196, 0x3fffe7, 22);
416 addChar(197, 0x7ffff2, 23);
417 addChar(198, 0x3fffe8, 22);
418 addChar(199, 0x1ffffec, 25);
419 addChar(200, 0x3ffffe2, 26);
420 addChar(201, 0x3ffffe3, 26);
421 addChar(202, 0x3ffffe4, 26);
422 addChar(203, 0x7ffffde, 27);
423 addChar(204, 0x7ffffdf, 27);
424 addChar(205, 0x3ffffe5, 26);
425 addChar(206, 0xfffff1, 24);
426 addChar(207, 0x1ffffed, 25);
427 addChar(208, 0x7fff2, 19);
428 addChar(209, 0x1fffe3, 21);
429 addChar(210, 0x3ffffe6, 26);
430 addChar(211, 0x7ffffe0, 27);
431 addChar(212, 0x7ffffe1, 27);
432 addChar(213, 0x3ffffe7, 26);
433 addChar(214, 0x7ffffe2, 27);
434 addChar(215, 0xfffff2, 24);
435 addChar(216, 0x1fffe4, 21);
436 addChar(217, 0x1fffe5, 21);
437 addChar(218, 0x3ffffe8, 26);
438 addChar(219, 0x3ffffe9, 26);
439 addChar(220, 0xffffffd, 28);
440 addChar(221, 0x7ffffe3, 27);
441 addChar(222, 0x7ffffe4, 27);
442 addChar(223, 0x7ffffe5, 27);
443 addChar(224, 0xfffec, 20);
444 addChar(225, 0xfffff3, 24);
445 addChar(226, 0xfffed, 20);
446 addChar(227, 0x1fffe6, 21);
447 addChar(228, 0x3fffe9, 22);
448 addChar(229, 0x1fffe7, 21);
449 addChar(230, 0x1fffe8, 21);
450 addChar(231, 0x7ffff3, 23);
451 addChar(232, 0x3fffea, 22);
452 addChar(233, 0x3fffeb, 22);
453 addChar(234, 0x1ffffee, 25);
454 addChar(235, 0x1ffffef, 25);
455 addChar(236, 0xfffff4, 24);
456 addChar(237, 0xfffff5, 24);
457 addChar(238, 0x3ffffea, 26);
458 addChar(239, 0x7ffff4, 23);
459 addChar(240, 0x3ffffeb, 26);
460 addChar(241, 0x7ffffe6, 27);
461 addChar(242, 0x3ffffec, 26);
462 addChar(243, 0x3ffffed, 26);
463 addChar(244, 0x7ffffe7, 27);
464 addChar(245, 0x7ffffe8, 27);
465 addChar(246, 0x7ffffe9, 27);
466 addChar(247, 0x7ffffea, 27);
467 addChar(248, 0x7ffffeb, 27);
468 addChar(249, 0xffffffe, 28);
469 addChar(250, 0x7ffffec, 27);
470 addChar(251, 0x7ffffed, 27);
471 addChar(252, 0x7ffffee, 27);
472 addChar(253, 0x7ffffef, 27);
473 addChar(254, 0x7fffff0, 27);
474 addChar(255, 0x3ffffee, 26);
475 addEOS (256, EOS.code, EOS.length);
476 // @formatter:on
477 }
478
479
480 /**
481 * Calculates the number of bytes required to represent the given {@code
482 * CharSequence} with the Huffman coding.
483 *
484 * @param value
485 * characters
486 *
487 * @return number of bytes
488 *
489 * @throws NullPointerException
490 * if the value is null
491 */
492 public int lengthOf(CharSequence value) {
493 return lengthOf(value, 0, value.length());
494 }
495
496 /**
497 * Calculates the number of bytes required to represent a subsequence of the
498 * given {@code CharSequence} with the Huffman coding.
499 *
500 * @param value
501 * characters
502 * @param start
503 * the start index, inclusive
504 * @param end
505 * the end index, exclusive
506 *
507 * @return number of bytes
508 *
509 * @throws NullPointerException
510 * if the value is null
511 * @throws IndexOutOfBoundsException
512 * if any invocation of {@code value.charAt(i)}, where {@code start
513 * <= i < end} would throw an IndexOutOfBoundsException
514 */
515 public int lengthOf(CharSequence value, int start, int end) {
516 int len = 0;
517 for (int i = start; i < end; i++) {
518 char c = value.charAt(i);
519 len += INSTANCE.codeOf(c).length;
520 }
521 // Integer division with ceiling, assumption:
522 assert (len / 8 + (len % 8 != 0 ? 1 : 0)) == (len + 7) / 8 : len;
523 return (len + 7) / 8;
524 }
525
526 private void addChar(int c, int code, int bitLength) {
527 addLeaf(c, code, bitLength, false);
528 codes[c] = new Code(code, bitLength);
529 }
530
531 private void addEOS(int c, int code, int bitLength) {
532 addLeaf(c, code, bitLength, true);
533 codes[c] = new Code(code, bitLength);
534 }
535
536 private void addLeaf(int c, int code, int bitLength, boolean isEOS) {
537 if (bitLength < 1) {
538 throw new IllegalArgumentException("bitLength < 1");
539 }
540 Node curr = root;
541 for (int p = 1 << bitLength - 1; p != 0 && !curr.isLeaf(); p = p >> 1) {
542 curr.isEOSPath |= isEOS; // If it's already true, it can't become false
543 curr = curr.addChildIfAbsent(p & code);
544 }
545 curr.isEOSPath |= isEOS; // The last one needs to have this property as well
546 if (curr.isLeaf()) {
547 throw new IllegalStateException("Specified code is already taken");
548 }
549 curr.setChar((char) c);
550 }
551
552 private Code codeOf(char c) {
553 if (c > 255) {
554 throw new IllegalArgumentException("char=" + ((int) c));
555 }
556 return codes[c];
557 }
558
559 //
560 // For debugging/testing purposes
561 //
562 Node getRoot() {
563 return root;
564 }
565
566 //
567 // Guarantees:
568 //
569 // if (isLeaf() == true) => getChar() is a legal call
570 // if (isLeaf() == false) => getChild(i) is a legal call (though it can
571 // return null)
572 //
573 static class Node {
574
575 Node left;
576 Node right;
577 boolean isEOSPath;
578
579 boolean charIsSet;
580 char c;
581
582 Node getChild(int selector) {
583 if (isLeaf()) {
584 throw new IllegalStateException("This is a leaf node");
585 }
586 Node result = selector == 0 ? left : right;
587 if (result == null) {
588 throw new IllegalStateException(format(
589 "Node doesn't have a child (selector=%s)", selector));
590 }
591 return result;
592 }
593
594 boolean isLeaf() {
595 return charIsSet;
596 }
597
598 char getChar() {
599 if (!isLeaf()) {
600 throw new IllegalStateException("This node is not a leaf node");
601 }
602 return c;
603 }
604
605 void setChar(char c) {
606 if (charIsSet) {
607 throw new IllegalStateException(
608 "This node has been taken already");
609 }
610 if (left != null || right != null) {
611 throw new IllegalStateException("The node cannot be made "
612 + "a leaf as it's already has a child");
613 }
614 this.c = c;
615 charIsSet = true;
616 }
617
618 Node addChildIfAbsent(int i) {
619 if (charIsSet) {
620 throw new IllegalStateException("The node cannot have a child "
621 + "as it's already a leaf node");
622 }
623 Node child;
624 if (i == 0) {
625 if ((child = left) == null) {
626 child = left = new Node();
627 }
628 } else {
629 if ((child = right) == null) {
630 child = right = new Node();
631 }
632 }
633 return child;
634 }
635
636 @Override
637 public String toString() {
638 if (isLeaf()) {
639 if (isEOSPath) {
640 return "EOS";
641 } else {
642 return format("char: (%3s) '%s'", (int) c, c);
643 }
644 }
645 return "/\\";
646 }
647 }
648
649 // TODO: value-based class?
650 // FIXME: can we re-use Node instead of this class?
651 private static final class Code {
652
653 final int code;
654 final int length;
655
656 private Code(int code, int length) {
657 this.code = code;
658 this.length = length;
659 }
660
661 public int getCode() {
662 return code;
663 }
664
665 public int getLength() {
666 return length;
667 }
668
669 @Override
670 public String toString() {
671 long p = 1 << length;
672 return Long.toBinaryString(code + p).substring(1)
673 + ", length=" + length;
674 }
675 }
676 }