aboutsummaryrefslogtreecommitdiffhomepage
path: root/demux/ebml.c
blob: d94aed5f64f00c554c5b409b800d24fa97b413c4 (plain)
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
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
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
/*
 * native ebml reader for the Matroska demuxer
 * new parser copyright (c) 2010 Uoti Urpala
 * copyright (c) 2004 Aurelien Jacobs <aurel@gnuage.org>
 * based on the one written by Ronald Bultje for gstreamer
 *
 * This file is part of MPlayer.
 *
 * MPlayer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * MPlayer 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 for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"

#include <stdlib.h>
#include <stdbool.h>
#include <inttypes.h>
#include <stddef.h>
#include <assert.h>

#include <libavutil/intfloat.h>
#include <libavutil/common.h>
#include "talloc.h"
#include "ebml.h"
#include "stream/stream.h"
#include "common/msg.h"

// Whether the id is a known Matroska level 1 element (allowed as element on
// global file level, after the level 0 MATROSKA_ID_SEGMENT).
// This (intentionally) doesn't include "global" elements.
bool ebml_is_mkv_level1_id(uint32_t id)
{
    switch (id) {
    case MATROSKA_ID_SEEKHEAD:
    case MATROSKA_ID_INFO:
    case MATROSKA_ID_CLUSTER:
    case MATROSKA_ID_TRACKS:
    case MATROSKA_ID_CUES:
    case MATROSKA_ID_ATTACHMENTS:
    case MATROSKA_ID_CHAPTERS:
    case MATROSKA_ID_TAGS:
        return true;
    default:
        return false;
    }
}

/*
 * Read: the element content data ID.
 * Return: the ID.
 */
uint32_t ebml_read_id(stream_t *s)
{
    int i, len_mask = 0x80;
    uint32_t id;

    for (i = 0, id = stream_read_char(s); i < 4 && !(id & len_mask); i++)
        len_mask >>= 1;
    if (i >= 4)
        return EBML_ID_INVALID;
    while (i--)
        id = (id << 8) | stream_read_char(s);
    return id;
}

/*
 * Read a variable length unsigned int.
 */
uint64_t ebml_read_vlen_uint(bstr *buffer)
{
    int i, j, num_ffs = 0, len_mask = 0x80;
    uint64_t num;

    if (buffer->len == 0)
        return EBML_UINT_INVALID;

    for (i = 0, num = buffer->start[0]; i < 8 && !(num & len_mask); i++)
        len_mask >>= 1;
    if (i >= 8)
        return EBML_UINT_INVALID;
    j = i + 1;
    if ((int) (num &= (len_mask - 1)) == len_mask - 1)
        num_ffs++;
    if (j > buffer->len)
        return EBML_UINT_INVALID;
    for (int n = 0; n < i; n++) {
        num = (num << 8) | buffer->start[n + 1];
        if ((num & 0xFF) == 0xFF)
            num_ffs++;
    }
    if (j == num_ffs)
        return EBML_UINT_INVALID;
    buffer->start += j;
    buffer->len -= j;
    return num;
}

/*
 * Read a variable length signed int.
 */
int64_t ebml_read_vlen_int(bstr *buffer)
{
    uint64_t unum;
    int l;

    /* read as unsigned number first */
    size_t len = buffer->len;
    unum = ebml_read_vlen_uint(buffer);
    if (unum == EBML_UINT_INVALID)
        return EBML_INT_INVALID;
    l = len - buffer->len;

    return unum - ((1 << ((7 * l) - 1)) - 1);
}

/*
 * Read: element content length.
 */
uint64_t ebml_read_length(stream_t *s)
{
    int i, j, num_ffs = 0, len_mask = 0x80;
    uint64_t len;

    for (i = 0, len = stream_read_char(s); i < 8 && !(len & len_mask); i++)
        len_mask >>= 1;
    if (i >= 8)
        return EBML_UINT_INVALID;
    j = i + 1;
    if ((int) (len &= (len_mask - 1)) == len_mask - 1)
        num_ffs++;
    while (i--) {
        len = (len << 8) | stream_read_char(s);
        if ((len & 0xFF) == 0xFF)
            num_ffs++;
    }
    if (j == num_ffs)
        return EBML_UINT_INVALID;
    if (len >= 1ULL<<63)   // Can happen if stream_read_char returns EOF
        return EBML_UINT_INVALID;
    return len;
}

/*
 * Read the next element as an unsigned int.
 */
uint64_t ebml_read_uint(stream_t *s)
{
    uint64_t len, value = 0;

    len = ebml_read_length(s);
    if (len == EBML_UINT_INVALID || len < 1 || len > 8)
        return EBML_UINT_INVALID;

    while (len--)
        value = (value << 8) | stream_read_char(s);

    return value;
}

/*
 * Read the next element as a signed int.
 */
int64_t ebml_read_int(stream_t *s)
{
    uint64_t value = 0;
    uint64_t len;
    int l;

    len = ebml_read_length(s);
    if (len == EBML_UINT_INVALID || len < 1 || len > 8)
        return EBML_INT_INVALID;

    len--;
    l = stream_read_char(s);
    if (l & 0x80)
        value = -1;
    value = (value << 8) | l;
    while (len--)
        value = (value << 8) | stream_read_char(s);

    return (int64_t)value; // assume complement of 2
}

/*
 * Skip the current element.
 * end: the end of the parent element or -1 (for robust error handling)
 */
int ebml_read_skip(struct mp_log *log, int64_t end, stream_t *s)
{
    uint64_t len;

    int64_t pos = stream_tell(s);

    len = ebml_read_length(s);
    if (len == EBML_UINT_INVALID)
        goto invalid;

    int64_t pos2 = stream_tell(s);
    if (len >= INT64_MAX - pos2 || (end > 0 && pos2 + len > end))
        goto invalid;

    if (!stream_skip(s, len))
        goto invalid;

    return 0;

invalid:
    mp_err(log, "Invalid EBML length at position %"PRId64"\n", pos);
    stream_seek(s, pos);
    return 1;
}

/*
 * Skip to (probable) next cluster (MATROSKA_ID_CLUSTER) element start position.
 */
int ebml_resync_cluster(struct mp_log *log, stream_t *s)
{
    int64_t pos = stream_tell(s);
    uint32_t last_4_bytes = 0;
    mp_err(log, "Corrupt file detected. "
           "Trying to resync starting from position %"PRId64"...\n", pos);
    while (!s->eof) {
        // Assumes MATROSKA_ID_CLUSTER is 4 bytes, with no 0 bytes.
        if (last_4_bytes == MATROSKA_ID_CLUSTER) {
            mp_err(log, "Cluster found at %"PRId64".\n", pos - 4);
            stream_seek(s, pos - 4);
            return 0;
        }
        last_4_bytes = (last_4_bytes << 8) | stream_read_char(s);
        pos++;
    }
    return -1;
}



#define EVALARGS(F, ...) F(__VA_ARGS__)
#define E(str, N, type) const struct ebml_elem_desc ebml_ ## N ## _desc = { str, type };
#define E_SN(str, count, N) const struct ebml_elem_desc ebml_ ## N ## _desc = { str, EBML_TYPE_SUBELEMENTS, sizeof(struct ebml_ ## N), count, (const struct ebml_field_desc[]){
#define E_S(str, count) EVALARGS(E_SN, str, count, N)
#define FN(id, name, multiple, N) { id, multiple, offsetof(struct ebml_ ## N, name), offsetof(struct ebml_ ## N, n_ ## name), &ebml_##name##_desc},
#define F(id, name, multiple) EVALARGS(FN, id, name, multiple, N)
#include "ebml_defs.c"
#undef EVALARGS
#undef SN
#undef S
#undef FN
#undef F

// Used to read/write pointers to different struct types
struct generic;
#define generic_struct struct generic

static uint32_t ebml_parse_id(uint8_t *data, int *length)
{
    int len = 1;
    uint32_t id = *data++;
    for (int len_mask = 0x80; !(id & len_mask); len_mask >>= 1) {
        len++;
        if (len > 4) {
            *length = -1;
            return EBML_ID_INVALID;
        }
    }
    *length = len;
    while (--len)
        id = (id << 8) | *data++;
    return id;
}

static uint64_t parse_vlen(uint8_t *data, int *length, bool is_length)
{
    uint64_t r = *data++;
    int len = 1;
    int len_mask;
    for (len_mask = 0x80; !(r & len_mask); len_mask >>= 1) {
        len++;
        if (len > 8) {
            *length = -1;
            return -1;
        }
    }
    r &= len_mask - 1;

    int num_allones = 0;
    if (r == len_mask - 1)
        num_allones++;
    for (int i = 1; i < len; i++) {
        if (*data == 255)
            num_allones++;
        r = (r << 8) | *data++;
    }
    if (is_length && num_allones == len) {
        // According to Matroska specs this means "unknown length"
        // Could be supported if there are any actual files using it
        *length = -1;
        return -1;
    }
    *length = len;
    return r;
}

static uint64_t ebml_parse_length(uint8_t *data, int *length)
{
    return parse_vlen(data, length, true);
}

static uint64_t ebml_parse_uint(uint8_t *data, int length)
{
    assert(length >= 1 && length <= 8);
    uint64_t r = 0;
    while (length--)
        r = (r << 8) + *data++;
    return r;
}

static int64_t ebml_parse_sint(uint8_t *data, int length)
{
    assert(length >=1 && length <= 8);
    uint64_t r = 0;
    if (*data & 0x80)
        r = -1;
    while (length--)
        r = (r << 8) | *data++;
    return (int64_t)r; // assume complement of 2
}

static double ebml_parse_float(uint8_t *data, int length)
{
    assert(length == 4 || length == 8);
    uint64_t i = ebml_parse_uint(data, length);
    if (length == 4)
        return av_int2float(i);
    else
        return av_int2double(i);
}


// target must be initialized to zero
static void ebml_parse_element(struct ebml_parse_ctx *ctx, void *target,
                               uint8_t *data, int size,
                               const struct ebml_elem_desc *type, int level)
{
    assert(type->type == EBML_TYPE_SUBELEMENTS);
    assert(level < 8);
    MP_DBG(ctx, "%.*sParsing element %s\n", level, "       ", type->name);

    char *s = target;
    uint8_t *end = data + size;
    uint8_t *p = data;
    int num_elems[MAX_EBML_SUBELEMENTS] = {0};
    while (p < end) {
        uint8_t *startp = p;
        int len;
        uint32_t id = ebml_parse_id(p, &len);
        if (len > end - p)
            goto past_end_error;
        if (len < 0) {
            MP_DBG(ctx, "Error parsing subelement id\n");
            goto other_error;
        }
        p += len;
        uint64_t length = ebml_parse_length(p, &len);
        if (len > end - p)
            goto past_end_error;
        if (len < 0) {
            MP_DBG(ctx, "Error parsing subelement length\n");
            goto other_error;
        }
        p += len;

        int field_idx = -1;
        for (int i = 0; i < type->field_count; i++)
            if (type->fields[i].id == id) {
                field_idx = i;
                num_elems[i]++;
                if (num_elems[i] >= 0x70000000) {
                    MP_ERR(ctx, "Too many EBML subelements.\n");
                    goto other_error;
                }
                break;
            }

        if (length > end - p) {
            if (field_idx >= 0 && type->fields[field_idx].desc->type
                != EBML_TYPE_SUBELEMENTS) {
                MP_DBG(ctx, "Subelement content goes "
                       "past end of containing element\n");
                goto other_error;
            }
            // Try to parse what is possible from inside this partial element
            ctx->has_errors = true;
            length = end - p;
        }
        p += length;

        continue;

    past_end_error:
        MP_DBG(ctx, "Subelement headers go past end of containing element\n");
    other_error:
        ctx->has_errors = true;
        end = startp;
        break;
    }

    for (int i = 0; i < type->field_count; i++)
        if (num_elems[i] && type->fields[i].multiple) {
            char *ptr = s + type->fields[i].offset;
            switch (type->fields[i].desc->type) {
            case EBML_TYPE_SUBELEMENTS: {
                size_t max = 1000000000 / type->fields[i].desc->size;
                if (num_elems[i] > max) {
                    MP_ERR(ctx, "Too many subelements.\n");
                    num_elems[i] = max;
                }
                int sz = num_elems[i] * type->fields[i].desc->size;
                *(generic_struct **) ptr = talloc_zero_size(ctx->talloc_ctx, sz);
                break;
            }
            case EBML_TYPE_UINT:
                *(uint64_t **) ptr = talloc_zero_array(ctx->talloc_ctx,
                                                       uint64_t, num_elems[i]);
                break;
            case EBML_TYPE_SINT:
                *(int64_t **) ptr = talloc_zero_array(ctx->talloc_ctx,
                                                      int64_t, num_elems[i]);
                break;
            case EBML_TYPE_FLOAT:
                *(double **) ptr = talloc_zero_array(ctx->talloc_ctx,
                                                     double, num_elems[i]);
                break;
            case EBML_TYPE_STR:
            case EBML_TYPE_BINARY:
                *(struct bstr **) ptr = talloc_zero_array(ctx->talloc_ctx,
                                                          struct bstr,
                                                          num_elems[i]);
                break;
            case EBML_TYPE_EBML_ID:
                *(int32_t **) ptr = talloc_zero_array(ctx->talloc_ctx,
                                                      uint32_t, num_elems[i]);
                break;
            default:
                abort();
            }
        }

    while (data < end) {
        int len;
        uint32_t id = ebml_parse_id(data, &len);
        assert(len >= 0 && len <= end - data);
        data += len;
        uint64_t length = ebml_parse_length(data, &len);
        assert(len >= 0 && len <= end - data);
        data += len;
        if (length > end - data) {
            // Try to parse what is possible from inside this partial element
            length = end - data;
            MP_DBG(ctx, "Next subelement content goes "
                   "past end of containing element, will be truncated\n");
        }
        int field_idx = -1;
        for (int i = 0; i < type->field_count; i++)
            if (type->fields[i].id == id) {
                field_idx = i;
                break;
            }
        if (field_idx < 0) {
            if (id == 0xec)
                MP_DBG(ctx, "%.*sIgnoring Void element "
                       "size: %"PRIu64"\n", level+1, "        ", length);
            else if (id == 0xbf)
                MP_DBG(ctx, "%.*sIgnoring CRC-32 "
                       "element size: %"PRIu64"\n", level+1, "        ",
                       length);
            else
                MP_DBG(ctx, "Ignoring unrecognized "
                       "subelement. ID: %x size: %"PRIu64"\n", id, length);
            data += length;
            continue;
        }
        const struct ebml_field_desc *fd = &type->fields[field_idx];
        const struct ebml_elem_desc *ed = fd->desc;
        bool multiple = fd->multiple;
        int *countptr = (int *) (s + fd->count_offset);
        if (*countptr >= num_elems[field_idx]) {
            // Shouldn't happen with on any sane file without bugs
            MP_ERR(ctx, "Too many subelems?\n");
            ctx->has_errors = true;
            data += length;
            continue;
        }
        if (*countptr > 0 && !multiple) {
            MP_DBG(ctx, "Another subelement of type "
                   "%x %s (size: %"PRIu64"). Only one allowed. Ignoring.\n",
                   id, ed->name, length);
            ctx->has_errors = true;
            data += length;
            continue;
        }
        MP_DBG(ctx, "%.*sParsing %x %s size: %"PRIu64
               " value: ", level+1, "        ", id, ed->name, length);

        char *fieldptr = s + fd->offset;
        switch (ed->type) {
        case EBML_TYPE_SUBELEMENTS:
            MP_DBG(ctx, "subelements\n");
            char *subelptr;
            if (multiple) {
                char *array_start = (char *) *(generic_struct **) fieldptr;
                subelptr = array_start + *countptr * ed->size;
            } else
                subelptr = fieldptr;
            ebml_parse_element(ctx, subelptr, data, length, ed, level + 1);
            break;

        case EBML_TYPE_UINT:;
            uint64_t *uintptr;
#define GETPTR(subelptr, fieldtype)                                     \
            if (multiple)                                               \
                subelptr = *(fieldtype **) fieldptr + *countptr;        \
            else                                                        \
                subelptr = (fieldtype *) fieldptr
            GETPTR(uintptr, uint64_t);
            if (length < 1 || length > 8) {
                MP_DBG(ctx, "uint invalid length %"PRIu64"\n", length);
                goto error;
            }
            *uintptr = ebml_parse_uint(data, length);
            MP_DBG(ctx, "uint %"PRIu64"\n", *uintptr);
            break;

        case EBML_TYPE_SINT:;
            int64_t *sintptr;
            GETPTR(sintptr, int64_t);
            if (length < 1 || length > 8) {
                MP_DBG(ctx, "sint invalid length %"PRIu64"\n", length);
                goto error;
            }
            *sintptr = ebml_parse_sint(data, length);
            MP_DBG(ctx, "sint %"PRId64"\n", *sintptr);
            break;

        case EBML_TYPE_FLOAT:;
            double *floatptr;
            GETPTR(floatptr, double);
            if (length != 4 && length != 8) {
                MP_DBG(ctx, "float invalid length %"PRIu64"\n", length);
                goto error;
            }
            *floatptr = ebml_parse_float(data, length);
            MP_DBG(ctx, "float %f\n", *floatptr);
            break;

        case EBML_TYPE_STR:
        case EBML_TYPE_BINARY:;
            if (length > 0x80000000) {
                MP_ERR(ctx, "Not reading overly long EBML element.\n");
                break;
            }
            struct bstr *strptr;
            GETPTR(strptr, struct bstr);
            strptr->start = data;
            strptr->len = length;
            if (ed->type == EBML_TYPE_STR)
                MP_DBG(ctx, "string \"%.*s\"\n", BSTR_P(*strptr));
            else
                MP_DBG(ctx, "binary %zd bytes\n", strptr->len);
            break;

        case EBML_TYPE_EBML_ID:;
            uint32_t *idptr;
            GETPTR(idptr, uint32_t);
            *idptr = ebml_parse_id(data, &len);
            if (len != length) {
                MP_DBG(ctx, "ebml_id broken value\n");
                goto error;
            }
            MP_DBG(ctx, "ebml_id %x\n", (unsigned)*idptr);
            break;
        default:
            abort();
        }
        *countptr += 1;
    error:
        data += length;
    }
}

// target must be initialized to zero
int ebml_read_element(struct stream *s, struct ebml_parse_ctx *ctx,
                      void *target, const struct ebml_elem_desc *desc)
{
    ctx->has_errors = false;
    int msglevel = ctx->no_error_messages ? MSGL_DEBUG : MSGL_WARN;
    uint64_t length = ebml_read_length(s);
    if (s->eof) {
        MP_MSG(ctx, msglevel, "Unexpected end of file "
                   "- partial or corrupt file?\n");
        return -1;
    }
    if (length > 1000000000) {
        MP_MSG(ctx, msglevel, "Refusing to read element over 100 MB in size\n");
        return -1;
    }
    ctx->talloc_ctx = talloc_size(NULL, length + 8);
    int read_len = stream_read(s, ctx->talloc_ctx, length);
    if (read_len < length)
        MP_MSG(ctx, msglevel, "Unexpected end of file - partial or corrupt file?\n");
    ebml_parse_element(ctx, target, ctx->talloc_ctx, read_len, desc, 0);
    if (ctx->has_errors)
        MP_MSG(ctx, msglevel, "Error parsing element %s\n", desc->name);
    return 0;
}