Root/
1 | /**************************************************************************** |
2 | * ip_conntrack_helper_h323_asn1.c - BER and PER decoding library for H.323 |
3 | * conntrack/NAT module. |
4 | * |
5 | * Copyright (c) 2006 by Jing Min Zhao <zhaojingmin@users.sourceforge.net> |
6 | * |
7 | * This source code is licensed under General Public License version 2. |
8 | * |
9 | * See ip_conntrack_helper_h323_asn1.h for details. |
10 | * |
11 | ****************************************************************************/ |
12 | |
13 | #ifdef __KERNEL__ |
14 | #include <linux/kernel.h> |
15 | #else |
16 | #include <stdio.h> |
17 | #endif |
18 | #include <linux/netfilter/nf_conntrack_h323_asn1.h> |
19 | |
20 | /* Trace Flag */ |
21 | #ifndef H323_TRACE |
22 | #define H323_TRACE 0 |
23 | #endif |
24 | |
25 | #if H323_TRACE |
26 | #define TAB_SIZE 4 |
27 | #define IFTHEN(cond, act) if(cond){act;} |
28 | #ifdef __KERNEL__ |
29 | #define PRINT printk |
30 | #else |
31 | #define PRINT printf |
32 | #endif |
33 | #define FNAME(name) name, |
34 | #else |
35 | #define IFTHEN(cond, act) |
36 | #define PRINT(fmt, args...) |
37 | #define FNAME(name) |
38 | #endif |
39 | |
40 | /* ASN.1 Types */ |
41 | #define NUL 0 |
42 | #define BOOL 1 |
43 | #define OID 2 |
44 | #define INT 3 |
45 | #define ENUM 4 |
46 | #define BITSTR 5 |
47 | #define NUMSTR 6 |
48 | #define NUMDGT 6 |
49 | #define TBCDSTR 6 |
50 | #define OCTSTR 7 |
51 | #define PRTSTR 7 |
52 | #define IA5STR 7 |
53 | #define GENSTR 7 |
54 | #define BMPSTR 8 |
55 | #define SEQ 9 |
56 | #define SET 9 |
57 | #define SEQOF 10 |
58 | #define SETOF 10 |
59 | #define CHOICE 11 |
60 | |
61 | /* Constraint Types */ |
62 | #define FIXD 0 |
63 | /* #define BITS 1-8 */ |
64 | #define BYTE 9 |
65 | #define WORD 10 |
66 | #define CONS 11 |
67 | #define SEMI 12 |
68 | #define UNCO 13 |
69 | |
70 | /* ASN.1 Type Attributes */ |
71 | #define SKIP 0 |
72 | #define STOP 1 |
73 | #define DECODE 2 |
74 | #define EXT 4 |
75 | #define OPEN 8 |
76 | #define OPT 16 |
77 | |
78 | |
79 | /* ASN.1 Field Structure */ |
80 | typedef struct field_t { |
81 | #if H323_TRACE |
82 | char *name; |
83 | #endif |
84 | unsigned char type; |
85 | unsigned char sz; |
86 | unsigned char lb; |
87 | unsigned char ub; |
88 | unsigned short attr; |
89 | unsigned short offset; |
90 | const struct field_t *fields; |
91 | } field_t; |
92 | |
93 | /* Bit Stream */ |
94 | typedef struct { |
95 | unsigned char *buf; |
96 | unsigned char *beg; |
97 | unsigned char *end; |
98 | unsigned char *cur; |
99 | unsigned int bit; |
100 | } bitstr_t; |
101 | |
102 | /* Tool Functions */ |
103 | #define INC_BIT(bs) if((++(bs)->bit)>7){(bs)->cur++;(bs)->bit=0;} |
104 | #define INC_BITS(bs,b) if(((bs)->bit+=(b))>7){(bs)->cur+=(bs)->bit>>3;(bs)->bit&=7;} |
105 | #define BYTE_ALIGN(bs) if((bs)->bit){(bs)->cur++;(bs)->bit=0;} |
106 | #define CHECK_BOUND(bs,n) if((bs)->cur+(n)>(bs)->end)return(H323_ERROR_BOUND) |
107 | static unsigned int get_len(bitstr_t *bs); |
108 | static unsigned int get_bit(bitstr_t *bs); |
109 | static unsigned int get_bits(bitstr_t *bs, unsigned int b); |
110 | static unsigned int get_bitmap(bitstr_t *bs, unsigned int b); |
111 | static unsigned int get_uint(bitstr_t *bs, int b); |
112 | |
113 | /* Decoder Functions */ |
114 | static int decode_nul(bitstr_t *bs, const struct field_t *f, char *base, int level); |
115 | static int decode_bool(bitstr_t *bs, const struct field_t *f, char *base, int level); |
116 | static int decode_oid(bitstr_t *bs, const struct field_t *f, char *base, int level); |
117 | static int decode_int(bitstr_t *bs, const struct field_t *f, char *base, int level); |
118 | static int decode_enum(bitstr_t *bs, const struct field_t *f, char *base, int level); |
119 | static int decode_bitstr(bitstr_t *bs, const struct field_t *f, char *base, int level); |
120 | static int decode_numstr(bitstr_t *bs, const struct field_t *f, char *base, int level); |
121 | static int decode_octstr(bitstr_t *bs, const struct field_t *f, char *base, int level); |
122 | static int decode_bmpstr(bitstr_t *bs, const struct field_t *f, char *base, int level); |
123 | static int decode_seq(bitstr_t *bs, const struct field_t *f, char *base, int level); |
124 | static int decode_seqof(bitstr_t *bs, const struct field_t *f, char *base, int level); |
125 | static int decode_choice(bitstr_t *bs, const struct field_t *f, char *base, int level); |
126 | |
127 | /* Decoder Functions Vector */ |
128 | typedef int (*decoder_t)(bitstr_t *, const struct field_t *, char *, int); |
129 | static const decoder_t Decoders[] = { |
130 | decode_nul, |
131 | decode_bool, |
132 | decode_oid, |
133 | decode_int, |
134 | decode_enum, |
135 | decode_bitstr, |
136 | decode_numstr, |
137 | decode_octstr, |
138 | decode_bmpstr, |
139 | decode_seq, |
140 | decode_seqof, |
141 | decode_choice, |
142 | }; |
143 | |
144 | /**************************************************************************** |
145 | * H.323 Types |
146 | ****************************************************************************/ |
147 | #include "nf_conntrack_h323_types.c" |
148 | |
149 | /**************************************************************************** |
150 | * Functions |
151 | ****************************************************************************/ |
152 | /* Assume bs is aligned && v < 16384 */ |
153 | static unsigned int get_len(bitstr_t *bs) |
154 | { |
155 | unsigned int v; |
156 | |
157 | v = *bs->cur++; |
158 | |
159 | if (v & 0x80) { |
160 | v &= 0x3f; |
161 | v <<= 8; |
162 | v += *bs->cur++; |
163 | } |
164 | |
165 | return v; |
166 | } |
167 | |
168 | /****************************************************************************/ |
169 | static unsigned int get_bit(bitstr_t *bs) |
170 | { |
171 | unsigned int b = (*bs->cur) & (0x80 >> bs->bit); |
172 | |
173 | INC_BIT(bs); |
174 | |
175 | return b; |
176 | } |
177 | |
178 | /****************************************************************************/ |
179 | /* Assume b <= 8 */ |
180 | static unsigned int get_bits(bitstr_t *bs, unsigned int b) |
181 | { |
182 | unsigned int v, l; |
183 | |
184 | v = (*bs->cur) & (0xffU >> bs->bit); |
185 | l = b + bs->bit; |
186 | |
187 | if (l < 8) { |
188 | v >>= 8 - l; |
189 | bs->bit = l; |
190 | } else if (l == 8) { |
191 | bs->cur++; |
192 | bs->bit = 0; |
193 | } else { /* l > 8 */ |
194 | |
195 | v <<= 8; |
196 | v += *(++bs->cur); |
197 | v >>= 16 - l; |
198 | bs->bit = l - 8; |
199 | } |
200 | |
201 | return v; |
202 | } |
203 | |
204 | /****************************************************************************/ |
205 | /* Assume b <= 32 */ |
206 | static unsigned int get_bitmap(bitstr_t *bs, unsigned int b) |
207 | { |
208 | unsigned int v, l, shift, bytes; |
209 | |
210 | if (!b) |
211 | return 0; |
212 | |
213 | l = bs->bit + b; |
214 | |
215 | if (l < 8) { |
216 | v = (unsigned int)(*bs->cur) << (bs->bit + 24); |
217 | bs->bit = l; |
218 | } else if (l == 8) { |
219 | v = (unsigned int)(*bs->cur++) << (bs->bit + 24); |
220 | bs->bit = 0; |
221 | } else { |
222 | for (bytes = l >> 3, shift = 24, v = 0; bytes; |
223 | bytes--, shift -= 8) |
224 | v |= (unsigned int)(*bs->cur++) << shift; |
225 | |
226 | if (l < 32) { |
227 | v |= (unsigned int)(*bs->cur) << shift; |
228 | v <<= bs->bit; |
229 | } else if (l > 32) { |
230 | v <<= bs->bit; |
231 | v |= (*bs->cur) >> (8 - bs->bit); |
232 | } |
233 | |
234 | bs->bit = l & 0x7; |
235 | } |
236 | |
237 | v &= 0xffffffff << (32 - b); |
238 | |
239 | return v; |
240 | } |
241 | |
242 | /**************************************************************************** |
243 | * Assume bs is aligned and sizeof(unsigned int) == 4 |
244 | ****************************************************************************/ |
245 | static unsigned int get_uint(bitstr_t *bs, int b) |
246 | { |
247 | unsigned int v = 0; |
248 | |
249 | switch (b) { |
250 | case 4: |
251 | v |= *bs->cur++; |
252 | v <<= 8; |
253 | case 3: |
254 | v |= *bs->cur++; |
255 | v <<= 8; |
256 | case 2: |
257 | v |= *bs->cur++; |
258 | v <<= 8; |
259 | case 1: |
260 | v |= *bs->cur++; |
261 | break; |
262 | } |
263 | return v; |
264 | } |
265 | |
266 | /****************************************************************************/ |
267 | static int decode_nul(bitstr_t *bs, const struct field_t *f, |
268 | char *base, int level) |
269 | { |
270 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
271 | |
272 | return H323_ERROR_NONE; |
273 | } |
274 | |
275 | /****************************************************************************/ |
276 | static int decode_bool(bitstr_t *bs, const struct field_t *f, |
277 | char *base, int level) |
278 | { |
279 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
280 | |
281 | INC_BIT(bs); |
282 | |
283 | CHECK_BOUND(bs, 0); |
284 | return H323_ERROR_NONE; |
285 | } |
286 | |
287 | /****************************************************************************/ |
288 | static int decode_oid(bitstr_t *bs, const struct field_t *f, |
289 | char *base, int level) |
290 | { |
291 | int len; |
292 | |
293 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
294 | |
295 | BYTE_ALIGN(bs); |
296 | CHECK_BOUND(bs, 1); |
297 | len = *bs->cur++; |
298 | bs->cur += len; |
299 | |
300 | CHECK_BOUND(bs, 0); |
301 | return H323_ERROR_NONE; |
302 | } |
303 | |
304 | /****************************************************************************/ |
305 | static int decode_int(bitstr_t *bs, const struct field_t *f, |
306 | char *base, int level) |
307 | { |
308 | unsigned int len; |
309 | |
310 | PRINT("%*.s%s", level * TAB_SIZE, " ", f->name); |
311 | |
312 | switch (f->sz) { |
313 | case BYTE: /* Range == 256 */ |
314 | BYTE_ALIGN(bs); |
315 | bs->cur++; |
316 | break; |
317 | case WORD: /* 257 <= Range <= 64K */ |
318 | BYTE_ALIGN(bs); |
319 | bs->cur += 2; |
320 | break; |
321 | case CONS: /* 64K < Range < 4G */ |
322 | len = get_bits(bs, 2) + 1; |
323 | BYTE_ALIGN(bs); |
324 | if (base && (f->attr & DECODE)) { /* timeToLive */ |
325 | unsigned int v = get_uint(bs, len) + f->lb; |
326 | PRINT(" = %u", v); |
327 | *((unsigned int *)(base + f->offset)) = v; |
328 | } |
329 | bs->cur += len; |
330 | break; |
331 | case UNCO: |
332 | BYTE_ALIGN(bs); |
333 | CHECK_BOUND(bs, 2); |
334 | len = get_len(bs); |
335 | bs->cur += len; |
336 | break; |
337 | default: /* 2 <= Range <= 255 */ |
338 | INC_BITS(bs, f->sz); |
339 | break; |
340 | } |
341 | |
342 | PRINT("\n"); |
343 | |
344 | CHECK_BOUND(bs, 0); |
345 | return H323_ERROR_NONE; |
346 | } |
347 | |
348 | /****************************************************************************/ |
349 | static int decode_enum(bitstr_t *bs, const struct field_t *f, |
350 | char *base, int level) |
351 | { |
352 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
353 | |
354 | if ((f->attr & EXT) && get_bit(bs)) { |
355 | INC_BITS(bs, 7); |
356 | } else { |
357 | INC_BITS(bs, f->sz); |
358 | } |
359 | |
360 | CHECK_BOUND(bs, 0); |
361 | return H323_ERROR_NONE; |
362 | } |
363 | |
364 | /****************************************************************************/ |
365 | static int decode_bitstr(bitstr_t *bs, const struct field_t *f, |
366 | char *base, int level) |
367 | { |
368 | unsigned int len; |
369 | |
370 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
371 | |
372 | BYTE_ALIGN(bs); |
373 | switch (f->sz) { |
374 | case FIXD: /* fixed length > 16 */ |
375 | len = f->lb; |
376 | break; |
377 | case WORD: /* 2-byte length */ |
378 | CHECK_BOUND(bs, 2); |
379 | len = (*bs->cur++) << 8; |
380 | len += (*bs->cur++) + f->lb; |
381 | break; |
382 | case SEMI: |
383 | CHECK_BOUND(bs, 2); |
384 | len = get_len(bs); |
385 | break; |
386 | default: |
387 | len = 0; |
388 | break; |
389 | } |
390 | |
391 | bs->cur += len >> 3; |
392 | bs->bit = len & 7; |
393 | |
394 | CHECK_BOUND(bs, 0); |
395 | return H323_ERROR_NONE; |
396 | } |
397 | |
398 | /****************************************************************************/ |
399 | static int decode_numstr(bitstr_t *bs, const struct field_t *f, |
400 | char *base, int level) |
401 | { |
402 | unsigned int len; |
403 | |
404 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
405 | |
406 | /* 2 <= Range <= 255 */ |
407 | len = get_bits(bs, f->sz) + f->lb; |
408 | |
409 | BYTE_ALIGN(bs); |
410 | INC_BITS(bs, (len << 2)); |
411 | |
412 | CHECK_BOUND(bs, 0); |
413 | return H323_ERROR_NONE; |
414 | } |
415 | |
416 | /****************************************************************************/ |
417 | static int decode_octstr(bitstr_t *bs, const struct field_t *f, |
418 | char *base, int level) |
419 | { |
420 | unsigned int len; |
421 | |
422 | PRINT("%*.s%s", level * TAB_SIZE, " ", f->name); |
423 | |
424 | switch (f->sz) { |
425 | case FIXD: /* Range == 1 */ |
426 | if (f->lb > 2) { |
427 | BYTE_ALIGN(bs); |
428 | if (base && (f->attr & DECODE)) { |
429 | /* The IP Address */ |
430 | IFTHEN(f->lb == 4, |
431 | PRINT(" = %d.%d.%d.%d:%d", |
432 | bs->cur[0], bs->cur[1], |
433 | bs->cur[2], bs->cur[3], |
434 | bs->cur[4] * 256 + bs->cur[5])); |
435 | *((unsigned int *)(base + f->offset)) = |
436 | bs->cur - bs->buf; |
437 | } |
438 | } |
439 | len = f->lb; |
440 | break; |
441 | case BYTE: /* Range == 256 */ |
442 | BYTE_ALIGN(bs); |
443 | CHECK_BOUND(bs, 1); |
444 | len = (*bs->cur++) + f->lb; |
445 | break; |
446 | case SEMI: |
447 | BYTE_ALIGN(bs); |
448 | CHECK_BOUND(bs, 2); |
449 | len = get_len(bs) + f->lb; |
450 | break; |
451 | default: /* 2 <= Range <= 255 */ |
452 | len = get_bits(bs, f->sz) + f->lb; |
453 | BYTE_ALIGN(bs); |
454 | break; |
455 | } |
456 | |
457 | bs->cur += len; |
458 | |
459 | PRINT("\n"); |
460 | |
461 | CHECK_BOUND(bs, 0); |
462 | return H323_ERROR_NONE; |
463 | } |
464 | |
465 | /****************************************************************************/ |
466 | static int decode_bmpstr(bitstr_t *bs, const struct field_t *f, |
467 | char *base, int level) |
468 | { |
469 | unsigned int len; |
470 | |
471 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
472 | |
473 | switch (f->sz) { |
474 | case BYTE: /* Range == 256 */ |
475 | BYTE_ALIGN(bs); |
476 | CHECK_BOUND(bs, 1); |
477 | len = (*bs->cur++) + f->lb; |
478 | break; |
479 | default: /* 2 <= Range <= 255 */ |
480 | len = get_bits(bs, f->sz) + f->lb; |
481 | BYTE_ALIGN(bs); |
482 | break; |
483 | } |
484 | |
485 | bs->cur += len << 1; |
486 | |
487 | CHECK_BOUND(bs, 0); |
488 | return H323_ERROR_NONE; |
489 | } |
490 | |
491 | /****************************************************************************/ |
492 | static int decode_seq(bitstr_t *bs, const struct field_t *f, |
493 | char *base, int level) |
494 | { |
495 | unsigned int ext, bmp, i, opt, len = 0, bmp2, bmp2_len; |
496 | int err; |
497 | const struct field_t *son; |
498 | unsigned char *beg = NULL; |
499 | |
500 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
501 | |
502 | /* Decode? */ |
503 | base = (base && (f->attr & DECODE)) ? base + f->offset : NULL; |
504 | |
505 | /* Extensible? */ |
506 | ext = (f->attr & EXT) ? get_bit(bs) : 0; |
507 | |
508 | /* Get fields bitmap */ |
509 | bmp = get_bitmap(bs, f->sz); |
510 | if (base) |
511 | *(unsigned int *)base = bmp; |
512 | |
513 | /* Decode the root components */ |
514 | for (i = opt = 0, son = f->fields; i < f->lb; i++, son++) { |
515 | if (son->attr & STOP) { |
516 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", |
517 | son->name); |
518 | return H323_ERROR_STOP; |
519 | } |
520 | |
521 | if (son->attr & OPT) { /* Optional component */ |
522 | if (!((0x80000000U >> (opt++)) & bmp)) /* Not exist */ |
523 | continue; |
524 | } |
525 | |
526 | /* Decode */ |
527 | if (son->attr & OPEN) { /* Open field */ |
528 | CHECK_BOUND(bs, 2); |
529 | len = get_len(bs); |
530 | CHECK_BOUND(bs, len); |
531 | if (!base || !(son->attr & DECODE)) { |
532 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, |
533 | " ", son->name); |
534 | bs->cur += len; |
535 | continue; |
536 | } |
537 | beg = bs->cur; |
538 | |
539 | /* Decode */ |
540 | if ((err = (Decoders[son->type]) (bs, son, base, |
541 | level + 1)) < |
542 | H323_ERROR_NONE) |
543 | return err; |
544 | |
545 | bs->cur = beg + len; |
546 | bs->bit = 0; |
547 | } else if ((err = (Decoders[son->type]) (bs, son, base, |
548 | level + 1)) < |
549 | H323_ERROR_NONE) |
550 | return err; |
551 | } |
552 | |
553 | /* No extension? */ |
554 | if (!ext) |
555 | return H323_ERROR_NONE; |
556 | |
557 | /* Get the extension bitmap */ |
558 | bmp2_len = get_bits(bs, 7) + 1; |
559 | CHECK_BOUND(bs, (bmp2_len + 7) >> 3); |
560 | bmp2 = get_bitmap(bs, bmp2_len); |
561 | bmp |= bmp2 >> f->sz; |
562 | if (base) |
563 | *(unsigned int *)base = bmp; |
564 | BYTE_ALIGN(bs); |
565 | |
566 | /* Decode the extension components */ |
567 | for (opt = 0; opt < bmp2_len; opt++, i++, son++) { |
568 | /* Check Range */ |
569 | if (i >= f->ub) { /* Newer Version? */ |
570 | CHECK_BOUND(bs, 2); |
571 | len = get_len(bs); |
572 | CHECK_BOUND(bs, len); |
573 | bs->cur += len; |
574 | continue; |
575 | } |
576 | |
577 | if (son->attr & STOP) { |
578 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", |
579 | son->name); |
580 | return H323_ERROR_STOP; |
581 | } |
582 | |
583 | if (!((0x80000000 >> opt) & bmp2)) /* Not present */ |
584 | continue; |
585 | |
586 | CHECK_BOUND(bs, 2); |
587 | len = get_len(bs); |
588 | CHECK_BOUND(bs, len); |
589 | if (!base || !(son->attr & DECODE)) { |
590 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", |
591 | son->name); |
592 | bs->cur += len; |
593 | continue; |
594 | } |
595 | beg = bs->cur; |
596 | |
597 | if ((err = (Decoders[son->type]) (bs, son, base, |
598 | level + 1)) < |
599 | H323_ERROR_NONE) |
600 | return err; |
601 | |
602 | bs->cur = beg + len; |
603 | bs->bit = 0; |
604 | } |
605 | return H323_ERROR_NONE; |
606 | } |
607 | |
608 | /****************************************************************************/ |
609 | static int decode_seqof(bitstr_t *bs, const struct field_t *f, |
610 | char *base, int level) |
611 | { |
612 | unsigned int count, effective_count = 0, i, len = 0; |
613 | int err; |
614 | const struct field_t *son; |
615 | unsigned char *beg = NULL; |
616 | |
617 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
618 | |
619 | /* Decode? */ |
620 | base = (base && (f->attr & DECODE)) ? base + f->offset : NULL; |
621 | |
622 | /* Decode item count */ |
623 | switch (f->sz) { |
624 | case BYTE: |
625 | BYTE_ALIGN(bs); |
626 | CHECK_BOUND(bs, 1); |
627 | count = *bs->cur++; |
628 | break; |
629 | case WORD: |
630 | BYTE_ALIGN(bs); |
631 | CHECK_BOUND(bs, 2); |
632 | count = *bs->cur++; |
633 | count <<= 8; |
634 | count = *bs->cur++; |
635 | break; |
636 | case SEMI: |
637 | BYTE_ALIGN(bs); |
638 | CHECK_BOUND(bs, 2); |
639 | count = get_len(bs); |
640 | break; |
641 | default: |
642 | count = get_bits(bs, f->sz); |
643 | break; |
644 | } |
645 | count += f->lb; |
646 | |
647 | /* Write Count */ |
648 | if (base) { |
649 | effective_count = count > f->ub ? f->ub : count; |
650 | *(unsigned int *)base = effective_count; |
651 | base += sizeof(unsigned int); |
652 | } |
653 | |
654 | /* Decode nested field */ |
655 | son = f->fields; |
656 | if (base) |
657 | base -= son->offset; |
658 | for (i = 0; i < count; i++) { |
659 | if (son->attr & OPEN) { |
660 | BYTE_ALIGN(bs); |
661 | len = get_len(bs); |
662 | CHECK_BOUND(bs, len); |
663 | if (!base || !(son->attr & DECODE)) { |
664 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, |
665 | " ", son->name); |
666 | bs->cur += len; |
667 | continue; |
668 | } |
669 | beg = bs->cur; |
670 | |
671 | if ((err = (Decoders[son->type]) (bs, son, |
672 | i < |
673 | effective_count ? |
674 | base : NULL, |
675 | level + 1)) < |
676 | H323_ERROR_NONE) |
677 | return err; |
678 | |
679 | bs->cur = beg + len; |
680 | bs->bit = 0; |
681 | } else |
682 | if ((err = (Decoders[son->type]) (bs, son, |
683 | i < |
684 | effective_count ? |
685 | base : NULL, |
686 | level + 1)) < |
687 | H323_ERROR_NONE) |
688 | return err; |
689 | |
690 | if (base) |
691 | base += son->offset; |
692 | } |
693 | |
694 | return H323_ERROR_NONE; |
695 | } |
696 | |
697 | |
698 | /****************************************************************************/ |
699 | static int decode_choice(bitstr_t *bs, const struct field_t *f, |
700 | char *base, int level) |
701 | { |
702 | unsigned int type, ext, len = 0; |
703 | int err; |
704 | const struct field_t *son; |
705 | unsigned char *beg = NULL; |
706 | |
707 | PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name); |
708 | |
709 | /* Decode? */ |
710 | base = (base && (f->attr & DECODE)) ? base + f->offset : NULL; |
711 | |
712 | /* Decode the choice index number */ |
713 | if ((f->attr & EXT) && get_bit(bs)) { |
714 | ext = 1; |
715 | type = get_bits(bs, 7) + f->lb; |
716 | } else { |
717 | ext = 0; |
718 | type = get_bits(bs, f->sz); |
719 | if (type >= f->lb) |
720 | return H323_ERROR_RANGE; |
721 | } |
722 | |
723 | /* Write Type */ |
724 | if (base) |
725 | *(unsigned int *)base = type; |
726 | |
727 | /* Check Range */ |
728 | if (type >= f->ub) { /* Newer version? */ |
729 | BYTE_ALIGN(bs); |
730 | len = get_len(bs); |
731 | CHECK_BOUND(bs, len); |
732 | bs->cur += len; |
733 | return H323_ERROR_NONE; |
734 | } |
735 | |
736 | /* Transfer to son level */ |
737 | son = &f->fields[type]; |
738 | if (son->attr & STOP) { |
739 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", son->name); |
740 | return H323_ERROR_STOP; |
741 | } |
742 | |
743 | if (ext || (son->attr & OPEN)) { |
744 | BYTE_ALIGN(bs); |
745 | len = get_len(bs); |
746 | CHECK_BOUND(bs, len); |
747 | if (!base || !(son->attr & DECODE)) { |
748 | PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", |
749 | son->name); |
750 | bs->cur += len; |
751 | return H323_ERROR_NONE; |
752 | } |
753 | beg = bs->cur; |
754 | |
755 | if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) < |
756 | H323_ERROR_NONE) |
757 | return err; |
758 | |
759 | bs->cur = beg + len; |
760 | bs->bit = 0; |
761 | } else if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) < |
762 | H323_ERROR_NONE) |
763 | return err; |
764 | |
765 | return H323_ERROR_NONE; |
766 | } |
767 | |
768 | /****************************************************************************/ |
769 | int DecodeRasMessage(unsigned char *buf, size_t sz, RasMessage *ras) |
770 | { |
771 | static const struct field_t ras_message = { |
772 | FNAME("RasMessage") CHOICE, 5, 24, 32, DECODE | EXT, |
773 | 0, _RasMessage |
774 | }; |
775 | bitstr_t bs; |
776 | |
777 | bs.buf = bs.beg = bs.cur = buf; |
778 | bs.end = buf + sz; |
779 | bs.bit = 0; |
780 | |
781 | return decode_choice(&bs, &ras_message, (char *) ras, 0); |
782 | } |
783 | |
784 | /****************************************************************************/ |
785 | static int DecodeH323_UserInformation(unsigned char *buf, unsigned char *beg, |
786 | size_t sz, H323_UserInformation *uuie) |
787 | { |
788 | static const struct field_t h323_userinformation = { |
789 | FNAME("H323-UserInformation") SEQ, 1, 2, 2, DECODE | EXT, |
790 | 0, _H323_UserInformation |
791 | }; |
792 | bitstr_t bs; |
793 | |
794 | bs.buf = buf; |
795 | bs.beg = bs.cur = beg; |
796 | bs.end = beg + sz; |
797 | bs.bit = 0; |
798 | |
799 | return decode_seq(&bs, &h323_userinformation, (char *) uuie, 0); |
800 | } |
801 | |
802 | /****************************************************************************/ |
803 | int DecodeMultimediaSystemControlMessage(unsigned char *buf, size_t sz, |
804 | MultimediaSystemControlMessage * |
805 | mscm) |
806 | { |
807 | static const struct field_t multimediasystemcontrolmessage = { |
808 | FNAME("MultimediaSystemControlMessage") CHOICE, 2, 4, 4, |
809 | DECODE | EXT, 0, _MultimediaSystemControlMessage |
810 | }; |
811 | bitstr_t bs; |
812 | |
813 | bs.buf = bs.beg = bs.cur = buf; |
814 | bs.end = buf + sz; |
815 | bs.bit = 0; |
816 | |
817 | return decode_choice(&bs, &multimediasystemcontrolmessage, |
818 | (char *) mscm, 0); |
819 | } |
820 | |
821 | /****************************************************************************/ |
822 | int DecodeQ931(unsigned char *buf, size_t sz, Q931 *q931) |
823 | { |
824 | unsigned char *p = buf; |
825 | int len; |
826 | |
827 | if (!p || sz < 1) |
828 | return H323_ERROR_BOUND; |
829 | |
830 | /* Protocol Discriminator */ |
831 | if (*p != 0x08) { |
832 | PRINT("Unknown Protocol Discriminator\n"); |
833 | return H323_ERROR_RANGE; |
834 | } |
835 | p++; |
836 | sz--; |
837 | |
838 | /* CallReferenceValue */ |
839 | if (sz < 1) |
840 | return H323_ERROR_BOUND; |
841 | len = *p++; |
842 | sz--; |
843 | if (sz < len) |
844 | return H323_ERROR_BOUND; |
845 | p += len; |
846 | sz -= len; |
847 | |
848 | /* Message Type */ |
849 | if (sz < 1) |
850 | return H323_ERROR_BOUND; |
851 | q931->MessageType = *p++; |
852 | PRINT("MessageType = %02X\n", q931->MessageType); |
853 | if (*p & 0x80) { |
854 | p++; |
855 | sz--; |
856 | } |
857 | |
858 | /* Decode Information Elements */ |
859 | while (sz > 0) { |
860 | if (*p == 0x7e) { /* UserUserIE */ |
861 | if (sz < 3) |
862 | break; |
863 | p++; |
864 | len = *p++ << 8; |
865 | len |= *p++; |
866 | sz -= 3; |
867 | if (sz < len) |
868 | break; |
869 | p++; |
870 | len--; |
871 | return DecodeH323_UserInformation(buf, p, len, |
872 | &q931->UUIE); |
873 | } |
874 | p++; |
875 | sz--; |
876 | if (sz < 1) |
877 | break; |
878 | len = *p++; |
879 | if (sz < len) |
880 | break; |
881 | p += len; |
882 | sz -= len; |
883 | } |
884 | |
885 | PRINT("Q.931 UUIE not found\n"); |
886 | |
887 | return H323_ERROR_BOUND; |
888 | } |
889 |
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