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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
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
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
62#define FIXD 0
63
64#define BYTE 9
65#define WORD 10
66#define CONS 11
67#define SEMI 12
68#define UNCO 13
69
70
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
80typedef 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
94typedef 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
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)
107static unsigned int get_len(bitstr_t *bs);
108static unsigned int get_bit(bitstr_t *bs);
109static unsigned int get_bits(bitstr_t *bs, unsigned int b);
110static unsigned int get_bitmap(bitstr_t *bs, unsigned int b);
111static unsigned int get_uint(bitstr_t *bs, int b);
112
113
114static int decode_nul(bitstr_t *bs, const struct field_t *f, char *base, int level);
115static int decode_bool(bitstr_t *bs, const struct field_t *f, char *base, int level);
116static int decode_oid(bitstr_t *bs, const struct field_t *f, char *base, int level);
117static int decode_int(bitstr_t *bs, const struct field_t *f, char *base, int level);
118static int decode_enum(bitstr_t *bs, const struct field_t *f, char *base, int level);
119static int decode_bitstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
120static int decode_numstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
121static int decode_octstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
122static int decode_bmpstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
123static int decode_seq(bitstr_t *bs, const struct field_t *f, char *base, int level);
124static int decode_seqof(bitstr_t *bs, const struct field_t *f, char *base, int level);
125static int decode_choice(bitstr_t *bs, const struct field_t *f, char *base, int level);
126
127
128typedef int (*decoder_t)(bitstr_t *, const struct field_t *, char *, int);
129static 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
146
147#include "nf_conntrack_h323_types.c"
148
149
150
151
152
153static 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
169static 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
180static 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 {
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
206static 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
244
245static 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
267static 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
276static 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
288static 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
305static 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:
314 BYTE_ALIGN(bs);
315 bs->cur++;
316 break;
317 case WORD:
318 BYTE_ALIGN(bs);
319 bs->cur += 2;
320 break;
321 case CONS:
322 len = get_bits(bs, 2) + 1;
323 BYTE_ALIGN(bs);
324 if (base && (f->attr & DECODE)) {
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:
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
349static 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
365static 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:
375 len = f->lb;
376 break;
377 case WORD:
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
399static 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
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
417static 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:
426 if (f->lb > 2) {
427 BYTE_ALIGN(bs);
428 if (base && (f->attr & DECODE)) {
429
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:
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:
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
466static 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:
475 BYTE_ALIGN(bs);
476 CHECK_BOUND(bs, 1);
477 len = (*bs->cur++) + f->lb;
478 break;
479 default:
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
492static 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
503 base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
504
505
506 ext = (f->attr & EXT) ? get_bit(bs) : 0;
507
508
509 bmp = get_bitmap(bs, f->sz);
510 if (base)
511 *(unsigned int *)base = bmp;
512
513
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) {
522 if (!((0x80000000U >> (opt++)) & bmp))
523 continue;
524 }
525
526
527 if (son->attr & OPEN) {
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
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
554 if (!ext)
555 return H323_ERROR_NONE;
556
557
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
567 for (opt = 0; opt < bmp2_len; opt++, i++, son++) {
568
569 if (i >= f->ub) {
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))
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
609static 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
620 base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
621
622
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
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
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
699static 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
710 base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
711
712
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
724 if (base)
725 *(unsigned int *)base = type;
726
727
728 if (type >= f->ub) {
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
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
769int 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
785static 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
803int 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
822int 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
831 if (*p != 0x08) {
832 PRINT("Unknown Protocol Discriminator\n");
833 return H323_ERROR_RANGE;
834 }
835 p++;
836 sz--;
837
838
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
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
859 while (sz > 0) {
860 if (*p == 0x7e) {
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
