aboutsummaryrefslogtreecommitdiffstats
path: root/tools/net/bpf_exp.y
blob: f8332749b44c49a45b2c9f10165f7b9ee6d62cd4 (plain) (blame)
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
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
/*
 * BPF asm code parser
 *
 * This program is free software; you can distribute 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.
 *
 * Syntax kept close to:
 *
 * Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new
 * architecture for user-level packet capture. In Proceedings of the
 * USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993
 * Conference Proceedings (USENIX'93). USENIX Association, Berkeley,
 * CA, USA, 2-2.
 *
 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
 */

%{

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <linux/filter.h>

#include "bpf_exp.yacc.h"

enum jmp_type { JTL, JFL, JKL };

extern FILE *yyin;
extern int yylex(void);
extern void yyerror(const char *str);

extern void bpf_asm_compile(FILE *fp, bool cstyle);
static void bpf_set_curr_instr(uint16_t op, uint8_t jt, uint8_t jf, uint32_t k);
static void bpf_set_curr_label(char *label);
static void bpf_set_jmp_label(char *label, enum jmp_type type);

%}

%union {
	char *label;
	uint32_t number;
}

%token OP_LDB OP_LDH OP_LD OP_LDX OP_ST OP_STX OP_JMP OP_JEQ OP_JGT OP_JGE
%token OP_JSET OP_ADD OP_SUB OP_MUL OP_DIV OP_AND OP_OR OP_XOR OP_LSH OP_RSH
%token OP_RET OP_TAX OP_TXA OP_LDXB OP_MOD OP_NEG OP_JNEQ OP_JLT OP_JLE OP_LDI
%token OP_LDXI

%token K_PKT_LEN K_PROTO K_TYPE K_NLATTR K_NLATTR_NEST K_MARK K_QUEUE K_HATYPE
%token K_RXHASH K_CPU K_IFIDX K_VLANT K_VLANP K_VLANTPID K_POFF K_RAND

%token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%'

%token number label

%type <label> label
%type <number> number

%%

prog
	: line
	| prog line
	;

line
	: instr
	| labelled_instr
	;

labelled_instr
	: labelled instr
	;

instr
	: ldb
	| ldh
	| ld
	| ldi
	| ldx
	| ldxi
	| st
	| stx
	| jmp
	| jeq
	| jneq
	| jlt
	| jle
	| jgt
	| jge
	| jset
	| add
	| sub
	| mul
	| div
	| mod
	| neg
	| and
	| or
	| xor
	| lsh
	| rsh
	| ret
	| tax
	| txa
	;

labelled
	: label ':' { bpf_set_curr_label($1); }
	;

ldb
	: OP_LDB '[' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $5); }
	| OP_LDB '[' '%' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $6); }
	| OP_LDB '[' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, $3); }
	| OP_LDB K_PROTO {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PROTOCOL); }
	| OP_LDB K_TYPE {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PKTTYPE); }
	| OP_LDB K_IFIDX {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_IFINDEX); }
	| OP_LDB K_NLATTR {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR); }
	| OP_LDB K_NLATTR_NEST {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
	| OP_LDB K_MARK {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_MARK); }
	| OP_LDB K_QUEUE {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_QUEUE); }
	| OP_LDB K_HATYPE {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_HATYPE); }
	| OP_LDB K_RXHASH {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RXHASH); }
	| OP_LDB K_CPU {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_CPU); }
	| OP_LDB K_VLANT {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG); }
	| OP_LDB K_VLANP {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
	| OP_LDB K_POFF {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
	| OP_LDB K_RAND {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RANDOM); }
	| OP_LDB K_VLANTPID {
		bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TPID); }
	;

ldh
	: OP_LDH '[' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $5); }
	| OP_LDH '[' '%' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $6); }
	| OP_LDH '[' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, $3); }
	| OP_LDH K_PROTO {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PROTOCOL); }
	| OP_LDH K_TYPE {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PKTTYPE); }
	| OP_LDH K_IFIDX {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_IFINDEX); }
	| OP_LDH K_NLATTR {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR); }
	| OP_LDH K_NLATTR_NEST {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
	| OP_LDH K_MARK {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_MARK); }
	| OP_LDH K_QUEUE {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_QUEUE); }
	| OP_LDH K_HATYPE {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_HATYPE); }
	| OP_LDH K_RXHASH {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RXHASH); }
	| OP_LDH K_CPU {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_CPU); }
	| OP_LDH K_VLANT {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG); }
	| OP_LDH K_VLANP {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
	| OP_LDH K_POFF {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
	| OP_LDH K_RAND {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RANDOM); }
	| OP_LDH K_VLANTPID {
		bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TPID); }
	;

ldi
	: OP_LDI '#' number {
		bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
	| OP_LDI number {
		bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $2); }
	;

ld
	: OP_LD '#' number {
		bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
	| OP_LD K_PKT_LEN {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_LEN, 0, 0, 0); }
	| OP_LD K_PROTO {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PROTOCOL); }
	| OP_LD K_TYPE {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PKTTYPE); }
	| OP_LD K_IFIDX {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_IFINDEX); }
	| OP_LD K_NLATTR {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR); }
	| OP_LD K_NLATTR_NEST {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
	| OP_LD K_MARK {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_MARK); }
	| OP_LD K_QUEUE {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_QUEUE); }
	| OP_LD K_HATYPE {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_HATYPE); }
	| OP_LD K_RXHASH {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RXHASH); }
	| OP_LD K_CPU {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_CPU); }
	| OP_LD K_VLANT {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG); }
	| OP_LD K_VLANP {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
	| OP_LD K_POFF {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
	| OP_LD K_RAND {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_RANDOM); }
	| OP_LD K_VLANTPID {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
				   SKF_AD_OFF + SKF_AD_VLAN_TPID); }
	| OP_LD 'M' '[' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); }
	| OP_LD '[' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $5); }
	| OP_LD '[' '%' 'x' '+' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $6); }
	| OP_LD '[' number ']' {
		bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, $3); }
	;

ldxi
	: OP_LDXI '#' number {
		bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
	| OP_LDXI number {
		bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $2); }
	;

ldx
	: OP_LDX '#' number {
		bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
	| OP_LDX K_PKT_LEN {
		bpf_set_curr_instr(BPF_LDX | BPF_W | BPF_LEN, 0, 0, 0); }
	| OP_LDX 'M' '[' number ']' {
		bpf_set_curr_instr(BPF_LDX | BPF_MEM, 0, 0, $4); }
	| OP_LDXB number '*' '(' '[' number ']' '&' number ')' {
		if ($2 != 4 || $9 != 0xf) {
			fprintf(stderr, "ldxb offset not supported!\n");
			exit(0);
		} else {
			bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
	| OP_LDX number '*' '(' '[' number ']' '&' number ')' {
		if ($2 != 4 || $9 != 0xf) {
			fprintf(stderr, "ldxb offset not supported!\n");
			exit(0);
		} else {
			bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
	;

st
	: OP_ST 'M' '[' number ']' {
		bpf_set_curr_instr(BPF_ST, 0, 0, $4); }
	;

stx
	: OP_STX 'M' '[' number ']' {
		bpf_set_curr_instr(BPF_STX, 0, 0, $4); }
	;

jmp
	: OP_JMP label {
		bpf_set_jmp_label($2, JKL);
		bpf_set_curr_instr(BPF_JMP | BPF_JA, 0, 0, 0); }
	;

jeq
	: OP_JEQ '#' number ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
	| OP_JEQ 'x' ',' label ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_jmp_label($6, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	| OP_JEQ '%' 'x' ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	| OP_JEQ '#' number ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
	| OP_JEQ 'x' ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	| OP_JEQ '%' 'x' ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	;

jneq
	: OP_JNEQ '#' number ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
	| OP_JNEQ 'x' ',' label {
		bpf_set_jmp_label($4, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	| OP_JNEQ '%' 'x' ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
	;

jlt
	: OP_JLT '#' number ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
	| OP_JLT 'x' ',' label {
		bpf_set_jmp_label($4, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	| OP_JLT '%' 'x' ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	;

jle
	: OP_JLE '#' number ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
	| OP_JLE 'x' ',' label {
		bpf_set_jmp_label($4, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	| OP_JLE '%' 'x' ',' label {
		bpf_set_jmp_label($5, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	;

jgt
	: OP_JGT '#' number ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
	| OP_JGT 'x' ',' label ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_jmp_label($6, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	| OP_JGT '%' 'x' ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	| OP_JGT '#' number ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
	| OP_JGT 'x' ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	| OP_JGT '%' 'x' ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
	;

jge
	: OP_JGE '#' number ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
	| OP_JGE 'x' ',' label ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_jmp_label($6, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	| OP_JGE '%' 'x' ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	| OP_JGE '#' number ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
	| OP_JGE 'x' ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	| OP_JGE '%' 'x' ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
	;

jset
	: OP_JSET '#' number ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
	| OP_JSET 'x' ',' label ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_jmp_label($6, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
	| OP_JSET '%' 'x' ',' label ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_jmp_label($7, JFL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
	| OP_JSET '#' number ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
	| OP_JSET 'x' ',' label {
		bpf_set_jmp_label($4, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
	| OP_JSET '%' 'x' ',' label {
		bpf_set_jmp_label($5, JTL);
		bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
	;

add
	: OP_ADD '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_K, 0, 0, $3); }
	| OP_ADD 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
	| OP_ADD '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
	;

sub
	: OP_SUB '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_K, 0, 0, $3); }
	| OP_SUB 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
	| OP_SUB '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
	;

mul
	: OP_MUL '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_K, 0, 0, $3); }
	| OP_MUL 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
	| OP_MUL '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
	;

div
	: OP_DIV '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_K, 0, 0, $3); }
	| OP_DIV 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
	| OP_DIV '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
	;

mod
	: OP_MOD '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_K, 0, 0, $3); }
	| OP_MOD 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
	| OP_MOD '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
	;

neg
	: OP_NEG {
		bpf_set_curr_instr(BPF_ALU | BPF_NEG, 0, 0, 0); }
	;

and
	: OP_AND '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_K, 0, 0, $3); }
	| OP_AND 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
	| OP_AND '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
	;

or
	: OP_OR '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_K, 0, 0, $3); }
	| OP_OR 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
	| OP_OR '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
	;

xor
	: OP_XOR '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_K, 0, 0, $3); }
	| OP_XOR 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
	| OP_XOR '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
	;

lsh
	: OP_LSH '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_K, 0, 0, $3); }
	| OP_LSH 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
	| OP_LSH '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
	;

rsh
	: OP_RSH '#' number {
		bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_K, 0, 0, $3); }
	| OP_RSH 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
	| OP_RSH '%' 'x' {
		bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
	;

ret
	: OP_RET 'a' {
		bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
	| OP_RET '%' 'a' {
		bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
	| OP_RET 'x' {
		bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
	| OP_RET '%' 'x' {
		bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
	| OP_RET '#' number {
		bpf_set_curr_instr(BPF_RET | BPF_K, 0, 0, $3); }
	;

tax
	: OP_TAX {
		bpf_set_curr_instr(BPF_MISC | BPF_TAX, 0, 0, 0); }
	;

txa
	: OP_TXA {
		bpf_set_curr_instr(BPF_MISC | BPF_TXA, 0, 0, 0); }
	;

%%

static int curr_instr = 0;
static struct sock_filter out[BPF_MAXINSNS];
static char **labels, **labels_jt, **labels_jf, **labels_k;

static void bpf_assert_max(void)
{
	if (curr_instr >= BPF_MAXINSNS) {
		fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS);
		exit(0);
	}
}

static void bpf_set_curr_instr(uint16_t code, uint8_t jt, uint8_t jf,
			       uint32_t k)
{
	bpf_assert_max();
	out[curr_instr].code = code;
	out[curr_instr].jt = jt;
	out[curr_instr].jf = jf;
	out[curr_instr].k = k;
	curr_instr++;
}

static void bpf_set_curr_label(char *label)
{
	bpf_assert_max();
	labels[curr_instr] = label;
}

static void bpf_set_jmp_label(char *label, enum jmp_type type)
{
	bpf_assert_max();
	switch (type) {
	case JTL:
		labels_jt[curr_instr] = label;
		break;
	case JFL:
		labels_jf[curr_instr] = label;
		break;
	case JKL:
		labels_k[curr_instr] = label;
		break;
	}
}

static int bpf_find_insns_offset(const char *label)
{
	int i, max = curr_instr, ret = -ENOENT;

	for (i = 0; i < max; i++) {
		if (labels[i] && !strcmp(label, labels[i])) {
			ret = i;
			break;
		}
	}

	if (ret == -ENOENT) {
		fprintf(stderr, "no such label \'%s\'!\n", label);
		exit(0);
	}

	return ret;
}

static void bpf_stage_1_insert_insns(void)
{
	yyparse();
}

static void bpf_reduce_k_jumps(void)
{
	int i;

	for (i = 0; i < curr_instr; i++) {
		if (labels_k[i]) {
			int off = bpf_find_insns_offset(labels_k[i]);
			out[i].k = (uint32_t) (off - i - 1);
		}
	}
}

static void bpf_reduce_jt_jumps(void)
{
	int i;

	for (i = 0; i < curr_instr; i++) {
		if (labels_jt[i]) {
			int off = bpf_find_insns_offset(labels_jt[i]);
			out[i].jt = (uint8_t) (off - i -1);
		}
	}
}

static void bpf_reduce_jf_jumps(void)
{
	int i;

	for (i = 0; i < curr_instr; i++) {
		if (labels_jf[i]) {
			int off = bpf_find_insns_offset(labels_jf[i]);
			out[i].jf = (uint8_t) (off - i - 1);
		}
	}
}

static void bpf_stage_2_reduce_labels(void)
{
	bpf_reduce_k_jumps();
	bpf_reduce_jt_jumps();
	bpf_reduce_jf_jumps();
}

static void bpf_pretty_print_c(void)
{
	int i;

	for (i = 0; i < curr_instr; i++)
		printf("{ %#04x, %2u, %2u, %#010x },\n", out[i].code,
		       out[i].jt, out[i].jf, out[i].k);
}

static void bpf_pretty_print(void)
{
	int i;

	printf("%u,", curr_instr);
	for (i = 0; i < curr_instr; i++)
		printf("%u %u %u %u,", out[i].code,
		       out[i].jt, out[i].jf, out[i].k);
	printf("\n");
}

static void bpf_init(void)
{
	memset(out, 0, sizeof(out));

	labels = calloc(BPF_MAXINSNS, sizeof(*labels));
	assert(labels);
	labels_jt = calloc(BPF_MAXINSNS, sizeof(*labels_jt));
	assert(labels_jt);
	labels_jf = calloc(BPF_MAXINSNS, sizeof(*labels_jf));
	assert(labels_jf);
	labels_k = calloc(BPF_MAXINSNS, sizeof(*labels_k));
	assert(labels_k);
}

static void bpf_destroy_labels(void)
{
	int i;

	for (i = 0; i < curr_instr; i++) {
		free(labels_jf[i]);
		free(labels_jt[i]);
		free(labels_k[i]);
		free(labels[i]);
	}
}

static void bpf_destroy(void)
{
	bpf_destroy_labels();
	free(labels_jt);
	free(labels_jf);
	free(labels_k);
	free(labels);
}

void bpf_asm_compile(FILE *fp, bool cstyle)
{
	yyin = fp;

	bpf_init();
	bpf_stage_1_insert_insns();
	bpf_stage_2_reduce_labels();
	bpf_destroy();

	if (cstyle)
		bpf_pretty_print_c();
	else
		bpf_pretty_print();

	if (fp != stdin)
		fclose(yyin);
}

void yyerror(const char *str)
{
	exit(1);
}