1 /*
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 */
21 #ifndef lint
22 static char rcsid[] =
23 "@(#) $Header: gencode.c,v 1.26 91/06/06 22:36:19 mccanne Exp $ (LBL)";
24 #endif
25
26 #ifdef __STDC__
27 #include <stdlib.h>
28 #endif
29 #include <sys/types.h>
30 #include <sys/socket.h>
31 #include <net/if.h>
32 #include <netinet/in.h>
33 #include <netinet/if_ether.h>
34
35 #include <sys/time.h>
36 #include <net/bpf.h>
37
38 #include "interface.h"
39 #include "gencode.h"
40 #include "nametoaddr.h"
41 #include "extract.h"
42
43 #define JMP(c) ((c)|BPF_JMP|BPF_K)
44
45 extern struct bpf_insn *icode_to_fcode();
46 extern u_long net_mask();
47 static void init_linktype();
48
49 static int alloc_reg();
50 static void free_reg();
51
52 static struct block *root;
53
54 /*
55 * We divy out chunks of memory rather than call malloc each time so
56 * we don't have to worry about leaking memory. It's probably
57 * not a big deal if all this memory was wasted but it this ever
58 * goes into a library that would probably not be a good idea.
59 */
60 #define NCHUNKS 16
61 #define CHUNK0SIZE 1024
62 struct chunk {
63 u_int n_left;
64 void *m;
65 };
66
67 static struct chunk chunks[NCHUNKS];
68 static int cur_chunk;
69
70 static void *
newchunk(n)71 newchunk(n)
72 u_int n;
73 {
74 struct chunk *cp;
75 int k, size;
76
77 /* XXX Round up to nearest long. */
78 n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
79
80 cp = &chunks[cur_chunk];
81 if (n > cp->n_left) {
82 ++cp, k = ++cur_chunk;
83 if (k >= NCHUNKS)
84 error("newchunk: out of chunks");
85 size = CHUNK0SIZE << k;
86 cp->m = (void *)malloc(size);
87 bzero((char *)cp->m, size);
88 cp->n_left = size;
89 if (n > size)
90 error("newchunk: request too big");
91 }
92 cp->n_left -= n;
93 return (void *)((char *)cp->m + cp->n_left);
94 }
95
96 static void
freechunks()97 freechunks()
98 {
99 int i;
100
101 for (i = 0; i < NCHUNKS; ++i)
102 if (chunks[i].m)
103 free(chunks[i].m);
104 }
105
106 static inline struct block *
new_block(code)107 new_block(code)
108 int code;
109 {
110 struct block *p;
111
112 p = (struct block *)newchunk(sizeof(*p));
113 p->s.code = code;
114 p->head = p;
115
116 return p;
117 }
118
119 static inline struct slist *
new_stmt(code)120 new_stmt(code)
121 int code;
122 {
123 struct slist *p;
124
125 p = (struct slist *)newchunk(sizeof(*p));
126 p->s.code = code;
127
128 return p;
129 }
130
131 static struct block *
gen_retblk(v)132 gen_retblk(v)
133 int v;
134 {
135 struct block *b = new_block(BPF_RET|BPF_K);
136
137 b->s.k = v;
138 return b;
139 }
140
141 struct bpf_program *
parse(buf,Oflag,linktype)142 parse(buf, Oflag, linktype)
143 char *buf;
144 int Oflag;
145 int linktype;
146 {
147 extern int n_errors;
148 static struct bpf_program F;
149 struct bpf_insn *p;
150 int len;
151
152 F.bf_insns = 0;
153 F.bf_len = 0;
154
155 lex_init(buf ? buf : "");
156 init_linktype(linktype);
157 yyparse();
158
159 if (n_errors)
160 error("expression syntax error");
161
162 if (root == 0)
163 root = gen_retblk(snaplen);
164
165 if (Oflag) {
166 optimize(&root);
167 if (root == 0 ||
168 (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0))
169 error("expression rejects all packets");
170 }
171 p = icode_to_fcode(root, &len);
172 F.bf_insns = p;
173 F.bf_len = len;
174
175 freechunks();
176 return &F;
177 }
178
179 /*
180 * Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates
181 * which of the jt and jf fields has been resolved and which is a pointer
182 * back to another unresolved block (or nil). At least one of the fields
183 * in each block is already resolved.
184 */
185 static void
backpatch(list,target)186 backpatch(list, target)
187 struct block *list, *target;
188 {
189 struct block *next;
190
191 while (list) {
192 if (!list->sense) {
193 next = JT(list);
194 JT(list) = target;
195 } else {
196 next = JF(list);
197 JF(list) = target;
198 }
199 list = next;
200 }
201 }
202
203 /*
204 * Merge the lists in b0 and b1, using the 'sense' field to indicate
205 * which of jt and jf is the link.
206 */
207 static void
merge(b0,b1)208 merge(b0, b1)
209 struct block *b0, *b1;
210 {
211 register struct block **p = &b0;
212
213 /* Find end of list. */
214 while (*p)
215 p = !((*p)->sense) ? &JT(*p) : &JF(*p);
216
217 /* Concatenate the lists. */
218 *p = b1;
219 }
220
221 void
finish_parse(p)222 finish_parse(p)
223 struct block *p;
224 {
225 backpatch(p, gen_retblk(snaplen));
226 p->sense = !p->sense;
227 backpatch(p, gen_retblk(0));
228 root = p->head;
229 }
230
231 void
gen_and(b0,b1)232 gen_and(b0, b1)
233 struct block *b0, *b1;
234 {
235 backpatch(b0, b1->head);
236 b0->sense = !b0->sense;
237 b1->sense = !b1->sense;
238 merge(b1, b0);
239 b1->sense = !b1->sense;
240 b1->head = b0->head;
241 }
242
243 void
gen_or(b0,b1)244 gen_or(b0, b1)
245 struct block *b0, *b1;
246 {
247 b0->sense = !b0->sense;
248 backpatch(b0, b1->head);
249 b0->sense = !b0->sense;
250 merge(b1, b0);
251 b1->head = b0->head;
252 }
253
254 void
gen_not(b)255 gen_not(b)
256 struct block *b;
257 {
258 b->sense = !b->sense;
259 }
260
261 static struct block *
gen_cmp(offset,size,v)262 gen_cmp(offset, size, v)
263 u_int offset, size;
264 long v;
265 {
266 struct slist *s;
267 struct block *b;
268
269 s = new_stmt(BPF_LD|BPF_ABS|size);
270 s->s.k = offset;
271
272 b = new_block(JMP(BPF_JEQ));
273 b->stmts = s;
274 b->s.k = v;
275
276 return b;
277 }
278
279 struct block *
gen_mcmp(offset,size,v,mask)280 gen_mcmp(offset, size, v, mask)
281 u_int offset, size;
282 long v;
283 u_long mask;
284 {
285 struct block *b = gen_cmp(offset, size, v);
286 struct slist *s;
287
288 if (mask != 0xffffffff) {
289 s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
290 s->s.k = mask;
291 b->stmts->next = s;
292 }
293 return b;
294 }
295
296 struct block *
gen_bcmp(offset,size,v)297 gen_bcmp(offset, size, v)
298 u_int offset;
299 u_int size;
300 u_char *v;
301 {
302 struct block *b, *tmp;
303 int k;
304
305 b = 0;
306 while (size >= 4) {
307 k = size - 4;
308 tmp = gen_cmp(offset + k, BPF_W, EXTRACT_LONG(&v[k]));
309 if (b != 0)
310 gen_and(b, tmp);
311 b = tmp;
312 size -= 4;
313 }
314 while (size >= 2) {
315 k = size - 2;
316 tmp = gen_cmp(offset + k, BPF_H, (long)EXTRACT_SHORT(&v[k]));
317 if (b != 0)
318 gen_and(b, tmp);
319 b = tmp;
320 size -= 2;
321 }
322 if (size > 0) {
323 tmp = gen_cmp(offset, BPF_B, (long)v[0]);
324 if (b != 0)
325 gen_and(b, tmp);
326 b = tmp;
327 }
328 return b;
329 }
330
331 /*
332 * Various code contructs need to know the layout of the data link
333 * layer. These variables give the necessary offsets.
334 */
335 static u_int off_linktype;
336 static u_int off_nl;
337 static int linktype;
338
339 static void
init_linktype(type)340 init_linktype(type)
341 int type;
342 {
343 linktype = type;
344
345 switch (type) {
346 case DLT_EN10MB:
347 off_linktype = 12;
348 off_nl = 14;
349 return;
350
351 case DLT_SLIP:
352 /*
353 * SLIP doesn't have a link level type. The 16 byte
354 * header is hacked into our SLIP driver.
355 */
356 off_linktype = -1;
357 off_nl = 16;
358 return;
359
360 case DLT_PPP:
361 off_linktype = 2;
362 off_nl = 4;
363 return;
364 }
365 error("unknown data link type %x", linktype);
366 /* NOTREACHED */
367 }
368
369 static struct block *
gen_uncond(rsense)370 gen_uncond(rsense)
371 int rsense;
372 {
373 struct block *b;
374 struct slist *s;
375
376 s = new_stmt(BPF_LD|BPF_IMM);
377 s->s.k = !rsense;
378 b = new_block(JMP(BPF_JEQ));
379 b->stmts = s;
380
381 return b;
382 }
383
384 static inline struct block *
gen_true()385 gen_true()
386 {
387 return gen_uncond(1);
388 }
389
390 static inline struct block *
gen_false()391 gen_false()
392 {
393 return gen_uncond(0);
394 }
395
396 struct block *
gen_linktype(proto)397 gen_linktype(proto)
398 int proto;
399 {
400 switch (linktype) {
401 case DLT_SLIP:
402 if (proto == ETHERTYPE_IP)
403 return gen_true();
404 else
405 return gen_false();
406
407 case DLT_PPP:
408 if (proto == ETHERTYPE_IP)
409 proto = 0x0021; /* XXX - need ppp.h defs */
410 break;
411 }
412 return gen_cmp(off_linktype, BPF_H, (long)proto);
413 }
414
415 static struct block *
gen_hostop(addr,mask,dir,proto,src_off,dst_off)416 gen_hostop(addr, mask, dir, proto, src_off, dst_off)
417 u_long addr;
418 u_long mask;
419 int dir, proto;
420 u_int src_off, dst_off;
421 {
422 struct block *b0, *b1;
423 u_int offset;
424
425 switch (dir) {
426
427 case Q_SRC:
428 offset = src_off;
429 break;
430
431 case Q_DST:
432 offset = dst_off;
433 break;
434
435 case Q_AND:
436 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
437 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
438 gen_and(b0, b1);
439 return b1;
440
441 case Q_OR:
442 case Q_DEFAULT:
443 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
444 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
445 gen_or(b0, b1);
446 return b1;
447
448 default:
449 abort();
450 }
451 b0 = gen_linktype(proto);
452 b1 = gen_mcmp(offset, BPF_W, (long)addr, mask);
453 gen_and(b0, b1);
454 return b1;
455 }
456
457 static struct block *
gen_ehostop(eaddr,dir)458 gen_ehostop(eaddr, dir)
459 u_char *eaddr;
460 int dir;
461 {
462 struct block *b0, *b1;
463
464 switch (dir) {
465 case Q_SRC:
466 return gen_bcmp(6, 6, eaddr);
467
468 case Q_DST:
469 return gen_bcmp(0, 6, eaddr);
470
471 case Q_AND:
472 b0 = gen_ehostop(eaddr, Q_SRC);
473 b1 = gen_ehostop(eaddr, Q_DST);
474 gen_and(b0, b1);
475 return b1;
476
477 case Q_DEFAULT:
478 case Q_OR:
479 b0 = gen_ehostop(eaddr, Q_SRC);
480 b1 = gen_ehostop(eaddr, Q_DST);
481 gen_or(b0, b1);
482 return b1;
483 }
484 abort();
485 /* NOTREACHED */
486 }
487
488 static struct block *
gen_host(addr,mask,proto,dir)489 gen_host(addr, mask, proto, dir)
490 u_long addr;
491 u_long mask;
492 int proto;
493 int dir;
494 {
495 struct block *b0, *b1;
496
497 switch (proto) {
498
499 case Q_DEFAULT:
500 b0 = gen_host(addr, mask, Q_IP, dir);
501 b1 = gen_host(addr, mask, Q_ARP, dir);
502 gen_or(b0, b1);
503 b0 = gen_host(addr, mask, Q_RARP, dir);
504 gen_or(b1, b0);
505 return b0;
506
507 case Q_IP:
508 return gen_hostop(addr, mask, dir, ETHERTYPE_IP,
509 off_nl + 12, off_nl + 16);
510
511 case Q_RARP:
512 return gen_hostop(addr, mask, dir, ETHERTYPE_REVARP,
513 off_nl + 14, off_nl + 24);
514
515 case Q_ARP:
516 return gen_hostop(addr, mask, dir, ETHERTYPE_ARP,
517 off_nl + 14, off_nl + 24);
518
519 case Q_TCP:
520 error("'tcp' modifier applied to host");
521
522 case Q_UDP:
523 error("'udp' modifier applied to host");
524
525 case Q_ICMP:
526 error("'icmp' modifier applied to host");
527 }
528 abort();
529 /* NOTREACHED */
530 }
531
532 static struct block *
gen_gateway(eaddr,alist,proto,dir)533 gen_gateway(eaddr, alist, proto, dir)
534 u_char *eaddr;
535 u_long **alist;
536 int proto;
537 int dir;
538 {
539 struct block *b0, *b1, *tmp;
540
541 if (dir != 0)
542 error("direction applied to 'gateway'");
543
544 switch (proto) {
545 case Q_DEFAULT:
546 case Q_IP:
547 case Q_ARP:
548 case Q_RARP:
549 b0 = gen_ehostop(eaddr, Q_OR);
550 b1 = gen_host(**alist++, 0xffffffffL, proto, Q_OR);
551 while (*alist) {
552 tmp = gen_host(**alist++, 0xffffffffL, proto, Q_OR);
553 gen_or(b1, tmp);
554 b1 = tmp;
555 }
556 gen_not(b1);
557 gen_and(b0, b1);
558 return b1;
559 }
560 error("illegal modifier of 'gateway'");
561 /* NOTREACHED */
562 }
563
564 struct block *
gen_proto_abbrev(proto)565 gen_proto_abbrev(proto)
566 int proto;
567 {
568 struct block *b0, *b1;
569
570 switch (proto) {
571
572 case Q_TCP:
573 b0 = gen_linktype(ETHERTYPE_IP);
574 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_TCP);
575 gen_and(b0, b1);
576 break;
577
578 case Q_UDP:
579 b0 = gen_linktype(ETHERTYPE_IP);
580 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_UDP);
581 gen_and(b0, b1);
582 break;
583
584 case Q_ICMP:
585 b0 = gen_linktype(ETHERTYPE_IP);
586 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_ICMP);
587 gen_and(b0, b1);
588 break;
589
590 case Q_IP:
591 b1 = gen_linktype(ETHERTYPE_IP);
592 break;
593
594 case Q_ARP:
595 b1 = gen_linktype(ETHERTYPE_ARP);
596 break;
597
598 case Q_RARP:
599 b1 = gen_linktype(ETHERTYPE_REVARP);
600 break;
601
602 case Q_ETHER:
603 error("'ether' keyword used incorrectly");
604
605 default:
606 abort();
607 }
608 return b1;
609 }
610
611 static struct block *
gen_ipfrag()612 gen_ipfrag()
613 {
614 struct slist *s;
615 struct block *b;
616
617 /* not ip frag */
618 s = new_stmt(BPF_LD|BPF_H|BPF_ABS);
619 s->s.k = off_nl + 6;
620 b = new_block(JMP(BPF_JSET));
621 b->s.k = 0x1fff;
622 b->stmts = s;
623 gen_not(b);
624
625 return b;
626 }
627
628 static struct block *
gen_portatom(off,v)629 gen_portatom(off, v)
630 int off;
631 long v;
632 {
633 struct slist *s;
634 struct block *b;
635
636 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
637 s->s.k = off_nl;
638
639 s->next = new_stmt(BPF_LD|BPF_IND|BPF_H);
640 s->next->s.k = off_nl + off;
641
642 b = new_block(JMP(BPF_JEQ));
643 b->stmts = s;
644 b->s.k = v;
645
646 return b;
647 }
648
649 struct block *
gen_portop(port,proto,dir)650 gen_portop(port, proto, dir)
651 int port;
652 int proto;
653 int dir;
654 {
655 struct block *b0, *b1, *tmp;
656
657 /* ip proto 'proto' */
658 tmp = gen_cmp(off_nl + 9, BPF_B, (long)proto);
659 b0 = gen_ipfrag();
660 gen_and(tmp, b0);
661
662 switch (dir) {
663 case Q_SRC:
664 b1 = gen_portatom(0, (long)port);
665 break;
666
667 case Q_DST:
668 b1 = gen_portatom(2, (long)port);
669 break;
670
671 case Q_OR:
672 case Q_DEFAULT:
673 tmp = gen_portatom(0, (long)port);
674 b1 = gen_portatom(2, (long)port);
675 gen_or(tmp, b1);
676 break;
677
678 case Q_AND:
679 tmp = gen_portatom(0, (long)port);
680 b1 = gen_portatom(2, (long)port);
681 gen_and(tmp, b1);
682 break;
683
684 default:
685 abort();
686 }
687 gen_and(b0, b1);
688
689 return b1;
690 }
691
692 static struct block *
gen_port(port,ip_proto,dir)693 gen_port(port, ip_proto, dir)
694 int port;
695 int ip_proto;
696 int dir;
697 {
698 struct block *b0, *b1, *tmp;
699
700 /* ether proto ip */
701 b0 = gen_linktype(ETHERTYPE_IP);
702
703 switch (ip_proto) {
704 case IPPROTO_UDP:
705 case IPPROTO_TCP:
706 b1 = gen_portop(port, ip_proto, dir);
707 break;
708
709 case PROTO_UNDEF:
710 tmp = gen_portop(port, IPPROTO_TCP, dir);
711 b1 = gen_portop(port, IPPROTO_UDP, dir);
712 gen_or(tmp, b1);
713 break;
714
715 default:
716 abort();
717 }
718 gen_and(b0, b1);
719 return b1;
720 }
721
722 int
lookup_proto(name,proto)723 lookup_proto(name, proto)
724 char *name;
725 int proto;
726 {
727 int v;
728
729 switch (proto) {
730 case Q_DEFAULT:
731 case Q_IP:
732 v = s_nametoproto(name);
733 if (v == PROTO_UNDEF)
734 error("unknown ip proto '%s'", name);
735 break;
736
737 case Q_ETHER:
738 v = s_nametoeproto(name);
739 if (v == PROTO_UNDEF)
740 error("unknown ether proto '%s'", name);
741 break;
742
743 default:
744 v = PROTO_UNDEF;
745 break;
746 }
747 return v;
748 }
749
750 struct block *
gen_proto(v,proto,dir)751 gen_proto(v, proto, dir)
752 int v;
753 int proto;
754 int dir;
755 {
756 struct block *b0, *b1;
757
758 if (dir != Q_DEFAULT)
759 error("direction applied to 'proto'");
760
761 switch (proto) {
762 case Q_DEFAULT:
763 case Q_IP:
764 b0 = gen_linktype(ETHERTYPE_IP);
765 b1 = gen_cmp(off_nl + 9, BPF_B, (long)v);
766 gen_and(b0, b1);
767 return b1;
768
769 case Q_ARP:
770 error("arp does not encapsulate another protocol");
771 /* NOTREACHED */
772
773 case Q_RARP:
774 error("rarp does not encapsulate another protocol");
775 /* NOTREACHED */
776
777 case Q_ETHER:
778 return gen_linktype(v);
779
780 case Q_UDP:
781 error("'udp proto' is bogus");
782
783 case Q_TCP:
784 error("'tcp proto' is bogus");
785
786 case Q_ICMP:
787 error("'icmp proto' is bogus");
788 }
789 abort();
790 /* NOTREACHED */
791 }
792
793 struct block *
gen_scode(name,q)794 gen_scode(name, q)
795 char *name;
796 struct qual q;
797 {
798 int proto = q.protocol;
799 int dir = q.dir;
800 u_char *eaddr;
801 u_long mask, addr, **alist;
802 struct block *b, *tmp;
803 int port, real_proto;
804
805 switch (q.primary) {
806
807 case Q_NET:
808 addr = s_nametonetaddr(name);
809 if (addr == 0)
810 error("unknown network '%s'", name);
811 mask = net_mask(&addr);
812 return gen_host(addr, mask, proto, dir);
813
814 case Q_DEFAULT:
815 case Q_HOST:
816 if (proto == Q_ETHER) {
817 eaddr = ETHER_hostton(name);
818 if (eaddr == 0)
819 error("unknown ether host '%s'", name);
820 return gen_ehostop(eaddr, dir);
821
822 } else {
823 alist = s_nametoaddr(name);
824 if (alist == 0 || *alist == 0)
825 error("uknown host '%s'", name);
826 b = gen_host(**alist++, 0xffffffffL, proto, dir);
827 while (*alist) {
828 tmp = gen_host(**alist++, 0xffffffffL,
829 proto, dir);
830 gen_or(b, tmp);
831 b = tmp;
832 }
833 return b;
834 }
835
836 case Q_PORT:
837 if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP)
838 error("illegal qualifier of 'port'");
839 if (s_nametoport(name, &port, &real_proto) == 0)
840 error("unknown port '%s'", name);
841 if (proto == Q_UDP) {
842 if (real_proto == IPPROTO_TCP)
843 error("port '%s' is tcp", name);
844 else
845 /* override PROTO_UNDEF */
846 real_proto = IPPROTO_UDP;
847 }
848 if (proto == Q_TCP) {
849 if (real_proto == IPPROTO_UDP)
850 error("port '%s' is udp", name);
851 else
852 /* override PROTO_UNDEF */
853 real_proto = IPPROTO_TCP;
854 }
855 return gen_port(port, real_proto, dir);
856
857 case Q_GATEWAY:
858 eaddr = ETHER_hostton(name);
859 if (eaddr == 0)
860 error("unknown ether host: %s", name);
861
862 alist = s_nametoaddr(name);
863 if (alist == 0 || *alist == 0)
864 error("uknown host '%s'", name);
865 return gen_gateway(eaddr, alist, proto, dir);
866
867 case Q_PROTO:
868 real_proto = lookup_proto(name, proto);
869 if (real_proto >= 0)
870 return gen_proto(real_proto, proto, dir);
871 else
872 error("unknown protocol: %s", name);
873 }
874 abort();
875 /* NOTREACHED */
876 }
877
878 struct block *
gen_ncode(v,q)879 gen_ncode(v, q)
880 u_long v;
881 struct qual q;
882 {
883 u_long mask;
884 int proto = q.protocol;
885 int dir = q.dir;
886
887 switch (q.primary) {
888
889 case Q_DEFAULT:
890 case Q_HOST:
891 case Q_NET:
892 mask = net_mask(&v);
893 return gen_host(v, mask, proto, dir);
894
895 case Q_PORT:
896 if (proto == Q_UDP)
897 proto = IPPROTO_UDP;
898 else if (proto == Q_TCP)
899 proto = IPPROTO_TCP;
900 else if (proto == Q_DEFAULT)
901 proto = PROTO_UNDEF;
902 else
903 error("illegal qualifier of 'port'");
904
905 return gen_port((int)v, proto, dir);
906
907 case Q_GATEWAY:
908 error("'gateway' requires a name");
909 /* NOTREACHED */
910
911 case Q_PROTO:
912 return gen_proto((int)v, proto, dir);
913 }
914 abort();
915 /* NOTREACHED */
916 }
917
918 struct block *
gen_ecode(eaddr,q)919 gen_ecode(eaddr, q)
920 u_char *eaddr;
921 struct qual q;
922 {
923 if ((q.primary == Q_HOST || q.primary == Q_DEFAULT)
924 && q.protocol == Q_ETHER)
925 return gen_ehostop(eaddr, (int)q.dir);
926 else
927 error("ethernet address used in non-ether expression");
928 /* NOTREACHED */
929 }
930
931 void
sappend(s0,s1)932 sappend(s0, s1)
933 struct slist *s0, *s1;
934 {
935 /*
936 * This is definitely not the best way to do this, but the
937 * lists will rarely get long.
938 */
939 while (s0->next)
940 s0 = s0->next;
941 s0->next = s1;
942 }
943
944 struct slist *
xfer_to_x(a)945 xfer_to_x(a)
946 struct arth *a;
947 {
948 struct slist *s;
949
950 s = new_stmt(BPF_LDX|BPF_MEM);
951 s->s.k = a->regno;
952 return s;
953 }
954
955 struct slist *
xfer_to_a(a)956 xfer_to_a(a)
957 struct arth *a;
958 {
959 struct slist *s;
960
961 s = new_stmt(BPF_LD|BPF_MEM);
962 s->s.k = a->regno;
963 return s;
964 }
965
966 struct arth *
gen_load(proto,index,size)967 gen_load(proto, index, size)
968 int proto;
969 struct arth *index;
970 int size;
971 {
972 struct slist *s, *tmp;
973 struct block *b;
974 int regno = alloc_reg();
975
976 free_reg(index->regno);
977 switch (size) {
978
979 default:
980 error("data size must be 1, 2, or 4");
981
982 case 1:
983 size = BPF_B;
984 break;
985
986 case 2:
987 size = BPF_H;
988 break;
989
990 case 4:
991 size = BPF_W;
992 break;
993 }
994 switch (proto) {
995 default:
996 error("unsupported index operation");
997
998 case Q_ETHER:
999 s = xfer_to_x(index);
1000 tmp = new_stmt(BPF_LD|BPF_IND|size);
1001 sappend(s, tmp);
1002 sappend(index->s, s);
1003 break;
1004
1005 case Q_IP:
1006 case Q_ARP:
1007 case Q_RARP:
1008 s = xfer_to_x(index);
1009 tmp = new_stmt(BPF_LD|BPF_IND|size);
1010 tmp->s.k = off_nl;
1011 sappend(s, tmp);
1012 sappend(index->s, s);
1013
1014 b = gen_proto_abbrev(proto);
1015 if (index->b)
1016 gen_and(index->b, b);
1017 index->b = b;
1018 break;
1019
1020 case Q_TCP:
1021 case Q_UDP:
1022 case Q_ICMP:
1023 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
1024 s->s.k = off_nl;
1025 sappend(s, xfer_to_a(index));
1026 sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X));
1027 sappend(s, new_stmt(BPF_MISC|BPF_TAX));
1028 sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size));
1029 tmp->s.k = off_nl;
1030 sappend(index->s, s);
1031
1032 gen_and(gen_proto_abbrev(proto), b = gen_ipfrag());
1033 if (index->b)
1034 gen_and(index->b, b);
1035 index->b = b;
1036 break;
1037 }
1038 index->regno = regno;
1039 s = new_stmt(BPF_ST);
1040 s->s.k = regno;
1041 sappend(index->s, s);
1042
1043 return index;
1044 }
1045
1046 struct block *
gen_relation(code,a0,a1,reversed)1047 gen_relation(code, a0, a1, reversed)
1048 int code;
1049 struct arth *a0, *a1;
1050 int reversed;
1051 {
1052 struct slist *s0, *s1, *s2;
1053 struct block *b, *tmp;
1054
1055 s0 = xfer_to_x(a1);
1056 s1 = xfer_to_a(a0);
1057 s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X);
1058 b = new_block(JMP(code));
1059 if (reversed)
1060 gen_not(b);
1061
1062 sappend(s1, s2);
1063 sappend(s0, s1);
1064 sappend(a1->s, s0);
1065 sappend(a0->s, a1->s);
1066
1067 b->stmts = a0->s;
1068
1069 free_reg(a0->regno);
1070 free_reg(a1->regno);
1071
1072 /* 'and' together protocol checks */
1073 if (a0->b) {
1074 if (a1->b) {
1075 gen_and(a0->b, tmp = a1->b);
1076 }
1077 else
1078 tmp = a0->b;
1079 } else
1080 tmp = a1->b;
1081
1082 if (tmp)
1083 gen_and(tmp, b);
1084
1085 return b;
1086 }
1087
1088 struct arth *
gen_loadlen()1089 gen_loadlen()
1090 {
1091 int regno = alloc_reg();
1092 struct arth *a = (struct arth *)newchunk(sizeof(*a));
1093 struct slist *s;
1094
1095 s = new_stmt(BPF_LD|BPF_LEN);
1096 s->next = new_stmt(BPF_ST);
1097 s->next->s.k = regno;
1098 a->s = s;
1099 a->regno = regno;
1100
1101 return a;
1102 }
1103
1104 struct arth *
gen_loadi(val)1105 gen_loadi(val)
1106 int val;
1107 {
1108 struct arth *a;
1109 struct slist *s;
1110 int reg;
1111
1112 a = (struct arth *)newchunk(sizeof(*a));
1113
1114 reg = alloc_reg();
1115
1116 s = new_stmt(BPF_LD|BPF_IMM);
1117 s->s.k = val;
1118 s->next = new_stmt(BPF_ST);
1119 s->next->s.k = reg;
1120 a->s = s;
1121 a->regno = reg;
1122
1123 return a;
1124 }
1125
1126 struct arth *
gen_neg(a)1127 gen_neg(a)
1128 struct arth *a;
1129 {
1130 struct slist *s;
1131
1132 s = xfer_to_a(a);
1133 sappend(a->s, s);
1134 s = new_stmt(BPF_ALU|BPF_NEG);
1135 s->s.k = 0;
1136 sappend(a->s, s);
1137 s = new_stmt(BPF_ST);
1138 s->s.k = a->regno;
1139 sappend(a->s, s);
1140
1141 return a;
1142 }
1143
1144 struct arth *
gen_arth(code,a0,a1)1145 gen_arth(code, a0, a1)
1146 int code;
1147 struct arth *a0, *a1;
1148 {
1149 struct slist *s0, *s1, *s2;
1150
1151 s0 = xfer_to_x(a1);
1152 s1 = xfer_to_a(a0);
1153 s2 = new_stmt(BPF_ALU|BPF_X|code);
1154
1155 sappend(s1, s2);
1156 sappend(s0, s1);
1157 sappend(a1->s, s0);
1158 sappend(a0->s, a1->s);
1159
1160 free_reg(a1->regno);
1161
1162 s0 = new_stmt(BPF_ST);
1163 a0->regno = s0->s.k = alloc_reg();
1164 sappend(a0->s, s0);
1165
1166 return a0;
1167 }
1168
1169 /*
1170 * Here we handle simple allocation of the scratch registers.
1171 * If too many registers are alloc'd, the allocator punts.
1172 */
1173 static int regused[BPF_MEMWORDS];
1174 static int curreg;
1175
1176 /*
1177 * Return the next free register.
1178 */
1179 static int
alloc_reg()1180 alloc_reg()
1181 {
1182 int n = BPF_MEMWORDS;
1183
1184 while (--n >= 0) {
1185 if (regused[curreg])
1186 curreg = (curreg + 1) % BPF_MEMWORDS;
1187 else {
1188 regused[curreg] = 1;
1189 return curreg;
1190 }
1191 }
1192 error("too many registers needed to evaluate expression");
1193 /* NOTREACHED */
1194 }
1195
1196 /*
1197 * Return a register to the table so it can
1198 * be used later.
1199 */
1200 static void
free_reg(n)1201 free_reg(n)
1202 int n;
1203 {
1204 regused[n] = 0;
1205 }
1206
1207 static struct block *
gen_len(jmp,n)1208 gen_len(jmp, n)
1209 int jmp;
1210 int n;
1211 {
1212 struct slist *s;
1213 struct block *b;
1214
1215 s = new_stmt(BPF_LD|BPF_LEN);
1216 s->next = new_stmt(BPF_SUB|BPF_IMM);
1217 s->next->s.k = n;
1218 b = new_block(JMP(jmp));
1219 b->stmts = s;
1220
1221 return b;
1222 }
1223
1224 struct block *
gen_greater(n)1225 gen_greater(n)
1226 int n;
1227 {
1228 return gen_len(BPF_JGE, n);
1229 }
1230
1231 struct block *
gen_less(n)1232 gen_less(n)
1233 int n;
1234 {
1235 struct block *b;
1236
1237 b = gen_len(BPF_JGT, n);
1238 gen_not(b);
1239
1240 return b;
1241 }
1242
1243 struct block *
gen_byteop(op,idx,val)1244 gen_byteop(op, idx, val)
1245 int op;
1246 int idx;
1247 int val;
1248 {
1249 struct block *b;
1250 struct slist *s;
1251
1252 switch (op) {
1253 default:
1254 abort();
1255
1256 case '=':
1257 return gen_cmp((u_int)idx, BPF_B, (long)val);
1258
1259 case '<':
1260 b = gen_cmp((u_int)idx, BPF_B, (long)val);
1261 b->s.code = JMP(BPF_JGE);
1262 gen_not(b);
1263 return b;
1264
1265 case '>':
1266 b = gen_cmp((u_int)idx, BPF_B, (long)val);
1267 b->s.code = JMP(BPF_JGT);
1268 return b;
1269
1270 case '|':
1271 s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
1272 break;
1273
1274 case '&':
1275 s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
1276 break;
1277 }
1278 s->s.k = val;
1279 b = new_block(JMP(BPF_JEQ));
1280 b->stmts = s;
1281 gen_not(b);
1282
1283 return b;
1284 }
1285
1286 struct block *
gen_broadcast()1287 gen_broadcast()
1288 {
1289 static u_char ebroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
1290
1291 return gen_ehostop(ebroadcast, Q_DST);
1292 }
1293
1294