1 /* $OpenBSD: gencode.c,v 1.4 1996/07/12 13:19:08 mickey Exp $ */ 2 3 /* 4 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that: (1) source code distributions 9 * retain the above copyright notice and this paragraph in its entirety, (2) 10 * distributions including binary code include the above copyright notice and 11 * this paragraph in its entirety in the documentation or other materials 12 * provided with the distribution, and (3) all advertising materials mentioning 13 * features or use of this software display the following acknowledgement: 14 * ``This product includes software developed by the University of California, 15 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 16 * the University nor the names of its contributors may be used to endorse 17 * or promote products derived from this software without specific prior 18 * written permission. 19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 20 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 21 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 22 */ 23 #ifndef lint 24 static char rcsid[] = 25 "@(#) Header: gencode.c,v 1.81 96/06/19 23:09:09 leres Exp (LBL)"; 26 #endif 27 28 #include <sys/types.h> 29 #include <sys/socket.h> 30 #include <sys/time.h> 31 32 #if __STDC__ 33 struct mbuf; 34 struct rtentry; 35 #endif 36 37 #include <net/if.h> 38 #include <net/bpf.h> 39 40 #include <netinet/in.h> 41 #include <netinet/if_ether.h> 42 43 #include <stdlib.h> 44 #include <memory.h> 45 #include <pcap.h> 46 #include <pcap-namedb.h> 47 #include <setjmp.h> 48 #if __STDC__ 49 #include <stdarg.h> 50 #else 51 #include <varargs.h> 52 #endif 53 54 #ifdef HAVE_OS_PROTO_H 55 #include "os-proto.h" 56 #endif 57 58 #include "pcap-int.h" 59 60 #include "gencode.h" 61 62 #ifndef ETHERTYPE_REVARP 63 #define ETHERTYPE_REVARP 0x8035 64 #endif 65 #ifndef ETHERTYPE_MOPDL 66 #define ETHERTYPE_MOPDL 0x6001 67 #endif 68 #ifndef ETHERTYPE_MOPRC 69 #define ETHERTYPE_MOPRC 0x6002 70 #endif 71 #ifndef ETHERTYPE_DN 72 #define ETHERTYPE_DN 0x6003 73 #endif 74 #ifndef ETHERTYPE_LAT 75 #define ETHERTYPE_LAT 0x6004 76 #endif 77 78 #define JMP(c) ((c)|BPF_JMP|BPF_K) 79 80 /* Locals */ 81 static jmp_buf top_ctx; 82 static pcap_t *bpf_pcap; 83 84 /* XXX */ 85 #ifdef PCAP_FDDIPAD 86 int pcap_fddipad = PCAP_FDDIPAD; 87 #else 88 int pcap_fddipad; 89 #endif 90 91 /* VARARGS */ 92 __dead void 93 #if __STDC__ 94 bpf_error(const char *fmt, ...) 95 #else 96 bpf_error(fmt, va_alist) 97 const char *fmt; 98 va_dcl 99 #endif 100 { 101 va_list ap; 102 103 #if __STDC__ 104 va_start(ap, fmt); 105 #else 106 va_start(ap); 107 #endif 108 if (bpf_pcap != NULL) 109 (void)vsprintf(pcap_geterr(bpf_pcap), fmt, ap); 110 va_end(ap); 111 longjmp(top_ctx, 1); 112 /* NOTREACHED */ 113 } 114 115 static void init_linktype(int); 116 117 static int alloc_reg(void); 118 static void free_reg(int); 119 120 static struct block *root; 121 122 /* 123 * We divy out chunks of memory rather than call malloc each time so 124 * we don't have to worry about leaking memory. It's probably 125 * not a big deal if all this memory was wasted but it this ever 126 * goes into a library that would probably not be a good idea. 127 */ 128 #define NCHUNKS 16 129 #define CHUNK0SIZE 1024 130 struct chunk { 131 u_int n_left; 132 void *m; 133 }; 134 135 static struct chunk chunks[NCHUNKS]; 136 static int cur_chunk; 137 138 static void *newchunk(u_int); 139 static void freechunks(void); 140 static inline struct block *new_block(int); 141 static inline struct slist *new_stmt(int); 142 static struct block *gen_retblk(int); 143 static inline void syntax(void); 144 145 static void backpatch(struct block *, struct block *); 146 static void merge(struct block *, struct block *); 147 static struct block *gen_cmp(u_int, u_int, bpf_int32); 148 static struct block *gen_mcmp(u_int, u_int, bpf_int32, bpf_u_int32); 149 static struct block *gen_bcmp(u_int, u_int, u_char *); 150 static struct block *gen_uncond(int); 151 static inline struct block *gen_true(void); 152 static inline struct block *gen_false(void); 153 static struct block *gen_linktype(int); 154 static struct block *gen_hostop(bpf_u_int32, bpf_u_int32, int, int, u_int, u_int); 155 static struct block *gen_ehostop(u_char *, int); 156 static struct block *gen_fhostop(u_char *, int); 157 static struct block *gen_dnhostop(bpf_u_int32, int, u_int); 158 static struct block *gen_host(bpf_u_int32, bpf_u_int32, int, int); 159 static struct block *gen_gateway(u_char *, bpf_u_int32 **, int, int); 160 static struct block *gen_ipfrag(void); 161 static struct block *gen_portatom(int, bpf_int32); 162 struct block *gen_portop(int, int, int); 163 static struct block *gen_port(int, int, int); 164 static int lookup_proto(char *, int); 165 static struct block *gen_proto(int, int, int); 166 static bpf_u_int32 net_mask(bpf_u_int32 *); 167 static struct slist *xfer_to_x(struct arth *); 168 static struct slist *xfer_to_a(struct arth *); 169 static struct block *gen_len(int, int); 170 171 static void * 172 newchunk(n) 173 u_int n; 174 { 175 struct chunk *cp; 176 int k, size; 177 178 /* XXX Round up to nearest long. */ 179 n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1); 180 181 cp = &chunks[cur_chunk]; 182 if (n > cp->n_left) { 183 ++cp, k = ++cur_chunk; 184 if (k >= NCHUNKS) 185 bpf_error("out of memory"); 186 size = CHUNK0SIZE << k; 187 cp->m = (void *)malloc(size); 188 memset((char *)cp->m, 0, size); 189 cp->n_left = size; 190 if (n > size) 191 bpf_error("out of memory"); 192 } 193 cp->n_left -= n; 194 return (void *)((char *)cp->m + cp->n_left); 195 } 196 197 static void 198 freechunks() 199 { 200 int i; 201 202 cur_chunk = 0; 203 for (i = 0; i < NCHUNKS; ++i) 204 if (chunks[i].m != NULL) { 205 free(chunks[i].m); 206 chunks[i].m = NULL; 207 } 208 } 209 210 /* 211 * A strdup whose allocations are freed after code generation is over. 212 */ 213 char * 214 sdup(s) 215 char *s; 216 { 217 int n = strlen(s) + 1; 218 char *cp = newchunk(n); 219 strcpy(cp, s); 220 return (cp); 221 } 222 223 static inline struct block * 224 new_block(code) 225 int code; 226 { 227 struct block *p; 228 229 p = (struct block *)newchunk(sizeof(*p)); 230 p->s.code = code; 231 p->head = p; 232 233 return p; 234 } 235 236 static inline struct slist * 237 new_stmt(code) 238 int code; 239 { 240 struct slist *p; 241 242 p = (struct slist *)newchunk(sizeof(*p)); 243 p->s.code = code; 244 245 return p; 246 } 247 248 static struct block * 249 gen_retblk(v) 250 int v; 251 { 252 struct block *b = new_block(BPF_RET|BPF_K); 253 254 b->s.k = v; 255 return b; 256 } 257 258 static inline void 259 syntax() 260 { 261 bpf_error("syntax error in filter expression"); 262 } 263 264 static bpf_u_int32 netmask; 265 static int snaplen; 266 267 int 268 pcap_compile(pcap_t *p, struct bpf_program *program, 269 char *buf, int optimize, bpf_u_int32 mask) 270 { 271 extern int n_errors; 272 int len; 273 274 n_errors = 0; 275 root = NULL; 276 bpf_pcap = p; 277 if (setjmp(top_ctx)) { 278 freechunks(); 279 return (-1); 280 } 281 282 netmask = mask; 283 snaplen = pcap_snapshot(p); 284 285 lex_init(buf ? buf : ""); 286 init_linktype(pcap_datalink(p)); 287 (void)pcap_parse(); 288 289 if (n_errors) 290 syntax(); 291 292 if (root == NULL) 293 root = gen_retblk(snaplen); 294 295 if (optimize) { 296 bpf_optimize(&root); 297 if (root == NULL || 298 (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0)) 299 bpf_error("expression rejects all packets"); 300 } 301 program->bf_insns = icode_to_fcode(root, &len); 302 program->bf_len = len; 303 304 freechunks(); 305 return (0); 306 } 307 308 /* 309 * Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates 310 * which of the jt and jf fields has been resolved and which is a pointer 311 * back to another unresolved block (or nil). At least one of the fields 312 * in each block is already resolved. 313 */ 314 static void 315 backpatch(list, target) 316 struct block *list, *target; 317 { 318 struct block *next; 319 320 while (list) { 321 if (!list->sense) { 322 next = JT(list); 323 JT(list) = target; 324 } else { 325 next = JF(list); 326 JF(list) = target; 327 } 328 list = next; 329 } 330 } 331 332 /* 333 * Merge the lists in b0 and b1, using the 'sense' field to indicate 334 * which of jt and jf is the link. 335 */ 336 static void 337 merge(b0, b1) 338 struct block *b0, *b1; 339 { 340 register struct block **p = &b0; 341 342 /* Find end of list. */ 343 while (*p) 344 p = !((*p)->sense) ? &JT(*p) : &JF(*p); 345 346 /* Concatenate the lists. */ 347 *p = b1; 348 } 349 350 void 351 finish_parse(p) 352 struct block *p; 353 { 354 backpatch(p, gen_retblk(snaplen)); 355 p->sense = !p->sense; 356 backpatch(p, gen_retblk(0)); 357 root = p->head; 358 } 359 360 void 361 gen_and(b0, b1) 362 struct block *b0, *b1; 363 { 364 backpatch(b0, b1->head); 365 b0->sense = !b0->sense; 366 b1->sense = !b1->sense; 367 merge(b1, b0); 368 b1->sense = !b1->sense; 369 b1->head = b0->head; 370 } 371 372 void 373 gen_or(b0, b1) 374 struct block *b0, *b1; 375 { 376 b0->sense = !b0->sense; 377 backpatch(b0, b1->head); 378 b0->sense = !b0->sense; 379 merge(b1, b0); 380 b1->head = b0->head; 381 } 382 383 void 384 gen_not(b) 385 struct block *b; 386 { 387 b->sense = !b->sense; 388 } 389 390 static struct block * 391 gen_cmp(offset, size, v) 392 u_int offset, size; 393 bpf_int32 v; 394 { 395 struct slist *s; 396 struct block *b; 397 398 s = new_stmt(BPF_LD|BPF_ABS|size); 399 s->s.k = offset; 400 401 b = new_block(JMP(BPF_JEQ)); 402 b->stmts = s; 403 b->s.k = v; 404 405 return b; 406 } 407 408 static struct block * 409 gen_mcmp(offset, size, v, mask) 410 u_int offset, size; 411 bpf_int32 v; 412 bpf_u_int32 mask; 413 { 414 struct block *b = gen_cmp(offset, size, v); 415 struct slist *s; 416 417 if (mask != 0xffffffff) { 418 s = new_stmt(BPF_ALU|BPF_AND|BPF_K); 419 s->s.k = mask; 420 b->stmts->next = s; 421 } 422 return b; 423 } 424 425 static struct block * 426 gen_bcmp(offset, size, v) 427 u_int offset, size; 428 u_char *v; 429 { 430 struct block *b, *tmp; 431 432 b = NULL; 433 while (size >= 4) { 434 u_char *p = &v[size - 4]; 435 bpf_int32 w = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]; 436 tmp = gen_cmp(offset + size - 4, BPF_W, w); 437 if (b != NULL) 438 gen_and(b, tmp); 439 b = tmp; 440 size -= 4; 441 } 442 while (size >= 2) { 443 u_char *p = &v[size - 2]; 444 bpf_int32 w = (p[0] << 8) | p[1]; 445 tmp = gen_cmp(offset + size - 2, BPF_H, w); 446 if (b != NULL) 447 gen_and(b, tmp); 448 b = tmp; 449 size -= 2; 450 } 451 if (size > 0) { 452 tmp = gen_cmp(offset, BPF_B, (bpf_int32)v[0]); 453 if (b != NULL) 454 gen_and(b, tmp); 455 b = tmp; 456 } 457 return b; 458 } 459 460 /* 461 * Various code constructs need to know the layout of the data link 462 * layer. These variables give the necessary offsets. off_linktype 463 * is set to -1 for no encapsulation, in which case, IP is assumed. 464 */ 465 static u_int off_linktype; 466 static u_int off_nl; 467 static int linktype; 468 469 static void 470 init_linktype(type) 471 int type; 472 { 473 linktype = type; 474 475 switch (type) { 476 477 case DLT_EN10MB: 478 off_linktype = 12; 479 off_nl = 14; 480 return; 481 482 case DLT_SLIP: 483 /* 484 * SLIP doesn't have a link level type. The 16 byte 485 * header is hacked into our SLIP driver. 486 */ 487 off_linktype = -1; 488 off_nl = 16; 489 return; 490 491 case DLT_NULL: 492 off_linktype = -1; 493 off_nl = 0; 494 return; 495 496 case DLT_PPP: 497 off_linktype = 2; 498 off_nl = 4; 499 return; 500 501 case DLT_FDDI: 502 /* 503 * FDDI doesn't really have a link-level type field. 504 * We assume that SSAP = SNAP is being used and pick 505 * out the encapsulated Ethernet type. 506 */ 507 off_linktype = 19; 508 #ifdef PCAP_FDDIPAD 509 off_linktype += pcap_fddipad; 510 #endif 511 off_nl = 21; 512 #ifdef PCAP_FDDIPAD 513 off_nl += pcap_fddipad; 514 #endif 515 return; 516 517 case DLT_IEEE802: 518 off_linktype = 20; 519 off_nl = 22; 520 return; 521 522 case DLT_ATM_RFC1483: 523 /* 524 * assume routed, non-ISO PDUs 525 * (i.e., LLC = 0xAA-AA-03, OUT = 0x00-00-00) 526 */ 527 off_linktype = 6; 528 off_nl = 8; 529 return; 530 } 531 bpf_error("unknown data link type 0x%x", linktype); 532 /* NOTREACHED */ 533 } 534 535 static struct block * 536 gen_uncond(rsense) 537 int rsense; 538 { 539 struct block *b; 540 struct slist *s; 541 542 s = new_stmt(BPF_LD|BPF_IMM); 543 s->s.k = !rsense; 544 b = new_block(JMP(BPF_JEQ)); 545 b->stmts = s; 546 547 return b; 548 } 549 550 static inline struct block * 551 gen_true() 552 { 553 return gen_uncond(1); 554 } 555 556 static inline struct block * 557 gen_false() 558 { 559 return gen_uncond(0); 560 } 561 562 static struct block * 563 gen_linktype(proto) 564 int proto; 565 { 566 switch (linktype) { 567 case DLT_SLIP: 568 if (proto == ETHERTYPE_IP) 569 return gen_true(); 570 else 571 return gen_false(); 572 573 case DLT_PPP: 574 if (proto == ETHERTYPE_IP) 575 proto = 0x0021; /* XXX - need ppp.h defs */ 576 break; 577 578 case DLT_NULL: 579 /* XXX */ 580 if (proto == ETHERTYPE_IP) 581 return (gen_cmp(0, BPF_W, (bpf_int32)AF_INET)); 582 else 583 return gen_false(); 584 } 585 return gen_cmp(off_linktype, BPF_H, (bpf_int32)proto); 586 } 587 588 static struct block * 589 gen_hostop(addr, mask, dir, proto, src_off, dst_off) 590 bpf_u_int32 addr; 591 bpf_u_int32 mask; 592 int dir, proto; 593 u_int src_off, dst_off; 594 { 595 struct block *b0, *b1; 596 u_int offset; 597 598 switch (dir) { 599 600 case Q_SRC: 601 offset = src_off; 602 break; 603 604 case Q_DST: 605 offset = dst_off; 606 break; 607 608 case Q_AND: 609 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); 610 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); 611 gen_and(b0, b1); 612 return b1; 613 614 case Q_OR: 615 case Q_DEFAULT: 616 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); 617 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); 618 gen_or(b0, b1); 619 return b1; 620 621 default: 622 abort(); 623 } 624 b0 = gen_linktype(proto); 625 b1 = gen_mcmp(offset, BPF_W, (bpf_int32)addr, mask); 626 gen_and(b0, b1); 627 return b1; 628 } 629 630 static struct block * 631 gen_ehostop(eaddr, dir) 632 u_char *eaddr; 633 int dir; 634 { 635 struct block *b0, *b1; 636 637 switch (dir) { 638 case Q_SRC: 639 return gen_bcmp(6, 6, eaddr); 640 641 case Q_DST: 642 return gen_bcmp(0, 6, eaddr); 643 644 case Q_AND: 645 b0 = gen_ehostop(eaddr, Q_SRC); 646 b1 = gen_ehostop(eaddr, Q_DST); 647 gen_and(b0, b1); 648 return b1; 649 650 case Q_DEFAULT: 651 case Q_OR: 652 b0 = gen_ehostop(eaddr, Q_SRC); 653 b1 = gen_ehostop(eaddr, Q_DST); 654 gen_or(b0, b1); 655 return b1; 656 } 657 abort(); 658 /* NOTREACHED */ 659 } 660 661 /* 662 * Like gen_ehostop, but for DLT_FDDI 663 */ 664 static struct block * 665 gen_fhostop(eaddr, dir) 666 u_char *eaddr; 667 int dir; 668 { 669 struct block *b0, *b1; 670 671 switch (dir) { 672 case Q_SRC: 673 #ifdef PCAP_FDDIPAD 674 return gen_bcmp(6 + 1 + pcap_fddipad, 6, eaddr); 675 #else 676 return gen_bcmp(6 + 1, 6, eaddr); 677 #endif 678 679 case Q_DST: 680 #ifdef PCAP_FDDIPAD 681 return gen_bcmp(0 + 1 + pcap_fddipad, 6, eaddr); 682 #else 683 return gen_bcmp(0 + 1, 6, eaddr); 684 #endif 685 686 case Q_AND: 687 b0 = gen_fhostop(eaddr, Q_SRC); 688 b1 = gen_fhostop(eaddr, Q_DST); 689 gen_and(b0, b1); 690 return b1; 691 692 case Q_DEFAULT: 693 case Q_OR: 694 b0 = gen_fhostop(eaddr, Q_SRC); 695 b1 = gen_fhostop(eaddr, Q_DST); 696 gen_or(b0, b1); 697 return b1; 698 } 699 abort(); 700 /* NOTREACHED */ 701 } 702 703 /* 704 * This is quite tricky because there may be pad bytes in front of the 705 * DECNET header, and then there are two possible data packet formats that 706 * carry both src and dst addresses, plus 5 packet types in a format that 707 * carries only the src node, plus 2 types that use a different format and 708 * also carry just the src node. 709 * 710 * Yuck. 711 * 712 * Instead of doing those all right, we just look for data packets with 713 * 0 or 1 bytes of padding. If you want to look at other packets, that 714 * will require a lot more hacking. 715 * 716 * To add support for filtering on DECNET "areas" (network numbers) 717 * one would want to add a "mask" argument to this routine. That would 718 * make the filter even more inefficient, although one could be clever 719 * and not generate masking instructions if the mask is 0xFFFF. 720 */ 721 static struct block * 722 gen_dnhostop(addr, dir, base_off) 723 bpf_u_int32 addr; 724 int dir; 725 u_int base_off; 726 { 727 struct block *b0, *b1, *b2, *tmp; 728 u_int offset_lh; /* offset if long header is received */ 729 u_int offset_sh; /* offset if short header is received */ 730 731 switch (dir) { 732 733 case Q_DST: 734 offset_sh = 1; /* follows flags */ 735 offset_lh = 7; /* flgs,darea,dsubarea,HIORD */ 736 break; 737 738 case Q_SRC: 739 offset_sh = 3; /* follows flags, dstnode */ 740 offset_lh = 15; /* flgs,darea,dsubarea,did,sarea,ssub,HIORD */ 741 break; 742 743 case Q_AND: 744 /* Inefficient because we do our Calvinball dance twice */ 745 b0 = gen_dnhostop(addr, Q_SRC, base_off); 746 b1 = gen_dnhostop(addr, Q_DST, base_off); 747 gen_and(b0, b1); 748 return b1; 749 750 case Q_OR: 751 case Q_DEFAULT: 752 /* Inefficient because we do our Calvinball dance twice */ 753 b0 = gen_dnhostop(addr, Q_SRC, base_off); 754 b1 = gen_dnhostop(addr, Q_DST, base_off); 755 gen_or(b0, b1); 756 return b1; 757 758 default: 759 abort(); 760 } 761 b0 = gen_linktype(ETHERTYPE_DN); 762 /* Check for pad = 1, long header case */ 763 tmp = gen_mcmp(base_off + 2, BPF_H, 764 (bpf_int32)ntohs(0x0681), (bpf_int32)ntohs(0x07FF)); 765 b1 = gen_cmp(base_off + 2 + 1 + offset_lh, 766 BPF_H, (bpf_int32)ntohs(addr)); 767 gen_and(tmp, b1); 768 /* Check for pad = 0, long header case */ 769 tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x06, (bpf_int32)0x7); 770 b2 = gen_cmp(base_off + 2 + offset_lh, BPF_H, (bpf_int32)ntohs(addr)); 771 gen_and(tmp, b2); 772 gen_or(b2, b1); 773 /* Check for pad = 1, short header case */ 774 tmp = gen_mcmp(base_off + 2, BPF_H, 775 (bpf_int32)ntohs(0x0281), (bpf_int32)ntohs(0x07FF)); 776 b2 = gen_cmp(base_off + 2 + 1 + offset_sh, 777 BPF_H, (bpf_int32)ntohs(addr)); 778 gen_and(tmp, b2); 779 gen_or(b2, b1); 780 /* Check for pad = 0, short header case */ 781 tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x02, (bpf_int32)0x7); 782 b2 = gen_cmp(base_off + 2 + offset_sh, BPF_H, (bpf_int32)ntohs(addr)); 783 gen_and(tmp, b2); 784 gen_or(b2, b1); 785 786 /* Combine with test for linktype */ 787 gen_and(b0, b1); 788 return b1; 789 } 790 791 static struct block * 792 gen_host(addr, mask, proto, dir) 793 bpf_u_int32 addr; 794 bpf_u_int32 mask; 795 int proto; 796 int dir; 797 { 798 struct block *b0, *b1; 799 800 switch (proto) { 801 802 case Q_DEFAULT: 803 b0 = gen_host(addr, mask, Q_IP, dir); 804 b1 = gen_host(addr, mask, Q_ARP, dir); 805 gen_or(b0, b1); 806 b0 = gen_host(addr, mask, Q_RARP, dir); 807 gen_or(b1, b0); 808 return b0; 809 810 case Q_IP: 811 return gen_hostop(addr, mask, dir, ETHERTYPE_IP, 812 off_nl + 12, off_nl + 16); 813 814 case Q_RARP: 815 return gen_hostop(addr, mask, dir, ETHERTYPE_REVARP, 816 off_nl + 14, off_nl + 24); 817 818 case Q_ARP: 819 return gen_hostop(addr, mask, dir, ETHERTYPE_ARP, 820 off_nl + 14, off_nl + 24); 821 822 case Q_TCP: 823 bpf_error("'tcp' modifier applied to host"); 824 825 case Q_UDP: 826 bpf_error("'udp' modifier applied to host"); 827 828 case Q_ICMP: 829 bpf_error("'icmp' modifier applied to host"); 830 831 case Q_IGMP: 832 bpf_error("'igmp' modifier applied to host"); 833 834 case Q_DECNET: 835 return gen_dnhostop(addr, dir, off_nl); 836 837 case Q_LAT: 838 bpf_error("LAT host filtering not implemented"); 839 840 case Q_MOPDL: 841 bpf_error("MOPDL host filtering not implemented"); 842 843 case Q_MOPRC: 844 bpf_error("MOPRC host filtering not implemented"); 845 846 default: 847 abort(); 848 } 849 /* NOTREACHED */ 850 } 851 852 static struct block * 853 gen_gateway(eaddr, alist, proto, dir) 854 u_char *eaddr; 855 bpf_u_int32 **alist; 856 int proto; 857 int dir; 858 { 859 struct block *b0, *b1, *tmp; 860 861 if (dir != 0) 862 bpf_error("direction applied to 'gateway'"); 863 864 switch (proto) { 865 case Q_DEFAULT: 866 case Q_IP: 867 case Q_ARP: 868 case Q_RARP: 869 if (linktype == DLT_EN10MB) 870 b0 = gen_ehostop(eaddr, Q_OR); 871 else if (linktype == DLT_FDDI) 872 b0 = gen_fhostop(eaddr, Q_OR); 873 else 874 bpf_error( 875 "'gateway' supported only on ethernet or FDDI"); 876 877 b1 = gen_host(**alist++, 0xffffffffL, proto, Q_OR); 878 while (*alist) { 879 tmp = gen_host(**alist++, 0xffffffffL, proto, Q_OR); 880 gen_or(b1, tmp); 881 b1 = tmp; 882 } 883 gen_not(b1); 884 gen_and(b0, b1); 885 return b1; 886 } 887 bpf_error("illegal modifier of 'gateway'"); 888 /* NOTREACHED */ 889 } 890 891 struct block * 892 gen_proto_abbrev(proto) 893 int proto; 894 { 895 struct block *b0, *b1; 896 897 switch (proto) { 898 899 case Q_TCP: 900 b0 = gen_linktype(ETHERTYPE_IP); 901 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_TCP); 902 gen_and(b0, b1); 903 break; 904 905 case Q_UDP: 906 b0 = gen_linktype(ETHERTYPE_IP); 907 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_UDP); 908 gen_and(b0, b1); 909 break; 910 911 case Q_ICMP: 912 b0 = gen_linktype(ETHERTYPE_IP); 913 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_ICMP); 914 gen_and(b0, b1); 915 break; 916 917 case Q_IGMP: 918 b0 = gen_linktype(ETHERTYPE_IP); 919 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)2); 920 gen_and(b0, b1); 921 break; 922 923 case Q_IP: 924 b1 = gen_linktype(ETHERTYPE_IP); 925 break; 926 927 case Q_ARP: 928 b1 = gen_linktype(ETHERTYPE_ARP); 929 break; 930 931 case Q_RARP: 932 b1 = gen_linktype(ETHERTYPE_REVARP); 933 break; 934 935 case Q_LINK: 936 bpf_error("link layer applied in wrong context"); 937 938 case Q_DECNET: 939 b1 = gen_linktype(ETHERTYPE_DN); 940 break; 941 942 case Q_LAT: 943 b1 = gen_linktype(ETHERTYPE_LAT); 944 break; 945 946 case Q_MOPDL: 947 b1 = gen_linktype(ETHERTYPE_MOPDL); 948 break; 949 950 case Q_MOPRC: 951 b1 = gen_linktype(ETHERTYPE_MOPRC); 952 break; 953 954 default: 955 abort(); 956 } 957 return b1; 958 } 959 960 static struct block * 961 gen_ipfrag() 962 { 963 struct slist *s; 964 struct block *b; 965 966 /* not ip frag */ 967 s = new_stmt(BPF_LD|BPF_H|BPF_ABS); 968 s->s.k = off_nl + 6; 969 b = new_block(JMP(BPF_JSET)); 970 b->s.k = 0x1fff; 971 b->stmts = s; 972 gen_not(b); 973 974 return b; 975 } 976 977 static struct block * 978 gen_portatom(off, v) 979 int off; 980 bpf_int32 v; 981 { 982 struct slist *s; 983 struct block *b; 984 985 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); 986 s->s.k = off_nl; 987 988 s->next = new_stmt(BPF_LD|BPF_IND|BPF_H); 989 s->next->s.k = off_nl + off; 990 991 b = new_block(JMP(BPF_JEQ)); 992 b->stmts = s; 993 b->s.k = v; 994 995 return b; 996 } 997 998 struct block * 999 gen_portop(port, proto, dir) 1000 int port, proto, dir; 1001 { 1002 struct block *b0, *b1, *tmp; 1003 1004 /* ip proto 'proto' */ 1005 tmp = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)proto); 1006 b0 = gen_ipfrag(); 1007 gen_and(tmp, b0); 1008 1009 switch (dir) { 1010 case Q_SRC: 1011 b1 = gen_portatom(0, (bpf_int32)port); 1012 break; 1013 1014 case Q_DST: 1015 b1 = gen_portatom(2, (bpf_int32)port); 1016 break; 1017 1018 case Q_OR: 1019 case Q_DEFAULT: 1020 tmp = gen_portatom(0, (bpf_int32)port); 1021 b1 = gen_portatom(2, (bpf_int32)port); 1022 gen_or(tmp, b1); 1023 break; 1024 1025 case Q_AND: 1026 tmp = gen_portatom(0, (bpf_int32)port); 1027 b1 = gen_portatom(2, (bpf_int32)port); 1028 gen_and(tmp, b1); 1029 break; 1030 1031 default: 1032 abort(); 1033 } 1034 gen_and(b0, b1); 1035 1036 return b1; 1037 } 1038 1039 static struct block * 1040 gen_port(port, ip_proto, dir) 1041 int port; 1042 int ip_proto; 1043 int dir; 1044 { 1045 struct block *b0, *b1, *tmp; 1046 1047 /* ether proto ip */ 1048 b0 = gen_linktype(ETHERTYPE_IP); 1049 1050 switch (ip_proto) { 1051 case IPPROTO_UDP: 1052 case IPPROTO_TCP: 1053 b1 = gen_portop(port, ip_proto, dir); 1054 break; 1055 1056 case PROTO_UNDEF: 1057 tmp = gen_portop(port, IPPROTO_TCP, dir); 1058 b1 = gen_portop(port, IPPROTO_UDP, dir); 1059 gen_or(tmp, b1); 1060 break; 1061 1062 default: 1063 abort(); 1064 } 1065 gen_and(b0, b1); 1066 return b1; 1067 } 1068 1069 static int 1070 lookup_proto(name, proto) 1071 char *name; 1072 int proto; 1073 { 1074 int v; 1075 1076 switch (proto) { 1077 case Q_DEFAULT: 1078 case Q_IP: 1079 v = pcap_nametoproto(name); 1080 if (v == PROTO_UNDEF) 1081 bpf_error("unknown ip proto '%s'", name); 1082 break; 1083 1084 case Q_LINK: 1085 /* XXX should look up h/w protocol type based on linktype */ 1086 v = pcap_nametoeproto(name); 1087 if (v == PROTO_UNDEF) 1088 bpf_error("unknown ether proto '%s'", name); 1089 break; 1090 1091 default: 1092 v = PROTO_UNDEF; 1093 break; 1094 } 1095 return v; 1096 } 1097 1098 static struct block * 1099 gen_proto(v, proto, dir) 1100 int v; 1101 int proto; 1102 int dir; 1103 { 1104 struct block *b0, *b1; 1105 1106 if (dir != Q_DEFAULT) 1107 bpf_error("direction applied to 'proto'"); 1108 1109 switch (proto) { 1110 case Q_DEFAULT: 1111 case Q_IP: 1112 b0 = gen_linktype(ETHERTYPE_IP); 1113 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)v); 1114 gen_and(b0, b1); 1115 return b1; 1116 1117 case Q_ARP: 1118 bpf_error("arp does not encapsulate another protocol"); 1119 /* NOTREACHED */ 1120 1121 case Q_RARP: 1122 bpf_error("rarp does not encapsulate another protocol"); 1123 /* NOTREACHED */ 1124 1125 case Q_DECNET: 1126 bpf_error("decnet encapsulation is not specifiable"); 1127 /* NOTREACHED */ 1128 1129 case Q_LAT: 1130 bpf_error("lat does not encapsulate another protocol"); 1131 /* NOTREACHED */ 1132 1133 case Q_MOPRC: 1134 bpf_error("moprc does not encapsulate another protocol"); 1135 /* NOTREACHED */ 1136 1137 case Q_MOPDL: 1138 bpf_error("mopdl does not encapsulate another protocol"); 1139 /* NOTREACHED */ 1140 1141 case Q_LINK: 1142 return gen_linktype(v); 1143 1144 case Q_UDP: 1145 bpf_error("'udp proto' is bogus"); 1146 /* NOTREACHED */ 1147 1148 case Q_TCP: 1149 bpf_error("'tcp proto' is bogus"); 1150 /* NOTREACHED */ 1151 1152 case Q_ICMP: 1153 bpf_error("'icmp proto' is bogus"); 1154 /* NOTREACHED */ 1155 1156 case Q_IGMP: 1157 bpf_error("'igmp proto' is bogus"); 1158 /* NOTREACHED */ 1159 1160 default: 1161 abort(); 1162 /* NOTREACHED */ 1163 } 1164 /* NOTREACHED */ 1165 } 1166 1167 /* 1168 * Left justify 'addr' and return its resulting network mask. 1169 */ 1170 static bpf_u_int32 1171 net_mask(addr) 1172 bpf_u_int32 *addr; 1173 { 1174 register bpf_u_int32 m = 0xffffffff; 1175 1176 if (*addr) 1177 while ((*addr & 0xff000000) == 0) 1178 *addr <<= 8, m <<= 8; 1179 1180 return m; 1181 } 1182 1183 struct block * 1184 gen_scode(name, q) 1185 char *name; 1186 struct qual q; 1187 { 1188 int proto = q.proto; 1189 int dir = q.dir; 1190 u_char *eaddr; 1191 bpf_u_int32 mask, addr, **alist; 1192 struct block *b, *tmp; 1193 int port, real_proto; 1194 1195 switch (q.addr) { 1196 1197 case Q_NET: 1198 addr = pcap_nametonetaddr(name); 1199 if (addr == 0) 1200 bpf_error("unknown network '%s'", name); 1201 mask = net_mask(&addr); 1202 return gen_host(addr, mask, proto, dir); 1203 1204 case Q_DEFAULT: 1205 case Q_HOST: 1206 if (proto == Q_LINK) { 1207 switch (linktype) { 1208 1209 case DLT_EN10MB: 1210 eaddr = pcap_ether_hostton(name); 1211 if (eaddr == NULL) 1212 bpf_error( 1213 "unknown ether host '%s'", name); 1214 return gen_ehostop(eaddr, dir); 1215 1216 case DLT_FDDI: 1217 eaddr = pcap_ether_hostton(name); 1218 if (eaddr == NULL) 1219 bpf_error( 1220 "unknown FDDI host '%s'", name); 1221 return gen_fhostop(eaddr, dir); 1222 1223 default: 1224 bpf_error( 1225 "only ethernet/FDDI supports link-level host name"); 1226 break; 1227 } 1228 } else if (proto == Q_DECNET) { 1229 unsigned short dn_addr = __pcap_nametodnaddr(name); 1230 /* 1231 * I don't think DECNET hosts can be multihomed, so 1232 * there is no need to build up a list of addresses 1233 */ 1234 return (gen_host(dn_addr, 0, proto, dir)); 1235 } else { 1236 alist = pcap_nametoaddr(name); 1237 if (alist == NULL || *alist == NULL) 1238 bpf_error("unknown host '%s'", name); 1239 b = gen_host(**alist++, 0xffffffffL, proto, dir); 1240 while (*alist) { 1241 tmp = gen_host(**alist++, 0xffffffffL, 1242 proto, dir); 1243 gen_or(b, tmp); 1244 b = tmp; 1245 } 1246 return b; 1247 } 1248 1249 case Q_PORT: 1250 if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP) 1251 bpf_error("illegal qualifier of 'port'"); 1252 if (pcap_nametoport(name, &port, &real_proto) == 0) 1253 bpf_error("unknown port '%s'", name); 1254 if (proto == Q_UDP) { 1255 if (real_proto == IPPROTO_TCP) 1256 bpf_error("port '%s' is tcp", name); 1257 else 1258 /* override PROTO_UNDEF */ 1259 real_proto = IPPROTO_UDP; 1260 } 1261 if (proto == Q_TCP) { 1262 if (real_proto == IPPROTO_UDP) 1263 bpf_error("port '%s' is udp", name); 1264 else 1265 /* override PROTO_UNDEF */ 1266 real_proto = IPPROTO_TCP; 1267 } 1268 return gen_port(port, real_proto, dir); 1269 1270 case Q_GATEWAY: 1271 eaddr = pcap_ether_hostton(name); 1272 if (eaddr == NULL) 1273 bpf_error("unknown ether host: %s", name); 1274 1275 alist = pcap_nametoaddr(name); 1276 if (alist == NULL || *alist == NULL) 1277 bpf_error("unknown host '%s'", name); 1278 return gen_gateway(eaddr, alist, proto, dir); 1279 1280 case Q_PROTO: 1281 real_proto = lookup_proto(name, proto); 1282 if (real_proto >= 0) 1283 return gen_proto(real_proto, proto, dir); 1284 else 1285 bpf_error("unknown protocol: %s", name); 1286 1287 case Q_UNDEF: 1288 syntax(); 1289 /* NOTREACHED */ 1290 } 1291 abort(); 1292 /* NOTREACHED */ 1293 } 1294 1295 struct block * 1296 gen_ncode(v, q) 1297 bpf_u_int32 v; 1298 struct qual q; 1299 { 1300 bpf_u_int32 mask; 1301 int proto = q.proto; 1302 int dir = q.dir; 1303 1304 switch (q.addr) { 1305 1306 case Q_DEFAULT: 1307 case Q_HOST: 1308 case Q_NET: 1309 if (proto == Q_DECNET) 1310 return gen_host(v, 0, proto, dir); 1311 else if (proto == Q_LINK) { 1312 bpf_error("illegal link layer address"); 1313 } else { 1314 mask = net_mask(&v); 1315 return gen_host(v, mask, proto, dir); 1316 } 1317 1318 case Q_PORT: 1319 if (proto == Q_UDP) 1320 proto = IPPROTO_UDP; 1321 else if (proto == Q_TCP) 1322 proto = IPPROTO_TCP; 1323 else if (proto == Q_DEFAULT) 1324 proto = PROTO_UNDEF; 1325 else 1326 bpf_error("illegal qualifier of 'port'"); 1327 1328 return gen_port((int)v, proto, dir); 1329 1330 case Q_GATEWAY: 1331 bpf_error("'gateway' requires a name"); 1332 /* NOTREACHED */ 1333 1334 case Q_PROTO: 1335 return gen_proto((int)v, proto, dir); 1336 1337 case Q_UNDEF: 1338 syntax(); 1339 /* NOTREACHED */ 1340 1341 default: 1342 abort(); 1343 /* NOTREACHED */ 1344 } 1345 /* NOTREACHED */ 1346 } 1347 1348 struct block * 1349 gen_ecode(eaddr, q) 1350 u_char *eaddr; 1351 struct qual q; 1352 { 1353 if ((q.addr == Q_HOST || q.addr == Q_DEFAULT) && q.proto == Q_LINK) { 1354 if (linktype == DLT_EN10MB) 1355 return gen_ehostop(eaddr, (int)q.dir); 1356 if (linktype == DLT_FDDI) 1357 return gen_fhostop(eaddr, (int)q.dir); 1358 } 1359 bpf_error("ethernet address used in non-ether expression"); 1360 /* NOTREACHED */ 1361 } 1362 1363 void 1364 sappend(s0, s1) 1365 struct slist *s0, *s1; 1366 { 1367 /* 1368 * This is definitely not the best way to do this, but the 1369 * lists will rarely get long. 1370 */ 1371 while (s0->next) 1372 s0 = s0->next; 1373 s0->next = s1; 1374 } 1375 1376 static struct slist * 1377 xfer_to_x(a) 1378 struct arth *a; 1379 { 1380 struct slist *s; 1381 1382 s = new_stmt(BPF_LDX|BPF_MEM); 1383 s->s.k = a->regno; 1384 return s; 1385 } 1386 1387 static struct slist * 1388 xfer_to_a(a) 1389 struct arth *a; 1390 { 1391 struct slist *s; 1392 1393 s = new_stmt(BPF_LD|BPF_MEM); 1394 s->s.k = a->regno; 1395 return s; 1396 } 1397 1398 struct arth * 1399 gen_load(proto, index, size) 1400 int proto; 1401 struct arth *index; 1402 int size; 1403 { 1404 struct slist *s, *tmp; 1405 struct block *b; 1406 int regno = alloc_reg(); 1407 1408 free_reg(index->regno); 1409 switch (size) { 1410 1411 default: 1412 bpf_error("data size must be 1, 2, or 4"); 1413 1414 case 1: 1415 size = BPF_B; 1416 break; 1417 1418 case 2: 1419 size = BPF_H; 1420 break; 1421 1422 case 4: 1423 size = BPF_W; 1424 break; 1425 } 1426 switch (proto) { 1427 default: 1428 bpf_error("unsupported index operation"); 1429 1430 case Q_LINK: 1431 s = xfer_to_x(index); 1432 tmp = new_stmt(BPF_LD|BPF_IND|size); 1433 sappend(s, tmp); 1434 sappend(index->s, s); 1435 break; 1436 1437 case Q_IP: 1438 case Q_ARP: 1439 case Q_RARP: 1440 case Q_DECNET: 1441 case Q_LAT: 1442 case Q_MOPRC: 1443 case Q_MOPDL: 1444 /* XXX Note that we assume a fixed link link header here. */ 1445 s = xfer_to_x(index); 1446 tmp = new_stmt(BPF_LD|BPF_IND|size); 1447 tmp->s.k = off_nl; 1448 sappend(s, tmp); 1449 sappend(index->s, s); 1450 1451 b = gen_proto_abbrev(proto); 1452 if (index->b) 1453 gen_and(index->b, b); 1454 index->b = b; 1455 break; 1456 1457 case Q_TCP: 1458 case Q_UDP: 1459 case Q_ICMP: 1460 case Q_IGMP: 1461 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); 1462 s->s.k = off_nl; 1463 sappend(s, xfer_to_a(index)); 1464 sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X)); 1465 sappend(s, new_stmt(BPF_MISC|BPF_TAX)); 1466 sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size)); 1467 tmp->s.k = off_nl; 1468 sappend(index->s, s); 1469 1470 gen_and(gen_proto_abbrev(proto), b = gen_ipfrag()); 1471 if (index->b) 1472 gen_and(index->b, b); 1473 index->b = b; 1474 break; 1475 } 1476 index->regno = regno; 1477 s = new_stmt(BPF_ST); 1478 s->s.k = regno; 1479 sappend(index->s, s); 1480 1481 return index; 1482 } 1483 1484 struct block * 1485 gen_relation(code, a0, a1, reversed) 1486 int code; 1487 struct arth *a0, *a1; 1488 int reversed; 1489 { 1490 struct slist *s0, *s1, *s2; 1491 struct block *b, *tmp; 1492 1493 s0 = xfer_to_x(a1); 1494 s1 = xfer_to_a(a0); 1495 s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X); 1496 b = new_block(JMP(code)); 1497 if (code == BPF_JGT || code == BPF_JGE) { 1498 reversed = !reversed; 1499 b->s.k = 0x80000000; 1500 } 1501 if (reversed) 1502 gen_not(b); 1503 1504 sappend(s1, s2); 1505 sappend(s0, s1); 1506 sappend(a1->s, s0); 1507 sappend(a0->s, a1->s); 1508 1509 b->stmts = a0->s; 1510 1511 free_reg(a0->regno); 1512 free_reg(a1->regno); 1513 1514 /* 'and' together protocol checks */ 1515 if (a0->b) { 1516 if (a1->b) { 1517 gen_and(a0->b, tmp = a1->b); 1518 } 1519 else 1520 tmp = a0->b; 1521 } else 1522 tmp = a1->b; 1523 1524 if (tmp) 1525 gen_and(tmp, b); 1526 1527 return b; 1528 } 1529 1530 struct arth * 1531 gen_loadlen() 1532 { 1533 int regno = alloc_reg(); 1534 struct arth *a = (struct arth *)newchunk(sizeof(*a)); 1535 struct slist *s; 1536 1537 s = new_stmt(BPF_LD|BPF_LEN); 1538 s->next = new_stmt(BPF_ST); 1539 s->next->s.k = regno; 1540 a->s = s; 1541 a->regno = regno; 1542 1543 return a; 1544 } 1545 1546 struct arth * 1547 gen_loadi(val) 1548 int val; 1549 { 1550 struct arth *a; 1551 struct slist *s; 1552 int reg; 1553 1554 a = (struct arth *)newchunk(sizeof(*a)); 1555 1556 reg = alloc_reg(); 1557 1558 s = new_stmt(BPF_LD|BPF_IMM); 1559 s->s.k = val; 1560 s->next = new_stmt(BPF_ST); 1561 s->next->s.k = reg; 1562 a->s = s; 1563 a->regno = reg; 1564 1565 return a; 1566 } 1567 1568 struct arth * 1569 gen_neg(a) 1570 struct arth *a; 1571 { 1572 struct slist *s; 1573 1574 s = xfer_to_a(a); 1575 sappend(a->s, s); 1576 s = new_stmt(BPF_ALU|BPF_NEG); 1577 s->s.k = 0; 1578 sappend(a->s, s); 1579 s = new_stmt(BPF_ST); 1580 s->s.k = a->regno; 1581 sappend(a->s, s); 1582 1583 return a; 1584 } 1585 1586 struct arth * 1587 gen_arth(code, a0, a1) 1588 int code; 1589 struct arth *a0, *a1; 1590 { 1591 struct slist *s0, *s1, *s2; 1592 1593 s0 = xfer_to_x(a1); 1594 s1 = xfer_to_a(a0); 1595 s2 = new_stmt(BPF_ALU|BPF_X|code); 1596 1597 sappend(s1, s2); 1598 sappend(s0, s1); 1599 sappend(a1->s, s0); 1600 sappend(a0->s, a1->s); 1601 1602 free_reg(a1->regno); 1603 1604 s0 = new_stmt(BPF_ST); 1605 a0->regno = s0->s.k = alloc_reg(); 1606 sappend(a0->s, s0); 1607 1608 return a0; 1609 } 1610 1611 /* 1612 * Here we handle simple allocation of the scratch registers. 1613 * If too many registers are alloc'd, the allocator punts. 1614 */ 1615 static int regused[BPF_MEMWORDS]; 1616 static int curreg; 1617 1618 /* 1619 * Return the next free register. 1620 */ 1621 static int 1622 alloc_reg() 1623 { 1624 int n = BPF_MEMWORDS; 1625 1626 while (--n >= 0) { 1627 if (regused[curreg]) 1628 curreg = (curreg + 1) % BPF_MEMWORDS; 1629 else { 1630 regused[curreg] = 1; 1631 return curreg; 1632 } 1633 } 1634 bpf_error("too many registers needed to evaluate expression"); 1635 /* NOTREACHED */ 1636 } 1637 1638 /* 1639 * Return a register to the table so it can 1640 * be used later. 1641 */ 1642 static void 1643 free_reg(n) 1644 int n; 1645 { 1646 regused[n] = 0; 1647 } 1648 1649 static struct block * 1650 gen_len(jmp, n) 1651 int jmp, n; 1652 { 1653 struct slist *s; 1654 struct block *b; 1655 1656 s = new_stmt(BPF_LD|BPF_LEN); 1657 b = new_block(JMP(jmp)); 1658 b->stmts = s; 1659 b->s.k = n; 1660 1661 return b; 1662 } 1663 1664 struct block * 1665 gen_greater(n) 1666 int n; 1667 { 1668 return gen_len(BPF_JGE, n); 1669 } 1670 1671 struct block * 1672 gen_less(n) 1673 int n; 1674 { 1675 struct block *b; 1676 1677 b = gen_len(BPF_JGT, n); 1678 gen_not(b); 1679 1680 return b; 1681 } 1682 1683 struct block * 1684 gen_byteop(op, idx, val) 1685 int op, idx, val; 1686 { 1687 struct block *b; 1688 struct slist *s; 1689 1690 switch (op) { 1691 default: 1692 abort(); 1693 1694 case '=': 1695 return gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1696 1697 case '<': 1698 b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1699 b->s.code = JMP(BPF_JGE); 1700 gen_not(b); 1701 return b; 1702 1703 case '>': 1704 b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1705 b->s.code = JMP(BPF_JGT); 1706 return b; 1707 1708 case '|': 1709 s = new_stmt(BPF_ALU|BPF_OR|BPF_K); 1710 break; 1711 1712 case '&': 1713 s = new_stmt(BPF_ALU|BPF_AND|BPF_K); 1714 break; 1715 } 1716 s->s.k = val; 1717 b = new_block(JMP(BPF_JEQ)); 1718 b->stmts = s; 1719 gen_not(b); 1720 1721 return b; 1722 } 1723 1724 struct block * 1725 gen_broadcast(proto) 1726 int proto; 1727 { 1728 bpf_u_int32 hostmask; 1729 struct block *b0, *b1, *b2; 1730 static u_char ebroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; 1731 1732 switch (proto) { 1733 1734 case Q_DEFAULT: 1735 case Q_LINK: 1736 if (linktype == DLT_EN10MB) 1737 return gen_ehostop(ebroadcast, Q_DST); 1738 if (linktype == DLT_FDDI) 1739 return gen_fhostop(ebroadcast, Q_DST); 1740 bpf_error("not a broadcast link"); 1741 break; 1742 1743 case Q_IP: 1744 b0 = gen_linktype(ETHERTYPE_IP); 1745 hostmask = ~netmask; 1746 b1 = gen_mcmp(off_nl + 16, BPF_W, (bpf_int32)0, hostmask); 1747 b2 = gen_mcmp(off_nl + 16, BPF_W, 1748 (bpf_int32)(~0 & hostmask), hostmask); 1749 gen_or(b1, b2); 1750 gen_and(b0, b2); 1751 return b2; 1752 } 1753 bpf_error("only ether/ip broadcast filters supported"); 1754 } 1755 1756 struct block * 1757 gen_multicast(proto) 1758 int proto; 1759 { 1760 register struct block *b0, *b1; 1761 register struct slist *s; 1762 1763 switch (proto) { 1764 1765 case Q_DEFAULT: 1766 case Q_LINK: 1767 if (linktype == DLT_EN10MB) { 1768 /* ether[0] & 1 != 0 */ 1769 s = new_stmt(BPF_LD|BPF_B|BPF_ABS); 1770 s->s.k = 0; 1771 b0 = new_block(JMP(BPF_JSET)); 1772 b0->s.k = 1; 1773 b0->stmts = s; 1774 return b0; 1775 } 1776 1777 if (linktype == DLT_FDDI) { 1778 /* XXX TEST THIS: MIGHT NOT PORT PROPERLY XXX */ 1779 /* fddi[1] & 1 != 0 */ 1780 s = new_stmt(BPF_LD|BPF_B|BPF_ABS); 1781 s->s.k = 1; 1782 b0 = new_block(JMP(BPF_JSET)); 1783 b0->s.k = 1; 1784 b0->stmts = s; 1785 return b0; 1786 } 1787 /* Link not known to support multicasts */ 1788 break; 1789 1790 case Q_IP: 1791 b0 = gen_linktype(ETHERTYPE_IP); 1792 b1 = gen_cmp(off_nl + 16, BPF_B, (bpf_int32)224); 1793 b1->s.code = JMP(BPF_JGE); 1794 gen_and(b0, b1); 1795 return b1; 1796 } 1797 bpf_error("only IP multicast filters supported on ethernet/FDDI"); 1798 } 1799 1800 /* 1801 * generate command for inbound/outbound. It's here so we can 1802 * make it link-type specific. 'dir' = 0 implies "inbound", 1803 * = 1 implies "outbound". 1804 */ 1805 struct block * 1806 gen_inbound(dir) 1807 int dir; 1808 { 1809 register struct block *b0; 1810 1811 b0 = gen_relation(BPF_JEQ, 1812 gen_load(Q_LINK, gen_loadi(0), 1), 1813 gen_loadi(0), 1814 dir); 1815 return (b0); 1816 } 1817