1 /* $OpenBSD: gencode.c,v 1.11 1999/07/20 04:49:54 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998 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 const char rcsid[] = 25 "@(#) $Header: /home/cvs/src/lib/libpcap/gencode.c,v 1.11 1999/07/20 04:49:54 deraadt Exp $ (LBL)"; 26 #endif 27 28 #include <sys/types.h> 29 #include <sys/socket.h> 30 #include <sys/time.h> 31 32 #ifdef __STDC__ 33 struct mbuf; 34 struct rtentry; 35 #endif 36 37 #include <net/if.h> 38 39 #include <netinet/in.h> 40 #include <netinet/if_ether.h> 41 42 #include <stdlib.h> 43 #include <memory.h> 44 #include <setjmp.h> 45 #ifdef __STDC__ 46 #include <stdarg.h> 47 #else 48 #include <varargs.h> 49 #endif 50 51 #include "pcap-int.h" 52 53 #include "ethertype.h" 54 #include "gencode.h" 55 #include "ppp.h" 56 #include <pcap-namedb.h> 57 58 #ifdef HAVE_OS_PROTO_H 59 #include "os-proto.h" 60 #endif 61 62 #define JMP(c) ((c)|BPF_JMP|BPF_K) 63 64 /* Locals */ 65 static jmp_buf top_ctx; 66 static pcap_t *bpf_pcap; 67 68 /* XXX */ 69 #ifdef PCAP_FDDIPAD 70 int pcap_fddipad = PCAP_FDDIPAD; 71 #else 72 int pcap_fddipad; 73 #endif 74 75 /* VARARGS */ 76 __dead void 77 #ifdef __STDC__ 78 bpf_error(const char *fmt, ...) 79 #else 80 bpf_error(fmt, va_alist) 81 const char *fmt; 82 va_dcl 83 #endif 84 { 85 va_list ap; 86 87 #ifdef __STDC__ 88 va_start(ap, fmt); 89 #else 90 va_start(ap); 91 #endif 92 if (bpf_pcap != NULL) 93 (void)vsnprintf(pcap_geterr(bpf_pcap), PCAP_ERRBUF_SIZE, 94 fmt, ap); 95 va_end(ap); 96 longjmp(top_ctx, 1); 97 /* NOTREACHED */ 98 } 99 100 static void init_linktype(int); 101 102 static int alloc_reg(void); 103 static void free_reg(int); 104 105 static struct block *root; 106 107 /* 108 * We divy out chunks of memory rather than call malloc each time so 109 * we don't have to worry about leaking memory. It's probably 110 * not a big deal if all this memory was wasted but it this ever 111 * goes into a library that would probably not be a good idea. 112 */ 113 #define NCHUNKS 16 114 #define CHUNK0SIZE 1024 115 struct chunk { 116 u_int n_left; 117 void *m; 118 }; 119 120 static struct chunk chunks[NCHUNKS]; 121 static int cur_chunk; 122 123 static void *newchunk(u_int); 124 static void freechunks(void); 125 static __inline struct block *new_block(int); 126 static __inline struct slist *new_stmt(int); 127 static struct block *gen_retblk(int); 128 static __inline void syntax(void); 129 130 static void backpatch(struct block *, struct block *); 131 static void merge(struct block *, struct block *); 132 static struct block *gen_cmp(u_int, u_int, bpf_int32); 133 static struct block *gen_mcmp(u_int, u_int, bpf_int32, bpf_u_int32); 134 static struct block *gen_bcmp(u_int, u_int, const u_char *); 135 static struct block *gen_uncond(int); 136 static __inline struct block *gen_true(void); 137 static __inline struct block *gen_false(void); 138 static struct block *gen_linktype(int); 139 static struct block *gen_hostop(bpf_u_int32, bpf_u_int32, int, int, u_int, u_int); 140 static struct block *gen_ehostop(const u_char *, int); 141 static struct block *gen_fhostop(const u_char *, int); 142 static struct block *gen_dnhostop(bpf_u_int32, int, u_int); 143 static struct block *gen_host(bpf_u_int32, bpf_u_int32, int, int); 144 static struct block *gen_gateway(const u_char *, bpf_u_int32 **, int, int); 145 static struct block *gen_ipfrag(void); 146 static struct block *gen_portatom(int, bpf_int32); 147 struct block *gen_portop(int, int, int); 148 static struct block *gen_port(int, int, int); 149 static int lookup_proto(const char *, int); 150 static struct block *gen_proto(int, int, int); 151 static struct slist *xfer_to_x(struct arth *); 152 static struct slist *xfer_to_a(struct arth *); 153 static struct block *gen_len(int, int); 154 155 static void * 156 newchunk(n) 157 u_int n; 158 { 159 struct chunk *cp; 160 int k, size; 161 162 /* XXX Round up to nearest long. */ 163 n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1); 164 165 cp = &chunks[cur_chunk]; 166 if (n > cp->n_left) { 167 ++cp, k = ++cur_chunk; 168 if (k >= NCHUNKS) 169 bpf_error("out of memory"); 170 size = CHUNK0SIZE << k; 171 cp->m = (void *)malloc(size); 172 memset((char *)cp->m, 0, size); 173 cp->n_left = size; 174 if (n > size) 175 bpf_error("out of memory"); 176 } 177 cp->n_left -= n; 178 return (void *)((char *)cp->m + cp->n_left); 179 } 180 181 static void 182 freechunks() 183 { 184 int i; 185 186 cur_chunk = 0; 187 for (i = 0; i < NCHUNKS; ++i) 188 if (chunks[i].m != NULL) { 189 free(chunks[i].m); 190 chunks[i].m = NULL; 191 } 192 } 193 194 /* 195 * A strdup whose allocations are freed after code generation is over. 196 */ 197 char * 198 sdup(s) 199 register const char *s; 200 { 201 int n = strlen(s) + 1; 202 char *cp = newchunk(n); 203 204 strlcpy(cp, s, n); 205 return (cp); 206 } 207 208 static __inline struct block * 209 new_block(code) 210 int code; 211 { 212 struct block *p; 213 214 p = (struct block *)newchunk(sizeof(*p)); 215 p->s.code = code; 216 p->head = p; 217 218 return p; 219 } 220 221 static __inline struct slist * 222 new_stmt(code) 223 int code; 224 { 225 struct slist *p; 226 227 p = (struct slist *)newchunk(sizeof(*p)); 228 p->s.code = code; 229 230 return p; 231 } 232 233 static struct block * 234 gen_retblk(v) 235 int v; 236 { 237 struct block *b = new_block(BPF_RET|BPF_K); 238 239 b->s.k = v; 240 return b; 241 } 242 243 static __inline void 244 syntax() 245 { 246 bpf_error("syntax error in filter expression"); 247 } 248 249 static bpf_u_int32 netmask; 250 static int snaplen; 251 252 int 253 pcap_compile(pcap_t *p, struct bpf_program *program, 254 char *buf, int optimize, bpf_u_int32 mask) 255 { 256 extern int n_errors; 257 int len; 258 259 n_errors = 0; 260 root = NULL; 261 bpf_pcap = p; 262 if (setjmp(top_ctx)) { 263 freechunks(); 264 return (-1); 265 } 266 267 netmask = mask; 268 snaplen = pcap_snapshot(p); 269 270 lex_init(buf ? buf : ""); 271 init_linktype(pcap_datalink(p)); 272 (void)pcap_parse(); 273 274 if (n_errors) 275 syntax(); 276 277 if (root == NULL) 278 root = gen_retblk(snaplen); 279 280 if (optimize) { 281 bpf_optimize(&root); 282 if (root == NULL || 283 (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0)) 284 bpf_error("expression rejects all packets"); 285 } 286 program->bf_insns = icode_to_fcode(root, &len); 287 program->bf_len = len; 288 289 freechunks(); 290 return (0); 291 } 292 293 /* 294 * Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates 295 * which of the jt and jf fields has been resolved and which is a pointer 296 * back to another unresolved block (or nil). At least one of the fields 297 * in each block is already resolved. 298 */ 299 static void 300 backpatch(list, target) 301 struct block *list, *target; 302 { 303 struct block *next; 304 305 while (list) { 306 if (!list->sense) { 307 next = JT(list); 308 JT(list) = target; 309 } else { 310 next = JF(list); 311 JF(list) = target; 312 } 313 list = next; 314 } 315 } 316 317 /* 318 * Merge the lists in b0 and b1, using the 'sense' field to indicate 319 * which of jt and jf is the link. 320 */ 321 static void 322 merge(b0, b1) 323 struct block *b0, *b1; 324 { 325 register struct block **p = &b0; 326 327 /* Find end of list. */ 328 while (*p) 329 p = !((*p)->sense) ? &JT(*p) : &JF(*p); 330 331 /* Concatenate the lists. */ 332 *p = b1; 333 } 334 335 void 336 finish_parse(p) 337 struct block *p; 338 { 339 backpatch(p, gen_retblk(snaplen)); 340 p->sense = !p->sense; 341 backpatch(p, gen_retblk(0)); 342 root = p->head; 343 } 344 345 void 346 gen_and(b0, b1) 347 struct block *b0, *b1; 348 { 349 backpatch(b0, b1->head); 350 b0->sense = !b0->sense; 351 b1->sense = !b1->sense; 352 merge(b1, b0); 353 b1->sense = !b1->sense; 354 b1->head = b0->head; 355 } 356 357 void 358 gen_or(b0, b1) 359 struct block *b0, *b1; 360 { 361 b0->sense = !b0->sense; 362 backpatch(b0, b1->head); 363 b0->sense = !b0->sense; 364 merge(b1, b0); 365 b1->head = b0->head; 366 } 367 368 void 369 gen_not(b) 370 struct block *b; 371 { 372 b->sense = !b->sense; 373 } 374 375 static struct block * 376 gen_cmp(offset, size, v) 377 u_int offset, size; 378 bpf_int32 v; 379 { 380 struct slist *s; 381 struct block *b; 382 383 s = new_stmt(BPF_LD|BPF_ABS|size); 384 s->s.k = offset; 385 386 b = new_block(JMP(BPF_JEQ)); 387 b->stmts = s; 388 b->s.k = v; 389 390 return b; 391 } 392 393 static struct block * 394 gen_mcmp(offset, size, v, mask) 395 u_int offset, size; 396 bpf_int32 v; 397 bpf_u_int32 mask; 398 { 399 struct block *b = gen_cmp(offset, size, v); 400 struct slist *s; 401 402 if (mask != 0xffffffff) { 403 s = new_stmt(BPF_ALU|BPF_AND|BPF_K); 404 s->s.k = mask; 405 b->stmts->next = s; 406 } 407 return b; 408 } 409 410 static struct block * 411 gen_bcmp(offset, size, v) 412 register u_int offset, size; 413 register const u_char *v; 414 { 415 register struct block *b, *tmp; 416 417 b = NULL; 418 while (size >= 4) { 419 register const u_char *p = &v[size - 4]; 420 bpf_int32 w = ((bpf_int32)p[0] << 24) | 421 ((bpf_int32)p[1] << 16) | ((bpf_int32)p[2] << 8) | p[3]; 422 423 tmp = gen_cmp(offset + size - 4, BPF_W, w); 424 if (b != NULL) 425 gen_and(b, tmp); 426 b = tmp; 427 size -= 4; 428 } 429 while (size >= 2) { 430 register const u_char *p = &v[size - 2]; 431 bpf_int32 w = ((bpf_int32)p[0] << 8) | p[1]; 432 433 tmp = gen_cmp(offset + size - 2, BPF_H, w); 434 if (b != NULL) 435 gen_and(b, tmp); 436 b = tmp; 437 size -= 2; 438 } 439 if (size > 0) { 440 tmp = gen_cmp(offset, BPF_B, (bpf_int32)v[0]); 441 if (b != NULL) 442 gen_and(b, tmp); 443 b = tmp; 444 } 445 return b; 446 } 447 448 /* 449 * Various code constructs need to know the layout of the data link 450 * layer. These variables give the necessary offsets. off_linktype 451 * is set to -1 for no encapsulation, in which case, IP is assumed. 452 */ 453 static u_int off_linktype; 454 static u_int off_nl; 455 static int linktype; 456 457 static void 458 init_linktype(type) 459 int type; 460 { 461 linktype = type; 462 463 switch (type) { 464 465 case DLT_EN10MB: 466 off_linktype = 12; 467 off_nl = 14; 468 return; 469 470 case DLT_SLIP: 471 /* 472 * SLIP doesn't have a link level type. The 16 byte 473 * header is hacked into our SLIP driver. 474 */ 475 off_linktype = -1; 476 off_nl = 16; 477 return; 478 479 case DLT_SLIP_BSDOS: 480 /* XXX this may be the same as the DLT_PPP_BSDOS case */ 481 off_linktype = -1; 482 /* XXX end */ 483 off_nl = 24; 484 return; 485 486 case DLT_NULL: 487 off_linktype = 0; 488 off_nl = 4; 489 return; 490 491 case DLT_PPP: 492 off_linktype = 2; 493 off_nl = 4; 494 return; 495 496 case DLT_PPP_BSDOS: 497 off_linktype = 5; 498 off_nl = 24; 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 case DLT_LOOP: 532 off_linktype = -1; 533 off_nl = 4; 534 return; 535 536 case DLT_ENC: 537 off_linktype = -1; 538 off_nl = 12; 539 return; 540 541 case DLT_RAW: 542 off_linktype = -1; 543 off_nl = 0; 544 return; 545 } 546 bpf_error("unknown data link type 0x%x", linktype); 547 /* NOTREACHED */ 548 } 549 550 static struct block * 551 gen_uncond(rsense) 552 int rsense; 553 { 554 struct block *b; 555 struct slist *s; 556 557 s = new_stmt(BPF_LD|BPF_IMM); 558 s->s.k = !rsense; 559 b = new_block(JMP(BPF_JEQ)); 560 b->stmts = s; 561 562 return b; 563 } 564 565 static __inline struct block * 566 gen_true() 567 { 568 return gen_uncond(1); 569 } 570 571 static __inline struct block * 572 gen_false() 573 { 574 return gen_uncond(0); 575 } 576 577 static struct block * 578 gen_linktype(proto) 579 register int proto; 580 { 581 struct block *b0, *b1; 582 583 /* If we're not using encapsulation and checking for IP, we're done */ 584 if (off_linktype == -1 && proto == ETHERTYPE_IP) 585 return gen_true(); 586 587 switch (linktype) { 588 589 case DLT_SLIP: 590 return gen_false(); 591 592 case DLT_PPP: 593 if (proto == ETHERTYPE_IP) 594 proto = PPP_IP; /* XXX was 0x21 */ 595 break; 596 597 case DLT_PPP_BSDOS: 598 switch (proto) { 599 600 case ETHERTYPE_IP: 601 b0 = gen_cmp(off_linktype, BPF_H, PPP_IP); 602 b1 = gen_cmp(off_linktype, BPF_H, PPP_VJC); 603 gen_or(b0, b1); 604 b0 = gen_cmp(off_linktype, BPF_H, PPP_VJNC); 605 gen_or(b1, b0); 606 return b0; 607 608 case ETHERTYPE_DN: 609 proto = PPP_DECNET; 610 break; 611 612 case ETHERTYPE_ATALK: 613 proto = PPP_APPLE; 614 break; 615 616 case ETHERTYPE_NS: 617 proto = PPP_NS; 618 break; 619 } 620 break; 621 622 case DLT_LOOP: 623 case DLT_ENC: 624 case DLT_NULL: 625 /* XXX */ 626 if (proto == ETHERTYPE_IP) 627 return (gen_cmp(0, BPF_W, (bpf_int32)htonl(AF_INET))); 628 else 629 return gen_false(); 630 } 631 return gen_cmp(off_linktype, BPF_H, (bpf_int32)proto); 632 } 633 634 static struct block * 635 gen_hostop(addr, mask, dir, proto, src_off, dst_off) 636 bpf_u_int32 addr; 637 bpf_u_int32 mask; 638 int dir, proto; 639 u_int src_off, dst_off; 640 { 641 struct block *b0, *b1; 642 u_int offset; 643 644 switch (dir) { 645 646 case Q_SRC: 647 offset = src_off; 648 break; 649 650 case Q_DST: 651 offset = dst_off; 652 break; 653 654 case Q_AND: 655 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); 656 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); 657 gen_and(b0, b1); 658 return b1; 659 660 case Q_OR: 661 case Q_DEFAULT: 662 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); 663 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); 664 gen_or(b0, b1); 665 return b1; 666 667 default: 668 abort(); 669 } 670 b0 = gen_linktype(proto); 671 b1 = gen_mcmp(offset, BPF_W, (bpf_int32)addr, mask); 672 gen_and(b0, b1); 673 return b1; 674 } 675 676 static struct block * 677 gen_ehostop(eaddr, dir) 678 register const u_char *eaddr; 679 register int dir; 680 { 681 register struct block *b0, *b1; 682 683 switch (dir) { 684 case Q_SRC: 685 return gen_bcmp(6, 6, eaddr); 686 687 case Q_DST: 688 return gen_bcmp(0, 6, eaddr); 689 690 case Q_AND: 691 b0 = gen_ehostop(eaddr, Q_SRC); 692 b1 = gen_ehostop(eaddr, Q_DST); 693 gen_and(b0, b1); 694 return b1; 695 696 case Q_DEFAULT: 697 case Q_OR: 698 b0 = gen_ehostop(eaddr, Q_SRC); 699 b1 = gen_ehostop(eaddr, Q_DST); 700 gen_or(b0, b1); 701 return b1; 702 } 703 abort(); 704 /* NOTREACHED */ 705 } 706 707 /* 708 * Like gen_ehostop, but for DLT_FDDI 709 */ 710 static struct block * 711 gen_fhostop(eaddr, dir) 712 register const u_char *eaddr; 713 register int dir; 714 { 715 struct block *b0, *b1; 716 717 switch (dir) { 718 case Q_SRC: 719 #ifdef PCAP_FDDIPAD 720 return gen_bcmp(6 + 1 + pcap_fddipad, 6, eaddr); 721 #else 722 return gen_bcmp(6 + 1, 6, eaddr); 723 #endif 724 725 case Q_DST: 726 #ifdef PCAP_FDDIPAD 727 return gen_bcmp(0 + 1 + pcap_fddipad, 6, eaddr); 728 #else 729 return gen_bcmp(0 + 1, 6, eaddr); 730 #endif 731 732 case Q_AND: 733 b0 = gen_fhostop(eaddr, Q_SRC); 734 b1 = gen_fhostop(eaddr, Q_DST); 735 gen_and(b0, b1); 736 return b1; 737 738 case Q_DEFAULT: 739 case Q_OR: 740 b0 = gen_fhostop(eaddr, Q_SRC); 741 b1 = gen_fhostop(eaddr, Q_DST); 742 gen_or(b0, b1); 743 return b1; 744 } 745 abort(); 746 /* NOTREACHED */ 747 } 748 749 /* 750 * This is quite tricky because there may be pad bytes in front of the 751 * DECNET header, and then there are two possible data packet formats that 752 * carry both src and dst addresses, plus 5 packet types in a format that 753 * carries only the src node, plus 2 types that use a different format and 754 * also carry just the src node. 755 * 756 * Yuck. 757 * 758 * Instead of doing those all right, we just look for data packets with 759 * 0 or 1 bytes of padding. If you want to look at other packets, that 760 * will require a lot more hacking. 761 * 762 * To add support for filtering on DECNET "areas" (network numbers) 763 * one would want to add a "mask" argument to this routine. That would 764 * make the filter even more inefficient, although one could be clever 765 * and not generate masking instructions if the mask is 0xFFFF. 766 */ 767 static struct block * 768 gen_dnhostop(addr, dir, base_off) 769 bpf_u_int32 addr; 770 int dir; 771 u_int base_off; 772 { 773 struct block *b0, *b1, *b2, *tmp; 774 u_int offset_lh; /* offset if long header is received */ 775 u_int offset_sh; /* offset if short header is received */ 776 777 switch (dir) { 778 779 case Q_DST: 780 offset_sh = 1; /* follows flags */ 781 offset_lh = 7; /* flgs,darea,dsubarea,HIORD */ 782 break; 783 784 case Q_SRC: 785 offset_sh = 3; /* follows flags, dstnode */ 786 offset_lh = 15; /* flgs,darea,dsubarea,did,sarea,ssub,HIORD */ 787 break; 788 789 case Q_AND: 790 /* Inefficient because we do our Calvinball dance twice */ 791 b0 = gen_dnhostop(addr, Q_SRC, base_off); 792 b1 = gen_dnhostop(addr, Q_DST, base_off); 793 gen_and(b0, b1); 794 return b1; 795 796 case Q_OR: 797 case Q_DEFAULT: 798 /* Inefficient because we do our Calvinball dance twice */ 799 b0 = gen_dnhostop(addr, Q_SRC, base_off); 800 b1 = gen_dnhostop(addr, Q_DST, base_off); 801 gen_or(b0, b1); 802 return b1; 803 804 default: 805 abort(); 806 } 807 b0 = gen_linktype(ETHERTYPE_DN); 808 /* Check for pad = 1, long header case */ 809 tmp = gen_mcmp(base_off + 2, BPF_H, 810 (bpf_int32)ntohs(0x0681), (bpf_int32)ntohs(0x07FF)); 811 b1 = gen_cmp(base_off + 2 + 1 + offset_lh, 812 BPF_H, (bpf_int32)ntohs(addr)); 813 gen_and(tmp, b1); 814 /* Check for pad = 0, long header case */ 815 tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x06, (bpf_int32)0x7); 816 b2 = gen_cmp(base_off + 2 + offset_lh, BPF_H, (bpf_int32)ntohs(addr)); 817 gen_and(tmp, b2); 818 gen_or(b2, b1); 819 /* Check for pad = 1, short header case */ 820 tmp = gen_mcmp(base_off + 2, BPF_H, 821 (bpf_int32)ntohs(0x0281), (bpf_int32)ntohs(0x07FF)); 822 b2 = gen_cmp(base_off + 2 + 1 + offset_sh, 823 BPF_H, (bpf_int32)ntohs(addr)); 824 gen_and(tmp, b2); 825 gen_or(b2, b1); 826 /* Check for pad = 0, short header case */ 827 tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x02, (bpf_int32)0x7); 828 b2 = gen_cmp(base_off + 2 + offset_sh, BPF_H, (bpf_int32)ntohs(addr)); 829 gen_and(tmp, b2); 830 gen_or(b2, b1); 831 832 /* Combine with test for linktype */ 833 gen_and(b0, b1); 834 return b1; 835 } 836 837 static struct block * 838 gen_host(addr, mask, proto, dir) 839 bpf_u_int32 addr; 840 bpf_u_int32 mask; 841 int proto; 842 int dir; 843 { 844 struct block *b0, *b1; 845 846 switch (proto) { 847 848 case Q_DEFAULT: 849 b0 = gen_host(addr, mask, Q_IP, dir); 850 b1 = gen_host(addr, mask, Q_ARP, dir); 851 gen_or(b0, b1); 852 b0 = gen_host(addr, mask, Q_RARP, dir); 853 gen_or(b1, b0); 854 return b0; 855 856 case Q_IP: 857 return gen_hostop(addr, mask, dir, ETHERTYPE_IP, 858 off_nl + 12, off_nl + 16); 859 860 case Q_RARP: 861 return gen_hostop(addr, mask, dir, ETHERTYPE_REVARP, 862 off_nl + 14, off_nl + 24); 863 864 case Q_ARP: 865 return gen_hostop(addr, mask, dir, ETHERTYPE_ARP, 866 off_nl + 14, off_nl + 24); 867 868 case Q_TCP: 869 bpf_error("'tcp' modifier applied to host"); 870 871 case Q_UDP: 872 bpf_error("'udp' modifier applied to host"); 873 874 case Q_ICMP: 875 bpf_error("'icmp' modifier applied to host"); 876 877 case Q_IGMP: 878 bpf_error("'igmp' modifier applied to host"); 879 880 case Q_IGRP: 881 bpf_error("'igrp' modifier applied to host"); 882 883 case Q_ATALK: 884 bpf_error("ATALK host filtering not implemented"); 885 886 case Q_DECNET: 887 return gen_dnhostop(addr, dir, off_nl); 888 889 case Q_SCA: 890 bpf_error("SCA host filtering not implemented"); 891 892 case Q_LAT: 893 bpf_error("LAT host filtering not implemented"); 894 895 case Q_MOPDL: 896 bpf_error("MOPDL host filtering not implemented"); 897 898 case Q_MOPRC: 899 bpf_error("MOPRC host filtering not implemented"); 900 901 default: 902 abort(); 903 } 904 /* NOTREACHED */ 905 } 906 907 static struct block * 908 gen_gateway(eaddr, alist, proto, dir) 909 const u_char *eaddr; 910 bpf_u_int32 **alist; 911 int proto; 912 int dir; 913 { 914 struct block *b0, *b1, *tmp; 915 916 if (dir != 0) 917 bpf_error("direction applied to 'gateway'"); 918 919 switch (proto) { 920 case Q_DEFAULT: 921 case Q_IP: 922 case Q_ARP: 923 case Q_RARP: 924 if (linktype == DLT_EN10MB) 925 b0 = gen_ehostop(eaddr, Q_OR); 926 else if (linktype == DLT_FDDI) 927 b0 = gen_fhostop(eaddr, Q_OR); 928 else 929 bpf_error( 930 "'gateway' supported only on ethernet or FDDI"); 931 932 b1 = gen_host(**alist++, 0xffffffff, proto, Q_OR); 933 while (*alist) { 934 tmp = gen_host(**alist++, 0xffffffff, proto, Q_OR); 935 gen_or(b1, tmp); 936 b1 = tmp; 937 } 938 gen_not(b1); 939 gen_and(b0, b1); 940 return b1; 941 } 942 bpf_error("illegal modifier of 'gateway'"); 943 /* NOTREACHED */ 944 } 945 946 struct block * 947 gen_proto_abbrev(proto) 948 int proto; 949 { 950 struct block *b0, *b1; 951 952 switch (proto) { 953 954 case Q_TCP: 955 b0 = gen_linktype(ETHERTYPE_IP); 956 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_TCP); 957 gen_and(b0, b1); 958 break; 959 960 case Q_UDP: 961 b0 = gen_linktype(ETHERTYPE_IP); 962 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_UDP); 963 gen_and(b0, b1); 964 break; 965 966 case Q_ICMP: 967 b0 = gen_linktype(ETHERTYPE_IP); 968 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_ICMP); 969 gen_and(b0, b1); 970 break; 971 972 case Q_IGMP: 973 b0 = gen_linktype(ETHERTYPE_IP); 974 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)2); 975 gen_and(b0, b1); 976 break; 977 978 #ifndef IPPROTO_IGRP 979 #define IPPROTO_IGRP 9 980 #endif 981 case Q_IGRP: 982 b0 = gen_linktype(ETHERTYPE_IP); 983 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_IGRP); 984 gen_and(b0, b1); 985 break; 986 987 case Q_IP: 988 b1 = gen_linktype(ETHERTYPE_IP); 989 break; 990 991 case Q_ARP: 992 b1 = gen_linktype(ETHERTYPE_ARP); 993 break; 994 995 case Q_RARP: 996 b1 = gen_linktype(ETHERTYPE_REVARP); 997 break; 998 999 case Q_LINK: 1000 bpf_error("link layer applied in wrong context"); 1001 1002 case Q_ATALK: 1003 b1 = gen_linktype(ETHERTYPE_ATALK); 1004 break; 1005 1006 case Q_DECNET: 1007 b1 = gen_linktype(ETHERTYPE_DN); 1008 break; 1009 1010 case Q_SCA: 1011 b1 = gen_linktype(ETHERTYPE_SCA); 1012 break; 1013 1014 case Q_LAT: 1015 b1 = gen_linktype(ETHERTYPE_LAT); 1016 break; 1017 1018 case Q_MOPDL: 1019 b1 = gen_linktype(ETHERTYPE_MOPDL); 1020 break; 1021 1022 case Q_MOPRC: 1023 b1 = gen_linktype(ETHERTYPE_MOPRC); 1024 break; 1025 1026 default: 1027 abort(); 1028 } 1029 return b1; 1030 } 1031 1032 static struct block * 1033 gen_ipfrag() 1034 { 1035 struct slist *s; 1036 struct block *b; 1037 1038 /* not ip frag */ 1039 s = new_stmt(BPF_LD|BPF_H|BPF_ABS); 1040 s->s.k = off_nl + 6; 1041 b = new_block(JMP(BPF_JSET)); 1042 b->s.k = 0x1fff; 1043 b->stmts = s; 1044 gen_not(b); 1045 1046 return b; 1047 } 1048 1049 static struct block * 1050 gen_portatom(off, v) 1051 int off; 1052 bpf_int32 v; 1053 { 1054 struct slist *s; 1055 struct block *b; 1056 1057 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); 1058 s->s.k = off_nl; 1059 1060 s->next = new_stmt(BPF_LD|BPF_IND|BPF_H); 1061 s->next->s.k = off_nl + off; 1062 1063 b = new_block(JMP(BPF_JEQ)); 1064 b->stmts = s; 1065 b->s.k = v; 1066 1067 return b; 1068 } 1069 1070 struct block * 1071 gen_portop(port, proto, dir) 1072 int port, proto, dir; 1073 { 1074 struct block *b0, *b1, *tmp; 1075 1076 /* ip proto 'proto' */ 1077 tmp = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)proto); 1078 b0 = gen_ipfrag(); 1079 gen_and(tmp, b0); 1080 1081 switch (dir) { 1082 case Q_SRC: 1083 b1 = gen_portatom(0, (bpf_int32)port); 1084 break; 1085 1086 case Q_DST: 1087 b1 = gen_portatom(2, (bpf_int32)port); 1088 break; 1089 1090 case Q_OR: 1091 case Q_DEFAULT: 1092 tmp = gen_portatom(0, (bpf_int32)port); 1093 b1 = gen_portatom(2, (bpf_int32)port); 1094 gen_or(tmp, b1); 1095 break; 1096 1097 case Q_AND: 1098 tmp = gen_portatom(0, (bpf_int32)port); 1099 b1 = gen_portatom(2, (bpf_int32)port); 1100 gen_and(tmp, b1); 1101 break; 1102 1103 default: 1104 abort(); 1105 } 1106 gen_and(b0, b1); 1107 1108 return b1; 1109 } 1110 1111 static struct block * 1112 gen_port(port, ip_proto, dir) 1113 int port; 1114 int ip_proto; 1115 int dir; 1116 { 1117 struct block *b0, *b1, *tmp; 1118 1119 /* ether proto ip */ 1120 b0 = gen_linktype(ETHERTYPE_IP); 1121 1122 switch (ip_proto) { 1123 case IPPROTO_UDP: 1124 case IPPROTO_TCP: 1125 b1 = gen_portop(port, ip_proto, dir); 1126 break; 1127 1128 case PROTO_UNDEF: 1129 tmp = gen_portop(port, IPPROTO_TCP, dir); 1130 b1 = gen_portop(port, IPPROTO_UDP, dir); 1131 gen_or(tmp, b1); 1132 break; 1133 1134 default: 1135 abort(); 1136 } 1137 gen_and(b0, b1); 1138 return b1; 1139 } 1140 1141 static int 1142 lookup_proto(name, proto) 1143 register const char *name; 1144 register int proto; 1145 { 1146 register int v; 1147 1148 switch (proto) { 1149 1150 case Q_DEFAULT: 1151 case Q_IP: 1152 v = pcap_nametoproto(name); 1153 if (v == PROTO_UNDEF) 1154 bpf_error("unknown ip proto '%s'", name); 1155 break; 1156 1157 case Q_LINK: 1158 /* XXX should look up h/w protocol type based on linktype */ 1159 v = pcap_nametoeproto(name); 1160 if (v == PROTO_UNDEF) 1161 bpf_error("unknown ether proto '%s'", name); 1162 break; 1163 1164 default: 1165 v = PROTO_UNDEF; 1166 break; 1167 } 1168 return v; 1169 } 1170 1171 static struct block * 1172 gen_proto(v, proto, dir) 1173 int v; 1174 int proto; 1175 int dir; 1176 { 1177 struct block *b0, *b1; 1178 1179 if (dir != Q_DEFAULT) 1180 bpf_error("direction applied to 'proto'"); 1181 1182 switch (proto) { 1183 case Q_DEFAULT: 1184 case Q_IP: 1185 b0 = gen_linktype(ETHERTYPE_IP); 1186 b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)v); 1187 gen_and(b0, b1); 1188 return b1; 1189 1190 case Q_ARP: 1191 bpf_error("arp does not encapsulate another protocol"); 1192 /* NOTREACHED */ 1193 1194 case Q_RARP: 1195 bpf_error("rarp does not encapsulate another protocol"); 1196 /* NOTREACHED */ 1197 1198 case Q_ATALK: 1199 bpf_error("atalk encapsulation is not specifiable"); 1200 /* NOTREACHED */ 1201 1202 case Q_DECNET: 1203 bpf_error("decnet encapsulation is not specifiable"); 1204 /* NOTREACHED */ 1205 1206 case Q_SCA: 1207 bpf_error("sca does not encapsulate another protocol"); 1208 /* NOTREACHED */ 1209 1210 case Q_LAT: 1211 bpf_error("lat does not encapsulate another protocol"); 1212 /* NOTREACHED */ 1213 1214 case Q_MOPRC: 1215 bpf_error("moprc does not encapsulate another protocol"); 1216 /* NOTREACHED */ 1217 1218 case Q_MOPDL: 1219 bpf_error("mopdl does not encapsulate another protocol"); 1220 /* NOTREACHED */ 1221 1222 case Q_LINK: 1223 return gen_linktype(v); 1224 1225 case Q_UDP: 1226 bpf_error("'udp proto' is bogus"); 1227 /* NOTREACHED */ 1228 1229 case Q_TCP: 1230 bpf_error("'tcp proto' is bogus"); 1231 /* NOTREACHED */ 1232 1233 case Q_ICMP: 1234 bpf_error("'icmp proto' is bogus"); 1235 /* NOTREACHED */ 1236 1237 case Q_IGMP: 1238 bpf_error("'igmp proto' is bogus"); 1239 /* NOTREACHED */ 1240 1241 case Q_IGRP: 1242 bpf_error("'igrp proto' is bogus"); 1243 /* NOTREACHED */ 1244 1245 default: 1246 abort(); 1247 /* NOTREACHED */ 1248 } 1249 /* NOTREACHED */ 1250 } 1251 1252 struct block * 1253 gen_scode(name, q) 1254 register const char *name; 1255 struct qual q; 1256 { 1257 int proto = q.proto; 1258 int dir = q.dir; 1259 int tproto; 1260 u_char *eaddr; 1261 bpf_u_int32 mask, addr, **alist; 1262 struct block *b, *tmp; 1263 int port, real_proto; 1264 1265 switch (q.addr) { 1266 1267 case Q_NET: 1268 addr = pcap_nametonetaddr(name); 1269 if (addr == 0) 1270 bpf_error("unknown network '%s'", name); 1271 /* Left justify network addr and calculate its network mask */ 1272 mask = 0xffffffff; 1273 while (addr && (addr & 0xff000000) == 0) { 1274 addr <<= 8; 1275 mask <<= 8; 1276 } 1277 return gen_host(addr, mask, proto, dir); 1278 1279 case Q_DEFAULT: 1280 case Q_HOST: 1281 if (proto == Q_LINK) { 1282 switch (linktype) { 1283 1284 case DLT_EN10MB: 1285 eaddr = pcap_ether_hostton(name); 1286 if (eaddr == NULL) 1287 bpf_error( 1288 "unknown ether host '%s'", name); 1289 return gen_ehostop(eaddr, dir); 1290 1291 case DLT_FDDI: 1292 eaddr = pcap_ether_hostton(name); 1293 if (eaddr == NULL) 1294 bpf_error( 1295 "unknown FDDI host '%s'", name); 1296 return gen_fhostop(eaddr, dir); 1297 1298 default: 1299 bpf_error( 1300 "only ethernet/FDDI supports link-level host name"); 1301 break; 1302 } 1303 } else if (proto == Q_DECNET) { 1304 unsigned short dn_addr = __pcap_nametodnaddr(name); 1305 /* 1306 * I don't think DECNET hosts can be multihomed, so 1307 * there is no need to build up a list of addresses 1308 */ 1309 return (gen_host(dn_addr, 0, proto, dir)); 1310 } else { 1311 alist = pcap_nametoaddr(name); 1312 if (alist == NULL || *alist == NULL) 1313 bpf_error("unknown host '%s'", name); 1314 tproto = proto; 1315 if (off_linktype == -1 && tproto == Q_DEFAULT) 1316 tproto = Q_IP; 1317 b = gen_host(**alist++, 0xffffffff, tproto, dir); 1318 while (*alist) { 1319 tmp = gen_host(**alist++, 0xffffffff, 1320 tproto, dir); 1321 gen_or(b, tmp); 1322 b = tmp; 1323 } 1324 return b; 1325 } 1326 1327 case Q_PORT: 1328 if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP) 1329 bpf_error("illegal qualifier of 'port'"); 1330 if (pcap_nametoport(name, &port, &real_proto) == 0) 1331 bpf_error("unknown port '%s'", name); 1332 if (proto == Q_UDP) { 1333 if (real_proto == IPPROTO_TCP) 1334 bpf_error("port '%s' is tcp", name); 1335 else 1336 /* override PROTO_UNDEF */ 1337 real_proto = IPPROTO_UDP; 1338 } 1339 if (proto == Q_TCP) { 1340 if (real_proto == IPPROTO_UDP) 1341 bpf_error("port '%s' is udp", name); 1342 else 1343 /* override PROTO_UNDEF */ 1344 real_proto = IPPROTO_TCP; 1345 } 1346 return gen_port(port, real_proto, dir); 1347 1348 case Q_GATEWAY: 1349 eaddr = pcap_ether_hostton(name); 1350 if (eaddr == NULL) 1351 bpf_error("unknown ether host: %s", name); 1352 1353 alist = pcap_nametoaddr(name); 1354 if (alist == NULL || *alist == NULL) 1355 bpf_error("unknown host '%s'", name); 1356 return gen_gateway(eaddr, alist, proto, dir); 1357 1358 case Q_PROTO: 1359 real_proto = lookup_proto(name, proto); 1360 if (real_proto >= 0) 1361 return gen_proto(real_proto, proto, dir); 1362 else 1363 bpf_error("unknown protocol: %s", name); 1364 1365 case Q_UNDEF: 1366 syntax(); 1367 /* NOTREACHED */ 1368 } 1369 abort(); 1370 /* NOTREACHED */ 1371 } 1372 1373 struct block * 1374 gen_mcode(s1, s2, masklen, q) 1375 register const char *s1, *s2; 1376 register int masklen; 1377 struct qual q; 1378 { 1379 register int nlen, mlen; 1380 bpf_u_int32 n, m; 1381 1382 nlen = __pcap_atoin(s1, &n); 1383 /* Promote short ipaddr */ 1384 n <<= 32 - nlen; 1385 1386 if (s2 != NULL) { 1387 mlen = __pcap_atoin(s2, &m); 1388 /* Promote short ipaddr */ 1389 m <<= 32 - mlen; 1390 if ((n & ~m) != 0) 1391 bpf_error("non-network bits set in \"%s mask %s\"", 1392 s1, s2); 1393 } else { 1394 /* Convert mask len to mask */ 1395 if (masklen > 32) 1396 bpf_error("mask length must be <= 32"); 1397 m = 0xffffffff << (32 - masklen); 1398 if ((n & ~m) != 0) 1399 bpf_error("non-network bits set in \"%s/%d\"", 1400 s1, masklen); 1401 } 1402 1403 switch (q.addr) { 1404 1405 case Q_NET: 1406 return gen_host(n, m, q.proto, q.dir); 1407 1408 default: 1409 bpf_error("Mask syntax for networks only"); 1410 /* NOTREACHED */ 1411 } 1412 } 1413 1414 struct block * 1415 gen_ncode(s, v, q) 1416 register const char *s; 1417 bpf_u_int32 v; 1418 struct qual q; 1419 { 1420 bpf_u_int32 mask; 1421 int proto = q.proto; 1422 int dir = q.dir; 1423 register int vlen; 1424 1425 if (s == NULL) 1426 vlen = 32; 1427 else if (q.proto == Q_DECNET) 1428 vlen = __pcap_atodn(s, &v); 1429 else 1430 vlen = __pcap_atoin(s, &v); 1431 1432 switch (q.addr) { 1433 1434 case Q_DEFAULT: 1435 case Q_HOST: 1436 case Q_NET: 1437 if (proto == Q_DECNET) 1438 return gen_host(v, 0, proto, dir); 1439 else if (proto == Q_LINK) { 1440 bpf_error("illegal link layer address"); 1441 } else { 1442 mask = 0xffffffff; 1443 if (s == NULL && q.addr == Q_NET) { 1444 /* Promote short net number */ 1445 while (v && (v & 0xff000000) == 0) { 1446 v <<= 8; 1447 mask <<= 8; 1448 } 1449 } else { 1450 /* Promote short ipaddr */ 1451 v <<= 32 - vlen; 1452 mask <<= 32 - vlen; 1453 } 1454 return gen_host(v, mask, proto, dir); 1455 } 1456 1457 case Q_PORT: 1458 if (proto == Q_UDP) 1459 proto = IPPROTO_UDP; 1460 else if (proto == Q_TCP) 1461 proto = IPPROTO_TCP; 1462 else if (proto == Q_DEFAULT) 1463 proto = PROTO_UNDEF; 1464 else 1465 bpf_error("illegal qualifier of 'port'"); 1466 1467 return gen_port((int)v, proto, dir); 1468 1469 case Q_GATEWAY: 1470 bpf_error("'gateway' requires a name"); 1471 /* NOTREACHED */ 1472 1473 case Q_PROTO: 1474 return gen_proto((int)v, proto, dir); 1475 1476 case Q_UNDEF: 1477 syntax(); 1478 /* NOTREACHED */ 1479 1480 default: 1481 abort(); 1482 /* NOTREACHED */ 1483 } 1484 /* NOTREACHED */ 1485 } 1486 1487 struct block * 1488 gen_ecode(eaddr, q) 1489 register const u_char *eaddr; 1490 struct qual q; 1491 { 1492 if ((q.addr == Q_HOST || q.addr == Q_DEFAULT) && q.proto == Q_LINK) { 1493 if (linktype == DLT_EN10MB) 1494 return gen_ehostop(eaddr, (int)q.dir); 1495 if (linktype == DLT_FDDI) 1496 return gen_fhostop(eaddr, (int)q.dir); 1497 } 1498 bpf_error("ethernet address used in non-ether expression"); 1499 /* NOTREACHED */ 1500 } 1501 1502 void 1503 sappend(s0, s1) 1504 struct slist *s0, *s1; 1505 { 1506 /* 1507 * This is definitely not the best way to do this, but the 1508 * lists will rarely get long. 1509 */ 1510 while (s0->next) 1511 s0 = s0->next; 1512 s0->next = s1; 1513 } 1514 1515 static struct slist * 1516 xfer_to_x(a) 1517 struct arth *a; 1518 { 1519 struct slist *s; 1520 1521 s = new_stmt(BPF_LDX|BPF_MEM); 1522 s->s.k = a->regno; 1523 return s; 1524 } 1525 1526 static struct slist * 1527 xfer_to_a(a) 1528 struct arth *a; 1529 { 1530 struct slist *s; 1531 1532 s = new_stmt(BPF_LD|BPF_MEM); 1533 s->s.k = a->regno; 1534 return s; 1535 } 1536 1537 struct arth * 1538 gen_load(proto, index, size) 1539 int proto; 1540 struct arth *index; 1541 int size; 1542 { 1543 struct slist *s, *tmp; 1544 struct block *b; 1545 int regno = alloc_reg(); 1546 1547 free_reg(index->regno); 1548 switch (size) { 1549 1550 default: 1551 bpf_error("data size must be 1, 2, or 4"); 1552 1553 case 1: 1554 size = BPF_B; 1555 break; 1556 1557 case 2: 1558 size = BPF_H; 1559 break; 1560 1561 case 4: 1562 size = BPF_W; 1563 break; 1564 } 1565 switch (proto) { 1566 default: 1567 bpf_error("unsupported index operation"); 1568 1569 case Q_LINK: 1570 s = xfer_to_x(index); 1571 tmp = new_stmt(BPF_LD|BPF_IND|size); 1572 sappend(s, tmp); 1573 sappend(index->s, s); 1574 break; 1575 1576 case Q_IP: 1577 case Q_ARP: 1578 case Q_RARP: 1579 case Q_ATALK: 1580 case Q_DECNET: 1581 case Q_SCA: 1582 case Q_LAT: 1583 case Q_MOPRC: 1584 case Q_MOPDL: 1585 /* XXX Note that we assume a fixed link link header here. */ 1586 s = xfer_to_x(index); 1587 tmp = new_stmt(BPF_LD|BPF_IND|size); 1588 tmp->s.k = off_nl; 1589 sappend(s, tmp); 1590 sappend(index->s, s); 1591 1592 b = gen_proto_abbrev(proto); 1593 if (index->b) 1594 gen_and(index->b, b); 1595 index->b = b; 1596 break; 1597 1598 case Q_TCP: 1599 case Q_UDP: 1600 case Q_ICMP: 1601 case Q_IGMP: 1602 case Q_IGRP: 1603 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); 1604 s->s.k = off_nl; 1605 sappend(s, xfer_to_a(index)); 1606 sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X)); 1607 sappend(s, new_stmt(BPF_MISC|BPF_TAX)); 1608 sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size)); 1609 tmp->s.k = off_nl; 1610 sappend(index->s, s); 1611 1612 gen_and(gen_proto_abbrev(proto), b = gen_ipfrag()); 1613 if (index->b) 1614 gen_and(index->b, b); 1615 index->b = b; 1616 break; 1617 } 1618 index->regno = regno; 1619 s = new_stmt(BPF_ST); 1620 s->s.k = regno; 1621 sappend(index->s, s); 1622 1623 return index; 1624 } 1625 1626 struct block * 1627 gen_relation(code, a0, a1, reversed) 1628 int code; 1629 struct arth *a0, *a1; 1630 int reversed; 1631 { 1632 struct slist *s0, *s1, *s2; 1633 struct block *b, *tmp; 1634 1635 s0 = xfer_to_x(a1); 1636 s1 = xfer_to_a(a0); 1637 s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X); 1638 b = new_block(JMP(code)); 1639 if (code == BPF_JGT || code == BPF_JGE) { 1640 reversed = !reversed; 1641 b->s.k = 0x80000000; 1642 } 1643 if (reversed) 1644 gen_not(b); 1645 1646 sappend(s1, s2); 1647 sappend(s0, s1); 1648 sappend(a1->s, s0); 1649 sappend(a0->s, a1->s); 1650 1651 b->stmts = a0->s; 1652 1653 free_reg(a0->regno); 1654 free_reg(a1->regno); 1655 1656 /* 'and' together protocol checks */ 1657 if (a0->b) { 1658 if (a1->b) { 1659 gen_and(a0->b, tmp = a1->b); 1660 } 1661 else 1662 tmp = a0->b; 1663 } else 1664 tmp = a1->b; 1665 1666 if (tmp) 1667 gen_and(tmp, b); 1668 1669 return b; 1670 } 1671 1672 struct arth * 1673 gen_loadlen() 1674 { 1675 int regno = alloc_reg(); 1676 struct arth *a = (struct arth *)newchunk(sizeof(*a)); 1677 struct slist *s; 1678 1679 s = new_stmt(BPF_LD|BPF_LEN); 1680 s->next = new_stmt(BPF_ST); 1681 s->next->s.k = regno; 1682 a->s = s; 1683 a->regno = regno; 1684 1685 return a; 1686 } 1687 1688 struct arth * 1689 gen_loadi(val) 1690 int val; 1691 { 1692 struct arth *a; 1693 struct slist *s; 1694 int reg; 1695 1696 a = (struct arth *)newchunk(sizeof(*a)); 1697 1698 reg = alloc_reg(); 1699 1700 s = new_stmt(BPF_LD|BPF_IMM); 1701 s->s.k = val; 1702 s->next = new_stmt(BPF_ST); 1703 s->next->s.k = reg; 1704 a->s = s; 1705 a->regno = reg; 1706 1707 return a; 1708 } 1709 1710 struct arth * 1711 gen_neg(a) 1712 struct arth *a; 1713 { 1714 struct slist *s; 1715 1716 s = xfer_to_a(a); 1717 sappend(a->s, s); 1718 s = new_stmt(BPF_ALU|BPF_NEG); 1719 s->s.k = 0; 1720 sappend(a->s, s); 1721 s = new_stmt(BPF_ST); 1722 s->s.k = a->regno; 1723 sappend(a->s, s); 1724 1725 return a; 1726 } 1727 1728 struct arth * 1729 gen_arth(code, a0, a1) 1730 int code; 1731 struct arth *a0, *a1; 1732 { 1733 struct slist *s0, *s1, *s2; 1734 1735 s0 = xfer_to_x(a1); 1736 s1 = xfer_to_a(a0); 1737 s2 = new_stmt(BPF_ALU|BPF_X|code); 1738 1739 sappend(s1, s2); 1740 sappend(s0, s1); 1741 sappend(a1->s, s0); 1742 sappend(a0->s, a1->s); 1743 1744 free_reg(a1->regno); 1745 1746 s0 = new_stmt(BPF_ST); 1747 a0->regno = s0->s.k = alloc_reg(); 1748 sappend(a0->s, s0); 1749 1750 return a0; 1751 } 1752 1753 /* 1754 * Here we handle simple allocation of the scratch registers. 1755 * If too many registers are alloc'd, the allocator punts. 1756 */ 1757 static int regused[BPF_MEMWORDS]; 1758 static int curreg; 1759 1760 /* 1761 * Return the next free register. 1762 */ 1763 static int 1764 alloc_reg() 1765 { 1766 int n = BPF_MEMWORDS; 1767 1768 while (--n >= 0) { 1769 if (regused[curreg]) 1770 curreg = (curreg + 1) % BPF_MEMWORDS; 1771 else { 1772 regused[curreg] = 1; 1773 return curreg; 1774 } 1775 } 1776 bpf_error("too many registers needed to evaluate expression"); 1777 /* NOTREACHED */ 1778 } 1779 1780 /* 1781 * Return a register to the table so it can 1782 * be used later. 1783 */ 1784 static void 1785 free_reg(n) 1786 int n; 1787 { 1788 regused[n] = 0; 1789 } 1790 1791 static struct block * 1792 gen_len(jmp, n) 1793 int jmp, n; 1794 { 1795 struct slist *s; 1796 struct block *b; 1797 1798 s = new_stmt(BPF_LD|BPF_LEN); 1799 b = new_block(JMP(jmp)); 1800 b->stmts = s; 1801 b->s.k = n; 1802 1803 return b; 1804 } 1805 1806 struct block * 1807 gen_greater(n) 1808 int n; 1809 { 1810 return gen_len(BPF_JGE, n); 1811 } 1812 1813 struct block * 1814 gen_less(n) 1815 int n; 1816 { 1817 struct block *b; 1818 1819 b = gen_len(BPF_JGT, n); 1820 gen_not(b); 1821 1822 return b; 1823 } 1824 1825 struct block * 1826 gen_byteop(op, idx, val) 1827 int op, idx, val; 1828 { 1829 struct block *b; 1830 struct slist *s; 1831 1832 switch (op) { 1833 default: 1834 abort(); 1835 1836 case '=': 1837 return gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1838 1839 case '<': 1840 b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1841 b->s.code = JMP(BPF_JGE); 1842 gen_not(b); 1843 return b; 1844 1845 case '>': 1846 b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); 1847 b->s.code = JMP(BPF_JGT); 1848 return b; 1849 1850 case '|': 1851 s = new_stmt(BPF_ALU|BPF_OR|BPF_K); 1852 break; 1853 1854 case '&': 1855 s = new_stmt(BPF_ALU|BPF_AND|BPF_K); 1856 break; 1857 } 1858 s->s.k = val; 1859 b = new_block(JMP(BPF_JEQ)); 1860 b->stmts = s; 1861 gen_not(b); 1862 1863 return b; 1864 } 1865 1866 struct block * 1867 gen_broadcast(proto) 1868 int proto; 1869 { 1870 bpf_u_int32 hostmask; 1871 struct block *b0, *b1, *b2; 1872 static u_char ebroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; 1873 1874 switch (proto) { 1875 1876 case Q_DEFAULT: 1877 case Q_LINK: 1878 if (linktype == DLT_EN10MB) 1879 return gen_ehostop(ebroadcast, Q_DST); 1880 if (linktype == DLT_FDDI) 1881 return gen_fhostop(ebroadcast, Q_DST); 1882 bpf_error("not a broadcast link"); 1883 break; 1884 1885 case Q_IP: 1886 b0 = gen_linktype(ETHERTYPE_IP); 1887 hostmask = ~netmask; 1888 b1 = gen_mcmp(off_nl + 16, BPF_W, (bpf_int32)0, hostmask); 1889 b2 = gen_mcmp(off_nl + 16, BPF_W, 1890 (bpf_int32)(~0 & hostmask), hostmask); 1891 gen_or(b1, b2); 1892 gen_and(b0, b2); 1893 return b2; 1894 } 1895 bpf_error("only ether/ip broadcast filters supported"); 1896 } 1897 1898 struct block * 1899 gen_multicast(proto) 1900 int proto; 1901 { 1902 register struct block *b0, *b1; 1903 register struct slist *s; 1904 1905 switch (proto) { 1906 1907 case Q_DEFAULT: 1908 case Q_LINK: 1909 if (linktype == DLT_EN10MB) { 1910 /* ether[0] & 1 != 0 */ 1911 s = new_stmt(BPF_LD|BPF_B|BPF_ABS); 1912 s->s.k = 0; 1913 b0 = new_block(JMP(BPF_JSET)); 1914 b0->s.k = 1; 1915 b0->stmts = s; 1916 return b0; 1917 } 1918 1919 if (linktype == DLT_FDDI) { 1920 /* XXX TEST THIS: MIGHT NOT PORT PROPERLY XXX */ 1921 /* fddi[1] & 1 != 0 */ 1922 s = new_stmt(BPF_LD|BPF_B|BPF_ABS); 1923 s->s.k = 1; 1924 b0 = new_block(JMP(BPF_JSET)); 1925 b0->s.k = 1; 1926 b0->stmts = s; 1927 return b0; 1928 } 1929 /* Link not known to support multicasts */ 1930 break; 1931 1932 case Q_IP: 1933 b0 = gen_linktype(ETHERTYPE_IP); 1934 b1 = gen_cmp(off_nl + 16, BPF_B, (bpf_int32)224); 1935 b1->s.code = JMP(BPF_JGE); 1936 gen_and(b0, b1); 1937 return b1; 1938 } 1939 bpf_error("only IP multicast filters supported on ethernet/FDDI"); 1940 } 1941 1942 /* 1943 * generate command for inbound/outbound. It's here so we can 1944 * make it link-type specific. 'dir' = 0 implies "inbound", 1945 * = 1 implies "outbound". 1946 */ 1947 struct block * 1948 gen_inbound(dir) 1949 int dir; 1950 { 1951 register struct block *b0; 1952 1953 b0 = gen_relation(BPF_JEQ, 1954 gen_load(Q_LINK, gen_loadi(0), 1), 1955 gen_loadi(0), 1956 dir); 1957 return (b0); 1958 } 1959