1 /* From NetBSD: gencode.c,v 1.2 1995/03/06 11:38:21 mycroft Exp */
4 * Copyright (c) 1990, 1991, 1992, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
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
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.
25 "@(#) Header: gencode.c,v 1.55 94/06/20 19:07:53 leres Exp (LBL)";
30 #include <sys/types.h>
31 #include <sys/socket.h>
34 #include <net/ppp_defs.h>
35 #include <netinet/in.h>
37 #include "bpf_compile.h"
52 #define JMP(c) ((c)|BPF_JMP|BPF_K)
54 static jmp_buf top_ctx;
55 static char errbuf[PCAP_ERRBUF_SIZE];
60 bpf_error(char *fmt, ...)
62 bpf_error(fmt, va_alist)
74 vsprintf(errbuf, fmt, ap);
86 static void init_linktype();
88 static int alloc_reg(void);
89 static void free_reg(int);
91 static struct block *root;
94 * We divy out chunks of memory rather than call malloc each time so
95 * we don't have to worry about leaking memory. It's probably
96 * not a big deal if all this memory was wasted but it this ever
97 * goes into a library that would probably not be a good idea.
100 #define CHUNK0SIZE 1024
106 static struct chunk chunks[NCHUNKS];
107 static int cur_chunk = -1;
109 static void *newchunk(u_int);
110 static void freechunks(void);
111 static inline struct block *new_block(int);
112 static inline struct slist *new_stmt(int);
113 static struct block *gen_retblk(int);
114 static inline void syntax(void);
116 static void backpatch(struct block *, struct block *);
117 static void merge(struct block *, struct block *);
118 static struct block *gen_cmp(u_int, u_int, long);
119 static struct block *gen_mcmp(u_int, u_int, long, u_long);
121 static struct block *gen_bcmp(u_int, u_int, u_char *);
123 static struct block *gen_uncond(int);
124 static inline struct block *gen_true(void);
125 static inline struct block *gen_false(void);
126 static struct block *gen_linktype(int);
127 static struct block *gen_hostop(u_long, u_long, int, int, u_int, u_int);
128 static struct block *gen_host(u_long, u_long, int, int);
129 static struct block *gen_ipfrag(void);
130 static struct block *gen_portatom(int, long);
131 struct block *gen_portop(int, int, int);
132 static struct block *gen_port(int, int, int);
133 static int lookup_proto(char *, int);
134 static struct block *gen_proto(int, int, int);
135 static u_long net_mask(u_long *);
136 static u_long net_mask(u_long *);
137 static struct slist *xfer_to_x(struct arth *);
138 static struct slist *xfer_to_a(struct arth *);
139 static struct block *gen_len(int, int);
148 /* XXX Round up to nearest long. */
149 n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
151 cp = &chunks[cur_chunk];
152 if (cur_chunk < 0 || n > cp->n_left) {
153 if (++cur_chunk >= NCHUNKS)
154 bpf_error("out of memory");
155 cp = &chunks[cur_chunk];
156 size = CHUNK0SIZE << cur_chunk;
157 cp->m = (void *)malloc(size);
158 if (cp->m == 0 || n > size)
159 bpf_error("out of memory");
160 memset((char *)cp->m, 0, size);
164 return (void *)((char *)cp->m + cp->n_left);
172 for (i = 0; i < NCHUNKS; ++i)
179 * A strdup whose allocations are freed after code generation is over.
185 int n = strlen(s) + 1;
186 char *cp = newchunk(n);
191 static inline struct block *
197 p = (struct block *)newchunk(sizeof(*p));
204 static inline struct slist *
210 p = (struct slist *)newchunk(sizeof(*p));
216 static struct block *
220 struct block *b = new_block(BPF_RET|BPF_K);
229 bpf_error("syntax error in filter expression");
235 bpf_compile(program, buf, optimize)
236 struct bpf_program *program;
246 snaplen = PPP_HDRLEN;
248 lex_init(buf ? buf : "");
256 root = gen_retblk(snaplen);
261 (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0))
262 bpf_error("expression rejects all packets");
264 program->bf_insns = icode_to_fcode(root, &len);
265 program->bf_len = len;
272 * Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates
273 * which of the jt and jf fields has been resolved and which is a pointer
274 * back to another unresolved block (or nil). At least one of the fields
275 * in each block is already resolved.
278 backpatch(list, target)
279 struct block *list, *target;
296 * Merge the lists in b0 and b1, using the 'sense' field to indicate
297 * which of jt and jf is the link.
301 struct block *b0, *b1;
303 register struct block **p = &b0;
305 /* Find end of list. */
307 p = !((*p)->sense) ? &JT(*p) : &JF(*p);
309 /* Concatenate the lists. */
317 backpatch(p, gen_retblk(snaplen));
318 p->sense = !p->sense;
319 backpatch(p, gen_retblk(0));
325 struct block *b0, *b1;
327 backpatch(b0, b1->head);
328 b0->sense = !b0->sense;
329 b1->sense = !b1->sense;
331 b1->sense = !b1->sense;
337 struct block *b0, *b1;
339 b0->sense = !b0->sense;
340 backpatch(b0, b1->head);
341 b0->sense = !b0->sense;
350 b->sense = !b->sense;
353 static struct block *
354 gen_cmp(offset, size, v)
355 unsigned int offset, size;
361 s = new_stmt(BPF_LD|BPF_ABS|size);
364 b = new_block(JMP(BPF_JEQ));
371 static struct block *
372 gen_mcmp(offset, size, v, mask)
373 unsigned int offset, size;
377 struct block *b = gen_cmp(offset, size, v);
380 if (mask != 0xffffffff) {
381 s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
389 static struct block *
390 gen_bcmp(offset, size, v)
391 unsigned int offset, size;
394 struct block *b, *tmp;
398 unsigned char *p = &v[size - 4];
399 long w = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
400 tmp = gen_cmp(offset + size - 4, BPF_W, w);
407 unsigned char *p = &v[size - 2];
408 long w = (p[0] << 8) | p[1];
409 tmp = gen_cmp(offset + size - 2, BPF_H, w);
416 tmp = gen_cmp(offset, BPF_B, (long)v[0]);
426 * Various code constructs need to know the layout of the data link
427 * layer. These variables give the necessary offsets. off_linktype
428 * is set to -1 for no encapsulation, in which case, IP is assumed.
430 static unsigned int off_linktype;
431 static unsigned int off_nl;
440 static struct block *
447 s = new_stmt(BPF_LD|BPF_IMM);
449 b = new_block(JMP(BPF_JEQ));
455 static inline struct block *
458 return gen_uncond(1);
461 static inline struct block *
464 return gen_uncond(0);
467 static struct block *
471 return gen_cmp(off_linktype, BPF_H, (long)proto);
474 static struct block *
475 gen_hostop(addr, mask, dir, proto, src_off, dst_off)
479 unsigned int src_off, dst_off;
481 struct block *b0, *b1;
495 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
496 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
502 b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
503 b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
510 b0 = gen_linktype(proto);
511 b1 = gen_mcmp(offset, BPF_W, (long)addr, mask);
516 static struct block *
517 gen_host(addr, mask, proto, dir)
528 b0 = gen_host(addr, mask, Q_IP, dir);
532 return gen_hostop(addr, mask, dir, PPP_IP,
533 off_nl + 12, off_nl + 16);
536 bpf_error("'tcp' modifier applied to host");
539 bpf_error("'udp' modifier applied to host");
542 bpf_error("'icmp' modifier applied to host");
551 gen_proto_abbrev(proto)
554 struct block *b0, *b1;
559 b0 = gen_linktype(PPP_IP);
560 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_TCP);
565 b0 = gen_linktype(PPP_IP);
566 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_UDP);
571 b0 = gen_linktype(PPP_IP);
572 b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_ICMP);
577 b1 = gen_linktype(PPP_IP);
581 bpf_error("link layer applied in wrong context");
589 static struct block *
596 s = new_stmt(BPF_LD|BPF_H|BPF_ABS);
598 b = new_block(JMP(BPF_JSET));
606 static struct block *
614 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
617 s->next = new_stmt(BPF_LD|BPF_IND|BPF_H);
618 s->next->s.k = off_nl + off;
620 b = new_block(JMP(BPF_JEQ));
628 gen_portop(port, proto, dir)
629 int port, proto, dir;
631 struct block *b0, *b1, *tmp;
633 /* ip proto 'proto' */
634 tmp = gen_cmp(off_nl + 9, BPF_B, (long)proto);
640 b1 = gen_portatom(0, (long)port);
644 b1 = gen_portatom(2, (long)port);
649 tmp = gen_portatom(0, (long)port);
650 b1 = gen_portatom(2, (long)port);
655 tmp = gen_portatom(0, (long)port);
656 b1 = gen_portatom(2, (long)port);
668 static struct block *
669 gen_port(port, ip_proto, dir)
674 struct block *b0, *b1, *tmp;
677 b0 = gen_linktype(PPP_IP);
682 b1 = gen_portop(port, ip_proto, dir);
686 tmp = gen_portop(port, IPPROTO_TCP, dir);
687 b1 = gen_portop(port, IPPROTO_UDP, dir);
699 lookup_proto(name, proto)
708 v = pcap_nametoproto(name);
709 if (v == PROTO_UNDEF)
710 bpf_error("unknown ip proto '%s'", name);
714 /* XXX should look up h/w protocol type based on linktype */
715 v = pcap_nametopppproto(name);
716 if (v == PROTO_UNDEF)
717 bpf_error("unknown PPP proto '%s'", name);
727 static struct block *
728 gen_proto(v, proto, dir)
733 struct block *b0, *b1;
735 if (dir != Q_DEFAULT)
736 bpf_error("direction applied to 'proto'");
741 b0 = gen_linktype(PPP_IP);
742 b1 = gen_cmp(off_nl + 9, BPF_B, (long)v);
747 return gen_linktype(v);
750 bpf_error("'udp proto' is bogus");
754 bpf_error("'tcp proto' is bogus");
758 bpf_error("'icmp proto' is bogus");
769 * Left justify 'addr' and return its resulting network mask.
775 register unsigned long m = 0xffffffff;
778 while ((*addr & 0xff000000) == 0)
779 *addr <<= 8, m <<= 8;
791 unsigned long mask, addr, **alist;
792 struct block *b, *tmp;
793 int port, real_proto;
798 addr = pcap_nametonetaddr(name);
800 bpf_error("unknown network '%s'", name);
801 mask = net_mask(&addr);
802 return gen_host(addr, mask, proto, dir);
806 if (proto == Q_LINK) {
807 bpf_error("link-level host name not supported");
810 alist = pcap_nametoaddr(name);
811 if (alist == NULL || *alist == NULL)
812 bpf_error("unknown host '%s'", name);
813 b = gen_host(**alist++, 0xffffffffL, proto, dir);
815 tmp = gen_host(**alist++, 0xffffffffL,
824 if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP)
825 bpf_error("illegal qualifier of 'port'");
826 if (pcap_nametoport(name, &port, &real_proto) == 0)
827 bpf_error("unknown port '%s'", name);
828 if (proto == Q_UDP) {
829 if (real_proto == IPPROTO_TCP)
830 bpf_error("port '%s' is tcp", name);
832 /* override PROTO_UNDEF */
833 real_proto = IPPROTO_UDP;
835 if (proto == Q_TCP) {
836 if (real_proto == IPPROTO_UDP)
837 bpf_error("port '%s' is udp", name);
839 /* override PROTO_UNDEF */
840 real_proto = IPPROTO_TCP;
842 return gen_port(port, real_proto, dir);
845 real_proto = lookup_proto(name, proto);
847 return gen_proto(real_proto, proto, dir);
849 bpf_error("unknown protocol: %s", name);
873 if (proto == Q_LINK) {
874 bpf_error("illegal link layer address");
877 return gen_host(v, mask, proto, dir);
883 else if (proto == Q_TCP)
885 else if (proto == Q_DEFAULT)
888 bpf_error("illegal qualifier of 'port'");
890 return gen_port((int)v, proto, dir);
893 return gen_proto((int)v, proto, dir);
908 struct slist *s0, *s1;
911 * This is definitely not the best way to do this, but the
912 * lists will rarely get long.
919 static struct slist *
925 s = new_stmt(BPF_LDX|BPF_MEM);
930 static struct slist *
936 s = new_stmt(BPF_LD|BPF_MEM);
942 gen_load(proto, index, size)
947 struct slist *s, *tmp;
949 int regno = alloc_reg();
951 free_reg(index->regno);
955 bpf_error("data size must be 1, 2, or 4");
971 bpf_error("unsupported index operation");
974 s = xfer_to_x(index);
975 tmp = new_stmt(BPF_LD|BPF_IND|size);
977 sappend(index->s, s);
981 /* XXX Note that we assume a fixed link link header here. */
982 s = xfer_to_x(index);
983 tmp = new_stmt(BPF_LD|BPF_IND|size);
986 sappend(index->s, s);
988 b = gen_proto_abbrev(proto);
990 gen_and(index->b, b);
997 s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
999 sappend(s, xfer_to_a(index));
1000 sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X));
1001 sappend(s, new_stmt(BPF_MISC|BPF_TAX));
1002 sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size));
1004 sappend(index->s, s);
1006 gen_and(gen_proto_abbrev(proto), b = gen_ipfrag());
1008 gen_and(index->b, b);
1012 index->regno = regno;
1013 s = new_stmt(BPF_ST);
1015 sappend(index->s, s);
1021 gen_relation(code, a0, a1, reversed)
1023 struct arth *a0, *a1;
1026 struct slist *s0, *s1, *s2;
1027 struct block *b, *tmp;
1031 s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X);
1032 b = new_block(JMP(code));
1039 sappend(a0->s, a1->s);
1043 free_reg(a0->regno);
1044 free_reg(a1->regno);
1046 /* 'and' together protocol checks */
1049 gen_and(a0->b, tmp = a1->b);
1065 int regno = alloc_reg();
1066 struct arth *a = (struct arth *)newchunk(sizeof(*a));
1069 s = new_stmt(BPF_LD|BPF_LEN);
1070 s->next = new_stmt(BPF_ST);
1071 s->next->s.k = regno;
1086 a = (struct arth *)newchunk(sizeof(*a));
1090 s = new_stmt(BPF_LD|BPF_IMM);
1092 s->next = new_stmt(BPF_ST);
1108 s = new_stmt(BPF_ALU|BPF_NEG);
1111 s = new_stmt(BPF_ST);
1119 gen_arth(code, a0, a1)
1121 struct arth *a0, *a1;
1123 struct slist *s0, *s1, *s2;
1127 s2 = new_stmt(BPF_ALU|BPF_X|code);
1132 sappend(a0->s, a1->s);
1134 free_reg(a1->regno);
1136 s0 = new_stmt(BPF_ST);
1137 a0->regno = s0->s.k = alloc_reg();
1144 * Here we handle simple allocation of the scratch registers.
1145 * If too many registers are alloc'd, the allocator punts.
1147 static int regused[BPF_MEMWORDS];
1151 * Return the next free register.
1156 int n = BPF_MEMWORDS;
1159 if (regused[curreg])
1160 curreg = (curreg + 1) % BPF_MEMWORDS;
1162 regused[curreg] = 1;
1166 bpf_error("too many registers needed to evaluate expression");
1171 * Return a register to the table so it can
1181 static struct block *
1188 s = new_stmt(BPF_LD|BPF_LEN);
1189 s->next = new_stmt(BPF_ALU|BPF_SUB|BPF_K);
1191 b = new_block(JMP(jmp));
1201 return gen_len(BPF_JGE, n);
1210 b = gen_len(BPF_JGT, n);
1217 gen_byteop(op, idx, val)
1228 return gen_cmp((unsigned int)idx, BPF_B, (long)val);
1231 b = gen_cmp((unsigned int)idx, BPF_B, (long)val);
1232 b->s.code = JMP(BPF_JGE);
1237 b = gen_cmp((unsigned int)idx, BPF_B, (long)val);
1238 b->s.code = JMP(BPF_JGT);
1242 s = new_stmt(BPF_ALU|BPF_OR|BPF_K);
1246 s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
1250 b = new_block(JMP(BPF_JEQ));
1258 gen_broadcast(proto)
1261 bpf_error("broadcast not supported");
1265 gen_multicast(proto)
1268 register struct block *b0, *b1;
1273 b0 = gen_linktype(PPP_IP);
1274 b1 = gen_cmp(off_nl + 16, BPF_B, (long)224);
1275 b1->s.code = JMP(BPF_JGE);
1279 bpf_error("only IP multicast filters supported");
1283 * generate command for inbound/outbound. It's here so we can
1284 * make it link-type specific. 'dir' = 0 implies "inbound",
1285 * = 1 implies "outbound".
1291 register struct block *b0;
1293 b0 = gen_relation(BPF_JEQ,
1294 gen_load(Q_LINK, gen_loadi(0), 1),