NetBSD/usr.sbin/pppd/gencode.c

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/* From NetBSD: gencode.c,v 1.2 1995/03/06 11:38:21 mycroft Exp */
/*
* Copyright (c) 1990, 1991, 1992, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char rcsid[] =
"@(#) Header: gencode.c,v 1.55 94/06/20 19:07:53 leres Exp (LBL)";
#endif
#include <stdio.h>
#include <memory.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <net/ppp_defs.h>
#include <netinet/in.h>
#include "bpf_compile.h"
#include "gencode.h"
#include <setjmp.h>
#ifdef __STDC__
#include <stdarg.h>
#include <stdlib.h>
#else
#include <varargs.h>
#endif
#ifndef __GNUC__
#define inline
#endif
#define JMP(c) ((c)|BPF_JMP|BPF_K)
static jmp_buf top_ctx;
static char errbuf[PCAP_ERRBUF_SIZE];
/* VARARGS */
volatile void
#ifdef __STDC__
bpf_error(char *fmt, ...)
#else
bpf_error(fmt, va_alist)
char *fmt;
va_dcl
#endif
{
va_list ap;
#ifdef __STDC__
va_start(ap, fmt);
#else
va_start(ap);
#endif
vsprintf(errbuf, fmt, ap);
va_end(ap);
longjmp(top_ctx, 1);
/* NOTREACHED */
}
char *
bpf_geterr()
{
return errbuf;
}
static void init_linktype();
static int alloc_reg(void);
static void free_reg(int);
static struct block *root;
/*
* We divy out chunks of memory rather than call malloc each time so
* we don't have to worry about leaking memory. It's probably
* not a big deal if all this memory was wasted but it this ever
* goes into a library that would probably not be a good idea.
*/
#define NCHUNKS 16
#define CHUNK0SIZE 1024
struct chunk {
u_int n_left;
void *m;
};
static struct chunk chunks[NCHUNKS];
static int cur_chunk = -1;
static void *newchunk(u_int);
static void freechunks(void);
static inline struct block *new_block(int);
static inline struct slist *new_stmt(int);
static struct block *gen_retblk(int);
static inline void syntax(void);
static void backpatch(struct block *, struct block *);
static void merge(struct block *, struct block *);
static struct block *gen_cmp(u_int, u_int, long);
static struct block *gen_mcmp(u_int, u_int, long, u_long);
#if 0
static struct block *gen_bcmp(u_int, u_int, u_char *);
#endif
static struct block *gen_uncond(int);
static inline struct block *gen_true(void);
static inline struct block *gen_false(void);
static struct block *gen_linktype(int);
static struct block *gen_hostop(u_long, u_long, int, int, u_int, u_int);
static struct block *gen_host(u_long, u_long, int, int);
static struct block *gen_ipfrag(void);
static struct block *gen_portatom(int, long);
struct block *gen_portop(int, int, int);
static struct block *gen_port(int, int, int);
static int lookup_proto(char *, int);
static struct block *gen_proto(int, int, int);
static u_long net_mask(u_long *);
static u_long net_mask(u_long *);
static struct slist *xfer_to_x(struct arth *);
static struct slist *xfer_to_a(struct arth *);
static struct block *gen_len(int, int);
static void *
newchunk(n)
u_int n;
{
struct chunk *cp;
int size;
/* XXX Round up to nearest long. */
n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
cp = &chunks[cur_chunk];
if (cur_chunk < 0 || n > cp->n_left) {
if (++cur_chunk >= NCHUNKS)
bpf_error("out of memory");
cp = &chunks[cur_chunk];
size = CHUNK0SIZE << cur_chunk;
cp->m = (void *)malloc(size);
if (cp->m == 0 || n > size)
bpf_error("out of memory");
memset((char *)cp->m, 0, size);
cp->n_left = size;
}
cp->n_left -= n;
return (void *)((char *)cp->m + cp->n_left);
}
static void
freechunks()
{
int i;
for (i = 0; i < NCHUNKS; ++i)
if (chunks[i].m)
free(chunks[i].m);
cur_chunk = -1;
}
/*
* A strdup whose allocations are freed after code generation is over.
*/
char *
sdup(s)
char *s;
{
int n = strlen(s) + 1;
char *cp = newchunk(n);
strcpy(cp, s);
return (cp);
}
static inline struct block *
new_block(code)
int code;
{
struct block *p;
p = (struct block *)newchunk(sizeof(*p));
p->s.code = code;
p->head = p;
return p;
}
static inline struct slist *
new_stmt(code)
int code;
{
struct slist *p;
p = (struct slist *)newchunk(sizeof(*p));
p->s.code = code;
return p;
}
static struct block *
gen_retblk(v)
int v;
{
struct block *b = new_block(BPF_RET|BPF_K);
b->s.k = v;
return b;
}
static inline void
syntax()
{
bpf_error("syntax error in filter expression");
}
static int snaplen;
int
bpf_compile(program, buf, optimize)
struct bpf_program *program;
char *buf;
int optimize;
{
extern int n_errors;
int len;
if (setjmp(top_ctx))
return (-1);
snaplen = PPP_HDRLEN;
lex_init(buf ? buf : "");
init_linktype();
pcap_parse();
if (n_errors)
syntax();
if (root == NULL)
root = gen_retblk(snaplen);
if (optimize) {
bpf_optimize(&root);
if (root == NULL ||
(root->s.code == (BPF_RET|BPF_K) && root->s.k == 0))
bpf_error("expression rejects all packets");
}
program->bf_insns = icode_to_fcode(root, &len);
program->bf_len = len;
freechunks();
return (0);
}
/*
* Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates
* which of the jt and jf fields has been resolved and which is a pointer
* back to another unresolved block (or nil). At least one of the fields
* in each block is already resolved.
*/
static void
backpatch(list, target)
struct block *list, *target;
{
struct block *next;
while (list) {
if (!list->sense) {
next = JT(list);
JT(list) = target;
} else {
next = JF(list);
JF(list) = target;
}
list = next;
}
}
/*
* Merge the lists in b0 and b1, using the 'sense' field to indicate
* which of jt and jf is the link.
*/
static void
merge(b0, b1)
struct block *b0, *b1;
{
register struct block **p = &b0;
/* Find end of list. */
while (*p)
p = !((*p)->sense) ? &JT(*p) : &JF(*p);
/* Concatenate the lists. */
*p = b1;
}
void
finish_parse(p)
struct block *p;
{
backpatch(p, gen_retblk(snaplen));
p->sense = !p->sense;
backpatch(p, gen_retblk(0));
root = p->head;
}
void
gen_and(b0, b1)
struct block *b0, *b1;
{
backpatch(b0, b1->head);
b0->sense = !b0->sense;
b1->sense = !b1->sense;
merge(b1, b0);
b1->sense = !b1->sense;
b1->head = b0->head;
}
void
gen_or(b0, b1)
struct block *b0, *b1;
{
b0->sense = !b0->sense;
backpatch(b0, b1->head);
b0->sense = !b0->sense;
merge(b1, b0);
b1->head = b0->head;
}
void
gen_not(b)
struct block *b;
{
b->sense = !b->sense;
}
static struct block *
gen_cmp(offset, size, v)
unsigned int offset, size;
long v;
{
struct slist *s;
struct block *b;
s = new_stmt(BPF_LD|BPF_ABS|size);
s->s.k = offset;
b = new_block(JMP(BPF_JEQ));
b->stmts = s;
b->s.k = v;
return b;
}
static struct block *
gen_mcmp(offset, size, v, mask)
unsigned int offset, size;
long v;
unsigned long mask;
{
struct block *b = gen_cmp(offset, size, v);
struct slist *s;
if (mask != 0xffffffff) {
s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
s->s.k = mask;
b->stmts->next = s;
}
return b;
}
#if 0
static struct block *
gen_bcmp(offset, size, v)
unsigned int offset, size;
unsigned char *v;
{
struct block *b, *tmp;
b = NULL;
while (size >= 4) {
unsigned char *p = &v[size - 4];
long w = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
tmp = gen_cmp(offset + size - 4, BPF_W, w);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
size -= 4;
}
while (size >= 2) {
unsigned char *p = &v[size - 2];
long w = (p[0] << 8) | p[1];
tmp = gen_cmp(offset + size - 2, BPF_H, w);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
size -= 2;
}
if (size > 0) {
tmp = gen_cmp(offset, BPF_B, (long)v[0]);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
}
return b;
}
#endif
/*
* Various code constructs need to know the layout of the data link
* layer. These variables give the necessary offsets. off_linktype
* is set to -1 for no encapsulation, in which case, IP is assumed.
*/
static unsigned int off_linktype;
static unsigned int off_nl;
static void
init_linktype()
{
off_linktype = 2;
off_nl = 4;
}
static struct block *
gen_uncond(rsense)
int rsense;
{
struct block *b;
struct slist *s;
s = new_stmt(BPF_LD|BPF_IMM);
s->s.k = !rsense;
b = new_block(JMP(BPF_JEQ));
b->stmts = s;
return b;
}
static inline struct block *
gen_true()
{
return gen_uncond(1);
}
static inline struct block *
gen_false()
{
return gen_uncond(0);
}
static struct block *
gen_linktype(proto)
int proto;
{
return gen_cmp(off_linktype, BPF_H, (long)proto);
}
static struct block *
gen_hostop(addr, mask, dir, proto, src_off, dst_off)
unsigned long addr;
unsigned long mask;
int dir, proto;
unsigned int src_off, dst_off;
{
struct block *b0, *b1;
unsigned int offset;
switch (dir) {
case Q_SRC:
offset = src_off;
break;
case Q_DST:
offset = dst_off;
break;
case Q_AND:
b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
gen_and(b0, b1);
return b1;
case Q_OR:
case Q_DEFAULT:
b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off);
b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off);
gen_or(b0, b1);
return b1;
default:
abort();
}
b0 = gen_linktype(proto);
b1 = gen_mcmp(offset, BPF_W, (long)addr, mask);
gen_and(b0, b1);
return b1;
}
static struct block *
gen_host(addr, mask, proto, dir)
unsigned long addr;
unsigned long mask;
int proto;
int dir;
{
struct block *b0;
switch (proto) {
case Q_DEFAULT:
b0 = gen_host(addr, mask, Q_IP, dir);
return b0;
case Q_IP:
return gen_hostop(addr, mask, dir, PPP_IP,
off_nl + 12, off_nl + 16);
case Q_TCP:
bpf_error("'tcp' modifier applied to host");
case Q_UDP:
bpf_error("'udp' modifier applied to host");
case Q_ICMP:
bpf_error("'icmp' modifier applied to host");
default:
abort();
}
/* NOTREACHED */
}
struct block *
gen_proto_abbrev(proto)
int proto;
{
struct block *b0, *b1;
switch (proto) {
case Q_TCP:
b0 = gen_linktype(PPP_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_TCP);
gen_and(b0, b1);
break;
case Q_UDP:
b0 = gen_linktype(PPP_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_UDP);
gen_and(b0, b1);
break;
case Q_ICMP:
b0 = gen_linktype(PPP_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_ICMP);
gen_and(b0, b1);
break;
case Q_IP:
b1 = gen_linktype(PPP_IP);
break;
case Q_LINK:
bpf_error("link layer applied in wrong context");
default:
abort();
}
return b1;
}
static struct block *
gen_ipfrag()
{
struct slist *s;
struct block *b;
/* not ip frag */
s = new_stmt(BPF_LD|BPF_H|BPF_ABS);
s->s.k = off_nl + 6;
b = new_block(JMP(BPF_JSET));
b->s.k = 0x1fff;
b->stmts = s;
gen_not(b);
return b;
}
static struct block *
gen_portatom(off, v)
int off;
long v;
{
struct slist *s;
struct block *b;
s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
s->s.k = off_nl;
s->next = new_stmt(BPF_LD|BPF_IND|BPF_H);
s->next->s.k = off_nl + off;
b = new_block(JMP(BPF_JEQ));
b->stmts = s;
b->s.k = v;
return b;
}
struct block *
gen_portop(port, proto, dir)
int port, proto, dir;
{
struct block *b0, *b1, *tmp;
/* ip proto 'proto' */
tmp = gen_cmp(off_nl + 9, BPF_B, (long)proto);
b0 = gen_ipfrag();
gen_and(tmp, b0);
switch (dir) {
case Q_SRC:
b1 = gen_portatom(0, (long)port);
break;
case Q_DST:
b1 = gen_portatom(2, (long)port);
break;
case Q_OR:
case Q_DEFAULT:
tmp = gen_portatom(0, (long)port);
b1 = gen_portatom(2, (long)port);
gen_or(tmp, b1);
break;
case Q_AND:
tmp = gen_portatom(0, (long)port);
b1 = gen_portatom(2, (long)port);
gen_and(tmp, b1);
break;
default:
abort();
}
gen_and(b0, b1);
return b1;
}
static struct block *
gen_port(port, ip_proto, dir)
int port;
int ip_proto;
int dir;
{
struct block *b0, *b1, *tmp;
/* PPP proto ip */
b0 = gen_linktype(PPP_IP);
switch (ip_proto) {
case IPPROTO_UDP:
case IPPROTO_TCP:
b1 = gen_portop(port, ip_proto, dir);
break;
case PROTO_UNDEF:
tmp = gen_portop(port, IPPROTO_TCP, dir);
b1 = gen_portop(port, IPPROTO_UDP, dir);
gen_or(tmp, b1);
break;
default:
abort();
}
gen_and(b0, b1);
return b1;
}
static int
lookup_proto(name, proto)
char *name;
int proto;
{
int v;
switch (proto) {
case Q_DEFAULT:
case Q_IP:
v = pcap_nametoproto(name);
if (v == PROTO_UNDEF)
bpf_error("unknown ip proto '%s'", name);
break;
case Q_LINK:
/* XXX should look up h/w protocol type based on linktype */
v = pcap_nametopppproto(name);
if (v == PROTO_UNDEF)
bpf_error("unknown PPP proto '%s'", name);
break;
default:
v = PROTO_UNDEF;
break;
}
return v;
}
static struct block *
gen_proto(v, proto, dir)
int v;
int proto;
int dir;
{
struct block *b0, *b1;
if (dir != Q_DEFAULT)
bpf_error("direction applied to 'proto'");
switch (proto) {
case Q_DEFAULT:
case Q_IP:
b0 = gen_linktype(PPP_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)v);
gen_and(b0, b1);
return b1;
case Q_LINK:
return gen_linktype(v);
case Q_UDP:
bpf_error("'udp proto' is bogus");
/* NOTREACHED */
case Q_TCP:
bpf_error("'tcp proto' is bogus");
/* NOTREACHED */
case Q_ICMP:
bpf_error("'icmp proto' is bogus");
/* NOTREACHED */
default:
abort();
/* NOTREACHED */
}
/* NOTREACHED */
}
/*
* Left justify 'addr' and return its resulting network mask.
*/
static unsigned long
net_mask(addr)
unsigned long *addr;
{
register unsigned long m = 0xffffffff;
if (*addr)
while ((*addr & 0xff000000) == 0)
*addr <<= 8, m <<= 8;
return m;
}
struct block *
gen_scode(name, q)
char *name;
struct qual q;
{
int proto = q.proto;
int dir = q.dir;
unsigned long mask, addr, **alist;
struct block *b, *tmp;
int port, real_proto;
switch (q.addr) {
case Q_NET:
addr = pcap_nametonetaddr(name);
if (addr == 0)
bpf_error("unknown network '%s'", name);
mask = net_mask(&addr);
return gen_host(addr, mask, proto, dir);
case Q_DEFAULT:
case Q_HOST:
if (proto == Q_LINK) {
bpf_error("link-level host name not supported");
break;
} else {
alist = pcap_nametoaddr(name);
if (alist == NULL || *alist == NULL)
bpf_error("unknown host '%s'", name);
b = gen_host(**alist++, 0xffffffffL, proto, dir);
while (*alist) {
tmp = gen_host(**alist++, 0xffffffffL,
proto, dir);
gen_or(b, tmp);
b = tmp;
}
return b;
}
case Q_PORT:
if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP)
bpf_error("illegal qualifier of 'port'");
if (pcap_nametoport(name, &port, &real_proto) == 0)
bpf_error("unknown port '%s'", name);
if (proto == Q_UDP) {
if (real_proto == IPPROTO_TCP)
bpf_error("port '%s' is tcp", name);
else
/* override PROTO_UNDEF */
real_proto = IPPROTO_UDP;
}
if (proto == Q_TCP) {
if (real_proto == IPPROTO_UDP)
bpf_error("port '%s' is udp", name);
else
/* override PROTO_UNDEF */
real_proto = IPPROTO_TCP;
}
return gen_port(port, real_proto, dir);
case Q_PROTO:
real_proto = lookup_proto(name, proto);
if (real_proto >= 0)
return gen_proto(real_proto, proto, dir);
else
bpf_error("unknown protocol: %s", name);
case Q_UNDEF:
syntax();
/* NOTREACHED */
}
abort();
/* NOTREACHED */
}
struct block *
gen_ncode(v, q)
unsigned long v;
struct qual q;
{
unsigned long mask;
int proto = q.proto;
int dir = q.dir;
switch (q.addr) {
case Q_DEFAULT:
case Q_HOST:
case Q_NET:
if (proto == Q_LINK) {
bpf_error("illegal link layer address");
} else {
mask = net_mask(&v);
return gen_host(v, mask, proto, dir);
}
case Q_PORT:
if (proto == Q_UDP)
proto = IPPROTO_UDP;
else if (proto == Q_TCP)
proto = IPPROTO_TCP;
else if (proto == Q_DEFAULT)
proto = PROTO_UNDEF;
else
bpf_error("illegal qualifier of 'port'");
return gen_port((int)v, proto, dir);
case Q_PROTO:
return gen_proto((int)v, proto, dir);
case Q_UNDEF:
syntax();
/* NOTREACHED */
default:
abort();
/* NOTREACHED */
}
/* NOTREACHED */
}
void
sappend(s0, s1)
struct slist *s0, *s1;
{
/*
* This is definitely not the best way to do this, but the
* lists will rarely get long.
*/
while (s0->next)
s0 = s0->next;
s0->next = s1;
}
static struct slist *
xfer_to_x(a)
struct arth *a;
{
struct slist *s;
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = a->regno;
return s;
}
static struct slist *
xfer_to_a(a)
struct arth *a;
{
struct slist *s;
s = new_stmt(BPF_LD|BPF_MEM);
s->s.k = a->regno;
return s;
}
struct arth *
gen_load(proto, index, size)
int proto;
struct arth *index;
int size;
{
struct slist *s, *tmp;
struct block *b;
int regno = alloc_reg();
free_reg(index->regno);
switch (size) {
default:
bpf_error("data size must be 1, 2, or 4");
case 1:
size = BPF_B;
break;
case 2:
size = BPF_H;
break;
case 4:
size = BPF_W;
break;
}
switch (proto) {
default:
bpf_error("unsupported index operation");
case Q_LINK:
s = xfer_to_x(index);
tmp = new_stmt(BPF_LD|BPF_IND|size);
sappend(s, tmp);
sappend(index->s, s);
break;
case Q_IP:
/* XXX Note that we assume a fixed link link header here. */
s = xfer_to_x(index);
tmp = new_stmt(BPF_LD|BPF_IND|size);
tmp->s.k = off_nl;
sappend(s, tmp);
sappend(index->s, s);
b = gen_proto_abbrev(proto);
if (index->b)
gen_and(index->b, b);
index->b = b;
break;
case Q_TCP:
case Q_UDP:
case Q_ICMP:
s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
s->s.k = off_nl;
sappend(s, xfer_to_a(index));
sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X));
sappend(s, new_stmt(BPF_MISC|BPF_TAX));
sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size));
tmp->s.k = off_nl;
sappend(index->s, s);
gen_and(gen_proto_abbrev(proto), b = gen_ipfrag());
if (index->b)
gen_and(index->b, b);
index->b = b;
break;
}
index->regno = regno;
s = new_stmt(BPF_ST);
s->s.k = regno;
sappend(index->s, s);
return index;
}
struct block *
gen_relation(code, a0, a1, reversed)
int code;
struct arth *a0, *a1;
int reversed;
{
struct slist *s0, *s1, *s2;
struct block *b, *tmp;
s0 = xfer_to_x(a1);
s1 = xfer_to_a(a0);
s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X);
b = new_block(JMP(code));
if (reversed)
gen_not(b);
sappend(s1, s2);
sappend(s0, s1);
sappend(a1->s, s0);
sappend(a0->s, a1->s);
b->stmts = a0->s;
free_reg(a0->regno);
free_reg(a1->regno);
/* 'and' together protocol checks */
if (a0->b) {
if (a1->b) {
gen_and(a0->b, tmp = a1->b);
}
else
tmp = a0->b;
} else
tmp = a1->b;
if (tmp)
gen_and(tmp, b);
return b;
}
struct arth *
gen_loadlen()
{
int regno = alloc_reg();
struct arth *a = (struct arth *)newchunk(sizeof(*a));
struct slist *s;
s = new_stmt(BPF_LD|BPF_LEN);
s->next = new_stmt(BPF_ST);
s->next->s.k = regno;
a->s = s;
a->regno = regno;
return a;
}
struct arth *
gen_loadi(val)
int val;
{
struct arth *a;
struct slist *s;
int reg;
a = (struct arth *)newchunk(sizeof(*a));
reg = alloc_reg();
s = new_stmt(BPF_LD|BPF_IMM);
s->s.k = val;
s->next = new_stmt(BPF_ST);
s->next->s.k = reg;
a->s = s;
a->regno = reg;
return a;
}
struct arth *
gen_neg(a)
struct arth *a;
{
struct slist *s;
s = xfer_to_a(a);
sappend(a->s, s);
s = new_stmt(BPF_ALU|BPF_NEG);
s->s.k = 0;
sappend(a->s, s);
s = new_stmt(BPF_ST);
s->s.k = a->regno;
sappend(a->s, s);
return a;
}
struct arth *
gen_arth(code, a0, a1)
int code;
struct arth *a0, *a1;
{
struct slist *s0, *s1, *s2;
s0 = xfer_to_x(a1);
s1 = xfer_to_a(a0);
s2 = new_stmt(BPF_ALU|BPF_X|code);
sappend(s1, s2);
sappend(s0, s1);
sappend(a1->s, s0);
sappend(a0->s, a1->s);
free_reg(a1->regno);
s0 = new_stmt(BPF_ST);
a0->regno = s0->s.k = alloc_reg();
sappend(a0->s, s0);
return a0;
}
/*
* Here we handle simple allocation of the scratch registers.
* If too many registers are alloc'd, the allocator punts.
*/
static int regused[BPF_MEMWORDS];
static int curreg;
/*
* Return the next free register.
*/
static int
alloc_reg()
{
int n = BPF_MEMWORDS;
while (--n >= 0) {
if (regused[curreg])
curreg = (curreg + 1) % BPF_MEMWORDS;
else {
regused[curreg] = 1;
return curreg;
}
}
bpf_error("too many registers needed to evaluate expression");
/* NOTREACHED */
}
/*
* Return a register to the table so it can
* be used later.
*/
static void
free_reg(n)
int n;
{
regused[n] = 0;
}
static struct block *
gen_len(jmp, n)
int jmp, n;
{
struct slist *s;
struct block *b;
s = new_stmt(BPF_LD|BPF_LEN);
s->next = new_stmt(BPF_ALU|BPF_SUB|BPF_K);
s->next->s.k = n;
b = new_block(JMP(jmp));
b->stmts = s;
return b;
}
struct block *
gen_greater(n)
int n;
{
return gen_len(BPF_JGE, n);
}
struct block *
gen_less(n)
int n;
{
struct block *b;
b = gen_len(BPF_JGT, n);
gen_not(b);
return b;
}
struct block *
gen_byteop(op, idx, val)
int op, idx, val;
{
struct block *b;
struct slist *s;
switch (op) {
default:
abort();
case '=':
return gen_cmp((unsigned int)idx, BPF_B, (long)val);
case '<':
b = gen_cmp((unsigned int)idx, BPF_B, (long)val);
b->s.code = JMP(BPF_JGE);
gen_not(b);
return b;
case '>':
b = gen_cmp((unsigned int)idx, BPF_B, (long)val);
b->s.code = JMP(BPF_JGT);
return b;
case '|':
s = new_stmt(BPF_ALU|BPF_OR|BPF_K);
break;
case '&':
s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
break;
}
s->s.k = val;
b = new_block(JMP(BPF_JEQ));
b->stmts = s;
gen_not(b);
return b;
}
struct block *
gen_broadcast(proto)
int proto;
{
bpf_error("broadcast not supported");
}
struct block *
gen_multicast(proto)
int proto;
{
register struct block *b0, *b1;
switch (proto) {
case Q_DEFAULT:
case Q_IP:
b0 = gen_linktype(PPP_IP);
b1 = gen_cmp(off_nl + 16, BPF_B, (long)224);
b1->s.code = JMP(BPF_JGE);
gen_and(b0, b1);
return b1;
}
bpf_error("only IP multicast filters supported");
}
/*
* generate command for inbound/outbound. It's here so we can
* make it link-type specific. 'dir' = 0 implies "inbound",
* = 1 implies "outbound".
*/
struct block *
gen_inbound(dir)
int dir;
{
register struct block *b0;
b0 = gen_relation(BPF_JEQ,
gen_load(Q_LINK, gen_loadi(0), 1),
gen_loadi(0),
dir);
return (b0);
}