/*
* Copyright (c) 1990 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: /usr/staff/martinh/tcpview/RCS/gencode.c,v 1.3 1993/04/22 20:20:45 martinh Exp $ ";
#endif
#ifdef __STDC__
#include <stdlib.h>
#endif
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <sys/time.h>
#include <net/bpf.h>
#ifdef TCPVIEW
#include <stdarg.h>
#include <setjmp.h>
static jmp_buf env;
#define error parse_error
void eprint();
#endif
#include "interface.h"
#include "gencode.h"
#include "nametoaddr.h"
#if defined(sparc) || defined(mips) || defined(ibm032)
#define BPF_ALIGN
#endif
#ifndef BPF_ALIGN
#define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
#define EXTRACT_LONG(p) (ntohl(*(u_long *)p))
#else
#define EXTRACT_SHORT(p)\
((u_short)\
((u_short)*((u_char *)p+0)<<8|\
(u_short)*((u_char *)p+1)<<0))
#define EXTRACT_LONG(p)\
((u_long)*((u_char *)p+0)<<24|\
(u_long)*((u_char *)p+1)<<16|\
(u_long)*((u_char *)p+2)<<8|\
(u_long)*((u_char *)p+3)<<0)
#endif
#define JMP(c) ((c)|BPF_JMP|BPF_K)
extern struct bpf_insn *icode_to_fcode();
extern u_long net_mask();
static void init_linktype();
static int alloc_reg();
static void free_reg();
static void free_all_reg();
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;
#ifdef TCPVIEW
extern eprintv(char *cp, va_list ap);
void parse_error(char *cp, ...)
{
va_list ap;
va_start(ap, cp);
eprintv(cp, ap);
va_end(ap);
longjmp(env,1);
}
#endif
static void *
newchunk(n)
u_int n;
{
struct chunk *cp;
int k, size;
/* XXX Round up to nearest long. */
n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
cp = &chunks[cur_chunk];
if (n > cp->n_left) {
++cp, k = ++cur_chunk;
if (k >= NCHUNKS)
error("out of memory");
size = CHUNK0SIZE << k;
cp->m = (void *)malloc(size);
bzero((char *)cp->m, size);
cp->n_left = size;
if (n > size)
error("out of memory");
}
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);
chunks[i].m=0;
chunks[i].n_left=0;
}
}
cur_chunk = 0;
}
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()
{
error("syntax error in filter expression");
}
static u_long netmask;
struct bpf_program *
parse(buf, Oflag, linktype, mask)
char *buf;
int Oflag;
int linktype;
u_long mask;
{
extern int n_errors;
static struct bpf_program F;
struct bpf_insn *p;
int len;
if( cur_chunk )
freechunks();
free_all_reg();
root = 0;
netmask = mask;
F.bf_insns = 0;
F.bf_len = 0;
lex_init(buf ? buf : "");
#ifdef TCPVIEW
/* if there is a problem, try again with no filter */
if( setjmp(env) ) {
lex_init("");
}
#endif
init_linktype(linktype);
yyparse();
if (n_errors)
syntax();
if (root == 0)
root = gen_retblk(snaplen);
if (Oflag) {
optimize(&root);
if (root == 0 ||
(root->s.code == (BPF_RET|BPF_K) && root->s.k == 0))
error("expression rejects all packets");
}
p = icode_to_fcode(root, &len);
F.bf_insns = p;
F.bf_len = len;
freechunks();
return &F;
}
/*
* 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)
u_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;
}
struct block *
gen_mcmp(offset, size, v, mask)
u_int offset, size;
long v;
u_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;
}
struct block *
gen_bcmp(offset, size, v)
u_int offset;
u_int size;
u_char *v;
{
struct block *b, *tmp;
int k;
b = 0;
while (size >= 4) {
k = size - 4;
tmp = gen_cmp(offset + k, BPF_W, EXTRACT_LONG(&v[k]));
if (b != 0)
gen_and(b, tmp);
b = tmp;
size -= 4;
}
while (size >= 2) {
k = size - 2;
tmp = gen_cmp(offset + k, BPF_H, (long)EXTRACT_SHORT(&v[k]));
if (b != 0)
gen_and(b, tmp);
b = tmp;
size -= 2;
}
if (size > 0) {
tmp = gen_cmp(offset, BPF_B, (long)v[0]);
if (b != 0)
gen_and(b, tmp);
b = tmp;
}
return b;
}
/*
* Various code contructs 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 u_int off_linktype;
static u_int off_nl;
static int linktype;
static void
init_linktype(type)
int type;
{
linktype = type;
switch (type) {
case DLT_EN10MB:
off_linktype = 12;
off_nl = 14;
return;
case DLT_SLIP:
/*
* SLIP doesn't have a link level type. The 16 byte
* header is hacked into our SLIP driver.
*/
off_linktype = -1;
off_nl = 16;
return;
case DLT_NULL:
off_linktype = -1;
off_nl = 0;
return;
case DLT_PPP:
off_linktype = 2;
off_nl = 4;
return;
case DLT_FDDI:
off_linktype = 19;
off_nl = 21;
return;
case DLT_IEEE802:
off_linktype = 20;
off_nl = 22;
return;
}
error("unknown data link type 0x%x", linktype);
/* NOTREACHED */
}
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);
}
struct block *
gen_linktype(proto)
int proto;
{
switch (linktype) {
case DLT_SLIP:
if (proto == ETHERTYPE_IP)
return gen_true();
else
return gen_false();
case DLT_PPP:
if (proto == ETHERTYPE_IP)
proto = 0x0021; /* XXX - need ppp.h defs */
break;
}
return gen_cmp(off_linktype, BPF_H, (long)proto);
}
static struct block *
gen_hostop(addr, mask, dir, proto, src_off, dst_off)
u_long addr;
u_long mask;
int dir, proto;
u_int src_off, dst_off;
{
struct block *b0, *b1;
u_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_ehostop(eaddr, dir)
u_char *eaddr;
int dir;
{
struct block *b0, *b1;
switch (dir) {
case Q_SRC:
return gen_bcmp(6, 6, eaddr);
case Q_DST:
return gen_bcmp(0, 6, eaddr);
case Q_AND:
b0 = gen_ehostop(eaddr, Q_SRC);
b1 = gen_ehostop(eaddr, Q_DST);
gen_and(b0, b1);
return b1;
case Q_DEFAULT:
case Q_OR:
b0 = gen_ehostop(eaddr, Q_SRC);
b1 = gen_ehostop(eaddr, Q_DST);
gen_or(b0, b1);
return b1;
}
abort();
/* NOTREACHED */
}
static struct block *
gen_host(addr, mask, proto, dir)
u_long addr;
u_long mask;
int proto;
int dir;
{
struct block *b0, *b1;
switch (proto) {
case Q_DEFAULT:
b0 = gen_host(addr, mask, Q_IP, dir);
b1 = gen_host(addr, mask, Q_ARP, dir);
gen_or(b0, b1);
b0 = gen_host(addr, mask, Q_RARP, dir);
gen_or(b1, b0);
return b0;
case Q_IP:
return gen_hostop(addr, mask, dir, ETHERTYPE_IP,
off_nl + 12, off_nl + 16);
case Q_RARP:
return gen_hostop(addr, mask, dir, ETHERTYPE_REVARP,
off_nl + 14, off_nl + 24);
case Q_ARP:
return gen_hostop(addr, mask, dir, ETHERTYPE_ARP,
off_nl + 14, off_nl + 24);
case Q_TCP:
error("'tcp' modifier applied to host");
case Q_UDP:
error("'udp' modifier applied to host");
case Q_ICMP:
error("'icmp' modifier applied to host");
}
abort();
/* NOTREACHED */
}
static struct block *
gen_gateway(eaddr, alist, proto, dir)
u_char *eaddr;
u_long **alist;
int proto;
int dir;
{
struct block *b0, *b1, *tmp;
if (dir != 0)
error("direction applied to 'gateway'");
switch (proto) {
case Q_DEFAULT:
case Q_IP:
case Q_ARP:
case Q_RARP:
b0 = gen_ehostop(eaddr, Q_OR);
b1 = gen_host(**alist++, 0xffffffffL, proto, Q_OR);
while (*alist) {
tmp = gen_host(**alist++, 0xffffffffL, proto, Q_OR);
gen_or(b1, tmp);
b1 = tmp;
}
gen_not(b1);
gen_and(b0, b1);
return b1;
}
error("illegal modifier of 'gateway'");
/* NOTREACHED */
}
struct block *
gen_proto_abbrev(proto)
int proto;
{
struct block *b0, *b1;
switch (proto) {
case Q_TCP:
b0 = gen_linktype(ETHERTYPE_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_TCP);
gen_and(b0, b1);
break;
case Q_UDP:
b0 = gen_linktype(ETHERTYPE_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_UDP);
gen_and(b0, b1);
break;
case Q_ICMP:
b0 = gen_linktype(ETHERTYPE_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)IPPROTO_ICMP);
gen_and(b0, b1);
break;
case Q_IP:
b1 = gen_linktype(ETHERTYPE_IP);
break;
case Q_ARP:
b1 = gen_linktype(ETHERTYPE_ARP);
break;
case Q_RARP:
b1 = gen_linktype(ETHERTYPE_REVARP);
break;
case Q_LINK:
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;
int proto;
int 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;
/* ether proto ip */
b0 = gen_linktype(ETHERTYPE_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;
}
int
lookup_proto(name, proto)
char *name;
int proto;
{
int v;
switch (proto) {
case Q_DEFAULT:
case Q_IP:
v = s_nametoproto(name);
if (v == PROTO_UNDEF)
error("unknown ip proto '%s'", name);
break;
case Q_LINK:
/* XXX should look up h/w protocol type based on linktype */
v = s_nametoeproto(name);
if (v == PROTO_UNDEF)
error("unknown ether proto '%s'", name);
break;
default:
v = PROTO_UNDEF;
break;
}
return v;
}
struct block *
gen_proto(v, proto, dir)
int v;
int proto;
int dir;
{
struct block *b0, *b1;
if (dir != Q_DEFAULT)
error("direction applied to 'proto'");
switch (proto) {
case Q_DEFAULT:
case Q_IP:
b0 = gen_linktype(ETHERTYPE_IP);
b1 = gen_cmp(off_nl + 9, BPF_B, (long)v);
gen_and(b0, b1);
return b1;
case Q_ARP:
error("arp does not encapsulate another protocol");
/* NOTREACHED */
case Q_RARP:
error("rarp does not encapsulate another protocol");
/* NOTREACHED */
case Q_LINK:
return gen_linktype(v);
case Q_UDP:
error("'udp proto' is bogus");
case Q_TCP:
error("'tcp proto' is bogus");
case Q_ICMP:
error("'icmp proto' is bogus");
}
abort();
/* NOTREACHED */
}
struct block *
gen_scode(name, q)
char *name;
struct qual q;
{
int proto = q.proto;
int dir = q.dir;
u_char *eaddr;
u_long mask, addr, **alist;
struct block *b, *tmp;
int port, real_proto;
switch (q.addr) {
case Q_NET:
addr = s_nametonetaddr(name);
if (addr == 0)
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) {
/* XXX Should lookup hw addr based on link layer */
eaddr = ETHER_hostton(name);
if (eaddr == 0)
error("unknown ether host '%s'", name);
return gen_ehostop(eaddr, dir);
} else {
alist = s_nametoaddr(name);
if (alist == 0 || *alist == 0)
error("uknown 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)
error("illegal qualifier of 'port'");
if (s_nametoport(name, &port, &real_proto) == 0)
error("unknown port '%s'", name);
if (proto == Q_UDP) {
if (real_proto == IPPROTO_TCP)
error("port '%s' is tcp", name);
else
/* override PROTO_UNDEF */
real_proto = IPPROTO_UDP;
}
if (proto == Q_TCP) {
if (real_proto == IPPROTO_UDP)
error("port '%s' is udp", name);
else
/* override PROTO_UNDEF */
real_proto = IPPROTO_TCP;
}
return gen_port(port, real_proto, dir);
case Q_GATEWAY:
eaddr = ETHER_hostton(name);
if (eaddr == 0)
error("unknown ether host: %s", name);
alist = s_nametoaddr(name);
if (alist == 0 || *alist == 0)
error("uknown host '%s'", name);
return gen_gateway(eaddr, alist, proto, dir);
case Q_PROTO:
real_proto = lookup_proto(name, proto);
if (real_proto >= 0)
return gen_proto(real_proto, proto, dir);
else
error("unknown protocol: %s", name);
case Q_UNDEF:
syntax();
/* NOTREACHED */
}
abort();
/* NOTREACHED */
}
struct block *
gen_ncode(v, q)
u_long v;
struct qual q;
{
u_long mask;
int proto = q.proto;
int dir = q.dir;
switch (q.addr) {
case Q_DEFAULT:
case Q_HOST:
case Q_NET:
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
error("illegal qualifier of 'port'");
return gen_port((int)v, proto, dir);
case Q_GATEWAY:
error("'gateway' requires a name");
/* NOTREACHED */
case Q_PROTO:
return gen_proto((int)v, proto, dir);
case Q_UNDEF:
syntax();
/* NOTREACHED */
}
abort();
/* NOTREACHED */
}
struct block *
gen_ecode(eaddr, q)
u_char *eaddr;
struct qual q;
{
if ((q.addr == Q_HOST || q.addr == Q_DEFAULT) && q.proto == Q_LINK)
return gen_ehostop(eaddr, (int)q.dir);
else
error("ethernet address used in non-ether expression");
/* 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;
}
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;
}
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:
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:
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:
case Q_ARP:
case Q_RARP:
/* 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;
}
}
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 void
free_all_reg()
{
int n;
for(n=0;n<BPF_MEMWORDS;n++)
regused[n] = 0;
curreg = 0;
}
static struct block *
gen_len(jmp, n)
int jmp;
int n;
{
struct slist *s;
struct block *b;
s = new_stmt(BPF_LD|BPF_LEN);
s->next = new_stmt(BPF_SUB|BPF_IMM);
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;
int idx;
int val;
{
struct block *b;
struct slist *s;
switch (op) {
default:
abort();
case '=':
return gen_cmp((u_int)idx, BPF_B, (long)val);
case '<':
b = gen_cmp((u_int)idx, BPF_B, (long)val);
b->s.code = JMP(BPF_JGE);
gen_not(b);
return b;
case '>':
b = gen_cmp((u_int)idx, BPF_B, (long)val);
b->s.code = JMP(BPF_JGT);
return b;
case '|':
s = new_stmt(BPF_ALU|BPF_AND|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;
{
u_long hostmask;
struct block *b0, *b1, *b2;
static u_char ebroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
switch (proto) {
case Q_DEFAULT:
case Q_LINK:
if (linktype == DLT_EN10MB)
return gen_ehostop(ebroadcast, Q_DST);
error("not a broadcast link");
break;
case Q_IP:
b0 = gen_linktype(ETHERTYPE_IP);
hostmask = ~netmask;
b1 = gen_mcmp(off_nl + 16, BPF_W, (long)0, hostmask);
b2 = gen_mcmp(off_nl + 16, BPF_W,
(long)(~0 & hostmask), hostmask);
gen_or(b1, b2);
gen_and(b0, b2);
return b2;
}
error("only ether/ip broadcast filters supported");
}
struct block *
gen_multicast(proto)
int proto;
{
register struct block *b0, *b1, *b2;
register struct slist *s;
switch (proto) {
case Q_DEFAULT:
case Q_LINK:
if (linktype != DLT_EN10MB)
break;
/* ether[0] & 1 != 0 */
s = new_stmt(BPF_LD|BPF_B|BPF_ABS);
s->s.k = 0;
b0 = new_block(JMP(BPF_JSET));
b0->s.k = 1;
b0->stmts = s;
return b0;
case Q_IP:
b0 = gen_linktype(ETHERTYPE_IP);
b1 = gen_cmp(off_nl + 16, BPF_B, (long)224);
b1->s.code = JMP(BPF_JGE);
gen_and(b0, b1);
return b1;
}
error("only ether/ip multicast filters supported");
}
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