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nest-open-source / nest-learning-thermostat / 5.0 / libpcap / refs/heads/master / . / libpcap-1.3.0 / gencode.c
blob: 532229aae64a9630b560338f950341e7a4f51971 [file] [log] [blame] [edit]
/*#define CHASE_CHAIN*/
/*
* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998
* 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 const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.309 2008-12-23 20:13:29 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif
#include <sys/types.h>
#include <sys/socket.h>
#endif /* WIN32 */
/*
* XXX - why was this included even on UNIX?
*/
#ifdef __MINGW32__
#include "ip6_misc.h"
#endif
#ifndef WIN32
#ifdef __NetBSD__
#include <sys/param.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#endif /* WIN32 */
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <setjmp.h>
#include <stdarg.h>
#ifdef MSDOS
#include "pcap-dos.h"
#endif
#include "pcap-int.h"
#include "ethertype.h"
#include "nlpid.h"
#include "llc.h"
#include "gencode.h"
#include "ieee80211.h"
#include "atmuni31.h"
#include "sunatmpos.h"
#include "ppp.h"
#include "pcap/sll.h"
#include "pcap/ipnet.h"
#include "arcnet.h"
#if defined(PF_PACKET) && defined(SO_ATTACH_FILTER)
#include <linux/types.h>
#include <linux/if_packet.h>
#include <linux/filter.h>
#endif
#ifdef HAVE_NET_PFVAR_H
#include <sys/socket.h>
#include <net/if.h>
#include <net/pfvar.h>
#include <net/if_pflog.h>
#endif
#ifndef offsetof
#define offsetof(s, e) ((size_t)&((s *)0)->e)
#endif
#ifdef INET6
#ifndef WIN32
#include <netdb.h> /* for "struct addrinfo" */
#endif /* WIN32 */
#endif /*INET6*/
#include <pcap/namedb.h>
#define ETHERMTU 1500
#ifndef IPPROTO_SCTP
#define IPPROTO_SCTP 132
#endif
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#define JMP(c) ((c)|BPF_JMP|BPF_K)
/* Locals */
static jmp_buf top_ctx;
static pcap_t *bpf_pcap;
/* Hack for updating VLAN, MPLS, and PPPoE offsets. */
#ifdef WIN32
static u_int orig_linktype = (u_int)-1, orig_nl = (u_int)-1, label_stack_depth = (u_int)-1;
#else
static u_int orig_linktype = -1U, orig_nl = -1U, label_stack_depth = -1U;
#endif
/* XXX */
#ifdef PCAP_FDDIPAD
static int pcap_fddipad;
#endif
/* VARARGS */
void
bpf_error(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (bpf_pcap != NULL)
(void)vsnprintf(pcap_geterr(bpf_pcap), PCAP_ERRBUF_SIZE,
fmt, ap);
va_end(ap);
longjmp(top_ctx, 1);
/* NOTREACHED */
}
static void init_linktype(pcap_t *);
static void init_regs(void);
static int alloc_reg(void);
static void free_reg(int);
static struct block *root;
/*
* Value passed to gen_load_a() to indicate what the offset argument
* is relative to.
*/
enum e_offrel {
OR_PACKET, /* relative to the beginning of the packet */
OR_LINK, /* relative to the beginning of the link-layer header */
OR_MACPL, /* relative to the end of the MAC-layer header */
OR_NET, /* relative to the network-layer header */
OR_NET_NOSNAP, /* relative to the network-layer header, with no SNAP header at the link layer */
OR_TRAN_IPV4, /* relative to the transport-layer header, with IPv4 network layer */
OR_TRAN_IPV6 /* relative to the transport-layer header, with IPv6 network layer */
};
#ifdef INET6
/*
* As errors are handled by a longjmp, anything allocated must be freed
* in the longjmp handler, so it must be reachable from that handler.
* One thing that's allocated is the result of pcap_nametoaddrinfo();
* it must be freed with freeaddrinfo(). This variable points to any
* addrinfo structure that would need to be freed.
*/
static struct addrinfo *ai;
#endif
/*
* 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 if this ever
* goes into a library that would probably not be a good idea.
*
* XXX - this *is* in a library....
*/
#define NCHUNKS 16
#define CHUNK0SIZE 1024
struct chunk {
u_int n_left;
void *m;
};
static struct chunk chunks[NCHUNKS];
static int cur_chunk;
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(enum e_offrel, u_int, u_int, bpf_int32);
static struct block *gen_cmp_gt(enum e_offrel, u_int, u_int, bpf_int32);
static struct block *gen_cmp_ge(enum e_offrel, u_int, u_int, bpf_int32);
static struct block *gen_cmp_lt(enum e_offrel, u_int, u_int, bpf_int32);
static struct block *gen_cmp_le(enum e_offrel, u_int, u_int, bpf_int32);
static struct block *gen_mcmp(enum e_offrel, u_int, u_int, bpf_int32,
bpf_u_int32);
static struct block *gen_bcmp(enum e_offrel, u_int, u_int, const u_char *);
static struct block *gen_ncmp(enum e_offrel, bpf_u_int32, bpf_u_int32,
bpf_u_int32, bpf_u_int32, int, bpf_int32);
static struct slist *gen_load_llrel(u_int, u_int);
static struct slist *gen_load_macplrel(u_int, u_int);
static struct slist *gen_load_a(enum e_offrel, u_int, u_int);
static struct slist *gen_loadx_iphdrlen(void);
static struct block *gen_uncond(int);
static inline struct block *gen_true(void);
static inline struct block *gen_false(void);
static struct block *gen_ether_linktype(int);
static struct block *gen_ipnet_linktype(int);
static struct block *gen_linux_sll_linktype(int);
static struct slist *gen_load_prism_llprefixlen(void);
static struct slist *gen_load_avs_llprefixlen(void);
static struct slist *gen_load_radiotap_llprefixlen(void);
static struct slist *gen_load_ppi_llprefixlen(void);
static void insert_compute_vloffsets(struct block *);
static struct slist *gen_llprefixlen(void);
static struct slist *gen_off_macpl(void);
static int ethertype_to_ppptype(int);
static struct block *gen_linktype(int);
static struct block *gen_snap(bpf_u_int32, bpf_u_int32);
static struct block *gen_llc_linktype(int);
static struct block *gen_hostop(bpf_u_int32, bpf_u_int32, int, int, u_int, u_int);
#ifdef INET6
static struct block *gen_hostop6(struct in6_addr *, struct in6_addr *, int, int, u_int, u_int);
#endif
static struct block *gen_ahostop(const u_char *, int);
static struct block *gen_ehostop(const u_char *, int);
static struct block *gen_fhostop(const u_char *, int);
static struct block *gen_thostop(const u_char *, int);
static struct block *gen_wlanhostop(const u_char *, int);
static struct block *gen_ipfchostop(const u_char *, int);
static struct block *gen_dnhostop(bpf_u_int32, int);
static struct block *gen_mpls_linktype(int);
static struct block *gen_host(bpf_u_int32, bpf_u_int32, int, int, int);
#ifdef INET6
static struct block *gen_host6(struct in6_addr *, struct in6_addr *, int, int, int);
#endif
#ifndef INET6
static struct block *gen_gateway(const u_char *, bpf_u_int32 **, int, int);
#endif
static struct block *gen_ipfrag(void);
static struct block *gen_portatom(int, bpf_int32);
static struct block *gen_portrangeatom(int, bpf_int32, bpf_int32);
#ifdef INET6
static struct block *gen_portatom6(int, bpf_int32);
static struct block *gen_portrangeatom6(int, bpf_int32, bpf_int32);
#endif
struct block *gen_portop(int, int, int);
static struct block *gen_port(int, int, int);
struct block *gen_portrangeop(int, int, int, int);
static struct block *gen_portrange(int, int, int, int);
#ifdef INET6
struct block *gen_portop6(int, int, int);
static struct block *gen_port6(int, int, int);
struct block *gen_portrangeop6(int, int, int, int);
static struct block *gen_portrange6(int, int, int, int);
#endif
static int lookup_proto(const char *, int);
static struct block *gen_protochain(int, int, int);
static struct block *gen_proto(int, int, int);
static struct slist *xfer_to_x(struct arth *);
static struct slist *xfer_to_a(struct arth *);
static struct block *gen_mac_multicast(int);
static struct block *gen_len(int, int);
static struct block *gen_check_802_11_data_frame(void);
static struct block *gen_ppi_dlt_check(void);
static struct block *gen_msg_abbrev(int type);
static void *
newchunk(n)
u_int n;
{
struct chunk *cp;
int k;
size_t size;
#ifndef __NetBSD__
/* XXX Round up to nearest long. */
n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
#else
/* XXX Round up to structure boundary. */
n = ALIGN(n);
#endif
cp = &chunks[cur_chunk];
if (n > cp->n_left) {
++cp, k = ++cur_chunk;
if (k >= NCHUNKS)
bpf_error("out of memory");
size = CHUNK0SIZE << k;
cp->m = (void *)malloc(size);
if (cp->m == NULL)
bpf_error("out of memory");
memset((char *)cp->m, 0, size);
cp->n_left = size;
if (n > size)
bpf_error("out of memory");
}
cp->n_left -= n;
return (void *)((char *)cp->m + cp->n_left);
}
static void
freechunks()
{
int i;
cur_chunk = 0;
for (i = 0; i < NCHUNKS; ++i)
if (chunks[i].m != NULL) {
free(chunks[i].m);
chunks[i].m = NULL;
}
}
/*
* A strdup whose allocations are freed after code generation is over.
*/
char *
sdup(s)
register const char *s;
{
int n = strlen(s) + 1;
char *cp = newchunk(n);
strlcpy(cp, s, n);
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 bpf_u_int32 netmask;
static int snaplen;
int no_optimize;
#ifdef WIN32
static int
pcap_compile_unsafe(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask);
int
pcap_compile(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
{
int result;
EnterCriticalSection(&g_PcapCompileCriticalSection);
result = pcap_compile_unsafe(p, program, buf, optimize, mask);
LeaveCriticalSection(&g_PcapCompileCriticalSection);
return result;
}
static int
pcap_compile_unsafe(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
#else /* WIN32 */
int
pcap_compile(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
#endif /* WIN32 */
{
extern int n_errors;
const char * volatile xbuf = buf;
u_int len;
no_optimize = 0;
n_errors = 0;
root = NULL;
bpf_pcap = p;
init_regs();
if (setjmp(top_ctx)) {
#ifdef INET6
if (ai != NULL) {
freeaddrinfo(ai);
ai = NULL;
}
#endif
lex_cleanup();
freechunks();
return (-1);
}
netmask = mask;
snaplen = pcap_snapshot(p);
if (snaplen == 0) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"snaplen of 0 rejects all packets");
return -1;
}
lex_init(xbuf ? xbuf : "");
init_linktype(p);
(void)pcap_parse();
if (n_errors)
syntax();
if (root == NULL)
root = gen_retblk(snaplen);
if (optimize && !no_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;
lex_cleanup();
freechunks();
return (0);
}
/*
* entry point for using the compiler with no pcap open
* pass in all the stuff that is needed explicitly instead.
*/
int
pcap_compile_nopcap(int snaplen_arg, int linktype_arg,
struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
{
pcap_t *p;
int ret;
p = pcap_open_dead(linktype_arg, snaplen_arg);
if (p == NULL)
return (-1);
ret = pcap_compile(p, program, buf, optimize, mask);
pcap_close(p);
return (ret);
}
/*
* Clean up a "struct bpf_program" by freeing all the memory allocated
* in it.
*/
void
pcap_freecode(struct bpf_program *program)
{
program->bf_len = 0;
if (program->bf_insns != NULL) {
free((char *)program->bf_insns);
program->bf_insns = NULL;
}
}
/*
* 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;
{
struct block *ppi_dlt_check;
/*
* Insert before the statements of the first (root) block any
* statements needed to load the lengths of any variable-length
* headers into registers.
*
* XXX - a fancier strategy would be to insert those before the
* statements of all blocks that use those lengths and that
* have no predecessors that use them, so that we only compute
* the lengths if we need them. There might be even better
* approaches than that.
*
* However, those strategies would be more complicated, and
* as we don't generate code to compute a length if the
* program has no tests that use the length, and as most
* tests will probably use those lengths, we would just
* postpone computing the lengths so that it's not done
* for tests that fail early, and it's not clear that's
* worth the effort.
*/
insert_compute_vloffsets(p->head);
/*
* For DLT_PPI captures, generate a check of the per-packet
* DLT value to make sure it's DLT_IEEE802_11.
*/
ppi_dlt_check = gen_ppi_dlt_check();
if (ppi_dlt_check != NULL)
gen_and(ppi_dlt_check, 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(offrel, offset, size, v)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
{
return gen_ncmp(offrel, offset, size, 0xffffffff, BPF_JEQ, 0, v);
}
static struct block *
gen_cmp_gt(offrel, offset, size, v)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
{
return gen_ncmp(offrel, offset, size, 0xffffffff, BPF_JGT, 0, v);
}
static struct block *
gen_cmp_ge(offrel, offset, size, v)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
{
return gen_ncmp(offrel, offset, size, 0xffffffff, BPF_JGE, 0, v);
}
static struct block *
gen_cmp_lt(offrel, offset, size, v)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
{
return gen_ncmp(offrel, offset, size, 0xffffffff, BPF_JGE, 1, v);
}
static struct block *
gen_cmp_le(offrel, offset, size, v)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
{
return gen_ncmp(offrel, offset, size, 0xffffffff, BPF_JGT, 1, v);
}
static struct block *
gen_mcmp(offrel, offset, size, v, mask)
enum e_offrel offrel;
u_int offset, size;
bpf_int32 v;
bpf_u_int32 mask;
{
return gen_ncmp(offrel, offset, size, mask, BPF_JEQ, 0, v);
}
static struct block *
gen_bcmp(offrel, offset, size, v)
enum e_offrel offrel;
register u_int offset, size;
register const u_char *v;
{
register struct block *b, *tmp;
b = NULL;
while (size >= 4) {
register const u_char *p = &v[size - 4];
bpf_int32 w = ((bpf_int32)p[0] << 24) |
((bpf_int32)p[1] << 16) | ((bpf_int32)p[2] << 8) | p[3];
tmp = gen_cmp(offrel, offset + size - 4, BPF_W, w);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
size -= 4;
}
while (size >= 2) {
register const u_char *p = &v[size - 2];
bpf_int32 w = ((bpf_int32)p[0] << 8) | p[1];
tmp = gen_cmp(offrel, offset + size - 2, BPF_H, w);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
size -= 2;
}
if (size > 0) {
tmp = gen_cmp(offrel, offset, BPF_B, (bpf_int32)v[0]);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
}
return b;
}
/*
* AND the field of size "size" at offset "offset" relative to the header
* specified by "offrel" with "mask", and compare it with the value "v"
* with the test specified by "jtype"; if "reverse" is true, the test
* should test the opposite of "jtype".
*/
static struct block *
gen_ncmp(offrel, offset, size, mask, jtype, reverse, v)
enum e_offrel offrel;
bpf_int32 v;
bpf_u_int32 offset, size, mask, jtype;
int reverse;
{
struct slist *s, *s2;
struct block *b;
s = gen_load_a(offrel, offset, size);
if (mask != 0xffffffff) {
s2 = new_stmt(BPF_ALU|BPF_AND|BPF_K);
s2->s.k = mask;
sappend(s, s2);
}
b = new_block(JMP(jtype));
b->stmts = s;
b->s.k = v;
if (reverse && (jtype == BPF_JGT || jtype == BPF_JGE))
gen_not(b);
return b;
}
/*
* Various code constructs need to know the layout of the data link
* layer. These variables give the necessary offsets from the beginning
* of the packet data.
*/
/*
* This is the offset of the beginning of the link-layer header from
* the beginning of the raw packet data.
*
* It's usually 0, except for 802.11 with a fixed-length radio header.
* (For 802.11 with a variable-length radio header, we have to generate
* code to compute that offset; off_ll is 0 in that case.)
*/
static u_int off_ll;
/*
* If there's a variable-length header preceding the link-layer header,
* "reg_off_ll" is the register number for a register containing the
* length of that header, and therefore the offset of the link-layer
* header from the beginning of the raw packet data. Otherwise,
* "reg_off_ll" is -1.
*/
static int reg_off_ll;
/*
* This is the offset of the beginning of the MAC-layer header from
* the beginning of the link-layer header.
* It's usually 0, except for ATM LANE, where it's the offset, relative
* to the beginning of the raw packet data, of the Ethernet header, and
* for Ethernet with various additional information.
*/
static u_int off_mac;
/*
* This is the offset of the beginning of the MAC-layer payload,
* from the beginning of the raw packet data.
*
* I.e., it's the sum of the length of the link-layer header (without,
* for example, any 802.2 LLC header, so it's the MAC-layer
* portion of that header), plus any prefix preceding the
* link-layer header.
*/
static u_int off_macpl;
/*
* This is 1 if the offset of the beginning of the MAC-layer payload
* from the beginning of the link-layer header is variable-length.
*/
static int off_macpl_is_variable;
/*
* If the link layer has variable_length headers, "reg_off_macpl"
* is the register number for a register containing the length of the
* link-layer header plus the length of any variable-length header
* preceding the link-layer header. Otherwise, "reg_off_macpl"
* is -1.
*/
static int reg_off_macpl;
/*
* "off_linktype" is the offset to information in the link-layer header
* giving the packet type. This offset is relative to the beginning
* of the link-layer header (i.e., it doesn't include off_ll).
*
* For Ethernet, it's the offset of the Ethernet type field.
*
* For link-layer types that always use 802.2 headers, it's the
* offset of the LLC header.
*
* For PPP, it's the offset of the PPP type field.
*
* For Cisco HDLC, it's the offset of the CHDLC type field.
*
* For BSD loopback, it's the offset of the AF_ value.
*
* For Linux cooked sockets, it's the offset of the type field.
*
* It's set to -1 for no encapsulation, in which case, IP is assumed.
*/
static u_int off_linktype;
/*
* TRUE if "pppoes" appeared in the filter; it causes link-layer type
* checks to check the PPP header, assumed to follow a LAN-style link-
* layer header and a PPPoE session header.
*/
static int is_pppoes = 0;
/*
* TRUE if the link layer includes an ATM pseudo-header.
*/
static int is_atm = 0;
/*
* TRUE if "lane" appeared in the filter; it causes us to generate
* code that assumes LANE rather than LLC-encapsulated traffic in SunATM.
*/
static int is_lane = 0;
/*
* These are offsets for the ATM pseudo-header.
*/
static u_int off_vpi;
static u_int off_vci;
static u_int off_proto;
/*
* These are offsets for the MTP2 fields.
*/
static u_int off_li;
/*
* These are offsets for the MTP3 fields.
*/
static u_int off_sio;
static u_int off_opc;
static u_int off_dpc;
static u_int off_sls;
/*
* This is the offset of the first byte after the ATM pseudo_header,
* or -1 if there is no ATM pseudo-header.
*/
static u_int off_payload;
/*
* These are offsets to the beginning of the network-layer header.
* They are relative to the beginning of the MAC-layer payload (i.e.,
* they don't include off_ll or off_macpl).
*
* If the link layer never uses 802.2 LLC:
*
* "off_nl" and "off_nl_nosnap" are the same.
*
* If the link layer always uses 802.2 LLC:
*
* "off_nl" is the offset if there's a SNAP header following
* the 802.2 header;
*
* "off_nl_nosnap" is the offset if there's no SNAP header.
*
* If the link layer is Ethernet:
*
* "off_nl" is the offset if the packet is an Ethernet II packet
* (we assume no 802.3+802.2+SNAP);
*
* "off_nl_nosnap" is the offset if the packet is an 802.3 packet
* with an 802.2 header following it.
*/
static u_int off_nl;
static u_int off_nl_nosnap;
static int linktype;
static void
init_linktype(p)
pcap_t *p;
{
linktype = pcap_datalink(p);
#ifdef PCAP_FDDIPAD
pcap_fddipad = p->fddipad;
#endif
/*
* Assume it's not raw ATM with a pseudo-header, for now.
*/
off_mac = 0;
is_atm = 0;
is_lane = 0;
off_vpi = -1;
off_vci = -1;
off_proto = -1;
off_payload = -1;
/*
* And that we're not doing PPPoE.
*/
is_pppoes = 0;
/*
* And assume we're not doing SS7.
*/
off_li = -1;
off_sio = -1;
off_opc = -1;
off_dpc = -1;
off_sls = -1;
/*
* Also assume it's not 802.11.
*/
off_ll = 0;
off_macpl = 0;
off_macpl_is_variable = 0;
orig_linktype = -1;
orig_nl = -1;
label_stack_depth = 0;
reg_off_ll = -1;
reg_off_macpl = -1;
switch (linktype) {
case DLT_ARCNET:
off_linktype = 2;
off_macpl = 6;
off_nl = 0; /* XXX in reality, variable! */
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_ARCNET_LINUX:
off_linktype = 4;
off_macpl = 8;
off_nl = 0; /* XXX in reality, variable! */
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_EN10MB:
off_linktype = 12;
off_macpl = 14; /* Ethernet header length */
off_nl = 0; /* Ethernet II */
off_nl_nosnap = 3; /* 802.3+802.2 */
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_macpl = 16;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_SLIP_BSDOS:
/* XXX this may be the same as the DLT_PPP_BSDOS case */
off_linktype = -1;
/* XXX end */
off_macpl = 24;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_NULL:
case DLT_LOOP:
off_linktype = 0;
off_macpl = 4;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_ENC:
off_linktype = 0;
off_macpl = 12;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_PPP:
case DLT_PPP_PPPD:
case DLT_C_HDLC: /* BSD/OS Cisco HDLC */
case DLT_PPP_SERIAL: /* NetBSD sync/async serial PPP */
off_linktype = 2;
off_macpl = 4;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_PPP_ETHER:
/*
* This does no include the Ethernet header, and
* only covers session state.
*/
off_linktype = 6;
off_macpl = 8;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_PPP_BSDOS:
off_linktype = 5;
off_macpl = 24;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_FDDI:
/*
* FDDI doesn't really have a link-level type field.
* We set "off_linktype" to the offset of the LLC header.
*
* To check for Ethernet types, we assume that SSAP = SNAP
* is being used and pick out the encapsulated Ethernet type.
* XXX - should we generate code to check for SNAP?
*/
off_linktype = 13;
#ifdef PCAP_FDDIPAD
off_linktype += pcap_fddipad;
#endif
off_macpl = 13; /* FDDI MAC header length */
#ifdef PCAP_FDDIPAD
off_macpl += pcap_fddipad;
#endif
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_IEEE802:
/*
* Token Ring doesn't really have a link-level type field.
* We set "off_linktype" to the offset of the LLC header.
*
* To check for Ethernet types, we assume that SSAP = SNAP
* is being used and pick out the encapsulated Ethernet type.
* XXX - should we generate code to check for SNAP?
*
* XXX - the header is actually variable-length.
* Some various Linux patched versions gave 38
* as "off_linktype" and 40 as "off_nl"; however,
* if a token ring packet has *no* routing
* information, i.e. is not source-routed, the correct
* values are 20 and 22, as they are in the vanilla code.
*
* A packet is source-routed iff the uppermost bit
* of the first byte of the source address, at an
* offset of 8, has the uppermost bit set. If the
* packet is source-routed, the total number of bytes
* of routing information is 2 plus bits 0x1F00 of
* the 16-bit value at an offset of 14 (shifted right
* 8 - figure out which byte that is).
*/
off_linktype = 14;
off_macpl = 14; /* Token Ring MAC header length */
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_IEEE802_11:
case DLT_PRISM_HEADER:
case DLT_IEEE802_11_RADIO_AVS:
case DLT_IEEE802_11_RADIO:
/*
* 802.11 doesn't really have a link-level type field.
* We set "off_linktype" to the offset of the LLC header.
*
* To check for Ethernet types, we assume that SSAP = SNAP
* is being used and pick out the encapsulated Ethernet type.
* XXX - should we generate code to check for SNAP?
*
* We also handle variable-length radio headers here.
* The Prism header is in theory variable-length, but in
* practice it's always 144 bytes long. However, some
* drivers on Linux use ARPHRD_IEEE80211_PRISM, but
* sometimes or always supply an AVS header, so we
* have to check whether the radio header is a Prism
* header or an AVS header, so, in practice, it's
* variable-length.
*/
off_linktype = 24;
off_macpl = 0; /* link-layer header is variable-length */
off_macpl_is_variable = 1;
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_PPI:
/*
* At the moment we treat PPI the same way that we treat
* normal Radiotap encoded packets. The difference is in
* the function that generates the code at the beginning
* to compute the header length. Since this code generator
* of PPI supports bare 802.11 encapsulation only (i.e.
* the encapsulated DLT should be DLT_IEEE802_11) we
* generate code to check for this too.
*/
off_linktype = 24;
off_macpl = 0; /* link-layer header is variable-length */
off_macpl_is_variable = 1;
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_ATM_RFC1483:
case DLT_ATM_CLIP: /* Linux ATM defines this */
/*
* assume routed, non-ISO PDUs
* (i.e., LLC = 0xAA-AA-03, OUT = 0x00-00-00)
*
* XXX - what about ISO PDUs, e.g. CLNP, ISIS, ESIS,
* or PPP with the PPP NLPID (e.g., PPPoA)? The
* latter would presumably be treated the way PPPoE
* should be, so you can do "pppoe and udp port 2049"
* or "pppoa and tcp port 80" and have it check for
* PPPo{A,E} and a PPP protocol of IP and....
*/
off_linktype = 0;
off_macpl = 0; /* packet begins with LLC header */
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_SUNATM:
/*
* Full Frontal ATM; you get AALn PDUs with an ATM
* pseudo-header.
*/
is_atm = 1;
off_vpi = SUNATM_VPI_POS;
off_vci = SUNATM_VCI_POS;
off_proto = PROTO_POS;
off_mac = -1; /* assume LLC-encapsulated, so no MAC-layer header */
off_payload = SUNATM_PKT_BEGIN_POS;
off_linktype = off_payload;
off_macpl = off_payload; /* if LLC-encapsulated */
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_RAW:
case DLT_IPV4:
case DLT_IPV6:
off_linktype = -1;
off_macpl = 0;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_LINUX_SLL: /* fake header for Linux cooked socket */
off_linktype = 14;
off_macpl = 16;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_LTALK:
/*
* LocalTalk does have a 1-byte type field in the LLAP header,
* but really it just indicates whether there is a "short" or
* "long" DDP packet following.
*/
off_linktype = -1;
off_macpl = 0;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_IP_OVER_FC:
/*
* RFC 2625 IP-over-Fibre-Channel doesn't really have a
* link-level type field. We set "off_linktype" to the
* offset of the LLC header.
*
* To check for Ethernet types, we assume that SSAP = SNAP
* is being used and pick out the encapsulated Ethernet type.
* XXX - should we generate code to check for SNAP? RFC
* 2625 says SNAP should be used.
*/
off_linktype = 16;
off_macpl = 16;
off_nl = 8; /* 802.2+SNAP */
off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_FRELAY:
/*
* XXX - we should set this to handle SNAP-encapsulated
* frames (NLPID of 0x80).
*/
off_linktype = -1;
off_macpl = 0;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
/*
* the only BPF-interesting FRF.16 frames are non-control frames;
* Frame Relay has a variable length link-layer
* so lets start with offset 4 for now and increments later on (FIXME);
*/
case DLT_MFR:
off_linktype = -1;
off_macpl = 0;
off_nl = 4;
off_nl_nosnap = 0; /* XXX - for now -> no 802.2 LLC */
return;
case DLT_APPLE_IP_OVER_IEEE1394:
off_linktype = 16;
off_macpl = 18;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_SYMANTEC_FIREWALL:
off_linktype = 6;
off_macpl = 44;
off_nl = 0; /* Ethernet II */
off_nl_nosnap = 0; /* XXX - what does it do with 802.3 packets? */
return;
#ifdef HAVE_NET_PFVAR_H
case DLT_PFLOG:
off_linktype = 0;
off_macpl = PFLOG_HDRLEN;
off_nl = 0;
off_nl_nosnap = 0; /* no 802.2 LLC */
return;
#endif
case DLT_JUNIPER_MFR:
case DLT_JUNIPER_MLFR:
case DLT_JUNIPER_MLPPP:
case DLT_JUNIPER_PPP:
case DLT_JUNIPER_CHDLC:
case DLT_JUNIPER_FRELAY:
off_linktype = 4;
off_macpl = 4;
off_nl = 0;
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_ATM1:
off_linktype = 4; /* in reality variable between 4-8 */
off_macpl = 4; /* in reality variable between 4-8 */
off_nl = 0;
off_nl_nosnap = 10;
return;
case DLT_JUNIPER_ATM2:
off_linktype = 8; /* in reality variable between 8-12 */
off_macpl = 8; /* in reality variable between 8-12 */
off_nl = 0;
off_nl_nosnap = 10;
return;
/* frames captured on a Juniper PPPoE service PIC
* contain raw ethernet frames */
case DLT_JUNIPER_PPPOE:
case DLT_JUNIPER_ETHER:
off_macpl = 14;
off_linktype = 16;
off_nl = 18; /* Ethernet II */
off_nl_nosnap = 21; /* 802.3+802.2 */
return;
case DLT_JUNIPER_PPPOE_ATM:
off_linktype = 4;
off_macpl = 6;
off_nl = 0;
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_GGSN:
off_linktype = 6;
off_macpl = 12;
off_nl = 0;
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_ES:
off_linktype = 6;
off_macpl = -1; /* not really a network layer but raw IP addresses */
off_nl = -1; /* not really a network layer but raw IP addresses */
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_MONITOR:
off_linktype = 12;
off_macpl = 12;
off_nl = 0; /* raw IP/IP6 header */
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_SERVICES:
off_linktype = 12;
off_macpl = -1; /* L3 proto location dep. on cookie type */
off_nl = -1; /* L3 proto location dep. on cookie type */
off_nl_nosnap = -1; /* no 802.2 LLC */
return;
case DLT_JUNIPER_VP:
off_linktype = 18;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_JUNIPER_ST:
off_linktype = 18;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_JUNIPER_ISM:
off_linktype = 8;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_JUNIPER_VS:
case DLT_JUNIPER_SRX_E2E:
case DLT_JUNIPER_FIBRECHANNEL:
case DLT_JUNIPER_ATM_CEMIC:
off_linktype = 8;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_MTP2:
off_li = 2;
off_sio = 3;
off_opc = 4;
off_dpc = 4;
off_sls = 7;
off_linktype = -1;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_MTP2_WITH_PHDR:
off_li = 6;
off_sio = 7;
off_opc = 8;
off_dpc = 8;
off_sls = 11;
off_linktype = -1;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_ERF:
off_li = 22;
off_sio = 23;
off_opc = 24;
off_dpc = 24;
off_sls = 27;
off_linktype = -1;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
case DLT_PFSYNC:
off_linktype = -1;
off_macpl = 4;
off_nl = 0;
off_nl_nosnap = 0;
return;
case DLT_AX25_KISS:
/*
* Currently, only raw "link[N:M]" filtering is supported.
*/
off_linktype = -1; /* variable, min 15, max 71 steps of 7 */
off_macpl = -1;
off_nl = -1; /* variable, min 16, max 71 steps of 7 */
off_nl_nosnap = -1; /* no 802.2 LLC */
off_mac = 1; /* step over the kiss length byte */
return;
case DLT_IPNET:
off_linktype = 1;
off_macpl = 24; /* ipnet header length */
off_nl = 0;
off_nl_nosnap = -1;
return;
case DLT_NETANALYZER:
off_mac = 4; /* MAC header is past 4-byte pseudo-header */
off_linktype = 16; /* includes 4-byte pseudo-header */
off_macpl = 18; /* pseudo-header+Ethernet header length */
off_nl = 0; /* Ethernet II */
off_nl_nosnap = 3; /* 802.3+802.2 */
return;
case DLT_NETANALYZER_TRANSPARENT:
off_mac = 12; /* MAC header is past 4-byte pseudo-header, preamble, and SFD */
off_linktype = 24; /* includes 4-byte pseudo-header+preamble+SFD */
off_macpl = 26; /* pseudo-header+preamble+SFD+Ethernet header length */
off_nl = 0; /* Ethernet II */
off_nl_nosnap = 3; /* 802.3+802.2 */
return;
default:
/*
* For values in the range in which we've assigned new
* DLT_ values, only raw "link[N:M]" filtering is supported.
*/
if (linktype >= DLT_MATCHING_MIN &&
linktype <= DLT_MATCHING_MAX) {
off_linktype = -1;
off_macpl = -1;
off_nl = -1;
off_nl_nosnap = -1;
return;
}
}
bpf_error("unknown data link type %d", linktype);
/* NOTREACHED */
}
/*
* Load a value relative to the beginning of the link-layer header.
* The link-layer header doesn't necessarily begin at the beginning
* of the packet data; there might be a variable-length prefix containing
* radio information.
*/
static struct slist *
gen_load_llrel(offset, size)
u_int offset, size;
{
struct slist *s, *s2;
s = gen_llprefixlen();
/*
* If "s" is non-null, it has code to arrange that the X register
* contains the length of the prefix preceding the link-layer
* header.
*
* Otherwise, the length of the prefix preceding the link-layer
* header is "off_ll".
*/
if (s != NULL) {
/*
* There's a variable-length prefix preceding the
* link-layer header. "s" points to a list of statements
* that put the length of that prefix into the X register.
* do an indirect load, to use the X register as an offset.
*/
s2 = new_stmt(BPF_LD|BPF_IND|size);
s2->s.k = offset;
sappend(s, s2);
} else {
/*
* There is no variable-length header preceding the
* link-layer header; add in off_ll, which, if there's
* a fixed-length header preceding the link-layer header,
* is the length of that header.
*/
s = new_stmt(BPF_LD|BPF_ABS|size);
s->s.k = offset + off_ll;
}
return s;
}
/*
* Load a value relative to the beginning of the MAC-layer payload.
*/
static struct slist *
gen_load_macplrel(offset, size)
u_int offset, size;
{
struct slist *s, *s2;
s = gen_off_macpl();
/*
* If s is non-null, the offset of the MAC-layer payload is
* variable, and s points to a list of instructions that
* arrange that the X register contains that offset.
*
* Otherwise, the offset of the MAC-layer payload is constant,
* and is in off_macpl.
*/
if (s != NULL) {
/*
* The offset of the MAC-layer payload is in the X
* register. Do an indirect load, to use the X register
* as an offset.
*/
s2 = new_stmt(BPF_LD|BPF_IND|size);
s2->s.k = offset;
sappend(s, s2);
} else {
/*
* The offset of the MAC-layer payload is constant,
* and is in off_macpl; load the value at that offset
* plus the specified offset.
*/
s = new_stmt(BPF_LD|BPF_ABS|size);
s->s.k = off_macpl + offset;
}
return s;
}
/*
* Load a value relative to the beginning of the specified header.
*/
static struct slist *
gen_load_a(offrel, offset, size)
enum e_offrel offrel;
u_int offset, size;
{
struct slist *s, *s2;
switch (offrel) {
case OR_PACKET:
s = new_stmt(BPF_LD|BPF_ABS|size);
s->s.k = offset;
break;
case OR_LINK:
s = gen_load_llrel(offset, size);
break;
case OR_MACPL:
s = gen_load_macplrel(offset, size);
break;
case OR_NET:
s = gen_load_macplrel(off_nl + offset, size);
break;
case OR_NET_NOSNAP:
s = gen_load_macplrel(off_nl_nosnap + offset, size);
break;
case OR_TRAN_IPV4:
/*
* Load the X register with the length of the IPv4 header
* (plus the offset of the link-layer header, if it's
* preceded by a variable-length header such as a radio
* header), in bytes.
*/
s = gen_loadx_iphdrlen();
/*
* Load the item at {offset of the MAC-layer payload} +
* {offset, relative to the start of the MAC-layer
* paylod, of the IPv4 header} + {length of the IPv4 header} +
* {specified offset}.
*
* (If the offset of the MAC-layer payload is variable,
* it's included in the value in the X register, and
* off_macpl is 0.)
*/
s2 = new_stmt(BPF_LD|BPF_IND|size);
s2->s.k = off_macpl + off_nl + offset;
sappend(s, s2);
break;
case OR_TRAN_IPV6:
s = gen_load_macplrel(off_nl + 40 + offset, size);
break;
default:
abort();
return NULL;
}
return s;
}
/*
* Generate code to load into the X register the sum of the length of
* the IPv4 header and any variable-length header preceding the link-layer
* header.
*/
static struct slist *
gen_loadx_iphdrlen()
{
struct slist *s, *s2;
s = gen_off_macpl();
if (s != NULL) {
/*
* There's a variable-length prefix preceding the
* link-layer header, or the link-layer header is itself
* variable-length. "s" points to a list of statements
* that put the offset of the MAC-layer payload into
* the X register.
*
* The 4*([k]&0xf) addressing mode can't be used, as we
* don't have a constant offset, so we have to load the
* value in question into the A register and add to it
* the value from the X register.
*/
s2 = new_stmt(BPF_LD|BPF_IND|BPF_B);
s2->s.k = off_nl;
sappend(s, s2);
s2 = new_stmt(BPF_ALU|BPF_AND|BPF_K);
s2->s.k = 0xf;
sappend(s, s2);
s2 = new_stmt(BPF_ALU|BPF_LSH|BPF_K);
s2->s.k = 2;
sappend(s, s2);
/*
* The A register now contains the length of the
* IP header. We need to add to it the offset of
* the MAC-layer payload, which is still in the X
* register, and move the result into the X register.
*/
sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X));
sappend(s, new_stmt(BPF_MISC|BPF_TAX));
} else {
/*
* There is no variable-length header preceding the
* link-layer header, and the link-layer header is
* fixed-length; load the length of the IPv4 header,
* which is at an offset of off_nl from the beginning
* of the MAC-layer payload, and thus at an offset
* of off_mac_pl + off_nl from the beginning of the
* raw packet data.
*/
s = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
s->s.k = off_macpl + off_nl;
}
return s;
}
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);
}
/*
* Byte-swap a 32-bit number.
* ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
* big-endian platforms.)
*/
#define SWAPLONG(y) \
((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
/*
* Generate code to match a particular packet type.
*
* "proto" is an Ethernet type value, if > ETHERMTU, or an LLC SAP
* value, if <= ETHERMTU. We use that to determine whether to
* match the type/length field or to check the type/length field for
* a value <= ETHERMTU to see whether it's a type field and then do
* the appropriate test.
*/
static struct block *
gen_ether_linktype(proto)
register int proto;
{
struct block *b0, *b1;
switch (proto) {
case LLCSAP_ISONS:
case LLCSAP_IP:
case LLCSAP_NETBEUI:
/*
* OSI protocols and NetBEUI always use 802.2 encapsulation,
* so we check the DSAP and SSAP.
*
* LLCSAP_IP checks for IP-over-802.2, rather
* than IP-over-Ethernet or IP-over-SNAP.
*
* XXX - should we check both the DSAP and the
* SSAP, like this, or should we check just the
* DSAP, as we do for other types <= ETHERMTU
* (i.e., other SAP values)?
*/
b0 = gen_cmp_gt(OR_LINK, off_linktype, BPF_H, ETHERMTU);
gen_not(b0);
b1 = gen_cmp(OR_MACPL, 0, BPF_H, (bpf_int32)
((proto << 8) | proto));
gen_and(b0, b1);
return b1;
case LLCSAP_IPX:
/*
* Check for;
*
* Ethernet_II frames, which are Ethernet
* frames with a frame type of ETHERTYPE_IPX;
*
* Ethernet_802.3 frames, which are 802.3
* frames (i.e., the type/length field is
* a length field, <= ETHERMTU, rather than
* a type field) with the first two bytes
* after the Ethernet/802.3 header being
* 0xFFFF;
*
* Ethernet_802.2 frames, which are 802.3
* frames with an 802.2 LLC header and
* with the IPX LSAP as the DSAP in the LLC
* header;
*
* Ethernet_SNAP frames, which are 802.3
* frames with an LLC header and a SNAP
* header and with an OUI of 0x000000
* (encapsulated Ethernet) and a protocol
* ID of ETHERTYPE_IPX in the SNAP header.
*
* XXX - should we generate the same code both
* for tests for LLCSAP_IPX and for ETHERTYPE_IPX?
*/
/*
* This generates code to check both for the
* IPX LSAP (Ethernet_802.2) and for Ethernet_802.3.
*/
b0 = gen_cmp(OR_MACPL, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
b1 = gen_cmp(OR_MACPL, 0, BPF_H, (bpf_int32)0xFFFF);
gen_or(b0, b1);
/*
* Now we add code to check for SNAP frames with
* ETHERTYPE_IPX, i.e. Ethernet_SNAP.
*/
b0 = gen_snap(0x000000, ETHERTYPE_IPX);
gen_or(b0, b1);
/*
* Now we generate code to check for 802.3
* frames in general.
*/
b0 = gen_cmp_gt(OR_LINK, off_linktype, BPF_H, ETHERMTU);
gen_not(b0);
/*
* Now add the check for 802.3 frames before the
* check for Ethernet_802.2 and Ethernet_802.3,
* as those checks should only be done on 802.3
* frames, not on Ethernet frames.
*/
gen_and(b0, b1);
/*
* Now add the check for Ethernet_II frames, and
* do that before checking for the other frame
* types.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)ETHERTYPE_IPX);
gen_or(b0, b1);
return b1;
case ETHERTYPE_ATALK:
case ETHERTYPE_AARP:
/*
* EtherTalk (AppleTalk protocols on Ethernet link
* layer) may use 802.2 encapsulation.
*/
/*
* Check for 802.2 encapsulation (EtherTalk phase 2?);
* we check for an Ethernet type field less than
* 1500, which means it's an 802.3 length field.
*/
b0 = gen_cmp_gt(OR_LINK, off_linktype, BPF_H, ETHERMTU);
gen_not(b0);
/*
* 802.2-encapsulated ETHERTYPE_ATALK packets are
* SNAP packets with an organization code of
* 0x080007 (Apple, for Appletalk) and a protocol
* type of ETHERTYPE_ATALK (Appletalk).
*
* 802.2-encapsulated ETHERTYPE_AARP packets are
* SNAP packets with an organization code of
* 0x000000 (encapsulated Ethernet) and a protocol
* type of ETHERTYPE_AARP (Appletalk ARP).
*/
if (proto == ETHERTYPE_ATALK)
b1 = gen_snap(0x080007, ETHERTYPE_ATALK);
else /* proto == ETHERTYPE_AARP */
b1 = gen_snap(0x000000, ETHERTYPE_AARP);
gen_and(b0, b1);
/*
* Check for Ethernet encapsulation (Ethertalk
* phase 1?); we just check for the Ethernet
* protocol type.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto);
gen_or(b0, b1);
return b1;
default:
if (proto <= ETHERMTU) {
/*
* This is an LLC SAP value, so the frames
* that match would be 802.2 frames.
* Check that the frame is an 802.2 frame
* (i.e., that the length/type field is
* a length field, <= ETHERMTU) and
* then check the DSAP.
*/
b0 = gen_cmp_gt(OR_LINK, off_linktype, BPF_H, ETHERMTU);
gen_not(b0);
b1 = gen_cmp(OR_LINK, off_linktype + 2, BPF_B,
(bpf_int32)proto);
gen_and(b0, b1);
return b1;
} else {
/*
* This is an Ethernet type, so compare
* the length/type field with it (if
* the frame is an 802.2 frame, the length
* field will be <= ETHERMTU, and, as
* "proto" is > ETHERMTU, this test
* will fail and the frame won't match,
* which is what we want).
*/
return gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)proto);
}
}
}
/*
* "proto" is an Ethernet type value and for IPNET, if it is not IPv4
* or IPv6 then we have an error.
*/
static struct block *
gen_ipnet_linktype(proto)
register int proto;
{
switch (proto) {
case ETHERTYPE_IP:
return gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)IPH_AF_INET);
/* NOTREACHED */
case ETHERTYPE_IPV6:
return gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)IPH_AF_INET6);
/* NOTREACHED */
default:
break;
}
return gen_false();
}
/*
* Generate code to match a particular packet type.
*
* "proto" is an Ethernet type value, if > ETHERMTU, or an LLC SAP
* value, if <= ETHERMTU. We use that to determine whether to
* match the type field or to check the type field for the special
* LINUX_SLL_P_802_2 value and then do the appropriate test.
*/
static struct block *
gen_linux_sll_linktype(proto)
register int proto;
{
struct block *b0, *b1;
switch (proto) {
case LLCSAP_ISONS:
case LLCSAP_IP:
case LLCSAP_NETBEUI:
/*
* OSI protocols and NetBEUI always use 802.2 encapsulation,
* so we check the DSAP and SSAP.
*
* LLCSAP_IP checks for IP-over-802.2, rather
* than IP-over-Ethernet or IP-over-SNAP.
*
* XXX - should we check both the DSAP and the
* SSAP, like this, or should we check just the
* DSAP, as we do for other types <= ETHERMTU
* (i.e., other SAP values)?
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_2);
b1 = gen_cmp(OR_MACPL, 0, BPF_H, (bpf_int32)
((proto << 8) | proto));
gen_and(b0, b1);
return b1;
case LLCSAP_IPX:
/*
* Ethernet_II frames, which are Ethernet
* frames with a frame type of ETHERTYPE_IPX;
*
* Ethernet_802.3 frames, which have a frame
* type of LINUX_SLL_P_802_3;
*
* Ethernet_802.2 frames, which are 802.3
* frames with an 802.2 LLC header (i.e, have
* a frame type of LINUX_SLL_P_802_2) and
* with the IPX LSAP as the DSAP in the LLC
* header;
*
* Ethernet_SNAP frames, which are 802.3
* frames with an LLC header and a SNAP
* header and with an OUI of 0x000000
* (encapsulated Ethernet) and a protocol
* ID of ETHERTYPE_IPX in the SNAP header.
*
* First, do the checks on LINUX_SLL_P_802_2
* frames; generate the check for either
* Ethernet_802.2 or Ethernet_SNAP frames, and
* then put a check for LINUX_SLL_P_802_2 frames
* before it.
*/
b0 = gen_cmp(OR_MACPL, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
b1 = gen_snap(0x000000, ETHERTYPE_IPX);
gen_or(b0, b1);
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_2);
gen_and(b0, b1);
/*
* Now check for 802.3 frames and OR that with
* the previous test.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_3);
gen_or(b0, b1);
/*
* Now add the check for Ethernet_II frames, and
* do that before checking for the other frame
* types.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)ETHERTYPE_IPX);
gen_or(b0, b1);
return b1;
case ETHERTYPE_ATALK:
case ETHERTYPE_AARP:
/*
* EtherTalk (AppleTalk protocols on Ethernet link
* layer) may use 802.2 encapsulation.
*/
/*
* Check for 802.2 encapsulation (EtherTalk phase 2?);
* we check for the 802.2 protocol type in the
* "Ethernet type" field.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_2);
/*
* 802.2-encapsulated ETHERTYPE_ATALK packets are
* SNAP packets with an organization code of
* 0x080007 (Apple, for Appletalk) and a protocol
* type of ETHERTYPE_ATALK (Appletalk).
*
* 802.2-encapsulated ETHERTYPE_AARP packets are
* SNAP packets with an organization code of
* 0x000000 (encapsulated Ethernet) and a protocol
* type of ETHERTYPE_AARP (Appletalk ARP).
*/
if (proto == ETHERTYPE_ATALK)
b1 = gen_snap(0x080007, ETHERTYPE_ATALK);
else /* proto == ETHERTYPE_AARP */
b1 = gen_snap(0x000000, ETHERTYPE_AARP);
gen_and(b0, b1);
/*
* Check for Ethernet encapsulation (Ethertalk
* phase 1?); we just check for the Ethernet
* protocol type.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto);
gen_or(b0, b1);
return b1;
default:
if (proto <= ETHERMTU) {
/*
* This is an LLC SAP value, so the frames
* that match would be 802.2 frames.
* Check for the 802.2 protocol type
* in the "Ethernet type" field, and
* then check the DSAP.
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H,
LINUX_SLL_P_802_2);
b1 = gen_cmp(OR_LINK, off_macpl, BPF_B,
(bpf_int32)proto);
gen_and(b0, b1);
return b1;
} else {
/*
* This is an Ethernet type, so compare
* the length/type field with it (if
* the frame is an 802.2 frame, the length
* field will be <= ETHERMTU, and, as
* "proto" is > ETHERMTU, this test
* will fail and the frame won't match,
* which is what we want).
*/
return gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)proto);
}
}
}
static struct slist *
gen_load_prism_llprefixlen()
{
struct slist *s1, *s2;
struct slist *sjeq_avs_cookie;
struct slist *sjcommon;
/*
* This code is not compatible with the optimizer, as
* we are generating jmp instructions within a normal
* slist of instructions
*/
no_optimize = 1;
/*
* Generate code to load the length of the radio header into
* the register assigned to hold that length, if one has been
* assigned. (If one hasn't been assigned, no code we've
* generated uses that prefix, so we don't need to generate any
* code to load it.)
*
* Some Linux drivers use ARPHRD_IEEE80211_PRISM but sometimes
* or always use the AVS header rather than the Prism header.
* We load a 4-byte big-endian value at the beginning of the
* raw packet data, and see whether, when masked with 0xFFFFF000,
* it's equal to 0x80211000. If so, that indicates that it's
* an AVS header (the masked-out bits are the version number).
* Otherwise, it's a Prism header.
*
* XXX - the Prism header is also, in theory, variable-length,
* but no known software generates headers that aren't 144
* bytes long.
*/
if (reg_off_ll != -1) {
/*
* Load the cookie.
*/
s1 = new_stmt(BPF_LD|BPF_W|BPF_ABS);
s1->s.k = 0;
/*
* AND it with 0xFFFFF000.
*/
s2 = new_stmt(BPF_ALU|BPF_AND|BPF_K);
s2->s.k = 0xFFFFF000;
sappend(s1, s2);
/*
* Compare with 0x80211000.
*/
sjeq_avs_cookie = new_stmt(JMP(BPF_JEQ));
sjeq_avs_cookie->s.k = 0x80211000;
sappend(s1, sjeq_avs_cookie);
/*
* If it's AVS:
*
* The 4 bytes at an offset of 4 from the beginning of
* the AVS header are the length of the AVS header.
* That field is big-endian.
*/
s2 = new_stmt(BPF_LD|BPF_W|BPF_ABS);
s2->s.k = 4;
sappend(s1, s2);
sjeq_avs_cookie->s.jt = s2;
/*
* Now jump to the code to allocate a register
* into which to save the header length and
* store the length there. (The "jump always"
* instruction needs to have the k field set;
* it's added to the PC, so, as we're jumping
* over a single instruction, it should be 1.)
*/
sjcommon = new_stmt(JMP(BPF_JA));
sjcommon->s.k = 1;
sappend(s1, sjcommon);
/*
* Now for the code that handles the Prism header.
* Just load the length of the Prism header (144)
* into the A register. Have the test for an AVS
* header branch here if we don't have an AVS header.
*/
s2 = new_stmt(BPF_LD|BPF_W|BPF_IMM);
s2->s.k = 144;
sappend(s1, s2);
sjeq_avs_cookie->s.jf = s2;
/*
* Now allocate a register to hold that value and store
* it. The code for the AVS header will jump here after
* loading the length of the AVS header.
*/
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_ll;
sappend(s1, s2);
sjcommon->s.jf = s2;
/*
* Now move it into the X register.
*/
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
return (s1);
} else
return (NULL);
}
static struct slist *
gen_load_avs_llprefixlen()
{
struct slist *s1, *s2;
/*
* Generate code to load the length of the AVS header into
* the register assigned to hold that length, if one has been
* assigned. (If one hasn't been assigned, no code we've
* generated uses that prefix, so we don't need to generate any
* code to load it.)
*/
if (reg_off_ll != -1) {
/*
* The 4 bytes at an offset of 4 from the beginning of
* the AVS header are the length of the AVS header.
* That field is big-endian.
*/
s1 = new_stmt(BPF_LD|BPF_W|BPF_ABS);
s1->s.k = 4;
/*
* Now allocate a register to hold that value and store
* it.
*/
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_ll;
sappend(s1, s2);
/*
* Now move it into the X register.
*/
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
return (s1);
} else
return (NULL);
}
static struct slist *
gen_load_radiotap_llprefixlen()
{
struct slist *s1, *s2;
/*
* Generate code to load the length of the radiotap header into
* the register assigned to hold that length, if one has been
* assigned. (If one hasn't been assigned, no code we've
* generated uses that prefix, so we don't need to generate any
* code to load it.)
*/
if (reg_off_ll != -1) {
/*
* The 2 bytes at offsets of 2 and 3 from the beginning
* of the radiotap header are the length of the radiotap
* header; unfortunately, it's little-endian, so we have
* to load it a byte at a time and construct the value.
*/
/*
* Load the high-order byte, at an offset of 3, shift it
* left a byte, and put the result in the X register.
*/
s1 = new_stmt(BPF_LD|BPF_B|BPF_ABS);
s1->s.k = 3;
s2 = new_stmt(BPF_ALU|BPF_LSH|BPF_K);
sappend(s1, s2);
s2->s.k = 8;
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
/*
* Load the next byte, at an offset of 2, and OR the
* value from the X register into it.
*/
s2 = new_stmt(BPF_LD|BPF_B|BPF_ABS);
sappend(s1, s2);
s2->s.k = 2;
s2 = new_stmt(BPF_ALU|BPF_OR|BPF_X);
sappend(s1, s2);
/*
* Now allocate a register to hold that value and store
* it.
*/
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_ll;
sappend(s1, s2);
/*
* Now move it into the X register.
*/
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
return (s1);
} else
return (NULL);
}
/*
* At the moment we treat PPI as normal Radiotap encoded
* packets. The difference is in the function that generates
* the code at the beginning to compute the header length.
* Since this code generator of PPI supports bare 802.11
* encapsulation only (i.e. the encapsulated DLT should be
* DLT_IEEE802_11) we generate code to check for this too;
* that's done in finish_parse().
*/
static struct slist *
gen_load_ppi_llprefixlen()
{
struct slist *s1, *s2;
/*
* Generate code to load the length of the radiotap header
* into the register assigned to hold that length, if one has
* been assigned.
*/
if (reg_off_ll != -1) {
/*
* The 2 bytes at offsets of 2 and 3 from the beginning
* of the radiotap header are the length of the radiotap
* header; unfortunately, it's little-endian, so we have
* to load it a byte at a time and construct the value.
*/
/*
* Load the high-order byte, at an offset of 3, shift it
* left a byte, and put the result in the X register.
*/
s1 = new_stmt(BPF_LD|BPF_B|BPF_ABS);
s1->s.k = 3;
s2 = new_stmt(BPF_ALU|BPF_LSH|BPF_K);
sappend(s1, s2);
s2->s.k = 8;
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
/*
* Load the next byte, at an offset of 2, and OR the
* value from the X register into it.
*/
s2 = new_stmt(BPF_LD|BPF_B|BPF_ABS);
sappend(s1, s2);
s2->s.k = 2;
s2 = new_stmt(BPF_ALU|BPF_OR|BPF_X);
sappend(s1, s2);
/*
* Now allocate a register to hold that value and store
* it.
*/
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_ll;
sappend(s1, s2);
/*
* Now move it into the X register.
*/
s2 = new_stmt(BPF_MISC|BPF_TAX);
sappend(s1, s2);
return (s1);
} else
return (NULL);
}
/*
* Load a value relative to the beginning of the link-layer header after the 802.11
* header, i.e. LLC_SNAP.
* The link-layer header doesn't necessarily begin at the beginning
* of the packet data; there might be a variable-length prefix containing
* radio information.
*/
static struct slist *
gen_load_802_11_header_len(struct slist *s, struct slist *snext)
{
struct slist *s2;
struct slist *sjset_data_frame_1;
struct slist *sjset_data_frame_2;
struct slist *sjset_qos;
struct slist *sjset_radiotap_flags;
struct slist *sjset_radiotap_tsft;
struct slist *sjset_tsft_datapad, *sjset_notsft_datapad;
struct slist *s_roundup;
if (reg_off_macpl == -1) {
/*
* No register has been assigned to the offset of
* the MAC-layer payload, which means nobody needs
* it; don't bother computing it - just return
* what we already have.
*/
return (s);
}
/*
* This code is not compatible with the optimizer, as
* we are generating jmp instructions within a normal
* slist of instructions
*/
no_optimize = 1;
/*
* If "s" is non-null, it has code to arrange that the X register
* contains the length of the prefix preceding the link-layer
* header.
*
* Otherwise, the length of the prefix preceding the link-layer
* header is "off_ll".
*/
if (s == NULL) {
/*
* There is no variable-length header preceding the
* link-layer header.
*
* Load the length of the fixed-length prefix preceding
* the link-layer header (if any) into the X register,
* and store it in the reg_off_macpl register.
* That length is off_ll.
*/
s = new_stmt(BPF_LDX|BPF_IMM);
s->s.k = off_ll;
}
/*
* The X register contains the offset of the beginning of the
* link-layer header; add 24, which is the minimum length
* of the MAC header for a data frame, to that, and store it
* in reg_off_macpl, and then load the Frame Control field,
* which is at the offset in the X register, with an indexed load.
*/
s2 = new_stmt(BPF_MISC|BPF_TXA);
sappend(s, s2);
s2 = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
s2->s.k = 24;
sappend(s, s2);
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_macpl;
sappend(s, s2);
s2 = new_stmt(BPF_LD|BPF_IND|BPF_B);
s2->s.k = 0;
sappend(s, s2);
/*
* Check the Frame Control field to see if this is a data frame;
* a data frame has the 0x08 bit (b3) in that field set and the
* 0x04 bit (b2) clear.
*/
sjset_data_frame_1 = new_stmt(JMP(BPF_JSET));
sjset_data_frame_1->s.k = 0x08;
sappend(s, sjset_data_frame_1);
/*
* If b3 is set, test b2, otherwise go to the first statement of
* the rest of the program.
*/
sjset_data_frame_1->s.jt = sjset_data_frame_2 = new_stmt(JMP(BPF_JSET));
sjset_data_frame_2->s.k = 0x04;
sappend(s, sjset_data_frame_2);
sjset_data_frame_1->s.jf = snext;
/*
* If b2 is not set, this is a data frame; test the QoS bit.
* Otherwise, go to the first statement of the rest of the
* program.
*/
sjset_data_frame_2->s.jt = snext;
sjset_data_frame_2->s.jf = sjset_qos = new_stmt(JMP(BPF_JSET));
sjset_qos->s.k = 0x80; /* QoS bit */
sappend(s, sjset_qos);
/*
* If it's set, add 2 to reg_off_macpl, to skip the QoS
* field.
* Otherwise, go to the first statement of the rest of the
* program.
*/
sjset_qos->s.jt = s2 = new_stmt(BPF_LD|BPF_MEM);
s2->s.k = reg_off_macpl;
sappend(s, s2);
s2 = new_stmt(BPF_ALU|BPF_ADD|BPF_IMM);
s2->s.k = 2;
sappend(s, s2);
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_macpl;
sappend(s, s2);
/*
* If we have a radiotap header, look at it to see whether
* there's Atheros padding between the MAC-layer header
* and the payload.
*
* Note: all of the fields in the radiotap header are
* little-endian, so we byte-swap all of the values
* we test against, as they will be loaded as big-endian
* values.
*/
if (linktype == DLT_IEEE802_11_RADIO) {
/*
* Is the IEEE80211_RADIOTAP_FLAGS bit (0x0000002) set
* in the presence flag?
*/
sjset_qos->s.jf = s2 = new_stmt(BPF_LD|BPF_ABS|BPF_W);
s2->s.k = 4;
sappend(s, s2);
sjset_radiotap_flags = new_stmt(JMP(BPF_JSET));
sjset_radiotap_flags->s.k = SWAPLONG(0x00000002);
sappend(s, sjset_radiotap_flags);
/*
* If not, skip all of this.
*/
sjset_radiotap_flags->s.jf = snext;
/*
* Otherwise, is the IEEE80211_RADIOTAP_TSFT bit set?
*/
sjset_radiotap_tsft = sjset_radiotap_flags->s.jt =
new_stmt(JMP(BPF_JSET));
sjset_radiotap_tsft->s.k = SWAPLONG(0x00000001);
sappend(s, sjset_radiotap_tsft);
/*
* If IEEE80211_RADIOTAP_TSFT is set, the flags field is
* at an offset of 16 from the beginning of the raw packet
* data (8 bytes for the radiotap header and 8 bytes for
* the TSFT field).
*
* Test whether the IEEE80211_RADIOTAP_F_DATAPAD bit (0x20)
* is set.
*/
sjset_radiotap_tsft->s.jt = s2 = new_stmt(BPF_LD|BPF_ABS|BPF_B);
s2->s.k = 16;
sappend(s, s2);
sjset_tsft_datapad = new_stmt(JMP(BPF_JSET));
sjset_tsft_datapad->s.k = 0x20;
sappend(s, sjset_tsft_datapad);
/*
* If IEEE80211_RADIOTAP_TSFT is not set, the flags field is
* at an offset of 8 from the beginning of the raw packet
* data (8 bytes for the radiotap header).
*
* Test whether the IEEE80211_RADIOTAP_F_DATAPAD bit (0x20)
* is set.
*/
sjset_radiotap_tsft->s.jf = s2 = new_stmt(BPF_LD|BPF_ABS|BPF_B);
s2->s.k = 8;
sappend(s, s2);
sjset_notsft_datapad = new_stmt(JMP(BPF_JSET));
sjset_notsft_datapad->s.k = 0x20;
sappend(s, sjset_notsft_datapad);
/*
* In either case, if IEEE80211_RADIOTAP_F_DATAPAD is
* set, round the length of the 802.11 header to
* a multiple of 4. Do that by adding 3 and then
* dividing by and multiplying by 4, which we do by
* ANDing with ~3.
*/
s_roundup = new_stmt(BPF_LD|BPF_MEM);
s_roundup->s.k = reg_off_macpl;
sappend(s, s_roundup);
s2 = new_stmt(BPF_ALU|BPF_ADD|BPF_IMM);
s2->s.k = 3;
sappend(s, s2);
s2 = new_stmt(BPF_ALU|BPF_AND|BPF_IMM);
s2->s.k = ~3;
sappend(s, s2);
s2 = new_stmt(BPF_ST);
s2->s.k = reg_off_macpl;
sappend(s, s2);
sjset_tsft_datapad->s.jt = s_roundup;
sjset_tsft_datapad->s.jf = snext;
sjset_notsft_datapad->s.jt = s_roundup;
sjset_notsft_datapad->s.jf = snext;
} else
sjset_qos->s.jf = snext;
return s;
}
static void
insert_compute_vloffsets(b)
struct block *b;
{
struct slist *s;
/*
* For link-layer types that have a variable-length header
* preceding the link-layer header, generate code to load
* the offset of the link-layer header into the register
* assigned to that offset, if any.
*/
switch (linktype) {
case DLT_PRISM_HEADER:
s = gen_load_prism_llprefixlen();
break;
case DLT_IEEE802_11_RADIO_AVS:
s = gen_load_avs_llprefixlen();
break;
case DLT_IEEE802_11_RADIO:
s = gen_load_radiotap_llprefixlen();
break;
case DLT_PPI:
s = gen_load_ppi_llprefixlen();
break;
default:
s = NULL;
break;
}
/*
* For link-layer types that have a variable-length link-layer
* header, generate code to load the offset of the MAC-layer
* payload into the register assigned to that offset, if any.
*/
switch (linktype) {
case DLT_IEEE802_11:
case DLT_PRISM_HEADER:
case DLT_IEEE802_11_RADIO_AVS:
case DLT_IEEE802_11_RADIO:
case DLT_PPI:
s = gen_load_802_11_header_len(s, b->stmts);
break;
}
/*
* If we have any offset-loading code, append all the
* existing statements in the block to those statements,
* and make the resulting list the list of statements
* for the block.
*/
if (s != NULL) {
sappend(s, b->stmts);
b->stmts = s;
}
}
static struct block *
gen_ppi_dlt_check(void)
{
struct slist *s_load_dlt;
struct block *b;
if (linktype == DLT_PPI)
{
/* Create the statements that check for the DLT
*/
s_load_dlt = new_stmt(BPF_LD|BPF_W|BPF_ABS);
s_load_dlt->s.k = 4;
b = new_block(JMP(BPF_JEQ));
b->stmts = s_load_dlt;
b->s.k = SWAPLONG(DLT_IEEE802_11);
}
else
{
b = NULL;
}
return b;
}
static struct slist *
gen_prism_llprefixlen(void)
{
struct slist *s;
if (reg_off_ll == -1) {
/*
* We haven't yet assigned a register for the length
* of the radio header; allocate one.
*/
reg_off_ll = alloc_reg();
}
/*
* Load the register containing the radio length
* into the X register.
*/
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = reg_off_ll;
return s;
}
static struct slist *
gen_avs_llprefixlen(void)
{
struct slist *s;
if (reg_off_ll == -1) {
/*
* We haven't yet assigned a register for the length
* of the AVS header; allocate one.
*/
reg_off_ll = alloc_reg();
}
/*
* Load the register containing the AVS length
* into the X register.
*/
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = reg_off_ll;
return s;
}
static struct slist *
gen_radiotap_llprefixlen(void)
{
struct slist *s;
if (reg_off_ll == -1) {
/*
* We haven't yet assigned a register for the length
* of the radiotap header; allocate one.
*/
reg_off_ll = alloc_reg();
}
/*
* Load the register containing the radiotap length
* into the X register.
*/
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = reg_off_ll;
return s;
}
/*
* At the moment we treat PPI as normal Radiotap encoded
* packets. The difference is in the function that generates
* the code at the beginning to compute the header length.
* Since this code generator of PPI supports bare 802.11
* encapsulation only (i.e. the encapsulated DLT should be
* DLT_IEEE802_11) we generate code to check for this too.
*/
static struct slist *
gen_ppi_llprefixlen(void)
{
struct slist *s;
if (reg_off_ll == -1) {
/*
* We haven't yet assigned a register for the length
* of the radiotap header; allocate one.
*/
reg_off_ll = alloc_reg();
}
/*
* Load the register containing the PPI length
* into the X register.
*/
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = reg_off_ll;
return s;
}
/*
* Generate code to compute the link-layer header length, if necessary,
* putting it into the X register, and to return either a pointer to a
* "struct slist" for the list of statements in that code, or NULL if
* no code is necessary.
*/
static struct slist *
gen_llprefixlen(void)
{
switch (linktype) {
case DLT_PRISM_HEADER:
return gen_prism_llprefixlen();
case DLT_IEEE802_11_RADIO_AVS:
return gen_avs_llprefixlen();
case DLT_IEEE802_11_RADIO:
return gen_radiotap_llprefixlen();
case DLT_PPI:
return gen_ppi_llprefixlen();
default:
return NULL;
}
}
/*
* Generate code to load the register containing the offset of the
* MAC-layer payload into the X register; if no register for that offset
* has been allocated, allocate it first.
*/
static struct slist *
gen_off_macpl(void)
{
struct slist *s;
if (off_macpl_is_variable) {
if (reg_off_macpl == -1) {
/*
* We haven't yet assigned a register for the offset
* of the MAC-layer payload; allocate one.
*/
reg_off_macpl = alloc_reg();
}
/*
* Load the register containing the offset of the MAC-layer
* payload into the X register.
*/
s = new_stmt(BPF_LDX|BPF_MEM);
s->s.k = reg_off_macpl;
return s;
} else {
/*
* That offset isn't variable, so we don't need to
* generate any code.
*/
return NULL;
}
}
/*
* Map an Ethernet type to the equivalent PPP type.
*/
static int
ethertype_to_ppptype(proto)
int proto;
{
switch (proto) {
case ETHERTYPE_IP:
proto = PPP_IP;
break;
#ifdef INET6
case ETHERTYPE_IPV6:
proto = PPP_IPV6;
break;
#endif
case ETHERTYPE_DN:
proto = PPP_DECNET;
break;
case ETHERTYPE_ATALK:
proto = PPP_APPLE;
break;
case ETHERTYPE_NS:
proto = PPP_NS;
break;
case LLCSAP_ISONS:
proto = PPP_OSI;
break;
case LLCSAP_8021D:
/*
* I'm assuming the "Bridging PDU"s that go
* over PPP are Spanning Tree Protocol
* Bridging PDUs.
*/
proto = PPP_BRPDU;
break;
case LLCSAP_IPX:
proto = PPP_IPX;
break;
}
return (proto);
}
/*
* Generate code to match a particular packet type by matching the
* link-layer type field or fields in the 802.2 LLC header.
*
* "proto" is an Ethernet type value, if > ETHERMTU, or an LLC SAP
* value, if <= ETHERMTU.
*/
static struct block *
gen_linktype(proto)
register int proto;
{
struct block *b0, *b1, *b2;
/* are we checking MPLS-encapsulated packets? */
if (label_stack_depth > 0) {
switch (proto) {
case ETHERTYPE_IP:
case PPP_IP:
/* FIXME add other L3 proto IDs */
return gen_mpls_linktype(Q_IP);
case ETHERTYPE_IPV6:
case PPP_IPV6:
/* FIXME add other L3 proto IDs */
return gen_mpls_linktype(Q_IPV6);
default:
bpf_error("unsupported protocol over mpls");
/* NOTREACHED */
}
}
/*
* Are we testing PPPoE packets?
*/
if (is_pppoes) {
/*
* The PPPoE session header is part of the
* MAC-layer payload, so all references
* should be relative to the beginning of
* that payload.
*/
/*
* We use Ethernet protocol types inside libpcap;
* map them to the corresponding PPP protocol types.
*/
proto = ethertype_to_ppptype(proto);
return gen_cmp(OR_MACPL, off_linktype, BPF_H, (bpf_int32)proto);
}
switch (linktype) {
case DLT_EN10MB:
case DLT_NETANALYZER:
case DLT_NETANALYZER_TRANSPARENT:
return gen_ether_linktype(proto);
/*NOTREACHED*/
break;
case DLT_C_HDLC:
switch (proto) {
case LLCSAP_ISONS:
proto = (proto << 8 | LLCSAP_ISONS);
/* fall through */
default:
return gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)proto);
/*NOTREACHED*/
break;
}
break;
case DLT_IEEE802_11:
case DLT_PRISM_HEADER:
case DLT_IEEE802_11_RADIO_AVS:
case DLT_IEEE802_11_RADIO:
case DLT_PPI:
/*
* Check that we have a data frame.
*/
b0 = gen_check_802_11_data_frame();
/*
* Now check for the specified link-layer type.
*/
b1 = gen_llc_linktype(proto);
gen_and(b0, b1);
return b1;
/*NOTREACHED*/
break;
case DLT_FDDI:
/*
* XXX - check for asynchronous frames, as per RFC 1103.
*/
return gen_llc_linktype(proto);
/*NOTREACHED*/
break;
case DLT_IEEE802:
/*
* XXX - check for LLC PDUs, as per IEEE 802.5.
*/
return gen_llc_linktype(proto);
/*NOTREACHED*/
break;
case DLT_ATM_RFC1483:
case DLT_ATM_CLIP:
case DLT_IP_OVER_FC:
return gen_llc_linktype(proto);
/*NOTREACHED*/
break;
case DLT_SUNATM:
/*
* If "is_lane" is set, check for a LANE-encapsulated
* version of this protocol, otherwise check for an
* LLC-encapsulated version of this protocol.
*
* We assume LANE means Ethernet, not Token Ring.
*/
if (is_lane) {
/*
* Check that the packet doesn't begin with an
* LE Control marker. (We've already generated
* a test for LANE.)
*/
b0 = gen_cmp(OR_LINK, SUNATM_PKT_BEGIN_POS, BPF_H,
0xFF00);
gen_not(b0);
/*
* Now generate an Ethernet test.
*/
b1 = gen_ether_linktype(proto);
gen_and(b0, b1);
return b1;
} else {
/*
* Check for LLC encapsulation and then check the
* protocol.
*/
b0 = gen_atmfield_code(A_PROTOTYPE, PT_LLC, BPF_JEQ, 0);
b1 = gen_llc_linktype(proto);
gen_and(b0, b1);
return b1;
}
/*NOTREACHED*/
break;
case DLT_LINUX_SLL:
return gen_linux_sll_linktype(proto);
/*NOTREACHED*/
break;
case DLT_SLIP:
case DLT_SLIP_BSDOS:
case DLT_RAW:
/*
* These types don't provide any type field; packets
* are always IPv4 or IPv6.
*
* XXX - for IPv4, check for a version number of 4, and,
* for IPv6, check for a version number of 6?
*/
switch (proto) {
case ETHERTYPE_IP:
/* Check for a version number of 4. */
return gen_mcmp(OR_LINK, 0, BPF_B, 0x40, 0xF0);
#ifdef INET6
case ETHERTYPE_IPV6:
/* Check for a version number of 6. */
return gen_mcmp(OR_LINK, 0, BPF_B, 0x60, 0xF0);
#endif
default:
return gen_false(); /* always false */
}
/*NOTREACHED*/
break;
case DLT_IPV4:
/*
* Raw IPv4, so no type field.
*/
if (proto == ETHERTYPE_IP)
return gen_true(); /* always true */
/* Checking for something other than IPv4; always false */
return gen_false();
/*NOTREACHED*/
break;
case DLT_IPV6:
/*
* Raw IPv6, so no type field.
*/
#ifdef INET6
if (proto == ETHERTYPE_IPV6)
return gen_true(); /* always true */
#endif
/* Checking for something other than IPv6; always false */
return gen_false();
/*NOTREACHED*/
break;
case DLT_PPP:
case DLT_PPP_PPPD:
case DLT_PPP_SERIAL:
case DLT_PPP_ETHER:
/*
* We use Ethernet protocol types inside libpcap;
* map them to the corresponding PPP protocol types.
*/
proto = ethertype_to_ppptype(proto);
return gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto);
/*NOTREACHED*/
break;
case DLT_PPP_BSDOS:
/*
* We use Ethernet protocol types inside libpcap;
* map them to the corresponding PPP protocol types.
*/
switch (proto) {
case ETHERTYPE_IP:
/*
* Also check for Van Jacobson-compressed IP.
* XXX - do this for other forms of PPP?
*/
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, PPP_IP);
b1 = gen_cmp(OR_LINK, off_linktype, BPF_H, PPP_VJC);
gen_or(b0, b1);
b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, PPP_VJNC);
gen_or(b1, b0);
return b0;
default:
proto = ethertype_to_ppptype(proto);
return gen_cmp(OR_LINK, off_linktype, BPF_H,
(bpf_int32)proto);
}
/*NOTREACHED*/
break;
case DLT_NULL:
case DLT_LOOP:
case DLT_ENC:
/*
* For DLT_NULL, the link-layer header is a 32-bit
* word containing an AF_ value in *host* byte order,
* and for DLT_ENC, the link-layer header begins
* with a 32-bit work containing an AF_ value in
* host byte order.
*
* In addition, if we're reading a saved capture file,
* the host byte order in the capture may not be the
* same as the host byte order on this machine.
*
* For DLT_LOOP, the link-layer header is a 32-bit
* word containing an AF_ value in *network* byte order.
*
* XXX - AF_ values may, unfortunately, be platform-
* dependent; for example, FreeBSD's AF_INET6 is 24
* whilst NetBSD's and OpenBSD's is 26.
*
* This means that, when reading a capture file, just
* checking for our AF_INET6 value won't work if the
* capture file came from another OS.
*/
switch (proto) {
case ETHERTYPE_IP:
proto = AF_INET;
break;
#ifdef INET6
case ETHERTYPE_IPV6:
proto = AF_INET6;
break;
#endif
default:
/*
* Not a type on which we support filtering.
* XXX - support those that have AF_ values
* #defined on this platform, at least?
*/
return gen_false();
}
if (linktype == DLT_NULL || linktype == DLT_ENC) {
/*
* The AF_ value is in host byte order, but
* the BPF interpreter will convert it to
* network byte order.
*
* If this is a save file, and it's from a
* machine with the opposite byte order to
* ours, we byte-swap the AF_ value.
*
* Then we run it through "htonl()", and
* generate code to compare against the result.
*/
if (bpf_pcap->sf.rfile != NULL &&
bpf_pcap->sf.swapped)
proto = SWAPLONG(proto);
proto = htonl(proto);
}
return (gen_cmp(OR_LINK, 0, BPF_W, (bpf_int32)proto));
#ifdef HAVE_NET_PFVAR_H
case DLT_PFLOG:
/*
* af field is host byte order in contrast to the rest of
* the packet.
*/
if (proto == ETHERTYPE_IP)
return (gen_cmp(OR_LINK, offsetof(struct pfloghdr, af),
BPF_B, (bpf_int32)AF_INET));
#ifdef INET6
else if (proto == ETHERTYPE_IPV6)
return (gen_cmp(OR_LINK, offsetof(struct pfloghdr, af),
BPF_B, (bpf_int32)AF_INET6));
#endif /* INET6 */
else
return gen_false();
/*NOTREACHED*/
break;
#endif /* HAVE_NET_PFVAR_H */
case DLT_ARCNET:
case DLT_ARCNET_LINUX:
/*
* XXX should we check for first fragment if the protocol
* uses PHDS?
*/
switch (proto) {
default:
return gen_false();
#ifdef INET6
case ETHERTYPE_IPV6:
return (gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_INET6));
#endif /* INET6 */
case ETHERTYPE_IP:
b0 = gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_IP);
b1 = gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_IP_OLD);
gen_or(b0, b1);
return (b1);
case ETHERTYPE_ARP:
b0 = gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_ARP);
b1 = gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_ARP_OLD);
gen_or(b0, b1);
return (b1);
case ETHERTYPE_REVARP:
return (gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_REVARP));
case ETHERTYPE_ATALK:
return (gen_cmp(OR_LINK, off_linktype, BPF_B,
(bpf_int32)ARCTYPE_ATALK));
}
/*NOTREACHED*/
break;
case DLT_LTALK:
switch (proto) {
case ETHERTYPE_ATALK:
return gen_true();
default:
return gen_false();
}
/*NOTREACHED*/
break;
case DLT_FRELAY:
/*
* XXX - assumes a 2-byte Frame Relay header with
* DLCI and flags. What if the address is longer?
*/
switch (proto) {
case ETHERTYPE_IP:
/*
* Check for the special NLPID for IP.
*/
return gen_cmp(OR_LINK, 2, BPF_H, (0x03<<8) | 0xcc);
#ifdef INET6
case ETHERTYPE_IPV6:
/*
* Check for the special NLPID for IPv6.
*/
return gen_cmp(OR_LINK, 2, BPF_H, (0x03<<8) | 0x8e);
#endif
case LLCSAP_ISONS:
/*
* Check for several OSI protocols.
*
* Frame Relay packets typically have an OSI
* NLPID at the beginning; we check for each
* of them.
*
* What we check for is the NLPID and a frame
* control field of UI, i.e. 0x03 followed
* by the NLPID.
*/
b0 = gen_cmp(OR_LINK, 2, BPF_H, (0x03<<8) | ISO8473_CLNP);
b1 = gen_cmp(OR_LINK, 2, BPF_H, (0x03<<8) | ISO9542_ESIS);
b2 = gen_cmp(OR_LINK, 2, BPF_H, (0x03<<8) | ISO10589_ISIS);
gen_or(b1, b2);
gen_or(b0, b2);
return b2;
default:
return gen_false();
}
/*NOTREACHED*/
break;
case DLT_MFR:
bpf_error("Multi-link Frame Relay link-layer type filtering not implemented");
case DLT_JUNIPER_MFR:
case DLT_JUNIPER_MLFR:
case DLT_JUNIPER_MLPPP:
case DLT_JUNIPER_ATM1:
case DLT_JUNIPER_ATM2:
case DLT_JUNIPER_PPPOE:
case DLT_JUNIPER_PPPOE_ATM:
case DLT_JUNIPER_GGSN:
case DLT_JUNIPER_ES:
case DLT_JUNIPER_MONITOR:
case DLT_JUNIPER_SERVICES:
case DLT_JUNIPER_ETHER:
case DLT_JUNIPER_PPP:
case DLT_JUNIPER_FRELAY:
case DLT_JUNIPER_CHDLC:
case DLT_JUNIPER_VP:
case DLT_JUNIPER_ST:
case DLT_JUNIPER_ISM:
case DLT_JUNIPER_VS:
case DLT_JUNIPER_SRX_E2E:
case DLT_JUNIPER_FIBRECHANNEL:
case DLT_JUNIPER_ATM_CEMIC:
/* just lets verify the magic number for now -
* on ATM we may have up to 6 different encapsulations on the wire
* and need a lot of heuristics to figure out that the payload
* might be;
*
* FIXME encapsulation specific BPF_ filters
*/
return gen_mcmp(OR_LINK, 0, BPF_W, 0x4d474300, 0xffffff00); /* compare the magic number */
case DLT_IPNET:
return gen_ipnet_linktype(proto);
case DLT_LINUX_IRDA:
bpf_error("IrDA link-layer type filtering not implemented");
case DLT_DOCSIS:
bpf_error("DOCSIS link-layer type filtering not implemented");
case DLT_MTP2:
case DLT_MTP2_WITH_PHDR:
bpf_error("MTP2 link-layer type filtering not implemented");
case DLT_ERF:
bpf_error("ERF link-layer type filtering not implemented");
case DLT_PFSYNC:
bpf_error("PFSYNC link-layer type filtering not implemented");
case DLT_LINUX_LAPD:
bpf_error("LAPD link-layer type filtering not implemented");
case DLT_USB:
case DLT_USB_LINUX:
case DLT_USB_LINUX_MMAPPED:
bpf_error("USB link-layer type filtering not implemented");
case DLT_BLUETOOTH_HCI_H4:
case DLT_BLUETOOTH_HCI_H4_WITH_PHDR:
bpf_error("Bluetooth link-layer type filtering not implemented");
case DLT_CAN20B:
case DLT_CAN_SOCKETCAN:
bpf_error("CAN link-layer type filtering not implemented");
case DLT_IEEE802_15_4:
case DLT_IEEE802_15_4_LINUX:
case DLT_IEEE802_15_4_NONASK_PHY:
case DLT_IEEE802_15_4_NOFCS:
bpf_error("IEEE 802.15.4 link-layer type filtering not implemented");
case DLT_IEEE802_16_MAC_CPS_RADIO:
bpf_error("IEEE 802.16 link-layer type filtering not implemented");
case DLT_SITA:
bpf_error("SITA link-layer type filtering not implemented");
case DLT_RAIF1:
bpf_error("RAIF1 link-layer type filtering not implemented");
case DLT_IPMB:
bpf_error("IPMB link-layer type filtering not implemented");
case DLT_AX25_KISS:
bpf_error("AX.25 link-layer type filtering not implemented");
}
/*
* All the types that have no encapsulation should either be
* handled as DLT_SLIP, DLT_SLIP_BSDOS, and DLT_RAW are, if
* all packets are IP packets, or should be handled in some
* special case, if none of them are (if some are and some
* aren't, the lack of encapsulation is a problem, as we'd
* have to find some other way of determining the packet type).
*
* Therefore, if "off_linktype" is -1, there's an error.
*/
if (off_linktype == (u_int)-1)
abort();
/*
* Any type not handled above should always have an Ethernet
* type at an offset of "off_linktype".
*/
return gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto);
}
/*
* Check for an LLC SNAP packet with a given organization code and
* protocol type; we check the entire contents of the 802.2 LLC and
* snap headers, checking for DSAP and SSAP of SNAP and a control
* field of 0x03 in the LLC header, and for the specified organization
* code and protocol type in the SNAP header.
*/
static struct block *
gen_snap(orgcode, ptype)
bpf_u_int32 orgcode;
bpf_u_int32 ptype;
{
u_char snapblock[8];
snapblock[0] = LLCSAP_SNAP; /* DSAP = SNAP */
snapblock[1] = LLCSAP_SNAP; /* SSAP = SNAP */
snapblock[2] = 0x03; /* control = UI */
snapblock[3] = (orgcode >> 16); /* upper 8 bits of organization code */
snapblock[4] = (orgcode >> 8); /* middle 8 bits of organization code */
snapblock[5] = (orgcode >> 0); /* lower 8 bits of organization code */
snapblock[6] = (ptype >> 8); /* upper 8 bits of protocol type */
snapblock[7] = (ptype >> 0); /* lower 8 bits of protocol type */
return gen_bcmp(OR_MACPL, 0, 8, snapblock);
}
/*
* Generate code to match a particular packet type, for link-layer types
* using 802.2 LLC headers.
*
* This is *NOT* used for Ethernet; "gen_ether_linktype()" is used
* for that - it handles the D/I/X Ethernet vs. 802.3+802.2 issues.
*
* "proto" is an Ethernet type value, if > ETHERMTU, or an LLC SAP
* value, if <= ETHERMTU. We use that to determine whether to
* match the DSAP or both DSAP and LSAP or to check the OUI and
* protocol ID in a SNAP header.
*/
static struct block *
gen_llc_linktype(proto)
int proto;
{
/*
* XXX - handle token-ring variable-length header.