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gencode.c
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gencode.c
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/*#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 */
#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>
#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 "arcnet.h"
#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_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;
int
pcap_compile(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
{
extern int n_errors;
const char * volatile xbuf = buf;
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.
*/
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:
/*