gencode.c

用来监视网络通信数据的源代码和应用程序,方便网络程序底层开发.

/*#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[] =
    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.184 2003/01/23 07:24:51 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>
#include <sys/time.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>

#include "pcap-int.h"

#include "ethertype.h"
#include "nlpid.h"
#include "llc.h"
#include "gencode.h"
#include "atmuni31.h"
#include "sunatmpos.h"
#include "ppp.h"
#include "sll.h"
#include "arcnet.h"
#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 offsets. */
static u_int	orig_linktype = -1, orig_nl = -1, orig_nl_nosnap = -1;

/* XXX */
#ifdef PCAP_FDDIPAD
int	pcap_fddipad = PCAP_FDDIPAD;
#else
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(int);

static int alloc_reg(void);
static void free_reg(int);

static struct block *root;

/*
 * We divy out chunks of memory rather than call malloc each time so
 * we don't have to worry about leaking memory.  It's probably
 * not a big deal if all this memory was wasted but it this ever
 * goes into a library that would probably not be a good idea.
 */
#define NCHUNKS 16
#define CHUNK0SIZE 1024
struct chunk {
	u_int n_left;
	void *m;
};

static struct chunk chunks[NCHUNKS];
static int cur_chunk;

static void *newchunk(u_int);
static void freechunks(void);
static inline struct block *new_block(int);
static inline struct slist *new_stmt(int);
static struct block *gen_retblk(int);
static inline void syntax(void);

static void backpatch(struct block *, struct block *);
static void merge(struct block *, struct block *);
static struct block *gen_cmp(u_int, u_int, bpf_int32);
static struct block *gen_cmp_gt(u_int, u_int, bpf_int32);
static struct block *gen_mcmp(u_int, u_int, bpf_int32, bpf_u_int32);
static struct block *gen_bcmp(u_int, u_int, const u_char *);
static struct block *gen_ncmp(bpf_u_int32, bpf_u_int32, bpf_u_int32,
    bpf_u_int32, bpf_u_int32, int);
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_linktype(int);
static struct block *gen_snap(bpf_u_int32, bpf_u_int32, u_int);
static struct block *gen_llc(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, u_int);
static struct block *gen_host(bpf_u_int32, bpf_u_int32, int, int);
#ifdef INET6
static struct block *gen_host6(struct in6_addr *, struct in6_addr *, 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);
#ifdef INET6
static struct block *gen_portatom6(int, bpf_int32);
#endif
struct block *gen_portop(int, int, int);
static struct block *gen_port(int, int, int);
#ifdef INET6
struct block *gen_portop6(int, int, int);
static struct block *gen_port6(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_msg_abbrev(int type);

static void *
newchunk(n)
	u_int n;
{
	struct chunk *cp;
	int k, 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);
		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,
	     char *buf, int optimize, bpf_u_int32 mask)
{
	extern int n_errors;
	int len;

	no_optimize = 0;
	n_errors = 0;
	root = NULL;
	bpf_pcap = p;
	if (setjmp(top_ctx)) {
		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(buf ? buf : "");
	init_linktype(pcap_datalink(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,
	     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;
{
	backpatch(p, gen_retblk(snaplen));
	p->sense = !p->sense;
	backpatch(p, gen_retblk(0));
	root = p->head;
}

void
gen_and(b0, b1)
	struct block *b0, *b1;
{
	backpatch(b0, b1->head);
	b0->sense = !b0->sense;
	b1->sense = !b1->sense;
	merge(b1, b0);
	b1->sense = !b1->sense;
	b1->head = b0->head;
}

void
gen_or(b0, b1)
	struct block *b0, *b1;
{
	b0->sense = !b0->sense;
	backpatch(b0, b1->head);
	b0->sense = !b0->sense;
	merge(b1, b0);
	b1->head = b0->head;
}

void
gen_not(b)
	struct block *b;
{
	b->sense = !b->sense;
}

static struct block *
gen_cmp(offset, size, v)
	u_int offset, size;
	bpf_int32 v;
{
	struct slist *s;
	struct block *b;

	s = new_stmt(BPF_LD|BPF_ABS|size);
	s->s.k = offset;

	b = new_block(JMP(BPF_JEQ));
	b->stmts = s;
	b->s.k = v;

	return b;
}

static struct block *
gen_cmp_gt(offset, size, v)
	u_int offset, size;
	bpf_int32 v;
{
	struct slist *s;
	struct block *b;

	s = new_stmt(BPF_LD|BPF_ABS|size);
	s->s.k = offset;

	b = new_block(JMP(BPF_JGT));
	b->stmts = s;
	b->s.k = v;

	return b;
}

static struct block *
gen_mcmp(offset, size, v, mask)
	u_int offset, size;
	bpf_int32 v;
	bpf_u_int32 mask;
{
	struct block *b = gen_cmp(offset, size, v);
	struct slist *s;

	if (mask != 0xffffffff) {
		s = new_stmt(BPF_ALU|BPF_AND|BPF_K);
		s->s.k = mask;
		b->stmts->next = s;
	}
	return b;
}

static struct block *
gen_bcmp(offset, size, v)
	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(offset + size - 4, BPF_W, w);
		if (b != NULL)
			gen_and(b, tmp);
		b = tmp;