pcap-pf.c

Windows XP下的抓包程序实现

/*
 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
 *	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.
 *
 * packet filter subroutines for tcpdump
 *	Extraction/creation by Jeffrey Mogul, DECWRL
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.91.2.2 2005/05/03 18:54:37 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <net/pfilt.h>

struct mbuf;
struct rtentry;
#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>

#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * Make "pcap.h" not include "pcap-bpf.h"; we are going to include the
 * native OS version, as we need various BPF ioctls from it.
 */
#define PCAP_DONT_INCLUDE_PCAP_BPF_H
#include <net/bpf.h>

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

static int pcap_setfilter_pf(pcap_t *, struct bpf_program *);

/*
 * BUFSPACE is the size in bytes of the packet read buffer.  Most tcpdump
 * applications aren't going to need more than 200 bytes of packet header
 * and the read shouldn't return more packets than packetfilter's internal
 * queue limit (bounded at 256).
 */
#define BUFSPACE (200 * 256)

static int
pcap_read_pf(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
{
	register u_char *p, *bp;
	struct bpf_insn *fcode;
	register int cc, n, buflen, inc;
	register struct enstamp *sp;
#ifdef LBL_ALIGN
	struct enstamp stamp;
#endif
#ifdef PCAP_FDDIPAD
	register int pad;
#endif

	fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
 again:
	cc = pc->cc;
	if (cc == 0) {
		cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
		if (cc < 0) {
			if (errno == EWOULDBLOCK)
				return (0);
			if (errno == EINVAL &&
			    lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
				/*
				 * Due to a kernel bug, after 2^31 bytes,
				 * the kernel file offset overflows and
				 * read fails with EINVAL. The lseek()
				 * to 0 will fix things.
				 */
				(void)lseek(pc->fd, 0L, SEEK_SET);
				goto again;
			}
			snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
				pcap_strerror(errno));
			return (-1);
		}
		bp = pc->buffer + pc->offset;
	} else
		bp = pc->bp;
	/*
	 * Loop through each packet.
	 */
	n = 0;
#ifdef PCAP_FDDIPAD
	pad = pc->fddipad;
#endif
	while (cc > 0) {
		/*
		 * Has "pcap_breakloop()" been called?
		 * If so, return immediately - if we haven't read any
		 * packets, clear the flag and return -2 to indicate
		 * that we were told to break out of the loop, otherwise
		 * leave the flag set, so that the *next* call will break
		 * out of the loop without having read any packets, and
		 * return the number of packets we've processed so far.
		 */
		if (pc->break_loop) {
			if (n == 0) {
				pc->break_loop = 0;
				return (-2);
			} else {
				pc->cc = cc;
				pc->bp = bp;
				return (n);
			}
		}
		if (cc < sizeof(*sp)) {
			snprintf(pc->errbuf, sizeof(pc->errbuf),
			    "pf short read (%d)", cc);
			return (-1);
		}
#ifdef LBL_ALIGN
		if ((long)bp & 3) {
			sp = &stamp;
			memcpy((char *)sp, (char *)bp, sizeof(*sp));
		} else
#endif
			sp = (struct enstamp *)bp;
		if (sp->ens_stamplen != sizeof(*sp)) {
			snprintf(pc->errbuf, sizeof(pc->errbuf),
			    "pf short stamplen (%d)",
			    sp->ens_stamplen);
			return (-1);
		}

		p = bp + sp->ens_stamplen;
		buflen = sp->ens_count;
		if (buflen > pc->snapshot)
			buflen = pc->snapshot;

		/* Calculate inc before possible pad update */
		inc = ENALIGN(buflen + sp->ens_stamplen);
		cc -= inc;
		bp += inc;
		pc->md.TotPkts++;
		pc->md.TotDrops += sp->ens_dropped;
		pc->md.TotMissed = sp->ens_ifoverflows;
		if (pc->md.OrigMissed < 0)
			pc->md.OrigMissed = pc->md.TotMissed;

		/*
		 * Short-circuit evaluation: if using BPF filter
		 * in kernel, no need to do it now.
		 *
#ifdef PCAP_FDDIPAD
		 * Note: the filter code was generated assuming
		 * that pc->fddipad was the amount of padding
		 * before the header, as that's what's required
		 * in the kernel, so we run the filter before
		 * skipping that padding.
#endif
		 */
		if (fcode == NULL ||
		    bpf_filter(fcode, p, sp->ens_count, buflen)) {
			struct pcap_pkthdr h;
			pc->md.TotAccepted++;
			h.ts = sp->ens_tstamp;
#ifdef PCAP_FDDIPAD
			h.len = sp->ens_count - pad;
#else
			h.len = sp->ens_count;
#endif
#ifdef PCAP_FDDIPAD
			p += pad;
			buflen -= pad;
#endif
			h.caplen = buflen;
			(*callback)(user, &h, p);
			if (++n >= cnt && cnt > 0) {
				pc->cc = cc;
				pc->bp = bp;
				return (n);
			}
		}
	}
	pc->cc = 0;
	return (n);
}

static int
pcap_inject_pf(pcap_t *p, const void *buf, size_t size)
{
	int ret;

	ret = write(p->fd, buf, size);
	if (ret == -1) {
		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
		    pcap_strerror(errno));
		return (-1);
	}
	return (ret);
}                           

static int
pcap_stats_pf(pcap_t *p, struct pcap_stat *ps)
{

	/*
	 * If packet filtering is being done in the kernel:
	 *
	 *	"ps_recv" counts only packets that passed the filter.
	 *	This does not include packets dropped because we
	 *	ran out of buffer space.  (XXX - perhaps it should,
	 *	by adding "ps_drop" to "ps_recv", for compatibility
	 *	with some other platforms.  On the other hand, on
	 *	some platforms "ps_recv" counts only packets that
	 *	passed the filter, and on others it counts packets
	 *	that didn't pass the filter....)
	 *
	 *	"ps_drop" counts packets that passed the kernel filter
	 *	(if any) but were dropped because the input queue was
	 *	full.
	 *
	 *	"ps_ifdrop" counts packets dropped by the network
	 *	inteface (regardless of whether they would have passed
	 *	the input filter, of course).
	 *
	 * If packet filtering is not being done in the kernel:
	 *
	 *	"ps_recv" counts only packets that passed the filter.
	 *
	 *	"ps_drop" counts packets that were dropped because the
	 *	input queue was full, regardless of whether they passed
	 *	the userland filter.
	 *
	 *	"ps_ifdrop" counts packets dropped by the network
	 *	inteface (regardless of whether they would have passed
	 *	the input filter, of course).
	 *
	 * These statistics don't include packets not yet read from
	 * the kernel by libpcap, but they may include packets not
	 * yet read from libpcap by the application.
	 */
	ps->ps_recv = p->md.TotAccepted;
	ps->ps_drop = p->md.TotDrops;
	ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
	return (0);
}

/*
 * We include the OS's <net/bpf.h>, not our "pcap-bpf.h", so we probably
 * don't get DLT_DOCSIS defined.
 */
#ifndef DLT_DOCSIS
#define DLT_DOCSIS	143
#endif

pcap_t *
pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
    char *ebuf)
{
	pcap_t *p;
	short enmode;
	int backlog = -1;	/* request the most */
	struct enfilter Filter;
	struct endevp devparams;

	p = (pcap_t *)malloc(sizeof(*p));
	if (p == NULL) {