pcap.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.

/*
 * Copyright (c) 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 the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /tcpdump/master/libpcap/pcap.c,v 1.45 2003/01/23 07:24:52 guy Exp $ (LBL)";
#endif

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

#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#include <sys/types.h>
#endif /* WIN32 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef WIN32
#include <unistd.h>
#endif
#include <fcntl.h>
#include <errno.h>

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

#ifdef REMOTE
#include <pcap-remote.h>
#endif

#include "pcap-int.h"

int
pcap_dispatch(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{

	if (p->sf.rfile != NULL)
		return (pcap_offline_read(p, cnt, callback, user));
	return (pcap_read(p, cnt, callback, user));
}

int
pcap_loop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
	register int n;

	for (;;) {
		if (p->sf.rfile != NULL)
			n = pcap_offline_read(p, cnt, callback, user);
		else {
			/*
			 * XXX keep reading until we get something
			 * (or an error occurs)
			 */
			do {
				n = pcap_read(p, cnt, callback, user);
			} while (n == 0);
		}
		if (n <= 0)
			return (n);
		if (cnt > 0) {
			cnt -= n;
			if (cnt <= 0)
				return (0);
		}
	}
}

struct singleton {
	struct pcap_pkthdr *hdr;
	const u_char *pkt;
};


static void
pcap_oneshot(u_char *userData, const struct pcap_pkthdr *h, const u_char *pkt)
{
	struct singleton *sp = (struct singleton *)userData;
	*sp->hdr = *h;
	sp->pkt = pkt;
}

const u_char *
pcap_next(pcap_t *p, struct pcap_pkthdr *h)
{
	struct singleton s;

	s.hdr = h;
	if (pcap_dispatch(p, 1, pcap_oneshot, (u_char*)&s) <= 0)
		return (0);
	return (s.pkt);
}



// MODIFICATIONS FOR PCAP_NEXT_EX
struct pkt_for_fakecallback {
	struct pcap_pkthdr *hdr;
	const u_char **pkt;
};


static void
pcap_fakecallback(u_char *userData, const struct pcap_pkthdr *h, const u_char *pkt)
{
	struct pkt_for_fakecallback *sp = (struct pkt_for_fakecallback *)userData;
	*sp->hdr = *h;
	*sp->pkt = pkt;
}


int 
pcap_next_ex(pcap_t *p, struct pcap_pkthdr **pkt_header, u_char **pkt_data)
{
struct pkt_for_fakecallback s;

	s.hdr= &(p->pcap_header);
	s.pkt= pkt_data;

	// Saves a pointer to the packet headers
	*pkt_header= &(p->pcap_header);

	/* Check the capture type */
#ifdef REMOTE
	if (p->rmt_clientside)
	{
		/* We are on an remote capture */
		if (!p->rmt_capstarted)
		{
			// if the capture has not started yet, please start it
			if (pcap_startcapture_remote(p) )
				return -1;
			p->rmt_capstarted= 1;
		}

		return pcap_read_nocb_remote(p, pkt_header, pkt_data);
	}
#endif

	if (p->sf.rfile != NULL)
	{
	int status;

		/* We are on an offline capture */
		status= pcap_offline_read(p, 1, pcap_fakecallback, (u_char*)&s);

		/*
			Return codes for pcap_offline_read() are:
			-  0: EOF
			- -1: error
			- >1: OK
			The first one ('0') conflicts with the return code of the pcap_read()
		*/
		if (status == 0)
			return -2;
		else
			return status;
	}

	/*
		Return codes for pcap_read() are:
		-  0: timeout
		- -1: error
		- >1: OK
		The first one ('0') conflicts with the return code of the pcap_offline_read()
	*/
	return (pcap_read(p, 1, pcap_fakecallback, (u_char*)&s));
}
// END MODIFICATIONS FOR PCAP_NEXT_EX



int
pcap_datalink(pcap_t *p)
{
	return (p->linktype);
}

int
pcap_list_datalinks(pcap_t *p, int **dlt_buffer)
{
	if (p->dlt_count == 0) {
		/*
		 * We couldn't fetch the list of DLTs, which means
		 * this platform doesn't support changing the
		 * DLT for an interface.  Return a list of DLTs
		 * containing only the DLT this device supports.
		 */
		*dlt_buffer = (int*)malloc(sizeof(**dlt_buffer));
		if (*dlt_buffer == NULL) {
			(void)snprintf(p->errbuf, sizeof(p->errbuf),
			    "malloc: %s", pcap_strerror(errno));
			return (-1);
		}
		**dlt_buffer = p->linktype;
		return (1);
	} else {
		*dlt_buffer = (int*)malloc(sizeof(**dlt_buffer) * p->dlt_count);
		if (*dlt_buffer == NULL) {
			(void)snprintf(p->errbuf, sizeof(p->errbuf),
			    "malloc: %s", pcap_strerror(errno));
			return (-1);
		}
		(void)memcpy(*dlt_buffer, p->dlt_list,
		    sizeof(**dlt_buffer) * p->dlt_count);
		return (p->dlt_count);
	}
}

int
pcap_set_datalink(pcap_t *p, int dlt)
{
	int i;
	const char *dlt_name;

	if (p->dlt_count == 0) {
		/*
		 * We couldn't fetch the list of DLTs, which means
		 * this platform doesn't support changing the
		 * DLT for an interface.  Check whether the new
		 * DLT is the one this interface supports.
		 */
		if (p->linktype != dlt)
			goto unsupported;

		/*
		 * It is, so there's nothing we need to do here.
		 */
		return (0);
	}
	for (i = 0; i < p->dlt_count; i++)
		if (p->dlt_list[i] == dlt)
			break;
	if (i >= p->dlt_count)
		goto unsupported;
	if (pcap_set_datalink_platform(p, dlt) == -1)
		return (-1);
	p->linktype = dlt;
	return (0);

unsupported:
	dlt_name = pcap_datalink_val_to_name(dlt);
	if (dlt_name != NULL) {
		(void) snprintf(p->errbuf, sizeof(p->errbuf),
		    "%s is not one of the DLTs supported by this device",
		    dlt_name);
	} else {
		(void) snprintf(p->errbuf, sizeof(p->errbuf),
		    "DLT %d is not one of the DLTs supported by this device",
		    dlt);
	}
	return (-1);
}

struct dlt_choice {
	const char *name;
	int	dlt;
};

#define DLT_CHOICE(code) { #code, code }
#define DLT_CHOICE_SENTINEL { NULL, 0 }

static struct dlt_choice dlt_choices[] = {
	DLT_CHOICE(DLT_ARCNET),
	DLT_CHOICE(DLT_ARCNET_LINUX),
	DLT_CHOICE(DLT_EN10MB),
	DLT_CHOICE(DLT_SLIP),
	DLT_CHOICE(DLT_SLIP_BSDOS),
	DLT_CHOICE(DLT_NULL),
	DLT_CHOICE(DLT_LOOP),
	DLT_CHOICE(DLT_PPP),
	DLT_CHOICE(DLT_C_HDLC),
	DLT_CHOICE(DLT_PPP_SERIAL),
	DLT_CHOICE(DLT_PPP_ETHER),
	DLT_CHOICE(DLT_PPP_BSDOS),
	DLT_CHOICE(DLT_FDDI),
	DLT_CHOICE(DLT_IEEE802),
	DLT_CHOICE(DLT_IEEE802_11),
	DLT_CHOICE(DLT_PRISM_HEADER),
	DLT_CHOICE(DLT_IEEE802_11_RADIO),
	DLT_CHOICE(DLT_ATM_RFC1483),
	DLT_CHOICE(DLT_ATM_CLIP),
	DLT_CHOICE(DLT_SUNATM),
	DLT_CHOICE(DLT_RAW),
	DLT_CHOICE(DLT_LINUX_SLL),
	DLT_CHOICE(DLT_LTALK),
	DLT_CHOICE(DLT_IP_OVER_FC),
	DLT_CHOICE(DLT_FRELAY),
	DLT_CHOICE_SENTINEL
};

/*
 * This array is designed for mapping upper and lower case letter
 * together for a case independent comparison.  The mappings are
 * based upon ascii character sequences.
 */
static const u_char charmap[] = {
	(u_char)'\000', (u_char)'\001', (u_char)'\002', (u_char)'\003',
	(u_char)'\004', (u_char)'\005', (u_char)'\006', (u_char)'\007',
	(u_char)'\010', (u_char)'\011', (u_char)'\012', (u_char)'\013',
	(u_char)'\014', (u_char)'\015', (u_char)'\016', (u_char)'\017',
	(u_char)'\020', (u_char)'\021', (u_char)'\022', (u_char)'\023',
	(u_char)'\024', (u_char)'\025', (u_char)'\026', (u_char)'\027',
	(u_char)'\030', (u_char)'\031', (u_char)'\032', (u_char)'\033',
	(u_char)'\034', (u_char)'\035', (u_char)'\036', (u_char)'\037',
	(u_char)'\040', (u_char)'\041', (u_char)'\042', (u_char)'\043',
	(u_char)'\044', (u_char)'\045', (u_char)'\046', (u_char)'\047',
	(u_char)'\050', (u_char)'\051', (u_char)'\052', (u_char)'\053',
	(u_char)'\054', (u_char)'\055', (u_char)'\056', (u_char)'\057',