inet.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.

/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
/*
 * Copyright (c) 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/inet.c,v 1.54 2002/12/22 02:36:48 guy Exp $ (LBL)";
#endif

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

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

#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif
#include <sys/time.h>				/* concession to AIX */

struct mbuf;		/* Squelch compiler warnings on some platforms for */
struct rtentry;		/* declarations in <net/if.h> */
#include <net/if.h>
#include <netinet/in.h>
#endif /* WIN32 */

#include <ctype.h>
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef WIN32
#include <unistd.h>
#endif /* WIN32 */
#ifdef HAVE_LIMITS_H
#include <limits.h>
#else
#define INT_MAX		2147483647
#endif
#ifdef HAVE_IFADDRS_H
#include <ifaddrs.h>
#endif

#include "pcap-int.h"

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

/* Not all systems have IFF_LOOPBACK */
#ifdef IFF_LOOPBACK
#define ISLOOPBACK(name, flags) ((flags) & IFF_LOOPBACK)
#else
#define ISLOOPBACK(name, flags) ((name)[0] == 'l' && (name)[1] == 'o' && \
    (isdigit((unsigned char)((name)[2])) || (name)[2] == '\0'))
#endif

struct sockaddr *
dup_sockaddr(struct sockaddr *sa, size_t sa_length)
{
	struct sockaddr *newsa;

	if ((newsa = malloc(sa_length)) == NULL)
		return (NULL);
	return (memcpy(newsa, sa, sa_length));
}

static int
get_instance(const char *name)
{
	const char *cp, *endcp;
	int n;

	if (strcmp(name, "any") == 0) {
		/*
		 * Give the "any" device an artificially high instance
		 * number, so it shows up after all other non-loopback
		 * interfaces.
		 */
		return INT_MAX;
	}

	endcp = name + strlen(name);
	for (cp = name; cp < endcp && !isdigit((unsigned char)*cp); ++cp)
		continue;

	if (isdigit((unsigned char)*cp))
		n = atoi(cp);
	else
		n = 0;
	return (n);
}

int
add_or_find_if(pcap_if_t **curdev_ret, pcap_if_t **alldevs, const char *name,
    u_int flags, const char *description, char *errbuf)
{
	pcap_t *p;
	pcap_if_t *curdev, *prevdev, *nextdev;
	int this_instance;

	/*
	 * Can we open this interface for live capture?
	 */
	p = pcap_open_live(name, 68, 0, 0, errbuf);
	if (p == NULL) {
		/*
		 * No.  Don't bother including it.
		 * Don't treat this as an error, though.
		 */
		*curdev_ret = NULL;
		return (0);
	}
	pcap_close(p);

	/*
	 * Is there already an entry in the list for this interface?
	 */
	for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
		if (strcmp(name, curdev->name) == 0)
			break;	/* yes, we found it */
	}
	if (curdev == NULL) {
		/*
		 * No, we didn't find it.
		 * Allocate a new entry.
		 */
		curdev = malloc(sizeof(pcap_if_t));
		if (curdev == NULL) {
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			return (-1);
		}

		/*
		 * Fill in the entry.
		 */
		curdev->next = NULL;
		curdev->name = malloc(strlen(name) + 1);
		strcpy(curdev->name, name);
		if (description != NULL) {
			/*
			 * We have a description for this interface.
			 */
			curdev->description = malloc(strlen(description) + 1);
			strcpy(curdev->description, description);
		} else {
			/*
			 * We don't.
			 */
			curdev->description = NULL;
		}
		curdev->addresses = NULL;	/* list starts out as empty */
		curdev->flags = 0;
		if (ISLOOPBACK(name, flags))
			curdev->flags |= PCAP_IF_LOOPBACK;

		/*
		 * Add it to the list, in the appropriate location.
		 * First, get the instance number of this interface.
		 */
		this_instance = get_instance(name);

		/*
		 * Now look for the last interface with an instance number
		 * less than or equal to the new interface's instance
		 * number - except that non-loopback interfaces are
		 * arbitrarily treated as having interface numbers less
		 * than those of loopback interfaces, so the loopback
		 * interfaces are put at the end of the list.
		 *
		 * We start with "prevdev" being NULL, meaning we're before
		 * the first element in the list.
		 */
		prevdev = NULL;
		for (;;) {
			/*
			 * Get the interface after this one.
			 */
			if (prevdev == NULL) {
				/*
				 * The next element is the first element.
				 */
				nextdev = *alldevs;
			} else
				nextdev = prevdev->next;

			/*
			 * Are we at the end of the list?
			 */
			if (nextdev == NULL) {
				/*
				 * Yes - we have to put the new entry
				 * after "prevdev".
				 */
				break;
			}

			/*
			 * Is the new interface a non-loopback interface
			 * and the next interface a loopback interface?
			 */
			if (!(curdev->flags & PCAP_IF_LOOPBACK) &&
			    (nextdev->flags & PCAP_IF_LOOPBACK)) {
				/*
				 * Yes, we should put the new entry
				 * before "nextdev", i.e. after "prevdev".
				 */
				break;
			}

			/*
			 * Is the new interface's instance number less
			 * than the next interface's instance number,
			 * and is it the case that the new interface is a
			 * non-loopback interface or the next interface is
			 * a loopback interface?
			 *
			 * (The goal of both loopback tests is to make
			 * sure that we never put a loopback interface
			 * before any non-loopback interface and that we
			 * always put a non-loopback interface before all
			 * loopback interfaces.)
			 */
			if (this_instance < get_instance(nextdev->name) &&
			    (!(curdev->flags & PCAP_IF_LOOPBACK) ||
			       (nextdev->flags & PCAP_IF_LOOPBACK))) {
				/*
				 * Yes - we should put the new entry
				 * before "nextdev", i.e. after "prevdev".
				 */
				break;
			}

			prevdev = nextdev;
		}

		/*
		 * Insert before "nextdev".
		 */
		curdev->next = nextdev;

		/*
		 * Insert after "prevdev" - unless "prevdev" is null,
		 * in which case this is the first interface.
		 */
		if (prevdev == NULL) {
			/*
			 * This is the first interface.  Pass back a
			 * pointer to it, and put "curdev" before
			 * "nextdev".
			 */
			*alldevs = curdev;
		} else
			prevdev->next = curdev;
	}

	*curdev_ret = curdev;
	return (0);
}

int
add_addr_to_iflist(pcap_if_t **alldevs, char *name, u_int flags,
    struct sockaddr *addr, size_t addr_size,
    struct sockaddr *netmask, size_t netmask_size,
    struct sockaddr *broadaddr, size_t broadaddr_size,
    struct sockaddr *dstaddr, size_t dstaddr_size,
    char *errbuf)
{
	pcap_if_t *curdev;
	pcap_addr_t *curaddr, *prevaddr, *nextaddr;

	if (add_or_find_if(&curdev, alldevs, name, flags, NULL, errbuf) == -1) {
		/*
		 * Error - give up.
		 */
		return (-1);
	}
	if (curdev == NULL) {
		/*
		 * Device wasn't added because it can't be opened.
		 * Not a fatal error.
		 */
		return (0);
	}

	/*
	 * "curdev" is an entry for this interface; add an entry for this
	 * address to its list of addresses.
	 *
	 * Allocate the new entry and fill it in.
	 */
	curaddr = malloc(sizeof(pcap_addr_t));
	if (curaddr == NULL) {
		(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,