if.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 158 行

#ifndef lint
static	char	*sccsid = "@(#)if.c	4.4	(ULTRIX)	10/15/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1984,1988 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */
/*
 * 12 June 90 - Peter Grehan, TaN, Sydney, Australia.
 *		Changed the same(,) macro to only compare the Internet address
 *		field of a sockaddr structure.
 */
/*
#ifndef lint
static char sccsid[] = "@(#)if.c	4.4 (Berkeley) 10/15/90";
#endif not lint
*/
/*
 * Routing Table Management Daemon
 */
#include "defs.h"

extern	struct interface *ifnet;

/*
 * Find the interface with address addr.
 */
struct interface *
if_ifwithaddr(addr)
	struct sockaddr *addr;
{
	register struct interface *ifp;

#define	same(a1, a2) \
 	(bcmp( &(a1)->sa_data[2], &(a2)->sa_data[2], 4) == 0) 
	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
		if (ifp->int_flags & IFF_REMOTE)
			continue;
		if (ifp->int_addr.sa_family != addr->sa_family)
			continue;
		if (same(&ifp->int_addr, addr))
			break;
		if ((ifp->int_flags & IFF_BROADCAST) &&
		    same(&ifp->int_broadaddr, addr))
			break;
	}
	return (ifp);
}

/*
 * Find the point-to-point interface with destination address addr.
 */
struct interface *
if_ifwithdstaddr(addr)
	struct sockaddr *addr;
{
	register struct interface *ifp;

	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
		if ((ifp->int_flags & IFF_POINTOPOINT) == 0)
			continue;
		if (same(&ifp->int_dstaddr, addr))
			break;
	}
	return (ifp);
}

/*
 * Find the interface on the network 
 * of the specified address.
 */
struct interface *
if_ifwithnet(addr)
	register struct sockaddr *addr;
{
	register struct interface *ifp;
	register int af = addr->sa_family;
	register int (*netmatch)();

	if (af >= af_max)
		return (0);
	netmatch = afswitch[af].af_netmatch;
	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
		if (ifp->int_flags & IFF_REMOTE)
			continue;
		if (af != ifp->int_addr.sa_family)
			continue;
		if ((*netmatch)(addr, &ifp->int_addr))
			break;
	}
	return (ifp);
}

/*
 * Find an interface from which the specified address
 * should have come from.  Used for figuring out which
 * interface a packet came in on -- for tracing.
 */
struct interface *
if_iflookup(addr)
	struct sockaddr *addr;
{
	register struct interface *ifp, *maybe;
	register int af = addr->sa_family;
	register int (*netmatch)();

	if (af >= af_max)
		return (0);
	maybe = 0;
	netmatch = afswitch[af].af_netmatch;
	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
		if (ifp->int_addr.sa_family != af)
			continue;
		if (same(&ifp->int_addr, addr))
			break;
		if ((ifp->int_flags & IFF_BROADCAST) &&
		    same(&ifp->int_broadaddr, addr))
			break;
		if ((ifp->int_flags & IFF_POINTOPOINT) &&
		    same(&ifp->int_dstaddr, addr))
			break;
		if (maybe == 0 && (*netmatch)(addr, &ifp->int_addr))
			maybe = ifp;
	}
	if (ifp == 0)
		ifp = maybe;
	return (ifp);
}