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if.c revision 1.6 
      1 /*
      2  * Copyright (c) 1983, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 /*static char sccsid[] = "from: @(#)if.c	8.1 (Berkeley) 6/5/93";*/
     36 static char *rcsid = "$Id: if.c,v 1.6 1994/09/23 23:49:23 mycroft Exp $";
     37 #endif /* not lint */
     38 
     39 /*
     40  * Routing Table Management Daemon
     41  */
     42 #include "defs.h"
     43 
     44 extern	struct interface *ifnet;
     45 
     46 /*
     47  * Find the interface with address addr.
     48  */
     49 struct interface *
     50 if_ifwithaddr(addr)
     51 	struct sockaddr *addr;
     52 {
     53 	register struct interface *ifp;
     54 
     55 #define	same(a1, a2) \
     56 	(memcmp((a1)->sa_data, (a2)->sa_data, 14) == 0)
     57 	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
     58 		if (ifp->int_flags & IFF_REMOTE)
     59 			continue;
     60 		if (ifp->int_addr.sa_family != addr->sa_family)
     61 			continue;
     62 		if (same(&ifp->int_addr, addr))
     63 			break;
     64 		if ((ifp->int_flags & IFF_BROADCAST) &&
     65 		    same(&ifp->int_broadaddr, addr))
     66 			break;
     67 	}
     68 	return (ifp);
     69 }
     70 
     71 /*
     72  * Find the point-to-point interface with destination address addr.
     73  */
     74 struct interface *
     75 if_ifwithdstaddr(addr)
     76 	struct sockaddr *addr;
     77 {
     78 	register struct interface *ifp;
     79 
     80 	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
     81 		if ((ifp->int_flags & IFF_POINTOPOINT) == 0)
     82 			continue;
     83 		if (same(&ifp->int_dstaddr, addr))
     84 			break;
     85 	}
     86 	return (ifp);
     87 }
     88 
     89 /*
     90  * Find the interface on the network
     91  * of the specified address.
     92  */
     93 struct interface *
     94 if_ifwithnet(addr)
     95 	register struct sockaddr *addr;
     96 {
     97 	register struct interface *ifp;
     98 	register int af = addr->sa_family;
     99 	register int (*netmatch)();
    100 
    101 	if (af >= af_max)
    102 		return (0);
    103 	netmatch = afswitch[af].af_netmatch;
    104 	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
    105 		if (ifp->int_flags & IFF_REMOTE)
    106 			continue;
    107 		if (af != ifp->int_addr.sa_family)
    108 			continue;
    109 		if ((*netmatch)(addr, &ifp->int_addr))
    110 			break;
    111 	}
    112 	return (ifp);
    113 }
    114 
    115 /*
    116  * Find an interface from which the specified address
    117  * should have come from.  Used for figuring out which
    118  * interface a packet came in on -- for tracing.
    119  */
    120 struct interface *
    121 if_iflookup(addr)
    122 	struct sockaddr *addr;
    123 {
    124 	register struct interface *ifp, *maybe;
    125 	register int af = addr->sa_family;
    126 	register int (*netmatch)();
    127 
    128 	if (af >= af_max)
    129 		return (0);
    130 	maybe = 0;
    131 	netmatch = afswitch[af].af_netmatch;
    132 	for (ifp = ifnet; ifp; ifp = ifp->int_next) {
    133 		if (ifp->int_addr.sa_family != af)
    134 			continue;
    135 		if (same(&ifp->int_addr, addr))
    136 			break;
    137 		if ((ifp->int_flags & IFF_BROADCAST) &&
    138 		    same(&ifp->int_broadaddr, addr))
    139 			break;
    140 		if ((ifp->int_flags & IFF_POINTOPOINT) &&
    141 		    same(&ifp->int_dstaddr, addr))
    142 			break;
    143 		if (maybe == 0 && (*netmatch)(addr, &ifp->int_addr))
    144 			maybe = ifp;
    145 	}
    146 	if (ifp == 0)
    147 		ifp = maybe;
    148 	return (ifp);
    149 }
    150