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if_nameindex.c revision 1.3 
      1 /*	$NetBSD: if_nameindex.c,v 1.3 2000/07/06 02:55:45 christos Exp $	*/
      2 /*	$KAME: if_nameindex.c,v 1.3 2000/04/24 10:08:41 itojun Exp $	*/
      3 
      4 /*-
      5  * Copyright (c) 1997, 2000
      6  *	Berkeley Software Design, Inc.  All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
     15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     17  * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
     18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     24  * SUCH DAMAGE.
     25  *
     26  *	BSDI Id: if_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #if defined(LIBC_SCCS) && !defined(lint)
     31 __RCSID("$NetBSD: if_nameindex.c,v 1.3 2000/07/06 02:55:45 christos Exp $");
     32 #endif /* LIBC_SCCS and not lint */
     33 
     34 #include "namespace.h"
     35 #include <sys/types.h>
     36 #include <sys/socket.h>
     37 #include <net/if_dl.h>
     38 #include <net/if.h>
     39 #include <ifaddrs.h>
     40 #include <stdlib.h>
     41 #include <string.h>
     42 
     43 #ifdef __weak_alias
     44 __weak_alias(if_nameindex,_if_nameindex)
     45 __weak_alias(if_freenameindex,_if_freenameindex)
     46 #endif
     47 /*
     48  * From RFC 2133:
     49  *
     50  * 4.3.  Return All Interface Names and Indexes
     51  *
     52  *    The final function returns an array of if_nameindex structures, one
     53  *    structure per interface.
     54  *
     55  *        #include <net/if.h>
     56  *
     57  *        struct if_nameindex {
     58  *          unsigned int   if_index;  / * 1, 2, ... * /
     59  *          char          *if_name;   / * null terminated name: "le0", ... * /
     60  *        };
     61  *
     62  *        struct if_nameindex  *if_nameindex(void);
     63  *
     64  *    The end of the array of structures is indicated by a structure with
     65  *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
     66  *    pointer upon an error.
     67  *
     68  *    The memory used for this array of structures along with the interface
     69  *    names pointed to by the if_name members is obtained dynamically.
     70  *    This memory is freed by the next function.
     71  *
     72  * 4.4.  Free Memory
     73  *
     74  *    The following function frees the dynamic memory that was allocated by
     75  *    if_nameindex().
     76  *
     77  *        #include <net/if.h>
     78  *
     79  *        void  if_freenameindex(struct if_nameindex *ptr);
     80  *
     81  *    The argument to this function must be a pointer that was returned by
     82  *    if_nameindex().
     83  */
     84 
     85 struct if_nameindex *
     86 if_nameindex(void)
     87 {
     88 	struct ifaddrs *ifaddrs, *ifa;
     89 	unsigned int ni;
     90 	int nbytes;
     91 	struct if_nameindex *ifni, *ifni2;
     92 	char *cp;
     93 
     94 	if (getifaddrs(&ifaddrs) < 0)
     95 		return(NULL);
     96 
     97 	/*
     98 	 * First, find out how many interfaces there are, and how
     99 	 * much space we need for the string names.
    100 	 */
    101 	ni = 0;
    102 	nbytes = 0;
    103 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
    104 		if (ifa->ifa_addr &&
    105 		    ifa->ifa_addr->sa_family == AF_LINK) {
    106 			nbytes += strlen(ifa->ifa_name) + 1;
    107 			ni++;
    108 		}
    109 	}
    110 
    111 	/*
    112 	 * Next, allocate a chunk of memory, use the first part
    113 	 * for the array of structures, and the last part for
    114 	 * the strings.
    115 	 */
    116 	cp = malloc(ni*(sizeof(struct if_nameindex) + 1) + nbytes);
    117 	ifni = (struct if_nameindex *)(void *)cp;
    118 	if (ifni == NULL)
    119 		goto out;
    120 	cp += ni*(sizeof(struct if_nameindex) + 1);
    121 
    122 	/*
    123 	 * Now just loop through the list of interfaces again,
    124 	 * filling in the if_nameindex array and making copies
    125 	 * of all the strings.
    126 	 */
    127 	ifni2 = ifni;
    128 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
    129 		if (ifa->ifa_addr &&
    130 		    ifa->ifa_addr->sa_family == AF_LINK) {
    131 			ifni2->if_index =
    132 			    ((struct sockaddr_dl*)
    133 			    (void *)ifa->ifa_addr)->sdl_index;
    134 			ifni2->if_name = cp;
    135 			strcpy(cp, ifa->ifa_name);
    136 			ifni2++;
    137 			cp += strlen(cp) + 1;
    138 		}
    139 	}
    140 	/*
    141 	 * Finally, don't forget to terminate the array.
    142 	 */
    143 	ifni2->if_index = 0;
    144 	ifni2->if_name = NULL;
    145 out:
    146 	freeifaddrs(ifaddrs);
    147 	return(ifni);
    148 }
    149 
    150 void
    151 if_freenameindex(struct if_nameindex *ptr)
    152 {
    153 	free(ptr);
    154 }
    155