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      1 /*	$NetBSD: if_nameindex.c,v 1.7 2012/03/13 21:13:41 christos Exp $	*/
      2 /*	$KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 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 1.7 2012/03/13 21:13:41 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 2553:
     49  *
     50  * 4.3 Return All Interface Names and Indexes
     51  *
     52  *    The if_nameindex structure holds the information about a single
     53  *    interface and is defined as a result of including the <net/if.h>
     54  *    header.
     55  *
     56  *       struct if_nameindex {
     57  *         unsigned int   if_index;
     58  *         char          *if_name;
     59  *       };
     60  *
     61  *    The final function returns an array of if_nameindex structures, one
     62  *    structure per interface.
     63  *
     64  *       struct if_nameindex  *if_nameindex(void);
     65  *
     66  *    The end of the array of structures is indicated by a structure with
     67  *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
     68  *    pointer upon an error, and would set errno to the appropriate value.
     69  *
     70  *    The memory used for this array of structures along with the interface
     71  *    names pointed to by the if_name members is obtained dynamically.
     72  *    This memory is freed by the next function.
     73  *
     74  * 4.4.  Free Memory
     75  *
     76  *    The following function frees the dynamic memory that was allocated by
     77  *    if_nameindex().
     78  *
     79  *        #include <net/if.h>
     80  *
     81  *        void  if_freenameindex(struct if_nameindex *ptr);
     82  *
     83  *    The argument to this function must be a pointer that was returned by
     84  *    if_nameindex().
     85  */
     86 
     87 struct if_nameindex *
     88 if_nameindex(void)
     89 {
     90 	struct ifaddrs *ifaddrs, *ifa;
     91 	size_t nbytes, ni;
     92 	struct if_nameindex *ifni, *ifni2;
     93 	char *cp;
     94 
     95 	if (getifaddrs(&ifaddrs) < 0)
     96 		return(NULL);
     97 
     98 	/*
     99 	 * First, find out how many interfaces there are, and how
    100 	 * much space we need for the string names.
    101 	 */
    102 	ni = 0;
    103 	nbytes = 0;
    104 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
    105 		if (ifa->ifa_addr &&
    106 		    ifa->ifa_addr->sa_family == AF_LINK) {
    107 			nbytes += strlen(ifa->ifa_name) + 1;
    108 			ni++;
    109 		}
    110 	}
    111 
    112 	/*
    113 	 * Next, allocate a chunk of memory, use the first part
    114 	 * for the array of structures, and the last part for
    115 	 * the strings.
    116 	 */
    117 	cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
    118 	ifni = (struct if_nameindex *)(void *)cp;
    119 	if (ifni == NULL)
    120 		goto out;
    121 	cp += (ni + 1) * sizeof(struct if_nameindex);
    122 
    123 	/*
    124 	 * Now just loop through the list of interfaces again,
    125 	 * filling in the if_nameindex array and making copies
    126 	 * of all the strings.
    127 	 */
    128 	ifni2 = ifni;
    129 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
    130 		if (ifa->ifa_addr &&
    131 		    ifa->ifa_addr->sa_family == AF_LINK) {
    132 			ifni2->if_index =
    133 			    ((struct sockaddr_dl*)
    134 			    (void *)ifa->ifa_addr)->sdl_index;
    135 			ifni2->if_name = cp;
    136 			strcpy(cp, ifa->ifa_name);
    137 			ifni2++;
    138 			cp += strlen(cp) + 1;
    139 		}
    140 	}
    141 	/*
    142 	 * Finally, don't forget to terminate the array.
    143 	 */
    144 	ifni2->if_index = 0;
    145 	ifni2->if_name = NULL;
    146 out:
    147 	freeifaddrs(ifaddrs);
    148 	return(ifni);
    149 }
    150 
    151 void
    152 if_freenameindex(struct if_nameindex *ptr)
    153 {
    154 	free(ptr);
    155 }
    156