1/*	$KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 itojun Exp $	*/
2
3/*-
4 * SPDX-License-Identifier: BSD-1-Clause
5 *
6 * Copyright (c) 1997, 2000
7 *	Berkeley Software Design, Inc.  All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 *	BSDI Id: if_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
28 */
29
30#include <sys/types.h>
31#include <sys/socket.h>
32#include <net/if_dl.h>
33#include <net/if.h>
34#include <ifaddrs.h>
35#include <stdlib.h>
36#include <string.h>
37
38/*
39 * From RFC 2553:
40 *
41 * 4.3 Return All Interface Names and Indexes
42 *
43 *    The if_nameindex structure holds the information about a single
44 *    interface and is defined as a result of including the <net/if.h>
45 *    header.
46 *
47 *       struct if_nameindex {
48 *         unsigned int   if_index;
49 *         char          *if_name;
50 *       };
51 *
52 *    The final function returns an array of if_nameindex structures, one
53 *    structure per interface.
54 *
55 *       struct if_nameindex  *if_nameindex(void);
56 *
57 *    The end of the array of structures is indicated by a structure with
58 *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
59 *    pointer upon an error, and would set errno to the appropriate value.
60 *
61 *    The memory used for this array of structures along with the interface
62 *    names pointed to by the if_name members is obtained dynamically.
63 *    This memory is freed by the next function.
64 *
65 * 4.4.  Free Memory
66 *
67 *    The following function frees the dynamic memory that was allocated by
68 *    if_nameindex().
69 *
70 *        #include <net/if.h>
71 *
72 *        void  if_freenameindex(struct if_nameindex *ptr);
73 *
74 *    The argument to this function must be a pointer that was returned by
75 *    if_nameindex().
76 */
77
78struct if_nameindex *
79if_nameindex(void)
80{
81	struct ifaddrs *ifaddrs, *ifa;
82	unsigned int ni;
83	int nbytes;
84	struct if_nameindex *ifni, *ifni2;
85	char *cp;
86
87	if (getifaddrs(&ifaddrs) < 0)
88		return(NULL);
89
90	/*
91	 * First, find out how many interfaces there are, and how
92	 * much space we need for the string names.
93	 */
94	ni = 0;
95	nbytes = 0;
96	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
97		if (ifa->ifa_addr &&
98		    ifa->ifa_addr->sa_family == AF_LINK) {
99			nbytes += strlen(ifa->ifa_name) + 1;
100			ni++;
101		}
102	}
103
104	/*
105	 * Next, allocate a chunk of memory, use the first part
106	 * for the array of structures, and the last part for
107	 * the strings.
108	 */
109	cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
110	ifni = (struct if_nameindex *)cp;
111	if (ifni == NULL)
112		goto out;
113	cp += (ni + 1) * sizeof(struct if_nameindex);
114
115	/*
116	 * Now just loop through the list of interfaces again,
117	 * filling in the if_nameindex array and making copies
118	 * of all the strings.
119	 */
120	ifni2 = ifni;
121	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
122		if (ifa->ifa_addr &&
123		    ifa->ifa_addr->sa_family == AF_LINK) {
124			ifni2->if_index =
125			    LLINDEX((struct sockaddr_dl*)ifa->ifa_addr);
126			ifni2->if_name = cp;
127			strcpy(cp, ifa->ifa_name);
128			ifni2++;
129			cp += strlen(cp) + 1;
130		}
131	}
132	/*
133	 * Finally, don't forget to terminate the array.
134	 */
135	ifni2->if_index = 0;
136	ifni2->if_name = NULL;
137out:
138	freeifaddrs(ifaddrs);
139	return(ifni);
140}
141
142void
143if_freenameindex(struct if_nameindex *ptr)
144{
145	free(ptr);
146}
147