ifconf.c revision 313498 
1/*	$NetBSD: ifconf.c,v 1.1 2014/12/08 04:23:03 ozaki-r Exp $	*/
2/*
3 * Copyright (c) 2014 The NetBSD Foundation, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__RCSID("$NetBSD: ifconf.c,v 1.1 2014/12/08 04:23:03 ozaki-r Exp $");
29#include <sys/types.h>
30#include <sys/socket.h>
31#include <sys/sockio.h>
32#include <sys/ioctl.h>
33
34#include <net/if.h>
35
36#include <stdio.h>
37#include <err.h>
38#include <stdlib.h>
39#include <unistd.h>
40#include <string.h>
41
42static void
43help(void)
44{
45	fprintf(stderr, "usage:\n\t%s total\n\t%s list [<nifreqs>]\n",
46	    getprogname(), getprogname());
47	exit(EXIT_FAILURE);
48}
49
50static int
51get_number_of_entries(void)
52{
53	int fd, r;
54	struct ifconf ifc;
55
56	fd = socket(AF_INET, SOCK_DGRAM, 0);
57	if (fd == -1)
58		err(EXIT_FAILURE, "socket");
59
60	ifc.ifc_len = 0;
61	ifc.ifc_buf = NULL;
62
63	r = ioctl(fd, SIOCGIFCONF, &ifc);
64	if (r == -1)
65		err(EXIT_FAILURE, "ioctl");
66
67	close(fd);
68
69	return ifc.ifc_len / sizeof(struct ifreq);
70}
71
72static void
73show_number_of_entries(void)
74{
75	printf("%d\n", get_number_of_entries());
76}
77
78static void
79show_interfaces(int nifreqs)
80{
81	int i, fd, r;
82	struct ifconf ifc;
83	struct ifreq *ifreqs;
84
85	if (nifreqs == 0)
86		nifreqs = get_number_of_entries();
87
88	if (nifreqs <= 0)
89		errx(EXIT_FAILURE, "nifreqs=%d", nifreqs);
90
91	ifreqs = malloc(sizeof(struct ifreq) * nifreqs);
92	if (ifreqs == NULL)
93		err(EXIT_FAILURE, "malloc(sizeof(ifreq) * %d)", nifreqs);
94
95	fd = socket(AF_INET, SOCK_DGRAM, 0);
96	if (fd == -1)
97		err(EXIT_FAILURE, "socket");
98
99	ifc.ifc_len = sizeof(struct ifreq) * nifreqs;
100	ifc.ifc_req = ifreqs;
101
102	r = ioctl(fd, SIOCGIFCONF, &ifc);
103	if (r == -1)
104		err(EXIT_FAILURE, "ioctl");
105	close(fd);
106
107	for (i=0; i < (int)(ifc.ifc_len / sizeof(struct ifreq)); i++) {
108		printf("%s: af=%hhu socklen=%hhu\n", ifreqs[i].ifr_name,
109		    ifreqs[i].ifr_addr.sa_family, ifreqs[i].ifr_addr.sa_len);
110	}
111
112	free(ifreqs);
113}
114
115int
116main(int argc, char *argv[])
117{
118	if (argc < 2)
119		help();
120
121	if (strcmp(argv[1], "total") == 0) {
122		show_number_of_entries();
123	} else if (strcmp(argv[1], "list") == 0) {
124		if (argc == 2)
125			show_interfaces(0);
126		else if (argc == 3)
127			show_interfaces(atoi(argv[2]));
128		else
129			help();
130	} else
131		help();
132
133	return EXIT_SUCCESS;
134}
135