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ifconf.c revision 1.1 
      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 
     42 static void
     43 help(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 
     50 static int
     51 get_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 
     72 static void
     73 show_number_of_entries(void)
     74 {
     75 	printf("%d\n", get_number_of_entries());
     76 }
     77 
     78 static void
     79 show_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 
    115 int
    116 main(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