net_utils.c

/* Copyright (c) 2007-2017 Sergey Matveychuk Yandex, LLC.  All rights
 * reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer. 2.
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution. 4. Neither the name
 * of the company nor the names of its contributors may be used to endorse or
 * promote products derived from this software without specific prior written
 * permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE. */

#include <unistd.h>
#include <string.h>
#include <err.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <sys/ioctl.h>
#include <sys/mac.h>
#include <ifaddrs.h>
#include "dhcprelya.h"

/* Get MAC address from if_name.
 */
int
get_mac(const char *if_name, char *if_mac)
{
	struct ifaddrs *ifaphead, *ifap;
	int found = 0;
	struct sockaddr_dl *sdl = NULL;

	if (getifaddrs(&ifaphead) != 0)
		errx(EX_RES, "getifaddrs: %s", strerror(errno));

	for (ifap = ifaphead; ifap && !found; ifap = ifap->ifa_next)
		if (strcmp(ifap->ifa_name, if_name) == 0) {
			found = 1;
			sdl = (struct sockaddr_dl *)ifap->ifa_addr;
			if (sdl)
				memcpy(if_mac, LLADDR(sdl), sdl->sdl_alen);
		}
	freeifaddrs(ifaphead);
	if (!found) {
		logd(LOG_DEBUG, "can't find mac for interface %s", if_name);
		return 0;
	}
	return 1;
}

/* Get an IP address from ifname. If bound_ip != NULL, it's a preferable.
 */
int
get_ip(const char *iname, ip_addr_t *ip, const ip_addr_t *bound_ip)
{
	struct ifaddrs *ifaddr, *ifa;
	int family;
	struct sockaddr_in *saddr = NULL;

	if (getifaddrs(&ifaddr) == -1)
		errx(1, "getifaddrs: %s", strerror(errno));
	for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
		if (ifa->ifa_addr == NULL)
			continue;
		family = ifa->ifa_addr->sa_family;
		if (family != PF_INET && family != AF_INET)
			continue;
		if (strcmp(ifa->ifa_name, iname) != 0)
			continue;
		saddr = (struct sockaddr_in *)ifa->ifa_addr;
		if (bound_ip && memcmp(&saddr->sin_addr, &bound_ip, sizeof(ip_addr_t)) != 0)
			continue;
		if (ip != NULL)
			memcpy(ip, &saddr->sin_addr, sizeof(ip_addr_t));
		freeifaddrs(ifaddr);
		return 1;
	}
	freeifaddrs(ifaddr);
	return 0;
}