/*

 * arping.c

 *

 *		This program is free software; you can redistribute it and/or

 *		modify it under the terms of the GNU General Public License

 *		as published by the Free Software Foundation; either version

 *		2 of the License, or (at your option) any later version.

 *

 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

 * 		YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

 */

#include <stdlib.h>

#include <time.h>

#include <signal.h>

#include <net/if.h>

#include <linux/if_packet.h>

#include <linux/if_ether.h>

#include <net/if_arp.h>

#include <sys/ioctl.h>

#include <sys/param.h>

#ifdef CAPABILITIES

#include <sys/prctl.h>

#include <sys/capability.h>

#endif

#include <netdb.h>

#include <unistd.h>

#include <stdio.h>

#include <ctype.h>

#include <errno.h>

#include <string.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#ifdef USE_SYSFS

#include <sys/types.h>

#include <dirent.h>

#endif

#ifndef WITHOUT_IFADDRS

#include <ifaddrs.h>

#endif

#ifdef USE_IDN

#include <locale.h>

#endif

#include "SNAPSHOT.h"

static void usage(void) __attribute__((noreturn));

#ifdef DEFAULT_DEVICE

# define DEFAULT_DEVICE_STR	DEFAULT_DEVICE

#else

# define DEFAULT_DEVICE		NULL

#endif

struct device {

	char *name;

	int ifindex;

#ifndef WITHOUT_IFADDRS

	struct ifaddrs *ifa;

#endif

#ifdef USE_SYSFS

	struct sysfs_devattr_values *sysfs;

#endif

};

int quit_on_reply=0;

struct device device = {

	.name = DEFAULT_DEVICE,

};

char *source;

struct in_addr src, dst;

char *target;

int dad, unsolicited, advert;

int quiet;

int count=-1;

int timeout;

int unicasting;

int s;

int broadcast_only;

struct sockaddr_storage me;

struct sockaddr_storage he;

struct timespec start, last;

int sent, brd_sent;

int received, brd_recv, req_recv;

#ifndef CAPABILITIES

static uid_t euid;

#endif

#define MS_TDIFF(tv1,tv2) ( ((tv1).tv_sec-(tv2).tv_sec)*1000 + \

			   ((tv1).tv_usec-(tv2).tv_usec)/1000 )

#define OFFSET_OF(name,ele)	((size_t)(((name *)0)->ele))

static inline socklen_t sll_len(size_t halen)

{

	socklen_t len = OFFSET_OF(struct sockaddr_ll, sll_addr) + halen;

	if (len < sizeof(struct sockaddr_ll))

		len = sizeof(struct sockaddr_ll);

	return len;

}

#define SLL_LEN(hln)		sll_len(hln)

void usage(void)

{

	fprintf(stderr,

		"Usage: arping [-fqbDUAV] [-c count] [-w timeout] [-I device] [-s source] destination\n"

		"  -f : quit on first reply\n"

		"  -q : be quiet\n"

		"  -b : keep broadcasting, don't go unicast\n"

		"  -D : duplicate address detection mode\n"

		"  -U : Unsolicited ARP mode, update your neighbours\n"

		"  -A : ARP answer mode, update your neighbours\n"

		"  -V : print version and exit\n"

		"  -c count : how many packets to send\n"

		"  -w timeout : how long to wait for a reply\n"

		"  -I device : which ethernet device to use"

#ifdef DEFAULT_DEVICE_STR

			" (" DEFAULT_DEVICE_STR ")"

#endif

			"\n"

		"  -s source : source ip address\n"

		"  destination : ask for what ip address\n"

		);

	exit(2);

}

void set_signal(int signo, void (*handler)(void))

{

	struct sigaction sa;

	memset(&sa, 0, sizeof(sa));

	sa.sa_handler = (void (*)(int))handler;

	sa.sa_flags = SA_RESTART;

	sigaction(signo, &sa, NULL);

}

#ifdef CAPABILITIES

static const cap_value_t caps[] = { CAP_NET_RAW, };

static cap_flag_value_t cap_raw = CAP_CLEAR;

#endif

void limit_capabilities(void)

{

#ifdef CAPABILITIES

	cap_t cap_p;

	cap_p = cap_get_proc();

	if (!cap_p) {

		perror("arping: cap_get_proc");

		exit(-1);

	}

	cap_get_flag(cap_p, CAP_NET_RAW, CAP_PERMITTED, &cap_raw);

	if (cap_raw != CAP_CLEAR) {

		if (cap_clear(cap_p) < 0) {

			perror("arping: cap_clear");

			exit(-1);

		}

		cap_set_flag(cap_p, CAP_PERMITTED, 1, caps, CAP_SET);

		if (cap_set_proc(cap_p) < 0) {

			perror("arping: cap_set_proc");

			if (errno != EPERM)

				exit(-1);

		}

	}

	if (prctl(PR_SET_KEEPCAPS, 1) < 0) {

		perror("arping: prctl");

		exit(-1);

	}

	if (setuid(getuid()) < 0) {

		perror("arping: setuid");

		exit(-1);

	}

	if (prctl(PR_SET_KEEPCAPS, 0) < 0) {

		perror("arping: prctl");

		exit(-1);

	}

	cap_free(cap_p);

#else

	euid = geteuid();

#endif

}

int modify_capability_raw(int on)

{

#ifdef CAPABILITIES

	cap_t cap_p;

	if (cap_raw != CAP_SET)

		return on ? -1 : 0;

	cap_p = cap_get_proc();

	if (!cap_p) {

		perror("arping: cap_get_proc");

		return -1;

	}

	cap_set_flag(cap_p, CAP_EFFECTIVE, 1, caps, on ? CAP_SET : CAP_CLEAR);

	if (cap_set_proc(cap_p) < 0) {

		perror("arping: cap_set_proc");

		return -1;

	}

	cap_free(cap_p);

#else

	if (setuid(on ? euid : getuid())) {

		perror("arping: setuid");

		return -1;

	}

#endif

	return 0;

}

static inline int enable_capability_raw(void)

{

	return modify_capability_raw(1);

}

static inline int disable_capability_raw(void)

{

	return modify_capability_raw(0);

}

void drop_capabilities(void)

{

#ifdef CAPABILITIES

	cap_t cap_p = cap_init();

	if (!cap_p) {

		perror("arping: cap_init");

		exit(-1);

	}

	if (cap_set_proc(cap_p) < 0) {

		perror("arping: cap_set_proc");

		exit(-1);

	}

	cap_free(cap_p);

#else

	if (setuid(getuid()) < 0) {

		perror("arping: setuid");

		exit(-1);

	}

#endif

}

int send_pack(int s, struct in_addr src, struct in_addr dst,

	      struct sockaddr_ll *ME, struct sockaddr_ll *HE)

{

	int err;

	struct timespec now;

	unsigned char buf[256];

	struct arphdr *ah = (struct arphdr*)buf;

	unsigned char *p = (unsigned char *)(ah+1);

	ah->ar_hrd = htons(ME->sll_hatype);

	if (ah->ar_hrd == htons(ARPHRD_FDDI))

		ah->ar_hrd = htons(ARPHRD_ETHER);

	ah->ar_pro = htons(ETH_P_IP);

	ah->ar_hln = ME->sll_halen;

	ah->ar_pln = 4;

	ah->ar_op  = advert ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);

	memcpy(p, &ME->sll_addr, ah->ar_hln);

	p+=ME->sll_halen;

	memcpy(p, &src, 4);

	p+=4;

	if (advert)

		memcpy(p, &ME->sll_addr, ah->ar_hln);

	else

		memcpy(p, &HE->sll_addr, ah->ar_hln);

	p+=ah->ar_hln;

	memcpy(p, &dst, 4);

	p+=4;

	clock_gettime(CLOCK_MONOTONIC, &now;;

	err = sendto(s, buf, p-buf, 0, (struct sockaddr*)HE, SLL_LEN(ah->ar_hln));

	if (err == p-buf) {

		last = now;

		sent++;

		if (!unicasting)

			brd_sent++;

	}

	return err;

}

void finish(void)

{

	if (!quiet) {

		printf("Sent %d probes (%d broadcast(s))\n", sent, brd_sent);

		printf("Received %d response(s)", received);

		if (brd_recv || req_recv) {

			printf(" (");

			if (req_recv)

				printf("%d request(s)", req_recv);

			if (brd_recv)

				printf("%s%d broadcast(s)",

				       req_recv ? ", " : "",

				       brd_recv);

			printf(")");

		}

		printf("\n");

		fflush(stdout);

	}

	if (dad)

		exit(!!received);

	if (unsolicited)

		exit(0);

	exit(!received);

}

static void timespec_sub(struct timespec *a, struct timespec *b,

			 struct timespec *res)

{

	res->tv_sec = a->tv_sec - b->tv_sec;

	res->tv_nsec = a->tv_nsec - b->tv_nsec;

	if (a->tv_nsec < b->tv_nsec) {

		res->tv_sec--;

		res->tv_nsec += 1000000000;

	}

}

static int timespec_later(struct timespec *a, struct timespec *b)

{

	return (a->tv_sec > b->tv_sec) ||

		((a->tv_sec == b->tv_sec) && (a->tv_nsec > b->tv_nsec));

}

void catcher(void)

{

	struct timespec ts, ts_s, ts_o;

	clock_gettime(CLOCK_MONOTONIC, &ts);

	if (start.tv_sec==0)

		start = ts;

	timespec_sub(&ts, &start, &ts_s);

	ts_o.tv_sec = timeout;

	ts_o.tv_nsec = 500 * 1000000;

	if (timeout && timespec_later(&ts_s, &ts_o))

		finish();

	timespec_sub(&ts, &last, &ts_s);

	ts_o.tv_sec = 0;

	if (last.tv_sec==0 || timespec_later(&ts_s, &ts_o)) {

		if (!timeout && (sent == count))

			finish();

		send_pack(s, src, dst,

			  (struct sockaddr_ll *)&me, (struct sockaddr_ll *)&he);

		if ((sent == count) && unsolicited)

			/* We usually wait for an extra iteration

			 * after sending the last request to see if we

			 * get a reply, but we don't need to in

			 * unsolicited mode */

			finish();

	}

	alarm(1);

}

void print_hex(unsigned char *p, int len)

{

	int i;

	for (i=0; i

		printf("%02X", p[i]);

		if (i != len-1)

			printf(":");

	}

}

int recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)

{

	struct timespec ts;

	struct arphdr *ah = (struct arphdr*)buf;

	unsigned char *p = (unsigned char *)(ah+1);

	struct in_addr src_ip, dst_ip;

	clock_gettime(CLOCK_MONOTONIC, &ts);

	/* Filter out wild packets */

	if (FROM->sll_pkttype != PACKET_HOST &&

	    FROM->sll_pkttype != PACKET_BROADCAST &&

	    FROM->sll_pkttype != PACKET_MULTICAST)

		return 0;

	/* Only these types are recognised */

	if (ah->ar_op != htons(ARPOP_REQUEST) &&

	    ah->ar_op != htons(ARPOP_REPLY))

		return 0;

	/* ARPHRD check and this darned FDDI hack here :-( */

	if (ah->ar_hrd != htons(FROM->sll_hatype) &&

	    (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))

		return 0;

	/* Protocol must be IP. */

	if (ah->ar_pro != htons(ETH_P_IP))

		return 0;

	if (ah->ar_pln != 4)

		return 0;

	if (ah->ar_hln != ((struct sockaddr_ll *)&me)->sll_halen)

		return 0;

	if (len < sizeof(*ah) + 2*(4 + ah->ar_hln))

		return 0;

	memcpy(&src_ip, p+ah->ar_hln, 4);

	memcpy(&dst_ip, p+ah->ar_hln+4+ah->ar_hln, 4);

	if (!dad) {

		if (src_ip.s_addr != dst.s_addr)

			return 0;

		if (src.s_addr != dst_ip.s_addr)

			return 0;

		if (memcmp(p+ah->ar_hln+4, ((struct sockaddr_ll *)&me)->sll_addr, ah->ar_hln))

			return 0;

	} else {

		/* DAD packet was:

		   src_ip = 0 (or some src)

		   src_hw = ME

		   dst_ip = tested address

		   dst_hw = <unspec>

		   We fail, if receive request/reply with:

		   src_ip = tested_address

		   src_hw != ME

		   if src_ip in request was not zero, check

		   also that it matches to dst_ip, otherwise

		   dst_ip/dst_hw do not matter.

		 */

		if (src_ip.s_addr != dst.s_addr)

			return 0;

		if (memcmp(p, ((struct sockaddr_ll *)&me)->sll_addr, ((struct sockaddr_ll *)&me)->sll_halen) == 0)

			return 0;

		if (src.s_addr && src.s_addr != dst_ip.s_addr)

			return 0;

	}

	if (!quiet) {

		int s_printed = 0;

		printf("%s ", FROM->sll_pkttype==PACKET_HOST ? "Unicast" : "Broadcast");

		printf("%s from ", ah->ar_op == htons(ARPOP_REPLY) ? "reply" : "request");

		printf("%s [", inet_ntoa(src_ip));

		print_hex(p, ah->ar_hln);

		printf("] ");

		if (dst_ip.s_addr != src.s_addr) {

			printf("for %s ", inet_ntoa(dst_ip));

			s_printed = 1;

		}

		if (memcmp(p+ah->ar_hln+4, ((struct sockaddr_ll *)&me)->sll_addr, ah->ar_hln)) {

			if (!s_printed)

				printf("for ");

			printf("[");

			print_hex(p+ah->ar_hln+4, ah->ar_hln);

			printf("]");

		}

		if (last.tv_sec) {

			long usecs = (ts.tv_sec-last.tv_sec) * 1000000 +

				(ts.tv_nsec-last.tv_nsec+500) / 1000;

			long msecs = (usecs+500)/1000;

			usecs -= msecs*1000 - 500;

			printf(" %ld.%03ldms\n", msecs, usecs);

		} else {

			printf(" UNSOLICITED?\n");

		}

		fflush(stdout);

	}

	received++;

	if (timeout && (received == count))

		finish();

	if (FROM->sll_pkttype != PACKET_HOST)

		brd_recv++;

	if (ah->ar_op == htons(ARPOP_REQUEST))

		req_recv++;

	if (quit_on_reply || (count == 0 && received == sent))

		finish();

	if(!broadcast_only) {

		memcpy(((struct sockaddr_ll *)&he)->sll_addr, p, ((struct sockaddr_ll *)&me)->sll_halen);

		unicasting=1;

	}

	return 1;

}

#ifdef USE_SYSFS

union sysfs_devattr_value {

	unsigned long	ulong;

	void		*ptr;

};

enum {

	SYSFS_DEVATTR_IFINDEX,

	SYSFS_DEVATTR_FLAGS,

	SYSFS_DEVATTR_ADDR_LEN,

	SYSFS_DEVATTR_BROADCAST,

	SYSFS_DEVATTR_NUM

};

struct sysfs_devattr_values

{

	char *ifname;

	union sysfs_devattr_value	value[SYSFS_DEVATTR_NUM];

};

static int sysfs_devattr_ulong_dec(char *ptr, struct sysfs_devattr_values *v, unsigned idx);

static int sysfs_devattr_ulong_hex(char *ptr, struct sysfs_devattr_values *v, unsigned idx);

static int sysfs_devattr_macaddr(char *ptr, struct sysfs_devattr_values *v, unsigned idx);

struct sysfs_devattrs {

	const char *name;

	int (*handler)(char *ptr, struct sysfs_devattr_values *v, unsigned int idx);

	int free;

} sysfs_devattrs[SYSFS_DEVATTR_NUM] = {

	[SYSFS_DEVATTR_IFINDEX] = {

		.name		= "ifindex",

		.handler	= sysfs_devattr_ulong_dec,

	},

	[SYSFS_DEVATTR_ADDR_LEN] = {

		.name		= "addr_len",

		.handler	= sysfs_devattr_ulong_dec,

	},

	[SYSFS_DEVATTR_FLAGS] = {

		.name		= "flags",

		.handler	= sysfs_devattr_ulong_hex,

	},

	[SYSFS_DEVATTR_BROADCAST] = {

		.name		= "broadcast",

		.handler	= sysfs_devattr_macaddr,

		.free		= 1,

	},

};

#endif

/*

 * find_device()

 *

 * This function checks 1) if the device (if given) is okay for ARP,

 * or 2) find fist appropriate device on the system.

 *

 * Return value:

 *	>0	: Succeeded, and appropriate device not found.

 *		  device.ifindex remains 0.

 *	0	: Succeeded, and approptiate device found.

 *		  device.ifindex is set.

 *	<0	: Failed.  Support not found, or other

 *		: system error.  Try other method.

 *

 * If an appropriate device found, it is recorded inside the

 * "device" variable for later reference.

 *

 * We have several implementations for this.

 *	by_ifaddrs():	requires getifaddr() in glibc, and rtnetlink in

 *			kernel. default and recommended for recent systems.

 *	by_sysfs():	requires libsysfs , and sysfs in kernel.

 *	by_ioctl():	unable to list devices without ipv4 address; this

 *			means, you need to supply the device name for

 *			DAD purpose.

 */

/* Common check for ifa->ifa_flags */

static int check_ifflags(unsigned int ifflags, int fatal)

{

	if (!(ifflags & IFF_UP)) {

		if (fatal) {

			if (!quiet)

				printf("Interface \"%s\" is down\n", device.name);

			exit(2);

		}

		return -1;

	}

	if (ifflags & (IFF_NOARP | IFF_LOOPBACK)) {

		if (fatal) {

			if (!quiet)

				printf("Interface \"%s\" is not ARPable\n", device.name);

			exit(dad ? 0 : 2);

		}

		return -1;

	}

	return 0;

}

static int find_device_by_ifaddrs(void)

{

#ifndef WITHOUT_IFADDRS

	int rc;

	struct ifaddrs *ifa0, *ifa;

	int n = 0;

	rc = getifaddrs(&ifa0);

	if (rc) {

		perror("getifaddrs");

		return -1;

	}

	for (ifa = ifa0; ifa; ifa = ifa->ifa_next) {

		if (!ifa->ifa_addr)

			continue;

		if (ifa->ifa_addr->sa_family != AF_PACKET)

			continue;

		if (device.name && ifa->ifa_name && strcmp(ifa->ifa_name, device.name))

			continue;

		if (check_ifflags(ifa->ifa_flags, device.name != NULL) < 0)

			continue;

		if (!((struct sockaddr_ll *)ifa->ifa_addr)->sll_halen)

			continue;

		if (!ifa->ifa_broadaddr)

			continue;

		device.ifa = ifa;

		if (n++)

			break;

	}

	if (n == 1 && device.ifa) {

		device.ifindex = if_nametoindex(device.ifa->ifa_name);

		if (!device.ifindex) {

			perror("arping: if_nametoindex");

			freeifaddrs(ifa0);

			return -1;

		}

		device.name  = device.ifa->ifa_name;

		return 0;

	}

	return 1;

#else

	return -1;

#endif

}

#ifdef USE_SYSFS

static void sysfs_devattr_values_init(struct sysfs_devattr_values *v, int do_free)

{

	int i;

	if (do_free) {

		free(v->ifname);

		for (i = 0; i < SYSFS_DEVATTR_NUM; i++) {

			if (sysfs_devattrs[i].free)

				free(v->value[i].ptr);

		}

	}

	memset(v, 0, sizeof(*v));

}

static int sysfs_devattr_ulong(char *ptr, struct sysfs_devattr_values *v, unsigned int idx,

				     unsigned int base)

{

	unsigned long *p;

	char *ep;

	if (!ptr || !v)

		return -1;

	p = &v->value[idx].ulong;

	errno = 0;

	*p = strtoul(ptr, &ep, base);

	if ((*ptr && isspace(*ptr & 0xff)) || errno || (*ep != '\0' && *ep != '\n'))

		goto out;

	return 0;

out:

	return -1;

}

static int sysfs_devattr_ulong_dec(char *ptr, struct sysfs_devattr_values *v, unsigned int idx)

{

	int rc = sysfs_devattr_ulong(ptr, v, idx, 10);

	return rc;

}

static int sysfs_devattr_ulong_hex(char *ptr, struct sysfs_devattr_values *v, unsigned int idx)

{

	int rc = sysfs_devattr_ulong(ptr, v, idx, 16);

	return rc;

}

static int sysfs_devattr_macaddr(char *ptr, struct sysfs_devattr_values *v, unsigned int idx)

{

	unsigned char *m;

	int i;

	unsigned int addrlen;

	if (!ptr || !v)

		return -1;

	addrlen = v->value[SYSFS_DEVATTR_ADDR_LEN].ulong;

	m = malloc(addrlen);

	for (i = 0; i < addrlen; i++) {

		if (i && *(ptr + i * 3 - 1) != ':')

			goto out;

		if (sscanf(ptr + i * 3, "%02hhx", &m[i]) != 1)

			goto out;

	}

	v->value[idx].ptr = m;

	return 0;

out:

	free(m);

	return -1;

}

#endif

int find_device_by_sysfs(void)

{

	int rc = -1;

#ifdef USE_SYSFS

	DIR *dir;

	struct dirent *dirp;

	struct sysfs_devattr_values sysfs_devattr_values;

	int n = 0;

	if (!device.sysfs) {

		device.sysfs = malloc(sizeof(*device.sysfs));

		sysfs_devattr_values_init(device.sysfs, 0);

	}

	dir = opendir("/sys/class/net");

	sysfs_devattr_values_init(&sysfs_devattr_values, 0);

	while ((dirp = readdir(dir)) != NULL) {

		int i;

		int rc = -1;

		if (!strcmp(dirp->d_name, ".") || !strcmp(dirp->d_name, ".."))

			continue;

		if (device.name && strcmp(dirp->d_name, device.name))

			goto do_next;

		sysfs_devattr_values_init(&sysfs_devattr_values, 1);

		for (i = 0; i < SYSFS_DEVATTR_NUM; i++) {

			char path[PATH_MAX];

			char str[256];

			FILE *f;

			sprintf(path, "/sys/class/net/%s/%s", dirp->d_name, sysfs_devattrs[i].name);

			f = fopen(path, "r");

			if (!f)

				continue;

			if (fscanf(f, "%255s", str) != 1)

				str[0] = '\0';

			fclose(f);

			rc = sysfs_devattrs[i].handler(str, &sysfs_devattr_values, i);

			if (rc < 0)

				break;

		}

		if (rc < 0)

			goto do_next;

		if (check_ifflags(sysfs_devattr_values.value[SYSFS_DEVATTR_FLAGS].ulong,

				  device.name != NULL) < 0)

			goto do_next;

		if (!sysfs_devattr_values.value[SYSFS_DEVATTR_ADDR_LEN].ulong)

			goto do_next;

		if (device.sysfs->value[SYSFS_DEVATTR_IFINDEX].ulong) {

			if (device.sysfs->value[SYSFS_DEVATTR_FLAGS].ulong & IFF_RUNNING)

				goto do_next;

		}

		sysfs_devattr_values.ifname = strdup(dirp->d_name);

		if (!sysfs_devattr_values.ifname) {

			perror("malloc");

			goto out;

		}

		sysfs_devattr_values_init(device.sysfs, 1);

		memcpy(device.sysfs, &sysfs_devattr_values, sizeof(*device.sysfs));

		sysfs_devattr_values_init(&sysfs_devattr_values, 0);

		if (n++)

			break;

		continue;

do_next:

		sysfs_devattr_values_init(&sysfs_devattr_values, 1);

	}

	if (n == 1) {

		device.ifindex = device.sysfs->value[SYSFS_DEVATTR_IFINDEX].ulong;

		device.name = device.sysfs->ifname;

	}

	rc = !device.ifindex;

out:

	closedir(dir);

#endif

	return rc;

}

static int check_device_by_ioctl(int s, struct ifreq *ifr)

{

	if (ioctl(s, SIOCGIFFLAGS, ifr) < 0) {

		perror("ioctl(SIOCGIFINDEX");

		return -1;

	}

	if (check_ifflags(ifr->ifr_flags, device.name != NULL) < 0)

		return 1;

	if (ioctl(s, SIOCGIFINDEX, ifr) < 0) {

		perror("ioctl(SIOCGIFINDEX");

		return -1;

	}

	return 0;

}

static int find_device_by_ioctl(void)

{

	int s;

	struct ifreq *ifr0, *ifr, *ifr_end;

	size_t ifrsize = sizeof(*ifr);

	struct ifconf ifc;

	static struct ifreq ifrbuf;

	int n = 0;

	s = socket(AF_INET, SOCK_DGRAM, 0);

	if (s < 0) {

		perror("socket");

		return -1;

	}

	memset(&ifrbuf, 0, sizeof(ifrbuf));

	if (device.name) {

		strncpy(ifrbuf.ifr_name, device.name, sizeof(ifrbuf.ifr_name) - 1);

		if (check_device_by_ioctl(s, &ifrbuf))

			goto out;

		n++;

	} else {

		do {

			int rc;

			ifr0 = malloc(ifrsize);

			if (!ifr0) {

				perror("malloc");

				goto out;

			}

			ifc.ifc_buf = (char *)ifr0;

			ifc.ifc_len = ifrsize;

			rc = ioctl(s, SIOCGIFCONF, &ifc;;

			if (rc < 0) {

				perror("ioctl(SIOCFIFCONF");

				goto out;

			}

			if (ifc.ifc_len + sizeof(*ifr0) + sizeof(struct sockaddr_storage) - sizeof(struct sockaddr) <= ifrsize)

				break;

			ifrsize *= 2;

			free(ifr0);

			ifr0 = NULL;

		} while(ifrsize < INT_MAX / 2);

		if (!ifr0) {

			fprintf(stderr, "arping: too many interfaces!?\n");

			goto out;