text: /*
   * 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 <sys/param.h>
  #include <sys/socket.h>
  #include <linux/sockios.h>
  #include <sys/file.h>
  #include <sys/time.h>
  #include <sys/signal.h>
  #include <sys/ioctl.h>
  #include <net/if.h>
  #include <linux/if_packet.h>
  #include <linux/if_ether.h>
  #include <net/if_arp.h>
  #include <sys/uio.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 <sysfs/libsysfs.h>
  struct sysfs_devattr_values;
  #endif
  
  #ifndef WITHOUT_IFADDRS
  #include <ifaddrs.h>
  #endif
  
  #ifdef USE_IDN
  #include <idna.h>
  #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 timeval 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 timeval 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;
  
  	gettimeofday(&now, NULL);
  	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);
  }
  
  void catcher(void)
  {
  	struct timeval tv, tv_s, tv_o;
  
  	gettimeofday(&tv, NULL);
  
  	if (start.tv_sec==0)
  		start = tv;
  
  	timersub(&tv, &start, &tv_s);
  	tv_o.tv_sec = timeout;
  	tv_o.tv_usec = 500 * 1000;
  
  	if (count-- == 0 || (timeout && timercmp(&tv_s, &tv_o, >)))
  		finish();
  
  	timersub(&tv, &last, &tv_s);
  	tv_o.tv_sec = 0;
  
  	if (last.tv_sec==0 || timercmp(&tv_s, &tv_o, >)) {
  		send_pack(s, src, dst,
  			  (struct sockaddr_ll *)&me, (struct sockaddr_ll *)&he);
  		if (count == 0 && unsolicited)
  			finish();
  	}
  	alarm(1);
  }
  
  void print_hex(unsigned char *p, int len)
  {
  	int i;
  	for (i=0; i<len; i++) {
  		printf("%02X", p[i]);
  		if (i != len-1)
  			printf(":");
  	}
  }
  
  int recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
  {
  	struct timeval tv;
  	struct arphdr *ah = (struct arphdr*)buf;
  	unsigned char *p = (unsigned char *)(ah+1);
  	struct in_addr src_ip, dst_ip;
  
  	gettimeofday(&tv, NULL);
  
  	/* 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 = (tv.tv_sec-last.tv_sec) * 1000000 +
  				tv.tv_usec-last.tv_usec;
  			long msecs = (usecs+500)/1000;
  			usecs -= msecs*1000 - 500;
  			printf(" %ld.%03ldms\n", msecs, usecs);
  		} else {
  			printf(" UNSOLICITED?\n");
  		}
  		fflush(stdout);
  	}
  	received++;
  	if (FROM->sll_pkttype != PACKET_HOST)
  		brd_recv++;
  	if (ah->ar_op == htons(ARPOP_REQUEST))
  		req_recv++;
  	if (quit_on_reply)
  		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,
  #if 0
  	SYSFS_DEVATTR_TYPE,
  	SYSFS_DEVATTR_ADDRESS,
  #endif
  	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,
  	},
  #if 0
  	[SYSFS_DEVATTR_TYPE] = {
  		.name		= "type",
  		.handler	= sysfs_devattr_ulong_dec,
  	},
  	[SYSFS_DEVATTR_ADDRESS] = {
  		.name		= "address",
  		.handler	= sysfs_devattr_macaddr,
  		.free		= 1,
  	},
  #endif
  	[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 count = 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 (count++)
  			break;
  	}
  
  	if (count == 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
  	struct sysfs_class *cls_net;
  	struct dlist *dev_list;
  	struct sysfs_class_device *dev;
  	struct sysfs_attribute *dev_attr;
  	struct sysfs_devattr_values sysfs_devattr_values;
  	int count = 0;
  
  	if (!device.sysfs) {
  		device.sysfs = malloc(sizeof(*device.sysfs));
  		sysfs_devattr_values_init(device.sysfs, 0);
  	}
  
  	cls_net = sysfs_open_class("net");
  	if (!cls_net) {
  		perror("sysfs_open_class");
  		return -1;
  	}
  
  	dev_list = sysfs_get_class_devices(cls_net);
  	if (!dev_list) {
  		perror("sysfs_get_class_devices");
  		goto out;
  	}
  
  	sysfs_devattr_values_init(&sysfs_devattr_values, 0);
  
  	dlist_for_each_data(dev_list, dev, struct sysfs_class_device) {
  		int i;
  		int rc = -1;
  
  		if (device.name && strcmp(dev->name, device.name))
  			goto do_next;
  
  		sysfs_devattr_values_init(&sysfs_devattr_values, 1);
  
  		for (i = 0; i < SYSFS_DEVATTR_NUM; i++) {
  
  			dev_attr = sysfs_get_classdev_attr(dev, sysfs_devattrs[i].name);
  			if (!dev_attr) {
  				perror("sysfs_get_classdev_attr");
  				rc = -1;
  				break;
  			}
  			if (sysfs_read_attribute(dev_attr)) {
  				perror("sysfs_read_attribute");
  				rc = -1;
  				break;
  			}
  			rc = sysfs_devattrs[i].handler(dev_attr->value, &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(dev->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 (count++)
  			break;
  
  		continue;
  do_next:
  		sysfs_devattr_values_init(&sysfs_devattr_values, 1);
  	}
  
  	if (count == 1) {
  		device.ifindex = device.sysfs->value[SYSFS_DEVATTR_IFINDEX].ulong;
  		device.name = device.sysfs->ifname;
  	}
  	rc = !device.ifindex;
  out:
  	sysfs_close_class(cls_net);
  #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 count = 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;
  		count++;
  	} 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;
  		}
  
  		ifr_end = (struct ifreq *)(((char *)ifr0) + ifc.ifc_len - sizeof(*ifr0));
  		for (ifr = ifr0; ifr <= ifr_end; ifr++) {
  			if (check_device_by_ioctl(s, &ifrbuf))
  				continue;
  			memcpy(&ifrbuf.ifr_name, ifr->ifr_name, sizeof(ifrbuf.ifr_name));
  			if (count++)
  				break;
  		}
  	}
  
  	close(s);
  
  	if (count == 1) {
  		device.ifindex = ifrbuf.ifr_ifindex;
  		device.name = ifrbuf.ifr_name;
  	}
  	return !device.ifindex;
  out:
  	close(s);
  	return -1;
  }
  
  static int find_device(void)
  {
  	int rc;
  	rc = find_device_by_ifaddrs();
  	if (rc >= 0)
  		goto out;
  	rc = find_device_by_sysfs();
  	if (rc >= 0)
  		goto out;
  	rc = find_device_by_ioctl();
  out:
  	return rc;
  }
  
  /*
   * set_device_broadcast()
   *
   * This fills the device "broadcast address"
   * based on information found by find_device() funcion.
   */
  static int set_device_broadcast_ifaddrs_one(struct device *device, unsigned char *ba, size_t balen, int fatal)
  {
  #ifndef WITHOUT_IFADDRS
  	struct ifaddrs *ifa;
  	struct sockaddr_ll *sll;
  
  	if (!device)
  		return -1;
  
  	ifa = device->ifa;
  	if (!ifa)
  		return -1;
  
  	sll = (struct sockaddr_ll *)ifa->ifa_broadaddr;
  
  	if (sll->sll_halen != balen) {
  		if (fatal) {
  			if (!quiet)
  				printf("Address length does not match...\n");
  			exit(2);
  		}
  		return -1;
  	}
  	memcpy(ba, sll->sll_addr, sll->sll_halen);
  	return 0;
  #else
  	return -1;
  #endif
  }
  int set_device_broadcast_sysfs(struct device *device, unsigned char *ba, size_t balen)
  {
  #ifdef USE_SYSFS
  	struct sysfs_devattr_values *v;
  	if (!device)
  		return -1;
  	v = device->sysfs;
  	if (!v)
  		return -1;
  	if (v->value[SYSFS_DEVATTR_ADDR_LEN].ulong != balen)
  		return -1;
  	memcpy(ba, v->value[SYSFS_DEVATTR_BROADCAST].ptr, balen);
  	return 0;
  #else
  	return -1;
  #endif
  }
  
  static int set_device_broadcast_fallback(struct device *device, unsigned char *ba, size_t balen)
  {
  	if (!quiet)
  		fprintf(stderr, "WARNING: using default broadcast address.\n");
  	memset(ba, -1, balen);
  	return 0;
  }
  
  static void set_device_broadcast(struct device *dev, unsigned char *ba, size_t balen)
  {
  	if (!set_device_broadcast_ifaddrs_one(dev, ba, balen, 0))
  		return;
  	if (!set_device_broadcast_sysfs(dev, ba, balen))
  		return;
  	set_device_broadcast_fallback(dev, ba, balen);
  }
  
  int
  main(int argc, char **argv)
  {
  	int socket_errno;
  	int ch;
  
  	limit_capabilities();
  
  #ifdef USE_IDN
  	setlocale(LC_ALL, "");
  #endif
  
  	enable_capability_raw();
  
  	s = socket(PF_PACKET, SOCK_DGRAM, 0);
  	socket_errno = errno;
  
  	disable_capability_raw();
  
  	while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I:V")) != EOF) {
  		switch(ch) {
  		case 'b':
  			broadcast_only=1;
  			break;
  		case 'D':
  			dad++;
  			quit_on_reply=1;
  			break;
  		case 'U':
  			unsolicited++;
  			break;
  		case 'A':
  			advert++;
  			unsolicited++;
  			break;
  		case 'q':
  			quiet++;
  			break;
  		case 'c':
  			count = atoi(optarg);
  			break;
  		case 'w':
  			timeout = atoi(optarg);
  			break;
  		case 'I':
  			device.name = optarg;
  			break;
  		case 'f':
  			quit_on_reply=1;
  			break;
  		case 's':
  			source = optarg;
  			break;
  		case 'V':
  			printf("arping utility, iputils-%s\n", SNAPSHOT);
  			exit(0);
  		case 'h':
  		case '?':
  		default:
  			usage();
  		}
  	}
  	argc -= optind;
  	argv += optind;
  
  	if (argc != 1)
  		usage();
  
  	target = *argv;
  
  	if (device.name && !*device.name)
  		device.name = NULL;
  
  	if (s < 0) {
  		errno = socket_errno;
  		perror("arping: socket");
  		exit(2);
  	}
  
  	if (find_device() < 0)
  		exit(2);
  
  	if (!device.ifindex) {
  		if (device.name) {
  			fprintf(stderr, "arping: Device %s not available.\n", device.name);
  			exit(2);
  		}
  		fprintf(stderr, "arping: device (option -I) is required.\n");
  		usage();
  	}
  
  	if (inet_aton(target, &dst) != 1) {
  		struct hostent *hp;
  		char *idn = target;
  #ifdef USE_IDN
  		int rc;
  
  		rc = idna_to_ascii_lz(target, &idn, 0);
  
  		if (rc != IDNA_SUCCESS) {
  			fprintf(stderr, "arping: IDN encoding failed: %s\n", idna_strerror(rc));
  			exit(2);
  		}
  #endif
  
  		hp = gethostbyname2(idn, AF_INET);
  		if (!hp) {
  			fprintf(stderr, "arping: unknown host %s\n", target);
  			exit(2);
  		}
  
  #ifdef USE_IDN
  		free(idn);
  #endif
  
  		memcpy(&dst, hp->h_addr, 4);
  	}
  
  	if (source && inet_aton(source, &src) != 1) {
  		fprintf(stderr, "arping: invalid source %s\n", source);
  		exit(2);
  	}
  
  	if (!dad && unsolicited && src.s_addr == 0)
  		src = dst;
  
  	if (!dad || src.s_addr) {
  		struct sockaddr_in saddr;
  		int probe_fd = socket(AF_INET, SOCK_DGRAM, 0);
  
  		if (probe_fd < 0) {
  			perror("socket");
  			exit(2);
  		}
  		if (device.name) {
  			enable_capability_raw();
  
  			if (setsockopt(probe_fd, SOL_SOCKET, SO_BINDTODEVICE, device.name, strlen(device.name)+1) == -1)
  				perror("WARNING: interface is ignored");
  
  			disable_capability_raw();
  		}
  		memset(&saddr, 0, sizeof(saddr));
  		saddr.sin_family = AF_INET;
  		if (src.s_addr) {
  			saddr.sin_addr = src;
  			if (bind(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) {
  				perror("bind");
  				exit(2);
  			}
  		} else if (!dad) {
  			int on = 1;
  			socklen_t alen = sizeof(saddr);
  
  			saddr.sin_port = htons(1025);
  			saddr.sin_addr = dst;
  
  			if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, (char*)&on, sizeof(on)) == -1)
  				perror("WARNING: setsockopt(SO_DONTROUTE)");
  			if (connect(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) {
  				perror("connect");
  				exit(2);
  			}
  			if (getsockname(probe_fd, (struct sockaddr*)&saddr, &alen) == -1) {
  				perror("getsockname");
  				exit(2);
  			}
  			src = saddr.sin_addr;
  		}
  		close(probe_fd);
  	};
  
  	((struct sockaddr_ll *)&me)->sll_family = AF_PACKET;
  	((struct sockaddr_ll *)&me)->sll_ifindex = device.ifindex;
  	((struct sockaddr_ll *)&me)->sll_protocol = htons(ETH_P_ARP);
  	if (bind(s, (struct sockaddr*)&me, sizeof(me)) == -1) {
  		perror("bind");
  		exit(2);
  	}
  
  	if (1) {
  		socklen_t alen = sizeof(me);
  		if (getsockname(s, (struct sockaddr*)&me, &alen) == -1) {
  			perror("getsockname");
  			exit(2);
  		}
  	}
  	if (((struct sockaddr_ll *)&me)->sll_halen == 0) {
  		if (!quiet)
  			printf("Interface \"%s\" is not ARPable (no ll address)\n", device.name);
  		exit(dad?0:2);
  	}
  
  	he = me;
  
  	set_device_broadcast(&device, ((struct sockaddr_ll *)&he)->sll_addr,
  			     ((struct sockaddr_ll *)&he)->sll_halen);
  
  	if (!quiet) {
  		printf("ARPING %s ", inet_ntoa(dst));
  		printf("from %s %s\n",  inet_ntoa(src), device.name ? : "");
  	}
  
  	if (!src.s_addr && !dad) {
  		fprintf(stderr, "arping: no source address in not-DAD mode\n");
  		exit(2);
  	}
  
  	drop_capabilities();
  
  	set_signal(SIGINT, finish);
  	set_signal(SIGALRM, catcher);
  
  	catcher();
  
  	while(1) {
  		sigset_t sset, osset;
  		unsigned char packet[4096];
  		struct sockaddr_storage from;
  		socklen_t alen = sizeof(from);
  		int cc;
  
  		if ((cc = recvfrom(s, packet, sizeof(packet), 0,
  				   (struct sockaddr *)&from, &alen)) < 0) {
  			perror("arping: recvfrom");
  			continue;
  		}
  
  		sigemptyset(&sset);
  		sigaddset(&sset, SIGALRM);
  		sigaddset(&sset, SIGINT);
  		sigprocmask(SIG_BLOCK, &sset, &osset);
  		recv_pack(packet, cc, (struct sockaddr_ll *)&from);
  		sigprocmask(SIG_SETMASK, &osset, NULL);
  	}
  }
  
  
  