arping applet by Nick Fedchik

include/applets.h

@@ -58,6 +58,9 @@
 #ifdef CONFIG_AR
 	APPLET(ar, ar_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
 #endif
+#ifdef CONFIG_ARPING
+	APPLET(arping, arping_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
+#endif
 #ifdef CONFIG_ASH
 	APPLET_NOUSAGE("ash", ash_main, _BB_DIR_BIN, _BB_SUID_NEVER)
 #endif

include/usage.h

@@ -38,6 +38,23 @@
 	"\t-x\t\textract\n" \
 	"\t-v\t\tverbosely list files processed\n"
 
+#define arping_trivial_usage \
+	"[-fqbDUA] [-c count] [-w timeout] [-I device] [-s sender] target\n"
+#define arping_full_usage \
+	"Ping hosts by ARP requests/replies.\n\n" \
+	"Options:\n" \
+	"\t-f\t\tQuit on first ARP reply\n" \
+	"\t-q\t\tBe quiet\n" \
+	"\t-b\t\tKeep broadcasting, don't go unicast\n" \
+	"\t-D\t\tDuplicated address detection mode\n" \
+	"\t-U\t\tUnsolicited ARP mode, update your neighbours\n" \
+	"\t-A\t\tARP answer mode, update your neighbours\n" \
+	"\t-c count\tStop after sending count ARP request packets\n" \
+	"\t-w timeout\tTime to wait for ARP reply, in seconds\n" \
+	"\t-I device\tOutgoing interface name, default is eth0\n" \
+	"\t-s sender\tSet specific sender IP address\n" \
+	"\ttarget\t\tTarget IP address of ARP request\n"
+
 #define	awk_trivial_usage \
 	"[-v var=val][-F sep] { -f progname | 'programtext' } [FILE ...]"
 #define	awk_full_usage \

networking/Config.in

@@ -11,6 +11,12 @@ config CONFIG_FEATURE_IPV6
 	help
 	  Please submit a patch to add help text for this item.
 
+config CONFIG_ARPING
+	bool "arping"
+	default n
+	help
+	  Ping hosts by ARP packets
+
 config CONFIG_FTPGET
 	bool "ftpget"
 	default n

networking/Makefile.in

@@ -23,6 +23,7 @@ NETWORKING_DIR:=$(TOPDIR)networking/
 endif
 
 NETWORKING-y:=
+NETWORKING-$(CONFIG_ARPING)	+= arping.o
 NETWORKING-$(CONFIG_FTPGET)	+= ftpgetput.o
 NETWORKING-$(CONFIG_FTPPUT)	+= ftpgetput.o
 NETWORKING-$(CONFIG_HOSTNAME)	+= hostname.o

networking/arping.c

@@ -0,0 +1,492 @@
+/*
+ * arping.c - Ping hosts by ARP requests/replies
+ *
+ * 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.
+ *
+ * Author:	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
+ * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
+ */
+
+#include <sys/ioctl.h>
+#include <sys/signal.h>
+#include <sys/time.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <netinet/ether.h>
+#include <netpacket/packet.h>
+
+#include "busybox.h"
+
+#define APPLET_NAME "arping"
+
+struct in_addr src;
+struct in_addr dst;
+struct sockaddr_ll me;
+struct sockaddr_ll he;
+struct timeval last;
+int dad;
+int unsolicited;
+int advert;
+int quiet;
+int quit_on_reply = 0;
+int count = -1;
+int timeout;
+int unicasting;
+int s;
+int broadcast_only;
+int sent;
+int brd_sent;
+int received;
+int brd_recv;
+int req_recv;
+
+#define MS_TDIFF(tv1,tv2) ( ((tv1).tv_sec-(tv2).tv_sec)*1000 + \
+			   ((tv1).tv_usec-(tv2).tv_usec)/1000 )
+#if 0
+static 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);
+}
+#endif
+
+static int send_pack(int sock, struct in_addr *src_addr, struct in_addr *dst_addr,
+			  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);
+	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_addr, 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_addr, 4);
+	p += 4;
+
+	gettimeofday(&now, NULL);
+	err = sendto(sock, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
+	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 repl%s", received, (received > 1) ? "ies" : "y");
+		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);
+			putchar(')');
+		}
+		putchar('\n');
+		fflush(stdout);
+	}
+	if (dad)
+		exit(!!received);
+	if (unsolicited)
+		exit(0);
+	exit(!received);
+}
+
+void catcher(void)
+{
+	struct timeval tv;
+	struct timeval start;
+
+	gettimeofday(&tv, NULL);
+
+	if (start.tv_sec == 0)
+		start = tv;
+
+	if (count-- == 0
+		|| (timeout && MS_TDIFF(tv, start) > timeout * 1000 + 500))
+		finish();
+
+	if (last.tv_sec == 0 || MS_TDIFF(tv, last) > 500) {
+		send_pack(s, &src, &dst, &me, &he);
+		if (count == 0 && unsolicited)
+			finish();
+	}
+	alarm(1);
+}
+
+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 != 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, &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, &me.sll_addr, 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));
+		printf("[%s]", ether_ntoa((struct ether_addr *) p));
+		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, me.sll_addr, ah->ar_hln)) {
+			if (!s_printed)
+				printf("for ");
+			printf("[%s]",
+				   ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
+		}
+		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(he.sll_addr, p, me.sll_halen);
+		unicasting = 1;
+	}
+	return 1;
+}
+
+int arping_main(int argc, char **argv)
+{
+	int socket_errno;
+	int ch;
+	uid_t uid = getuid();
+	char *device = "eth0";
+	int ifindex = 0;
+	char *source = NULL;
+	char *target;
+
+	s = socket(PF_PACKET, SOCK_DGRAM, 0);
+	socket_errno = errno;
+
+	setuid(uid);
+
+	while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I")) != 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 = optarg;
+			break;
+		case 'f':
+			quit_on_reply = 1;
+			break;
+		case 's':
+			source = optarg;
+			break;
+		case 'h':
+		case '?':
+		default:
+			show_usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+
+	if (argc != 1)
+		show_usage();
+
+	target = *argv;
+
+	if (device == NULL) {
+		error_msg("-I <interface> is required!");
+		exit(1);
+	}
+
+	if (s < 0) {
+		error_msg("socket");
+		exit(socket_errno);
+	}
+
+	if (1) {
+		struct ifreq ifr;
+
+		memset(&ifr, 0, sizeof(ifr));
+		strncpy(ifr.ifr_name, device, IFNAMSIZ - 1);
+		if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
+			error_msg("unknown interface %s", device);
+			exit(2);
+		}
+		ifindex = ifr.ifr_ifindex;
+
+		if (ioctl(s, SIOCGIFFLAGS, (char *) &ifr)) {
+			error_msg("SIOCGIFFLAGS");
+			exit(2);
+		}
+		if (!(ifr.ifr_flags & IFF_UP)) {
+			error_msg("Interface \"%s\" is down", device);
+			exit(2);
+		}
+		if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
+			error_msg("Interface \"%s\" is not ARPable", device);
+			exit(dad ? 0 : 2);
+		}
+	}
+
+	if (inet_aton(target, &dst) != 1) {
+		struct hostent *hp;
+
+		hp = gethostbyname2(target, AF_INET);
+		if (!hp) {
+			error_msg("invalid or unknown target %s", target);
+			exit(2);
+		}
+		memcpy(&dst, hp->h_addr, 4);
+	}
+
+	if (source && inet_aton(source, &src) != 1) {
+		error_msg("invalid source address %s", 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) {
+			error_msg("socket");
+			exit(2);
+		}
+		if (device) {
+			if (setsockopt
+				(probe_fd, SOL_SOCKET, SO_BINDTODEVICE, device,
+				 strlen(device) + 1) == -1)
+				perror("WARNING: interface is ignored");
+		}
+		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) {
+				error_msg("bind");
+				exit(2);
+			}
+		} else if (!dad) {
+			int on = 1;
+			int 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) {
+				error_msg("connect");
+				exit(2);
+			}
+			if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) ==
+				-1) {
+				error_msg("getsockname");
+				exit(2);
+			}
+			src = saddr.sin_addr;
+		}
+		close(probe_fd);
+	};
+
+	me.sll_family = AF_PACKET;
+	me.sll_ifindex = ifindex;
+	me.sll_protocol = htons(ETH_P_ARP);
+	if (bind(s, (struct sockaddr *) &me, sizeof(me)) == -1) {
+		error_msg("bind");
+		exit(2);
+	}
+
+	if (1) {
+		int alen = sizeof(me);
+
+		if (getsockname(s, (struct sockaddr *) &me, &alen) == -1) {
+			error_msg("getsockname");
+			exit(2);
+		}
+	}
+	if (me.sll_halen == 0) {
+		error_msg("Interface \"%s\" is not ARPable (no ll address)", device);
+		exit(dad ? 0 : 2);
+	}
+	he = me;
+	memset(he.sll_addr, -1, he.sll_halen);
+
+	if (!quiet)
+		printf("ARPING to %s from %s via %s\n", inet_ntoa(dst),
+			   inet_ntoa(src), device ? device : "unknown");
+
+	if (!src.s_addr && !dad) {
+		error_msg("no src address in the non-DAD mode");
+		exit(2);
+	}
+
+	{
+		struct sigaction sa;
+		memset(&sa, 0, sizeof(sa));
+		sa.sa_flags = SA_RESTART;
+
+		sa.sa_handler = (void (*)(int)) finish;
+		sigaction(SIGINT, &sa, NULL);
+
+		sa.sa_handler = (void (*)(int)) catcher;
+		sigaction(SIGALRM, &sa, NULL);
+	}
+
+	catcher();
+
+	while (1) {
+		sigset_t sset, osset;
+		char packet[4096];
+		struct sockaddr_ll from;
+		int alen = sizeof(from);
+		int cc;
+
+		if ((cc = recvfrom(s, packet, sizeof(packet), 0,
+						   (struct sockaddr *) &from, &alen)) < 0) {
+			perror("recvfrom");
+			continue;
+		}
+		sigemptyset(&sset);
+		sigaddset(&sset, SIGALRM);
+		sigaddset(&sset, SIGINT);
+		sigprocmask(SIG_BLOCK, &sset, &osset);
+		recv_pack(packet, cc, &from);
+		sigprocmask(SIG_SETMASK, &osset, NULL);
+	}
+}