hush/networking/arping.c

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/* vi: set sw=4 ts=4: */
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/*
* arping.c - Ping hosts by ARP requests/replies
*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*
* Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
* Busybox port: Nick Fedchik <nick@fedchik.org.ua>
*/
#include <sys/ioctl.h>
#include <signal.h>
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#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netpacket/packet.h>
#include "busybox.h"
static struct in_addr src;
static struct in_addr dst;
static struct sockaddr_ll me;
static struct sockaddr_ll he;
static struct timeval last;
enum cfg_e {
dad = 1,
unsolicited = 2,
advert = 4,
quiet = 8,
quit_on_reply = 16,
broadcast_only = 32,
unicasting = 64
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};
static int cfg;
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static int s;
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static unsigned count = UINT_MAX;
static unsigned timeout;
static int sent;
static int brd_sent;
static int received;
static int brd_recv;
static int req_recv;
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#define MS_TDIFF(tv1,tv2) ( ((tv1).tv_sec-(tv2).tv_sec)*1000 + \
((tv1).tv_usec-(tv2).tv_usec)/1000 )
static int send_pack(int sock, struct in_addr *src_addr,
struct in_addr *dst_addr, struct sockaddr_ll *ME,
struct sockaddr_ll *HE)
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{
int err;
struct timeval now;
RESERVE_CONFIG_UBUFFER(buf, 256);
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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 = cfg & advert ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
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memcpy(p, &ME->sll_addr, ah->ar_hln);
p += ME->sll_halen;
memcpy(p, src_addr, 4);
p += 4;
if (cfg & advert)
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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 (!(cfg & unicasting))
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brd_sent++;
}
RELEASE_CONFIG_BUFFER(buf);
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return err;
}
static void finish(void)
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{
if (!(cfg & quiet)) {
printf("Sent %d probe(s) (%d broadcast(s))\n"
"Received %d repl%s"
" (%d request(s), %d broadcast(s))\n",
sent, brd_sent,
received, (received == 1) ? "ies" : "y",
req_recv, brd_recv);
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}
if (cfg & dad)
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exit(!!received);
if (cfg & unsolicited)
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exit(0);
exit(!received);
}
static void catcher(void)
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{
struct timeval tv;
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static struct timeval start;
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gettimeofday(&tv, NULL);
if (start.tv_sec == 0)
start = tv;
if (count-- == 0
|| (timeout && MS_TDIFF(tv, start) > timeout * 1000 + 500))
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finish();
if (last.tv_sec == 0 || MS_TDIFF(tv, last) > 500) {
send_pack(s, &src, &dst, &me, &he);
if (count == 0 && (cfg & unsolicited))
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finish();
}
alarm(1);
}
static int recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
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{
struct arphdr *ah = (struct arphdr *) buf;
unsigned char *p = (unsigned char *) (ah + 1);
struct in_addr src_ip, dst_ip;
/* Filter out wild packets */
if (FROM->sll_pkttype != PACKET_HOST
&& FROM->sll_pkttype != PACKET_BROADCAST
&& FROM->sll_pkttype != PACKET_MULTICAST)
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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)))
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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 (!(cfg & dad)) {
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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 (!(cfg & quiet)) {
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int s_printed = 0;
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struct timeval tv;
gettimeofday(&tv, NULL);
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printf("%scast re%s from %s [%s]",
FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
inet_ntoa(src_ip),
ether_ntoa((struct ether_addr *) p));
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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));
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}
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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 (cfg & quit_on_reply)
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finish();
if (!(cfg & broadcast_only)) {
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memcpy(he.sll_addr, p, me.sll_halen);
cfg |= unicasting;
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}
return 1;
}
int arping_main(int argc, char **argv)
{
char *device = "eth0";
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int ifindex;
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char *source = NULL;
char *target;
s = xsocket(PF_PACKET, SOCK_DGRAM, 0);
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// Drop suid root privileges
xsetuid(getuid());
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{
unsigned opt;
char *_count, *_timeout;
/* Dad also sets quit_on_reply.
* Advert also sets unsolicited.
*/
opt_complementary = "Df:AU";
opt = getopt32(argc, argv, "DUAqfbc:w:i:s:",
&_count, &_timeout, &device, &source);
cfg |= opt & 0x3f; /* set respective flags */
if (opt & 0x40) /* -c: count */
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count = xatou(_count);
if (opt & 0x80) /* -w: timeout */
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timeout = xatoul_range(_timeout, 0, INT_MAX/2000);
//if (opt & 0x100) /* -i: interface */
if (strlen(device) > IF_NAMESIZE) {
bb_error_msg_and_die("interface name '%s' is too long",
device);
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}
//if (opt & 0x200) /* -s: source */
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}
argc -= optind;
argv += optind;
if (argc != 1)
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bb_show_usage();
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target = *argv;
xfunc_error_retval = 2;
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{
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struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, device, IFNAMSIZ - 1);
if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
bb_error_msg_and_die("interface %s not found", device);
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}
ifindex = ifr.ifr_ifindex;
if (ioctl(s, SIOCGIFFLAGS, (char *) &ifr)) {
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bb_error_msg_and_die("SIOCGIFFLAGS");
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}
if (!(ifr.ifr_flags & IFF_UP)) {
bb_error_msg_and_die("interface %s is down", device);
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}
if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
bb_error_msg("interface %s is not ARPable", device);
return (cfg & dad ? 0 : 2);
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}
}
if (!inet_aton(target, &dst)) {
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struct hostent *hp;
hp = gethostbyname2(target, AF_INET);
if (!hp) {
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bb_error_msg_and_die("invalid or unknown target %s", target);
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}
memcpy(&dst, hp->h_addr, 4);
}
if (source && !inet_aton(source, &src)) {
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bb_error_msg_and_die("invalid source address %s", source);
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}
if (!(cfg & dad) && (cfg & unsolicited) && src.s_addr == 0)
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src = dst;
if (!(cfg & dad) || src.s_addr) {
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struct sockaddr_in saddr;
int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
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if (device) {
if (setsockopt(probe_fd, SOL_SOCKET, SO_BINDTODEVICE, device, strlen(device) + 1) == -1)
bb_error_msg("warning: interface %s is ignored", device);
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}
memset(&saddr, 0, sizeof(saddr));
saddr.sin_family = AF_INET;
if (src.s_addr) {
saddr.sin_addr = src;
xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
} else if (!(cfg & dad)) {
static const int on = 1;
socklen_t alen = sizeof(saddr);
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saddr.sin_port = htons(1025);
saddr.sin_addr = dst;
if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, (char *) &on, sizeof(on)) == -1)
bb_perror_msg("warning: setsockopt(SO_DONTROUTE)");
xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1) {
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bb_error_msg_and_die("getsockname");
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}
src = saddr.sin_addr;
}
close(probe_fd);
}
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me.sll_family = AF_PACKET;
me.sll_ifindex = ifindex;
me.sll_protocol = htons(ETH_P_ARP);
xbind(s, (struct sockaddr *) &me, sizeof(me));
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{
socklen_t alen = sizeof(me);
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if (getsockname(s, (struct sockaddr *) &me, &alen) == -1) {
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bb_error_msg_and_die("getsockname");
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}
}
if (me.sll_halen == 0) {
bb_error_msg("interface \"%s\" is not ARPable (no ll address)", device);
return (cfg & dad ? 0 : 2);
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}
he = me;
memset(he.sll_addr, -1, he.sll_halen);
if (!(cfg & quiet)) {
printf("ARPING to %s from %s via %s\n",
inet_ntoa(dst), inet_ntoa(src),
device ? device : "unknown");
}
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if (!src.s_addr && !(cfg & dad)) {
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bb_error_msg_and_die("no src address in the non-DAD mode");
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}
{
struct sigaction sa;
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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;
RESERVE_CONFIG_UBUFFER(packet, 4096);
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struct sockaddr_ll from;
socklen_t alen = sizeof(from);
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int cc;
cc = recvfrom(s, packet, 4096, 0, (struct sockaddr *) &from, &alen);
if (cc < 0) {
bb_perror_msg("recvfrom");
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continue;
}
sigemptyset(&sset);
sigaddset(&sset, SIGALRM);
sigaddset(&sset, SIGINT);
sigprocmask(SIG_BLOCK, &sset, &osset);
recv_pack(packet, cc, &from);
sigprocmask(SIG_SETMASK, &osset, NULL);
RELEASE_CONFIG_BUFFER(packet);
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}
}