busybox/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 <arpa/inet.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netpacket/packet.h>
#include "libbb.h"
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/* We don't expect to see 1000+ seconds delay, unsigned is enough */
#define MONOTONIC_US() ((unsigned)monotonic_us())
enum {
DAD = 1,
UNSOLICITED = 2,
ADVERT = 4,
QUIET = 8,
QUIT_ON_REPLY = 16,
BCAST_ONLY = 32,
UNICASTING = 64
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};
struct globals {
struct in_addr src;
struct in_addr dst;
struct sockaddr_ll me;
struct sockaddr_ll he;
int sock_fd;
int count; // = -1;
unsigned last;
unsigned timeout_us;
unsigned start;
unsigned sent;
unsigned brd_sent;
unsigned received;
unsigned brd_recv;
unsigned req_recv;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define src (G.src )
#define dst (G.dst )
#define me (G.me )
#define he (G.he )
#define sock_fd (G.sock_fd )
#define count (G.count )
#define last (G.last )
#define timeout_us (G.timeout_us)
#define start (G.start )
#define sent (G.sent )
#define brd_sent (G.brd_sent )
#define received (G.received )
#define brd_recv (G.brd_recv )
#define req_recv (G.req_recv )
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#define INIT_G() do { \
count = -1; \
} while (0)
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// If GNUisms are not available...
//static void *mempcpy(void *_dst, const void *_src, int n)
//{
// memcpy(_dst, _src, n);
// return (char*)_dst + n;
//}
static int send_pack(struct in_addr *src_addr,
struct in_addr *dst_addr, struct sockaddr_ll *ME,
struct sockaddr_ll *HE)
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{
int err;
unsigned char buf[256];
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struct arphdr *ah = (struct arphdr *) buf;
unsigned char *p = (unsigned char *) (ah + 1);
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 = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
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p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
p = mempcpy(p, src_addr, 4);
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if (option_mask32 & ADVERT)
p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
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else
p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
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p = mempcpy(p, dst_addr, 4);
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err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
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if (err == p - buf) {
last = MONOTONIC_US();
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sent++;
if (!(option_mask32 & UNICASTING))
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brd_sent++;
}
return err;
}
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static void finish(void) NORETURN;
static void finish(void)
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{
if (!(option_mask32 & QUIET)) {
printf("Sent %u probe(s) (%u broadcast(s))\n"
"Received %u repl%s"
" (%u request(s), %u broadcast(s))\n",
sent, brd_sent,
received, (received == 1) ? "ies" : "y",
req_recv, brd_recv);
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}
if (option_mask32 & DAD)
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exit(!!received);
if (option_mask32 & UNSOLICITED)
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exit(EXIT_SUCCESS);
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exit(!received);
}
static void catcher(void)
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{
unsigned now;
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now = MONOTONIC_US();
if (start == 0)
start = now;
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if (count == 0 || (timeout_us && (now - start) > timeout_us))
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finish();
/* count < 0 means "infinite count" */
if (count > 0)
count--;
if (last == 0 || (now - last) > 500000) {
send_pack(&src, &dst, &me, &he);
if (count == 0 && (option_mask32 & UNSOLICITED))
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finish();
}
alarm(1);
}
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static bool 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;
/* moves below assume in_addr is 4 bytes big, ensure that */
struct BUG_in_addr_must_be_4 {
char BUG_in_addr_must_be_4[
sizeof(struct in_addr) == 4 ? 1 : -1
];
char BUG_s_addr_must_be_4[
sizeof(src_ip.s_addr) == 4 ? 1 : -1
];
};
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/* 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 false;
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/* Only these types are recognized */
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if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
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return false;
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/* 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 false;
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/* Protocol must be IP. */
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if (ah->ar_pro != htons(ETH_P_IP)
|| (ah->ar_pln != 4)
|| (ah->ar_hln != me.sll_halen)
|| (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
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return false;
move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
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if (dst.s_addr != src_ip.s_addr)
return false;
if (!(option_mask32 & DAD)) {
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if ((src.s_addr != dst_ip.s_addr)
|| (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
return false;
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} 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.
*/
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if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
|| (src.s_addr && src.s_addr != dst_ip.s_addr))
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return false;
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}
if (!(option_mask32 & QUIET)) {
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int s_printed = 0;
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) {
unsigned diff = MONOTONIC_US() - last;
printf(" %u.%03ums\n", diff / 1000, diff % 1000);
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} 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 (option_mask32 & QUIT_ON_REPLY)
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finish();
if (!(option_mask32 & BCAST_ONLY)) {
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memcpy(he.sll_addr, p, me.sll_halen);
option_mask32 |= UNICASTING;
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}
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return true;
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}
int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int arping_main(int argc UNUSED_PARAM, char **argv)
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{
const char *device = "eth0";
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char *source = NULL;
char *target;
unsigned char *packet;
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char *err_str;
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INIT_G();
sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
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// Drop suid root privileges
// Need to remove SUID_NEVER from applets.h for this to work
//xsetuid(getuid());
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err_str = xasprintf("interface %s %%s", device);
{
unsigned opt;
char *str_timeout;
/* Dad also sets quit_on_reply.
* Advert also sets unsolicited.
*/
opt_complementary = "=1:Df:AU:c+";
opt = getopt32(argv, "DUAqfbc:w:I:s:",
&count, &str_timeout, &device, &source);
if (opt & 0x80) /* -w: timeout */
timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
//if (opt & 0x200) /* -s: source */
option_mask32 &= 0x3f; /* set respective flags */
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}
target = argv[optind];
xfunc_error_retval = 2;
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{
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struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy_IFNAMSIZ(ifr.ifr_name, device);
/* We use ifr.ifr_name in error msg so that problem
* with truncated name will be visible */
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ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
me.sll_ifindex = ifr.ifr_ifindex;
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xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
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if (!(ifr.ifr_flags & IFF_UP)) {
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bb_error_msg_and_die(err_str, "is down");
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}
if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
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bb_error_msg(err_str, "is not ARPable");
return (option_mask32 & DAD ? 0 : 2);
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}
}
/* if (!inet_aton(target, &dst)) - not needed */ {
len_and_sockaddr *lsa;
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lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
dst = lsa->u.sin.sin_addr;
if (ENABLE_FEATURE_CLEAN_UP)
free(lsa);
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}
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 ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
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src = dst;
if (!(option_mask32 & 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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setsockopt_bindtodevice(probe_fd, device);
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memset(&saddr, 0, sizeof(saddr));
saddr.sin_family = AF_INET;
if (src.s_addr) {
/* Check that this is indeed our IP */
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saddr.sin_addr = src;
xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
} else { /* !(option_mask32 & DAD) case */
/* Find IP address on this iface */
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, &const_int_1, sizeof(const_int_1)) == -1)
bb_perror_msg("setsockopt(SO_DONTROUTE)");
xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
//never happens:
//if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
// bb_perror_msg_and_die("getsockname");
if (saddr.sin_family != AF_INET)
bb_error_msg_and_die("no IP address configured");
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src = saddr.sin_addr;
}
close(probe_fd);
}
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me.sll_family = AF_PACKET;
//me.sll_ifindex = ifindex; - done before
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me.sll_protocol = htons(ETH_P_ARP);
xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
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{
socklen_t alen = sizeof(me);
getsockname(sock_fd, (struct sockaddr *) &me, &alen);
//never happens:
//if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
// bb_perror_msg_and_die("getsockname");
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}
if (me.sll_halen == 0) {
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bb_error_msg(err_str, "is not ARPable (no ll address)");
return (option_mask32 & DAD ? 0 : 2);
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}
he = me;
memset(he.sll_addr, -1, he.sll_halen);
if (!(option_mask32 & QUIET)) {
/* inet_ntoa uses static storage, can't use in same printf */
printf("ARPING to %s", inet_ntoa(dst));
printf(" from %s via %s\n", inet_ntoa(src), device);
}
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signal_SA_RESTART_empty_mask(SIGINT, (void (*)(int))finish);
signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
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catcher();
packet = xmalloc(4096);
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while (1) {
sigset_t sset, osset;
struct sockaddr_ll from;
socklen_t alen = sizeof(from);
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int cc;
cc = recvfrom(sock_fd, 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);
}
}