busybox/networking/arping.c
Denys Vlasenko b5257a6701 arping: code shrink
function                                             old     new   delta
catcher                                              310     309      -1
arping_main                                         1668    1641     -27

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-02-11 21:16:24 +01:00

439 lines
12 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*
* Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
* Busybox port: Nick Fedchik <nick@fedchik.org.ua>
*/
//config:config ARPING
//config: bool "arping (9.3 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: Ping hosts by ARP packets.
//applet:IF_ARPING(APPLET(arping, BB_DIR_USR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_ARPING) += arping.o
//usage:#define arping_trivial_usage
//usage: "[-fqbDUA] [-c CNT] [-w TIMEOUT] [-I IFACE] [-s SRC_IP] DST_IP"
//usage:#define arping_full_usage "\n\n"
//usage: "Send ARP requests/replies\n"
//usage: "\n -f Quit on first ARP reply"
//usage: "\n -q Quiet"
//usage: "\n -b Keep broadcasting, don't go unicast"
//usage: "\n -D Exit with 1 if DST_IP replies"
//usage: "\n -U Unsolicited ARP mode, update your neighbors"
//usage: "\n -A ARP answer mode, update your neighbors"
//usage: "\n -c N Stop after sending N ARP requests"
//usage: "\n -w TIMEOUT Seconds to wait for ARP reply"
//NB: in iputils-s20160308, iface is mandatory, no default
//usage: "\n -I IFACE Interface to use (default eth0)"
//usage: "\n -s SRC_IP Sender IP address"
//usage: "\n DST_IP Target IP address"
#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netpacket/packet.h>
#include "libbb.h"
#include "common_bufsiz.h"
/* We don't expect to see 1000+ seconds delay, unsigned is enough */
#define MONOTONIC_US() ((unsigned)monotonic_us())
enum {
UNSOLICITED = 1 << 0,
DAD = 1 << 1,
ADVERT = 1 << 2,
QUIET = 1 << 3,
QUIT_ON_REPLY = 1 << 4,
BCAST_ONLY = 1 << 5,
UNICASTING = 1 << 6,
TIMEOUT = 1 << 7,
};
#define GETOPT32(str_timeout, device, source) \
getopt32(argv, "^" \
"UDAqfbc:+w:I:s:" \
/* DAD also sets quit_on_reply, */ \
/* advert also sets unsolicited: */ \
"\0" "=1:Df:AU", \
&count, &str_timeout, &device, &source \
);
struct globals {
struct in_addr src;
struct in_addr dst;
struct sockaddr_ll me;
struct sockaddr_ll he;
int count; // = -1;
unsigned last;
unsigned timeout_us;
unsigned start;
unsigned sent;
unsigned brd_sent;
unsigned received;
unsigned brd_recv;
unsigned req_recv;
/* should be in main(), but are here to reduce stack use: */
struct ifreq ifr;
struct sockaddr_in probe_saddr;
sigset_t sset;
unsigned char packet[4096];
} FIX_ALIASING;
#define src (G.src )
#define dst (G.dst )
#define me (G.me )
#define he (G.he )
#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 )
//#define G (*(struct globals*)bb_common_bufsiz1)
#define G (*ptr_to_globals)
#define INIT_G() do { \
/*setup_common_bufsiz();*/ \
SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
count = -1; \
} while (0)
#define sock_fd 3
static int send_pack(struct in_addr *src_addr,
struct in_addr *dst_addr,
struct sockaddr_ll *ME,
struct sockaddr_ll *HE)
{
int err;
unsigned char buf[256];
struct arphdr *ah = (struct arphdr *) buf;
unsigned char *p;
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);
p = (unsigned char *) (ah + 1);
p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
p = mempcpy(p, src_addr, 4);
if (option_mask32 & ADVERT)
p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
else
p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
p = mempcpy(p, dst_addr, 4);
err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
if (err == p - buf) {
last = MONOTONIC_US();
sent++;
if (!(option_mask32 & UNICASTING))
brd_sent++;
}
return err;
}
static void finish(void) NORETURN;
static void finish(void)
{
if (!(option_mask32 & QUIET)) {
printf("Sent %u probe(s) (%u broadcast(s))\n"
"Received %u response(s)"
" (%u request(s), %u broadcast(s))\n",
sent, brd_sent,
received,
req_recv, brd_recv);
}
if (option_mask32 & DAD)
exit(!!received);
if (option_mask32 & UNSOLICITED)
exit(EXIT_SUCCESS);
exit(!received);
}
static void catcher(void)
{
unsigned now;
now = MONOTONIC_US();
if (start == 0)
start = now;
if (count == 0 || (timeout_us && (now - start) > timeout_us))
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))
finish();
}
alarm(1);
}
static void recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
{
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 */
BUILD_BUG_ON(sizeof(struct in_addr) != 4);
BUILD_BUG_ON(sizeof(src_ip.s_addr) != 4);
/* Filter out wild packets */
if (FROM->sll_pkttype != PACKET_HOST
&& FROM->sll_pkttype != PACKET_BROADCAST
&& FROM->sll_pkttype != PACKET_MULTICAST)
return;
/* Only these types are recognized */
if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
return;
/* 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;
/* Protocol must be IP. */
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)))
) {
return;
}
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);
if (dst.s_addr != src_ip.s_addr)
return;
if (!(option_mask32 & DAD)) {
if ((src.s_addr != dst_ip.s_addr)
|| (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
return;
} 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 ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
|| (src.s_addr && src.s_addr != dst_ip.s_addr))
return;
}
if (!(option_mask32 & QUIET)) {
int s_printed = 0;
//TODO: arping from iputils-s20160308 print upprcase hex in MAC, follow them?
printf("%scast re%s from %s [%02x:%02x:%02x:%02x:%02x:%02x]",
FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
inet_ntoa(src_ip),
p[0], p[1], p[2], p[3], p[4], p[5]
);
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)) {
unsigned char *pp = p + ah->ar_hln + 4;
if (!s_printed)
printf(" for");
printf(" [%02x:%02x:%02x:%02x:%02x:%02x]",
pp[0], pp[1], pp[2], pp[3], pp[4], pp[5]
);
}
if (last) {
unsigned diff = MONOTONIC_US() - last;
printf(" %u.%03ums\n", diff / 1000, diff % 1000);
} else {
puts(" UNSOLICITED?");
}
fflush_all();
}
received++;
if (FROM->sll_pkttype != PACKET_HOST)
brd_recv++;
if (ah->ar_op == htons(ARPOP_REQUEST))
req_recv++;
if (option_mask32 & QUIT_ON_REPLY)
finish();
if (!(option_mask32 & BCAST_ONLY)) {
memcpy(he.sll_addr, p, me.sll_halen);
option_mask32 |= UNICASTING;
}
}
int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int arping_main(int argc UNUSED_PARAM, char **argv)
{
const char *device = "eth0";
char *source = NULL;
char *target;
char *err_str;
INIT_G();
xmove_fd(xsocket(AF_PACKET, SOCK_DGRAM, 0), sock_fd);
// If you ever change BB_SUID_DROP to BB_SUID_REQUIRE,
// drop suid root privileges here:
//xsetuid(getuid());
{
unsigned opt;
char *str_timeout;
opt = GETOPT32(str_timeout, device, source);
if (opt & TIMEOUT)
timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
}
target = argv[optind];
err_str = xasprintf("interface %s %%s", device);
xfunc_error_retval = 2;
/*memset(&G.ifr, 0, sizeof(G.ifr)); - zeroed by INIT_G */
strncpy_IFNAMSIZ(G.ifr.ifr_name, device);
ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &G.ifr, err_str, "not found");
me.sll_ifindex = G.ifr.ifr_ifindex;
xioctl(sock_fd, SIOCGIFFLAGS, (char *) &G.ifr);
if (!(G.ifr.ifr_flags & IFF_UP)) {
bb_error_msg_and_die(err_str, "is down");
}
if (G.ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
bb_error_msg(err_str, "is not ARPable");
BUILD_BUG_ON(DAD != 2);
/* exit 0 if DAD, else exit 2 */
return (~option_mask32 & DAD);
}
/* if (!inet_aton(target, &dst)) - not needed */ {
len_and_sockaddr *lsa;
lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
dst = lsa->u.sin.sin_addr;
if (ENABLE_FEATURE_CLEAN_UP)
free(lsa);
}
if (source && !inet_aton(source, &src)) {
bb_error_msg_and_die("invalid source address %s", source);
}
if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
src = dst;
if (!(option_mask32 & DAD) || src.s_addr) {
/*struct sockaddr_in probe_saddr;*/
int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
setsockopt_bindtodevice(probe_fd, device);
/*memset(&G.probe_saddr, 0, sizeof(G.probe_saddr)); - zeroed by INIT_G */
G.probe_saddr.sin_family = AF_INET;
if (src.s_addr) {
/* Check that this is indeed our IP */
G.probe_saddr.sin_addr = src;
xbind(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
} else { /* !(option_mask32 & DAD) case */
/* Find IP address on this iface */
G.probe_saddr.sin_port = htons(1025);
G.probe_saddr.sin_addr = dst;
if (setsockopt_SOL_SOCKET_1(probe_fd, SO_DONTROUTE) != 0)
bb_perror_msg("setsockopt(%s)", "SO_DONTROUTE");
xconnect(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
bb_getsockname(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
if (G.probe_saddr.sin_family != AF_INET)
bb_error_msg_and_die("no IP address configured");
src = G.probe_saddr.sin_addr;
}
close(probe_fd);
}
me.sll_family = AF_PACKET;
//me.sll_ifindex = ifindex; - done before
me.sll_protocol = htons(ETH_P_ARP);
xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
bb_getsockname(sock_fd, (struct sockaddr *) &me, sizeof(me));
//never happens:
//if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
// bb_perror_msg_and_die("getsockname");
if (me.sll_halen == 0) {
bb_error_msg(err_str, "is not ARPable (no ll address)");
BUILD_BUG_ON(DAD != 2);
/* exit 0 if DAD, else exit 2 */
return (~option_mask32 & DAD);
}
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 %s", inet_ntoa(dst));
printf(" from %s %s\n", inet_ntoa(src), device);
}
/*sigemptyset(&G.sset); - zeroed by INIT_G */
sigaddset(&G.sset, SIGALRM);
sigaddset(&G.sset, SIGINT);
signal_SA_RESTART_empty_mask(SIGINT, (void (*)(int))finish);
signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
/* Send the first packet, arm ALRM */
catcher();
while (1) {
struct sockaddr_ll from;
socklen_t alen = sizeof(from);
int cc;
/* Unblock SIGALRM so that the previously called alarm()
* can prevent recvfrom from blocking forever in case the
* inherited procmask is blocking SIGALRM.
*/
sigprocmask(SIG_UNBLOCK, &G.sset, NULL);
cc = recvfrom(sock_fd, G.packet, sizeof(G.packet), 0, (struct sockaddr *) &from, &alen);
/* Don't allow SIGALRMs while we process the reply */
sigprocmask(SIG_BLOCK, &G.sset, NULL);
if (cc < 0) {
bb_perror_msg("recvfrom");
continue;
}
recv_pack(G.packet, cc, &from);
}
}