1 /* vi: set sw=4 ts=4: */
2 /*
3 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
4 *
5 * Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
6 * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
7 */
8 //config:config ARPING
9 //config: bool "arping (9 kb)"
10 //config: default y
11 //config: help
12 //config: Ping hosts by ARP packets.
13
14 //applet:IF_ARPING(APPLET(arping, BB_DIR_USR_SBIN, BB_SUID_DROP))
15
16 //kbuild:lib-$(CONFIG_ARPING) += arping.o
17
18 //usage:#define arping_trivial_usage
19 //usage: "[-fqbDUA] [-c CNT] [-w TIMEOUT] [-I IFACE] [-s SRC_IP] DST_IP"
20 //usage:#define arping_full_usage "\n\n"
21 //usage: "Send ARP requests/replies\n"
22 //usage: "\n -f Quit on first ARP reply"
23 //usage: "\n -q Quiet"
24 //usage: "\n -b Keep broadcasting, don't go unicast"
25 //usage: "\n -D Exit with 1 if DST_IP replies"
26 //usage: "\n -U Unsolicited ARP mode, update your neighbors"
27 //usage: "\n -A ARP answer mode, update your neighbors"
28 //usage: "\n -c N Stop after sending N ARP requests"
29 //usage: "\n -w TIMEOUT Seconds to wait for ARP reply"
30 //NB: in iputils-s20160308, iface is mandatory, no default
31 //usage: "\n -I IFACE Interface to use (default eth0)"
32 //usage: "\n -s SRC_IP Sender IP address"
33 //usage: "\n DST_IP Target IP address"
34
35 #include <arpa/inet.h>
36 #include <net/if.h>
37 #include <netinet/ether.h>
38 #include <netpacket/packet.h>
39
40 #include "libbb.h"
41 #include "common_bufsiz.h"
42
43 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
44 #define MONOTONIC_US() ((unsigned)monotonic_us())
45
46 enum {
47 UNSOLICITED = 1 << 0,
48 DAD = 1 << 1,
49 ADVERT = 1 << 2,
50 QUIET = 1 << 3,
51 QUIT_ON_REPLY = 1 << 4,
52 BCAST_ONLY = 1 << 5,
53 UNICASTING = 1 << 6,
54 TIMEOUT = 1 << 7,
55 };
56 #define GETOPT32(str_timeout, device, source) \
57 getopt32(argv, "^" \
58 "UDAqfbc:+w:I:s:" \
59 /* DAD also sets quit_on_reply, */ \
60 /* advert also sets unsolicited: */ \
61 "\0" "=1:Df:AU", \
62 &count, &str_timeout, &device, &source \
63 );
64
65 struct globals {
66 struct in_addr src;
67 struct in_addr dst;
68 struct sockaddr_ll me;
69 struct sockaddr_ll he;
70
71 int count; // = -1;
72 unsigned last;
73 unsigned timeout_us;
74 unsigned start;
75
76 unsigned sent;
77 unsigned brd_sent;
78 unsigned received;
79 unsigned brd_recv;
80 unsigned req_recv;
81
82 /* should be in main(), but are here to reduce stack use: */
83 struct ifreq ifr;
84 struct sockaddr_in probe_saddr;
85 sigset_t sset;
86 unsigned char packet[4096];
87 } FIX_ALIASING;
88 #define src (G.src )
89 #define dst (G.dst )
90 #define me (G.me )
91 #define he (G.he )
92 #define count (G.count )
93 #define last (G.last )
94 #define timeout_us (G.timeout_us)
95 #define start (G.start )
96 #define sent (G.sent )
97 #define brd_sent (G.brd_sent )
98 #define received (G.received )
99 #define brd_recv (G.brd_recv )
100 #define req_recv (G.req_recv )
101 //#define G (*(struct globals*)bb_common_bufsiz1)
102 #define G (*ptr_to_globals)
103 #define INIT_G() do { \
104 /*setup_common_bufsiz();*/ \
105 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
106 count = -1; \
107 } while (0)
108
109 #define sock_fd 3
110
send_pack(struct in_addr * src_addr,struct in_addr * dst_addr,struct sockaddr_ll * ME,struct sockaddr_ll * HE)111 static int send_pack(struct in_addr *src_addr,
112 struct in_addr *dst_addr,
113 struct sockaddr_ll *ME,
114 struct sockaddr_ll *HE)
115 {
116 int err;
117 unsigned char buf[256];
118 struct arphdr *ah = (struct arphdr *) buf;
119 unsigned char *p;
120
121 ah->ar_hrd = htons(ARPHRD_ETHER);
122 ah->ar_pro = htons(ETH_P_IP);
123 ah->ar_hln = ME->sll_halen;
124 ah->ar_pln = 4;
125 ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
126
127 p = (unsigned char *) (ah + 1);
128 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
129 p = mempcpy(p, src_addr, 4);
130
131 if (option_mask32 & ADVERT)
132 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
133 else
134 p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
135
136 p = mempcpy(p, dst_addr, 4);
137
138 err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
139 if (err == p - buf) {
140 last = MONOTONIC_US();
141 sent++;
142 if (!(option_mask32 & UNICASTING))
143 brd_sent++;
144 }
145 return err;
146 }
147
148 static void finish(void) NORETURN;
finish(void)149 static void finish(void)
150 {
151 if (!(option_mask32 & QUIET)) {
152 printf("Sent %u probe(s) (%u broadcast(s))\n"
153 "Received %u response(s)"
154 " (%u request(s), %u broadcast(s))\n",
155 sent, brd_sent,
156 received,
157 req_recv, brd_recv);
158 }
159 if (option_mask32 & DAD)
160 exit(!!received);
161 if (option_mask32 & UNSOLICITED)
162 exit(EXIT_SUCCESS);
163 exit(!received);
164 }
165
catcher(void)166 static void catcher(void)
167 {
168 unsigned now;
169
170 now = MONOTONIC_US();
171 if (start == 0)
172 start = now;
173
174 if (count == 0 || (timeout_us && (now - start) > timeout_us))
175 finish();
176
177 /* count < 0 means "infinite count" */
178 if (count > 0)
179 count--;
180
181 if (last == 0 || (now - last) > 500000) {
182 send_pack(&src, &dst, &me, &he);
183 if (count == 0 && (option_mask32 & UNSOLICITED))
184 finish();
185 }
186 alarm(1);
187 }
188
recv_pack(unsigned char * buf,int len,struct sockaddr_ll * FROM)189 static void recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
190 {
191 struct arphdr *ah = (struct arphdr *) buf;
192 unsigned char *p = (unsigned char *) (ah + 1);
193 struct in_addr src_ip, dst_ip;
194
195 /* moves below assume in_addr is 4 bytes big, ensure that */
196 BUILD_BUG_ON(sizeof(struct in_addr) != 4);
197 BUILD_BUG_ON(sizeof(src_ip.s_addr) != 4);
198
199 /* Filter out wild packets */
200 if (FROM->sll_pkttype != PACKET_HOST
201 && FROM->sll_pkttype != PACKET_BROADCAST
202 && FROM->sll_pkttype != PACKET_MULTICAST)
203 return;
204
205 /* Only these types are recognized */
206 if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
207 return;
208
209 /* ARPHRD check and this darned FDDI hack here :-( */
210 if (ah->ar_hrd != htons(FROM->sll_hatype)
211 && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
212 return;
213
214 /* Protocol must be IP. */
215 if (ah->ar_pro != htons(ETH_P_IP)
216 || (ah->ar_pln != 4)
217 || (ah->ar_hln != me.sll_halen)
218 || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln)))
219 ) {
220 return;
221 }
222
223 move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
224 move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
225
226 if (dst.s_addr != src_ip.s_addr)
227 return;
228 if (!(option_mask32 & DAD)) {
229 if ((src.s_addr != dst_ip.s_addr)
230 || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
231 return;
232 } else {
233 /* DAD packet was:
234 src_ip = 0 (or some src)
235 src_hw = ME
236 dst_ip = tested address
237 dst_hw = <unspec>
238
239 We fail, if receive request/reply with:
240 src_ip = tested_address
241 src_hw != ME
242 if src_ip in request was not zero, check
243 also that it matches to dst_ip, otherwise
244 dst_ip/dst_hw do not matter.
245 */
246 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
247 || (src.s_addr && src.s_addr != dst_ip.s_addr))
248 return;
249 }
250 if (!(option_mask32 & QUIET)) {
251 int s_printed = 0;
252
253 //TODO: arping from iputils-s20160308 print upprcase hex in MAC, follow them?
254 printf("%scast re%s from %s [%02x:%02x:%02x:%02x:%02x:%02x]",
255 FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
256 ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
257 inet_ntoa(src_ip),
258 p[0], p[1], p[2], p[3], p[4], p[5]
259 );
260 if (dst_ip.s_addr != src.s_addr) {
261 printf("for %s", inet_ntoa(dst_ip));
262 s_printed = 1;
263 }
264 if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
265 unsigned char *pp = p + ah->ar_hln + 4;
266 if (!s_printed)
267 printf(" for");
268 printf(" [%02x:%02x:%02x:%02x:%02x:%02x]",
269 pp[0], pp[1], pp[2], pp[3], pp[4], pp[5]
270 );
271 }
272
273 if (last) {
274 unsigned diff = MONOTONIC_US() - last;
275 printf(" %u.%03ums\n", diff / 1000, diff % 1000);
276 } else {
277 puts(" UNSOLICITED?");
278 }
279 fflush_all();
280 }
281 received++;
282 if (FROM->sll_pkttype != PACKET_HOST)
283 brd_recv++;
284 if (ah->ar_op == htons(ARPOP_REQUEST))
285 req_recv++;
286 if (option_mask32 & QUIT_ON_REPLY)
287 finish();
288 if (!(option_mask32 & BCAST_ONLY)) {
289 memcpy(he.sll_addr, p, me.sll_halen);
290 option_mask32 |= UNICASTING;
291 }
292 }
293
294 int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
arping_main(int argc UNUSED_PARAM,char ** argv)295 int arping_main(int argc UNUSED_PARAM, char **argv)
296 {
297 const char *device = "eth0";
298 char *source = NULL;
299 char *target;
300 char *err_str;
301
302 INIT_G();
303
304 xmove_fd(xsocket(AF_PACKET, SOCK_DGRAM, 0), sock_fd);
305
306 // If you ever change BB_SUID_DROP to BB_SUID_REQUIRE,
307 // drop suid root privileges here:
308 //xsetuid(getuid());
309
310 {
311 unsigned opt;
312 char *str_timeout;
313
314 opt = GETOPT32(str_timeout, device, source);
315 if (opt & TIMEOUT)
316 timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
317 }
318
319 target = argv[optind];
320 err_str = xasprintf("interface %s %%s", device);
321 xfunc_error_retval = 2;
322
323 /*memset(&G.ifr, 0, sizeof(G.ifr)); - zeroed by INIT_G */
324 strncpy_IFNAMSIZ(G.ifr.ifr_name, device);
325 ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &G.ifr, err_str, "not found");
326 me.sll_ifindex = G.ifr.ifr_ifindex;
327
328 xioctl(sock_fd, SIOCGIFFLAGS, (char *) &G.ifr);
329
330 if (!(G.ifr.ifr_flags & IFF_UP)) {
331 bb_error_msg_and_die(err_str, "is down");
332 }
333 if (G.ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
334 bb_error_msg(err_str, "is not ARPable");
335 BUILD_BUG_ON(DAD != 2);
336 /* exit 0 if DAD, else exit 2 */
337 return (~option_mask32 & DAD);
338 }
339
340 /* if (!inet_aton(target, &dst)) - not needed */ {
341 len_and_sockaddr *lsa;
342 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
343 dst = lsa->u.sin.sin_addr;
344 if (ENABLE_FEATURE_CLEAN_UP)
345 free(lsa);
346 }
347
348 if (source && !inet_aton(source, &src)) {
349 bb_error_msg_and_die("invalid source address %s", source);
350 }
351
352 if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
353 src = dst;
354
355 if (!(option_mask32 & DAD) || src.s_addr) {
356 /*struct sockaddr_in probe_saddr;*/
357 int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
358
359 setsockopt_bindtodevice(probe_fd, device);
360
361 /*memset(&G.probe_saddr, 0, sizeof(G.probe_saddr)); - zeroed by INIT_G */
362 G.probe_saddr.sin_family = AF_INET;
363 if (src.s_addr) {
364 /* Check that this is indeed our IP */
365 G.probe_saddr.sin_addr = src;
366 xbind(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
367 } else { /* !(option_mask32 & DAD) case */
368 /* Find IP address on this iface */
369 G.probe_saddr.sin_port = htons(1025);
370 G.probe_saddr.sin_addr = dst;
371
372 if (setsockopt_SOL_SOCKET_1(probe_fd, SO_DONTROUTE) != 0)
373 bb_perror_msg("setsockopt(%s)", "SO_DONTROUTE");
374 xconnect(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
375 bb_getsockname(probe_fd, (struct sockaddr *) &G.probe_saddr, sizeof(G.probe_saddr));
376 if (G.probe_saddr.sin_family != AF_INET)
377 bb_simple_error_msg_and_die("no IP address configured");
378 src = G.probe_saddr.sin_addr;
379 }
380 close(probe_fd);
381 }
382
383 me.sll_family = AF_PACKET;
384 //me.sll_ifindex = ifindex; - done before
385 me.sll_protocol = htons(ETH_P_ARP);
386 xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
387
388 bb_getsockname(sock_fd, (struct sockaddr *) &me, sizeof(me));
389 //never happens:
390 //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
391 // bb_perror_msg_and_die("getsockname");
392 if (me.sll_halen == 0) {
393 bb_error_msg(err_str, "is not ARPable (no ll address)");
394 BUILD_BUG_ON(DAD != 2);
395 /* exit 0 if DAD, else exit 2 */
396 return (~option_mask32 & DAD);
397 }
398 he = me;
399 memset(he.sll_addr, -1, he.sll_halen);
400
401 if (!(option_mask32 & QUIET)) {
402 /* inet_ntoa uses static storage, can't use in same printf */
403 printf("ARPING %s", inet_ntoa(dst));
404 printf(" from %s %s\n", inet_ntoa(src), device);
405 }
406
407 /*sigemptyset(&G.sset); - zeroed by INIT_G */
408 sigaddset(&G.sset, SIGALRM);
409 sigaddset(&G.sset, SIGINT);
410 signal_SA_RESTART_empty_mask(SIGINT, (void (*)(int))finish);
411 signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
412
413 /* Send the first packet, arm ALRM */
414 catcher();
415
416 while (1) {
417 struct sockaddr_ll from;
418 socklen_t alen = sizeof(from);
419 int cc;
420
421 /* Unblock SIGALRM so that the previously called alarm()
422 * can prevent recvfrom from blocking forever in case the
423 * inherited procmask is blocking SIGALRM.
424 */
425 sigprocmask(SIG_UNBLOCK, &G.sset, NULL);
426
427 cc = recvfrom(sock_fd, G.packet, sizeof(G.packet), 0, (struct sockaddr *) &from, &alen);
428
429 /* Don't allow SIGALRMs while we process the reply */
430 sigprocmask(SIG_BLOCK, &G.sset, NULL);
431 if (cc < 0) {
432 bb_simple_perror_msg("recvfrom");
433 continue;
434 }
435 recv_pack(G.packet, cc, &from);
436 }
437 }
438