1 /* vi: set sw=4 ts=4: */
2 /*
3 * arp.c - Manipulate the system ARP cache
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * Author: Fred N. van Kempen, <waltje at uwalt.nl.mugnet.org>
11 * Busybox port: Paul van Gool <pvangool at mimotech.com>
12 *
13 * modified for getopt32 by Arne Bernin <arne [at] alamut.de>
14 */
15 //config:config ARP
16 //config: bool "arp"
17 //config: default y
18 //config: select PLATFORM_LINUX
19 //config: help
20 //config: Manipulate the system ARP cache.
21
22 //applet:IF_ARP(APPLET(arp, BB_DIR_SBIN, BB_SUID_DROP))
23
24 //kbuild:lib-$(CONFIG_ARP) += arp.o interface.o
25
26 //usage:#define arp_trivial_usage
27 //usage: "\n[-vn] [-H HWTYPE] [-i IF] -a [HOSTNAME]"
28 //usage: "\n[-v] [-i IF] -d HOSTNAME [pub]"
29 //usage: "\n[-v] [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [temp]"
30 //usage: "\n[-v] [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [netmask MASK] pub"
31 //usage: "\n[-v] [-H HWTYPE] [-i IF] -Ds HOSTNAME IFACE [netmask MASK] pub"
32 //usage:#define arp_full_usage "\n\n"
33 //usage: "Manipulate ARP cache\n"
34 //usage: "\n -a Display (all) hosts"
35 //usage: "\n -d Delete ARP entry"
36 //usage: "\n -s Set new entry"
37 //usage: "\n -v Verbose"
38 //usage: "\n -n Don't resolve names"
39 //usage: "\n -i IF Network interface"
40 //usage: "\n -D Read HWADDR from IFACE"
41 //usage: "\n -A,-p AF Protocol family"
42 //usage: "\n -H HWTYPE Hardware address type"
43
44 #include "libbb.h"
45 #include "common_bufsiz.h"
46 #include "inet_common.h"
47
48 #include <arpa/inet.h>
49 #include <net/if.h>
50 #include <net/if_arp.h>
51 #include <netinet/ether.h>
52 #include <netpacket/packet.h>
53
54 #define DEBUG 0
55
56 #define DFLT_AF "inet"
57 #define DFLT_HW "ether"
58
59 enum {
60 ARP_OPT_A = (1 << 0),
61 ARP_OPT_p = (1 << 1),
62 ARP_OPT_H = (1 << 2),
63 ARP_OPT_t = (1 << 3),
64 ARP_OPT_i = (1 << 4),
65 ARP_OPT_a = (1 << 5),
66 ARP_OPT_d = (1 << 6),
67 ARP_OPT_n = (1 << 7), /* do not resolve addresses */
68 ARP_OPT_D = (1 << 8), /* HW-address is devicename */
69 ARP_OPT_s = (1 << 9),
70 ARP_OPT_v = (1 << 10) * DEBUG, /* debugging output flag */
71 };
72
73 enum {
74 sockfd = 3, /* active socket descriptor */
75 };
76
77 struct globals {
78 const struct aftype *ap; /* current address family */
79 const struct hwtype *hw; /* current hardware type */
80 const char *device; /* current device */
81 smallint hw_set; /* flag if hw-type was set (-H) */
82 } FIX_ALIASING;
83 #define G (*(struct globals*)bb_common_bufsiz1)
84 #define ap (G.ap )
85 #define hw (G.hw )
86 #define device (G.device )
87 #define hw_set (G.hw_set )
88 #define INIT_G() do { \
89 setup_common_bufsiz(); \
90 device = ""; \
91 } while (0)
92
93
94 static const char options[] ALIGN1 =
95 "pub\0"
96 "priv\0"
97 "temp\0"
98 "trail\0"
99 "dontpub\0"
100 "auto\0"
101 "dev\0"
102 "netmask\0";
103
104 /* Delete an entry from the ARP cache. */
105 /* Called only from main, once */
arp_del(char ** args)106 static int arp_del(char **args)
107 {
108 char *host;
109 struct arpreq req;
110 struct sockaddr sa;
111 int flags = 0;
112 int err;
113
114 memset(&req, 0, sizeof(req));
115
116 /* Resolve the host name. */
117 host = *args;
118 if (ap->input(host, &sa) < 0) {
119 bb_herror_msg_and_die("%s", host);
120 }
121
122 /* If a host has more than one address, use the correct one! */
123 memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
124
125 if (hw_set)
126 req.arp_ha.sa_family = hw->type;
127
128 req.arp_flags = ATF_PERM;
129 args++;
130 while (*args != NULL) {
131 switch (index_in_strings(options, *args)) {
132 case 0: /* "pub" */
133 flags |= 1;
134 args++;
135 break;
136 case 1: /* "priv" */
137 flags |= 2;
138 args++;
139 break;
140 case 2: /* "temp" */
141 req.arp_flags &= ~ATF_PERM;
142 args++;
143 break;
144 case 3: /* "trail" */
145 req.arp_flags |= ATF_USETRAILERS;
146 args++;
147 break;
148 case 4: /* "dontpub" */
149 #ifdef HAVE_ATF_DONTPUB
150 req.arp_flags |= ATF_DONTPUB;
151 #else
152 bb_error_msg("feature ATF_DONTPUB is not supported");
153 #endif
154 args++;
155 break;
156 case 5: /* "auto" */
157 #ifdef HAVE_ATF_MAGIC
158 req.arp_flags |= ATF_MAGIC;
159 #else
160 bb_error_msg("feature ATF_MAGIC is not supported");
161 #endif
162 args++;
163 break;
164 case 6: /* "dev" */
165 if (*++args == NULL)
166 bb_show_usage();
167 device = *args;
168 args++;
169 break;
170 case 7: /* "netmask" */
171 if (*++args == NULL)
172 bb_show_usage();
173 if (strcmp(*args, "255.255.255.255") != 0) {
174 host = *args;
175 if (ap->input(host, &sa) < 0) {
176 bb_herror_msg_and_die("%s", host);
177 }
178 memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
179 req.arp_flags |= ATF_NETMASK;
180 }
181 args++;
182 break;
183 default:
184 bb_show_usage();
185 break;
186 }
187 }
188 if (flags == 0)
189 flags = 3;
190
191 strncpy_IFNAMSIZ(req.arp_dev, device);
192
193 err = -1;
194
195 /* Call the kernel. */
196 if (flags & 2) {
197 if (option_mask32 & ARP_OPT_v)
198 bb_error_msg("SIOCDARP(nopub)");
199 err = ioctl(sockfd, SIOCDARP, &req);
200 if (err < 0) {
201 if (errno == ENXIO) {
202 if (flags & 1)
203 goto nopub;
204 printf("No ARP entry for %s\n", host);
205 return -1;
206 }
207 bb_perror_msg_and_die("SIOCDARP(priv)");
208 }
209 }
210 if ((flags & 1) && err) {
211 nopub:
212 req.arp_flags |= ATF_PUBL;
213 if (option_mask32 & ARP_OPT_v)
214 bb_error_msg("SIOCDARP(pub)");
215 if (ioctl(sockfd, SIOCDARP, &req) < 0) {
216 if (errno == ENXIO) {
217 printf("No ARP entry for %s\n", host);
218 return -1;
219 }
220 bb_perror_msg_and_die("SIOCDARP(pub)");
221 }
222 }
223 return 0;
224 }
225
226 /* Get the hardware address to a specified interface name */
arp_getdevhw(char * ifname,struct sockaddr * sa)227 static void arp_getdevhw(char *ifname, struct sockaddr *sa)
228 {
229 struct ifreq ifr;
230 const struct hwtype *xhw;
231
232 strncpy_IFNAMSIZ(ifr.ifr_name, ifname);
233 ioctl_or_perror_and_die(sockfd, SIOCGIFHWADDR, &ifr,
234 "can't get HW-Address for '%s'", ifname);
235 if (hw_set && (ifr.ifr_hwaddr.sa_family != hw->type)) {
236 bb_error_msg_and_die("protocol type mismatch");
237 }
238 memcpy(sa, &(ifr.ifr_hwaddr), sizeof(struct sockaddr));
239
240 if (option_mask32 & ARP_OPT_v) {
241 xhw = get_hwntype(ifr.ifr_hwaddr.sa_family);
242 if (!xhw || !xhw->print) {
243 xhw = get_hwntype(-1);
244 }
245 bb_error_msg("device '%s' has HW address %s '%s'",
246 ifname, xhw->name,
247 xhw->print((unsigned char *) &ifr.ifr_hwaddr.sa_data));
248 }
249 }
250
251 /* Set an entry in the ARP cache. */
252 /* Called only from main, once */
arp_set(char ** args)253 static int arp_set(char **args)
254 {
255 char *host;
256 struct arpreq req;
257 struct sockaddr sa;
258 int flags;
259
260 memset(&req, 0, sizeof(req));
261
262 host = *args++;
263 if (ap->input(host, &sa) < 0) {
264 bb_herror_msg_and_die("%s", host);
265 }
266 /* If a host has more than one address, use the correct one! */
267 memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
268
269 /* Fetch the hardware address. */
270 if (*args == NULL) {
271 bb_error_msg_and_die("need hardware address");
272 }
273 if (option_mask32 & ARP_OPT_D) {
274 arp_getdevhw(*args++, &req.arp_ha);
275 } else {
276 if (hw->input(*args++, &req.arp_ha) < 0) {
277 bb_error_msg_and_die("invalid hardware address");
278 }
279 }
280
281 /* Check out any modifiers. */
282 flags = ATF_PERM | ATF_COM;
283 while (*args != NULL) {
284 switch (index_in_strings(options, *args)) {
285 case 0: /* "pub" */
286 flags |= ATF_PUBL;
287 args++;
288 break;
289 case 1: /* "priv" */
290 flags &= ~ATF_PUBL;
291 args++;
292 break;
293 case 2: /* "temp" */
294 flags &= ~ATF_PERM;
295 args++;
296 break;
297 case 3: /* "trail" */
298 flags |= ATF_USETRAILERS;
299 args++;
300 break;
301 case 4: /* "dontpub" */
302 #ifdef HAVE_ATF_DONTPUB
303 flags |= ATF_DONTPUB;
304 #else
305 bb_error_msg("feature ATF_DONTPUB is not supported");
306 #endif
307 args++;
308 break;
309 case 5: /* "auto" */
310 #ifdef HAVE_ATF_MAGIC
311 flags |= ATF_MAGIC;
312 #else
313 bb_error_msg("feature ATF_MAGIC is not supported");
314 #endif
315 args++;
316 break;
317 case 6: /* "dev" */
318 if (*++args == NULL)
319 bb_show_usage();
320 device = *args;
321 args++;
322 break;
323 case 7: /* "netmask" */
324 if (*++args == NULL)
325 bb_show_usage();
326 if (strcmp(*args, "255.255.255.255") != 0) {
327 host = *args;
328 if (ap->input(host, &sa) < 0) {
329 bb_herror_msg_and_die("%s", host);
330 }
331 memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
332 flags |= ATF_NETMASK;
333 }
334 args++;
335 break;
336 default:
337 bb_show_usage();
338 break;
339 }
340 }
341
342 /* Fill in the remainder of the request. */
343 req.arp_flags = flags;
344
345 strncpy_IFNAMSIZ(req.arp_dev, device);
346
347 /* Call the kernel. */
348 if (option_mask32 & ARP_OPT_v)
349 bb_error_msg("SIOCSARP()");
350 xioctl(sockfd, SIOCSARP, &req);
351 return 0;
352 }
353
354
355 /* Print the contents of an ARP request block. */
356 static void
arp_disp(const char * name,char * ip,int type,int arp_flags,char * hwa,char * mask,char * dev)357 arp_disp(const char *name, char *ip, int type, int arp_flags,
358 char *hwa, char *mask, char *dev)
359 {
360 static const int arp_masks[] = {
361 ATF_PERM, ATF_PUBL,
362 #ifdef HAVE_ATF_MAGIC
363 ATF_MAGIC,
364 #endif
365 #ifdef HAVE_ATF_DONTPUB
366 ATF_DONTPUB,
367 #endif
368 ATF_USETRAILERS,
369 };
370 static const char arp_labels[] ALIGN1 = "PERM\0""PUP\0"
371 #ifdef HAVE_ATF_MAGIC
372 "AUTO\0"
373 #endif
374 #ifdef HAVE_ATF_DONTPUB
375 "DONTPUB\0"
376 #endif
377 "TRAIL\0"
378 ;
379
380 const struct hwtype *xhw;
381
382 xhw = get_hwntype(type);
383 if (xhw == NULL)
384 xhw = get_hwtype(DFLT_HW);
385
386 printf("%s (%s) at ", name, ip);
387
388 if (!(arp_flags & ATF_COM)) {
389 if (arp_flags & ATF_PUBL)
390 printf("* ");
391 else
392 printf("<incomplete> ");
393 } else {
394 printf("%s [%s] ", hwa, xhw->name);
395 }
396
397 if (arp_flags & ATF_NETMASK)
398 printf("netmask %s ", mask);
399
400 print_flags_separated(arp_masks, arp_labels, arp_flags, " ");
401 printf(" on %s\n", dev);
402 }
403
404 /* Display the contents of the ARP cache in the kernel. */
405 /* Called only from main, once */
arp_show(char * name)406 static int arp_show(char *name)
407 {
408 const char *host;
409 const char *hostname;
410 FILE *fp;
411 struct sockaddr sa;
412 int type, flags;
413 int num;
414 unsigned entries = 0, shown = 0;
415 char ip[128];
416 char hwa[128];
417 char mask[128];
418 char line[128];
419 char dev[128];
420
421 host = NULL;
422 if (name != NULL) {
423 /* Resolve the host name. */
424 if (ap->input(name, &sa) < 0) {
425 bb_herror_msg_and_die("%s", name);
426 }
427 host = xstrdup(ap->sprint(&sa, 1));
428 }
429 fp = xfopen_for_read("/proc/net/arp");
430 /* Bypass header -- read one line */
431 fgets(line, sizeof(line), fp);
432
433 /* Read the ARP cache entries. */
434 while (fgets(line, sizeof(line), fp)) {
435
436 mask[0] = '-'; mask[1] = '\0';
437 dev[0] = '-'; dev[1] = '\0';
438 /* All these strings can't overflow
439 * because fgets above reads limited amount of data */
440 num = sscanf(line, "%s 0x%x 0x%x %s %s %s\n",
441 ip, &type, &flags, hwa, mask, dev);
442 if (num < 4)
443 break;
444
445 entries++;
446 /* if the user specified hw-type differs, skip it */
447 if (hw_set && (type != hw->type))
448 continue;
449
450 /* if the user specified address differs, skip it */
451 if (host && strcmp(ip, host) != 0)
452 continue;
453
454 /* if the user specified device differs, skip it */
455 if (device[0] && strcmp(dev, device) != 0)
456 continue;
457
458 shown++;
459 /* This IS ugly but it works -be */
460 hostname = "?";
461 if (!(option_mask32 & ARP_OPT_n)) {
462 if (ap->input(ip, &sa) < 0)
463 hostname = ip;
464 else
465 hostname = ap->sprint(&sa, (option_mask32 & ARP_OPT_n) | 0x8000);
466 if (strcmp(hostname, ip) == 0)
467 hostname = "?";
468 }
469
470 arp_disp(hostname, ip, type, flags, hwa, mask, dev);
471 }
472 if (option_mask32 & ARP_OPT_v)
473 printf("Entries: %u\tSkipped: %u\tFound: %u\n",
474 entries, entries - shown, shown);
475
476 if (!shown) {
477 if (hw_set || host || device[0])
478 printf("No match found in %u entries\n", entries);
479 }
480 if (ENABLE_FEATURE_CLEAN_UP) {
481 free((char*)host);
482 fclose(fp);
483 }
484 return 0;
485 }
486
487 int arp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
arp_main(int argc UNUSED_PARAM,char ** argv)488 int arp_main(int argc UNUSED_PARAM, char **argv)
489 {
490 const char *hw_type;
491 const char *protocol;
492 unsigned opts;
493
494 INIT_G();
495
496 xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), sockfd);
497
498 ap = get_aftype(DFLT_AF);
499 /* Defaults are always supported */
500 //if (!ap)
501 // bb_error_msg_and_die("%s: %s not supported", DFLT_AF, "address family");
502 hw = get_hwtype(DFLT_HW);
503 //if (!hw)
504 // bb_error_msg_and_die("%s: %s not supported", DFLT_HW, "hardware type");
505
506 opts = getopt32(argv, "A:p:H:t:i:adnDsv", &protocol, &protocol,
507 &hw_type, &hw_type, &device);
508 argv += optind;
509 if (opts & (ARP_OPT_A | ARP_OPT_p)) {
510 ap = get_aftype(protocol);
511 if (!ap)
512 bb_error_msg_and_die("%s: unknown %s", protocol, "address family");
513 }
514 if (opts & (ARP_OPT_H | ARP_OPT_t)) {
515 hw = get_hwtype(hw_type);
516 if (!hw)
517 bb_error_msg_and_die("%s: unknown %s", hw_type, "hardware type");
518 hw_set = 1;
519 }
520 //if (opts & ARP_OPT_i)... -i
521
522 if (ap->af != AF_INET) {
523 bb_error_msg_and_die("%s: kernel only supports 'inet'", ap->name);
524 }
525 if (hw->alen <= 0) {
526 bb_error_msg_and_die("%s: %s without ARP support",
527 hw->name, "hardware type");
528 }
529
530 /* Now see what we have to do here... */
531 if (opts & (ARP_OPT_d | ARP_OPT_s)) {
532 if (argv[0] == NULL)
533 bb_error_msg_and_die("need host name");
534 if (opts & ARP_OPT_s)
535 return arp_set(argv);
536 return arp_del(argv);
537 }
538
539 //if (opts & ARP_OPT_a) - default
540 return arp_show(argv[0]);
541 }
542