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