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
30#define	ARP_OPT_A (0x1)
31#define	ARP_OPT_p (0x2)
32#define	ARP_OPT_H (0x4)
33#define	ARP_OPT_t (0x8)
34#define	ARP_OPT_i (0x10)
35#define	ARP_OPT_a (0x20)
36#define	ARP_OPT_d (0x40)
37#define	ARP_OPT_n (0x80)	/* do not resolve addresses     */
38#define	ARP_OPT_D (0x100)	/* HW-address is devicename     */
39#define	ARP_OPT_s (0x200)
40#define	ARP_OPT_v (0x400 * DEBUG)	/* debugging output flag        */
41
42
43static const struct aftype *ap; /* current address family       */
44static const struct hwtype *hw; /* current hardware type        */
45static int sockfd;              /* active socket descriptor     */
46static smallint hw_set;         /* flag if hw-type was set (-H) */
47static const char *device = ""; /* current device               */
48
49static const char options[] ALIGN1 =
50	"pub\0"
51	"priv\0"
52	"temp\0"
53	"trail\0"
54	"dontpub\0"
55	"auto\0"
56	"dev\0"
57	"netmask\0";
58
59/* Delete an entry from the ARP cache. */
60/* Called only from main, once */
61static int arp_del(char **args)
62{
63	char *host;
64	struct arpreq req;
65	struct sockaddr sa;
66	int flags = 0;
67	int err;
68
69	memset(&req, 0, sizeof(req));
70
71	/* Resolve the host name. */
72	host = *args;
73	if (ap->input(host, &sa) < 0) {
74		bb_herror_msg_and_die("%s", host);
75	}
76
77	/* If a host has more than one address, use the correct one! */
78	memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
79
80	if (hw_set)
81		req.arp_ha.sa_family = hw->type;
82
83	req.arp_flags = ATF_PERM;
84	args++;
85	while (*args != NULL) {
86		switch (index_in_strings(options, *args)) {
87		case 0: /* "pub" */
88			flags |= 1;
89			args++;
90			break;
91		case 1: /* "priv" */
92			flags |= 2;
93			args++;
94			break;
95		case 2: /* "temp" */
96			req.arp_flags &= ~ATF_PERM;
97			args++;
98			break;
99		case 3: /* "trail" */
100			req.arp_flags |= ATF_USETRAILERS;
101			args++;
102			break;
103		case 4: /* "dontpub" */
104#ifdef HAVE_ATF_DONTPUB
105			req.arp_flags |= ATF_DONTPUB;
106#else
107			bb_error_msg("feature ATF_DONTPUB is not supported");
108#endif
109			args++;
110			break;
111		case 5: /* "auto" */
112#ifdef HAVE_ATF_MAGIC
113			req.arp_flags |= ATF_MAGIC;
114#else
115			bb_error_msg("feature ATF_MAGIC is not supported");
116#endif
117			args++;
118			break;
119		case 6: /* "dev" */
120			if (*++args == NULL)
121				bb_show_usage();
122			device = *args;
123			args++;
124			break;
125		case 7: /* "netmask" */
126			if (*++args == NULL)
127				bb_show_usage();
128			if (strcmp(*args, "255.255.255.255") != 0) {
129				host = *args;
130				if (ap->input(host, &sa) < 0) {
131					bb_herror_msg_and_die("%s", host);
132				}
133				memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
134				req.arp_flags |= ATF_NETMASK;
135			}
136			args++;
137			break;
138		default:
139			bb_show_usage();
140			break;
141		}
142	}
143	if (flags == 0)
144		flags = 3;
145
146	strncpy(req.arp_dev, device, sizeof(req.arp_dev));
147
148	err = -1;
149
150	/* Call the kernel. */
151	if (flags & 2) {
152		if (option_mask32 & ARP_OPT_v)
153			bb_error_msg("SIOCDARP(nopub)");
154		err = ioctl(sockfd, SIOCDARP, &req);
155		if (err < 0) {
156			if (errno == ENXIO) {
157				if (flags & 1)
158					goto nopub;
159				printf("No ARP entry for %s\n", host);
160				return -1;
161			}
162			bb_perror_msg_and_die("SIOCDARP(priv)");
163		}
164	}
165	if ((flags & 1) && err) {
166 nopub:
167		req.arp_flags |= ATF_PUBL;
168		if (option_mask32 & ARP_OPT_v)
169			bb_error_msg("SIOCDARP(pub)");
170		if (ioctl(sockfd, SIOCDARP, &req) < 0) {
171			if (errno == ENXIO) {
172				printf("No ARP entry for %s\n", host);
173				return -1;
174			}
175			bb_perror_msg_and_die("SIOCDARP(pub)");
176		}
177	}
178	return 0;
179}
180
181/* Get the hardware address to a specified interface name */
182static void arp_getdevhw(char *ifname, struct sockaddr *sa,
183						 const struct hwtype *hwt)
184{
185	struct ifreq ifr;
186	const struct hwtype *xhw;
187
188	strcpy(ifr.ifr_name, ifname);
189	ioctl_or_perror_and_die(sockfd, SIOCGIFHWADDR, &ifr,
190					"cant get HW-Address for '%s'", ifname);
191	if (hwt && (ifr.ifr_hwaddr.sa_family != hw->type)) {
192		bb_error_msg_and_die("protocol type mismatch");
193	}
194	memcpy(sa, &(ifr.ifr_hwaddr), sizeof(struct sockaddr));
195
196	if (option_mask32 & ARP_OPT_v) {
197		xhw = get_hwntype(ifr.ifr_hwaddr.sa_family);
198		if (!xhw || !xhw->print) {
199			xhw = get_hwntype(-1);
200		}
201		bb_error_msg("device '%s' has HW address %s '%s'",
202					 ifname, xhw->name,
203					 xhw->print((char *) &ifr.ifr_hwaddr.sa_data));
204	}
205}
206
207/* Set an entry in the ARP cache. */
208/* Called only from main, once */
209static int arp_set(char **args)
210{
211	char *host;
212	struct arpreq req;
213	struct sockaddr sa;
214	int flags;
215
216	memset(&req, 0, sizeof(req));
217
218	host = *args++;
219	if (ap->input(host, &sa) < 0) {
220		bb_herror_msg_and_die("%s", host);
221	}
222	/* If a host has more than one address, use the correct one! */
223	memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
224
225	/* Fetch the hardware address. */
226	if (*args == NULL) {
227		bb_error_msg_and_die("need hardware address");
228	}
229	if (option_mask32 & ARP_OPT_D) {
230		arp_getdevhw(*args++, &req.arp_ha, hw_set ? hw : NULL);
231	} else {
232		if (hw->input(*args++, &req.arp_ha) < 0) {
233			bb_error_msg_and_die("invalid hardware address");
234		}
235	}
236
237	/* Check out any modifiers. */
238	flags = ATF_PERM | ATF_COM;
239	while (*args != NULL) {
240		switch (index_in_strings(options, *args)) {
241		case 0: /* "pub" */
242			flags |= ATF_PUBL;
243			args++;
244			break;
245		case 1: /* "priv" */
246			flags &= ~ATF_PUBL;
247			args++;
248			break;
249		case 2: /* "temp" */
250			flags &= ~ATF_PERM;
251			args++;
252			break;
253		case 3: /* "trail" */
254			flags |= ATF_USETRAILERS;
255			args++;
256			break;
257		case 4: /* "dontpub" */
258#ifdef HAVE_ATF_DONTPUB
259			flags |= ATF_DONTPUB;
260#else
261			bb_error_msg("feature ATF_DONTPUB is not supported");
262#endif
263			args++;
264			break;
265		case 5: /* "auto" */
266#ifdef HAVE_ATF_MAGIC
267			flags |= ATF_MAGIC;
268#else
269			bb_error_msg("feature ATF_MAGIC is not supported");
270#endif
271			args++;
272			break;
273		case 6: /* "dev" */
274			if (*++args == NULL)
275				bb_show_usage();
276			device = *args;
277			args++;
278			break;
279		case 7: /* "netmask" */
280			if (*++args == NULL)
281				bb_show_usage();
282			if (strcmp(*args, "255.255.255.255") != 0) {
283				host = *args;
284				if (ap->input(host, &sa) < 0) {
285					bb_herror_msg_and_die("%s", host);
286				}
287				memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
288				flags |= ATF_NETMASK;
289			}
290			args++;
291			break;
292		default:
293			bb_show_usage();
294			break;
295		}
296	}
297
298	/* Fill in the remainder of the request. */
299	req.arp_flags = flags;
300
301	strncpy(req.arp_dev, device, sizeof(req.arp_dev));
302
303	/* Call the kernel. */
304	if (option_mask32 & ARP_OPT_v)
305		bb_error_msg("SIOCSARP()");
306	xioctl(sockfd, SIOCSARP, &req);
307	return 0;
308}
309
310
311/* Print the contents of an ARP request block. */
312static void
313arp_disp(const char *name, char *ip, int type, int arp_flags,
314		 char *hwa, char *mask, char *dev)
315{
316	const struct hwtype *xhw;
317
318	xhw = get_hwntype(type);
319	if (xhw == NULL)
320		xhw = get_hwtype(DFLT_HW);
321
322	printf("%s (%s) at ", name, ip);
323
324	if (!(arp_flags & ATF_COM)) {
325		if (arp_flags & ATF_PUBL)
326			printf("* ");
327		else
328			printf("<incomplete> ");
329	} else {
330		printf("%s [%s] ", hwa, xhw->name);
331	}
332
333	if (arp_flags & ATF_NETMASK)
334		printf("netmask %s ", mask);
335
336	if (arp_flags & ATF_PERM)
337		printf("PERM ");
338	if (arp_flags & ATF_PUBL)
339		printf("PUP ");
340#ifdef HAVE_ATF_MAGIC
341	if (arp_flags & ATF_MAGIC)
342		printf("AUTO ");
343#endif
344#ifdef HAVE_ATF_DONTPUB
345	if (arp_flags & ATF_DONTPUB)
346		printf("DONTPUB ");
347#endif
348	if (arp_flags & ATF_USETRAILERS)
349		printf("TRAIL ");
350
351	printf("on %s\n", dev);
352}
353
354/* Display the contents of the ARP cache in the kernel. */
355/* Called only from main, once */
356static int arp_show(char *name)
357{
358	const char *host;
359	const char *hostname;
360	FILE *fp;
361	struct sockaddr sa;
362	int type, flags;
363	int num;
364	unsigned entries = 0, shown = 0;
365	char ip[128];
366	char hwa[128];
367	char mask[128];
368	char line[128];
369	char dev[128];
370
371	host = NULL;
372	if (name != NULL) {
373		/* Resolve the host name. */
374		if (ap->input(name, &sa) < 0) {
375			bb_herror_msg_and_die("%s", name);
376		}
377		host = xstrdup(ap->sprint(&sa, 1));
378	}
379	fp = xfopen("/proc/net/arp", "r");
380	/* Bypass header -- read one line */
381	fgets(line, sizeof(line), fp);
382
383	/* Read the ARP cache entries. */
384	while (fgets(line, sizeof(line), fp)) {
385
386		mask[0] = '-'; mask[1] = '\0';
387		dev[0] = '-'; dev[1] = '\0';
388		/* All these strings can't overflow
389		 * because fgets above reads limited amount of data */
390		num = sscanf(line, "%s 0x%x 0x%x %s %s %s\n",
391					 ip, &type, &flags, hwa, mask, dev);
392		if (num < 4)
393			break;
394
395		entries++;
396		/* if the user specified hw-type differs, skip it */
397		if (hw_set && (type != hw->type))
398			continue;
399
400		/* if the user specified address differs, skip it */
401		if (host && strcmp(ip, host) != 0)
402			continue;
403
404		/* if the user specified device differs, skip it */
405		if (device[0] && strcmp(dev, device) != 0)
406			continue;
407
408		shown++;
409		/* This IS ugly but it works -be */
410		hostname = "?";
411		if (!(option_mask32 & ARP_OPT_n)) {
412			if (ap->input(ip, &sa) < 0)
413				hostname = ip;
414			else
415				hostname = ap->sprint(&sa, (option_mask32 & ARP_OPT_n) | 0x8000);
416			if (strcmp(hostname, ip) == 0)
417				hostname = "?";
418		}
419
420		arp_disp(hostname, ip, type, flags, hwa, mask, dev);
421	}
422	if (option_mask32 & ARP_OPT_v)
423		printf("Entries: %d\tSkipped: %d\tFound: %d\n",
424			   entries, entries - shown, shown);
425
426	if (!shown) {
427		if (hw_set || host || device[0])
428			printf("No match found in %d entries\n", entries);
429	}
430	if (ENABLE_FEATURE_CLEAN_UP) {
431		free((char*)host);
432		fclose(fp);
433	}
434	return 0;
435}
436
437int arp_main(int argc, char **argv);
438int arp_main(int argc, char **argv)
439{
440	char *hw_type;
441	char *protocol;
442
443	/* Initialize variables... */
444	ap = get_aftype(DFLT_AF);
445	if (!ap)
446		bb_error_msg_and_die("%s: %s not supported", DFLT_AF, "address family");
447
448	getopt32(argv, "A:p:H:t:i:adnDsv", &protocol, &protocol,
449				 &hw_type, &hw_type, &device);
450	argv += optind;
451	if (option_mask32 & ARP_OPT_A || option_mask32 & ARP_OPT_p) {
452		ap = get_aftype(protocol);
453		if (ap == NULL)
454			bb_error_msg_and_die("%s: unknown %s", protocol, "address family");
455	}
456	if (option_mask32 & ARP_OPT_A || option_mask32 & ARP_OPT_p) {
457		hw = get_hwtype(hw_type);
458		if (hw == NULL)
459			bb_error_msg_and_die("%s: unknown %s", hw_type, "hardware type");
460		hw_set = 1;
461	}
462	//if (option_mask32 & ARP_OPT_i)... -i
463
464	if (ap->af != AF_INET) {
465		bb_error_msg_and_die("%s: kernel only supports 'inet'", ap->name);
466	}
467
468	/* If no hw type specified get default */
469	if (!hw) {
470		hw = get_hwtype(DFLT_HW);
471		if (!hw)
472			bb_error_msg_and_die("%s: %s not supported", DFLT_HW, "hardware type");
473	}
474
475	if (hw->alen <= 0) {
476		bb_error_msg_and_die("%s: %s without ARP support",
477							 hw->name, "hardware type");
478	}
479	sockfd = xsocket(AF_INET, SOCK_DGRAM, 0);
480
481	/* Now see what we have to do here... */
482	if (option_mask32 & (ARP_OPT_d|ARP_OPT_s)) {
483		if (argv[0] == NULL)
484			bb_error_msg_and_die("need host name");
485		if (option_mask32 & ARP_OPT_s)
486			return arp_set(argv);
487		return arp_del(argv);
488	}
489	//if (option_mask32 & ARP_OPT_a) - default
490	return arp_show(argv[0]);
491}
492