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source: rtems-libbsd/freebsd/usr.sbin/arp/arp.c @ 246b61e

55-freebsd-126-freebsd-12

Last change on this file since 246b61e was 246b61e, checked in by Sebastian Huber <sebastian.huber@…>, on 01/10/17 at 06:58:50
ARP(8): Import from FreeBSD
Property mode set to `100644`
File size: 20.4 KB

Line
1	#include <machine/rtems-bsd-user-space.h>
2
3	/*
4	* Copyright (c) 1984, 1993
5	* The Regents of the University of California. All rights reserved.
6	*
7	* This code is derived from software contributed to Berkeley by
8	* Sun Microsystems, Inc.
9	*
10	* Redistribution and use in source and binary forms, with or without
11	* modification, are permitted provided that the following conditions
12	* are met:
13	* 1. Redistributions of source code must retain the above copyright
14	* notice, this list of conditions and the following disclaimer.
15	* 2. Redistributions in binary form must reproduce the above copyright
16	* notice, this list of conditions and the following disclaimer in the
17	* documentation and/or other materials provided with the distribution.
18	* 4. Neither the name of the University nor the names of its contributors
19	* may be used to endorse or promote products derived from this software
20	* without specific prior written permission.
21	*
22	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32	* SUCH DAMAGE.
33	*/
34
35	#if 0
36	#ifndef lint
37	static char const copyright[] =
38	"@(#) Copyright (c) 1984, 1993\n\
39	The Regents of the University of California. All rights reserved.\n";
40	#endif /* not lint */
41
42	#ifndef lint
43	static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
44	#endif /* not lint */
45	#endif
46	#include <sys/cdefs.h>
47	__FBSDID("$FreeBSD$");
48
49	/*
50	* arp - display, set, and delete arp table entries
51	*/
52
53
54	#include <rtems/bsd/sys/param.h>
55	#include <sys/file.h>
56	#include <sys/socket.h>
57	#include <sys/sockio.h>
58	#include <sys/sysctl.h>
59	#include <sys/ioctl.h>
60	#include <sys/time.h>
61
62	#include <net/if.h>
63	#include <net/if_dl.h>
64	#include <net/if_types.h>
65	#include <net/route.h>
66	#include <net/iso88025.h>
67
68	#include <netinet/in.h>
69	#include <netinet/if_ether.h>
70
71	#include <arpa/inet.h>
72
73	#include <ctype.h>
74	#include <err.h>
75	#include <errno.h>
76	#include <netdb.h>
77	#include <nlist.h>
78	#include <paths.h>
79	#include <stdio.h>
80	#include <stdlib.h>
81	#include <string.h>
82	#include <strings.h>
83	#include <unistd.h>
84
85	typedef void (action_fn)(struct sockaddr_dl *sdl,
86	struct sockaddr_in s_in, struct rt_msghdr rtm);
87
88	static int search(u_long addr, action_fn *action);
89	static action_fn print_entry;
90	static action_fn nuke_entry;
91
92	static int delete(char *host);
93	static void usage(void);
94	static int set(int argc, char **argv);
95	static int get(char *host);
96	static int file(char *name);
97	static struct rt_msghdr *rtmsg(int cmd,
98	struct sockaddr_in dst, struct sockaddr_dl sdl);
99	static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
100	static struct sockaddr_in getaddr(char host);
101	static int valid_type(int type);
102
103	static int nflag; /* no reverse dns lookups */
104	static char *rifname;
105
106	static time_t expire_time;
107	static int flags, doing_proxy;
108
109	struct if_nameindex *ifnameindex;
110
111	/* which function we're supposed to do */
112	#define F_GET 1
113	#define F_SET 2
114	#define F_FILESET 3
115	#define F_REPLACE 4
116	#define F_DELETE 5
117
118	#define SETFUNC(f) { if (func) usage(); func = (f); }
119
120	int
121	main(int argc, char *argv[])
122	{
123	int ch, func = 0;
124	int rtn = 0;
125	int aflag = 0; /* do it for all entries */
126
127	while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
128	switch(ch) {
129	case 'a':
130	aflag = 1;
131	break;
132	case 'd':
133	SETFUNC(F_DELETE);
134	break;
135	case 'n':
136	nflag = 1;
137	break;
138	case 'S':
139	SETFUNC(F_REPLACE);
140	break;
141	case 's':
142	SETFUNC(F_SET);
143	break;
144	case 'f' :
145	SETFUNC(F_FILESET);
146	break;
147	case 'i':
148	rifname = optarg;
149	break;
150	case '?':
151	default:
152	usage();
153	}
154	argc -= optind;
155	argv += optind;
156
157	if (!func)
158	func = F_GET;
159	if (rifname) {
160	if (func != F_GET && !(func == F_DELETE && aflag))
161	errx(1, "-i not applicable to this operation");
162	if (if_nametoindex(rifname) == 0) {
163	if (errno == ENXIO)
164	errx(1, "interface %s does not exist", rifname);
165	else
166	err(1, "if_nametoindex(%s)", rifname);
167	}
168	}
169	switch (func) {
170	case F_GET:
171	if (aflag) {
172	if (argc != 0)
173	usage();
174	search(0, print_entry);
175	} else {
176	if (argc != 1)
177	usage();
178	rtn = get(argv[0]);
179	}
180	break;
181	case F_SET:
182	case F_REPLACE:
183	if (argc < 2 \|\| argc > 6)
184	usage();
185	if (func == F_REPLACE)
186	(void)delete(argv[0]);
187	rtn = set(argc, argv) ? 1 : 0;
188	break;
189	case F_DELETE:
190	if (aflag) {
191	if (argc != 0)
192	usage();
193	search(0, nuke_entry);
194	} else {
195	if (argc != 1)
196	usage();
197	rtn = delete(argv[0]);
198	}
199	break;
200	case F_FILESET:
201	if (argc != 1)
202	usage();
203	rtn = file(argv[0]);
204	break;
205	}
206
207	if (ifnameindex != NULL)
208	if_freenameindex(ifnameindex);
209
210	return (rtn);
211	}
212
213	/*
214	* Process a file to set standard arp entries
215	*/
216	static int
217	file(char *name)
218	{
219	FILE *fp;
220	int i, retval;
221	char line[100], arg[5][50], args[5], p;
222
223	if ((fp = fopen(name, "r")) == NULL)
224	err(1, "cannot open %s", name);
225	args[0] = &arg[0][0];
226	args[1] = &arg[1][0];
227	args[2] = &arg[2][0];
228	args[3] = &arg[3][0];
229	args[4] = &arg[4][0];
230	retval = 0;
231	while(fgets(line, sizeof(line), fp) != NULL) {
232	if ((p = strchr(line, '#')) != NULL)
233	*p = '\0';
234	for (p = line; isblank(*p); p++);
235	if (p == '\n' \|\| p == '\0')
236	continue;
237	i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
238	arg[2], arg[3], arg[4]);
239	if (i < 2) {
240	warnx("bad line: %s", line);
241	retval = 1;
242	continue;
243	}
244	if (set(i, args))
245	retval = 1;
246	}
247	fclose(fp);
248	return (retval);
249	}
250
251	/*
252	* Given a hostname, fills up a (static) struct sockaddr_in with
253	* the address of the host and returns a pointer to the
254	* structure.
255	*/
256	static struct sockaddr_in *
257	getaddr(char *host)
258	{
259	struct hostent *hp;
260	static struct sockaddr_in reply;
261
262	bzero(&reply, sizeof(reply));
263	reply.sin_len = sizeof(reply);
264	reply.sin_family = AF_INET;
265	reply.sin_addr.s_addr = inet_addr(host);
266	if (reply.sin_addr.s_addr == INADDR_NONE) {
267	if (!(hp = gethostbyname(host))) {
268	warnx("%s: %s", host, hstrerror(h_errno));
269	return (NULL);
270	}
271	bcopy((char )hp->h_addr, (char )&reply.sin_addr,
272	sizeof reply.sin_addr);
273	}
274	return (&reply);
275	}
276
277	/*
278	* Returns true if the type is a valid one for ARP.
279	*/
280	static int
281	valid_type(int type)
282	{
283
284	switch (type) {
285	case IFT_ETHER:
286	case IFT_FDDI:
287	case IFT_INFINIBAND:
288	case IFT_ISO88023:
289	case IFT_ISO88024:
290	case IFT_ISO88025:
291	case IFT_L2VLAN:
292	case IFT_BRIDGE:
293	return (1);
294	default:
295	return (0);
296	}
297	}
298
299	/*
300	* Set an individual arp entry
301	*/
302	static int
303	set(int argc, char **argv)
304	{
305	struct sockaddr_in *addr;
306	struct sockaddr_in dst; / what are we looking for */
307	struct sockaddr_dl *sdl;
308	struct rt_msghdr *rtm;
309	struct ether_addr *ea;
310	char host = argv[0], eaddr = argv[1];
311	struct sockaddr_dl sdl_m;
312
313	argc -= 2;
314	argv += 2;
315
316	bzero(&sdl_m, sizeof(sdl_m));
317	sdl_m.sdl_len = sizeof(sdl_m);
318	sdl_m.sdl_family = AF_LINK;
319
320	dst = getaddr(host);
321	if (dst == NULL)
322	return (1);
323	doing_proxy = flags = expire_time = 0;
324	while (argc-- > 0) {
325	if (strncmp(argv[0], "temp", 4) == 0) {
326	struct timespec tp;
327	int max_age;
328	size_t len = sizeof(max_age);
329
330	clock_gettime(CLOCK_MONOTONIC, &tp);
331	if (sysctlbyname("net.link.ether.inet.max_age",
332	&max_age, &len, NULL, 0) != 0)
333	err(1, "sysctlbyname");
334	expire_time = tp.tv_sec + max_age;
335	} else if (strncmp(argv[0], "pub", 3) == 0) {
336	flags \|= RTF_ANNOUNCE;
337	doing_proxy = 1;
338	if (argc && strncmp(argv[1], "only", 3) == 0) {
339	/*
340	* Compatibility: in pre FreeBSD 8 times
341	* the "only" keyword used to mean that
342	* an ARP entry should be announced, but
343	* not installed into routing table.
344	*/
345	argc--; argv++;
346	}
347	} else if (strncmp(argv[0], "blackhole", 9) == 0) {
348	if (flags & RTF_REJECT) {
349	printf("Choose one of blackhole or reject, not both.\n");
350	}
351	flags \|= RTF_BLACKHOLE;
352	} else if (strncmp(argv[0], "reject", 6) == 0) {
353	if (flags & RTF_BLACKHOLE) {
354	printf("Choose one of blackhole or reject, not both.\n");
355	}
356	flags \|= RTF_REJECT;
357	} else if (strncmp(argv[0], "trail", 5) == 0) {
358	/* XXX deprecated and undocumented feature */
359	printf("%s: Sending trailers is no longer supported\n",
360	host);
361	}
362	argv++;
363	}
364	ea = (struct ether_addr *)LLADDR(&sdl_m);
365	if (doing_proxy && !strcmp(eaddr, "auto")) {
366	if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
367	printf("no interface found for %s\n",
368	inet_ntoa(dst->sin_addr));
369	return (1);
370	}
371	sdl_m.sdl_alen = ETHER_ADDR_LEN;
372	} else {
373	struct ether_addr *ea1 = ether_aton(eaddr);
374
375	if (ea1 == NULL) {
376	warnx("invalid Ethernet address '%s'", eaddr);
377	return (1);
378	} else {
379	ea = ea1;
380	sdl_m.sdl_alen = ETHER_ADDR_LEN;
381	}
382	}
383
384	/*
385	* In the case a proxy-arp entry is being added for
386	* a remote end point, the RTF_ANNOUNCE flag in the
387	* RTM_GET command is an indication to the kernel
388	* routing code that the interface associated with
389	* the prefix route covering the local end of the
390	* PPP link should be returned, on which ARP applies.
391	*/
392	rtm = rtmsg(RTM_GET, dst, &sdl_m);
393	if (rtm == NULL) {
394	warn("%s", host);
395	return (1);
396	}
397	addr = (struct sockaddr_in *)(rtm + 1);
398	sdl = (struct sockaddr_dl )(SA_SIZE(addr) + (char )addr);
399
400	if ((sdl->sdl_family != AF_LINK) \|\|
401	(rtm->rtm_flags & RTF_GATEWAY) \|\|
402	!valid_type(sdl->sdl_type)) {
403	printf("cannot intuit interface index and type for %s\n", host);
404	return (1);
405	}
406	sdl_m.sdl_type = sdl->sdl_type;
407	sdl_m.sdl_index = sdl->sdl_index;
408	return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
409	}
410
411	/*
412	* Display an individual arp entry
413	*/
414	static int
415	get(char *host)
416	{
417	struct sockaddr_in *addr;
418
419	addr = getaddr(host);
420	if (addr == NULL)
421	return (1);
422	if (0 == search(addr->sin_addr.s_addr, print_entry)) {
423	printf("%s (%s) -- no entry",
424	host, inet_ntoa(addr->sin_addr));
425	if (rifname)
426	printf(" on %s", rifname);
427	printf("\n");
428	return (1);
429	}
430	return (0);
431	}
432
433	/*
434	* Delete an arp entry
435	*/
436	static int
437	delete(char *host)
438	{
439	struct sockaddr_in addr, dst;
440	struct rt_msghdr *rtm;
441	struct sockaddr_dl *sdl;
442	struct sockaddr_dl sdl_m;
443
444	dst = getaddr(host);
445	if (dst == NULL)
446	return (1);
447
448	/*
449	* Perform a regular entry delete first.
450	*/
451	flags &= ~RTF_ANNOUNCE;
452
453	/*
454	* setup the data structure to notify the kernel
455	* it is the ARP entry the RTM_GET is interested
456	* in
457	*/
458	bzero(&sdl_m, sizeof(sdl_m));
459	sdl_m.sdl_len = sizeof(sdl_m);
460	sdl_m.sdl_family = AF_LINK;
461
462	for (;;) { /* try twice */
463	rtm = rtmsg(RTM_GET, dst, &sdl_m);
464	if (rtm == NULL) {
465	warn("%s", host);
466	return (1);
467	}
468	addr = (struct sockaddr_in *)(rtm + 1);
469	sdl = (struct sockaddr_dl )(SA_SIZE(addr) + (char )addr);
470
471	/*
472	* With the new L2/L3 restructure, the route
473	* returned is a prefix route. The important
474	* piece of information from the previous
475	* RTM_GET is the interface index. In the
476	* case of ECMP, the kernel will traverse
477	* the route group for the given entry.
478	*/
479	if (sdl->sdl_family == AF_LINK &&
480	!(rtm->rtm_flags & RTF_GATEWAY) &&
481	valid_type(sdl->sdl_type) ) {
482	addr->sin_addr.s_addr = dst->sin_addr.s_addr;
483	break;
484	}
485
486	/*
487	* Regualar entry delete failed, now check if there
488	* is a proxy-arp entry to remove.
489	*/
490	if (flags & RTF_ANNOUNCE) {
491	fprintf(stderr, "delete: cannot locate %s\n",host);
492	return (1);
493	}
494
495	flags \|= RTF_ANNOUNCE;
496	}
497	rtm->rtm_flags \|= RTF_LLDATA;
498	if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
499	printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
500	return (0);
501	}
502	return (1);
503	}
504
505
506	/*
507	* Search the arp table and do some action on matching entries
508	*/
509	static int
510	search(u_long addr, action_fn *action)
511	{
512	int mib[6];
513	size_t needed;
514	char lim, buf, *next;
515	struct rt_msghdr *rtm;
516	struct sockaddr_in *sin2;
517	struct sockaddr_dl *sdl;
518	char ifname[IF_NAMESIZE];
519	int st, found_entry = 0;
520
521	mib[0] = CTL_NET;
522	mib[1] = PF_ROUTE;
523	mib[2] = 0;
524	mib[3] = AF_INET;
525	mib[4] = NET_RT_FLAGS;
526	#ifdef RTF_LLINFO
527	mib[5] = RTF_LLINFO;
528	#else
529	mib[5] = 0;
530	#endif
531	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
532	err(1, "route-sysctl-estimate");
533	if (needed == 0) /* empty table */
534	return 0;
535	buf = NULL;
536	for (;;) {
537	buf = reallocf(buf, needed);
538	if (buf == NULL)
539	errx(1, "could not reallocate memory");
540	st = sysctl(mib, 6, buf, &needed, NULL, 0);
541	if (st == 0 \|\| errno != ENOMEM)
542	break;
543	needed += needed / 8;
544	}
545	if (st == -1)
546	err(1, "actual retrieval of routing table");
547	lim = buf + needed;
548	for (next = buf; next < lim; next += rtm->rtm_msglen) {
549	rtm = (struct rt_msghdr *)next;
550	sin2 = (struct sockaddr_in *)(rtm + 1);
551	sdl = (struct sockaddr_dl )((char )sin2 + SA_SIZE(sin2));
552	if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
553	strcmp(ifname, rifname))
554	continue;
555	if (addr) {
556	if (addr != sin2->sin_addr.s_addr)
557	continue;
558	found_entry = 1;
559	}
560	(*action)(sdl, sin2, rtm);
561	}
562	free(buf);
563	return (found_entry);
564	}
565
566	/*
567	* Display an arp entry
568	*/
569
570	static void
571	print_entry(struct sockaddr_dl *sdl,
572	struct sockaddr_in addr, struct rt_msghdr rtm)
573	{
574	const char *host;
575	struct hostent *hp;
576	struct iso88025_sockaddr_dl_data *trld;
577	struct if_nameindex *p;
578	int seg;
579
580	if (ifnameindex == NULL)
581	if ((ifnameindex = if_nameindex()) == NULL)
582	err(1, "cannot retrieve interface names");
583
584	if (nflag == 0)
585	hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
586	sizeof addr->sin_addr, AF_INET);
587	else
588	hp = 0;
589	if (hp)
590	host = hp->h_name;
591	else {
592	host = "?";
593	if (h_errno == TRY_AGAIN)
594	nflag = 1;
595	}
596	printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
597	if (sdl->sdl_alen) {
598	if ((sdl->sdl_type == IFT_ETHER \|\|
599	sdl->sdl_type == IFT_L2VLAN \|\|
600	sdl->sdl_type == IFT_BRIDGE) &&
601	sdl->sdl_alen == ETHER_ADDR_LEN)
602	printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
603	else {
604	int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
605
606	printf("%s", link_ntoa(sdl) + n);
607	}
608	} else
609	printf("(incomplete)");
610
611	for (p = ifnameindex; p && ifnameindex->if_index &&
612	ifnameindex->if_name; p++) {
613	if (p->if_index == sdl->sdl_index) {
614	printf(" on %s", p->if_name);
615	break;
616	}
617	}
618
619	if (rtm->rtm_rmx.rmx_expire == 0)
620	printf(" permanent");
621	else {
622	static struct timespec tp;
623	if (tp.tv_sec == 0)
624	clock_gettime(CLOCK_MONOTONIC, &tp);
625	if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
626	printf(" expires in %d seconds", (int)expire_time);
627	else
628	printf(" expired");
629	}
630	if (rtm->rtm_flags & RTF_ANNOUNCE)
631	printf(" published");
632	switch(sdl->sdl_type) {
633	case IFT_ETHER:
634	printf(" [ethernet]");
635	break;
636	case IFT_ISO88025:
637	printf(" [token-ring]");
638	trld = SDL_ISO88025(sdl);
639	if (trld->trld_rcf != 0) {
640	printf(" rt=%x", ntohs(trld->trld_rcf));
641	for (seg = 0;
642	seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
643	seg++)
644	printf(":%x", ntohs(*(trld->trld_route[seg])));
645	}
646	break;
647	case IFT_FDDI:
648	printf(" [fddi]");
649	break;
650	case IFT_ATM:
651	printf(" [atm]");
652	break;
653	case IFT_L2VLAN:
654	printf(" [vlan]");
655	break;
656	case IFT_IEEE1394:
657	printf(" [firewire]");
658	break;
659	case IFT_BRIDGE:
660	printf(" [bridge]");
661	break;
662	case IFT_INFINIBAND:
663	printf(" [infiniband]");
664	break;
665	default:
666	break;
667	}
668
669	printf("\n");
670
671	}
672
673	/*
674	* Nuke an arp entry
675	*/
676	static void
677	nuke_entry(struct sockaddr_dl *sdl __unused,
678	struct sockaddr_in addr, struct rt_msghdr rtm)
679	{
680	char ip[20];
681
682	if (rtm->rtm_flags & RTF_PINNED)
683	return;
684
685	snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
686	delete(ip);
687	}
688
689	static void
690	usage(void)
691	{
692	fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
693	"usage: arp [-n] [-i interface] hostname",
694	" arp [-n] [-i interface] -a",
695	" arp -d hostname [pub]",
696	" arp -d [-i interface] -a",
697	" arp -s hostname ether_addr [temp] [reject \| blackhole] [pub [only]]",
698	" arp -S hostname ether_addr [temp] [reject \| blackhole] [pub [only]]",
699	" arp -f filename");
700	exit(1);
701	}
702
703	static struct rt_msghdr *
704	rtmsg(int cmd, struct sockaddr_in dst, struct sockaddr_dl sdl)
705	{
706	static int seq;
707	int rlen;
708	int l;
709	struct sockaddr_in so_mask, *som = &so_mask;
710	static int s = -1;
711	static pid_t pid;
712
713	static struct {
714	struct rt_msghdr m_rtm;
715	char m_space[512];
716	} m_rtmsg;
717
718	struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
719	char *cp = m_rtmsg.m_space;
720
721	if (s < 0) { /* first time: open socket, get pid */
722	s = socket(PF_ROUTE, SOCK_RAW, 0);
723	if (s < 0)
724	err(1, "socket");
725	pid = getpid();
726	}
727	bzero(&so_mask, sizeof(so_mask));
728	so_mask.sin_len = 8;
729	so_mask.sin_addr.s_addr = 0xffffffff;
730
731	errno = 0;
732	/*
733	* XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
734	* appropriately.
735	*/
736	if (cmd == RTM_DELETE)
737	goto doit;
738	bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
739	rtm->rtm_flags = flags;
740	rtm->rtm_version = RTM_VERSION;
741
742	switch (cmd) {
743	default:
744	errx(1, "internal wrong cmd");
745	case RTM_ADD:
746	rtm->rtm_addrs \|= RTA_GATEWAY;
747	rtm->rtm_rmx.rmx_expire = expire_time;
748	rtm->rtm_inits = RTV_EXPIRE;
749	rtm->rtm_flags \|= (RTF_HOST \| RTF_STATIC \| RTF_LLDATA);
750	if (doing_proxy) {
751	rtm->rtm_addrs \|= RTA_NETMASK;
752	rtm->rtm_flags &= ~RTF_HOST;
753	}
754	/* FALLTHROUGH */
755	case RTM_GET:
756	rtm->rtm_addrs \|= RTA_DST;
757	}
758	#define NEXTADDR(w, s) \
759	do { \
760	if ((s) != NULL && rtm->rtm_addrs & (w)) { \
761	bcopy((s), cp, sizeof(*(s))); \
762	cp += SA_SIZE(s); \
763	} \
764	} while (0)
765
766	NEXTADDR(RTA_DST, dst);
767	NEXTADDR(RTA_GATEWAY, sdl);
768	NEXTADDR(RTA_NETMASK, som);
769
770	rtm->rtm_msglen = cp - (char *)&m_rtmsg;
771	doit:
772	l = rtm->rtm_msglen;
773	rtm->rtm_seq = ++seq;
774	rtm->rtm_type = cmd;
775	if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
776	if (errno != ESRCH \|\| cmd != RTM_DELETE) {
777	warn("writing to routing socket");
778	return (NULL);
779	}
780	}
781	do {
782	l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
783	} while (l > 0 && (rtm->rtm_seq != seq \|\| rtm->rtm_pid != pid));
784	if (l < 0)
785	warn("read from routing socket");
786	return (rtm);
787	}
788
789	/*
790	* get_ether_addr - get the hardware address of an interface on the
791	* the same subnet as ipaddr.
792	*/
793	#define MAX_IFS 32
794
795	static int
796	get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
797	{
798	struct ifreq ifr, ifend, *ifp;
799	in_addr_t ina, mask;
800	struct sockaddr_dl *dla;
801	struct ifreq ifreq;
802	struct ifconf ifc;
803	struct ifreq ifs[MAX_IFS];
804	int sock;
805	int retval = 0;
806
807	sock = socket(AF_INET, SOCK_DGRAM, 0);
808	if (sock < 0)
809	err(1, "socket");
810
811	ifc.ifc_len = sizeof(ifs);
812	ifc.ifc_req = ifs;
813	if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
814	warnx("ioctl(SIOCGIFCONF)");
815	goto done;
816	}
817
818	#define NEXTIFR(i) \
819	((struct ifreq )((char )&(i)->ifr_addr \
820	+ MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
821
822	/*
823	* Scan through looking for an interface with an Internet
824	* address on the same subnet as `ipaddr'.
825	*/
826	ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
827	for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
828	if (ifr->ifr_addr.sa_family != AF_INET)
829	continue;
830	strncpy(ifreq.ifr_name, ifr->ifr_name,
831	sizeof(ifreq.ifr_name));
832	ifreq.ifr_addr = ifr->ifr_addr;
833	/*
834	* Check that the interface is up,
835	* and not point-to-point or loopback.
836	*/
837	if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
838	continue;
839	if ((ifreq.ifr_flags &
840	(IFF_UP\|IFF_BROADCAST\|IFF_POINTOPOINT\|
841	IFF_LOOPBACK\|IFF_NOARP))
842	!= (IFF_UP\|IFF_BROADCAST))
843	continue;
844	/*
845	* Get its netmask and check that it's on
846	* the right subnet.
847	*/
848	if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
849	continue;
850	mask = ((struct sockaddr_in *)
851	&ifreq.ifr_addr)->sin_addr.s_addr;
852	ina = ((struct sockaddr_in *)
853	&ifr->ifr_addr)->sin_addr.s_addr;
854	if ((ipaddr & mask) == (ina & mask))
855	break; /* ok, we got it! */
856	}
857
858	if (ifr >= ifend)
859	goto done;
860
861	/*
862	* Now scan through again looking for a link-level address
863	* for this interface.
864	*/
865	ifp = ifr;
866	for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
867	if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
868	ifr->ifr_addr.sa_family == AF_LINK)
869	break;
870	if (ifr >= ifend)
871	goto done;
872	/*
873	* Found the link-level address - copy it out
874	*/
875	dla = (struct sockaddr_dl *) &ifr->ifr_addr;
876	memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
877	printf("using interface %s for proxy with address ",
878	ifp->ifr_name);
879	printf("%s\n", ether_ntoa(hwaddr));
880	retval = dla->sdl_alen;
881	done:
882	close(sock);
883	return (retval);
884	}

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