1/*-
2 * SPDX-License-Identifier: BSD-1-Clause
3 *
4 * Copyright (c) 1990, 1991, 1992, 1993, 1996
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that: (1) source code distributions
9 * retain the above copyright notice and this paragraph in its entirety, (2)
10 * distributions including binary code include the above copyright notice and
11 * this paragraph in its entirety in the documentation or other materials
12 * provided with the distribution
13 *
14 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
15 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
16 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
17 */
18
19/*
20 * rarpd - Reverse ARP Daemon
21 *
22 * Usage:	rarpd -a [-dfsv] [-t directory] [-P pidfile] [hostname]
23 *		rarpd [-dfsv] [-t directory] [-P pidfile] interface [hostname]
24 *
25 * 'hostname' is optional solely for backwards compatibility with Sun's rarpd.
26 * Currently, the argument is ignored.
27 */
28#include <sys/param.h>
29#include <sys/file.h>
30#include <sys/ioctl.h>
31#include <sys/socket.h>
32#include <sys/time.h>
33
34#include <net/bpf.h>
35#include <net/ethernet.h>
36#include <net/if.h>
37#include <net/if_types.h>
38#include <net/if_dl.h>
39#include <net/route.h>
40
41#include <netinet/in.h>
42#include <netinet/if_ether.h>
43
44#include <arpa/inet.h>
45
46#include <dirent.h>
47#include <errno.h>
48#include <ifaddrs.h>
49#include <netdb.h>
50#include <stdarg.h>
51#include <stdio.h>
52#include <string.h>
53#include <syslog.h>
54#include <stdlib.h>
55#include <unistd.h>
56#include <libutil.h>
57
58/* Cast a struct sockaddr to a struct sockaddr_in */
59#define SATOSIN(sa) ((struct sockaddr_in *)(sa))
60
61#ifndef TFTP_DIR
62#define TFTP_DIR "/tftpboot"
63#endif
64
65#define ARPSECS (20 * 60)		/* as per code in netinet/if_ether.c */
66#define REVARP_REQUEST ARPOP_REVREQUEST
67#define REVARP_REPLY ARPOP_REVREPLY
68
69/*
70 * The structure for each interface.
71 */
72struct if_info {
73	struct if_info	*ii_next;
74	int		ii_fd;			/* BPF file descriptor */
75	in_addr_t	ii_ipaddr;		/* IP address */
76	in_addr_t	ii_netmask;		/* subnet or net mask */
77	u_char		ii_eaddr[ETHER_ADDR_LEN];	/* ethernet address */
78	char		ii_ifname[IF_NAMESIZE];
79};
80
81/*
82 * The list of all interfaces that are being listened to.  rarp_loop()
83 * "selects" on the descriptors in this list.
84 */
85static struct if_info *iflist;
86
87static int verbose;		/* verbose messages */
88static const char *tftp_dir = TFTP_DIR;	/* tftp directory */
89
90static int dflag;		/* messages to stdout/stderr, not syslog(3) */
91static int sflag;		/* ignore /tftpboot */
92
93static	u_char zero[6];
94
95static char pidfile_buf[PATH_MAX];
96static char *pidfile;
97#define	RARPD_PIDFILE	"/var/run/rarpd.%s.pid"
98static struct pidfh *pidfile_fh;
99
100static int	bpf_open(void);
101static in_addr_t	choose_ipaddr(in_addr_t **, in_addr_t, in_addr_t);
102static char	*eatoa(u_char *);
103static int	expand_syslog_m(const char *fmt, char **newfmt);
104static void	init(char *);
105static void	init_one(struct ifaddrs *, char *, int);
106static char	*intoa(in_addr_t);
107static in_addr_t	ipaddrtonetmask(in_addr_t);
108static void	logmsg(int, const char *, ...) __printflike(2, 3);
109static int	rarp_bootable(in_addr_t);
110static int	rarp_check(u_char *, u_int);
111static void	rarp_loop(void);
112static int	rarp_open(char *);
113static void	rarp_process(struct if_info *, u_char *, u_int);
114static void	rarp_reply(struct if_info *, struct ether_header *,
115		in_addr_t, u_int);
116static void	update_arptab(u_char *, in_addr_t);
117static void	usage(void);
118
119int
120main(int argc, char *argv[])
121{
122	int op;
123	char *ifname, *name;
124
125	int aflag = 0;		/* listen on "all" interfaces  */
126	int fflag = 0;		/* don't fork */
127
128	if ((name = strrchr(argv[0], '/')) != NULL)
129		++name;
130	else
131		name = argv[0];
132	if (*name == '-')
133		++name;
134
135	/*
136	 * All error reporting is done through syslog, unless -d is specified
137	 */
138	openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON);
139
140	opterr = 0;
141	while ((op = getopt(argc, argv, "adfsP:t:v")) != -1)
142		switch (op) {
143		case 'a':
144			++aflag;
145			break;
146
147		case 'd':
148			++dflag;
149			break;
150
151		case 'f':
152			++fflag;
153			break;
154
155		case 's':
156			++sflag;
157			break;
158
159		case 'P':
160			strncpy(pidfile_buf, optarg, sizeof(pidfile_buf) - 1);
161			pidfile_buf[sizeof(pidfile_buf) - 1] = '\0';
162			pidfile = pidfile_buf;
163			break;
164
165		case 't':
166			tftp_dir = optarg;
167			break;
168
169		case 'v':
170			++verbose;
171			break;
172
173		default:
174			usage();
175			/* NOTREACHED */
176		}
177	argc -= optind;
178	argv += optind;
179
180	ifname = (aflag == 0) ? argv[0] : NULL;
181
182	if ((aflag && ifname) || (!aflag && ifname == NULL))
183		usage();
184
185	init(ifname);
186
187	if (!fflag) {
188		if (pidfile == NULL && ifname != NULL && aflag == 0) {
189			snprintf(pidfile_buf, sizeof(pidfile_buf) - 1,
190			    RARPD_PIDFILE, ifname);
191			pidfile_buf[sizeof(pidfile_buf) - 1] = '\0';
192			pidfile = pidfile_buf;
193		}
194		/* If pidfile == NULL, /var/run/<progname>.pid will be used. */
195		pidfile_fh = pidfile_open(pidfile, 0600, NULL);
196		if (pidfile_fh == NULL)
197			logmsg(LOG_ERR, "Cannot open or create pidfile: %s",
198			    (pidfile == NULL) ? "/var/run/rarpd.pid" : pidfile);
199		if (daemon(0,0)) {
200			logmsg(LOG_ERR, "cannot fork");
201			pidfile_remove(pidfile_fh);
202			exit(1);
203		}
204		pidfile_write(pidfile_fh);
205	}
206	rarp_loop();
207	return(0);
208}
209
210/*
211 * Add to the interface list.
212 */
213static void
214init_one(struct ifaddrs *ifa, char *target, int pass1)
215{
216	struct if_info *ii, *ii2;
217	struct sockaddr_dl *ll;
218	int family;
219
220	family = ifa->ifa_addr->sa_family;
221	switch (family) {
222	case AF_INET:
223		if (pass1)
224			/* Consider only AF_LINK during pass1. */
225			return;
226		/* FALLTHROUGH */
227	case AF_LINK:
228		if (!(ifa->ifa_flags & IFF_UP) ||
229		    (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)))
230			return;
231		break;
232	default:
233		return;
234	}
235
236	/* Don't bother going any further if not the target interface */
237	if (target != NULL && strcmp(ifa->ifa_name, target) != 0)
238		return;
239
240	/* Look for interface in list */
241	for (ii = iflist; ii != NULL; ii = ii->ii_next)
242		if (strcmp(ifa->ifa_name, ii->ii_ifname) == 0)
243			break;
244
245	if (pass1 && ii != NULL)
246		/* We've already seen that interface once. */
247		return;
248
249	/* Allocate a new one if not found */
250	if (ii == NULL) {
251		ii = (struct if_info *)malloc(sizeof(*ii));
252		if (ii == NULL) {
253			logmsg(LOG_ERR, "malloc: %m");
254			pidfile_remove(pidfile_fh);
255			exit(1);
256		}
257		bzero(ii, sizeof(*ii));
258		ii->ii_fd = -1;
259		strlcpy(ii->ii_ifname, ifa->ifa_name, sizeof(ii->ii_ifname));
260		ii->ii_next = iflist;
261		iflist = ii;
262	} else if (!pass1 && ii->ii_ipaddr != 0) {
263		/*
264		 * Second AF_INET definition for that interface: clone
265		 * the existing one, and work on that cloned one.
266		 * This must be another IP address for this interface,
267		 * so avoid killing the previous configuration.
268		 */
269		ii2 = (struct if_info *)malloc(sizeof(*ii2));
270		if (ii2 == NULL) {
271			logmsg(LOG_ERR, "malloc: %m");
272			pidfile_remove(pidfile_fh);
273			exit(1);
274		}
275		memcpy(ii2, ii, sizeof(*ii2));
276		ii2->ii_fd = -1;
277		ii2->ii_next = iflist;
278		iflist = ii2;
279
280		ii = ii2;
281	}
282
283	switch (family) {
284	case AF_INET:
285		ii->ii_ipaddr = SATOSIN(ifa->ifa_addr)->sin_addr.s_addr;
286		ii->ii_netmask = SATOSIN(ifa->ifa_netmask)->sin_addr.s_addr;
287		if (ii->ii_netmask == 0)
288			ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr);
289		if (ii->ii_fd < 0)
290			ii->ii_fd = rarp_open(ii->ii_ifname);
291		break;
292
293	case AF_LINK:
294		ll = (struct sockaddr_dl *)ifa->ifa_addr;
295		switch (ll->sdl_type) {
296		case IFT_ETHER:
297		case IFT_L2VLAN:
298			bcopy(LLADDR(ll), ii->ii_eaddr, 6);
299		}
300		break;
301	}
302}
303
304/*
305 * Initialize all "candidate" interfaces that are in the system
306 * configuration list.  A "candidate" is up, not loopback and not
307 * point to point.
308 */
309static void
310init(char *target)
311{
312	struct if_info *ii, *nii, *lii;
313	struct ifaddrs *ifhead, *ifa;
314	int error;
315
316	error = getifaddrs(&ifhead);
317	if (error) {
318		logmsg(LOG_ERR, "getifaddrs: %m");
319		pidfile_remove(pidfile_fh);
320		exit(1);
321	}
322	/*
323	 * We make two passes over the list we have got.  In the first
324	 * one, we only collect AF_LINK interfaces, and initialize our
325	 * list of interfaces from them.  In the second pass, we
326	 * collect the actual IP addresses from the AF_INET
327	 * interfaces, and allow for the same interface name to appear
328	 * multiple times (in case of more than one IP address).
329	 */
330	for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
331		init_one(ifa, target, 1);
332	for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
333		init_one(ifa, target, 0);
334	freeifaddrs(ifhead);
335
336	/* Throw away incomplete interfaces */
337	lii = NULL;
338	for (ii = iflist; ii != NULL; ii = nii) {
339		nii = ii->ii_next;
340		if (ii->ii_ipaddr == 0 ||
341		    bcmp(ii->ii_eaddr, zero, 6) == 0) {
342			if (lii == NULL)
343				iflist = nii;
344			else
345				lii->ii_next = nii;
346			if (ii->ii_fd >= 0)
347				close(ii->ii_fd);
348			free(ii);
349			continue;
350		}
351		lii = ii;
352	}
353
354	/* Verbose stuff */
355	if (verbose)
356		for (ii = iflist; ii != NULL; ii = ii->ii_next)
357			logmsg(LOG_DEBUG, "%s %s 0x%08x %s",
358			    ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)),
359			    (in_addr_t)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr));
360}
361
362static void
363usage(void)
364{
365
366	(void)fprintf(stderr, "%s\n%s\n",
367	    "usage: rarpd -a [-dfsv] [-t directory] [-P pidfile]",
368	    "       rarpd [-dfsv] [-t directory] [-P pidfile] interface");
369	exit(1);
370}
371
372static int
373bpf_open(void)
374{
375	int fd;
376	int n = 0;
377	char device[sizeof "/dev/bpf000"];
378
379	/*
380	 * Go through all the minors and find one that isn't in use.
381	 */
382	do {
383		(void)sprintf(device, "/dev/bpf%d", n++);
384		fd = open(device, O_RDWR);
385	} while ((fd == -1) && (errno == EBUSY));
386
387	if (fd == -1) {
388		logmsg(LOG_ERR, "%s: %m", device);
389		pidfile_remove(pidfile_fh);
390		exit(1);
391	}
392	return fd;
393}
394
395/*
396 * Open a BPF file and attach it to the interface named 'device'.
397 * Set immediate mode, and set a filter that accepts only RARP requests.
398 */
399static int
400rarp_open(char *device)
401{
402	int fd;
403	struct ifreq ifr;
404	u_int dlt;
405	int immediate;
406
407	static struct bpf_insn insns[] = {
408		BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12),
409		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3),
410		BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20),
411		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1),
412		BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) +
413			 sizeof(struct ether_header)),
414		BPF_STMT(BPF_RET|BPF_K, 0),
415	};
416	static struct bpf_program filter = {
417		sizeof insns / sizeof(insns[0]),
418		insns
419	};
420
421	fd = bpf_open();
422	/*
423	 * Set immediate mode so packets are processed as they arrive.
424	 */
425	immediate = 1;
426	if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) {
427		logmsg(LOG_ERR, "BIOCIMMEDIATE: %m");
428		goto rarp_open_err;
429	}
430	strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
431	if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) {
432		logmsg(LOG_ERR, "BIOCSETIF: %m");
433		goto rarp_open_err;
434	}
435	/*
436	 * Check that the data link layer is an Ethernet; this code won't
437	 * work with anything else.
438	 */
439	if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) {
440		logmsg(LOG_ERR, "BIOCGDLT: %m");
441		goto rarp_open_err;
442	}
443	if (dlt != DLT_EN10MB) {
444		logmsg(LOG_ERR, "%s is not an ethernet", device);
445		goto rarp_open_err;
446	}
447	/*
448	 * Set filter program.
449	 */
450	if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) {
451		logmsg(LOG_ERR, "BIOCSETF: %m");
452		goto rarp_open_err;
453	}
454	return fd;
455
456rarp_open_err:
457	pidfile_remove(pidfile_fh);
458	exit(1);
459}
460
461/*
462 * Perform various sanity checks on the RARP request packet.  Return
463 * false on failure and log the reason.
464 */
465static int
466rarp_check(u_char *p, u_int len)
467{
468	struct ether_header *ep = (struct ether_header *)p;
469	struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep));
470
471	if (len < sizeof(*ep) + sizeof(*ap)) {
472		logmsg(LOG_ERR, "truncated request, got %u, expected %lu",
473				len, (u_long)(sizeof(*ep) + sizeof(*ap)));
474		return 0;
475	}
476	/*
477	 * XXX This test might be better off broken out...
478	 */
479	if (ntohs(ep->ether_type) != ETHERTYPE_REVARP ||
480	    ntohs(ap->arp_hrd) != ARPHRD_ETHER ||
481	    ntohs(ap->arp_op) != REVARP_REQUEST ||
482	    ntohs(ap->arp_pro) != ETHERTYPE_IP ||
483	    ap->arp_hln != 6 || ap->arp_pln != 4) {
484		logmsg(LOG_DEBUG, "request fails sanity check");
485		return 0;
486	}
487	if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) {
488		logmsg(LOG_DEBUG, "ether/arp sender address mismatch");
489		return 0;
490	}
491	if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) {
492		logmsg(LOG_DEBUG, "ether/arp target address mismatch");
493		return 0;
494	}
495	return 1;
496}
497
498/*
499 * Loop indefinitely listening for RARP requests on the
500 * interfaces in 'iflist'.
501 */
502static void
503rarp_loop(void)
504{
505	u_char *buf, *bp, *ep;
506	int cc, fd;
507	fd_set fds, listeners;
508	int bufsize, maxfd = 0;
509	struct if_info *ii;
510
511	if (iflist == NULL) {
512		logmsg(LOG_ERR, "no interfaces");
513		goto rarpd_loop_err;
514	}
515	if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) {
516		logmsg(LOG_ERR, "BIOCGBLEN: %m");
517		goto rarpd_loop_err;
518	}
519	buf = malloc(bufsize);
520	if (buf == NULL) {
521		logmsg(LOG_ERR, "malloc: %m");
522		goto rarpd_loop_err;
523	}
524
525	while (1) {
526		/*
527		 * Find the highest numbered file descriptor for select().
528		 * Initialize the set of descriptors to listen to.
529		 */
530		FD_ZERO(&fds);
531		for (ii = iflist; ii != NULL; ii = ii->ii_next) {
532			FD_SET(ii->ii_fd, &fds);
533			if (ii->ii_fd > maxfd)
534				maxfd = ii->ii_fd;
535		}
536		listeners = fds;
537		if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) {
538			/* Don't choke when we get ptraced */
539			if (errno == EINTR)
540				continue;
541			logmsg(LOG_ERR, "select: %m");
542			goto rarpd_loop_err;
543		}
544		for (ii = iflist; ii != NULL; ii = ii->ii_next) {
545			fd = ii->ii_fd;
546			if (!FD_ISSET(fd, &listeners))
547				continue;
548		again:
549			cc = read(fd, (char *)buf, bufsize);
550			/* Don't choke when we get ptraced */
551			if ((cc == -1) && (errno == EINTR))
552				goto again;
553
554			/* Loop through the packet(s) */
555#define bhp ((struct bpf_hdr *)bp)
556			bp = buf;
557			ep = bp + cc;
558			while (bp < ep) {
559				u_int caplen, hdrlen;
560
561				caplen = bhp->bh_caplen;
562				hdrlen = bhp->bh_hdrlen;
563				if (rarp_check(bp + hdrlen, caplen))
564					rarp_process(ii, bp + hdrlen, caplen);
565				bp += BPF_WORDALIGN(hdrlen + caplen);
566			}
567		}
568	}
569#undef bhp
570	return;
571
572rarpd_loop_err:
573	pidfile_remove(pidfile_fh);
574	exit(1);
575}
576
577/*
578 * True if this server can boot the host whose IP address is 'addr'.
579 * This check is made by looking in the tftp directory for the
580 * configuration file.
581 */
582static int
583rarp_bootable(in_addr_t addr)
584{
585	struct dirent *dent;
586	DIR *d;
587	char ipname[9];
588	static DIR *dd = NULL;
589
590	(void)sprintf(ipname, "%08X", (in_addr_t)ntohl(addr));
591
592	/*
593	 * If directory is already open, rewind it.  Otherwise, open it.
594	 */
595	if ((d = dd) != NULL)
596		rewinddir(d);
597	else {
598		if (chdir(tftp_dir) == -1) {
599			logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir);
600			goto rarp_bootable_err;
601		}
602		d = opendir(".");
603		if (d == NULL) {
604			logmsg(LOG_ERR, "opendir: %m");
605			goto rarp_bootable_err;
606		}
607		dd = d;
608	}
609	while ((dent = readdir(d)) != NULL)
610		if (strncmp(dent->d_name, ipname, 8) == 0)
611			return 1;
612	return 0;
613
614rarp_bootable_err:
615	pidfile_remove(pidfile_fh);
616	exit(1);
617}
618
619/*
620 * Given a list of IP addresses, 'alist', return the first address that
621 * is on network 'net'; 'netmask' is a mask indicating the network portion
622 * of the address.
623 */
624static in_addr_t
625choose_ipaddr(in_addr_t **alist, in_addr_t net, in_addr_t netmask)
626{
627
628	for (; *alist; ++alist)
629		if ((**alist & netmask) == net)
630			return **alist;
631	return 0;
632}
633
634/*
635 * Answer the RARP request in 'pkt', on the interface 'ii'.  'pkt' has
636 * already been checked for validity.  The reply is overlaid on the request.
637 */
638static void
639rarp_process(struct if_info *ii, u_char *pkt, u_int len)
640{
641	struct ether_header *ep;
642	struct hostent *hp;
643	in_addr_t target_ipaddr;
644	char ename[256];
645
646	ep = (struct ether_header *)pkt;
647	/* should this be arp_tha? */
648	if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) {
649		logmsg(LOG_ERR, "cannot map %s to name",
650			eatoa(ep->ether_shost));
651		return;
652	}
653
654	if ((hp = gethostbyname(ename)) == NULL) {
655		logmsg(LOG_ERR, "cannot map %s to IP address", ename);
656		return;
657	}
658
659	/*
660	 * Choose correct address from list.
661	 */
662	if (hp->h_addrtype != AF_INET) {
663		logmsg(LOG_ERR, "cannot handle non IP addresses for %s",
664								ename);
665		return;
666	}
667	target_ipaddr = choose_ipaddr((in_addr_t **)hp->h_addr_list,
668				      ii->ii_ipaddr & ii->ii_netmask,
669				      ii->ii_netmask);
670	if (target_ipaddr == 0) {
671		logmsg(LOG_ERR, "cannot find %s on net %s",
672		       ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask)));
673		return;
674	}
675	if (sflag || rarp_bootable(target_ipaddr))
676		rarp_reply(ii, ep, target_ipaddr, len);
677	else if (verbose > 1)
678		logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)",
679		    ii->ii_ifname,
680		    eatoa(ep->ether_shost),
681		    intoa(ntohl(target_ipaddr)));
682}
683
684/*
685 * Poke the kernel arp tables with the ethernet/ip address combination
686 * given.  When processing a reply, we must do this so that the booting
687 * host (i.e. the guy running rarpd), won't try to ARP for the hardware
688 * address of the guy being booted (he cannot answer the ARP).
689 */
690static struct sockaddr_in sin_inarp = {
691	sizeof(struct sockaddr_in), AF_INET, 0,
692	{0},
693	{0},
694};
695
696static struct sockaddr_dl sin_dl = {
697	sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
698	0, ""
699};
700
701static struct {
702	struct rt_msghdr rthdr;
703	char rtspace[512];
704} rtmsg;
705
706static void
707update_arptab(u_char *ep, in_addr_t ipaddr)
708{
709	struct timespec tp;
710	int cc;
711	struct sockaddr_in *ar, *ar2;
712	struct sockaddr_dl *ll, *ll2;
713	struct rt_msghdr *rt;
714	int xtype, xindex;
715	static pid_t pid;
716	int r;
717	static int seq;
718
719	r = socket(PF_ROUTE, SOCK_RAW, 0);
720	if (r == -1) {
721		logmsg(LOG_ERR, "raw route socket: %m");
722		pidfile_remove(pidfile_fh);
723		exit(1);
724	}
725	pid = getpid();
726
727	ar = &sin_inarp;
728	ar->sin_addr.s_addr = ipaddr;
729	ll = &sin_dl;
730	bcopy(ep, LLADDR(ll), 6);
731
732	/* Get the type and interface index */
733	rt = &rtmsg.rthdr;
734	bzero(&rtmsg, sizeof(rtmsg));
735	rt->rtm_version = RTM_VERSION;
736	rt->rtm_addrs = RTA_DST;
737	rt->rtm_type = RTM_GET;
738	rt->rtm_seq = ++seq;
739	ar2 = (struct sockaddr_in *)rtmsg.rtspace;
740	bcopy(ar, ar2, sizeof(*ar));
741	rt->rtm_msglen = sizeof(*rt) + sizeof(*ar);
742	errno = 0;
743	if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) {
744		logmsg(LOG_ERR, "rtmsg get write: %m");
745		close(r);
746		return;
747	}
748	do {
749		cc = read(r, rt, sizeof(rtmsg));
750	} while (cc > 0 && (rt->rtm_type != RTM_GET || rt->rtm_seq != seq ||
751	    rt->rtm_pid != pid));
752	if (cc == -1) {
753		logmsg(LOG_ERR, "rtmsg get read: %m");
754		close(r);
755		return;
756	}
757	ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len);
758	if (ll2->sdl_family != AF_LINK) {
759		/*
760		 * XXX I think this means the ip address is not on a
761		 * directly connected network (the family is AF_INET in
762		 * this case).
763		 */
764		logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08X?\n",
765		    ll2->sdl_family, ipaddr);
766		close(r);
767		return;
768	}
769	xtype = ll2->sdl_type;
770	xindex = ll2->sdl_index;
771
772	/* Set the new arp entry */
773	bzero(rt, sizeof(rtmsg));
774	rt->rtm_version = RTM_VERSION;
775	rt->rtm_addrs = RTA_DST | RTA_GATEWAY;
776	rt->rtm_inits = RTV_EXPIRE;
777	clock_gettime(CLOCK_MONOTONIC, &tp);
778	rt->rtm_rmx.rmx_expire = tp.tv_sec + ARPSECS;
779	rt->rtm_flags = RTF_HOST | RTF_STATIC;
780	rt->rtm_type = RTM_ADD;
781	rt->rtm_seq = ++seq;
782
783	bcopy(ar, ar2, sizeof(*ar));
784
785	ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2));
786	bcopy(ll, ll2, sizeof(*ll));
787	ll2->sdl_type = xtype;
788	ll2->sdl_index = xindex;
789
790	rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2);
791	errno = 0;
792	if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) {
793		logmsg(LOG_ERR, "rtmsg add write: %m");
794		close(r);
795		return;
796	}
797	do {
798		cc = read(r, rt, sizeof(rtmsg));
799	} while (cc > 0 && (rt->rtm_type != RTM_ADD || rt->rtm_seq != seq ||
800	    rt->rtm_pid != pid));
801	close(r);
802	if (cc == -1) {
803		logmsg(LOG_ERR, "rtmsg add read: %m");
804		return;
805	}
806}
807
808/*
809 * Build a reverse ARP packet and sent it out on the interface.
810 * 'ep' points to a valid REVARP_REQUEST.  The REVARP_REPLY is built
811 * on top of the request, then written to the network.
812 *
813 * RFC 903 defines the ether_arp fields as follows.  The following comments
814 * are taken (more or less) straight from this document.
815 *
816 * REVARP_REQUEST
817 *
818 * arp_sha is the hardware address of the sender of the packet.
819 * arp_spa is undefined.
820 * arp_tha is the 'target' hardware address.
821 *   In the case where the sender wishes to determine his own
822 *   protocol address, this, like arp_sha, will be the hardware
823 *   address of the sender.
824 * arp_tpa is undefined.
825 *
826 * REVARP_REPLY
827 *
828 * arp_sha is the hardware address of the responder (the sender of the
829 *   reply packet).
830 * arp_spa is the protocol address of the responder (see the note below).
831 * arp_tha is the hardware address of the target, and should be the same as
832 *   that which was given in the request.
833 * arp_tpa is the protocol address of the target, that is, the desired address.
834 *
835 * Note that the requirement that arp_spa be filled in with the responder's
836 * protocol is purely for convenience.  For instance, if a system were to use
837 * both ARP and RARP, then the inclusion of the valid protocol-hardware
838 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent
839 * ARP request.
840 */
841static void
842rarp_reply(struct if_info *ii, struct ether_header *ep, in_addr_t ipaddr,
843		u_int len)
844{
845	u_int n;
846	struct ether_arp *ap = (struct ether_arp *)(ep + 1);
847
848	update_arptab((u_char *)&ap->arp_sha, ipaddr);
849
850	/*
851	 * Build the rarp reply by modifying the rarp request in place.
852	 */
853	ap->arp_op = htons(REVARP_REPLY);
854
855#ifdef BROKEN_BPF
856	ep->ether_type = ETHERTYPE_REVARP;
857#endif
858	bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6);
859	bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6);
860	bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6);
861
862	bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4);
863	/* Target hardware is unchanged. */
864	bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4);
865
866	/* Zero possible garbage after packet. */
867	bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)),
868			len - (sizeof(*ep) + sizeof(*ap)));
869	n = write(ii->ii_fd, (char *)ep, len);
870	if (n != len)
871		logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len);
872	if (verbose)
873		logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname,
874		    eatoa(ap->arp_tha),
875		    intoa(ntohl(ipaddr)));
876}
877
878/*
879 * Get the netmask of an IP address.  This routine is used if
880 * SIOCGIFNETMASK doesn't work.
881 */
882static in_addr_t
883ipaddrtonetmask(in_addr_t addr)
884{
885
886	addr = ntohl(addr);
887	if (IN_CLASSA(addr))
888		return htonl(IN_CLASSA_NET);
889	if (IN_CLASSB(addr))
890		return htonl(IN_CLASSB_NET);
891	if (IN_CLASSC(addr))
892		return htonl(IN_CLASSC_NET);
893	logmsg(LOG_DEBUG, "unknown IP address class: %08X", addr);
894	return htonl(0xffffffff);
895}
896
897/*
898 * A faster replacement for inet_ntoa().
899 */
900static char *
901intoa(in_addr_t addr)
902{
903	char *cp;
904	u_int byte;
905	int n;
906	static char buf[sizeof(".xxx.xxx.xxx.xxx")];
907
908	cp = &buf[sizeof buf];
909	*--cp = '\0';
910
911	n = 4;
912	do {
913		byte = addr & 0xff;
914		*--cp = byte % 10 + '0';
915		byte /= 10;
916		if (byte > 0) {
917			*--cp = byte % 10 + '0';
918			byte /= 10;
919			if (byte > 0)
920				*--cp = byte + '0';
921		}
922		*--cp = '.';
923		addr >>= 8;
924	} while (--n > 0);
925
926	return cp + 1;
927}
928
929static char *
930eatoa(u_char *ea)
931{
932	static char buf[sizeof("xx:xx:xx:xx:xx:xx")];
933
934	(void)sprintf(buf, "%x:%x:%x:%x:%x:%x",
935	    ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]);
936	return (buf);
937}
938
939static void
940logmsg(int pri, const char *fmt, ...)
941{
942	va_list v;
943	FILE *fp;
944	char *newfmt;
945
946	va_start(v, fmt);
947	if (dflag) {
948		if (pri == LOG_ERR)
949			fp = stderr;
950		else
951			fp = stdout;
952		if (expand_syslog_m(fmt, &newfmt) == -1) {
953			vfprintf(fp, fmt, v);
954		} else {
955			vfprintf(fp, newfmt, v);
956			free(newfmt);
957		}
958		fputs("\n", fp);
959		fflush(fp);
960	} else {
961		vsyslog(pri, fmt, v);
962	}
963	va_end(v);
964}
965
966static int
967expand_syslog_m(const char *fmt, char **newfmt) {
968	const char *str, *m;
969	char *p, *np;
970
971	p = strdup("");
972	str = fmt;
973	while ((m = strstr(str, "%m")) != NULL) {
974		asprintf(&np, "%s%.*s%s", p, (int)(m - str),
975		    str, strerror(errno));
976		free(p);
977		if (np == NULL) {
978			errno = ENOMEM;
979			return (-1);
980		}
981		p = np;
982		str = m + 2;
983	}
984
985	if (*str != '\0') {
986		asprintf(&np, "%s%s", p, str);
987		free(p);
988		if (np == NULL) {
989			errno = ENOMEM;
990			return (-1);
991		}
992		p = np;
993	}
994
995	*newfmt = p;
996	return (0);
997}
998