1/*
2 * Copyright (c) 1990, 1991, 1992, 1993, 1996
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution
11 *
12 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
13 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
14 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
15 */
16
17#if 0
18#ifndef lint
19static const char copyright[] =
20"@(#) Copyright (c) 1990, 1991, 1992, 1993, 1996\n\
21The Regents of the University of California. All rights reserved.\n";
22#endif /* not lint */
23#endif
24#include <sys/cdefs.h>
25__FBSDID("$FreeBSD: head/usr.sbin/rarpd/rarpd.c 238282 2012-07-09 08:11:16Z hrs $");
26
27/*
28 * rarpd - Reverse ARP Daemon
29 *
30 * Usage: rarpd -a [-dfsv] [-t directory] [-P pidfile] [hostname]
31 * rarpd [-dfsv] [-t directory] [-P pidfile] interface [hostname]
32 *
33 * 'hostname' is optional solely for backwards compatibility with Sun's rarpd.
34 * Currently, the argument is ignored.
35 */
36#include <sys/param.h>
37#include <sys/file.h>
38#include <sys/ioctl.h>
39#include <sys/socket.h>
40#include <sys/time.h>
41
42#include <net/bpf.h>
43#include <net/ethernet.h>
44#include <net/if.h>
45#include <net/if_types.h>
46#include <net/if_dl.h>
47#include <net/route.h>
48
49#include <netinet/in.h>
50#include <netinet/if_ether.h>
51
52#include <arpa/inet.h>
53
54#include <dirent.h>
55#include <errno.h>
56#include <ifaddrs.h>
57#include <netdb.h>
58#include <stdarg.h>
59#include <stdio.h>
60#include <string.h>
61#include <syslog.h>
62#include <stdlib.h>
63#include <unistd.h>
64#include <libutil.h>
65
66/* Cast a struct sockaddr to a struct sockaddr_in */
67#define SATOSIN(sa) ((struct sockaddr_in *)(sa))
68
69#ifndef TFTP_DIR
70#define TFTP_DIR "/tftpboot"
71#endif
72
73#define ARPSECS (20 * 60) /* as per code in netinet/if_ether.c */
74#define REVARP_REQUEST ARPOP_REVREQUEST
75#define REVARP_REPLY ARPOP_REVREPLY
76
77/*
78 * The structure for each interface.
79 */
80struct if_info {
81 struct if_info *ii_next;
82 int ii_fd; /* BPF file descriptor */
83 in_addr_t ii_ipaddr; /* IP address */
84 in_addr_t ii_netmask; /* subnet or net mask */
85 u_char ii_eaddr[ETHER_ADDR_LEN]; /* ethernet address */
86 char ii_ifname[IF_NAMESIZE];
87};
88
89/*
90 * The list of all interfaces that are being listened to. rarp_loop()
91 * "selects" on the descriptors in this list.
92 */
93struct if_info *iflist;
94
95int verbose; /* verbose messages */
96const char *tftp_dir = TFTP_DIR; /* tftp directory */
97
98int dflag; /* messages to stdout/stderr, not syslog(3) */
99int sflag; /* ignore /tftpboot */
100
101static u_char zero[6];
102
103static char pidfile_buf[PATH_MAX];
104static char *pidfile;
105#define RARPD_PIDFILE "/var/run/rarpd.%s.pid"
106static struct pidfh *pidfile_fh;
107
108static int bpf_open(void);
109static in_addr_t choose_ipaddr(in_addr_t **, in_addr_t, in_addr_t);
110static char *eatoa(u_char *);
111static int expand_syslog_m(const char *fmt, char **newfmt);
112static void init(char *);
113static void init_one(struct ifaddrs *, char *, int);
114static char *intoa(in_addr_t);
115static in_addr_t ipaddrtonetmask(in_addr_t);
116static void logmsg(int, const char *, ...) __printflike(2, 3);
117static int rarp_bootable(in_addr_t);
118static int rarp_check(u_char *, u_int);
119static void rarp_loop(void);
120static int rarp_open(char *);
121static void rarp_process(struct if_info *, u_char *, u_int);
122static void rarp_reply(struct if_info *, struct ether_header *,
123 in_addr_t, u_int);
124static void update_arptab(u_char *, in_addr_t);
125static void usage(void);
126
127int
128main(int argc, char *argv[])
129{
130 int op;
131 char *ifname, *name;
132
133 int aflag = 0; /* listen on "all" interfaces */
134 int fflag = 0; /* don't fork */
135
136 if ((name = strrchr(argv[0], '/')) != NULL)
137 ++name;
138 else
139 name = argv[0];
140 if (*name == '-')
141 ++name;
142
143 /*
144 * All error reporting is done through syslog, unless -d is specified
145 */
146 openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON);
147
148 opterr = 0;
149 while ((op = getopt(argc, argv, "adfsP:t:v")) != -1)
150 switch (op) {
151 case 'a':
152 ++aflag;
153 break;
154
155 case 'd':
156 ++dflag;
157 break;
158
159 case 'f':
160 ++fflag;
161 break;
162
163 case 's':
164 ++sflag;
165 break;
166
167 case 'P':
168 strncpy(pidfile_buf, optarg, sizeof(pidfile_buf) - 1);
169 pidfile_buf[sizeof(pidfile_buf) - 1] = '\0';
170 pidfile = pidfile_buf;
171 break;
172
173 case 't':
174 tftp_dir = optarg;
175 break;
176
177 case 'v':
178 ++verbose;
179 break;
180
181 default:
182 usage();
183 /* NOTREACHED */
184 }
185 argc -= optind;
186 argv += optind;
187
188 ifname = (aflag == 0) ? argv[0] : NULL;
189
190 if ((aflag && ifname) || (!aflag && ifname == NULL))
191 usage();
192
193 init(ifname);
194
195 if (!fflag) {
196 if (pidfile == NULL && ifname != NULL && aflag == 0) {
197 snprintf(pidfile_buf, sizeof(pidfile_buf) - 1,
198 RARPD_PIDFILE, ifname);
199 pidfile_buf[sizeof(pidfile_buf) - 1] = '\0';
200 pidfile = pidfile_buf;
201 }
202 /* If pidfile == NULL, /var/run/<progname>.pid will be used. */
203 pidfile_fh = pidfile_open(pidfile, 0600, NULL);
204 if (pidfile_fh == NULL)
205 logmsg(LOG_ERR, "Cannot open or create pidfile: %s",
206 (pidfile == NULL) ? "/var/run/rarpd.pid" : pidfile);
207 if (daemon(0,0)) {
208 logmsg(LOG_ERR, "cannot fork");
209 pidfile_remove(pidfile_fh);
210 exit(1);
211 }
212 pidfile_write(pidfile_fh);
213 }
214 rarp_loop();
215 return(0);
216}
217
218/*
219 * Add to the interface list.
220 */
221static void
222init_one(struct ifaddrs *ifa, char *target, int pass1)
223{
224 struct if_info *ii, *ii2;
225 struct sockaddr_dl *ll;
226 int family;
227
228 family = ifa->ifa_addr->sa_family;
229 switch (family) {
230 case AF_INET:
231 if (pass1)
232 /* Consider only AF_LINK during pass1. */
233 return;
234 /* FALLTHROUGH */
235 case AF_LINK:
236 if (!(ifa->ifa_flags & IFF_UP) ||
237 (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)))
238 return;
239 break;
240 default:
241 return;
242 }
243
244 /* Don't bother going any further if not the target interface */
245 if (target != NULL && strcmp(ifa->ifa_name, target) != 0)
246 return;
247
248 /* Look for interface in list */
249 for (ii = iflist; ii != NULL; ii = ii->ii_next)
250 if (strcmp(ifa->ifa_name, ii->ii_ifname) == 0)
251 break;
252
253 if (pass1 && ii != NULL)
254 /* We've already seen that interface once. */
255 return;
256
257 /* Allocate a new one if not found */
258 if (ii == NULL) {
259 ii = (struct if_info *)malloc(sizeof(*ii));
260 if (ii == NULL) {
261 logmsg(LOG_ERR, "malloc: %m");
262 pidfile_remove(pidfile_fh);
263 exit(1);
264 }
265 bzero(ii, sizeof(*ii));
266 ii->ii_fd = -1;
267 strlcpy(ii->ii_ifname, ifa->ifa_name, sizeof(ii->ii_ifname));
268 ii->ii_next = iflist;
269 iflist = ii;
270 } else if (!pass1 && ii->ii_ipaddr != 0) {
271 /*
272 * Second AF_INET definition for that interface: clone
273 * the existing one, and work on that cloned one.
274 * This must be another IP address for this interface,
275 * so avoid killing the previous configuration.
276 */
277 ii2 = (struct if_info *)malloc(sizeof(*ii2));
278 if (ii2 == NULL) {
279 logmsg(LOG_ERR, "malloc: %m");
280 pidfile_remove(pidfile_fh);
281 exit(1);
282 }
283 memcpy(ii2, ii, sizeof(*ii2));
284 ii2->ii_fd = -1;
285 ii2->ii_next = iflist;
286 iflist = ii2;
287
288 ii = ii2;
289 }
290
291 switch (family) {
292 case AF_INET:
293 ii->ii_ipaddr = SATOSIN(ifa->ifa_addr)->sin_addr.s_addr;
294 ii->ii_netmask = SATOSIN(ifa->ifa_netmask)->sin_addr.s_addr;
295 if (ii->ii_netmask == 0)
296 ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr);
297 if (ii->ii_fd < 0)
298 ii->ii_fd = rarp_open(ii->ii_ifname);
299 break;
300
301 case AF_LINK:
302 ll = (struct sockaddr_dl *)ifa->ifa_addr;
303 switch (ll->sdl_type) {
304 case IFT_ETHER:
305 case IFT_L2VLAN:
306 bcopy(LLADDR(ll), ii->ii_eaddr, 6);
307 }
308 break;
309 }
310}
311/*
312 * Initialize all "candidate" interfaces that are in the system
313 * configuration list. A "candidate" is up, not loopback and not
314 * point to point.
315 */
316static void
317init(char *target)
318{
319 struct if_info *ii, *nii, *lii;
320 struct ifaddrs *ifhead, *ifa;
321 int error;
322
323 error = getifaddrs(&ifhead);
324 if (error) {
325 logmsg(LOG_ERR, "getifaddrs: %m");
326 pidfile_remove(pidfile_fh);
327 exit(1);
328 }
329 /*
330 * We make two passes over the list we have got. In the first
331 * one, we only collect AF_LINK interfaces, and initialize our
332 * list of interfaces from them. In the second pass, we
333 * collect the actual IP addresses from the AF_INET
334 * interfaces, and allow for the same interface name to appear
335 * multiple times (in case of more than one IP address).
336 */
337 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
338 init_one(ifa, target, 1);
339 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
340 init_one(ifa, target, 0);
341 freeifaddrs(ifhead);
342
343 /* Throw away incomplete interfaces */
344 lii = NULL;
345 for (ii = iflist; ii != NULL; ii = nii) {
346 nii = ii->ii_next;
347 if (ii->ii_ipaddr == 0 ||
348 bcmp(ii->ii_eaddr, zero, 6) == 0) {
349 if (lii == NULL)
350 iflist = nii;
351 else
352 lii->ii_next = nii;
353 if (ii->ii_fd >= 0)
354 close(ii->ii_fd);
355 free(ii);
356 continue;
357 }
358 lii = ii;
359 }
360
361 /* Verbose stuff */
362 if (verbose)
363 for (ii = iflist; ii != NULL; ii = ii->ii_next)
364 logmsg(LOG_DEBUG, "%s %s 0x%08x %s",
365 ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)),
366 (in_addr_t)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr));
367}
368
369static void
370usage(void)
371{
372 (void)fprintf(stderr, "%s\n%s\n",
373 "usage: rarpd -a [-dfsv] [-t directory] [-P pidfile]",
374 " rarpd [-dfsv] [-t directory] [-P pidfile] interface");
375 exit(1);
376}
377
378static int
379bpf_open(void)
380{
381 int fd;
382 int n = 0;
383 char device[sizeof "/dev/bpf000"];
384
385 /*
386 * Go through all the minors and find one that isn't in use.
387 */
388 do {
389 (void)sprintf(device, "/dev/bpf%d", n++);
390 fd = open(device, O_RDWR);
391 } while ((fd == -1) && (errno == EBUSY));
392
393 if (fd == -1) {
394 logmsg(LOG_ERR, "%s: %m", device);
395 pidfile_remove(pidfile_fh);
396 exit(1);
397 }
398 return fd;
399}
400
401/*
402 * Open a BPF file and attach it to the interface named 'device'.
403 * Set immediate mode, and set a filter that accepts only RARP requests.
404 */
405static int
406rarp_open(char *device)
407{
408 int fd;
409 struct ifreq ifr;
410 u_int dlt;
411 int immediate;
412
413 static struct bpf_insn insns[] = {
414 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12),
415 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3),
416 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20),
417 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1),
418 BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) +
419 sizeof(struct ether_header)),
420 BPF_STMT(BPF_RET|BPF_K, 0),
421 };
422 static struct bpf_program filter = {
423 sizeof insns / sizeof(insns[0]),
424 insns
425 };
426
427 fd = bpf_open();
428 /*
429 * Set immediate mode so packets are processed as they arrive.
430 */
431 immediate = 1;
432 if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) {
433 logmsg(LOG_ERR, "BIOCIMMEDIATE: %m");
434 goto rarp_open_err;
435 }
436 strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
437 if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) {
438 logmsg(LOG_ERR, "BIOCSETIF: %m");
439 goto rarp_open_err;
440 }
441 /*
442 * Check that the data link layer is an Ethernet; this code won't
443 * work with anything else.
444 */
445 if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) {
446 logmsg(LOG_ERR, "BIOCGDLT: %m");
447 goto rarp_open_err;
448 }
449 if (dlt != DLT_EN10MB) {
450 logmsg(LOG_ERR, "%s is not an ethernet", device);
451 goto rarp_open_err;
452 }
453 /*
454 * Set filter program.
455 */
456 if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) {
457 logmsg(LOG_ERR, "BIOCSETF: %m");
458 goto rarp_open_err;
459 }
460 return fd;
461
462rarp_open_err:
463 pidfile_remove(pidfile_fh);
464 exit(1);
465}
466
467/*
468 * Perform various sanity checks on the RARP request packet. Return
469 * false on failure and log the reason.
470 */
471static int
472rarp_check(u_char *p, u_int len)
473{
474 struct ether_header *ep = (struct ether_header *)p;
475 struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep));
476
477 if (len < sizeof(*ep) + sizeof(*ap)) {
478 logmsg(LOG_ERR, "truncated request, got %u, expected %lu",
479 len, (u_long)(sizeof(*ep) + sizeof(*ap)));
480 return 0;
481 }
482 /*
483 * XXX This test might be better off broken out...
484 */
485 if (ntohs(ep->ether_type) != ETHERTYPE_REVARP ||
486 ntohs(ap->arp_hrd) != ARPHRD_ETHER ||
487 ntohs(ap->arp_op) != REVARP_REQUEST ||
488 ntohs(ap->arp_pro) != ETHERTYPE_IP ||
489 ap->arp_hln != 6 || ap->arp_pln != 4) {
490 logmsg(LOG_DEBUG, "request fails sanity check");
491 return 0;
492 }
493 if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) {
494 logmsg(LOG_DEBUG, "ether/arp sender address mismatch");
495 return 0;
496 }
497 if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) {
498 logmsg(LOG_DEBUG, "ether/arp target address mismatch");
499 return 0;
500 }
501 return 1;
502}
503
504/*
505 * Loop indefinitely listening for RARP requests on the
506 * interfaces in 'iflist'.
507 */
508static void
509rarp_loop(void)
510{
511 u_char *buf, *bp, *ep;
512 int cc, fd;
513 fd_set fds, listeners;
514 int bufsize, maxfd = 0;
515 struct if_info *ii;
516
517 if (iflist == NULL) {
518 logmsg(LOG_ERR, "no interfaces");
519 goto rarpd_loop_err;
520 }
521 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) {
522 logmsg(LOG_ERR, "BIOCGBLEN: %m");
523 goto rarpd_loop_err;
524 }
525 buf = malloc(bufsize);
526 if (buf == NULL) {
527 logmsg(LOG_ERR, "malloc: %m");
528 goto rarpd_loop_err;
529 }
530
531 while (1) {
532 /*
533 * Find the highest numbered file descriptor for select().
534 * Initialize the set of descriptors to listen to.
535 */
536 FD_ZERO(&fds);
537 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
538 FD_SET(ii->ii_fd, &fds);
539 if (ii->ii_fd > maxfd)
540 maxfd = ii->ii_fd;
541 }
542 listeners = fds;
543 if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) {
544 /* Don't choke when we get ptraced */
545 if (errno == EINTR)
546 continue;
547 logmsg(LOG_ERR, "select: %m");
548 goto rarpd_loop_err;
549 }
550 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
551 fd = ii->ii_fd;
552 if (!FD_ISSET(fd, &listeners))
553 continue;
554 again:
555 cc = read(fd, (char *)buf, bufsize);
556 /* Don't choke when we get ptraced */
557 if ((cc == -1) && (errno == EINTR))
558 goto again;
559
560 /* Loop through the packet(s) */
561#define bhp ((struct bpf_hdr *)bp)
562 bp = buf;
563 ep = bp + cc;
564 while (bp < ep) {
565 u_int caplen, hdrlen;
566
567 caplen = bhp->bh_caplen;
568 hdrlen = bhp->bh_hdrlen;
569 if (rarp_check(bp + hdrlen, caplen))
570 rarp_process(ii, bp + hdrlen, caplen);
571 bp += BPF_WORDALIGN(hdrlen + caplen);
572 }
573 }
574 }
575#undef bhp
576 return;
577
578rarpd_loop_err:
579 pidfile_remove(pidfile_fh);
580 exit(1);
581}
582
583/*
584 * True if this server can boot the host whose IP address is 'addr'.
585 * This check is made by looking in the tftp directory for the
586 * configuration file.
587 */
588static int
589rarp_bootable(in_addr_t addr)
590{
591 struct dirent *dent;
592 DIR *d;
593 char ipname[9];
594 static DIR *dd = NULL;
595
596 (void)sprintf(ipname, "%08X", (in_addr_t)ntohl(addr));
597
598 /*
599 * If directory is already open, rewind it. Otherwise, open it.
600 */
601 if ((d = dd) != NULL)
602 rewinddir(d);
603 else {
604 if (chdir(tftp_dir) == -1) {
605 logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir);
606 goto rarp_bootable_err;
607 }
608 d = opendir(".");
609 if (d == NULL) {
610 logmsg(LOG_ERR, "opendir: %m");
611 goto rarp_bootable_err;
612 }
613 dd = d;
614 }
615 while ((dent = readdir(d)) != NULL)
616 if (strncmp(dent->d_name, ipname, 8) == 0)
617 return 1;
618 return 0;
619
620rarp_bootable_err:
621 pidfile_remove(pidfile_fh);
622 exit(1);
623}
624
625/*
626 * Given a list of IP addresses, 'alist', return the first address that
627 * is on network 'net'; 'netmask' is a mask indicating the network portion
628 * of the address.
629 */
630static in_addr_t
631choose_ipaddr(in_addr_t **alist, in_addr_t net, in_addr_t netmask)
632{
633 for (; *alist; ++alist)
634 if ((**alist & netmask) == net)
635 return **alist;
636 return 0;
637}
638
639/*
640 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has
641 * already been checked for validity. The reply is overlaid on the request.
642 */
643static void
644rarp_process(struct if_info *ii, u_char *pkt, u_int len)
645{
646 struct ether_header *ep;
647 struct hostent *hp;
648 in_addr_t target_ipaddr;
649 char ename[256];
650
651 ep = (struct ether_header *)pkt;
652 /* should this be arp_tha? */
653 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) {
654 logmsg(LOG_ERR, "cannot map %s to name",
655 eatoa(ep->ether_shost));
656 return;
657 }
658
659 if ((hp = gethostbyname(ename)) == NULL) {
660 logmsg(LOG_ERR, "cannot map %s to IP address", ename);
661 return;
662 }
663
664 /*
665 * Choose correct address from list.
666 */
667 if (hp->h_addrtype != AF_INET) {
668 logmsg(LOG_ERR, "cannot handle non IP addresses for %s",
669 ename);
670 return;
671 }
672 target_ipaddr = choose_ipaddr((in_addr_t **)hp->h_addr_list,
673 ii->ii_ipaddr & ii->ii_netmask,
674 ii->ii_netmask);
675 if (target_ipaddr == 0) {
676 logmsg(LOG_ERR, "cannot find %s on net %s",
677 ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask)));
678 return;
679 }
680 if (sflag || rarp_bootable(target_ipaddr))
681 rarp_reply(ii, ep, target_ipaddr, len);
682 else if (verbose > 1)
683 logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)",
684 ii->ii_ifname,
685 eatoa(ep->ether_shost),
686 intoa(ntohl(target_ipaddr)));
687}
688
689/*
690 * Poke the kernel arp tables with the ethernet/ip address combinataion
691 * given. When processing a reply, we must do this so that the booting
692 * host (i.e. the guy running rarpd), won't try to ARP for the hardware
693 * address of the guy being booted (he cannot answer the ARP).
694 */
695struct sockaddr_inarp sin_inarp = {
696 sizeof(struct sockaddr_inarp), AF_INET, 0,
697 {0},
698 {0},
699 0, 0
700};
701struct sockaddr_dl sin_dl = {
702 sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
703 0, ""
704};
705struct {
706 struct rt_msghdr rthdr;
707 char rtspace[512];
708} rtmsg;
709
710static void
711update_arptab(u_char *ep, in_addr_t ipaddr)
712{
713 struct timespec tp;
714 int cc;
715 struct sockaddr_inarp *ar, *ar2;
716 struct sockaddr_dl *ll, *ll2;
717 struct rt_msghdr *rt;
718 int xtype, xindex;
719 static pid_t pid;
720 int r;
721 static int seq;
722
723 r = socket(PF_ROUTE, SOCK_RAW, 0);
724 if (r == -1) {
725 logmsg(LOG_ERR, "raw route socket: %m");
726 pidfile_remove(pidfile_fh);
727 exit(1);
728 }
729 pid = getpid();
730
731 ar = &sin_inarp;
732 ar->sin_addr.s_addr = ipaddr;
733 ll = &sin_dl;
734 bcopy(ep, LLADDR(ll), 6);
735
736 /* Get the type and interface index */
737 rt = &rtmsg.rthdr;
738 bzero(rt, sizeof(rtmsg));
739 rt->rtm_version = RTM_VERSION;
740 rt->rtm_addrs = RTA_DST;
741 rt->rtm_type = RTM_GET;
742 rt->rtm_seq = ++seq;
743 ar2 = (struct sockaddr_inarp *)rtmsg.rtspace;
744 bcopy(ar, ar2, sizeof(*ar));
745 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar);
746 errno = 0;
747 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) {
748 logmsg(LOG_ERR, "rtmsg get write: %m");
749 close(r);
750 return;
751 }
752 do {
753 cc = read(r, rt, sizeof(rtmsg));
754 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid));
755 if (cc == -1) {
756 logmsg(LOG_ERR, "rtmsg get read: %m");
757 close(r);
758 return;
759 }
760 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len);
761 if (ll2->sdl_family != AF_LINK) {
762 /*
763 * XXX I think this means the ip address is not on a
764 * directly connected network (the family is AF_INET in
765 * this case).
766 */
767 logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08X?\n",
768 ll2->sdl_family, ipaddr);
769 close(r);
770 return;
771 }
772 xtype = ll2->sdl_type;
773 xindex = ll2->sdl_index;
774
775 /* Set the new arp entry */
776 bzero(rt, sizeof(rtmsg));
777 rt->rtm_version = RTM_VERSION;
778 rt->rtm_addrs = RTA_DST | RTA_GATEWAY;
779 rt->rtm_inits = RTV_EXPIRE;
780 clock_gettime(CLOCK_MONOTONIC, &tp);
781 rt->rtm_rmx.rmx_expire = tp.tv_sec + ARPSECS;
782 rt->rtm_flags = RTF_HOST | RTF_STATIC;
783 rt->rtm_type = RTM_ADD;
784 rt->rtm_seq = ++seq;
785
786 bcopy(ar, ar2, sizeof(*ar));
787
788 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2));
789 bcopy(ll, ll2, sizeof(*ll));
790 ll2->sdl_type = xtype;
791 ll2->sdl_index = xindex;
792
793 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2);
794 errno = 0;
795 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) {
796 logmsg(LOG_ERR, "rtmsg add write: %m");
797 close(r);
798 return;
799 }
800 do {
801 cc = read(r, rt, sizeof(rtmsg));
802 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid));
803 close(r);
804 if (cc == -1) {
805 logmsg(LOG_ERR, "rtmsg add read: %m");
806 return;
807 }
808}
809
810/*
811 * Build a reverse ARP packet and sent it out on the interface.
812 * 'ep' points to a valid REVARP_REQUEST. The REVARP_REPLY is built
813 * on top of the request, then written to the network.
814 *
815 * RFC 903 defines the ether_arp fields as follows. The following comments
816 * are taken (more or less) straight from this document.
817 *
818 * REVARP_REQUEST
819 *
820 * arp_sha is the hardware address of the sender of the packet.
821 * arp_spa is undefined.
822 * arp_tha is the 'target' hardware address.
823 * In the case where the sender wishes to determine his own
824 * protocol address, this, like arp_sha, will be the hardware
825 * address of the sender.
826 * arp_tpa is undefined.
827 *
828 * REVARP_REPLY
829 *
830 * arp_sha is the hardware address of the responder (the sender of the
831 * reply packet).
832 * arp_spa is the protocol address of the responder (see the note below).
833 * arp_tha is the hardware address of the target, and should be the same as
834 * that which was given in the request.
835 * arp_tpa is the protocol address of the target, that is, the desired address.
836 *
837 * Note that the requirement that arp_spa be filled in with the responder's
838 * protocol is purely for convenience. For instance, if a system were to use
839 * both ARP and RARP, then the inclusion of the valid protocol-hardware
840 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent
841 * ARP request.
842 */
843static void
844rarp_reply(struct if_info *ii, struct ether_header *ep, in_addr_t ipaddr,
845 u_int len)
846{
847 u_int n;
848 struct ether_arp *ap = (struct ether_arp *)(ep + 1);
849
850 update_arptab((u_char *)&ap->arp_sha, ipaddr);
851
852 /*
853 * Build the rarp reply by modifying the rarp request in place.
854 */
855 ap->arp_op = htons(REVARP_REPLY);
856
857#ifdef BROKEN_BPF
858 ep->ether_type = ETHERTYPE_REVARP;
859#endif
860 bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6);
861 bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6);
862 bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6);
863
864 bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4);
865 /* Target hardware is unchanged. */
866 bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4);
867
868 /* Zero possible garbage after packet. */
869 bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)),
870 len - (sizeof(*ep) + sizeof(*ap)));
871 n = write(ii->ii_fd, (char *)ep, len);
872 if (n != len)
873 logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len);
874 if (verbose)
875 logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname,
876 eatoa(ap->arp_tha),
877 intoa(ntohl(ipaddr)));
878}
879
880/*
881 * Get the netmask of an IP address. This routine is used if
882 * SIOCGIFNETMASK doesn't work.
883 */
884static in_addr_t
885ipaddrtonetmask(in_addr_t addr)
886{
887 addr = ntohl(addr);
888 if (IN_CLASSA(addr))
889 return htonl(IN_CLASSA_NET);
890 if (IN_CLASSB(addr))
891 return htonl(IN_CLASSB_NET);
892 if (IN_CLASSC(addr))
893 return htonl(IN_CLASSC_NET);
894 logmsg(LOG_DEBUG, "unknown IP address class: %08X", addr);
895 return htonl(0xffffffff);
896}
897
898/*
899 * A faster replacement for inet_ntoa().
900 */
901static char *
902intoa(in_addr_t addr)
903{
904 char *cp;
905 u_int byte;
906 int n;
907 static char buf[sizeof(".xxx.xxx.xxx.xxx")];
908
909 cp = &buf[sizeof buf];
910 *--cp = '\0';
911
912 n = 4;
913 do {
914 byte = addr & 0xff;
915 *--cp = byte % 10 + '0';
916 byte /= 10;
917 if (byte > 0) {
918 *--cp = byte % 10 + '0';
919 byte /= 10;
920 if (byte > 0)
921 *--cp = byte + '0';
922 }
923 *--cp = '.';
924 addr >>= 8;
925 } while (--n > 0);
926
927 return cp + 1;
928}
929
930static char *
931eatoa(u_char *ea)
932{
933 static char buf[sizeof("xx:xx:xx:xx:xx:xx")];
934
935 (void)sprintf(buf, "%x:%x:%x:%x:%x:%x",
936 ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]);
937 return (buf);
938}
939
940static void
941logmsg(int pri, const char *fmt, ...)
942{
943 va_list v;
944 FILE *fp;
945 char *newfmt;
946
947 va_start(v, fmt);
948 if (dflag) {
949 if (pri == LOG_ERR)
950 fp = stderr;
951 else
952 fp = stdout;
953 if (expand_syslog_m(fmt, &newfmt) == -1) {
954 vfprintf(fp, fmt, v);
955 } else {
956 vfprintf(fp, newfmt, v);
957 free(newfmt);
958 }
959 fputs("\n", fp);
960 fflush(fp);
961 } else {
962 vsyslog(pri, fmt, v);
963 }
964 va_end(v);
965}
966
967static int
968expand_syslog_m(const char *fmt, char **newfmt) {
969 const char *str, *m;
970 char *p, *np;
971
972 p = strdup("");
973 str = fmt;
974 while ((m = strstr(str, "%m")) != NULL) {
975 asprintf(&np, "%s%.*s%s", p, (int)(m - str),
976 str, strerror(errno));
977 free(p);
978 if (np == NULL) {
979 errno = ENOMEM;
980 return (-1);
981 }
982 p = np;
983 str = m + 2;
984 }
985
986 if (*str != '\0') {
987 asprintf(&np, "%s%s", p, str);
988 free(p);
989 if (np == NULL) {
990 errno = ENOMEM;
991 return (-1);
992 }
993 p = np;
994 }
995
996 *newfmt = p;
997 return (0);
998}