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 #if 0
20 #ifndef lint
21 static const char copyright[] =
22 "@(#) Copyright (c) 1990, 1991, 1992, 1993, 1996\n\
23 The Regents of the University of California. All rights reserved.\n";
24 #endif /* not lint */
25 #endif
26 #include <sys/cdefs.h>
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 */
80 struct 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 */
93 static struct if_info *iflist;
94
95 static int verbose; /* verbose messages */
96 static const char *tftp_dir = TFTP_DIR; /* tftp directory */
97
98 static int dflag; /* messages to stdout/stderr, not syslog(3) */
99 static int sflag; /* ignore /tftpboot */
100
101 static u_char zero[6];
102
103 static char pidfile_buf[PATH_MAX];
104 static char *pidfile;
105 #define RARPD_PIDFILE "/var/run/rarpd.%s.pid"
106 static struct pidfh *pidfile_fh;
107
108 static int bpf_open(void);
109 static in_addr_t choose_ipaddr(in_addr_t **, in_addr_t, in_addr_t);
110 static char *eatoa(u_char *);
111 static int expand_syslog_m(const char *fmt, char **newfmt);
112 static void init(char *);
113 static void init_one(struct ifaddrs *, char *, int);
114 static char *intoa(in_addr_t);
115 static in_addr_t ipaddrtonetmask(in_addr_t);
116 static void logmsg(int, const char *, ...) __printflike(2, 3);
117 static int rarp_bootable(in_addr_t);
118 static int rarp_check(u_char *, u_int);
119 static void rarp_loop(void);
120 static int rarp_open(char *);
121 static void rarp_process(struct if_info *, u_char *, u_int);
122 static void rarp_reply(struct if_info *, struct ether_header *,
123 in_addr_t, u_int);
124 static void update_arptab(u_char *, in_addr_t);
125 static void usage(void);
126
127 int
main(int argc,char * argv[])128 main(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 */
221 static void
init_one(struct ifaddrs * ifa,char * target,int pass1)222 init_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 /*
313 * Initialize all "candidate" interfaces that are in the system
314 * configuration list. A "candidate" is up, not loopback and not
315 * point to point.
316 */
317 static void
init(char * target)318 init(char *target)
319 {
320 struct if_info *ii, *nii, *lii;
321 struct ifaddrs *ifhead, *ifa;
322 int error;
323
324 error = getifaddrs(&ifhead);
325 if (error) {
326 logmsg(LOG_ERR, "getifaddrs: %m");
327 pidfile_remove(pidfile_fh);
328 exit(1);
329 }
330 /*
331 * We make two passes over the list we have got. In the first
332 * one, we only collect AF_LINK interfaces, and initialize our
333 * list of interfaces from them. In the second pass, we
334 * collect the actual IP addresses from the AF_INET
335 * interfaces, and allow for the same interface name to appear
336 * multiple times (in case of more than one IP address).
337 */
338 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
339 init_one(ifa, target, 1);
340 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next)
341 init_one(ifa, target, 0);
342 freeifaddrs(ifhead);
343
344 /* Throw away incomplete interfaces */
345 lii = NULL;
346 for (ii = iflist; ii != NULL; ii = nii) {
347 nii = ii->ii_next;
348 if (ii->ii_ipaddr == 0 ||
349 bcmp(ii->ii_eaddr, zero, 6) == 0) {
350 if (lii == NULL)
351 iflist = nii;
352 else
353 lii->ii_next = nii;
354 if (ii->ii_fd >= 0)
355 close(ii->ii_fd);
356 free(ii);
357 continue;
358 }
359 lii = ii;
360 }
361
362 /* Verbose stuff */
363 if (verbose)
364 for (ii = iflist; ii != NULL; ii = ii->ii_next)
365 logmsg(LOG_DEBUG, "%s %s 0x%08x %s",
366 ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)),
367 (in_addr_t)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr));
368 }
369
370 static void
usage(void)371 usage(void)
372 {
373
374 (void)fprintf(stderr, "%s\n%s\n",
375 "usage: rarpd -a [-dfsv] [-t directory] [-P pidfile]",
376 " rarpd [-dfsv] [-t directory] [-P pidfile] interface");
377 exit(1);
378 }
379
380 static int
bpf_open(void)381 bpf_open(void)
382 {
383 int fd;
384 int n = 0;
385 char device[sizeof "/dev/bpf000"];
386
387 /*
388 * Go through all the minors and find one that isn't in use.
389 */
390 do {
391 (void)sprintf(device, "/dev/bpf%d", n++);
392 fd = open(device, O_RDWR);
393 } while ((fd == -1) && (errno == EBUSY));
394
395 if (fd == -1) {
396 logmsg(LOG_ERR, "%s: %m", device);
397 pidfile_remove(pidfile_fh);
398 exit(1);
399 }
400 return fd;
401 }
402
403 /*
404 * Open a BPF file and attach it to the interface named 'device'.
405 * Set immediate mode, and set a filter that accepts only RARP requests.
406 */
407 static int
rarp_open(char * device)408 rarp_open(char *device)
409 {
410 int fd;
411 struct ifreq ifr;
412 u_int dlt;
413 int immediate;
414
415 static struct bpf_insn insns[] = {
416 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12),
417 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3),
418 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20),
419 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1),
420 BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) +
421 sizeof(struct ether_header)),
422 BPF_STMT(BPF_RET|BPF_K, 0),
423 };
424 static struct bpf_program filter = {
425 sizeof insns / sizeof(insns[0]),
426 insns
427 };
428
429 fd = bpf_open();
430 /*
431 * Set immediate mode so packets are processed as they arrive.
432 */
433 immediate = 1;
434 if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) {
435 logmsg(LOG_ERR, "BIOCIMMEDIATE: %m");
436 goto rarp_open_err;
437 }
438 strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
439 if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) {
440 logmsg(LOG_ERR, "BIOCSETIF: %m");
441 goto rarp_open_err;
442 }
443 /*
444 * Check that the data link layer is an Ethernet; this code won't
445 * work with anything else.
446 */
447 if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) {
448 logmsg(LOG_ERR, "BIOCGDLT: %m");
449 goto rarp_open_err;
450 }
451 if (dlt != DLT_EN10MB) {
452 logmsg(LOG_ERR, "%s is not an ethernet", device);
453 goto rarp_open_err;
454 }
455 /*
456 * Set filter program.
457 */
458 if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) {
459 logmsg(LOG_ERR, "BIOCSETF: %m");
460 goto rarp_open_err;
461 }
462 return fd;
463
464 rarp_open_err:
465 pidfile_remove(pidfile_fh);
466 exit(1);
467 }
468
469 /*
470 * Perform various sanity checks on the RARP request packet. Return
471 * false on failure and log the reason.
472 */
473 static int
rarp_check(u_char * p,u_int len)474 rarp_check(u_char *p, u_int len)
475 {
476 struct ether_header *ep = (struct ether_header *)p;
477 struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep));
478
479 if (len < sizeof(*ep) + sizeof(*ap)) {
480 logmsg(LOG_ERR, "truncated request, got %u, expected %lu",
481 len, (u_long)(sizeof(*ep) + sizeof(*ap)));
482 return 0;
483 }
484 /*
485 * XXX This test might be better off broken out...
486 */
487 if (ntohs(ep->ether_type) != ETHERTYPE_REVARP ||
488 ntohs(ap->arp_hrd) != ARPHRD_ETHER ||
489 ntohs(ap->arp_op) != REVARP_REQUEST ||
490 ntohs(ap->arp_pro) != ETHERTYPE_IP ||
491 ap->arp_hln != 6 || ap->arp_pln != 4) {
492 logmsg(LOG_DEBUG, "request fails sanity check");
493 return 0;
494 }
495 if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) {
496 logmsg(LOG_DEBUG, "ether/arp sender address mismatch");
497 return 0;
498 }
499 if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) {
500 logmsg(LOG_DEBUG, "ether/arp target address mismatch");
501 return 0;
502 }
503 return 1;
504 }
505
506 /*
507 * Loop indefinitely listening for RARP requests on the
508 * interfaces in 'iflist'.
509 */
510 static void
rarp_loop(void)511 rarp_loop(void)
512 {
513 u_char *buf, *bp, *ep;
514 int cc, fd;
515 fd_set fds, listeners;
516 int bufsize, maxfd = 0;
517 struct if_info *ii;
518
519 if (iflist == NULL) {
520 logmsg(LOG_ERR, "no interfaces");
521 goto rarpd_loop_err;
522 }
523 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) {
524 logmsg(LOG_ERR, "BIOCGBLEN: %m");
525 goto rarpd_loop_err;
526 }
527 buf = malloc(bufsize);
528 if (buf == NULL) {
529 logmsg(LOG_ERR, "malloc: %m");
530 goto rarpd_loop_err;
531 }
532
533 while (1) {
534 /*
535 * Find the highest numbered file descriptor for select().
536 * Initialize the set of descriptors to listen to.
537 */
538 FD_ZERO(&fds);
539 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
540 FD_SET(ii->ii_fd, &fds);
541 if (ii->ii_fd > maxfd)
542 maxfd = ii->ii_fd;
543 }
544 listeners = fds;
545 if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) {
546 /* Don't choke when we get ptraced */
547 if (errno == EINTR)
548 continue;
549 logmsg(LOG_ERR, "select: %m");
550 goto rarpd_loop_err;
551 }
552 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
553 fd = ii->ii_fd;
554 if (!FD_ISSET(fd, &listeners))
555 continue;
556 again:
557 cc = read(fd, (char *)buf, bufsize);
558 /* Don't choke when we get ptraced */
559 if ((cc == -1) && (errno == EINTR))
560 goto again;
561
562 /* Loop through the packet(s) */
563 #define bhp ((struct bpf_hdr *)bp)
564 bp = buf;
565 ep = bp + cc;
566 while (bp < ep) {
567 u_int caplen, hdrlen;
568
569 caplen = bhp->bh_caplen;
570 hdrlen = bhp->bh_hdrlen;
571 if (rarp_check(bp + hdrlen, caplen))
572 rarp_process(ii, bp + hdrlen, caplen);
573 bp += BPF_WORDALIGN(hdrlen + caplen);
574 }
575 }
576 }
577 #undef bhp
578 return;
579
580 rarpd_loop_err:
581 pidfile_remove(pidfile_fh);
582 exit(1);
583 }
584
585 /*
586 * True if this server can boot the host whose IP address is 'addr'.
587 * This check is made by looking in the tftp directory for the
588 * configuration file.
589 */
590 static int
rarp_bootable(in_addr_t addr)591 rarp_bootable(in_addr_t addr)
592 {
593 struct dirent *dent;
594 DIR *d;
595 char ipname[9];
596 static DIR *dd = NULL;
597
598 (void)sprintf(ipname, "%08X", (in_addr_t)ntohl(addr));
599
600 /*
601 * If directory is already open, rewind it. Otherwise, open it.
602 */
603 if ((d = dd) != NULL)
604 rewinddir(d);
605 else {
606 if (chdir(tftp_dir) == -1) {
607 logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir);
608 goto rarp_bootable_err;
609 }
610 d = opendir(".");
611 if (d == NULL) {
612 logmsg(LOG_ERR, "opendir: %m");
613 goto rarp_bootable_err;
614 }
615 dd = d;
616 }
617 while ((dent = readdir(d)) != NULL)
618 if (strncmp(dent->d_name, ipname, 8) == 0)
619 return 1;
620 return 0;
621
622 rarp_bootable_err:
623 pidfile_remove(pidfile_fh);
624 exit(1);
625 }
626
627 /*
628 * Given a list of IP addresses, 'alist', return the first address that
629 * is on network 'net'; 'netmask' is a mask indicating the network portion
630 * of the address.
631 */
632 static in_addr_t
choose_ipaddr(in_addr_t ** alist,in_addr_t net,in_addr_t netmask)633 choose_ipaddr(in_addr_t **alist, in_addr_t net, in_addr_t netmask)
634 {
635
636 for (; *alist; ++alist)
637 if ((**alist & netmask) == net)
638 return **alist;
639 return 0;
640 }
641
642 /*
643 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has
644 * already been checked for validity. The reply is overlaid on the request.
645 */
646 static void
rarp_process(struct if_info * ii,u_char * pkt,u_int len)647 rarp_process(struct if_info *ii, u_char *pkt, u_int len)
648 {
649 struct ether_header *ep;
650 struct hostent *hp;
651 in_addr_t target_ipaddr;
652 char ename[256];
653
654 ep = (struct ether_header *)pkt;
655 /* should this be arp_tha? */
656 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) {
657 logmsg(LOG_ERR, "cannot map %s to name",
658 eatoa(ep->ether_shost));
659 return;
660 }
661
662 if ((hp = gethostbyname(ename)) == NULL) {
663 logmsg(LOG_ERR, "cannot map %s to IP address", ename);
664 return;
665 }
666
667 /*
668 * Choose correct address from list.
669 */
670 if (hp->h_addrtype != AF_INET) {
671 logmsg(LOG_ERR, "cannot handle non IP addresses for %s",
672 ename);
673 return;
674 }
675 target_ipaddr = choose_ipaddr((in_addr_t **)hp->h_addr_list,
676 ii->ii_ipaddr & ii->ii_netmask,
677 ii->ii_netmask);
678 if (target_ipaddr == 0) {
679 logmsg(LOG_ERR, "cannot find %s on net %s",
680 ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask)));
681 return;
682 }
683 if (sflag || rarp_bootable(target_ipaddr))
684 rarp_reply(ii, ep, target_ipaddr, len);
685 else if (verbose > 1)
686 logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)",
687 ii->ii_ifname,
688 eatoa(ep->ether_shost),
689 intoa(ntohl(target_ipaddr)));
690 }
691
692 /*
693 * Poke the kernel arp tables with the ethernet/ip address combination
694 * given. When processing a reply, we must do this so that the booting
695 * host (i.e. the guy running rarpd), won't try to ARP for the hardware
696 * address of the guy being booted (he cannot answer the ARP).
697 */
698 static struct sockaddr_in sin_inarp = {
699 sizeof(struct sockaddr_in), AF_INET, 0,
700 {0},
701 {0},
702 };
703
704 static struct sockaddr_dl sin_dl = {
705 sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
706 0, ""
707 };
708
709 static struct {
710 struct rt_msghdr rthdr;
711 char rtspace[512];
712 } rtmsg;
713
714 static void
update_arptab(u_char * ep,in_addr_t ipaddr)715 update_arptab(u_char *ep, in_addr_t ipaddr)
716 {
717 struct timespec tp;
718 int cc;
719 struct sockaddr_in *ar, *ar2;
720 struct sockaddr_dl *ll, *ll2;
721 struct rt_msghdr *rt;
722 int xtype, xindex;
723 static pid_t pid;
724 int r;
725 static int seq;
726
727 r = socket(PF_ROUTE, SOCK_RAW, 0);
728 if (r == -1) {
729 logmsg(LOG_ERR, "raw route socket: %m");
730 pidfile_remove(pidfile_fh);
731 exit(1);
732 }
733 pid = getpid();
734
735 ar = &sin_inarp;
736 ar->sin_addr.s_addr = ipaddr;
737 ll = &sin_dl;
738 bcopy(ep, LLADDR(ll), 6);
739
740 /* Get the type and interface index */
741 rt = &rtmsg.rthdr;
742 bzero(&rtmsg, sizeof(rtmsg));
743 rt->rtm_version = RTM_VERSION;
744 rt->rtm_addrs = RTA_DST;
745 rt->rtm_type = RTM_GET;
746 rt->rtm_seq = ++seq;
747 ar2 = (struct sockaddr_in *)rtmsg.rtspace;
748 bcopy(ar, ar2, sizeof(*ar));
749 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar);
750 errno = 0;
751 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) {
752 logmsg(LOG_ERR, "rtmsg get write: %m");
753 close(r);
754 return;
755 }
756 do {
757 cc = read(r, rt, sizeof(rtmsg));
758 } while (cc > 0 && (rt->rtm_type != RTM_GET || rt->rtm_seq != seq ||
759 rt->rtm_pid != pid));
760 if (cc == -1) {
761 logmsg(LOG_ERR, "rtmsg get read: %m");
762 close(r);
763 return;
764 }
765 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len);
766 if (ll2->sdl_family != AF_LINK) {
767 /*
768 * XXX I think this means the ip address is not on a
769 * directly connected network (the family is AF_INET in
770 * this case).
771 */
772 logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08X?\n",
773 ll2->sdl_family, ipaddr);
774 close(r);
775 return;
776 }
777 xtype = ll2->sdl_type;
778 xindex = ll2->sdl_index;
779
780 /* Set the new arp entry */
781 bzero(rt, sizeof(rtmsg));
782 rt->rtm_version = RTM_VERSION;
783 rt->rtm_addrs = RTA_DST | RTA_GATEWAY;
784 rt->rtm_inits = RTV_EXPIRE;
785 clock_gettime(CLOCK_MONOTONIC, &tp);
786 rt->rtm_rmx.rmx_expire = tp.tv_sec + ARPSECS;
787 rt->rtm_flags = RTF_HOST | RTF_STATIC;
788 rt->rtm_type = RTM_ADD;
789 rt->rtm_seq = ++seq;
790
791 bcopy(ar, ar2, sizeof(*ar));
792
793 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2));
794 bcopy(ll, ll2, sizeof(*ll));
795 ll2->sdl_type = xtype;
796 ll2->sdl_index = xindex;
797
798 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2);
799 errno = 0;
800 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) {
801 logmsg(LOG_ERR, "rtmsg add write: %m");
802 close(r);
803 return;
804 }
805 do {
806 cc = read(r, rt, sizeof(rtmsg));
807 } while (cc > 0 && (rt->rtm_type != RTM_ADD || rt->rtm_seq != seq ||
808 rt->rtm_pid != pid));
809 close(r);
810 if (cc == -1) {
811 logmsg(LOG_ERR, "rtmsg add read: %m");
812 return;
813 }
814 }
815
816 /*
817 * Build a reverse ARP packet and sent it out on the interface.
818 * 'ep' points to a valid REVARP_REQUEST. The REVARP_REPLY is built
819 * on top of the request, then written to the network.
820 *
821 * RFC 903 defines the ether_arp fields as follows. The following comments
822 * are taken (more or less) straight from this document.
823 *
824 * REVARP_REQUEST
825 *
826 * arp_sha is the hardware address of the sender of the packet.
827 * arp_spa is undefined.
828 * arp_tha is the 'target' hardware address.
829 * In the case where the sender wishes to determine his own
830 * protocol address, this, like arp_sha, will be the hardware
831 * address of the sender.
832 * arp_tpa is undefined.
833 *
834 * REVARP_REPLY
835 *
836 * arp_sha is the hardware address of the responder (the sender of the
837 * reply packet).
838 * arp_spa is the protocol address of the responder (see the note below).
839 * arp_tha is the hardware address of the target, and should be the same as
840 * that which was given in the request.
841 * arp_tpa is the protocol address of the target, that is, the desired address.
842 *
843 * Note that the requirement that arp_spa be filled in with the responder's
844 * protocol is purely for convenience. For instance, if a system were to use
845 * both ARP and RARP, then the inclusion of the valid protocol-hardware
846 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent
847 * ARP request.
848 */
849 static void
rarp_reply(struct if_info * ii,struct ether_header * ep,in_addr_t ipaddr,u_int len)850 rarp_reply(struct if_info *ii, struct ether_header *ep, in_addr_t ipaddr,
851 u_int len)
852 {
853 u_int n;
854 struct ether_arp *ap = (struct ether_arp *)(ep + 1);
855
856 update_arptab((u_char *)&ap->arp_sha, ipaddr);
857
858 /*
859 * Build the rarp reply by modifying the rarp request in place.
860 */
861 ap->arp_op = htons(REVARP_REPLY);
862
863 #ifdef BROKEN_BPF
864 ep->ether_type = ETHERTYPE_REVARP;
865 #endif
866 bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6);
867 bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6);
868 bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6);
869
870 bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4);
871 /* Target hardware is unchanged. */
872 bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4);
873
874 /* Zero possible garbage after packet. */
875 bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)),
876 len - (sizeof(*ep) + sizeof(*ap)));
877 n = write(ii->ii_fd, (char *)ep, len);
878 if (n != len)
879 logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len);
880 if (verbose)
881 logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname,
882 eatoa(ap->arp_tha),
883 intoa(ntohl(ipaddr)));
884 }
885
886 /*
887 * Get the netmask of an IP address. This routine is used if
888 * SIOCGIFNETMASK doesn't work.
889 */
890 static in_addr_t
ipaddrtonetmask(in_addr_t addr)891 ipaddrtonetmask(in_addr_t addr)
892 {
893
894 addr = ntohl(addr);
895 if (IN_CLASSA(addr))
896 return htonl(IN_CLASSA_NET);
897 if (IN_CLASSB(addr))
898 return htonl(IN_CLASSB_NET);
899 if (IN_CLASSC(addr))
900 return htonl(IN_CLASSC_NET);
901 logmsg(LOG_DEBUG, "unknown IP address class: %08X", addr);
902 return htonl(0xffffffff);
903 }
904
905 /*
906 * A faster replacement for inet_ntoa().
907 */
908 static char *
intoa(in_addr_t addr)909 intoa(in_addr_t addr)
910 {
911 char *cp;
912 u_int byte;
913 int n;
914 static char buf[sizeof(".xxx.xxx.xxx.xxx")];
915
916 cp = &buf[sizeof buf];
917 *--cp = '\0';
918
919 n = 4;
920 do {
921 byte = addr & 0xff;
922 *--cp = byte % 10 + '0';
923 byte /= 10;
924 if (byte > 0) {
925 *--cp = byte % 10 + '0';
926 byte /= 10;
927 if (byte > 0)
928 *--cp = byte + '0';
929 }
930 *--cp = '.';
931 addr >>= 8;
932 } while (--n > 0);
933
934 return cp + 1;
935 }
936
937 static char *
eatoa(u_char * ea)938 eatoa(u_char *ea)
939 {
940 static char buf[sizeof("xx:xx:xx:xx:xx:xx")];
941
942 (void)sprintf(buf, "%x:%x:%x:%x:%x:%x",
943 ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]);
944 return (buf);
945 }
946
947 static void
logmsg(int pri,const char * fmt,...)948 logmsg(int pri, const char *fmt, ...)
949 {
950 va_list v;
951 FILE *fp;
952 char *newfmt;
953
954 va_start(v, fmt);
955 if (dflag) {
956 if (pri == LOG_ERR)
957 fp = stderr;
958 else
959 fp = stdout;
960 if (expand_syslog_m(fmt, &newfmt) == -1) {
961 vfprintf(fp, fmt, v);
962 } else {
963 vfprintf(fp, newfmt, v);
964 free(newfmt);
965 }
966 fputs("\n", fp);
967 fflush(fp);
968 } else {
969 vsyslog(pri, fmt, v);
970 }
971 va_end(v);
972 }
973
974 static int
expand_syslog_m(const char * fmt,char ** newfmt)975 expand_syslog_m(const char *fmt, char **newfmt) {
976 const char *str, *m;
977 char *p, *np;
978
979 p = strdup("");
980 str = fmt;
981 while ((m = strstr(str, "%m")) != NULL) {
982 asprintf(&np, "%s%.*s%s", p, (int)(m - str),
983 str, strerror(errno));
984 free(p);
985 if (np == NULL) {
986 errno = ENOMEM;
987 return (-1);
988 }
989 p = np;
990 str = m + 2;
991 }
992
993 if (*str != '\0') {
994 asprintf(&np, "%s%s", p, str);
995 free(p);
996 if (np == NULL) {
997 errno = ENOMEM;
998 return (-1);
999 }
1000 p = np;
1001 }
1002
1003 *newfmt = p;
1004 return (0);
1005 }
1006