1 /* $OpenBSD: dispatch.c,v 1.31 2004/09/21 04:07:03 david Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright 2004 Henning Brauer <henning@openbsd.org>
7 * Copyright (c) 1995, 1996, 1997, 1998, 1999
8 * The Internet Software Consortium. All rights reserved.
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 *
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of The Internet Software Consortium nor the names
20 * of its contributors may be used to endorse or promote products derived
21 * from this software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
24 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
25 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
27 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
28 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
30 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
31 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
32 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
33 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
34 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * This software has been written for the Internet Software Consortium
38 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
39 * Enterprises. To learn more about the Internet Software Consortium,
40 * see ``http://www.vix.com/isc''. To learn more about Vixie
41 * Enterprises, see ``http://www.vix.com''.
42 */
43
44 #include <sys/cdefs.h>
45 #include "dhcpd.h"
46 #include "privsep.h"
47
48 #include <sys/ioctl.h>
49
50 #include <assert.h>
51 #include <net/if_media.h>
52 #include <ifaddrs.h>
53 #include <poll.h>
54
55 /* Assert that pointer p is aligned to at least align bytes */
56 #define assert_aligned(p, align) assert((((uintptr_t)p) & ((align) - 1)) == 0)
57
58 static struct protocol *protocols;
59 static struct timeout *timeouts;
60 static struct timeout *free_timeouts;
61 static int interfaces_invalidated;
62 void (*bootp_packet_handler)(struct interface_info *,
63 struct dhcp_packet *, int, unsigned int,
64 struct iaddr, struct hardware *);
65
66 static int interface_status(struct interface_info *ifinfo);
67
68 /*
69 * Use getifaddrs() to get a list of all the attached interfaces. For
70 * each interface that's of type INET and not the loopback interface,
71 * register that interface with the network I/O software, figure out
72 * what subnet it's on, and add it to the list of interfaces.
73 */
74 void
discover_interfaces(struct interface_info * iface)75 discover_interfaces(struct interface_info *iface)
76 {
77 struct ifaddrs *ifap, *ifa;
78 struct ifreq *tif;
79 int len = IFNAMSIZ + sizeof(struct sockaddr_storage);
80
81 if (getifaddrs(&ifap) != 0)
82 error("getifaddrs failed");
83
84 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
85 if ((ifa->ifa_flags & IFF_LOOPBACK) ||
86 (ifa->ifa_flags & IFF_POINTOPOINT) ||
87 (!(ifa->ifa_flags & IFF_UP)))
88 continue;
89
90 if (strcmp(iface->name, ifa->ifa_name))
91 continue;
92
93 /*
94 * If we have the capability, extract link information
95 * and record it in a linked list.
96 */
97 if (ifa->ifa_addr->sa_family == AF_LINK) {
98 struct sockaddr_dl *foo;
99
100 /*
101 * The implementation of getifaddrs should guarantee
102 * this alignment
103 */
104 assert_aligned(ifa->ifa_addr,
105 _Alignof(struct sockaddr_dl));
106 #ifdef __clang__
107 #pragma clang diagnostic push
108 #pragma clang diagnostic ignored "-Wcast-align"
109 #endif
110 foo = (struct sockaddr_dl *)ifa->ifa_addr;
111 #ifdef __clang__
112 #pragma clang diagnostic pop
113 #endif
114
115 iface->index = foo->sdl_index;
116 iface->hw_address.hlen = foo->sdl_alen;
117 iface->hw_address.htype = HTYPE_ETHER; /* XXX */
118 memcpy(iface->hw_address.haddr,
119 LLADDR(foo), foo->sdl_alen);
120 }
121 if (!iface->ifp) {
122 if ((tif = calloc(1, len)) == NULL)
123 error("no space to remember ifp");
124 strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
125 iface->ifp = tif;
126 }
127
128 }
129
130 if (!iface->ifp)
131 error("%s: not found", iface->name);
132
133 /* Register the interface... */
134 if_register_receive(iface);
135 if_register_send(iface);
136 add_protocol(iface->name, iface->rfdesc, got_one, iface);
137 freeifaddrs(ifap);
138 }
139
140 void
reinitialize_interfaces(void)141 reinitialize_interfaces(void)
142 {
143 interfaces_invalidated = 1;
144 }
145
146 /*
147 * Wait for packets to come in using poll(). When a packet comes in,
148 * call receive_packet to receive the packet and possibly strip hardware
149 * addressing information from it, and then call through the
150 * bootp_packet_handler hook to try to do something with it.
151 */
152 void
dispatch(void)153 dispatch(void)
154 {
155 int count, live_interfaces, i, to_msec, nfds = 0;
156 struct protocol *l;
157 struct pollfd *fds;
158 time_t howlong;
159
160 for (l = protocols; l; l = l->next)
161 nfds++;
162
163 fds = malloc(nfds * sizeof(struct pollfd));
164 if (fds == NULL)
165 error("Can't allocate poll structures.");
166
167 do {
168 /*
169 * Call any expired timeouts, and then if there's still
170 * a timeout registered, time out the select call then.
171 */
172 another:
173 if (timeouts) {
174 struct timeout *t;
175
176 if (timeouts->when <= cur_time) {
177 t = timeouts;
178 timeouts = timeouts->next;
179 (*(t->func))(t->what);
180 t->next = free_timeouts;
181 free_timeouts = t;
182 goto another;
183 }
184
185 /*
186 * Figure timeout in milliseconds, and check for
187 * potential overflow, so we can cram into an
188 * int for poll, while not polling with a
189 * negative timeout and blocking indefinitely.
190 */
191 howlong = timeouts->when - cur_time;
192 if (howlong > INT_MAX / 1000)
193 howlong = INT_MAX / 1000;
194 to_msec = howlong * 1000;
195 } else
196 to_msec = -1;
197
198 /* Set up the descriptors to be polled. */
199 live_interfaces = 0;
200 for (i = 0, l = protocols; l; l = l->next) {
201 struct interface_info *ip = l->local;
202
203 if (ip == NULL || ip->dead)
204 continue;
205 fds[i].fd = l->fd;
206 fds[i].events = POLLIN;
207 fds[i].revents = 0;
208 i++;
209 if (l->handler == got_one)
210 live_interfaces++;
211 }
212 if (live_interfaces == 0)
213 error("No live interfaces to poll on - exiting.");
214
215 /* Wait for a packet or a timeout... XXX */
216 count = poll(fds, nfds, to_msec);
217
218 /* Not likely to be transitory... */
219 if (count == -1) {
220 if (errno == EAGAIN || errno == EINTR) {
221 time(&cur_time);
222 continue;
223 } else
224 error("poll: %m");
225 }
226
227 /* Get the current time... */
228 time(&cur_time);
229
230 i = 0;
231 for (l = protocols; l; l = l->next) {
232 struct interface_info *ip;
233 ip = l->local;
234 if ((fds[i].revents & (POLLIN | POLLHUP))) {
235 fds[i].revents = 0;
236 if (ip && (l->handler != got_one ||
237 !ip->dead))
238 (*(l->handler))(l);
239 if (interfaces_invalidated)
240 break;
241 }
242 i++;
243 }
244 interfaces_invalidated = 0;
245 } while (1);
246 }
247
248
249 void
got_one(struct protocol * l)250 got_one(struct protocol *l)
251 {
252 struct sockaddr_in from;
253 struct hardware hfrom;
254 struct iaddr ifrom;
255 ssize_t result;
256 union {
257 /*
258 * Packet input buffer. Must be as large as largest
259 * possible MTU.
260 */
261 unsigned char packbuf[4095];
262 struct dhcp_packet packet;
263 } u;
264 struct interface_info *ip = l->local;
265
266 if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
267 &hfrom)) == -1) {
268 warning("receive_packet failed on %s: %s", ip->name,
269 strerror(errno));
270 ip->errors++;
271 if ((!interface_status(ip)) ||
272 (ip->noifmedia && ip->errors > 20)) {
273 /* our interface has gone away. */
274 warning("Interface %s no longer appears valid.",
275 ip->name);
276 ip->dead = 1;
277 interfaces_invalidated = 1;
278 close(l->fd);
279 remove_protocol(l);
280 free(ip);
281 }
282 return;
283 }
284 if (result == 0)
285 return;
286
287 if (bootp_packet_handler) {
288 ifrom.len = 4;
289 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
290
291 (*bootp_packet_handler)(ip, &u.packet, result,
292 from.sin_port, ifrom, &hfrom);
293 }
294 }
295
296 int
interface_status(struct interface_info * ifinfo)297 interface_status(struct interface_info *ifinfo)
298 {
299 char *ifname = ifinfo->name;
300 int ifsock = ifinfo->rfdesc;
301 struct ifreq ifr;
302 struct ifmediareq ifmr;
303
304 /* get interface flags */
305 memset(&ifr, 0, sizeof(ifr));
306 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
307 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
308 cap_syslog(capsyslog, LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
309 ifname);
310 goto inactive;
311 }
312
313 /*
314 * if one of UP and RUNNING flags is dropped,
315 * the interface is not active.
316 */
317 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
318 goto inactive;
319
320 /* Next, check carrier on the interface, if possible */
321 if (ifinfo->noifmedia)
322 goto active;
323 memset(&ifmr, 0, sizeof(ifmr));
324 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
325 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
326 if (errno != EINVAL) {
327 cap_syslog(capsyslog, LOG_DEBUG,
328 "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
329 ifinfo->noifmedia = 1;
330 goto active;
331 }
332 /*
333 * EINVAL (or ENOTTY) simply means that the interface
334 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
335 */
336 ifinfo->noifmedia = 1;
337 goto active;
338 }
339 if (ifmr.ifm_status & IFM_AVALID) {
340 switch (ifmr.ifm_active & IFM_NMASK) {
341 case IFM_ETHER:
342 case IFM_IEEE80211:
343 if (ifmr.ifm_status & IFM_ACTIVE)
344 goto active;
345 else
346 goto inactive;
347 break;
348 default:
349 goto inactive;
350 }
351 }
352 inactive:
353 return (0);
354 active:
355 return (1);
356 }
357
358 void
add_timeout(time_t when,void (* where)(void *),void * what)359 add_timeout(time_t when, void (*where)(void *), void *what)
360 {
361 struct timeout *t, *q;
362
363 /* See if this timeout supersedes an existing timeout. */
364 t = NULL;
365 for (q = timeouts; q; q = q->next) {
366 if (q->func == where && q->what == what) {
367 if (t)
368 t->next = q->next;
369 else
370 timeouts = q->next;
371 break;
372 }
373 t = q;
374 }
375
376 /* If we didn't supersede a timeout, allocate a timeout
377 structure now. */
378 if (!q) {
379 if (free_timeouts) {
380 q = free_timeouts;
381 free_timeouts = q->next;
382 q->func = where;
383 q->what = what;
384 } else {
385 q = malloc(sizeof(struct timeout));
386 if (!q)
387 error("Can't allocate timeout structure!");
388 q->func = where;
389 q->what = what;
390 }
391 }
392
393 q->when = when;
394
395 /* Now sort this timeout into the timeout list. */
396
397 /* Beginning of list? */
398 if (!timeouts || timeouts->when > q->when) {
399 q->next = timeouts;
400 timeouts = q;
401 return;
402 }
403
404 /* Middle of list? */
405 for (t = timeouts; t->next; t = t->next) {
406 if (t->next->when > q->when) {
407 q->next = t->next;
408 t->next = q;
409 return;
410 }
411 }
412
413 /* End of list. */
414 t->next = q;
415 q->next = NULL;
416 }
417
418 void
cancel_timeout(void (* where)(void *),void * what)419 cancel_timeout(void (*where)(void *), void *what)
420 {
421 struct timeout *t, *q;
422
423 /* Look for this timeout on the list, and unlink it if we find it. */
424 t = NULL;
425 for (q = timeouts; q; q = q->next) {
426 if (q->func == where && q->what == what) {
427 if (t)
428 t->next = q->next;
429 else
430 timeouts = q->next;
431 break;
432 }
433 t = q;
434 }
435
436 /* If we found the timeout, put it on the free list. */
437 if (q) {
438 q->next = free_timeouts;
439 free_timeouts = q;
440 }
441 }
442
443 /* Add a protocol to the list of protocols... */
444 void
add_protocol(const char * name,int fd,void (* handler)(struct protocol *),void * local)445 add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
446 void *local)
447 {
448 struct protocol *p;
449
450 p = malloc(sizeof(*p));
451 if (!p)
452 error("can't allocate protocol struct for %s", name);
453
454 p->fd = fd;
455 p->handler = handler;
456 p->local = local;
457 p->next = protocols;
458 protocols = p;
459 }
460
461 void
remove_protocol(struct protocol * proto)462 remove_protocol(struct protocol *proto)
463 {
464 struct protocol *p, *prev;
465
466 for (p = protocols, prev = NULL; p != NULL; prev = p, p = p->next) {
467 if (p == proto) {
468 if (prev == NULL)
469 protocols = p->next;
470 else
471 prev->next = p->next;
472 free(p);
473 break;
474 }
475 }
476 }
477
478 int
interface_link_status(char * ifname)479 interface_link_status(char *ifname)
480 {
481 struct ifmediareq ifmr;
482 int sock;
483
484 if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
485 error("Can't create socket");
486
487 memset(&ifmr, 0, sizeof(ifmr));
488 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
489 if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
490 /* EINVAL -> link state unknown. treat as active */
491 if (errno != EINVAL)
492 cap_syslog(capsyslog, LOG_DEBUG,
493 "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
494 close(sock);
495 return (1);
496 }
497 close(sock);
498
499 if (ifmr.ifm_status & IFM_AVALID) {
500 switch (ifmr.ifm_active & IFM_NMASK) {
501 case IFM_ETHER:
502 case IFM_IEEE80211:
503 if (ifmr.ifm_status & IFM_ACTIVE)
504 return (1);
505 else
506 return (0);
507 }
508 }
509 return (1);
510 }
511
512 void
interface_set_mtu_unpriv(int privfd,u_int16_t mtu)513 interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
514 {
515 struct imsg_hdr hdr;
516 struct buf *buf;
517 int errs = 0;
518
519 hdr.code = IMSG_SET_INTERFACE_MTU;
520 hdr.len = sizeof(hdr) +
521 sizeof(u_int16_t);
522
523 if ((buf = buf_open(hdr.len)) == NULL)
524 error("buf_open: %m");
525
526 errs += buf_add(buf, &hdr, sizeof(hdr));
527 errs += buf_add(buf, &mtu, sizeof(mtu));
528 if (errs)
529 error("buf_add: %m");
530
531 if (buf_close(privfd, buf) == -1)
532 error("buf_close: %m");
533 }
534
535 void
interface_set_mtu_priv(char * ifname,u_int16_t mtu)536 interface_set_mtu_priv(char *ifname, u_int16_t mtu)
537 {
538 struct ifreq ifr;
539 int sock;
540 u_int16_t old_mtu;
541
542 if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
543 error("Can't create socket");
544
545 memset(&ifr, 0, sizeof(ifr));
546 old_mtu = 0;
547
548 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
549
550 if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
551 warning("SIOCGIFMTU failed (%s): %s", ifname,
552 strerror(errno));
553 else
554 old_mtu = ifr.ifr_mtu;
555
556 if (mtu != old_mtu) {
557 ifr.ifr_mtu = mtu;
558
559 if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
560 warning("SIOCSIFMTU failed (%d): %s", mtu,
561 strerror(errno));
562 }
563
564 close(sock);
565 }
566