xref: /freebsd/sbin/dhclient/dispatch.c (revision 9f44a47fd07924afc035991af15d84e6585dea4f) 
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 __FBSDID("$FreeBSD$");
46 
47 #include "dhcpd.h"
48 #include "privsep.h"
49 
50 #include <sys/ioctl.h>
51 
52 #include <assert.h>
53 #include <net/if_media.h>
54 #include <ifaddrs.h>
55 #include <poll.h>
56 
57 /* Assert that pointer p is aligned to at least align bytes */
58 #define assert_aligned(p, align) assert((((uintptr_t)p) & ((align) - 1)) == 0)
59 
60 static struct protocol *protocols;
61 static struct timeout *timeouts;
62 static struct timeout *free_timeouts;
63 static int interfaces_invalidated;
64 void (*bootp_packet_handler)(struct interface_info *,
65     struct dhcp_packet *, int, unsigned int,
66     struct iaddr, struct hardware *);
67 
68 static int interface_status(struct interface_info *ifinfo);
69 
70 /*
71  * Use getifaddrs() to get a list of all the attached interfaces.  For
72  * each interface that's of type INET and not the loopback interface,
73  * register that interface with the network I/O software, figure out
74  * what subnet it's on, and add it to the list of interfaces.
75  */
76 void
77 discover_interfaces(struct interface_info *iface)
78 {
79 	struct ifaddrs *ifap, *ifa;
80 	struct ifreq *tif;
81 	int len = IFNAMSIZ + sizeof(struct sockaddr_storage);
82 
83 	if (getifaddrs(&ifap) != 0)
84 		error("getifaddrs failed");
85 
86 	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
87 		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
88 		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
89 		    (!(ifa->ifa_flags & IFF_UP)))
90 			continue;
91 
92 		if (strcmp(iface->name, ifa->ifa_name))
93 			continue;
94 
95 		/*
96 		 * If we have the capability, extract link information
97 		 * and record it in a linked list.
98 		 */
99 		if (ifa->ifa_addr->sa_family == AF_LINK) {
100 			struct sockaddr_dl *foo;
101 
102 			/*
103 			 * The implementation of getifaddrs should guarantee
104 			 * this alignment
105 			 */
106 			assert_aligned(ifa->ifa_addr,
107 				       _Alignof(struct sockaddr_dl));
108 #ifdef __clang__
109 #pragma clang diagnostic push
110 #pragma clang diagnostic ignored "-Wcast-align"
111 #endif
112 			foo = (struct sockaddr_dl *)ifa->ifa_addr;
113 #ifdef __clang__
114 #pragma clang diagnostic pop
115 #endif
116 
117 			iface->index = foo->sdl_index;
118 			iface->hw_address.hlen = foo->sdl_alen;
119 			iface->hw_address.htype = HTYPE_ETHER; /* XXX */
120 			memcpy(iface->hw_address.haddr,
121 			    LLADDR(foo), foo->sdl_alen);
122 		}
123 		if (!iface->ifp) {
124 			if ((tif = calloc(1, len)) == NULL)
125 				error("no space to remember ifp");
126 			strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
127 			iface->ifp = tif;
128 		}
129 
130 	}
131 
132 	if (!iface->ifp)
133 		error("%s: not found", iface->name);
134 
135 	/* Register the interface... */
136 	if_register_receive(iface);
137 	if_register_send(iface);
138 	add_protocol(iface->name, iface->rfdesc, got_one, iface);
139 	freeifaddrs(ifap);
140 }
141 
142 void
143 reinitialize_interfaces(void)
144 {
145 	interfaces_invalidated = 1;
146 }
147 
148 /*
149  * Wait for packets to come in using poll().  When a packet comes in,
150  * call receive_packet to receive the packet and possibly strip hardware
151  * addressing information from it, and then call through the
152  * bootp_packet_handler hook to try to do something with it.
153  */
154 void
155 dispatch(void)
156 {
157 	int count, live_interfaces, i, to_msec, nfds = 0;
158 	struct protocol *l;
159 	struct pollfd *fds;
160 	time_t howlong;
161 
162 	for (l = protocols; l; l = l->next)
163 		nfds++;
164 
165 	fds = malloc(nfds * sizeof(struct pollfd));
166 	if (fds == NULL)
167 		error("Can't allocate poll structures.");
168 
169 	do {
170 		/*
171 		 * Call any expired timeouts, and then if there's still
172 		 * a timeout registered, time out the select call then.
173 		 */
174 another:
175 		if (timeouts) {
176 			struct timeout *t;
177 
178 			if (timeouts->when <= cur_time) {
179 				t = timeouts;
180 				timeouts = timeouts->next;
181 				(*(t->func))(t->what);
182 				t->next = free_timeouts;
183 				free_timeouts = t;
184 				goto another;
185 			}
186 
187 			/*
188 			 * Figure timeout in milliseconds, and check for
189 			 * potential overflow, so we can cram into an
190 			 * int for poll, while not polling with a
191 			 * negative timeout and blocking indefinitely.
192 			 */
193 			howlong = timeouts->when - cur_time;
194 			if (howlong > INT_MAX / 1000)
195 				howlong = INT_MAX / 1000;
196 			to_msec = howlong * 1000;
197 		} else
198 			to_msec = -1;
199 
200 		/* Set up the descriptors to be polled. */
201 		live_interfaces = 0;
202 		for (i = 0, l = protocols; l; l = l->next) {
203 			struct interface_info *ip = l->local;
204 
205 			if (ip == NULL || ip->dead)
206 				continue;
207 			fds[i].fd = l->fd;
208 			fds[i].events = POLLIN;
209 			fds[i].revents = 0;
210 			i++;
211 			if (l->handler == got_one)
212 				live_interfaces++;
213 		}
214 		if (live_interfaces == 0)
215 			error("No live interfaces to poll on - exiting.");
216 
217 		/* Wait for a packet or a timeout... XXX */
218 		count = poll(fds, nfds, to_msec);
219 
220 		/* Not likely to be transitory... */
221 		if (count == -1) {
222 			if (errno == EAGAIN || errno == EINTR) {
223 				time(&cur_time);
224 				continue;
225 			} else
226 				error("poll: %m");
227 		}
228 
229 		/* Get the current time... */
230 		time(&cur_time);
231 
232 		i = 0;
233 		for (l = protocols; l; l = l->next) {
234 			struct interface_info *ip;
235 			ip = l->local;
236 			if ((fds[i].revents & (POLLIN | POLLHUP))) {
237 				fds[i].revents = 0;
238 				if (ip && (l->handler != got_one ||
239 				    !ip->dead))
240 					(*(l->handler))(l);
241 				if (interfaces_invalidated)
242 					break;
243 			}
244 			i++;
245 		}
246 		interfaces_invalidated = 0;
247 	} while (1);
248 }
249 
250 
251 void
252 got_one(struct protocol *l)
253 {
254 	struct sockaddr_in from;
255 	struct hardware hfrom;
256 	struct iaddr ifrom;
257 	ssize_t result;
258 	union {
259 		/*
260 		 * Packet input buffer.  Must be as large as largest
261 		 * possible MTU.
262 		 */
263 		unsigned char packbuf[4095];
264 		struct dhcp_packet packet;
265 	} u;
266 	struct interface_info *ip = l->local;
267 
268 	if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
269 	    &hfrom)) == -1) {
270 		warning("receive_packet failed on %s: %s", ip->name,
271 		    strerror(errno));
272 		ip->errors++;
273 		if ((!interface_status(ip)) ||
274 		    (ip->noifmedia && ip->errors > 20)) {
275 			/* our interface has gone away. */
276 			warning("Interface %s no longer appears valid.",
277 			    ip->name);
278 			ip->dead = 1;
279 			interfaces_invalidated = 1;
280 			close(l->fd);
281 			remove_protocol(l);
282 			free(ip);
283 		}
284 		return;
285 	}
286 	if (result == 0)
287 		return;
288 
289 	if (bootp_packet_handler) {
290 		ifrom.len = 4;
291 		memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
292 
293 		(*bootp_packet_handler)(ip, &u.packet, result,
294 		    from.sin_port, ifrom, &hfrom);
295 	}
296 }
297 
298 int
299 interface_status(struct interface_info *ifinfo)
300 {
301 	char *ifname = ifinfo->name;
302 	int ifsock = ifinfo->rfdesc;
303 	struct ifreq ifr;
304 	struct ifmediareq ifmr;
305 
306 	/* get interface flags */
307 	memset(&ifr, 0, sizeof(ifr));
308 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
309 	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
310 		cap_syslog(capsyslog, LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
311 		    ifname);
312 		goto inactive;
313 	}
314 
315 	/*
316 	 * if one of UP and RUNNING flags is dropped,
317 	 * the interface is not active.
318 	 */
319 	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
320 		goto inactive;
321 
322 	/* Next, check carrier on the interface, if possible */
323 	if (ifinfo->noifmedia)
324 		goto active;
325 	memset(&ifmr, 0, sizeof(ifmr));
326 	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
327 	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
328 		if (errno != EINVAL) {
329 			cap_syslog(capsyslog, LOG_DEBUG,
330 			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
331 			ifinfo->noifmedia = 1;
332 			goto active;
333 		}
334 		/*
335 		 * EINVAL (or ENOTTY) simply means that the interface
336 		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
337 		 */
338 		ifinfo->noifmedia = 1;
339 		goto active;
340 	}
341 	if (ifmr.ifm_status & IFM_AVALID) {
342 		switch (ifmr.ifm_active & IFM_NMASK) {
343 		case IFM_ETHER:
344 		case IFM_IEEE80211:
345 			if (ifmr.ifm_status & IFM_ACTIVE)
346 				goto active;
347 			else
348 				goto inactive;
349 			break;
350 		default:
351 			goto inactive;
352 		}
353 	}
354 inactive:
355 	return (0);
356 active:
357 	return (1);
358 }
359 
360 void
361 add_timeout(time_t when, void (*where)(void *), void *what)
362 {
363 	struct timeout *t, *q;
364 
365 	/* See if this timeout supersedes an existing timeout. */
366 	t = NULL;
367 	for (q = timeouts; q; q = q->next) {
368 		if (q->func == where && q->what == what) {
369 			if (t)
370 				t->next = q->next;
371 			else
372 				timeouts = q->next;
373 			break;
374 		}
375 		t = q;
376 	}
377 
378 	/* If we didn't supersede a timeout, allocate a timeout
379 	   structure now. */
380 	if (!q) {
381 		if (free_timeouts) {
382 			q = free_timeouts;
383 			free_timeouts = q->next;
384 			q->func = where;
385 			q->what = what;
386 		} else {
387 			q = malloc(sizeof(struct timeout));
388 			if (!q)
389 				error("Can't allocate timeout structure!");
390 			q->func = where;
391 			q->what = what;
392 		}
393 	}
394 
395 	q->when = when;
396 
397 	/* Now sort this timeout into the timeout list. */
398 
399 	/* Beginning of list? */
400 	if (!timeouts || timeouts->when > q->when) {
401 		q->next = timeouts;
402 		timeouts = q;
403 		return;
404 	}
405 
406 	/* Middle of list? */
407 	for (t = timeouts; t->next; t = t->next) {
408 		if (t->next->when > q->when) {
409 			q->next = t->next;
410 			t->next = q;
411 			return;
412 		}
413 	}
414 
415 	/* End of list. */
416 	t->next = q;
417 	q->next = NULL;
418 }
419 
420 void
421 cancel_timeout(void (*where)(void *), void *what)
422 {
423 	struct timeout *t, *q;
424 
425 	/* Look for this timeout on the list, and unlink it if we find it. */
426 	t = NULL;
427 	for (q = timeouts; q; q = q->next) {
428 		if (q->func == where && q->what == what) {
429 			if (t)
430 				t->next = q->next;
431 			else
432 				timeouts = q->next;
433 			break;
434 		}
435 		t = q;
436 	}
437 
438 	/* If we found the timeout, put it on the free list. */
439 	if (q) {
440 		q->next = free_timeouts;
441 		free_timeouts = q;
442 	}
443 }
444 
445 /* Add a protocol to the list of protocols... */
446 void
447 add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
448     void *local)
449 {
450 	struct protocol *p;
451 
452 	p = malloc(sizeof(*p));
453 	if (!p)
454 		error("can't allocate protocol struct for %s", name);
455 
456 	p->fd = fd;
457 	p->handler = handler;
458 	p->local = local;
459 	p->next = protocols;
460 	protocols = p;
461 }
462 
463 void
464 remove_protocol(struct protocol *proto)
465 {
466 	struct protocol *p, *prev;
467 
468 	for (p = protocols, prev = NULL; p != NULL; prev = p, p = p->next) {
469 		if (p == proto) {
470 			if (prev == NULL)
471 				protocols = p->next;
472 			else
473 				prev->next = p->next;
474 			free(p);
475 			break;
476 		}
477 	}
478 }
479 
480 int
481 interface_link_status(char *ifname)
482 {
483 	struct ifmediareq ifmr;
484 	int sock;
485 
486 	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
487 		error("Can't create socket");
488 
489 	memset(&ifmr, 0, sizeof(ifmr));
490 	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
491 	if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
492 		/* EINVAL -> link state unknown. treat as active */
493 		if (errno != EINVAL)
494 			cap_syslog(capsyslog, LOG_DEBUG,
495 			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
496 		close(sock);
497 		return (1);
498 	}
499 	close(sock);
500 
501 	if (ifmr.ifm_status & IFM_AVALID) {
502 		switch (ifmr.ifm_active & IFM_NMASK) {
503 		case IFM_ETHER:
504 		case IFM_IEEE80211:
505 			if (ifmr.ifm_status & IFM_ACTIVE)
506 				return (1);
507 			else
508 				return (0);
509 		}
510 	}
511 	return (1);
512 }
513 
514 void
515 interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
516 {
517 	struct imsg_hdr hdr;
518 	struct buf *buf;
519 	int errs = 0;
520 
521 	hdr.code = IMSG_SET_INTERFACE_MTU;
522 	hdr.len = sizeof(hdr) +
523 		sizeof(u_int16_t);
524 
525 	if ((buf = buf_open(hdr.len)) == NULL)
526 		error("buf_open: %m");
527 
528 	errs += buf_add(buf, &hdr, sizeof(hdr));
529 	errs += buf_add(buf, &mtu, sizeof(mtu));
530 	if (errs)
531 		error("buf_add: %m");
532 
533 	if (buf_close(privfd, buf) == -1)
534 		error("buf_close: %m");
535 }
536 
537 void
538 interface_set_mtu_priv(char *ifname, u_int16_t mtu)
539 {
540 	struct ifreq ifr;
541 	int sock;
542 	u_int16_t old_mtu;
543 
544 	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
545 		error("Can't create socket");
546 
547 	memset(&ifr, 0, sizeof(ifr));
548 	old_mtu = 0;
549 
550 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
551 
552 	if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
553 		warning("SIOCGIFMTU failed (%s): %s", ifname,
554 			strerror(errno));
555 	else
556 		old_mtu = ifr.ifr_mtu;
557 
558 	if (mtu != old_mtu) {
559 		ifr.ifr_mtu = mtu;
560 
561 		if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
562 			warning("SIOCSIFMTU failed (%d): %s", mtu,
563 				strerror(errno));
564 	}
565 
566 	close(sock);
567 }
568