xref: /freebsd/sbin/dhclient/dispatch.c (revision f39bffc62c1395bde25d152c7f68fdf7cbaab414) 
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 struct protocol *protocols;
61 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 
82 	if (getifaddrs(&ifap) != 0)
83 		error("getifaddrs failed");
84 
85 	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
86 		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
87 		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
88 		    (!(ifa->ifa_flags & IFF_UP)))
89 			continue;
90 
91 		if (strcmp(iface->name, ifa->ifa_name))
92 			continue;
93 
94 		/*
95 		 * If we have the capability, extract link information
96 		 * and record it in a linked list.
97 		 */
98 		if (ifa->ifa_addr->sa_family == AF_LINK) {
99 			struct sockaddr_dl *foo;
100 
101 			/*
102 			 * The implementation of getifaddrs should guarantee
103 			 * this alignment
104 			 */
105 			assert_aligned(ifa->ifa_addr,
106 				       _Alignof(struct sockaddr_dl));
107 #ifdef __clang__
108 #pragma clang diagnostic push
109 #pragma clang diagnostic ignored "-Wcast-align"
110 #endif
111 			foo = (struct sockaddr_dl *)ifa->ifa_addr;
112 #ifdef __clang__
113 #pragma clang diagnostic pop
114 #endif
115 
116 			iface->index = foo->sdl_index;
117 			iface->hw_address.hlen = foo->sdl_alen;
118 			iface->hw_address.htype = HTYPE_ETHER; /* XXX */
119 			memcpy(iface->hw_address.haddr,
120 			    LLADDR(foo), foo->sdl_alen);
121 		} else if (ifa->ifa_addr->sa_family == AF_INET) {
122 			struct sockaddr_in foo;
123 			struct iaddr addr;
124 
125 			memcpy(&foo, ifa->ifa_addr, sizeof(foo));
126 			if (foo.sin_addr.s_addr == htonl(INADDR_LOOPBACK))
127 				continue;
128 			if (!iface->ifp) {
129 				if ((tif = calloc(1, sizeof(struct ifreq)))
130 				    == NULL)
131 					error("no space to remember ifp");
132 				strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
133 				memcpy(&tif->ifr_addr, ifa->ifa_addr,
134 				    ifa->ifa_addr->sa_len);
135 				iface->ifp = tif;
136 				iface->primary_address = foo.sin_addr;
137 			}
138 			addr.len = 4;
139 			memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len);
140 		}
141 	}
142 
143 	if (!iface->ifp)
144 		error("%s: not found", iface->name);
145 
146 	/* Register the interface... */
147 	if_register_receive(iface);
148 	if_register_send(iface);
149 	add_protocol(iface->name, iface->rfdesc, got_one, iface);
150 	freeifaddrs(ifap);
151 }
152 
153 void
154 reinitialize_interfaces(void)
155 {
156 	interfaces_invalidated = 1;
157 }
158 
159 /*
160  * Wait for packets to come in using poll().  When a packet comes in,
161  * call receive_packet to receive the packet and possibly strip hardware
162  * addressing information from it, and then call through the
163  * bootp_packet_handler hook to try to do something with it.
164  */
165 void
166 dispatch(void)
167 {
168 	int count, live_interfaces, i, to_msec, nfds = 0;
169 	struct protocol *l;
170 	struct pollfd *fds;
171 	time_t howlong;
172 
173 	for (l = protocols; l; l = l->next)
174 		nfds++;
175 
176 	fds = malloc(nfds * sizeof(struct pollfd));
177 	if (fds == NULL)
178 		error("Can't allocate poll structures.");
179 
180 	do {
181 		/*
182 		 * Call any expired timeouts, and then if there's still
183 		 * a timeout registered, time out the select call then.
184 		 */
185 another:
186 		if (timeouts) {
187 			struct timeout *t;
188 
189 			if (timeouts->when <= cur_time) {
190 				t = timeouts;
191 				timeouts = timeouts->next;
192 				(*(t->func))(t->what);
193 				t->next = free_timeouts;
194 				free_timeouts = t;
195 				goto another;
196 			}
197 
198 			/*
199 			 * Figure timeout in milliseconds, and check for
200 			 * potential overflow, so we can cram into an
201 			 * int for poll, while not polling with a
202 			 * negative timeout and blocking indefinitely.
203 			 */
204 			howlong = timeouts->when - cur_time;
205 			if (howlong > INT_MAX / 1000)
206 				howlong = INT_MAX / 1000;
207 			to_msec = howlong * 1000;
208 		} else
209 			to_msec = -1;
210 
211 		/* Set up the descriptors to be polled. */
212 		live_interfaces = 0;
213 		for (i = 0, l = protocols; l; l = l->next) {
214 			struct interface_info *ip = l->local;
215 
216 			if (ip == NULL || ip->dead)
217 				continue;
218 			fds[i].fd = l->fd;
219 			fds[i].events = POLLIN;
220 			fds[i].revents = 0;
221 			i++;
222 			if (l->handler == got_one)
223 				live_interfaces++;
224 		}
225 		if (live_interfaces == 0)
226 			error("No live interfaces to poll on - exiting.");
227 
228 		/* Wait for a packet or a timeout... XXX */
229 		count = poll(fds, nfds, to_msec);
230 
231 		/* Not likely to be transitory... */
232 		if (count == -1) {
233 			if (errno == EAGAIN || errno == EINTR) {
234 				time(&cur_time);
235 				continue;
236 			} else
237 				error("poll: %m");
238 		}
239 
240 		/* Get the current time... */
241 		time(&cur_time);
242 
243 		i = 0;
244 		for (l = protocols; l; l = l->next) {
245 			struct interface_info *ip;
246 			ip = l->local;
247 			if ((fds[i].revents & (POLLIN | POLLHUP))) {
248 				fds[i].revents = 0;
249 				if (ip && (l->handler != got_one ||
250 				    !ip->dead))
251 					(*(l->handler))(l);
252 				if (interfaces_invalidated)
253 					break;
254 			}
255 			i++;
256 		}
257 		interfaces_invalidated = 0;
258 	} while (1);
259 }
260 
261 
262 void
263 got_one(struct protocol *l)
264 {
265 	struct sockaddr_in from;
266 	struct hardware hfrom;
267 	struct iaddr ifrom;
268 	ssize_t result;
269 	union {
270 		/*
271 		 * Packet input buffer.  Must be as large as largest
272 		 * possible MTU.
273 		 */
274 		unsigned char packbuf[4095];
275 		struct dhcp_packet packet;
276 	} u;
277 	struct interface_info *ip = l->local;
278 
279 	if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
280 	    &hfrom)) == -1) {
281 		warning("receive_packet failed on %s: %s", ip->name,
282 		    strerror(errno));
283 		ip->errors++;
284 		if ((!interface_status(ip)) ||
285 		    (ip->noifmedia && ip->errors > 20)) {
286 			/* our interface has gone away. */
287 			warning("Interface %s no longer appears valid.",
288 			    ip->name);
289 			ip->dead = 1;
290 			interfaces_invalidated = 1;
291 			close(l->fd);
292 			remove_protocol(l);
293 			free(ip);
294 		}
295 		return;
296 	}
297 	if (result == 0)
298 		return;
299 
300 	if (bootp_packet_handler) {
301 		ifrom.len = 4;
302 		memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
303 
304 		(*bootp_packet_handler)(ip, &u.packet, result,
305 		    from.sin_port, ifrom, &hfrom);
306 	}
307 }
308 
309 int
310 interface_status(struct interface_info *ifinfo)
311 {
312 	char *ifname = ifinfo->name;
313 	int ifsock = ifinfo->rfdesc;
314 	struct ifreq ifr;
315 	struct ifmediareq ifmr;
316 
317 	/* get interface flags */
318 	memset(&ifr, 0, sizeof(ifr));
319 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
320 	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
321 		cap_syslog(capsyslog, LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
322 		    ifname);
323 		goto inactive;
324 	}
325 
326 	/*
327 	 * if one of UP and RUNNING flags is dropped,
328 	 * the interface is not active.
329 	 */
330 	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
331 		goto inactive;
332 
333 	/* Next, check carrier on the interface, if possible */
334 	if (ifinfo->noifmedia)
335 		goto active;
336 	memset(&ifmr, 0, sizeof(ifmr));
337 	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
338 	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
339 		if (errno != EINVAL) {
340 			cap_syslog(capsyslog, LOG_DEBUG,
341 			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
342 			ifinfo->noifmedia = 1;
343 			goto active;
344 		}
345 		/*
346 		 * EINVAL (or ENOTTY) simply means that the interface
347 		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
348 		 */
349 		ifinfo->noifmedia = 1;
350 		goto active;
351 	}
352 	if (ifmr.ifm_status & IFM_AVALID) {
353 		switch (ifmr.ifm_active & IFM_NMASK) {
354 		case IFM_ETHER:
355 		case IFM_IEEE80211:
356 			if (ifmr.ifm_status & IFM_ACTIVE)
357 				goto active;
358 			else
359 				goto inactive;
360 			break;
361 		default:
362 			goto inactive;
363 		}
364 	}
365 inactive:
366 	return (0);
367 active:
368 	return (1);
369 }
370 
371 void
372 add_timeout(time_t when, void (*where)(void *), void *what)
373 {
374 	struct timeout *t, *q;
375 
376 	/* See if this timeout supersedes an existing timeout. */
377 	t = NULL;
378 	for (q = timeouts; q; q = q->next) {
379 		if (q->func == where && q->what == what) {
380 			if (t)
381 				t->next = q->next;
382 			else
383 				timeouts = q->next;
384 			break;
385 		}
386 		t = q;
387 	}
388 
389 	/* If we didn't supersede a timeout, allocate a timeout
390 	   structure now. */
391 	if (!q) {
392 		if (free_timeouts) {
393 			q = free_timeouts;
394 			free_timeouts = q->next;
395 			q->func = where;
396 			q->what = what;
397 		} else {
398 			q = malloc(sizeof(struct timeout));
399 			if (!q)
400 				error("Can't allocate timeout structure!");
401 			q->func = where;
402 			q->what = what;
403 		}
404 	}
405 
406 	q->when = when;
407 
408 	/* Now sort this timeout into the timeout list. */
409 
410 	/* Beginning of list? */
411 	if (!timeouts || timeouts->when > q->when) {
412 		q->next = timeouts;
413 		timeouts = q;
414 		return;
415 	}
416 
417 	/* Middle of list? */
418 	for (t = timeouts; t->next; t = t->next) {
419 		if (t->next->when > q->when) {
420 			q->next = t->next;
421 			t->next = q;
422 			return;
423 		}
424 	}
425 
426 	/* End of list. */
427 	t->next = q;
428 	q->next = NULL;
429 }
430 
431 void
432 cancel_timeout(void (*where)(void *), void *what)
433 {
434 	struct timeout *t, *q;
435 
436 	/* Look for this timeout on the list, and unlink it if we find it. */
437 	t = NULL;
438 	for (q = timeouts; q; q = q->next) {
439 		if (q->func == where && q->what == what) {
440 			if (t)
441 				t->next = q->next;
442 			else
443 				timeouts = q->next;
444 			break;
445 		}
446 		t = q;
447 	}
448 
449 	/* If we found the timeout, put it on the free list. */
450 	if (q) {
451 		q->next = free_timeouts;
452 		free_timeouts = q;
453 	}
454 }
455 
456 /* Add a protocol to the list of protocols... */
457 void
458 add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
459     void *local)
460 {
461 	struct protocol *p;
462 
463 	p = malloc(sizeof(*p));
464 	if (!p)
465 		error("can't allocate protocol struct for %s", name);
466 
467 	p->fd = fd;
468 	p->handler = handler;
469 	p->local = local;
470 	p->next = protocols;
471 	protocols = p;
472 }
473 
474 void
475 remove_protocol(struct protocol *proto)
476 {
477 	struct protocol *p, *next;
478 
479 	for (p = protocols; p; p = next) {
480 		next = p->next;
481 		if (p == proto) {
482 			protocols = p->next;
483 			free(p);
484 		}
485 	}
486 }
487 
488 int
489 interface_link_status(char *ifname)
490 {
491 	struct ifmediareq ifmr;
492 	int sock;
493 
494 	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
495 		error("Can't create socket");
496 
497 	memset(&ifmr, 0, sizeof(ifmr));
498 	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
499 	if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
500 		/* EINVAL -> link state unknown. treat as active */
501 		if (errno != EINVAL)
502 			cap_syslog(capsyslog, LOG_DEBUG,
503 			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
504 		close(sock);
505 		return (1);
506 	}
507 	close(sock);
508 
509 	if (ifmr.ifm_status & IFM_AVALID) {
510 		switch (ifmr.ifm_active & IFM_NMASK) {
511 		case IFM_ETHER:
512 		case IFM_IEEE80211:
513 			if (ifmr.ifm_status & IFM_ACTIVE)
514 				return (1);
515 			else
516 				return (0);
517 		}
518 	}
519 	return (1);
520 }
521 
522 void
523 interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
524 {
525 	struct imsg_hdr hdr;
526 	struct buf *buf;
527 	int errs = 0;
528 
529 	hdr.code = IMSG_SET_INTERFACE_MTU;
530 	hdr.len = sizeof(hdr) +
531 		sizeof(u_int16_t);
532 
533 	if ((buf = buf_open(hdr.len)) == NULL)
534 		error("buf_open: %m");
535 
536 	errs += buf_add(buf, &hdr, sizeof(hdr));
537 	errs += buf_add(buf, &mtu, sizeof(mtu));
538 	if (errs)
539 		error("buf_add: %m");
540 
541 	if (buf_close(privfd, buf) == -1)
542 		error("buf_close: %m");
543 }
544 
545 void
546 interface_set_mtu_priv(char *ifname, u_int16_t mtu)
547 {
548 	struct ifreq ifr;
549 	int sock;
550 
551 	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
552 		error("Can't create socket");
553 
554 	memset(&ifr, 0, sizeof(ifr));
555 
556 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
557 	ifr.ifr_mtu = mtu;
558 
559 	if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
560 		warning("SIOCSIFMTU failed (%d): %s", mtu,
561 			strerror(errno));
562 	close(sock);
563 }
564