dispatch.c revision 1.8 
1/*	$OpenBSD: dispatch.c,v 1.8 2004/04/20 05:35:33 henning Exp $ */
2
3/*
4 * Copyright (c) 1995, 1996, 1997, 1998, 1999
5 * The Internet Software Consortium.   All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of The Internet Software Consortium nor the names
17 *    of its contributors may be used to endorse or promote products derived
18 *    from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
21 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
22 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
25 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
28 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
29 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * This software has been written for the Internet Software Consortium
35 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
36 * Enterprises.  To learn more about the Internet Software Consortium,
37 * see ``http://www.vix.com/isc''.  To learn more about Vixie
38 * Enterprises, see ``http://www.vix.com''.
39 */
40
41#include "dhcpd.h"
42#include <ifaddrs.h>
43#include <sys/ioctl.h>
44#include <poll.h>
45#include <net/if_media.h>
46
47
48/* Most boxes has less than 16 interfaces, so this might be a good guess.  */
49#define INITIAL_IFREQ_COUNT 16
50
51struct interface_info *interfaces, *dummy_interfaces, *fallback_interface;
52struct protocol *protocols;
53struct timeout *timeouts;
54static struct timeout *free_timeouts;
55static int interfaces_invalidated;
56void (*bootp_packet_handler)(struct interface_info *,
57    struct dhcp_packet *, int, unsigned int, struct iaddr, struct hardware *);
58
59static int interface_status(struct interface_info *ifinfo);
60
61int quiet_interface_discovery;
62
63/* Use getifaddrs() to get a list of all the attached interfaces.
64   For each interface that's of type INET and not the loopback interface,
65   register that interface with the network I/O software, figure out what
66   subnet it's on, and add it to the list of interfaces. */
67
68void
69discover_interfaces(int state)
70{
71	struct interface_info *tmp;
72	struct interface_info *last, *next;
73	struct subnet *subnet;
74	struct shared_network *share;
75	struct sockaddr_in foo;
76	int ir;
77	struct ifreq *tif;
78	struct ifaddrs *ifap, *ifa;
79#ifdef ALIAS_NAMES_PERMUTED
80	char *s;
81#endif
82
83	if (getifaddrs(&ifap) != 0)
84		error("getifaddrs failed");
85
86	/* If we already have a list of interfaces, and we're running as
87	   a DHCP server, the interfaces were requested. */
88	if (interfaces && (state == DISCOVER_SERVER ||
89	    state == DISCOVER_RELAY || state == DISCOVER_REQUESTED))
90		ir = 0;
91	else if (state == DISCOVER_UNCONFIGURED)
92		ir = INTERFACE_REQUESTED | INTERFACE_AUTOMATIC;
93	else
94		ir = INTERFACE_REQUESTED;
95
96	/* Cycle through the list of interfaces looking for IP addresses. */
97	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
98		/*
99		 * See if this is the sort of interface we want to
100		 * deal with.  Skip loopback, point-to-point and down
101		 * interfaces, except don't skip down interfaces if we're
102		 * trying to get a list of configurable interfaces.
103		 */
104		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
105		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
106		    (!(ifa->ifa_flags & IFF_UP) &&
107		    state != DISCOVER_UNCONFIGURED))
108			continue;
109
110		/* See if we've seen an interface that matches this one. */
111		for (tmp = interfaces; tmp; tmp = tmp->next)
112			if (!strcmp(tmp->name, ifa->ifa_name))
113				break;
114
115		/* If there isn't already an interface by this name,
116		   allocate one. */
117		if (!tmp) {
118			tmp = ((struct interface_info *)dmalloc(sizeof *tmp,
119			    "discover_interfaces"));
120			if (!tmp)
121				error("Insufficient memory to %s %s",
122				    "record interface", ifa->ifa_name);
123			strlcpy(tmp->name, ifa->ifa_name, sizeof(tmp->name));
124			tmp->next = interfaces;
125			tmp->flags = ir;
126			tmp->noifmedia = tmp->dead = tmp->errors = 0;
127			interfaces = tmp;
128		}
129
130		/* If we have the capability, extract link information
131		   and record it in a linked list. */
132		if (ifa->ifa_addr->sa_family == AF_LINK) {
133			struct sockaddr_dl *foo =
134			    ((struct sockaddr_dl *)(ifa->ifa_addr));
135			tmp->index = foo->sdl_index;
136			tmp->hw_address.hlen = foo->sdl_alen;
137			tmp->hw_address.htype = HTYPE_ETHER; /* XXX */
138			memcpy(tmp->hw_address.haddr,
139			    LLADDR(foo), foo->sdl_alen);
140		} else if (ifa->ifa_addr->sa_family == AF_INET) {
141			struct iaddr addr;
142
143			/* Get a pointer to the address... */
144			bcopy(ifa->ifa_addr, &foo, sizeof(foo));
145
146			/* We don't want the loopback interface. */
147			if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK))
148				continue;
149
150			/* If this is the first real IP address we've
151			   found, keep a pointer to ifreq structure in
152			   which we found it. */
153			if (!tmp->ifp) {
154				int len = (IFNAMSIZ + ifa->ifa_addr->sa_len);
155				tif = (struct ifreq *)malloc(len);
156				if (!tif)
157					error("no space to remember ifp.");
158				strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
159				memcpy(&tif->ifr_addr, ifa->ifa_addr,
160				    ifa->ifa_addr->sa_len);
161				tmp->ifp = tif;
162				tmp->primary_address = foo.sin_addr;
163			}
164
165			/* Grab the address... */
166			addr.len = 4;
167			memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len);
168
169			/* If there's a registered subnet for this address,
170			   connect it together... */
171			if ((subnet = find_subnet(addr))) {
172				/* If this interface has multiple aliases
173				   on the same subnet, ignore all but the
174				   first we encounter. */
175				if (!subnet->interface) {
176					subnet->interface = tmp;
177					subnet->interface_address = addr;
178				} else if (subnet->interface != tmp) {
179					warn("Multiple %s %s: %s %s",
180					    "interfaces match the",
181					    "same subnet",
182					    subnet->interface->name,
183					    tmp->name);
184				}
185				share = subnet->shared_network;
186				if (tmp->shared_network &&
187				    tmp->shared_network != share) {
188					warn("Interface %s matches %s",
189					    tmp->name,
190					    "multiple shared networks");
191				} else {
192					tmp->shared_network = share;
193				}
194
195				if (!share->interface) {
196					share->interface = tmp;
197				} else if (share->interface != tmp) {
198					warn("Multiple %s %s: %s %s",
199					    "interfaces match the",
200					    "same shared network",
201					    share->interface->name,
202					    tmp->name);
203				}
204			}
205		}
206	}
207
208	/* Now cycle through all the interfaces we found, looking for
209	   hardware addresses. */
210
211	/* If we're just trying to get a list of interfaces that we might
212	   be able to configure, we can quit now. */
213	if (state == DISCOVER_UNCONFIGURED)
214		return;
215
216	/* Weed out the interfaces that did not have IP addresses. */
217	last = NULL;
218	for (tmp = interfaces; tmp; tmp = next) {
219		next = tmp->next;
220		if ((tmp->flags & INTERFACE_AUTOMATIC) &&
221		    state == DISCOVER_REQUESTED)
222			tmp->flags &=
223			    ~(INTERFACE_AUTOMATIC | INTERFACE_REQUESTED);
224		if (!tmp->ifp || !(tmp->flags & INTERFACE_REQUESTED)) {
225			if ((tmp->flags & INTERFACE_REQUESTED) != ir)
226				error("%s: not found", tmp->name);
227			if (!last)
228				interfaces = interfaces->next;
229			else
230				last->next = tmp->next;
231
232			/* Remember the interface in case we need to know
233			   about it later. */
234			tmp->next = dummy_interfaces;
235			dummy_interfaces = tmp;
236			continue;
237		}
238		last = tmp;
239
240		memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr);
241
242		/* We must have a subnet declaration for each interface. */
243		if (!tmp->shared_network && (state == DISCOVER_SERVER)) {
244			warn("No subnet declaration for %s (%s).",
245			    tmp->name, inet_ntoa(foo.sin_addr));
246			warn("Please write a subnet declaration in your %s",
247			    "dhcpd.conf file for the");
248			error("network segment to which interface %s %s",
249			    tmp->name, "is attached.");
250		}
251
252		/* Find subnets that don't have valid interface
253		   addresses... */
254		for (subnet = (tmp->shared_network ? tmp->shared_network->subnets :
255		    NULL); subnet; subnet = subnet->next_sibling) {
256			if (!subnet->interface_address.len) {
257				/*
258				 * Set the interface address for this subnet
259				 * to the first address we found.
260				 */
261				subnet->interface_address.len = 4;
262				memcpy(subnet->interface_address.iabuf,
263				    &foo.sin_addr.s_addr, 4);
264			}
265		}
266
267		/* Register the interface... */
268		if_register_receive(tmp);
269		if_register_send(tmp);
270	}
271
272	/* Now register all the remaining interfaces as protocols. */
273	for (tmp = interfaces; tmp; tmp = tmp->next)
274		add_protocol(tmp->name, tmp->rfdesc, got_one, tmp);
275
276	freeifaddrs(ifap);
277}
278
279struct interface_info *
280setup_fallback(void)
281{
282	fallback_interface = ((struct interface_info *)dmalloc(
283	    sizeof *fallback_interface, "discover_interfaces"));
284
285	if (!fallback_interface)
286		error("Insufficient memory to record fallback interface.");
287	memset(fallback_interface, 0, sizeof *fallback_interface);
288	strlcpy(fallback_interface->name, "fallback", IFNAMSIZ);
289	fallback_interface->shared_network =
290	    new_shared_network("parse_statement");
291	if (!fallback_interface->shared_network)
292		error("No memory for shared subnet");
293	memset(fallback_interface->shared_network, 0,
294	    sizeof(struct shared_network));
295	fallback_interface->shared_network->name = "fallback-net";
296	return fallback_interface;
297}
298
299void
300reinitialize_interfaces(void)
301{
302	interfaces_invalidated = 1;
303}
304
305/*
306 * Wait for packets to come in using poll().  When a packet comes in,
307 * call receive_packet to receive the packet and possibly strip hardware
308 * addressing information from it, and then call through the
309 * bootp_packet_handler hook to try to do something with it.
310 */
311void
312dispatch(void)
313{
314	int count, i, nfds = 0, to_msec;
315	struct protocol *l;
316	struct pollfd *fds;
317	time_t howlong;
318
319	for (l = protocols; l; l = l->next)
320		++nfds;
321	fds = (struct pollfd *)malloc((nfds) * sizeof (struct pollfd));
322	if (fds == NULL)
323		error("Can't allocate poll structures.");
324
325	do {
326		/*
327		 * Call any expired timeouts, and then if there's
328		 * still a timeout registered, time out the select
329		 * call then.
330		 */
331another:
332		if (timeouts) {
333			struct timeout *t;
334
335			if (timeouts->when <= cur_time) {
336				t = timeouts;
337				timeouts = timeouts->next;
338				(*(t->func))(t->what);
339				t->next = free_timeouts;
340				free_timeouts = t;
341				goto another;
342			}
343
344			/*
345			 * Figure timeout in milliseconds, and check for
346			 * potential overflow, so we can cram into an int
347			 * for poll, while not polling with a negative
348			 * timeout and blocking indefinetely.
349			 */
350			howlong = timeouts->when - cur_time;
351			if (howlong > INT_MAX / 1000)
352				howlong = INT_MAX / 1000;
353			to_msec = howlong * 1000;
354		} else
355			to_msec = -1;
356
357		/* Set up the descriptors to be polled. */
358		i = 0;
359
360		for (l = protocols; l; l = l->next) {
361			struct interface_info *ip = l->local;
362
363			if (ip && (l->handler != got_one || !ip->dead)) {
364				fds[i].fd = l->fd;
365				fds[i].events = POLLIN;
366				fds[i].revents = 0;
367				++i;
368			}
369		}
370
371		if (i == 0)
372			error("No live interfaces to poll on - exiting.");
373
374		/* Wait for a packet or a timeout... XXX */
375		count = poll(fds, nfds, to_msec);
376
377		/* Not likely to be transitory... */
378		if (count == -1) {
379			if (errno == EAGAIN || errno == EINTR) {
380				time(&cur_time);
381				continue;
382			} else
383				error("poll: %m");
384		}
385
386		/* Get the current time... */
387		time(&cur_time);
388
389		i = 0;
390		for (l = protocols; l; l = l->next) {
391			struct interface_info *ip = l->local;
392
393			if ((fds[i].revents & POLLIN)) {
394				fds[i].revents = 0;
395				if (ip && (l->handler != got_one ||
396				    !ip->dead))
397					(*(l->handler))(l);
398				if (interfaces_invalidated)
399					break;
400			}
401			++i;
402		}
403		interfaces_invalidated = 0;
404	} while (1);
405}
406
407
408void
409got_one(struct protocol *l)
410{
411	struct sockaddr_in from;
412	struct hardware hfrom;
413	struct iaddr ifrom;
414	size_t result;
415	union {
416		unsigned char packbuf[4095];
417		struct dhcp_packet packet;
418	} u;
419	struct interface_info *ip = l->local;
420
421	if ((result = receive_packet (ip, u.packbuf, sizeof u,
422	    &from, &hfrom)) == -1) {
423		warn("receive_packet failed on %s: %s", ip->name,
424		    strerror(errno));
425		ip->errors++;
426		if ((!interface_status(ip)) ||
427		    (ip->noifmedia && ip->errors > 20)) {
428			/* our interface has gone away. */
429			warn("Interface %s no longer appears valid.",
430			    ip->name);
431			ip->dead = 1;
432			interfaces_invalidated = 1;
433			close(l->fd);
434			remove_protocol(l);
435			free(ip);
436		}
437		return;
438	}
439	if (result == 0)
440		return;
441
442	if (bootp_packet_handler) {
443		ifrom.len = 4;
444		memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
445
446		(*bootp_packet_handler)(ip, &u.packet, result,
447		    from.sin_port, ifrom, &hfrom);
448	}
449}
450
451int
452interface_status(struct interface_info *ifinfo)
453{
454	char * ifname = ifinfo->name;
455	int ifsock = ifinfo->rfdesc;
456	struct ifreq ifr;
457	struct ifmediareq ifmr;
458
459	/* get interface flags */
460	memset(&ifr, 0, sizeof(ifr));
461	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
462	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
463		syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname);
464		goto inactive;
465	}
466	/*
467	 * if one of UP and RUNNING flags is dropped,
468	 * the interface is not active.
469	 */
470	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
471		goto inactive;
472
473	/* Next, check carrier on the interface, if possible */
474	if (ifinfo->noifmedia)
475		goto active;
476	memset(&ifmr, 0, sizeof(ifmr));
477	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
478	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
479		if (errno != EINVAL) {
480			syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m",
481			    ifname);
482			ifinfo->noifmedia = 1;
483			goto active;
484		}
485		/*
486		 * EINVAL (or ENOTTY) simply means that the interface
487		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
488		 */
489		ifinfo->noifmedia = 1;
490		goto active;
491	}
492	if (ifmr.ifm_status & IFM_AVALID) {
493		switch (ifmr.ifm_active & IFM_NMASK) {
494		case IFM_ETHER:
495			if (ifmr.ifm_status & IFM_ACTIVE)
496				goto active;
497			else
498				goto inactive;
499			break;
500		default:
501			goto inactive;
502		}
503	}
504 inactive:
505	return (0);
506 active:
507	return (1);
508}
509
510int
511locate_network(struct packet *packet)
512{
513	struct iaddr ia;
514
515	/* If this came through a gateway, find the corresponding subnet... */
516	if (packet->raw->giaddr.s_addr) {
517		struct subnet *subnet;
518
519		ia.len = 4;
520		memcpy(ia.iabuf, &packet->raw->giaddr, 4);
521		subnet = find_subnet(ia);
522		if (subnet)
523			packet->shared_network = subnet->shared_network;
524		else
525			packet->shared_network = NULL;
526	} else {
527		packet->shared_network = packet->interface->shared_network;
528	}
529	if (packet->shared_network)
530		return 1;
531	return 0;
532}
533
534void
535add_timeout(time_t when, void (*where)(void *), void *what)
536{
537	struct timeout *t, *q;
538
539	/* See if this timeout supersedes an existing timeout. */
540	t = NULL;
541	for (q = timeouts; q; q = q->next) {
542		if (q->func == where && q->what == what) {
543			if (t)
544				t->next = q->next;
545			else
546				timeouts = q->next;
547			break;
548		}
549		t = q;
550	}
551
552	/* If we didn't supersede a timeout, allocate a timeout
553	   structure now. */
554	if (!q) {
555		if (free_timeouts) {
556			q = free_timeouts;
557			free_timeouts = q->next;
558			q->func = where;
559			q->what = what;
560		} else {
561			q = (struct timeout *)malloc(sizeof (struct timeout));
562			if (!q)
563				error("Can't allocate timeout structure!");
564			q->func = where;
565			q->what = what;
566		}
567	}
568
569	q->when = when;
570
571	/* Now sort this timeout into the timeout list. */
572
573	/* Beginning of list? */
574	if (!timeouts || timeouts->when > q->when) {
575		q->next = timeouts;
576		timeouts = q;
577		return;
578	}
579
580	/* Middle of list? */
581	for (t = timeouts; t->next; t = t->next) {
582		if (t->next->when > q->when) {
583			q->next = t->next;
584			t->next = q;
585			return;
586		}
587	}
588
589	/* End of list. */
590	t->next = q;
591	q->next = NULL;
592}
593
594void
595cancel_timeout(void (*where)(void *), void *what)
596{
597	struct timeout *t, *q;
598
599	/* Look for this timeout on the list, and unlink it if we find it. */
600	t = NULL;
601	for (q = timeouts; q; q = q->next) {
602		if (q->func == where && q->what == what) {
603			if (t)
604				t->next = q->next;
605			else
606				timeouts = q->next;
607			break;
608		}
609		t = q;
610	}
611
612	/* If we found the timeout, put it on the free list. */
613	if (q) {
614		q->next = free_timeouts;
615		free_timeouts = q;
616	}
617}
618
619/* Add a protocol to the list of protocols... */
620void
621add_protocol(char *name, int fd, void (*handler)(struct protocol *),
622    void *local)
623{
624	struct protocol *p;
625
626	p = (struct protocol *)malloc(sizeof *p);
627	if (!p)
628		error("can't allocate protocol struct for %s", name);
629	p->fd = fd;
630	p->handler = handler;
631	p->local = local;
632	p->next = protocols;
633	protocols = p;
634}
635
636void
637remove_protocol(struct protocol *proto)
638{
639	struct protocol *p, *next, *prev = NULL;
640
641	for (p = protocols; p; p = next) {
642		next = p->next;
643		if (p == proto) {
644			if (prev)
645				prev->next = p->next;
646			else
647				protocols = p->next;
648			free(p);
649		}
650	}
651}
652