dispatch.c revision 1.17 
1/*	$OpenBSD: dispatch.c,v 1.17 2006/03/16 15:44:40 claudio 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;
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
61/* Use getifaddrs() to get a list of all the attached interfaces.
62   For each interface that's of type INET and not the loopback interface,
63   register that interface with the network I/O software, figure out what
64   subnet it's on, and add it to the list of interfaces. */
65
66void
67discover_interfaces(int state)
68{
69	struct interface_info *tmp;
70	struct interface_info *last, *next;
71	struct subnet *subnet;
72	struct shared_network *share;
73	struct sockaddr_in foo;
74	int ir;
75	struct ifreq *tif;
76	struct ifaddrs *ifap, *ifa;
77#ifdef ALIAS_NAMES_PERMUTED
78	char *s;
79#endif
80
81	if (getifaddrs(&ifap) != 0)
82		error("getifaddrs failed");
83
84	/* If we already have a list of interfaces, and we're running as
85	   a DHCP server, the interfaces were requested. */
86	if (interfaces && (state == DISCOVER_SERVER ||
87	    state == DISCOVER_RELAY || state == DISCOVER_REQUESTED))
88		ir = 0;
89	else if (state == DISCOVER_UNCONFIGURED)
90		ir = INTERFACE_REQUESTED | INTERFACE_AUTOMATIC;
91	else
92		ir = INTERFACE_REQUESTED;
93
94	/* Cycle through the list of interfaces looking for IP addresses. */
95	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
96		/*
97		 * See if this is the sort of interface we want to
98		 * deal with.  Skip loopback, point-to-point and down
99		 * interfaces, except don't skip down interfaces if we're
100		 * trying to get a list of configurable interfaces.
101		 */
102		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
103		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
104		    (!(ifa->ifa_flags & IFF_UP) &&
105		    state != DISCOVER_UNCONFIGURED))
106			continue;
107
108		/* See if we've seen an interface that matches this one. */
109		for (tmp = interfaces; tmp; tmp = tmp->next)
110			if (!strcmp(tmp->name, ifa->ifa_name))
111				break;
112
113		/* If there isn't already an interface by this name,
114		   allocate one. */
115		if (!tmp) {
116			tmp = ((struct interface_info *)dmalloc(sizeof *tmp,
117			    "discover_interfaces"));
118			if (!tmp)
119				error("Insufficient memory to %s %s",
120				    "record interface", ifa->ifa_name);
121			strlcpy(tmp->name, ifa->ifa_name, sizeof(tmp->name));
122			tmp->next = interfaces;
123			tmp->flags = ir;
124			tmp->noifmedia = tmp->dead = tmp->errors = 0;
125			interfaces = tmp;
126		}
127
128		/* If we have the capability, extract link information
129		   and record it in a linked list. */
130		if (ifa->ifa_addr->sa_family == AF_LINK) {
131			struct sockaddr_dl *foo =
132			    ((struct sockaddr_dl *)(ifa->ifa_addr));
133			tmp->index = foo->sdl_index;
134			tmp->hw_address.hlen = foo->sdl_alen;
135			tmp->hw_address.htype = HTYPE_ETHER; /* XXX */
136			memcpy(tmp->hw_address.haddr,
137			    LLADDR(foo), foo->sdl_alen);
138		} else if (ifa->ifa_addr->sa_family == AF_INET) {
139			struct iaddr addr;
140
141			/* Get a pointer to the address... */
142			bcopy(ifa->ifa_addr, &foo, sizeof(foo));
143
144			/* We don't want the loopback interface. */
145			if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK))
146				continue;
147
148			/* If this is the first real IP address we've
149			   found, keep a pointer to ifreq structure in
150			   which we found it. */
151			if (!tmp->ifp) {
152				int len = (IFNAMSIZ + ifa->ifa_addr->sa_len);
153				tif = (struct ifreq *)malloc(len);
154				if (!tif)
155					error("no space to remember ifp.");
156				strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
157				memcpy(&tif->ifr_addr, ifa->ifa_addr,
158				    ifa->ifa_addr->sa_len);
159				tmp->ifp = tif;
160				tmp->primary_address = foo.sin_addr;
161			}
162
163			/* Grab the address... */
164			addr.len = 4;
165			memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len);
166
167			/* If there's a registered subnet for this address,
168			   connect it together... */
169			if ((subnet = find_subnet(addr))) {
170				/* If this interface has multiple aliases
171				   on the same subnet, ignore all but the
172				   first we encounter. */
173				if (!subnet->interface) {
174					subnet->interface = tmp;
175					subnet->interface_address = addr;
176				} else if (subnet->interface != tmp) {
177					warning("Multiple %s %s: %s %s",
178					    "interfaces match the",
179					    "same subnet",
180					    subnet->interface->name,
181					    tmp->name);
182				}
183				share = subnet->shared_network;
184				if (tmp->shared_network &&
185				    tmp->shared_network != share) {
186					warning("Interface %s matches %s",
187					    tmp->name,
188					    "multiple shared networks");
189				} else {
190					tmp->shared_network = share;
191				}
192
193				if (!share->interface) {
194					share->interface = tmp;
195				} else if (share->interface != tmp) {
196					warning("Multiple %s %s: %s %s",
197					    "interfaces match the",
198					    "same shared network",
199					    share->interface->name,
200					    tmp->name);
201				}
202			}
203		}
204	}
205
206	/* Now cycle through all the interfaces we found, looking for
207	   hardware addresses. */
208
209	/* If we're just trying to get a list of interfaces that we might
210	   be able to configure, we can quit now. */
211	if (state == DISCOVER_UNCONFIGURED)
212		return;
213
214	/* Weed out the interfaces that did not have IP addresses. */
215	last = NULL;
216	for (tmp = interfaces; tmp; tmp = next) {
217		next = tmp->next;
218		if ((tmp->flags & INTERFACE_AUTOMATIC) &&
219		    state == DISCOVER_REQUESTED)
220			tmp->flags &=
221			    ~(INTERFACE_AUTOMATIC | INTERFACE_REQUESTED);
222		if (!tmp->ifp || !(tmp->flags & INTERFACE_REQUESTED)) {
223			if ((tmp->flags & INTERFACE_REQUESTED) != ir)
224				error("%s: not found", tmp->name);
225			if (!last)
226				interfaces = interfaces->next;
227			else
228				last->next = tmp->next;
229
230			continue;
231		}
232		last = tmp;
233
234		memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr);
235
236		/* We must have a subnet declaration for each interface. */
237		if (!tmp->shared_network && (state == DISCOVER_SERVER)) {
238			warning("No subnet declaration for %s (%s).",
239			    tmp->name, inet_ntoa(foo.sin_addr));
240			warning("Please write a subnet declaration in your %s",
241			    "dhcpd.conf file for the");
242			error("network segment to which interface %s %s",
243			    tmp->name, "is attached.");
244		}
245
246		/* Find subnets that don't have valid interface
247		   addresses... */
248		for (subnet = (tmp->shared_network ? tmp->shared_network->subnets :
249		    NULL); subnet; subnet = subnet->next_sibling) {
250			if (!subnet->interface_address.len) {
251				/*
252				 * Set the interface address for this subnet
253				 * to the first address we found.
254				 */
255				subnet->interface_address.len = 4;
256				memcpy(subnet->interface_address.iabuf,
257				    &foo.sin_addr.s_addr, 4);
258			}
259		}
260
261		/* Register the interface... */
262		if_register_receive(tmp);
263		if_register_send(tmp);
264	}
265
266	/* Now register all the remaining interfaces as protocols. */
267	for (tmp = interfaces; tmp; tmp = tmp->next)
268		add_protocol(tmp->name, tmp->rfdesc, got_one, tmp);
269
270	freeifaddrs(ifap);
271}
272
273/*
274 * Wait for packets to come in using poll().  When a packet comes in,
275 * call receive_packet to receive the packet and possibly strip hardware
276 * addressing information from it, and then call through the
277 * bootp_packet_handler hook to try to do something with it.
278 */
279void
280dispatch(void)
281{
282	int nfds, i, to_msec;
283	struct protocol *l;
284	static struct pollfd *fds;
285	static int nfds_max;
286	time_t howlong;
287
288	for (nfds = 0, l = protocols; l; l = l->next)
289		nfds++;
290	if (nfds > nfds_max) {
291		fds = realloc(fds, nfds * sizeof(struct pollfd));
292		if (fds == NULL)
293			error("Can't allocate poll structures.");
294		nfds_max = nfds;
295	}
296
297	for (;;) {
298		/*
299		 * Call any expired timeouts, and then if there's
300		 * still a timeout registered, time out the poll
301		 * call then.
302		 */
303		time(&cur_time);
304another:
305		if (timeouts) {
306			if (timeouts->when <= cur_time) {
307				struct timeout *t = timeouts;
308				timeouts = timeouts->next;
309				(*(t->func))(t->what);
310				t->next = free_timeouts;
311				free_timeouts = t;
312				goto another;
313			}
314
315			/*
316			 * Figure timeout in milliseconds, and check for
317			 * potential overflow, so we can cram into an int
318			 * for poll, while not polling with a negative
319			 * timeout and blocking indefinitely.
320			 */
321			howlong = timeouts->when - cur_time;
322			if (howlong > INT_MAX / 1000)
323				howlong = INT_MAX / 1000;
324			to_msec = howlong * 1000;
325		} else
326			to_msec = -1;
327
328		/* Set up the descriptors to be polled. */
329		for (i = 0, l = protocols; l; l = l->next) {
330			struct interface_info *ip = l->local;
331
332			if (ip && (l->handler != got_one || !ip->dead)) {
333				fds[i].fd = l->fd;
334				fds[i].events = POLLIN;
335				++i;
336			}
337		}
338		if (i == 0)
339			error("No live interfaces to poll on - exiting.");
340
341		/* Wait for a packet or a timeout... */
342		switch (poll(fds, nfds, to_msec)) {
343		case -1:
344			if (errno != EAGAIN && errno != EINTR)
345				error("poll: %m");
346			/* FALLTHROUGH */
347		case 0:
348			continue;	/* no packets */
349		}
350
351		for (i = 0, l = protocols; l; l = l->next) {
352			struct interface_info *ip = l->local;
353
354			if ((fds[i].revents & (POLLIN | POLLHUP))) {
355				if (ip && (l->handler != got_one ||
356				    !ip->dead))
357					(*(l->handler))(l);
358				if (interfaces_invalidated)
359					break;
360			}
361			++i;
362		}
363		interfaces_invalidated = 0;
364	}
365}
366
367
368void
369got_one(struct protocol *l)
370{
371	struct sockaddr_in from;
372	struct hardware hfrom;
373	struct iaddr ifrom;
374	ssize_t result;
375	union {
376		unsigned char packbuf[4095];
377		struct dhcp_packet packet;
378	} u;
379	struct interface_info *ip = l->local;
380
381	if ((result = receive_packet(ip, u.packbuf, sizeof u,
382	    &from, &hfrom)) == -1) {
383		warning("receive_packet failed on %s: %s", ip->name,
384		    strerror(errno));
385		ip->errors++;
386		if ((!interface_status(ip)) ||
387		    (ip->noifmedia && ip->errors > 20)) {
388			/* our interface has gone away. */
389			warning("Interface %s no longer appears valid.",
390			    ip->name);
391			ip->dead = 1;
392			interfaces_invalidated = 1;
393			close(l->fd);
394			remove_protocol(l);
395			free(ip);
396		}
397		return;
398	}
399	if (result == 0)
400		return;
401
402	if (bootp_packet_handler) {
403		ifrom.len = 4;
404		memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
405
406		(*bootp_packet_handler)(ip, &u.packet, result,
407		    from.sin_port, ifrom, &hfrom);
408	}
409}
410
411int
412interface_status(struct interface_info *ifinfo)
413{
414	char * ifname = ifinfo->name;
415	int ifsock = ifinfo->rfdesc;
416	struct ifreq ifr;
417	struct ifmediareq ifmr;
418
419	/* get interface flags */
420	memset(&ifr, 0, sizeof(ifr));
421	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
422	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
423		syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname);
424		goto inactive;
425	}
426	/*
427	 * if one of UP and RUNNING flags is dropped,
428	 * the interface is not active.
429	 */
430	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
431		goto inactive;
432
433	/* Next, check carrier on the interface, if possible */
434	if (ifinfo->noifmedia)
435		goto active;
436	memset(&ifmr, 0, sizeof(ifmr));
437	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
438	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
439		if (errno != EINVAL) {
440			syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m",
441			    ifname);
442			ifinfo->noifmedia = 1;
443			goto active;
444		}
445		/*
446		 * EINVAL (or ENOTTY) simply means that the interface
447		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
448		 */
449		ifinfo->noifmedia = 1;
450		goto active;
451	}
452	if (ifmr.ifm_status & IFM_AVALID) {
453		switch (ifmr.ifm_active & IFM_NMASK) {
454		case IFM_ETHER:
455			if (ifmr.ifm_status & IFM_ACTIVE)
456				goto active;
457			else
458				goto inactive;
459			break;
460		default:
461			goto inactive;
462		}
463	}
464 inactive:
465	return (0);
466 active:
467	return (1);
468}
469
470int
471locate_network(struct packet *packet)
472{
473	struct iaddr ia;
474
475	/* If this came through a gateway, find the corresponding subnet... */
476	if (packet->raw->giaddr.s_addr) {
477		struct subnet *subnet;
478
479		ia.len = 4;
480		memcpy(ia.iabuf, &packet->raw->giaddr, 4);
481		subnet = find_subnet(ia);
482		if (subnet)
483			packet->shared_network = subnet->shared_network;
484		else
485			packet->shared_network = NULL;
486	} else {
487		packet->shared_network = packet->interface->shared_network;
488	}
489	if (packet->shared_network)
490		return 1;
491	return 0;
492}
493
494void
495add_timeout(time_t when, void (*where)(void *), void *what)
496{
497	struct timeout *t, *q;
498
499	/* See if this timeout supersedes an existing timeout. */
500	t = NULL;
501	for (q = timeouts; q; q = q->next) {
502		if (q->func == where && q->what == what) {
503			if (t)
504				t->next = q->next;
505			else
506				timeouts = q->next;
507			break;
508		}
509		t = q;
510	}
511
512	/* If we didn't supersede a timeout, allocate a timeout
513	   structure now. */
514	if (!q) {
515		if (free_timeouts) {
516			q = free_timeouts;
517			free_timeouts = q->next;
518			q->func = where;
519			q->what = what;
520		} else {
521			q = (struct timeout *)malloc(sizeof (struct timeout));
522			if (!q)
523				error("Can't allocate timeout structure!");
524			q->func = where;
525			q->what = what;
526		}
527	}
528
529	q->when = when;
530
531	/* Now sort this timeout into the timeout list. */
532
533	/* Beginning of list? */
534	if (!timeouts || timeouts->when > q->when) {
535		q->next = timeouts;
536		timeouts = q;
537		return;
538	}
539
540	/* Middle of list? */
541	for (t = timeouts; t->next; t = t->next) {
542		if (t->next->when > q->when) {
543			q->next = t->next;
544			t->next = q;
545			return;
546		}
547	}
548
549	/* End of list. */
550	t->next = q;
551	q->next = NULL;
552}
553
554void
555cancel_timeout(void (*where)(void *), void *what)
556{
557	struct timeout *t, *q;
558
559	/* Look for this timeout on the list, and unlink it if we find it. */
560	t = NULL;
561	for (q = timeouts; q; q = q->next) {
562		if (q->func == where && q->what == what) {
563			if (t)
564				t->next = q->next;
565			else
566				timeouts = q->next;
567			break;
568		}
569		t = q;
570	}
571
572	/* If we found the timeout, put it on the free list. */
573	if (q) {
574		q->next = free_timeouts;
575		free_timeouts = q;
576	}
577}
578
579/* Add a protocol to the list of protocols... */
580void
581add_protocol(char *name, int fd, void (*handler)(struct protocol *),
582    void *local)
583{
584	struct protocol *p;
585
586	p = (struct protocol *)malloc(sizeof *p);
587	if (!p)
588		error("can't allocate protocol struct for %s", name);
589	p->fd = fd;
590	p->handler = handler;
591	p->local = local;
592	p->next = protocols;
593	protocols = p;
594}
595
596void
597remove_protocol(struct protocol *proto)
598{
599	struct protocol *p, *next, *prev = NULL;
600
601	for (p = protocols; p; p = next) {
602		next = p->next;
603		if (p == proto) {
604			if (prev)
605				prev->next = p->next;
606			else
607				protocols = p->next;
608			free(p);
609		}
610	}
611}
612