dispatch.c revision 1.3 
1/*	$OpenBSD: dispatch.c,v 1.3 2023/07/14 07:09:00 gerhard Exp $	*/
2
3/*
4 * Copyright 2004 Henning Brauer <henning@openbsd.org>
5 * Copyright (c) 1995, 1996, 1997, 1998, 1999
6 * The Internet Software Consortium.   All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of The Internet Software Consortium nor the names
18 *    of its contributors may be used to endorse or promote products derived
19 *    from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
22 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
23 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
25 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
26 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
28 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
29 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
30 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * This software has been written for the Internet Software Consortium
36 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
37 * Enterprises.  To learn more about the Internet Software Consortium,
38 * see ``http://www.vix.com/isc''.  To learn more about Vixie
39 * Enterprises, see ``http://www.vix.com''.
40 */
41
42#include <sys/types.h>
43#include <sys/ioctl.h>
44#include <sys/socket.h>
45
46#include <net/if.h>
47#include <net/if_dl.h>
48#include <net/if_media.h>
49#include <net/if_types.h>
50
51#include <netinet/in.h>
52#include <netinet/if_ether.h>
53
54#include <errno.h>
55#include <ifaddrs.h>
56#include <limits.h>
57#include <poll.h>
58#include <stdlib.h>
59#include <string.h>
60#include <syslog.h>
61#include <time.h>
62#include <unistd.h>
63
64#include "dhcp.h"
65#include "dhcpd.h"
66#include "log.h"
67
68/*
69 * Macros implementation used to generate link-local addresses. This
70 * code was copied from: sys/netinet6/in6_ifattach.c.
71 */
72#define EUI64_UBIT		0x02
73#define EUI64_TO_IFID(in6) \
74	do { (in6)->s6_addr[8] ^= EUI64_UBIT; } while (0)
75
76struct protocol *protocols;
77struct timeout *timeouts;
78static struct timeout *free_timeouts;
79static int interfaces_invalidated;
80
81void (*bootp_packet_handler)(struct interface_info *,
82    void *, size_t, struct packet_ctx *);
83
84static int interface_status(struct interface_info *ifinfo);
85
86struct interface_info *
87iflist_getbyindex(unsigned int index)
88{
89	struct interface_info	*intf;
90
91	TAILQ_FOREACH(intf, &intflist, entry) {
92		if (intf->index != index)
93			continue;
94
95		return intf;
96	}
97
98	return NULL;
99}
100
101struct interface_info *
102iflist_getbyname(const char *name)
103{
104	struct interface_info	*intf;
105
106	TAILQ_FOREACH(intf, &intflist, entry) {
107		if (strcmp(intf->name, name) != 0)
108			continue;
109
110		return intf;
111	}
112
113	return NULL;
114}
115
116struct interface_info *
117iflist_getbyaddr6(struct in6_addr *addr)
118{
119	struct interface_info	*intf;
120
121	TAILQ_FOREACH(intf, &intflist, entry) {
122		/* Look for link-layer address. */
123		if (memcmp(&intf->linklocal, addr, sizeof(*addr)) == 0)
124			return intf;
125	}
126
127	return NULL;
128}
129
130void
131setup_iflist(void)
132{
133	struct interface_info		*intf;
134	struct sockaddr_dl		*sdl;
135	struct ifaddrs			*ifap, *ifa;
136	struct if_data			*ifi;
137	struct sockaddr_in		*sin;
138	struct sockaddr_in6		*sin6;
139
140	TAILQ_INIT(&intflist);
141	if (getifaddrs(&ifap))
142		fatalx("getifaddrs failed");
143
144	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
145		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
146		    (ifa->ifa_flags & IFF_POINTOPOINT))
147			continue;
148
149		/* Find interface or create it. */
150		intf = iflist_getbyname(ifa->ifa_name);
151		if (intf == NULL) {
152			intf = calloc(1, sizeof(*intf));
153			if (intf == NULL)
154				fatal("calloc");
155
156			strlcpy(intf->name, ifa->ifa_name,
157			    sizeof(intf->name));
158			TAILQ_INSERT_HEAD(&intflist, intf, entry);
159		}
160
161		/* Signal disabled interface. */
162		if ((ifa->ifa_flags & IFF_UP) == 0)
163			intf->dead = 1;
164
165		if (ifa->ifa_addr->sa_family == AF_LINK) {
166			sdl = (struct sockaddr_dl *)ifa->ifa_addr;
167			ifi = (struct if_data *)ifa->ifa_data;
168
169			/* Skip non ethernet interfaces. */
170			if (ifi->ifi_type != IFT_ETHER &&
171			    ifi->ifi_type != IFT_ENC &&
172			    ifi->ifi_type != IFT_CARP) {
173				TAILQ_REMOVE(&intflist, intf, entry);
174				free(intf);
175				continue;
176			}
177
178			intf->index = sdl->sdl_index;
179			intf->hw_address.hlen = sdl->sdl_alen;
180			memcpy(intf->hw_address.haddr,
181			    LLADDR(sdl), sdl->sdl_alen);
182		} else if (ifa->ifa_addr->sa_family == AF_INET) {
183			sin = (struct sockaddr_in *)ifa->ifa_addr;
184			if (sin->sin_addr.s_addr == htonl(INADDR_LOOPBACK) ||
185			    intf->primary_address.s_addr != INADDR_ANY)
186				continue;
187
188			intf->primary_address = sin->sin_addr;
189		} else if (ifa->ifa_addr->sa_family == AF_INET6) {
190			sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
191			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
192				intf->linklocal = sin6->sin6_addr;
193#ifdef __KAME__
194				/*
195				 * Remove possible scope from address if
196				 * link-local.
197				 */
198				intf->linklocal.s6_addr[2] = 0;
199				intf->linklocal.s6_addr[3] = 0;
200#endif
201			} else
202				intf->gipv6 = 1;
203
204			/* At least one IPv6 address was found. */
205			intf->ipv6 = 1;
206		}
207	}
208
209	freeifaddrs(ifap);
210
211	/*
212	 * Generate link-local IPv6 address for interfaces without it.
213	 *
214	 * For IPv6 DHCP Relay it doesn't matter what is used for
215	 * link-addr field, so let's generate an address that won't
216	 * change during execution so we can always find the interface
217	 * to relay packets back. This is only used for layer 2 relaying
218	 * when the interface might not have an address.
219	 */
220	TAILQ_FOREACH(intf, &intflist, entry) {
221		if (memcmp(&intf->linklocal, &in6addr_any,
222		    sizeof(in6addr_any)) != 0)
223			continue;
224
225		intf->linklocal.s6_addr[0] = 0xfe;
226		intf->linklocal.s6_addr[1] = 0x80;
227		intf->linklocal.s6_addr[8] = intf->hw_address.haddr[0];
228		intf->linklocal.s6_addr[9] = intf->hw_address.haddr[1];
229		intf->linklocal.s6_addr[10] = intf->hw_address.haddr[2];
230		intf->linklocal.s6_addr[11] = 0xff;
231		intf->linklocal.s6_addr[12] = 0xfe;
232		intf->linklocal.s6_addr[13] = intf->hw_address.haddr[3];
233		intf->linklocal.s6_addr[14] = intf->hw_address.haddr[4];
234		intf->linklocal.s6_addr[15] = intf->hw_address.haddr[5];
235		EUI64_TO_IFID(&intf->linklocal);
236	}
237}
238
239struct interface_info *
240register_interface(const char *ifname, void (*handler)(struct protocol *))
241{
242	struct interface_info		*intf;
243
244	if ((intf = iflist_getbyname(ifname)) == NULL)
245		return NULL;
246
247	/* Don't register disabled interfaces. */
248	if (intf->dead)
249		return NULL;
250
251	/* Check if we already registered the interface. */
252	if (intf->ifr.ifr_name[0] != 0)
253		return intf;
254
255	if (strlcpy(intf->ifr.ifr_name, ifname,
256	    sizeof(intf->ifr.ifr_name)) >= sizeof(intf->ifr.ifr_name))
257		fatalx("interface name '%s' too long", ifname);
258
259	if_register_receive(intf);
260	if_register_send(intf);
261	add_protocol(intf->name, intf->rfdesc, handler, intf);
262
263	return intf;
264}
265
266/*
267 * Wait for packets to come in using poll().  When a packet comes in,
268 * call receive_packet to receive the packet and possibly strip hardware
269 * addressing information from it, and then call through the
270 * bootp_packet_handler hook to try to do something with it.
271 */
272void
273dispatch(void)
274{
275	int count, i, to_msec, nfds = 0;
276	struct protocol *l;
277	struct pollfd *fds;
278	time_t howlong;
279
280	nfds = 0;
281	for (l = protocols; l; l = l->next)
282		nfds++;
283
284	fds = calloc(nfds, sizeof(struct pollfd));
285	if (fds == NULL)
286		fatalx("Can't allocate poll structures.");
287
288	do {
289		/*
290		 * Call any expired timeouts, and then if there's still
291		 * a timeout registered, time out the select call then.
292		 */
293another:
294		if (timeouts) {
295			if (timeouts->when <= cur_time) {
296				struct timeout *t = timeouts;
297
298				timeouts = timeouts->next;
299				(*(t->func))(t->what);
300				t->next = free_timeouts;
301				free_timeouts = t;
302				goto another;
303			}
304
305			/*
306			 * Figure timeout in milliseconds, and check for
307			 * potential overflow, so we can cram into an
308			 * int for poll, while not polling with a
309			 * negative timeout and blocking indefinitely.
310			 */
311			howlong = timeouts->when - cur_time;
312			if (howlong > INT_MAX / 1000)
313				howlong = INT_MAX / 1000;
314			to_msec = howlong * 1000;
315		} else
316			to_msec = -1;
317
318		/* Set up the descriptors to be polled. */
319		i = 0;
320
321		for (l = protocols; l; l = l->next) {
322			struct interface_info *ip = l->local;
323
324			if (ip && (l->handler != got_one || !ip->dead)) {
325				fds[i].fd = l->fd;
326				fds[i].events = POLLIN;
327				fds[i].revents = 0;
328				i++;
329			}
330		}
331
332		if (i == 0)
333			fatalx("No live interfaces to poll on - exiting.");
334
335		/* Wait for a packet or a timeout... XXX */
336		count = poll(fds, nfds, to_msec);
337
338		/* Not likely to be transitory... */
339		if (count == -1) {
340			if (errno == EAGAIN || errno == EINTR) {
341				time(&cur_time);
342				continue;
343			}
344			else
345				fatal("poll");
346		}
347
348		/* Get the current time... */
349		time(&cur_time);
350
351		i = 0;
352		for (l = protocols; l; l = l->next) {
353			struct interface_info *ip = l->local;
354
355			if ((fds[i].revents & (POLLIN | POLLHUP))) {
356				fds[i].revents = 0;
357				if (ip && (l->handler != got_one ||
358				    !ip->dead))
359					(*(l->handler))(l);
360				if (interfaces_invalidated)
361					break;
362			}
363			i++;
364		}
365		interfaces_invalidated = 0;
366	} while (1);
367}
368
369
370void
371got_one(struct protocol *l)
372{
373	struct packet_ctx pc;
374	ssize_t result;
375	uint8_t buf[4096];
376	struct interface_info *ip = l->local;
377
378	memset(&pc, 0, sizeof(pc));
379
380	if ((result = receive_packet(ip, buf, sizeof(buf), &pc)) == -1) {
381		log_warn("receive_packet failed on %s", ip->name);
382		ip->errors++;
383		if ((!interface_status(ip)) ||
384		    (ip->noifmedia && ip->errors > 20)) {
385			/* our interface has gone away. */
386			log_warnx("Interface %s no longer appears valid.",
387			    ip->name);
388			ip->dead = 1;
389			interfaces_invalidated = 1;
390			close(l->fd);
391			remove_protocol(l);
392			free(ip);
393		}
394		return;
395	}
396	if (result == 0)
397		return;
398
399	if (bootp_packet_handler)
400		(*bootp_packet_handler)(ip, buf, result, &pc);
401}
402
403int
404interface_status(struct interface_info *ifinfo)
405{
406	char *ifname = ifinfo->name;
407	int ifsock = ifinfo->rfdesc;
408	struct ifreq ifr;
409	struct ifmediareq ifmr;
410
411	/* get interface flags */
412	memset(&ifr, 0, sizeof(ifr));
413	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
414	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) {
415		log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname);
416		goto inactive;
417	}
418	/*
419	 * if one of UP and RUNNING flags is dropped,
420	 * the interface is not active.
421	 */
422	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
423		goto inactive;
424	}
425	/* Next, check carrier on the interface, if possible */
426	if (ifinfo->noifmedia)
427		goto active;
428	memset(&ifmr, 0, sizeof(ifmr));
429	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
430	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
431		if (errno != EINVAL) {
432			log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname);
433			ifinfo->noifmedia = 1;
434			goto active;
435		}
436		/*
437		 * EINVAL (or ENOTTY) simply means that the interface
438		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
439		 */
440		ifinfo->noifmedia = 1;
441		goto active;
442	}
443	if (ifmr.ifm_status & IFM_AVALID) {
444		switch (ifmr.ifm_active & IFM_NMASK) {
445		case IFM_ETHER:
446			if (ifmr.ifm_status & IFM_ACTIVE)
447				goto active;
448			else
449				goto inactive;
450			break;
451		default:
452			goto inactive;
453		}
454	}
455inactive:
456	return (0);
457active:
458	return (1);
459}
460
461/* Add a protocol to the list of protocols... */
462void
463add_protocol(char *name, int fd, void (*handler)(struct protocol *),
464    void *local)
465{
466	struct protocol *p;
467
468	p = malloc(sizeof(*p));
469	if (!p)
470		fatalx("can't allocate protocol struct for %s", name);
471
472	p->fd = fd;
473	p->handler = handler;
474	p->local = local;
475	p->next = protocols;
476	protocols = p;
477}
478
479void
480remove_protocol(struct protocol *proto)
481{
482	struct protocol *p, *next, *prev;
483
484	prev = NULL;
485	for (p = protocols; p; p = next) {
486		next = p->next;
487		if (p == proto) {
488			if (prev)
489				prev->next = p->next;
490			else
491				protocols = p->next;
492			free(p);
493		}
494	}
495}
496