dispatch.c revision 1.2 
1/*	$OpenBSD: dispatch.c,v 1.2 2021/01/17 13:41:24 claudio 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				TAILQ_REMOVE(&intflist, intf, entry);
173				free(intf);
174				continue;
175			}
176
177			intf->index = sdl->sdl_index;
178			intf->hw_address.hlen = sdl->sdl_alen;
179			memcpy(intf->hw_address.haddr,
180			    LLADDR(sdl), sdl->sdl_alen);
181		} else if (ifa->ifa_addr->sa_family == AF_INET) {
182			sin = (struct sockaddr_in *)ifa->ifa_addr;
183			if (sin->sin_addr.s_addr == htonl(INADDR_LOOPBACK) ||
184			    intf->primary_address.s_addr != INADDR_ANY)
185				continue;
186
187			intf->primary_address = sin->sin_addr;
188		} else if (ifa->ifa_addr->sa_family == AF_INET6) {
189			sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
190			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
191				intf->linklocal = sin6->sin6_addr;
192#ifdef __KAME__
193				/*
194				 * Remove possible scope from address if
195				 * link-local.
196				 */
197				intf->linklocal.s6_addr[2] = 0;
198				intf->linklocal.s6_addr[3] = 0;
199#endif
200			} else
201				intf->gipv6 = 1;
202
203			/* At least one IPv6 address was found. */
204			intf->ipv6 = 1;
205		}
206	}
207
208	freeifaddrs(ifap);
209
210	/*
211	 * Generate link-local IPv6 address for interfaces without it.
212	 *
213	 * For IPv6 DHCP Relay it doesn't matter what is used for
214	 * link-addr field, so let's generate an address that won't
215	 * change during execution so we can always find the interface
216	 * to relay packets back. This is only used for layer 2 relaying
217	 * when the interface might not have an address.
218	 */
219	TAILQ_FOREACH(intf, &intflist, entry) {
220		if (memcmp(&intf->linklocal, &in6addr_any,
221		    sizeof(in6addr_any)) != 0)
222			continue;
223
224		intf->linklocal.s6_addr[0] = 0xfe;
225		intf->linklocal.s6_addr[1] = 0x80;
226		intf->linklocal.s6_addr[8] = intf->hw_address.haddr[0];
227		intf->linklocal.s6_addr[9] = intf->hw_address.haddr[1];
228		intf->linklocal.s6_addr[10] = intf->hw_address.haddr[2];
229		intf->linklocal.s6_addr[11] = 0xff;
230		intf->linklocal.s6_addr[12] = 0xfe;
231		intf->linklocal.s6_addr[13] = intf->hw_address.haddr[3];
232		intf->linklocal.s6_addr[14] = intf->hw_address.haddr[4];
233		intf->linklocal.s6_addr[15] = intf->hw_address.haddr[5];
234		EUI64_TO_IFID(&intf->linklocal);
235	}
236}
237
238struct interface_info *
239register_interface(const char *ifname, void (*handler)(struct protocol *))
240{
241	struct interface_info		*intf;
242
243	if ((intf = iflist_getbyname(ifname)) == NULL)
244		return NULL;
245
246	/* Don't register disabled interfaces. */
247	if (intf->dead)
248		return NULL;
249
250	/* Check if we already registered the interface. */
251	if (intf->ifr.ifr_name[0] != 0)
252		return intf;
253
254	if (strlcpy(intf->ifr.ifr_name, ifname,
255	    sizeof(intf->ifr.ifr_name)) >= sizeof(intf->ifr.ifr_name))
256		fatalx("interface name '%s' too long", ifname);
257
258	if_register_receive(intf);
259	if_register_send(intf);
260	add_protocol(intf->name, intf->rfdesc, handler, intf);
261
262	return intf;
263}
264
265/*
266 * Wait for packets to come in using poll().  When a packet comes in,
267 * call receive_packet to receive the packet and possibly strip hardware
268 * addressing information from it, and then call through the
269 * bootp_packet_handler hook to try to do something with it.
270 */
271void
272dispatch(void)
273{
274	int count, i, to_msec, nfds = 0;
275	struct protocol *l;
276	struct pollfd *fds;
277	time_t howlong;
278
279	nfds = 0;
280	for (l = protocols; l; l = l->next)
281		nfds++;
282
283	fds = calloc(nfds, sizeof(struct pollfd));
284	if (fds == NULL)
285		fatalx("Can't allocate poll structures.");
286
287	do {
288		/*
289		 * Call any expired timeouts, and then if there's still
290		 * a timeout registered, time out the select call then.
291		 */
292another:
293		if (timeouts) {
294			if (timeouts->when <= cur_time) {
295				struct timeout *t = timeouts;
296
297				timeouts = timeouts->next;
298				(*(t->func))(t->what);
299				t->next = free_timeouts;
300				free_timeouts = t;
301				goto another;
302			}
303
304			/*
305			 * Figure timeout in milliseconds, and check for
306			 * potential overflow, so we can cram into an
307			 * int for poll, while not polling with a
308			 * negative timeout and blocking indefinitely.
309			 */
310			howlong = timeouts->when - cur_time;
311			if (howlong > INT_MAX / 1000)
312				howlong = INT_MAX / 1000;
313			to_msec = howlong * 1000;
314		} else
315			to_msec = -1;
316
317		/* Set up the descriptors to be polled. */
318		i = 0;
319
320		for (l = protocols; l; l = l->next) {
321			struct interface_info *ip = l->local;
322
323			if (ip && (l->handler != got_one || !ip->dead)) {
324				fds[i].fd = l->fd;
325				fds[i].events = POLLIN;
326				fds[i].revents = 0;
327				i++;
328			}
329		}
330
331		if (i == 0)
332			fatalx("No live interfaces to poll on - exiting.");
333
334		/* Wait for a packet or a timeout... XXX */
335		count = poll(fds, nfds, to_msec);
336
337		/* Not likely to be transitory... */
338		if (count == -1) {
339			if (errno == EAGAIN || errno == EINTR) {
340				time(&cur_time);
341				continue;
342			}
343			else
344				fatal("poll");
345		}
346
347		/* Get the current time... */
348		time(&cur_time);
349
350		i = 0;
351		for (l = protocols; l; l = l->next) {
352			struct interface_info *ip = l->local;
353
354			if ((fds[i].revents & (POLLIN | POLLHUP))) {
355				fds[i].revents = 0;
356				if (ip && (l->handler != got_one ||
357				    !ip->dead))
358					(*(l->handler))(l);
359				if (interfaces_invalidated)
360					break;
361			}
362			i++;
363		}
364		interfaces_invalidated = 0;
365	} while (1);
366}
367
368
369void
370got_one(struct protocol *l)
371{
372	struct packet_ctx pc;
373	ssize_t result;
374	uint8_t buf[4096];
375	struct interface_info *ip = l->local;
376
377	memset(&pc, 0, sizeof(pc));
378
379	if ((result = receive_packet(ip, buf, sizeof(buf), &pc)) == -1) {
380		log_warn("receive_packet failed on %s", ip->name);
381		ip->errors++;
382		if ((!interface_status(ip)) ||
383		    (ip->noifmedia && ip->errors > 20)) {
384			/* our interface has gone away. */
385			log_warnx("Interface %s no longer appears valid.",
386			    ip->name);
387			ip->dead = 1;
388			interfaces_invalidated = 1;
389			close(l->fd);
390			remove_protocol(l);
391			free(ip);
392		}
393		return;
394	}
395	if (result == 0)
396		return;
397
398	if (bootp_packet_handler)
399		(*bootp_packet_handler)(ip, buf, result, &pc);
400}
401
402int
403interface_status(struct interface_info *ifinfo)
404{
405	char *ifname = ifinfo->name;
406	int ifsock = ifinfo->rfdesc;
407	struct ifreq ifr;
408	struct ifmediareq ifmr;
409
410	/* get interface flags */
411	memset(&ifr, 0, sizeof(ifr));
412	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
413	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) {
414		log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname);
415		goto inactive;
416	}
417	/*
418	 * if one of UP and RUNNING flags is dropped,
419	 * the interface is not active.
420	 */
421	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
422		goto inactive;
423	}
424	/* Next, check carrier on the interface, if possible */
425	if (ifinfo->noifmedia)
426		goto active;
427	memset(&ifmr, 0, sizeof(ifmr));
428	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
429	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
430		if (errno != EINVAL) {
431			log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname);
432			ifinfo->noifmedia = 1;
433			goto active;
434		}
435		/*
436		 * EINVAL (or ENOTTY) simply means that the interface
437		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
438		 */
439		ifinfo->noifmedia = 1;
440		goto active;
441	}
442	if (ifmr.ifm_status & IFM_AVALID) {
443		switch (ifmr.ifm_active & IFM_NMASK) {
444		case IFM_ETHER:
445			if (ifmr.ifm_status & IFM_ACTIVE)
446				goto active;
447			else
448				goto inactive;
449			break;
450		default:
451			goto inactive;
452		}
453	}
454inactive:
455	return (0);
456active:
457	return (1);
458}
459
460/* Add a protocol to the list of protocols... */
461void
462add_protocol(char *name, int fd, void (*handler)(struct protocol *),
463    void *local)
464{
465	struct protocol *p;
466
467	p = malloc(sizeof(*p));
468	if (!p)
469		fatalx("can't allocate protocol struct for %s", name);
470
471	p->fd = fd;
472	p->handler = handler;
473	p->local = local;
474	p->next = protocols;
475	protocols = p;
476}
477
478void
479remove_protocol(struct protocol *proto)
480{
481	struct protocol *p, *next, *prev;
482
483	prev = NULL;
484	for (p = protocols; p; p = next) {
485		next = p->next;
486		if (p == proto) {
487			if (prev)
488				prev->next = p->next;
489			else
490				protocols = p->next;
491			free(p);
492		}
493	}
494}
495