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
76 struct protocol *protocols;
77 struct timeout *timeouts;
78 static struct timeout *free_timeouts;
79 static int interfaces_invalidated;
80
81 void (*bootp_packet_handler)(struct interface_info *,
82 void *, size_t, struct packet_ctx *);
83
84 static int interface_status(struct interface_info *ifinfo);
85
86 struct interface_info *
iflist_getbyindex(unsigned int index)87 iflist_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
101 struct interface_info *
iflist_getbyname(const char * name)102 iflist_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
116 struct interface_info *
iflist_getbyaddr6(struct in6_addr * addr)117 iflist_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
130 void
setup_iflist(void)131 setup_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
239 struct interface_info *
register_interface(const char * ifname,void (* handler)(struct protocol *))240 register_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 */
272 void
dispatch(void)273 dispatch(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 */
293 another:
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
370 void
got_one(struct protocol * l)371 got_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
403 int
interface_status(struct interface_info * ifinfo)404 interface_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 }
455 inactive:
456 return (0);
457 active:
458 return (1);
459 }
460
461 /* Add a protocol to the list of protocols... */
462 void
add_protocol(char * name,int fd,void (* handler)(struct protocol *),void * local)463 add_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
479 void
remove_protocol(struct protocol * proto)480 remove_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