FreeBSD/Linux Kernel Cross Reference
sys/netinet/igmp.c
1 /*-
2 * Copyright (c) 1988 Stephen Deering.
3 * Copyright (c) 1992, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Stephen Deering of Stanford University.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
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 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)igmp.c 8.1 (Berkeley) 7/19/93
34 * $FreeBSD$
35 */
36
37 /*
38 * Internet Group Management Protocol (IGMP) routines.
39 *
40 * Written by Steve Deering, Stanford, May 1988.
41 * Modified by Rosen Sharma, Stanford, Aug 1994.
42 * Modified by Bill Fenner, Xerox PARC, Feb 1995.
43 * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
44 *
45 * MULTICAST Revision: 3.5.1.4
46 */
47
48 #include "opt_mac.h"
49
50 #include <sys/param.h>
51 #include <sys/systm.h>
52 #include <sys/mac.h>
53 #include <sys/malloc.h>
54 #include <sys/mbuf.h>
55 #include <sys/socket.h>
56 #include <sys/protosw.h>
57 #include <sys/kernel.h>
58 #include <sys/sysctl.h>
59
60 #include <net/if.h>
61 #include <net/route.h>
62
63 #include <netinet/in.h>
64 #include <netinet/in_var.h>
65 #include <netinet/in_systm.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_var.h>
68 #include <netinet/igmp.h>
69 #include <netinet/igmp_var.h>
70
71 #include <machine/in_cksum.h>
72
73 static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");
74
75 static struct router_info *find_rti(struct ifnet *ifp);
76 static void igmp_sendpkt(struct in_multi *, int, unsigned long);
77
78 static struct igmpstat igmpstat;
79
80 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, &igmpstat,
81 igmpstat, "");
82
83 /*
84 * igmp_mtx protects all mutable global variables in igmp.c, as well as
85 * the data fields in struct router_info. In general, a router_info
86 * structure will be valid as long as the referencing struct in_multi is
87 * valid, so no reference counting is used. We allow unlocked reads of
88 * router_info data when accessed via an in_multi read-only.
89 */
90 static struct mtx igmp_mtx;
91 static SLIST_HEAD(, router_info) router_info_head;
92 static int igmp_timers_are_running;
93
94 /*
95 * XXXRW: can we define these such that these can be made const? In any
96 * case, these shouldn't be changed after igmp_init() and therefore don't
97 * need locking.
98 */
99 static u_long igmp_all_hosts_group;
100 static u_long igmp_all_rtrs_group;
101
102 static struct mbuf *router_alert;
103 static struct route igmprt;
104
105 #ifdef IGMP_DEBUG
106 #define IGMP_PRINTF(x) printf(x)
107 #else
108 #define IGMP_PRINTF(x)
109 #endif
110
111 void
112 igmp_init(void)
113 {
114 struct ipoption *ra;
115
116 /*
117 * To avoid byte-swapping the same value over and over again.
118 */
119 igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
120 igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);
121
122 igmp_timers_are_running = 0;
123
124 /*
125 * Construct a Router Alert option to use in outgoing packets
126 */
127 MGET(router_alert, M_DONTWAIT, MT_DATA);
128 ra = mtod(router_alert, struct ipoption *);
129 ra->ipopt_dst.s_addr = 0;
130 ra->ipopt_list[0] = IPOPT_RA; /* Router Alert Option */
131 ra->ipopt_list[1] = 0x04; /* 4 bytes long */
132 ra->ipopt_list[2] = 0x00;
133 ra->ipopt_list[3] = 0x00;
134 router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];
135
136 mtx_init(&igmp_mtx, "igmp_mtx", NULL, MTX_DEF);
137 SLIST_INIT(&router_info_head);
138 }
139
140 static struct router_info *
141 find_rti(struct ifnet *ifp)
142 {
143 struct router_info *rti;
144
145 mtx_assert(&igmp_mtx, MA_OWNED);
146 IGMP_PRINTF("[igmp.c, _find_rti] --> entering \n");
147 SLIST_FOREACH(rti, &router_info_head, rti_list) {
148 if (rti->rti_ifp == ifp) {
149 IGMP_PRINTF(
150 "[igmp.c, _find_rti] --> found old entry \n");
151 return rti;
152 }
153 }
154 /*
155 * XXXRW: return value of malloc not checked, despite M_NOWAIT.
156 */
157 MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT);
158 rti->rti_ifp = ifp;
159 rti->rti_type = IGMP_V2_ROUTER;
160 rti->rti_time = 0;
161 SLIST_INSERT_HEAD(&router_info_head, rti, rti_list);
162
163 IGMP_PRINTF("[igmp.c, _find_rti] --> created an entry \n");
164 return rti;
165 }
166
167 void
168 igmp_input(register struct mbuf *m, int off)
169 {
170 register int iphlen = off;
171 register struct igmp *igmp;
172 register struct ip *ip;
173 register int igmplen;
174 register struct ifnet *ifp = m->m_pkthdr.rcvif;
175 register int minlen;
176 register struct in_multi *inm;
177 register struct in_ifaddr *ia;
178 struct in_multistep step;
179 struct router_info *rti;
180 int timer; /** timer value in the igmp query header **/
181
182 ++igmpstat.igps_rcv_total;
183
184 ip = mtod(m, struct ip *);
185 igmplen = ip->ip_len;
186
187 /*
188 * Validate lengths
189 */
190 if (igmplen < IGMP_MINLEN) {
191 ++igmpstat.igps_rcv_tooshort;
192 m_freem(m);
193 return;
194 }
195 minlen = iphlen + IGMP_MINLEN;
196 if ((m->m_flags & M_EXT || m->m_len < minlen) &&
197 (m = m_pullup(m, minlen)) == 0) {
198 ++igmpstat.igps_rcv_tooshort;
199 return;
200 }
201
202 /*
203 * Validate checksum
204 */
205 m->m_data += iphlen;
206 m->m_len -= iphlen;
207 igmp = mtod(m, struct igmp *);
208 if (in_cksum(m, igmplen)) {
209 ++igmpstat.igps_rcv_badsum;
210 m_freem(m);
211 return;
212 }
213 m->m_data -= iphlen;
214 m->m_len += iphlen;
215
216 ip = mtod(m, struct ip *);
217 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
218 if (timer == 0)
219 timer = 1;
220
221 /*
222 * In the IGMPv2 specification, there are 3 states and a flag.
223 *
224 * In Non-Member state, we simply don't have a membership record.
225 * In Delaying Member state, our timer is running (inm->inm_timer)
226 * In Idle Member state, our timer is not running (inm->inm_timer==0)
227 *
228 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
229 * we have heard a report from another member, or IGMP_IREPORTEDLAST
230 * if I sent the last report.
231 */
232 switch (igmp->igmp_type) {
233 case IGMP_MEMBERSHIP_QUERY:
234 ++igmpstat.igps_rcv_queries;
235
236 if (ifp->if_flags & IFF_LOOPBACK)
237 break;
238
239 if (igmp->igmp_code == 0) {
240 /*
241 * Old router. Remember that the querier on this
242 * interface is old, and set the timer to the
243 * value in RFC 1112.
244 */
245
246 mtx_lock(&igmp_mtx);
247 rti = find_rti(ifp);
248 rti->rti_type = IGMP_V1_ROUTER;
249 rti->rti_time = 0;
250 mtx_unlock(&igmp_mtx);
251
252 timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
253
254 if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
255 igmp->igmp_group.s_addr != 0) {
256 ++igmpstat.igps_rcv_badqueries;
257 m_freem(m);
258 return;
259 }
260 } else {
261 /*
262 * New router. Simply do the new validity check.
263 */
264
265 if (igmp->igmp_group.s_addr != 0 &&
266 !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
267 ++igmpstat.igps_rcv_badqueries;
268 m_freem(m);
269 return;
270 }
271 }
272
273 /*
274 * - Start the timers in all of our membership records
275 * that the query applies to for the interface on
276 * which the query arrived excl. those that belong
277 * to the "all-hosts" group (224.0.0.1).
278 * - Restart any timer that is already running but has
279 * a value longer than the requested timeout.
280 * - Use the value specified in the query message as
281 * the maximum timeout.
282 */
283 IN_MULTI_LOCK();
284 IN_FIRST_MULTI(step, inm);
285 while (inm != NULL) {
286 if (inm->inm_ifp == ifp &&
287 inm->inm_addr.s_addr != igmp_all_hosts_group &&
288 (igmp->igmp_group.s_addr == 0 ||
289 igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
290 if (inm->inm_timer == 0 ||
291 inm->inm_timer > timer) {
292 inm->inm_timer =
293 IGMP_RANDOM_DELAY(timer);
294 igmp_timers_are_running = 1;
295 }
296 }
297 IN_NEXT_MULTI(step, inm);
298 }
299 IN_MULTI_UNLOCK();
300
301 break;
302
303 case IGMP_V1_MEMBERSHIP_REPORT:
304 case IGMP_V2_MEMBERSHIP_REPORT:
305 /*
306 * For fast leave to work, we have to know that we are the
307 * last person to send a report for this group. Reports
308 * can potentially get looped back if we are a multicast
309 * router, so discard reports sourced by me.
310 */
311 IFP_TO_IA(ifp, ia);
312 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
313 break;
314
315 ++igmpstat.igps_rcv_reports;
316
317 if (ifp->if_flags & IFF_LOOPBACK)
318 break;
319
320 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
321 ++igmpstat.igps_rcv_badreports;
322 m_freem(m);
323 return;
324 }
325
326 /*
327 * KLUDGE: if the IP source address of the report has an
328 * unspecified (i.e., zero) subnet number, as is allowed for
329 * a booting host, replace it with the correct subnet number
330 * so that a process-level multicast routing daemon can
331 * determine which subnet it arrived from. This is necessary
332 * to compensate for the lack of any way for a process to
333 * determine the arrival interface of an incoming packet.
334 */
335 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
336 if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
337
338 /*
339 * If we belong to the group being reported, stop
340 * our timer for that group.
341 */
342 IN_MULTI_LOCK();
343 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
344 if (inm != NULL) {
345 inm->inm_timer = 0;
346 ++igmpstat.igps_rcv_ourreports;
347
348 inm->inm_state = IGMP_OTHERMEMBER;
349 }
350 IN_MULTI_UNLOCK();
351
352 break;
353 }
354
355 /*
356 * Pass all valid IGMP packets up to any process(es) listening
357 * on a raw IGMP socket.
358 */
359 rip_input(m, off);
360 }
361
362 void
363 igmp_joingroup(struct in_multi *inm)
364 {
365
366 IN_MULTI_LOCK_ASSERT();
367
368 if (inm->inm_addr.s_addr == igmp_all_hosts_group
369 || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
370 inm->inm_timer = 0;
371 inm->inm_state = IGMP_OTHERMEMBER;
372 } else {
373 mtx_lock(&igmp_mtx);
374 inm->inm_rti = find_rti(inm->inm_ifp);
375 mtx_unlock(&igmp_mtx);
376 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
377 inm->inm_timer = IGMP_RANDOM_DELAY(
378 IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
379 inm->inm_state = IGMP_IREPORTEDLAST;
380 igmp_timers_are_running = 1;
381 }
382 }
383
384 void
385 igmp_leavegroup(struct in_multi *inm)
386 {
387
388 IN_MULTI_LOCK_ASSERT();
389
390 if (inm->inm_state == IGMP_IREPORTEDLAST &&
391 inm->inm_addr.s_addr != igmp_all_hosts_group &&
392 !(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
393 inm->inm_rti->rti_type != IGMP_V1_ROUTER)
394 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
395 }
396
397 void
398 igmp_fasttimo(void)
399 {
400 register struct in_multi *inm;
401 struct in_multistep step;
402
403 /*
404 * Quick check to see if any work needs to be done, in order
405 * to minimize the overhead of fasttimo processing.
406 */
407
408 if (!igmp_timers_are_running)
409 return;
410
411 IN_MULTI_LOCK();
412 igmp_timers_are_running = 0;
413 IN_FIRST_MULTI(step, inm);
414 while (inm != NULL) {
415 if (inm->inm_timer == 0) {
416 /* do nothing */
417 } else if (--inm->inm_timer == 0) {
418 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
419 inm->inm_state = IGMP_IREPORTEDLAST;
420 } else {
421 igmp_timers_are_running = 1;
422 }
423 IN_NEXT_MULTI(step, inm);
424 }
425 IN_MULTI_UNLOCK();
426 }
427
428 void
429 igmp_slowtimo(void)
430 {
431 struct router_info *rti;
432
433 IGMP_PRINTF("[igmp.c,_slowtimo] -- > entering \n");
434 mtx_lock(&igmp_mtx);
435 SLIST_FOREACH(rti, &router_info_head, rti_list) {
436 if (rti->rti_type == IGMP_V1_ROUTER) {
437 rti->rti_time++;
438 if (rti->rti_time >= IGMP_AGE_THRESHOLD)
439 rti->rti_type = IGMP_V2_ROUTER;
440 }
441 }
442 mtx_unlock(&igmp_mtx);
443 IGMP_PRINTF("[igmp.c,_slowtimo] -- > exiting \n");
444 }
445
446 static void
447 igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr)
448 {
449 struct mbuf *m;
450 struct igmp *igmp;
451 struct ip *ip;
452 struct ip_moptions imo;
453
454 IN_MULTI_LOCK_ASSERT();
455
456 MGETHDR(m, M_DONTWAIT, MT_HEADER);
457 if (m == NULL)
458 return;
459
460 m->m_pkthdr.rcvif = loif;
461 #ifdef MAC
462 mac_create_mbuf_linklayer(inm->inm_ifp, m);
463 #endif
464 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
465 MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
466 m->m_data += sizeof(struct ip);
467 m->m_len = IGMP_MINLEN;
468 igmp = mtod(m, struct igmp *);
469 igmp->igmp_type = type;
470 igmp->igmp_code = 0;
471 igmp->igmp_group = inm->inm_addr;
472 igmp->igmp_cksum = 0;
473 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN);
474
475 m->m_data -= sizeof(struct ip);
476 m->m_len += sizeof(struct ip);
477 ip = mtod(m, struct ip *);
478 ip->ip_tos = 0;
479 ip->ip_len = sizeof(struct ip) + IGMP_MINLEN;
480 ip->ip_off = 0;
481 ip->ip_p = IPPROTO_IGMP;
482 ip->ip_src.s_addr = INADDR_ANY;
483 ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr;
484
485 imo.imo_multicast_ifp = inm->inm_ifp;
486 imo.imo_multicast_ttl = 1;
487 imo.imo_multicast_vif = -1;
488 /*
489 * Request loopback of the report if we are acting as a multicast
490 * router, so that the process-level routing daemon can hear it.
491 */
492 imo.imo_multicast_loop = (ip_mrouter != NULL);
493
494 /*
495 * XXX
496 * Do we have to worry about reentrancy here? Don't think so.
497 */
498 ip_output(m, router_alert, &igmprt, 0, &imo, NULL);
499
500 ++igmpstat.igps_snd_reports;
501 }
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