xref: /freebsd/sys/netinet/igmp.c (revision 7f3dea244c40159a41ab22da77a434d7c5b5e85a)
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  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed by the University of
20  *	California, Berkeley and its contributors.
21  * 4. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  *
37  *	@(#)igmp.c	8.1 (Berkeley) 7/19/93
38  * $Id: igmp.c,v 1.26 1998/12/12 21:45:49 dillon Exp $
39  */
40 
41 /*
42  * Internet Group Management Protocol (IGMP) routines.
43  *
44  * Written by Steve Deering, Stanford, May 1988.
45  * Modified by Rosen Sharma, Stanford, Aug 1994.
46  * Modified by Bill Fenner, Xerox PARC, Feb 1995.
47  * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
48  *
49  * MULTICAST Revision: 3.5.1.4
50  */
51 
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/malloc.h>
55 #include <sys/mbuf.h>
56 #include <sys/socket.h>
57 #include <sys/protosw.h>
58 #include <sys/kernel.h>
59 #include <sys/sysctl.h>
60 
61 #include <net/if.h>
62 #include <net/route.h>
63 
64 #include <netinet/in.h>
65 #include <netinet/in_var.h>
66 #include <netinet/in_systm.h>
67 #include <netinet/ip.h>
68 #include <netinet/ip_var.h>
69 #include <netinet/igmp.h>
70 #include <netinet/igmp_var.h>
71 
72 static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");
73 
74 static struct router_info *
75 		find_rti __P((struct ifnet *ifp));
76 
77 static struct igmpstat igmpstat;
78 
79 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RD,
80 	&igmpstat, igmpstat, "");
81 
82 static int igmp_timers_are_running;
83 static u_long igmp_all_hosts_group;
84 static u_long igmp_all_rtrs_group;
85 static struct mbuf *router_alert;
86 static struct router_info *Head;
87 
88 static void igmp_sendpkt __P((struct in_multi *, int, unsigned long));
89 
90 void
91 igmp_init()
92 {
93 	struct ipoption *ra;
94 
95 	/*
96 	 * To avoid byte-swapping the same value over and over again.
97 	 */
98 	igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
99 	igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);
100 
101 	igmp_timers_are_running = 0;
102 
103 	/*
104 	 * Construct a Router Alert option to use in outgoing packets
105 	 */
106 	MGET(router_alert, M_DONTWAIT, MT_DATA);
107 	ra = mtod(router_alert, struct ipoption *);
108 	ra->ipopt_dst.s_addr = 0;
109 	ra->ipopt_list[0] = IPOPT_RA;	/* Router Alert Option */
110 	ra->ipopt_list[1] = 0x04;	/* 4 bytes long */
111 	ra->ipopt_list[2] = 0x00;
112 	ra->ipopt_list[3] = 0x00;
113 	router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];
114 
115 	Head = (struct router_info *) 0;
116 }
117 
118 static struct router_info *
119 find_rti(ifp)
120 	struct ifnet *ifp;
121 {
122         register struct router_info *rti = Head;
123 
124 #ifdef IGMP_DEBUG
125 	printf("[igmp.c, _find_rti] --> entering \n");
126 #endif
127         while (rti) {
128                 if (rti->rti_ifp == ifp) {
129 #ifdef IGMP_DEBUG
130 			printf("[igmp.c, _find_rti] --> found old entry \n");
131 #endif
132                         return rti;
133                 }
134                 rti = rti->rti_next;
135         }
136 	MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT);
137         rti->rti_ifp = ifp;
138         rti->rti_type = IGMP_V2_ROUTER;
139         rti->rti_time = 0;
140         rti->rti_next = Head;
141         Head = rti;
142 #ifdef IGMP_DEBUG
143 	printf("[igmp.c, _find_rti] --> created an entry \n");
144 #endif
145         return rti;
146 }
147 
148 void
149 igmp_input(m, iphlen)
150 	register struct mbuf *m;
151 	register int iphlen;
152 {
153 	register struct igmp *igmp;
154 	register struct ip *ip;
155 	register int igmplen;
156 	register struct ifnet *ifp = m->m_pkthdr.rcvif;
157 	register int minlen;
158 	register struct in_multi *inm;
159 	register struct in_ifaddr *ia;
160 	struct in_multistep step;
161 	struct router_info *rti;
162 
163 	int timer; /** timer value in the igmp query header **/
164 
165 	++igmpstat.igps_rcv_total;
166 
167 	ip = mtod(m, struct ip *);
168 	igmplen = ip->ip_len;
169 
170 	/*
171 	 * Validate lengths
172 	 */
173 	if (igmplen < IGMP_MINLEN) {
174 		++igmpstat.igps_rcv_tooshort;
175 		m_freem(m);
176 		return;
177 	}
178 	minlen = iphlen + IGMP_MINLEN;
179 	if ((m->m_flags & M_EXT || m->m_len < minlen) &&
180 	    (m = m_pullup(m, minlen)) == 0) {
181 		++igmpstat.igps_rcv_tooshort;
182 		return;
183 	}
184 
185 	/*
186 	 * Validate checksum
187 	 */
188 	m->m_data += iphlen;
189 	m->m_len -= iphlen;
190 	igmp = mtod(m, struct igmp *);
191 	if (in_cksum(m, igmplen)) {
192 		++igmpstat.igps_rcv_badsum;
193 		m_freem(m);
194 		return;
195 	}
196 	m->m_data -= iphlen;
197 	m->m_len += iphlen;
198 
199 	ip = mtod(m, struct ip *);
200 	timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
201 	if (timer == 0)
202 		timer = 1;
203 	rti = find_rti(ifp);
204 
205 	/*
206 	 * In the IGMPv2 specification, there are 3 states and a flag.
207 	 *
208 	 * In Non-Member state, we simply don't have a membership record.
209 	 * In Delaying Member state, our timer is running (inm->inm_timer)
210 	 * In Idle Member state, our timer is not running (inm->inm_timer==0)
211 	 *
212 	 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
213 	 * we have heard a report from another member, or IGMP_IREPORTEDLAST
214 	 * if I sent the last report.
215 	 */
216 	switch (igmp->igmp_type) {
217 
218 	case IGMP_MEMBERSHIP_QUERY:
219 		++igmpstat.igps_rcv_queries;
220 
221 		if (ifp->if_flags & IFF_LOOPBACK)
222 			break;
223 
224 		if (igmp->igmp_code == 0) {
225 			/*
226 			 * Old router.  Remember that the querier on this
227 			 * interface is old, and set the timer to the
228 			 * value in RFC 1112.
229 			 */
230 
231 			rti->rti_type = IGMP_V1_ROUTER;
232 			rti->rti_time = 0;
233 
234 			timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
235 
236 			if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
237 			    igmp->igmp_group.s_addr != 0) {
238 				++igmpstat.igps_rcv_badqueries;
239 				m_freem(m);
240 				return;
241 			}
242 		} else {
243 			/*
244 			 * New router.  Simply do the new validity check.
245 			 */
246 
247 			if (igmp->igmp_group.s_addr != 0 &&
248 			    !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
249 				++igmpstat.igps_rcv_badqueries;
250 				m_freem(m);
251 				return;
252 			}
253 		}
254 
255 		/*
256 		 * - Start the timers in all of our membership records
257 		 *   that the query applies to for the interface on
258 		 *   which the query arrived excl. those that belong
259 		 *   to the "all-hosts" group (224.0.0.1).
260 		 * - Restart any timer that is already running but has
261 		 *   a value longer than the requested timeout.
262 		 * - Use the value specified in the query message as
263 		 *   the maximum timeout.
264 		 */
265 		IN_FIRST_MULTI(step, inm);
266 		while (inm != NULL) {
267 			if (inm->inm_ifp == ifp &&
268 			    inm->inm_addr.s_addr != igmp_all_hosts_group &&
269 			    (igmp->igmp_group.s_addr == 0 ||
270 			     igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
271 				if (inm->inm_timer == 0 ||
272 				    inm->inm_timer > timer) {
273 					inm->inm_timer =
274 						IGMP_RANDOM_DELAY(timer);
275 					igmp_timers_are_running = 1;
276 				}
277 			}
278 			IN_NEXT_MULTI(step, inm);
279 		}
280 
281 		break;
282 
283 	case IGMP_V1_MEMBERSHIP_REPORT:
284 	case IGMP_V2_MEMBERSHIP_REPORT:
285 		/*
286 		 * For fast leave to work, we have to know that we are the
287 		 * last person to send a report for this group.  Reports
288 		 * can potentially get looped back if we are a multicast
289 		 * router, so discard reports sourced by me.
290 		 */
291 		IFP_TO_IA(ifp, ia);
292 		if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
293 			break;
294 
295 		++igmpstat.igps_rcv_reports;
296 
297 		if (ifp->if_flags & IFF_LOOPBACK)
298 			break;
299 
300 		if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
301 			++igmpstat.igps_rcv_badreports;
302 			m_freem(m);
303 			return;
304 		}
305 
306 		/*
307 		 * KLUDGE: if the IP source address of the report has an
308 		 * unspecified (i.e., zero) subnet number, as is allowed for
309 		 * a booting host, replace it with the correct subnet number
310 		 * so that a process-level multicast routing demon can
311 		 * determine which subnet it arrived from.  This is necessary
312 		 * to compensate for the lack of any way for a process to
313 		 * determine the arrival interface of an incoming packet.
314 		 */
315 		if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
316 			if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
317 
318 		/*
319 		 * If we belong to the group being reported, stop
320 		 * our timer for that group.
321 		 */
322 		IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
323 
324 		if (inm != NULL) {
325 			inm->inm_timer = 0;
326 			++igmpstat.igps_rcv_ourreports;
327 
328 			inm->inm_state = IGMP_OTHERMEMBER;
329 		}
330 
331 		break;
332 	}
333 
334 	/*
335 	 * Pass all valid IGMP packets up to any process(es) listening
336 	 * on a raw IGMP socket.
337 	 */
338 	rip_input(m, iphlen);
339 }
340 
341 void
342 igmp_joingroup(inm)
343 	struct in_multi *inm;
344 {
345 	int s = splnet();
346 
347 	if (inm->inm_addr.s_addr == igmp_all_hosts_group
348 	    || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
349 		inm->inm_timer = 0;
350 		inm->inm_state = IGMP_OTHERMEMBER;
351 	} else {
352 		inm->inm_rti = find_rti(inm->inm_ifp);
353 		igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
354 		inm->inm_timer = IGMP_RANDOM_DELAY(
355 					IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
356 		inm->inm_state = IGMP_IREPORTEDLAST;
357 		igmp_timers_are_running = 1;
358 	}
359 	splx(s);
360 }
361 
362 void
363 igmp_leavegroup(inm)
364 	struct in_multi *inm;
365 {
366 	if (inm->inm_state == IGMP_IREPORTEDLAST &&
367 	    inm->inm_addr.s_addr != igmp_all_hosts_group &&
368 	    !(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
369 	    inm->inm_rti->rti_type != IGMP_V1_ROUTER)
370 		igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
371 }
372 
373 void
374 igmp_fasttimo()
375 {
376 	register struct in_multi *inm;
377 	struct in_multistep step;
378 	int s;
379 
380 	/*
381 	 * Quick check to see if any work needs to be done, in order
382 	 * to minimize the overhead of fasttimo processing.
383 	 */
384 
385 	if (!igmp_timers_are_running)
386 		return;
387 
388 	s = splnet();
389 	igmp_timers_are_running = 0;
390 	IN_FIRST_MULTI(step, inm);
391 	while (inm != NULL) {
392 		if (inm->inm_timer == 0) {
393 			/* do nothing */
394 		} else if (--inm->inm_timer == 0) {
395 			igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
396 			inm->inm_state = IGMP_IREPORTEDLAST;
397 		} else {
398 			igmp_timers_are_running = 1;
399 		}
400 		IN_NEXT_MULTI(step, inm);
401 	}
402 	splx(s);
403 }
404 
405 void
406 igmp_slowtimo()
407 {
408 	int s = splnet();
409 	register struct router_info *rti =  Head;
410 
411 #ifdef IGMP_DEBUG
412 	printf("[igmp.c,_slowtimo] -- > entering \n");
413 #endif
414 	while (rti) {
415 	    if (rti->rti_type == IGMP_V1_ROUTER) {
416 		rti->rti_time++;
417 		if (rti->rti_time >= IGMP_AGE_THRESHOLD) {
418 			rti->rti_type = IGMP_V2_ROUTER;
419 		}
420 	    }
421 	    rti = rti->rti_next;
422 	}
423 #ifdef IGMP_DEBUG
424 	printf("[igmp.c,_slowtimo] -- > exiting \n");
425 #endif
426 	splx(s);
427 }
428 
429 static struct route igmprt;
430 
431 static void
432 igmp_sendpkt(inm, type, addr)
433 	struct in_multi *inm;
434 	int type;
435 	unsigned long addr;
436 {
437         struct mbuf *m;
438         struct igmp *igmp;
439         struct ip *ip;
440         struct ip_moptions imo;
441 
442         MGETHDR(m, M_DONTWAIT, MT_HEADER);
443         if (m == NULL)
444                 return;
445 
446 	m->m_pkthdr.rcvif = loif;
447 	m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
448 	MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
449 	m->m_data += sizeof(struct ip);
450         m->m_len = IGMP_MINLEN;
451         igmp = mtod(m, struct igmp *);
452         igmp->igmp_type   = type;
453         igmp->igmp_code   = 0;
454         igmp->igmp_group  = inm->inm_addr;
455         igmp->igmp_cksum  = 0;
456         igmp->igmp_cksum  = in_cksum(m, IGMP_MINLEN);
457 
458         m->m_data -= sizeof(struct ip);
459         m->m_len += sizeof(struct ip);
460         ip = mtod(m, struct ip *);
461         ip->ip_tos        = 0;
462         ip->ip_len        = sizeof(struct ip) + IGMP_MINLEN;
463         ip->ip_off        = 0;
464         ip->ip_p          = IPPROTO_IGMP;
465         ip->ip_src.s_addr = INADDR_ANY;
466         ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr;
467 
468         imo.imo_multicast_ifp  = inm->inm_ifp;
469         imo.imo_multicast_ttl  = 1;
470 	imo.imo_multicast_vif  = -1;
471         /*
472          * Request loopback of the report if we are acting as a multicast
473          * router, so that the process-level routing demon can hear it.
474          */
475         imo.imo_multicast_loop = (ip_mrouter != NULL);
476 
477 	/*
478 	 * XXX
479 	 * Do we have to worry about reentrancy here?  Don't think so.
480 	 */
481         ip_output(m, router_alert, &igmprt, 0, &imo);
482 
483         ++igmpstat.igps_snd_reports;
484 }
485