igmp.c revision 181803
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 */ 35 36/* 37 * Internet Group Management Protocol (IGMP) routines. 38 * 39 * Written by Steve Deering, Stanford, May 1988. 40 * Modified by Rosen Sharma, Stanford, Aug 1994. 41 * Modified by Bill Fenner, Xerox PARC, Feb 1995. 42 * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995. 43 * 44 * MULTICAST Revision: 3.5.1.4 45 */ 46 47#include <sys/cdefs.h> 48__FBSDID("$FreeBSD: head/sys/netinet/igmp.c 181803 2008-08-17 23:27:27Z bz $"); 49 50#include "opt_mac.h" 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#include <sys/vimage.h> 61 62#include <net/if.h> 63#include <net/route.h> 64 65#include <netinet/in.h> 66#include <netinet/in_var.h> 67#include <netinet/in_systm.h> 68#include <netinet/ip.h> 69#include <netinet/ip_var.h> 70#include <netinet/ip_options.h> 71#include <netinet/igmp.h> 72#include <netinet/igmp_var.h> 73 74#include <machine/in_cksum.h> 75 76#include <security/mac/mac_framework.h> 77 78static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state"); 79 80static struct router_info *find_rti(struct ifnet *ifp); 81static void igmp_sendpkt(struct in_multi *, int, unsigned long); 82 83static struct igmpstat igmpstat; 84 85SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, &igmpstat, 86 igmpstat, ""); 87 88/* 89 * igmp_mtx protects all mutable global variables in igmp.c, as well as the 90 * data fields in struct router_info. In general, a router_info structure 91 * will be valid as long as the referencing struct in_multi is valid, so no 92 * reference counting is used. We allow unlocked reads of router_info data 93 * when accessed via an in_multi read-only. 94 */ 95static struct mtx igmp_mtx; 96static SLIST_HEAD(, router_info) router_info_head; 97static int igmp_timers_are_running; 98 99/* 100 * XXXRW: can we define these such that these can be made const? In any 101 * case, these shouldn't be changed after igmp_init() and therefore don't 102 * need locking. 103 */ 104static u_long igmp_all_hosts_group; 105static u_long igmp_all_rtrs_group; 106 107static struct mbuf *router_alert; 108static struct route igmprt; 109 110#ifdef IGMP_DEBUG 111#define IGMP_PRINTF(x) printf(x) 112#else 113#define IGMP_PRINTF(x) 114#endif 115 116void 117igmp_init(void) 118{ 119 struct ipoption *ra; 120 121 /* 122 * To avoid byte-swapping the same value over and over again. 123 */ 124 igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP); 125 igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP); 126 127 igmp_timers_are_running = 0; 128 129 /* 130 * Construct a Router Alert option to use in outgoing packets. 131 */ 132 MGET(router_alert, M_DONTWAIT, MT_DATA); 133 ra = mtod(router_alert, struct ipoption *); 134 ra->ipopt_dst.s_addr = 0; 135 ra->ipopt_list[0] = IPOPT_RA; /* Router Alert Option */ 136 ra->ipopt_list[1] = 0x04; /* 4 bytes long */ 137 ra->ipopt_list[2] = 0x00; 138 ra->ipopt_list[3] = 0x00; 139 router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1]; 140 141 mtx_init(&igmp_mtx, "igmp_mtx", NULL, MTX_DEF); 142 SLIST_INIT(&V_router_info_head); 143} 144 145static struct router_info * 146find_rti(struct ifnet *ifp) 147{ 148 struct router_info *rti; 149 150 mtx_assert(&igmp_mtx, MA_OWNED); 151 IGMP_PRINTF("[igmp.c, _find_rti] --> entering \n"); 152 SLIST_FOREACH(rti, &V_router_info_head, rti_list) { 153 if (rti->rti_ifp == ifp) { 154 IGMP_PRINTF( 155 "[igmp.c, _find_rti] --> found old entry \n"); 156 return (rti); 157 } 158 } 159 MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT); 160 if (rti == NULL) { 161 IGMP_PRINTF("[igmp.c, _find_rti] --> no memory for entry\n"); 162 return (NULL); 163 } 164 rti->rti_ifp = ifp; 165 rti->rti_type = IGMP_V2_ROUTER; 166 rti->rti_time = 0; 167 SLIST_INSERT_HEAD(&V_router_info_head, rti, rti_list); 168 IGMP_PRINTF("[igmp.c, _find_rti] --> created an entry \n"); 169 return (rti); 170} 171 172void 173igmp_input(register struct mbuf *m, int off) 174{ 175 register int iphlen = off; 176 register struct igmp *igmp; 177 register struct ip *ip; 178 register int igmplen; 179 register struct ifnet *ifp = m->m_pkthdr.rcvif; 180 register int minlen; 181 register struct in_multi *inm; 182 register struct in_ifaddr *ia; 183 struct in_multistep step; 184 struct router_info *rti; 185 int timer; /** timer value in the igmp query header **/ 186 187 ++V_igmpstat.igps_rcv_total; 188 189 ip = mtod(m, struct ip *); 190 igmplen = ip->ip_len; 191 192 /* 193 * Validate lengths. 194 */ 195 if (igmplen < IGMP_MINLEN) { 196 ++V_igmpstat.igps_rcv_tooshort; 197 m_freem(m); 198 return; 199 } 200 minlen = iphlen + IGMP_MINLEN; 201 if ((m->m_flags & M_EXT || m->m_len < minlen) && 202 (m = m_pullup(m, minlen)) == 0) { 203 ++V_igmpstat.igps_rcv_tooshort; 204 return; 205 } 206 207 /* 208 * Validate checksum. 209 */ 210 m->m_data += iphlen; 211 m->m_len -= iphlen; 212 igmp = mtod(m, struct igmp *); 213 if (in_cksum(m, igmplen)) { 214 ++V_igmpstat.igps_rcv_badsum; 215 m_freem(m); 216 return; 217 } 218 m->m_data -= iphlen; 219 m->m_len += iphlen; 220 221 ip = mtod(m, struct ip *); 222 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE; 223 if (timer == 0) 224 timer = 1; 225 226 /* 227 * In the IGMPv2 specification, there are 3 states and a flag. 228 * 229 * In Non-Member state, we simply don't have a membership record. 230 * In Delaying Member state, our timer is running (inm->inm_timer). 231 * In Idle Member state, our timer is not running (inm->inm_timer==0). 232 * 233 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if we 234 * have heard a report from another member, or IGMP_IREPORTEDLAST if 235 * I sent the last report. 236 */ 237 switch (igmp->igmp_type) { 238 case IGMP_MEMBERSHIP_QUERY: 239 ++V_igmpstat.igps_rcv_queries; 240 241 if (ifp->if_flags & IFF_LOOPBACK) 242 break; 243 244 if (igmp->igmp_code == 0) { 245 /* 246 * Old router. Remember that the querier on this 247 * interface is old, and set the timer to the value 248 * in RFC 1112. 249 */ 250 251 mtx_lock(&igmp_mtx); 252 rti = find_rti(ifp); 253 if (rti == NULL) { 254 mtx_unlock(&igmp_mtx); 255 m_freem(m); 256 return; 257 } 258 rti->rti_type = IGMP_V1_ROUTER; 259 rti->rti_time = 0; 260 mtx_unlock(&igmp_mtx); 261 262 timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ; 263 264 if (ip->ip_dst.s_addr != igmp_all_hosts_group || 265 igmp->igmp_group.s_addr != 0) { 266 ++V_igmpstat.igps_rcv_badqueries; 267 m_freem(m); 268 return; 269 } 270 } else { 271 /* 272 * New router. Simply do the new validity check. 273 */ 274 275 if (igmp->igmp_group.s_addr != 0 && 276 !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 277 ++V_igmpstat.igps_rcv_badqueries; 278 m_freem(m); 279 return; 280 } 281 } 282 283 /* 284 * - Start the timers in all of our membership records that 285 * the query applies to for the interface on which the 286 * query arrived excl. those that belong to the "all-hosts" 287 * group (224.0.0.1). 288 * - Restart any timer that is already running but has a 289 * value longer than the requested timeout. 290 * - Use the value specified in the query message as the 291 * maximum timeout. 292 */ 293 IN_MULTI_LOCK(); 294 IN_FIRST_MULTI(step, inm); 295 while (inm != NULL) { 296 if (inm->inm_ifp == ifp && 297 inm->inm_addr.s_addr != igmp_all_hosts_group && 298 (igmp->igmp_group.s_addr == 0 || 299 igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) { 300 if (inm->inm_timer == 0 || 301 inm->inm_timer > timer) { 302 inm->inm_timer = 303 IGMP_RANDOM_DELAY(timer); 304 igmp_timers_are_running = 1; 305 } 306 } 307 IN_NEXT_MULTI(step, inm); 308 } 309 IN_MULTI_UNLOCK(); 310 break; 311 312 case IGMP_V1_MEMBERSHIP_REPORT: 313 case IGMP_V2_MEMBERSHIP_REPORT: 314 /* 315 * For fast leave to work, we have to know that we are the 316 * last person to send a report for this group. Reports can 317 * potentially get looped back if we are a multicast router, 318 * so discard reports sourced by me. 319 */ 320 IFP_TO_IA(ifp, ia); 321 if (ia != NULL && 322 ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr) 323 break; 324 325 ++V_igmpstat.igps_rcv_reports; 326 327 if (ifp->if_flags & IFF_LOOPBACK) 328 break; 329 330 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 331 ++V_igmpstat.igps_rcv_badreports; 332 m_freem(m); 333 return; 334 } 335 336 /* 337 * KLUDGE: if the IP source address of the report has an 338 * unspecified (i.e., zero) subnet number, as is allowed for 339 * a booting host, replace it with the correct subnet number 340 * so that a process-level multicast routing daemon can 341 * determine which subnet it arrived from. This is necessary 342 * to compensate for the lack of any way for a process to 343 * determine the arrival interface of an incoming packet. 344 */ 345 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) { 346 if (ia != NULL) 347 ip->ip_src.s_addr = htonl(ia->ia_subnet); 348 } 349 350 /* 351 * If we belong to the group being reported, stop our timer 352 * for that group. 353 */ 354 IN_MULTI_LOCK(); 355 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 356 if (inm != NULL) { 357 inm->inm_timer = 0; 358 ++V_igmpstat.igps_rcv_ourreports; 359 inm->inm_state = IGMP_OTHERMEMBER; 360 } 361 IN_MULTI_UNLOCK(); 362 break; 363 } 364 365 /* 366 * Pass all valid IGMP packets up to any process(es) listening on a 367 * raw IGMP socket. 368 */ 369 rip_input(m, off); 370} 371 372void 373igmp_joingroup(struct in_multi *inm) 374{ 375 376 IN_MULTI_LOCK_ASSERT(); 377 378 if (inm->inm_addr.s_addr == igmp_all_hosts_group 379 || inm->inm_ifp->if_flags & IFF_LOOPBACK) { 380 inm->inm_timer = 0; 381 inm->inm_state = IGMP_OTHERMEMBER; 382 } else { 383 mtx_lock(&igmp_mtx); 384 inm->inm_rti = find_rti(inm->inm_ifp); 385 mtx_unlock(&igmp_mtx); 386 if (inm->inm_rti != NULL) { 387 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 388 inm->inm_timer = IGMP_RANDOM_DELAY( 389 IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ); 390 inm->inm_state = IGMP_IREPORTEDLAST; 391 igmp_timers_are_running = 1; 392 } 393 /* XXX handling of failure case? */ 394 } 395} 396 397void 398igmp_leavegroup(struct in_multi *inm) 399{ 400 401 IN_MULTI_LOCK_ASSERT(); 402 403 if (inm->inm_state == IGMP_IREPORTEDLAST && 404 inm->inm_addr.s_addr != igmp_all_hosts_group && 405 !(inm->inm_ifp->if_flags & IFF_LOOPBACK) && 406 inm->inm_rti->rti_type != IGMP_V1_ROUTER) 407 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group); 408} 409 410void 411igmp_fasttimo(void) 412{ 413 register struct in_multi *inm; 414 struct in_multistep step; 415 416 /* 417 * Quick check to see if any work needs to be done, in order to 418 * minimize the overhead of fasttimo processing. 419 */ 420 421 if (!igmp_timers_are_running) 422 return; 423 424 IN_MULTI_LOCK(); 425 igmp_timers_are_running = 0; 426 IN_FIRST_MULTI(step, inm); 427 while (inm != NULL) { 428 if (inm->inm_timer == 0) { 429 /* do nothing */ 430 } else if (--inm->inm_timer == 0) { 431 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 432 inm->inm_state = IGMP_IREPORTEDLAST; 433 } else { 434 igmp_timers_are_running = 1; 435 } 436 IN_NEXT_MULTI(step, inm); 437 } 438 IN_MULTI_UNLOCK(); 439} 440 441void 442igmp_slowtimo(void) 443{ 444 struct router_info *rti; 445 446 IGMP_PRINTF("[igmp.c,_slowtimo] -- > entering \n"); 447 mtx_lock(&igmp_mtx); 448 SLIST_FOREACH(rti, &V_router_info_head, rti_list) { 449 if (rti->rti_type == IGMP_V1_ROUTER) { 450 rti->rti_time++; 451 if (rti->rti_time >= IGMP_AGE_THRESHOLD) 452 rti->rti_type = IGMP_V2_ROUTER; 453 } 454 } 455 mtx_unlock(&igmp_mtx); 456 IGMP_PRINTF("[igmp.c,_slowtimo] -- > exiting \n"); 457} 458 459static void 460igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr) 461{ 462 struct mbuf *m; 463 struct igmp *igmp; 464 struct ip *ip; 465 struct ip_moptions imo; 466 467 IN_MULTI_LOCK_ASSERT(); 468 469 MGETHDR(m, M_DONTWAIT, MT_DATA); 470 if (m == NULL) 471 return; 472 473 m->m_pkthdr.rcvif = V_loif; 474#ifdef MAC 475 mac_netinet_igmp_send(inm->inm_ifp, m); 476#endif 477 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN; 478 MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip)); 479 m->m_data += sizeof(struct ip); 480 m->m_len = IGMP_MINLEN; 481 igmp = mtod(m, struct igmp *); 482 igmp->igmp_type = type; 483 igmp->igmp_code = 0; 484 igmp->igmp_group = inm->inm_addr; 485 igmp->igmp_cksum = 0; 486 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN); 487 488 m->m_data -= sizeof(struct ip); 489 m->m_len += sizeof(struct ip); 490 ip = mtod(m, struct ip *); 491 ip->ip_tos = 0; 492 ip->ip_len = sizeof(struct ip) + IGMP_MINLEN; 493 ip->ip_off = 0; 494 ip->ip_p = IPPROTO_IGMP; 495 ip->ip_src.s_addr = INADDR_ANY; 496 ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr; 497 498 imo.imo_multicast_ifp = inm->inm_ifp; 499 imo.imo_multicast_ttl = 1; 500 imo.imo_multicast_vif = -1; 501 /* 502 * Request loopback of the report if we are acting as a multicast 503 * router, so that the process-level routing daemon can hear it. 504 */ 505 imo.imo_multicast_loop = (V_ip_mrouter != NULL); 506 507 /* 508 * XXX: Do we have to worry about reentrancy here? Don't think so. 509 */ 510 ip_output(m, router_alert, &igmprt, 0, &imo, NULL); 511 512 ++V_igmpstat.igps_snd_reports; 513} 514