Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/igmp.c
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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 * $FreeBSD$ 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 }
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