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: src/sys/netinet/igmp.c,v 1.19.2.1 1999/09/05 08:18:14 peter 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/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 static struct router_info * 72 find_rti __P((struct ifnet *ifp)); 73 74 static struct igmpstat igmpstat; 75 76 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RD, 77 &igmpstat, igmpstat, ""); 78 79 static int igmp_timers_are_running; 80 static u_long igmp_all_hosts_group; 81 static u_long igmp_all_rtrs_group; 82 static struct mbuf *router_alert; 83 static struct router_info *Head; 84 85 static void igmp_sendpkt(struct in_multi *, int, unsigned long); 86 87 void 88 igmp_init() 89 { 90 struct ipoption *ra; 91 92 /* 93 * To avoid byte-swapping the same value over and over again. 94 */ 95 igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP); 96 igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP); 97 98 igmp_timers_are_running = 0; 99 100 /* 101 * Construct a Router Alert option to use in outgoing packets 102 */ 103 MGET(router_alert, M_DONTWAIT, MT_DATA); 104 ra = mtod(router_alert, struct ipoption *); 105 ra->ipopt_dst.s_addr = 0; 106 ra->ipopt_list[0] = IPOPT_RA; /* Router Alert Option */ 107 ra->ipopt_list[1] = 0x04; /* 4 bytes long */ 108 ra->ipopt_list[2] = 0x00; 109 ra->ipopt_list[3] = 0x00; 110 router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1]; 111 112 Head = (struct router_info *) 0; 113 } 114 115 static struct router_info * 116 find_rti(ifp) 117 struct ifnet *ifp; 118 { 119 register struct router_info *rti = Head; 120 121 #ifdef IGMP_DEBUG 122 printf("[igmp.c, _find_rti] --> entering \n"); 123 #endif 124 while (rti) { 125 if (rti->rti_ifp == ifp) { 126 #ifdef IGMP_DEBUG 127 printf("[igmp.c, _find_rti] --> found old entry \n"); 128 #endif 129 return rti; 130 } 131 rti = rti->rti_next; 132 } 133 MALLOC(rti, struct router_info *, sizeof *rti, M_MRTABLE, M_NOWAIT); 134 rti->rti_ifp = ifp; 135 rti->rti_type = IGMP_V2_ROUTER; 136 rti->rti_time = 0; 137 rti->rti_next = Head; 138 Head = rti; 139 #ifdef IGMP_DEBUG 140 printf("[igmp.c, _find_rti] --> created an entry \n"); 141 #endif 142 return rti; 143 } 144 145 void 146 igmp_input(m, iphlen) 147 register struct mbuf *m; 148 register int iphlen; 149 { 150 register struct igmp *igmp; 151 register struct ip *ip; 152 register int igmplen; 153 register struct ifnet *ifp = m->m_pkthdr.rcvif; 154 register int minlen; 155 register struct in_multi *inm; 156 register struct in_ifaddr *ia; 157 struct in_multistep step; 158 struct router_info *rti; 159 160 int timer; /** timer value in the igmp query header **/ 161 162 ++igmpstat.igps_rcv_total; 163 164 ip = mtod(m, struct ip *); 165 igmplen = ip->ip_len; 166 167 /* 168 * Validate lengths 169 */ 170 if (igmplen < IGMP_MINLEN) { 171 ++igmpstat.igps_rcv_tooshort; 172 m_freem(m); 173 return; 174 } 175 minlen = iphlen + IGMP_MINLEN; 176 if ((m->m_flags & M_EXT || m->m_len < minlen) && 177 (m = m_pullup(m, minlen)) == 0) { 178 ++igmpstat.igps_rcv_tooshort; 179 return; 180 } 181 182 /* 183 * Validate checksum 184 */ 185 m->m_data += iphlen; 186 m->m_len -= iphlen; 187 igmp = mtod(m, struct igmp *); 188 if (in_cksum(m, igmplen)) { 189 ++igmpstat.igps_rcv_badsum; 190 m_freem(m); 191 return; 192 } 193 m->m_data -= iphlen; 194 m->m_len += iphlen; 195 196 ip = mtod(m, struct ip *); 197 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE; 198 rti = find_rti(ifp); 199 200 /* 201 * In the IGMPv2 specification, there are 3 states and a flag. 202 * 203 * In Non-Member state, we simply don't have a membership record. 204 * In Delaying Member state, our timer is running (inm->inm_timer) 205 * In Idle Member state, our timer is not running (inm->inm_timer==0) 206 * 207 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if 208 * we have heard a report from another member, or IGMP_IREPORTEDLAST 209 * if I sent the last report. 210 */ 211 switch (igmp->igmp_type) { 212 213 case IGMP_MEMBERSHIP_QUERY: 214 ++igmpstat.igps_rcv_queries; 215 216 if (ifp->if_flags & IFF_LOOPBACK) 217 break; 218 219 if (igmp->igmp_code == 0) { 220 /* 221 * Old router. Remember that the querier on this 222 * interface is old, and set the timer to the 223 * value in RFC 1112. 224 */ 225 226 rti->rti_type = IGMP_V1_ROUTER; 227 rti->rti_time = 0; 228 229 timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ; 230 231 if (ip->ip_dst.s_addr != igmp_all_hosts_group || 232 igmp->igmp_group.s_addr != 0) { 233 ++igmpstat.igps_rcv_badqueries; 234 m_freem(m); 235 return; 236 } 237 } else { 238 /* 239 * New router. Simply do the new validity check. 240 */ 241 242 if (igmp->igmp_group.s_addr != 0 && 243 !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 244 ++igmpstat.igps_rcv_badqueries; 245 m_freem(m); 246 return; 247 } 248 } 249 250 /* 251 * - Start the timers in all of our membership records 252 * that the query applies to for the interface on 253 * which the query arrived excl. those that belong 254 * to the "all-hosts" group (224.0.0.1). 255 * - Restart any timer that is already running but has 256 * a value longer than the requested timeout. 257 * - Use the value specified in the query message as 258 * the maximum timeout. 259 */ 260 IN_FIRST_MULTI(step, inm); 261 while (inm != NULL) { 262 if (inm->inm_ifp == ifp && 263 inm->inm_addr.s_addr != igmp_all_hosts_group && 264 (igmp->igmp_group.s_addr == 0 || 265 igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) { 266 if (inm->inm_timer == 0 || 267 inm->inm_timer > timer) { 268 inm->inm_timer = 269 IGMP_RANDOM_DELAY(timer); 270 igmp_timers_are_running = 1; 271 } 272 } 273 IN_NEXT_MULTI(step, inm); 274 } 275 276 break; 277 278 case IGMP_V1_MEMBERSHIP_REPORT: 279 case IGMP_V2_MEMBERSHIP_REPORT: 280 /* 281 * For fast leave to work, we have to know that we are the 282 * last person to send a report for this group. Reports 283 * can potentially get looped back if we are a multicast 284 * router, so discard reports sourced by me. 285 */ 286 IFP_TO_IA(ifp, ia); 287 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr) 288 break; 289 290 ++igmpstat.igps_rcv_reports; 291 292 if (ifp->if_flags & IFF_LOOPBACK) 293 break; 294 295 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 296 ++igmpstat.igps_rcv_badreports; 297 m_freem(m); 298 return; 299 } 300 301 /* 302 * KLUDGE: if the IP source address of the report has an 303 * unspecified (i.e., zero) subnet number, as is allowed for 304 * a booting host, replace it with the correct subnet number 305 * so that a process-level multicast routing demon can 306 * determine which subnet it arrived from. This is necessary 307 * to compensate for the lack of any way for a process to 308 * determine the arrival interface of an incoming packet. 309 */ 310 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) 311 if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet); 312 313 /* 314 * If we belong to the group being reported, stop 315 * our timer for that group. 316 */ 317 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 318 319 if (inm != NULL) { 320 inm->inm_timer = 0; 321 ++igmpstat.igps_rcv_ourreports; 322 323 inm->inm_state = IGMP_OTHERMEMBER; 324 } 325 326 break; 327 } 328 329 /* 330 * Pass all valid IGMP packets up to any process(es) listening 331 * on a raw IGMP socket. 332 */ 333 rip_input(m, iphlen); 334 } 335 336 void 337 igmp_joingroup(inm) 338 struct in_multi *inm; 339 { 340 int s = splnet(); 341 342 if (inm->inm_addr.s_addr == igmp_all_hosts_group 343 || inm->inm_ifp->if_flags & IFF_LOOPBACK) { 344 inm->inm_timer = 0; 345 inm->inm_state = IGMP_OTHERMEMBER; 346 } else { 347 inm->inm_rti = find_rti(inm->inm_ifp); 348 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 349 inm->inm_timer = IGMP_RANDOM_DELAY( 350 IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ); 351 inm->inm_state = IGMP_IREPORTEDLAST; 352 igmp_timers_are_running = 1; 353 } 354 splx(s); 355 } 356 357 void 358 igmp_leavegroup(inm) 359 struct in_multi *inm; 360 { 361 if (inm->inm_state == IGMP_IREPORTEDLAST && 362 inm->inm_addr.s_addr != igmp_all_hosts_group && 363 !(inm->inm_ifp->if_flags & IFF_LOOPBACK) && 364 inm->inm_rti->rti_type != IGMP_V1_ROUTER) 365 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group); 366 } 367 368 void 369 igmp_fasttimo() 370 { 371 register struct in_multi *inm; 372 struct in_multistep step; 373 int s; 374 375 /* 376 * Quick check to see if any work needs to be done, in order 377 * to minimize the overhead of fasttimo processing. 378 */ 379 380 if (!igmp_timers_are_running) 381 return; 382 383 s = splnet(); 384 igmp_timers_are_running = 0; 385 IN_FIRST_MULTI(step, inm); 386 while (inm != NULL) { 387 if (inm->inm_timer == 0) { 388 /* do nothing */ 389 } else if (--inm->inm_timer == 0) { 390 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 391 inm->inm_state = IGMP_IREPORTEDLAST; 392 } else { 393 igmp_timers_are_running = 1; 394 } 395 IN_NEXT_MULTI(step, inm); 396 } 397 splx(s); 398 } 399 400 void 401 igmp_slowtimo() 402 { 403 int s = splnet(); 404 register struct router_info *rti = Head; 405 406 #ifdef IGMP_DEBUG 407 printf("[igmp.c,_slowtimo] -- > entering \n"); 408 #endif 409 while (rti) { 410 if (rti->rti_type == IGMP_V1_ROUTER) { 411 rti->rti_time++; 412 if (rti->rti_time >= IGMP_AGE_THRESHOLD) { 413 rti->rti_type = IGMP_V2_ROUTER; 414 } 415 } 416 rti = rti->rti_next; 417 } 418 #ifdef IGMP_DEBUG 419 printf("[igmp.c,_slowtimo] -- > exiting \n"); 420 #endif 421 splx(s); 422 } 423 424 static struct route igmprt; 425 426 static void 427 igmp_sendpkt(inm, type, addr) 428 struct in_multi *inm; 429 int type; 430 unsigned long addr; 431 { 432 struct mbuf *m; 433 struct igmp *igmp; 434 struct ip *ip; 435 struct ip_moptions imo; 436 437 MGETHDR(m, M_DONTWAIT, MT_HEADER); 438 if (m == NULL) 439 return; 440 441 m->m_pkthdr.rcvif = loif; 442 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN; 443 MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip)); 444 m->m_data += sizeof(struct ip); 445 m->m_len = IGMP_MINLEN; 446 igmp = mtod(m, struct igmp *); 447 igmp->igmp_type = type; 448 igmp->igmp_code = 0; 449 igmp->igmp_group = inm->inm_addr; 450 igmp->igmp_cksum = 0; 451 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN); 452 453 m->m_data -= sizeof(struct ip); 454 m->m_len += sizeof(struct ip); 455 ip = mtod(m, struct ip *); 456 ip->ip_tos = 0; 457 ip->ip_len = sizeof(struct ip) + IGMP_MINLEN; 458 ip->ip_off = 0; 459 ip->ip_p = IPPROTO_IGMP; 460 ip->ip_src.s_addr = INADDR_ANY; 461 ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr; 462 463 imo.imo_multicast_ifp = inm->inm_ifp; 464 imo.imo_multicast_ttl = 1; 465 imo.imo_multicast_vif = -1; 466 /* 467 * Request loopback of the report if we are acting as a multicast 468 * router, so that the process-level routing demon can hear it. 469 */ 470 imo.imo_multicast_loop = (ip_mrouter != NULL); 471 472 /* 473 * XXX 474 * Do we have to worry about reentrancy here? Don't think so. 475 */ 476 ip_output(m, router_alert, &igmprt, 0, &imo); 477 478 ++igmpstat.igps_snd_reports; 479 }
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