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: releng/5.0/sys/netinet/igmp.c 107113 2002-11-20 19:00:54Z luigi $ 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 "opt_mac.h" 53 54 #include <sys/param.h> 55 #include <sys/systm.h> 56 #include <sys/mac.h> 57 #include <sys/malloc.h> 58 #include <sys/mbuf.h> 59 #include <sys/socket.h> 60 #include <sys/protosw.h> 61 #include <sys/kernel.h> 62 #include <sys/sysctl.h> 63 64 #include <net/if.h> 65 #include <net/route.h> 66 67 #include <netinet/in.h> 68 #include <netinet/in_var.h> 69 #include <netinet/in_systm.h> 70 #include <netinet/ip.h> 71 #include <netinet/ip_var.h> 72 #include <netinet/igmp.h> 73 #include <netinet/igmp_var.h> 74 75 #include <machine/in_cksum.h> 76 77 static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state"); 78 79 static struct router_info * 80 find_rti(struct ifnet *ifp); 81 82 static struct igmpstat igmpstat; 83 84 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, 85 &igmpstat, igmpstat, ""); 86 87 static int igmp_timers_are_running; 88 static u_long igmp_all_hosts_group; 89 static u_long igmp_all_rtrs_group; 90 static struct mbuf *router_alert; 91 static struct router_info *Head; 92 93 static void igmp_sendpkt(struct in_multi *, int, unsigned long); 94 95 void 96 igmp_init() 97 { 98 struct ipoption *ra; 99 100 /* 101 * To avoid byte-swapping the same value over and over again. 102 */ 103 igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP); 104 igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP); 105 106 igmp_timers_are_running = 0; 107 108 /* 109 * Construct a Router Alert option to use in outgoing packets 110 */ 111 MGET(router_alert, M_DONTWAIT, MT_DATA); 112 ra = mtod(router_alert, struct ipoption *); 113 ra->ipopt_dst.s_addr = 0; 114 ra->ipopt_list[0] = IPOPT_RA; /* Router Alert Option */ 115 ra->ipopt_list[1] = 0x04; /* 4 bytes long */ 116 ra->ipopt_list[2] = 0x00; 117 ra->ipopt_list[3] = 0x00; 118 router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1]; 119 120 Head = (struct router_info *) 0; 121 } 122 123 static struct router_info * 124 find_rti(ifp) 125 struct ifnet *ifp; 126 { 127 register struct router_info *rti = Head; 128 129 #ifdef IGMP_DEBUG 130 printf("[igmp.c, _find_rti] --> entering \n"); 131 #endif 132 while (rti) { 133 if (rti->rti_ifp == ifp) { 134 #ifdef IGMP_DEBUG 135 printf("[igmp.c, _find_rti] --> found old entry \n"); 136 #endif 137 return rti; 138 } 139 rti = rti->rti_next; 140 } 141 MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT); 142 rti->rti_ifp = ifp; 143 rti->rti_type = IGMP_V2_ROUTER; 144 rti->rti_time = 0; 145 rti->rti_next = Head; 146 Head = rti; 147 #ifdef IGMP_DEBUG 148 printf("[igmp.c, _find_rti] --> created an entry \n"); 149 #endif 150 return rti; 151 } 152 153 void 154 igmp_input(m, off) 155 register struct mbuf *m; 156 int off; 157 { 158 register int iphlen = off; 159 register struct igmp *igmp; 160 register struct ip *ip; 161 register int igmplen; 162 register struct ifnet *ifp = m->m_pkthdr.rcvif; 163 register int minlen; 164 register struct in_multi *inm; 165 register struct in_ifaddr *ia; 166 struct in_multistep step; 167 struct router_info *rti; 168 169 int timer; /** timer value in the igmp query header **/ 170 171 ++igmpstat.igps_rcv_total; 172 173 ip = mtod(m, struct ip *); 174 igmplen = ip->ip_len; 175 176 /* 177 * Validate lengths 178 */ 179 if (igmplen < IGMP_MINLEN) { 180 ++igmpstat.igps_rcv_tooshort; 181 m_freem(m); 182 return; 183 } 184 minlen = iphlen + IGMP_MINLEN; 185 if ((m->m_flags & M_EXT || m->m_len < minlen) && 186 (m = m_pullup(m, minlen)) == 0) { 187 ++igmpstat.igps_rcv_tooshort; 188 return; 189 } 190 191 /* 192 * Validate checksum 193 */ 194 m->m_data += iphlen; 195 m->m_len -= iphlen; 196 igmp = mtod(m, struct igmp *); 197 if (in_cksum(m, igmplen)) { 198 ++igmpstat.igps_rcv_badsum; 199 m_freem(m); 200 return; 201 } 202 m->m_data -= iphlen; 203 m->m_len += iphlen; 204 205 ip = mtod(m, struct ip *); 206 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE; 207 if (timer == 0) 208 timer = 1; 209 rti = find_rti(ifp); 210 211 /* 212 * In the IGMPv2 specification, there are 3 states and a flag. 213 * 214 * In Non-Member state, we simply don't have a membership record. 215 * In Delaying Member state, our timer is running (inm->inm_timer) 216 * In Idle Member state, our timer is not running (inm->inm_timer==0) 217 * 218 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if 219 * we have heard a report from another member, or IGMP_IREPORTEDLAST 220 * if I sent the last report. 221 */ 222 switch (igmp->igmp_type) { 223 224 case IGMP_MEMBERSHIP_QUERY: 225 ++igmpstat.igps_rcv_queries; 226 227 if (ifp->if_flags & IFF_LOOPBACK) 228 break; 229 230 if (igmp->igmp_code == 0) { 231 /* 232 * Old router. Remember that the querier on this 233 * interface is old, and set the timer to the 234 * value in RFC 1112. 235 */ 236 237 rti->rti_type = IGMP_V1_ROUTER; 238 rti->rti_time = 0; 239 240 timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ; 241 242 if (ip->ip_dst.s_addr != igmp_all_hosts_group || 243 igmp->igmp_group.s_addr != 0) { 244 ++igmpstat.igps_rcv_badqueries; 245 m_freem(m); 246 return; 247 } 248 } else { 249 /* 250 * New router. Simply do the new validity check. 251 */ 252 253 if (igmp->igmp_group.s_addr != 0 && 254 !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 255 ++igmpstat.igps_rcv_badqueries; 256 m_freem(m); 257 return; 258 } 259 } 260 261 /* 262 * - Start the timers in all of our membership records 263 * that the query applies to for the interface on 264 * which the query arrived excl. those that belong 265 * to the "all-hosts" group (224.0.0.1). 266 * - Restart any timer that is already running but has 267 * a value longer than the requested timeout. 268 * - Use the value specified in the query message as 269 * the maximum timeout. 270 */ 271 IN_FIRST_MULTI(step, inm); 272 while (inm != NULL) { 273 if (inm->inm_ifp == ifp && 274 inm->inm_addr.s_addr != igmp_all_hosts_group && 275 (igmp->igmp_group.s_addr == 0 || 276 igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) { 277 if (inm->inm_timer == 0 || 278 inm->inm_timer > timer) { 279 inm->inm_timer = 280 IGMP_RANDOM_DELAY(timer); 281 igmp_timers_are_running = 1; 282 } 283 } 284 IN_NEXT_MULTI(step, inm); 285 } 286 287 break; 288 289 case IGMP_V1_MEMBERSHIP_REPORT: 290 case IGMP_V2_MEMBERSHIP_REPORT: 291 /* 292 * For fast leave to work, we have to know that we are the 293 * last person to send a report for this group. Reports 294 * can potentially get looped back if we are a multicast 295 * router, so discard reports sourced by me. 296 */ 297 IFP_TO_IA(ifp, ia); 298 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr) 299 break; 300 301 ++igmpstat.igps_rcv_reports; 302 303 if (ifp->if_flags & IFF_LOOPBACK) 304 break; 305 306 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 307 ++igmpstat.igps_rcv_badreports; 308 m_freem(m); 309 return; 310 } 311 312 /* 313 * KLUDGE: if the IP source address of the report has an 314 * unspecified (i.e., zero) subnet number, as is allowed for 315 * a booting host, replace it with the correct subnet number 316 * so that a process-level multicast routing daemon can 317 * determine which subnet it arrived from. This is necessary 318 * to compensate for the lack of any way for a process to 319 * determine the arrival interface of an incoming packet. 320 */ 321 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) 322 if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet); 323 324 /* 325 * If we belong to the group being reported, stop 326 * our timer for that group. 327 */ 328 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 329 330 if (inm != NULL) { 331 inm->inm_timer = 0; 332 ++igmpstat.igps_rcv_ourreports; 333 334 inm->inm_state = IGMP_OTHERMEMBER; 335 } 336 337 break; 338 } 339 340 /* 341 * Pass all valid IGMP packets up to any process(es) listening 342 * on a raw IGMP socket. 343 */ 344 rip_input(m, off); 345 } 346 347 void 348 igmp_joingroup(inm) 349 struct in_multi *inm; 350 { 351 int s = splnet(); 352 353 if (inm->inm_addr.s_addr == igmp_all_hosts_group 354 || inm->inm_ifp->if_flags & IFF_LOOPBACK) { 355 inm->inm_timer = 0; 356 inm->inm_state = IGMP_OTHERMEMBER; 357 } else { 358 inm->inm_rti = find_rti(inm->inm_ifp); 359 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 360 inm->inm_timer = IGMP_RANDOM_DELAY( 361 IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ); 362 inm->inm_state = IGMP_IREPORTEDLAST; 363 igmp_timers_are_running = 1; 364 } 365 splx(s); 366 } 367 368 void 369 igmp_leavegroup(inm) 370 struct in_multi *inm; 371 { 372 if (inm->inm_state == IGMP_IREPORTEDLAST && 373 inm->inm_addr.s_addr != igmp_all_hosts_group && 374 !(inm->inm_ifp->if_flags & IFF_LOOPBACK) && 375 inm->inm_rti->rti_type != IGMP_V1_ROUTER) 376 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group); 377 } 378 379 void 380 igmp_fasttimo() 381 { 382 register struct in_multi *inm; 383 struct in_multistep step; 384 int s; 385 386 /* 387 * Quick check to see if any work needs to be done, in order 388 * to minimize the overhead of fasttimo processing. 389 */ 390 391 if (!igmp_timers_are_running) 392 return; 393 394 s = splnet(); 395 igmp_timers_are_running = 0; 396 IN_FIRST_MULTI(step, inm); 397 while (inm != NULL) { 398 if (inm->inm_timer == 0) { 399 /* do nothing */ 400 } else if (--inm->inm_timer == 0) { 401 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 402 inm->inm_state = IGMP_IREPORTEDLAST; 403 } else { 404 igmp_timers_are_running = 1; 405 } 406 IN_NEXT_MULTI(step, inm); 407 } 408 splx(s); 409 } 410 411 void 412 igmp_slowtimo() 413 { 414 int s = splnet(); 415 register struct router_info *rti = Head; 416 417 #ifdef IGMP_DEBUG 418 printf("[igmp.c,_slowtimo] -- > entering \n"); 419 #endif 420 while (rti) { 421 if (rti->rti_type == IGMP_V1_ROUTER) { 422 rti->rti_time++; 423 if (rti->rti_time >= IGMP_AGE_THRESHOLD) { 424 rti->rti_type = IGMP_V2_ROUTER; 425 } 426 } 427 rti = rti->rti_next; 428 } 429 #ifdef IGMP_DEBUG 430 printf("[igmp.c,_slowtimo] -- > exiting \n"); 431 #endif 432 splx(s); 433 } 434 435 static struct route igmprt; 436 437 static void 438 igmp_sendpkt(inm, type, addr) 439 struct in_multi *inm; 440 int type; 441 unsigned long addr; 442 { 443 struct mbuf *m; 444 struct igmp *igmp; 445 struct ip *ip; 446 struct ip_moptions imo; 447 448 MGETHDR(m, M_DONTWAIT, MT_HEADER); 449 if (m == NULL) 450 return; 451 452 m->m_pkthdr.rcvif = loif; 453 #ifdef MAC 454 mac_create_mbuf_linklayer(inm->inm_ifp, m); 455 #endif 456 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN; 457 MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip)); 458 m->m_data += sizeof(struct ip); 459 m->m_len = IGMP_MINLEN; 460 igmp = mtod(m, struct igmp *); 461 igmp->igmp_type = type; 462 igmp->igmp_code = 0; 463 igmp->igmp_group = inm->inm_addr; 464 igmp->igmp_cksum = 0; 465 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN); 466 467 m->m_data -= sizeof(struct ip); 468 m->m_len += sizeof(struct ip); 469 ip = mtod(m, struct ip *); 470 ip->ip_tos = 0; 471 ip->ip_len = sizeof(struct ip) + IGMP_MINLEN; 472 ip->ip_off = 0; 473 ip->ip_p = IPPROTO_IGMP; 474 ip->ip_src.s_addr = INADDR_ANY; 475 ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr; 476 477 imo.imo_multicast_ifp = inm->inm_ifp; 478 imo.imo_multicast_ttl = 1; 479 imo.imo_multicast_vif = -1; 480 /* 481 * Request loopback of the report if we are acting as a multicast 482 * router, so that the process-level routing daemon can hear it. 483 */ 484 imo.imo_multicast_loop = (ip_mrouter != NULL); 485 486 /* 487 * XXX 488 * Do we have to worry about reentrancy here? Don't think so. 489 */ 490 ip_output(m, router_alert, &igmprt, 0, &imo, NULL); 491 492 ++igmpstat.igps_snd_reports; 493 }
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