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. 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 * $FreeBSD: src/sys/netinet/igmp.c,v 1.29.2.2 2003/01/23 21:06:44 sam Exp $ 35 */ 36 37 /* 38 * Internet Group Management Protocol (IGMP) routines. 39 * 40 * Written by Steve Deering, Stanford, May 1988. 41 * Modified by Rosen Sharma, Stanford, Aug 1994. 42 * Modified by Bill Fenner, Xerox PARC, Feb 1995. 43 * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995. 44 * 45 * MULTICAST Revision: 3.5.1.4 46 */ 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/malloc.h> 51 #include <sys/mbuf.h> 52 #include <sys/socket.h> 53 #include <sys/protosw.h> 54 #include <sys/kernel.h> 55 #include <sys/sysctl.h> 56 #include <sys/in_cksum.h> 57 #include <sys/thread2.h> 58 59 #include <machine/stdarg.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 (struct ifnet *ifp); 76 77 static struct igmpstat igmpstat; 78 79 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, 80 &igmpstat, igmpstat, "IGMP statistics"); 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 (struct in_multi *, int, unsigned long); 89 90 void 91 igmp_init(void) 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, MB_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 = NULL; 116 } 117 118 static struct router_info * 119 find_rti(struct ifnet *ifp) 120 { 121 struct router_info *rti = Head; 122 123 #ifdef IGMP_DEBUG 124 kprintf("[igmp.c, _find_rti] --> entering \n"); 125 #endif 126 while (rti) { 127 if (rti->rti_ifp == ifp) { 128 #ifdef IGMP_DEBUG 129 kprintf("[igmp.c, _find_rti] --> found old entry \n"); 130 #endif 131 return rti; 132 } 133 rti = rti->rti_next; 134 } 135 rti = kmalloc(sizeof *rti, M_IGMP, M_INTWAIT); 136 rti->rti_ifp = ifp; 137 rti->rti_type = IGMP_V2_ROUTER; 138 rti->rti_time = 0; 139 rti->rti_next = Head; 140 Head = rti; 141 #ifdef IGMP_DEBUG 142 kprintf("[igmp.c, _find_rti] --> created an entry \n"); 143 #endif 144 return rti; 145 } 146 147 int 148 igmp_input(struct mbuf **mp, int *offp, int proto) 149 { 150 struct mbuf *m = *mp; 151 int iphlen; 152 struct igmp *igmp; 153 struct ip *ip; 154 int igmplen; 155 struct ifnet *ifp = m->m_pkthdr.rcvif; 156 int minlen; 157 struct in_multi *inm; 158 struct in_ifaddr *ia; 159 struct in_multistep step; 160 struct router_info *rti; 161 int timer; /** timer value in the igmp query header **/ 162 163 iphlen = *offp; 164 *mp = NULL; 165 166 ++igmpstat.igps_rcv_total; 167 168 ip = mtod(m, struct ip *); 169 igmplen = ip->ip_len; 170 171 /* 172 * Validate lengths 173 */ 174 if (igmplen < IGMP_MINLEN) { 175 ++igmpstat.igps_rcv_tooshort; 176 m_freem(m); 177 return(IPPROTO_DONE); 178 } 179 minlen = iphlen + IGMP_MINLEN; 180 if ((m->m_flags & M_EXT || m->m_len < minlen) && 181 (m = m_pullup(m, minlen)) == NULL) { 182 ++igmpstat.igps_rcv_tooshort; 183 return(IPPROTO_DONE); 184 } 185 186 /* 187 * Validate checksum 188 */ 189 m->m_data += iphlen; 190 m->m_len -= iphlen; 191 igmp = mtod(m, struct igmp *); 192 if (in_cksum(m, igmplen)) { 193 ++igmpstat.igps_rcv_badsum; 194 m_freem(m); 195 return(IPPROTO_DONE); 196 } 197 m->m_data -= iphlen; 198 m->m_len += iphlen; 199 200 ip = mtod(m, struct ip *); 201 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE; 202 if (timer == 0) 203 timer = 1; 204 rti = find_rti(ifp); 205 206 /* 207 * In the IGMPv2 specification, there are 3 states and a flag. 208 * 209 * In Non-Member state, we simply don't have a membership record. 210 * In Delaying Member state, our timer is running (inm->inm_timer) 211 * In Idle Member state, our timer is not running (inm->inm_timer==0) 212 * 213 * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if 214 * we have heard a report from another member, or IGMP_IREPORTEDLAST 215 * if I sent the last report. 216 */ 217 switch (igmp->igmp_type) { 218 219 case IGMP_MEMBERSHIP_QUERY: 220 ++igmpstat.igps_rcv_queries; 221 222 if (ifp->if_flags & IFF_LOOPBACK) 223 break; 224 225 if (igmp->igmp_code == 0) { 226 /* 227 * Old router. Remember that the querier on this 228 * interface is old, and set the timer to the 229 * value in RFC 1112. 230 */ 231 232 rti->rti_type = IGMP_V1_ROUTER; 233 rti->rti_time = 0; 234 235 timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ; 236 237 if (ip->ip_dst.s_addr != igmp_all_hosts_group || 238 igmp->igmp_group.s_addr != 0) { 239 ++igmpstat.igps_rcv_badqueries; 240 m_freem(m); 241 return(IPPROTO_DONE); 242 } 243 } else { 244 /* 245 * New router. Simply do the new validity check. 246 */ 247 248 if (igmp->igmp_group.s_addr != 0 && 249 !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 250 ++igmpstat.igps_rcv_badqueries; 251 m_freem(m); 252 return(IPPROTO_DONE); 253 } 254 } 255 256 /* 257 * - Start the timers in all of our membership records 258 * that the query applies to for the interface on 259 * which the query arrived excl. those that belong 260 * to the "all-hosts" group (224.0.0.1). 261 * - Restart any timer that is already running but has 262 * a value longer than the requested timeout. 263 * - Use the value specified in the query message as 264 * the maximum timeout. 265 */ 266 IN_FIRST_MULTI(step, inm); 267 while (inm != NULL) { 268 if (inm->inm_ifp == ifp && 269 inm->inm_addr.s_addr != igmp_all_hosts_group && 270 (igmp->igmp_group.s_addr == 0 || 271 igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) { 272 if (inm->inm_timer == 0 || 273 inm->inm_timer > timer) { 274 inm->inm_timer = 275 IGMP_RANDOM_DELAY(timer); 276 igmp_timers_are_running = 1; 277 } 278 } 279 IN_NEXT_MULTI(step, inm); 280 } 281 282 break; 283 284 case IGMP_V1_MEMBERSHIP_REPORT: 285 case IGMP_V2_MEMBERSHIP_REPORT: 286 /* 287 * For fast leave to work, we have to know that we are the 288 * last person to send a report for this group. Reports 289 * can potentially get looped back if we are a multicast 290 * router, so discard reports sourced by me. 291 */ 292 ia = IFP_TO_IA(ifp); 293 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr) 294 break; 295 296 ++igmpstat.igps_rcv_reports; 297 298 if (ifp->if_flags & IFF_LOOPBACK) 299 break; 300 301 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) { 302 ++igmpstat.igps_rcv_badreports; 303 m_freem(m); 304 return(IPPROTO_DONE); 305 } 306 307 /* 308 * KLUDGE: if the IP source address of the report has an 309 * unspecified (i.e., zero) subnet number, as is allowed for 310 * a booting host, replace it with the correct subnet number 311 * so that a process-level multicast routing demon can 312 * determine which subnet it arrived from. This is necessary 313 * to compensate for the lack of any way for a process to 314 * determine the arrival interface of an incoming packet. 315 */ 316 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) 317 if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet); 318 319 /* 320 * If we belong to the group being reported, stop 321 * our timer for that group. 322 */ 323 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 324 325 if (inm != NULL) { 326 inm->inm_timer = 0; 327 ++igmpstat.igps_rcv_ourreports; 328 329 inm->inm_state = IGMP_OTHERMEMBER; 330 } 331 332 break; 333 } 334 335 /* 336 * Pass all valid IGMP packets up to any process(es) listening 337 * on a raw IGMP socket. 338 */ 339 *mp = m; 340 rip_input(mp, offp, proto); 341 return(IPPROTO_DONE); 342 } 343 344 void 345 igmp_joingroup(struct in_multi *inm) 346 { 347 crit_enter(); 348 if (inm->inm_addr.s_addr == igmp_all_hosts_group 349 || inm->inm_ifp->if_flags & IFF_LOOPBACK) { 350 inm->inm_timer = 0; 351 inm->inm_state = IGMP_OTHERMEMBER; 352 } else { 353 inm->inm_rti = find_rti(inm->inm_ifp); 354 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 355 inm->inm_timer = IGMP_RANDOM_DELAY( 356 IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ); 357 inm->inm_state = IGMP_IREPORTEDLAST; 358 igmp_timers_are_running = 1; 359 } 360 crit_exit(); 361 } 362 363 void 364 igmp_leavegroup(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(void) 375 { 376 struct in_multi *inm; 377 struct in_multistep step; 378 379 /* 380 * Quick check to see if any work needs to be done, in order 381 * to minimize the overhead of fasttimo processing. 382 */ 383 384 if (!igmp_timers_are_running) 385 return; 386 387 crit_enter(); 388 igmp_timers_are_running = 0; 389 IN_FIRST_MULTI(step, inm); 390 while (inm != NULL) { 391 if (inm->inm_timer == 0) { 392 /* do nothing */ 393 } else if (--inm->inm_timer == 0) { 394 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0); 395 inm->inm_state = IGMP_IREPORTEDLAST; 396 } else { 397 igmp_timers_are_running = 1; 398 } 399 IN_NEXT_MULTI(step, inm); 400 } 401 crit_exit(); 402 } 403 404 void 405 igmp_slowtimo(void) 406 { 407 struct router_info *rti = Head; 408 409 crit_enter(); 410 #ifdef IGMP_DEBUG 411 kprintf("[igmp.c,_slowtimo] -- > entering \n"); 412 #endif 413 while (rti) { 414 if (rti->rti_type == IGMP_V1_ROUTER) { 415 rti->rti_time++; 416 if (rti->rti_time >= IGMP_AGE_THRESHOLD) { 417 rti->rti_type = IGMP_V2_ROUTER; 418 } 419 } 420 rti = rti->rti_next; 421 } 422 #ifdef IGMP_DEBUG 423 kprintf("[igmp.c,_slowtimo] -- > exiting \n"); 424 #endif 425 crit_exit(); 426 } 427 428 static struct route igmprt; 429 430 static void 431 igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr) 432 { 433 struct mbuf *m; 434 struct igmp *igmp; 435 struct ip *ip; 436 struct ip_moptions imo; 437 438 MGETHDR(m, MB_DONTWAIT, MT_HEADER); 439 if (m == NULL) 440 return; 441 442 m->m_pkthdr.rcvif = loif; 443 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN; 444 MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip)); 445 m->m_data += sizeof(struct ip); 446 m->m_len = IGMP_MINLEN; 447 igmp = mtod(m, struct igmp *); 448 igmp->igmp_type = type; 449 igmp->igmp_code = 0; 450 igmp->igmp_group = inm->inm_addr; 451 igmp->igmp_cksum = 0; 452 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN); 453 454 m->m_data -= sizeof(struct ip); 455 m->m_len += sizeof(struct ip); 456 ip = mtod(m, struct ip *); 457 ip->ip_tos = 0; 458 ip->ip_len = sizeof(struct ip) + IGMP_MINLEN; 459 ip->ip_off = 0; 460 ip->ip_p = IPPROTO_IGMP; 461 ip->ip_src.s_addr = INADDR_ANY; 462 ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr; 463 464 imo.imo_multicast_ifp = inm->inm_ifp; 465 imo.imo_multicast_ttl = 1; 466 imo.imo_multicast_vif = -1; 467 /* 468 * Request loopback of the report if we are acting as a multicast 469 * router, so that the process-level routing demon can hear it. 470 */ 471 imo.imo_multicast_loop = (ip_mrouter != NULL); 472 473 /* 474 * XXX 475 * Do we have to worry about reentrancy here? Don't think so. 476 */ 477 ip_output(m, router_alert, &igmprt, 0, &imo, NULL); 478 479 ++igmpstat.igps_snd_reports; 480 }
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