sys/netinet/igmp.c

   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 1.29.2.2 2003/01/23 21:06:44 sam 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/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/in_cksum.h>
  61 #include <sys/thread2.h>
  62
  63 #include <machine/stdarg.h>
  64
  65 #include <net/if.h>
  66 #include <net/route.h>
  67
  68 #include <netinet/in.h>
  69 #include <netinet/in_var.h>
  70 #include <netinet/in_systm.h>
  71 #include <netinet/ip.h>
  72 #include <netinet/ip_var.h>
  73 #include <netinet/igmp.h>
  74 #include <netinet/igmp_var.h>
  75
  76 static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");
  77
  78 static struct router_info *
  79                 find_rti (struct ifnet *ifp);
  80
  81 static struct igmpstat igmpstat;
  82
  83 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW,
  84         &igmpstat, igmpstat, "IGMP statistics");
  85
  86 static int igmp_timers_are_running;
  87 static u_long igmp_all_hosts_group;
  88 static u_long igmp_all_rtrs_group;
  89 static struct mbuf *router_alert;
  90 static struct router_info *Head;
  91
  92 static void igmp_sendpkt (struct in_multi *, int, unsigned long);
  93
  94 void
  95 igmp_init(void)
  96 {
  97         struct ipoption *ra;
  98
  99         /*
 100          * To avoid byte-swapping the same value over and over again.
 101          */
 102         igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
 103         igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);
 104
 105         igmp_timers_are_running = 0;
 106
 107         /*
 108          * Construct a Router Alert option to use in outgoing packets
 109          */
 110         MGET(router_alert, MB_DONTWAIT, MT_DATA);
 111         ra = mtod(router_alert, struct ipoption *);
 112         ra->ipopt_dst.s_addr = 0;
 113         ra->ipopt_list[0] = IPOPT_RA;   /* Router Alert Option */
 114         ra->ipopt_list[1] = 0x04;       /* 4 bytes long */
 115         ra->ipopt_list[2] = 0x00;
 116         ra->ipopt_list[3] = 0x00;
 117         router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];
 118
 119         Head = NULL;
 120 }
 121
 122 static struct router_info *
 123 find_rti(struct ifnet *ifp)
 124 {
 125         struct router_info *rti = Head;
 126
 127 #ifdef IGMP_DEBUG
 128         kprintf("[igmp.c, _find_rti] --> entering \n");
 129 #endif
 130         while (rti) {
 131                 if (rti->rti_ifp == ifp) {
 132 #ifdef IGMP_DEBUG
 133                         kprintf("[igmp.c, _find_rti] --> found old entry \n");
 134 #endif
 135                         return rti;
 136                 }
 137                 rti = rti->rti_next;
 138         }
 139         rti = kmalloc(sizeof *rti, M_IGMP, M_INTWAIT);
 140         rti->rti_ifp = ifp;
 141         rti->rti_type = IGMP_V2_ROUTER;
 142         rti->rti_time = 0;
 143         rti->rti_next = Head;
 144         Head = rti;
 145 #ifdef IGMP_DEBUG
 146         kprintf("[igmp.c, _find_rti] --> created an entry \n");
 147 #endif
 148         return rti;
 149 }
 150
 151 int
 152 igmp_input(struct mbuf **mp, int *offp, int proto)
 153 {
 154         struct mbuf *m = *mp;
 155         int iphlen;
 156         struct igmp *igmp;
 157         struct ip *ip;
 158         int igmplen;
 159         struct ifnet *ifp = m->m_pkthdr.rcvif;
 160         int minlen;
 161         struct in_multi *inm;
 162         struct in_ifaddr *ia;
 163         struct in_multistep step;
 164         struct router_info *rti;
 165         int timer; /** timer value in the igmp query header **/
 166
 167         iphlen = *offp;
 168         *mp = NULL;
 169
 170         ++igmpstat.igps_rcv_total;
 171
 172         ip = mtod(m, struct ip *);
 173         igmplen = ip->ip_len;
 174
 175         /*
 176          * Validate lengths
 177          */
 178         if (igmplen < IGMP_MINLEN) {
 179                 ++igmpstat.igps_rcv_tooshort;
 180                 m_freem(m);
 181                 return(IPPROTO_DONE);
 182         }
 183         minlen = iphlen + IGMP_MINLEN;
 184         if ((m->m_flags & M_EXT || m->m_len < minlen) &&
 185             (m = m_pullup(m, minlen)) == NULL) {
 186                 ++igmpstat.igps_rcv_tooshort;
 187                 return(IPPROTO_DONE);
 188         }
 189
 190         /*
 191          * Validate checksum
 192          */
 193         m->m_data += iphlen;
 194         m->m_len -= iphlen;
 195         igmp = mtod(m, struct igmp *);
 196         if (in_cksum(m, igmplen)) {
 197                 ++igmpstat.igps_rcv_badsum;
 198                 m_freem(m);
 199                 return(IPPROTO_DONE);
 200         }
 201         m->m_data -= iphlen;
 202         m->m_len += iphlen;
 203
 204         ip = mtod(m, struct ip *);
 205         timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
 206         if (timer == 0)
 207                 timer = 1;
 208         rti = find_rti(ifp);
 209
 210         /*
 211          * In the IGMPv2 specification, there are 3 states and a flag.
 212          *
 213          * In Non-Member state, we simply don't have a membership record.
 214          * In Delaying Member state, our timer is running (inm->inm_timer)
 215          * In Idle Member state, our timer is not running (inm->inm_timer==0)
 216          *
 217          * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
 218          * we have heard a report from another member, or IGMP_IREPORTEDLAST
 219          * if I sent the last report.
 220          */
 221         switch (igmp->igmp_type) {
 222
 223         case IGMP_MEMBERSHIP_QUERY:
 224                 ++igmpstat.igps_rcv_queries;
 225
 226                 if (ifp->if_flags & IFF_LOOPBACK)
 227                         break;
 228
 229                 if (igmp->igmp_code == 0) {
 230                         /*
 231                          * Old router.  Remember that the querier on this
 232                          * interface is old, and set the timer to the
 233                          * value in RFC 1112.
 234                          */
 235
 236                         rti->rti_type = IGMP_V1_ROUTER;
 237                         rti->rti_time = 0;
 238
 239                         timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
 240
 241                         if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
 242                             igmp->igmp_group.s_addr != 0) {
 243                                 ++igmpstat.igps_rcv_badqueries;
 244                                 m_freem(m);
 245                                 return(IPPROTO_DONE);
 246                         }
 247                 } else {
 248                         /*
 249                          * New router.  Simply do the new validity check.
 250                          */
 251
 252                         if (igmp->igmp_group.s_addr != 0 &&
 253                             !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
 254                                 ++igmpstat.igps_rcv_badqueries;
 255                                 m_freem(m);
 256                                 return(IPPROTO_DONE);
 257                         }
 258                 }
 259
 260                 /*
 261                  * - Start the timers in all of our membership records
 262                  *   that the query applies to for the interface on
 263                  *   which the query arrived excl. those that belong
 264                  *   to the "all-hosts" group (224.0.0.1).
 265                  * - Restart any timer that is already running but has
 266                  *   a value longer than the requested timeout.
 267                  * - Use the value specified in the query message as
 268                  *   the maximum timeout.
 269                  */
 270                 IN_FIRST_MULTI(step, inm);
 271                 while (inm != NULL) {
 272                         if (inm->inm_ifp == ifp &&
 273                             inm->inm_addr.s_addr != igmp_all_hosts_group &&
 274                             (igmp->igmp_group.s_addr == 0 ||
 275                              igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
 276                                 if (inm->inm_timer == 0 ||
 277                                     inm->inm_timer > timer) {
 278                                         inm->inm_timer =
 279                                                 IGMP_RANDOM_DELAY(timer);
 280                                         igmp_timers_are_running = 1;
 281                                 }
 282                         }
 283                         IN_NEXT_MULTI(step, inm);
 284                 }
 285
 286                 break;
 287
 288         case IGMP_V1_MEMBERSHIP_REPORT:
 289         case IGMP_V2_MEMBERSHIP_REPORT:
 290                 /*
 291                  * For fast leave to work, we have to know that we are the
 292                  * last person to send a report for this group.  Reports
 293                  * can potentially get looped back if we are a multicast
 294                  * router, so discard reports sourced by me.
 295                  */
 296                 ia = IFP_TO_IA(ifp);
 297                 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
 298                         break;
 299
 300                 ++igmpstat.igps_rcv_reports;
 301
 302                 if (ifp->if_flags & IFF_LOOPBACK)
 303                         break;
 304
 305                 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
 306                         ++igmpstat.igps_rcv_badreports;
 307                         m_freem(m);
 308                         return(IPPROTO_DONE);
 309                 }
 310
 311                 /*
 312                  * KLUDGE: if the IP source address of the report has an
 313                  * unspecified (i.e., zero) subnet number, as is allowed for
 314                  * a booting host, replace it with the correct subnet number
 315                  * so that a process-level multicast routing demon can
 316                  * determine which subnet it arrived from.  This is necessary
 317                  * to compensate for the lack of any way for a process to
 318                  * determine the arrival interface of an incoming packet.
 319                  */
 320                 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
 321                         if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
 322
 323                 /*
 324                  * If we belong to the group being reported, stop
 325                  * our timer for that group.
 326                  */
 327                 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
 328
 329                 if (inm != NULL) {
 330                         inm->inm_timer = 0;
 331                         ++igmpstat.igps_rcv_ourreports;
 332
 333                         inm->inm_state = IGMP_OTHERMEMBER;
 334                 }
 335
 336                 break;
 337         }
 338
 339         /*
 340          * Pass all valid IGMP packets up to any process(es) listening
 341          * on a raw IGMP socket.
 342          */
 343         *mp = m;
 344         rip_input(mp, offp, proto);
 345         return(IPPROTO_DONE);
 346 }
 347
 348 void
 349 igmp_joingroup(struct in_multi *inm)
 350 {
 351         crit_enter();
 352         if (inm->inm_addr.s_addr == igmp_all_hosts_group
 353             || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
 354                 inm->inm_timer = 0;
 355                 inm->inm_state = IGMP_OTHERMEMBER;
 356         } else {
 357                 inm->inm_rti = find_rti(inm->inm_ifp);
 358                 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
 359                 inm->inm_timer = IGMP_RANDOM_DELAY(
 360                                         IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
 361                 inm->inm_state = IGMP_IREPORTEDLAST;
 362                 igmp_timers_are_running = 1;
 363         }
 364         crit_exit();
 365 }
 366
 367 void
 368 igmp_leavegroup(struct in_multi *inm)
 369 {
 370         if (inm->inm_state == IGMP_IREPORTEDLAST &&
 371             inm->inm_addr.s_addr != igmp_all_hosts_group &&
 372             !(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
 373             inm->inm_rti->rti_type != IGMP_V1_ROUTER)
 374                 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
 375 }
 376
 377 void
 378 igmp_fasttimo(void)
 379 {
 380         struct in_multi *inm;
 381         struct in_multistep step;
 382
 383         /*
 384          * Quick check to see if any work needs to be done, in order
 385          * to minimize the overhead of fasttimo processing.
 386          */
 387
 388         if (!igmp_timers_are_running)
 389                 return;
 390
 391         crit_enter();
 392         igmp_timers_are_running = 0;
 393         IN_FIRST_MULTI(step, inm);
 394         while (inm != NULL) {
 395                 if (inm->inm_timer == 0) {
 396                         /* do nothing */
 397                 } else if (--inm->inm_timer == 0) {
 398                         igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
 399                         inm->inm_state = IGMP_IREPORTEDLAST;
 400                 } else {
 401                         igmp_timers_are_running = 1;
 402                 }
 403                 IN_NEXT_MULTI(step, inm);
 404         }
 405         crit_exit();
 406 }
 407
 408 void
 409 igmp_slowtimo(void)
 410 {
 411         struct router_info *rti =  Head;
 412
 413         crit_enter();
 414 #ifdef IGMP_DEBUG
 415         kprintf("[igmp.c,_slowtimo] -- > entering \n");
 416 #endif
 417         while (rti) {
 418             if (rti->rti_type == IGMP_V1_ROUTER) {
 419                 rti->rti_time++;
 420                 if (rti->rti_time >= IGMP_AGE_THRESHOLD) {
 421                         rti->rti_type = IGMP_V2_ROUTER;
 422                 }
 423             }
 424             rti = rti->rti_next;
 425         }
 426 #ifdef IGMP_DEBUG
 427         kprintf("[igmp.c,_slowtimo] -- > exiting \n");
 428 #endif
 429         crit_exit();
 430 }
 431
 432 static struct route igmprt;
 433
 434 static void
 435 igmp_sendpkt(struct in_multi *inm, int type, 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, MB_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, NULL);
 482
 483         ++igmpstat.igps_snd_reports;
 484 }