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  * $DragonFly: src/sys/netinet/igmp.c,v 1.14 2008/06/08 08:38:05 sephe Exp $
  40  */
  41
  42 /*
  43  * Internet Group Management Protocol (IGMP) routines.
  44  *
  45  * Written by Steve Deering, Stanford, May 1988.
  46  * Modified by Rosen Sharma, Stanford, Aug 1994.
  47  * Modified by Bill Fenner, Xerox PARC, Feb 1995.
  48  * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
  49  *
  50  * MULTICAST Revision: 3.5.1.4
  51  */
  52
  53 #include <sys/param.h>
  54 #include <sys/systm.h>
  55 #include <sys/malloc.h>
  56 #include <sys/mbuf.h>
  57 #include <sys/socket.h>
  58 #include <sys/protosw.h>
  59 #include <sys/kernel.h>
  60 #include <sys/sysctl.h>
  61 #include <sys/in_cksum.h>
  62 #include <sys/thread2.h>
  63
  64 #include <machine/stdarg.h>
  65
  66 #include <net/if.h>
  67 #include <net/route.h>
  68
  69 #include <netinet/in.h>
  70 #include <netinet/in_var.h>
  71 #include <netinet/in_systm.h>
  72 #include <netinet/ip.h>
  73 #include <netinet/ip_var.h>
  74 #include <netinet/igmp.h>
  75 #include <netinet/igmp_var.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(void)
  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, MB_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 = NULL;
 121 }
 122
 123 static struct router_info *
 124 find_rti(struct ifnet *ifp)
 125 {
 126         struct router_info *rti = Head;
 127
 128 #ifdef IGMP_DEBUG
 129         kprintf("[igmp.c, _find_rti] --> entering \n");
 130 #endif
 131         while (rti) {
 132                 if (rti->rti_ifp == ifp) {
 133 #ifdef IGMP_DEBUG
 134                         kprintf("[igmp.c, _find_rti] --> found old entry \n");
 135 #endif
 136                         return rti;
 137                 }
 138                 rti = rti->rti_next;
 139         }
 140         MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_INTWAIT);
 141         rti->rti_ifp = ifp;
 142         rti->rti_type = IGMP_V2_ROUTER;
 143         rti->rti_time = 0;
 144         rti->rti_next = Head;
 145         Head = rti;
 146 #ifdef IGMP_DEBUG
 147         kprintf("[igmp.c, _find_rti] --> created an entry \n");
 148 #endif
 149         return rti;
 150 }
 151
 152 void
 153 igmp_input(struct mbuf *m, ...)
 154 {
 155         int iphlen, off, proto;
 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         __va_list ap;
 166
 167         int timer; /** timer value in the igmp query header **/
 168
 169         __va_start(ap, m);
 170         off = __va_arg(ap, int);
 171         proto = __va_arg(ap, int);
 172         __va_end(ap);
 173
 174         iphlen = off;
 175
 176         ++igmpstat.igps_rcv_total;
 177
 178         ip = mtod(m, struct ip *);
 179         igmplen = ip->ip_len;
 180
 181         /*
 182          * Validate lengths
 183          */
 184         if (igmplen < IGMP_MINLEN) {
 185                 ++igmpstat.igps_rcv_tooshort;
 186                 m_freem(m);
 187                 return;
 188         }
 189         minlen = iphlen + IGMP_MINLEN;
 190         if ((m->m_flags & M_EXT || m->m_len < minlen) &&
 191             (m = m_pullup(m, minlen)) == 0) {
 192                 ++igmpstat.igps_rcv_tooshort;
 193                 return;
 194         }
 195
 196         /*
 197          * Validate checksum
 198          */
 199         m->m_data += iphlen;
 200         m->m_len -= iphlen;
 201         igmp = mtod(m, struct igmp *);
 202         if (in_cksum(m, igmplen)) {
 203                 ++igmpstat.igps_rcv_badsum;
 204                 m_freem(m);
 205                 return;
 206         }
 207         m->m_data -= iphlen;
 208         m->m_len += iphlen;
 209
 210         ip = mtod(m, struct ip *);
 211         timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
 212         if (timer == 0)
 213                 timer = 1;
 214         rti = find_rti(ifp);
 215
 216         /*
 217          * In the IGMPv2 specification, there are 3 states and a flag.
 218          *
 219          * In Non-Member state, we simply don't have a membership record.
 220          * In Delaying Member state, our timer is running (inm->inm_timer)
 221          * In Idle Member state, our timer is not running (inm->inm_timer==0)
 222          *
 223          * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
 224          * we have heard a report from another member, or IGMP_IREPORTEDLAST
 225          * if I sent the last report.
 226          */
 227         switch (igmp->igmp_type) {
 228
 229         case IGMP_MEMBERSHIP_QUERY:
 230                 ++igmpstat.igps_rcv_queries;
 231
 232                 if (ifp->if_flags & IFF_LOOPBACK)
 233                         break;
 234
 235                 if (igmp->igmp_code == 0) {
 236                         /*
 237                          * Old router.  Remember that the querier on this
 238                          * interface is old, and set the timer to the
 239                          * value in RFC 1112.
 240                          */
 241
 242                         rti->rti_type = IGMP_V1_ROUTER;
 243                         rti->rti_time = 0;
 244
 245                         timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
 246
 247                         if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
 248                             igmp->igmp_group.s_addr != 0) {
 249                                 ++igmpstat.igps_rcv_badqueries;
 250                                 m_freem(m);
 251                                 return;
 252                         }
 253                 } else {
 254                         /*
 255                          * New router.  Simply do the new validity check.
 256                          */
 257
 258                         if (igmp->igmp_group.s_addr != 0 &&
 259                             !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
 260                                 ++igmpstat.igps_rcv_badqueries;
 261                                 m_freem(m);
 262                                 return;
 263                         }
 264                 }
 265
 266                 /*
 267                  * - Start the timers in all of our membership records
 268                  *   that the query applies to for the interface on
 269                  *   which the query arrived excl. those that belong
 270                  *   to the "all-hosts" group (224.0.0.1).
 271                  * - Restart any timer that is already running but has
 272                  *   a value longer than the requested timeout.
 273                  * - Use the value specified in the query message as
 274                  *   the maximum timeout.
 275                  */
 276                 IN_FIRST_MULTI(step, inm);
 277                 while (inm != NULL) {
 278                         if (inm->inm_ifp == ifp &&
 279                             inm->inm_addr.s_addr != igmp_all_hosts_group &&
 280                             (igmp->igmp_group.s_addr == 0 ||
 281                              igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
 282                                 if (inm->inm_timer == 0 ||
 283                                     inm->inm_timer > timer) {
 284                                         inm->inm_timer =
 285                                                 IGMP_RANDOM_DELAY(timer);
 286                                         igmp_timers_are_running = 1;
 287                                 }
 288                         }
 289                         IN_NEXT_MULTI(step, inm);
 290                 }
 291
 292                 break;
 293
 294         case IGMP_V1_MEMBERSHIP_REPORT:
 295         case IGMP_V2_MEMBERSHIP_REPORT:
 296                 /*
 297                  * For fast leave to work, we have to know that we are the
 298                  * last person to send a report for this group.  Reports
 299                  * can potentially get looped back if we are a multicast
 300                  * router, so discard reports sourced by me.
 301                  */
 302                 ia = IFP_TO_IA(ifp);
 303                 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
 304                         break;
 305
 306                 ++igmpstat.igps_rcv_reports;
 307
 308                 if (ifp->if_flags & IFF_LOOPBACK)
 309                         break;
 310
 311                 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
 312                         ++igmpstat.igps_rcv_badreports;
 313                         m_freem(m);
 314                         return;
 315                 }
 316
 317                 /*
 318                  * KLUDGE: if the IP source address of the report has an
 319                  * unspecified (i.e., zero) subnet number, as is allowed for
 320                  * a booting host, replace it with the correct subnet number
 321                  * so that a process-level multicast routing demon can
 322                  * determine which subnet it arrived from.  This is necessary
 323                  * to compensate for the lack of any way for a process to
 324                  * determine the arrival interface of an incoming packet.
 325                  */
 326                 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
 327                         if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
 328
 329                 /*
 330                  * If we belong to the group being reported, stop
 331                  * our timer for that group.
 332                  */
 333                 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
 334
 335                 if (inm != NULL) {
 336                         inm->inm_timer = 0;
 337                         ++igmpstat.igps_rcv_ourreports;
 338
 339                         inm->inm_state = IGMP_OTHERMEMBER;
 340                 }
 341
 342                 break;
 343         }
 344
 345         /*
 346          * Pass all valid IGMP packets up to any process(es) listening
 347          * on a raw IGMP socket.
 348          */
 349         rip_input(m, off, proto);
 350 }
 351
 352 void
 353 igmp_joingroup(struct in_multi *inm)
 354 {
 355         crit_enter();
 356         if (inm->inm_addr.s_addr == igmp_all_hosts_group
 357             || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
 358                 inm->inm_timer = 0;
 359                 inm->inm_state = IGMP_OTHERMEMBER;
 360         } else {
 361                 inm->inm_rti = find_rti(inm->inm_ifp);
 362                 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
 363                 inm->inm_timer = IGMP_RANDOM_DELAY(
 364                                         IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
 365                 inm->inm_state = IGMP_IREPORTEDLAST;
 366                 igmp_timers_are_running = 1;
 367         }
 368         crit_exit();
 369 }
 370
 371 void
 372 igmp_leavegroup(struct in_multi *inm)
 373 {
 374         if (inm->inm_state == IGMP_IREPORTEDLAST &&
 375             inm->inm_addr.s_addr != igmp_all_hosts_group &&
 376             !(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
 377             inm->inm_rti->rti_type != IGMP_V1_ROUTER)
 378                 igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
 379 }
 380
 381 void
 382 igmp_fasttimo(void)
 383 {
 384         struct in_multi *inm;
 385         struct in_multistep step;
 386
 387         /*
 388          * Quick check to see if any work needs to be done, in order
 389          * to minimize the overhead of fasttimo processing.
 390          */
 391
 392         if (!igmp_timers_are_running)
 393                 return;
 394
 395         crit_enter();
 396         igmp_timers_are_running = 0;
 397         IN_FIRST_MULTI(step, inm);
 398         while (inm != NULL) {
 399                 if (inm->inm_timer == 0) {
 400                         /* do nothing */
 401                 } else if (--inm->inm_timer == 0) {
 402                         igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
 403                         inm->inm_state = IGMP_IREPORTEDLAST;
 404                 } else {
 405                         igmp_timers_are_running = 1;
 406                 }
 407                 IN_NEXT_MULTI(step, inm);
 408         }
 409         crit_exit();
 410 }
 411
 412 void
 413 igmp_slowtimo(void)
 414 {
 415         struct router_info *rti =  Head;
 416
 417         crit_enter();
 418 #ifdef IGMP_DEBUG
 419         kprintf("[igmp.c,_slowtimo] -- > entering \n");
 420 #endif
 421         while (rti) {
 422             if (rti->rti_type == IGMP_V1_ROUTER) {
 423                 rti->rti_time++;
 424                 if (rti->rti_time >= IGMP_AGE_THRESHOLD) {
 425                         rti->rti_type = IGMP_V2_ROUTER;
 426                 }
 427             }
 428             rti = rti->rti_next;
 429         }
 430 #ifdef IGMP_DEBUG
 431         kprintf("[igmp.c,_slowtimo] -- > exiting \n");
 432 #endif
 433         crit_exit();
 434 }
 435
 436 static struct route igmprt;
 437
 438 static void
 439 igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr)
 440 {
 441         struct mbuf *m;
 442         struct igmp *igmp;
 443         struct ip *ip;
 444         struct ip_moptions imo;
 445
 446         MGETHDR(m, MB_DONTWAIT, MT_HEADER);
 447         if (m == NULL)
 448                 return;
 449
 450         m->m_pkthdr.rcvif = loif;
 451         m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
 452         MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
 453         m->m_data += sizeof(struct ip);
 454         m->m_len = IGMP_MINLEN;
 455         igmp = mtod(m, struct igmp *);
 456         igmp->igmp_type   = type;
 457         igmp->igmp_code   = 0;
 458         igmp->igmp_group  = inm->inm_addr;
 459         igmp->igmp_cksum  = 0;
 460         igmp->igmp_cksum  = in_cksum(m, IGMP_MINLEN);
 461
 462         m->m_data -= sizeof(struct ip);
 463         m->m_len += sizeof(struct ip);
 464         ip = mtod(m, struct ip *);
 465         ip->ip_tos = 0;
 466         ip->ip_len = sizeof(struct ip) + IGMP_MINLEN;
 467         ip->ip_off = 0;
 468         ip->ip_p = IPPROTO_IGMP;
 469         ip->ip_src.s_addr = INADDR_ANY;
 470         ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr;
 471
 472         imo.imo_multicast_ifp = inm->inm_ifp;
 473         imo.imo_multicast_ttl = 1;
 474         imo.imo_multicast_vif = -1;
 475         /*
 476          * Request loopback of the report if we are acting as a multicast
 477          * router, so that the process-level routing demon can hear it.
 478          */
 479         imo.imo_multicast_loop = (ip_mrouter != NULL);
 480
 481         /*
 482          * XXX
 483          * Do we have to worry about reentrancy here?  Don't think so.
 484          */
 485         ip_output(m, router_alert, &igmprt, 0, &imo, NULL);
 486
 487         ++igmpstat.igps_snd_reports;
 488 }