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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 1.27.2.1 1999/08/29 16:29:32 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/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 
   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 __P((struct ifnet *ifp));
   76 
   77 static struct igmpstat igmpstat;
   78 
   79 SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RD,
   80         &igmpstat, igmpstat, "");
   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 __P((struct in_multi *, int, unsigned long));
   89 
   90 void
   91 igmp_init()
   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, M_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 = (struct router_info *) 0;
  116 }
  117 
  118 static struct router_info *
  119 find_rti(ifp)
  120         struct ifnet *ifp;
  121 {
  122         register struct router_info *rti = Head;
  123 
  124 #ifdef IGMP_DEBUG
  125         printf("[igmp.c, _find_rti] --> entering \n");
  126 #endif
  127         while (rti) {
  128                 if (rti->rti_ifp == ifp) {
  129 #ifdef IGMP_DEBUG
  130                         printf("[igmp.c, _find_rti] --> found old entry \n");
  131 #endif
  132                         return rti;
  133                 }
  134                 rti = rti->rti_next;
  135         }
  136         MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT);
  137         rti->rti_ifp = ifp;
  138         rti->rti_type = IGMP_V2_ROUTER;
  139         rti->rti_time = 0;
  140         rti->rti_next = Head;
  141         Head = rti;
  142 #ifdef IGMP_DEBUG
  143         printf("[igmp.c, _find_rti] --> created an entry \n");
  144 #endif
  145         return rti;
  146 }
  147 
  148 void
  149 igmp_input(m, iphlen)
  150         register struct mbuf *m;
  151         register int iphlen;
  152 {
  153         register struct igmp *igmp;
  154         register struct ip *ip;
  155         register int igmplen;
  156         register struct ifnet *ifp = m->m_pkthdr.rcvif;
  157         register int minlen;
  158         register struct in_multi *inm;
  159         register struct in_ifaddr *ia;
  160         struct in_multistep step;
  161         struct router_info *rti;
  162         
  163         int timer; /** timer value in the igmp query header **/
  164 
  165         ++igmpstat.igps_rcv_total;
  166 
  167         ip = mtod(m, struct ip *);
  168         igmplen = ip->ip_len;
  169 
  170         /*
  171          * Validate lengths
  172          */
  173         if (igmplen < IGMP_MINLEN) {
  174                 ++igmpstat.igps_rcv_tooshort;
  175                 m_freem(m);
  176                 return;
  177         }
  178         minlen = iphlen + IGMP_MINLEN;
  179         if ((m->m_flags & M_EXT || m->m_len < minlen) &&
  180             (m = m_pullup(m, minlen)) == 0) {
  181                 ++igmpstat.igps_rcv_tooshort;
  182                 return;
  183         }
  184 
  185         /*
  186          * Validate checksum
  187          */
  188         m->m_data += iphlen;
  189         m->m_len -= iphlen;
  190         igmp = mtod(m, struct igmp *);
  191         if (in_cksum(m, igmplen)) {
  192                 ++igmpstat.igps_rcv_badsum;
  193                 m_freem(m);
  194                 return;
  195         }
  196         m->m_data -= iphlen;
  197         m->m_len += iphlen;
  198 
  199         ip = mtod(m, struct ip *);
  200         timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
  201         if (timer == 0)
  202                 timer = 1;
  203         rti = find_rti(ifp);
  204 
  205         /*
  206          * In the IGMPv2 specification, there are 3 states and a flag.
  207          *
  208          * In Non-Member state, we simply don't have a membership record.
  209          * In Delaying Member state, our timer is running (inm->inm_timer)
  210          * In Idle Member state, our timer is not running (inm->inm_timer==0)
  211          *
  212          * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
  213          * we have heard a report from another member, or IGMP_IREPORTEDLAST
  214          * if I sent the last report.
  215          */
  216         switch (igmp->igmp_type) {
  217 
  218         case IGMP_MEMBERSHIP_QUERY:
  219                 ++igmpstat.igps_rcv_queries;
  220 
  221                 if (ifp->if_flags & IFF_LOOPBACK)
  222                         break;
  223 
  224                 if (igmp->igmp_code == 0) {
  225                         /*
  226                          * Old router.  Remember that the querier on this
  227                          * interface is old, and set the timer to the
  228                          * value in RFC 1112.
  229                          */
  230 
  231                         rti->rti_type = IGMP_V1_ROUTER;
  232                         rti->rti_time = 0;
  233 
  234                         timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
  235 
  236                         if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
  237                             igmp->igmp_group.s_addr != 0) {
  238                                 ++igmpstat.igps_rcv_badqueries;
  239                                 m_freem(m);
  240                                 return;
  241                         }
  242                 } else {
  243                         /*
  244                          * New router.  Simply do the new validity check.
  245                          */
  246                         
  247                         if (igmp->igmp_group.s_addr != 0 &&
  248                             !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
  249                                 ++igmpstat.igps_rcv_badqueries;
  250                                 m_freem(m);
  251                                 return;
  252                         }
  253                 }
  254 
  255                 /*
  256                  * - Start the timers in all of our membership records
  257                  *   that the query applies to for the interface on
  258                  *   which the query arrived excl. those that belong
  259                  *   to the "all-hosts" group (224.0.0.1).
  260                  * - Restart any timer that is already running but has
  261                  *   a value longer than the requested timeout.
  262                  * - Use the value specified in the query message as
  263                  *   the maximum timeout.
  264                  */
  265                 IN_FIRST_MULTI(step, inm);
  266                 while (inm != NULL) {
  267                         if (inm->inm_ifp == ifp &&
  268                             inm->inm_addr.s_addr != igmp_all_hosts_group &&
  269                             (igmp->igmp_group.s_addr == 0 ||
  270                              igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
  271                                 if (inm->inm_timer == 0 ||
  272                                     inm->inm_timer > timer) {
  273                                         inm->inm_timer =
  274                                                 IGMP_RANDOM_DELAY(timer);
  275                                         igmp_timers_are_running = 1;
  276                                 }
  277                         }
  278                         IN_NEXT_MULTI(step, inm);
  279                 }
  280 
  281                 break;
  282 
  283         case IGMP_V1_MEMBERSHIP_REPORT:
  284         case IGMP_V2_MEMBERSHIP_REPORT:
  285                 /*
  286                  * For fast leave to work, we have to know that we are the
  287                  * last person to send a report for this group.  Reports
  288                  * can potentially get looped back if we are a multicast
  289                  * router, so discard reports sourced by me.
  290                  */
  291                 IFP_TO_IA(ifp, ia);
  292                 if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
  293                         break;
  294 
  295                 ++igmpstat.igps_rcv_reports;
  296 
  297                 if (ifp->if_flags & IFF_LOOPBACK)
  298                         break;
  299 
  300                 if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
  301                         ++igmpstat.igps_rcv_badreports;
  302                         m_freem(m);
  303                         return;
  304                 }
  305 
  306                 /*
  307                  * KLUDGE: if the IP source address of the report has an
  308                  * unspecified (i.e., zero) subnet number, as is allowed for
  309                  * a booting host, replace it with the correct subnet number
  310                  * so that a process-level multicast routing demon can
  311                  * determine which subnet it arrived from.  This is necessary
  312                  * to compensate for the lack of any way for a process to
  313                  * determine the arrival interface of an incoming packet.
  314                  */
  315                 if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
  316                         if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
  317 
  318                 /*
  319                  * If we belong to the group being reported, stop
  320                  * our timer for that group.
  321                  */
  322                 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
  323 
  324                 if (inm != NULL) {
  325                         inm->inm_timer = 0;
  326                         ++igmpstat.igps_rcv_ourreports;
  327 
  328                         inm->inm_state = IGMP_OTHERMEMBER;
  329                 }
  330 
  331                 break;
  332         }
  333 
  334         /*
  335          * Pass all valid IGMP packets up to any process(es) listening
  336          * on a raw IGMP socket.
  337          */
  338         rip_input(m, iphlen);
  339 }
  340 
  341 void
  342 igmp_joingroup(inm)
  343         struct in_multi *inm;
  344 {
  345         int s = splnet();
  346 
  347         if (inm->inm_addr.s_addr == igmp_all_hosts_group
  348             || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
  349                 inm->inm_timer = 0;
  350                 inm->inm_state = IGMP_OTHERMEMBER;
  351         } else {
  352                 inm->inm_rti = find_rti(inm->inm_ifp);
  353                 igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
  354                 inm->inm_timer = IGMP_RANDOM_DELAY(
  355                                         IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
  356                 inm->inm_state = IGMP_IREPORTEDLAST;
  357                 igmp_timers_are_running = 1;
  358         }
  359         splx(s);
  360 }
  361 
  362 void
  363 igmp_leavegroup(inm)
  364         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()
  375 {
  376         register struct in_multi *inm;
  377         struct in_multistep step;
  378         int s;
  379 
  380         /*
  381          * Quick check to see if any work needs to be done, in order
  382          * to minimize the overhead of fasttimo processing.
  383          */
  384 
  385         if (!igmp_timers_are_running)
  386                 return;
  387 
  388         s = splnet();
  389         igmp_timers_are_running = 0;
  390         IN_FIRST_MULTI(step, inm);
  391         while (inm != NULL) {
  392                 if (inm->inm_timer == 0) {
  393                         /* do nothing */
  394                 } else if (--inm->inm_timer == 0) {
  395                         igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
  396                         inm->inm_state = IGMP_IREPORTEDLAST;
  397                 } else {
  398                         igmp_timers_are_running = 1;
  399                 }
  400                 IN_NEXT_MULTI(step, inm);
  401         }
  402         splx(s);
  403 }
  404 
  405 void
  406 igmp_slowtimo()
  407 {
  408         int s = splnet();
  409         register struct router_info *rti =  Head;
  410 
  411 #ifdef IGMP_DEBUG
  412         printf("[igmp.c,_slowtimo] -- > entering \n");
  413 #endif
  414         while (rti) {
  415             if (rti->rti_type == IGMP_V1_ROUTER) {
  416                 rti->rti_time++;
  417                 if (rti->rti_time >= IGMP_AGE_THRESHOLD) {
  418                         rti->rti_type = IGMP_V2_ROUTER;
  419                 }
  420             }
  421             rti = rti->rti_next;
  422         }
  423 #ifdef IGMP_DEBUG       
  424         printf("[igmp.c,_slowtimo] -- > exiting \n");
  425 #endif
  426         splx(s);
  427 }
  428 
  429 static struct route igmprt;
  430 
  431 static void
  432 igmp_sendpkt(inm, type, addr)
  433         struct in_multi *inm;
  434         int type;
  435         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, M_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);
  482 
  483         ++igmpstat.igps_snd_reports;
  484 }

Cache object: 15aa38050fcc70e95beaa74e5e9b2507


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