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Annotation of kernel/bsd/netinet/igmp.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            26: /*
        !            27:  * Copyright (c) 1988 Stephen Deering.
        !            28:  * Copyright (c) 1992, 1993
        !            29:  *     The Regents of the University of California.  All rights reserved.
        !            30:  *
        !            31:  * This code is derived from software contributed to Berkeley by
        !            32:  * Stephen Deering of Stanford University.
        !            33:  *
        !            34:  * Redistribution and use in source and binary forms, with or without
        !            35:  * modification, are permitted provided that the following conditions
        !            36:  * are met:
        !            37:  * 1. Redistributions of source code must retain the above copyright
        !            38:  *    notice, this list of conditions and the following disclaimer.
        !            39:  * 2. Redistributions in binary form must reproduce the above copyright
        !            40:  *    notice, this list of conditions and the following disclaimer in the
        !            41:  *    documentation and/or other materials provided with the distribution.
        !            42:  * 3. All advertising materials mentioning features or use of this software
        !            43:  *    must display the following acknowledgement:
        !            44:  *     This product includes software developed by the University of
        !            45:  *     California, Berkeley and its contributors.
        !            46:  * 4. Neither the name of the University nor the names of its contributors
        !            47:  *    may be used to endorse or promote products derived from this software
        !            48:  *    without specific prior written permission.
        !            49:  *
        !            50:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            51:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            52:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            53:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            54:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            55:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            56:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            57:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            58:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            59:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            60:  * SUCH DAMAGE.
        !            61:  *
        !            62:  *     @(#)igmp.c      8.2 (Berkeley) 5/3/95
        !            63:  */
        !            64: 
        !            65: /* Internet Group Management Protocol (IGMP) routines. */
        !            66: 
        !            67: 
        !            68: #include <sys/param.h>
        !            69: #include <sys/mbuf.h>
        !            70: #include <sys/socket.h>
        !            71: #include <sys/protosw.h>
        !            72: 
        !            73: #include <kernserv/machine/spl.h>
        !            74: 
        !            75: #include <net/if.h>
        !            76: #include <net/route.h>
        !            77: 
        !            78: #include <netinet/in.h>
        !            79: #include <netinet/in_var.h>
        !            80: #include <netinet/in_systm.h>
        !            81: #include <netinet/ip.h>
        !            82: #include <netinet/ip_var.h>
        !            83: #include <netinet/igmp.h>
        !            84: #include <netinet/igmp_var.h>
        !            85: 
        !            86: extern struct ifnet loif;
        !            87: 
        !            88: struct igmpstat igmpstat;
        !            89: 
        !            90: static int igmp_timers_are_running = 0;
        !            91: static u_long igmp_all_hosts_group;
        !            92: 
        !            93: static void igmp_sendreport __P((struct in_multi *));
        !            94: 
        !            95: void
        !            96: igmp_init()
        !            97: {
        !            98:        /*
        !            99:         * To avoid byte-swapping the same value over and over again.
        !           100:         */
        !           101:        igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
        !           102: }
        !           103: 
        !           104: void
        !           105: igmp_input(m, iphlen)
        !           106:        register struct mbuf *m;
        !           107:        register int iphlen;
        !           108: {
        !           109:        register struct igmp *igmp;
        !           110:        register struct ip *ip;
        !           111:        register int igmplen;
        !           112:        register struct ifnet *ifp = m->m_pkthdr.rcvif;
        !           113:        register int minlen;
        !           114:        register struct in_multi *inm;
        !           115:        register struct in_ifaddr *ia;
        !           116:        struct in_multistep step;
        !           117: 
        !           118:        ++igmpstat.igps_rcv_total;
        !           119: 
        !           120:        ip = mtod(m, struct ip *);
        !           121:        igmplen = ip->ip_len;
        !           122: 
        !           123:        /*
        !           124:         * Validate lengths
        !           125:         */
        !           126:        if (igmplen < IGMP_MINLEN) {
        !           127:                ++igmpstat.igps_rcv_tooshort;
        !           128:                m_freem(m);
        !           129:                return;
        !           130:        }
        !           131:        minlen = iphlen + IGMP_MINLEN;
        !           132:        if ((m->m_flags & M_EXT || m->m_len < minlen) &&
        !           133:            (m = m_pullup(m, minlen)) == 0) {
        !           134:                ++igmpstat.igps_rcv_tooshort;
        !           135:                return;
        !           136:        }
        !           137: 
        !           138:        /*
        !           139:         * Validate checksum
        !           140:         */
        !           141:        m->m_data += iphlen;
        !           142:        m->m_len -= iphlen;
        !           143:        igmp = mtod(m, struct igmp *);
        !           144:        if (in_cksum(m, igmplen)) {
        !           145:                ++igmpstat.igps_rcv_badsum;
        !           146:                m_freem(m);
        !           147:                return;
        !           148:        }
        !           149:        m->m_data -= iphlen;
        !           150:        m->m_len += iphlen;
        !           151:        ip = mtod(m, struct ip *);
        !           152: 
        !           153:        switch (igmp->igmp_type) {
        !           154: 
        !           155:        case IGMP_HOST_MEMBERSHIP_QUERY:
        !           156:                ++igmpstat.igps_rcv_queries;
        !           157: 
        !           158:                if (ifp == &loif)
        !           159:                        break;
        !           160: 
        !           161:                if (ip->ip_dst.s_addr != igmp_all_hosts_group) {
        !           162:                        ++igmpstat.igps_rcv_badqueries;
        !           163:                        m_freem(m);
        !           164:                        return;
        !           165:                }
        !           166: 
        !           167:                /*
        !           168:                 * Start the timers in all of our membership records for
        !           169:                 * the interface on which the query arrived, except those
        !           170:                 * that are already running and those that belong to the
        !           171:                 * "all-hosts" group.
        !           172:                 */
        !           173:                IN_FIRST_MULTI(step, inm);
        !           174:                while (inm != NULL) {
        !           175:                        if (inm->inm_ifp == ifp && inm->inm_timer == 0 &&
        !           176:                            inm->inm_addr.s_addr != igmp_all_hosts_group) {
        !           177:                                inm->inm_timer =
        !           178:                                    IGMP_RANDOM_DELAY(inm->inm_addr);
        !           179:                                igmp_timers_are_running = 1;
        !           180:                        }
        !           181:                        IN_NEXT_MULTI(step, inm);
        !           182:                }
        !           183: 
        !           184:                break;
        !           185: 
        !           186:        case IGMP_HOST_MEMBERSHIP_REPORT:
        !           187:                ++igmpstat.igps_rcv_reports;
        !           188: 
        !           189:                if (ifp == &loif)
        !           190:                        break;
        !           191: 
        !           192:                if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
        !           193:                    igmp->igmp_group.s_addr != ip->ip_dst.s_addr) {
        !           194:                        ++igmpstat.igps_rcv_badreports;
        !           195:                        m_freem(m);
        !           196:                        return;
        !           197:                }
        !           198: 
        !           199:                /*
        !           200:                 * KLUDGE: if the IP source address of the report has an
        !           201:                 * unspecified (i.e., zero) subnet number, as is allowed for
        !           202:                 * a booting host, replace it with the correct subnet number
        !           203:                 * so that a process-level multicast routing demon can
        !           204:                 * determine which subnet it arrived from.  This is necessary
        !           205:                 * to compensate for the lack of any way for a process to
        !           206:                 * determine the arrival interface of an incoming packet.
        !           207:                 */
        !           208:                if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) {
        !           209:                        IFP_TO_IA(ifp, ia);
        !           210:                        if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
        !           211:                }
        !           212: 
        !           213:                /*
        !           214:                 * If we belong to the group being reported, stop
        !           215:                 * our timer for that group.
        !           216:                 */
        !           217:                IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
        !           218:                if (inm != NULL) {
        !           219:                        inm->inm_timer = 0;
        !           220:                        ++igmpstat.igps_rcv_ourreports;
        !           221:                }
        !           222: 
        !           223:                break;
        !           224:        }
        !           225: 
        !           226:        /*
        !           227:         * Pass all valid IGMP packets up to any process(es) listening
        !           228:         * on a raw IGMP socket.
        !           229:         */
        !           230:        rip_input(m);
        !           231: }
        !           232: 
        !           233: void
        !           234: igmp_joingroup(inm)
        !           235:        struct in_multi *inm;
        !           236: {
        !           237:        register int s = splnet();
        !           238: 
        !           239:        if (inm->inm_addr.s_addr == igmp_all_hosts_group ||
        !           240:            inm->inm_ifp == &loif)
        !           241:                inm->inm_timer = 0;
        !           242:        else {
        !           243:                igmp_sendreport(inm);
        !           244:                inm->inm_timer = IGMP_RANDOM_DELAY(inm->inm_addr);
        !           245:                igmp_timers_are_running = 1;
        !           246:        }
        !           247:        splx(s);
        !           248: }
        !           249: 
        !           250: void
        !           251: igmp_leavegroup(inm)
        !           252:        struct in_multi *inm;
        !           253: {
        !           254:        /*
        !           255:         * No action required on leaving a group.
        !           256:         */
        !           257: }
        !           258: 
        !           259: void
        !           260: igmp_fasttimo()
        !           261: {
        !           262:        register struct in_multi *inm;
        !           263:        register int s;
        !           264:        struct in_multistep step;
        !           265: 
        !           266:        /*
        !           267:         * Quick check to see if any work needs to be done, in order
        !           268:         * to minimize the overhead of fasttimo processing.
        !           269:         */
        !           270:        if (!igmp_timers_are_running)
        !           271:                return;
        !           272: 
        !           273:        s = splnet();
        !           274:        igmp_timers_are_running = 0;
        !           275:        IN_FIRST_MULTI(step, inm);
        !           276:        while (inm != NULL) {
        !           277:                if (inm->inm_timer == 0) {
        !           278:                        /* do nothing */
        !           279:                } else if (--inm->inm_timer == 0) {
        !           280:                        igmp_sendreport(inm);
        !           281:                } else {
        !           282:                        igmp_timers_are_running = 1;
        !           283:                }
        !           284:                IN_NEXT_MULTI(step, inm);
        !           285:        }
        !           286:        splx(s);
        !           287: }
        !           288: 
        !           289: static void
        !           290: igmp_sendreport(inm)
        !           291:        register struct in_multi *inm;
        !           292: {
        !           293:        register struct mbuf *m;
        !           294:        register struct igmp *igmp;
        !           295:        register struct ip *ip;
        !           296:        register struct ip_moptions *imo;
        !           297:        struct ip_moptions simo;
        !           298: 
        !           299:        MGETHDR(m, M_DONTWAIT, MT_HEADER);
        !           300:        if (m == NULL)
        !           301:                return;
        !           302:        /*
        !           303:         * Assume max_linkhdr + sizeof(struct ip) + IGMP_MINLEN
        !           304:         * is smaller than mbuf size returned by MGETHDR.
        !           305:         */
        !           306:        m->m_data += max_linkhdr;
        !           307:        m->m_len = sizeof(struct ip) + IGMP_MINLEN;
        !           308:        m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
        !           309: 
        !           310:        ip = mtod(m, struct ip *);
        !           311:        ip->ip_tos = 0;
        !           312:        ip->ip_len = sizeof(struct ip) + IGMP_MINLEN;
        !           313:        ip->ip_off = 0;
        !           314:        ip->ip_p = IPPROTO_IGMP;
        !           315:        ip->ip_src.s_addr = INADDR_ANY;
        !           316:        ip->ip_dst = inm->inm_addr;
        !           317: 
        !           318:        m->m_data += sizeof(struct ip);
        !           319:        m->m_len -= sizeof(struct ip);
        !           320:        igmp = mtod(m, struct igmp *);
        !           321:        igmp->igmp_type = IGMP_HOST_MEMBERSHIP_REPORT;
        !           322:        igmp->igmp_code = 0;
        !           323:        igmp->igmp_group = inm->inm_addr;
        !           324:        igmp->igmp_cksum = 0;
        !           325:        igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN);
        !           326:        m->m_data -= sizeof(struct ip);
        !           327:        m->m_len += sizeof(struct ip);
        !           328: 
        !           329:        imo = &simo;
        !           330:        bzero((caddr_t)imo, sizeof(*imo));
        !           331:        imo->imo_multicast_ifp = inm->inm_ifp;
        !           332:        imo->imo_multicast_ttl = 1;
        !           333:        /*
        !           334:         * Request loopback of the report if we are acting as a multicast
        !           335:         * router, so that the process-level routing demon can hear it.
        !           336:         */
        !           337: #if MROUTING
        !           338:     {
        !           339:        extern struct socket *ip_mrouter;
        !           340:        imo->imo_multicast_loop = (ip_mrouter != NULL);
        !           341:     }
        !           342: #endif
        !           343:        ip_output(m, NULL, NULL, 0, imo);
        !           344: 
        !           345:        ++igmpstat.igps_snd_reports;
        !           346: }

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