/*      $NetBSD: igmp.c,v 1.70 2020/05/15 06:34:34 maxv Exp $   */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Internet Group Management Protocol (IGMP) routines.
 *
 * Written by Steve Deering, Stanford, May 1988.
 * Modified by Rosen Sharma, Stanford, Aug 1994.
 * Modified by Bill Fenner, Xerox PARC, Feb 1995.
 *
 * MULTICAST Revision: 1.3
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: igmp.c,v 1.70 2020/05/15 06:34:34 maxv Exp $");

#ifdef _KERNEL_OPT
#include "opt_mrouting.h"
#include "opt_net_mpsafe.h"
#endif

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/cprng.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/net_stats.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/igmp.h>
#include <netinet/igmp_var.h>

/*
 * Per-interface router version information.
 */
typedef struct router_info {
        LIST_ENTRY(router_info) rti_link;
        ifnet_t *       rti_ifp;
        int             rti_type;       /* type of router on this interface */
        int             rti_age;        /* time since last v1 query */
} router_info_t;

/*
 * The router-info list and the timer flag are protected by in_multilock.
 *
 * Lock order:
 *
 *      softnet_lock ->
 *              in_multilock
 */
static struct pool      igmp_rti_pool           __cacheline_aligned;
static LIST_HEAD(, router_info) rti_head        __cacheline_aligned;
static int              igmp_timers_on          __cacheline_aligned;
static percpu_t *       igmpstat_percpu         __read_mostly;

#define IGMP_STATINC(x)         _NET_STATINC(igmpstat_percpu, x)

static void             igmp_sendpkt(struct in_multi *, int);
static int              rti_fill(struct in_multi *);
static router_info_t *  rti_find(struct ifnet *);
static void             rti_delete(struct ifnet *);
static void             sysctl_net_inet_igmp_setup(struct sysctllog **);

/*
 * rti_fill: associate router information with the given multicast group;
 * if there is no router information for the interface, then create it.
 */
static int
rti_fill(struct in_multi *inm)
{
        router_info_t *rti;

        KASSERT(in_multi_lock_held());

        LIST_FOREACH(rti, &rti_head, rti_link) {
                if (rti->rti_ifp == inm->inm_ifp) {
                        inm->inm_rti = rti;
                        return rti->rti_type == IGMP_v1_ROUTER ?
                            IGMP_v1_HOST_MEMBERSHIP_REPORT :
                            IGMP_v2_HOST_MEMBERSHIP_REPORT;
                }
        }
        rti = pool_get(&igmp_rti_pool, PR_NOWAIT);
        if (rti == NULL) {
                return 0;
        }
        rti->rti_ifp = inm->inm_ifp;
        rti->rti_type = IGMP_v2_ROUTER;
        LIST_INSERT_HEAD(&rti_head, rti, rti_link);
        inm->inm_rti = rti;
        return IGMP_v2_HOST_MEMBERSHIP_REPORT;
}

/*
 * rti_find: lookup or create router information for the given interface.
 */
static router_info_t *
rti_find(ifnet_t *ifp)
{
        router_info_t *rti;

        KASSERT(in_multi_lock_held());

        LIST_FOREACH(rti, &rti_head, rti_link) {
                if (rti->rti_ifp == ifp)
                        return rti;
        }
        rti = pool_get(&igmp_rti_pool, PR_NOWAIT);
        if (rti == NULL) {
                return NULL;
        }
        rti->rti_ifp = ifp;
        rti->rti_type = IGMP_v2_ROUTER;
        LIST_INSERT_HEAD(&rti_head, rti, rti_link);
        return rti;
}

/*
 * rti_delete: remove and free the router information entry for the
 * given interface.
 */
static void
rti_delete(ifnet_t *ifp)
{
        router_info_t *rti;

        KASSERT(in_multi_lock_held());

        LIST_FOREACH(rti, &rti_head, rti_link) {
                if (rti->rti_ifp == ifp) {
                        LIST_REMOVE(rti, rti_link);
                        pool_put(&igmp_rti_pool, rti);
                        break;
                }
        }
}

void
igmp_init(void)
{
        pool_init(&igmp_rti_pool, sizeof(router_info_t), 0, 0, 0,
            "igmppl", NULL, IPL_SOFTNET);
        igmpstat_percpu = percpu_alloc(sizeof(uint64_t) * IGMP_NSTATS);
        sysctl_net_inet_igmp_setup(NULL);
        LIST_INIT(&rti_head);
}

void
igmp_input(struct mbuf *m, int off, int proto)
{
        ifnet_t *ifp;
        struct ip *ip = mtod(m, struct ip *);
        struct igmp *igmp;
        u_int minlen, timer;
        struct in_multi *inm;
        struct in_ifaddr *ia;
        int ip_len, iphlen;
        struct psref psref;

        iphlen = off;

        IGMP_STATINC(IGMP_STAT_RCV_TOTAL);

        /*
         * Validate lengths
         */
        minlen = iphlen + IGMP_MINLEN;
        ip_len = ntohs(ip->ip_len);
        if (ip_len < minlen) {
                IGMP_STATINC(IGMP_STAT_RCV_TOOSHORT);
                m_freem(m);
                return;
        }
        if (((m->m_flags & M_EXT) && (ip->ip_src.s_addr & IN_CLASSA_NET) == 0)
            || m->m_len < minlen) {
                if ((m = m_pullup(m, minlen)) == NULL) {
                        IGMP_STATINC(IGMP_STAT_RCV_TOOSHORT);
                        return;
                }
                ip = mtod(m, struct ip *);
        }

        /*
         * Validate checksum
         */
        m->m_data += iphlen;
        m->m_len -= iphlen;
        igmp = mtod(m, struct igmp *);
        /* No need to assert alignment here. */
        if (in_cksum(m, ip_len - iphlen)) {
                IGMP_STATINC(IGMP_STAT_RCV_BADSUM);
                m_freem(m);
                return;
        }
        m->m_data -= iphlen;
        m->m_len += iphlen;

        ifp = m_get_rcvif_psref(m, &psref);
        if (__predict_false(ifp == NULL))
                goto drop;

        switch (igmp->igmp_type) {

        case IGMP_HOST_MEMBERSHIP_QUERY:
                IGMP_STATINC(IGMP_STAT_RCV_QUERIES);

                if (ifp->if_flags & IFF_LOOPBACK)
                        break;

                if (igmp->igmp_code == 0) {
                        struct in_multistep step;
                        router_info_t *rti;

                        if (ip->ip_dst.s_addr != INADDR_ALLHOSTS_GROUP) {
                                IGMP_STATINC(IGMP_STAT_RCV_BADQUERIES);
                                goto drop;
                        }

                        in_multi_lock(RW_WRITER);
                        rti = rti_find(ifp);
                        if (rti == NULL) {
                                in_multi_unlock();
                                break;
                        }
                        rti->rti_type = IGMP_v1_ROUTER;
                        rti->rti_age = 0;

                        /*
                         * Start the timers in all of our membership records
                         * for the interface on which the query arrived,
                         * except those that are already running and those
                         * that belong to a "local" group (224.0.0.X).
                         */

                        inm = in_first_multi(&step);
                        while (inm != NULL) {
                                if (inm->inm_ifp == ifp &&
                                    inm->inm_timer == 0 &&
                                    !IN_LOCAL_GROUP(inm->inm_addr.s_addr)) {
                                        inm->inm_state = IGMP_DELAYING_MEMBER;
                                        inm->inm_timer = IGMP_RANDOM_DELAY(
                                            IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ);
                                        igmp_timers_on = true;
                                }
                                inm = in_next_multi(&step);
                        }
                        in_multi_unlock();
                } else {
                        struct in_multistep step;

                        if (!IN_MULTICAST(ip->ip_dst.s_addr)) {
                                IGMP_STATINC(IGMP_STAT_RCV_BADQUERIES);
                                goto drop;
                        }

                        timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
                        if (timer == 0)
                                timer = 1;

                        /*
                         * Start the timers in all of our membership records
                         * for the interface on which the query arrived,
                         * except those that are already running and those
                         * that belong to a "local" group (224.0.0.X).  For
                         * timers already running, check if they need to be
                         * reset.
                         */
                        in_multi_lock(RW_WRITER);
                        inm = in_first_multi(&step);
                        while (inm != NULL) {
                                if (inm->inm_ifp == ifp &&
                                    !IN_LOCAL_GROUP(inm->inm_addr.s_addr) &&
                                    (ip->ip_dst.s_addr == INADDR_ALLHOSTS_GROUP ||
                                     in_hosteq(ip->ip_dst, inm->inm_addr))) {
                                        switch (inm->inm_state) {
                                        case IGMP_DELAYING_MEMBER:
                                                if (inm->inm_timer <= timer)
                                                        break;
                                                /* FALLTHROUGH */
                                        case IGMP_IDLE_MEMBER:
                                        case IGMP_LAZY_MEMBER:
                                        case IGMP_AWAKENING_MEMBER:
                                                inm->inm_state =
                                                    IGMP_DELAYING_MEMBER;
                                                inm->inm_timer =
                                                    IGMP_RANDOM_DELAY(timer);
                                                igmp_timers_on = true;
                                                break;
                                        case IGMP_SLEEPING_MEMBER:
                                                inm->inm_state =
                                                    IGMP_AWAKENING_MEMBER;
                                                break;
                                        }
                                }
                                inm = in_next_multi(&step);
                        }
                        in_multi_unlock();
                }

                break;

        case IGMP_v1_HOST_MEMBERSHIP_REPORT:
                IGMP_STATINC(IGMP_STAT_RCV_REPORTS);

                if (ifp->if_flags & IFF_LOOPBACK)
                        break;

                if (!IN_MULTICAST(igmp->igmp_group.s_addr) ||
                    !in_hosteq(igmp->igmp_group, ip->ip_dst)) {
                        IGMP_STATINC(IGMP_STAT_RCV_BADREPORTS);
                        goto drop;
                }

                /*
                 * KLUDGE: if the IP source address of the report has an
                 * unspecified (i.e., zero) subnet number, as is allowed for
                 * a booting host, replace it with the correct subnet number
                 * so that a process-level multicast routing daemon can
                 * determine which subnet it arrived from.  This is necessary
                 * to compensate for the lack of any way for a process to
                 * determine the arrival interface of an incoming packet.
                 */
                if ((ip->ip_src.s_addr & IN_CLASSA_NET) == 0) {
                        int s = pserialize_read_enter();
                        ia = in_get_ia_from_ifp(ifp); /* XXX */
                        if (ia)
                                ip->ip_src.s_addr = ia->ia_subnet;
                        pserialize_read_exit(s);
                }

                /*
                 * If we belong to the group being reported, stop
                 * our timer for that group.
                 */
                in_multi_lock(RW_WRITER);
                inm = in_lookup_multi(igmp->igmp_group, ifp);
                if (inm != NULL) {
                        inm->inm_timer = 0;
                        IGMP_STATINC(IGMP_STAT_RCV_OURREPORTS);

                        switch (inm->inm_state) {
                        case IGMP_IDLE_MEMBER:
                        case IGMP_LAZY_MEMBER:
                        case IGMP_AWAKENING_MEMBER:
                        case IGMP_SLEEPING_MEMBER:
                                inm->inm_state = IGMP_SLEEPING_MEMBER;
                                break;
                        case IGMP_DELAYING_MEMBER:
                                if (inm->inm_rti->rti_type == IGMP_v1_ROUTER)
                                        inm->inm_state = IGMP_LAZY_MEMBER;
                                else
                                        inm->inm_state = IGMP_SLEEPING_MEMBER;
                                break;
                        }
                }
                in_multi_unlock();
                break;

        case IGMP_v2_HOST_MEMBERSHIP_REPORT: {
                int s = pserialize_read_enter();
#ifdef MROUTING
                /*
                 * Make sure we don't hear our own membership report.  Fast
                 * leave requires knowing that we are the only member of a
                 * group.
                 */
                ia = in_get_ia_from_ifp(ifp);   /* XXX */
                if (ia && in_hosteq(ip->ip_src, ia->ia_addr.sin_addr)) {
                        pserialize_read_exit(s);
                        break;
                }
#endif

                IGMP_STATINC(IGMP_STAT_RCV_REPORTS);

                if (ifp->if_flags & IFF_LOOPBACK) {
                        pserialize_read_exit(s);
                        break;
                }

                if (!IN_MULTICAST(igmp->igmp_group.s_addr) ||
                    !in_hosteq(igmp->igmp_group, ip->ip_dst)) {
                        IGMP_STATINC(IGMP_STAT_RCV_BADREPORTS);
                        pserialize_read_exit(s);
                        goto drop;
                }

                /*
                 * KLUDGE: if the IP source address of the report has an
                 * unspecified (i.e., zero) subnet number, as is allowed for
                 * a booting host, replace it with the correct subnet number
                 * so that a process-level multicast routing daemon can
                 * determine which subnet it arrived from.  This is necessary
                 * to compensate for the lack of any way for a process to
                 * determine the arrival interface of an incoming packet.
                 */
                if ((ip->ip_src.s_addr & IN_CLASSA_NET) == 0) {
#ifndef MROUTING
                        ia = in_get_ia_from_ifp(ifp); /* XXX */
#endif
                        if (ia)
                                ip->ip_src.s_addr = ia->ia_subnet;
                }
                pserialize_read_exit(s);

                /*
                 * If we belong to the group being reported, stop
                 * our timer for that group.
                 */
                in_multi_lock(RW_WRITER);
                inm = in_lookup_multi(igmp->igmp_group, ifp);
                if (inm != NULL) {
                        inm->inm_timer = 0;
                        IGMP_STATINC(IGMP_STAT_RCV_OURREPORTS);

                        switch (inm->inm_state) {
                        case IGMP_DELAYING_MEMBER:
                        case IGMP_IDLE_MEMBER:
                        case IGMP_AWAKENING_MEMBER:
                                inm->inm_state = IGMP_LAZY_MEMBER;
                                break;
                        case IGMP_LAZY_MEMBER:
                        case IGMP_SLEEPING_MEMBER:
                                break;
                        }
                }
                in_multi_unlock();
                break;
            }
        }
        m_put_rcvif_psref(ifp, &psref);

        /*
         * Pass all valid IGMP packets up to any process(es) listening
         * on a raw IGMP socket.
         */
        /*
         * Currently, igmp_input() is always called holding softnet_lock
         * by ipintr()(!NET_MPSAFE) or PR_INPUT_WRAP()(NET_MPSAFE).
         */
        KASSERT(mutex_owned(softnet_lock));
        rip_input(m, iphlen, proto);
        return;

drop:
        m_put_rcvif_psref(ifp, &psref);
        m_freem(m);
        return;
}

int
igmp_joingroup(struct in_multi *inm)
{
        KASSERT(in_multi_lock_held());
        inm->inm_state = IGMP_IDLE_MEMBER;

        if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) &&
            (inm->inm_ifp->if_flags & IFF_LOOPBACK) == 0) {
                int report_type;

                report_type = rti_fill(inm);
                if (report_type == 0) {
                        return ENOMEM;
                }
                igmp_sendpkt(inm, report_type);
                inm->inm_state = IGMP_DELAYING_MEMBER;
                inm->inm_timer = IGMP_RANDOM_DELAY(
                    IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ);
                igmp_timers_on = true;
        } else
                inm->inm_timer = 0;

        return 0;
}

void
igmp_leavegroup(struct in_multi *inm)
{
        KASSERT(in_multi_lock_held());

        switch (inm->inm_state) {
        case IGMP_DELAYING_MEMBER:
        case IGMP_IDLE_MEMBER:
                if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) &&
                    (inm->inm_ifp->if_flags & IFF_LOOPBACK) == 0)
                        if (inm->inm_rti->rti_type != IGMP_v1_ROUTER)
                                igmp_sendpkt(inm, IGMP_HOST_LEAVE_MESSAGE);
                break;
        case IGMP_LAZY_MEMBER:
        case IGMP_AWAKENING_MEMBER:
        case IGMP_SLEEPING_MEMBER:
                break;
        }
}

void
igmp_fasttimo(void)
{
        struct in_multi *inm;
        struct in_multistep step;

        /*
         * Quick check to see if any work needs to be done, in order
         * to minimize the overhead of fasttimo processing.
         */
        if (!igmp_timers_on) {
                return;
        }

        /* XXX: Needed for ip_output(). */
        SOFTNET_LOCK_UNLESS_NET_MPSAFE();

        in_multi_lock(RW_WRITER);
        igmp_timers_on = false;
        inm = in_first_multi(&step);
        while (inm != NULL) {
                if (inm->inm_timer == 0) {
                        /* do nothing */
                } else if (--inm->inm_timer == 0) {
                        if (inm->inm_state == IGMP_DELAYING_MEMBER) {
                                if (inm->inm_rti->rti_type == IGMP_v1_ROUTER)
                                        igmp_sendpkt(inm,
                                            IGMP_v1_HOST_MEMBERSHIP_REPORT);
                                else
                                        igmp_sendpkt(inm,
                                            IGMP_v2_HOST_MEMBERSHIP_REPORT);
                                inm->inm_state = IGMP_IDLE_MEMBER;
                        }
                } else {
                        igmp_timers_on = true;
                }
                inm = in_next_multi(&step);
        }
        in_multi_unlock();
        SOFTNET_UNLOCK_UNLESS_NET_MPSAFE();
}

void
igmp_slowtimo(void)
{
        router_info_t *rti;

        in_multi_lock(RW_WRITER);
        LIST_FOREACH(rti, &rti_head, rti_link) {
                if (rti->rti_type == IGMP_v1_ROUTER &&
                    ++rti->rti_age >= IGMP_AGE_THRESHOLD) {
                        rti->rti_type = IGMP_v2_ROUTER;
                }
        }
        in_multi_unlock();
}

/*
 * igmp_sendpkt: construct an IGMP packet, given the multicast structure
 * and the type, and send the datagram.
 */
static void
igmp_sendpkt(struct in_multi *inm, int type)
{
        struct mbuf *m;
        struct igmp *igmp;
        struct ip *ip;
        struct ip_moptions imo;

        KASSERT(in_multi_lock_held());

        MGETHDR(m, M_DONTWAIT, MT_HEADER);
        if (m == NULL)
                return;
        KASSERT(max_linkhdr + sizeof(struct ip) + IGMP_MINLEN <= MHLEN);

        m->m_data += max_linkhdr;
        m->m_len = sizeof(struct ip) + IGMP_MINLEN;
        m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;

        ip = mtod(m, struct ip *);
        ip->ip_tos = 0;
        ip->ip_len = htons(sizeof(struct ip) + IGMP_MINLEN);
        ip->ip_off = htons(0);
        ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
        ip->ip_p = IPPROTO_IGMP;
        ip->ip_src = zeroin_addr;
        ip->ip_dst = inm->inm_addr;

        m->m_data += sizeof(struct ip);
        m->m_len -= sizeof(struct ip);
        igmp = mtod(m, struct igmp *);
        igmp->igmp_type = type;
        igmp->igmp_code = 0;
        igmp->igmp_group = inm->inm_addr;
        igmp->igmp_cksum = 0;
        igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN);
        m->m_data -= sizeof(struct ip);
        m->m_len += sizeof(struct ip);

        imo.imo_multicast_if_index = if_get_index(inm->inm_ifp);
        imo.imo_multicast_ttl = 1;

        /*
         * Request loopback of the report if we are acting as a multicast
         * router, so that the process-level routing demon can hear it.
         */
#ifdef MROUTING
        extern struct socket *ip_mrouter;
        imo.imo_multicast_loop = (ip_mrouter != NULL);
#else
        imo.imo_multicast_loop = 0;
#endif

        /*
         * Note: IP_IGMP_MCAST indicates that in_multilock is held.
         * The caller must still acquire softnet_lock for ip_output().
         */
#ifndef NET_MPSAFE
        KASSERT(mutex_owned(softnet_lock));
#endif
        ip_output(m, NULL, NULL, IP_IGMP_MCAST, &imo, NULL);
        IGMP_STATINC(IGMP_STAT_SND_REPORTS);
}

void
igmp_purgeif(ifnet_t *ifp)
{
        in_multi_lock(RW_WRITER);
        rti_delete(ifp);
        in_multi_unlock();
}

static int
sysctl_net_inet_igmp_stats(SYSCTLFN_ARGS)
{
        return NETSTAT_SYSCTL(igmpstat_percpu, IGMP_NSTATS);
}

static void
sysctl_net_inet_igmp_setup(struct sysctllog **clog)
{
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "inet", NULL,
                        NULL, 0, NULL, 0,
                        CTL_NET, PF_INET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "igmp",
                        SYSCTL_DESCR("Internet Group Management Protocol"),
                        NULL, 0, NULL, 0,
                        CTL_NET, PF_INET, IPPROTO_IGMP, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_STRUCT, "stats",
                        SYSCTL_DESCR("IGMP statistics"),
                        sysctl_net_inet_igmp_stats, 0, NULL, 0,
                        CTL_NET, PF_INET, IPPROTO_IGMP, CTL_CREATE, CTL_EOL);
}