/*
 * Copyright (c) 1988 Stephen Deering.
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Stephen Deering of Stanford University.
 *
 * 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 University 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 REGENTS 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 REGENTS 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.
 *
 *      @(#)igmp.c      8.1 (Berkeley) 7/19/93
 * $FreeBSD: src/sys/netinet/igmp.c,v 1.29.2.2 2003/01/23 21:06:44 sam Exp $
 */

/*
 * 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.
 * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
 *
 * MULTICAST Revision: 3.5.1.4
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/in_cksum.h>
#include <sys/thread2.h>

#include <machine/stdarg.h>

#include <net/if.h>
#include <net/route.h>
#include <net/netmsg2.h>
#include <net/netisr2.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>

#define IGMP_FASTTIMO           (hz / PR_FASTHZ)
#define IGMP_SLOWTIMO           (hz / PR_SLOWHZ)

static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");

static struct router_info *
                find_rti (struct ifnet *ifp);

static struct igmpstat igmpstat;

SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW,
        &igmpstat, igmpstat, "IGMP statistics");

static int igmp_timers_are_running;
static u_long igmp_all_hosts_group;
static u_long igmp_all_rtrs_group;
static struct mbuf *router_alert;
static struct router_info *Head;

static void igmp_sendpkt (struct in_multi *, int, unsigned long);
static void igmp_fasttimo_dispatch(netmsg_t);
static void igmp_fasttimo(void *);
static void igmp_slowtimo_dispatch(netmsg_t);
static void igmp_slowtimo(void *);

static struct netmsg_base igmp_slowtimo_netmsg;
static struct callout igmp_slowtimo_ch;
static struct netmsg_base igmp_fasttimo_netmsg;
static struct callout igmp_fasttimo_ch;

void
igmp_init(void)
{
        struct ipoption *ra;

        /*
         * To avoid byte-swapping the same value over and over again.
         */
        igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
        igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);

        igmp_timers_are_running = 0;

        /*
         * Construct a Router Alert option to use in outgoing packets
         */
        MGET(router_alert, M_NOWAIT, MT_DATA);
        ra = mtod(router_alert, struct ipoption *);
        ra->ipopt_dst.s_addr = 0;
        ra->ipopt_list[0] = IPOPT_RA;   /* Router Alert Option */
        ra->ipopt_list[1] = 0x04;       /* 4 bytes long */
        ra->ipopt_list[2] = 0x00;
        ra->ipopt_list[3] = 0x00;
        router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];

        Head = NULL;

        callout_init_mp(&igmp_slowtimo_ch);
        netmsg_init(&igmp_slowtimo_netmsg, NULL, &netisr_adone_rport,
            MSGF_PRIORITY, igmp_slowtimo_dispatch);

        callout_init_mp(&igmp_fasttimo_ch);
        netmsg_init(&igmp_fasttimo_netmsg, NULL, &netisr_adone_rport,
            MSGF_PRIORITY, igmp_fasttimo_dispatch);

        callout_reset_bycpu(&igmp_slowtimo_ch, IGMP_SLOWTIMO,
            igmp_slowtimo, NULL, 0);
        callout_reset_bycpu(&igmp_fasttimo_ch, IGMP_FASTTIMO,
            igmp_fasttimo, NULL, 0);
}

static struct router_info *
find_rti(struct ifnet *ifp)
{
        struct router_info *rti = Head;

#ifdef IGMP_DEBUG
        kprintf("[igmp.c, _find_rti] --> entering \n");
#endif
        while (rti) {
                if (rti->rti_ifp == ifp) {
#ifdef IGMP_DEBUG
                        kprintf("[igmp.c, _find_rti] --> found old entry \n");
#endif
                        return rti;
                }
                rti = rti->rti_next;
        }
        rti = kmalloc(sizeof *rti, M_IGMP, M_INTWAIT);
        rti->rti_ifp = ifp;
        rti->rti_type = IGMP_V2_ROUTER;
        rti->rti_time = 0;
        rti->rti_next = Head;
        Head = rti;
#ifdef IGMP_DEBUG
        kprintf("[igmp.c, _find_rti] --> created an entry \n");
#endif
        return rti;
}

int
igmp_input(struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m = *mp;
        int iphlen;
        struct igmp *igmp;
        struct ip *ip;
        int igmplen;
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        int minlen;
        struct in_multi *inm;
        struct in_ifaddr *ia;
        struct in_multistep step;
        struct router_info *rti;
        int timer; /** timer value in the igmp query header **/

        iphlen = *offp;
        *mp = NULL;

        ++igmpstat.igps_rcv_total;

        ip = mtod(m, struct ip *);
        igmplen = ntohs(ip->ip_len) - iphlen;

        /*
         * Validate lengths
         */
        if (igmplen < IGMP_MINLEN) {
                ++igmpstat.igps_rcv_tooshort;
                m_freem(m);
                return(IPPROTO_DONE);
        }
        minlen = iphlen + IGMP_MINLEN;
        if ((m->m_flags & M_EXT || m->m_len < minlen) &&
            (m = m_pullup(m, minlen)) == NULL) {
                ++igmpstat.igps_rcv_tooshort;
                return(IPPROTO_DONE);
        }

        /*
         * Validate checksum
         */
        m->m_data += iphlen;
        m->m_len -= iphlen;
        igmp = mtod(m, struct igmp *);
        if (in_cksum(m, igmplen)) {
                ++igmpstat.igps_rcv_badsum;
                m_freem(m);
                return(IPPROTO_DONE);
        }
        m->m_data -= iphlen;
        m->m_len += iphlen;

        ip = mtod(m, struct ip *);
        timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
        if (timer == 0)
                timer = 1;
        rti = find_rti(ifp);

        /*
         * In the IGMPv2 specification, there are 3 states and a flag.
         *
         * In Non-Member state, we simply don't have a membership record.
         * In Delaying Member state, our timer is running (inm->inm_timer)
         * In Idle Member state, our timer is not running (inm->inm_timer==0)
         *
         * The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
         * we have heard a report from another member, or IGMP_IREPORTEDLAST
         * if I sent the last report.
         */
        switch (igmp->igmp_type) {

        case IGMP_MEMBERSHIP_QUERY:
                ++igmpstat.igps_rcv_queries;

                if (ifp->if_flags & IFF_LOOPBACK)
                        break;

                if (igmp->igmp_code == 0) {
                        /*
                         * Old router.  Remember that the querier on this
                         * interface is old, and set the timer to the
                         * value in RFC 1112.
                         */

                        rti->rti_type = IGMP_V1_ROUTER;
                        rti->rti_time = 0;

                        timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;

                        if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
                            igmp->igmp_group.s_addr != 0) {
                                ++igmpstat.igps_rcv_badqueries;
                                m_freem(m);
                                return(IPPROTO_DONE);
                        }
                } else {
                        /*
                         * New router.  Simply do the new validity check.
                         */
                        
                        if (igmp->igmp_group.s_addr != 0 &&
                            !IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
                                ++igmpstat.igps_rcv_badqueries;
                                m_freem(m);
                                return(IPPROTO_DONE);
                        }
                }

                /*
                 * - Start the timers in all of our membership records
                 *   that the query applies to for the interface on
                 *   which the query arrived excl. those that belong
                 *   to the "all-hosts" group (224.0.0.1).
                 * - Restart any timer that is already running but has
                 *   a value longer than the requested timeout.
                 * - Use the value specified in the query message as
                 *   the maximum timeout.
                 */
                IN_FIRST_MULTI(step, inm);
                while (inm != NULL) {
                        if (inm->inm_ifp == ifp &&
                            inm->inm_addr.s_addr != igmp_all_hosts_group &&
                            (igmp->igmp_group.s_addr == 0 ||
                             igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
                                if (inm->inm_timer == 0 ||
                                    inm->inm_timer > timer) {
                                        inm->inm_timer =
                                                IGMP_RANDOM_DELAY(timer);
                                        igmp_timers_are_running = 1;
                                }
                        }
                        IN_NEXT_MULTI(step, inm);
                }

                break;

        case IGMP_V1_MEMBERSHIP_REPORT:
        case IGMP_V2_MEMBERSHIP_REPORT:
                /*
                 * For fast leave to work, we have to know that we are the
                 * last person to send a report for this group.  Reports
                 * can potentially get looped back if we are a multicast
                 * router, so discard reports sourced by me.
                 */
                ia = IFP_TO_IA(ifp);
                if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
                        break;

                ++igmpstat.igps_rcv_reports;

                if (ifp->if_flags & IFF_LOOPBACK)
                        break;

                if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
                        ++igmpstat.igps_rcv_badreports;
                        m_freem(m);
                        return(IPPROTO_DONE);
                }

                /*
                 * 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 demon 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 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
                        if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);

                /*
                 * If we belong to the group being reported, stop
                 * our timer for that group.
                 */
                inm = IN_LOOKUP_MULTI(&igmp->igmp_group, ifp);

                if (inm != NULL) {
                        inm->inm_timer = 0;
                        ++igmpstat.igps_rcv_ourreports;

                        inm->inm_state = IGMP_OTHERMEMBER;
                }

                break;
        }

        /*
         * Pass all valid IGMP packets up to any process(es) listening
         * on a raw IGMP socket.
         */
        *mp = m;
        rip_input(mp, offp, proto);
        return(IPPROTO_DONE);
}

void
igmp_joingroup(struct in_multi *inm)
{
        crit_enter();
        if (inm->inm_addr.s_addr == igmp_all_hosts_group
            || inm->inm_ifp->if_flags & IFF_LOOPBACK) {
                inm->inm_timer = 0;
                inm->inm_state = IGMP_OTHERMEMBER;
        } else {
                inm->inm_rti = find_rti(inm->inm_ifp);
                igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
                inm->inm_timer = IGMP_RANDOM_DELAY(
                                        IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
                inm->inm_state = IGMP_IREPORTEDLAST;
                igmp_timers_are_running = 1;
        }
        crit_exit();
}

void
igmp_leavegroup(struct in_multi *inm)
{
        if (inm->inm_state == IGMP_IREPORTEDLAST &&
            inm->inm_addr.s_addr != igmp_all_hosts_group &&
            !(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
            inm->inm_rti->rti_type != IGMP_V1_ROUTER)
                igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
}

static void
igmp_fasttimo(void *dummy __unused)
{
        struct netmsg_base *msg = &igmp_fasttimo_netmsg;

        KKASSERT(mycpuid == 0);

        crit_enter();
        if (msg->lmsg.ms_flags & MSGF_DONE)
                netisr_sendmsg_oncpu(msg);
        crit_exit();
}

static void
igmp_fasttimo_dispatch(netmsg_t nmsg)
{
        struct in_multi *inm;
        struct in_multistep step;

        ASSERT_NETISR0;

        crit_enter();
        netisr_replymsg(&nmsg->base, 0);        /* reply ASAP */
        crit_exit();

        /*
         * Quick check to see if any work needs to be done, in order
         * to minimize the overhead of fasttimo processing.
         */

        if (!igmp_timers_are_running)
                goto done;

        igmp_timers_are_running = 0;
        IN_FIRST_MULTI(step, inm);
        while (inm != NULL) {
                if (inm->inm_timer == 0) {
                        /* do nothing */
                } else if (--inm->inm_timer == 0) {
                        igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
                        inm->inm_state = IGMP_IREPORTEDLAST;
                } else {
                        igmp_timers_are_running = 1;
                }
                IN_NEXT_MULTI(step, inm);
        }
done:
        callout_reset(&igmp_fasttimo_ch, IGMP_FASTTIMO, igmp_fasttimo, NULL);
}

static void
igmp_slowtimo(void *dummy __unused)
{
        struct netmsg_base *msg = &igmp_slowtimo_netmsg;

        KKASSERT(mycpuid == 0);

        crit_enter();
        if (msg->lmsg.ms_flags & MSGF_DONE)
                netisr_sendmsg_oncpu(msg);
        crit_exit();
}

static void
igmp_slowtimo_dispatch(netmsg_t nmsg)
{
        struct router_info *rti = Head;

        ASSERT_NETISR0;

        crit_enter();
        netisr_replymsg(&nmsg->base, 0);        /* reply ASAP */
        crit_exit();

#ifdef IGMP_DEBUG
        kprintf("[igmp.c,_slowtimo] -- > entering \n");
#endif
        while (rti) {
            if (rti->rti_type == IGMP_V1_ROUTER) {
                rti->rti_time++;
                if (rti->rti_time >= IGMP_AGE_THRESHOLD) {
                        rti->rti_type = IGMP_V2_ROUTER;
                }
            }
            rti = rti->rti_next;
        }
#ifdef IGMP_DEBUG       
        kprintf("[igmp.c,_slowtimo] -- > exiting \n");
#endif
        callout_reset(&igmp_slowtimo_ch, IGMP_SLOWTIMO, igmp_slowtimo, NULL);
}

static struct route igmprt;

static void
igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr)
{
        struct mbuf *m;
        struct igmp *igmp;
        struct ip *ip;
        struct ip_moptions imo;

        MGETHDR(m, M_NOWAIT, MT_HEADER);
        if (m == NULL)
                return;

        m->m_pkthdr.rcvif = loif;
        m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
        MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
        m->m_data += sizeof(struct ip);
        m->m_len = IGMP_MINLEN;
        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);
        ip = mtod(m, struct ip *);
        ip->ip_tos = 0;
        ip->ip_len = htons(sizeof(struct ip) + IGMP_MINLEN);
        ip->ip_off = 0;
        ip->ip_p = IPPROTO_IGMP;
        ip->ip_src.s_addr = INADDR_ANY;
        ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr;

        imo.imo_multicast_ifp = inm->inm_ifp;
        imo.imo_multicast_ttl = 1;
        imo.imo_multicast_vif = -1;
        /*
         * Request loopback of the report if we are acting as a multicast
         * router, so that the process-level routing demon can hear it.
         */
        imo.imo_multicast_loop = (ip_mrouter != NULL);

        /*
         * XXX
         * Do we have to worry about reentrancy here?  Don't think so.
         */
        ip_output(m, router_alert, &igmprt, 0, &imo, NULL);

        ++igmpstat.igps_snd_reports;
}