igmp.c

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/*
 *      Linux NET3:     Internet Group Management Protocol  [IGMP]
 *
 *      This code implements the IGMP protocol as defined in RFC1112. There has
 *      been a further revision of this protocol since which is now supported.
 *
 *      If you have trouble with this module be careful what gcc you have used,
 *      the older version didn't come out right using gcc 2.5.8, the newer one
 *      seems to fall out with gcc 2.6.2.
 *
 *      Version: $Id: igmp.c,v 1.46 2001/07/27 09:27:29 davem Exp $
 *
 *      Authors:
 *              Alan Cox <Alan.Cox@linux.org>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *      Fixes:
 *
 *              Alan Cox        :       Added lots of __inline__ to optimise
 *                                      the memory usage of all the tiny little
 *                                      functions.
 *              Alan Cox        :       Dumped the header building experiment.
 *              Alan Cox        :       Minor tweaks ready for multicast routing
 *                                      and extended IGMP protocol.
 *              Alan Cox        :       Removed a load of inline directives. Gcc 2.5.8
 *                                      writes utterly bogus code otherwise (sigh)
 *                                      fixed IGMP loopback to behave in the manner
 *                                      desired by mrouted, fixed the fact it has been
 *                                      broken since 1.3.6 and cleaned up a few minor
 *                                      points.
 *
 *              Chih-Jen Chang  :       Tried to revise IGMP to Version 2
 *              Tsu-Sheng Tsao          E-mail: chihjenc@scf.usc.edu and tsusheng@scf.usc.edu
 *                                      The enhancements are mainly based on Steve Deering's 
 *                                      ipmulti-3.5 source code.
 *              Chih-Jen Chang  :       Added the igmp_get_mrouter_info and
 *              Tsu-Sheng Tsao          igmp_set_mrouter_info to keep track of
 *                                      the mrouted version on that device.
 *              Chih-Jen Chang  :       Added the max_resp_time parameter to
 *              Tsu-Sheng Tsao          igmp_heard_query(). Using this parameter
 *                                      to identify the multicast router version
 *                                      and do what the IGMP version 2 specified.
 *              Chih-Jen Chang  :       Added a timer to revert to IGMP V2 router
 *              Tsu-Sheng Tsao          if the specified time expired.
 *              Alan Cox        :       Stop IGMP from 0.0.0.0 being accepted.
 *              Alan Cox        :       Use GFP_ATOMIC in the right places.
 *              Christian Daudt :       igmp timer wasn't set for local group
 *                                      memberships but was being deleted, 
 *                                      which caused a "del_timer() called 
 *                                      from %p with timer not initialized\n"
 *                                      message (960131).
 *              Christian Daudt :       removed del_timer from 
 *                                      igmp_timer_expire function (960205).
 *             Christian Daudt :       igmp_heard_report now only calls
 *                                     igmp_timer_expire if tm->running is
 *                                     true (960216).
 *              Malcolm Beattie :       ttl comparison wrong in igmp_rcv made
 *                                      igmp_heard_query never trigger. Expiry
 *                                      miscalculation fixed in igmp_heard_query
 *                                      and random() made to return unsigned to
 *                                      prevent negative expiry times.
 *              Alexey Kuznetsov:       Wrong group leaving behaviour, backport
 *                                      fix from pending 2.1.x patches.
 *              Alan Cox:               Forget to enable FDDI support earlier.
 *              Alexey Kuznetsov:       Fixed leaving groups on device down.
 *              Alexey Kuznetsov:       Accordance to igmp-v2-06 draft.
 *              David L Stevens:        IGMPv3 support, with help from
 *                                      Vinay Kulkarni
 */


#include <linux/config.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4.h>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif


#define IP_MAX_MEMBERSHIPS 20

#ifdef CONFIG_IP_MULTICAST
/* Parameter names and values are taken from igmp-v2-06 draft */

#define IGMP_V1_Router_Present_Timeout          (400*HZ)
#define IGMP_V2_Router_Present_Timeout          (400*HZ)
#define IGMP_Unsolicited_Report_Interval        (10*HZ)
#define IGMP_Query_Response_Interval            (10*HZ)
#define IGMP_Unsolicited_Report_Count           2


#define IGMP_Initial_Report_Delay               (1)

/* IGMP_Initial_Report_Delay is not from IGMP specs!
 * IGMP specs require to report membership immediately after
 * joining a group, but we delay the first report by a
 * small interval. It seems more natural and still does not
 * contradict to specs provided this delay is small enough.
 */

#define IGMP_V1_SEEN(in_dev) ((in_dev)->mr_v1_seen && \
                time_before(jiffies, (in_dev)->mr_v1_seen))
#define IGMP_V2_SEEN(in_dev) ((in_dev)->mr_v2_seen && \
                time_before(jiffies, (in_dev)->mr_v2_seen))

static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im);
static void igmpv3_del_delrec(struct in_device *in_dev, __u32 multiaddr);
static void igmpv3_clear_delrec(struct in_device *in_dev);
static int sf_setstate(struct ip_mc_list *pmc);
static void sf_markstate(struct ip_mc_list *pmc);
#endif
static void ip_mc_clear_src(struct ip_mc_list *pmc);
int ip_mc_add_src(struct in_device *in_dev, __u32 *pmca, int sfmode,
        int sfcount, __u32 *psfsrc, int delta);

static void ip_ma_put(struct ip_mc_list *im)
{
        if (atomic_dec_and_test(&im->refcnt)) {
                in_dev_put(im->interface);
                kfree(im);
        }
}

#ifdef CONFIG_IP_MULTICAST

/*
 *      Timer management
 */

static __inline__ void igmp_stop_timer(struct ip_mc_list *im)
{
        spin_lock_bh(&im->lock);
        if (del_timer(&im->timer))
                atomic_dec(&im->refcnt);
        im->tm_running=0;
        im->reporter = 0;
        im->unsolicit_count = 0;
        spin_unlock_bh(&im->lock);
}

/* It must be called with locked im->lock */
static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
{
        int tv=net_random() % max_delay;

        im->tm_running=1;
        if (!mod_timer(&im->timer, jiffies+tv+2))
                atomic_inc(&im->refcnt);
}

static void igmp_gq_start_timer(struct in_device *in_dev)
{
        int tv = net_random() % in_dev->mr_maxdelay;

        in_dev->mr_gq_running = 1;
        if (!mod_timer(&in_dev->mr_gq_timer, jiffies+tv+2))
                in_dev_hold(in_dev);
}

static void igmp_ifc_start_timer(struct in_device *in_dev, int delay)
{
        int tv = net_random() % delay;

        if (!mod_timer(&in_dev->mr_ifc_timer, jiffies+tv+2))
                in_dev_hold(in_dev);
}

static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
{
        spin_lock_bh(&im->lock);
        im->unsolicit_count = 0;
        if (del_timer(&im->timer)) {
                if ((long)(im->timer.expires-jiffies) < max_delay) {
                        add_timer(&im->timer);
                        im->tm_running=1;
                        spin_unlock_bh(&im->lock);
                        return;
                }
                atomic_dec(&im->refcnt);
        }
        igmp_start_timer(im, max_delay);
        spin_unlock_bh(&im->lock);
}


/*
 *      Send an IGMP report.
 */

#define IGMP_SIZE (sizeof(struct igmphdr)+sizeof(struct iphdr)+4)

/* Don't just hand NF_HOOK skb->dst->output, in case netfilter hook
   changes route */
static inline int
output_maybe_reroute(struct sk_buff *skb)
{
        return skb->dst->output(skb);
}


static int is_in(struct ip_mc_list *pmc, struct ip_sf_list *psf, int type,
        int gdeleted, int sdeleted)
{
        switch (type) {
        case IGMPV3_MODE_IS_INCLUDE:
        case IGMPV3_MODE_IS_EXCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                return !(pmc->gsquery && !psf->sf_gsresp);
        case IGMPV3_CHANGE_TO_INCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                return psf->sf_count[MCAST_INCLUDE] != 0;
        case IGMPV3_CHANGE_TO_EXCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                if (pmc->sfcount[MCAST_EXCLUDE] == 0 ||
                    psf->sf_count[MCAST_INCLUDE])
                        return 0;
                return pmc->sfcount[MCAST_EXCLUDE] ==
                        psf->sf_count[MCAST_EXCLUDE];
        case IGMPV3_ALLOW_NEW_SOURCES:
                if (gdeleted || !psf->sf_crcount)
                        return 0;
                return (pmc->sfmode == MCAST_INCLUDE) ^ sdeleted;
        case IGMPV3_BLOCK_OLD_SOURCES:
                if (pmc->sfmode == MCAST_INCLUDE)
                        return gdeleted || (psf->sf_crcount && sdeleted);
                return psf->sf_crcount && !gdeleted && !sdeleted;
        }
        return 0;
}

static int
igmp_scount(struct ip_mc_list *pmc, int type, int gdeleted, int sdeleted)
{
        struct ip_sf_list *psf;
        int scount = 0;

        for (psf=pmc->sources; psf; psf=psf->sf_next) {
                if (!is_in(pmc, psf, type, gdeleted, sdeleted))
                        continue;
                scount++;
        }
        return scount;
}

static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
{
        struct sk_buff *skb;
        struct rtable *rt;
        struct iphdr *pip;
        struct igmpv3_report *pig;
        u32     dst;

        dst = IGMPV3_ALL_MCR;
        if (ip_route_output(&rt, dst, 0, 0, dev->ifindex))
                return 0;
        if (rt->rt_src == 0) {
                ip_rt_put(rt);
                return 0;
        }
        skb = alloc_skb(size + dev->hard_header_len + 15, GFP_ATOMIC);
        if (skb == NULL) {
                ip_rt_put(rt);
                return 0;
        }

        skb->dst = &rt->u.dst;
        skb->dev = dev;

        skb_reserve(skb, (dev->hard_header_len+15)&~15);

        skb->nh.iph = pip =(struct iphdr *)skb_put(skb, sizeof(struct iphdr)+4);

        pip->version  = 4;
        pip->ihl      = (sizeof(struct iphdr)+4)>>2;
        pip->tos      = 0xc0;
        pip->frag_off = htons(IP_DF);
        pip->ttl      = 1;
        pip->daddr    = rt->rt_dst;
        pip->saddr    = rt->rt_src;
        pip->protocol = IPPROTO_IGMP;
        pip->tot_len  = 0;      /* filled in later */
        ip_select_ident(pip, &rt->u.dst, NULL);
        ((u8*)&pip[1])[0] = IPOPT_RA;
        ((u8*)&pip[1])[1] = 4;
        ((u8*)&pip[1])[2] = 0;
        ((u8*)&pip[1])[3] = 0;

        pig =(struct igmpv3_report *)skb_put(skb, sizeof(*pig));
        skb->h.igmph = (struct igmphdr *)pig;
        pig->type = IGMPV3_HOST_MEMBERSHIP_REPORT;
        pig->resv1 = 0;
        pig->csum = 0;
        pig->resv2 = 0;
        pig->ngrec = 0;
        return skb;
}

static int igmpv3_sendpack(struct sk_buff *skb)
{
        struct iphdr *pip = skb->nh.iph;
        struct igmphdr *pig = skb->h.igmph;
        int iplen, igmplen;

        iplen = skb->tail - (unsigned char *)skb->nh.iph;
        pip->tot_len = htons(iplen);
        ip_send_check(pip);

        igmplen = skb->tail - (unsigned char *)skb->h.igmph;
        pig->csum = ip_compute_csum((void *)skb->h.igmph, igmplen);

        return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, skb->dev,
                       output_maybe_reroute);
}

static int grec_size(struct ip_mc_list *pmc, int type, int gdel, int sdel)
{
        return sizeof(struct igmpv3_grec) + 4*igmp_scount(pmc,type,gdel,sdel);
}

static struct sk_buff *add_grhead(struct sk_buff *skb, struct ip_mc_list *pmc,
        int type, struct igmpv3_grec **ppgr)
{
        struct net_device *dev = pmc->interface->dev;
        struct igmpv3_report *pih;
        struct igmpv3_grec *pgr;

        if (!skb)
                skb = igmpv3_newpack(dev, dev->mtu);
        if (!skb)
                return 0;
        pgr = (struct igmpv3_grec *)skb_put(skb, sizeof(struct igmpv3_grec));
        pgr->grec_type = type;
        pgr->grec_auxwords = 0;
        pgr->grec_nsrcs = 0;
        pgr->grec_mca = pmc->multiaddr;
        pih = (struct igmpv3_report *)skb->h.igmph;
        pih->ngrec = htons(ntohs(pih->ngrec)+1);
        *ppgr = pgr;
        return skb;
}

#define AVAILABLE(skb) ((skb) ? ((skb)->dev ? (skb)->dev->mtu - (skb)->len : \
        skb_tailroom(skb)) : 0)

static struct sk_buff *add_grec(struct sk_buff *skb, struct ip_mc_list *pmc,
        int type, int gdeleted, int sdeleted)
{
        struct net_device *dev = pmc->interface->dev;
        struct igmpv3_report *pih;
        struct igmpv3_grec *pgr = 0;
        struct ip_sf_list *psf, *psf_next, *psf_prev, **psf_list;
        int scount, first, isquery, truncate;

        if (pmc->multiaddr == IGMP_ALL_HOSTS)
                return skb;

        isquery = type == IGMPV3_MODE_IS_INCLUDE ||
                  type == IGMPV3_MODE_IS_EXCLUDE;
        truncate = type == IGMPV3_MODE_IS_EXCLUDE ||
                    type == IGMPV3_CHANGE_TO_EXCLUDE;

        psf_list = sdeleted ? &pmc->tomb : &pmc->sources;

        if (!*psf_list) {
                if (type == IGMPV3_ALLOW_NEW_SOURCES ||
                    type == IGMPV3_BLOCK_OLD_SOURCES)
                        return skb;
                if (pmc->crcount || isquery) {
                        /* make sure we have room for group header and at
                         * least one source.
                         */
                        if (skb && AVAILABLE(skb) < sizeof(struct igmpv3_grec)+
                            sizeof(__u32)) {
                                igmpv3_sendpack(skb);
                                skb = 0; /* add_grhead will get a new one */
                        }
                        skb = add_grhead(skb, pmc, type, &pgr);
                }
                return skb;
        }
        pih = skb ? (struct igmpv3_report *)skb->h.igmph : 0;

        /* EX and TO_EX get a fresh packet, if needed */
        if (truncate) {
                if (pih && pih->ngrec &&
                    AVAILABLE(skb) < grec_size(pmc, type, gdeleted, sdeleted)) {
                        if (skb)
                                igmpv3_sendpack(skb);
                        skb = igmpv3_newpack(dev, dev->mtu);
                }
        }
        first = 1;
        scount = 0;
        psf_prev = 0;
        for (psf=*psf_list; psf; psf=psf_next) {
                u32 *psrc;

                psf_next = psf->sf_next;

                if (!is_in(pmc, psf, type, gdeleted, sdeleted)) {
                        psf_prev = psf;
                        continue;
                }

                /* clear marks on query responses */
                if (isquery)
                        psf->sf_gsresp = 0;

                if (AVAILABLE(skb) < sizeof(u32) +
                    first*sizeof(struct igmpv3_grec)) {
                        if (truncate && !first)
                                break;   /* truncate these */
                        if (pgr)
                                pgr->grec_nsrcs = htons(scount);
                        if (skb)
                                igmpv3_sendpack(skb);
                        skb = igmpv3_newpack(dev, dev->mtu);
                        first = 1;
                        scount = 0;
                }
                if (first) {
                        skb = add_grhead(skb, pmc, type, &pgr);
                        first = 0;
                }
                psrc = (u32 *)skb_put(skb, sizeof(u32));
                *psrc = psf->sf_inaddr;
                scount++;
                if ((type == IGMPV3_ALLOW_NEW_SOURCES ||
                     type == IGMPV3_BLOCK_OLD_SOURCES) && psf->sf_crcount) {
                        psf->sf_crcount--;
                        if ((sdeleted || gdeleted) && psf->sf_crcount == 0) {
                                if (psf_prev)
                                        psf_prev->sf_next = psf->sf_next;
                                else
                                        *psf_list = psf->sf_next;
                                kfree(psf);
                                continue;
                        }
                }
                psf_prev = psf;
        }
        if (pgr)
                pgr->grec_nsrcs = htons(scount);

        if (isquery)
                pmc->gsquery = 0;       /* clear query state on report */
        return skb;
}

static int igmpv3_send_report(struct in_device *in_dev, struct ip_mc_list *pmc)
{
        struct sk_buff *skb = 0;
        int type;

        if (!pmc) {
                read_lock(&in_dev->lock);
                for (pmc=in_dev->mc_list; pmc; pmc=pmc->next) {
                        if (pmc->multiaddr == IGMP_ALL_HOSTS)
                                continue;
                        spin_lock_bh(&pmc->lock);
                        if (pmc->sfcount[MCAST_EXCLUDE])
                                type = IGMPV3_MODE_IS_EXCLUDE;
                        else
                                type = IGMPV3_MODE_IS_INCLUDE;
                        skb = add_grec(skb, pmc, type, 0, 0);
                        spin_unlock_bh(&pmc->lock);
                }
                read_unlock(&in_dev->lock);
        } else {
                spin_lock_bh(&pmc->lock);
                if (pmc->sfcount[MCAST_EXCLUDE])
                        type = IGMPV3_MODE_IS_EXCLUDE;
                else
                        type = IGMPV3_MODE_IS_INCLUDE;
                skb = add_grec(skb, pmc, type, 0, 0);
                spin_unlock_bh(&pmc->lock);
        }
        if (!skb)
                return 0;
        return igmpv3_sendpack(skb);
}

/*
 * remove zero-count source records from a source filter list
 */
static void igmpv3_clear_zeros(struct ip_sf_list **ppsf)
{
        struct ip_sf_list *psf_prev, *psf_next, *psf;

        psf_prev = 0;
        for (psf=*ppsf; psf; psf = psf_next) {
                psf_next = psf->sf_next;
                if (psf->sf_crcount == 0) {
                        if (psf_prev)
                                psf_prev->sf_next = psf->sf_next;
                        else
                                *ppsf = psf->sf_next;
                        kfree(psf);
                } else
                        psf_prev = psf;
        }
}

static void igmpv3_send_cr(struct in_device *in_dev)
{
        struct ip_mc_list *pmc, *pmc_prev, *pmc_next;
        struct sk_buff *skb = 0;
        int type, dtype;

        read_lock(&in_dev->lock);
        write_lock_bh(&in_dev->mc_lock);

        /* deleted MCA's */
        pmc_prev = 0;
        for (pmc=in_dev->mc_tomb; pmc; pmc=pmc_next) {
                pmc_next = pmc->next;
                if (pmc->sfmode == MCAST_INCLUDE) {
                        type = IGMPV3_BLOCK_OLD_SOURCES;
                        dtype = IGMPV3_BLOCK_OLD_SOURCES;
                        skb = add_grec(skb, pmc, type, 1, 0);
                        skb = add_grec(skb, pmc, dtype, 1, 1);
                }
                if (pmc->crcount) {
                        pmc->crcount--;
                        if (pmc->sfmode == MCAST_EXCLUDE) {
                                type = IGMPV3_CHANGE_TO_INCLUDE;
                                skb = add_grec(skb, pmc, type, 1, 0);
                        }
                        if (pmc->crcount == 0) {
                                igmpv3_clear_zeros(&pmc->tomb);
                                igmpv3_clear_zeros(&pmc->sources);
                        }
                }
                if (pmc->crcount == 0 && !pmc->tomb && !pmc->sources) {
                        if (pmc_prev)
                                pmc_prev->next = pmc_next;
                        else
                                in_dev->mc_tomb = pmc_next;
                        in_dev_put(pmc->interface);
                        kfree(pmc);
                } else
                        pmc_prev = pmc;
        }
        write_unlock_bh(&in_dev->mc_lock);

        /* change recs */
        for (pmc=in_dev->mc_list; pmc; pmc=pmc->next) {
                spin_lock_bh(&pmc->lock);
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        type = IGMPV3_BLOCK_OLD_SOURCES;
                        dtype = IGMPV3_ALLOW_NEW_SOURCES;
                } else {
                        type = IGMPV3_ALLOW_NEW_SOURCES;
                        dtype = IGMPV3_BLOCK_OLD_SOURCES;
                }
                skb = add_grec(skb, pmc, type, 0, 0);
                skb = add_grec(skb, pmc, dtype, 0, 1);  /* deleted sources */

                /* filter mode changes */
                if (pmc->crcount) {
                        pmc->crcount--;
                        if (pmc->sfmode == MCAST_EXCLUDE)
                                type = IGMPV3_CHANGE_TO_EXCLUDE;
                        else
                                type = IGMPV3_CHANGE_TO_INCLUDE;
                        skb = add_grec(skb, pmc, type, 0, 0);
                }
                spin_unlock_bh(&pmc->lock);
        }
        read_unlock(&in_dev->lock);
        if (!skb)
                return;
        (void) igmpv3_sendpack(skb);
}

static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc,
        int type)
{
        struct sk_buff *skb;
        struct iphdr *iph;
        struct igmphdr *ih;
        struct rtable *rt;
        struct net_device *dev = in_dev->dev;
        u32     group = pmc ? pmc->multiaddr : 0;
        u32     dst;

        if (type == IGMPV3_HOST_MEMBERSHIP_REPORT)
                return igmpv3_send_report(in_dev, pmc);
        else if (type == IGMP_HOST_LEAVE_MESSAGE)
                dst = IGMP_ALL_ROUTER;
        else
                dst = group;

        if (ip_route_output(&rt, dst, 0, 0, dev->ifindex))
                return -1;
        if (rt->rt_src == 0) {
                ip_rt_put(rt);
                return -1;
        }

        skb=alloc_skb(IGMP_SIZE+dev->hard_header_len+15, GFP_ATOMIC);
        if (skb == NULL) {
                ip_rt_put(rt);
                return -1;
        }

        skb->dst = &rt->u.dst;

        skb_reserve(skb, (dev->hard_header_len+15)&~15);

        skb->nh.iph = iph = (struct iphdr *)skb_put(skb, sizeof(struct iphdr)+4);

        iph->version  = 4;
        iph->ihl      = (sizeof(struct iphdr)+4)>>2;
        iph->tos      = 0xc0;
        iph->frag_off = htons(IP_DF);
        iph->ttl      = 1;
        iph->daddr    = dst;
        iph->saddr    = rt->rt_src;
        iph->protocol = IPPROTO_IGMP;
        iph->tot_len  = htons(IGMP_SIZE);
        ip_select_ident(iph, &rt->u.dst, NULL);
        ((u8*)&iph[1])[0] = IPOPT_RA;
        ((u8*)&iph[1])[1] = 4;
        ((u8*)&iph[1])[2] = 0;
        ((u8*)&iph[1])[3] = 0;
        ip_send_check(iph);

        ih = (struct igmphdr *)skb_put(skb, sizeof(struct igmphdr));
        ih->type=type;
        ih->code=0;
        ih->csum=0;
        ih->group=group;
        ih->csum=ip_compute_csum((void *)ih, sizeof(struct igmphdr));

        return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
                       output_maybe_reroute);
}

static void igmp_gq_timer_expire(unsigned long data)
{
        struct in_device *in_dev = (struct in_device *)data;

        in_dev->mr_gq_running = 0;
        igmpv3_send_report(in_dev, 0);
        __in_dev_put(in_dev);
}

static void igmp_ifc_timer_expire(unsigned long data)
{
        struct in_device *in_dev = (struct in_device *)data;

        igmpv3_send_cr(in_dev);
        if (in_dev->mr_ifc_count) {
                in_dev->mr_ifc_count--;
                igmp_ifc_start_timer(in_dev, IGMP_Unsolicited_Report_Interval);
        }
        __in_dev_put(in_dev);
}

static void igmp_ifc_event(struct in_device *in_dev)
{
        if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev))
                return;
        in_dev->mr_ifc_count = in_dev->mr_qrv ? in_dev->mr_qrv : 
                IGMP_Unsolicited_Report_Count;
        igmp_ifc_start_timer(in_dev, 1);
}


static void igmp_timer_expire(unsigned long data)
{
        struct ip_mc_list *im=(struct ip_mc_list *)data;
        struct in_device *in_dev = im->interface;

        spin_lock(&im->lock);
        im->tm_running=0;

        if (im->unsolicit_count) {
                im->unsolicit_count--;
                igmp_start_timer(im, IGMP_Unsolicited_Report_Interval);
        }
        im->reporter = 1;
        spin_unlock(&im->lock);

        if (IGMP_V1_SEEN(in_dev))
                igmp_send_report(in_dev, im, IGMP_HOST_MEMBERSHIP_REPORT);
        else if (IGMP_V2_SEEN(in_dev))
                igmp_send_report(in_dev, im, IGMPV2_HOST_MEMBERSHIP_REPORT);
        else
                igmp_send_report(in_dev, im, IGMPV3_HOST_MEMBERSHIP_REPORT);

        ip_ma_put(im);
}

static void igmp_marksources(struct ip_mc_list *pmc, int nsrcs, __u32 *srcs)
{
        struct ip_sf_list *psf;
        int i, scount;

        scount = 0;
        for (psf=pmc->sources; psf; psf=psf->sf_next) {
                if (scount == nsrcs)
                        break;
                for (i=0; i<nsrcs; i++)
                        if (srcs[i] == psf->sf_inaddr) {
                                psf->sf_gsresp = 1;
                                scount++;
                                break;
                        }
        }
}

static void igmp_heard_report(struct in_device *in_dev, u32 group)
{
        struct ip_mc_list *im;

        /* Timers are only set for non-local groups */

        if (group == IGMP_ALL_HOSTS)
                return;

        read_lock(&in_dev->lock);
        for (im=in_dev->mc_list; im!=NULL; im=im->next) {
                if (im->multiaddr == group) {
                        igmp_stop_timer(im);
                        break;
                }
        }
        read_unlock(&in_dev->lock);
}

static void igmp_heard_query(struct in_device *in_dev, struct igmphdr *ih,
        int len)
{
        struct igmpv3_query *ih3 = (struct igmpv3_query *)ih;
        struct ip_mc_list       *im;
        u32                     group = ih->group;
        int                     max_delay;
        int                     mark = 0;


        if (len == 8) {
                if (ih->code == 0) {
                        /* Alas, old v1 router presents here. */
        
                        max_delay = IGMP_Query_Response_Interval;
                        in_dev->mr_v1_seen = jiffies +
                                IGMP_V1_Router_Present_Timeout;
                        group = 0;
                } else {
                        /* v2 router present */
                        max_delay = ih->code*(HZ/IGMP_TIMER_SCALE);
                        in_dev->mr_v2_seen = jiffies +
                                IGMP_V2_Router_Present_Timeout;
                }
                /* cancel the interface change timer */
                in_dev->mr_ifc_count = 0;
                if (del_timer(&in_dev->mr_ifc_timer))
                        __in_dev_put(in_dev);
                /* clear deleted report items */
                igmpv3_clear_delrec(in_dev);
        } else if (len < 12) {
                return; /* ignore bogus packet; freed by caller */
        } else { /* v3 */
                max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
                if (!max_delay)
                        max_delay = 1;  /* can't mod w/ 0 */
                in_dev->mr_maxdelay = max_delay;
                if (ih3->qrv)
                        in_dev->mr_qrv = ih3->qrv;
                if (!group) { /* general query */
                        if (ih3->nsrcs)
                                return; /* no sources allowed */
                        igmp_gq_start_timer(in_dev);
                        return;
                }
                /* mark sources to include, if group & source-specific */
                mark = ih3->nsrcs != 0;
        }

        /*
         * - 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 a "local" group (224.0.0.X)
         * - For timers already running check if they need to
         *   be reset.
         * - Use the igmp->igmp_code field as the maximum
         *   delay possible
         */
        read_lock(&in_dev->lock);
        for (im=in_dev->mc_list; im!=NULL; im=im->next) {
                if (group && group != im->multiaddr)
                        continue;
                if (im->multiaddr == IGMP_ALL_HOSTS)
                        continue;
                spin_lock_bh(&im->lock);
                if (im->tm_running)
                        im->gsquery = im->gsquery && mark;
                else
                        im->gsquery = mark;
                if (im->gsquery)
                        igmp_marksources(im, ntohs(ih3->nsrcs), ih3->srcs);
                spin_unlock_bh(&im->lock);
                igmp_mod_timer(im, max_delay);
        }
        read_unlock(&in_dev->lock);
}

int igmp_rcv(struct sk_buff *skb)
{
        /* This basically follows the spec line by line -- see RFC1112 */
        struct igmphdr *ih = skb->h.igmph;
        struct in_device *in_dev = in_dev_get(skb->dev);
        int len = skb->len;

        if (in_dev==NULL) {
                kfree_skb(skb);
                return 0;
        }

        if (skb_is_nonlinear(skb)) {
                if (skb_linearize(skb, GFP_ATOMIC) != 0) {
                        kfree_skb(skb);
                        return -ENOMEM;
                }
                ih = skb->h.igmph;
        }

        if (len < sizeof(struct igmphdr) || ip_compute_csum((void *)ih, len)) {
                in_dev_put(in_dev);
                kfree_skb(skb);
                return 0;
        }

        switch (ih->type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:
                igmp_heard_query(in_dev, ih, len);
                break;
        case IGMP_HOST_MEMBERSHIP_REPORT:
        case IGMPV2_HOST_MEMBERSHIP_REPORT:
        case IGMPV3_HOST_MEMBERSHIP_REPORT:
                /* Is it our report looped back? */
                if (((struct rtable*)skb->dst)->key.iif == 0)
                        break;
                igmp_heard_report(in_dev, ih->group);
                break;
        case IGMP_PIM:
#ifdef CONFIG_IP_PIMSM_V1
                in_dev_put(in_dev);
                return pim_rcv_v1(skb);
#endif
        case IGMP_DVMRP:
        case IGMP_TRACE:
        case IGMP_HOST_LEAVE_MESSAGE:
        case IGMP_MTRACE:
        case IGMP_MTRACE_RESP:
                break;
        default:
                NETDEBUG(printk(KERN_DEBUG "New IGMP type=%d, why we do not know about it?\n", ih->type));
        }
        in_dev_put(in_dev);
        kfree_skb(skb);
        return 0;
}

#endif


/*
 *      Add a filter to a device
 */

static void ip_mc_filter_add(struct in_device *in_dev, u32 addr)
{
        char buf[MAX_ADDR_LEN];
        struct net_device *dev = in_dev->dev;

        /* Checking for IFF_MULTICAST here is WRONG-WRONG-WRONG.
           We will get multicast token leakage, when IFF_MULTICAST
           is changed. This check should be done in dev->set_multicast_list
           routine. Something sort of:
           if (dev->mc_list && dev->flags&IFF_MULTICAST) { do it; }
           --ANK
           */
        if (arp_mc_map(addr, buf, dev, 0) == 0)
                dev_mc_add(dev,buf,dev->addr_len,0);
}

/*
 *      Remove a filter from a device
 */

static void ip_mc_filter_del(struct in_device *in_dev, u32 addr)
{
        char buf[MAX_ADDR_LEN];
        struct net_device *dev = in_dev->dev;

        if (arp_mc_map(addr, buf, dev, 0) == 0)
                dev_mc_delete(dev,buf,dev->addr_len,0);
}

#ifdef CONFIG_IP_MULTICAST
/*
 * deleted ip_mc_list manipulation
 */
static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im)
{
        struct ip_mc_list *pmc;

        /* this is an "ip_mc_list" for convenience; only the fields below
         * are actually used. In particular, the refcnt and users are not
         * used for management of the delete list. Using the same structure
         * for deleted items allows change reports to use common code with
         * non-deleted or query-response MCA's.
         */
        pmc = (struct ip_mc_list *)kmalloc(sizeof(*pmc), GFP_KERNEL);
        if (!pmc)
                return;
        memset(pmc, 0, sizeof(*pmc));
        spin_lock_bh(&im->lock);
        pmc->interface = im->interface;
        in_dev_hold(in_dev);
        pmc->multiaddr = im->multiaddr;
        pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
                IGMP_Unsolicited_Report_Count;
        pmc->sfmode = im->sfmode;
        if (pmc->sfmode == MCAST_INCLUDE) {
                struct ip_sf_list *psf;

                pmc->tomb = im->tomb;
                pmc->sources = im->sources;
                im->tomb = im->sources = 0;
                for (psf=pmc->sources; psf; psf=psf->sf_next)
                        psf->sf_crcount = pmc->crcount;
        }
        spin_unlock_bh(&im->lock);

        write_lock_bh(&in_dev->mc_lock);
        pmc->next = in_dev->mc_tomb;
        in_dev->mc_tomb = pmc;
        write_unlock_bh(&in_dev->mc_lock);
}

static void igmpv3_del_delrec(struct in_device *in_dev, __u32 multiaddr)
{
        struct ip_mc_list *pmc, *pmc_prev;
        struct ip_sf_list *psf, *psf_next;

        write_lock_bh(&in_dev->mc_lock);
        pmc_prev = 0;
        for (pmc=in_dev->mc_tomb; pmc; pmc=pmc->next) {
                if (pmc->multiaddr == multiaddr)
                        break;
                pmc_prev = pmc;
        }
        if (pmc) {
                if (pmc_prev)
                        pmc_prev->next = pmc->next;
                else
                        in_dev->mc_tomb = pmc->next;
        }
        write_unlock_bh(&in_dev->mc_lock);
        if (pmc) {
                for (psf=pmc->tomb; psf; psf=psf_next) {
                        psf_next = psf->sf_next;
                        kfree(psf);
                }
                in_dev_put(pmc->interface);
                kfree(pmc);
        }
}

static void igmpv3_clear_delrec(struct in_device *in_dev)
{
        struct ip_mc_list *pmc, *nextpmc;

        write_lock_bh(&in_dev->mc_lock);
        pmc = in_dev->mc_tomb;
        in_dev->mc_tomb = 0;
        write_unlock_bh(&in_dev->mc_lock);

        for (; pmc; pmc = nextpmc) {
                nextpmc = pmc->next;
                ip_mc_clear_src(pmc);
                in_dev_put(pmc->interface);
                kfree(pmc);
        }
        /* clear dead sources, too */
        read_lock(&in_dev->lock);
        for (pmc=in_dev->mc_list; pmc; pmc=pmc->next) {
                struct ip_sf_list *psf, *psf_next;

                spin_lock_bh(&pmc->lock);
                psf = pmc->tomb;
                pmc->tomb = 0;
                spin_unlock_bh(&pmc->lock);
                for (; psf; psf=psf_next) {
                        psf_next = psf->sf_next;
                        kfree(psf);
                }
        }
        read_unlock(&in_dev->lock);
}
#endif

static void igmp_group_dropped(struct ip_mc_list *im)
{
        struct in_device *in_dev = im->interface;
#ifdef CONFIG_IP_MULTICAST
        int reporter;
#endif

        if (im->loaded) {
                im->loaded = 0;
                ip_mc_filter_del(in_dev, im->multiaddr);
        }

#ifdef CONFIG_IP_MULTICAST
        if (im->multiaddr == IGMP_ALL_HOSTS)
                return;

        reporter = im->reporter;
        igmp_stop_timer(im);

        if (in_dev->dev->flags & IFF_UP) {
                if (IGMP_V1_SEEN(in_dev))
                        goto done;
                if (IGMP_V2_SEEN(in_dev)) {
                        if (reporter)
                                igmp_send_report(in_dev, im, IGMP_HOST_LEAVE_MESSAGE);
                        goto done;
                }
                /* IGMPv3 */
                igmpv3_add_delrec(in_dev, im);

                igmp_ifc_event(in_dev);
        }
done:
#endif
        ip_mc_clear_src(im);
}

static void igmp_group_added(struct ip_mc_list *im)
{
        struct in_device *in_dev = im->interface;

        if (im->loaded == 0) {
                im->loaded = 1;
                ip_mc_filter_add(in_dev, im->multiaddr);
        }

#ifdef CONFIG_IP_MULTICAST
        if (im->multiaddr == IGMP_ALL_HOSTS)
                return;

        if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev)) {
                spin_lock_bh(&im->lock);
                igmp_start_timer(im, IGMP_Initial_Report_Delay);
                spin_unlock_bh(&im->lock);
                return;
        }
        /* else, v3 */

        im->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
                IGMP_Unsolicited_Report_Count;
        igmp_ifc_event(in_dev);
#endif
}


/*
 *      Multicast list managers
 */


/*
 *      A socket has joined a multicast group on device dev.
 */

void ip_mc_inc_group(struct in_device *in_dev, u32 addr)
{
        struct ip_mc_list *im;

        ASSERT_RTNL();

        for (im=in_dev->mc_list; im; im=im->next) {
                if (im->multiaddr == addr) {
                        im->users++;
                        ip_mc_add_src(in_dev, &addr, MCAST_EXCLUDE, 0, 0, 0);
                        goto out;
                }
        }

        im = (struct ip_mc_list *)kmalloc(sizeof(*im), GFP_KERNEL);
        if (!im)
                goto out;

        im->users=1;
        im->interface=in_dev;
        in_dev_hold(in_dev);
        im->multiaddr=addr;
        /* initial mode is (EX, empty) */
        im->sfmode = MCAST_EXCLUDE;
        im->sfcount[MCAST_INCLUDE] = 0;
        im->sfcount[MCAST_EXCLUDE] = 1;
        im->sources = 0;
        im->tomb = 0;
        im->crcount = 0;
        atomic_set(&im->refcnt, 1);
        spin_lock_init(&im->lock);
#ifdef CONFIG_IP_MULTICAST
        im->tm_running=0;
        init_timer(&im->timer);
        im->timer.data=(unsigned long)im;
        im->timer.function=&igmp_timer_expire;
        im->unsolicit_count = IGMP_Unsolicited_Report_Count;
        im->reporter = 0;
        im->gsquery = 0;
#endif
        im->loaded = 0;
        write_lock_bh(&in_dev->lock);
        im->next=in_dev->mc_list;
        in_dev->mc_list=im;
        write_unlock_bh(&in_dev->lock);
#ifdef CONFIG_IP_MULTICAST
        igmpv3_del_delrec(in_dev, im->multiaddr);
#endif
        igmp_group_added(im);
        if (in_dev->dev->flags & IFF_UP)
                ip_rt_multicast_event(in_dev);
out:
        return;
}

/*
 *      A socket has left a multicast group on device dev
 */

void ip_mc_dec_group(struct in_device *in_dev, u32 addr)
{
        struct ip_mc_list *i, **ip;
        
        ASSERT_RTNL();
        
        for (ip=&in_dev->mc_list; (i=*ip)!=NULL; ip=&i->next) {
                if (i->multiaddr==addr) {
                        if (--i->users == 0) {
                                write_lock_bh(&in_dev->lock);
                                *ip = i->next;
                                write_unlock_bh(&in_dev->lock);
                                igmp_group_dropped(i);

                                if (in_dev->dev->flags & IFF_UP)
                                        ip_rt_multicast_event(in_dev);

                                ip_ma_put(i);
                                return;
                        }
                        break;
                }
        }
}

/* Device going down */

void ip_mc_down(struct in_device *in_dev)
{
        struct ip_mc_list *i;

        ASSERT_RTNL();

#ifdef CONFIG_IP_MULTICAST
        in_dev->mr_ifc_count = 0;
        if (del_timer(&in_dev->mr_ifc_timer))
                __in_dev_put(in_dev);
        in_dev->mr_gq_running = 0;
        if (del_timer(&in_dev->mr_gq_timer))
                __in_dev_put(in_dev);
#endif

        for (i=in_dev->mc_list; i; i=i->next)
                igmp_group_dropped(i);

#ifdef CONFIG_IP_MULTICAST
        igmpv3_clear_delrec(in_dev);
#endif

        ip_mc_dec_group(in_dev, IGMP_ALL_HOSTS);
}

/* Device going up */

void ip_mc_up(struct in_device *in_dev)
{
        struct ip_mc_list *i;

        ASSERT_RTNL();

        in_dev->mc_tomb = 0;
#ifdef CONFIG_IP_MULTICAST
        in_dev->mr_gq_running = 0;
        init_timer(&in_dev->mr_gq_timer);
        in_dev->mr_gq_timer.data=(unsigned long) in_dev;
        in_dev->mr_gq_timer.function=&igmp_gq_timer_expire;
        in_dev->mr_ifc_count = 0;
        init_timer(&in_dev->mr_ifc_timer);
        in_dev->mr_ifc_timer.data=(unsigned long) in_dev;
        in_dev->mr_ifc_timer.function=&igmp_ifc_timer_expire;
        in_dev->mr_qrv = IGMP_Unsolicited_Report_Count;
#endif

        in_dev->mc_lock = RW_LOCK_UNLOCKED;
        ip_mc_inc_group(in_dev, IGMP_ALL_HOSTS);

        for (i=in_dev->mc_list; i; i=i->next)
                igmp_group_added(i);
}

/*
 *      Device is about to be destroyed: clean up.
 */

void ip_mc_destroy_dev(struct in_device *in_dev)
{
        struct ip_mc_list *i;

        ASSERT_RTNL();

        write_lock_bh(&in_dev->lock);
        while ((i = in_dev->mc_list) != NULL) {
                in_dev->mc_list = i->next;
                write_unlock_bh(&in_dev->lock);

                igmp_group_dropped(i);
                ip_ma_put(i);

                write_lock_bh(&in_dev->lock);
        }
        write_unlock_bh(&in_dev->lock);
}

static struct in_device * ip_mc_find_dev(struct ip_mreqn *imr)
{
        struct rtable *rt;
        struct net_device *dev = NULL;
        struct in_device *idev = NULL;

        if (imr->imr_ifindex) {
                idev = inetdev_by_index(imr->imr_ifindex);
                if (idev)
                        __in_dev_put(idev);
                return idev;
        }
        if (imr->imr_address.s_addr) {
                dev = ip_dev_find(imr->imr_address.s_addr);
                if (!dev)
                        return NULL;
                __dev_put(dev);
        }

        if (!dev && !ip_route_output(&rt, imr->imr_multiaddr.s_addr, 0, 0, 0)) {
                dev = rt->u.dst.dev;
                ip_rt_put(rt);
        }
        if (dev) {
                imr->imr_ifindex = dev->ifindex;
                idev = __in_dev_get(dev);
        }
        return idev;
}

/*
 *      Join a socket to a group
 */
int sysctl_igmp_max_memberships = IP_MAX_MEMBERSHIPS;


static int ip_mc_del1_src(struct ip_mc_list *pmc, int sfmode,
        __u32 *psfsrc)
{
        struct ip_sf_list *psf, *psf_prev;
        int rv = 0;

        psf_prev = 0;
        for (psf=pmc->sources; psf; psf=psf->sf_next) {
                if (psf->sf_inaddr == *psfsrc)
                        break;
                psf_prev = psf;
        }
        if (!psf || psf->sf_count[sfmode] == 0) {
                /* source filter not found, or count wrong =>  bug */
                return -ESRCH;
        }
        psf->sf_count[sfmode]--;
        if (psf->sf_count[sfmode] == 0) {
                ip_rt_multicast_event(pmc->interface);
        }
        if (!psf->sf_count[MCAST_INCLUDE] && !psf->sf_count[MCAST_EXCLUDE]) {
#ifdef CONFIG_IP_MULTICAST
                struct in_device *in_dev = pmc->interface;
#endif

                /* no more filters for this source */
                if (psf_prev)
                        psf_prev->sf_next = psf->sf_next;
                else
                        pmc->sources = psf->sf_next;
#ifdef CONFIG_IP_MULTICAST
                if (psf->sf_oldin &&
                    !IGMP_V1_SEEN(in_dev) && !IGMP_V2_SEEN(in_dev)) {
                        psf->sf_crcount = in_dev->mr_qrv ? in_dev->mr_qrv : 
                                IGMP_Unsolicited_Report_Count;
                        psf->sf_next = pmc->tomb;
                        pmc->tomb = psf;
                        rv = 1;
                } else
#endif
                        kfree(psf);
        }
        return rv;
}

int ip_mc_del_src(struct in_device *in_dev, __u32 *pmca, int sfmode,
        int sfcount, __u32 *psfsrc, int delta)
{
        struct ip_mc_list *pmc;
        int     changerec = 0;
        int     i, err;

        if (!in_dev)
                return -ENODEV;
        read_lock(&in_dev->lock);
        for (pmc=in_dev->mc_list; pmc; pmc=pmc->next) {
                if (*pmca == pmc->multiaddr)
                        break;
        }
        if (!pmc) {
                /* MCA not found?? bug */
                read_unlock(&in_dev->lock);
                return -ESRCH;
        }
        spin_lock_bh(&pmc->lock);
        read_unlock(&in_dev->lock);
#ifdef CONFIG_IP_MULTICAST
        sf_markstate(pmc);
#endif
        if (!delta) {
                err = -EINVAL;
                if (!pmc->sfcount[sfmode])
                        goto out_unlock;
                pmc->sfcount[sfmode]--;
        }
        err = 0;
        for (i=0; i<sfcount; i++) {
                int rv = ip_mc_del1_src(pmc, sfmode, &psfsrc[i]);

                changerec |= rv > 0;
                if (!err && rv < 0)
                        err = rv;
        }
        if (pmc->sfmode == MCAST_EXCLUDE &&
            pmc->sfcount[MCAST_EXCLUDE] == 0 &&
            pmc->sfcount[MCAST_INCLUDE]) {
#ifdef CONFIG_IP_MULTICAST
                struct ip_sf_list *psf;
#endif

                /* filter mode change */
                pmc->sfmode = MCAST_INCLUDE;
#ifdef CONFIG_IP_MULTICAST
                pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv : 
                        IGMP_Unsolicited_Report_Count;
                in_dev->mr_ifc_count = pmc->crcount;
                for (psf=pmc->sources; psf; psf = psf->sf_next)
                        psf->sf_crcount = 0;
                igmp_ifc_event(pmc->interface);
        } else if (sf_setstate(pmc) || changerec) {
                igmp_ifc_event(pmc->interface);
#endif
        }
out_unlock:
        spin_unlock_bh(&pmc->lock);
        return err;
}

/*
 * Add multicast single-source filter to the interface list
 */
static int ip_mc_add1_src(struct ip_mc_list *pmc, int sfmode,
        __u32 *psfsrc, int delta)
{
        struct ip_sf_list *psf, *psf_prev;

        psf_prev = 0;
        for (psf=pmc->sources; psf; psf=psf->sf_next) {
                if (psf->sf_inaddr == *psfsrc)
                        break;
                psf_prev = psf;
        }
        if (!psf) {
                psf = (struct ip_sf_list *)kmalloc(sizeof(*psf), GFP_ATOMIC);
                if (!psf)
                        return -ENOBUFS;
                memset(psf, 0, sizeof(*psf));
                psf->sf_inaddr = *psfsrc;
                if (psf_prev) {
                        psf_prev->sf_next = psf;
                } else
                        pmc->sources = psf;
        }
        psf->sf_count[sfmode]++;
        if (psf->sf_count[sfmode] == 1) {
                ip_rt_multicast_event(pmc->interface);
        }
        return 0;
}

#ifdef CONFIG_IP_MULTICAST
static void sf_markstate(struct ip_mc_list *pmc)
{
        struct ip_sf_list *psf;
        int mca_xcount = pmc->sfcount[MCAST_EXCLUDE];

        for (psf=pmc->sources; psf; psf=psf->sf_next)
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        psf->sf_oldin = mca_xcount ==
                                psf->sf_count[MCAST_EXCLUDE] &&
                                !psf->sf_count[MCAST_INCLUDE];
                } else
                        psf->sf_oldin = psf->sf_count[MCAST_INCLUDE] != 0;
}

static int sf_setstate(struct ip_mc_list *pmc)
{
        struct ip_sf_list *psf;
        int mca_xcount = pmc->sfcount[MCAST_EXCLUDE];
        int qrv = pmc->interface->mr_qrv;
        int new_in, rv;

        rv = 0;
        for (psf=pmc->sources; psf; psf=psf->sf_next) {
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        new_in = mca_xcount == psf->sf_count[MCAST_EXCLUDE] &&
                                !psf->sf_count[MCAST_INCLUDE];
                } else
                        new_in = psf->sf_count[MCAST_INCLUDE] != 0;
                if (new_in != psf->sf_oldin) {
                        psf->sf_crcount = qrv;
                        rv++;
                }
        }
        return rv;
}
#endif

/*
 * Add multicast source filter list to the interface list
 */
int ip_mc_add_src(struct in_device *in_dev, __u32 *pmca, int sfmode,
        int sfcount, __u32 *psfsrc, int delta)
{
        struct ip_mc_list *pmc;
        int     isexclude;
        int     i, err;

        if (!in_dev)
                return -ENODEV;
        read_lock(&in_dev->lock);
        for (pmc=in_dev->mc_list; pmc; pmc=pmc->next) {
                if (*pmca == pmc->multiaddr)
                        break;
        }
        if (!pmc) {
                /* MCA not found?? bug */
                read_unlock(&in_dev->lock);
                return -ESRCH;
        }
        spin_lock_bh(&pmc->lock);
        read_unlock(&in_dev->lock);

#ifdef CONFIG_IP_MULTICAST
        sf_markstate(pmc);
#endif
        isexclude = pmc->sfmode == MCAST_EXCLUDE;
        if (!delta)
                pmc->sfcount[sfmode]++;
        err = 0;
        for (i=0; i<sfcount; i++) {
                err = ip_mc_add1_src(pmc, sfmode, &psfsrc[i], delta);
                if (err)
                        break;
        }
        if (err) {
                int j;

                pmc->sfcount[sfmode]--;
                for (j=0; j<i; j++)
                        (void) ip_mc_del1_src(pmc, sfmode, &psfsrc[i]);
        } else if (isexclude != (pmc->sfcount[MCAST_EXCLUDE] != 0)) {
#ifdef CONFIG_IP_MULTICAST
                struct in_device *in_dev = pmc->interface;
                struct ip_sf_list *psf;
#endif

                /* filter mode change */
                if (pmc->sfcount[MCAST_EXCLUDE])
                        pmc->sfmode = MCAST_EXCLUDE;
                else if (pmc->sfcount[MCAST_INCLUDE])
                        pmc->sfmode = MCAST_INCLUDE;
#ifdef CONFIG_IP_MULTICAST
                /* else no filters; keep old mode for reports */

                pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv : 
                        IGMP_Unsolicited_Report_Count;
                in_dev->mr_ifc_count = pmc->crcount;
                for (psf=pmc->sources; psf; psf = psf->sf_next)
                        psf->sf_crcount = 0;
                igmp_ifc_event(in_dev);
        } else if (sf_setstate(pmc)) {
                igmp_ifc_event(in_dev);
#endif
        }
        spin_unlock_bh(&pmc->lock);
        return err;
}

static void ip_mc_clear_src(struct ip_mc_list *pmc)
{
        struct ip_sf_list *psf, *nextpsf;

        for (psf=pmc->tomb; psf; psf=nextpsf) {
                nextpsf = psf->sf_next;
                kfree(psf);
        }
        pmc->tomb = 0;
        for (psf=pmc->sources; psf; psf=nextpsf) {
                nextpsf = psf->sf_next;
                kfree(psf);
        }
        pmc->sources = 0;
        pmc->sfmode = MCAST_EXCLUDE;
        pmc->sfcount[MCAST_EXCLUDE] = 0;
        pmc->sfcount[MCAST_EXCLUDE] = 1;
}


/*
 * Join a multicast group
 */
int ip_mc_join_group(struct sock *sk , struct ip_mreqn *imr)
{
        int err;
        u32 addr = imr->imr_multiaddr.s_addr;
        struct ip_mc_socklist *iml, *i;
        struct in_device *in_dev;
        struct inet_opt *inet = &sk->protinfo.af_inet;
        int count = 0;

        if (!MULTICAST(addr))
                return -EINVAL;

        rtnl_shlock();

        in_dev = ip_mc_find_dev(imr);

        if (!in_dev) {
                iml = NULL;
                err = -ENODEV;
                goto done;
        }

        iml = (struct ip_mc_socklist *)sock_kmalloc(sk, sizeof(*iml), GFP_KERNEL);

        err = -EADDRINUSE;
        for (i = inet->mc_list; i; i = i->next) {
                if (memcmp(&i->multi, imr, sizeof(*imr)) == 0) {
                        /* New style additions are reference counted */
                        if (imr->imr_address.s_addr == 0) {
                                i->count++;
                                err = 0;
                        }
                        goto done;
                }
                count++;
        }
        err = -ENOBUFS;
        if (iml == NULL || count >= sysctl_igmp_max_memberships)
                goto done;
        memcpy(&iml->multi, imr, sizeof(*imr));
        iml->next = sk->protinfo.af_inet.mc_list;
        iml->count = 1;
        iml->sflist = NULL;
        iml->sfmode = MCAST_EXCLUDE;
        inet->mc_list = iml;
        ip_mc_inc_group(in_dev, addr);
        iml = NULL;
        err = 0;

done:
        rtnl_shunlock();
        if (iml)
                sock_kfree_s(sk, iml, sizeof(*iml));
        return err;
}

int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml,
        struct in_device *in_dev)
{
        int err;

        if (iml->sflist == 0) {
                /* any-source empty exclude case */
                return ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
                        iml->sfmode, 0, 0, 0);
        }
        err = ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
                        iml->sfmode, iml->sflist->sl_count,
                        iml->sflist->sl_addr, 0);
        sock_kfree_s(sk, iml->sflist, IP_SFLSIZE(iml->sflist->sl_max));
        iml->sflist = 0;
        return err;
}

/*
 *      Ask a socket to leave a group.
 */

int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr)
{
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_mc_socklist *iml, **imlp;

        rtnl_lock();
        for (imlp = &inet->mc_list; (iml = *imlp) != NULL; imlp = &iml->next) {
                if (iml->multi.imr_multiaddr.s_addr==imr->imr_multiaddr.s_addr &&
                    iml->multi.imr_address.s_addr==imr->imr_address.s_addr &&
                    (!imr->imr_ifindex || iml->multi.imr_ifindex==imr->imr_ifindex)) {
                        struct in_device *in_dev;

                        in_dev = inetdev_by_index(iml->multi.imr_ifindex);
                        if (in_dev)
                                (void) ip_mc_leave_src(sk, iml, in_dev);
                        if (--iml->count) {
                                rtnl_unlock();
                                if (in_dev)
                                        in_dev_put(in_dev);
                                return 0;
                        }

                        *imlp = iml->next;

                        if (in_dev) {
                                ip_mc_dec_group(in_dev, imr->imr_multiaddr.s_addr);
                                in_dev_put(in_dev);
                        }
                        rtnl_unlock();
                        sock_kfree_s(sk, iml, sizeof(*iml));
                        return 0;
                }
        }
        rtnl_unlock();
        return -EADDRNOTAVAIL;
}

int ip_mc_source(int add, int omode, struct sock *sk, struct
        ip_mreq_source *mreqs, int ifindex)
{
        int err;
        struct ip_mreqn imr;
        u32 addr = mreqs->imr_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev = 0;
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_sf_socklist *psl;
        int i, j, rv;

        if (!MULTICAST(addr))
                return -EINVAL;

        rtnl_shlock();

        imr.imr_multiaddr.s_addr = mreqs->imr_multiaddr;
        imr.imr_address.s_addr = mreqs->imr_interface;
        imr.imr_ifindex = ifindex;
        in_dev = ip_mc_find_dev(&imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }
        err = -EADDRNOTAVAIL;

        for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
                if (memcmp(&pmc->multi, mreqs, 2*sizeof(__u32)) == 0)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        /* if a source filter was set, must be the same mode as before */
        if (pmc->sflist) {
                if (pmc->sfmode != omode)
                        goto done;
        } else if (pmc->sfmode != omode) {
                /* allow mode switches for empty-set filters */
                ip_mc_del_src(in_dev, &mreqs->imr_multiaddr, pmc->sfmode, 0, 
                        0, 0);
                pmc->sfmode = omode;
                ip_mc_add_src(in_dev, &mreqs->imr_multiaddr, pmc->sfmode, 0, 
                        0, 0);
        }

        psl = pmc->sflist;
        if (!add) {
                if (!psl)
                        goto done;
                rv = !0;
                for (i=0; i<psl->sl_count; i++) {
                        rv = memcmp(&psl->sl_addr, &mreqs->imr_multiaddr,
                                sizeof(__u32));
                        if (rv >= 0)
                                break;
                }
                if (!rv)        /* source not found */
                        goto done;

                /* update the interface filter */
                ip_mc_del_src(in_dev, &mreqs->imr_multiaddr, omode, 1, 
                        &mreqs->imr_sourceaddr, 1);

                for (j=i+1; j<psl->sl_count; j++)
                        psl->sl_addr[j-1] = psl->sl_addr[j];
                psl->sl_count--;
                err = 0;
                goto done;
        }
        /* else, add a new source to the filter */

        if (!psl || psl->sl_count == psl->sl_max) {
                struct ip_sf_socklist *newpsl;
                int count = IP_SFBLOCK;

                if (psl)
                        count += psl->sl_max;
                newpsl = (struct ip_sf_socklist *)sock_kmalloc(sk,
                        IP_SFLSIZE(count), GFP_KERNEL);
                if (!newpsl) {
                        err = -ENOBUFS;
                        goto done;
                }
                newpsl->sl_max = count;
                newpsl->sl_count = count - IP_SFBLOCK;
                if (psl) {
                        for (i=0; i<psl->sl_count; i++)
                                newpsl->sl_addr[i] = psl->sl_addr[i];
                        sock_kfree_s(sk, psl, IP_SFLSIZE(psl->sl_max));
                }
                pmc->sflist = psl = newpsl;
        }
        rv = 1; /* > 0 for insert logic below if sl_count is 0 */
        for (i=0; i<psl->sl_count; i++) {
                rv = memcmp(&psl->sl_addr, &mreqs->imr_multiaddr,
                        sizeof(__u32));
                if (rv >= 0)
                        break;
        }
        if (rv == 0)            /* address already there is an error */
                goto done;
        for (j=psl->sl_count-1; j>=i; j--)
                psl->sl_addr[j+1] = psl->sl_addr[j];
        psl->sl_addr[i] = mreqs->imr_sourceaddr;
        psl->sl_count++;
        err = 0;
        /* update the interface list */
        ip_mc_add_src(in_dev, &mreqs->imr_multiaddr, omode, 1, 
                &mreqs->imr_sourceaddr, 1);
done:
        rtnl_shunlock();
        return err;
}

int ip_mc_msfilter(struct sock *sk, struct ip_msfilter *msf, int ifindex)
{
        int err;
        struct ip_mreqn imr;
        u32 addr = msf->imsf_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev;
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_sf_socklist *newpsl, *psl;

        if (!MULTICAST(addr))
                return -EINVAL;
        if (msf->imsf_fmode != MCAST_INCLUDE &&
            msf->imsf_fmode != MCAST_EXCLUDE)
                return -EINVAL;

        rtnl_shlock();

        imr.imr_multiaddr.s_addr = msf->imsf_multiaddr;
        imr.imr_address.s_addr = msf->imsf_interface;
        imr.imr_ifindex = ifindex;
        in_dev = ip_mc_find_dev(&imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }
        err = -EADDRNOTAVAIL;

        for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
                if (pmc->multi.imr_multiaddr.s_addr == msf->imsf_multiaddr &&
                    pmc->multi.imr_ifindex == imr.imr_ifindex)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        if (msf->imsf_numsrc) {
                newpsl = (struct ip_sf_socklist *)sock_kmalloc(sk,
                                IP_SFLSIZE(msf->imsf_numsrc), GFP_KERNEL);
                if (!newpsl) {
                        err = -ENOBUFS;
                        goto done;
                }
                newpsl->sl_max = newpsl->sl_count = msf->imsf_numsrc;
                memcpy(newpsl->sl_addr, msf->imsf_slist,
                        msf->imsf_numsrc * sizeof(msf->imsf_slist[0]));
                err = ip_mc_add_src(in_dev, &msf->imsf_multiaddr,
                        msf->imsf_fmode, newpsl->sl_count, newpsl->sl_addr, 0);
                if (err) {
                        sock_kfree_s(sk, newpsl, IP_SFLSIZE(newpsl->sl_max));
                        goto done;
                }
        } else
                newpsl = 0;
        psl = pmc->sflist;
        if (psl) {
                (void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
                        psl->sl_count, psl->sl_addr, 0);
                sock_kfree_s(sk, psl, IP_SFLSIZE(psl->sl_max));
        } else
                (void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
                        0, 0, 0);
        pmc->sflist = newpsl;
        pmc->sfmode = msf->imsf_fmode;
done:
        rtnl_shunlock();
        return err;
}

int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
        struct ip_msfilter *optval, int *optlen)
{
        int err, len, count, copycount;
        struct ip_mreqn imr;
        u32 addr = msf->imsf_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev;
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_sf_socklist *psl;

        if (!MULTICAST(addr))
                return -EINVAL;

        rtnl_shlock();

        imr.imr_multiaddr.s_addr = msf->imsf_multiaddr;
        imr.imr_address.s_addr = msf->imsf_interface;
        imr.imr_ifindex = 0;
        in_dev = ip_mc_find_dev(&imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }
        err = -EADDRNOTAVAIL;

        for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
                if (pmc->multi.imr_multiaddr.s_addr == msf->imsf_multiaddr &&
                    pmc->multi.imr_ifindex == imr.imr_ifindex)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        msf->imsf_fmode = pmc->sfmode;
        psl = pmc->sflist;
        rtnl_shunlock();
        if (!psl) {
                len = 0;
                count = 0;
        } else {
                count = psl->sl_count;
        }
        copycount = count < msf->imsf_numsrc ? count : msf->imsf_numsrc;
        len = copycount * sizeof(psl->sl_addr[0]);
        msf->imsf_numsrc = count;
        if (put_user(IP_MSFILTER_SIZE(copycount), optlen) ||
            copy_to_user((void *)optval, msf, IP_MSFILTER_SIZE(0))) {
                return -EFAULT;
        }
        if (len &&
            copy_to_user((void *)&optval->imsf_slist[0], psl->sl_addr, len))
                return -EFAULT;
        return 0;
done:
        rtnl_shunlock();
        return err;
}

int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
        struct group_filter *optval, int *optlen)
{
        int err, i, count, copycount;
        struct sockaddr_in *psin;
        u32 addr;
        struct ip_mc_socklist *pmc;
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_sf_socklist *psl;

        psin = (struct sockaddr_in *)&gsf->gf_group;
        if (psin->sin_family != AF_INET)
                return -EINVAL;
        addr = psin->sin_addr.s_addr;
        if (!MULTICAST(addr))
                return -EINVAL;

        rtnl_shlock();

        err = -EADDRNOTAVAIL;

        for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
                if (pmc->multi.imr_multiaddr.s_addr == addr &&
                    pmc->multi.imr_ifindex == gsf->gf_interface)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        gsf->gf_fmode = pmc->sfmode;
        psl = pmc->sflist;
        rtnl_shunlock();
        count = psl ? psl->sl_count : 0;
        copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
        gsf->gf_numsrc = count;
        if (put_user(GROUP_FILTER_SIZE(copycount), optlen) ||
            copy_to_user((void *)optval, gsf, GROUP_FILTER_SIZE(0))) {
                return -EFAULT;
        }
        for (i=0; i<copycount; i++) {
                struct sockaddr_in *psin;
                struct sockaddr_storage ss;

                psin = (struct sockaddr_in *)&ss;
                memset(&ss, 0, sizeof(ss));
                psin->sin_family = AF_INET;
                psin->sin_addr.s_addr = psl->sl_addr[i];
                if (copy_to_user((void *)&optval->gf_slist[i], &ss, sizeof(ss)))
                        return -EFAULT;
        }
        return 0;
done:
        rtnl_shunlock();
        return err;
}

/*
 * check if a multicast source filter allows delivery for a given <src,dst,intf>
 */
int ip_mc_sf_allow(struct sock *sk, u32 loc_addr, u32 rmt_addr, int dif)
{
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_mc_socklist *pmc;
        struct ip_sf_socklist *psl;
        int i;

        if (!MULTICAST(loc_addr))
                return 1;

        for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
                if (pmc->multi.imr_multiaddr.s_addr == loc_addr &&
                    pmc->multi.imr_ifindex == dif)
                        break;
        }
        if (!pmc)
                return 1;
        psl = pmc->sflist;
        if (!psl)
                return pmc->sfmode == MCAST_EXCLUDE;

        for (i=0; i<psl->sl_count; i++) {
                if (psl->sl_addr[i] == rmt_addr)
                        break;
        }
        if (pmc->sfmode == MCAST_INCLUDE && i >= psl->sl_count)
                return 0;
        if (pmc->sfmode == MCAST_EXCLUDE && i < psl->sl_count)
                return 0;
        return 1;
}

/*
 *      A socket is closing.
 */

void ip_mc_drop_socket(struct sock *sk)
{
        struct inet_opt *inet = &sk->protinfo.af_inet;
        struct ip_mc_socklist *iml;

        if (inet->mc_list == NULL)
                return;

        rtnl_lock();
        while ((iml = inet->mc_list) != NULL) {
                struct in_device *in_dev;
                inet->mc_list = iml->next;

                if ((in_dev = inetdev_by_index(iml->multi.imr_ifindex)) != NULL) {
                        (void) ip_mc_leave_src(sk, iml, in_dev);
                        ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr);
                        in_dev_put(in_dev);
                }
                sock_kfree_s(sk, iml, sizeof(*iml));

        }
        rtnl_unlock();
}

int ip_check_mc(struct in_device *in_dev, u32 mc_addr, u32 src_addr)
{
        struct ip_mc_list *im;
        struct ip_sf_list *psf;
        int rv = 0;

        read_lock(&in_dev->lock);
        for (im=in_dev->mc_list; im; im=im->next) {
                if (im->multiaddr == mc_addr)
                        break;
        }
        /*
         * This should check the protocol and allow all IGMP packets
         * here, but it isn't available in the call from ip_route_output()
         * in 2.4.x. It shouldn't actually matter, since groups joined
         * from within the kernel will have an {exclude, empty} filter.
         * Differs from 2.5.x here.     +-DLS 4/23/03
         */
        if (im) {
                for (psf=im->sources; psf; psf=psf->sf_next) {
                        if (psf->sf_inaddr == src_addr)
                                break;
                }
                if (psf)
                        rv = psf->sf_count[MCAST_INCLUDE] ||
                                psf->sf_count[MCAST_EXCLUDE] !=
                                im->sfcount[MCAST_EXCLUDE];
                else
                        rv = im->sfcount[MCAST_EXCLUDE] != 0;
        }
        read_unlock(&in_dev->lock);
        return rv;
}


int ip_mc_procinfo(char *buffer, char **start, off_t offset, int length)
{
        off_t pos=0, begin=0;
        struct ip_mc_list *im;
        int len=0;
        struct net_device *dev;

        len=sprintf(buffer,"Idx\tDevice    : Count Querier\tGroup    Users Timer\tReporter\n");  

        read_lock(&dev_base_lock);
        for(dev = dev_base; dev; dev = dev->next) {
                struct in_device *in_dev = in_dev_get(dev);
                char   *querier = "NONE";

                if (in_dev == NULL)
                        continue;

#ifdef CONFIG_IP_MULTICAST
                querier = IGMP_V1_SEEN(in_dev) ? "V1" : "V2";
#endif

                len+=sprintf(buffer+len,"%d\t%-10s: %5d %7s\n",
                             dev->ifindex, dev->name, dev->mc_count, querier);

                read_lock(&in_dev->lock);
                for (im = in_dev->mc_list; im; im = im->next) {
                        len+=sprintf(buffer+len,
                                     "\t\t\t\t%08lX %5d %d:%08lX\t\t%d\n",
                                     im->multiaddr, im->users,
                                     im->tm_running, im->timer.expires-jiffies, im->reporter);

                        pos=begin+len;
                        if(pos<offset)
                        {
                                len=0;
                                begin=pos;
                        }
                        if(pos>offset+length) {
                                read_unlock(&in_dev->lock);
                                in_dev_put(in_dev);
                                goto done;
                        }
                }
                read_unlock(&in_dev->lock);
                in_dev_put(in_dev);
        }
done:
        read_unlock(&dev_base_lock);

        *start=buffer+(offset-begin);
        len-=(offset-begin);
        if(len>length)
                len=length;
        if(len<0)
                len=0;
        return len;
}

int ip_mcf_procinfo(char *buffer, char **start, off_t offset, int length)
{
        off_t pos=0, begin=0;
        int len=0;
        int first = 1;
        struct net_device *dev;

        read_lock(&dev_base_lock);
        for(dev=dev_base; dev; dev=dev->next) {
                struct in_device *in_dev = in_dev_get(dev);
                struct ip_mc_list *imc;

                if (in_dev == NULL)
                        continue;

                read_lock(&in_dev->lock);

                for (imc=in_dev->mc_list; imc; imc=imc->next) {
                        struct ip_sf_list *psf;

                        spin_lock_bh(&imc->lock);
                        for (psf=imc->sources; psf; psf=psf->sf_next) {
                                if (first) {
                                        len += sprintf(buffer+len, "%3s %6s "
                                                "%10s %10s %6s %6s\n", "Idx",
                                                "Device", "MCA", "SRC", "INC",
                                                "EXC");
                                        first = 0;
                                }
                                len += sprintf(buffer+len, "%3d %6.6s 0x%08x "
                                        "0x%08x %6lu %6lu\n", dev->ifindex,
                                        dev->name, ntohl(imc->multiaddr),
                                        ntohl(psf->sf_inaddr),
                                        psf->sf_count[MCAST_INCLUDE],
                                        psf->sf_count[MCAST_EXCLUDE]);
                                pos=begin+len;
                                if(pos<offset)
                                {
                                        len=0;
                                        begin=pos;
                                }
                                if(pos>offset+length) {
                                        spin_unlock_bh(&imc->lock);
                                        read_unlock(&in_dev->lock);
                                        in_dev_put(in_dev);
                                        goto done;
                                }
                        }
                        spin_unlock_bh(&imc->lock);
                }
                read_unlock(&in_dev->lock);
                in_dev_put(in_dev);
        }
done:
        read_unlock(&dev_base_lock);

        *start=buffer+(offset-begin);
        len-=(offset-begin);
        if(len>length)
                len=length;
        if(len<0)
                len=0;
        return len;
}

---