ipmr.c

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/*
 *      IP multicast routing support for mrouted 3.6/3.8
 *
 *              (c) 1995 Alan Cox, <alan@redhat.com>
 *        Linux Consultancy and Custom Driver Development
 *
 *      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.
 *
 *      Version: $Id: ipmr.c,v 1.65 2001/10/31 21:55:54 davem Exp $
 *
 *      Fixes:
 *      Michael Chastain        :       Incorrect size of copying.
 *      Alan Cox                :       Added the cache manager code
 *      Alan Cox                :       Fixed the clone/copy bug and device race.
 *      Mike McLagan            :       Routing by source
 *      Malcolm Beattie         :       Buffer handling fixes.
 *      Alexey Kuznetsov        :       Double buffer free and other fixes.
 *      SVR Anand               :       Fixed several multicast bugs and problems.
 *      Alexey Kuznetsov        :       Status, optimisations and more.
 *      Brad Parker             :       Better behaviour on mrouted upcall
 *                                      overflow.
 *      Carlos Picoto           :       PIMv1 Support
 *      Pavlin Ivanov Radoslavov:       PIMv2 Registers must checksum only PIM header
 *                                      Relax this requrement to work with older peers.
 *
 */

#include <linux/config.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/proc_fs.h>
#include <linux/mroute.h>
#include <linux/init.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <linux/notifier.h>
#include <linux/if_arp.h>
#include <linux/netfilter_ipv4.h>
#include <net/ipip.h>
#include <net/checksum.h>

#if defined(CONFIG_IP_PIMSM_V1) || defined(CONFIG_IP_PIMSM_V2)
#define CONFIG_IP_PIMSM 1
#endif

static struct sock *mroute_socket;


/* Big lock, protecting vif table, mrt cache and mroute socket state.
   Note that the changes are semaphored via rtnl_lock.
 */

static rwlock_t mrt_lock = RW_LOCK_UNLOCKED;

/*
 *      Multicast router control variables
 */

static struct vif_device vif_table[MAXVIFS];            /* Devices              */
static int maxvif;

#define VIF_EXISTS(idx) (vif_table[idx].dev != NULL)

int mroute_do_assert;                                   /* Set in PIM assert    */
int mroute_do_pim;

static struct mfc_cache *mfc_cache_array[MFC_LINES];    /* Forwarding cache     */

static struct mfc_cache *mfc_unres_queue;               /* Queue of unresolved entries */
atomic_t cache_resolve_queue_len;                       /* Size of unresolved   */

/* Special spinlock for queue of unresolved entries */
static spinlock_t mfc_unres_lock = SPIN_LOCK_UNLOCKED;

/* We return to original Alan's scheme. Hash table of resolved
   entries is changed only in process context and protected
   with weak lock mrt_lock. Queue of unresolved entries is protected
   with strong spinlock mfc_unres_lock.

   In this case data path is free of exclusive locks at all.
 */

kmem_cache_t *mrt_cachep;

static int ip_mr_forward(struct sk_buff *skb, struct mfc_cache *cache, int local);
static int ipmr_cache_report(struct sk_buff *pkt, vifi_t vifi, int assert);
static int ipmr_fill_mroute(struct sk_buff *skb, struct mfc_cache *c, struct rtmsg *rtm);

extern struct inet_protocol pim_protocol;

static struct timer_list ipmr_expire_timer;

/* Service routines creating virtual interfaces: DVMRP tunnels and PIMREG */

static
struct net_device *ipmr_new_tunnel(struct vifctl *v)
{
        struct net_device  *dev;

        dev = __dev_get_by_name("tunl0");

        if (dev) {
                int err;
                struct ifreq ifr;
                mm_segment_t    oldfs;
                struct ip_tunnel_parm p;
                struct in_device  *in_dev;

                memset(&p, 0, sizeof(p));
                p.iph.daddr = v->vifc_rmt_addr.s_addr;
                p.iph.saddr = v->vifc_lcl_addr.s_addr;
                p.iph.version = 4;
                p.iph.ihl = 5;
                p.iph.protocol = IPPROTO_IPIP;
                sprintf(p.name, "dvmrp%d", v->vifc_vifi);
                ifr.ifr_ifru.ifru_data = (void*)&p;

                oldfs = get_fs(); set_fs(KERNEL_DS);
                err = dev->do_ioctl(dev, &ifr, SIOCADDTUNNEL);
                set_fs(oldfs);

                dev = NULL;

                if (err == 0 && (dev = __dev_get_by_name(p.name)) != NULL) {
                        dev->flags |= IFF_MULTICAST;

                        in_dev = __in_dev_get(dev);
                        if (in_dev == NULL && (in_dev = inetdev_init(dev)) == NULL)
                                goto failure;
                        in_dev->cnf.rp_filter = 0;

                        if (dev_open(dev))
                                goto failure;
                }
        }
        return dev;

failure:
        unregister_netdevice(dev);
        return NULL;
}

#ifdef CONFIG_IP_PIMSM

static int reg_vif_num = -1;

static int reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
{
        read_lock(&mrt_lock);
        ((struct net_device_stats*)dev->priv)->tx_bytes += skb->len;
        ((struct net_device_stats*)dev->priv)->tx_packets++;
        ipmr_cache_report(skb, reg_vif_num, IGMPMSG_WHOLEPKT);
        read_unlock(&mrt_lock);
        kfree_skb(skb);
        return 0;
}

static struct net_device_stats *reg_vif_get_stats(struct net_device *dev)
{
        return (struct net_device_stats*)dev->priv;
}

static
struct net_device *ipmr_reg_vif(struct vifctl *v)
{
        struct net_device  *dev;
        struct in_device *in_dev;
        int size;

        size = sizeof(*dev) + sizeof(struct net_device_stats);
        dev = kmalloc(size, GFP_KERNEL);
        if (!dev)
                return NULL;

        memset(dev, 0, size);

        dev->priv = dev + 1;

        strcpy(dev->name, "pimreg");

        dev->type               = ARPHRD_PIMREG;
        dev->mtu                = 1500 - sizeof(struct iphdr) - 8;
        dev->flags              = IFF_NOARP;
        dev->hard_start_xmit    = reg_vif_xmit;
        dev->get_stats          = reg_vif_get_stats;
        dev->features           |= NETIF_F_DYNALLOC;

        if (register_netdevice(dev)) {
                kfree(dev);
                return NULL;
        }
        dev->iflink = 0;

        if ((in_dev = inetdev_init(dev)) == NULL)
                goto failure;

        in_dev->cnf.rp_filter = 0;

        if (dev_open(dev))
                goto failure;

        return dev;

failure:
        unregister_netdevice(dev);
        return NULL;
}
#endif

/*
 *      Delete a VIF entry
 */
 
static int vif_delete(int vifi)
{
        struct vif_device *v;
        struct net_device *dev;
        struct in_device *in_dev;

        if (vifi < 0 || vifi >= maxvif)
                return -EADDRNOTAVAIL;

        v = &vif_table[vifi];

        write_lock_bh(&mrt_lock);
        dev = v->dev;
        v->dev = NULL;

        if (!dev) {
                write_unlock_bh(&mrt_lock);
                return -EADDRNOTAVAIL;
        }

#ifdef CONFIG_IP_PIMSM
        if (vifi == reg_vif_num)
                reg_vif_num = -1;
#endif

        if (vifi+1 == maxvif) {
                int tmp;
                for (tmp=vifi-1; tmp>=0; tmp--) {
                        if (VIF_EXISTS(tmp))
                                break;
                }
                maxvif = tmp+1;
        }

        write_unlock_bh(&mrt_lock);

        dev_set_allmulti(dev, -1);

        if ((in_dev = __in_dev_get(dev)) != NULL) {
                in_dev->cnf.mc_forwarding--;
                ip_rt_multicast_event(in_dev);
        }

        if (v->flags&(VIFF_TUNNEL|VIFF_REGISTER))
                unregister_netdevice(dev);

        dev_put(dev);
        return 0;
}

/* Destroy an unresolved cache entry, killing queued skbs
   and reporting error to netlink readers.
 */

static void ipmr_destroy_unres(struct mfc_cache *c)
{
        struct sk_buff *skb;

        atomic_dec(&cache_resolve_queue_len);

        while((skb=skb_dequeue(&c->mfc_un.unres.unresolved))) {
                if (skb->nh.iph->version == 0) {
                        struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct iphdr));
                        nlh->nlmsg_type = NLMSG_ERROR;
                        nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nlmsgerr));
                        skb_trim(skb, nlh->nlmsg_len);
                        ((struct nlmsgerr*)NLMSG_DATA(nlh))->error = -ETIMEDOUT;
                        netlink_unicast(rtnl, skb, NETLINK_CB(skb).dst_pid, MSG_DONTWAIT);
                } else
                        kfree_skb(skb);
        }

        kmem_cache_free(mrt_cachep, c);
}


/* Single timer process for all the unresolved queue. */

void ipmr_expire_process(unsigned long dummy)
{
        unsigned long now;
        unsigned long expires;
        struct mfc_cache *c, **cp;

        if (!spin_trylock(&mfc_unres_lock)) {
                mod_timer(&ipmr_expire_timer, jiffies+HZ/10);
                return;
        }

        if (atomic_read(&cache_resolve_queue_len) == 0)
                goto out;

        now = jiffies;
        expires = 10*HZ;
        cp = &mfc_unres_queue;

        while ((c=*cp) != NULL) {
                long interval = c->mfc_un.unres.expires - now;

                if (interval > 0) {
                        if (interval < expires)
                                expires = interval;
                        cp = &c->next;
                        continue;
                }

                *cp = c->next;

                ipmr_destroy_unres(c);
        }

        if (atomic_read(&cache_resolve_queue_len))
                mod_timer(&ipmr_expire_timer, jiffies + expires);

out:
        spin_unlock(&mfc_unres_lock);
}

/* Fill oifs list. It is called under write locked mrt_lock. */

static void ipmr_update_threshoulds(struct mfc_cache *cache, unsigned char *ttls)
{
        int vifi;

        cache->mfc_un.res.minvif = MAXVIFS;
        cache->mfc_un.res.maxvif = 0;
        memset(cache->mfc_un.res.ttls, 255, MAXVIFS);

        for (vifi=0; vifi<maxvif; vifi++) {
                if (VIF_EXISTS(vifi) && ttls[vifi] && ttls[vifi] < 255) {
                        cache->mfc_un.res.ttls[vifi] = ttls[vifi];
                        if (cache->mfc_un.res.minvif > vifi)
                                cache->mfc_un.res.minvif = vifi;
                        if (cache->mfc_un.res.maxvif <= vifi)
                                cache->mfc_un.res.maxvif = vifi + 1;
                }
        }
}

static int vif_add(struct vifctl *vifc, int mrtsock)
{
        int vifi = vifc->vifc_vifi;
        struct vif_device *v = &vif_table[vifi];
        struct net_device *dev;
        struct in_device *in_dev;

        /* Is vif busy ? */
        if (VIF_EXISTS(vifi))
                return -EADDRINUSE;

        switch (vifc->vifc_flags) {
#ifdef CONFIG_IP_PIMSM
        case VIFF_REGISTER:
                /*
                 * Special Purpose VIF in PIM
                 * All the packets will be sent to the daemon
                 */
                if (reg_vif_num >= 0)
                        return -EADDRINUSE;
                dev = ipmr_reg_vif(vifc);
                if (!dev)
                        return -ENOBUFS;
                break;
#endif
        case VIFF_TUNNEL:       
                dev = ipmr_new_tunnel(vifc);
                if (!dev)
                        return -ENOBUFS;
                break;
        case 0:
                dev=ip_dev_find(vifc->vifc_lcl_addr.s_addr);
                if (!dev)
                        return -EADDRNOTAVAIL;
                __dev_put(dev);
                break;
        default:
                return -EINVAL;
        }

        if ((in_dev = __in_dev_get(dev)) == NULL)
                return -EADDRNOTAVAIL;
        in_dev->cnf.mc_forwarding++;
        dev_set_allmulti(dev, +1);
        ip_rt_multicast_event(in_dev);

        /*
         *      Fill in the VIF structures
         */
        v->rate_limit=vifc->vifc_rate_limit;
        v->local=vifc->vifc_lcl_addr.s_addr;
        v->remote=vifc->vifc_rmt_addr.s_addr;
        v->flags=vifc->vifc_flags;
        if (!mrtsock)
                v->flags |= VIFF_STATIC;
        v->threshold=vifc->vifc_threshold;
        v->bytes_in = 0;
        v->bytes_out = 0;
        v->pkt_in = 0;
        v->pkt_out = 0;
        v->link = dev->ifindex;
        if (v->flags&(VIFF_TUNNEL|VIFF_REGISTER))
                v->link = dev->iflink;

        /* And finish update writing critical data */
        write_lock_bh(&mrt_lock);
        dev_hold(dev);
        v->dev=dev;
#ifdef CONFIG_IP_PIMSM
        if (v->flags&VIFF_REGISTER)
                reg_vif_num = vifi;
#endif
        if (vifi+1 > maxvif)
                maxvif = vifi+1;
        write_unlock_bh(&mrt_lock);
        return 0;
}

static struct mfc_cache *ipmr_cache_find(__u32 origin, __u32 mcastgrp)
{
        int line=MFC_HASH(mcastgrp,origin);
        struct mfc_cache *c;

        for (c=mfc_cache_array[line]; c; c = c->next) {
                if (c->mfc_origin==origin && c->mfc_mcastgrp==mcastgrp)
                        break;
        }
        return c;
}

/*
 *      Allocate a multicast cache entry
 */
static struct mfc_cache *ipmr_cache_alloc(void)
{
        struct mfc_cache *c=kmem_cache_alloc(mrt_cachep, GFP_KERNEL);
        if(c==NULL)
                return NULL;
        memset(c, 0, sizeof(*c));
        c->mfc_un.res.minvif = MAXVIFS;
        return c;
}

static struct mfc_cache *ipmr_cache_alloc_unres(void)
{
        struct mfc_cache *c=kmem_cache_alloc(mrt_cachep, GFP_ATOMIC);
        if(c==NULL)
                return NULL;
        memset(c, 0, sizeof(*c));
        skb_queue_head_init(&c->mfc_un.unres.unresolved);
        c->mfc_un.unres.expires = jiffies + 10*HZ;
        return c;
}

/*
 *      A cache entry has gone into a resolved state from queued
 */
 
static void ipmr_cache_resolve(struct mfc_cache *uc, struct mfc_cache *c)
{
        struct sk_buff *skb;

        /*
         *      Play the pending entries through our router
         */

        while((skb=__skb_dequeue(&uc->mfc_un.unres.unresolved))) {
                if (skb->nh.iph->version == 0) {
                        int err;
                        struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct iphdr));

                        if (ipmr_fill_mroute(skb, c, NLMSG_DATA(nlh)) > 0) {
                                nlh->nlmsg_len = skb->tail - (u8*)nlh;
                        } else {
                                nlh->nlmsg_type = NLMSG_ERROR;
                                nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nlmsgerr));
                                skb_trim(skb, nlh->nlmsg_len);
                                ((struct nlmsgerr*)NLMSG_DATA(nlh))->error = -EMSGSIZE;
                        }
                        err = netlink_unicast(rtnl, skb, NETLINK_CB(skb).dst_pid, MSG_DONTWAIT);
                } else
                        ip_mr_forward(skb, c, 0);
        }
}

/*
 *      Bounce a cache query up to mrouted. We could use netlink for this but mrouted
 *      expects the following bizarre scheme.
 *
 *      Called under mrt_lock.
 */
 
static int ipmr_cache_report(struct sk_buff *pkt, vifi_t vifi, int assert)
{
        struct sk_buff *skb;
        int ihl = pkt->nh.iph->ihl<<2;
        struct igmphdr *igmp;
        struct igmpmsg *msg;
        int ret;

#ifdef CONFIG_IP_PIMSM
        if (assert == IGMPMSG_WHOLEPKT)
                skb = skb_realloc_headroom(pkt, sizeof(struct iphdr));
        else
#endif
                skb = alloc_skb(128, GFP_ATOMIC);

        if(!skb)
                return -ENOBUFS;

#ifdef CONFIG_IP_PIMSM
        if (assert == IGMPMSG_WHOLEPKT) {
                /* Ugly, but we have no choice with this interface.
                   Duplicate old header, fix ihl, length etc.
                   And all this only to mangle msg->im_msgtype and
                   to set msg->im_mbz to "mbz" :-)
                 */
                msg = (struct igmpmsg*)skb_push(skb, sizeof(struct iphdr));
                skb->nh.raw = skb->h.raw = (u8*)msg;
                memcpy(msg, pkt->nh.raw, sizeof(struct iphdr));
                msg->im_msgtype = IGMPMSG_WHOLEPKT;
                msg->im_mbz = 0;
                msg->im_vif = reg_vif_num;
                skb->nh.iph->ihl = sizeof(struct iphdr) >> 2;
                skb->nh.iph->tot_len = htons(ntohs(pkt->nh.iph->tot_len) + sizeof(struct iphdr));
        } else 
#endif
        {       
                
        /*
         *      Copy the IP header
         */

        skb->nh.iph = (struct iphdr *)skb_put(skb, ihl);
        memcpy(skb->data,pkt->data,ihl);
        skb->nh.iph->protocol = 0;                      /* Flag to the kernel this is a route add */
        msg = (struct igmpmsg*)skb->nh.iph;
        msg->im_vif = vifi;
        skb->dst = dst_clone(pkt->dst);

        /*
         *      Add our header
         */

        igmp=(struct igmphdr *)skb_put(skb,sizeof(struct igmphdr));
        igmp->type      =
        msg->im_msgtype = assert;
        igmp->code      =       0;
        skb->nh.iph->tot_len=htons(skb->len);                   /* Fix the length */
        skb->h.raw = skb->nh.raw;
        }

        if (mroute_socket == NULL) {
                kfree_skb(skb);
                return -EINVAL;
        }

        /*
         *      Deliver to mrouted
         */
        if ((ret=sock_queue_rcv_skb(mroute_socket,skb))<0) {
                if (net_ratelimit())
                        printk(KERN_WARNING "mroute: pending queue full, dropping entries.\n");
                kfree_skb(skb);
        }

        return ret;
}

/*
 *      Queue a packet for resolution. It gets locked cache entry!
 */
 
static int
ipmr_cache_unresolved(vifi_t vifi, struct sk_buff *skb)
{
        int err;
        struct mfc_cache *c;

        spin_lock_bh(&mfc_unres_lock);
        for (c=mfc_unres_queue; c; c=c->next) {
                if (c->mfc_mcastgrp == skb->nh.iph->daddr &&
                    c->mfc_origin == skb->nh.iph->saddr)
                        break;
        }

        if (c == NULL) {
                /*
                 *      Create a new entry if allowable
                 */

                if (atomic_read(&cache_resolve_queue_len)>=10 ||
                    (c=ipmr_cache_alloc_unres())==NULL) {
                        spin_unlock_bh(&mfc_unres_lock);

                        kfree_skb(skb);
                        return -ENOBUFS;
                }

                /*
                 *      Fill in the new cache entry
                 */
                c->mfc_parent=-1;
                c->mfc_origin=skb->nh.iph->saddr;
                c->mfc_mcastgrp=skb->nh.iph->daddr;

                /*
                 *      Reflect first query at mrouted.
                 */
                if ((err = ipmr_cache_report(skb, vifi, IGMPMSG_NOCACHE))<0) {
                        /* If the report failed throw the cache entry 
                           out - Brad Parker
                         */
                        spin_unlock_bh(&mfc_unres_lock);

                        kmem_cache_free(mrt_cachep, c);
                        kfree_skb(skb);
                        return err;
                }

                atomic_inc(&cache_resolve_queue_len);
                c->next = mfc_unres_queue;
                mfc_unres_queue = c;

                mod_timer(&ipmr_expire_timer, c->mfc_un.unres.expires);
        }

        /*
         *      See if we can append the packet
         */
        if (c->mfc_un.unres.unresolved.qlen>3) {
                kfree_skb(skb);
                err = -ENOBUFS;
        } else {
                skb_queue_tail(&c->mfc_un.unres.unresolved,skb);
                err = 0;
        }

        spin_unlock_bh(&mfc_unres_lock);
        return err;
}

/*
 *      MFC cache manipulation by user space mroute daemon
 */

int ipmr_mfc_delete(struct mfcctl *mfc)
{
        int line;
        struct mfc_cache *c, **cp;

        line=MFC_HASH(mfc->mfcc_mcastgrp.s_addr, mfc->mfcc_origin.s_addr);

        for (cp=&mfc_cache_array[line]; (c=*cp) != NULL; cp = &c->next) {
                if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
                    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
                        write_lock_bh(&mrt_lock);
                        *cp = c->next;
                        write_unlock_bh(&mrt_lock);

                        kmem_cache_free(mrt_cachep, c);
                        return 0;
                }
        }
        return -ENOENT;
}

int ipmr_mfc_add(struct mfcctl *mfc, int mrtsock)
{
        int line;
        struct mfc_cache *uc, *c, **cp;

        line=MFC_HASH(mfc->mfcc_mcastgrp.s_addr, mfc->mfcc_origin.s_addr);

        for (cp=&mfc_cache_array[line]; (c=*cp) != NULL; cp = &c->next) {
                if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
                    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr)
                        break;
        }

        if (c != NULL) {
                write_lock_bh(&mrt_lock);
                c->mfc_parent = mfc->mfcc_parent;
                ipmr_update_threshoulds(c, mfc->mfcc_ttls);
                if (!mrtsock)
                        c->mfc_flags |= MFC_STATIC;
                write_unlock_bh(&mrt_lock);
                return 0;
        }

        if(!MULTICAST(mfc->mfcc_mcastgrp.s_addr))
                return -EINVAL;

        c=ipmr_cache_alloc();
        if (c==NULL)
                return -ENOMEM;

        c->mfc_origin=mfc->mfcc_origin.s_addr;
        c->mfc_mcastgrp=mfc->mfcc_mcastgrp.s_addr;
        c->mfc_parent=mfc->mfcc_parent;
        ipmr_update_threshoulds(c, mfc->mfcc_ttls);
        if (!mrtsock)
                c->mfc_flags |= MFC_STATIC;

        write_lock_bh(&mrt_lock);
        c->next = mfc_cache_array[line];
        mfc_cache_array[line] = c;
        write_unlock_bh(&mrt_lock);

        /*
         *      Check to see if we resolved a queued list. If so we
         *      need to send on the frames and tidy up.
         */
        spin_lock_bh(&mfc_unres_lock);
        for (cp = &mfc_unres_queue; (uc=*cp) != NULL;
             cp = &uc->next) {
                if (uc->mfc_origin == c->mfc_origin &&
                    uc->mfc_mcastgrp == c->mfc_mcastgrp) {
                        *cp = uc->next;
                        if (atomic_dec_and_test(&cache_resolve_queue_len))
                                del_timer(&ipmr_expire_timer);
                        break;
                }
        }
        spin_unlock_bh(&mfc_unres_lock);

        if (uc) {
                ipmr_cache_resolve(uc, c);
                kmem_cache_free(mrt_cachep, uc);
        }
        return 0;
}

/*
 *      Close the multicast socket, and clear the vif tables etc
 */
 
static void mroute_clean_tables(struct sock *sk)
{
        int i;
                
        /*
         *      Shut down all active vif entries
         */
        for(i=0; i<maxvif; i++) {
                if (!(vif_table[i].flags&VIFF_STATIC))
                        vif_delete(i);
        }

        /*
         *      Wipe the cache
         */
        for (i=0;i<MFC_LINES;i++) {
                struct mfc_cache *c, **cp;

                cp = &mfc_cache_array[i];
                while ((c = *cp) != NULL) {
                        if (c->mfc_flags&MFC_STATIC) {
                                cp = &c->next;
                                continue;
                        }
                        write_lock_bh(&mrt_lock);
                        *cp = c->next;
                        write_unlock_bh(&mrt_lock);

                        kmem_cache_free(mrt_cachep, c);
                }
        }

        if (atomic_read(&cache_resolve_queue_len) != 0) {
                struct mfc_cache *c;

                spin_lock_bh(&mfc_unres_lock);
                while (mfc_unres_queue != NULL) {
                        c = mfc_unres_queue;
                        mfc_unres_queue = c->next;
                        spin_unlock_bh(&mfc_unres_lock);

                        ipmr_destroy_unres(c);

                        spin_lock_bh(&mfc_unres_lock);
                }
                spin_unlock_bh(&mfc_unres_lock);
        }
}

static void mrtsock_destruct(struct sock *sk)
{
        rtnl_lock();
        if (sk == mroute_socket) {
                ipv4_devconf.mc_forwarding--;

                write_lock_bh(&mrt_lock);
                mroute_socket=NULL;
                write_unlock_bh(&mrt_lock);

                mroute_clean_tables(sk);
        }
        rtnl_unlock();
}

/*
 *      Socket options and virtual interface manipulation. The whole
 *      virtual interface system is a complete heap, but unfortunately
 *      that's how BSD mrouted happens to think. Maybe one day with a proper
 *      MOSPF/PIM router set up we can clean this up.
 */
 
int ip_mroute_setsockopt(struct sock *sk,int optname,char *optval,int optlen)
{
        int ret;
        struct vifctl vif;
        struct mfcctl mfc;
        
        if(optname!=MRT_INIT)
        {
                if(sk!=mroute_socket && !capable(CAP_NET_ADMIN))
                        return -EACCES;
        }

        switch(optname)
        {
                case MRT_INIT:
                        if(sk->type!=SOCK_RAW || sk->num!=IPPROTO_IGMP)
                                return -EOPNOTSUPP;
                        if(optlen!=sizeof(int))
                                return -ENOPROTOOPT;

                        rtnl_lock();
                        if (mroute_socket) {
                                rtnl_unlock();
                                return -EADDRINUSE;
                        }

                        ret = ip_ra_control(sk, 1, mrtsock_destruct);
                        if (ret == 0) {
                                write_lock_bh(&mrt_lock);
                                mroute_socket=sk;
                                write_unlock_bh(&mrt_lock);

                                ipv4_devconf.mc_forwarding++;
                        }
                        rtnl_unlock();
                        return ret;
                case MRT_DONE:
                        if (sk!=mroute_socket)
                                return -EACCES;
                        return ip_ra_control(sk, 0, NULL);
                case MRT_ADD_VIF:
                case MRT_DEL_VIF:
                        if(optlen!=sizeof(vif))
                                return -EINVAL;
                        if (copy_from_user(&vif,optval,sizeof(vif)))
                                return -EFAULT; 
                        if(vif.vifc_vifi >= MAXVIFS)
                                return -ENFILE;
                        rtnl_lock();
                        if (optname==MRT_ADD_VIF) {
                                ret = vif_add(&vif, sk==mroute_socket);
                        } else {
                                ret = vif_delete(vif.vifc_vifi);
                        }
                        rtnl_unlock();
                        return ret;

                /*
                 *      Manipulate the forwarding caches. These live
                 *      in a sort of kernel/user symbiosis.
                 */
                case MRT_ADD_MFC:
                case MRT_DEL_MFC:
                        if(optlen!=sizeof(mfc))
                                return -EINVAL;
                        if (copy_from_user(&mfc,optval, sizeof(mfc)))
                                return -EFAULT;
                        rtnl_lock();
                        if (optname==MRT_DEL_MFC)
                                ret = ipmr_mfc_delete(&mfc);
                        else
                                ret = ipmr_mfc_add(&mfc, sk==mroute_socket);
                        rtnl_unlock();
                        return ret;
                /*
                 *      Control PIM assert.
                 */
                case MRT_ASSERT:
                {
                        int v;
                        if(get_user(v,(int *)optval))
                                return -EFAULT;
                        mroute_do_assert=(v)?1:0;
                        return 0;
                }
#ifdef CONFIG_IP_PIMSM
                case MRT_PIM:
                {
                        int v;
                        if(get_user(v,(int *)optval))
                                return -EFAULT;
                        v = (v)?1:0;
                        rtnl_lock();
                        if (v != mroute_do_pim) {
                                mroute_do_pim = v;
                                mroute_do_assert = v;
#ifdef CONFIG_IP_PIMSM_V2
                                if (mroute_do_pim)
                                        inet_add_protocol(&pim_protocol);
                                else
                                        inet_del_protocol(&pim_protocol);
#endif
                        }
                        rtnl_unlock();
                        return 0;
                }
#endif
                /*
                 *      Spurious command, or MRT_VERSION which you cannot
                 *      set.
                 */
                default:
                        return -ENOPROTOOPT;
        }
}

/*
 *      Getsock opt support for the multicast routing system.
 */
 
int ip_mroute_getsockopt(struct sock *sk,int optname,char *optval,int *optlen)
{
        int olr;
        int val;

        if(optname!=MRT_VERSION && 
#ifdef CONFIG_IP_PIMSM
           optname!=MRT_PIM &&
#endif
           optname!=MRT_ASSERT)
                return -ENOPROTOOPT;

        if (get_user(olr, optlen))
                return -EFAULT;

        olr = min_t(unsigned int, olr, sizeof(int));
        if (olr < 0)
                return -EINVAL;
                
        if(put_user(olr,optlen))
                return -EFAULT;
        if(optname==MRT_VERSION)
                val=0x0305;
#ifdef CONFIG_IP_PIMSM
        else if(optname==MRT_PIM)
                val=mroute_do_pim;
#endif
        else
                val=mroute_do_assert;
        if(copy_to_user(optval,&val,olr))
                return -EFAULT;
        return 0;
}

/*
 *      The IP multicast ioctl support routines.
 */
 
int ipmr_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
        struct sioc_sg_req sr;
        struct sioc_vif_req vr;
        struct vif_device *vif;
        struct mfc_cache *c;
        
        switch(cmd)
        {
                case SIOCGETVIFCNT:
                        if (copy_from_user(&vr,(void *)arg,sizeof(vr)))
                                return -EFAULT; 
                        if(vr.vifi>=maxvif)
                                return -EINVAL;
                        read_lock(&mrt_lock);
                        vif=&vif_table[vr.vifi];
                        if(VIF_EXISTS(vr.vifi)) {
                                vr.icount=vif->pkt_in;
                                vr.ocount=vif->pkt_out;
                                vr.ibytes=vif->bytes_in;
                                vr.obytes=vif->bytes_out;
                                read_unlock(&mrt_lock);

                                if (copy_to_user((void *)arg,&vr,sizeof(vr)))
                                        return -EFAULT;
                                return 0;
                        }
                        read_unlock(&mrt_lock);
                        return -EADDRNOTAVAIL;
                case SIOCGETSGCNT:
                        if (copy_from_user(&sr,(void *)arg,sizeof(sr)))
                                return -EFAULT;

                        read_lock(&mrt_lock);
                        c = ipmr_cache_find(sr.src.s_addr, sr.grp.s_addr);
                        if (c) {
                                sr.pktcnt = c->mfc_un.res.pkt;
                                sr.bytecnt = c->mfc_un.res.bytes;
                                sr.wrong_if = c->mfc_un.res.wrong_if;
                                read_unlock(&mrt_lock);

                                if (copy_to_user((void *)arg,&sr,sizeof(sr)))
                                        return -EFAULT;
                                return 0;
                        }
                        read_unlock(&mrt_lock);
                        return -EADDRNOTAVAIL;
                default:
                        return -ENOIOCTLCMD;
        }
}


static int ipmr_device_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct vif_device *v;
        int ct;
        if (event != NETDEV_UNREGISTER)
                return NOTIFY_DONE;
        v=&vif_table[0];
        for(ct=0;ct<maxvif;ct++,v++) {
                if (v->dev==ptr)
                        vif_delete(ct);
        }
        return NOTIFY_DONE;
}


static struct notifier_block ip_mr_notifier={
        ipmr_device_event,
        NULL,
        0
};

/*
 *      Encapsulate a packet by attaching a valid IPIP header to it.
 *      This avoids tunnel drivers and other mess and gives us the speed so
 *      important for multicast video.
 */
 
static void ip_encap(struct sk_buff *skb, u32 saddr, u32 daddr)
{
        struct iphdr *iph = (struct iphdr *)skb_push(skb,sizeof(struct iphdr));

        iph->version    =       4;
        iph->tos        =       skb->nh.iph->tos;
        iph->ttl        =       skb->nh.iph->ttl;
        iph->frag_off   =       0;
        iph->daddr      =       daddr;
        iph->saddr      =       saddr;
        iph->protocol   =       IPPROTO_IPIP;
        iph->ihl        =       5;
        iph->tot_len    =       htons(skb->len);
        ip_select_ident(iph, skb->dst, NULL);
        ip_send_check(iph);

        skb->h.ipiph = skb->nh.iph;
        skb->nh.iph = iph;
        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
#ifdef CONFIG_NETFILTER
        nf_conntrack_put(skb->nfct);
        skb->nfct = NULL;
#endif
}

static inline int ipmr_forward_finish(struct sk_buff *skb)
{
        struct ip_options *opt = &(IPCB(skb)->opt);
        struct dst_entry *dst = skb->dst;

        if (unlikely(opt->optlen))
                ip_forward_options(skb);

        if (skb->len <= dst->pmtu)
                return dst->output(skb);
        else
                return ip_fragment(skb, dst->output);
}

/*
 *      Processing handlers for ipmr_forward
 */

static void ipmr_queue_xmit(struct sk_buff *skb, struct mfc_cache *c,
                           int vifi, int last)
{
        struct iphdr *iph = skb->nh.iph;
        struct vif_device *vif = &vif_table[vifi];
        struct net_device *dev;
        struct rtable *rt;
        int    encap = 0;
        struct sk_buff *skb2;

        if (vif->dev == NULL)
                return;

#ifdef CONFIG_IP_PIMSM
        if (vif->flags & VIFF_REGISTER) {
                vif->pkt_out++;
                vif->bytes_out+=skb->len;
                ((struct net_device_stats*)vif->dev->priv)->tx_bytes += skb->len;
                ((struct net_device_stats*)vif->dev->priv)->tx_packets++;
                ipmr_cache_report(skb, vifi, IGMPMSG_WHOLEPKT);
                return;
        }
#endif

        if (vif->flags&VIFF_TUNNEL) {
                if (ip_route_output(&rt, vif->remote, vif->local, RT_TOS(iph->tos), vif->link))
                        return;
                encap = sizeof(struct iphdr);
        } else {
                if (ip_route_output(&rt, iph->daddr, 0, RT_TOS(iph->tos), vif->link))
                        return;
        }

        dev = rt->u.dst.dev;

        if (skb->len+encap > rt->u.dst.pmtu && (ntohs(iph->frag_off) & IP_DF)) {
                /* Do not fragment multicasts. Alas, IPv4 does not
                   allow to send ICMP, so that packets will disappear
                   to blackhole.
                 */

                IP_INC_STATS_BH(IpFragFails);
                ip_rt_put(rt);
                return;
        }

        encap += dev->hard_header_len;

        if (skb_headroom(skb) < encap || skb_cloned(skb) || !last)
                skb2 = skb_realloc_headroom(skb, (encap + 15)&~15);
        else if (atomic_read(&skb->users) != 1)
                skb2 = skb_clone(skb, GFP_ATOMIC);
        else {
                atomic_inc(&skb->users);
                skb2 = skb;
        }

        if (skb2 == NULL) {
                ip_rt_put(rt);
                return;
        }

        vif->pkt_out++;
        vif->bytes_out+=skb->len;

        dst_release(skb2->dst);
        skb2->dst = &rt->u.dst;
        iph = skb2->nh.iph;
        ip_decrease_ttl(iph);

        /* FIXME: forward and output firewalls used to be called here.
         * What do we do with netfilter? -- RR */
        if (vif->flags & VIFF_TUNNEL) {
                ip_encap(skb2, vif->local, vif->remote);
                /* FIXME: extra output firewall step used to be here. --RR */
                ((struct ip_tunnel *)vif->dev->priv)->stat.tx_packets++;
                ((struct ip_tunnel *)vif->dev->priv)->stat.tx_bytes+=skb2->len;
        }

        IPCB(skb2)->flags |= IPSKB_FORWARDED;

        /*
         * RFC1584 teaches, that DVMRP/PIM router must deliver packets locally
         * not only before forwarding, but after forwarding on all output
         * interfaces. It is clear, if mrouter runs a multicasting
         * program, it should receive packets not depending to what interface
         * program is joined.
         * If we will not make it, the program will have to join on all
         * interfaces. On the other hand, multihoming host (or router, but
         * not mrouter) cannot join to more than one interface - it will
         * result in receiving multiple packets.
         */
        NF_HOOK(PF_INET, NF_IP_FORWARD, skb2, skb->dev, dev, 
                ipmr_forward_finish);
}

int ipmr_find_vif(struct net_device *dev)
{
        int ct;
        for (ct=maxvif-1; ct>=0; ct--) {
                if (vif_table[ct].dev == dev)
                        break;
        }
        return ct;
}

/* "local" means that we should preserve one skb (for local delivery) */

int ip_mr_forward(struct sk_buff *skb, struct mfc_cache *cache, int local)
{
        int psend = -1;
        int vif, ct;

        vif = cache->mfc_parent;
        cache->mfc_un.res.pkt++;
        cache->mfc_un.res.bytes += skb->len;

        /*
         * Wrong interface: drop packet and (maybe) send PIM assert.
         */
        if (vif_table[vif].dev != skb->dev) {
                int true_vifi;

                if (((struct rtable*)skb->dst)->key.iif == 0) {
                        /* It is our own packet, looped back.
                           Very complicated situation...

                           The best workaround until routing daemons will be
                           fixed is not to redistribute packet, if it was
                           send through wrong interface. It means, that
                           multicast applications WILL NOT work for
                           (S,G), which have default multicast route pointing
                           to wrong oif. In any case, it is not a good
                           idea to use multicasting applications on router.
                         */
                        goto dont_forward;
                }

                cache->mfc_un.res.wrong_if++;
                true_vifi = ipmr_find_vif(skb->dev);

                if (true_vifi >= 0 && mroute_do_assert &&
                    /* pimsm uses asserts, when switching from RPT to SPT,
                       so that we cannot check that packet arrived on an oif.
                       It is bad, but otherwise we would need to move pretty
                       large chunk of pimd to kernel. Ough... --ANK
                     */
                    (mroute_do_pim || cache->mfc_un.res.ttls[true_vifi] < 255) &&
                    jiffies - cache->mfc_un.res.last_assert > MFC_ASSERT_THRESH) {
                        cache->mfc_un.res.last_assert = jiffies;
                        ipmr_cache_report(skb, true_vifi, IGMPMSG_WRONGVIF);
                }
                goto dont_forward;
        }

        vif_table[vif].pkt_in++;
        vif_table[vif].bytes_in+=skb->len;

        /*
         *      Forward the frame
         */
        for (ct = cache->mfc_un.res.maxvif-1; ct >= cache->mfc_un.res.minvif; ct--) {
                if (skb->nh.iph->ttl > cache->mfc_un.res.ttls[ct]) {
                        if (psend != -1)
                                ipmr_queue_xmit(skb, cache, psend, 0);
                        psend=ct;
                }
        }
        if (psend != -1)
                ipmr_queue_xmit(skb, cache, psend, !local);

dont_forward:
        if (!local)
                kfree_skb(skb);
        return 0;
}


/*
 *      Multicast packets for forwarding arrive here
 */

int ip_mr_input(struct sk_buff *skb)
{
        struct mfc_cache *cache;
        int local = ((struct rtable*)skb->dst)->rt_flags&RTCF_LOCAL;

        /* Packet is looped back after forward, it should not be
           forwarded second time, but still can be delivered locally.
         */
        if (IPCB(skb)->flags&IPSKB_FORWARDED)
                goto dont_forward;

        if (!local) {
                    if (IPCB(skb)->opt.router_alert) {
                            if (ip_call_ra_chain(skb))
                                    return 0;
                    } else if (skb->nh.iph->protocol == IPPROTO_IGMP){
                            /* IGMPv1 (and broken IGMPv2 implementations sort of
                               Cisco IOS <= 11.2(8)) do not put router alert
                               option to IGMP packets destined to routable
                               groups. It is very bad, because it means
                               that we can forward NO IGMP messages.
                             */
                            read_lock(&mrt_lock);
                            if (mroute_socket) {
                                    raw_rcv(mroute_socket, skb);
                                    read_unlock(&mrt_lock);
                                    return 0;
                            }
                            read_unlock(&mrt_lock);
                    }
        }

        read_lock(&mrt_lock);
        cache = ipmr_cache_find(skb->nh.iph->saddr, skb->nh.iph->daddr);

        /*
         *      No usable cache entry
         */
        if (cache==NULL) {
                int vif;

                if (local) {
                        struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
                        ip_local_deliver(skb);
                        if (skb2 == NULL) {
                                read_unlock(&mrt_lock);
                                return -ENOBUFS;
                        }
                        skb = skb2;
                }

                vif = ipmr_find_vif(skb->dev);
                if (vif >= 0) {
                        int err = ipmr_cache_unresolved(vif, skb);
                        read_unlock(&mrt_lock);

                        return err;
                }
                read_unlock(&mrt_lock);
                kfree_skb(skb);
                return -ENODEV;
        }

        ip_mr_forward(skb, cache, local);

        read_unlock(&mrt_lock);

        if (local)
                return ip_local_deliver(skb);

        return 0;

dont_forward:
        if (local)
                return ip_local_deliver(skb);
        kfree_skb(skb);
        return 0;
}

#ifdef CONFIG_IP_PIMSM_V1
/*
 * Handle IGMP messages of PIMv1
 */

int pim_rcv_v1(struct sk_buff * skb)
{
        struct igmphdr *pim = (struct igmphdr*)skb->h.raw;
        struct iphdr   *encap;
        struct net_device  *reg_dev = NULL;

        if (skb_is_nonlinear(skb)) {
                if (skb_linearize(skb, GFP_ATOMIC) != 0) {
                        kfree_skb(skb);
                        return -ENOMEM;
                }
                pim = (struct igmphdr*)skb->h.raw;
        }

        if (!mroute_do_pim ||
            skb->len < sizeof(*pim) + sizeof(*encap) ||
            pim->group != PIM_V1_VERSION || pim->code != PIM_V1_REGISTER) {
                kfree_skb(skb);
                return -EINVAL;
        }

        encap = (struct iphdr*)(skb->h.raw + sizeof(struct igmphdr));
        /*
           Check that:
           a. packet is really destinted to a multicast group
           b. packet is not a NULL-REGISTER
           c. packet is not truncated
         */
        if (!MULTICAST(encap->daddr) ||
            ntohs(encap->tot_len) == 0 ||
            ntohs(encap->tot_len) + sizeof(*pim) > skb->len) {
                kfree_skb(skb);
                return -EINVAL;
        }

        read_lock(&mrt_lock);
        if (reg_vif_num >= 0)
                reg_dev = vif_table[reg_vif_num].dev;
        if (reg_dev)
                dev_hold(reg_dev);
        read_unlock(&mrt_lock);

        if (reg_dev == NULL) {
                kfree_skb(skb);
                return -EINVAL;
        }

        skb->mac.raw = skb->nh.raw;
        skb_pull(skb, (u8*)encap - skb->data);
        skb->nh.iph = (struct iphdr *)skb->data;
        skb->dev = reg_dev;
        memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
        skb->protocol = htons(ETH_P_IP);
        skb->ip_summed = 0;
        skb->pkt_type = PACKET_HOST;
        dst_release(skb->dst);
        skb->dst = NULL;
        ((struct net_device_stats*)reg_dev->priv)->rx_bytes += skb->len;
        ((struct net_device_stats*)reg_dev->priv)->rx_packets++;
#ifdef CONFIG_NETFILTER
        nf_conntrack_put(skb->nfct);
        skb->nfct = NULL;
#endif
        netif_rx(skb);
        dev_put(reg_dev);
        return 0;
}
#endif

#ifdef CONFIG_IP_PIMSM_V2
int pim_rcv(struct sk_buff * skb)
{
        struct pimreghdr *pim = (struct pimreghdr*)skb->h.raw;
        struct iphdr   *encap;
        struct net_device  *reg_dev = NULL;

        if (skb_is_nonlinear(skb)) {
                if (skb_linearize(skb, GFP_ATOMIC) != 0) {
                        kfree_skb(skb);
                        return -ENOMEM;
                }
                pim = (struct pimreghdr*)skb->h.raw;
        }

        if (skb->len < sizeof(*pim) + sizeof(*encap) ||
            pim->type != ((PIM_VERSION<<4)|(PIM_REGISTER)) ||
            (pim->flags&PIM_NULL_REGISTER) ||
            (ip_compute_csum((void *)pim, sizeof(*pim)) != 0 &&
             ip_compute_csum((void *)pim, skb->len))) {
                kfree_skb(skb);
                return -EINVAL;
        }

        /* check if the inner packet is destined to mcast group */
        encap = (struct iphdr*)(skb->h.raw + sizeof(struct pimreghdr));
        if (!MULTICAST(encap->daddr) ||
            ntohs(encap->tot_len) == 0 ||
            ntohs(encap->tot_len) + sizeof(*pim) > skb->len) {
                kfree_skb(skb);
                return -EINVAL;
        }

        read_lock(&mrt_lock);
        if (reg_vif_num >= 0)
                reg_dev = vif_table[reg_vif_num].dev;
        if (reg_dev)
                dev_hold(reg_dev);
        read_unlock(&mrt_lock);

        if (reg_dev == NULL) {
                kfree_skb(skb);
                return -EINVAL;
        }

        skb->mac.raw = skb->nh.raw;
        skb_pull(skb, (u8*)encap - skb->data);
        skb->nh.iph = (struct iphdr *)skb->data;
        skb->dev = reg_dev;
        memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
        skb->protocol = htons(ETH_P_IP);
        skb->ip_summed = 0;
        skb->pkt_type = PACKET_HOST;
        dst_release(skb->dst);
        ((struct net_device_stats*)reg_dev->priv)->rx_bytes += skb->len;
        ((struct net_device_stats*)reg_dev->priv)->rx_packets++;
        skb->dst = NULL;
#ifdef CONFIG_NETFILTER
        nf_conntrack_put(skb->nfct);
        skb->nfct = NULL;
#endif
        netif_rx(skb);
        dev_put(reg_dev);
        return 0;
}
#endif

static int
ipmr_fill_mroute(struct sk_buff *skb, struct mfc_cache *c, struct rtmsg *rtm)
{
        int ct;
        struct rtnexthop *nhp;
        struct net_device *dev = vif_table[c->mfc_parent].dev;
        u8 *b = skb->tail;
        struct rtattr *mp_head;

        if (dev)
                RTA_PUT(skb, RTA_IIF, 4, &dev->ifindex);

        mp_head = (struct rtattr*)skb_put(skb, RTA_LENGTH(0));

        for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) {
                if (c->mfc_un.res.ttls[ct] < 255) {
                        if (skb_tailroom(skb) < RTA_ALIGN(RTA_ALIGN(sizeof(*nhp)) + 4))
                                goto rtattr_failure;
                        nhp = (struct rtnexthop*)skb_put(skb, RTA_ALIGN(sizeof(*nhp)));
                        nhp->rtnh_flags = 0;
                        nhp->rtnh_hops = c->mfc_un.res.ttls[ct];
                        nhp->rtnh_ifindex = vif_table[ct].dev->ifindex;
                        nhp->rtnh_len = sizeof(*nhp);
                }
        }
        mp_head->rta_type = RTA_MULTIPATH;
        mp_head->rta_len = skb->tail - (u8*)mp_head;
        rtm->rtm_type = RTN_MULTICAST;
        return 1;

rtattr_failure:
        skb_trim(skb, b - skb->data);
        return -EMSGSIZE;
}

int ipmr_get_route(struct sk_buff *skb, struct rtmsg *rtm, int nowait)
{
        int err;
        struct mfc_cache *cache;
        struct rtable *rt = (struct rtable*)skb->dst;

        read_lock(&mrt_lock);
        cache = ipmr_cache_find(rt->rt_src, rt->rt_dst);

        if (cache==NULL) {
                struct net_device *dev;
                int vif;

                if (nowait) {
                        read_unlock(&mrt_lock);
                        return -EAGAIN;
                }

                dev = skb->dev;
                if (dev == NULL || (vif = ipmr_find_vif(dev)) < 0) {
                        read_unlock(&mrt_lock);
                        return -ENODEV;
                }
                skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
                skb->nh.iph->ihl = sizeof(struct iphdr)>>2;
                skb->nh.iph->saddr = rt->rt_src;
                skb->nh.iph->daddr = rt->rt_dst;
                skb->nh.iph->version = 0;
                err = ipmr_cache_unresolved(vif, skb);
                read_unlock(&mrt_lock);
                return err;
        }

        if (!nowait && (rtm->rtm_flags&RTM_F_NOTIFY))
                cache->mfc_flags |= MFC_NOTIFY;
        err = ipmr_fill_mroute(skb, cache, rtm);
        read_unlock(&mrt_lock);
        return err;
}

#ifdef CONFIG_PROC_FS   
/*
 *      The /proc interfaces to multicast routing /proc/ip_mr_cache /proc/ip_mr_vif
 */
 
static int ipmr_vif_info(char *buffer, char **start, off_t offset, int length)
{
        struct vif_device *vif;
        int len=0;
        off_t pos=0;
        off_t begin=0;
        int size;
        int ct;

        len += sprintf(buffer,
                 "Interface      BytesIn  PktsIn  BytesOut PktsOut Flags Local    Remote\n");
        pos=len;
  
        read_lock(&mrt_lock);
        for (ct=0;ct<maxvif;ct++) 
        {
                char *name = "none";
                vif=&vif_table[ct];
                if(!VIF_EXISTS(ct))
                        continue;
                if (vif->dev)
                        name = vif->dev->name;
                size = sprintf(buffer+len, "%2d %-10s %8ld %7ld  %8ld %7ld %05X %08X %08X\n",
                        ct, name, vif->bytes_in, vif->pkt_in, vif->bytes_out, vif->pkt_out,
                        vif->flags, vif->local, vif->remote);
                len+=size;
                pos+=size;
                if(pos<offset)
                {
                        len=0;
                        begin=pos;
                }
                if(pos>offset+length)
                        break;
        }
        read_unlock(&mrt_lock);
        
        *start=buffer+(offset-begin);
        len-=(offset-begin);
        if(len>length)
                len=length;
        if (len<0)
                len = 0;
        return len;
}

static int ipmr_mfc_info(char *buffer, char **start, off_t offset, int length)
{
        struct mfc_cache *mfc;
        int len=0;
        off_t pos=0;
        off_t begin=0;
        int size;
        int ct;

        len += sprintf(buffer,
                 "Group    Origin   Iif     Pkts    Bytes    Wrong Oifs\n");
        pos=len;

        read_lock(&mrt_lock);
        for (ct=0;ct<MFC_LINES;ct++) 
        {
                for(mfc=mfc_cache_array[ct]; mfc; mfc=mfc->next)
                {
                        int n;

                        /*
                         *      Interface forwarding map
                         */
                        size = sprintf(buffer+len, "%08lX %08lX %-3d %8ld %8ld %8ld",
                                (unsigned long)mfc->mfc_mcastgrp,
                                (unsigned long)mfc->mfc_origin,
                                mfc->mfc_parent,
                                mfc->mfc_un.res.pkt,
                                mfc->mfc_un.res.bytes,
                                mfc->mfc_un.res.wrong_if);
                        for(n=mfc->mfc_un.res.minvif;n<mfc->mfc_un.res.maxvif;n++)
                        {
                                if(VIF_EXISTS(n) && mfc->mfc_un.res.ttls[n] < 255)
                                        size += sprintf(buffer+len+size, " %2d:%-3d", n, mfc->mfc_un.res.ttls[n]);
                        }
                        size += sprintf(buffer+len+size, "\n");
                        len+=size;
                        pos+=size;
                        if(pos<offset)
                        {
                                len=0;
                                begin=pos;
                        }
                        if(pos>offset+length)
                                goto done;
                }
        }

        spin_lock_bh(&mfc_unres_lock);
        for(mfc=mfc_unres_queue; mfc; mfc=mfc->next) {
                size = sprintf(buffer+len, "%08lX %08lX %-3d %8ld %8ld %8ld\n",
                               (unsigned long)mfc->mfc_mcastgrp,
                               (unsigned long)mfc->mfc_origin,
                               -1,
                                (long)mfc->mfc_un.unres.unresolved.qlen,
                                0L, 0L);
                len+=size;
                pos+=size;
                if(pos<offset)
                {
                        len=0;
                        begin=pos;
                }
                if(pos>offset+length)
                        break;
        }
        spin_unlock_bh(&mfc_unres_lock);

done:
        read_unlock(&mrt_lock);
        *start=buffer+(offset-begin);
        len-=(offset-begin);
        if(len>length)
                len=length;
        if (len < 0) {
                len = 0;
        }
        return len;
}

#endif  

#ifdef CONFIG_IP_PIMSM_V2
struct inet_protocol pim_protocol = 
{
        pim_rcv,                /* PIM handler          */
        NULL,                   /* PIM error control    */
        NULL,                   /* next                 */
        IPPROTO_PIM,            /* protocol ID          */
        0,                      /* copy                 */
        NULL,                   /* data                 */
        "PIM"                   /* name                 */
};
#endif


/*
 *      Setup for IP multicast routing
 */
 
void __init ip_mr_init(void)
{
        printk(KERN_INFO "Linux IP multicast router 0.06 plus PIM-SM\n");
        mrt_cachep = kmem_cache_create("ip_mrt_cache",
                                       sizeof(struct mfc_cache),
                                       0, SLAB_HWCACHE_ALIGN,
                                       NULL, NULL);
        init_timer(&ipmr_expire_timer);
        ipmr_expire_timer.function=ipmr_expire_process;
        register_netdevice_notifier(&ip_mr_notifier);
#ifdef CONFIG_PROC_FS   
        proc_net_create("ip_mr_vif",0,ipmr_vif_info);
        proc_net_create("ip_mr_cache",0,ipmr_mfc_info);
#endif  
}

---