/*
 *      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 1.30 1999/03/25 10:04:10 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.
 */


#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>
#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_Unsolicited_Report_Interval        (10*HZ)
#define IGMP_Query_Response_Interval            (10*HZ)
#define IGMP_Unsolicited_Report_Count           2


#define IGMP_Initial_Report_Delay               (1*HZ)

/* 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 && (long)(jiffies - (in_dev)->mr_v1_seen) < 0)

/*
 *      Timer management
 */

static __inline__ void igmp_stop_timer(struct ip_mc_list *im)
{
        if (im->tm_running) {
                del_timer(&im->timer);
                im->tm_running=0;
        }
}

static __inline__ void igmp_start_timer(struct ip_mc_list *im, int max_delay)
{
        int tv;
        if (im->tm_running)
                return;
        tv=net_random() % max_delay;
        im->timer.expires=jiffies+tv+2;
        im->tm_running=1;
        add_timer(&im->timer);
}

/*
 *      Send an IGMP report.
 */

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

static int igmp_send_report(struct device *dev, u32 group, int type)
{
        struct sk_buff *skb;
        struct iphdr *iph;
        struct igmphdr *ih;
        struct rtable *rt;
        u32     dst;

        /* According to IGMPv2 specs, LEAVE messages are
         * sent to all-routers group.
         */
        dst = group;
        if (type == IGMP_HOST_LEAVE_MESSAGE)
                dst = IGMP_ALL_ROUTER;

        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      = 0;
        iph->frag_off = 0;
        iph->ttl      = 1;
        iph->daddr    = dst;
        iph->saddr    = rt->rt_src;
        iph->protocol = IPPROTO_IGMP;
        iph->tot_len  = htons(IGMP_SIZE);
        iph->id       = htons(ip_id_count++);
        ((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 skb->dst->output(skb);
}


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;
        int err;

        im->tm_running=0;

        if (IGMP_V1_SEEN(in_dev))
                err = igmp_send_report(in_dev->dev, im->multiaddr, IGMP_HOST_MEMBERSHIP_REPORT);
        else
                err = igmp_send_report(in_dev->dev, im->multiaddr, IGMP_HOST_NEW_MEMBERSHIP_REPORT);

        /* Failed. Retry later. */
        if (err) {
                igmp_start_timer(im, IGMP_Unsolicited_Report_Interval);
                return;
        }

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

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 (LOCAL_MCAST(group))
                return;

        for (im=in_dev->mc_list; im!=NULL; im=im->next) {
                if (im->multiaddr == group) {
                        igmp_stop_timer(im);
                        im->reporter = 0;
                        im->unsolicit_count = 0;
                        return;
                }
        }
}

static void igmp_heard_query(struct in_device *in_dev, unsigned char max_resp_time,
                             u32 group)
{
        struct ip_mc_list       *im;
        int                     max_delay;

        max_delay = max_resp_time*(HZ/IGMP_TIMER_SCALE);

        if (max_resp_time == 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;
        }
                
        /*
         * - 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
         */
        for (im=in_dev->mc_list; im!=NULL; im=im->next) {
                if (group && group != im->multiaddr)
                        continue;
                if (LOCAL_MCAST(im->multiaddr))
                        continue;
                im->unsolicit_count = 0;
                if (im->tm_running && (long)(im->timer.expires-jiffies) > max_delay)
                        igmp_stop_timer(im);
                igmp_start_timer(im, max_delay);
        }
}

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

        if (len < sizeof(struct igmphdr) || ip_compute_csum((void *)ih, len)
            || in_dev==NULL) {
                kfree_skb(skb);
                return 0;
        }
        
        switch (ih->type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:
                igmp_heard_query(in_dev, ih->code, ih->group);
                break;
        case IGMP_HOST_MEMBERSHIP_REPORT:
        case IGMP_HOST_NEW_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
                return pim_rcv_v1(skb, len);
#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));
        }
        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 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 device *dev = in_dev->dev;

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

static void igmp_group_dropped(struct ip_mc_list *im)
{
        if (im->loaded) {
                im->loaded = 0;
                ip_mc_filter_del(im->interface, im->multiaddr);
        }

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

        start_bh_atomic();
        igmp_stop_timer(im);
        end_bh_atomic();

        if (im->reporter && !IGMP_V1_SEEN(im->interface))
                igmp_send_report(im->interface->dev, im->multiaddr, IGMP_HOST_LEAVE_MESSAGE);
#endif
}

static void igmp_group_added(struct ip_mc_list *im)
{
        if (im->loaded == 0) {
                im->loaded = 1;
                ip_mc_filter_add(im->interface, im->multiaddr);
        }

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

        start_bh_atomic();
        igmp_start_timer(im, IGMP_Initial_Report_Delay);
        end_bh_atomic();
#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 *i, *im;

        im = (struct ip_mc_list *)kmalloc(sizeof(*im), GFP_KERNEL);

        for (i=in_dev->mc_list; i; i=i->next) {
                if (i->multiaddr == addr) {
                        i->users++;
                        if (im)
                                kfree(im);
                        return;
                }
        }
        if (!im)
                return;
        im->users=1;
        im->interface=in_dev;
        im->multiaddr=addr;
#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->loaded = 0;
#endif
        im->next=in_dev->mc_list;
        in_dev->mc_list=im;
        igmp_group_added(im);
        if (in_dev->dev->flags & IFF_UP)
                ip_rt_multicast_event(in_dev);
        return;
}

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

int ip_mc_dec_group(struct in_device *in_dev, u32 addr)
{
        struct ip_mc_list *i, **ip;

        for (ip=&in_dev->mc_list; (i=*ip)!=NULL; ip=&i->next) {
                if (i->multiaddr==addr) {
                        if (--i->users == 0) {
                                *ip = i->next;
                                synchronize_bh();

                                igmp_group_dropped(i);
                                if (in_dev->dev->flags & IFF_UP)
                                        ip_rt_multicast_event(in_dev);
                                kfree_s(i, sizeof(*i));
                        }
                        return 0;
                }
        }
        return -ESRCH;
}

/* Device going down */

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

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

        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;

        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;

        while ((i = in_dev->mc_list) != NULL) {
                in_dev->mc_list = i->next;
                igmp_group_dropped(i);
                kfree_s(i, sizeof(*i));
        }
}

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

        if (imr->imr_address.s_addr) {
                dev = ip_dev_find(imr->imr_address.s_addr);
                if (!dev)
                        return NULL;
        }

        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;
                return dev->ip_ptr;
        }
        return NULL;
}

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

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;
        int count = 0;

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

        rtnl_shlock();

        if (!imr->imr_ifindex)
                in_dev = ip_mc_find_dev(imr);
        else
                in_dev = inetdev_by_index(imr->imr_ifindex);

        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=sk->ip_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->ip_mc_list;
        iml->count = 1;
        sk->ip_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;
}

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

int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr)
{
        struct ip_mc_socklist *iml, **imlp;

        for (imlp=&sk->ip_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;
                        if (--iml->count)
                                return 0;

                        *imlp = iml->next;
                        synchronize_bh();

                        in_dev = inetdev_by_index(iml->multi.imr_ifindex);
                        if (in_dev)
                                ip_mc_dec_group(in_dev, imr->imr_multiaddr.s_addr);
                        sock_kfree_s(sk, iml, sizeof(*iml));
                        return 0;
                }
        }
        return -EADDRNOTAVAIL;
}

/*
 *      A socket is closing.
 */

void ip_mc_drop_socket(struct sock *sk)
{
        struct ip_mc_socklist *iml;

        while ((iml=sk->ip_mc_list) != NULL) {
                struct in_device *in_dev;
                sk->ip_mc_list = iml->next;
                if ((in_dev = inetdev_by_index(iml->multi.imr_ifindex)) != NULL)
                        ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr);
                sock_kfree_s(sk, iml, sizeof(*iml));
        }
}


#ifdef CONFIG_IP_MULTICAST
 
int ip_mc_procinfo(char *buffer, char **start, off_t offset, int length, int dummy)
{
        off_t pos=0, begin=0;
        struct ip_mc_list *im;
        int len=0;
        struct device *dev;
        
        len=sprintf(buffer,"Idx\tDevice    : Count Querier\tGroup    Users Timer\tReporter\n");  
        
        for(dev = dev_base; dev; dev = dev->next)
        {
                struct in_device *in_dev = dev->ip_ptr;
                char   *querier = "NONE";
                
                if (in_dev == NULL)
                        continue;

                querier = IGMP_V1_SEEN(in_dev) ? "V1" : "V2";

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

                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)
                                goto done;
                }
        }
done:
        *start=buffer+(offset-begin);
        len-=(offset-begin);
        if(len>length)
                len=length;
        if(len<0)
                len=0;
        return len;
}
#endif