/*
 * NET3:        Token ring device handling subroutines
 *
 *              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:       3 Feb 97 Paul Norton <pnorton@cts.com> Minor routing fixes.
 *              Added rif table to /proc/net/tr_rif and rif timeout to
 *              /proc/sys/net/token-ring/rif_timeout.
 *              22 Jun 98 Paul Norton <p.norton@computer.org> Rearranged
 *              tr_header and tr_type_trans to handle passing IPX SNAP and
 *              802.2 through the correct layers. Eliminated tr_reformat.
 *
 */

#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/trdevice.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/net.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <net/arp.h>
#include <net/net_namespace.h>

static void tr_add_rif_info(struct trh_hdr *trh, struct net_device *dev);
static void rif_check_expire(unsigned long dummy);

#define TR_SR_DEBUG 0

/*
 *      Each RIF entry we learn is kept this way
 */

struct rif_cache {
        unsigned char addr[TR_ALEN];
        int iface;
        __be16 rcf;
        __be16 rseg[8];
        struct rif_cache *next;
        unsigned long last_used;
        unsigned char local_ring;
};

#define RIF_TABLE_SIZE 32

/*
 *      We hash the RIF cache 32 ways. We do after all have to look it
 *      up a lot.
 */

static struct rif_cache *rif_table[RIF_TABLE_SIZE];

static DEFINE_SPINLOCK(rif_lock);


/*
 *      Garbage disposal timer.
 */

static struct timer_list rif_timer;

static int sysctl_tr_rif_timeout = 60*10*HZ;

static inline unsigned long rif_hash(const unsigned char *addr)
{
        unsigned long x;

        x = addr[0];
        x = (x << 2) ^ addr[1];
        x = (x << 2) ^ addr[2];
        x = (x << 2) ^ addr[3];
        x = (x << 2) ^ addr[4];
        x = (x << 2) ^ addr[5];

        x ^= x >> 8;

        return x & (RIF_TABLE_SIZE - 1);
}

/*
 *      Put the headers on a token ring packet. Token ring source routing
 *      makes this a little more exciting than on ethernet.
 */

static int tr_header(struct sk_buff *skb, struct net_device *dev,
                     unsigned short type,
                     const void *daddr, const void *saddr, unsigned len)
{
        struct trh_hdr *trh;
        int hdr_len;

        /*
         * Add the 802.2 SNAP header if IP as the IPv4/IPv6 code calls
         * dev->hard_header directly.
         */
        if (type == ETH_P_IP || type == ETH_P_IPV6 || type == ETH_P_ARP)
        {
                struct trllc *trllc;

                hdr_len = sizeof(struct trh_hdr) + sizeof(struct trllc);
                trh = (struct trh_hdr *)skb_push(skb, hdr_len);
                trllc = (struct trllc *)(trh+1);
                trllc->dsap = trllc->ssap = EXTENDED_SAP;
                trllc->llc = UI_CMD;
                trllc->protid[0] = trllc->protid[1] = trllc->protid[2] = 0x00;
                trllc->ethertype = htons(type);
        }
        else
        {
                hdr_len = sizeof(struct trh_hdr);
                trh = (struct trh_hdr *)skb_push(skb, hdr_len);
        }

        trh->ac=AC;
        trh->fc=LLC_FRAME;

        if(saddr)
                memcpy(trh->saddr,saddr,dev->addr_len);
        else
                memcpy(trh->saddr,dev->dev_addr,dev->addr_len);

        /*
         *      Build the destination and then source route the frame
         */

        if(daddr)
        {
                memcpy(trh->daddr,daddr,dev->addr_len);
                tr_source_route(skb, trh, dev);
                return(hdr_len);
        }

        return -hdr_len;
}

/*
 *      A neighbour discovery of some species (eg arp) has completed. We
 *      can now send the packet.
 */

static int tr_rebuild_header(struct sk_buff *skb)
{
        struct trh_hdr *trh=(struct trh_hdr *)skb->data;
        struct trllc *trllc=(struct trllc *)(skb->data+sizeof(struct trh_hdr));
        struct net_device *dev = skb->dev;

        /*
         *      FIXME: We don't yet support IPv6 over token rings
         */

        if(trllc->ethertype != htons(ETH_P_IP)) {
                printk("tr_rebuild_header: Don't know how to resolve type %04X addresses ?\n", ntohs(trllc->ethertype));
                return 0;
        }

#ifdef CONFIG_INET
        if(arp_find(trh->daddr, skb)) {
                        return 1;
        }
        else
#endif
        {
                tr_source_route(skb,trh,dev);
                return 0;
        }
}

/*
 *      Some of this is a bit hackish. We intercept RIF information
 *      used for source routing. We also grab IP directly and don't feed
 *      it via SNAP.
 */

__be16 tr_type_trans(struct sk_buff *skb, struct net_device *dev)
{

        struct trh_hdr *trh;
        struct trllc *trllc;
        unsigned riflen=0;

        skb->dev = dev;
        skb_reset_mac_header(skb);
        trh = tr_hdr(skb);

        if(trh->saddr[0] & TR_RII)
                riflen = (ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8;

        trllc = (struct trllc *)(skb->data+sizeof(struct trh_hdr)-TR_MAXRIFLEN+riflen);

        skb_pull(skb,sizeof(struct trh_hdr)-TR_MAXRIFLEN+riflen);

        if(*trh->daddr & 0x80)
        {
                if(!memcmp(trh->daddr,dev->broadcast,TR_ALEN))
                        skb->pkt_type=PACKET_BROADCAST;
                else
                        skb->pkt_type=PACKET_MULTICAST;
        }
        else if ( (trh->daddr[0] & 0x01) && (trh->daddr[1] & 0x00) && (trh->daddr[2] & 0x5E))
        {
                skb->pkt_type=PACKET_MULTICAST;
        }
        else if(dev->flags & IFF_PROMISC)
        {
                if(memcmp(trh->daddr, dev->dev_addr, TR_ALEN))
                        skb->pkt_type=PACKET_OTHERHOST;
        }

        if ((skb->pkt_type != PACKET_BROADCAST) &&
            (skb->pkt_type != PACKET_MULTICAST))
                tr_add_rif_info(trh,dev) ;

        /*
         * Strip the SNAP header from ARP packets since we don't
         * pass them through to the 802.2/SNAP layers.
         */

        if (trllc->dsap == EXTENDED_SAP &&
            (trllc->ethertype == htons(ETH_P_IP) ||
             trllc->ethertype == htons(ETH_P_IPV6) ||
             trllc->ethertype == htons(ETH_P_ARP)))
        {
                skb_pull(skb, sizeof(struct trllc));
                return trllc->ethertype;
        }

        return htons(ETH_P_TR_802_2);
}

/*
 *      We try to do source routing...
 */

void tr_source_route(struct sk_buff *skb,struct trh_hdr *trh,
                     struct net_device *dev)
{
        int slack;
        unsigned int hash;
        struct rif_cache *entry;
        unsigned char *olddata;
        unsigned long flags;
        static const unsigned char mcast_func_addr[]
                = {0xC0,0x00,0x00,0x04,0x00,0x00};

        spin_lock_irqsave(&rif_lock, flags);

        /*
         *      Broadcasts are single route as stated in RFC 1042
         */
        if( (!memcmp(&(trh->daddr[0]),&(dev->broadcast[0]),TR_ALEN)) ||
            (!memcmp(&(trh->daddr[0]),&(mcast_func_addr[0]), TR_ALEN))  )
        {
                trh->rcf=htons((((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK)
                               | TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST);
                trh->saddr[0]|=TR_RII;
        }
        else
        {
                hash = rif_hash(trh->daddr);
                /*
                 *      Walk the hash table and look for an entry
                 */
                for(entry=rif_table[hash];entry && memcmp(&(entry->addr[0]),&(trh->daddr[0]),TR_ALEN);entry=entry->next);

                /*
                 *      If we found an entry we can route the frame.
                 */
                if(entry)
                {
#if TR_SR_DEBUG
printk("source routing for %pM\n", trh->daddr);
#endif
                        if(!entry->local_ring && (ntohs(entry->rcf) & TR_RCF_LEN_MASK) >> 8)
                        {
                                trh->rcf=entry->rcf;
                                memcpy(&trh->rseg[0],&entry->rseg[0],8*sizeof(unsigned short));
                                trh->rcf^=htons(TR_RCF_DIR_BIT);
                                trh->rcf&=htons(0x1fff);        /* Issam Chehab <ichehab@madge1.demon.co.uk> */

                                trh->saddr[0]|=TR_RII;
#if TR_SR_DEBUG
                                printk("entry found with rcf %04x\n", entry->rcf);
                        }
                        else
                        {
                                printk("entry found but without rcf length, local=%02x\n", entry->local_ring);
#endif
                        }
                        entry->last_used=jiffies;
                }
                else
                {
                        /*
                         *      Without the information we simply have to shout
                         *      on the wire. The replies should rapidly clean this
                         *      situation up.
                         */
                        trh->rcf=htons((((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK)
                                       | TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST);
                        trh->saddr[0]|=TR_RII;
#if TR_SR_DEBUG
                        printk("no entry in rif table found - broadcasting frame\n");
#endif
                }
        }

        /* Compress the RIF here so we don't have to do it in the driver(s) */
        if (!(trh->saddr[0] & 0x80))
                slack = 18;
        else
                slack = 18 - ((ntohs(trh->rcf) & TR_RCF_LEN_MASK)>>8);
        olddata = skb->data;
        spin_unlock_irqrestore(&rif_lock, flags);

        skb_pull(skb, slack);
        memmove(skb->data, olddata, sizeof(struct trh_hdr) - slack);
}

/*
 *      We have learned some new RIF information for our source
 *      routing.
 */

static void tr_add_rif_info(struct trh_hdr *trh, struct net_device *dev)
{
        unsigned int hash, rii_p = 0;
        unsigned long flags;
        struct rif_cache *entry;
        unsigned char saddr0;

        spin_lock_irqsave(&rif_lock, flags);
        saddr0 = trh->saddr[0];

        /*
         *      Firstly see if the entry exists
         */

        if(trh->saddr[0] & TR_RII)
        {
                trh->saddr[0]&=0x7f;
                if (((ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8) > 2)
                {
                        rii_p = 1;
                }
        }

        hash = rif_hash(trh->saddr);
        for(entry=rif_table[hash];entry && memcmp(&(entry->addr[0]),&(trh->saddr[0]),TR_ALEN);entry=entry->next);

        if(entry==NULL)
        {
#if TR_SR_DEBUG
                printk("adding rif_entry: addr:%pM rcf:%04X\n",
                       trh->saddr, ntohs(trh->rcf));
#endif
                /*
                 *      Allocate our new entry. A failure to allocate loses
                 *      use the information. This is harmless.
                 *
                 *      FIXME: We ought to keep some kind of cache size
                 *      limiting and adjust the timers to suit.
                 */
                entry=kmalloc(sizeof(struct rif_cache),GFP_ATOMIC);

                if(!entry)
                {
                        printk(KERN_DEBUG "tr.c: Couldn't malloc rif cache entry !\n");
                        spin_unlock_irqrestore(&rif_lock, flags);
                        return;
                }

                memcpy(&(entry->addr[0]),&(trh->saddr[0]),TR_ALEN);
                entry->iface = dev->ifindex;
                entry->next=rif_table[hash];
                entry->last_used=jiffies;
                rif_table[hash]=entry;

                if (rii_p)
                {
                        entry->rcf = trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK);
                        memcpy(&(entry->rseg[0]),&(trh->rseg[0]),8*sizeof(unsigned short));
                        entry->local_ring = 0;
                }
                else
                {
                        entry->local_ring = 1;
                }
        }
        else    /* Y. Tahara added */
        {
                /*
                 *      Update existing entries
                 */
                if (!entry->local_ring)
                    if (entry->rcf != (trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK)) &&
                         !(trh->rcf & htons(TR_RCF_BROADCAST_MASK)))
                    {
#if TR_SR_DEBUG
printk("updating rif_entry: addr:%pM rcf:%04X\n",
                trh->saddr, ntohs(trh->rcf));
#endif
                            entry->rcf = trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK);
                            memcpy(&(entry->rseg[0]),&(trh->rseg[0]),8*sizeof(unsigned short));
                    }
                entry->last_used=jiffies;
        }
        trh->saddr[0]=saddr0; /* put the routing indicator back for tcpdump */
        spin_unlock_irqrestore(&rif_lock, flags);
}

/*
 *      Scan the cache with a timer and see what we need to throw out.
 */

static void rif_check_expire(unsigned long dummy)
{
        int i;
        unsigned long flags, next_interval = jiffies + sysctl_tr_rif_timeout/2;

        spin_lock_irqsave(&rif_lock, flags);

        for(i =0; i < RIF_TABLE_SIZE; i++) {
                struct rif_cache *entry, **pentry;

                pentry = rif_table+i;
                while((entry=*pentry) != NULL) {
                        unsigned long expires
                                = entry->last_used + sysctl_tr_rif_timeout;

                        if (time_before_eq(expires, jiffies)) {
                                *pentry = entry->next;
                                kfree(entry);
                        } else {
                                pentry = &entry->next;

                                if (time_before(expires, next_interval))
                                        next_interval = expires;
                        }
                }
        }

        spin_unlock_irqrestore(&rif_lock, flags);

        mod_timer(&rif_timer, next_interval);

}

/*
 *      Generate the /proc/net information for the token ring RIF
 *      routing.
 */

#ifdef CONFIG_PROC_FS

static struct rif_cache *rif_get_idx(loff_t pos)
{
        int i;
        struct rif_cache *entry;
        loff_t off = 0;

        for(i = 0; i < RIF_TABLE_SIZE; i++)
                for(entry = rif_table[i]; entry; entry = entry->next) {
                        if (off == pos)
                                return entry;
                        ++off;
                }

        return NULL;
}

static void *rif_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(&rif_lock)
{
        spin_lock_irq(&rif_lock);

        return *pos ? rif_get_idx(*pos - 1) : SEQ_START_TOKEN;
}

static void *rif_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        int i;
        struct rif_cache *ent = v;

        ++*pos;

        if (v == SEQ_START_TOKEN) {
                i = -1;
                goto scan;
        }

        if (ent->next)
                return ent->next;

        i = rif_hash(ent->addr);
 scan:
        while (++i < RIF_TABLE_SIZE) {
                if ((ent = rif_table[i]) != NULL)
                        return ent;
        }
        return NULL;
}

static void rif_seq_stop(struct seq_file *seq, void *v)
        __releases(&rif_lock)
{
        spin_unlock_irq(&rif_lock);
}

static int rif_seq_show(struct seq_file *seq, void *v)
{
        int j, rcf_len, segment, brdgnmb;
        struct rif_cache *entry = v;

        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                     "if     TR address       TTL   rcf   routing segments\n");
        else {
                struct net_device *dev = dev_get_by_index(&init_net, entry->iface);
                long ttl = (long) (entry->last_used + sysctl_tr_rif_timeout)
                                - (long) jiffies;

                seq_printf(seq, "%s %pM %7li ",
                           dev?dev->name:"?",
                           entry->addr,
                           ttl/HZ);

                        if (entry->local_ring)
                                seq_puts(seq, "local\n");
                        else {

                                seq_printf(seq, "%04X", ntohs(entry->rcf));
                                rcf_len = ((ntohs(entry->rcf) & TR_RCF_LEN_MASK)>>8)-2;
                                if (rcf_len)
                                        rcf_len >>= 1;
                                for(j = 1; j < rcf_len; j++) {
                                        if(j==1) {
                                                segment=ntohs(entry->rseg[j-1])>>4;
                                                seq_printf(seq,"  %03X",segment);
                                        }

                                        segment=ntohs(entry->rseg[j])>>4;
                                        brdgnmb=ntohs(entry->rseg[j-1])&0x00f;
                                        seq_printf(seq,"-%01X-%03X",brdgnmb,segment);
                                }
                                seq_putc(seq, '\n');
                        }

                if (dev)
                        dev_put(dev);
                }
        return 0;
}


static const struct seq_operations rif_seq_ops = {
        .start = rif_seq_start,
        .next  = rif_seq_next,
        .stop  = rif_seq_stop,
        .show  = rif_seq_show,
};

static int rif_seq_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &rif_seq_ops);
}

static const struct file_operations rif_seq_fops = {
        .owner   = THIS_MODULE,
        .open    = rif_seq_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release,
};

#endif

static const struct header_ops tr_header_ops = {
        .create = tr_header,
        .rebuild= tr_rebuild_header,
};

static void tr_setup(struct net_device *dev)
{
        /*
         *      Configure and register
         */

        dev->header_ops = &tr_header_ops;

        dev->type               = ARPHRD_IEEE802_TR;
        dev->hard_header_len    = TR_HLEN;
        dev->mtu                = 2000;
        dev->addr_len           = TR_ALEN;
        dev->tx_queue_len       = 100;  /* Long queues on tr */

        memset(dev->broadcast,0xFF, TR_ALEN);

        /* New-style flags. */
        dev->flags              = IFF_BROADCAST | IFF_MULTICAST ;
}

/**
 * alloc_trdev - Register token ring device
 * @sizeof_priv: Size of additional driver-private structure to be allocated
 *      for this token ring device
 *
 * Fill in the fields of the device structure with token ring-generic values.
 *
 * Constructs a new net device, complete with a private data area of
 * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 * this private data area.
 */
struct net_device *alloc_trdev(int sizeof_priv)
{
        return alloc_netdev(sizeof_priv, "tr%d", tr_setup);
}

#ifdef CONFIG_SYSCTL
static struct ctl_table tr_table[] = {
        {
                .procname       = "rif_timeout",
                .data           = &sysctl_tr_rif_timeout,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec
        },
        { },
};

static __initdata struct ctl_path tr_path[] = {
        { .procname = "net", },
        { .procname = "token-ring", },
        { }
};
#endif

/*
 *      Called during bootup.  We don't actually have to initialise
 *      too much for this.
 */

static int __init rif_init(void)
{
        rif_timer.expires  = jiffies + sysctl_tr_rif_timeout;
        setup_timer(&rif_timer, rif_check_expire, 0);
        add_timer(&rif_timer);
#ifdef CONFIG_SYSCTL
        register_sysctl_paths(tr_path, tr_table);
#endif
        proc_net_fops_create(&init_net, "tr_rif", S_IRUGO, &rif_seq_fops);
        return 0;
}

module_init(rif_init);

EXPORT_SYMBOL(tr_type_trans);
EXPORT_SYMBOL(alloc_trdev);

MODULE_LICENSE("GPL");