dn_route.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

        if (memcmp(ptr, dn_hiord_addr, 4) != 0)
                goto drop_it;
        ptr += 6;


        /* Source info */
        ptr += 2;
	cb->src = dn_htons(dn_eth2dn(ptr));
        if (memcmp(ptr, dn_hiord_addr, 4) != 0)
                goto drop_it;
        ptr += 6;
        /* Other junk */
        ptr++;
        cb->hops = *ptr++; /* Visit Count */

	return NF_HOOK(PF_DECnet, NF_DN_PRE_ROUTING, skb, skb->dev, NULL, dn_route_rx_packet);

drop_it:
	kfree_skb(skb);
	return NET_RX_DROP;
}



static int dn_route_rx_short(struct sk_buff *skb)
{
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	unsigned char *ptr = skb->data;

	if (skb->len < 6) /* 5 for short header + 1 for shortest nsp */
		goto drop_it;

	skb_pull(skb, 5);
	skb->h.raw = skb->data;

	cb->dst = *(dn_address *)ptr;
        ptr += 2;
        cb->src = *(dn_address *)ptr;
        ptr += 2;
        cb->hops = *ptr & 0x3f;

	return NF_HOOK(PF_DECnet, NF_DN_PRE_ROUTING, skb, skb->dev, NULL, dn_route_rx_packet);

drop_it:
        kfree_skb(skb);
        return NET_RX_DROP;
}

static int dn_route_discard(struct sk_buff *skb)
{
	/*
	 * I know we drop the packet here, but thats considered success in
	 * this case
	 */
	kfree_skb(skb);
	return NET_RX_SUCCESS;
}

static int dn_route_ptp_hello(struct sk_buff *skb)
{
	dn_dev_hello(skb);
	dn_neigh_pointopoint_hello(skb);
	return NET_RX_SUCCESS;
}

int dn_route_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
{
	struct dn_skb_cb *cb;
	unsigned char flags = 0;
	__u16 len = dn_ntohs(*(__u16 *)skb->data);
	struct dn_dev *dn = (struct dn_dev *)dev->dn_ptr;
	unsigned char padlen = 0;

	if (dn == NULL)
		goto dump_it;

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
		goto out;

	skb_pull(skb, 2);

	if (len > skb->len)
		goto dump_it;

	skb_trim(skb, len);

	flags = *skb->data;

	cb = DN_SKB_CB(skb);
	cb->stamp = jiffies;
	cb->iif = dev->ifindex;

	/*
	 * If we have padding, remove it.
	 */
	if (flags & DN_RT_F_PF) {
		padlen = flags & ~DN_RT_F_PF;
		skb_pull(skb, padlen);
		flags = *skb->data;
	}

	skb->nh.raw = skb->data;

	/*
	 * Weed out future version DECnet
	 */
	if (flags & DN_RT_F_VER)
		goto dump_it;

	cb->rt_flags = flags;

	if (decnet_debug_level & 1)
		printk(KERN_DEBUG 
			"dn_route_rcv: got 0x%02x from %s [%d %d %d]\n",
			(int)flags, (dev) ? dev->name : "???", len, skb->len, 
			padlen);

        if (flags & DN_RT_PKT_CNTL) {
                switch(flags & DN_RT_CNTL_MSK) {
        	        case DN_RT_PKT_INIT:
				dn_dev_init_pkt(skb);
				break;
                	case DN_RT_PKT_VERI:
				dn_dev_veri_pkt(skb);
				break;
		}

		if (dn->parms.state != DN_DEV_S_RU)
			goto dump_it;

		switch(flags & DN_RT_CNTL_MSK) {
                	case DN_RT_PKT_HELO:
				return NF_HOOK(PF_DECnet, NF_DN_HELLO, skb, skb->dev, NULL, dn_route_ptp_hello);

                	case DN_RT_PKT_L1RT:
                	case DN_RT_PKT_L2RT:
                                return NF_HOOK(PF_DECnet, NF_DN_ROUTE, skb, skb->dev, NULL, dn_route_discard);
                	case DN_RT_PKT_ERTH:
				return NF_HOOK(PF_DECnet, NF_DN_HELLO, skb, skb->dev, NULL, dn_neigh_router_hello);

                	case DN_RT_PKT_EEDH:
				return NF_HOOK(PF_DECnet, NF_DN_HELLO, skb, skb->dev, NULL, dn_neigh_endnode_hello);
                }
        } else {
		if (dn->parms.state != DN_DEV_S_RU)
			goto dump_it;

		skb_pull(skb, 1); /* Pull flags */

                switch(flags & DN_RT_PKT_MSK) {
                	case DN_RT_PKT_LONG:
                        	return dn_route_rx_long(skb);
                	case DN_RT_PKT_SHORT:
                        	return dn_route_rx_short(skb);
		}
        }

dump_it:
	kfree_skb(skb);
out:
	return NET_RX_DROP;
}

static int dn_output(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct dn_route *rt = (struct dn_route *)dst;
	struct net_device *dev = dst->dev;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	struct neighbour *neigh;

	int err = -EINVAL;

	if ((neigh = dst->neighbour) == NULL)
		goto error;

	skb->dev = dev;

	cb->src = rt->rt_saddr;
	cb->dst = rt->rt_daddr;

	/*
	 * Always set the Intra-Ethernet bit on all outgoing packets
	 * originated on this node. Only valid flag from upper layers
	 * is return-to-sender-requested. Set hop count to 0 too.
	 */
	cb->rt_flags &= ~DN_RT_F_RQR;
	cb->rt_flags |= DN_RT_F_IE;
	cb->hops = 0;

	return NF_HOOK(PF_DECnet, NF_DN_LOCAL_OUT, skb, NULL, dev, neigh->output);

error:
	if (net_ratelimit())
		printk(KERN_DEBUG "dn_output: This should not happen\n");

	kfree_skb(skb);

	return err;
}

#ifdef CONFIG_DECNET_ROUTER
static int dn_forward(struct sk_buff *skb)
{
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	struct dst_entry *dst = skb->dst;
	struct neighbour *neigh;
	struct net_device *dev = skb->dev;
	int err = -EINVAL;

	if ((neigh = dst->neighbour) == NULL)
		goto error;

	/*
	 * Hop count exceeded.
	 */
	err = NET_RX_DROP;
	if (++cb->hops > 30)
		goto drop;

	skb->dev = dst->dev;

	/*
	 * If packet goes out same interface it came in on, then set
	 * the Intra-Ethernet bit. This has no effect for short
	 * packets, so we don't need to test for them here.
	 */
	if (cb->iif == dst->dev->ifindex)
		cb->rt_flags |= DN_RT_F_IE;
	else
		cb->rt_flags &= ~DN_RT_F_IE;

	return NF_HOOK(PF_DECnet, NF_DN_FORWARD, skb, dev, skb->dev, neigh->output);


error:
	if (net_ratelimit())
		printk(KERN_DEBUG "dn_forward: This should not happen\n");
drop:
	kfree_skb(skb);

	return err;
}
#endif

/*
 * Drop packet. This is used for endnodes and for
 * when we should not be forwarding packets from
 * this dest.
 */
static int dn_blackhole(struct sk_buff *skb)
{
	kfree_skb(skb);
	return NET_RX_DROP;
}

/*
 * Used to catch bugs. This should never normally get
 * called.
 */
static int dn_rt_bug(struct sk_buff *skb)
{
	if (net_ratelimit()) {
		struct dn_skb_cb *cb = DN_SKB_CB(skb);

		printk(KERN_DEBUG "dn_rt_bug: skb from:%04x to:%04x\n",
				cb->src, cb->dst);
	}

	kfree_skb(skb);

	return NET_RX_BAD;
}

static int dn_route_output_slow(struct dst_entry **pprt, dn_address dst, dn_address src, int flags)
{
	struct dn_route *rt = NULL;
	struct net_device *dev = decnet_default_device;
	struct neighbour *neigh = NULL;
	struct dn_dev *dn_db;
	unsigned hash;
#ifdef CONFIG_DECNET_ROUTER
	struct dn_fib_key key;
	struct dn_fib_res res;
	int err;

	key.src = src;
	key.dst = dst;
	key.iif = 0;
	key.oif = 0;
	key.fwmark = 0;
	key.scope = RT_SCOPE_UNIVERSE;

	if ((err = dn_fib_lookup(&key, &res)) == 0) {
		switch(res.type) {
			case RTN_UNICAST:
				/*
				 * This method of handling multipath
				 * routes is a hack and will change.
				 * It works for now though.
				 */
				if (res.fi->fib_nhs)
					dn_fib_select_multipath(&key, &res);
				neigh = __neigh_lookup(&dn_neigh_table, &DN_FIB_RES_GW(res), DN_FIB_RES_DEV(res), 1);
				err = -ENOBUFS;
				if (!neigh)
					break;
				err = 0;
				break;
			case RTN_UNREACHABLE:
				err = -EHOSTUNREACH;
				break;
			default:
				err = -EINVAL;
		}
		dn_fib_res_put(&res);
		if (err < 0)
			return err;
		goto got_route;
	}

	if (err != -ESRCH)
		return err;
#endif 

	/* Look in On-Ethernet cache first */
	if (!(flags & MSG_TRYHARD)) {
		if ((neigh = dn_neigh_lookup(&dn_neigh_table, &dst)) != NULL)
			goto got_route;
	}

	if (dev == NULL)
		return -EINVAL;

	dn_db = dev->dn_ptr;

	if (dn_db == NULL)
		return -EINVAL;

	/* Try default router */
	if ((neigh = neigh_clone(dn_db->router)) != NULL)
		goto got_route;

	/* Send to default device (and hope for the best) if above fail */
	if ((neigh = __neigh_lookup(&dn_neigh_table, &dst, dev, 1)) != NULL)
		goto got_route;


	return -EINVAL;

got_route:

	if ((rt = dst_alloc(&dn_dst_ops)) == NULL) {
		neigh_release(neigh);
		return -EINVAL;
	}

	dn_db = (struct dn_dev *)neigh->dev->dn_ptr;
	
	rt->key.saddr  = src;
	rt->rt_saddr   = src;
	rt->key.daddr  = dst;
	rt->rt_daddr   = dst;
	rt->key.oif    = neigh ? neigh->dev->ifindex : -1;
	rt->key.iif    = 0;
	rt->key.fwmark = 0;

	rt->u.dst.neighbour = neigh;
	rt->u.dst.dev = neigh ? neigh->dev : NULL;
	rt->u.dst.lastuse = jiffies;
	rt->u.dst.output = dn_output;
	rt->u.dst.input  = dn_rt_bug;

	if (dn_dev_islocal(neigh->dev, rt->rt_daddr))
		rt->u.dst.input = dn_nsp_rx;

	hash = dn_hash(rt->key.saddr, rt->key.daddr);
	dn_insert_route(rt, hash);
	*pprt = &rt->u.dst;

	return 0;
}

int dn_route_output(struct dst_entry **pprt, dn_address dst, dn_address src, int flags)
{
	unsigned hash = dn_hash(src, dst);
	struct dn_route *rt = NULL;

	if (!(flags & MSG_TRYHARD)) {
		read_lock_bh(&dn_rt_hash_table[hash].lock);
		for(rt = dn_rt_hash_table[hash].chain; rt; rt = rt->u.rt_next) {
			if ((dst == rt->key.daddr) &&
					(src == rt->key.saddr) &&
					(rt->key.iif == 0) &&
					(rt->key.oif != 0)) {
				rt->u.dst.lastuse = jiffies;
				dst_hold(&rt->u.dst);
				rt->u.dst.__use++;
				read_unlock_bh(&dn_rt_hash_table[hash].lock);
				*pprt = &rt->u.dst;
				return 0;
			}
		}
		read_unlock_bh(&dn_rt_hash_table[hash].lock);
	}

	return dn_route_output_slow(pprt, dst, src, flags);
}

static int dn_route_input_slow(struct sk_buff *skb)
{
	struct dn_route *rt = NULL;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	struct net_device *dev = skb->dev;
	struct dn_dev *dn_db;
	struct neighbour *neigh = NULL;
	int (*dnrt_input)(struct sk_buff *skb);
	int (*dnrt_output)(struct sk_buff *skb);
	u32 fwmark = 0;
	unsigned hash;
	dn_address saddr = cb->src;
	dn_address daddr = cb->dst;
#ifdef CONFIG_DECNET_ROUTER
	struct dn_fib_key key;
	struct dn_fib_res res;
	int err;
#endif

	if (dev == NULL)
		return -EINVAL;

	if ((dn_db = dev->dn_ptr) == NULL)
		return -EINVAL;