text: 
  /*
   * DECnet       An implementation of the DECnet protocol suite for the LINUX
   *              operating system.  DECnet is implemented using the  BSD Socket
   *              interface as the means of communication with the user level.
   *
   *              DECnet Routing Forwarding Information Base (Rules)
   *
   * Author:      Steve Whitehouse <SteveW@ACM.org>
   *              Mostly copied from Alexey Kuznetsov's ipv4/fib_rules.c
   *
   *
   * Changes:
   *
   */
  #include <linux/config.h>
  #include <linux/string.h>
  #include <linux/net.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/init.h>
  #include <linux/skbuff.h>
  #include <linux/netlink.h>
  #include <linux/rtnetlink.h>
  #include <linux/proc_fs.h>
  #include <linux/netdevice.h>
  #include <linux/timer.h>
  #include <linux/spinlock.h>
  #include <asm/atomic.h>
  #include <asm/uaccess.h>
  #include <net/neighbour.h>
  #include <net/dst.h>
  #include <net/dn.h>
  #include <net/dn_fib.h>
  #include <net/dn_neigh.h>
  #include <net/dn_dev.h>
  
  struct dn_fib_rule
  {
  	struct dn_fib_rule	*r_next;
  	atomic_t		r_clntref;
  	u32			r_preference;
  	unsigned char		r_table;
  	unsigned char		r_action;
  	unsigned char		r_dst_len;
  	unsigned char		r_src_len;
  	dn_address		r_src;
  	dn_address		r_srcmask;
  	dn_address		r_dst;
  	dn_address		r_dstmask;
  	u8			r_flags;
  #ifdef CONFIG_DECNET_ROUTE_FWMARK
  	u32			r_fwmark;
  #endif
  	int			r_ifindex;
  	char			r_ifname[IFNAMSIZ];
  	int			r_dead;
  };
  
  static struct dn_fib_rule default_rule = {
  	r_clntref:		ATOMIC_INIT(2),
  	r_preference:		0x7fff,
  	r_table:		DN_DEFAULT_TABLE,
  	r_action:		RTN_UNICAST
  };
  
  static struct dn_fib_rule *dn_fib_rules = &default_rule;
  static rwlock_t dn_fib_rules_lock = RW_LOCK_UNLOCKED;
  
  
  int dn_fib_rtm_delrule(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
  {
  	struct rtattr **rta = arg;
  	struct rtmsg *rtm = NLMSG_DATA(nlh);
  	struct dn_fib_rule *r, **rp;
  	int err = -ESRCH;
  
  	for(rp=&dn_fib_rules; (r=*rp) != NULL; rp = &r->r_next) {
  		if ((!rta[RTA_SRC-1] || memcmp(RTA_DATA(rta[RTA_SRC-1]), &r->r_src, 2) == 0) &&
  			rtm->rtm_src_len == r->r_src_len &&
  			rtm->rtm_dst_len == r->r_dst_len &&
  			(!rta[RTA_DST-1] || memcmp(RTA_DATA(rta[RTA_DST-1]), &r->r_dst, 2) == 0) &&
  #ifdef CONFIG_DECNET_ROUTE_FWMARK
  			(!rta[RTA_PROTOINFO-1] || memcmp(RTA_DATA(rta[RTA_PROTOINFO-1]), &r->r_fwmark, 4) == 0) &&
  #endif
  			(!rtm->rtm_type || rtm->rtm_type == r->r_action) &&
  			(!rta[RTA_PRIORITY-1] || memcmp(RTA_DATA(rta[RTA_PRIORITY-1]), &r->r_preference, 4) == 0) &&
  			(!rta[RTA_IIF-1] || strcmp(RTA_DATA(rta[RTA_IIF-1]), r->r_ifname) == 0) &&
  			(!rtm->rtm_table || (r && rtm->rtm_table == r->r_table))) {
  
  			err = -EPERM;
  			if (r == &default_rule)
  				break;
  
  			write_lock_bh(&dn_fib_rules_lock);
  			*rp = r->r_next;
  			r->r_dead = 1;
  			write_unlock_bh(&dn_fib_rules_lock);
  			dn_fib_rule_put(r);
  			err = 0;
  			break;
  		}
  	}
  
  	return err;
  }
  
  void dn_fib_rule_put(struct dn_fib_rule *r)
  {
  	if (atomic_dec_and_test(&r->r_clntref)) {
  		if (r->r_dead)
  			kfree(r);
  		else
  			printk(KERN_DEBUG "Attempt to free alive dn_fib_rule\n");
  	}
  }
  
  
  int dn_fib_rtm_newrule(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
  {
  	struct rtattr **rta = arg;
  	struct rtmsg *rtm = NLMSG_DATA(nlh);
  	struct dn_fib_rule *r, *new_r, **rp;
  	unsigned char table_id;
  
  	if (rtm->rtm_src_len > 16 || rtm->rtm_dst_len > 16)
  		return -EINVAL;
  
  	if (rta[RTA_IIF-1] && RTA_PAYLOAD(rta[RTA_IIF-1]) > IFNAMSIZ)
  		return -EINVAL;
  
  	if (rtm->rtm_type == RTN_NAT)
  		return -EINVAL;
  
  	table_id = rtm->rtm_table;
  	if (table_id == RT_TABLE_UNSPEC) {
  		struct dn_fib_table *tb;
  		if (rtm->rtm_type == RTN_UNICAST) {
  			if ((tb = dn_fib_empty_table()) == NULL)
  				return -ENOBUFS;
  			table_id = tb->n;
  		}
  	}
  
  	new_r = kmalloc(sizeof(*new_r), GFP_KERNEL);
  	if (!new_r)
  		return -ENOMEM;
  	memset(new_r, 0, sizeof(*new_r));
  	if (rta[RTA_SRC-1])
  		memcpy(&new_r->r_src, RTA_DATA(rta[RTA_SRC-1]), 2);
  	if (rta[RTA_DST-1])
  		memcpy(&new_r->r_dst, RTA_DATA(rta[RTA_DST-1]), 2);
  	new_r->r_src_len = rtm->rtm_src_len;
  	new_r->r_dst_len = rtm->rtm_dst_len;
  	new_r->r_srcmask = dnet_make_mask(rtm->rtm_src_len);
  	new_r->r_dstmask = dnet_make_mask(rtm->rtm_dst_len);
  #ifdef CONFIG_DECNET_ROUTE_FWMARK
  	if (rta[RTA_PROTOINFO-1])
  		memcpy(&new_r->r_fwmark, RTA_DATA(rta[RTA_PROTOINFO-1]), 4);
  #endif
  	new_r->r_action = rtm->rtm_type;
  	new_r->r_flags = rtm->rtm_flags;
  	if (rta[RTA_PRIORITY-1])
  		memcpy(&new_r->r_preference, RTA_DATA(rta[RTA_PRIORITY-1]), 4);
  	new_r->r_table = table_id;
  	if (rta[RTA_IIF-1]) {
  		struct net_device *dev;
  		memcpy(new_r->r_ifname, RTA_DATA(rta[RTA_IIF-1]), IFNAMSIZ);
  		new_r->r_ifname[IFNAMSIZ-1] = 0;
  		new_r->r_ifindex = -1;
  		dev = __dev_get_by_name(new_r->r_ifname);
  		if (dev)
  			new_r->r_ifindex = dev->ifindex;
  	}
  
  	rp = &dn_fib_rules;
  	if (!new_r->r_preference) {
  		r = dn_fib_rules;
  		if (r && (r = r->r_next) != NULL) {
  			rp = &dn_fib_rules->r_next;
  			if (r->r_preference)
  				new_r->r_preference = r->r_preference - 1;
  		}
  	}
  
  	while((r=*rp) != NULL) {
  		if (r->r_preference > new_r->r_preference)
  			break;
  		rp = &r->r_next;
  	}
  
  	new_r->r_next = r;
  	atomic_inc(&new_r->r_clntref);
  	write_lock_bh(&dn_fib_rules_lock);
  	*rp = new_r;
  	write_unlock_bh(&dn_fib_rules_lock);
  	return 0;
  }
  
  
  int dn_fib_lookup(struct dn_fib_key *key, struct dn_fib_res *res)
  {
  	struct dn_fib_rule *r, *policy;
  	struct dn_fib_table *tb;
  	dn_address saddr = key->src;
  	dn_address daddr = key->dst;
  	int err;
  
  	read_lock(&dn_fib_rules_lock);
  	for(r = dn_fib_rules; r; r = r->r_next) {
  		if (((saddr^r->r_src) & r->r_srcmask) ||
  		    ((daddr^r->r_dst) & r->r_dstmask) ||
  #ifdef CONFIG_DECNET_ROUTE_FWMARK
  		    (r->r_fwmark && r->r_fwmark != key->fwmark) ||
  #endif
  		    (r->r_ifindex && r->r_ifindex != key->iif))
  			continue;
  
  		switch(r->r_action) {
  			case RTN_UNICAST:
  				policy = r;
  				break;
  			case RTN_UNREACHABLE:
  				read_unlock(&dn_fib_rules_lock);
  				return -ENETUNREACH;
  			default:
  			case RTN_BLACKHOLE:
  				read_unlock(&dn_fib_rules_lock);
  				return -EINVAL;
  			case RTN_PROHIBIT:
  				read_unlock(&dn_fib_rules_lock);
  				return -EACCES;
  		}
  
  		if ((tb = dn_fib_get_table(r->r_table, 0)) == NULL)
  			continue;
  		err = tb->lookup(tb, key, res);
  		if (err == 0) {
  			res->r = policy;
  			if (policy)
  				atomic_inc(&policy->r_clntref);
  			read_unlock(&dn_fib_rules_lock);
  			return 0;
  		}
  		if (err < 0 && err != -EAGAIN) {
  			read_unlock(&dn_fib_rules_lock);
  			return err;
  		}
  	}
  
  	read_unlock(&dn_fib_rules_lock);
  	return -ESRCH;
  }
  
  static void dn_fib_rules_detach(struct net_device *dev)
  {
  	struct dn_fib_rule *r;
  
  	for(r = dn_fib_rules; r; r = r->r_next) {
  		if (r->r_ifindex == dev->ifindex) {
  			write_lock_bh(&dn_fib_rules_lock);
  			r->r_ifindex = -1;
  			write_unlock_bh(&dn_fib_rules_lock);
  		}
  	}
  }
  
  static void dn_fib_rules_attach(struct net_device *dev)
  {
  	struct dn_fib_rule *r;
  
  	for(r = dn_fib_rules; r; r = r->r_next) {
  		if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) {
  			write_lock_bh(&dn_fib_rules_lock);
  			r->r_ifindex = dev->ifindex;
  			write_unlock_bh(&dn_fib_rules_lock);
  		}
  	}
  }
  
  static int dn_fib_rules_event(struct notifier_block *this, unsigned long event, void *ptr)
  {
  	struct net_device *dev = ptr;
  
  	switch(event) {
  		case NETDEV_UNREGISTER:
  			dn_fib_rules_detach(dev);
  			dn_fib_sync_down(0, dev, 1);
  		case NETDEV_REGISTER:
  			dn_fib_rules_attach(dev);
  			dn_fib_sync_up(dev);
  	}
  
  	return NOTIFY_DONE;
  }
  
  
  static struct notifier_block dn_fib_rules_notifier = {
  	notifier_call:		dn_fib_rules_event,
  };
  
  static int dn_fib_fill_rule(struct sk_buff *skb, struct dn_fib_rule *r, struct netlink_callback *cb)
  {
  	struct rtmsg *rtm;
  	struct nlmsghdr *nlh;
  	unsigned char *b = skb->tail;
  
  
  	nlh = NLMSG_PUT(skb, NETLINK_CREDS(cb->skb)->pid, cb->nlh->nlmsg_seq, RTM_NEWRULE, sizeof(*rtm));
  	rtm = NLMSG_DATA(nlh);
  	rtm->rtm_family = AF_DECnet;
  	rtm->rtm_dst_len = r->r_dst_len;
  	rtm->rtm_src_len = r->r_src_len;
  	rtm->rtm_tos = 0;
  #ifdef CONFIG_DECNET_ROUTE_FWMARK
  	if (r->r_fwmark)
  		RTA_PUT(skb, RTA_PROTOINFO, 4, &r->r_fwmark);
  #endif
  	rtm->rtm_table = r->r_table;
  	rtm->rtm_protocol = 0;
  	rtm->rtm_scope = 0;
  	rtm->rtm_type = r->r_action;
  	rtm->rtm_flags = r->r_flags;
  
  	if (r->r_dst_len)
  		RTA_PUT(skb, RTA_DST, 2, &r->r_dst);
  	if (r->r_src_len)
  		RTA_PUT(skb, RTA_SRC, 2, &r->r_src);
  	if (r->r_ifname[0])
  		RTA_PUT(skb, RTA_IIF, IFNAMSIZ, &r->r_ifname);
  	if (r->r_preference)
  		RTA_PUT(skb, RTA_PRIORITY, 4, &r->r_preference);
  	nlh->nlmsg_len = skb->tail - b;
  	return skb->len;
  
  nlmsg_failure:
  rtattr_failure:
  	skb_put(skb, b - skb->tail);
  	return -1;
  }
  
  int dn_fib_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	int idx;
  	int s_idx = cb->args[0];
  	struct dn_fib_rule *r;
  
  	read_lock(&dn_fib_rules_lock);
  	for(r = dn_fib_rules, idx = 0; r; r = r->r_next, idx++) {
  		if (idx < s_idx)
  			continue;
  		if (dn_fib_fill_rule(skb, r, cb) < 0)
  			break;
  	}
  	read_unlock(&dn_fib_rules_lock);
  	cb->args[0] = idx;
  
  	return skb->len;
  }
  
  void __init dn_fib_rules_init(void)
  {
  	register_netdevice_notifier(&dn_fib_rules_notifier);
  }
  
  void __exit dn_fib_rules_cleanup(void)
  {
  	unregister_netdevice_notifier(&dn_fib_rules_notifier);
  }
  
  
  