// SPDX-License-Identifier: GPL-2.0

  #include <linux/rtnetlink.h>
  #include <linux/notifier.h>

  #include <linux/socket.h>

  #include <linux/kernel.h>

  #include <linux/export.h>

  #include <net/net_namespace.h>

  #include <net/fib_notifier.h>

  #include <net/netns/ipv4.h>
  #include <net/ip_fib.h>

  int call_fib4_notifier(struct notifier_block *nb, struct net *net,
  		       enum fib_event_type event_type,
  		       struct fib_notifier_info *info)

  {

  	info->family = AF_INET;
  	return call_fib_notifier(nb, net, event_type, info);

  }

  int call_fib4_notifiers(struct net *net, enum fib_event_type event_type,
  			struct fib_notifier_info *info)

  {

  	ASSERT_RTNL();
  
  	info->family = AF_INET;

  	net->ipv4.fib_seq++;

  	return call_fib_notifiers(net, event_type, info);

  }

  static unsigned int fib4_seq_read(struct net *net)

  {

  	ASSERT_RTNL();

  	return net->ipv4.fib_seq + fib4_rules_seq_read(net);

  }

  static int fib4_dump(struct net *net, struct notifier_block *nb)

  {

  	int err;
  
  	err = fib4_rules_dump(net, nb);
  	if (err)
  		return err;

  	fib_notify(net, nb);
  
  	return 0;

  }

  static const struct fib_notifier_ops fib4_notifier_ops_template = {
  	.family		= AF_INET,
  	.fib_seq_read	= fib4_seq_read,
  	.fib_dump	= fib4_dump,

  	.owner		= THIS_MODULE,

  };

  int __net_init fib4_notifier_init(struct net *net)
  {
  	struct fib_notifier_ops *ops;

  	net->ipv4.fib_seq = 0;

  	ops = fib_notifier_ops_register(&fib4_notifier_ops_template, net);
  	if (IS_ERR(ops))
  		return PTR_ERR(ops);
  	net->ipv4.notifier_ops = ops;

  	return 0;

  }

  void __net_exit fib4_notifier_exit(struct net *net)

  {

  	fib_notifier_ops_unregister(net->ipv4.notifier_ops);

  }