/*
   * xfrm6_policy.c: based on xfrm4_policy.c
   *
   * Authors:
   *	Mitsuru KANDA @USAGI
   * 	Kazunori MIYAZAWA @USAGI
   * 	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   * 		IPv6 support
   * 	YOSHIFUJI Hideaki
   * 		Split up af-specific portion

   *

   */

  #include <linux/err.h>
  #include <linux/kernel.h>

  #include <linux/netdevice.h>
  #include <net/addrconf.h>

  #include <net/dst.h>

  #include <net/xfrm.h>
  #include <net/ip.h>
  #include <net/ipv6.h>
  #include <net/ip6_route.h>

  #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)

  #include <net/mip6.h>
  #endif

  static struct xfrm_policy_afinfo xfrm6_policy_afinfo;

  static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos,

  					  const xfrm_address_t *saddr,
  					  const xfrm_address_t *daddr)

  {

  	struct flowi6 fl6;

  	struct dst_entry *dst;
  	int err;

  	memset(&fl6, 0, sizeof(fl6));
  	memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));

  	if (saddr)

  		memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));

  	dst = ip6_route_output(net, NULL, &fl6);

  
  	err = dst->error;
  	if (dst->error) {

  		dst_release(dst);

  		dst = ERR_PTR(err);
  	}
  
  	return dst;

  }

  static int xfrm6_get_saddr(struct net *net,
  			   xfrm_address_t *saddr, xfrm_address_t *daddr)

  {

  	struct dst_entry *dst;

  	struct net_device *dev;

  	dst = xfrm6_dst_lookup(net, 0, NULL, daddr);

  	if (IS_ERR(dst))
  		return -EHOSTUNREACH;

  	dev = ip6_dst_idev(dst)->dev;
  	ipv6_dev_get_saddr(dev_net(dev), dev,

  			   (struct in6_addr *)&daddr->a6, 0,

  			   (struct in6_addr *)&saddr->a6);

  	dst_release(dst);
  	return 0;

  }

  static int xfrm6_get_tos(const struct flowi *fl)

  {

  	return 0;
  }

  static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  			   int nfheader_len)
  {
  	if (dst->ops->family == AF_INET6) {
  		struct rt6_info *rt = (struct rt6_info*)dst;
  		if (rt->rt6i_node)
  			path->path_cookie = rt->rt6i_node->fn_sernum;
  	}
  
  	path->u.rt6.rt6i_nfheader_len = nfheader_len;
  
  	return 0;
  }

  static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,

  			  const struct flowi *fl)

  {
  	struct rt6_info *rt = (struct rt6_info*)xdst->route;

  	xdst->u.dst.dev = dev;
  	dev_hold(dev);

  	xdst->u.rt6.rt6i_idev = in6_dev_get(dev);

  	if (!xdst->u.rt6.rt6i_idev)
  		return -ENODEV;

  	xdst->u.rt6.rt6i_peer = rt->rt6i_peer;
  	if (rt->rt6i_peer)
  		atomic_inc(&rt->rt6i_peer->refcnt);

  	/* Sheit... I remember I did this right. Apparently,
  	 * it was magically lost, so this code needs audit */
  	xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
  						   RTF_LOCAL);
  	xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
  	xdst->u.rt6.rt6i_node = rt->rt6i_node;

  	if (rt->rt6i_node)
  		xdst->route_cookie = rt->rt6i_node->fn_sernum;

  	xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
  	xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
  	xdst->u.rt6.rt6i_src = rt->rt6i_src;

  	return 0;

  }
  
  static inline void

  _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)

  {

  	struct flowi6 *fl6 = &fl->u.ip6;

  	int onlyproto = 0;

  	u16 offset = skb_network_header_len(skb);

  	const struct ipv6hdr *hdr = ipv6_hdr(skb);

  	struct ipv6_opt_hdr *exthdr;

  	const unsigned char *nh = skb_network_header(skb);
  	u8 nexthdr = nh[IP6CB(skb)->nhoff];

  	memset(fl6, 0, sizeof(struct flowi6));
  	fl6->flowi6_mark = skb->mark;

  	fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
  	fl6->saddr = reverse ? hdr->daddr : hdr->saddr;

  	while (nh + offset + 1 < skb->data ||
  	       pskb_may_pull(skb, nh + offset + 1 - skb->data)) {

  		nh = skb_network_header(skb);
  		exthdr = (struct ipv6_opt_hdr *)(nh + offset);

  		switch (nexthdr) {

  		case NEXTHDR_FRAGMENT:
  			onlyproto = 1;

  		case NEXTHDR_ROUTING:
  		case NEXTHDR_HOP:
  		case NEXTHDR_DEST:
  			offset += ipv6_optlen(exthdr);
  			nexthdr = exthdr->nexthdr;

  			exthdr = (struct ipv6_opt_hdr *)(nh + offset);

  			break;
  
  		case IPPROTO_UDP:

  		case IPPROTO_UDPLITE:

  		case IPPROTO_TCP:
  		case IPPROTO_SCTP:

  		case IPPROTO_DCCP:

  			if (!onlyproto && (nh + offset + 4 < skb->data ||
  			     pskb_may_pull(skb, nh + offset + 4 - skb->data))) {

  				__be16 *ports = (__be16 *)exthdr;

  				fl6->fl6_sport = ports[!!reverse];
  				fl6->fl6_dport = ports[!reverse];

  			}

  			fl6->flowi6_proto = nexthdr;

  			return;
  
  		case IPPROTO_ICMPV6:

  			if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {

  				u8 *icmp = (u8 *)exthdr;

  				fl6->fl6_icmp_type = icmp[0];
  				fl6->fl6_icmp_code = icmp[1];

  			}

  			fl6->flowi6_proto = nexthdr;

  			return;

  #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)

  		case IPPROTO_MH:

  			if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {

  				struct ip6_mh *mh;
  				mh = (struct ip6_mh *)exthdr;

  				fl6->fl6_mh_type = mh->ip6mh_type;

  			}

  			fl6->flowi6_proto = nexthdr;

  			return;
  #endif

  		/* XXX Why are there these headers? */
  		case IPPROTO_AH:
  		case IPPROTO_ESP:
  		case IPPROTO_COMP:
  		default:

  			fl6->fl6_ipsec_spi = 0;

  			fl6->flowi6_proto = nexthdr;

  			return;

  		}

  	}
  }

  static inline int xfrm6_garbage_collect(struct dst_ops *ops)

  {

  	struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);
  
  	xfrm6_policy_afinfo.garbage_collect(net);

  	return dst_entries_get_fast(ops) > ops->gc_thresh * 2;

  }
  
  static void xfrm6_update_pmtu(struct dst_entry *dst, u32 mtu)
  {
  	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  	struct dst_entry *path = xdst->route;
  
  	path->ops->update_pmtu(path, mtu);
  }

  static void xfrm6_dst_destroy(struct dst_entry *dst)
  {
  	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
  
  	if (likely(xdst->u.rt6.rt6i_idev))
  		in6_dev_put(xdst->u.rt6.rt6i_idev);

  	dst_destroy_metrics_generic(dst);

  	if (likely(xdst->u.rt6.rt6i_peer))
  		inet_putpeer(xdst->u.rt6.rt6i_peer);

  	xfrm_dst_destroy(xdst);
  }
  
  static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
  			     int unregister)
  {
  	struct xfrm_dst *xdst;
  
  	if (!unregister)
  		return;
  
  	xdst = (struct xfrm_dst *)dst;
  	if (xdst->u.rt6.rt6i_idev->dev == dev) {

  		struct inet6_dev *loopback_idev =

  			in6_dev_get(dev_net(dev)->loopback_dev);

  		BUG_ON(!loopback_idev);
  
  		do {
  			in6_dev_put(xdst->u.rt6.rt6i_idev);
  			xdst->u.rt6.rt6i_idev = loopback_idev;
  			in6_dev_hold(loopback_idev);
  			xdst = (struct xfrm_dst *)xdst->u.dst.child;
  		} while (xdst->u.dst.xfrm);
  
  		__in6_dev_put(loopback_idev);
  	}
  
  	xfrm_dst_ifdown(dst, dev);
  }

  static struct dst_ops xfrm6_dst_ops = {
  	.family =		AF_INET6,

  	.protocol =		cpu_to_be16(ETH_P_IPV6),

  	.gc =			xfrm6_garbage_collect,
  	.update_pmtu =		xfrm6_update_pmtu,

  	.cow_metrics =		dst_cow_metrics_generic,

  	.destroy =		xfrm6_dst_destroy,
  	.ifdown =		xfrm6_dst_ifdown,

  	.local_out =		__ip6_local_out,

  	.gc_thresh =		1024,

  };
  
  static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
  	.family =		AF_INET6,

  	.dst_ops =		&xfrm6_dst_ops,
  	.dst_lookup =		xfrm6_dst_lookup,

  	.get_saddr = 		xfrm6_get_saddr,

  	.decode_session =	_decode_session6,

  	.get_tos =		xfrm6_get_tos,

  	.init_path =		xfrm6_init_path,

  	.fill_dst =		xfrm6_fill_dst,

  	.blackhole_route =	ip6_blackhole_route,

  };

  static int __init xfrm6_policy_init(void)

  {

  	return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);

  }
  
  static void xfrm6_policy_fini(void)
  {
  	xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
  }

  #ifdef CONFIG_SYSCTL

  static struct ctl_table xfrm6_policy_table[] = {
  	{

  		.procname       = "xfrm6_gc_thresh",

  		.data	   	= &init_net.xfrm.xfrm6_dst_ops.gc_thresh,

  		.maxlen	 	= sizeof(int),
  		.mode	   	= 0644,
  		.proc_handler   = proc_dointvec,
  	},
  	{ }
  };
  
  static struct ctl_table_header *sysctl_hdr;

  #endif

  int __init xfrm6_init(void)

  {

  	int ret;

  	unsigned int gc_thresh;

  	/*
  	 * We need a good default value for the xfrm6 gc threshold.
  	 * In ipv4 we set it to the route hash table size * 8, which
  	 * is half the size of the maximaum route cache for ipv4.  It
  	 * would be good to do the same thing for v6, except the table is
  	 * constructed differently here.  Here each table for a net namespace
  	 * can have FIB_TABLE_HASHSZ entries, so lets go with the same
  	 * computation that we used for ipv4 here.  Also, lets keep the initial
  	 * gc_thresh to a minimum of 1024, since, the ipv6 route cache defaults
  	 * to that as a minimum as well
  	 */
  	gc_thresh = FIB6_TABLE_HASHSZ * 8;
  	xfrm6_dst_ops.gc_thresh = (gc_thresh < 1024) ? 1024 : gc_thresh;

  	dst_entries_init(&xfrm6_dst_ops);

  
  	ret = xfrm6_policy_init();

  	if (ret) {
  		dst_entries_destroy(&xfrm6_dst_ops);

  		goto out;

  	}

  	ret = xfrm6_state_init();
  	if (ret)
  		goto out_policy;

  #ifdef CONFIG_SYSCTL

  	sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv6_ctl_path,
  						xfrm6_policy_table);

  #endif

  out:
  	return ret;
  out_policy:
  	xfrm6_policy_fini();
  	goto out;

  }
  
  void xfrm6_fini(void)
  {

  #ifdef CONFIG_SYSCTL

  	if (sysctl_hdr)
  		unregister_net_sysctl_table(sysctl_hdr);

  #endif

  	//xfrm6_input_fini();
  	xfrm6_policy_fini();
  	xfrm6_state_fini();

  	dst_entries_destroy(&xfrm6_dst_ops);

  }