/*
   *	Neighbour Discovery for IPv6

   *	Linux INET6 implementation

   *
   *	Authors:

   *	Pedro Roque		<roque@di.fc.ul.pt>

   *	Mike Shaver		<shaver@ingenia.com>
   *
   *	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.
   */
  
  /*
   *	Changes:
   *

   *	Alexey I. Froloff		:	RFC6106 (DNSSL) support

   *	Pierre Ynard			:	export userland ND options
   *						through netlink (RDNSS support)

   *	Lars Fenneberg			:	fixed MTU setting on receipt
   *						of an RA.

   *	Janos Farkas			:	kmalloc failure checks
   *	Alexey Kuznetsov		:	state machine reworked
   *						and moved to net/core.
   *	Pekka Savola			:	RFC2461 validation
   *	YOSHIFUJI Hideaki @USAGI	:	Verify ND options properly
   */

  #define pr_fmt(fmt) "ICMPv6: " fmt

  
  #include <linux/module.h>

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/sched.h>
  #include <linux/net.h>
  #include <linux/in6.h>
  #include <linux/route.h>
  #include <linux/init.h>
  #include <linux/rcupdate.h>

  #include <linux/slab.h>

  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif

  #include <linux/if_addr.h>

  #include <linux/if_arp.h>
  #include <linux/ipv6.h>
  #include <linux/icmpv6.h>
  #include <linux/jhash.h>
  
  #include <net/sock.h>
  #include <net/snmp.h>
  
  #include <net/ipv6.h>
  #include <net/protocol.h>
  #include <net/ndisc.h>
  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  #include <net/icmp.h>

  #include <net/netlink.h>
  #include <linux/rtnetlink.h>

  #include <net/flow.h>
  #include <net/ip6_checksum.h>

  #include <net/inet_common.h>

  #include <linux/proc_fs.h>
  
  #include <linux/netfilter.h>
  #include <linux/netfilter_ipv6.h>

  static u32 ndisc_hash(const void *pkey,
  		      const struct net_device *dev,

  		      __u32 *hash_rnd);

  static bool ndisc_key_eq(const struct neighbour *neigh, const void *pkey);

  static int ndisc_constructor(struct neighbour *neigh);
  static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb);
  static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb);
  static int pndisc_constructor(struct pneigh_entry *n);
  static void pndisc_destructor(struct pneigh_entry *n);
  static void pndisc_redo(struct sk_buff *skb);

  static const struct neigh_ops ndisc_generic_ops = {

  	.family =		AF_INET6,
  	.solicit =		ndisc_solicit,
  	.error_report =		ndisc_error_report,
  	.output =		neigh_resolve_output,
  	.connected_output =	neigh_connected_output,

  };

  static const struct neigh_ops ndisc_hh_ops = {

  	.family =		AF_INET6,
  	.solicit =		ndisc_solicit,
  	.error_report =		ndisc_error_report,
  	.output =		neigh_resolve_output,
  	.connected_output =	neigh_resolve_output,

  };

  static const struct neigh_ops ndisc_direct_ops = {

  	.family =		AF_INET6,

  	.output =		neigh_direct_output,
  	.connected_output =	neigh_direct_output,

  };
  
  struct neigh_table nd_tbl = {
  	.family =	AF_INET6,

  	.key_len =	sizeof(struct in6_addr),

  	.protocol =	cpu_to_be16(ETH_P_IPV6),

  	.hash =		ndisc_hash,

  	.key_eq =	ndisc_key_eq,

  	.constructor =	ndisc_constructor,
  	.pconstructor =	pndisc_constructor,
  	.pdestructor =	pndisc_destructor,
  	.proxy_redo =	pndisc_redo,
  	.id =		"ndisc_cache",
  	.parms = {

  		.tbl			= &nd_tbl,

  		.reachable_time		= ND_REACHABLE_TIME,

  		.data = {
  			[NEIGH_VAR_MCAST_PROBES] = 3,
  			[NEIGH_VAR_UCAST_PROBES] = 3,
  			[NEIGH_VAR_RETRANS_TIME] = ND_RETRANS_TIMER,
  			[NEIGH_VAR_BASE_REACHABLE_TIME] = ND_REACHABLE_TIME,
  			[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
  			[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
  			[NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
  			[NEIGH_VAR_PROXY_QLEN] = 64,
  			[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
  			[NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,
  		},

  	},
  	.gc_interval =	  30 * HZ,
  	.gc_thresh1 =	 128,
  	.gc_thresh2 =	 512,
  	.gc_thresh3 =	1024,
  };

  EXPORT_SYMBOL_GPL(nd_tbl);

  void __ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data,
  			      int data_len, int pad)

  {

  	int space = __ndisc_opt_addr_space(data_len, pad);

  	u8 *opt = skb_put(skb, space);

  
  	opt[0] = type;
  	opt[1] = space>>3;
  
  	memset(opt + 2, 0, pad);
  	opt   += pad;
  	space -= pad;
  
  	memcpy(opt+2, data, data_len);
  	data_len += 2;
  	opt += data_len;

  	space -= data_len;
  	if (space > 0)

  		memset(opt, 0, space);

  }

  EXPORT_SYMBOL_GPL(__ndisc_fill_addr_option);

  static inline void ndisc_fill_addr_option(struct sk_buff *skb, int type,

  					  void *data, u8 icmp6_type)

  {
  	__ndisc_fill_addr_option(skb, type, data, skb->dev->addr_len,
  				 ndisc_addr_option_pad(skb->dev->type));

  	ndisc_ops_fill_addr_option(skb->dev, skb, icmp6_type);
  }
  
  static inline void ndisc_fill_redirect_addr_option(struct sk_buff *skb,
  						   void *ha,
  						   const u8 *ops_data)
  {
  	ndisc_fill_addr_option(skb, ND_OPT_TARGET_LL_ADDR, ha, NDISC_REDIRECT);
  	ndisc_ops_fill_redirect_addr_option(skb->dev, skb, ops_data);

  }

  static struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur,
  					    struct nd_opt_hdr *end)
  {
  	int type;
  	if (!cur || !end || cur >= end)
  		return NULL;
  	type = cur->nd_opt_type;
  	do {
  		cur = ((void *)cur) + (cur->nd_opt_len << 3);

  	} while (cur < end && cur->nd_opt_type != type);

  	return cur <= end && cur->nd_opt_type == type ? cur : NULL;

  }

  static inline int ndisc_is_useropt(const struct net_device *dev,
  				   struct nd_opt_hdr *opt)

  {

  	return opt->nd_opt_type == ND_OPT_RDNSS ||

  		opt->nd_opt_type == ND_OPT_DNSSL ||
  		ndisc_ops_is_useropt(dev, opt->nd_opt_type);

  }

  static struct nd_opt_hdr *ndisc_next_useropt(const struct net_device *dev,
  					     struct nd_opt_hdr *cur,

  					     struct nd_opt_hdr *end)
  {
  	if (!cur || !end || cur >= end)
  		return NULL;
  	do {
  		cur = ((void *)cur) + (cur->nd_opt_len << 3);

  	} while (cur < end && !ndisc_is_useropt(dev, cur));
  	return cur <= end && ndisc_is_useropt(dev, cur) ? cur : NULL;

  }

  struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
  					  u8 *opt, int opt_len,

  					  struct ndisc_options *ndopts)

  {
  	struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)opt;
  
  	if (!nd_opt || opt_len < 0 || !ndopts)
  		return NULL;
  	memset(ndopts, 0, sizeof(*ndopts));
  	while (opt_len) {
  		int l;
  		if (opt_len < sizeof(struct nd_opt_hdr))
  			return NULL;
  		l = nd_opt->nd_opt_len << 3;
  		if (opt_len < l || l == 0)
  			return NULL;

  		if (ndisc_ops_parse_options(dev, nd_opt, ndopts))
  			goto next_opt;

  		switch (nd_opt->nd_opt_type) {
  		case ND_OPT_SOURCE_LL_ADDR:
  		case ND_OPT_TARGET_LL_ADDR:
  		case ND_OPT_MTU:

  		case ND_OPT_NONCE:

  		case ND_OPT_REDIRECT_HDR:
  			if (ndopts->nd_opt_array[nd_opt->nd_opt_type]) {

  				ND_PRINTK(2, warn,
  					  "%s: duplicated ND6 option found: type=%d
  ",
  					  __func__, nd_opt->nd_opt_type);

  			} else {
  				ndopts->nd_opt_array[nd_opt->nd_opt_type] = nd_opt;
  			}
  			break;
  		case ND_OPT_PREFIX_INFO:
  			ndopts->nd_opts_pi_end = nd_opt;

  			if (!ndopts->nd_opt_array[nd_opt->nd_opt_type])

  				ndopts->nd_opt_array[nd_opt->nd_opt_type] = nd_opt;
  			break;

  #ifdef CONFIG_IPV6_ROUTE_INFO
  		case ND_OPT_ROUTE_INFO:
  			ndopts->nd_opts_ri_end = nd_opt;
  			if (!ndopts->nd_opts_ri)
  				ndopts->nd_opts_ri = nd_opt;
  			break;
  #endif

  		default:

  			if (ndisc_is_useropt(dev, nd_opt)) {

  				ndopts->nd_useropts_end = nd_opt;
  				if (!ndopts->nd_useropts)
  					ndopts->nd_useropts = nd_opt;
  			} else {
  				/*
  				 * Unknown options must be silently ignored,
  				 * to accommodate future extension to the
  				 * protocol.
  				 */

  				ND_PRINTK(2, notice,
  					  "%s: ignored unsupported option; type=%d, len=%d
  ",
  					  __func__,
  					  nd_opt->nd_opt_type,
  					  nd_opt->nd_opt_len);

  			}

  		}

  next_opt:

  		opt_len -= l;
  		nd_opt = ((void *)nd_opt) + l;
  	}
  	return ndopts;
  }

  int ndisc_mc_map(const struct in6_addr *addr, char *buf, struct net_device *dev, int dir)

  {
  	switch (dev->type) {
  	case ARPHRD_ETHER:
  	case ARPHRD_IEEE802:	/* Not sure. Check it later. --ANK */
  	case ARPHRD_FDDI:
  		ipv6_eth_mc_map(addr, buf);
  		return 0;

  	case ARPHRD_ARCNET:
  		ipv6_arcnet_mc_map(addr, buf);
  		return 0;
  	case ARPHRD_INFINIBAND:

  		ipv6_ib_mc_map(addr, dev->broadcast, buf);

  		return 0;

  	case ARPHRD_IPGRE:
  		return ipv6_ipgre_mc_map(addr, dev->broadcast, buf);

  	default:
  		if (dir) {
  			memcpy(buf, dev->broadcast, dev->addr_len);
  			return 0;
  		}
  	}
  	return -EINVAL;
  }

  EXPORT_SYMBOL(ndisc_mc_map);

  static u32 ndisc_hash(const void *pkey,
  		      const struct net_device *dev,

  		      __u32 *hash_rnd)

  {

  	return ndisc_hashfn(pkey, dev, hash_rnd);

  }

  static bool ndisc_key_eq(const struct neighbour *n, const void *pkey)
  {
  	return neigh_key_eq128(n, pkey);
  }

  static int ndisc_constructor(struct neighbour *neigh)
  {

  	struct in6_addr *addr = (struct in6_addr *)&neigh->primary_key;

  	struct net_device *dev = neigh->dev;
  	struct inet6_dev *in6_dev;
  	struct neigh_parms *parms;

  	bool is_multicast = ipv6_addr_is_multicast(addr);

  	in6_dev = in6_dev_get(dev);

  	if (!in6_dev) {

  		return -EINVAL;
  	}
  
  	parms = in6_dev->nd_parms;
  	__neigh_parms_put(neigh->parms);
  	neigh->parms = neigh_parms_clone(parms);

  
  	neigh->type = is_multicast ? RTN_MULTICAST : RTN_UNICAST;

  	if (!dev->header_ops) {

  		neigh->nud_state = NUD_NOARP;
  		neigh->ops = &ndisc_direct_ops;

  		neigh->output = neigh_direct_output;

  	} else {
  		if (is_multicast) {
  			neigh->nud_state = NUD_NOARP;
  			ndisc_mc_map(addr, neigh->ha, dev, 1);
  		} else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
  			neigh->nud_state = NUD_NOARP;
  			memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
  			if (dev->flags&IFF_LOOPBACK)
  				neigh->type = RTN_LOCAL;
  		} else if (dev->flags&IFF_POINTOPOINT) {
  			neigh->nud_state = NUD_NOARP;
  			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
  		}

  		if (dev->header_ops->cache)

  			neigh->ops = &ndisc_hh_ops;
  		else
  			neigh->ops = &ndisc_generic_ops;
  		if (neigh->nud_state&NUD_VALID)
  			neigh->output = neigh->ops->connected_output;
  		else
  			neigh->output = neigh->ops->output;
  	}
  	in6_dev_put(in6_dev);
  	return 0;
  }
  
  static int pndisc_constructor(struct pneigh_entry *n)
  {

  	struct in6_addr *addr = (struct in6_addr *)&n->key;

  	struct in6_addr maddr;
  	struct net_device *dev = n->dev;

  	if (!dev || !__in6_dev_get(dev))

  		return -EINVAL;
  	addrconf_addr_solict_mult(addr, &maddr);
  	ipv6_dev_mc_inc(dev, &maddr);
  	return 0;
  }
  
  static void pndisc_destructor(struct pneigh_entry *n)
  {

  	struct in6_addr *addr = (struct in6_addr *)&n->key;

  	struct in6_addr maddr;
  	struct net_device *dev = n->dev;

  	if (!dev || !__in6_dev_get(dev))

  		return;
  	addrconf_addr_solict_mult(addr, &maddr);
  	ipv6_dev_mc_dec(dev, &maddr);
  }

  static struct sk_buff *ndisc_alloc_skb(struct net_device *dev,
  				       int len)
  {
  	int hlen = LL_RESERVED_SPACE(dev);
  	int tlen = dev->needed_tailroom;
  	struct sock *sk = dev_net(dev)->ipv6.ndisc_sk;
  	struct sk_buff *skb;

  	skb = alloc_skb(hlen + sizeof(struct ipv6hdr) + len + tlen, GFP_ATOMIC);

  	if (!skb) {

  		ND_PRINTK(0, err, "ndisc: %s failed to allocate an skb
  ",
  			  __func__);

  		return NULL;
  	}

  	skb->protocol = htons(ETH_P_IPV6);
  	skb->dev = dev;

  	skb_reserve(skb, hlen + sizeof(struct ipv6hdr));

  	skb_reset_transport_header(skb);

  	/* Manually assign socket ownership as we avoid calling
  	 * sock_alloc_send_pskb() to bypass wmem buffer limits
  	 */
  	skb_set_owner_w(skb, sk);

  	return skb;
  }

  static void ip6_nd_hdr(struct sk_buff *skb,

  		       const struct in6_addr *saddr,
  		       const struct in6_addr *daddr,

  		       int hop_limit, int len)

  {
  	struct ipv6hdr *hdr;

  	skb_push(skb, sizeof(*hdr));

  	skb_reset_network_header(skb);

  	hdr = ipv6_hdr(skb);
  
  	ip6_flow_hdr(hdr, 0, 0);
  
  	hdr->payload_len = htons(len);

  	hdr->nexthdr = IPPROTO_ICMPV6;
  	hdr->hop_limit = hop_limit;

  
  	hdr->saddr = *saddr;
  	hdr->daddr = *daddr;
  }

  static void ndisc_send_skb(struct sk_buff *skb,

  			   const struct in6_addr *daddr,

  			   const struct in6_addr *saddr)

  {

  	struct dst_entry *dst = skb_dst(skb);

  	struct net *net = dev_net(skb->dev);

  	struct sock *sk = net->ipv6.ndisc_sk;

  	struct inet6_dev *idev;
  	int err;

  	struct icmp6hdr *icmp6h = icmp6_hdr(skb);

  	u8 type;
  
  	type = icmp6h->icmp6_type;

  	if (!dst) {

  		struct flowi6 fl6;

  		int oif = skb->dev->ifindex;

  		icmpv6_flow_init(sk, &fl6, type, saddr, daddr, oif);

  		dst = icmp6_dst_alloc(skb->dev, &fl6);
  		if (IS_ERR(dst)) {
  			kfree_skb(skb);
  			return;
  		}
  
  		skb_dst_set(skb, dst);
  	}

  	icmp6h->icmp6_cksum = csum_ipv6_magic(saddr, daddr, skb->len,
  					      IPPROTO_ICMPV6,
  					      csum_partial(icmp6h,
  							   skb->len, 0));
  
  	ip6_nd_hdr(skb, saddr, daddr, inet6_sk(sk)->hop_limit, skb->len);

  	rcu_read_lock();
  	idev = __in6_dev_get(dst->dev);

  	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);

  	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
  		      net, sk, skb, NULL, dst->dev,

  		      dst_output);

  	if (!err) {

  		ICMP6MSGOUT_INC_STATS(net, idev, type);

  		ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);

  	}

  	rcu_read_unlock();

  }

  void ndisc_send_na(struct net_device *dev, const struct in6_addr *daddr,

  		   const struct in6_addr *solicited_addr,
  		   bool router, bool solicited, bool override, bool inc_opt)

  {

  	struct sk_buff *skb;

  	struct in6_addr tmpaddr;
  	struct inet6_ifaddr *ifp;

  	const struct in6_addr *src_addr;

  	struct nd_msg *msg;
  	int optlen = 0;

  
  	/* for anycast or proxy, solicited_addr != src_addr */

  	ifp = ipv6_get_ifaddr(dev_net(dev), solicited_addr, dev, 1);

  	if (ifp) {
  		src_addr = solicited_addr;
  		if (ifp->flags & IFA_F_OPTIMISTIC)

  			override = false;

  		inc_opt |= ifp->idev->cnf.force_tllao;

  		in6_ifa_put(ifp);
  	} else {

  		if (ipv6_dev_get_saddr(dev_net(dev), dev, daddr,

  				       inet6_sk(dev_net(dev)->ipv6.ndisc_sk)->srcprefs,

  				       &tmpaddr))

  			return;
  		src_addr = &tmpaddr;
  	}

  	if (!dev->addr_len)
  		inc_opt = 0;
  	if (inc_opt)

  		optlen += ndisc_opt_addr_space(dev,
  					       NDISC_NEIGHBOUR_ADVERTISEMENT);

  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);

  	if (!skb)
  		return;

  	msg = (struct nd_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct nd_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT,
  			.icmp6_router = router,
  			.icmp6_solicited = solicited,
  			.icmp6_override = override,
  		},
  		.target = *solicited_addr,
  	};
  
  	if (inc_opt)
  		ndisc_fill_addr_option(skb, ND_OPT_TARGET_LL_ADDR,

  				       dev->dev_addr,
  				       NDISC_NEIGHBOUR_ADVERTISEMENT);

  	ndisc_send_skb(skb, daddr, src_addr);

  }

  static void ndisc_send_unsol_na(struct net_device *dev)
  {
  	struct inet6_dev *idev;
  	struct inet6_ifaddr *ifa;

  
  	idev = in6_dev_get(dev);
  	if (!idev)
  		return;
  
  	read_lock_bh(&idev->lock);
  	list_for_each_entry(ifa, &idev->addr_list, if_list) {

  		ndisc_send_na(dev, &in6addr_linklocal_allnodes, &ifa->addr,

  			      /*router=*/ !!idev->cnf.forwarding,
  			      /*solicited=*/ false, /*override=*/ true,
  			      /*inc_opt=*/ true);
  	}
  	read_unlock_bh(&idev->lock);
  
  	in6_dev_put(idev);
  }

  void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,

  		   const struct in6_addr *daddr, const struct in6_addr *saddr,
  		   u64 nonce)

  {

  	struct sk_buff *skb;

  	struct in6_addr addr_buf;

  	int inc_opt = dev->addr_len;
  	int optlen = 0;
  	struct nd_msg *msg;

  	if (!saddr) {

  		if (ipv6_get_lladdr(dev, &addr_buf,
  				   (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))

  			return;
  		saddr = &addr_buf;
  	}

  	if (ipv6_addr_any(saddr))

  		inc_opt = false;

  	if (inc_opt)

  		optlen += ndisc_opt_addr_space(dev,
  					       NDISC_NEIGHBOUR_SOLICITATION);

  	if (nonce != 0)
  		optlen += 8;

  
  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);

  	if (!skb)
  		return;

  	msg = (struct nd_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct nd_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_NEIGHBOUR_SOLICITATION,
  		},
  		.target = *solicit,
  	};
  
  	if (inc_opt)
  		ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR,

  				       dev->dev_addr,
  				       NDISC_NEIGHBOUR_SOLICITATION);

  	if (nonce != 0) {
  		u8 *opt = skb_put(skb, 8);
  
  		opt[0] = ND_OPT_NONCE;
  		opt[1] = 8 >> 3;
  		memcpy(opt + 2, &nonce, 6);
  	}

  	ndisc_send_skb(skb, daddr, saddr);

  }

  void ndisc_send_rs(struct net_device *dev, const struct in6_addr *saddr,
  		   const struct in6_addr *daddr)

  {

  	struct sk_buff *skb;

  	struct rs_msg *msg;

  	int send_sllao = dev->addr_len;

  	int optlen = 0;

  
  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  	/*
  	 * According to section 2.2 of RFC 4429, we must not
  	 * send router solicitations with a sllao from
  	 * optimistic addresses, but we may send the solicitation
  	 * if we don't include the sllao.  So here we check
  	 * if our address is optimistic, and if so, we

  	 * suppress the inclusion of the sllao.

  	 */
  	if (send_sllao) {

  		struct inet6_ifaddr *ifp = ipv6_get_ifaddr(dev_net(dev), saddr,

  							   dev, 1);

  		if (ifp) {
  			if (ifp->flags & IFA_F_OPTIMISTIC)  {

  				send_sllao = 0;

  			}

  			in6_ifa_put(ifp);

  		} else {
  			send_sllao = 0;
  		}
  	}
  #endif

  	if (send_sllao)

  		optlen += ndisc_opt_addr_space(dev, NDISC_ROUTER_SOLICITATION);

  
  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);

  	if (!skb)
  		return;

  	msg = (struct rs_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct rs_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_ROUTER_SOLICITATION,
  		},
  	};
  
  	if (send_sllao)
  		ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR,

  				       dev->dev_addr,
  				       NDISC_ROUTER_SOLICITATION);

  	ndisc_send_skb(skb, daddr, saddr);

  }

  
  static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb)
  {
  	/*
  	 *	"The sender MUST return an ICMP
  	 *	 destination unreachable"
  	 */
  	dst_link_failure(skb);
  	kfree_skb(skb);
  }
  
  /* Called with locked neigh: either read or both */
  
  static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
  {
  	struct in6_addr *saddr = NULL;
  	struct in6_addr mcaddr;
  	struct net_device *dev = neigh->dev;
  	struct in6_addr *target = (struct in6_addr *)&neigh->primary_key;
  	int probes = atomic_read(&neigh->probes);

  	if (skb && ipv6_chk_addr_and_flags(dev_net(dev), &ipv6_hdr(skb)->saddr,
  					   dev, 1,
  					   IFA_F_TENTATIVE|IFA_F_OPTIMISTIC))

  		saddr = &ipv6_hdr(skb)->saddr;

  	probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
  	if (probes < 0) {

  		if (!(neigh->nud_state & NUD_VALID)) {

  			ND_PRINTK(1, dbg,
  				  "%s: trying to ucast probe in NUD_INVALID: %pI6
  ",
  				  __func__, target);

  		}

  		ndisc_send_ns(dev, target, target, saddr, 0);

  	} else if ((probes -= NEIGH_VAR(neigh->parms, APP_PROBES)) < 0) {

  		neigh_app_ns(neigh);

  	} else {
  		addrconf_addr_solict_mult(target, &mcaddr);

  		ndisc_send_ns(dev, target, &mcaddr, saddr, 0);

  	}
  }

  static int pndisc_is_router(const void *pkey,
  			    struct net_device *dev)

  {
  	struct pneigh_entry *n;

  	int ret = -1;

  
  	read_lock_bh(&nd_tbl.lock);

  	n = __pneigh_lookup(&nd_tbl, dev_net(dev), pkey, dev);
  	if (n)
  		ret = !!(n->flags & NTF_ROUTER);

  	read_unlock_bh(&nd_tbl.lock);

  	return ret;

  }

  void ndisc_update(const struct net_device *dev, struct neighbour *neigh,
  		  const u8 *lladdr, u8 new, u32 flags, u8 icmp6_type,
  		  struct ndisc_options *ndopts)
  {
  	neigh_update(neigh, lladdr, new, flags);
  	/* report ndisc ops about neighbour update */
  	ndisc_ops_update(dev, neigh, flags, icmp6_type, ndopts);
  }

  static void ndisc_recv_ns(struct sk_buff *skb)
  {

  	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);

  	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
  	const struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;

  	u8 *lladdr = NULL;

  	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +

  				    offsetof(struct nd_msg, opt));

  	struct ndisc_options ndopts;
  	struct net_device *dev = skb->dev;
  	struct inet6_ifaddr *ifp;
  	struct inet6_dev *idev = NULL;
  	struct neighbour *neigh;
  	int dad = ipv6_addr_any(saddr);

  	bool inc;

  	int is_router = -1;

  	u64 nonce = 0;

  	if (skb->len < sizeof(struct nd_msg)) {
  		ND_PRINTK(2, warn, "NS: packet too short
  ");
  		return;
  	}

  	if (ipv6_addr_is_multicast(&msg->target)) {

  		ND_PRINTK(2, warn, "NS: multicast target address
  ");

  		return;
  	}
  
  	/*
  	 * RFC2461 7.1.1:
  	 * DAD has to be destined for solicited node multicast address.
  	 */

  	if (dad && !ipv6_addr_is_solict_mult(daddr)) {

  		ND_PRINTK(2, warn, "NS: bad DAD packet (wrong destination)
  ");

  		return;
  	}

  	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {

  		ND_PRINTK(2, warn, "NS: invalid ND options
  ");

  		return;
  	}
  
  	if (ndopts.nd_opts_src_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr, dev);
  		if (!lladdr) {

  			ND_PRINTK(2, warn,
  				  "NS: invalid link-layer address length
  ");

  			return;
  		}
  
  		/* RFC2461 7.1.1:

  		 *	If the IP source address is the unspecified address,
  		 *	there MUST NOT be source link-layer address option

  		 *	in the message.
  		 */
  		if (dad) {

  			ND_PRINTK(2, warn,
  				  "NS: bad DAD packet (link-layer address option)
  ");

  			return;
  		}
  	}

  	if (ndopts.nd_opts_nonce)
  		memcpy(&nonce, (u8 *)(ndopts.nd_opts_nonce + 1), 6);

  
  	inc = ipv6_addr_is_multicast(daddr);

  	ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);

  	if (ifp) {

  have_ifp:

  		if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
  			if (dad) {

  				if (nonce != 0 && ifp->dad_nonce == nonce) {
  					u8 *np = (u8 *)&nonce;
  					/* Matching nonce if looped back */
  					ND_PRINTK(2, notice,
  						  "%s: IPv6 DAD loopback for address %pI6c nonce %pM ignored
  ",
  						  ifp->idev->dev->name,
  						  &ifp->addr, np);
  					goto out;
  				}

  				/*
  				 * We are colliding with another node
  				 * who is doing DAD
  				 * so fail our DAD process
  				 */
  				addrconf_dad_failure(ifp);

  				return;

  			} else {
  				/*
  				 * This is not a dad solicitation.
  				 * If we are an optimistic node,
  				 * we should respond.
  				 * Otherwise, we should ignore it.
  				 */
  				if (!(ifp->flags & IFA_F_OPTIMISTIC))

  					goto out;

  			}

  		}
  
  		idev = ifp->idev;
  	} else {

  		struct net *net = dev_net(dev);

  		/* perhaps an address on the master device */
  		if (netif_is_l3_slave(dev)) {
  			struct net_device *mdev;
  
  			mdev = netdev_master_upper_dev_get_rcu(dev);
  			if (mdev) {
  				ifp = ipv6_get_ifaddr(net, &msg->target, mdev, 1);
  				if (ifp)
  					goto have_ifp;
  			}
  		}

  		idev = in6_dev_get(dev);
  		if (!idev) {
  			/* XXX: count this drop? */
  			return;
  		}

  		if (ipv6_chk_acast_addr(net, dev, &msg->target) ||

  		    (idev->cnf.forwarding &&

  		     (net->ipv6.devconf_all->proxy_ndp || idev->cnf.proxy_ndp) &&

  		     (is_router = pndisc_is_router(&msg->target, dev)) >= 0)) {

  			if (!(NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED) &&

  			    skb->pkt_type != PACKET_HOST &&

  			    inc &&

  			    NEIGH_VAR(idev->nd_parms, PROXY_DELAY) != 0) {

  				/*
  				 * for anycast or proxy,

  				 * sender should delay its response
  				 * by a random time between 0 and

  				 * MAX_ANYCAST_DELAY_TIME seconds.
  				 * (RFC2461) -- yoshfuji
  				 */
  				struct sk_buff *n = skb_clone(skb, GFP_ATOMIC);
  				if (n)
  					pneigh_enqueue(&nd_tbl, idev->nd_parms, n);
  				goto out;
  			}
  		} else
  			goto out;
  	}

  	if (is_router < 0)

  		is_router = idev->cnf.forwarding;

  	if (dad) {

  		ndisc_send_na(dev, &in6addr_linklocal_allnodes, &msg->target,

  			      !!is_router, false, (ifp != NULL), true);

  		goto out;
  	}
  
  	if (inc)
  		NEIGH_CACHE_STAT_INC(&nd_tbl, rcv_probes_mcast);
  	else
  		NEIGH_CACHE_STAT_INC(&nd_tbl, rcv_probes_ucast);

  	/*

  	 *	update / create cache entry
  	 *	for the source address
  	 */
  	neigh = __neigh_lookup(&nd_tbl, saddr, dev,
  			       !inc || lladdr || !dev->addr_len);
  	if (neigh)

  		ndisc_update(dev, neigh, lladdr, NUD_STALE,

  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|

  			     NEIGH_UPDATE_F_OVERRIDE,
  			     NDISC_NEIGHBOUR_SOLICITATION, &ndopts);

  	if (neigh || !dev->header_ops) {

  		ndisc_send_na(dev, saddr, &msg->target, !!is_router,

  			      true, (ifp != NULL && inc), inc);

  		if (neigh)
  			neigh_release(neigh);
  	}
  
  out:
  	if (ifp)
  		in6_ifa_put(ifp);
  	else
  		in6_dev_put(idev);

  }
  
  static void ndisc_recv_na(struct sk_buff *skb)
  {

  	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);

  	struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;

  	const struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;

  	u8 *lladdr = NULL;

  	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +

  				    offsetof(struct nd_msg, opt));

  	struct ndisc_options ndopts;
  	struct net_device *dev = skb->dev;

  	struct inet6_dev *idev = __in6_dev_get(dev);

  	struct inet6_ifaddr *ifp;
  	struct neighbour *neigh;
  
  	if (skb->len < sizeof(struct nd_msg)) {

  		ND_PRINTK(2, warn, "NA: packet too short
  ");

  		return;
  	}
  
  	if (ipv6_addr_is_multicast(&msg->target)) {

  		ND_PRINTK(2, warn, "NA: target address is multicast
  ");

  		return;
  	}
  
  	if (ipv6_addr_is_multicast(daddr) &&
  	    msg->icmph.icmp6_solicited) {

  		ND_PRINTK(2, warn, "NA: solicited NA is multicasted
  ");

  		return;
  	}

  	/* For some 802.11 wireless deployments (and possibly other networks),
  	 * there will be a NA proxy and unsolicitd packets are attacks
  	 * and thus should not be accepted.
  	 */
  	if (!msg->icmph.icmp6_solicited && idev &&
  	    idev->cnf.drop_unsolicited_na)
  		return;

  	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {

  		ND_PRINTK(2, warn, "NS: invalid ND option
  ");

  		return;
  	}
  	if (ndopts.nd_opts_tgt_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_tgt_lladdr, dev);
  		if (!lladdr) {

  			ND_PRINTK(2, warn,
  				  "NA: invalid link-layer address length
  ");

  			return;
  		}
  	}

  	ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);

  	if (ifp) {

  		if (skb->pkt_type != PACKET_LOOPBACK
  		    && (ifp->flags & IFA_F_TENTATIVE)) {
  				addrconf_dad_failure(ifp);
  				return;

  		}
  		/* What should we make now? The advertisement
  		   is invalid, but ndisc specs say nothing
  		   about it. It could be misconfiguration, or
  		   an smart proxy agent tries to help us :-)

  
  		   We should not print the error if NA has been
  		   received from loopback - it is just our own
  		   unsolicited advertisement.

  		 */

  		if (skb->pkt_type != PACKET_LOOPBACK)

  			ND_PRINTK(1, warn,
  				  "NA: someone advertises our address %pI6 on %s!
  ",
  				  &ifp->addr, ifp->idev->dev->name);

  		in6_ifa_put(ifp);
  		return;
  	}
  	neigh = neigh_lookup(&nd_tbl, &msg->target, dev);
  
  	if (neigh) {
  		u8 old_flags = neigh->flags;

  		struct net *net = dev_net(dev);

  
  		if (neigh->nud_state & NUD_FAILED)
  			goto out;

  		/*
  		 * Don't update the neighbor cache entry on a proxy NA from
  		 * ourselves because either the proxied node is off link or it
  		 * has already sent a NA to us.
  		 */
  		if (lladdr && !memcmp(lladdr, dev->dev_addr, dev->addr_len) &&

  		    net->ipv6.devconf_all->forwarding && net->ipv6.devconf_all->proxy_ndp &&
  		    pneigh_lookup(&nd_tbl, net, &msg->target, dev, 0)) {

  			/* XXX: idev->cnf.proxy_ndp */

  			goto out;

  		}

  		ndisc_update(dev, neigh, lladdr,

  			     msg->icmph.icmp6_solicited ? NUD_REACHABLE : NUD_STALE,
  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     (msg->icmph.icmp6_override ? NEIGH_UPDATE_F_OVERRIDE : 0)|
  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER|

  			     (msg->icmph.icmp6_router ? NEIGH_UPDATE_F_ISROUTER : 0),
  			     NDISC_NEIGHBOUR_ADVERTISEMENT, &ndopts);

  
  		if ((old_flags & ~neigh->flags) & NTF_ROUTER) {
  			/*
  			 * Change: router to host
  			 */

  			rt6_clean_tohost(dev_net(dev),  saddr);

  		}
  
  out:
  		neigh_release(neigh);
  	}
  }
  
  static void ndisc_recv_rs(struct sk_buff *skb)
  {

  	struct rs_msg *rs_msg = (struct rs_msg *)skb_transport_header(skb);

  	unsigned long ndoptlen = skb->len - sizeof(*rs_msg);
  	struct neighbour *neigh;
  	struct inet6_dev *idev;

  	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;

  	struct ndisc_options ndopts;
  	u8 *lladdr = NULL;
  
  	if (skb->len < sizeof(*rs_msg))
  		return;

  	idev = __in6_dev_get(skb->dev);

  	if (!idev) {

  		ND_PRINTK(1, err, "RS: can't find in6 device
  ");

  		return;
  	}
  
  	/* Don't accept RS if we're not in router mode */
  	if (!idev->cnf.forwarding)
  		goto out;
  
  	/*
  	 * Don't update NCE if src = ::;
  	 * this implies that the source node has no ip address assigned yet.
  	 */
  	if (ipv6_addr_any(saddr))
  		goto out;
  
  	/* Parse ND options */

  	if (!ndisc_parse_options(skb->dev, rs_msg->opt, ndoptlen, &ndopts)) {

  		ND_PRINTK(2, notice, "NS: invalid ND option, ignored
  ");

  		goto out;
  	}
  
  	if (ndopts.nd_opts_src_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
  					     skb->dev);
  		if (!lladdr)
  			goto out;
  	}
  
  	neigh = __neigh_lookup(&nd_tbl, saddr, skb->dev, 1);
  	if (neigh) {

  		ndisc_update(skb->dev, neigh, lladdr, NUD_STALE,

  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE|

  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER,
  			     NDISC_ROUTER_SOLICITATION, &ndopts);

  		neigh_release(neigh);
  	}
  out:

  	return;

  }

  static void ndisc_ra_useropt(struct sk_buff *ra, struct nd_opt_hdr *opt)
  {
  	struct icmp6hdr *icmp6h = (struct icmp6hdr *)skb_transport_header(ra);
  	struct sk_buff *skb;
  	struct nlmsghdr *nlh;
  	struct nduseroptmsg *ndmsg;

  	struct net *net = dev_net(ra->dev);

  	int err;
  	int base_size = NLMSG_ALIGN(sizeof(struct nduseroptmsg)
  				    + (opt->nd_opt_len << 3));
  	size_t msg_size = base_size + nla_total_size(sizeof(struct in6_addr));
  
  	skb = nlmsg_new(msg_size, GFP_ATOMIC);

  	if (!skb) {

  		err = -ENOBUFS;
  		goto errout;
  	}
  
  	nlh = nlmsg_put(skb, 0, 0, RTM_NEWNDUSEROPT, base_size, 0);

  	if (!nlh) {

  		goto nla_put_failure;
  	}
  
  	ndmsg = nlmsg_data(nlh);
  	ndmsg->nduseropt_family = AF_INET6;

  	ndmsg->nduseropt_ifindex = ra->dev->ifindex;

  	ndmsg->nduseropt_icmp_type = icmp6h->icmp6_type;
  	ndmsg->nduseropt_icmp_code = icmp6h->icmp6_code;
  	ndmsg->nduseropt_opts_len = opt->nd_opt_len << 3;
  
  	memcpy(ndmsg + 1, opt, opt->nd_opt_len << 3);

  	if (nla_put_in6_addr(skb, NDUSEROPT_SRCADDR, &ipv6_hdr(ra)->saddr))

  		goto nla_put_failure;

  	nlmsg_end(skb, nlh);

  	rtnl_notify(skb, net, 0, RTNLGRP_ND_USEROPT, NULL, GFP_ATOMIC);

  	return;
  
  nla_put_failure:
  	nlmsg_free(skb);
  	err = -EMSGSIZE;
  errout:

  	rtnl_set_sk_err(net, RTNLGRP_ND_USEROPT, err);

  }

  static void ndisc_router_discovery(struct sk_buff *skb)
  {

  	struct ra_msg *ra_msg = (struct ra_msg *)skb_transport_header(skb);

  	struct neighbour *neigh = NULL;
  	struct inet6_dev *in6_dev;

  	struct rt6_info *rt = NULL;

  	int lifetime;
  	struct ndisc_options ndopts;
  	int optlen;

  	unsigned int pref = 0;

  	__u32 old_if_flags;

  	bool send_ifinfo_notify = false;

  	__u8 *opt = (__u8 *)(ra_msg + 1);

  	optlen = (skb_tail_pointer(skb) - skb_transport_header(skb)) -
  		sizeof(struct ra_msg);

  	ND_PRINTK(2, info,
  		  "RA: %s, dev: %s
  ",
  		  __func__, skb->dev->name);

  	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {

  		ND_PRINTK(2, warn, "RA: source address is not link-local
  ");

  		return;
  	}
  	if (optlen < 0) {

  		ND_PRINTK(2, warn, "RA: packet too short
  ");

  		return;
  	}

  #ifdef CONFIG_IPV6_NDISC_NODETYPE

  	if (skb->ndisc_nodetype == NDISC_NODETYPE_HOST) {

  		ND_PRINTK(2, warn, "RA: from host or unauthorized router
  ");

  		return;
  	}

  #endif

  	/*
  	 *	set the RA_RECV flag in the interface
  	 */

  	in6_dev = __in6_dev_get(skb->dev);

  	if (!in6_dev) {

  		ND_PRINTK(0, err, "RA: can't find inet6 device for %s
  ",
  			  skb->dev->name);

  		return;
  	}

  	if (!ndisc_parse_options(skb->dev, opt, optlen, &ndopts)) {

  		ND_PRINTK(2, warn, "RA: invalid ND options
  ");

  		return;
  	}

  	if (!ipv6_accept_ra(in6_dev)) {
  		ND_PRINTK(2, info,
  			  "RA: %s, did not accept ra for dev: %s
  ",
  			  __func__, skb->dev->name);

  		goto skip_linkparms;

  	}

  #ifdef CONFIG_IPV6_NDISC_NODETYPE

  	/* skip link-specific parameters from interior routers */

  	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT) {
  		ND_PRINTK(2, info,
  			  "RA: %s, nodetype is NODEFAULT, dev: %s
  ",
  			  __func__, skb->dev->name);

  		goto skip_linkparms;

  	}

  #endif

  	if (in6_dev->if_flags & IF_RS_SENT) {
  		/*
  		 *	flag that an RA was received after an RS was sent
  		 *	out on this interface.
  		 */
  		in6_dev->if_flags |= IF_RA_RCVD;
  	}
  
  	/*
  	 * Remember the managed/otherconf flags from most recently
  	 * received RA message (RFC 2462) -- yoshfuji
  	 */

  	old_if_flags = in6_dev->if_flags;

  	in6_dev->if_flags = (in6_dev->if_flags & ~(IF_RA_MANAGED |
  				IF_RA_OTHERCONF)) |
  				(ra_msg->icmph.icmp6_addrconf_managed ?
  					IF_RA_MANAGED : 0) |
  				(ra_msg->icmph.icmp6_addrconf_other ?
  					IF_RA_OTHERCONF : 0);

  	if (old_if_flags != in6_dev->if_flags)

  		send_ifinfo_notify = true;

  	if (!in6_dev->cnf.accept_ra_defrtr) {
  		ND_PRINTK(2, info,
  			  "RA: %s, defrtr is false for dev: %s
  ",
  			  __func__, skb->dev->name);

  		goto skip_defrtr;

  	}

  	/* Do not accept RA with source-addr found on local machine unless
  	 * accept_ra_from_local is set to true.
  	 */

  	if (!in6_dev->cnf.accept_ra_from_local &&
  	    ipv6_chk_addr(dev_net(in6_dev->dev), &ipv6_hdr(skb)->saddr,

  			  in6_dev->dev, 0)) {

  		ND_PRINTK(2, info,

  			  "RA from local address detected on dev: %s: default router ignored
  ",
  			  skb->dev->name);

  		goto skip_defrtr;

  	}

  	lifetime = ntohs(ra_msg->icmph.icmp6_rt_lifetime);

  #ifdef CONFIG_IPV6_ROUTER_PREF
  	pref = ra_msg->icmph.icmp6_router_pref;
  	/* 10b is handled as if it were 00b (medium) */

  	if (pref == ICMPV6_ROUTER_PREF_INVALID ||

  	    !in6_dev->cnf.accept_ra_rtr_pref)

  		pref = ICMPV6_ROUTER_PREF_MEDIUM;
  #endif

  	rt = rt6_get_dflt_router(&ipv6_hdr(skb)->saddr, skb->dev);

  	if (rt) {
  		neigh = dst_neigh_lookup(&rt->dst, &ipv6_hdr(skb)->saddr);
  		if (!neigh) {

  			ND_PRINTK(0, err,
  				  "RA: %s got default router without neighbour
  ",
  				  __func__);

  			ip6_rt_put(rt);

  			return;
  		}
  	}

  	if (rt && lifetime == 0) {

  		ip6_del_rt(rt);

  		rt = NULL;
  	}

  	ND_PRINTK(3, info, "RA: rt: %p  lifetime: %d, for dev: %s
  ",
  		  rt, lifetime, skb->dev->name);

  	if (!rt && lifetime) {

  		ND_PRINTK(3, info, "RA: adding default router
  ");

  		rt = rt6_add_dflt_router(&ipv6_hdr(skb)->saddr, skb->dev, pref);

  		if (!rt) {

  			ND_PRINTK(0, err,
  				  "RA: %s failed to add default route
  ",
  				  __func__);

  			return;
  		}

  		neigh = dst_neigh_lookup(&rt->dst, &ipv6_hdr(skb)->saddr);

  		if (!neigh) {

  			ND_PRINTK(0, err,
  				  "RA: %s got default router without neighbour
  ",
  				  __func__);

  			ip6_rt_put(rt);

  			return;
  		}
  		neigh->flags |= NTF_ROUTER;

  	} else if (rt) {

  		rt->rt6i_flags = (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);

  	}
  
  	if (rt)

  		rt6_set_expires(rt, jiffies + (HZ * lifetime));

  	if (in6_dev->cnf.accept_ra_min_hop_limit < 256 &&
  	    ra_msg->icmph.icmp6_hop_limit) {
  		if (in6_dev->cnf.accept_ra_min_hop_limit <= ra_msg->icmph.icmp6_hop_limit) {

  			in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;

  			if (rt)
  				dst_metric_set(&rt->dst, RTAX_HOPLIMIT,
  					       ra_msg->icmph.icmp6_hop_limit);

  		} else {

  			ND_PRINTK(2, warn, "RA: Got route advertisement with lower hop_limit than minimum
  ");

  		}

  	}

  skip_defrtr:

  	/*
  	 *	Update Reachable Time and Retrans Timer
  	 */
  
  	if (in6_dev->nd_parms) {
  		unsigned long rtime = ntohl(ra_msg->retrans_timer);
  
  		if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/HZ) {
  			rtime = (rtime*HZ)/1000;
  			if (rtime < HZ/10)
  				rtime = HZ/10;

  			NEIGH_VAR_SET(in6_dev->nd_parms, RETRANS_TIME, rtime);

  			in6_dev->tstamp = jiffies;

  			send_ifinfo_notify = true;

  		}
  
  		rtime = ntohl(ra_msg->reachable_time);
  		if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/(3*HZ)) {
  			rtime = (rtime*HZ)/1000;
  
  			if (rtime < HZ/10)
  				rtime = HZ/10;

  			if (rtime != NEIGH_VAR(in6_dev->nd_parms, BASE_REACHABLE_TIME)) {
  				NEIGH_VAR_SET(in6_dev->nd_parms,
  					      BASE_REACHABLE_TIME, rtime);
  				NEIGH_VAR_SET(in6_dev->nd_parms,
  					      GC_STALETIME, 3 * rtime);

  				in6_dev->nd_parms->reachable_time = neigh_rand_reach_time(rtime);
  				in6_dev->tstamp = jiffies;

  				send_ifinfo_notify = true;

  			}
  		}
  	}

  	/*
  	 *	Send a notify if RA changed managed/otherconf flags or timer settings
  	 */
  	if (send_ifinfo_notify)
  		inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);

  skip_linkparms:

  	/*
  	 *	Process options.
  	 */
  
  	if (!neigh)

  		neigh = __neigh_lookup(&nd_tbl, &ipv6_hdr(skb)->saddr,

  				       skb->dev, 1);
  	if (neigh) {
  		u8 *lladdr = NULL;
  		if (ndopts.nd_opts_src_lladdr) {
  			lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
  						     skb->dev);
  			if (!lladdr) {

  				ND_PRINTK(2, warn,
  					  "RA: invalid link-layer address length
  ");

  				goto out;
  			}
  		}

  		ndisc_update(skb->dev, neigh, lladdr, NUD_STALE,

  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER|

  			     NEIGH_UPDATE_F_ISROUTER,
  			     NDISC_ROUTER_ADVERTISEMENT, &ndopts);

  	}

  	if (!ipv6_accept_ra(in6_dev)) {
  		ND_PRINTK(2, info,
  			  "RA: %s, accept_ra is false for dev: %s
  ",
  			  __func__, skb->dev->name);

  		goto out;

  	}

  #ifdef CONFIG_IPV6_ROUTE_INFO

  	if (!in6_dev->cnf.accept_ra_from_local &&
  	    ipv6_chk_addr(dev_net(in6_dev->dev), &ipv6_hdr(skb)->saddr,

  			  in6_dev->dev, 0)) {

  		ND_PRINTK(2, info,

  			  "RA from local address detected on dev: %s: router info ignored.
  ",
  			  skb->dev->name);

  		goto skip_routeinfo;

  	}

  	if (in6_dev->cnf.accept_ra_rtr_pref && ndopts.nd_opts_ri) {

  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_opts_ri;
  		     p;
  		     p = ndisc_next_option(p, ndopts.nd_opts_ri_end)) {

  			struct route_info *ri = (struct route_info *)p;
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  			if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT &&
  			    ri->prefix_len == 0)
  				continue;
  #endif

  			if (ri->prefix_len == 0 &&
  			    !in6_dev->cnf.accept_ra_defrtr)
  				continue;

  			if (ri->prefix_len > in6_dev->cnf.accept_ra_rt_info_max_plen)

  				continue;

  			rt6_route_rcv(skb->dev, (u8 *)p, (p->nd_opt_len) << 3,

  				      &ipv6_hdr(skb)->saddr);

  		}
  	}

  
  skip_routeinfo:

  #endif

  #ifdef CONFIG_IPV6_NDISC_NODETYPE

  	/* skip link-specific ndopts from interior routers */

  	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT) {
  		ND_PRINTK(2, info,
  			  "RA: %s, nodetype is NODEFAULT (interior routes), dev: %s
  ",
  			  __func__, skb->dev->name);

  		goto out;

  	}

  #endif

  	if (in6_dev->cnf.accept_ra_pinfo && ndopts.nd_opts_pi) {

  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_opts_pi;
  		     p;
  		     p = ndisc_next_option(p, ndopts.nd_opts_pi_end)) {

  			addrconf_prefix_rcv(skb->dev, (u8 *)p,
  					    (p->nd_opt_len) << 3,
  					    ndopts.nd_opts_src_lladdr != NULL);

  		}
  	}

  	if (ndopts.nd_opts_mtu && in6_dev->cnf.accept_ra_mtu) {

  		__be32 n;

  		u32 mtu;

  		memcpy(&n, ((u8 *)(ndopts.nd_opts_mtu+1))+2, sizeof(mtu));

  		mtu = ntohl(n);

  
  		if (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) {

  			ND_PRINTK(2, warn, "RA: invalid mtu: %d
  ", mtu);

  		} else if (in6_dev->cnf.mtu6 != mtu) {
  			in6_dev->cnf.mtu6 = mtu;
  
  			if (rt)

  				dst_metric_set(&rt->dst, RTAX_MTU, mtu);

  
  			rt6_mtu_change(skb->dev, mtu);
  		}
  	}

  	if (ndopts.nd_useropts) {

  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_useropts;
  		     p;

  		     p = ndisc_next_useropt(skb->dev, p,
  					    ndopts.nd_useropts_end)) {

  			ndisc_ra_useropt(skb, p);

  		}
  	}

  	if (ndopts.nd_opts_tgt_lladdr || ndopts.nd_opts_rh) {

  		ND_PRINTK(2, warn, "RA: invalid RA options
  ");

  	}
  out:

  	ip6_rt_put(rt);

  	if (neigh)

  		neigh_release(neigh);

  }
  
  static void ndisc_redirect_rcv(struct sk_buff *skb)
  {

  	u8 *hdr;
  	struct ndisc_options ndopts;
  	struct rd_msg *msg = (struct rd_msg *)skb_transport_header(skb);

  	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +

  				    offsetof(struct rd_msg, opt));

  #ifdef CONFIG_IPV6_NDISC_NODETYPE

  	switch (skb->ndisc_nodetype) {
  	case NDISC_NODETYPE_HOST:
  	case NDISC_NODETYPE_NODEFAULT:

  		ND_PRINTK(2, warn,
  			  "Redirect: from host or unauthorized router
  ");

  		return;
  	}

  #endif

  	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {

  		ND_PRINTK(2, warn,
  			  "Redirect: source address is not link-local
  ");

  		return;
  	}

  	if (!ndisc_parse_options(skb->dev, msg->opt, ndoptlen, &ndopts))

  		return;

  	if (!ndopts.nd_opts_rh) {

  		ip6_redirect_no_header(skb, dev_net(skb->dev),
  					skb->dev->ifindex, 0);

  		return;

  	}

  
  	hdr = (u8 *)ndopts.nd_opts_rh;
  	hdr += 8;
  	if (!pskb_pull(skb, hdr - skb_transport_header(skb)))
  		return;

  	icmpv6_notify(skb, NDISC_REDIRECT, 0, 0);

  }

  static void ndisc_fill_redirect_hdr_option(struct sk_buff *skb,
  					   struct sk_buff *orig_skb,
  					   int rd_len)

  {

  	u8 *opt = skb_put(skb, rd_len);

  	memset(opt, 0, 8);
  	*(opt++) = ND_OPT_REDIRECT_HDR;
  	*(opt++) = (rd_len >> 3);
  	opt += 6;
  
  	memcpy(opt, ipv6_hdr(orig_skb), rd_len - 8);

  }

  void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)

  {

  	struct net_device *dev = skb->dev;

  	struct net *net = dev_net(dev);

  	struct sock *sk = net->ipv6.ndisc_sk;

  	int optlen = 0;

  	struct inet_peer *peer;

  	struct sk_buff *buff;

  	struct rd_msg *msg;

  	struct in6_addr saddr_buf;

  	struct rt6_info *rt;
  	struct dst_entry *dst;

  	struct flowi6 fl6;

  	int rd_len;

  	u8 ha_buf[MAX_ADDR_LEN], *ha = NULL,
  	   ops_data_buf[NDISC_OPS_REDIRECT_DATA_SPACE], *ops_data = NULL;

  	bool ret;

  	if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {

  		ND_PRINTK(2, warn, "Redirect: no link-local address on %s
  ",
  			  dev->name);

  		return;
  	}

  	if (!ipv6_addr_equal(&ipv6_hdr(skb)->daddr, target) &&

  	    ipv6_addr_type(target) != (IPV6_ADDR_UNICAST|IPV6_ADDR_LINKLOCAL)) {

  		ND_PRINTK(2, warn,
  			  "Redirect: target address is not link-local unicast
  ");

  		return;
  	}

  	icmpv6_flow_init(sk, &fl6, NDISC_REDIRECT,

  			 &saddr_buf, &ipv6_hdr(skb)->saddr, dev->ifindex);