text: #ifndef _NET_IP6_ROUTE_H
  #define _NET_IP6_ROUTE_H
  
  struct route_info {
  	__u8			type;
  	__u8			length;
  	__u8			prefix_len;
  #if defined(__BIG_ENDIAN_BITFIELD)
  	__u8			reserved_h:3,
  				route_pref:2,
  				reserved_l:3;
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	__u8			reserved_l:3,
  				route_pref:2,
  				reserved_h:3;
  #endif
  	__be32			lifetime;
  	__u8			prefix[0];	/* 0,8 or 16 */
  };
  
  #include <net/flow.h>
  #include <net/ip6_fib.h>
  #include <net/sock.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <linux/route.h>
  
  #define RT6_LOOKUP_F_IFACE		0x00000001
  #define RT6_LOOKUP_F_REACHABLE		0x00000002
  #define RT6_LOOKUP_F_HAS_SADDR		0x00000004
  #define RT6_LOOKUP_F_SRCPREF_TMP	0x00000008
  #define RT6_LOOKUP_F_SRCPREF_PUBLIC	0x00000010
  #define RT6_LOOKUP_F_SRCPREF_COA	0x00000020
  
  /* We do not (yet ?) support IPv6 jumbograms (RFC 2675)
   * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header
   */
  #define IP6_MAX_MTU (0xFFFF + sizeof(struct ipv6hdr))
  
  /*
   * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate
   * between IPV6_ADDR_PREFERENCES socket option values
   *	IPV6_PREFER_SRC_TMP    = 0x1
   *	IPV6_PREFER_SRC_PUBLIC = 0x2
   *	IPV6_PREFER_SRC_COA    = 0x4
   * and above RT6_LOOKUP_F_SRCPREF_xxx flags.
   */
  static inline int rt6_srcprefs2flags(unsigned int srcprefs)
  {
  	/* No need to bitmask because srcprefs have only 3 bits. */
  	return srcprefs << 3;
  }
  
  static inline unsigned int rt6_flags2srcprefs(int flags)
  {
  	return (flags >> 3) & 7;
  }
  
  static inline bool rt6_need_strict(const struct in6_addr *daddr)
  {
  	return ipv6_addr_type(daddr) &
  		(IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK);
  }
  
  void ip6_route_input(struct sk_buff *skb);
  
  struct dst_entry *ip6_route_output(struct net *net, const struct sock *sk,
  				   struct flowi6 *fl6);
  struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
  				   int flags);
  
  void ip6_route_init_special_entries(void);
  int ip6_route_init(void);
  void ip6_route_cleanup(void);
  
  int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg);
  
  int ip6_route_add(struct fib6_config *cfg);
  int ip6_ins_rt(struct rt6_info *);
  int ip6_del_rt(struct rt6_info *);
  
  int ip6_route_get_saddr(struct net *net, struct rt6_info *rt,
  			const struct in6_addr *daddr, unsigned int prefs,
  			struct in6_addr *saddr);
  
  struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
  			    const struct in6_addr *saddr, int oif, int flags);
  
  struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct flowi6 *fl6);
  int icmp6_dst_gc(void);
  
  void fib6_force_start_gc(struct net *net);
  
  struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
  				    const struct in6_addr *addr, bool anycast);
  
  /*
   *	support functions for ND
   *
   */
  struct rt6_info *rt6_get_dflt_router(const struct in6_addr *addr,
  				     struct net_device *dev);
  struct rt6_info *rt6_add_dflt_router(const struct in6_addr *gwaddr,
  				     struct net_device *dev, unsigned int pref);
  
  void rt6_purge_dflt_routers(struct net *net);
  
  int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
  		  const struct in6_addr *gwaddr);
  
  void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu, int oif,
  		     u32 mark, kuid_t uid);
  void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu);
  void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark,
  				kuid_t uid);
  void ip6_redirect_no_header(struct sk_buff *skb, struct net *net, int oif,
  			    u32 mark);
  void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk);
  
  struct netlink_callback;
  
  struct rt6_rtnl_dump_arg {
  	struct sk_buff *skb;
  	struct netlink_callback *cb;
  	struct net *net;
  };
  
  int rt6_dump_route(struct rt6_info *rt, void *p_arg);
  void rt6_ifdown(struct net *net, struct net_device *dev);
  void rt6_mtu_change(struct net_device *dev, unsigned int mtu);
  void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
  void rt6_clean_tohost(struct net *net, struct in6_addr *gateway);
  
  
  /*
   *	Store a destination cache entry in a socket
   */
  static inline void __ip6_dst_store(struct sock *sk, struct dst_entry *dst,
  				   const struct in6_addr *daddr,
  				   const struct in6_addr *saddr)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct rt6_info *rt = (struct rt6_info *) dst;
  
  	sk_setup_caps(sk, dst);
  	np->daddr_cache = daddr;
  #ifdef CONFIG_IPV6_SUBTREES
  	np->saddr_cache = saddr;
  #endif
  	np->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
  }
  
  static inline void ip6_dst_store(struct sock *sk, struct dst_entry *dst,
  				 struct in6_addr *daddr, struct in6_addr *saddr)
  {
  	spin_lock(&sk->sk_dst_lock);
  	__ip6_dst_store(sk, dst, daddr, saddr);
  	spin_unlock(&sk->sk_dst_lock);
  }
  
  static inline bool ipv6_unicast_destination(const struct sk_buff *skb)
  {
  	struct rt6_info *rt = (struct rt6_info *) skb_dst(skb);
  
  	return rt->rt6i_flags & RTF_LOCAL;
  }
  
  static inline bool ipv6_anycast_destination(const struct sk_buff *skb)
  {
  	struct rt6_info *rt = (struct rt6_info *) skb_dst(skb);
  
  	return rt->rt6i_flags & RTF_ANYCAST;
  }
  
  int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
  
  static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
  {
  	struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
  				inet6_sk(skb->sk) : NULL;
  
  	return (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) ?
  	       skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
  }
  
  static inline bool ip6_sk_accept_pmtu(const struct sock *sk)
  {
  	return inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_INTERFACE &&
  	       inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_OMIT;
  }
  
  static inline bool ip6_sk_ignore_df(const struct sock *sk)
  {
  	return inet6_sk(sk)->pmtudisc < IPV6_PMTUDISC_DO ||
  	       inet6_sk(sk)->pmtudisc == IPV6_PMTUDISC_OMIT;
  }
  
  static inline struct in6_addr *rt6_nexthop(struct rt6_info *rt)
  {
  	return &rt->rt6i_gateway;
  }
  
  #endif
  