text: /* SPDX-License-Identifier: GPL-2.0 */
  #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[];	/* 0,8 or 16 */
  };
  
  #include <net/addrconf.h>
  #include <net/flow.h>
  #include <net/ip6_fib.h>
  #include <net/sock.h>
  #include <net/lwtunnel.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <linux/route.h>
  #include <net/nexthop.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
  #define RT6_LOOKUP_F_IGNORE_LINKSTATE	0x00000040
  #define RT6_LOOKUP_F_DST_NOREF		0x00000080
  
  /* 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);
  }
  
  /* fib entries using a nexthop object can not be coalesced into
   * a multipath route
   */
  static inline bool rt6_qualify_for_ecmp(const struct fib6_info *f6i)
  {
  	/* the RTF_ADDRCONF flag filters out RA's */
  	return !(f6i->fib6_flags & RTF_ADDRCONF) && !f6i->nh &&
  		f6i->fib6_nh->fib_nh_gw_family;
  }
  
  void ip6_route_input(struct sk_buff *skb);
  struct dst_entry *ip6_route_input_lookup(struct net *net,
  					 struct net_device *dev,
  					 struct flowi6 *fl6,
  					 const struct sk_buff *skb, int flags);
  
  struct dst_entry *ip6_route_output_flags_noref(struct net *net,
  					       const struct sock *sk,
  					       struct flowi6 *fl6, int flags);
  
  struct dst_entry *ip6_route_output_flags(struct net *net, const struct sock *sk,
  					 struct flowi6 *fl6, int flags);
  
  static inline struct dst_entry *ip6_route_output(struct net *net,
  						 const struct sock *sk,
  						 struct flowi6 *fl6)
  {
  	return ip6_route_output_flags(net, sk, fl6, 0);
  }
  
  /* Only conditionally release dst if flags indicates
   * !RT6_LOOKUP_F_DST_NOREF or dst is in uncached_list.
   */
  static inline void ip6_rt_put_flags(struct rt6_info *rt, int flags)
  {
  	if (!(flags & RT6_LOOKUP_F_DST_NOREF) ||
  	    !list_empty(&rt->rt6i_uncached))
  		ip6_rt_put(rt);
  }
  
  struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
  				   const struct sk_buff *skb, int flags);
  struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
  			       int ifindex, struct flowi6 *fl6,
  			       const struct sk_buff *skb, 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,
  		struct in6_rtmsg *rtmsg);
  
  int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
  		  struct netlink_ext_ack *extack);
  int ip6_ins_rt(struct net *net, struct fib6_info *f6i);
  int ip6_del_rt(struct net *net, struct fib6_info *f6i, bool skip_notify);
  
  void rt6_flush_exceptions(struct fib6_info *f6i);
  void rt6_age_exceptions(struct fib6_info *f6i, struct fib6_gc_args *gc_args,
  			unsigned long now);
  
  static inline int ip6_route_get_saddr(struct net *net, struct fib6_info *f6i,
  				      const struct in6_addr *daddr,
  				      unsigned int prefs,
  				      struct in6_addr *saddr)
  {
  	int err = 0;
  
  	if (f6i && f6i->fib6_prefsrc.plen) {
  		*saddr = f6i->fib6_prefsrc.addr;
  	} else {
  		struct net_device *dev = f6i ? fib6_info_nh_dev(f6i) : NULL;
  
  		err = ipv6_dev_get_saddr(net, dev, daddr, prefs, saddr);
  	}
  
  	return err;
  }
  
  struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
  			    const struct in6_addr *saddr, int oif,
  			    const struct sk_buff *skb, int flags);
  u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
  		       const struct sk_buff *skb, struct flow_keys *hkeys);
  
  struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct flowi6 *fl6);
  
  void fib6_force_start_gc(struct net *net);
  
  struct fib6_info *addrconf_f6i_alloc(struct net *net, struct inet6_dev *idev,
  				     const struct in6_addr *addr, bool anycast,
  				     gfp_t gfp_flags);
  
  struct rt6_info *ip6_dst_alloc(struct net *net, struct net_device *dev,
  			       int flags);
  
  /*
   *	support functions for ND
   *
   */
  struct fib6_info *rt6_get_dflt_router(struct net *net,
  				     const struct in6_addr *addr,
  				     struct net_device *dev);
  struct fib6_info *rt6_add_dflt_router(struct net *net,
  				     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);
  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;
  	struct fib_dump_filter filter;
  };
  
  int rt6_dump_route(struct fib6_info *f6i, void *p_arg, unsigned int skip);
  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);
  void rt6_sync_up(struct net_device *dev, unsigned char nh_flags);
  void rt6_disable_ip(struct net_device *dev, unsigned long event);
  void rt6_sync_down_dev(struct net_device *dev, unsigned long event);
  void rt6_multipath_rebalance(struct fib6_info *f6i);
  
  void rt6_uncached_list_add(struct rt6_info *rt);
  void rt6_uncached_list_del(struct rt6_info *rt);
  
  static inline const struct rt6_info *skb_rt6_info(const struct sk_buff *skb)
  {
  	const struct dst_entry *dst = skb_dst(skb);
  	const struct rt6_info *rt6 = NULL;
  
  	if (dst)
  		rt6 = container_of(dst, struct rt6_info, dst);
  
  	return rt6;
  }
  
  /*
   *	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);
  
  	np->dst_cookie = rt6_get_cookie((struct rt6_info *)dst);
  	sk_setup_caps(sk, dst);
  	np->daddr_cache = daddr;
  #ifdef CONFIG_IPV6_SUBTREES
  	np->saddr_cache = saddr;
  #endif
  }
  
  void ip6_sk_dst_store_flow(struct sock *sk, struct dst_entry *dst,
  			   const struct flowi6 *fl6);
  
  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 dst_entry *dst,
  					    const struct in6_addr *daddr)
  {
  	struct rt6_info *rt = (struct rt6_info *)dst;
  
  	return rt->rt6i_flags & RTF_ANYCAST ||
  		(rt->rt6i_dst.plen < 127 &&
  		 !(rt->rt6i_flags & (RTF_GATEWAY | RTF_NONEXTHOP)) &&
  		 ipv6_addr_equal(&rt->rt6i_dst.addr, daddr));
  }
  
  int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
  		 int (*output)(struct net *, struct sock *, struct sk_buff *));
  
  static inline unsigned int ip6_skb_dst_mtu(struct sk_buff *skb)
  {
  	unsigned int mtu;
  
  	struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
  				inet6_sk(skb->sk) : NULL;
  
  	if (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) {
  		mtu = READ_ONCE(skb_dst(skb)->dev->mtu);
  		mtu -= lwtunnel_headroom(skb_dst(skb)->lwtstate, mtu);
  	} else
  		mtu = dst_mtu(skb_dst(skb));
  
  	return mtu;
  }
  
  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 const struct in6_addr *rt6_nexthop(const struct rt6_info *rt,
  						 const struct in6_addr *daddr)
  {
  	if (rt->rt6i_flags & RTF_GATEWAY)
  		return &rt->rt6i_gateway;
  	else if (unlikely(rt->rt6i_flags & RTF_CACHE))
  		return &rt->rt6i_dst.addr;
  	else
  		return daddr;
  }
  
  static inline bool rt6_duplicate_nexthop(struct fib6_info *a, struct fib6_info *b)
  {
  	struct fib6_nh *nha, *nhb;
  
  	if (a->nh || b->nh)
  		return nexthop_cmp(a->nh, b->nh);
  
  	nha = a->fib6_nh;
  	nhb = b->fib6_nh;
  	return nha->fib_nh_dev == nhb->fib_nh_dev &&
  	       ipv6_addr_equal(&nha->fib_nh_gw6, &nhb->fib_nh_gw6) &&
  	       !lwtunnel_cmp_encap(nha->fib_nh_lws, nhb->fib_nh_lws);
  }
  
  static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)
  {
  	struct inet6_dev *idev;
  	unsigned int mtu;
  
  	if (dst_metric_locked(dst, RTAX_MTU)) {
  		mtu = dst_metric_raw(dst, RTAX_MTU);
  		if (mtu)
  			goto out;
  	}
  
  	mtu = IPV6_MIN_MTU;
  	rcu_read_lock();
  	idev = __in6_dev_get(dst->dev);
  	if (idev)
  		mtu = idev->cnf.mtu6;
  	rcu_read_unlock();
  
  out:
  	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
  }
  
  u32 ip6_mtu_from_fib6(const struct fib6_result *res,
  		      const struct in6_addr *daddr,
  		      const struct in6_addr *saddr);
  
  struct neighbour *ip6_neigh_lookup(const struct in6_addr *gw,
  				   struct net_device *dev, struct sk_buff *skb,
  				   const void *daddr);
  #endif
  