/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET  is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Definitions for the IP router.
 *
 * Version:     @(#)route.h     1.0.4   05/27/93
 *
 * Authors:     Ross Biro
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 * Fixes:
 *              Alan Cox        :       Reformatted. Added ip_rt_local()
 *              Alan Cox        :       Support for TCP parameters.
 *              Alexey Kuznetsov:       Major changes for new routing code.
 *              Mike McLagan    :       Routing by source
 *              Robert Olsson   :       Added rt_cache statistics
 */
#ifndef _ROUTE_H
#define _ROUTE_H

#include <net/dst.h>
#include <net/inetpeer.h>
#include <net/flow.h>
#include <net/inet_sock.h>
#include <net/ip_fib.h>
#include <net/arp.h>
#include <net/ndisc.h>
#include <net/inet_dscp.h>
#include <net/sock.h>
#include <linux/in_route.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
#include <linux/route.h>
#include <linux/ip.h>
#include <linux/cache.h>
#include <linux/security.h>

static inline __u8 ip_sock_rt_scope(const struct sock *sk)
{
        if (sock_flag(sk, SOCK_LOCALROUTE))
                return RT_SCOPE_LINK;

        return RT_SCOPE_UNIVERSE;
}

static inline __u8 ip_sock_rt_tos(const struct sock *sk)
{
        return READ_ONCE(inet_sk(sk)->tos) & INET_DSCP_MASK;
}

struct ip_tunnel_info;
struct fib_nh;
struct fib_info;
struct uncached_list;
struct rtable {
        struct dst_entry        dst;

        int                     rt_genid;
        unsigned int            rt_flags;
        __u16                   rt_type;
        __u8                    rt_is_input;
        __u8                    rt_uses_gateway;

        int                     rt_iif;

        u8                      rt_gw_family;
        /* Info on neighbour */
        union {
                __be32          rt_gw4;
                struct in6_addr rt_gw6;
        };

        /* Miscellaneous cached information */
        u32                     rt_mtu_locked:1,
                                rt_pmtu:31;
};

#define dst_rtable(_ptr) container_of_const(_ptr, struct rtable, dst)

/**
 * skb_rtable - Returns the skb &rtable
 * @skb: buffer
 */
static inline struct rtable *skb_rtable(const struct sk_buff *skb)
{
        return dst_rtable(skb_dst(skb));
}

static inline bool rt_is_input_route(const struct rtable *rt)
{
        return rt->rt_is_input != 0;
}

static inline bool rt_is_output_route(const struct rtable *rt)
{
        return rt->rt_is_input == 0;
}

static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
{
        if (rt->rt_gw_family == AF_INET)
                return rt->rt_gw4;
        return daddr;
}

struct ip_rt_acct {
        __u32   o_bytes;
        __u32   o_packets;
        __u32   i_bytes;
        __u32   i_packets;
};

struct rt_cache_stat {
        unsigned int in_slow_tot;
        unsigned int in_slow_mc;
        unsigned int in_no_route;
        unsigned int in_brd;
        unsigned int in_martian_dst;
        unsigned int in_martian_src;
        unsigned int out_slow_tot;
        unsigned int out_slow_mc;
};

extern struct ip_rt_acct __percpu *ip_rt_acct;

struct in_device;

int ip_rt_init(void);
void rt_cache_flush(struct net *net);
void rt_flush_dev(struct net_device *dev);

static inline void inet_sk_init_flowi4(const struct inet_sock *inet,
                                       struct flowi4 *fl4)
{
        const struct ip_options_rcu *ip4_opt;
        const struct sock *sk;
        __be32 daddr;

        rcu_read_lock();
        ip4_opt = rcu_dereference(inet->inet_opt);

        /* Source routing option overrides the socket destination address */
        if (ip4_opt && ip4_opt->opt.srr)
                daddr = ip4_opt->opt.faddr;
        else
                daddr = inet->inet_daddr;
        rcu_read_unlock();

        sk = &inet->sk;
        flowi4_init_output(fl4, sk->sk_bound_dev_if, READ_ONCE(sk->sk_mark),
                           ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
                           sk->sk_protocol, inet_sk_flowi_flags(sk), daddr,
                           inet->inet_saddr, inet->inet_dport,
                           inet->inet_sport, sk_uid(sk));
        security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
}

struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
                                        const struct sk_buff *skb);
struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
                                            struct fib_result *res,
                                            const struct sk_buff *skb);

static inline struct rtable *__ip_route_output_key(struct net *net,
                                                   struct flowi4 *flp)
{
        return ip_route_output_key_hash(net, flp, NULL);
}

struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
                                    const struct sock *sk);
struct dst_entry *ipv4_blackhole_route(struct net *net,
                                       struct dst_entry *dst_orig);

static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
{
        return ip_route_output_flow(net, flp, NULL);
}

/* Simplistic IPv4 route lookup function.
 * This is only suitable for some particular use cases: since the flowi4
 * structure is only partially set, it may bypass some fib-rules.
 */
static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
                                             __be32 saddr, dscp_t dscp,
                                             int oif, __u8 scope)
{
        struct flowi4 fl4 = {
                .flowi4_oif = oif,
                .flowi4_dscp = dscp,
                .flowi4_scope = scope,
                .daddr = daddr,
                .saddr = saddr,
        };

        return ip_route_output_key(net, &fl4);
}

static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
                                                   const struct sock *sk,
                                                   __be32 daddr, __be32 saddr,
                                                   __be16 dport, __be16 sport,
                                                   __u8 proto, __u8 tos, int oif)
{
        flowi4_init_output(fl4, oif, sk ? READ_ONCE(sk->sk_mark) : 0, tos,
                           sk ? ip_sock_rt_scope(sk) : RT_SCOPE_UNIVERSE,
                           proto, sk ? inet_sk_flowi_flags(sk) : 0,
                           daddr, saddr, dport, sport, sock_net_uid(net, sk));
        if (sk)
                security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
        return ip_route_output_flow(net, fl4, sk);
}

enum skb_drop_reason
ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                      dscp_t dscp, struct net_device *dev,
                      struct in_device *in_dev, u32 *itag);
enum skb_drop_reason
ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                     dscp_t dscp, struct net_device *dev);
enum skb_drop_reason
ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                  dscp_t dscp, struct net_device *dev,
                  const struct sk_buff *hint);

static inline enum skb_drop_reason
ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src, dscp_t dscp,
               struct net_device *devin)
{
        enum skb_drop_reason reason;

        rcu_read_lock();
        reason = ip_route_input_noref(skb, dst, src, dscp, devin);
        if (!reason) {
                skb_dst_force(skb);
                if (!skb_dst(skb))
                        reason = SKB_DROP_REASON_NOT_SPECIFIED;
        }
        rcu_read_unlock();

        return reason;
}

void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
                      u8 protocol);
void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
void ip_rt_send_redirect(struct sk_buff *skb);

unsigned int inet_addr_type(struct net *net, __be32 addr);
unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
                                __be32 addr);
unsigned int inet_addr_type_dev_table(struct net *net,
                                      const struct net_device *dev,
                                      __be32 addr);
void ip_rt_multicast_event(struct in_device *);
int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
struct rtable *rt_dst_alloc(struct net_device *dev,
                            unsigned int flags, u16 type, bool noxfrm);
struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);

struct in_ifaddr;
void fib_add_ifaddr(struct in_ifaddr *);
void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);

void rt_add_uncached_list(struct rtable *rt);
void rt_del_uncached_list(struct rtable *rt);

int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
                       u32 table_id, struct fib_info *fi,
                       int *fa_index, int fa_start, unsigned int flags);

static inline void ip_rt_put(struct rtable *rt)
{
        /* dst_release() accepts a NULL parameter.
         * We rely on dst being first structure in struct rtable
         */
        BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
        dst_release(&rt->dst);
}

extern const __u8 ip_tos2prio[16];

static inline char rt_tos2priority(u8 tos)
{
        return ip_tos2prio[IPTOS_TOS(tos)>>1];
}

/* ip_route_connect() and ip_route_newports() work in tandem whilst
 * binding a socket for a new outgoing connection.
 *
 * In order to use IPSEC properly, we must, in the end, have a
 * route that was looked up using all available keys including source
 * and destination ports.
 *
 * However, if a source port needs to be allocated (the user specified
 * a wildcard source port) we need to obtain addressing information
 * in order to perform that allocation.
 *
 * So ip_route_connect() looks up a route using wildcarded source and
 * destination ports in the key, simply so that we can get a pair of
 * addresses to use for port allocation.
 *
 * Later, once the ports are allocated, ip_route_newports() will make
 * another route lookup if needed to make sure we catch any IPSEC
 * rules keyed on the port information.
 *
 * The callers allocate the flow key on their stack, and must pass in
 * the same flowi4 object to both the ip_route_connect() and the
 * ip_route_newports() calls.
 */

static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst,
                                         __be32 src, int oif, u8 protocol,
                                         __be16 sport, __be16 dport,
                                         const struct sock *sk)
{
        __u8 flow_flags = 0;

        if (inet_test_bit(TRANSPARENT, sk))
                flow_flags |= FLOWI_FLAG_ANYSRC;

        if (IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) && !sport)
                flow_flags |= FLOWI_FLAG_ANY_SPORT;

        flowi4_init_output(fl4, oif, READ_ONCE(sk->sk_mark), ip_sock_rt_tos(sk),
                           ip_sock_rt_scope(sk), protocol, flow_flags, dst,
                           src, dport, sport, sk_uid(sk));
}

static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
                                              __be32 src, int oif, u8 protocol,
                                              __be16 sport, __be16 dport,
                                              const struct sock *sk)
{
        struct net *net = sock_net(sk);
        struct rtable *rt;

        ip_route_connect_init(fl4, dst, src, oif, protocol, sport, dport, sk);

        if (!dst || !src) {
                rt = __ip_route_output_key(net, fl4);
                if (IS_ERR(rt))
                        return rt;
                ip_rt_put(rt);
                flowi4_update_output(fl4, oif, fl4->daddr, fl4->saddr);
        }
        security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
        return ip_route_output_flow(net, fl4, sk);
}

static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
                                               __be16 orig_sport, __be16 orig_dport,
                                               __be16 sport, __be16 dport,
                                               const struct sock *sk)
{
        if (sport != orig_sport || dport != orig_dport) {
                fl4->fl4_dport = dport;
                fl4->fl4_sport = sport;
                ip_rt_put(rt);
                flowi4_update_output(fl4, sk->sk_bound_dev_if, fl4->daddr,
                                     fl4->saddr);
                security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
                return ip_route_output_flow(sock_net(sk), fl4, sk);
        }
        return rt;
}

static inline int inet_iif(const struct sk_buff *skb)
{
        struct rtable *rt = skb_rtable(skb);

        if (rt && rt->rt_iif)
                return rt->rt_iif;

        return skb->skb_iif;
}

static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
{
        int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);

        if (hoplimit == 0) {
                const struct net *net;

                rcu_read_lock();
                net = dst_dev_net_rcu(dst);
                hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
                rcu_read_unlock();
        }
        return hoplimit;
}

static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
                                             __be32 daddr)
{
        struct neighbour *neigh;

        neigh = __ipv4_neigh_lookup_noref(dev, (__force u32)daddr);
        if (unlikely(!neigh))
                neigh = __neigh_create(&arp_tbl, &daddr, dev, false);

        return neigh;
}

static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
                                                struct sk_buff *skb,
                                                bool *is_v6gw)
{
        struct net_device *dev = rt->dst.dev;
        struct neighbour *neigh;

        if (likely(rt->rt_gw_family == AF_INET)) {
                neigh = ip_neigh_gw4(dev, rt->rt_gw4);
        } else if (rt->rt_gw_family == AF_INET6) {
                neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
                *is_v6gw = true;
        } else {
                neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
        }
        return neigh;
}

#endif  /* _ROUTE_H */