/*
 *      Linux INET6 implementation 
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>     
 *
 *      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.
 */

#ifndef _IP6_FIB_H
#define _IP6_FIB_H

#include <linux/ipv6_route.h>
#include <linux/rtnetlink.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/netlink.h>
#include <net/inetpeer.h>
#include <net/fib_notifier.h>

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
#define FIB6_TABLE_HASHSZ 256
#else
#define FIB6_TABLE_HASHSZ 1
#endif

#define RT6_DEBUG 2

#if RT6_DEBUG >= 3
#define RT6_TRACE(x...) pr_debug(x)
#else
#define RT6_TRACE(x...) do { ; } while (0)
#endif

struct rt6_info;

struct fib6_config {
        u32             fc_table;
        u32             fc_metric;
        int             fc_dst_len;
        int             fc_src_len;
        int             fc_ifindex;
        u32             fc_flags;
        u32             fc_protocol;
        u16             fc_type;        /* only 8 bits are used */
        u16             fc_delete_all_nh : 1,
                        __unused : 15;

        struct in6_addr fc_dst;
        struct in6_addr fc_src;
        struct in6_addr fc_prefsrc;
        struct in6_addr fc_gateway;

        unsigned long   fc_expires;
        struct nlattr   *fc_mx;
        int             fc_mx_len;
        int             fc_mp_len;
        struct nlattr   *fc_mp;

        struct nl_info  fc_nlinfo;
        struct nlattr   *fc_encap;
        u16             fc_encap_type;
};

struct fib6_node {
        struct fib6_node __rcu  *parent;
        struct fib6_node __rcu  *left;
        struct fib6_node __rcu  *right;
#ifdef CONFIG_IPV6_SUBTREES
        struct fib6_node __rcu  *subtree;
#endif
        struct rt6_info __rcu   *leaf;

        __u16                   fn_bit;         /* bit key */
        __u16                   fn_flags;
        int                     fn_sernum;
        struct rt6_info __rcu   *rr_ptr;
        struct rcu_head         rcu;
};

struct fib6_gc_args {
        int                     timeout;
        int                     more;
};

#ifndef CONFIG_IPV6_SUBTREES
#define FIB6_SUBTREE(fn)        NULL
#else
#define FIB6_SUBTREE(fn)        (rcu_dereference_protected((fn)->subtree, 1))
#endif

struct mx6_config {
        const u32 *mx;
        DECLARE_BITMAP(mx_valid, RTAX_MAX);
};

/*
 *      routing information
 *
 */

struct rt6key {
        struct in6_addr addr;
        int             plen;
};

struct fib6_table;

struct rt6_exception_bucket {
        struct hlist_head       chain;
        int                     depth;
};

struct rt6_exception {
        struct hlist_node       hlist;
        struct rt6_info         *rt6i;
        unsigned long           stamp;
        struct rcu_head         rcu;
};

#define FIB6_EXCEPTION_BUCKET_SIZE_SHIFT 10
#define FIB6_EXCEPTION_BUCKET_SIZE (1 << FIB6_EXCEPTION_BUCKET_SIZE_SHIFT)
#define FIB6_MAX_DEPTH 5

struct rt6_info {
        struct dst_entry                dst;
        struct rt6_info __rcu           *rt6_next;
        struct rt6_info                 *from;

        /*
         * Tail elements of dst_entry (__refcnt etc.)
         * and these elements (rarely used in hot path) are in
         * the same cache line.
         */
        struct fib6_table               *rt6i_table;
        struct fib6_node __rcu          *rt6i_node;

        struct in6_addr                 rt6i_gateway;

        /* Multipath routes:
         * siblings is a list of rt6_info that have the the same metric/weight,
         * destination, but not the same gateway. nsiblings is just a cache
         * to speed up lookup.
         */
        struct list_head                rt6i_siblings;
        unsigned int                    rt6i_nsiblings;
        atomic_t                        rt6i_nh_upper_bound;

        atomic_t                        rt6i_ref;

        unsigned int                    rt6i_nh_flags;

        /* These are in a separate cache line. */
        struct rt6key                   rt6i_dst ____cacheline_aligned_in_smp;
        u32                             rt6i_flags;
        struct rt6key                   rt6i_src;
        struct rt6key                   rt6i_prefsrc;

        struct list_head                rt6i_uncached;
        struct uncached_list            *rt6i_uncached_list;

        struct inet6_dev                *rt6i_idev;
        struct rt6_info * __percpu      *rt6i_pcpu;
        struct rt6_exception_bucket __rcu *rt6i_exception_bucket;

        u32                             rt6i_metric;
        u32                             rt6i_pmtu;
        /* more non-fragment space at head required */
        int                             rt6i_nh_weight;
        unsigned short                  rt6i_nfheader_len;
        u8                              rt6i_protocol;
        u8                              exception_bucket_flushed:1,
                                        should_flush:1,
                                        unused:6;
};

#define for_each_fib6_node_rt_rcu(fn)                                   \
        for (rt = rcu_dereference((fn)->leaf); rt;                      \
             rt = rcu_dereference(rt->rt6_next))

#define for_each_fib6_walker_rt(w)                                      \
        for (rt = (w)->leaf; rt;                                        \
             rt = rcu_dereference_protected(rt->rt6_next, 1))

static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst)
{
        return ((struct rt6_info *)dst)->rt6i_idev;
}

static inline void rt6_clean_expires(struct rt6_info *rt)
{
        rt->rt6i_flags &= ~RTF_EXPIRES;
        rt->dst.expires = 0;
}

static inline void rt6_set_expires(struct rt6_info *rt, unsigned long expires)
{
        rt->dst.expires = expires;
        rt->rt6i_flags |= RTF_EXPIRES;
}

static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
{
        struct rt6_info *rt;

        for (rt = rt0; rt && !(rt->rt6i_flags & RTF_EXPIRES); rt = rt->from);
        if (rt && rt != rt0)
                rt0->dst.expires = rt->dst.expires;
        dst_set_expires(&rt0->dst, timeout);
        rt0->rt6i_flags |= RTF_EXPIRES;
}

/* Function to safely get fn->sernum for passed in rt
 * and store result in passed in cookie.
 * Return true if we can get cookie safely
 * Return false if not
 */
static inline bool rt6_get_cookie_safe(const struct rt6_info *rt,
                                       u32 *cookie)
{
        struct fib6_node *fn;
        bool status = false;

        rcu_read_lock();
        fn = rcu_dereference(rt->rt6i_node);

        if (fn) {
                *cookie = fn->fn_sernum;
                /* pairs with smp_wmb() in fib6_update_sernum_upto_root() */
                smp_rmb();
                status = true;
        }

        rcu_read_unlock();
        return status;
}

static inline u32 rt6_get_cookie(const struct rt6_info *rt)
{
        u32 cookie = 0;

        if (rt->rt6i_flags & RTF_PCPU ||
            (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
                rt = rt->from;

        rt6_get_cookie_safe(rt, &cookie);

        return cookie;
}

static inline void ip6_rt_put(struct rt6_info *rt)
{
        /* dst_release() accepts a NULL parameter.
         * We rely on dst being first structure in struct rt6_info
         */
        BUILD_BUG_ON(offsetof(struct rt6_info, dst) != 0);
        dst_release(&rt->dst);
}

void rt6_free_pcpu(struct rt6_info *non_pcpu_rt);

static inline void rt6_hold(struct rt6_info *rt)
{
        atomic_inc(&rt->rt6i_ref);
}

static inline void rt6_release(struct rt6_info *rt)
{
        if (atomic_dec_and_test(&rt->rt6i_ref)) {
                rt6_free_pcpu(rt);
                dst_dev_put(&rt->dst);
                dst_release(&rt->dst);
        }
}

enum fib6_walk_state {
#ifdef CONFIG_IPV6_SUBTREES
        FWS_S,
#endif
        FWS_L,
        FWS_R,
        FWS_C,
        FWS_U
};

struct fib6_walker {
        struct list_head lh;
        struct fib6_node *root, *node;
        struct rt6_info *leaf;
        enum fib6_walk_state state;
        unsigned int skip;
        unsigned int count;
        int (*func)(struct fib6_walker *);
        void *args;
};

struct rt6_statistics {
        __u32           fib_nodes;              /* all fib6 nodes */
        __u32           fib_route_nodes;        /* intermediate nodes */
        __u32           fib_rt_entries;         /* rt entries in fib table */
        __u32           fib_rt_cache;           /* cached rt entries in exception table */
        __u32           fib_discarded_routes;   /* total number of routes delete */

        /* The following stats are not protected by any lock */
        atomic_t        fib_rt_alloc;           /* total number of routes alloced */
        atomic_t        fib_rt_uncache;         /* rt entries in uncached list */
};

#define RTN_TL_ROOT     0x0001
#define RTN_ROOT        0x0002          /* tree root node               */
#define RTN_RTINFO      0x0004          /* node with valid routing info */

/*
 *      priority levels (or metrics)
 *
 */


struct fib6_table {
        struct hlist_node       tb6_hlist;
        u32                     tb6_id;
        spinlock_t              tb6_lock;
        struct fib6_node        tb6_root;
        struct inet_peer_base   tb6_peers;
        unsigned int            flags;
        unsigned int            fib_seq;
#define RT6_TABLE_HAS_DFLT_ROUTER       BIT(0)
};

#define RT6_TABLE_UNSPEC        RT_TABLE_UNSPEC
#define RT6_TABLE_MAIN          RT_TABLE_MAIN
#define RT6_TABLE_DFLT          RT6_TABLE_MAIN
#define RT6_TABLE_INFO          RT6_TABLE_MAIN
#define RT6_TABLE_PREFIX        RT6_TABLE_MAIN

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
#define FIB6_TABLE_MIN          1
#define FIB6_TABLE_MAX          RT_TABLE_MAX
#define RT6_TABLE_LOCAL         RT_TABLE_LOCAL
#else
#define FIB6_TABLE_MIN          RT_TABLE_MAIN
#define FIB6_TABLE_MAX          FIB6_TABLE_MIN
#define RT6_TABLE_LOCAL         RT6_TABLE_MAIN
#endif

typedef struct rt6_info *(*pol_lookup_t)(struct net *,
                                         struct fib6_table *,
                                         struct flowi6 *,
                                         const struct sk_buff *, int);

struct fib6_entry_notifier_info {
        struct fib_notifier_info info; /* must be first */
        struct rt6_info *rt;
};

/*
 *      exported functions
 */

struct fib6_table *fib6_get_table(struct net *net, u32 id);
struct fib6_table *fib6_new_table(struct net *net, u32 id);
struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
                                   const struct sk_buff *skb,
                                   int flags, pol_lookup_t lookup);

struct fib6_node *fib6_lookup(struct fib6_node *root,
                              const struct in6_addr *daddr,
                              const struct in6_addr *saddr);

struct fib6_node *fib6_locate(struct fib6_node *root,
                              const struct in6_addr *daddr, int dst_len,
                              const struct in6_addr *saddr, int src_len,
                              bool exact_match);

void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
                    void *arg);

int fib6_add(struct fib6_node *root, struct rt6_info *rt,
             struct nl_info *info, struct mx6_config *mxc,
             struct netlink_ext_ack *extack);
int fib6_del(struct rt6_info *rt, struct nl_info *info);

void inet6_rt_notify(int event, struct rt6_info *rt, struct nl_info *info,
                     unsigned int flags);

void fib6_run_gc(unsigned long expires, struct net *net, bool force);

void fib6_gc_cleanup(void);

int fib6_init(void);

int ipv6_route_open(struct inode *inode, struct file *file);

int call_fib6_notifier(struct notifier_block *nb, struct net *net,
                       enum fib_event_type event_type,
                       struct fib_notifier_info *info);
int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
                        struct fib_notifier_info *info);

int __net_init fib6_notifier_init(struct net *net);
void __net_exit fib6_notifier_exit(struct net *net);

unsigned int fib6_tables_seq_read(struct net *net);
int fib6_tables_dump(struct net *net, struct notifier_block *nb);

void fib6_update_sernum(struct rt6_info *rt);
void fib6_update_sernum_upto_root(struct net *net, struct rt6_info *rt);

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
int fib6_rules_init(void);
void fib6_rules_cleanup(void);
bool fib6_rule_default(const struct fib_rule *rule);
int fib6_rules_dump(struct net *net, struct notifier_block *nb);
unsigned int fib6_rules_seq_read(struct net *net);

static inline bool fib6_rules_early_flow_dissect(struct net *net,
                                                 struct sk_buff *skb,
                                                 struct flowi6 *fl6,
                                                 struct flow_keys *flkeys)
{
        unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;

        if (!net->ipv6.fib6_rules_require_fldissect)
                return false;

        skb_flow_dissect_flow_keys(skb, flkeys, flag);
        fl6->fl6_sport = flkeys->ports.src;
        fl6->fl6_dport = flkeys->ports.dst;
        fl6->flowi6_proto = flkeys->basic.ip_proto;

        return true;
}
#else
static inline int               fib6_rules_init(void)
{
        return 0;
}
static inline void              fib6_rules_cleanup(void)
{
        return ;
}
static inline bool fib6_rule_default(const struct fib_rule *rule)
{
        return true;
}
static inline int fib6_rules_dump(struct net *net, struct notifier_block *nb)
{
        return 0;
}
static inline unsigned int fib6_rules_seq_read(struct net *net)
{
        return 0;
}
static inline bool fib6_rules_early_flow_dissect(struct net *net,
                                                 struct sk_buff *skb,
                                                 struct flowi6 *fl6,
                                                 struct flow_keys *flkeys)
{
        return false;
}
#endif
#endif