/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Alexander V. Chernikov
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <net/vnet.h>

#include <net/if.h>
#include <net/if_var.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_fib.h>

#include <net/route.h>
#include <net/route/nhop.h>
#include <net/route/route_ctl.h>
#include <net/route/route_var.h>
#include <net/route/fib_algo.h>

/*
 * Lockless radix lookup algo.
 *
 * Compiles immutable radix from the current routing table.
 * Used with small amount of routes (<1000).
 * As datastructure is immutable, it gets rebuild on each rtable change.
 *
 */

#define KEY_LEN_INET6   (offsetof(struct sa_in6, sin6_addr) + sizeof(struct in6_addr))
#define OFF_LEN_INET6   (8 * offsetof(struct sa_in6, sin6_addr))
struct sa_in6 {
        uint8_t                 sin6_len;
        uint8_t                 sin6_family;
        uint8_t                 pad[6];
        struct in6_addr         sin6_addr;
};
struct radix6_addr_entry {
        struct radix_node       rn[2];
        struct sa_in6           addr;
        struct nhop_object      *nhop;
};
#define LRADIX6_ITEM_SZ roundup2(sizeof(struct radix6_addr_entry), CACHE_LINE_SIZE)

struct lradix6_data {
        struct radix_node_head  *rnh;
        struct fib_data         *fd;
        void                    *mem; // raw radix_mem pointer to free
        void                    *radix_mem;
        uint32_t                alloc_items;
        uint32_t                num_items;
};

static struct nhop_object *
lradix6_lookup(void *algo_data, const struct flm_lookup_key key, uint32_t scopeid)
{
        struct radix_node_head *rnh = (struct radix_node_head *)algo_data;
        struct radix6_addr_entry *ent;
        struct sa_in6 addr6 = {
                .sin6_len = KEY_LEN_INET6,
                .sin6_addr = *key.addr6,
        };
        if (IN6_IS_SCOPE_LINKLOCAL(key.addr6))
                addr6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);
        ent = (struct radix6_addr_entry *)(rn_match(&addr6, &rnh->rh));
        if (ent != NULL)
                return (ent->nhop);
        return (NULL);
}

static uint8_t
lradix6_get_pref(const struct rib_rtable_info *rinfo)
{

        if (rinfo->num_prefixes < 10)
                return (255);
        else if (rinfo->num_prefixes < 10000)
                return (255 - rinfo->num_prefixes / 40);
        else
                return (1);
}

static enum flm_op_result
lradix6_init(uint32_t fibnum, struct fib_data *fd, void *_old_data, void **_data)
{
        struct lradix6_data *lr;
        struct rib_rtable_info rinfo;
        uint32_t count;
        void *mem;
 
        lr = malloc(sizeof(struct lradix6_data), M_RTABLE, M_NOWAIT | M_ZERO);
        if (lr == NULL || !rn_inithead((void **)&lr->rnh, OFF_LEN_INET6))
                return (FLM_REBUILD);
        fib_get_rtable_info(fib_get_rh(fd), &rinfo);

        count = rinfo.num_prefixes * 11 / 10;
        // count+1 adds at least 1 cache line
        mem = malloc((count + 1) * LRADIX6_ITEM_SZ, M_RTABLE, M_NOWAIT | M_ZERO);
        if (mem == NULL)
                return (FLM_REBUILD);
        lr->mem = mem;
        lr->radix_mem = (void *)roundup2((uintptr_t)mem, CACHE_LINE_SIZE);
        lr->alloc_items = count;
        lr->fd = fd;

        *_data = lr;

        return (FLM_SUCCESS);
}

static void
lradix6_destroy(void *_data)
{
        struct lradix6_data *lr = (struct lradix6_data *)_data;

        if (lr->rnh != NULL)
                rn_detachhead((void **)&lr->rnh);
        if (lr->mem != NULL)
                free(lr->mem, M_RTABLE);
        free(lr, M_RTABLE);
}

static enum flm_op_result
lradix6_add_route_cb(struct rtentry *rt, void *_data)
{
        struct lradix6_data *lr = (struct lradix6_data *)_data;
        struct radix6_addr_entry *ae;
        struct sockaddr_in6 *rt_dst, *rt_mask;
        struct sa_in6 mask;
        struct radix_node *rn;
        struct nhop_object *nh;

        nh = rt_get_raw_nhop(rt);

        if (lr->num_items >= lr->alloc_items)
                return (FLM_REBUILD);

        ae = (struct radix6_addr_entry *)((char *)lr->radix_mem + lr->num_items * LRADIX6_ITEM_SZ);
        lr->num_items++;

        ae->nhop = nh;

        rt_dst = (struct sockaddr_in6 *)rt_key(rt);
        rt_mask = (struct sockaddr_in6 *)rt_mask(rt);

        ae->addr.sin6_len = KEY_LEN_INET6;
        ae->addr.sin6_addr = rt_dst->sin6_addr;

        if (rt_mask != NULL) {
                bzero(&mask, sizeof(mask));
                mask.sin6_len = KEY_LEN_INET6;
                mask.sin6_addr = rt_mask->sin6_addr;
                rt_mask = (struct sockaddr_in6 *)&mask;
        }

        rn = lr->rnh->rnh_addaddr((struct sockaddr *)&ae->addr,
            (struct sockaddr *)rt_mask, &lr->rnh->rh, ae->rn);
        if (rn == NULL)
                return (FLM_REBUILD);

        return (FLM_SUCCESS);
}

static enum flm_op_result
lradix6_end_dump(void *_data, struct fib_dp *dp)
{
        struct lradix6_data *lr = (struct lradix6_data *)_data;

        dp->f = lradix6_lookup;
        dp->arg = lr->rnh;

        return (FLM_SUCCESS);
}

static enum flm_op_result
lradix6_change_cb(struct rib_head *rnh, struct rib_cmd_info *rc,
    void *_data)
{

        return (FLM_REBUILD);
}

struct fib_lookup_module flm_radix6_lockless = {
        .flm_name = "radix6_lockless",
        .flm_family = AF_INET6,
        .flm_init_cb = lradix6_init,
        .flm_destroy_cb = lradix6_destroy,
        .flm_dump_rib_item_cb = lradix6_add_route_cb,
        .flm_dump_end_cb = lradix6_end_dump,
        .flm_change_rib_item_cb = lradix6_change_cb,
        .flm_get_pref = lradix6_get_pref,
};

/*
 * Fallback lookup algorithm.
 * This is a simple wrapper around system radix.
 */

struct radix6_data {
        struct fib_data *fd;
        struct rib_head *rh;
};

static struct nhop_object *
radix6_lookup(void *algo_data, const struct flm_lookup_key key, uint32_t scopeid)
{
        RIB_RLOCK_TRACKER;
        struct rib_head *rh = (struct rib_head *)algo_data;
        struct radix_node *rn;
        struct nhop_object *nh;

        /* Prepare lookup key */
        struct sockaddr_in6 sin6 = {
                .sin6_family = AF_INET6,
                .sin6_len = sizeof(struct sockaddr_in6),
                .sin6_addr = *key.addr6,
        };
        if (IN6_IS_SCOPE_LINKLOCAL(key.addr6))
                sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);

        nh = NULL;
        RIB_RLOCK(rh);
        rn = rn_match((void *)&sin6, &rh->head);
        if (rn != NULL && ((rn->rn_flags & RNF_ROOT) == 0))
                nh = (RNTORT(rn))->rt_nhop;
        RIB_RUNLOCK(rh);

        return (nh);
}

struct nhop_object *
fib6_radix_lookup_nh(uint32_t fibnum, const struct in6_addr *dst6, uint32_t scopeid)
{
        struct rib_head *rh = rh = rt_tables_get_rnh(fibnum, AF_INET6);
        const struct flm_lookup_key key = { .addr6 = dst6 };

        if (rh == NULL)
                return (NULL);

        return (radix6_lookup(rh, key, scopeid));
}

static uint8_t
radix6_get_pref(const struct rib_rtable_info *rinfo)
{

        return (50);
}

static enum flm_op_result
radix6_init(uint32_t fibnum, struct fib_data *fd, void *_old_data, void **_data)
{
        struct radix6_data *r6;

        r6 = malloc(sizeof(struct radix6_data), M_RTABLE, M_NOWAIT | M_ZERO);
        if (r6 == NULL)
                return (FLM_REBUILD);
        r6->fd = fd;
        r6->rh = fib_get_rh(fd);

        *_data = r6;

        return (FLM_SUCCESS);
}

static void
radix6_destroy(void *_data)
{

        free(_data, M_RTABLE);
}

static enum flm_op_result
radix6_add_route_cb(struct rtentry *rt, void *_data)
{

        return (FLM_SUCCESS);
}

static enum flm_op_result
radix6_end_dump(void *_data, struct fib_dp *dp)
{
        struct radix6_data *r6 = (struct radix6_data *)_data;

        dp->f = radix6_lookup;
        dp->arg = r6->rh;

        return (FLM_SUCCESS);
}

static enum flm_op_result
radix6_change_cb(struct rib_head *rnh, struct rib_cmd_info *rc,
    void *_data)
{

        return (FLM_SUCCESS);
}

struct fib_lookup_module flm_radix6 = {
        .flm_name = "radix6",
        .flm_family = AF_INET6,
        .flm_init_cb = radix6_init,
        .flm_destroy_cb = radix6_destroy,
        .flm_dump_rib_item_cb = radix6_add_route_cb,
        .flm_dump_end_cb = radix6_end_dump,
        .flm_change_rib_item_cb = radix6_change_cb,
        .flm_get_pref = radix6_get_pref,
};

static void
fib6_algo_init(void *dummy __unused)
{

        fib_module_register(&flm_radix6_lockless);
        fib_module_register(&flm_radix6);
}
SYSINIT(fib6_algo_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, fib6_algo_init, NULL);