/*-
 * Copyright (c) 2015
 *      Alexander V. Chernikov <melifaro@FreeBSD.org>
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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_inet.h"
#include "opt_inet6.h"
#include "opt_route.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/kernel.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/if_private.h>
#include <net/route.h>
#include <net/route/route_ctl.h>
#include <net/route/route_var.h>
#include <net/route/fib_algo.h>
#include <net/route/nhop.h>
#include <net/toeplitz.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_mroute.h>
#include <netinet/ip6.h>
#include <netinet6/in6_fib.h>
#include <netinet6/in6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/scope6_var.h>

#include <net/if_types.h>

#ifdef INET6

CHK_STRUCT_ROUTE_COMPAT(struct route_in6, ro_dst);

#ifdef FIB_ALGO
VNET_DEFINE(struct fib_dp *, inet6_dp);
#endif

struct _hash_5tuple_ipv6 {
        struct in6_addr src;
        struct in6_addr dst;
        unsigned short src_port;
        unsigned short dst_port;
        char proto;
        char spare[3];
};
_Static_assert(sizeof(struct _hash_5tuple_ipv6) == 40,
    "_hash_5tuple_ipv6 size is wrong");

uint32_t
fib6_calc_software_hash(const struct in6_addr *src, const struct in6_addr *dst,
    unsigned short src_port, unsigned short dst_port, char proto,
    uint32_t *phashtype)
{
        struct _hash_5tuple_ipv6 data;

        data.src = *src;
        data.dst = *dst;
        data.src_port = src_port;
        data.dst_port = dst_port;
        data.proto = proto;
        data.spare[0] = data.spare[1] = data.spare[2] = 0;

        *phashtype = M_HASHTYPE_OPAQUE_HASH;

        return (toeplitz_hash(MPATH_ENTROPY_KEY_LEN, mpath_entropy_key,
          sizeof(data), (uint8_t *)&data));
}

/*
 * Looks up path in fib @fibnum specified by @dst.
 * Assumes scope is deembedded and provided in @scopeid.
 *
 * Returns path nexthop on success. Nexthop is safe to use
 *  within the current network epoch. If longer lifetime is required,
 *  one needs to pass NHR_REF as a flag. This will return referenced
 *  nexthop.
 */
#ifdef FIB_ALGO
struct nhop_object *
fib6_lookup(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid, uint32_t flags, uint32_t flowid)
{
        struct nhop_object *nh;
        struct fib_dp *dp = &V_inet6_dp[fibnum];
        struct flm_lookup_key key = {.addr6 = dst6 };

        nh = dp->f(dp->arg, key, scopeid);
        if (nh != NULL) {
                nh = nhop_select(nh, flowid);
                /* Ensure route & ifp is UP */
                if (RT_LINK_IS_UP(nh->nh_ifp)) {
                        if (flags & NHR_REF)
                                nhop_ref_object(nh);
                        return (nh);
                }
        }
        RTSTAT_INC(rts_unreach);
        return (NULL);
}
#else
struct nhop_object *
fib6_lookup(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid, uint32_t flags, uint32_t flowid)
{
        RIB_RLOCK_TRACKER;
        struct rib_head *rh;
        struct radix_node *rn;
        struct nhop_object *nh;

        KASSERT((fibnum < rt_numfibs), ("fib6_lookup: bad fibnum"));
        rh = rt_tables_get_rnh(fibnum, AF_INET6);
        if (rh == NULL)
                return (NULL);

        struct sockaddr_in6 sin6 = {
                .sin6_len = sizeof(struct sockaddr_in6),
                .sin6_addr = *dst6,
        };

        /* Assume scopeid is valid and embed it directly */
        if (IN6_IS_SCOPE_LINKLOCAL(dst6))
                sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);

        RIB_RLOCK(rh);
        rn = rh->rnh_matchaddr((void *)&sin6, &rh->head);
        if (rn != NULL && ((rn->rn_flags & RNF_ROOT) == 0)) {
                nh = nhop_select((RNTORT(rn))->rt_nhop, flowid);
                /* Ensure route & ifp is UP */
                if (RT_LINK_IS_UP(nh->nh_ifp)) {
                        if (flags & NHR_REF)
                                nhop_ref_object(nh);
                        RIB_RUNLOCK(rh);
                        return (nh);
                }
        }
        RIB_RUNLOCK(rh);

        RTSTAT_INC(rts_unreach);
        return (NULL);
}
#endif

inline static int
check_urpf_nhop(const struct nhop_object *nh, uint32_t flags,
    const struct ifnet *src_if)
{

        if (src_if != NULL && nh->nh_aifp == src_if) {
                return (1);
        }
        if (src_if == NULL) {
                if ((flags & NHR_NODEFAULT) == 0)
                        return (1);
                else if ((nh->nh_flags & NHF_DEFAULT) == 0)
                        return (1);
        }

        return (0);
}

static int
check_urpf(struct nhop_object *nh, uint32_t flags,
    const struct ifnet *src_if)
{
        const struct weightened_nhop *wn;
        uint32_t num_nhops;

        if (NH_IS_NHGRP(nh)) {
                wn = nhgrp_get_nhops((struct nhgrp_object *)nh, &num_nhops);
                for (int i = 0; i < num_nhops; i++) {
                        if (check_urpf_nhop(wn[i].nh, flags, src_if) != 0)
                                return (1);
                }
                return (0);
        }

        return (check_urpf_nhop(nh, flags, src_if));
}

#ifndef FIB_ALGO
static struct nhop_object *
lookup_nhop(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid)
{
        RIB_RLOCK_TRACKER;
        struct rib_head *rh;
        struct radix_node *rn;
        struct nhop_object *nh;

        KASSERT((fibnum < rt_numfibs), ("fib6_check_urpf: bad fibnum"));
        rh = rt_tables_get_rnh(fibnum, AF_INET6);
        if (rh == NULL)
                return (NULL);

        /* Prepare lookup key */
        struct sockaddr_in6 sin6 = {
                .sin6_len = sizeof(struct sockaddr_in6),
                .sin6_addr = *dst6,
        };

        /* Assume scopeid is valid and embed it directly */
        if (IN6_IS_SCOPE_LINKLOCAL(dst6))
                sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);

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

        return (nh);
}
#endif

/*
 * Performs reverse path forwarding lookup.
 * If @src_if is non-zero, verifies that at least 1 path goes via
 *   this interface.
 * If @src_if is zero, verifies that route exist.
 * if @flags contains NHR_NOTDEFAULT, do not consider default route.
 *
 * Returns 1 if route matching conditions is found, 0 otherwise.
 */
int
fib6_check_urpf(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid, uint32_t flags, const struct ifnet *src_if)
{
        struct nhop_object *nh;
#ifdef FIB_ALGO
        struct fib_dp *dp = &V_inet6_dp[fibnum];
        struct flm_lookup_key key = {.addr6 = dst6 };

        nh = dp->f(dp->arg, key, scopeid);
#else
        nh = lookup_nhop(fibnum, dst6, scopeid);
#endif
        if (nh != NULL)
                return (check_urpf(nh, flags, src_if));
        return (0);
}

/*
 * Function returning prefix match data along with the nexthop data.
 * Intended to be used by the control plane code.
 * Supported flags:
 *  NHR_UNLOCKED: do not lock radix during lookup.
 * Returns pointer to rtentry and raw nexthop in @rnd. Both rtentry
 *  and nexthop are safe to use within current epoch. Note:
 * Note: rnd_nhop can actually be the nexthop group.
 */
struct rtentry *
fib6_lookup_rt(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid, uint32_t flags, struct route_nhop_data *rnd)
{
        RIB_RLOCK_TRACKER;
        struct rib_head *rh;
        struct radix_node *rn;
        struct rtentry *rt;

        KASSERT((fibnum < rt_numfibs), ("fib6_lookup: bad fibnum"));
        rh = rt_tables_get_rnh(fibnum, AF_INET6);
        if (rh == NULL)
                return (NULL);

        struct sockaddr_in6 sin6 = {
                .sin6_len = sizeof(struct sockaddr_in6),
                .sin6_addr = *dst6,
        };

        /* Assume scopeid is valid and embed it directly */
        if (IN6_IS_SCOPE_LINKLOCAL(dst6))
                sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);

        rt = NULL;
        if (!(flags & NHR_UNLOCKED))
                RIB_RLOCK(rh);
        rn = rh->rnh_matchaddr((void *)&sin6, &rh->head);
        if (rn != NULL && ((rn->rn_flags & RNF_ROOT) == 0)) {
                rt = (struct rtentry *)rn;
                rnd->rnd_nhop = rt->rt_nhop;
                rnd->rnd_weight = rt->rt_weight;
        }
        if (!(flags & NHR_UNLOCKED))
                RIB_RUNLOCK(rh);

        return (rt);
}

struct nhop_object *
fib6_lookup_debugnet(uint32_t fibnum, const struct in6_addr *dst6,
    uint32_t scopeid, uint32_t flags)
{
        struct rtentry *rt;
        struct route_nhop_data rnd;

        rt = fib6_lookup_rt(fibnum, dst6, scopeid, NHR_UNLOCKED, &rnd);
        if (rt != NULL) {
                struct nhop_object *nh = nhop_select(rnd.rnd_nhop, 0);
                /* Ensure route & ifp is UP */
                if (RT_LINK_IS_UP(nh->nh_ifp))
                        return (nh);
        }

        return (NULL);
}

#endif