/*-
 * 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 <sys/cdefs.h>
#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/kernel.h>
#include <sys/epoch.h>

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

#define DEBUG_MOD_NAME  nhop_ctl
#define DEBUG_MAX_LEVEL LOG_DEBUG
#include <net/route/route_debug.h>
_DECLARE_DEBUG(LOG_INFO);

/*
 * This file contains core functionality for the nexthop ("nhop") route subsystem.
 * The business logic needed to create nexhop objects is implemented here.
 *
 * Nexthops in the original sense are the objects containing all the necessary
 * information to forward the packet to the selected destination.
 * In particular, nexthop is defined by a combination of
 *  ifp, ifa, aifp, mtu, gw addr(if set), nh_type, nh_upper_family, mask of rt_flags and
 *    NHF_DEFAULT
 *
 * Additionally, each nexthop gets assigned its unique index (nexthop index).
 * It serves two purposes: first one is to ease the ability of userland programs to
 *  reference nexthops by their index. The second one allows lookup algorithms to
 *  to store index instead of pointer (2 bytes vs 8) as a lookup result.
 * All nexthops are stored in the resizable hash table.
 *
 * Basically, this file revolves around supporting 3 functions:
 * 1) nhop_create_from_info / nhop_create_from_nhop, which contains all
 *  business logic on filling the nexthop fields based on the provided request.
 * 2) nhop_get(), which gets a usable referenced nexthops.
 *
 * Conventions:
 * 1) non-exported functions start with verb
 * 2) exported function starts with the subsystem prefix: "nhop"
 */

static int dump_nhop_entry(struct rib_head *rh, struct nhop_object *nh, struct sysctl_req *w);

static int finalize_nhop(struct nh_control *ctl, struct nhop_object *nh, bool link);
static struct ifnet *get_aifp(const struct nhop_object *nh);
static void fill_sdl_from_ifp(struct sockaddr_dl_short *sdl, const struct ifnet *ifp);

static void destroy_nhop_epoch(epoch_context_t ctx);
static void destroy_nhop(struct nhop_object *nh);
static void nhops_ifnet_event(void *arg, struct ifnet *ifp, int state);
static void nhops_ifnet_link_event(void *arg, struct ifnet *ifp, int state);

_Static_assert(__offsetof(struct nhop_object, nh_ifp) == 32,
    "nhop_object: wrong nh_ifp offset");
_Static_assert(sizeof(struct nhop_object) <= 128,
    "nhop_object: size exceeds 128 bytes");

static uma_zone_t nhops_zone;   /* Global zone for each and every nexthop */

#define NHOP_OBJECT_ALIGNED_SIZE        roundup2(sizeof(struct nhop_object), \
                                                        2 * CACHE_LINE_SIZE)
#define NHOP_PRIV_ALIGNED_SIZE          roundup2(sizeof(struct nhop_priv), \
                                                        2 * CACHE_LINE_SIZE)
void
nhops_init(void)
{

        nhops_zone = uma_zcreate("routing nhops",
            NHOP_OBJECT_ALIGNED_SIZE + NHOP_PRIV_ALIGNED_SIZE,
            NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
        EVENTHANDLER_REGISTER(ifnet_event, nhops_ifnet_event, NULL,
            EVENTHANDLER_PRI_ANY);
        EVENTHANDLER_REGISTER(ifnet_link_event, nhops_ifnet_link_event, NULL,
            EVENTHANDLER_PRI_ANY);
}

/*
 * Fetches the interface of source address used by the route.
 * In all cases except interface-address-route and prefsrc it
 * would be the same as the transmit interfaces.
 * However, for the interface address this function will return
 * this interface ifp instead of loopback. This is needed to support
 * link-local IPv6 loopback communications.
 *
 * Returns found ifp.
 */
static struct ifnet *
get_aifp(const struct nhop_object *nh)
{
        struct ifnet *aifp = NULL;

        /*
         * Adjust the "outgoing" interface.  If we're going to loop
         * the packet back to ourselves, the ifp would be the loopback
         * interface. However, we'd rather know the interface associated
         * to the destination address (which should probably be one of
         * our own addresses).
         */
        if ((nh->nh_ifp->if_flags & IFF_LOOPBACK) &&
                        nh->gw_sa.sa_family == AF_LINK) {
                aifp = ifnet_byindex(nh->gwl_sa.sdl_index);
                if (aifp == NULL) {
                        FIB_NH_LOG(LOG_WARNING, nh, "unable to get aifp for %s index %d",
                                if_name(nh->nh_ifp), nh->gwl_sa.sdl_index);
                }
        } else if ((nh->nh_flags & NHF_PREFSRC) != 0)
                aifp = nh->nh_ifa->ifa_ifp;

        if (aifp == NULL)
                aifp = nh->nh_ifp;

        return (aifp);
}

int
cmp_priv(const struct nhop_priv *key, const struct nhop_priv *search)
{

        if (memcmp(key->nh, search->nh, NHOP_END_CMP) != 0)
                return (0);

        if (memcmp(key, search, NH_PRIV_END_CMP) != 0)
                return (0);

        if (key->nh_metric != RT_WILDCARD_METRIC &&
            key->nh_metric != search->nh_metric)
                return (0);

        return (1);
}

/*
 * Conditionally sets @nh mtu data based on the @info data.
 */
static void
set_nhop_mtu_from_info(struct nhop_object *nh, const struct rt_addrinfo *info)
{
        if (info->rti_mflags & RTV_MTU)
                nhop_set_mtu(nh, info->rti_rmx->rmx_mtu, true);
}

static void
set_nhop_metric_from_info(struct nhop_object *nh, const struct rt_addrinfo *info)
{
        uint32_t metric;

        if (info->rti_mflags & RTV_METRIC)
                metric = info->rti_rmx->rmx_metric;
        else
                metric = RT_DEFAULT_METRIC;

        nhop_set_metric(nh, metric);
}

/*
 * Fills in shorted link-level sockadd version suitable to be stored inside the
 *  nexthop gateway buffer.
 */
static void
fill_sdl_from_ifp(struct sockaddr_dl_short *sdl, const struct ifnet *ifp)
{

        bzero(sdl, sizeof(struct sockaddr_dl_short));
        sdl->sdl_family = AF_LINK;
        sdl->sdl_len = sizeof(struct sockaddr_dl_short);
        sdl->sdl_index = ifp->if_index;
        sdl->sdl_type = ifp->if_type;
}

static int
set_nhop_gw_from_info(struct nhop_object *nh, struct rt_addrinfo *info)
{
        struct sockaddr *gw;

        gw = info->rti_info[RTAX_GATEWAY];
        MPASS(gw != NULL);
        bool is_gw = info->rti_flags & RTF_GATEWAY;

        if ((gw->sa_family == AF_LINK) && !is_gw) {

                /*
                 * Interface route with interface specified by the interface
                 * index in sockadd_dl structure. It is used in the IPv6 loopback
                 * output code, where we need to preserve the original interface
                 * to maintain proper scoping.
                 * Despite the fact that nexthop code stores original interface
                 * in the separate field (nh_aifp, see below), write AF_LINK
                 * compatible sa with shorter total length.
                 */
                struct sockaddr_dl *sdl = (struct sockaddr_dl *)gw;
                struct ifnet *ifp = ifnet_byindex(sdl->sdl_index);
                if (ifp == NULL) {
                        FIB_NH_LOG(LOG_DEBUG, nh, "error: invalid ifindex %d",
                            sdl->sdl_index);
                        return (EINVAL);
                }
                nhop_set_direct_gw(nh, ifp);
        } else {

                /*
                 * Multiple options here:
                 *
                 * 1) RTF_GATEWAY with IPv4/IPv6 gateway data
                 * 2) Interface route with IPv4/IPv6 address of the
                 *   matching interface. Some routing daemons do that
                 *   instead of specifying ifindex in AF_LINK.
                 *
                 * In both cases, save the original nexthop to make the callers
                 *   happy.
                 */
                if (!nhop_set_gw(nh, gw, is_gw))
                        return (EINVAL);
        }
        return (0);
}

static void
set_nhop_expire_from_info(struct nhop_object *nh, const struct rt_addrinfo *info)
{
        uint32_t nh_expire = 0;

        /* Kernel -> userland timebase conversion. */
        if ((info->rti_mflags & RTV_EXPIRE) && (info->rti_rmx->rmx_expire > 0))
                nh_expire = info->rti_rmx->rmx_expire - time_second + time_uptime;
        nhop_set_expire(nh, nh_expire);
}

/*
 * Creates a new nexthop based on the information in @info.
 *
 * Returns:
 * 0 on success, filling @nh_ret with the desired nexthop object ptr
 * errno otherwise
 */
int
nhop_create_from_info(struct rib_head *rnh, struct rt_addrinfo *info,
    struct nhop_object **nh_ret)
{
        int error;

        NET_EPOCH_ASSERT();

        MPASS(info->rti_ifa != NULL);
        MPASS(info->rti_ifp != NULL);

        if (info->rti_info[RTAX_GATEWAY] == NULL) {
                FIB_RH_LOG(LOG_DEBUG, rnh, "error: empty gateway");
                return (EINVAL);
        }

        struct nhop_object *nh = nhop_alloc(rnh->rib_fibnum, rnh->rib_family);
        if (nh == NULL)
                return (ENOMEM);

        if ((error = set_nhop_gw_from_info(nh, info)) != 0) {
                nhop_free(nh);
                return (error);
        }
        nhop_set_transmit_ifp(nh, info->rti_ifp);

        nhop_set_blackhole(nh, info->rti_flags & (RTF_BLACKHOLE | RTF_REJECT));

        error = rnh->rnh_set_nh_pfxflags(rnh->rib_fibnum, info->rti_info[RTAX_DST],
            info->rti_info[RTAX_NETMASK], nh);

        nhop_set_redirect(nh, info->rti_flags & RTF_DYNAMIC);
        nhop_set_pinned(nh, info->rti_flags & RTF_PINNED);
        set_nhop_expire_from_info(nh, info);
        nhop_set_rtflags(nh, info->rti_flags);

        set_nhop_mtu_from_info(nh, info);
        set_nhop_metric_from_info(nh, info);
        nhop_set_src(nh, info->rti_ifa);

        /*
         * The remaining fields are either set from nh_preadd hook
         * or are computed from the provided data
         */
        *nh_ret = nhop_get_nhop(nh, &error);

        return (error);
}

/*
 * Gets linked nhop using the provided @nh nexhop data.
 * If linked nhop is found, returns it, freeing the provided one.
 * If there is no such nexthop, attaches the remaining data to the
 *  provided nexthop and links it.
 *
 * Returns 0 on success, storing referenced nexthop in @pnh.
 * Otherwise, errno is returned.
 */
struct nhop_object *
nhop_get_nhop(struct nhop_object *nh, int *perror)
{
        struct rib_head *rnh = nhop_get_rh(nh);

        if (__predict_false(rnh == NULL)) {
                *perror = EAFNOSUPPORT;
                nhop_free(nh);
                return (NULL);
        }

        return (nhop_get_nhop_internal(rnh, nh, perror));
}

struct nhop_object *
nhop_get_nhop_internal(struct rib_head *rnh, struct nhop_object *nh, int *perror)
{
        struct nhop_priv *tmp_priv;
        int error;

        nh->nh_aifp = get_aifp(nh);

        /* Give the protocols chance to augment nexthop properties */
        error = rnh->rnh_augment_nh(rnh->rib_fibnum, nh);
        if (error != 0) {
                nhop_free(nh);
                *perror = error;
                return (NULL);
        }

        tmp_priv = find_nhop(rnh->nh_control, nh->nh_priv);
        if (tmp_priv != NULL) {
                nhop_free(nh);
                *perror = 0;
                return (tmp_priv->nh);
        }

        /*
         * Existing nexthop not found, need to create new one.
         * Note: multiple simultaneous requests
         *  can result in multiple equal nexhops existing in the
         *  nexthop table. This is not a not a problem until the
         *  relative number of such nexthops is significant, which
         *  is extremely unlikely.
         */
        *perror = finalize_nhop(rnh->nh_control, nh, true);
        return (*perror == 0 ? nh : NULL);
}

/*
 * Gets referenced but unlinked nhop.
 * Alocates/references the remaining bits of the nexthop data, so
 *  it can be safely linked later or used as a clone source.
 *
 * Returns 0 on success.
 */
int
nhop_get_unlinked(struct nhop_object *nh)
{
        struct rib_head *rnh = nhop_get_rh(nh);

        if (__predict_false(rnh == NULL)) {
                nhop_free(nh);
                return (EAFNOSUPPORT);
        }

        nh->nh_aifp = get_aifp(nh);

        return (finalize_nhop(rnh->nh_control, nh, false));
}


/*
 * Update @nh with data supplied in @info.
 * This is a helper function to support route changes.
 *
 * It limits the changes that can be done to the route to the following:
 * 1) all combination of gateway changes
 * 2) route flags (FLAG[123],STATIC)
 * 3) route MTU
 *
 * Returns:
 * 0 on success, errno otherwise
 */
static int
alter_nhop_from_info(struct nhop_object *nh, struct rt_addrinfo *info)
{
        struct sockaddr *info_gw;
        int error;

        /* Update MTU if set in the request*/
        set_nhop_mtu_from_info(nh, info);

        /* Only RTF_FLAG[123] and RTF_STATIC */
        uint32_t rt_flags = nhop_get_rtflags(nh) & ~RT_CHANGE_RTFLAGS_MASK;
        rt_flags |= info->rti_flags & RT_CHANGE_RTFLAGS_MASK;
        nhop_set_rtflags(nh, rt_flags);

        /* Consider gateway change */
        info_gw = info->rti_info[RTAX_GATEWAY];
        if (info_gw != NULL) {
                error = set_nhop_gw_from_info(nh, info);
                if (error != 0)
                        return (error);
        }

        if (info->rti_ifa != NULL)
                nhop_set_src(nh, info->rti_ifa);
        if (info->rti_ifp != NULL)
                nhop_set_transmit_ifp(nh, info->rti_ifp);

        return (0);
}

/*
 * Creates new nexthop based on @nh_orig and augmentation data from @info.
 * Helper function used in the route changes, please see
 *   alter_nhop_from_info() comments for more details.
 *
 * Returns:
 * 0 on success, filling @nh_ret with the desired nexthop object
 * errno otherwise
 */
int
nhop_create_from_nhop(struct rib_head *rnh, const struct nhop_object *nh_orig,
    struct rt_addrinfo *info, struct nhop_object **pnh)
{
        struct nhop_object *nh;
        int error;

        NET_EPOCH_ASSERT();

        nh = nhop_alloc(rnh->rib_fibnum, rnh->rib_family);
        if (nh == NULL)
                return (ENOMEM);

        nhop_copy(nh, nh_orig);

        error = alter_nhop_from_info(nh, info);
        if (error != 0) {
                nhop_free(nh);
                return (error);
        }
        set_nhop_expire_from_info(nh, info);

        *pnh = nhop_get_nhop(nh, &error);

        return (error);
}

static bool
reference_nhop_deps(struct nhop_object *nh)
{
        if (!ifa_try_ref(nh->nh_ifa))
                return (false);
        nh->nh_aifp = get_aifp(nh);
        if (!if_try_ref(nh->nh_aifp)) {
                ifa_free(nh->nh_ifa);
                return (false);
        }
        FIB_NH_LOG(LOG_DEBUG2, nh, "nh_aifp: %s nh_ifp %s",
            if_name(nh->nh_aifp), if_name(nh->nh_ifp));
        if (!if_try_ref(nh->nh_ifp)) {
                ifa_free(nh->nh_ifa);
                if_rele(nh->nh_aifp);
                return (false);
        }

        return (true);
}

/*
 * Alocates/references the remaining bits of nexthop data and links
 *  it to the hash table.
 * Returns 0 if successful,
 *  errno otherwise. @nh_priv is freed in case of error.
 */
static int
finalize_nhop(struct nh_control *ctl, struct nhop_object *nh, bool link)
{

        /* Allocate per-cpu packet counter */
        nh->nh_pksent = counter_u64_alloc(M_NOWAIT);
        if (nh->nh_pksent == NULL) {
                FIB_NH_LOG(LOG_WARNING, nh, "counter_u64_alloc() failed");
                nhop_free(nh);
                RTSTAT_INC(rts_nh_alloc_failure);
                return (ENOMEM);
        }

        if (!reference_nhop_deps(nh)) {
                FIB_NH_LOG(LOG_WARNING, nh, "interface reference failed");
                counter_u64_free(nh->nh_pksent);
                nhop_free(nh);
                RTSTAT_INC(rts_nh_alloc_failure);
                return (EAGAIN);
        }

        /* Save vnet to ease destruction */
        nh->nh_priv->nh_vnet = curvnet;

        /* Please see nhop_free() comments on the initial value */
        refcount_init(&nh->nh_priv->nh_linked, 2);

        MPASS(nh->nh_priv->nh_fibnum == ctl->ctl_rh->rib_fibnum);

        if (!link) {
                refcount_release(&nh->nh_priv->nh_linked);
                NHOPS_WLOCK(ctl);
                nh->nh_priv->nh_finalized = 1;
                NHOPS_WUNLOCK(ctl);
        } else if (link_nhop(ctl, nh->nh_priv) == 0) {
                /*
                 * Adding nexthop to the datastructures
                 *  failed. Call destructor w/o waiting for
                 *  the epoch end, as nexthop is not used
                 *  and return.
                 */
                char nhbuf[NHOP_PRINT_BUFSIZE];
                FIB_NH_LOG(LOG_WARNING, nh, "failed to link %s",
                    nhop_print_buf(nh, nhbuf, sizeof(nhbuf)));
                destroy_nhop(nh);

                return (ENOBUFS);
        }

        IF_DEBUG_LEVEL(LOG_DEBUG) {
                char nhbuf[NHOP_PRINT_BUFSIZE] __unused;
                FIB_NH_LOG(LOG_DEBUG, nh, "finalized: %s",
                    nhop_print_buf(nh, nhbuf, sizeof(nhbuf)));
        }

        return (0);
}

static void
destroy_nhop(struct nhop_object *nh)
{
        if_rele(nh->nh_ifp);
        if_rele(nh->nh_aifp);
        ifa_free(nh->nh_ifa);
        counter_u64_free(nh->nh_pksent);

        uma_zfree(nhops_zone, nh);
}

/*
 * Epoch callback indicating nhop is safe to destroy
 */
static void
destroy_nhop_epoch(epoch_context_t ctx)
{
        struct nhop_priv *nh_priv;

        nh_priv = __containerof(ctx, struct nhop_priv, nh_epoch_ctx);

        destroy_nhop(nh_priv->nh);
}

void
nhop_ref_object(struct nhop_object *nh)
{
        u_int old __diagused;

        old = refcount_acquire(&nh->nh_priv->nh_refcnt);
        KASSERT(old > 0, ("%s: nhop object %p has 0 refs", __func__, nh));
}

int
nhop_try_ref_object(struct nhop_object *nh)
{

        return (refcount_acquire_if_not_zero(&nh->nh_priv->nh_refcnt));
}

void
nhop_free(struct nhop_object *nh)
{
        struct nh_control *ctl;
        struct nhop_priv *nh_priv = nh->nh_priv;
        struct epoch_tracker et;

        if (!refcount_release(&nh_priv->nh_refcnt))
                return;

        /* allows to use nhop_free() during nhop init */
        if (__predict_false(nh_priv->nh_finalized == 0)) {
                uma_zfree(nhops_zone, nh);
                return;
        }

        IF_DEBUG_LEVEL(LOG_DEBUG) {
                char nhbuf[NHOP_PRINT_BUFSIZE] __unused;
                FIB_NH_LOG(LOG_DEBUG, nh, "deleting %s",
                    nhop_print_buf(nh, nhbuf, sizeof(nhbuf)));
        }

        /*
         * There are only 2 places, where nh_linked can be decreased:
         *  rib destroy (nhops_destroy_rib) and this function.
         * nh_link can never be increased.
         *
         * Hence, use initial value of 2 to make use of
         *  refcount_release_if_not_last().
         *
         * There can be two scenarious when calling this function:
         *
         * 1) nh_linked value is 2. This means that either
         *  nhops_destroy_rib() has not been called OR it is running,
         *  but we are guaranteed that nh_control won't be freed in
         *  this epoch. Hence, nexthop can be safely unlinked.
         *
         * 2) nh_linked value is 1. In that case, nhops_destroy_rib()
         *  has been called and nhop unlink can be skipped.
         */

        NET_EPOCH_ENTER(et);
        if (refcount_release_if_not_last(&nh_priv->nh_linked)) {
                ctl = nh_priv->nh_control;
                if (unlink_nhop(ctl, nh_priv) == NULL) {
                        /* Do not try to reclaim */
                        char nhbuf[NHOP_PRINT_BUFSIZE];
                        FIB_NH_LOG(LOG_WARNING, nh, "failed to unlink %s",
                            nhop_print_buf(nh, nhbuf, sizeof(nhbuf)));
                        NET_EPOCH_EXIT(et);
                        return;
                }
        }
        NET_EPOCH_EXIT(et);

        NET_EPOCH_CALL(destroy_nhop_epoch, &nh_priv->nh_epoch_ctx);
}

void
nhop_ref_any(struct nhop_object *nh)
{

        if (!NH_IS_NHGRP(nh))
                nhop_ref_object(nh);
        else
                nhgrp_ref_object((struct nhgrp_object *)nh);
}

void
nhop_free_any(struct nhop_object *nh)
{

        if (!NH_IS_NHGRP(nh))
                nhop_free(nh);
        else
                nhgrp_free((struct nhgrp_object *)nh);
}

/* Nhop-related methods */

/*
 * Allocates an empty unlinked nhop object.
 * Returns object pointer or NULL on failure
 */
struct nhop_object *
nhop_alloc(uint32_t fibnum, int family)
{
        struct nhop_object *nh;
        struct nhop_priv *nh_priv;

        nh = (struct nhop_object *)uma_zalloc(nhops_zone, M_NOWAIT | M_ZERO);
        if (__predict_false(nh == NULL))
                return (NULL);

        nh_priv = (struct nhop_priv *)((char *)nh + NHOP_OBJECT_ALIGNED_SIZE);
        nh->nh_priv = nh_priv;
        nh_priv->nh = nh;

        nh_priv->nh_upper_family = family;
        nh_priv->nh_fibnum = fibnum;

        /* Setup refcount early to allow nhop_free() to work */
        refcount_init(&nh_priv->nh_refcnt, 1);

        return (nh);
}

void
nhop_copy(struct nhop_object *nh, const struct nhop_object *nh_orig)
{
        struct nhop_priv *nh_priv = nh->nh_priv;

        nh->nh_flags = nh_orig->nh_flags;
        nh->nh_mtu = nh_orig->nh_mtu;
        memcpy(&nh->gw_sa, &nh_orig->gw_sa, nh_orig->gw_sa.sa_len);
        nh->nh_ifp = nh_orig->nh_ifp;
        nh->nh_ifa = nh_orig->nh_ifa;
        nh->nh_aifp = nh_orig->nh_aifp;

        nh_priv->nh_upper_family = nh_orig->nh_priv->nh_upper_family;
        nh_priv->nh_neigh_family = nh_orig->nh_priv->nh_neigh_family;
        nh_priv->nh_type = nh_orig->nh_priv->nh_type;
        nh_priv->rt_flags = nh_orig->nh_priv->rt_flags;
        nh_priv->nh_fibnum = nh_orig->nh_priv->nh_fibnum;
        nh_priv->nh_origin = nh_orig->nh_priv->nh_origin;
}

void
nhop_set_direct_gw(struct nhop_object *nh, struct ifnet *ifp)
{
        nh->nh_flags &= ~NHF_GATEWAY;
        nh->nh_priv->rt_flags &= ~RTF_GATEWAY;
        nh->nh_priv->nh_neigh_family = nh->nh_priv->nh_upper_family;

        fill_sdl_from_ifp(&nh->gwl_sa, ifp);
        memset(&nh->gw_buf[nh->gw_sa.sa_len], 0, sizeof(nh->gw_buf) - nh->gw_sa.sa_len);
}

bool
nhop_check_gateway(int upper_family, int neigh_family)
{
        if (upper_family == neigh_family)
                return (true);
        else if (neigh_family == AF_UNSPEC || neigh_family == AF_LINK)
                return (true);
#if defined(INET) && defined(INET6)
        else if (upper_family == AF_INET && neigh_family == AF_INET6 &&
            rib_can_4o6_nhop())
                return (true);
#endif
        else
                return (false);
}

/*
 * Sets gateway for the nexthop.
 * It can be "normal" gateway with is_gw set or a special form of
 * adding interface route, refering to it by specifying local interface
 * address. In that case is_gw is set to false.
 */
bool
nhop_set_gw(struct nhop_object *nh, const struct sockaddr *gw, bool is_gw)
{
        if (gw->sa_len > sizeof(nh->gw_buf)) {
                FIB_NH_LOG(LOG_DEBUG, nh, "nhop SA size too big: AF %d len %u",
                    gw->sa_family, gw->sa_len);
                return (false);
        }

        if (!nhop_check_gateway(nh->nh_priv->nh_upper_family, gw->sa_family)) {
                FIB_NH_LOG(LOG_DEBUG, nh,
                    "error: invalid dst/gateway family combination (%d, %d)",
                    nh->nh_priv->nh_upper_family, gw->sa_family);
                return (false);
        }

        memcpy(&nh->gw_sa, gw, gw->sa_len);
        memset(&nh->gw_buf[gw->sa_len], 0, sizeof(nh->gw_buf) - gw->sa_len);

        if (is_gw) {
                nh->nh_flags |= NHF_GATEWAY;
                nh->nh_priv->rt_flags |= RTF_GATEWAY;
                nh->nh_priv->nh_neigh_family = gw->sa_family;
        } else {
                nh->nh_flags &= ~NHF_GATEWAY;
                nh->nh_priv->rt_flags &= ~RTF_GATEWAY;
                nh->nh_priv->nh_neigh_family = nh->nh_priv->nh_upper_family;
        }

        return (true);
}

bool
nhop_set_upper_family(struct nhop_object *nh, int family)
{
        if (!nhop_check_gateway(nh->nh_priv->nh_upper_family, family)) {
                FIB_NH_LOG(LOG_DEBUG, nh,
                    "error: invalid upper/neigh family combination (%d, %d)",
                    nh->nh_priv->nh_upper_family, family);
                return (false);
        }

        nh->nh_priv->nh_upper_family = family;
        return (true);
}

void
nhop_set_broadcast(struct nhop_object *nh, bool is_broadcast)
{
        if (is_broadcast) {
                nh->nh_flags |= NHF_BROADCAST;
                nh->nh_priv->rt_flags |= RTF_BROADCAST;
        } else {
                nh->nh_flags &= ~NHF_BROADCAST;
                nh->nh_priv->rt_flags &= ~RTF_BROADCAST;
        }
}

void
nhop_set_blackhole(struct nhop_object *nh, int blackhole_rt_flag)
{
        nh->nh_flags &= ~(NHF_BLACKHOLE | NHF_REJECT);
        nh->nh_priv->rt_flags &= ~(RTF_BLACKHOLE | RTF_REJECT);
        switch (blackhole_rt_flag) {
        case RTF_BLACKHOLE:
                nh->nh_flags |= NHF_BLACKHOLE;
                nh->nh_priv->rt_flags |= RTF_BLACKHOLE;
                break;
        case RTF_REJECT:
                nh->nh_flags |= NHF_REJECT;
                nh->nh_priv->rt_flags |= RTF_REJECT;
                break;
        default:
                /* Not a blackhole nexthop */
                return;
        }

        nh->nh_ifp = V_loif;
        nh->nh_flags &= ~NHF_GATEWAY;
        nh->nh_priv->rt_flags &= ~RTF_GATEWAY;
        nh->nh_priv->nh_neigh_family = nh->nh_priv->nh_upper_family;

        bzero(&nh->gw_sa, sizeof(nh->gw_sa));

        switch (nh->nh_priv->nh_upper_family) {
#ifdef INET
        case AF_INET:
                nh->gw4_sa.sin_family = AF_INET;
                nh->gw4_sa.sin_len = sizeof(struct sockaddr_in);
                nh->gw4_sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
                break;
#endif
#ifdef INET6
        case AF_INET6:
                nh->gw6_sa.sin6_family = AF_INET6;
                nh->gw6_sa.sin6_len = sizeof(struct sockaddr_in6);
                nh->gw6_sa.sin6_addr = in6addr_loopback;
                break;
#endif
        }
}

void
nhop_set_redirect(struct nhop_object *nh, bool is_redirect)
{
        if (is_redirect) {
                nh->nh_priv->rt_flags |= RTF_DYNAMIC;
                nh->nh_flags |= NHF_REDIRECT;
        } else {
                nh->nh_priv->rt_flags &= ~RTF_DYNAMIC;
                nh->nh_flags &= ~NHF_REDIRECT;
        }
}

void
nhop_set_pinned(struct nhop_object *nh, bool is_pinned)
{
        if (is_pinned)
                nh->nh_priv->rt_flags |= RTF_PINNED;
        else
                nh->nh_priv->rt_flags &= ~RTF_PINNED;
}

uint32_t
nhop_get_idx(const struct nhop_object *nh)
{

        return (nh->nh_priv->nh_idx);
}

uint32_t
nhop_get_uidx(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_uidx);
}

void
nhop_set_uidx(struct nhop_object *nh, uint32_t uidx)
{
        nh->nh_priv->nh_uidx = uidx;
}

enum nhop_type
nhop_get_type(const struct nhop_object *nh)
{

        return (nh->nh_priv->nh_type);
}

void
nhop_set_type(struct nhop_object *nh, enum nhop_type nh_type)
{

        nh->nh_priv->nh_type = nh_type;
}

int
nhop_get_rtflags(const struct nhop_object *nh)
{

        return (nh->nh_priv->rt_flags);
}

/*
 * Sets generic rtflags that are not covered by other functions.
 */
void
nhop_set_rtflags(struct nhop_object *nh, int rt_flags)
{
        nh->nh_priv->rt_flags &= ~RT_SET_RTFLAGS_MASK;
        nh->nh_priv->rt_flags |= (rt_flags & RT_SET_RTFLAGS_MASK);
}

/*
 * Sets flags that are specific to the prefix (NHF_HOST or NHF_DEFAULT).
 */
void
nhop_set_pxtype_flag(struct nhop_object *nh, int nh_flag)
{
        if (nh_flag == NHF_HOST) {
                nh->nh_flags |= NHF_HOST;
                nh->nh_flags &= ~NHF_DEFAULT;
                nh->nh_priv->rt_flags |= RTF_HOST;
        } else if (nh_flag == NHF_DEFAULT) {
                nh->nh_flags |= NHF_DEFAULT;
                nh->nh_flags &= ~NHF_HOST;
                nh->nh_priv->rt_flags &= ~RTF_HOST;
        } else {
                nh->nh_flags &= ~(NHF_HOST | NHF_DEFAULT);
                nh->nh_priv->rt_flags &= ~RTF_HOST;
        }
}

/*
 * Sets nhop MTU. Sets RTF_FIXEDMTU if mtu is explicitly
 * specified by userland.
 */
void
nhop_set_mtu(struct nhop_object *nh, uint32_t mtu, bool from_user)
{
        if (from_user) {
                if (mtu != 0)
                        nh->nh_priv->rt_flags |= RTF_FIXEDMTU;
                else
                        nh->nh_priv->rt_flags &= ~RTF_FIXEDMTU;
        }
        nh->nh_mtu = mtu;
}

void
nhop_set_src(struct nhop_object *nh, struct ifaddr *ifa)
{
        nh->nh_ifa = ifa;
}

void
nhop_set_transmit_ifp(struct nhop_object *nh, struct ifnet *ifp)
{
        nh->nh_ifp = ifp;
}


struct vnet *
nhop_get_vnet(const struct nhop_object *nh)
{

        return (nh->nh_priv->nh_vnet);
}

struct nhop_object *
nhop_select_func(struct nhop_object *nh, uint32_t flowid)
{

        return (nhop_select(nh, flowid));
}

/*
 * Returns address family of the traffic uses the nexthop.
 */
int
nhop_get_upper_family(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_upper_family);
}

/*
 * Returns address family of the LLE or gateway that is used
 * to forward the traffic to.
 */
int
nhop_get_neigh_family(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_neigh_family);
}

uint32_t
nhop_get_fibnum(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_fibnum);
}

void
nhop_set_fibnum(struct nhop_object *nh, uint32_t fibnum)
{
        nh->nh_priv->nh_fibnum = fibnum;
}

uint32_t
nhop_get_expire(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_expire);
}

void
nhop_set_expire(struct nhop_object *nh, uint32_t expire)
{
        MPASS(!NH_IS_LINKED(nh));
        nh->nh_priv->nh_expire = expire;
}

struct rib_head *
nhop_get_rh(const struct nhop_object *nh)
{
        uint32_t fibnum = nhop_get_fibnum(nh);
        int family = nhop_get_neigh_family(nh);

        return (rt_tables_get_rnh(fibnum, family));
}

uint8_t
nhop_get_origin(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_origin);
}

void
nhop_set_origin(struct nhop_object *nh, uint8_t origin)
{
        nh->nh_priv->nh_origin = origin;
}

uint32_t
nhop_get_metric(const struct nhop_object *nh)
{
        return (nh->nh_priv->nh_metric);
}

void
nhop_set_metric(struct nhop_object *nh, uint32_t metric)
{
        if (metric != RT_WILDCARD_METRIC)
                nh->nh_priv->nh_metric = metric;
        else
                nh->nh_priv->nh_metric = RT_DEFAULT_METRIC;
}

void
nhops_update_ifmtu(struct rib_head *rh, struct ifnet *ifp, uint32_t mtu)
{
        struct nh_control *ctl;
        struct nhop_priv *nh_priv;
        struct nhop_object *nh;

        ctl = rh->nh_control;

        NHOPS_WLOCK(ctl);
        CHT_SLIST_FOREACH(&ctl->nh_head, nhops, nh_priv) {
                nh = nh_priv->nh;
                if (nh->nh_ifp == ifp) {
                        if ((nh_priv->rt_flags & RTF_FIXEDMTU) == 0 ||
                            nh->nh_mtu > mtu) {
                                /* Update MTU directly */
                                nh->nh_mtu = mtu;
                        }
                }
        } CHT_SLIST_FOREACH_END;
        NHOPS_WUNLOCK(ctl);

}

struct nhop_object *
nhops_iter_start(struct nhop_iter *iter)
{
        if (iter->rh == NULL)
                iter->rh = rt_tables_get_rnh_safe(iter->fibnum, iter->family);
        if (iter->rh != NULL) {
                struct nh_control *ctl = iter->rh->nh_control;

                if (iter->wlock)
                        NHOPS_WLOCK(ctl);
                else
                        NHOPS_RLOCK(ctl);

                iter->_i = 0;
                iter->_next = CHT_FIRST(&ctl->nh_head, iter->_i);

                return (nhops_iter_next(iter));
        } else
                return (NULL);
}

struct nhop_object *
nhops_iter_next(struct nhop_iter *iter)
{
        struct nhop_priv *nh_priv = iter->_next;

        if (nh_priv != NULL) {
                iter->_next = nh_priv->nh_next;
                return (nh_priv->nh);
        }

        struct nh_control *ctl = iter->rh->nh_control;
        while (++iter->_i < ctl->nh_head.hash_size) {
                nh_priv = CHT_FIRST(&ctl->nh_head, iter->_i);
                if (nh_priv != NULL) {
                        iter->_next = nh_priv->nh_next;
                        return (nh_priv->nh);
                }
        }

        return (NULL);
}

void
nhops_iter_stop(struct nhop_iter *iter)
{
        if (iter->rh != NULL) {
                struct nh_control *ctl = iter->rh->nh_control;

                if (iter->wlock)
                        NHOPS_WUNLOCK(ctl);
                else
                        NHOPS_RUNLOCK(ctl);
        }
}

/*
 * Prints nexthop @nh data in the provided @buf.
 * Example: nh#33/inet/em0/192.168.0.1
 */
char *
nhop_print_buf(const struct nhop_object *nh, char *buf, size_t bufsize)
{
#if defined(INET) || defined(INET6)
        char abuf[INET6_ADDRSTRLEN];
#endif
        struct nhop_priv *nh_priv = nh->nh_priv;
        const char *upper_str = rib_print_family(nh->nh_priv->nh_upper_family);

        switch (nh->gw_sa.sa_family) {
#ifdef INET
        case AF_INET:
                inet_ntop(AF_INET, &nh->gw4_sa.sin_addr, abuf, sizeof(abuf));
                snprintf(buf, bufsize, "nh#%d/%s/%s/%s", nh_priv->nh_idx, upper_str,
                    if_name(nh->nh_ifp), abuf);
                break;
#endif
#ifdef INET6
        case AF_INET6:
                inet_ntop(AF_INET6, &nh->gw6_sa.sin6_addr, abuf, sizeof(abuf));
                snprintf(buf, bufsize, "nh#%d/%s/%s/%s", nh_priv->nh_idx, upper_str,
                    if_name(nh->nh_ifp), abuf);
                break;
#endif
        case AF_LINK:
                snprintf(buf, bufsize, "nh#%d/%s/%s/resolve", nh_priv->nh_idx, upper_str,
                    if_name(nh->nh_ifp));
                break;
        default:
                snprintf(buf, bufsize, "nh#%d/%s/%s/????", nh_priv->nh_idx, upper_str,
                    if_name(nh->nh_ifp));
                break;
        }

        return (buf);
}

char *
nhop_print_buf_any(const struct nhop_object *nh, char *buf, size_t bufsize)
{

        if (NH_IS_NHGRP(nh))
                return (nhgrp_print_buf((const struct nhgrp_object *)nh, buf, bufsize));

        return (nhop_print_buf(nh, buf, bufsize));
}

/*
 * Dumps a single entry to sysctl buffer.
 *
 * Layout:
 *  rt_msghdr - generic RTM header to allow users to skip non-understood messages
 *  nhop_external - nexhop description structure (with length)
 *  nhop_addrs - structure encapsulating GW/SRC sockaddrs
 */
static int
dump_nhop_entry(struct rib_head *rh, struct nhop_object *nh, struct sysctl_req *w)
{
        struct {
                struct rt_msghdr        rtm;
                struct nhop_external    nhe;
                struct nhop_addrs       na;
        } arpc;
        struct nhop_external *pnhe;
        struct sockaddr *gw_sa, *src_sa;
        struct sockaddr_storage ss;
        size_t addrs_len;
        int error;

        memset(&arpc, 0, sizeof(arpc));

        arpc.rtm.rtm_msglen = sizeof(arpc);
        arpc.rtm.rtm_version = RTM_VERSION;
        arpc.rtm.rtm_type = RTM_GET;
        //arpc.rtm.rtm_flags = RTF_UP;
        arpc.rtm.rtm_flags = nh->nh_priv->rt_flags;

        /* nhop_external */
        pnhe = &arpc.nhe;
        pnhe->nh_len = sizeof(struct nhop_external);
        pnhe->nh_idx = nh->nh_priv->nh_idx;
        pnhe->nh_fib = rh->rib_fibnum;
        pnhe->ifindex = nh->nh_ifp->if_index;
        pnhe->aifindex = nh->nh_aifp->if_index;
        pnhe->nh_family = nh->nh_priv->nh_upper_family;
        pnhe->nh_type = nh->nh_priv->nh_type;
        pnhe->nh_mtu = nh->nh_mtu;
        pnhe->nh_flags = nh->nh_flags;

        memcpy(pnhe->nh_prepend, nh->nh_prepend, sizeof(nh->nh_prepend));
        pnhe->prepend_len = nh->nh_prepend_len;
        pnhe->nh_refcount = nh->nh_priv->nh_refcnt;
        pnhe->nh_pksent = counter_u64_fetch(nh->nh_pksent);

        /* sockaddr container */
        addrs_len = sizeof(struct nhop_addrs);
        arpc.na.gw_sa_off = addrs_len;
        gw_sa = (struct sockaddr *)&nh->gw4_sa;
        addrs_len += gw_sa->sa_len;

        src_sa = nh->nh_ifa->ifa_addr;
        if (src_sa->sa_family == AF_LINK) {
                /* Shorten structure */
                memset(&ss, 0, sizeof(struct sockaddr_storage));
                fill_sdl_from_ifp((struct sockaddr_dl_short *)&ss,
                    nh->nh_ifa->ifa_ifp);
                src_sa = (struct sockaddr *)&ss;
        }
        arpc.na.src_sa_off = addrs_len;
        addrs_len += src_sa->sa_len;

        /* Write total container length */
        arpc.na.na_len = addrs_len;

        arpc.rtm.rtm_msglen += arpc.na.na_len - sizeof(struct nhop_addrs);

        error = SYSCTL_OUT(w, &arpc, sizeof(arpc));
        if (error == 0)
                error = SYSCTL_OUT(w, gw_sa, gw_sa->sa_len);
        if (error == 0)
                error = SYSCTL_OUT(w, src_sa, src_sa->sa_len);

        return (error);
}

uint32_t
nhops_get_count(struct rib_head *rh)
{
        struct nh_control *ctl;
        uint32_t count;

        ctl = rh->nh_control;

        NHOPS_RLOCK(ctl);
        count = ctl->nh_head.items_count;
        NHOPS_RUNLOCK(ctl);

        return (count);
}

int
nhops_dump_sysctl(struct rib_head *rh, struct sysctl_req *w)
{
        struct nh_control *ctl;
        struct nhop_priv *nh_priv;
        int error;

        ctl = rh->nh_control;

        NHOPS_RLOCK(ctl);
        FIB_RH_LOG(LOG_DEBUG, rh, "dump %u items", ctl->nh_head.items_count);
        CHT_SLIST_FOREACH(&ctl->nh_head, nhops, nh_priv) {
                error = dump_nhop_entry(rh, nh_priv->nh, w);
                if (error != 0) {
                        NHOPS_RUNLOCK(ctl);
                        return (error);
                }
        } CHT_SLIST_FOREACH_END;
        NHOPS_RUNLOCK(ctl);

        return (0);
}

static void
nhops_ifnet_state_changed(struct ifnet *ifp, bool status)
{
        struct nhop_object *nh;
        struct nhop_iter iter = { .fibnum = ifp->if_fib, .wlock = true };
        bool nhops_changed;

        for (iter.family = 1; iter.family <= AF_MAX; iter.family++) {
                /*
                 * By tracking nhop changes, we avoid redundant nhgrp
                 * recompilation triggered by multiple events.
                 */
                nhops_changed = false;
                iter.rh = rt_tables_get_rnh_safe(iter.fibnum, iter.family);
                for (nh = nhops_iter_start(&iter); nh != NULL;
                    nh = nhops_iter_next(&iter)) {
                        if (nh->nh_ifp != ifp)
                                continue;

                        if (status && !NH_IS_VALID(nh)) {
                                nh->nh_flags &= ~NHF_INVALID;
                                nhops_changed = true;
                        } else if (!status && NH_IS_VALID(nh)) {
                                nh->nh_flags |= NHF_INVALID;
                                nhops_changed = true;
                        }
                }
                if (iter.rh != NULL && nhops_changed)
                        nhgrp_recompile(iter.rh);
                nhops_iter_stop(&iter);
        }
}

static void
nhops_ifnet_event(void *arg __unused, struct ifnet *ifp, int state)
{

        if ((ifp->if_flags & IFF_DYING) != 0 ||
            (state != IFNET_EVENT_UP && state != IFNET_EVENT_DOWN))
                return;

        nhops_ifnet_state_changed(ifp, state == IFNET_EVENT_UP);
}

static void
nhops_ifnet_link_event(void *arg __unused, struct ifnet *ifp, int state)
{
#ifdef VIMAGE
        /*
         * rib_head will be calculated from V_tables in rt_tables_get_rnh
         * and the VNET is destroyed.
         */
        if (VNET_IS_SHUTTING_DOWN(ifp->if_vnet))
                return;
#endif

        if ((ifp->if_flags & IFF_DYING) != 0 ||
            (state != LINK_STATE_UP && state != LINK_STATE_DOWN))
                return;

        nhops_ifnet_state_changed(ifp, state == LINK_STATE_UP);
}