Merge pull request #5276 from donaldsharp/pim_double

[mirror_frr.git] / zebra / zebra_rib.c

/* Routing Information Base.
 * Copyright (C) 1997, 98, 99, 2001 Kunihiro Ishiguro
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra 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, or (at your option) any
 * later version.
 *
 * GNU Zebra is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>

#include "command.h"
#include "if.h"
#include "linklist.h"
#include "log.h"
#include "memory.h"
#include "mpls.h"
#include "nexthop.h"
#include "prefix.h"
#include "prefix.h"
#include "routemap.h"
#include "sockunion.h"
#include "srcdest_table.h"
#include "table.h"
#include "thread.h"
#include "vrf.h"
#include "workqueue.h"
#include "nexthop_group_private.h"
#include "frr_pthread.h"

#include "zebra/zebra_router.h"
#include "zebra/connected.h"
#include "zebra/debug.h"
#include "zebra/interface.h"
#include "zebra/redistribute.h"
#include "zebra/rib.h"
#include "zebra/rt.h"
#include "zebra/zapi_msg.h"
#include "zebra/zebra_errors.h"
#include "zebra/zebra_memory.h"
#include "zebra/zebra_ns.h"
#include "zebra/zebra_rnh.h"
#include "zebra/zebra_routemap.h"
#include "zebra/zebra_vrf.h"
#include "zebra/zebra_vxlan.h"
#include "zebra/zapi_msg.h"
#include "zebra/zebra_dplane.h"

DEFINE_MTYPE_STATIC(ZEBRA, RIB_UPDATE_CTX, "Rib update context object");

/*
 * Event, list, and mutex for delivery of dataplane results
 */
static pthread_mutex_t dplane_mutex;
static struct thread *t_dplane;
static struct dplane_ctx_q rib_dplane_q;

DEFINE_HOOK(rib_update, (struct route_node * rn, const char *reason),
            (rn, reason))

/* Should we allow non Quagga processes to delete our routes */
extern int allow_delete;

/* Each route type's string and default distance value. */
static const struct {
        int key;
        uint8_t distance;
        uint8_t meta_q_map;
} route_info[ZEBRA_ROUTE_MAX] = {
        [ZEBRA_ROUTE_NHG] = {ZEBRA_ROUTE_NHG, 255 /* Uneeded for nhg's */, 0},
        [ZEBRA_ROUTE_SYSTEM] = {ZEBRA_ROUTE_SYSTEM, 0, 5},
        [ZEBRA_ROUTE_KERNEL] = {ZEBRA_ROUTE_KERNEL, 0, 1},
        [ZEBRA_ROUTE_CONNECT] = {ZEBRA_ROUTE_CONNECT, 0, 1},
        [ZEBRA_ROUTE_STATIC] = {ZEBRA_ROUTE_STATIC, 1, 2},
        [ZEBRA_ROUTE_RIP] = {ZEBRA_ROUTE_RIP, 120, 3},
        [ZEBRA_ROUTE_RIPNG] = {ZEBRA_ROUTE_RIPNG, 120, 3},
        [ZEBRA_ROUTE_OSPF] = {ZEBRA_ROUTE_OSPF, 110, 3},
        [ZEBRA_ROUTE_OSPF6] = {ZEBRA_ROUTE_OSPF6, 110, 3},
        [ZEBRA_ROUTE_ISIS] = {ZEBRA_ROUTE_ISIS, 115, 3},
        [ZEBRA_ROUTE_BGP] = {ZEBRA_ROUTE_BGP, 20 /* IBGP is 200. */, 4},
        [ZEBRA_ROUTE_PIM] = {ZEBRA_ROUTE_PIM, 255, 5},
        [ZEBRA_ROUTE_EIGRP] = {ZEBRA_ROUTE_EIGRP, 90, 3},
        [ZEBRA_ROUTE_NHRP] = {ZEBRA_ROUTE_NHRP, 10, 3},
        [ZEBRA_ROUTE_HSLS] = {ZEBRA_ROUTE_HSLS, 255, 5},
        [ZEBRA_ROUTE_OLSR] = {ZEBRA_ROUTE_OLSR, 255, 5},
        [ZEBRA_ROUTE_TABLE] = {ZEBRA_ROUTE_TABLE, 150, 2},
        [ZEBRA_ROUTE_LDP] = {ZEBRA_ROUTE_LDP, 150, 5},
        [ZEBRA_ROUTE_VNC] = {ZEBRA_ROUTE_VNC, 20, 4},
        [ZEBRA_ROUTE_VNC_DIRECT] = {ZEBRA_ROUTE_VNC_DIRECT, 20, 4},
        [ZEBRA_ROUTE_VNC_DIRECT_RH] = {ZEBRA_ROUTE_VNC_DIRECT_RH, 20, 4},
        [ZEBRA_ROUTE_BGP_DIRECT] = {ZEBRA_ROUTE_BGP_DIRECT, 20, 4},
        [ZEBRA_ROUTE_BGP_DIRECT_EXT] = {ZEBRA_ROUTE_BGP_DIRECT_EXT, 20, 4},
        [ZEBRA_ROUTE_BABEL] = {ZEBRA_ROUTE_BABEL, 100, 3},
        [ZEBRA_ROUTE_SHARP] = {ZEBRA_ROUTE_SHARP, 150, 5},
        [ZEBRA_ROUTE_PBR] = {ZEBRA_ROUTE_PBR, 200, 5},
        [ZEBRA_ROUTE_BFD] = {ZEBRA_ROUTE_BFD, 255, 5},
        [ZEBRA_ROUTE_OPENFABRIC] = {ZEBRA_ROUTE_OPENFABRIC, 115, 3},
        [ZEBRA_ROUTE_VRRP] = {ZEBRA_ROUTE_VRRP, 255, 5}
        /* Any new route type added to zebra, should be mirrored here */

        /* no entry/default: 150 */
};

static void __attribute__((format(printf, 5, 6)))
_rnode_zlog(const char *_func, vrf_id_t vrf_id, struct route_node *rn,
            int priority, const char *msgfmt, ...)
{
        char buf[SRCDEST2STR_BUFFER + sizeof(" (MRIB)")];
        char msgbuf[512];
        va_list ap;

        va_start(ap, msgfmt);
        vsnprintf(msgbuf, sizeof(msgbuf), msgfmt, ap);
        va_end(ap);

        if (rn) {
                rib_table_info_t *info = srcdest_rnode_table_info(rn);
                srcdest_rnode2str(rn, buf, sizeof(buf));

                if (info->safi == SAFI_MULTICAST)
                        strlcat(buf, " (MRIB)", sizeof(buf));
        } else {
                snprintf(buf, sizeof(buf), "{(route_node *) NULL}");
        }

        zlog(priority, "%s: %d:%s: %s", _func, vrf_id, buf, msgbuf);
}

#define rnode_debug(node, vrf_id, ...)                                         \
        _rnode_zlog(__func__, vrf_id, node, LOG_DEBUG, __VA_ARGS__)
#define rnode_info(node, ...)                                                  \
        _rnode_zlog(__func__, vrf_id, node, LOG_INFO, __VA_ARGS__)

uint8_t route_distance(int type)
{
        uint8_t distance;

        if ((unsigned)type >= array_size(route_info))
                distance = 150;
        else
                distance = route_info[type].distance;

        return distance;
}

int is_zebra_valid_kernel_table(uint32_t table_id)
{
#ifdef linux
        if ((table_id == RT_TABLE_UNSPEC) || (table_id == RT_TABLE_LOCAL)
            || (table_id == RT_TABLE_COMPAT))
                return 0;
#endif

        return 1;
}

int is_zebra_main_routing_table(uint32_t table_id)
{
        if (table_id == RT_TABLE_MAIN)
                return 1;
        return 0;
}

int zebra_check_addr(const struct prefix *p)
{
        if (p->family == AF_INET) {
                uint32_t addr;

                addr = p->u.prefix4.s_addr;
                addr = ntohl(addr);

                if (IPV4_NET127(addr) || IN_CLASSD(addr)
                    || IPV4_LINKLOCAL(addr))
                        return 0;
        }
        if (p->family == AF_INET6) {
                if (IN6_IS_ADDR_LOOPBACK(&p->u.prefix6))
                        return 0;
                if (IN6_IS_ADDR_LINKLOCAL(&p->u.prefix6))
                        return 0;
        }
        return 1;
}

/* Add nexthop to the end of a rib node's nexthop list */
void route_entry_nexthop_add(struct route_entry *re, struct nexthop *nexthop)
{
        _nexthop_group_add_sorted(re->ng, nexthop);
}


/**
 * copy_nexthop - copy a nexthop to the rib structure.
 */
void route_entry_copy_nexthops(struct route_entry *re, struct nexthop *nh)
{
        assert(!re->ng->nexthop);
        copy_nexthops(&re->ng->nexthop, nh, NULL);
}

/* Delete specified nexthop from the list. */
void route_entry_nexthop_delete(struct route_entry *re, struct nexthop *nexthop)
{
        if (nexthop->next)
                nexthop->next->prev = nexthop->prev;
        if (nexthop->prev)
                nexthop->prev->next = nexthop->next;
        else
                re->ng->nexthop = nexthop->next;
}


struct nexthop *route_entry_nexthop_ifindex_add(struct route_entry *re,
                                                ifindex_t ifindex,
                                                vrf_id_t nh_vrf_id)
{
        struct nexthop *nexthop;

        nexthop = nexthop_new();
        nexthop->type = NEXTHOP_TYPE_IFINDEX;
        nexthop->ifindex = ifindex;
        nexthop->vrf_id = nh_vrf_id;

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct nexthop *route_entry_nexthop_ipv4_add(struct route_entry *re,
                                             struct in_addr *ipv4,
                                             struct in_addr *src,
                                             vrf_id_t nh_vrf_id)
{
        struct nexthop *nexthop;

        nexthop = nexthop_new();
        nexthop->type = NEXTHOP_TYPE_IPV4;
        nexthop->vrf_id = nh_vrf_id;
        nexthop->gate.ipv4 = *ipv4;
        if (src)
                nexthop->src.ipv4 = *src;

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct nexthop *route_entry_nexthop_ipv4_ifindex_add(struct route_entry *re,
                                                     struct in_addr *ipv4,
                                                     struct in_addr *src,
                                                     ifindex_t ifindex,
                                                     vrf_id_t nh_vrf_id)
{
        struct nexthop *nexthop;
        struct interface *ifp;

        nexthop = nexthop_new();
        nexthop->vrf_id = nh_vrf_id;
        nexthop->type = NEXTHOP_TYPE_IPV4_IFINDEX;
        nexthop->gate.ipv4 = *ipv4;
        if (src)
                nexthop->src.ipv4 = *src;
        nexthop->ifindex = ifindex;
        ifp = if_lookup_by_index(nexthop->ifindex, nh_vrf_id);
        /*Pending: need to think if null ifp here is ok during bootup?
          There was a crash because ifp here was coming to be NULL */
        if (ifp)
                if (connected_is_unnumbered(ifp))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK);

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct nexthop *route_entry_nexthop_ipv6_add(struct route_entry *re,
                                             struct in6_addr *ipv6,
                                             vrf_id_t nh_vrf_id)
{
        struct nexthop *nexthop;

        nexthop = nexthop_new();
        nexthop->vrf_id = nh_vrf_id;
        nexthop->type = NEXTHOP_TYPE_IPV6;
        nexthop->gate.ipv6 = *ipv6;

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct nexthop *route_entry_nexthop_ipv6_ifindex_add(struct route_entry *re,
                                                     struct in6_addr *ipv6,
                                                     ifindex_t ifindex,
                                                     vrf_id_t nh_vrf_id)
{
        struct nexthop *nexthop;

        nexthop = nexthop_new();
        nexthop->vrf_id = nh_vrf_id;
        nexthop->type = NEXTHOP_TYPE_IPV6_IFINDEX;
        nexthop->gate.ipv6 = *ipv6;
        nexthop->ifindex = ifindex;

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct nexthop *route_entry_nexthop_blackhole_add(struct route_entry *re,
                                                  enum blackhole_type bh_type)
{
        struct nexthop *nexthop;

        nexthop = nexthop_new();
        nexthop->vrf_id = VRF_DEFAULT;
        nexthop->type = NEXTHOP_TYPE_BLACKHOLE;
        nexthop->bh_type = bh_type;

        route_entry_nexthop_add(re, nexthop);

        return nexthop;
}

struct route_entry *rib_match(afi_t afi, safi_t safi, vrf_id_t vrf_id,
                              union g_addr *addr, struct route_node **rn_out)
{
        struct prefix p;
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *match = NULL;

        /* Lookup table.  */
        table = zebra_vrf_table(afi, safi, vrf_id);
        if (!table)
                return 0;

        memset(&p, 0, sizeof(struct prefix));
        p.family = afi;
        if (afi == AFI_IP) {
                p.u.prefix4 = addr->ipv4;
                p.prefixlen = IPV4_MAX_PREFIXLEN;
        } else {
                p.u.prefix6 = addr->ipv6;
                p.prefixlen = IPV6_MAX_PREFIXLEN;
        }

        rn = route_node_match(table, (struct prefix *)&p);

        while (rn) {
                rib_dest_t *dest;

                route_unlock_node(rn);

                dest = rib_dest_from_rnode(rn);
                if (dest && dest->selected_fib
                    && !CHECK_FLAG(dest->selected_fib->status,
                                   ROUTE_ENTRY_REMOVED))
                        match = dest->selected_fib;

                /* If there is no selected route or matched route is EGP, go up
                   tree. */
                if (!match) {
                        do {
                                rn = rn->parent;
                        } while (rn && rn->info == NULL);
                        if (rn)
                                route_lock_node(rn);
                } else {
                        if (match->type != ZEBRA_ROUTE_CONNECT) {
                                if (!CHECK_FLAG(match->status,
                                                ROUTE_ENTRY_INSTALLED))
                                        return NULL;
                        }

                        if (rn_out)
                                *rn_out = rn;
                        return match;
                }
        }
        return NULL;
}

struct route_entry *rib_match_ipv4_multicast(vrf_id_t vrf_id,
                                             struct in_addr addr,
                                             struct route_node **rn_out)
{
        struct route_entry *re = NULL, *mre = NULL, *ure = NULL;
        struct route_node *m_rn = NULL, *u_rn = NULL;
        union g_addr gaddr = {.ipv4 = addr};

        switch (zrouter.ipv4_multicast_mode) {
        case MCAST_MRIB_ONLY:
                return rib_match(AFI_IP, SAFI_MULTICAST, vrf_id, &gaddr,
                                 rn_out);
        case MCAST_URIB_ONLY:
                return rib_match(AFI_IP, SAFI_UNICAST, vrf_id, &gaddr, rn_out);
        case MCAST_NO_CONFIG:
        case MCAST_MIX_MRIB_FIRST:
                re = mre = rib_match(AFI_IP, SAFI_MULTICAST, vrf_id, &gaddr,
                                     &m_rn);
                if (!mre)
                        re = ure = rib_match(AFI_IP, SAFI_UNICAST, vrf_id,
                                             &gaddr, &u_rn);
                break;
        case MCAST_MIX_DISTANCE:
                mre = rib_match(AFI_IP, SAFI_MULTICAST, vrf_id, &gaddr, &m_rn);
                ure = rib_match(AFI_IP, SAFI_UNICAST, vrf_id, &gaddr, &u_rn);
                if (mre && ure)
                        re = ure->distance < mre->distance ? ure : mre;
                else if (mre)
                        re = mre;
                else if (ure)
                        re = ure;
                break;
        case MCAST_MIX_PFXLEN:
                mre = rib_match(AFI_IP, SAFI_MULTICAST, vrf_id, &gaddr, &m_rn);
                ure = rib_match(AFI_IP, SAFI_UNICAST, vrf_id, &gaddr, &u_rn);
                if (mre && ure)
                        re = u_rn->p.prefixlen > m_rn->p.prefixlen ? ure : mre;
                else if (mre)
                        re = mre;
                else if (ure)
                        re = ure;
                break;
        }

        if (rn_out)
                *rn_out = (re == mre) ? m_rn : u_rn;

        if (IS_ZEBRA_DEBUG_RIB) {
                char buf[BUFSIZ];
                inet_ntop(AF_INET, &addr, buf, BUFSIZ);

                zlog_debug("%s: %s: vrf: %u found %s, using %s",
                           __func__, buf, vrf_id,
                           mre ? (ure ? "MRIB+URIB" : "MRIB")
                               : ure ? "URIB" : "nothing",
                           re == ure ? "URIB" : re == mre ? "MRIB" : "none");
        }
        return re;
}

struct route_entry *rib_lookup_ipv4(struct prefix_ipv4 *p, vrf_id_t vrf_id)
{
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *match = NULL;
        rib_dest_t *dest;

        /* Lookup table.  */
        table = zebra_vrf_table(AFI_IP, SAFI_UNICAST, vrf_id);
        if (!table)
                return 0;

        rn = route_node_lookup(table, (struct prefix *)p);

        /* No route for this prefix. */
        if (!rn)
                return NULL;

        /* Unlock node. */
        route_unlock_node(rn);
        dest = rib_dest_from_rnode(rn);

        if (dest && dest->selected_fib
            && !CHECK_FLAG(dest->selected_fib->status, ROUTE_ENTRY_REMOVED))
                match = dest->selected_fib;

        if (!match)
                return NULL;

        if (match->type == ZEBRA_ROUTE_CONNECT)
                return match;

        if (CHECK_FLAG(match->status, ROUTE_ENTRY_INSTALLED))
                return match;

        return NULL;
}

/*
 * Is this RIB labeled-unicast? It must be of type BGP and all paths
 * (nexthops) must have a label.
 */
int zebra_rib_labeled_unicast(struct route_entry *re)
{
        struct nexthop *nexthop = NULL;

        if (re->type != ZEBRA_ROUTE_BGP)
                return 0;

        for (ALL_NEXTHOPS_PTR(re->ng, nexthop))
                if (!nexthop->nh_label || !nexthop->nh_label->num_labels)
                        return 0;

        return 1;
}

/* Update flag indicates whether this is a "replace" or not. Currently, this
 * is only used for IPv4.
 */
void rib_install_kernel(struct route_node *rn, struct route_entry *re,
                        struct route_entry *old)
{
        struct nexthop *nexthop;
        rib_table_info_t *info = srcdest_rnode_table_info(rn);
        struct zebra_vrf *zvrf = vrf_info_lookup(re->vrf_id);
        const struct prefix *p, *src_p;
        enum zebra_dplane_result ret;

        rib_dest_t *dest = rib_dest_from_rnode(rn);

        srcdest_rnode_prefixes(rn, &p, &src_p);

        if (info->safi != SAFI_UNICAST) {
                for (ALL_NEXTHOPS_PTR(re->ng, nexthop))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                return;
        }


        /*
         * Install the resolved nexthop object first.
         */
        zebra_nhg_install_kernel(zebra_nhg_lookup_id(re->nhe_id));

        /*
         * If this is a replace to a new RE let the originator of the RE
         * know that they've lost
         */
        if (old && (old != re) && (old->type != re->type))
                zsend_route_notify_owner(old, p, ZAPI_ROUTE_BETTER_ADMIN_WON);

        /* Update fib selection */
        dest->selected_fib = re;

        /*
         * Make sure we update the FPM any time we send new information to
         * the kernel.
         */
        hook_call(rib_update, rn, "installing in kernel");

        /* Send add or update */
        if (old)
                ret = dplane_route_update(rn, re, old);
        else
                ret = dplane_route_add(rn, re);

        switch (ret) {
        case ZEBRA_DPLANE_REQUEST_QUEUED:
                SET_FLAG(re->status, ROUTE_ENTRY_QUEUED);

                if (old) {
                        SET_FLAG(old->status, ROUTE_ENTRY_QUEUED);

                        /* Free old FIB nexthop group */
                        if (old->fib_ng.nexthop) {
                                nexthops_free(old->fib_ng.nexthop);
                                old->fib_ng.nexthop = NULL;
                        }
                }

                if (zvrf)
                        zvrf->installs_queued++;
                break;
        case ZEBRA_DPLANE_REQUEST_FAILURE:
        {
                char str[SRCDEST2STR_BUFFER];

                srcdest_rnode2str(rn, str, sizeof(str));
                flog_err(EC_ZEBRA_DP_INSTALL_FAIL,
                         "%u:%s: Failed to enqueue dataplane install",
                         re->vrf_id, str);
                break;
        }
        case ZEBRA_DPLANE_REQUEST_SUCCESS:
                if (zvrf)
                        zvrf->installs++;
                break;
        }

        return;
}

/* Uninstall the route from kernel. */
void rib_uninstall_kernel(struct route_node *rn, struct route_entry *re)
{
        struct nexthop *nexthop;
        rib_table_info_t *info = srcdest_rnode_table_info(rn);
        struct zebra_vrf *zvrf = vrf_info_lookup(re->vrf_id);

        if (info->safi != SAFI_UNICAST) {
                UNSET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                for (ALL_NEXTHOPS_PTR(re->ng, nexthop))
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                return;
        }

        /*
         * Make sure we update the FPM any time we send new information to
         * the dataplane.
         */
        hook_call(rib_update, rn, "uninstalling from kernel");

        switch (dplane_route_delete(rn, re)) {
        case ZEBRA_DPLANE_REQUEST_QUEUED:
                if (zvrf)
                        zvrf->removals_queued++;
                break;
        case ZEBRA_DPLANE_REQUEST_FAILURE:
        {
                char str[SRCDEST2STR_BUFFER];

                srcdest_rnode2str(rn, str, sizeof(str));
                flog_err(EC_ZEBRA_DP_INSTALL_FAIL,
                         "%u:%s: Failed to enqueue dataplane uninstall",
                         re->vrf_id, str);
                break;
        }
        case ZEBRA_DPLANE_REQUEST_SUCCESS:
                if (zvrf)
                        zvrf->removals++;
                break;
        }

        return;
}

/* Uninstall the route from kernel. */
static void rib_uninstall(struct route_node *rn, struct route_entry *re)
{
        rib_table_info_t *info = srcdest_rnode_table_info(rn);
        rib_dest_t *dest = rib_dest_from_rnode(rn);
        struct nexthop *nexthop;

        if (dest && dest->selected_fib == re) {
                if (info->safi == SAFI_UNICAST)
                        hook_call(rib_update, rn, "rib_uninstall");

                /* If labeled-unicast route, uninstall transit LSP. */
                if (zebra_rib_labeled_unicast(re))
                        zebra_mpls_lsp_uninstall(info->zvrf, rn, re);

                rib_uninstall_kernel(rn, re);

                dest->selected_fib = NULL;

                /* Free FIB nexthop group, if present */
                if (re->fib_ng.nexthop) {
                        nexthops_free(re->fib_ng.nexthop);
                        re->fib_ng.nexthop = NULL;
                }

                for (ALL_NEXTHOPS_PTR(re->ng, nexthop))
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
        }

        if (CHECK_FLAG(re->flags, ZEBRA_FLAG_SELECTED)) {
                const struct prefix *p, *src_p;

                srcdest_rnode_prefixes(rn, &p, &src_p);

                redistribute_delete(p, src_p, re, NULL);
                UNSET_FLAG(re->flags, ZEBRA_FLAG_SELECTED);
        }
}

/*
 * rib_can_delete_dest
 *
 * Returns true if the given dest can be deleted from the table.
 */
static int rib_can_delete_dest(rib_dest_t *dest)
{
        if (re_list_first(&dest->routes)) {
                return 0;
        }

        /*
         * Unresolved rnh's are stored on the default route's list
         *
         * dest->rnode can also be the source prefix node in an
         * ipv6 sourcedest table.  Fortunately the prefix of a
         * source prefix node can never be the default prefix.
         */
        if (is_default_prefix(&dest->rnode->p))
                return 0;

        /*
         * Don't delete the dest if we have to update the FPM about this
         * prefix.
         */
        if (CHECK_FLAG(dest->flags, RIB_DEST_UPDATE_FPM)
            || CHECK_FLAG(dest->flags, RIB_DEST_SENT_TO_FPM))
                return 0;

        return 1;
}

void zebra_rib_evaluate_rn_nexthops(struct route_node *rn, uint32_t seq)
{
        rib_dest_t *dest = rib_dest_from_rnode(rn);
        struct rnh *rnh;

        /*
         * We are storing the rnh's associated withb
         * the tracked nexthop as a list of the rn's.
         * Unresolved rnh's are placed at the top
         * of the tree list.( 0.0.0.0/0 for v4 and 0::0/0 for v6 )
         * As such for each rn we need to walk up the tree
         * and see if any rnh's need to see if they
         * would match a more specific route
         */
        while (rn) {
                if (IS_ZEBRA_DEBUG_NHT_DETAILED) {
                        char buf[PREFIX_STRLEN];

                        zlog_debug("%s: %s Being examined for Nexthop Tracking Count: %zd",
                                   __PRETTY_FUNCTION__,
                                   srcdest_rnode2str(rn, buf, sizeof(buf)),
                                   dest ? rnh_list_count(&dest->nht) : 0);
                }
                if (!dest) {
                        rn = rn->parent;
                        if (rn)
                                dest = rib_dest_from_rnode(rn);
                        continue;
                }
                /*
                 * If we have any rnh's stored in the nht list
                 * then we know that this route node was used for
                 * nht resolution and as such we need to call the
                 * nexthop tracking evaluation code
                 */
                frr_each_safe(rnh_list, &dest->nht, rnh) {
                        struct zebra_vrf *zvrf =
                                zebra_vrf_lookup_by_id(rnh->vrf_id);
                        struct prefix *p = &rnh->node->p;

                        if (IS_ZEBRA_DEBUG_NHT_DETAILED) {
                                char buf1[PREFIX_STRLEN];
                                char buf2[PREFIX_STRLEN];

                                zlog_debug("%u:%s has Nexthop(%s) Type: %s depending on it, evaluating %u:%u",
                                           zvrf->vrf->vrf_id,
                                           srcdest_rnode2str(rn, buf1,
                                                      sizeof(buf1)),
                                           prefix2str(p, buf2, sizeof(buf2)),
                                           rnh_type2str(rnh->type),
                                           seq, rnh->seqno);
                        }

                        /*
                         * If we have evaluated this node on this pass
                         * already, due to following the tree up
                         * then we know that we can move onto the next
                         * rnh to process.
                         *
                         * Additionally we call zebra_evaluate_rnh
                         * when we gc the dest.  In this case we know
                         * that there must be no other re's where
                         * we were originally as such we know that
                         * that sequence number is ok to respect.
                         */
                        if (rnh->seqno == seq) {
                                if (IS_ZEBRA_DEBUG_NHT_DETAILED)
                                        zlog_debug(
                                                "\tNode processed and moved already");
                                continue;
                        }

                        rnh->seqno = seq;
                        zebra_evaluate_rnh(zvrf, family2afi(p->family), 0,
                                           rnh->type, p);
                }

                rn = rn->parent;
                if (rn)
                        dest = rib_dest_from_rnode(rn);
        }
}

/*
 * rib_gc_dest
 *
 * Garbage collect the rib dest corresponding to the given route node
 * if appropriate.
 *
 * Returns true if the dest was deleted, false otherwise.
 */
int rib_gc_dest(struct route_node *rn)
{
        rib_dest_t *dest;

        dest = rib_dest_from_rnode(rn);
        if (!dest)
                return 0;

        if (!rib_can_delete_dest(dest))
                return 0;

        if (IS_ZEBRA_DEBUG_RIB) {
                struct zebra_vrf *zvrf;

                zvrf = rib_dest_vrf(dest);
                rnode_debug(rn, zvrf_id(zvrf), "removing dest from table");
        }

        zebra_rib_evaluate_rn_nexthops(rn, zebra_router_get_next_sequence());

        dest->rnode = NULL;
        rnh_list_fini(&dest->nht);
        XFREE(MTYPE_RIB_DEST, dest);
        rn->info = NULL;

        /*
         * Release the one reference that we keep on the route node.
         */
        route_unlock_node(rn);
        return 1;
}

static void rib_process_add_fib(struct zebra_vrf *zvrf, struct route_node *rn,
                                struct route_entry *new)
{
        hook_call(rib_update, rn, "new route selected");

        /* Update real nexthop. This may actually determine if nexthop is active
         * or not. */
        if (!nexthop_group_active_nexthop_num(new->ng)) {
                UNSET_FLAG(new->status, ROUTE_ENTRY_CHANGED);
                return;
        }

        if (IS_ZEBRA_DEBUG_RIB) {
                char buf[SRCDEST2STR_BUFFER];
                srcdest_rnode2str(rn, buf, sizeof(buf));
                zlog_debug("%u:%s: Adding route rn %p, re %p (%s)",
                           zvrf_id(zvrf), buf, rn, new,
                           zebra_route_string(new->type));
        }

        /* If labeled-unicast route, install transit LSP. */
        if (zebra_rib_labeled_unicast(new))
                zebra_mpls_lsp_install(zvrf, rn, new);

        rib_install_kernel(rn, new, NULL);

        UNSET_FLAG(new->status, ROUTE_ENTRY_CHANGED);
}

static void rib_process_del_fib(struct zebra_vrf *zvrf, struct route_node *rn,
                                struct route_entry *old)
{
        hook_call(rib_update, rn, "removing existing route");

        /* Uninstall from kernel. */
        if (IS_ZEBRA_DEBUG_RIB) {
                char buf[SRCDEST2STR_BUFFER];
                srcdest_rnode2str(rn, buf, sizeof(buf));
                zlog_debug("%u:%s: Deleting route rn %p, re %p (%s)",
                           zvrf_id(zvrf), buf, rn, old,
                           zebra_route_string(old->type));
        }

        /* If labeled-unicast route, uninstall transit LSP. */
        if (zebra_rib_labeled_unicast(old))
                zebra_mpls_lsp_uninstall(zvrf, rn, old);

        rib_uninstall_kernel(rn, old);

        /* Update nexthop for route, reset changed flag. */
        /* Note: this code also handles the Linux case when an interface goes
         * down, causing the kernel to delete routes without sending DELROUTE
         * notifications
         */
        if (RIB_KERNEL_ROUTE(old))
                SET_FLAG(old->status, ROUTE_ENTRY_REMOVED);
        else
                UNSET_FLAG(old->status, ROUTE_ENTRY_CHANGED);
}

static void rib_process_update_fib(struct zebra_vrf *zvrf,
                                   struct route_node *rn,
                                   struct route_entry *old,
                                   struct route_entry *new)
{
        int nh_active = 0;

        /*
         * We have to install or update if a new route has been selected or
         * something has changed.
         */
        if (new != old || CHECK_FLAG(new->status, ROUTE_ENTRY_CHANGED)) {
                hook_call(rib_update, rn, "updating existing route");

                /* Update the nexthop; we could determine here that nexthop is
                 * inactive. */
                if (nexthop_group_active_nexthop_num(new->ng))
                        nh_active = 1;

                /* If nexthop is active, install the selected route, if
                 * appropriate. If
                 * the install succeeds, cleanup flags for prior route, if
                 * different from
                 * newly selected.
                 */
                if (nh_active) {
                        if (IS_ZEBRA_DEBUG_RIB) {
                                char buf[SRCDEST2STR_BUFFER];
                                srcdest_rnode2str(rn, buf, sizeof(buf));
                                if (new != old)
                                        zlog_debug(
                                                "%u:%s: Updating route rn %p, re %p (%s) old %p (%s)",
                                                zvrf_id(zvrf), buf, rn, new,
                                                zebra_route_string(new->type),
                                                old,
                                                zebra_route_string(old->type));
                                else
                                        zlog_debug(
                                                "%u:%s: Updating route rn %p, re %p (%s)",
                                                zvrf_id(zvrf), buf, rn, new,
                                                zebra_route_string(new->type));
                        }

                        /* If labeled-unicast route, uninstall transit LSP. */
                        if (zebra_rib_labeled_unicast(old))
                                zebra_mpls_lsp_uninstall(zvrf, rn, old);

                        /*
                         * Non-system route should be installed.
                         * If labeled-unicast route, install transit
                         * LSP.
                         */
                        if (zebra_rib_labeled_unicast(new))
                                zebra_mpls_lsp_install(zvrf, rn, new);

                        rib_install_kernel(rn, new, old);
                }

                /*
                 * If nexthop for selected route is not active or install
                 * failed, we
                 * may need to uninstall and delete for redistribution.
                 */
                if (!nh_active) {
                        if (IS_ZEBRA_DEBUG_RIB) {
                                char buf[SRCDEST2STR_BUFFER];
                                srcdest_rnode2str(rn, buf, sizeof(buf));
                                if (new != old)
                                        zlog_debug(
                                                "%u:%s: Deleting route rn %p, re %p (%s) old %p (%s) - nexthop inactive",
                                                zvrf_id(zvrf), buf, rn, new,
                                                zebra_route_string(new->type),
                                                old,
                                                zebra_route_string(old->type));
                                else
                                        zlog_debug(
                                                "%u:%s: Deleting route rn %p, re %p (%s) - nexthop inactive",
                                                zvrf_id(zvrf), buf, rn, new,
                                                zebra_route_string(new->type));
                        }

                        /* If labeled-unicast route, uninstall transit LSP. */
                        if (zebra_rib_labeled_unicast(old))
                                zebra_mpls_lsp_uninstall(zvrf, rn, old);

                        rib_uninstall_kernel(rn, old);
                }
        } else {
                /*
                 * Same route selected; check if in the FIB and if not,
                 * re-install. This is housekeeping code to deal with
                 * race conditions in kernel with linux netlink reporting
                 * interface up before IPv4 or IPv6 protocol is ready
                 * to add routes.
                 */
                if (!CHECK_FLAG(new->status, ROUTE_ENTRY_INSTALLED) ||
                    RIB_SYSTEM_ROUTE(new))
                        rib_install_kernel(rn, new, NULL);
        }

        /* Update prior route. */
        if (new != old)
                UNSET_FLAG(old->status, ROUTE_ENTRY_CHANGED);

        /* Clear changed flag. */
        UNSET_FLAG(new->status, ROUTE_ENTRY_CHANGED);
}

/* Check if 'alternate' RIB entry is better than 'current'. */
static struct route_entry *rib_choose_best(struct route_entry *current,
                                           struct route_entry *alternate)
{
        if (current == NULL)
                return alternate;

        /* filter route selection in following order:
         * - connected beats other types
         * - if both connected, loopback or vrf wins
         * - lower distance beats higher
         * - lower metric beats higher for equal distance
         * - last, hence oldest, route wins tie break.
         */

        /* Connected routes. Check to see if either are a vrf
         * or loopback interface.  If not, pick the last connected
         * route of the set of lowest metric connected routes.
         */
        if (alternate->type == ZEBRA_ROUTE_CONNECT) {
                if (current->type != ZEBRA_ROUTE_CONNECT)
                        return alternate;

                /* both are connected.  are either loop or vrf? */
                struct nexthop *nexthop = NULL;

                for (ALL_NEXTHOPS_PTR(alternate->ng, nexthop)) {
                        struct interface *ifp = if_lookup_by_index(
                                nexthop->ifindex, alternate->vrf_id);

                        if (ifp && if_is_loopback_or_vrf(ifp))
                                return alternate;
                }

                for (ALL_NEXTHOPS_PTR(current->ng, nexthop)) {
                        struct interface *ifp = if_lookup_by_index(
                                nexthop->ifindex, current->vrf_id);

                        if (ifp && if_is_loopback_or_vrf(ifp))
                                return current;
                }

                /* Neither are loop or vrf so pick best metric  */
                if (alternate->metric <= current->metric)
                        return alternate;

                return current;
        }

        if (current->type == ZEBRA_ROUTE_CONNECT)
                return current;

        /* higher distance loses */
        if (alternate->distance < current->distance)
                return alternate;
        if (current->distance < alternate->distance)
                return current;

        /* metric tie-breaks equal distance */
        if (alternate->metric <= current->metric)
                return alternate;

        return current;
}

/* Core function for processing nexthop group contexts's off metaq */
static void rib_nhg_process(struct nhg_ctx *ctx)
{
        nhg_ctx_process(ctx);
}

/* Core function for processing routing information base. */
static void rib_process(struct route_node *rn)
{
        struct route_entry *re;
        struct route_entry *next;
        struct route_entry *old_selected = NULL;
        struct route_entry *new_selected = NULL;
        struct route_entry *old_fib = NULL;
        struct route_entry *new_fib = NULL;
        struct route_entry *best = NULL;
        char buf[SRCDEST2STR_BUFFER];
        rib_dest_t *dest;
        struct zebra_vrf *zvrf = NULL;
        const struct prefix *p, *src_p;

        srcdest_rnode_prefixes(rn, &p, &src_p);
        vrf_id_t vrf_id = VRF_UNKNOWN;

        assert(rn);

        dest = rib_dest_from_rnode(rn);
        if (dest) {
                zvrf = rib_dest_vrf(dest);
                vrf_id = zvrf_id(zvrf);
        }

        if (IS_ZEBRA_DEBUG_RIB)
                srcdest_rnode2str(rn, buf, sizeof(buf));

        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                zlog_debug("%u:%s: Processing rn %p", vrf_id, buf, rn);

        /*
         * we can have rn's that have a NULL info pointer
         * (dest).  As such let's not let the deref happen
         * additionally we know RNODE_FOREACH_RE_SAFE
         * will not iterate so we are ok.
         */
        if (dest)
                old_fib = dest->selected_fib;

        RNODE_FOREACH_RE_SAFE (rn, re, next) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug(
                                "%u:%s: Examine re %p (%s) status %x flags %x dist %d metric %d",
                                vrf_id, buf, re, zebra_route_string(re->type),
                                re->status, re->flags, re->distance,
                                re->metric);

                /* Currently selected re. */
                if (CHECK_FLAG(re->flags, ZEBRA_FLAG_SELECTED)) {
                        assert(old_selected == NULL);
                        old_selected = re;
                }

                /* Skip deleted entries from selection */
                if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
                        continue;

                /* Skip unreachable nexthop. */
                /* This first call to nexthop_active_update is merely to
                 * determine if there's any change to nexthops associated
                 * with this RIB entry. Now, rib_process() can be invoked due
                 * to an external event such as link down or due to
                 * next-hop-tracking evaluation. In the latter case,
                 * a decision has already been made that the NHs have changed.
                 * So, no need to invoke a potentially expensive call again.
                 * Further, since the change might be in a recursive NH which
                 * is not caught in the nexthop_active_update() code. Thus, we
                 * might miss changes to recursive NHs.
                 */
                if (CHECK_FLAG(re->status, ROUTE_ENTRY_CHANGED)
                    && !nexthop_active_update(rn, re)) {
                        if (re->type == ZEBRA_ROUTE_TABLE) {
                                /* XXX: HERE BE DRAGONS!!!!!
                                 * In all honesty, I have not yet figured out
                                 * what this part does or why the
                                 * ROUTE_ENTRY_CHANGED test above is correct
                                 * or why we need to delete a route here, and
                                 * also not whether this concerns both selected
                                 * and fib route, or only selected
                                 * or only fib
                                 *
                                 * This entry was denied by the 'ip protocol
                                 * table' route-map, we need to delete it */
                                if (re != old_selected) {
                                        if (IS_ZEBRA_DEBUG_RIB)
                                                zlog_debug(
                                                        "%s: %u:%s: imported via import-table but denied "
                                                        "by the ip protocol table route-map",
                                                        __func__, vrf_id, buf);
                                        rib_unlink(rn, re);
                                } else
                                        SET_FLAG(re->status,
                                                 ROUTE_ENTRY_REMOVED);
                        }

                        continue;
                }

                /* Infinite distance. */
                if (re->distance == DISTANCE_INFINITY) {
                        UNSET_FLAG(re->status, ROUTE_ENTRY_CHANGED);
                        continue;
                }

                if (CHECK_FLAG(re->flags, ZEBRA_FLAG_FIB_OVERRIDE)) {
                        best = rib_choose_best(new_fib, re);
                        if (new_fib && best != new_fib)
                                UNSET_FLAG(new_fib->status,
                                           ROUTE_ENTRY_CHANGED);
                        new_fib = best;
                } else {
                        best = rib_choose_best(new_selected, re);
                        if (new_selected && best != new_selected)
                                UNSET_FLAG(new_selected->status,
                                           ROUTE_ENTRY_CHANGED);
                        new_selected = best;
                }
                if (best != re)
                        UNSET_FLAG(re->status, ROUTE_ENTRY_CHANGED);
        } /* RNODE_FOREACH_RE */

        /* If no FIB override route, use the selected route also for FIB */
        if (new_fib == NULL)
                new_fib = new_selected;

        /* After the cycle is finished, the following pointers will be set:
         * old_selected --- RE entry currently having SELECTED
         * new_selected --- RE entry that is newly SELECTED
         * old_fib      --- RE entry currently in kernel FIB
         * new_fib      --- RE entry that is newly to be in kernel FIB
         *
         * new_selected will get SELECTED flag, and is going to be redistributed
         * the zclients. new_fib (which can be new_selected) will be installed
         * in kernel.
         */

        if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
                zlog_debug(
                        "%u:%s: After processing: old_selected %p new_selected %p old_fib %p new_fib %p",
                        vrf_id, buf, (void *)old_selected, (void *)new_selected,
                        (void *)old_fib, (void *)new_fib);
        }

        /* Buffer ROUTE_ENTRY_CHANGED here, because it will get cleared if
         * fib == selected */
        bool selected_changed = new_selected && CHECK_FLAG(new_selected->status,
                                                           ROUTE_ENTRY_CHANGED);

        /* Update fib according to selection results */
        if (new_fib && old_fib)
                rib_process_update_fib(zvrf, rn, old_fib, new_fib);
        else if (new_fib)
                rib_process_add_fib(zvrf, rn, new_fib);
        else if (old_fib)
                rib_process_del_fib(zvrf, rn, old_fib);

        /* Update SELECTED entry */
        if (old_selected != new_selected || selected_changed) {

                if (new_selected && new_selected != new_fib)
                        UNSET_FLAG(new_selected->status, ROUTE_ENTRY_CHANGED);

                if (new_selected)
                        SET_FLAG(new_selected->flags, ZEBRA_FLAG_SELECTED);

                if (old_selected) {
                        /*
                         * If we're removing the old entry, we should tell
                         * redist subscribers about that *if* they aren't
                         * going to see a redist for the new entry.
                         */
                        if (!new_selected || CHECK_FLAG(old_selected->status,
                                                        ROUTE_ENTRY_REMOVED))
                                redistribute_delete(p, src_p,
                                                    old_selected,
                                                    new_selected);

                        if (old_selected != new_selected)
                                UNSET_FLAG(old_selected->flags,
                                           ZEBRA_FLAG_SELECTED);
                }
        }

        /* Remove all RE entries queued for removal */
        RNODE_FOREACH_RE_SAFE (rn, re, next) {
                if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED)) {
                        if (IS_ZEBRA_DEBUG_RIB) {
                                rnode_debug(rn, vrf_id, "rn %p, removing re %p",
                                            (void *)rn, (void *)re);
                        }
                        rib_unlink(rn, re);
                }
        }

        /*
         * Check if the dest can be deleted now.
         */
        rib_gc_dest(rn);
}

static void zebra_rib_evaluate_mpls(struct route_node *rn)
{
        rib_dest_t *dest = rib_dest_from_rnode(rn);
        struct zebra_vrf *zvrf = vrf_info_lookup(VRF_DEFAULT);

        if (!dest)
                return;

        if (CHECK_FLAG(dest->flags, RIB_DEST_UPDATE_LSPS)) {
                if (IS_ZEBRA_DEBUG_MPLS)
                        zlog_debug(
                                "%u: Scheduling all LSPs upon RIB completion",
                                zvrf_id(zvrf));
                zebra_mpls_lsp_schedule(zvrf);
                mpls_unmark_lsps_for_processing(rn);
        }
}

/*
 * Utility to match route with dplane context data
 */
static bool rib_route_match_ctx(const struct route_entry *re,
                                const struct zebra_dplane_ctx *ctx,
                                bool is_update)
{
        bool result = false;

        if (is_update) {
                /*
                 * In 'update' case, we test info about the 'previous' or
                 * 'old' route
                 */
                if ((re->type == dplane_ctx_get_old_type(ctx)) &&
                    (re->instance == dplane_ctx_get_old_instance(ctx))) {
                        result = true;

                        /* TODO -- we're using this extra test, but it's not
                         * exactly clear why.
                         */
                        if (re->type == ZEBRA_ROUTE_STATIC &&
                            (re->distance != dplane_ctx_get_old_distance(ctx) ||
                             re->tag != dplane_ctx_get_old_tag(ctx))) {
                                result = false;
                        }
                }

        } else {
                /*
                 * Ordinary, single-route case using primary context info
                 */
                if ((dplane_ctx_get_op(ctx) != DPLANE_OP_ROUTE_DELETE) &&
                    CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED)) {
                        /* Skip route that's been deleted */
                        goto done;
                }

                if ((re->type == dplane_ctx_get_type(ctx)) &&
                    (re->instance == dplane_ctx_get_instance(ctx))) {
                        result = true;

                        /* TODO -- we're using this extra test, but it's not
                         * exactly clear why.
                         */
                        if (re->type == ZEBRA_ROUTE_STATIC &&
                            (re->distance != dplane_ctx_get_distance(ctx) ||
                             re->tag != dplane_ctx_get_tag(ctx))) {
                                result = false;
                        }
                }
        }

done:

        return (result);
}

static void zebra_rib_fixup_system(struct route_node *rn)
{
        struct route_entry *re;

        RNODE_FOREACH_RE(rn, re) {
                struct nexthop *nhop;

                if (!RIB_SYSTEM_ROUTE(re))
                        continue;

                if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
                        continue;

                SET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                UNSET_FLAG(re->status, ROUTE_ENTRY_QUEUED);

                for (ALL_NEXTHOPS_PTR(re->ng, nhop)) {
                        if (CHECK_FLAG(nhop->flags, NEXTHOP_FLAG_RECURSIVE))
                                continue;

                        SET_FLAG(nhop->flags, NEXTHOP_FLAG_FIB);
                }
        }
}

/*
 * Update a route from a dplane context. This consolidates common code
 * that can be used in processing of results from FIB updates, and in
 * async notification processing.
 * The return is 'true' if the installed nexthops changed; 'false' otherwise.
 */
static bool rib_update_re_from_ctx(struct route_entry *re,
                                   struct route_node *rn,
                                   struct zebra_dplane_ctx *ctx)
{
        char dest_str[PREFIX_STRLEN] = "";
        char nh_str[NEXTHOP_STRLEN];
        struct nexthop *nexthop, *ctx_nexthop;
        bool matched;
        const struct nexthop_group *ctxnhg;
        bool is_selected = false; /* Is 're' currently the selected re? */
        bool changed_p = false; /* Change to nexthops? */
        rib_dest_t *dest;

        /* Note well: only capturing the prefix string if debug is enabled here;
         * unconditional log messages will have to generate the string.
         */
        if (IS_ZEBRA_DEBUG_RIB)
                prefix2str(&(rn->p), dest_str, sizeof(dest_str));

        dest = rib_dest_from_rnode(rn);
        if (dest)
                is_selected = (re == dest->selected_fib);

        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                zlog_debug("update_from_ctx: %u:%s: %sSELECTED",
                           re->vrf_id, dest_str, (is_selected ? "" : "NOT "));

        /* Update zebra's nexthop FIB flag for each nexthop that was installed.
         * If the installed set differs from the set requested by the rib/owner,
         * we use the fib-specific nexthop-group to record the actual FIB
         * status.
         */

        /* Check both fib group and notif group for equivalence.
         *
         * Let's assume the nexthops are ordered here to save time.
         */
        if (nexthop_group_equal(&re->fib_ng, dplane_ctx_get_ng(ctx)) == false) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
                        zlog_debug(
                                "%u:%s update_from_ctx: notif nh and fib nh mismatch",
                                re->vrf_id, dest_str);
                }

                matched = false;
        } else
                matched = true;

        /* If the new FIB set matches the existing FIB set, we're done. */
        if (matched) {
                if (IS_ZEBRA_DEBUG_RIB)
                        zlog_debug("%u:%s update_from_ctx(): existing fib nhg, no change",
                                   re->vrf_id, dest_str);
                goto done;

        } else if (re->fib_ng.nexthop) {
                /*
                 * Free stale fib list and move on to check the rib nhg.
                 */
                if (IS_ZEBRA_DEBUG_RIB)
                        zlog_debug("%u:%s update_from_ctx(): replacing fib nhg",
                                   re->vrf_id, dest_str);
                nexthops_free(re->fib_ng.nexthop);
                re->fib_ng.nexthop = NULL;

                /* Note that the installed nexthops have changed */
                changed_p = true;
        } else {
                if (IS_ZEBRA_DEBUG_RIB)
                        zlog_debug("%u:%s update_from_ctx(): no fib nhg",
                                   re->vrf_id, dest_str);
        }

        /*
         * Compare with the rib nexthop group. The comparison here is different:
         * the RIB group may be a superset of the list installed in the FIB. We
         * walk the RIB group, looking for the 'installable' candidate
         * nexthops, and then check those against the set
         * that is actually installed.
         *
         * Assume nexthops are ordered here as well.
         */
        matched = true;

        ctx_nexthop = dplane_ctx_get_ng(ctx)->nexthop;

        /* Get the first `installed` one to check against.
         * If the dataplane doesn't set these to be what was actually installed,
         * it will just be whatever was in re->ng?
         */
        if (CHECK_FLAG(ctx_nexthop->flags, NEXTHOP_FLAG_RECURSIVE)
            || !CHECK_FLAG(ctx_nexthop->flags, NEXTHOP_FLAG_ACTIVE))
                ctx_nexthop = nexthop_next_active_resolved(ctx_nexthop);

        for (ALL_NEXTHOPS_PTR(re->ng, nexthop)) {

                if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
                        continue;

                if (!CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE))
                        continue;

                /* Check for a FIB nexthop corresponding to the RIB nexthop */
                if (nexthop_same(ctx_nexthop, nexthop) == false) {
                        /* If the FIB doesn't know about the nexthop,
                         * it's not installed
                         */
                        if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
                                nexthop2str(nexthop, nh_str, sizeof(nh_str));
                                zlog_debug(
                                        "update_from_ctx: no notif match for rib nh %s",
                                        nh_str);
                        }
                        matched = false;

                        if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                                changed_p = true;

                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);

                        /* Keep checking nexthops */
                        continue;
                }

                if (CHECK_FLAG(ctx_nexthop->flags, NEXTHOP_FLAG_FIB)) {
                        if (!CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                                changed_p = true;

                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                } else {
                        if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                                changed_p = true;

                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                }

                ctx_nexthop = nexthop_next_active_resolved(ctx_nexthop);
        }

        /* If all nexthops were processed, we're done */
        if (matched) {
                if (IS_ZEBRA_DEBUG_RIB)
                        zlog_debug("%u:%s update_from_ctx(): rib nhg matched, changed '%s'",
                                   re->vrf_id, dest_str,
                                   (changed_p ? "true" : "false"));
                goto done;
        }

        /* FIB nexthop set differs from the RIB set:
         * create a fib-specific nexthop-group
         */
        if (IS_ZEBRA_DEBUG_RIB)
                zlog_debug("%u:%s update_from_ctx(): changed %s, adding new fib nhg",
                           re->vrf_id, dest_str,
                           (changed_p ? "true" : "false"));

        ctxnhg = dplane_ctx_get_ng(ctx);

        if (ctxnhg->nexthop)
                copy_nexthops(&(re->fib_ng.nexthop), ctxnhg->nexthop, NULL);
        else {
                /* Bit of a special case when the fib has _no_ installed
                 * nexthops.
                 */
                nexthop = nexthop_new();
                nexthop->type = NEXTHOP_TYPE_IPV4;
                _nexthop_add(&(re->fib_ng.nexthop), nexthop);
        }

done:
        return changed_p;
}

/*
 * Helper to locate a zebra route-node from a dplane context. This is used
 * when processing dplane results, e.g. Note well: the route-node is returned
 * with a ref held - route_unlock_node() must be called eventually.
 */
static struct route_node *
rib_find_rn_from_ctx(const struct zebra_dplane_ctx *ctx)
{
        struct route_table *table = NULL;
        struct route_node *rn = NULL;
        const struct prefix *dest_pfx, *src_pfx;

        /* Locate rn and re(s) from ctx */

        table = zebra_vrf_lookup_table_with_table_id(
                dplane_ctx_get_afi(ctx), dplane_ctx_get_safi(ctx),
                dplane_ctx_get_vrf(ctx), dplane_ctx_get_table(ctx));
        if (table == NULL) {
                if (IS_ZEBRA_DEBUG_DPLANE) {
                        zlog_debug("Failed to find route for ctx: no table for afi %d, safi %d, vrf %u",
                                   dplane_ctx_get_afi(ctx),
                                   dplane_ctx_get_safi(ctx),
                                   dplane_ctx_get_vrf(ctx));
                }
                goto done;
        }

        dest_pfx = dplane_ctx_get_dest(ctx);
        src_pfx = dplane_ctx_get_src(ctx);

        rn = srcdest_rnode_get(table, dest_pfx,
                               src_pfx ? (struct prefix_ipv6 *)src_pfx : NULL);

done:
        return rn;
}



/*
 * Route-update results processing after async dataplane update.
 */
static void rib_process_result(struct zebra_dplane_ctx *ctx)
{
        struct zebra_vrf *zvrf = NULL;
        struct route_node *rn = NULL;
        struct route_entry *re = NULL, *old_re = NULL, *rib;
        bool is_update = false;
        char dest_str[PREFIX_STRLEN] = "";
        enum dplane_op_e op;
        enum zebra_dplane_result status;
        const struct prefix *dest_pfx, *src_pfx;
        uint32_t seq;
        bool fib_changed = false;

        zvrf = vrf_info_lookup(dplane_ctx_get_vrf(ctx));
        dest_pfx = dplane_ctx_get_dest(ctx);

        /* Note well: only capturing the prefix string if debug is enabled here;
         * unconditional log messages will have to generate the string.
         */
        if (IS_ZEBRA_DEBUG_DPLANE)
                prefix2str(dest_pfx, dest_str, sizeof(dest_str));

        /* Locate rn and re(s) from ctx */
        rn = rib_find_rn_from_ctx(ctx);
        if (rn == NULL) {
                if (IS_ZEBRA_DEBUG_DPLANE) {
                        zlog_debug("Failed to process dplane results: no route for %u:%s",
                                   dplane_ctx_get_vrf(ctx), dest_str);
                }
                goto done;
        }

        srcdest_rnode_prefixes(rn, &dest_pfx, &src_pfx);

        op = dplane_ctx_get_op(ctx);
        status = dplane_ctx_get_status(ctx);

        if (IS_ZEBRA_DEBUG_DPLANE_DETAIL)
                zlog_debug("%u:%s Processing dplane ctx %p, op %s result %s",
                           dplane_ctx_get_vrf(ctx), dest_str, ctx,
                           dplane_op2str(op), dplane_res2str(status));

        /*
         * Update is a bit of a special case, where we may have both old and new
         * routes to post-process.
         */
        is_update = dplane_ctx_is_update(ctx);

        /*
         * Take a pass through the routes, look for matches with the context
         * info.
         */
        RNODE_FOREACH_RE(rn, rib) {

                if (re == NULL) {
                        if (rib_route_match_ctx(rib, ctx, false))
                                re = rib;
                }

                /* Check for old route match */
                if (is_update && (old_re == NULL)) {
                        if (rib_route_match_ctx(rib, ctx, true /*is_update*/))
                                old_re = rib;
                }

                /* Have we found the routes we need to work on? */
                if (re && ((!is_update || old_re)))
                        break;
        }

        seq = dplane_ctx_get_seq(ctx);

        /*
         * Check sequence number(s) to detect stale results before continuing
         */
        if (re) {
                if (re->dplane_sequence != seq) {
                        if (IS_ZEBRA_DEBUG_DPLANE_DETAIL)
                                zlog_debug("%u:%s Stale dplane result for re %p",
                                           dplane_ctx_get_vrf(ctx),
                                           dest_str, re);
                } else
                        UNSET_FLAG(re->status, ROUTE_ENTRY_QUEUED);
        }

        if (old_re) {
                if (old_re->dplane_sequence != dplane_ctx_get_old_seq(ctx)) {
                        if (IS_ZEBRA_DEBUG_DPLANE_DETAIL)
                                zlog_debug("%u:%s Stale dplane result for old_re %p",
                                           dplane_ctx_get_vrf(ctx),
                                           dest_str, old_re);
                } else
                        UNSET_FLAG(old_re->status, ROUTE_ENTRY_QUEUED);
        }

        switch (op) {
        case DPLANE_OP_ROUTE_INSTALL:
        case DPLANE_OP_ROUTE_UPDATE:
                if (status == ZEBRA_DPLANE_REQUEST_SUCCESS) {
                        if (re) {
                                UNSET_FLAG(re->status, ROUTE_ENTRY_FAILED);
                                SET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                        }
                        /*
                         * On an update operation from the same route type
                         * context retrieval currently has no way to know
                         * which was the old and which was the new.
                         * So don't unset our flags that we just set.
                         * We know redistribution is ok because the
                         * old_re in this case is used for nothing
                         * more than knowing whom to contact if necessary.
                         */
                        if (old_re && old_re != re) {
                                UNSET_FLAG(old_re->status, ROUTE_ENTRY_FAILED);
                                UNSET_FLAG(old_re->status,
                                           ROUTE_ENTRY_INSTALLED);
                        }

                        /* Update zebra route based on the results in
                         * the context struct.
                         */
                        if (re) {
                                fib_changed =
                                        rib_update_re_from_ctx(re, rn, ctx);

                                if (!fib_changed) {
                                        if (IS_ZEBRA_DEBUG_DPLANE_DETAIL)
                                                zlog_debug("%u:%s no fib change for re",
                                                           dplane_ctx_get_vrf(
                                                                   ctx),
                                                           dest_str);
                                }

                                /* Redistribute */
                                redistribute_update(dest_pfx, src_pfx,
                                                    re, old_re);
                        }

                        /*
                         * System routes are weird in that they
                         * allow multiple to be installed that match
                         * to the same prefix, so after we get the
                         * result we need to clean them up so that
                         * we can actually use them.
                         */
                        if ((re && RIB_SYSTEM_ROUTE(re)) ||
                            (old_re && RIB_SYSTEM_ROUTE(old_re)))
                                zebra_rib_fixup_system(rn);

                        if (zvrf)
                                zvrf->installs++;

                        /* Notify route owner */
                        zsend_route_notify_owner_ctx(ctx, ZAPI_ROUTE_INSTALLED);

                } else {
                        if (re) {
                                SET_FLAG(re->status, ROUTE_ENTRY_FAILED);
                                UNSET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                        } if (old_re)
                                SET_FLAG(old_re->status, ROUTE_ENTRY_FAILED);
                        if (re)
                                zsend_route_notify_owner(re, dest_pfx,
                                                         ZAPI_ROUTE_FAIL_INSTALL);

                        zlog_warn("%u:%s: Route install failed",
                                  dplane_ctx_get_vrf(ctx),
                                  prefix2str(dest_pfx,
                                             dest_str, sizeof(dest_str)));
                }
                break;
        case DPLANE_OP_ROUTE_DELETE:
                if (re)
                        SET_FLAG(re->status, ROUTE_ENTRY_FAILED);
                /*
                 * In the delete case, the zebra core datastructs were
                 * updated (or removed) at the time the delete was issued,
                 * so we're just notifying the route owner.
                 */
                if (status == ZEBRA_DPLANE_REQUEST_SUCCESS) {
                        if (re) {
                                UNSET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                                UNSET_FLAG(re->status, ROUTE_ENTRY_FAILED);
                        }
                        zsend_route_notify_owner_ctx(ctx, ZAPI_ROUTE_REMOVED);

                        if (zvrf)
                                zvrf->removals++;
                } else {
                        if (re)
                                SET_FLAG(re->status, ROUTE_ENTRY_FAILED);
                        zsend_route_notify_owner_ctx(ctx,
                                                     ZAPI_ROUTE_REMOVE_FAIL);

                        zlog_warn("%u:%s: Route Deletion failure",
                                  dplane_ctx_get_vrf(ctx),
                                  prefix2str(dest_pfx,
                                             dest_str, sizeof(dest_str)));
                }

                /*
                 * System routes are weird in that they
                 * allow multiple to be installed that match
                 * to the same prefix, so after we get the
                 * result we need to clean them up so that
                 * we can actually use them.
                 */
                if ((re && RIB_SYSTEM_ROUTE(re)) ||
                    (old_re && RIB_SYSTEM_ROUTE(old_re)))
                        zebra_rib_fixup_system(rn);
                break;
        default:
                break;
        }

        zebra_rib_evaluate_rn_nexthops(rn, seq);
        zebra_rib_evaluate_mpls(rn);
done:

        if (rn)
                route_unlock_node(rn);

        /* Return context to dataplane module */
        dplane_ctx_fini(&ctx);
}

/*
 * Handle notification from async dataplane: the dataplane has detected
 * some change to a route, and notifies zebra so that the control plane
 * can reflect that change.
 */
static void rib_process_dplane_notify(struct zebra_dplane_ctx *ctx)
{
        struct route_node *rn = NULL;
        struct route_entry *re = NULL;
        struct nexthop *nexthop;
        char dest_str[PREFIX_STRLEN] = "";
        const struct prefix *dest_pfx, *src_pfx;
        rib_dest_t *dest;
        bool fib_changed = false;
        bool debug_p = IS_ZEBRA_DEBUG_DPLANE | IS_ZEBRA_DEBUG_RIB;
        int start_count, end_count;
        dest_pfx = dplane_ctx_get_dest(ctx);

        /* Note well: only capturing the prefix string if debug is enabled here;
         * unconditional log messages will have to generate the string.
         */
        if (debug_p)
                prefix2str(dest_pfx, dest_str, sizeof(dest_str));

        /* Locate rn and re(s) from ctx */
        rn = rib_find_rn_from_ctx(ctx);
        if (rn == NULL) {
                if (debug_p) {
                        zlog_debug("Failed to process dplane notification: no routes for %u:%s",
                                   dplane_ctx_get_vrf(ctx), dest_str);
                }
                goto done;
        }

        dest = rib_dest_from_rnode(rn);
        srcdest_rnode_prefixes(rn, &dest_pfx, &src_pfx);

        if (debug_p)
                zlog_debug("%u:%s Processing dplane notif ctx %p",
                           dplane_ctx_get_vrf(ctx), dest_str, ctx);

        /*
         * Take a pass through the routes, look for matches with the context
         * info.
         */
        RNODE_FOREACH_RE(rn, re) {
                if (rib_route_match_ctx(re, ctx, false /*!update*/))
                        break;
        }

        /* No match? Nothing we can do */
        if (re == NULL) {
                if (debug_p)
                        zlog_debug("%u:%s Unable to process dplane notification: no entry for type %s",
                                   dplane_ctx_get_vrf(ctx), dest_str,
                                   zebra_route_string(
                                           dplane_ctx_get_type(ctx)));

                goto done;
        }

        /* Ensure we clear the QUEUED flag */
        UNSET_FLAG(re->status, ROUTE_ENTRY_QUEUED);

        /* Is this a notification that ... matters? We only really care about
         * the route that is currently selected for installation.
         */
        if (re != dest->selected_fib) {
                /* TODO -- don't skip processing entirely? We might like to
                 * at least report on the event.
                 */
                if (debug_p)
                        zlog_debug("%u:%s dplane notif, but type %s not selected_fib",
                                   dplane_ctx_get_vrf(ctx), dest_str,
                                   zebra_route_string(
                                           dplane_ctx_get_type(ctx)));
                goto done;
        }

        /* We'll want to determine whether the installation status of the
         * route has changed: we'll check the status before processing,
         * and then again if there's been a change.
         */
        start_count = 0;
        for (ALL_NEXTHOPS_PTR(rib_active_nhg(re), nexthop)) {
                if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                        start_count++;
        }

        /* Update zebra's nexthop FIB flags based on the context struct's
         * nexthops.
         */
        fib_changed = rib_update_re_from_ctx(re, rn, ctx);

        if (!fib_changed) {
                if (debug_p)
                        zlog_debug("%u:%s No change from dplane notification",
                                   dplane_ctx_get_vrf(ctx), dest_str);

                goto done;
        }

        /*
         * Perform follow-up work if the actual status of the prefix
         * changed.
         */

        end_count = 0;
        for (ALL_NEXTHOPS_PTR(rib_active_nhg(re), nexthop)) {
                if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                        end_count++;
        }

        /* Various fib transitions: changed nexthops; from installed to
         * not-installed; or not-installed to installed.
         */
        if (start_count > 0 && end_count > 0) {
                if (debug_p)
                        zlog_debug("%u:%s applied nexthop changes from dplane notification",
                                   dplane_ctx_get_vrf(ctx), dest_str);

                /* Changed nexthops - update kernel/others */
                dplane_route_notif_update(rn, re,
                                          DPLANE_OP_ROUTE_UPDATE, ctx);

        } else if (start_count == 0 && end_count > 0) {
                if (debug_p)
                        zlog_debug("%u:%s installed transition from dplane notification",
                                   dplane_ctx_get_vrf(ctx), dest_str);

                /* We expect this to be the selected route, so we want
                 * to tell others about this transition.
                 */
                SET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);

                /* Changed nexthops - update kernel/others */
                dplane_route_notif_update(rn, re, DPLANE_OP_ROUTE_INSTALL, ctx);

                /* Redistribute, lsp, and nht update */
                redistribute_update(dest_pfx, src_pfx, re, NULL);

                zebra_rib_evaluate_rn_nexthops(
                        rn, zebra_router_get_next_sequence());

                zebra_rib_evaluate_mpls(rn);

        } else if (start_count > 0 && end_count == 0) {
                if (debug_p)
                        zlog_debug("%u:%s un-installed transition from dplane notification",
                                   dplane_ctx_get_vrf(ctx), dest_str);

                /* Transition from _something_ installed to _nothing_
                 * installed.
                 */
                /* We expect this to be the selected route, so we want
                 * to tell others about this transistion.
                 */
                UNSET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);

                /* Changed nexthops - update kernel/others */
                dplane_route_notif_update(rn, re, DPLANE_OP_ROUTE_DELETE, ctx);

                /* Redistribute, lsp, and nht update */
                redistribute_delete(dest_pfx, src_pfx, re, NULL);

                zebra_rib_evaluate_rn_nexthops(
                        rn, zebra_router_get_next_sequence());

                zebra_rib_evaluate_mpls(rn);
        }

done:
        if (rn)
                route_unlock_node(rn);

        /* Return context to dataplane module */
        dplane_ctx_fini(&ctx);
}

static void process_subq_nhg(struct listnode *lnode)
{
        struct nhg_ctx *ctx = NULL;
        uint8_t qindex = route_info[ZEBRA_ROUTE_NHG].meta_q_map;

        ctx = listgetdata(lnode);

        if (!ctx)
                return;

        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                zlog_debug("NHG Context id=%u dequeued from sub-queue %u",
                           ctx->id, qindex);

        rib_nhg_process(ctx);
}

static void process_subq_route(struct listnode *lnode, uint8_t qindex)
{
        struct route_node *rnode = NULL;
        rib_dest_t *dest = NULL;
        struct zebra_vrf *zvrf = NULL;

        rnode = listgetdata(lnode);
        dest = rib_dest_from_rnode(rnode);
        if (dest)
                zvrf = rib_dest_vrf(dest);

        rib_process(rnode);

        if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
                char buf[SRCDEST2STR_BUFFER];

                srcdest_rnode2str(rnode, buf, sizeof(buf));
                zlog_debug("%u:%s: rn %p dequeued from sub-queue %u",
                           zvrf ? zvrf_id(zvrf) : 0, buf, rnode, qindex);
        }

        if (rnode->info)
                UNSET_FLAG(rib_dest_from_rnode(rnode)->flags,
                           RIB_ROUTE_QUEUED(qindex));

#if 0
  else
    {
      zlog_debug ("%s: called for route_node (%p, %d) with no ribs",
                  __func__, rnode, rnode->lock);
      zlog_backtrace(LOG_DEBUG);
    }
#endif
        route_unlock_node(rnode);
}

/* Take a list of route_node structs and return 1, if there was a record
 * picked from it and processed by rib_process(). Don't process more,
 * than one RN record; operate only in the specified sub-queue.
 */
static unsigned int process_subq(struct list *subq, uint8_t qindex)
{
        struct listnode *lnode = listhead(subq);

        if (!lnode)
                return 0;

        if (qindex == route_info[ZEBRA_ROUTE_NHG].meta_q_map)
                process_subq_nhg(lnode);
        else
                process_subq_route(lnode, qindex);

        list_delete_node(subq, lnode);

        return 1;
}

/* Dispatch the meta queue by picking, processing and unlocking the next RN from
 * a non-empty sub-queue with lowest priority. wq is equal to zebra->ribq and
 * data
 * is pointed to the meta queue structure.
 */
static wq_item_status meta_queue_process(struct work_queue *dummy, void *data)
{
        struct meta_queue *mq = data;
        unsigned i;
        uint32_t queue_len, queue_limit;

        /* Ensure there's room for more dataplane updates */
        queue_limit = dplane_get_in_queue_limit();
        queue_len = dplane_get_in_queue_len();
        if (queue_len > queue_limit) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug("rib queue: dplane queue len %u, limit %u, retrying",
                                   queue_len, queue_limit);

                /* Ensure that the meta-queue is actually enqueued */
                if (work_queue_empty(zrouter.ribq))
                        work_queue_add(zrouter.ribq, zrouter.mq);

                return WQ_QUEUE_BLOCKED;
        }

        for (i = 0; i < MQ_SIZE; i++)
                if (process_subq(mq->subq[i], i)) {
                        mq->size--;
                        break;
                }
        return mq->size ? WQ_REQUEUE : WQ_SUCCESS;
}


/*
 * Look into the RN and queue it into the highest priority queue
 * at this point in time for processing.
 *
 * We will enqueue a route node only once per invocation.
 *
 * There are two possibilities here that should be kept in mind.
 * If the original invocation has not been pulled off for processing
 * yet, A subsuquent invocation can have a route entry with a better
 * meta queue index value and we can have a situation where
 * we might have the same node enqueued 2 times.  Not necessarily
 * an optimal situation but it should be ok.
 *
 * The other possibility is that the original invocation has not
 * been pulled off for processing yet, A subsusquent invocation
 * doesn't have a route_entry with a better meta-queue and the
 * original metaqueue index value will win and we'll end up with
 * the route node enqueued once.
 */
static int rib_meta_queue_add(struct meta_queue *mq, void *data)
{
        struct route_node *rn = NULL;
        struct route_entry *re = NULL, *curr_re = NULL;
        uint8_t qindex = MQ_SIZE, curr_qindex = MQ_SIZE;

        rn = (struct route_node *)data;

        RNODE_FOREACH_RE (rn, curr_re) {
                curr_qindex = route_info[curr_re->type].meta_q_map;

                if (curr_qindex <= qindex) {
                        re = curr_re;
                        qindex = curr_qindex;
                }
        }

        if (!re)
                return -1;

        /* Invariant: at this point we always have rn->info set. */
        if (CHECK_FLAG(rib_dest_from_rnode(rn)->flags,
                       RIB_ROUTE_QUEUED(qindex))) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        rnode_debug(rn, re->vrf_id,
                                    "rn %p is already queued in sub-queue %u",
                                    (void *)rn, qindex);
                return -1;
        }

        SET_FLAG(rib_dest_from_rnode(rn)->flags, RIB_ROUTE_QUEUED(qindex));
        listnode_add(mq->subq[qindex], rn);
        route_lock_node(rn);
        mq->size++;

        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                rnode_debug(rn, re->vrf_id, "queued rn %p into sub-queue %u",
                            (void *)rn, qindex);

        return 0;
}

static int rib_meta_queue_nhg_add(struct meta_queue *mq, void *data)
{
        struct nhg_ctx *ctx = NULL;
        uint8_t qindex = route_info[ZEBRA_ROUTE_NHG].meta_q_map;

        ctx = (struct nhg_ctx *)data;

        if (!ctx)
                return -1;

        listnode_add(mq->subq[qindex], ctx);
        mq->size++;

        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                zlog_debug("NHG Context id=%u queued into sub-queue %u",
                           ctx->id, qindex);

        return 0;
}

static int mq_add_handler(void *data,
                          int (*mq_add_func)(struct meta_queue *mq, void *data))
{
        if (zrouter.ribq == NULL) {
                flog_err(EC_ZEBRA_WQ_NONEXISTENT,
                         "%s: work_queue does not exist!", __func__);
                return -1;
        }

        /*
         * The RIB queue should normally be either empty or holding the only
         * work_queue_item element. In the latter case this element would
         * hold a pointer to the meta queue structure, which must be used to
         * actually queue the route nodes to process. So create the MQ
         * holder, if necessary, then push the work into it in any case.
         * This semantics was introduced after 0.99.9 release.
         */
        if (work_queue_empty(zrouter.ribq))
                work_queue_add(zrouter.ribq, zrouter.mq);

        return mq_add_func(zrouter.mq, data);
}

/* Add route_node to work queue and schedule processing */
int rib_queue_add(struct route_node *rn)
{
        assert(rn);

        /* Pointless to queue a route_node with no RIB entries to add or remove
         */
        if (!rnode_to_ribs(rn)) {
                zlog_debug("%s: called for route_node (%p, %d) with no ribs",
                           __func__, (void *)rn, rn->lock);
                zlog_backtrace(LOG_DEBUG);
                return -1;
        }

        return mq_add_handler(rn, &rib_meta_queue_add);
}

int rib_queue_nhg_add(struct nhg_ctx *ctx)
{
        assert(ctx);

        return mq_add_handler(ctx, &rib_meta_queue_nhg_add);
}

/* Create new meta queue.
   A destructor function doesn't seem to be necessary here.
 */
static struct meta_queue *meta_queue_new(void)
{
        struct meta_queue *new;
        unsigned i;

        new = XCALLOC(MTYPE_WORK_QUEUE, sizeof(struct meta_queue));

        for (i = 0; i < MQ_SIZE; i++) {
                new->subq[i] = list_new();
                assert(new->subq[i]);
        }

        return new;
}

void meta_queue_free(struct meta_queue *mq)
{
        unsigned i;

        for (i = 0; i < MQ_SIZE; i++)
                list_delete(&mq->subq[i]);

        XFREE(MTYPE_WORK_QUEUE, mq);
}

/* initialise zebra rib work queue */
static void rib_queue_init(void)
{
        if (!(zrouter.ribq = work_queue_new(zrouter.master,
                                            "route_node processing"))) {
                flog_err(EC_ZEBRA_WQ_NONEXISTENT,
                         "%s: could not initialise work queue!", __func__);
                return;
        }

        /* fill in the work queue spec */
        zrouter.ribq->spec.workfunc = &meta_queue_process;
        zrouter.ribq->spec.errorfunc = NULL;
        zrouter.ribq->spec.completion_func = NULL;
        /* XXX: TODO: These should be runtime configurable via vty */
        zrouter.ribq->spec.max_retries = 3;
        zrouter.ribq->spec.hold = ZEBRA_RIB_PROCESS_HOLD_TIME;
        zrouter.ribq->spec.retry = ZEBRA_RIB_PROCESS_RETRY_TIME;

        if (!(zrouter.mq = meta_queue_new())) {
                flog_err(EC_ZEBRA_WQ_NONEXISTENT,
                         "%s: could not initialise meta queue!", __func__);
                return;
        }
        return;
}

rib_dest_t *zebra_rib_create_dest(struct route_node *rn)
{
        rib_dest_t *dest;

        dest = XCALLOC(MTYPE_RIB_DEST, sizeof(rib_dest_t));
        rnh_list_init(&dest->nht);
        route_lock_node(rn); /* rn route table reference */
        rn->info = dest;
        dest->rnode = rn;

        return dest;
}

/* RIB updates are processed via a queue of pointers to route_nodes.
 *
 * The queue length is bounded by the maximal size of the routing table,
 * as a route_node will not be requeued, if already queued.
 *
 * REs are submitted via rib_addnode or rib_delnode which set minimal
 * state, or static_install_route (when an existing RE is updated)
 * and then submit route_node to queue for best-path selection later.
 * Order of add/delete state changes are preserved for any given RE.
 *
 * Deleted REs are reaped during best-path selection.
 *
 * rib_addnode
 * |-> rib_link or unset ROUTE_ENTRY_REMOVE      |->Update kernel with
 *       |-------->|                             |  best RE, if required
 *                 |                             |
 * static_install->|->rib_addqueue...... -> rib_process
 *                 |                             |
 *       |-------->|                             |-> rib_unlink
 *       |-> set ROUTE_ENTRY_REMOVE              |
 * rib_delnode                                  (RE freed)
 *
 * The 'info' pointer of a route_node points to a rib_dest_t
 * ('dest'). Queueing state for a route_node is kept on the dest. The
 * dest is created on-demand by rib_link() and is kept around at least
 * as long as there are ribs hanging off it (@see rib_gc_dest()).
 *
 * Refcounting (aka "locking" throughout the GNU Zebra and Quagga code):
 *
 * - route_nodes: refcounted by:
 *   - dest attached to route_node:
 *     - managed by: rib_link/rib_gc_dest
 *   - route_node processing queue
 *     - managed by: rib_addqueue, rib_process.
 *
 */

/* Add RE to head of the route node. */
static void rib_link(struct route_node *rn, struct route_entry *re, int process)
{
        rib_dest_t *dest;
        afi_t afi;
        const char *rmap_name;

        assert(re && rn);

        dest = rib_dest_from_rnode(rn);
        if (!dest) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        rnode_debug(rn, re->vrf_id, "rn %p adding dest", rn);

                dest = zebra_rib_create_dest(rn);
        }

        re_list_add_head(&dest->routes, re);

        afi = (rn->p.family == AF_INET)
                      ? AFI_IP
                      : (rn->p.family == AF_INET6) ? AFI_IP6 : AFI_MAX;
        if (is_zebra_import_table_enabled(afi, re->vrf_id, re->table)) {
                struct zebra_vrf *zvrf = zebra_vrf_lookup_by_id(re->vrf_id);

                rmap_name = zebra_get_import_table_route_map(afi, re->table);
                zebra_add_import_table_entry(zvrf, rn, re, rmap_name);
        } else if (process)
                rib_queue_add(rn);
}

static void rib_addnode(struct route_node *rn,
                        struct route_entry *re, int process)
{
        /* RE node has been un-removed before route-node is processed.
         * route_node must hence already be on the queue for processing..
         */
        if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED)) {
                if (IS_ZEBRA_DEBUG_RIB)
                        rnode_debug(rn, re->vrf_id, "rn %p, un-removed re %p",
                                    (void *)rn, (void *)re);

                UNSET_FLAG(re->status, ROUTE_ENTRY_REMOVED);
                return;
        }
        rib_link(rn, re, process);
}

/*
 * rib_unlink
 *
 * Detach a rib structure from a route_node.
 *
 * Note that a call to rib_unlink() should be followed by a call to
 * rib_gc_dest() at some point. This allows a rib_dest_t that is no
 * longer required to be deleted.
 */
void rib_unlink(struct route_node *rn, struct route_entry *re)
{
        rib_dest_t *dest;
        struct nhg_hash_entry *nhe = NULL;

        assert(rn && re);

        if (IS_ZEBRA_DEBUG_RIB)
                rnode_debug(rn, re->vrf_id, "rn %p, re %p", (void *)rn,
                            (void *)re);

        dest = rib_dest_from_rnode(rn);

        re_list_del(&dest->routes, re);

        if (dest->selected_fib == re)
                dest->selected_fib = NULL;

        if (re->nhe_id) {
                nhe = zebra_nhg_lookup_id(re->nhe_id);
                if (nhe)
                        zebra_nhg_decrement_ref(nhe);
        } else if (re->ng)
                nexthop_group_delete(&re->ng);

        nexthops_free(re->fib_ng.nexthop);

        XFREE(MTYPE_RE, re);
}

void rib_delnode(struct route_node *rn, struct route_entry *re)
{
        afi_t afi;

        if (IS_ZEBRA_DEBUG_RIB)
                rnode_debug(rn, re->vrf_id, "rn %p, re %p, removing",
                            (void *)rn, (void *)re);
        SET_FLAG(re->status, ROUTE_ENTRY_REMOVED);

        afi = (rn->p.family == AF_INET)
                      ? AFI_IP
                      : (rn->p.family == AF_INET6) ? AFI_IP6 : AFI_MAX;
        if (is_zebra_import_table_enabled(afi, re->vrf_id, re->table)) {
                struct zebra_vrf *zvrf = zebra_vrf_lookup_by_id(re->vrf_id);

                zebra_del_import_table_entry(zvrf, rn, re);
                /* Just clean up if non main table */
                if (IS_ZEBRA_DEBUG_RIB) {
                        char buf[SRCDEST2STR_BUFFER];
                        srcdest_rnode2str(rn, buf, sizeof(buf));
                        zlog_debug("%u:%s: Freeing route rn %p, re %p (%s)",
                                   re->vrf_id, buf, rn, re,
                                   zebra_route_string(re->type));
                }

                rib_unlink(rn, re);
        } else {
                rib_queue_add(rn);
        }
}

/* This function dumps the contents of a given RE entry into
 * standard debug log. Calling function name and IP prefix in
 * question are passed as 1st and 2nd arguments.
 */

void _route_entry_dump(const char *func, union prefixconstptr pp,
                       union prefixconstptr src_pp,
                       const struct route_entry *re)
{
        const struct prefix *src_p = src_pp.p;
        bool is_srcdst = src_p && src_p->prefixlen;
        char straddr[PREFIX_STRLEN];
        char srcaddr[PREFIX_STRLEN];
        char nhname[PREFIX_STRLEN];
        struct nexthop *nexthop;

        zlog_debug("%s: dumping RE entry %p for %s%s%s vrf %u", func,
                   (const void *)re, prefix2str(pp, straddr, sizeof(straddr)),
                   is_srcdst ? " from " : "",
                   is_srcdst ? prefix2str(src_pp, srcaddr, sizeof(srcaddr))
                             : "",
                   re->vrf_id);
        zlog_debug("%s: uptime == %lu, type == %u, instance == %d, table == %d",
                   straddr, (unsigned long)re->uptime, re->type, re->instance,
                   re->table);
        zlog_debug(
                "%s: metric == %u, mtu == %u, distance == %u, flags == %u, status == %u",
                straddr, re->metric, re->mtu, re->distance, re->flags, re->status);
        zlog_debug("%s: nexthop_num == %u, nexthop_active_num == %u", straddr,
                   nexthop_group_nexthop_num(re->ng),
                   nexthop_group_active_nexthop_num(re->ng));

        for (ALL_NEXTHOPS_PTR(re->ng, nexthop)) {
                struct interface *ifp;
                struct vrf *vrf = vrf_lookup_by_id(nexthop->vrf_id);

                switch (nexthop->type) {
                case NEXTHOP_TYPE_BLACKHOLE:
                        sprintf(nhname, "Blackhole");
                        break;
                case NEXTHOP_TYPE_IFINDEX:
                        ifp = if_lookup_by_index(nexthop->ifindex,
                                                 nexthop->vrf_id);
                        sprintf(nhname, "%s", ifp ? ifp->name : "Unknown");
                        break;
                case NEXTHOP_TYPE_IPV4:
                        /* fallthrough */
                case NEXTHOP_TYPE_IPV4_IFINDEX:
                        inet_ntop(AF_INET, &nexthop->gate, nhname,
                                  INET6_ADDRSTRLEN);
                        break;
                case NEXTHOP_TYPE_IPV6:
                case NEXTHOP_TYPE_IPV6_IFINDEX:
                        inet_ntop(AF_INET6, &nexthop->gate, nhname,
                                  INET6_ADDRSTRLEN);
                        break;
                }
                zlog_debug("%s: %s %s[%u] vrf %s(%u) with flags %s%s%s%s%s%s",
                           straddr, (nexthop->rparent ? "  NH" : "NH"), nhname,
                           nexthop->ifindex, vrf ? vrf->name : "Unknown",
                           nexthop->vrf_id,
                           (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE)
                                    ? "ACTIVE "
                                    : ""),
                           (CHECK_FLAG(re->status, ROUTE_ENTRY_INSTALLED)
                                    ? "FIB "
                                    : ""),
                           (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE)
                                    ? "RECURSIVE "
                                    : ""),
                           (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK)
                                    ? "ONLINK "
                                    : ""),
                           (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_MATCHED)
                                    ? "MATCHED "
                                    : ""),
                           (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_DUPLICATE)
                                    ? "DUPLICATE "
                                    : ""));
        }
        zlog_debug("%s: dump complete", straddr);
}

/* This is an exported helper to rtm_read() to dump the strange
 * RE entry found by rib_lookup_ipv4_route()
 */

void rib_lookup_and_dump(struct prefix_ipv4 *p, vrf_id_t vrf_id)
{
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *re;
        char prefix_buf[INET_ADDRSTRLEN];

        /* Lookup table.  */
        table = zebra_vrf_table(AFI_IP, SAFI_UNICAST, vrf_id);
        if (!table) {
                flog_err(EC_ZEBRA_TABLE_LOOKUP_FAILED,
                         "%s:%u zebra_vrf_table() returned NULL", __func__,
                         vrf_id);
                return;
        }

        /* Scan the RIB table for exactly matching RE entry. */
        rn = route_node_lookup(table, (struct prefix *)p);

        /* No route for this prefix. */
        if (!rn) {
                zlog_debug("%s:%u lookup failed for %s", __func__, vrf_id,
                           prefix2str((struct prefix *)p, prefix_buf,
                                      sizeof(prefix_buf)));
                return;
        }

        /* Unlock node. */
        route_unlock_node(rn);

        /* let's go */
        RNODE_FOREACH_RE (rn, re) {
                zlog_debug("%s:%u rn %p, re %p: %s, %s",
                           __func__, vrf_id,
                           (void *)rn, (void *)re,
                           (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED)
                                    ? "removed"
                                    : "NOT removed"),
                           (CHECK_FLAG(re->flags, ZEBRA_FLAG_SELECTED)
                                    ? "selected"
                                    : "NOT selected"));
                route_entry_dump(p, NULL, re);
        }
}

/* Check if requested address assignment will fail due to another
 * route being installed by zebra in FIB already. Take necessary
 * actions, if needed: remove such a route from FIB and deSELECT
 * corresponding RE entry. Then put affected RN into RIBQ head.
 */
void rib_lookup_and_pushup(struct prefix_ipv4 *p, vrf_id_t vrf_id)
{
        struct route_table *table;
        struct route_node *rn;
        rib_dest_t *dest;

        if (NULL == (table = zebra_vrf_table(AFI_IP, SAFI_UNICAST, vrf_id))) {
                flog_err(EC_ZEBRA_TABLE_LOOKUP_FAILED,
                         "%s:%u zebra_vrf_table() returned NULL", __func__,
                         vrf_id);
                return;
        }

        /* No matches would be the simplest case. */
        if (NULL == (rn = route_node_lookup(table, (struct prefix *)p)))
                return;

        /* Unlock node. */
        route_unlock_node(rn);

        dest = rib_dest_from_rnode(rn);
        /* Check all RE entries. In case any changes have to be done, requeue
         * the RN into RIBQ head. If the routing message about the new connected
         * route (generated by the IP address we are going to assign very soon)
         * comes before the RIBQ is processed, the new RE entry will join
         * RIBQ record already on head. This is necessary for proper
         * revalidation
         * of the rest of the RE.
         */
        if (dest->selected_fib) {
                if (IS_ZEBRA_DEBUG_RIB) {
                        char buf[PREFIX_STRLEN];

                        zlog_debug("%u:%s: freeing way for connected prefix",
                                   dest->selected_fib->vrf_id,
                                   prefix2str(&rn->p, buf, sizeof(buf)));
                        route_entry_dump(&rn->p, NULL, dest->selected_fib);
                }
                rib_uninstall(rn, dest->selected_fib);
                rib_queue_add(rn);
        }
}

int rib_add_multipath(afi_t afi, safi_t safi, struct prefix *p,
                      struct prefix_ipv6 *src_p, struct route_entry *re)
{
        struct nhg_hash_entry *nhe = NULL;
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *same = NULL;
        int ret = 0;

        if (!re)
                return 0;

        assert(!src_p || !src_p->prefixlen || afi == AFI_IP6);

        /* Lookup table.  */
        table = zebra_vrf_get_table_with_table_id(afi, safi, re->vrf_id,
                                                  re->table);
        if (!table) {
                if (re->ng)
                        nexthop_group_delete(&re->ng);
                XFREE(MTYPE_RE, re);
                return 0;
        }

        if (re->nhe_id) {
                nhe = zebra_nhg_lookup_id(re->nhe_id);

                if (!nhe) {
                        flog_err(
                                EC_ZEBRA_TABLE_LOOKUP_FAILED,
                                "Zebra failed to find the nexthop hash entry for id=%u in a route entry",
                                re->nhe_id);
                        XFREE(MTYPE_RE, re);
                        return -1;
                }
        } else {
                nhe = zebra_nhg_rib_find(0, re->ng, afi);

                /*
                 * The nexthops got copied over into an nhe,
                 * so free them now.
                 */
                nexthop_group_delete(&re->ng);

                if (!nhe) {
                        char buf[PREFIX_STRLEN] = "";
                        char buf2[PREFIX_STRLEN] = "";

                        flog_err(
                                EC_ZEBRA_TABLE_LOOKUP_FAILED,
                                "Zebra failed to find or create a nexthop hash entry for %s%s%s",
                                prefix2str(p, buf, sizeof(buf)),
                                src_p ? " from " : "",
                                src_p ? prefix2str(src_p, buf2, sizeof(buf2))
                                      : "");

                        XFREE(MTYPE_RE, re);
                        return -1;
                }
        }

        /*
         * Attach the re to the nhe's nexthop group.
         *
         * TODO: This will need to change when we start getting IDs from upper
         * level protocols, as the refcnt might be wrong, since it checks
         * if old_id != new_id.
         */
        zebra_nhg_re_update_ref(re, nhe);

        /* Make it sure prefixlen is applied to the prefix. */
        apply_mask(p);
        if (src_p)
                apply_mask_ipv6(src_p);

        /* Set default distance by route type. */
        if (re->distance == 0)
                re->distance = route_distance(re->type);

        /* Lookup route node.*/
        rn = srcdest_rnode_get(table, p, src_p);

        /*
         * If same type of route are installed, treat it as a implicit
         * withdraw.
         * If the user has specified the No route replace semantics
         * for the install don't do a route replace.
         */
        RNODE_FOREACH_RE (rn, same) {
                if (CHECK_FLAG(same->status, ROUTE_ENTRY_REMOVED))
                        continue;

                if (same->type != re->type)
                        continue;
                if (same->instance != re->instance)
                        continue;
                if (same->type == ZEBRA_ROUTE_KERNEL
                    && same->metric != re->metric)
                        continue;

                if (CHECK_FLAG(re->flags, ZEBRA_FLAG_RR_USE_DISTANCE) &&
                    same->distance != re->distance)
                        continue;

                /*
                 * We should allow duplicate connected routes
                 * because of IPv6 link-local routes and unnumbered
                 * interfaces on Linux.
                 */
                if (same->type != ZEBRA_ROUTE_CONNECT)
                        break;
        }

        /* If this route is kernel/connected route, notify the dataplane. */
        if (RIB_SYSTEM_ROUTE(re)) {
                /* Notify dataplane */
                dplane_sys_route_add(rn, re);
        }

        /* Link new re to node.*/
        if (IS_ZEBRA_DEBUG_RIB) {
                rnode_debug(rn, re->vrf_id,
                            "Inserting route rn %p, re %p (%s) existing %p",
                            rn, re, zebra_route_string(re->type), same);

                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        route_entry_dump(p, src_p, re);
        }

        SET_FLAG(re->status, ROUTE_ENTRY_CHANGED);
        rib_addnode(rn, re, 1);
        ret = 1;

        /* Free implicit route.*/
        if (same) {
                rib_delnode(rn, same);
                ret = -1;
        }

        route_unlock_node(rn);
        return ret;
}

void rib_delete(afi_t afi, safi_t safi, vrf_id_t vrf_id, int type,
                unsigned short instance, int flags, struct prefix *p,
                struct prefix_ipv6 *src_p, const struct nexthop *nh,
                uint32_t nhe_id, uint32_t table_id, uint32_t metric,
                uint8_t distance, bool fromkernel)
{
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *re;
        struct route_entry *fib = NULL;
        struct route_entry *same = NULL;
        struct nexthop *rtnh;
        char buf2[INET6_ADDRSTRLEN];
        rib_dest_t *dest;

        assert(!src_p || !src_p->prefixlen || afi == AFI_IP6);

        /* Lookup table.  */
        table = zebra_vrf_lookup_table_with_table_id(afi, safi, vrf_id,
                                                     table_id);
        if (!table)
                return;

        /* Apply mask. */
        apply_mask(p);
        if (src_p)
                apply_mask_ipv6(src_p);

        /* Lookup route node. */
        rn = srcdest_rnode_lookup(table, p, src_p);
        if (!rn) {
                char dst_buf[PREFIX_STRLEN], src_buf[PREFIX_STRLEN];

                prefix2str(p, dst_buf, sizeof(dst_buf));
                if (src_p && src_p->prefixlen)
                        prefix2str(src_p, src_buf, sizeof(src_buf));
                else
                        src_buf[0] = '\0';

                if (IS_ZEBRA_DEBUG_RIB) {
                        struct vrf *vrf = vrf_lookup_by_id(vrf_id);

                        zlog_debug("%s[%d]:%s%s%s doesn't exist in rib",
                                   vrf->name, table_id, dst_buf,
                                   (src_buf[0] != '\0') ? " from " : "",
                                   src_buf);
                }
                return;
        }

        dest = rib_dest_from_rnode(rn);
        fib = dest->selected_fib;

        /* Lookup same type route. */
        RNODE_FOREACH_RE (rn, re) {
                if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
                        continue;

                if (re->type != type)
                        continue;
                if (re->instance != instance)
                        continue;
                if (CHECK_FLAG(re->flags, ZEBRA_FLAG_RR_USE_DISTANCE) &&
                    distance != re->distance)
                        continue;

                if (re->type == ZEBRA_ROUTE_KERNEL && re->metric != metric)
                        continue;
                if (re->type == ZEBRA_ROUTE_CONNECT && (rtnh = re->ng->nexthop)
                    && rtnh->type == NEXTHOP_TYPE_IFINDEX && nh) {
                        if (rtnh->ifindex != nh->ifindex)
                                continue;
                        same = re;
                        break;
                }

                /* Make sure that the route found has the same gateway. */
                if (nhe_id && re->nhe_id == nhe_id) {
                        same = re;
                        break;
                }

                if (nh == NULL) {
                        same = re;
                        break;
                }
                for (ALL_NEXTHOPS_PTR(re->ng, rtnh)) {
                        /*
                         * No guarantee all kernel send nh with labels
                         * on delete.
                         */
                        if (nexthop_same_no_labels(rtnh, nh)) {
                                same = re;
                                break;
                        }
                }

                if (same)
                        break;
        }
        /* If same type of route can't be found and this message is from
           kernel. */
        if (!same) {
                /*
                 * In the past(HA!) we could get here because
                 * we were receiving a route delete from the
                 * kernel and we're not marking the proto
                 * as coming from it's appropriate originator.
                 * Now that we are properly noticing the fact
                 * that the kernel has deleted our route we
                 * are not going to get called in this path
                 * I am going to leave this here because
                 * this might still work this way on non-linux
                 * platforms as well as some weird state I have
                 * not properly thought of yet.
                 * If we can show that this code path is
                 * dead then we can remove it.
                 */
                if (fib && CHECK_FLAG(flags, ZEBRA_FLAG_SELFROUTE)) {
                        if (IS_ZEBRA_DEBUG_RIB) {
                                rnode_debug(rn, vrf_id,
                                            "rn %p, re %p (%s) was deleted from kernel, adding",
                                            rn, fib,
                                            zebra_route_string(fib->type));
                        }
                        if (allow_delete) {
                                UNSET_FLAG(fib->status, ROUTE_ENTRY_INSTALLED);
                                /* Unset flags. */
                                for (rtnh = fib->ng->nexthop; rtnh;
                                     rtnh = rtnh->next)
                                        UNSET_FLAG(rtnh->flags,
                                                   NEXTHOP_FLAG_FIB);

                                /*
                                 * This is a non FRR route
                                 * as such we should mark
                                 * it as deleted
                                 */
                                dest->selected_fib = NULL;
                        } else {
                                /* This means someone else, other than Zebra,
                                 * has deleted
                                 * a Zebra router from the kernel. We will add
                                 * it back */
                                rib_install_kernel(rn, fib, NULL);
                        }
                } else {
                        if (IS_ZEBRA_DEBUG_RIB) {
                                if (nh)
                                        rnode_debug(
                                                rn, vrf_id,
                                                "via %s ifindex %d type %d "
                                                "doesn't exist in rib",
                                                inet_ntop(afi2family(afi),
                                                          &nh->gate, buf2,
                                                          sizeof(buf2)),
                                                          nh->ifindex, type);
                                else
                                        rnode_debug(
                                                rn, vrf_id,
                                                "type %d doesn't exist in rib",
                                                type);
                        }
                        route_unlock_node(rn);
                        return;
                }
        }

        if (same) {
                if (fromkernel && CHECK_FLAG(flags, ZEBRA_FLAG_SELFROUTE)
                    && !allow_delete) {
                        rib_install_kernel(rn, same, NULL);
                        route_unlock_node(rn);

                        return;
                }

                /* Special handling for IPv4 or IPv6 routes sourced from
                 * EVPN - the nexthop (and associated MAC) need to be
                 * uninstalled if no more refs.
                 */
                if (CHECK_FLAG(flags, ZEBRA_FLAG_EVPN_ROUTE)) {
                        struct nexthop *tmp_nh;

                        for (ALL_NEXTHOPS_PTR(re->ng, tmp_nh)) {
                                struct ipaddr vtep_ip;

                                memset(&vtep_ip, 0, sizeof(struct ipaddr));
                                if (afi == AFI_IP) {
                                        vtep_ip.ipa_type = IPADDR_V4;
                                        memcpy(&(vtep_ip.ipaddr_v4),
                                               &(tmp_nh->gate.ipv4),
                                               sizeof(struct in_addr));
                                } else {
                                        vtep_ip.ipa_type = IPADDR_V6;
                                        memcpy(&(vtep_ip.ipaddr_v6),
                                               &(tmp_nh->gate.ipv6),
                                               sizeof(struct in6_addr));
                                }
                                zebra_vxlan_evpn_vrf_route_del(re->vrf_id,
                                                               &vtep_ip, p);
                        }
                }

                /* Notify dplane if system route changes */
                if (RIB_SYSTEM_ROUTE(re))
                        dplane_sys_route_del(rn, same);

                rib_delnode(rn, same);
        }

        route_unlock_node(rn);
        return;
}


int rib_add(afi_t afi, safi_t safi, vrf_id_t vrf_id, int type,
            unsigned short instance, int flags, struct prefix *p,
            struct prefix_ipv6 *src_p, const struct nexthop *nh,
            uint32_t nhe_id, uint32_t table_id, uint32_t metric, uint32_t mtu,
            uint8_t distance, route_tag_t tag)
{
        struct route_entry *re = NULL;
        struct nexthop *nexthop = NULL;

        /* Allocate new route_entry structure. */
        re = XCALLOC(MTYPE_RE, sizeof(struct route_entry));
        re->type = type;
        re->instance = instance;
        re->distance = distance;
        re->flags = flags;
        re->metric = metric;
        re->mtu = mtu;
        re->table = table_id;
        re->vrf_id = vrf_id;
        re->uptime = monotime(NULL);
        re->tag = tag;
        re->nhe_id = nhe_id;

        if (!nhe_id) {
                re->ng = nexthop_group_new();

                /* Add nexthop. */
                nexthop = nexthop_new();
                *nexthop = *nh;
                route_entry_nexthop_add(re, nexthop);
        }

        return rib_add_multipath(afi, safi, p, src_p, re);
}

static const char *rib_update_event2str(rib_update_event_t event)
{
        const char *ret = "UNKNOWN";

        switch (event) {
        case RIB_UPDATE_KERNEL:
                ret = "RIB_UPDATE_KERNEL";
                break;
        case RIB_UPDATE_RMAP_CHANGE:
                ret = "RIB_UPDATE_RMAP_CHANGE";
                break;
        case RIB_UPDATE_OTHER:
                ret = "RIB_UPDATE_OTHER";
                break;
        case RIB_UPDATE_MAX:
                break;
        }

        return ret;
}


/* Schedule route nodes to be processed if they match the type */
static void rib_update_route_node(struct route_node *rn, int type)
{
        struct route_entry *re, *next;
        bool re_changed = false;

        RNODE_FOREACH_RE_SAFE (rn, re, next) {
                if (type == ZEBRA_ROUTE_ALL || type == re->type) {
                        SET_FLAG(re->status, ROUTE_ENTRY_CHANGED);
                        re_changed = true;
                }
        }

        if (re_changed)
                rib_queue_add(rn);
}

/* Schedule routes of a particular table (address-family) based on event. */
void rib_update_table(struct route_table *table, rib_update_event_t event)
{
        struct route_node *rn;

        if (IS_ZEBRA_DEBUG_EVENT) {
                struct zebra_vrf *zvrf;
                struct vrf *vrf;

                zvrf = table->info ? ((rib_table_info_t *)table->info)->zvrf
                                   : NULL;
                vrf = zvrf ? zvrf->vrf : NULL;

                zlog_debug("%s: %s VRF %s Table %u event %s", __func__,
                           table->info ? afi2str(
                                   ((rib_table_info_t *)table->info)->afi)
                                       : "Unknown",
                           vrf ? vrf->name : "Unknown",
                           zvrf ? zvrf->table_id : 0,
                           rib_update_event2str(event));
        }

        /* Walk all routes and queue for processing, if appropriate for
         * the trigger event.
         */
        for (rn = route_top(table); rn; rn = srcdest_route_next(rn)) {
                /*
                 * If we are looking at a route node and the node
                 * has already been queued  we don't
                 * need to queue it up again
                 */
                if (rn->info
                    && CHECK_FLAG(rib_dest_from_rnode(rn)->flags,
                                  RIB_ROUTE_ANY_QUEUED))
                        continue;

                switch (event) {
                case RIB_UPDATE_KERNEL:
                        rib_update_route_node(rn, ZEBRA_ROUTE_KERNEL);
                        break;
                case RIB_UPDATE_RMAP_CHANGE:
                case RIB_UPDATE_OTHER:
                        rib_update_route_node(rn, ZEBRA_ROUTE_ALL);
                        break;
                default:
                        break;
                }
        }
}

static void rib_update_handle_vrf(vrf_id_t vrf_id, rib_update_event_t event)
{
        struct route_table *table;

        if (IS_ZEBRA_DEBUG_EVENT)
                zlog_debug("%s: Handling VRF %s event %s", __func__,
                           vrf_id_to_name(vrf_id), rib_update_event2str(event));

        /* Process routes of interested address-families. */
        table = zebra_vrf_table(AFI_IP, SAFI_UNICAST, vrf_id);
        if (table)
                rib_update_table(table, event);

        table = zebra_vrf_table(AFI_IP6, SAFI_UNICAST, vrf_id);
        if (table)
                rib_update_table(table, event);
}

static void rib_update_handle_vrf_all(rib_update_event_t event)
{
        struct zebra_router_table *zrt;

        if (IS_ZEBRA_DEBUG_EVENT)
                zlog_debug("%s: Handling VRF (ALL) event %s", __func__,
                           rib_update_event2str(event));

        /* Just iterate over all the route tables, rather than vrf lookups */
        RB_FOREACH (zrt, zebra_router_table_head, &zrouter.tables)
                rib_update_table(zrt->table, event);
}

struct rib_update_ctx {
        rib_update_event_t event;
        bool vrf_all;
        vrf_id_t vrf_id;
};

static struct rib_update_ctx *rib_update_ctx_init(vrf_id_t vrf_id,
                                                  rib_update_event_t event)
{
        struct rib_update_ctx *ctx;

        ctx = XCALLOC(MTYPE_RIB_UPDATE_CTX, sizeof(struct rib_update_ctx));

        ctx->event = event;
        ctx->vrf_id = vrf_id;

        return ctx;
}

static void rib_update_ctx_fini(struct rib_update_ctx **ctx)
{
        XFREE(MTYPE_RIB_UPDATE_CTX, *ctx);

        *ctx = NULL;
}

static int rib_update_handler(struct thread *thread)
{
        struct rib_update_ctx *ctx;

        ctx = THREAD_ARG(thread);

        if (ctx->vrf_all)
                rib_update_handle_vrf_all(ctx->event);
        else
                rib_update_handle_vrf(ctx->vrf_id, ctx->event);

        rib_update_ctx_fini(&ctx);

        return 0;
}

/*
 * Thread list to ensure we don't schedule a ton of events
 * if interfaces are flapping for instance.
 */
static struct thread *t_rib_update_threads[RIB_UPDATE_MAX];

/* Schedule a RIB update event for specific vrf */
void rib_update_vrf(vrf_id_t vrf_id, rib_update_event_t event)
{
        struct rib_update_ctx *ctx;

        ctx = rib_update_ctx_init(vrf_id, event);

        /* Don't worry about making sure multiple rib updates for specific vrf
         * are scheduled at once for now. If it becomes a problem, we can use a
         * lookup of some sort to keep track of running threads via t_vrf_id
         * like how we are doing it in t_rib_update_threads[].
         */
        thread_add_event(zrouter.master, rib_update_handler, ctx, 0, NULL);

        if (IS_ZEBRA_DEBUG_EVENT)
                zlog_debug("%s: Scheduled VRF %s, event %s", __func__,
                           vrf_id_to_name(ctx->vrf_id),
                           rib_update_event2str(event));
}

/* Schedule a RIB update event for all vrfs */
void rib_update(rib_update_event_t event)
{
        struct rib_update_ctx *ctx;

        ctx = rib_update_ctx_init(0, event);

        ctx->vrf_all = true;

        if (!thread_add_event(zrouter.master, rib_update_handler, ctx, 0,
                              &t_rib_update_threads[event]))
                rib_update_ctx_fini(&ctx); /* Already scheduled */
        else if (IS_ZEBRA_DEBUG_EVENT)
                zlog_debug("%s: Schedued VRF (ALL), event %s", __func__,
                           rib_update_event2str(event));
}

/* Delete self installed routes after zebra is relaunched.  */
void rib_sweep_table(struct route_table *table)
{
        struct route_node *rn;
        struct route_entry *re;
        struct route_entry *next;
        struct nexthop *nexthop;

        if (!table)
                return;

        for (rn = route_top(table); rn; rn = srcdest_route_next(rn)) {
                RNODE_FOREACH_RE_SAFE (rn, re, next) {

                        if (IS_ZEBRA_DEBUG_RIB)
                                route_entry_dump(&rn->p, NULL, re);

                        if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
                                continue;

                        if (!CHECK_FLAG(re->flags, ZEBRA_FLAG_SELFROUTE))
                                continue;

                        /*
                         * If routes are older than startup_time then
                         * we know we read them in from the kernel.
                         * As such we can safely remove them.
                         */
                        if (zrouter.startup_time < re->uptime)
                                continue;

                        /*
                         * So we are starting up and have received
                         * routes from the kernel that we have installed
                         * from a previous run of zebra but not cleaned
                         * up ( say a kill -9 )
                         * But since we haven't actually installed
                         * them yet( we received them from the kernel )
                         * we don't think they are active.
                         * So let's pretend they are active to actually
                         * remove them.
                         * In all honesty I'm not sure if we should
                         * mark them as active when we receive them
                         * This is startup only so probably ok.
                         *
                         * If we ever decide to move rib_sweep_table
                         * to a different spot (ie startup )
                         * this decision needs to be revisited
                         */
                        SET_FLAG(re->status, ROUTE_ENTRY_INSTALLED);
                        for (ALL_NEXTHOPS_PTR(re->ng, nexthop))
                                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);

                        rib_uninstall_kernel(rn, re);
                        rib_delnode(rn, re);
                }
        }
}

/* Sweep all RIB tables.  */
int rib_sweep_route(struct thread *t)
{
        struct vrf *vrf;
        struct zebra_vrf *zvrf;

        RB_FOREACH (vrf, vrf_id_head, &vrfs_by_id) {
                if ((zvrf = vrf->info) == NULL)
                        continue;

                rib_sweep_table(zvrf->table[AFI_IP][SAFI_UNICAST]);
                rib_sweep_table(zvrf->table[AFI_IP6][SAFI_UNICAST]);
        }

        zebra_router_sweep_route();
        zebra_router_sweep_nhgs();

        return 0;
}

/* Remove specific by protocol routes from 'table'. */
unsigned long rib_score_proto_table(uint8_t proto, unsigned short instance,
                                    struct route_table *table)
{
        struct route_node *rn;
        struct route_entry *re;
        struct route_entry *next;
        unsigned long n = 0;

        if (table)
                for (rn = route_top(table); rn; rn = srcdest_route_next(rn))
                        RNODE_FOREACH_RE_SAFE (rn, re, next) {
                                if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
                                        continue;
                                if (re->type == proto
                                    && re->instance == instance) {
                                        rib_delnode(rn, re);
                                        n++;
                                }
                        }
        return n;
}

/* Remove specific by protocol routes. */
unsigned long rib_score_proto(uint8_t proto, unsigned short instance)
{
        struct vrf *vrf;
        struct zebra_vrf *zvrf;
        struct other_route_table *ort;
        unsigned long cnt = 0;

        RB_FOREACH (vrf, vrf_id_head, &vrfs_by_id) {
                zvrf = vrf->info;
                if (!zvrf)
                        continue;

                cnt += rib_score_proto_table(proto, instance,
                                             zvrf->table[AFI_IP][SAFI_UNICAST])
                       + rib_score_proto_table(
                               proto, instance,
                               zvrf->table[AFI_IP6][SAFI_UNICAST]);

                frr_each(otable, &zvrf->other_tables, ort) cnt +=
                        rib_score_proto_table(proto, instance, ort->table);
        }

        return cnt;
}

/* Close RIB and clean up kernel routes. */
void rib_close_table(struct route_table *table)
{
        struct route_node *rn;
        rib_table_info_t *info;
        rib_dest_t *dest;

        if (!table)
                return;

        info = route_table_get_info(table);

        for (rn = route_top(table); rn; rn = srcdest_route_next(rn)) {
                dest = rib_dest_from_rnode(rn);

                if (dest && dest->selected_fib) {
                        if (info->safi == SAFI_UNICAST)
                                hook_call(rib_update, rn, NULL);

                        rib_uninstall_kernel(rn, dest->selected_fib);
                        dest->selected_fib = NULL;
                }
        }
}

/*
 * Handler for async dataplane results after a pseudowire installation
 */
static int handle_pw_result(struct zebra_dplane_ctx *ctx)
{
        struct zebra_pw *pw;
        struct zebra_vrf *vrf;

        /* The pseudowire code assumes success - we act on an error
         * result for installation attempts here.
         */
        if (dplane_ctx_get_op(ctx) != DPLANE_OP_PW_INSTALL)
                goto done;

        if (dplane_ctx_get_status(ctx) != ZEBRA_DPLANE_REQUEST_SUCCESS) {
                vrf = zebra_vrf_lookup_by_id(dplane_ctx_get_vrf(ctx));
                pw = zebra_pw_find(vrf, dplane_ctx_get_ifname(ctx));
                if (pw)
                        zebra_pw_install_failure(pw);
        }

done:

        return 0;
}


/*
 * Handle results from the dataplane system. Dequeue update context
 * structs, dispatch to appropriate internal handlers.
 */
static int rib_process_dplane_results(struct thread *thread)
{
        struct zebra_dplane_ctx *ctx;
        struct dplane_ctx_q ctxlist;
        bool shut_p = false;

        /* Dequeue a list of completed updates with one lock/unlock cycle */

        do {
                TAILQ_INIT(&ctxlist);

                /* Take lock controlling queue of results */
                frr_with_mutex(&dplane_mutex) {
                        /* Dequeue list of context structs */
                        dplane_ctx_list_append(&ctxlist, &rib_dplane_q);
                }

                /* Dequeue context block */
                ctx = dplane_ctx_dequeue(&ctxlist);

                /* If we've emptied the results queue, we're done */
                if (ctx == NULL)
                        break;

                /* If zebra is shutting down, avoid processing results,
                 * just drain the results queue.
                 */
                shut_p = atomic_load_explicit(&zrouter.in_shutdown,
                                              memory_order_relaxed);
                if (shut_p) {
                        while (ctx) {
                                dplane_ctx_fini(&ctx);

                                ctx = dplane_ctx_dequeue(&ctxlist);
                        }

                        continue;
                }

                while (ctx) {
                        switch (dplane_ctx_get_op(ctx)) {
                        case DPLANE_OP_ROUTE_INSTALL:
                        case DPLANE_OP_ROUTE_UPDATE:
                        case DPLANE_OP_ROUTE_DELETE:
                        {
                                /* Bit of special case for route updates
                                 * that were generated by async notifications:
                                 * we don't want to continue processing these
                                 * in the rib.
                                 */
                                if (dplane_ctx_get_notif_provider(ctx) == 0)
                                        rib_process_result(ctx);
                                else
                                        dplane_ctx_fini(&ctx);
                        }
                        break;

                        case DPLANE_OP_ROUTE_NOTIFY:
                                rib_process_dplane_notify(ctx);
                                break;

                        case DPLANE_OP_NH_INSTALL:
                        case DPLANE_OP_NH_UPDATE:
                        case DPLANE_OP_NH_DELETE:
                                zebra_nhg_dplane_result(ctx);
                                break;

                        case DPLANE_OP_LSP_INSTALL:
                        case DPLANE_OP_LSP_UPDATE:
                        case DPLANE_OP_LSP_DELETE:
                        {
                                /* Bit of special case for LSP updates
                                 * that were generated by async notifications:
                                 * we don't want to continue processing these.
                                 */
                                if (dplane_ctx_get_notif_provider(ctx) == 0)
                                        zebra_mpls_lsp_dplane_result(ctx);
                                else
                                        dplane_ctx_fini(&ctx);
                        }
                        break;

                        case DPLANE_OP_LSP_NOTIFY:
                                zebra_mpls_process_dplane_notify(ctx);
                                break;

                        case DPLANE_OP_PW_INSTALL:
                        case DPLANE_OP_PW_UNINSTALL:
                                handle_pw_result(ctx);
                                break;

                        case DPLANE_OP_SYS_ROUTE_ADD:
                        case DPLANE_OP_SYS_ROUTE_DELETE:
                                /* No further processing in zebra for these. */
                                dplane_ctx_fini(&ctx);
                                break;

                        case DPLANE_OP_MAC_INSTALL:
                        case DPLANE_OP_MAC_DELETE:
                                zebra_vxlan_handle_result(ctx);
                                break;

                        /* Some op codes not handled here */
                        case DPLANE_OP_ADDR_INSTALL:
                        case DPLANE_OP_ADDR_UNINSTALL:
                        case DPLANE_OP_NEIGH_INSTALL:
                        case DPLANE_OP_NEIGH_UPDATE:
                        case DPLANE_OP_NEIGH_DELETE:
                        case DPLANE_OP_VTEP_ADD:
                        case DPLANE_OP_VTEP_DELETE:
                        case DPLANE_OP_NONE:
                                /* Don't expect this: just return the struct? */
                                dplane_ctx_fini(&ctx);
                                break;

                        } /* Dispatch by op code */

                        ctx = dplane_ctx_dequeue(&ctxlist);
                }

        } while (1);

        return 0;
}

/*
 * Results are returned from the dataplane subsystem, in the context of
 * the dataplane pthread. We enqueue the results here for processing by
 * the main thread later.
 */
static int rib_dplane_results(struct dplane_ctx_q *ctxlist)
{
        /* Take lock controlling queue of results */
        frr_with_mutex(&dplane_mutex) {
                /* Enqueue context blocks */
                dplane_ctx_list_append(&rib_dplane_q, ctxlist);
        }

        /* Ensure event is signalled to zebra main pthread */
        thread_add_event(zrouter.master, rib_process_dplane_results, NULL, 0,
                         &t_dplane);

        return 0;
}

/*
 * Ensure there are no empty slots in the route_info array.
 * Every route type in zebra should be present there.
 */
static void check_route_info(void)
{
        int len = array_size(route_info);

        /*
         * ZEBRA_ROUTE_SYSTEM is special cased since
         * its key is 0 anyway.
         *
         * ZEBRA_ROUTE_ALL is also ignored.
         */
        for (int i = 0; i < len; i++) {
                if (i == ZEBRA_ROUTE_SYSTEM || i == ZEBRA_ROUTE_ALL)
                        continue;
                assert(route_info[i].key);
                assert(route_info[i].meta_q_map < MQ_SIZE);
        }
}

/* Routing information base initialize. */
void rib_init(void)
{
        check_route_info();

        rib_queue_init();

        /* Init dataplane, and register for results */
        pthread_mutex_init(&dplane_mutex, NULL);
        TAILQ_INIT(&rib_dplane_q);
        zebra_dplane_init(rib_dplane_results);
}

/*
 * vrf_id_get_next
 *
 * Get the first vrf id that is greater than the given vrf id if any.
 *
 * Returns true if a vrf id was found, false otherwise.
 */
static inline int vrf_id_get_next(vrf_id_t vrf_id, vrf_id_t *next_id_p)
{
        struct vrf *vrf;

        vrf = vrf_lookup_by_id(vrf_id);
        if (vrf) {
                vrf = RB_NEXT(vrf_id_head, vrf);
                if (vrf) {
                        *next_id_p = vrf->vrf_id;
                        return 1;
                }
        }

        return 0;
}

/*
 * rib_tables_iter_next
 *
 * Returns the next table in the iteration.
 */
struct route_table *rib_tables_iter_next(rib_tables_iter_t *iter)
{
        struct route_table *table;

        /*
         * Array that helps us go over all AFI/SAFI combinations via one
         * index.
         */
        static struct {
                afi_t afi;
                safi_t safi;
        } afi_safis[] = {
                {AFI_IP, SAFI_UNICAST},         {AFI_IP, SAFI_MULTICAST},
                {AFI_IP, SAFI_LABELED_UNICAST}, {AFI_IP6, SAFI_UNICAST},
                {AFI_IP6, SAFI_MULTICAST},      {AFI_IP6, SAFI_LABELED_UNICAST},
        };

        table = NULL;

        switch (iter->state) {

        case RIB_TABLES_ITER_S_INIT:
                iter->vrf_id = VRF_DEFAULT;
                iter->afi_safi_ix = -1;

        /* Fall through */

        case RIB_TABLES_ITER_S_ITERATING:
                iter->afi_safi_ix++;
                while (1) {

                        while (iter->afi_safi_ix
                               < (int)array_size(afi_safis)) {
                                table = zebra_vrf_table(
                                        afi_safis[iter->afi_safi_ix].afi,
                                        afi_safis[iter->afi_safi_ix].safi,
                                        iter->vrf_id);
                                if (table)
                                        break;

                                iter->afi_safi_ix++;
                        }

                        /*
                         * Found another table in this vrf.
                         */
                        if (table)
                                break;

                        /*
                         * Done with all tables in the current vrf, go to the
                         * next
                         * one.
                         */
                        if (!vrf_id_get_next(iter->vrf_id, &iter->vrf_id))
                                break;

                        iter->afi_safi_ix = 0;
                }

                break;

        case RIB_TABLES_ITER_S_DONE:
                return NULL;
        }

        if (table)
                iter->state = RIB_TABLES_ITER_S_ITERATING;
        else
                iter->state = RIB_TABLES_ITER_S_DONE;

        return table;
}