Merge pull request #3477 from donaldsharp/multipath_respect

[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 "log_int.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 "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"

/*
 * 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;
        int distance;
} route_info[ZEBRA_ROUTE_MAX] = {
                [ZEBRA_ROUTE_SYSTEM] = {ZEBRA_ROUTE_SYSTEM, 0},
                [ZEBRA_ROUTE_KERNEL] = {ZEBRA_ROUTE_KERNEL, 0},
                [ZEBRA_ROUTE_CONNECT] = {ZEBRA_ROUTE_CONNECT, 0},
                [ZEBRA_ROUTE_STATIC] = {ZEBRA_ROUTE_STATIC, 1},
                [ZEBRA_ROUTE_RIP] = {ZEBRA_ROUTE_RIP, 120},
                [ZEBRA_ROUTE_RIPNG] = {ZEBRA_ROUTE_RIPNG, 120},
                [ZEBRA_ROUTE_OSPF] = {ZEBRA_ROUTE_OSPF, 110},
                [ZEBRA_ROUTE_OSPF6] = {ZEBRA_ROUTE_OSPF6, 110},
                [ZEBRA_ROUTE_ISIS] = {ZEBRA_ROUTE_ISIS, 115},
                [ZEBRA_ROUTE_BGP] = {ZEBRA_ROUTE_BGP, 20 /* IBGP is 200. */},
                [ZEBRA_ROUTE_PIM] = {ZEBRA_ROUTE_PIM, 255},
                [ZEBRA_ROUTE_EIGRP] = {ZEBRA_ROUTE_EIGRP, 90},
                [ZEBRA_ROUTE_NHRP] = {ZEBRA_ROUTE_NHRP, 10},
                [ZEBRA_ROUTE_HSLS] = {ZEBRA_ROUTE_HSLS, 255},
                [ZEBRA_ROUTE_OLSR] = {ZEBRA_ROUTE_OLSR, 255},
                [ZEBRA_ROUTE_TABLE] = {ZEBRA_ROUTE_TABLE, 150},
                [ZEBRA_ROUTE_LDP] = {ZEBRA_ROUTE_LDP, 150},
                [ZEBRA_ROUTE_VNC] = {ZEBRA_ROUTE_VNC, 20},
                [ZEBRA_ROUTE_VNC_DIRECT] = {ZEBRA_ROUTE_VNC_DIRECT, 20},
                [ZEBRA_ROUTE_VNC_DIRECT_RH] = {ZEBRA_ROUTE_VNC_DIRECT_RH, 20},
                [ZEBRA_ROUTE_BGP_DIRECT] = {ZEBRA_ROUTE_BGP_DIRECT, 20},
                [ZEBRA_ROUTE_BGP_DIRECT_EXT] = {ZEBRA_ROUTE_BGP_DIRECT_EXT, 20},
                [ZEBRA_ROUTE_BABEL] = {ZEBRA_ROUTE_BABEL, 100},
                [ZEBRA_ROUTE_SHARP] = {ZEBRA_ROUTE_SHARP, 150},

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

/* RPF lookup behaviour */
static enum multicast_mode ipv4_multicast_mode = MCAST_NO_CONFIG;


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)
                        strcat(buf, " (MRIB)");
        } 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)
            || (table_id == zebrad.rtm_table_default))
                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_add(&re->ng.nexthop, nexthop);
        re->nexthop_num++;
}


/**
 * 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);
        for (struct nexthop *nexthop = nh; nexthop; nexthop = nexthop->next)
                re->nexthop_num++;
}

/* 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;
        re->nexthop_num--;
}


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)
                    || CHECK_FLAG(re->flags, ZEBRA_FLAG_EVPN_ROUTE)
                    || CHECK_FLAG(re->flags, ZEBRA_FLAG_ONLINK)) {
                        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;
        if (CHECK_FLAG(re->flags, ZEBRA_FLAG_EVPN_ROUTE)
            || CHECK_FLAG(re->flags, ZEBRA_FLAG_ONLINK)) {
                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK);
        }

        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;
}

static void nexthop_set_resolved(afi_t afi, const struct nexthop *newhop,
                                 struct nexthop *nexthop)
{
        struct nexthop *resolved_hop;

        resolved_hop = nexthop_new();
        SET_FLAG(resolved_hop->flags, NEXTHOP_FLAG_ACTIVE);

        resolved_hop->vrf_id = nexthop->vrf_id;
        switch (newhop->type) {
        case NEXTHOP_TYPE_IPV4:
        case NEXTHOP_TYPE_IPV4_IFINDEX:
                /* If the resolving route specifies a gateway, use it */
                resolved_hop->type = newhop->type;
                resolved_hop->gate.ipv4 = newhop->gate.ipv4;

                if (newhop->ifindex) {
                        resolved_hop->type = NEXTHOP_TYPE_IPV4_IFINDEX;
                        resolved_hop->ifindex = newhop->ifindex;
                }
                break;
        case NEXTHOP_TYPE_IPV6:
        case NEXTHOP_TYPE_IPV6_IFINDEX:
                resolved_hop->type = newhop->type;
                resolved_hop->gate.ipv6 = newhop->gate.ipv6;

                if (newhop->ifindex) {
                        resolved_hop->type = NEXTHOP_TYPE_IPV6_IFINDEX;
                        resolved_hop->ifindex = newhop->ifindex;
                }
                break;
        case NEXTHOP_TYPE_IFINDEX:
                /* If the resolving route is an interface route,
                 * it means the gateway we are looking up is connected
                 * to that interface. (The actual network is _not_ onlink).
                 * Therefore, the resolved route should have the original
                 * gateway as nexthop as it is directly connected.
                 *
                 * On Linux, we have to set the onlink netlink flag because
                 * otherwise, the kernel won't accept the route.
                 */
                resolved_hop->flags |= NEXTHOP_FLAG_ONLINK;
                if (afi == AFI_IP) {
                        resolved_hop->type = NEXTHOP_TYPE_IPV4_IFINDEX;
                        resolved_hop->gate.ipv4 = nexthop->gate.ipv4;
                } else if (afi == AFI_IP6) {
                        resolved_hop->type = NEXTHOP_TYPE_IPV6_IFINDEX;
                        resolved_hop->gate.ipv6 = nexthop->gate.ipv6;
                }
                resolved_hop->ifindex = newhop->ifindex;
                break;
        case NEXTHOP_TYPE_BLACKHOLE:
                resolved_hop->type = NEXTHOP_TYPE_BLACKHOLE;
                resolved_hop->bh_type = nexthop->bh_type;
                break;
        }

        if (newhop->flags & NEXTHOP_FLAG_ONLINK)
                resolved_hop->flags |= NEXTHOP_FLAG_ONLINK;

        /* Copy labels of the resolved route */
        if (newhop->nh_label)
                nexthop_add_labels(resolved_hop, newhop->nh_label_type,
                                   newhop->nh_label->num_labels,
                                   &newhop->nh_label->label[0]);

        resolved_hop->rparent = nexthop;
        nexthop_add(&nexthop->resolved, resolved_hop);
}

/* If force flag is not set, do not modify falgs at all for uninstall
   the route from FIB. */
static int nexthop_active(afi_t afi, struct route_entry *re,
                          struct nexthop *nexthop, bool set,
                          struct route_node *top)
{
        struct prefix p;
        struct route_table *table;
        struct route_node *rn;
        struct route_entry *match = NULL;
        int resolved;
        struct nexthop *newhop;
        struct interface *ifp;
        rib_dest_t *dest;

        if ((nexthop->type == NEXTHOP_TYPE_IPV4)
            || nexthop->type == NEXTHOP_TYPE_IPV6)
                nexthop->ifindex = 0;

        if (set) {
                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE);
                nexthops_free(nexthop->resolved);
                nexthop->resolved = NULL;
                re->nexthop_mtu = 0;
        }

        /* Next hops (remote VTEPs) for EVPN routes are fully resolved. */
        if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_EVPN_RVTEP))
                return 1;

        /* Skip nexthops that have been filtered out due to route-map */
        /* The nexthops are specific to this route and so the same */
        /* nexthop for a different route may not have this flag set */
        if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FILTERED)) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug("\t%s: Nexthop Filtered",
                                   __PRETTY_FUNCTION__);
                return 0;
        }

        /*
         * Check to see if we should trust the passed in information
         * for UNNUMBERED interfaces as that we won't find the GW
         * address in the routing table.
         */
        if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK)) {
                ifp = if_lookup_by_index(nexthop->ifindex, nexthop->vrf_id);
                if ((ifp && connected_is_unnumbered(ifp))
                    || CHECK_FLAG(re->flags, ZEBRA_FLAG_ONLINK)) {
                        if (if_is_operative(ifp))
                                return 1;
                        else {
                                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                                        zlog_debug(
                                                "\t%s: Onlink and interface %s is not operative",
                                                __PRETTY_FUNCTION__, ifp->name);
                                return 0;
                        }
                } else {
                        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                                zlog_debug(
                                        "\t%s: Interface %s is not unnumbered",
                                        __PRETTY_FUNCTION__,
                                        ifp ? ifp->name : "Unknown");
                        return 0;
                }
        }

        /* Make lookup prefix. */
        memset(&p, 0, sizeof(struct prefix));
        switch (afi) {
        case AFI_IP:
                p.family = AF_INET;
                p.prefixlen = IPV4_MAX_PREFIXLEN;
                p.u.prefix4 = nexthop->gate.ipv4;
                break;
        case AFI_IP6:
                p.family = AF_INET6;
                p.prefixlen = IPV6_MAX_PREFIXLEN;
                p.u.prefix6 = nexthop->gate.ipv6;
                break;
        default:
                assert(afi != AFI_IP && afi != AFI_IP6);
                break;
        }
        /* Lookup table.  */
        table = zebra_vrf_table(afi, SAFI_UNICAST, nexthop->vrf_id);
        if (!table) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug("\t%s: Table not found",
                                   __PRETTY_FUNCTION__);
                return 0;
        }

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

                /* Lookup should halt if we've matched against ourselves ('top',
                 * if specified) - i.e., we cannot have a nexthop NH1 is
                 * resolved by a route NH1. The exception is if the route is a
                 * host route.
                 */
                if (top && rn == top)
                        if (((afi == AFI_IP) && (rn->p.prefixlen != 32))
                            || ((afi == AFI_IP6) && (rn->p.prefixlen != 128))) {
                                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                                        zlog_debug(
                                                "\t%s: Matched against ourself and prefix length is not max bit length",
                                                __PRETTY_FUNCTION__);
                                return 0;
                        }

                /* Pick up selected route. */
                /* However, do not resolve over default route unless explicitly
                 * allowed. */
                if (is_default_prefix(&rn->p)
                    && !rnh_resolve_via_default(p.family)) {
                        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                                zlog_debug(
                                        "\t:%s: Resolved against default route",
                                        __PRETTY_FUNCTION__);
                        return 0;
                }

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

                        continue;
                }

                if (match->type == ZEBRA_ROUTE_CONNECT) {
                        /* Directly point connected route. */
                        newhop = match->ng.nexthop;
                        if (newhop) {
                                if (nexthop->type == NEXTHOP_TYPE_IPV4
                                    || nexthop->type == NEXTHOP_TYPE_IPV6)
                                        nexthop->ifindex = newhop->ifindex;
                        }
                        return 1;
                } else if (CHECK_FLAG(re->flags, ZEBRA_FLAG_ALLOW_RECURSION)) {
                        resolved = 0;
                        for (ALL_NEXTHOPS(match->ng, newhop)) {
                                if (!CHECK_FLAG(newhop->flags,
                                                NEXTHOP_FLAG_FIB))
                                        continue;
                                if (CHECK_FLAG(newhop->flags,
                                               NEXTHOP_FLAG_RECURSIVE))
                                        continue;

                                if (set) {
                                        SET_FLAG(nexthop->flags,
                                                 NEXTHOP_FLAG_RECURSIVE);
                                        SET_FLAG(re->status,
                                                 ROUTE_ENTRY_NEXTHOPS_CHANGED);
                                        nexthop_set_resolved(afi, newhop,
                                                             nexthop);
                                }
                                resolved = 1;
                        }
                        if (resolved && set)
                                re->nexthop_mtu = match->mtu;
                        if (!resolved && IS_ZEBRA_DEBUG_RIB_DETAILED)
                                zlog_debug("\t%s: Recursion failed to find",
                                           __PRETTY_FUNCTION__);
                        return resolved;
                } else if (re->type == ZEBRA_ROUTE_STATIC) {
                        resolved = 0;
                        for (ALL_NEXTHOPS(match->ng, newhop)) {
                                if (!CHECK_FLAG(newhop->flags,
                                                NEXTHOP_FLAG_FIB))
                                        continue;

                                if (set) {
                                        SET_FLAG(nexthop->flags,
                                                 NEXTHOP_FLAG_RECURSIVE);
                                        nexthop_set_resolved(afi, newhop,
                                                             nexthop);
                                }
                                resolved = 1;
                        }
                        if (resolved && set)
                                re->nexthop_mtu = match->mtu;

                        if (!resolved && IS_ZEBRA_DEBUG_RIB_DETAILED)
                                zlog_debug(
                                        "\t%s: Static route unable to resolve",
                                        __PRETTY_FUNCTION__);
                        return resolved;
                } else {
                        if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
                                zlog_debug("\t%s: Route Type %s has not turned on recursion",
                                           __PRETTY_FUNCTION__,
                                           zebra_route_string(re->type));
                                if (re->type == ZEBRA_ROUTE_BGP &&
                                    !CHECK_FLAG(re->flags, ZEBRA_FLAG_IBGP))
                                        zlog_debug("\tEBGP: see \"disable-ebgp-connected-route-check\" or \"disable-connected-check\"");
                        }
                        return 0;
                }
        }
        if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                zlog_debug("\t%s: Nexthop did not lookup in table",
                           __PRETTY_FUNCTION__);
        return 0;
}

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;
        struct nexthop *newhop;

        /* 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) {
                                int found = 0;
                                for (ALL_NEXTHOPS(match->ng, newhop))
                                        if (CHECK_FLAG(newhop->flags,
                                                       NEXTHOP_FLAG_FIB)) {
                                                found = 1;
                                                break;
                                        }
                                if (!found)
                                        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 (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;
}

void multicast_mode_ipv4_set(enum multicast_mode mode)
{
        if (IS_ZEBRA_DEBUG_RIB)
                zlog_debug("%s: multicast lookup mode set (%d)", __func__,
                           mode);
        ipv4_multicast_mode = mode;
}

enum multicast_mode multicast_mode_ipv4_get(void)
{
        return ipv4_multicast_mode;
}

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;
        struct nexthop *nexthop;
        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;

        for (ALL_NEXTHOPS(match->ng, nexthop))
                if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB))
                        return match;

        return NULL;
}

#define RIB_SYSTEM_ROUTE(R)                                                    \
        ((R)->type == ZEBRA_ROUTE_KERNEL || (R)->type == ZEBRA_ROUTE_CONNECT)

#define RIB_KERNEL_ROUTE(R)                                             \
        ((R)->type == ZEBRA_ROUTE_KERNEL)

/* This function verifies reachability of one given nexthop, which can be
 * numbered or unnumbered, IPv4 or IPv6. The result is unconditionally stored
 * in nexthop->flags field. If the 4th parameter, 'set', is non-zero,
 * nexthop->ifindex will be updated appropriately as well.
 * An existing route map can turn (otherwise active) nexthop into inactive, but
 * not vice versa.
 *
 * The return value is the final value of 'ACTIVE' flag.
 */

static unsigned nexthop_active_check(struct route_node *rn,
                                     struct route_entry *re,
                                     struct nexthop *nexthop, bool set)
{
        struct interface *ifp;
        route_map_result_t ret = RMAP_MATCH;
        int family;
        char buf[SRCDEST2STR_BUFFER];
        const struct prefix *p, *src_p;
        struct zebra_vrf *zvrf;

        srcdest_rnode_prefixes(rn, &p, &src_p);

        if (rn->p.family == AF_INET)
                family = AFI_IP;
        else if (rn->p.family == AF_INET6)
                family = AFI_IP6;
        else
                family = 0;
        switch (nexthop->type) {
        case NEXTHOP_TYPE_IFINDEX:
                ifp = if_lookup_by_index(nexthop->ifindex, nexthop->vrf_id);
                if (ifp && if_is_operative(ifp))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                else
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                break;
        case NEXTHOP_TYPE_IPV4:
        case NEXTHOP_TYPE_IPV4_IFINDEX:
                family = AFI_IP;
                if (nexthop_active(AFI_IP, re, nexthop, set, rn))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                else
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                break;
        case NEXTHOP_TYPE_IPV6:
                family = AFI_IP6;
                if (nexthop_active(AFI_IP6, re, nexthop, set, rn))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                else
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                break;
        case NEXTHOP_TYPE_IPV6_IFINDEX:
                /* RFC 5549, v4 prefix with v6 NH */
                if (rn->p.family != AF_INET)
                        family = AFI_IP6;
                if (IN6_IS_ADDR_LINKLOCAL(&nexthop->gate.ipv6)) {
                        ifp = if_lookup_by_index(nexthop->ifindex,
                                                 nexthop->vrf_id);
                        if (ifp && if_is_operative(ifp))
                                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                        else
                                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                } else {
                        if (nexthop_active(AFI_IP6, re, nexthop, set, rn))
                                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                        else
                                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                }
                break;
        case NEXTHOP_TYPE_BLACKHOLE:
                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                break;
        default:
                break;
        }
        if (!CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE)) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug("\t%s: Unable to find a active nexthop",
                                   __PRETTY_FUNCTION__);
                return 0;
        }

        /* XXX: What exactly do those checks do? Do we support
         * e.g. IPv4 routes with IPv6 nexthops or vice versa?
         */
        if (RIB_SYSTEM_ROUTE(re) || (family == AFI_IP && p->family != AF_INET)
            || (family == AFI_IP6 && p->family != AF_INET6))
                return CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);

        /* The original code didn't determine the family correctly
         * e.g. for NEXTHOP_TYPE_IFINDEX. Retrieve the correct afi
         * from the rib_table_info in those cases.
         * Possibly it may be better to use only the rib_table_info
         * in every case.
         */
        if (!family) {
                rib_table_info_t *info;

                info = srcdest_rnode_table_info(rn);
                family = info->afi;
        }

        memset(&nexthop->rmap_src.ipv6, 0, sizeof(union g_addr));

        zvrf = zebra_vrf_lookup_by_id(nexthop->vrf_id);
        if (!zvrf) {
                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        zlog_debug("\t%s: zvrf is NULL", __PRETTY_FUNCTION__);
                return CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
        }

        /* It'll get set if required inside */
        ret = zebra_route_map_check(family, re->type, re->instance, p,
                                    nexthop, zvrf, re->tag);
        if (ret == RMAP_DENYMATCH) {
                if (IS_ZEBRA_DEBUG_RIB) {
                        srcdest_rnode2str(rn, buf, sizeof(buf));
                        zlog_debug(
                                "%u:%s: Filtering out with NH out %s due to route map",
                                re->vrf_id, buf,
                                ifindex2ifname(nexthop->ifindex,
                                               nexthop->vrf_id));
                }
                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
        }
        return CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
}

/* Iterate over all nexthops of the given RIB entry and refresh their
 * ACTIVE flag. re->nexthop_active_num is updated accordingly. If any
 * nexthop is found to toggle the ACTIVE flag, the whole re structure
 * is flagged with ROUTE_ENTRY_CHANGED. The 4th 'set' argument is
 * transparently passed to nexthop_active_check().
 *
 * Return value is the new number of active nexthops.
 */

static int nexthop_active_update(struct route_node *rn, struct route_entry *re,
                                 bool set)
{
        struct nexthop *nexthop;
        union g_addr prev_src;
        unsigned int prev_active, new_active, old_num_nh;
        ifindex_t prev_index;

        old_num_nh = re->nexthop_active_num;

        re->nexthop_active_num = 0;
        UNSET_FLAG(re->status, ROUTE_ENTRY_CHANGED);

        for (nexthop = re->ng.nexthop; nexthop; nexthop = nexthop->next) {
                /* No protocol daemon provides src and so we're skipping
                 * tracking it */
                prev_src = nexthop->rmap_src;
                prev_active = CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                prev_index = nexthop->ifindex;
                /*
                 * We need to respect the multipath_num here
                 * as that what we should be able to install from
                 * a multipath perpsective should not be a data plane
                 * decision point.
                 */
                new_active = nexthop_active_check(rn, re, nexthop, set);
                if (new_active && re->nexthop_active_num >= multipath_num) {
                        UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
                        new_active = 0;
                }
                if (new_active)
                        re->nexthop_active_num++;
                /* Don't allow src setting on IPv6 addr for now */
                if (prev_active != new_active || prev_index != nexthop->ifindex
                    || ((nexthop->type >= NEXTHOP_TYPE_IFINDEX
                         && nexthop->type < NEXTHOP_TYPE_IPV6)
                        && prev_src.ipv4.s_addr
                                   != nexthop->rmap_src.ipv4.s_addr)
                    || ((nexthop->type >= NEXTHOP_TYPE_IPV6
                         && nexthop->type < NEXTHOP_TYPE_BLACKHOLE)
                        && !(IPV6_ADDR_SAME(&prev_src.ipv6,
                                            &nexthop->rmap_src.ipv6)))) {
                        SET_FLAG(re->status, ROUTE_ENTRY_CHANGED);
                        SET_FLAG(re->status, ROUTE_ENTRY_NEXTHOPS_CHANGED);
                }
        }

        if (old_num_nh != re->nexthop_active_num)
                SET_FLAG(re->status, ROUTE_ENTRY_CHANGED);

        if (CHECK_FLAG(re->status, ROUTE_ENTRY_CHANGED)) {
                SET_FLAG(re->status, ROUTE_ENTRY_NEXTHOPS_CHANGED);
        }

        return re->nexthop_active_num;
}

/*
 * 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(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(re->ng, nexthop))
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                return;
        } else {
                struct nexthop *prev;

                for (ALL_NEXTHOPS(re->ng, nexthop)) {
                        UNSET_FLAG (nexthop->flags, NEXTHOP_FLAG_DUPLICATE);
                        for (ALL_NEXTHOPS(re->ng, prev)) {
                                if (prev == nexthop)
                                        break;
                                if (nexthop_same_firsthop(nexthop, prev)) {
                                        SET_FLAG(nexthop->flags,
                                                 NEXTHOP_FLAG_DUPLICATE);
                                        break;
                                }
                        }
                }
        }

        /*
         * 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 && (old != re))
                ret = dplane_route_update(rn, re, old);
        else
                ret = dplane_route_add(rn, re);

        switch (ret) {
        case ZEBRA_DPLANE_REQUEST_QUEUED:
                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) {
                for (ALL_NEXTHOPS(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);

                if (!RIB_SYSTEM_ROUTE(re))
                        rib_uninstall_kernel(rn, re);

                dest->selected_fib = NULL;

                for (ALL_NEXTHOPS(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);
                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 (dest->routes) {
                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;
}

/*
 * 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");
        }

        dest->rnode = NULL;
        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)
{
        rib_dest_t *dest = rib_dest_from_rnode(rn);

        hook_call(rib_update, rn, "new route selected");

        /* Update real nexthop. This may actually determine if nexthop is active
         * or not. */
        if (!nexthop_active_update(rn, new, true)) {
                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 (type %d)",
                           zvrf_id(zvrf), buf, rn, new, new->type);
        }

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

        if (!RIB_SYSTEM_ROUTE(new))
                rib_install_kernel(rn, new, NULL);
        else
                dest->selected_fib = new;

        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)
{
        rib_dest_t *dest = rib_dest_from_rnode(rn);
        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 (type %d)",
                           zvrf_id(zvrf), buf, rn, old, old->type);
        }

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

        if (!RIB_SYSTEM_ROUTE(old))
                rib_uninstall_kernel(rn, old);
        else {
                /*
                 * We are setting this to NULL here
                 * because that is what we traditionally
                 * have been doing.  I am not positive
                 * that this is the right thing to do
                 * but let's leave the code alone
                 * for the RIB_SYSTEM_ROUTE case
                 */
                dest->selected_fib = NULL;
        }

        /* 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 (!nexthop_active_update(rn, old, true) &&
            (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)
{
        struct nexthop *nexthop = NULL;
        int nh_active = 0;
        rib_dest_t *dest = rib_dest_from_rnode(rn);

        /*
         * 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_active_update(rn, new, true))
                        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 (type %d) "
                                                "old %p (type %d)",
                                                zvrf_id(zvrf), buf, rn, new,
                                                new->type, old, old->type);
                                else
                                        zlog_debug(
                                                "%u:%s: Updating route rn %p, re %p (type %d)",
                                                zvrf_id(zvrf), buf, rn, new,
                                                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 (!RIB_SYSTEM_ROUTE(new)) {
                                /* 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);
                        } else {
                                /*
                                 * We do not need to install the
                                 * selected route because it
                                 * is already isntalled by
                                 * the system( ie not us )
                                 * so just mark it as winning
                                 * we do need to ensure that
                                 * if we uninstall a route
                                 * from ourselves we don't
                                 * over write this pointer
                                 */
                                dest->selected_fib = NULL;
                        }
                        /* If install succeeded or system route, cleanup flags
                         * for prior route. */
                        if (new != old) {
                                if (RIB_SYSTEM_ROUTE(new)) {
                                        if (!RIB_SYSTEM_ROUTE(old))
                                                rib_uninstall_kernel(rn, old);
                                } else {
                                        for (nexthop = old->ng.nexthop; nexthop;
                                             nexthop = nexthop->next)
                                                UNSET_FLAG(nexthop->flags,
                                                           NEXTHOP_FLAG_FIB);
                                }
                        }
                }

                /*
                 * 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 (type %d) "
                                                "old %p (type %d) - nexthop inactive",
                                                zvrf_id(zvrf), buf, rn, new,
                                                new->type, old, old->type);
                                else
                                        zlog_debug(
                                                "%u:%s: Deleting route rn %p, re %p (type %d) - nexthop inactive",
                                                zvrf_id(zvrf), buf, rn, new,
                                                new->type);
                        }

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

                        if (!RIB_SYSTEM_ROUTE(old))
                                rib_uninstall_kernel(rn, old);
                        else
                                dest->selected_fib = NULL;
                }
        } 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 (!RIB_SYSTEM_ROUTE(new)) {
                        bool in_fib = false;

                        for (ALL_NEXTHOPS(new->ng, nexthop))
                                if (CHECK_FLAG(nexthop->flags,
                                               NEXTHOP_FLAG_FIB)) {
                                        in_fib = true;
                                        break;
                                }
                        if (!in_fib)
                                rib_install_kernel(rn, new, NULL);
                }
        }

        /* Update prior route. */
        if (new != old) {
                /* Set real nexthop. */
                nexthop_active_update(rn, old, true);
                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(alternate->ng, nexthop)) {
                        if (if_is_loopback_or_vrf(if_lookup_by_index(
                                    nexthop->ifindex, alternate->vrf_id)))
                                return alternate;
                }

                for (ALL_NEXTHOPS(current->ng, nexthop)) {
                        if (if_is_loopback_or_vrf(if_lookup_by_index(
                                    nexthop->ifindex, current->vrf_id)))
                                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 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 (type %d) status %x flags %x "
                                "dist %d metric %d",
                                vrf_id, buf, re, re->type, re->status,
                                re->flags, re->distance, re->metric);

                UNSET_FLAG(re->status, ROUTE_ENTRY_NEXTHOPS_CHANGED);

                /* 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, false)) {
                        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) {
                        nexthop_active_update(rn, new_selected, true);
                        UNSET_FLAG(new_selected->status, ROUTE_ENTRY_CHANGED);
                }

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

                        /* Special case: new route is system route, so
                         * dataplane update will not be done - ensure we
                         * redistribute the route.
                         */
                        if (RIB_SYSTEM_ROUTE(new_selected))
                                redistribute_update(p, src_p, new_selected,
                                                    old_selected);
                }

                if (old_selected) {
                        if (!new_selected)
                                redistribute_delete(p, src_p, old_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);
}

/*
 * 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);
}

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

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

        table = zebra_vrf_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 process dplane results: 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;
        }

        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));

        src_pfx = dplane_ctx_get_src(ctx);
        rn = srcdest_rnode_get(table, dplane_ctx_get_dest(ctx),
                               src_pfx ? (struct prefix_ipv6 *)src_pfx : NULL);
        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));

        if (op == DPLANE_OP_ROUTE_DELETE) {
                /*
                 * 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) {
                        zsend_route_notify_owner_ctx(ctx, ZAPI_ROUTE_REMOVED);

                        if (zvrf)
                                zvrf->removals++;
                } else {
                        zsend_route_notify_owner_ctx(ctx,
                                                     ZAPI_ROUTE_FAIL_INSTALL);

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

                /* Nothing more to do in delete case */
                goto done;
        }

        /*
         * 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;
        }

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

        if (old_re &&
            (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);
                }
                old_re = NULL;
        }

        /*
         * Here's sort of a tough one: the route update result is stale.
         * Is it better to use the context block info to generate
         * redist and owner notification, or is it better to wait
         * for the up-to-date result to arrive?
         */
        if (re == NULL) {
                /* TODO -- for now, only expose up-to-date results */
                goto done;
        }

        if (status == ZEBRA_DPLANE_REQUEST_SUCCESS) {
                /* Update zebra nexthop FIB flag for each
                 * nexthop that was installed.
                 */
                for (ALL_NEXTHOPS_PTR(dplane_ctx_get_ng(ctx), ctx_nexthop)) {

                        for (ALL_NEXTHOPS(re->ng, nexthop)) {
                                if (nexthop_same(ctx_nexthop, nexthop))
                                        break;
                        }

                        if (nexthop == NULL)
                                continue;

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

                        if (CHECK_FLAG(ctx_nexthop->flags,
                                       NEXTHOP_FLAG_FIB))
                                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                        else
                                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);
                }

                if (zvrf) {
                        zvrf->installs++;
                        /* Set flag for nexthop tracking processing */
                        zvrf->flags |= ZEBRA_VRF_RIB_SCHEDULED;
                }

                /* Redistribute */
                /* TODO -- still calling the redist api using the route_entries,
                 * and there's a corner-case here: if there's no client
                 * for the 'new' route, a redist deleting the 'old' route
                 * will be sent. But if the 'old' context info was stale,
                 * 'old_re' will be NULL here and that delete will not be sent.
                 */
                redistribute_update(dest_pfx, src_pfx, re, old_re);

                /* Notify route owner */
                zsend_route_notify_owner(re,
                                         dest_pfx, ZAPI_ROUTE_INSTALLED);

        } else {
                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)));
        }

done:

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

/* 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);
        struct route_node *rnode;
        rib_dest_t *dest;
        struct zebra_vrf *zvrf = NULL;

        if (!lnode)
                return 0;

        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);
        list_delete_node(subq, lnode);
        return 1;
}

/*
 * Perform next-hop tracking processing after RIB updates.
 */
static void do_nht_processing(void)
{
        struct vrf *vrf;
        struct zebra_vrf *zvrf;

        /* Evaluate nexthops for those VRFs which underwent route processing.
         * This
         * should limit the evaluation to the necessary VRFs in most common
         * situations.
         */
        RB_FOREACH (vrf, vrf_id_head, &vrfs_by_id) {
                zvrf = vrf->info;
                if (zvrf == NULL || !(zvrf->flags & ZEBRA_VRF_RIB_SCHEDULED))
                        continue;

                if (IS_ZEBRA_DEBUG_RIB_DETAILED || IS_ZEBRA_DEBUG_NHT)
                        zlog_debug("NHT processing check for zvrf %s",
                                   zvrf_name(zvrf));

                zvrf->flags &= ~ZEBRA_VRF_RIB_SCHEDULED;
                zebra_evaluate_rnh(zvrf, AF_INET, 0, RNH_NEXTHOP_TYPE, NULL);
                zebra_evaluate_rnh(zvrf, AF_INET, 0, RNH_IMPORT_CHECK_TYPE,
                                   NULL);
                zebra_evaluate_rnh(zvrf, AF_INET6, 0, RNH_NEXTHOP_TYPE, NULL);
                zebra_evaluate_rnh(zvrf, AF_INET6, 0, RNH_IMPORT_CHECK_TYPE,
                                   NULL);
        }

        /* Schedule LSPs for processing, if needed. */
        zvrf = vrf_info_lookup(VRF_DEFAULT);
        if (mpls_should_lsps_be_processed(zvrf)) {
                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(zvrf);
        }
}

/*
 * All meta queues have been processed. Trigger next-hop evaluation.
 */
static void meta_queue_process_complete(struct work_queue *dummy)
{
        do_nht_processing();
}

/* 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(zebrad.ribq))
                        work_queue_add(zebrad.ribq, zebrad.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;
}

/*
 * Map from rib types to queue type (priority) in meta queue
 */
static const uint8_t meta_queue_map[ZEBRA_ROUTE_MAX] = {
        [ZEBRA_ROUTE_SYSTEM] = 4,
        [ZEBRA_ROUTE_KERNEL] = 0,
        [ZEBRA_ROUTE_CONNECT] = 0,
        [ZEBRA_ROUTE_STATIC] = 1,
        [ZEBRA_ROUTE_RIP] = 2,
        [ZEBRA_ROUTE_RIPNG] = 2,
        [ZEBRA_ROUTE_OSPF] = 2,
        [ZEBRA_ROUTE_OSPF6] = 2,
        [ZEBRA_ROUTE_ISIS] = 2,
        [ZEBRA_ROUTE_BGP] = 3,
        [ZEBRA_ROUTE_PIM] = 4, // Shouldn't happen but for safety
        [ZEBRA_ROUTE_EIGRP] = 2,
        [ZEBRA_ROUTE_NHRP] = 2,
        [ZEBRA_ROUTE_HSLS] = 4,
        [ZEBRA_ROUTE_OLSR] = 4,
        [ZEBRA_ROUTE_TABLE] = 1,
        [ZEBRA_ROUTE_LDP] = 4,
        [ZEBRA_ROUTE_VNC] = 3,
        [ZEBRA_ROUTE_VNC_DIRECT] = 3,
        [ZEBRA_ROUTE_VNC_DIRECT_RH] = 3,
        [ZEBRA_ROUTE_BGP_DIRECT] = 3,
        [ZEBRA_ROUTE_BGP_DIRECT_EXT] = 3,
        [ZEBRA_ROUTE_BABEL] = 2,
        [ZEBRA_ROUTE_ALL] = 4, // Shouldn't happen but for safety
};

/* Look into the RN and queue it into one or more priority queues,
 * increasing the size for each data push done.
 */
static void rib_meta_queue_add(struct meta_queue *mq, struct route_node *rn)
{
        struct route_entry *re;

        RNODE_FOREACH_RE (rn, re) {
                uint8_t qindex = meta_queue_map[re->type];
                struct zebra_vrf *zvrf;

                /* 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);
                        continue;
                }

                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);

                zvrf = zebra_vrf_lookup_by_id(re->vrf_id);
                if (zvrf)
                        zvrf->flags |= ZEBRA_VRF_RIB_SCHEDULED;
        }
}

/* Add route_node to work queue and schedule processing */
void 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;
        }

        if (zebrad.ribq == NULL) {
                flog_err(EC_ZEBRA_WQ_NONEXISTENT,
                         "%s: work_queue does not exist!", __func__);
                return;
        }

        /*
         * 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(zebrad.ribq))
                work_queue_add(zebrad.ribq, zebrad.mq);

        rib_meta_queue_add(zebrad.mq, rn);

        return;
}

/* 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(struct zebra_t *zebra)
{
        assert(zebra);

        if (!(zebra->ribq =
                      work_queue_new(zebra->master, "route_node processing"))) {
                flog_err(EC_ZEBRA_WQ_NONEXISTENT,
                         "%s: could not initialise work queue!", __func__);
                return;
        }

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

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

/* 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)
{
        struct route_entry *head;
        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 = XCALLOC(MTYPE_RIB_DEST, sizeof(rib_dest_t));
                route_lock_node(rn); /* rn route table reference */
                rn->info = dest;
                dest->rnode = rn;
        }

        head = dest->routes;
        if (head) {
                head->prev = re;
        }
        re->next = 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->table)) {
                rmap_name = zebra_get_import_table_route_map(afi, re->table);
                zebra_add_import_table_entry(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;

        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);

        if (re->next)
                re->next->prev = re->prev;

        if (re->prev)
                re->prev->next = re->next;
        else {
                dest->routes = re->next;
        }

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

        nexthops_free(re->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->table)) {
                zebra_del_import_table_entry(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 (type %d)",
                                re->vrf_id, buf, rn, re, 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];
        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",
                   func, (unsigned long)re->uptime, re->type, re->instance,
                   re->table);
        zlog_debug(
                "%s: metric == %u, mtu == %u, distance == %u, flags == %u, status == %u",
                func, re->metric, re->mtu, re->distance, re->flags, re->status);
        zlog_debug("%s: nexthop_num == %u, nexthop_active_num == %u", func,
                   re->nexthop_num, re->nexthop_active_num);

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

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

/* 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;
        unsigned changed = 0;
        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 && !RIB_SYSTEM_ROUTE(dest->selected_fib)) {
                changed = 1;
                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);
        }
        if (changed)
                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 route_table *table;
        struct route_node *rn;
        struct route_entry *same = NULL;
        struct nexthop *nexthop;
        int ret = 0;

        if (!re)
                return 0;

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

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

        /* 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);

                /* iBGP distance is 200. */
                if (re->type == ZEBRA_ROUTE_BGP
                    && CHECK_FLAG(re->flags, ZEBRA_FLAG_IBGP))
                        re->distance = 200;
        }

        /* 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 route, set FIB flag to the route. */
        if (RIB_SYSTEM_ROUTE(re))
                for (nexthop = re->ng.nexthop; nexthop; nexthop = nexthop->next)
                        SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);

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

                if (IS_ZEBRA_DEBUG_RIB_DETAILED)
                        route_entry_dump(p, src_p, re);
        }
        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 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_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)
                        zlog_debug("%u:%s%s%s doesn't exist in rib", vrf_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. */
                else {
                        if (nh == NULL) {
                                same = re;
                                break;
                        }
                        for (ALL_NEXTHOPS(re->ng, rtnh))
                                if (nexthop_same_no_recurse(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 (type %d) was deleted from kernel, adding",
                                        rn, fib, fib->type);
                        }
                        if (allow_delete) {
                                /* 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;
                }

                if (CHECK_FLAG(flags, ZEBRA_FLAG_EVPN_ROUTE)) {
                        struct nexthop *tmp_nh;

                        for (ALL_NEXTHOPS(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);
                        }
                }
                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 table_id, uint32_t metric, uint32_t mtu, uint8_t distance,
            route_tag_t tag)
{
        struct route_entry *re;
        struct nexthop *nexthop;

        /* 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->nexthop_num = 0;
        re->uptime = time(NULL);
        re->tag = tag;

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

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

/* 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;
        struct route_entry *re, *next;

        /* 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_IF_CHANGE:
                        /* Examine all routes that won't get processed by the
                         * protocol or
                         * triggered by nexthop evaluation (NHT). This would be
                         * system,
                         * kernel and certain static routes. Note that NHT will
                         * get
                         * triggered upon an interface event as connected routes
                         * always
                         * get queued for processing.
                         */
                        RNODE_FOREACH_RE_SAFE (rn, re, next) {
                                struct nexthop *nh;

                                if (re->type != ZEBRA_ROUTE_SYSTEM
                                    && re->type != ZEBRA_ROUTE_KERNEL
                                    && re->type != ZEBRA_ROUTE_CONNECT
                                    && re->type != ZEBRA_ROUTE_STATIC)
                                        continue;

                                if (re->type != ZEBRA_ROUTE_STATIC) {
                                        rib_queue_add(rn);
                                        continue;
                                }

                                for (nh = re->ng.nexthop; nh; nh = nh->next)
                                        if (!(nh->type == NEXTHOP_TYPE_IPV4
                                              || nh->type == NEXTHOP_TYPE_IPV6))
                                                break;

                                /* If we only have nexthops to a
                                 * gateway, NHT will
                                 * take care.
                                 */
                                if (nh)
                                        rib_queue_add(rn);
                        }
                        break;

                case RIB_UPDATE_RMAP_CHANGE:
                case RIB_UPDATE_OTHER:
                        /* Right now, examine all routes. Can restrict to a
                         * protocol in
                         * some cases (TODO).
                         */
                        if (rnode_to_ribs(rn))
                                rib_queue_add(rn);
                        break;

                default:
                        break;
                }
        }
}

/* RIB update function. */
void rib_update(vrf_id_t vrf_id, rib_update_event_t event)
{
        struct route_table *table;

        /* Process routes of interested address-families. */
        table = zebra_vrf_table(AFI_IP, SAFI_UNICAST, vrf_id);
        if (table) {
                if (IS_ZEBRA_DEBUG_EVENT)
                        zlog_debug("%s : AFI_IP event %d", __func__, event);
                rib_update_table(table, event);
        }

        table = zebra_vrf_table(AFI_IP6, SAFI_UNICAST, vrf_id);
        if (table) {
                if (IS_ZEBRA_DEBUG_EVENT)
                        zlog_debug("%s : AFI_IP6 event %d", __func__, event);
                rib_update_table(table, 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;

                        /*
                         * 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
                         */
                        for (ALL_NEXTHOPS(re->ng, nexthop))
                                SET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);

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

/* Sweep all RIB tables.  */
void rib_sweep_route(void)
{
        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();
}

/* 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;
        unsigned long cnt = 0;

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

        cnt += zebra_router_score_proto(proto, instance);

        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);

                        if (!RIB_SYSTEM_ROUTE(dest->selected_fib)) {
                                rib_uninstall_kernel(rn, dest->selected_fib);
                                dest->selected_fib = NULL;
                        }
                }
        }
}

/*
 *
 */
static int rib_process_dplane_results(struct thread *thread)
{
        struct zebra_dplane_ctx *ctx;

        do {
                /* Take lock controlling queue of results */
                pthread_mutex_lock(&dplane_mutex);
                {
                        /* Dequeue context block */
                        ctx = dplane_ctx_dequeue(&rib_dplane_q);
                }
                pthread_mutex_unlock(&dplane_mutex);

                if (ctx)
                        rib_process_after(ctx);
                else
                        break;

        } while (1);

        /* Check for nexthop tracking processing after finishing with results */
        do_nht_processing();

        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 zebra_dplane_ctx *ctx)
{
        /* Take lock controlling queue of results */
        pthread_mutex_lock(&dplane_mutex);
        {
                /* Enqueue context block */
                dplane_ctx_enqueue_tail(&rib_dplane_q, ctx);
        }
        pthread_mutex_unlock(&dplane_mutex);

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

        return 0;
}

/* Routing information base initialize. */
void rib_init(void)
{
        rib_queue_init(&zebrad);

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