Merge pull request #2329 from pguibert6WIND/issue_2275_proposal

[mirror_frr.git] / pimd / pim_msdp.c

/*
 * IP MSDP for Quagga
 * Copyright (C) 2016 Cumulus Networks, Inc.
 *
 * This program 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 of the License, or
 * (at your option) any later version.
 *
 * This program 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 <lib/hash.h>
#include <lib/jhash.h>
#include <lib/log.h>
#include <lib/prefix.h>
#include <lib/sockunion.h>
#include <lib/stream.h>
#include <lib/thread.h>
#include <lib/vty.h>
#include <lib/plist.h>

#include "pimd.h"
#include "pim_cmd.h"
#include "pim_memory.h"
#include "pim_iface.h"
#include "pim_rp.h"
#include "pim_str.h"
#include "pim_time.h"
#include "pim_upstream.h"
#include "pim_oil.h"

#include "pim_msdp.h"
#include "pim_msdp_packet.h"
#include "pim_msdp_socket.h"

// struct pim_msdp pim_msdp, *msdp = &pim_msdp;

static void pim_msdp_peer_listen(struct pim_msdp_peer *mp);
static void pim_msdp_peer_cr_timer_setup(struct pim_msdp_peer *mp, bool start);
static void pim_msdp_peer_ka_timer_setup(struct pim_msdp_peer *mp, bool start);
static void pim_msdp_peer_hold_timer_setup(struct pim_msdp_peer *mp,
                                           bool start);
static void pim_msdp_peer_free(struct pim_msdp_peer *mp);
static void pim_msdp_enable(struct pim_instance *pim);
static void pim_msdp_sa_adv_timer_setup(struct pim_instance *pim, bool start);
static void pim_msdp_sa_deref(struct pim_msdp_sa *sa,
                              enum pim_msdp_sa_flags flags);
static int pim_msdp_mg_mbr_comp(const void *p1, const void *p2);
static void pim_msdp_mg_mbr_free(struct pim_msdp_mg_mbr *mbr);
static void pim_msdp_mg_mbr_do_del(struct pim_msdp_mg *mg,
                                   struct pim_msdp_mg_mbr *mbr);

/************************ SA cache management ******************************/
static void pim_msdp_sa_timer_expiry_log(struct pim_msdp_sa *sa,
                                         const char *timer_str)
{
        zlog_debug("MSDP SA %s %s timer expired", sa->sg_str, timer_str);
}

/* RFC-3618:Sec-5.1 - global active source advertisement timer */
static int pim_msdp_sa_adv_timer_cb(struct thread *t)
{
        struct pim_instance *pim = THREAD_ARG(t);

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP SA advertisment timer expired");
        }

        pim_msdp_sa_adv_timer_setup(pim, true /* start */);
        pim_msdp_pkt_sa_tx(pim);
        return 0;
}
static void pim_msdp_sa_adv_timer_setup(struct pim_instance *pim, bool start)
{
        THREAD_OFF(pim->msdp.sa_adv_timer);
        if (start) {
                thread_add_timer(pim->msdp.master, pim_msdp_sa_adv_timer_cb,
                                 pim, PIM_MSDP_SA_ADVERTISMENT_TIME,
                                 &pim->msdp.sa_adv_timer);
        }
}

/* RFC-3618:Sec-5.3 - SA cache state timer */
static int pim_msdp_sa_state_timer_cb(struct thread *t)
{
        struct pim_msdp_sa *sa;

        sa = THREAD_ARG(t);

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_sa_timer_expiry_log(sa, "state");
        }

        pim_msdp_sa_deref(sa, PIM_MSDP_SAF_PEER);
        return 0;
}
static void pim_msdp_sa_state_timer_setup(struct pim_msdp_sa *sa, bool start)
{
        THREAD_OFF(sa->sa_state_timer);
        if (start) {
                thread_add_timer(sa->pim->msdp.master,
                                 pim_msdp_sa_state_timer_cb, sa,
                                 PIM_MSDP_SA_HOLD_TIME, &sa->sa_state_timer);
        }
}

static void pim_msdp_sa_upstream_del(struct pim_msdp_sa *sa)
{
        struct pim_upstream *up = sa->up;
        if (!up) {
                return;
        }

        sa->up = NULL;
        if (PIM_UPSTREAM_FLAG_TEST_SRC_MSDP(up->flags)) {
                PIM_UPSTREAM_FLAG_UNSET_SRC_MSDP(up->flags);
                sa->flags |= PIM_MSDP_SAF_UP_DEL_IN_PROG;
                pim_upstream_del(sa->pim, up, __PRETTY_FUNCTION__);
                sa->flags &= ~PIM_MSDP_SAF_UP_DEL_IN_PROG;
        }

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP SA %s de-referenced SPT", sa->sg_str);
        }
}

static bool pim_msdp_sa_upstream_add_ok(struct pim_msdp_sa *sa,
                                        struct pim_upstream *xg_up)
{
        if (!(sa->flags & PIM_MSDP_SAF_PEER)) {
                /* SA should have been rxed from a peer */
                return false;
        }
        /* check if we are RP */
        if (!I_am_RP(sa->pim, sa->sg.grp)) {
                return false;
        }

        /* check if we have a (*, G) with a non-empty immediate OIL */
        if (!xg_up) {
                struct prefix_sg sg;

                memset(&sg, 0, sizeof(sg));
                sg.grp = sa->sg.grp;

                xg_up = pim_upstream_find(sa->pim, &sg);
        }
        if (!xg_up || (xg_up->join_state != PIM_UPSTREAM_JOINED)) {
                /* join desired will be true for such (*, G) entries so we will
                 * just look at join_state and let the PIM state machine do the
                 * rest of
                 * the magic */
                return false;
        }

        return true;
}

/* Upstream add evaluation needs to happen everytime -
 * 1. Peer reference is added or removed.
 * 2. The RP for a group changes.
 * 3. joinDesired for the associated (*, G) changes
 * 4. associated (*, G) is removed - this seems like a bit redundant
 *    (considering #4); but just in case an entry gets nuked without
 *    upstream state transition
 *    */
static void pim_msdp_sa_upstream_update(struct pim_msdp_sa *sa,
                                        struct pim_upstream *xg_up,
                                        const char *ctx)
{
        struct pim_upstream *up;

        if (!pim_msdp_sa_upstream_add_ok(sa, xg_up)) {
                pim_msdp_sa_upstream_del(sa);
                return;
        }

        if (sa->up) {
                /* nothing to do */
                return;
        }

        up = pim_upstream_find(sa->pim, &sa->sg);
        if (up && (PIM_UPSTREAM_FLAG_TEST_SRC_MSDP(up->flags))) {
                /* somehow we lost track of the upstream ptr? best log it */
                sa->up = up;
                if (PIM_DEBUG_MSDP_EVENTS) {
                        zlog_debug("MSDP SA %s SPT reference missing",
                                   sa->sg_str);
                }
                return;
        }

        /* RFC3618: "RP triggers a (S, G) join event towards the data source
         * as if a JP message was rxed addressed to the RP itself." */
        up = pim_upstream_add(sa->pim, &sa->sg, NULL /* iif */,
                              PIM_UPSTREAM_FLAG_MASK_SRC_MSDP,
                              __PRETTY_FUNCTION__, NULL);

        sa->up = up;
        if (up) {
                /* update inherited oil */
                pim_upstream_inherited_olist(sa->pim, up);
                /* should we also start the kat in parallel? we will need it
                 * when the
                 * SA ages out */
                if (PIM_DEBUG_MSDP_EVENTS) {
                        zlog_debug("MSDP SA %s referenced SPT", sa->sg_str);
                }
        } else {
                if (PIM_DEBUG_MSDP_EVENTS) {
                        zlog_debug("MSDP SA %s SPT reference failed",
                                   sa->sg_str);
                }
        }
}

/* release all mem associated with a sa */
static void pim_msdp_sa_free(struct pim_msdp_sa *sa)
{
        pim_msdp_sa_state_timer_setup(sa, false);

        XFREE(MTYPE_PIM_MSDP_SA, sa);
}

static struct pim_msdp_sa *pim_msdp_sa_new(struct pim_instance *pim,
                                           struct prefix_sg *sg,
                                           struct in_addr rp)
{
        struct pim_msdp_sa *sa;

        sa = XCALLOC(MTYPE_PIM_MSDP_SA, sizeof(*sa));
        if (!sa) {
                zlog_err("%s: PIM XCALLOC(%zu) failure", __PRETTY_FUNCTION__,
                         sizeof(*sa));
                return NULL;
        }

        sa->pim = pim;
        sa->sg = *sg;
        pim_str_sg_set(sg, sa->sg_str);
        sa->rp = rp;
        sa->uptime = pim_time_monotonic_sec();

        /* insert into misc tables for easy access */
        sa = hash_get(pim->msdp.sa_hash, sa, hash_alloc_intern);
        listnode_add_sort(pim->msdp.sa_list, sa);

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP SA %s created", sa->sg_str);
        }

        return sa;
}

static struct pim_msdp_sa *pim_msdp_sa_find(struct pim_instance *pim,
                                            struct prefix_sg *sg)
{
        struct pim_msdp_sa lookup;

        lookup.sg = *sg;
        return hash_lookup(pim->msdp.sa_hash, &lookup);
}

static struct pim_msdp_sa *pim_msdp_sa_add(struct pim_instance *pim,
                                           struct prefix_sg *sg,
                                           struct in_addr rp)
{
        struct pim_msdp_sa *sa;

        sa = pim_msdp_sa_find(pim, sg);
        if (sa) {
                return sa;
        }

        return pim_msdp_sa_new(pim, sg, rp);
}

static void pim_msdp_sa_del(struct pim_msdp_sa *sa)
{
        /* this is somewhat redundant - still want to be careful not to leave
         * stale upstream references */
        pim_msdp_sa_upstream_del(sa);

        /* stop timers */
        pim_msdp_sa_state_timer_setup(sa, false /* start */);

        /* remove the entry from various tables */
        listnode_delete(sa->pim->msdp.sa_list, sa);
        hash_release(sa->pim->msdp.sa_hash, sa);

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP SA %s deleted", sa->sg_str);
        }

        /* free up any associated memory */
        pim_msdp_sa_free(sa);
}

static void pim_msdp_sa_peer_ip_set(struct pim_msdp_sa *sa,
                                    struct pim_msdp_peer *mp, struct in_addr rp)
{
        struct pim_msdp_peer *old_mp;

        /* optimize the "no change" case as it will happen
         * frequently/periodically */
        if (mp && (sa->peer.s_addr == mp->peer.s_addr)) {
                return;
        }

        /* any time the peer ip changes also update the rp address */
        if (PIM_INADDR_ISNOT_ANY(sa->peer)) {
                old_mp = pim_msdp_peer_find(sa->pim, sa->peer);
                if (old_mp && old_mp->sa_cnt) {
                        --old_mp->sa_cnt;
                }
        }

        if (mp) {
                ++mp->sa_cnt;
                sa->peer = mp->peer;
        } else {
                sa->peer.s_addr = PIM_NET_INADDR_ANY;
        }
        sa->rp = rp;
}

/* When a local active-source is removed there is no way to withdraw the
 * source from peers. We will simply remove it from the SA cache so it will
 * not be sent in supsequent SA updates. Peers will consequently timeout the
 * SA.
 * Similarly a "peer-added" SA is never explicitly deleted. It is simply
 * aged out overtime if not seen in the SA updates from the peers.
 * XXX: should we provide a knob to drop entries learnt from a peer when the
 * peer goes down? */
static void pim_msdp_sa_deref(struct pim_msdp_sa *sa,
                              enum pim_msdp_sa_flags flags)
{
        bool update_up = false;

        if ((sa->flags & PIM_MSDP_SAF_LOCAL)) {
                if (flags & PIM_MSDP_SAF_LOCAL) {
                        if (PIM_DEBUG_MSDP_EVENTS) {
                                zlog_debug("MSDP SA %s local reference removed",
                                           sa->sg_str);
                        }
                        if (sa->pim->msdp.local_cnt)
                                --sa->pim->msdp.local_cnt;
                }
        }

        if ((sa->flags & PIM_MSDP_SAF_PEER)) {
                if (flags & PIM_MSDP_SAF_PEER) {
                        struct in_addr rp;

                        if (PIM_DEBUG_MSDP_EVENTS) {
                                zlog_debug("MSDP SA %s peer reference removed",
                                           sa->sg_str);
                        }
                        pim_msdp_sa_state_timer_setup(sa, false /* start */);
                        rp.s_addr = INADDR_ANY;
                        pim_msdp_sa_peer_ip_set(sa, NULL /* mp */, rp);
                        /* if peer ref was removed we need to remove the msdp
                         * reference on the
                         * msdp entry */
                        update_up = true;
                }
        }

        sa->flags &= ~flags;
        if (update_up) {
                pim_msdp_sa_upstream_update(sa, NULL /* xg_up */, "sa-deref");
        }

        if (!(sa->flags & PIM_MSDP_SAF_REF)) {
                pim_msdp_sa_del(sa);
        }
}

void pim_msdp_sa_ref(struct pim_instance *pim, struct pim_msdp_peer *mp,
                     struct prefix_sg *sg, struct in_addr rp)
{
        struct pim_msdp_sa *sa;

        sa = pim_msdp_sa_add(pim, sg, rp);
        if (!sa) {
                return;
        }

        /* reference it */
        if (mp) {
                if (!(sa->flags & PIM_MSDP_SAF_PEER)) {
                        sa->flags |= PIM_MSDP_SAF_PEER;
                        if (PIM_DEBUG_MSDP_EVENTS) {
                                zlog_debug("MSDP SA %s added by peer",
                                           sa->sg_str);
                        }
                }
                pim_msdp_sa_peer_ip_set(sa, mp, rp);
                /* start/re-start the state timer to prevent cache expiry */
                pim_msdp_sa_state_timer_setup(sa, true /* start */);
                /* We re-evaluate SA "SPT-trigger" everytime we hear abt it from
                 * a
                 * peer. XXX: If this becomes too much of a periodic overhead we
                 * can make it event based */
                pim_msdp_sa_upstream_update(sa, NULL /* xg_up */, "peer-ref");
        } else {
                if (!(sa->flags & PIM_MSDP_SAF_LOCAL)) {
                        sa->flags |= PIM_MSDP_SAF_LOCAL;
                        ++sa->pim->msdp.local_cnt;
                        if (PIM_DEBUG_MSDP_EVENTS) {
                                zlog_debug("MSDP SA %s added locally",
                                           sa->sg_str);
                        }
                        /* send an immediate SA update to peers */
                        pim_msdp_pkt_sa_tx_one(sa);
                }
                sa->flags &= ~PIM_MSDP_SAF_STALE;
        }
}

/* The following criteria must be met to originate an SA from the MSDP
 * speaker -
 * 1. KAT must be running i.e. source is active.
 * 2. We must be RP for the group.
 * 3. Source must be registrable to the RP (this is where the RFC is vague
 *    and especially ambiguous in CLOS networks; with anycast RP all sources
 *    are potentially registrable to all RPs in the domain). We assume #3 is
 *    satisfied if -
 *    a. We are also the FHR-DR for the source (OR)
 *    b. We rxed a pim register (null or data encapsulated) within the last
 *       (3 * (1.5 * register_suppression_timer))).
 */
static bool pim_msdp_sa_local_add_ok(struct pim_upstream *up)
{
        struct pim_instance *pim = up->channel_oil->pim;

        if (!(pim->msdp.flags & PIM_MSDPF_ENABLE)) {
                return false;
        }

        if (!up->t_ka_timer) {
                /* stream is not active */
                return false;
        }

        if (!I_am_RP(pim, up->sg.grp)) {
                /* we are not RP for the group */
                return false;
        }

        /* we are the FHR-DR for this stream  or we are RP and have seen
         * registers
         * from a FHR for this source */
        if (PIM_UPSTREAM_FLAG_TEST_FHR(up->flags) || up->t_msdp_reg_timer) {
                return true;
        }

        return false;
}

static void pim_msdp_sa_local_add(struct pim_instance *pim,
                                  struct prefix_sg *sg)
{
        struct in_addr rp;
        rp.s_addr = 0;
        pim_msdp_sa_ref(pim, NULL /* mp */, sg, rp);
}

void pim_msdp_sa_local_del(struct pim_instance *pim, struct prefix_sg *sg)
{
        struct pim_msdp_sa *sa;

        sa = pim_msdp_sa_find(pim, sg);
        if (sa) {
                pim_msdp_sa_deref(sa, PIM_MSDP_SAF_LOCAL);
        }
}

/* we need to be very cautious with this API as SA del too can trigger an
 * upstream del and we will get stuck in a simple loop */
static void pim_msdp_sa_local_del_on_up_del(struct pim_instance *pim,
                                            struct prefix_sg *sg)
{
        struct pim_msdp_sa *sa;

        sa = pim_msdp_sa_find(pim, sg);
        if (sa) {
                if (PIM_DEBUG_MSDP_INTERNAL) {
                        zlog_debug("MSDP local sa %s del on up del",
                                   sa->sg_str);
                }

                /* if there is no local reference escape */
                if (!(sa->flags & PIM_MSDP_SAF_LOCAL)) {
                        if (PIM_DEBUG_MSDP_INTERNAL) {
                                zlog_debug("MSDP local sa %s del; no local ref",
                                           sa->sg_str);
                        }
                        return;
                }

                if (sa->flags & PIM_MSDP_SAF_UP_DEL_IN_PROG) {
                        /* MSDP is the one that triggered the upstream del. if
                         * this happens
                         * we most certainly have a bug in the PIM upstream
                         * state machine. We
                         * will not have a local reference unless the KAT is
                         * running. And if the
                         * KAT is running there MUST be an additional
                         * source-stream reference to
                         * the flow. Accounting for such cases requires lot of
                         * changes; perhaps
                         * address this in the next release? - XXX  */
                        zlog_err(
                                "MSDP sa %s SPT teardown is causing the local entry to be removed",
                                sa->sg_str);
                        return;
                }

                /* we are dropping the sa on upstream del we should not have an
                 * upstream reference */
                if (sa->up) {
                        if (PIM_DEBUG_MSDP_INTERNAL) {
                                zlog_debug("MSDP local sa %s del; up non-NULL",
                                           sa->sg_str);
                        }
                        sa->up = NULL;
                }
                pim_msdp_sa_deref(sa, PIM_MSDP_SAF_LOCAL);
        }
}

/* Local SA qualification needs to be re-evaluated when -
 * 1. KAT is started or stopped
 * 2. on RP changes
 * 3. Whenever FHR status changes for a (S,G) - XXX - currently there
 *    is no clear path to transition an entry out of "MASK_FHR" need
 *    to discuss this with Donald. May result in some strangeness if the
 *    FHR is also the RP.
 * 4. When msdp_reg timer is started or stopped
 */
void pim_msdp_sa_local_update(struct pim_upstream *up)
{
        struct pim_instance *pim = up->channel_oil->pim;

        if (pim_msdp_sa_local_add_ok(up)) {
                pim_msdp_sa_local_add(pim, &up->sg);
        } else {
                pim_msdp_sa_local_del(pim, &up->sg);
        }
}

static void pim_msdp_sa_local_setup(struct pim_instance *pim)
{
        struct pim_upstream *up;
        struct listnode *up_node;

        for (ALL_LIST_ELEMENTS_RO(pim->upstream_list, up_node, up)) {
                pim_msdp_sa_local_update(up);
        }
}

/* whenever the RP changes we need to re-evaluate the "local" SA-cache */
/* XXX: needs to be tested */
void pim_msdp_i_am_rp_changed(struct pim_instance *pim)
{
        struct listnode *sanode;
        struct listnode *nextnode;
        struct pim_msdp_sa *sa;

        if (!(pim->msdp.flags & PIM_MSDPF_ENABLE)) {
                /* if the feature is not enabled do nothing */
                return;
        }

        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP i_am_rp changed");
        }

        /* mark all local entries as stale */
        for (ALL_LIST_ELEMENTS_RO(pim->msdp.sa_list, sanode, sa)) {
                if (sa->flags & PIM_MSDP_SAF_LOCAL) {
                        sa->flags |= PIM_MSDP_SAF_STALE;
                }
        }

        /* re-setup local SA entries */
        pim_msdp_sa_local_setup(pim);

        for (ALL_LIST_ELEMENTS(pim->msdp.sa_list, sanode, nextnode, sa)) {
                /* purge stale SA entries */
                if (sa->flags & PIM_MSDP_SAF_STALE) {
                        /* clear the stale flag; the entry may be kept even
                         * after
                         * "local-deref" */
                        sa->flags &= ~PIM_MSDP_SAF_STALE;
                        /* sa_deref can end up freeing the sa; so don't access
                         * contents after */
                        pim_msdp_sa_deref(sa, PIM_MSDP_SAF_LOCAL);
                } else {
                        /* if the souce is still active check if we can
                         * influence SPT */
                        pim_msdp_sa_upstream_update(sa, NULL /* xg_up */,
                                                    "rp-change");
                }
        }
}

/* We track the join state of (*, G) entries. If G has sources in the SA-cache
 * we need to setup or teardown SPT when the JoinDesired status changes for
 * (*, G) */
void pim_msdp_up_join_state_changed(struct pim_instance *pim,
                                    struct pim_upstream *xg_up)
{
        struct listnode *sanode;
        struct pim_msdp_sa *sa;

        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP join state changed for %s", xg_up->sg_str);
        }

        /* If this is not really an XG entry just move on */
        if ((xg_up->sg.src.s_addr != INADDR_ANY)
            || (xg_up->sg.grp.s_addr == INADDR_ANY)) {
                return;
        }

        /* XXX: Need to maintain SAs per-group to avoid all this unnecessary
         * walking */
        for (ALL_LIST_ELEMENTS_RO(pim->msdp.sa_list, sanode, sa)) {
                if (sa->sg.grp.s_addr != xg_up->sg.grp.s_addr) {
                        continue;
                }
                pim_msdp_sa_upstream_update(sa, xg_up, "up-jp-change");
        }
}

static void pim_msdp_up_xg_del(struct pim_instance *pim, struct prefix_sg *sg)
{
        struct listnode *sanode;
        struct pim_msdp_sa *sa;

        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP %s del", pim_str_sg_dump(sg));
        }

        /* If this is not really an XG entry just move on */
        if ((sg->src.s_addr != INADDR_ANY) || (sg->grp.s_addr == INADDR_ANY)) {
                return;
        }

        /* XXX: Need to maintain SAs per-group to avoid all this unnecessary
         * walking */
        for (ALL_LIST_ELEMENTS_RO(pim->msdp.sa_list, sanode, sa)) {
                if (sa->sg.grp.s_addr != sg->grp.s_addr) {
                        continue;
                }
                pim_msdp_sa_upstream_update(sa, NULL /* xg */, "up-jp-change");
        }
}

void pim_msdp_up_del(struct pim_instance *pim, struct prefix_sg *sg)
{
        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP up %s del", pim_str_sg_dump(sg));
        }
        if (sg->src.s_addr == INADDR_ANY) {
                pim_msdp_up_xg_del(pim, sg);
        } else {
                pim_msdp_sa_local_del_on_up_del(pim, sg);
        }
}

/* sa hash and peer list helpers */
static unsigned int pim_msdp_sa_hash_key_make(void *p)
{
        struct pim_msdp_sa *sa = p;

        return (jhash_2words(sa->sg.src.s_addr, sa->sg.grp.s_addr, 0));
}

static int pim_msdp_sa_hash_eq(const void *p1, const void *p2)
{
        const struct pim_msdp_sa *sa1 = p1;
        const struct pim_msdp_sa *sa2 = p2;

        return ((sa1->sg.src.s_addr == sa2->sg.src.s_addr)
                && (sa1->sg.grp.s_addr == sa2->sg.grp.s_addr));
}

static int pim_msdp_sa_comp(const void *p1, const void *p2)
{
        const struct pim_msdp_sa *sa1 = p1;
        const struct pim_msdp_sa *sa2 = p2;

        if (ntohl(sa1->sg.grp.s_addr) < ntohl(sa2->sg.grp.s_addr))
                return -1;

        if (ntohl(sa1->sg.grp.s_addr) > ntohl(sa2->sg.grp.s_addr))
                return 1;

        if (ntohl(sa1->sg.src.s_addr) < ntohl(sa2->sg.src.s_addr))
                return -1;

        if (ntohl(sa1->sg.src.s_addr) > ntohl(sa2->sg.src.s_addr))
                return 1;

        return 0;
}

/* RFC-3618:Sec-10.1.3 - Peer-RPF forwarding */
/* XXX: this can use a bit of refining and extensions */
bool pim_msdp_peer_rpf_check(struct pim_msdp_peer *mp, struct in_addr rp)
{
        if (mp->peer.s_addr == rp.s_addr) {
                return true;
        }

        return false;
}

/************************ Peer session management **************************/
char *pim_msdp_state_dump(enum pim_msdp_peer_state state, char *buf,
                          int buf_size)
{
        switch (state) {
        case PIM_MSDP_DISABLED:
                snprintf(buf, buf_size, "%s", "disabled");
                break;
        case PIM_MSDP_INACTIVE:
                snprintf(buf, buf_size, "%s", "inactive");
                break;
        case PIM_MSDP_LISTEN:
                snprintf(buf, buf_size, "%s", "listen");
                break;
        case PIM_MSDP_CONNECTING:
                snprintf(buf, buf_size, "%s", "connecting");
                break;
        case PIM_MSDP_ESTABLISHED:
                snprintf(buf, buf_size, "%s", "established");
                break;
        default:
                snprintf(buf, buf_size, "unk-%d", state);
        }
        return buf;
}

char *pim_msdp_peer_key_dump(struct pim_msdp_peer *mp, char *buf, int buf_size,
                             bool long_format)
{
        char peer_str[INET_ADDRSTRLEN];
        char local_str[INET_ADDRSTRLEN];

        pim_inet4_dump("<peer?>", mp->peer, peer_str, sizeof(peer_str));
        if (long_format) {
                pim_inet4_dump("<local?>", mp->local, local_str,
                               sizeof(local_str));
                snprintf(buf, buf_size, "MSDP peer %s local %s mg %s", peer_str,
                         local_str, mp->mesh_group_name);
        } else {
                snprintf(buf, buf_size, "MSDP peer %s", peer_str);
        }

        return buf;
}

static void pim_msdp_peer_state_chg_log(struct pim_msdp_peer *mp)
{
        char state_str[PIM_MSDP_STATE_STRLEN];

        pim_msdp_state_dump(mp->state, state_str, sizeof(state_str));
        zlog_debug("MSDP peer %s state chg to %s", mp->key_str, state_str);
}

/* MSDP Connection State Machine actions (defined in RFC-3618:Sec-11.2) */
/* 11.2.A2: active peer - start connect retry timer; when the timer fires
 * a tcp connection will be made */
static void pim_msdp_peer_connect(struct pim_msdp_peer *mp)
{
        mp->state = PIM_MSDP_CONNECTING;
        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_state_chg_log(mp);
        }

        pim_msdp_peer_cr_timer_setup(mp, true /* start */);
}

/* 11.2.A3: passive peer - just listen for connections */
static void pim_msdp_peer_listen(struct pim_msdp_peer *mp)
{
        mp->state = PIM_MSDP_LISTEN;
        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_state_chg_log(mp);
        }

        /* this is interntionally asymmetric i.e. we set up listen-socket when
        * the
        * first listening peer is configured; but don't bother tearing it down
        * when
        * all the peers go down */
        pim_msdp_sock_listen(mp->pim);
}

/* 11.2.A4 and 11.2.A5: transition active or passive peer to
 * established state */
void pim_msdp_peer_established(struct pim_msdp_peer *mp)
{
        if (mp->state != PIM_MSDP_ESTABLISHED) {
                ++mp->est_flaps;
        }

        mp->state = PIM_MSDP_ESTABLISHED;
        mp->uptime = pim_time_monotonic_sec();

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_state_chg_log(mp);
        }

        /* stop retry timer on active peers */
        pim_msdp_peer_cr_timer_setup(mp, false /* start */);

        /* send KA; start KA and hold timers */
        pim_msdp_pkt_ka_tx(mp);
        pim_msdp_peer_ka_timer_setup(mp, true /* start */);
        pim_msdp_peer_hold_timer_setup(mp, true /* start */);

        pim_msdp_pkt_sa_tx_to_one_peer(mp);

        PIM_MSDP_PEER_WRITE_ON(mp);
        PIM_MSDP_PEER_READ_ON(mp);
}

/* 11.2.A6, 11.2.A7 and 11.2.A8: shutdown the peer tcp connection */
void pim_msdp_peer_stop_tcp_conn(struct pim_msdp_peer *mp, bool chg_state)
{
        if (chg_state) {
                if (mp->state == PIM_MSDP_ESTABLISHED) {
                        ++mp->est_flaps;
                }
                mp->state = PIM_MSDP_INACTIVE;
                if (PIM_DEBUG_MSDP_EVENTS) {
                        pim_msdp_peer_state_chg_log(mp);
                }
        }

        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP peer %s pim_msdp_peer_stop_tcp_conn",
                           mp->key_str);
        }
        /* stop read and write threads */
        PIM_MSDP_PEER_READ_OFF(mp);
        PIM_MSDP_PEER_WRITE_OFF(mp);

        /* reset buffers */
        mp->packet_size = 0;
        if (mp->ibuf)
                stream_reset(mp->ibuf);
        if (mp->obuf)
                stream_fifo_clean(mp->obuf);

        /* stop all peer timers */
        pim_msdp_peer_ka_timer_setup(mp, false /* start */);
        pim_msdp_peer_cr_timer_setup(mp, false /* start */);
        pim_msdp_peer_hold_timer_setup(mp, false /* start */);

        /* close connection */
        if (mp->fd >= 0) {
                close(mp->fd);
                mp->fd = -1;
        }
}

/* RFC-3618:Sec-5.6 - stop the peer tcp connection and startover */
void pim_msdp_peer_reset_tcp_conn(struct pim_msdp_peer *mp, const char *rc_str)
{
        if (PIM_DEBUG_EVENTS) {
                zlog_debug("MSDP peer %s tcp reset %s", mp->key_str, rc_str);
                snprintf(mp->last_reset, sizeof(mp->last_reset), "%s", rc_str);
        }

        /* close the connection and transition to listening or connecting */
        pim_msdp_peer_stop_tcp_conn(mp, true /* chg_state */);
        if (PIM_MSDP_PEER_IS_LISTENER(mp)) {
                pim_msdp_peer_listen(mp);
        } else {
                pim_msdp_peer_connect(mp);
        }
}

static void pim_msdp_peer_timer_expiry_log(struct pim_msdp_peer *mp,
                                           const char *timer_str)
{
        zlog_debug("MSDP peer %s %s timer expired", mp->key_str, timer_str);
}

/* RFC-3618:Sec-5.4 - peer hold timer */
static int pim_msdp_peer_hold_timer_cb(struct thread *t)
{
        struct pim_msdp_peer *mp;

        mp = THREAD_ARG(t);

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_timer_expiry_log(mp, "hold");
        }

        if (mp->state != PIM_MSDP_ESTABLISHED) {
                return 0;
        }

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_state_chg_log(mp);
        }
        pim_msdp_peer_reset_tcp_conn(mp, "ht-expired");
        return 0;
}

static void pim_msdp_peer_hold_timer_setup(struct pim_msdp_peer *mp, bool start)
{
        struct pim_instance *pim = mp->pim;
        THREAD_OFF(mp->hold_timer);
        if (start) {
                thread_add_timer(pim->msdp.master, pim_msdp_peer_hold_timer_cb,
                                 mp, PIM_MSDP_PEER_HOLD_TIME, &mp->hold_timer);
        }
}


/* RFC-3618:Sec-5.5 - peer keepalive timer */
static int pim_msdp_peer_ka_timer_cb(struct thread *t)
{
        struct pim_msdp_peer *mp;

        mp = THREAD_ARG(t);

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_timer_expiry_log(mp, "ka");
        }

        pim_msdp_pkt_ka_tx(mp);
        pim_msdp_peer_ka_timer_setup(mp, true /* start */);
        return 0;
}
static void pim_msdp_peer_ka_timer_setup(struct pim_msdp_peer *mp, bool start)
{
        THREAD_OFF(mp->ka_timer);
        if (start) {
                thread_add_timer(mp->pim->msdp.master,
                                 pim_msdp_peer_ka_timer_cb, mp,
                                 PIM_MSDP_PEER_KA_TIME, &mp->ka_timer);
        }
}

static void pim_msdp_peer_active_connect(struct pim_msdp_peer *mp)
{
        int rc;
        ++mp->conn_attempts;
        rc = pim_msdp_sock_connect(mp);

        if (PIM_DEBUG_MSDP_INTERNAL) {
                zlog_debug("MSDP peer %s pim_msdp_peer_active_connect: %d",
                           mp->key_str, rc);
        }

        switch (rc) {
        case connect_error:
        case -1:
                /* connect failed restart the connect-retry timer */
                pim_msdp_peer_cr_timer_setup(mp, true /* start */);
                break;

        case connect_success:
                /* connect was sucessful move to established */
                pim_msdp_peer_established(mp);
                break;

        case connect_in_progress:
                /* for NB content we need to wait till sock is readable or
                 * writeable */
                PIM_MSDP_PEER_WRITE_ON(mp);
                PIM_MSDP_PEER_READ_ON(mp);
                /* also restart connect-retry timer to reset the socket if
                 * connect is
                 * not sucessful */
                pim_msdp_peer_cr_timer_setup(mp, true /* start */);
                break;
        }
}

/* RFC-3618:Sec-5.6 - connection retry on active peer */
static int pim_msdp_peer_cr_timer_cb(struct thread *t)
{
        struct pim_msdp_peer *mp;

        mp = THREAD_ARG(t);

        if (PIM_DEBUG_MSDP_EVENTS) {
                pim_msdp_peer_timer_expiry_log(mp, "connect-retry");
        }

        if (mp->state != PIM_MSDP_CONNECTING || PIM_MSDP_PEER_IS_LISTENER(mp)) {
                return 0;
        }

        pim_msdp_peer_active_connect(mp);
        return 0;
}
static void pim_msdp_peer_cr_timer_setup(struct pim_msdp_peer *mp, bool start)
{
        THREAD_OFF(mp->cr_timer);
        if (start) {
                thread_add_timer(
                        mp->pim->msdp.master, pim_msdp_peer_cr_timer_cb, mp,
                        PIM_MSDP_PEER_CONNECT_RETRY_TIME, &mp->cr_timer);
        }
}

/* if a valid packet is rxed from the peer we can restart hold timer */
void pim_msdp_peer_pkt_rxed(struct pim_msdp_peer *mp)
{
        if (mp->state == PIM_MSDP_ESTABLISHED) {
                pim_msdp_peer_hold_timer_setup(mp, true /* start */);
        }
}

/* if a valid packet is txed to the peer we can restart ka timer and avoid
 * unnecessary ka noise in the network */
void pim_msdp_peer_pkt_txed(struct pim_msdp_peer *mp)
{
        if (mp->state == PIM_MSDP_ESTABLISHED) {
                pim_msdp_peer_ka_timer_setup(mp, true /* start */);
                if (PIM_DEBUG_MSDP_INTERNAL) {
                        zlog_debug("MSDP ka timer restart on pkt tx to %s",
                                   mp->key_str);
                }
        }
}

static void pim_msdp_addr2su(union sockunion *su, struct in_addr addr)
{
        sockunion_init(su);
        su->sin.sin_addr = addr;
        su->sin.sin_family = AF_INET;
#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
        su->sin.sin_len = sizeof(struct sockaddr_in);
#endif /* HAVE_STRUCT_SOCKADDR_IN_SIN_LEN */
}

/* 11.2.A1: create a new peer and transition state to listen or connecting */
static enum pim_msdp_err pim_msdp_peer_new(struct pim_instance *pim,
                                           struct in_addr peer_addr,
                                           struct in_addr local_addr,
                                           const char *mesh_group_name,
                                           struct pim_msdp_peer **mp_p)
{
        struct pim_msdp_peer *mp;

        pim_msdp_enable(pim);

        mp = XCALLOC(MTYPE_PIM_MSDP_PEER, sizeof(*mp));
        if (!mp) {
                zlog_err("%s: PIM XCALLOC(%zu) failure", __PRETTY_FUNCTION__,
                         sizeof(*mp));
                return PIM_MSDP_ERR_OOM;
        }

        mp->pim = pim;
        mp->peer = peer_addr;
        pim_inet4_dump("<peer?>", mp->peer, mp->key_str, sizeof(mp->key_str));
        pim_msdp_addr2su(&mp->su_peer, mp->peer);
        mp->local = local_addr;
        /* XXX: originator_id setting needs to move to the mesh group */
        pim->msdp.originator_id = local_addr;
        pim_msdp_addr2su(&mp->su_local, mp->local);
        mp->mesh_group_name = XSTRDUP(MTYPE_PIM_MSDP_MG_NAME, mesh_group_name);
        mp->state = PIM_MSDP_INACTIVE;
        mp->fd = -1;
        strcpy(mp->last_reset, "-");
        /* higher IP address is listener */
        if (ntohl(mp->local.s_addr) > ntohl(mp->peer.s_addr)) {
                mp->flags |= PIM_MSDP_PEERF_LISTENER;
        }

        /* setup packet buffers */
        mp->ibuf = stream_new(PIM_MSDP_MAX_PACKET_SIZE);
        mp->obuf = stream_fifo_new();

        /* insert into misc tables for easy access */
        mp = hash_get(pim->msdp.peer_hash, mp, hash_alloc_intern);
        listnode_add_sort(pim->msdp.peer_list, mp);

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP peer %s created", mp->key_str);

                pim_msdp_peer_state_chg_log(mp);
        }

        /* fireup the connect state machine */
        if (PIM_MSDP_PEER_IS_LISTENER(mp)) {
                pim_msdp_peer_listen(mp);
        } else {
                pim_msdp_peer_connect(mp);
        }
        if (mp_p) {
                *mp_p = mp;
        }
        return PIM_MSDP_ERR_NONE;
}

struct pim_msdp_peer *pim_msdp_peer_find(struct pim_instance *pim,
                                         struct in_addr peer_addr)
{
        struct pim_msdp_peer lookup;

        lookup.peer = peer_addr;
        return hash_lookup(pim->msdp.peer_hash, &lookup);
}

/* add peer configuration if it doesn't already exist */
enum pim_msdp_err pim_msdp_peer_add(struct pim_instance *pim,
                                    struct in_addr peer_addr,
                                    struct in_addr local_addr,
                                    const char *mesh_group_name,
                                    struct pim_msdp_peer **mp_p)
{
        struct pim_msdp_peer *mp;

        if (mp_p) {
                *mp_p = NULL;
        }

        if (peer_addr.s_addr == local_addr.s_addr) {
                /* skip session setup if config is invalid */
                if (PIM_DEBUG_MSDP_EVENTS) {
                        char peer_str[INET_ADDRSTRLEN];

                        pim_inet4_dump("<peer?>", peer_addr, peer_str,
                                       sizeof(peer_str));
                        zlog_debug("%s add skipped as DIP=SIP", peer_str);
                }
                return PIM_MSDP_ERR_SIP_EQ_DIP;
        }

        mp = pim_msdp_peer_find(pim, peer_addr);
        if (mp) {
                if (mp_p) {
                        *mp_p = mp;
                }
                return PIM_MSDP_ERR_PEER_EXISTS;
        }

        return pim_msdp_peer_new(pim, peer_addr, local_addr, mesh_group_name,
                                 mp_p);
}

/* release all mem associated with a peer */
static void pim_msdp_peer_free(struct pim_msdp_peer *mp)
{
        /*
         * Let's make sure we are not running when we delete
         * the underlying data structure
         */
        pim_msdp_peer_stop_tcp_conn(mp, false);

        if (mp->ibuf) {
                stream_free(mp->ibuf);
        }

        if (mp->obuf) {
                stream_fifo_free(mp->obuf);
        }

        if (mp->mesh_group_name) {
                XFREE(MTYPE_PIM_MSDP_MG_NAME, mp->mesh_group_name);
        }

        mp->pim = NULL;
        XFREE(MTYPE_PIM_MSDP_PEER, mp);
}

/* delete the peer config */
static enum pim_msdp_err pim_msdp_peer_do_del(struct pim_msdp_peer *mp)
{
        /* stop the tcp connection and shutdown all timers */
        pim_msdp_peer_stop_tcp_conn(mp, true /* chg_state */);

        /* remove the session from various tables */
        listnode_delete(mp->pim->msdp.peer_list, mp);
        hash_release(mp->pim->msdp.peer_hash, mp);

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP peer %s deleted", mp->key_str);
        }

        /* free up any associated memory */
        pim_msdp_peer_free(mp);

        return PIM_MSDP_ERR_NONE;
}

enum pim_msdp_err pim_msdp_peer_del(struct pim_instance *pim,
                                    struct in_addr peer_addr)
{
        struct pim_msdp_peer *mp;

        mp = pim_msdp_peer_find(pim, peer_addr);
        if (!mp) {
                return PIM_MSDP_ERR_NO_PEER;
        }

        return pim_msdp_peer_do_del(mp);
}

/* peer hash and peer list helpers */
static unsigned int pim_msdp_peer_hash_key_make(void *p)
{
        struct pim_msdp_peer *mp = p;
        return (jhash_1word(mp->peer.s_addr, 0));
}

static int pim_msdp_peer_hash_eq(const void *p1, const void *p2)
{
        const struct pim_msdp_peer *mp1 = p1;
        const struct pim_msdp_peer *mp2 = p2;

        return (mp1->peer.s_addr == mp2->peer.s_addr);
}

static int pim_msdp_peer_comp(const void *p1, const void *p2)
{
        const struct pim_msdp_peer *mp1 = p1;
        const struct pim_msdp_peer *mp2 = p2;

        if (ntohl(mp1->peer.s_addr) < ntohl(mp2->peer.s_addr))
                return -1;

        if (ntohl(mp1->peer.s_addr) > ntohl(mp2->peer.s_addr))
                return 1;

        return 0;
}

/************************** Mesh group management **************************/
static void pim_msdp_mg_free(struct pim_instance *pim, struct pim_msdp_mg *mg)
{
        /* If the mesh-group has valid member or src_ip don't delete it */
        if (!mg || mg->mbr_cnt || (mg->src_ip.s_addr != INADDR_ANY)) {
                return;
        }

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP mesh-group %s deleted", mg->mesh_group_name);
        }
        if (mg->mesh_group_name)
                XFREE(MTYPE_PIM_MSDP_MG_NAME, mg->mesh_group_name);

        if (mg->mbr_list)
                list_delete_and_null(&mg->mbr_list);

        XFREE(MTYPE_PIM_MSDP_MG, mg);
        pim->msdp.mg = NULL;
}

static struct pim_msdp_mg *pim_msdp_mg_new(const char *mesh_group_name)
{
        struct pim_msdp_mg *mg;

        mg = XCALLOC(MTYPE_PIM_MSDP_MG, sizeof(*mg));
        if (!mg) {
                zlog_err("%s: PIM XCALLOC(%zu) failure", __PRETTY_FUNCTION__,
                         sizeof(*mg));
                return NULL;
        }

        mg->mesh_group_name = XSTRDUP(MTYPE_PIM_MSDP_MG_NAME, mesh_group_name);
        mg->mbr_list = list_new();
        mg->mbr_list->del = (void (*)(void *))pim_msdp_mg_mbr_free;
        mg->mbr_list->cmp = (int (*)(void *, void *))pim_msdp_mg_mbr_comp;

        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP mesh-group %s created", mg->mesh_group_name);
        }
        return mg;
}

enum pim_msdp_err pim_msdp_mg_del(struct pim_instance *pim,
                                  const char *mesh_group_name)
{
        struct pim_msdp_mg *mg = pim->msdp.mg;
        struct pim_msdp_mg_mbr *mbr;

        if (!mg || strcmp(mg->mesh_group_name, mesh_group_name)) {
                return PIM_MSDP_ERR_NO_MG;
        }

        /* delete all the mesh-group members */
        while (!list_isempty(mg->mbr_list)) {
                mbr = listnode_head(mg->mbr_list);
                pim_msdp_mg_mbr_do_del(mg, mbr);
        }

        /* clear src ip */
        mg->src_ip.s_addr = INADDR_ANY;

        /* free up the mesh-group */
        pim_msdp_mg_free(pim, mg);
        return PIM_MSDP_ERR_NONE;
}

static enum pim_msdp_err pim_msdp_mg_add(struct pim_instance *pim,
                                         const char *mesh_group_name)
{
        if (pim->msdp.mg) {
                if (!strcmp(pim->msdp.mg->mesh_group_name, mesh_group_name)) {
                        return PIM_MSDP_ERR_NONE;
                }
                /* currently only one mesh-group can exist at a time */
                return PIM_MSDP_ERR_MAX_MESH_GROUPS;
        }

        pim->msdp.mg = pim_msdp_mg_new(mesh_group_name);
        if (!pim->msdp.mg) {
                return PIM_MSDP_ERR_OOM;
        }

        return PIM_MSDP_ERR_NONE;
}

static int pim_msdp_mg_mbr_comp(const void *p1, const void *p2)
{
        const struct pim_msdp_mg_mbr *mbr1 = p1;
        const struct pim_msdp_mg_mbr *mbr2 = p2;

        if (ntohl(mbr1->mbr_ip.s_addr) < ntohl(mbr2->mbr_ip.s_addr))
                return -1;

        if (ntohl(mbr1->mbr_ip.s_addr) > ntohl(mbr2->mbr_ip.s_addr))
                return 1;

        return 0;
}

static void pim_msdp_mg_mbr_free(struct pim_msdp_mg_mbr *mbr)
{
        XFREE(MTYPE_PIM_MSDP_MG_MBR, mbr);
}

static struct pim_msdp_mg_mbr *pim_msdp_mg_mbr_find(struct pim_instance *pim,
                                                    struct in_addr mbr_ip)
{
        struct pim_msdp_mg_mbr *mbr;
        struct listnode *mbr_node;

        if (!pim->msdp.mg) {
                return NULL;
        }
        /* we can move this to a hash but considering that number of peers in
         * a mesh-group that seems like bit of an overkill */
        for (ALL_LIST_ELEMENTS_RO(pim->msdp.mg->mbr_list, mbr_node, mbr)) {
                if (mbr->mbr_ip.s_addr == mbr_ip.s_addr) {
                        return mbr;
                }
        }
        return mbr;
}

enum pim_msdp_err pim_msdp_mg_mbr_add(struct pim_instance *pim,
                                      const char *mesh_group_name,
                                      struct in_addr mbr_ip)
{
        int rc;
        struct pim_msdp_mg_mbr *mbr;
        struct pim_msdp_mg *mg;

        rc = pim_msdp_mg_add(pim, mesh_group_name);
        if (rc != PIM_MSDP_ERR_NONE) {
                return rc;
        }

        mg = pim->msdp.mg;
        mbr = pim_msdp_mg_mbr_find(pim, mbr_ip);
        if (mbr) {
                return PIM_MSDP_ERR_MG_MBR_EXISTS;
        }

        mbr = XCALLOC(MTYPE_PIM_MSDP_MG_MBR, sizeof(*mbr));
        if (!mbr) {
                zlog_err("%s: PIM XCALLOC(%zu) failure", __PRETTY_FUNCTION__,
                         sizeof(*mbr));
                /* if there are no references to the mg free it */
                pim_msdp_mg_free(pim, mg);
                return PIM_MSDP_ERR_OOM;
        }
        mbr->mbr_ip = mbr_ip;
        listnode_add_sort(mg->mbr_list, mbr);

        /* if valid SIP has been configured add peer session */
        if (mg->src_ip.s_addr != INADDR_ANY) {
                pim_msdp_peer_add(pim, mbr_ip, mg->src_ip, mesh_group_name,
                                  &mbr->mp);
        }

        if (PIM_DEBUG_MSDP_EVENTS) {
                char ip_str[INET_ADDRSTRLEN];
                pim_inet4_dump("<mbr?>", mbr->mbr_ip, ip_str, sizeof(ip_str));
                zlog_debug("MSDP mesh-group %s mbr %s created",
                           mg->mesh_group_name, ip_str);
        }
        ++mg->mbr_cnt;
        return PIM_MSDP_ERR_NONE;
}

static void pim_msdp_mg_mbr_do_del(struct pim_msdp_mg *mg,
                                   struct pim_msdp_mg_mbr *mbr)
{
        /* Delete active peer session if any */
        if (mbr->mp) {
                pim_msdp_peer_do_del(mbr->mp);
        }

        listnode_delete(mg->mbr_list, mbr);
        if (PIM_DEBUG_MSDP_EVENTS) {
                char ip_str[INET_ADDRSTRLEN];
                pim_inet4_dump("<mbr?>", mbr->mbr_ip, ip_str, sizeof(ip_str));
                zlog_debug("MSDP mesh-group %s mbr %s deleted",
                           mg->mesh_group_name, ip_str);
        }
        pim_msdp_mg_mbr_free(mbr);
        if (mg->mbr_cnt) {
                --mg->mbr_cnt;
        }
}

enum pim_msdp_err pim_msdp_mg_mbr_del(struct pim_instance *pim,
                                      const char *mesh_group_name,
                                      struct in_addr mbr_ip)
{
        struct pim_msdp_mg_mbr *mbr;
        struct pim_msdp_mg *mg = pim->msdp.mg;

        if (!mg || strcmp(mg->mesh_group_name, mesh_group_name)) {
                return PIM_MSDP_ERR_NO_MG;
        }

        mbr = pim_msdp_mg_mbr_find(pim, mbr_ip);
        if (!mbr) {
                return PIM_MSDP_ERR_NO_MG_MBR;
        }

        pim_msdp_mg_mbr_do_del(mg, mbr);
        /* if there are no references to the mg free it */
        pim_msdp_mg_free(pim, mg);

        return PIM_MSDP_ERR_NONE;
}

static void pim_msdp_mg_src_do_del(struct pim_instance *pim)
{
        struct pim_msdp_mg_mbr *mbr;
        struct listnode *mbr_node;
        struct pim_msdp_mg *mg = pim->msdp.mg;

        /* SIP is being removed - tear down all active peer sessions */
        for (ALL_LIST_ELEMENTS_RO(mg->mbr_list, mbr_node, mbr)) {
                if (mbr->mp) {
                        pim_msdp_peer_do_del(mbr->mp);
                        mbr->mp = NULL;
                }
        }
        if (PIM_DEBUG_MSDP_EVENTS) {
                zlog_debug("MSDP mesh-group %s src cleared",
                           mg->mesh_group_name);
        }
}

enum pim_msdp_err pim_msdp_mg_src_del(struct pim_instance *pim,
                                      const char *mesh_group_name)
{
        struct pim_msdp_mg *mg = pim->msdp.mg;

        if (!mg || strcmp(mg->mesh_group_name, mesh_group_name)) {
                return PIM_MSDP_ERR_NO_MG;
        }

        if (mg->src_ip.s_addr != INADDR_ANY) {
                mg->src_ip.s_addr = INADDR_ANY;
                pim_msdp_mg_src_do_del(pim);
                /* if there are no references to the mg free it */
                pim_msdp_mg_free(pim, mg);
        }
        return PIM_MSDP_ERR_NONE;
}

enum pim_msdp_err pim_msdp_mg_src_add(struct pim_instance *pim,
                                      const char *mesh_group_name,
                                      struct in_addr src_ip)
{
        int rc;
        struct pim_msdp_mg_mbr *mbr;
        struct listnode *mbr_node;
        struct pim_msdp_mg *mg;

        if (src_ip.s_addr == INADDR_ANY) {
                pim_msdp_mg_src_del(pim, mesh_group_name);
                return PIM_MSDP_ERR_NONE;
        }

        rc = pim_msdp_mg_add(pim, mesh_group_name);
        if (rc != PIM_MSDP_ERR_NONE) {
                return rc;
        }

        mg = pim->msdp.mg;
        if (mg->src_ip.s_addr != INADDR_ANY) {
                pim_msdp_mg_src_do_del(pim);
        }
        mg->src_ip = src_ip;

        for (ALL_LIST_ELEMENTS_RO(mg->mbr_list, mbr_node, mbr)) {
                pim_msdp_peer_add(pim, mbr->mbr_ip, mg->src_ip, mesh_group_name,
                                  &mbr->mp);
        }

        if (PIM_DEBUG_MSDP_EVENTS) {
                char ip_str[INET_ADDRSTRLEN];
                pim_inet4_dump("<src?>", mg->src_ip, ip_str, sizeof(ip_str));
                zlog_debug("MSDP mesh-group %s src %s set", mg->mesh_group_name,
                           ip_str);
        }
        return PIM_MSDP_ERR_NONE;
}

/*********************** MSDP feature APIs *********************************/
int pim_msdp_config_write_helper(struct pim_instance *pim, struct vty *vty,
                                 const char *spaces)
{
        struct listnode *mbrnode;
        struct pim_msdp_mg_mbr *mbr;
        struct pim_msdp_mg *mg = pim->msdp.mg;
        char mbr_str[INET_ADDRSTRLEN];
        char src_str[INET_ADDRSTRLEN];
        int count = 0;

        if (!mg) {
                return count;
        }

        if (mg->src_ip.s_addr != INADDR_ANY) {
                pim_inet4_dump("<src?>", mg->src_ip, src_str, sizeof(src_str));
                vty_out(vty, "%sip msdp mesh-group %s source %s\n", spaces,
                        mg->mesh_group_name, src_str);
                ++count;
        }

        for (ALL_LIST_ELEMENTS_RO(mg->mbr_list, mbrnode, mbr)) {
                pim_inet4_dump("<mbr?>", mbr->mbr_ip, mbr_str, sizeof(mbr_str));
                vty_out(vty, "%sip msdp mesh-group %s member %s\n", spaces,
                        mg->mesh_group_name, mbr_str);
                ++count;
        }
        return count;
}

int pim_msdp_config_write(struct vty *vty)
{
        return pim_msdp_config_write_helper(pimg, vty, "");
}

/* Enable feature including active/periodic timers etc. on the first peer
 * config. Till then MSDP should just stay quiet. */
static void pim_msdp_enable(struct pim_instance *pim)
{
        if (pim->msdp.flags & PIM_MSDPF_ENABLE) {
                /* feature is already enabled */
                return;
        }
        pim->msdp.flags |= PIM_MSDPF_ENABLE;
        pim->msdp.work_obuf = stream_new(PIM_MSDP_MAX_PACKET_SIZE);
        pim_msdp_sa_adv_timer_setup(pim, true /* start */);
        /* setup sa cache based on local sources */
        pim_msdp_sa_local_setup(pim);
}

/* MSDP init */
void pim_msdp_init(struct pim_instance *pim, struct thread_master *master)
{
        pim->msdp.master = master;
        char hash_name[64];

        snprintf(hash_name, 64, "PIM %s MSDP Peer Hash", pim->vrf->name);
        pim->msdp.peer_hash = hash_create(pim_msdp_peer_hash_key_make,
                                          pim_msdp_peer_hash_eq, hash_name);
        pim->msdp.peer_list = list_new();
        pim->msdp.peer_list->del = (void (*)(void *))pim_msdp_peer_free;
        pim->msdp.peer_list->cmp = (int (*)(void *, void *))pim_msdp_peer_comp;

        snprintf(hash_name, 64, "PIM %s MSDP SA Hash", pim->vrf->name);
        pim->msdp.sa_hash = hash_create(pim_msdp_sa_hash_key_make,
                                        pim_msdp_sa_hash_eq, hash_name);
        pim->msdp.sa_list = list_new();
        pim->msdp.sa_list->del = (void (*)(void *))pim_msdp_sa_free;
        pim->msdp.sa_list->cmp = (int (*)(void *, void *))pim_msdp_sa_comp;
}

/* counterpart to MSDP init; XXX: unused currently */
void pim_msdp_exit(struct pim_instance *pim)
{
        pim_msdp_sa_adv_timer_setup(pim, false);

        /* XXX: stop listener and delete all peer sessions */

        if (pim->msdp.peer_hash) {
                hash_free(pim->msdp.peer_hash);
                pim->msdp.peer_hash = NULL;
        }

        if (pim->msdp.peer_list) {
                list_delete_and_null(&pim->msdp.peer_list);
        }

        if (pim->msdp.sa_hash) {
                hash_free(pim->msdp.sa_hash);
                pim->msdp.sa_hash = NULL;
        }

        if (pim->msdp.sa_list) {
                list_delete_and_null(&pim->msdp.sa_list);
        }
}