[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_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(void);
static void pim_msdp_sa_adv_timer_setup(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)
{
  msdp->sa_adv_timer = NULL;
  if (PIM_DEBUG_MSDP_EVENTS) {
    zlog_debug("MSDP SA advertisment timer expired");
  }

  pim_msdp_sa_adv_timer_setup(true /* start */);
  pim_msdp_pkt_sa_tx();
  return 0;
}
static void
pim_msdp_sa_adv_timer_setup(bool start)
{
  THREAD_OFF(msdp->sa_adv_timer);
  if (start) {
    thread_add_timer(msdp->master, pim_msdp_sa_adv_timer_cb, NULL,
                     PIM_MSDP_SA_ADVERTISMENT_TIME, &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);
  sa->sa_state_timer = NULL;

  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(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(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->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(&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->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->sg, NULL /* iif */,
                        PIM_UPSTREAM_FLAG_MASK_SRC_MSDP,
                        __PRETTY_FUNCTION__);

  sa->up = up;
  if (up) {
    /* update inherited oil */
    pim_upstream_inherited_olist(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)
{
  XFREE(MTYPE_PIM_MSDP_SA, sa);
}

static struct pim_msdp_sa *
pim_msdp_sa_new(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->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(msdp->sa_hash, sa, hash_alloc_intern);
  if (!sa) {
    zlog_err("%s: PIM hash get failure", __PRETTY_FUNCTION__);
    pim_msdp_sa_free(sa);
    return NULL;
  }
  listnode_add_sort(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 prefix_sg *sg)
{
  struct pim_msdp_sa lookup;

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

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

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

  return pim_msdp_sa_new(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(msdp->sa_list, sa);
  hash_release(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->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 (msdp->local_cnt)
        --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_msdp_peer *mp, struct prefix_sg *sg,
                struct in_addr rp)
{
  struct pim_msdp_sa *sa;

  sa = pim_msdp_sa_add(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;
      ++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)
{
  if (!(msdp->flags & PIM_MSDPF_ENABLE)) {
    return false;
  }

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

  if (!I_am_RP(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 prefix_sg *sg)
{
  struct in_addr rp;
  rp.s_addr = 0;
  pim_msdp_sa_ref(NULL /* mp */, sg, rp);
}

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

  sa = pim_msdp_sa_find(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 prefix_sg *sg)
{
  struct pim_msdp_sa *sa;

  sa = pim_msdp_sa_find(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)
{
  if (pim_msdp_sa_local_add_ok(up)) {
    pim_msdp_sa_local_add(&up->sg);
  } else {
    pim_msdp_sa_local_del(&up->sg);
  }
}

static void
pim_msdp_sa_local_setup(void)
{
  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(void)
{
  struct listnode *sanode;
  struct listnode *nextnode;
  struct pim_msdp_sa *sa;

  if (!(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(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();

  for (ALL_LIST_ELEMENTS(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_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(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 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(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 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(sg);
  } else {
    pim_msdp_sa_local_del_on_up_del(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();
}

/* 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);
  mp->hold_timer = NULL;

  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)
{
  THREAD_OFF(mp->hold_timer);
  if (start) {
    thread_add_timer(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);
  mp->ka_timer = NULL;

  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(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);
  mp->cr_timer = NULL;

  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(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 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();

  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->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 */
  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(msdp->peer_hash, mp, hash_alloc_intern);
  listnode_add_sort(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 in_addr peer_addr)
{
  struct pim_msdp_peer lookup;

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

/* add peer configuration if it doesn't already exist */
enum pim_msdp_err
pim_msdp_peer_add(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(peer_addr);
  if (mp) {
    if (mp_p) {
      *mp_p = mp;
    }
    return PIM_MSDP_ERR_PEER_EXISTS;
  }

  return pim_msdp_peer_new(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)
{
  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);
  }
  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(msdp->peer_list, mp);
  hash_release(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 in_addr peer_addr)
{
  struct pim_msdp_peer *mp;

  mp = pim_msdp_peer_find(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_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_free(mg->mbr_list);

  XFREE(MTYPE_PIM_MSDP_MG, mg);
  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(const char *mesh_group_name)
{
  struct pim_msdp_mg *mg = 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(mg);
  return PIM_MSDP_ERR_NONE;
}

static enum pim_msdp_err
pim_msdp_mg_add(const char *mesh_group_name)
{
  if (msdp->mg) {
    if (!strcmp(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;
  }

  msdp->mg = pim_msdp_mg_new(mesh_group_name);
  if (!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 in_addr mbr_ip)
{
  struct pim_msdp_mg_mbr *mbr;
  struct listnode *mbr_node;

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

  mg = msdp->mg;
  mbr = pim_msdp_mg_mbr_find(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(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(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(const char *mesh_group_name, struct in_addr mbr_ip)
{
  struct pim_msdp_mg_mbr *mbr;
  struct pim_msdp_mg *mg = msdp->mg;

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

  mbr = pim_msdp_mg_mbr_find(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(mg);

  return PIM_MSDP_ERR_NONE;
}

static void
pim_msdp_mg_src_do_del(void)
{
  struct pim_msdp_mg_mbr *mbr;
  struct listnode *mbr_node;
  struct pim_msdp_mg *mg = 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(const char *mesh_group_name)
{
  struct pim_msdp_mg *mg = 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();
    /* if there are no references to the mg free it */
    pim_msdp_mg_free(mg);
  }
  return PIM_MSDP_ERR_NONE;
}

enum pim_msdp_err
pim_msdp_mg_src_add(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(mesh_group_name);
    return PIM_MSDP_ERR_NONE;
  }

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

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

  for (ALL_LIST_ELEMENTS_RO(mg->mbr_list, mbr_node, mbr)) {
    pim_msdp_peer_add(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(struct vty *vty)
{
  struct listnode *mbrnode;
  struct pim_msdp_mg_mbr *mbr;
  struct pim_msdp_mg *mg = 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, "ip msdp mesh-group %s source %s%s",
        mg->mesh_group_name, src_str, VTY_NEWLINE);
    ++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, "ip msdp mesh-group %s member %s%s",
        mg->mesh_group_name, mbr_str, VTY_NEWLINE);
    ++count;
  }
  return count;
}

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

/* MSDP init */
void
pim_msdp_init(struct thread_master *master)
{
  msdp->master = master;

  msdp->peer_hash = hash_create(pim_msdp_peer_hash_key_make,
                                 pim_msdp_peer_hash_eq);
  msdp->peer_list = list_new();
  msdp->peer_list->del = (void (*)(void *))pim_msdp_peer_free;
  msdp->peer_list->cmp = (int (*)(void *, void *))pim_msdp_peer_comp;

  msdp->sa_hash = hash_create(pim_msdp_sa_hash_key_make,
                                 pim_msdp_sa_hash_eq);
  msdp->sa_list = list_new();
  msdp->sa_list->del = (void (*)(void *))pim_msdp_sa_free;
  msdp->sa_list->cmp = (int (*)(void *, void *))pim_msdp_sa_comp;
}

/* counterpart to MSDP init; XXX: unused currently */
void
pim_msdp_exit(void)
{
  /* XXX: stop listener and delete all peer sessions */

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

  if (msdp->peer_list) {
    list_free(msdp->peer_list);
    msdp->peer_list = NULL;
  }
}