[mirror_frr.git] / pimd / pim_bsm.c

/*
 * pim_bsm.c: PIM BSM handling routines
 *
 * Copyright (C) 2018-19 Vmware, Inc.
 * Saravanan K
 *
 * 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
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "if.h"
#include "pimd.h"
#include "pim_iface.h"
#include "pim_instance.h"
#include "pim_neighbor.h"
#include "pim_rpf.h"
#include "pim_hello.h"
#include "pim_pim.h"
#include "pim_nht.h"
#include "pim_bsm.h"
#include "pim_time.h"

/* Functions forward declaration */
static void pim_bs_timer_start(struct bsm_scope *scope, int bs_timeout);
static void pim_g2rp_timer_start(struct bsm_rpinfo *bsrp, int hold_time);
static inline void pim_g2rp_timer_restart(struct bsm_rpinfo *bsrp,
					  int hold_time);

/* Memory Types */
DEFINE_MTYPE_STATIC(PIMD, PIM_BSGRP_NODE, "PIM BSR advertised grp info");
DEFINE_MTYPE_STATIC(PIMD, PIM_BSRP_INFO, "PIM BSR advertised RP info");
DEFINE_MTYPE_STATIC(PIMD, PIM_BSM_FRAG, "PIM BSM fragment");
DEFINE_MTYPE_STATIC(PIMD, PIM_BSM_PKT_VAR_MEM, "PIM BSM Packet");

/* All bsm packets forwarded shall be fit within ip mtu less iphdr(max) */
#define MAX_IP_HDR_LEN 24

/* pim_bsm_write_config - Write the interface pim bsm configuration.*/
void pim_bsm_write_config(struct vty *vty, struct interface *ifp)
{
	struct pim_interface *pim_ifp = ifp->info;

	if (pim_ifp) {
		if (!pim_ifp->bsm_enable)
			vty_out(vty, " no ip pim bsm\n");
		if (!pim_ifp->ucast_bsm_accept)
			vty_out(vty, " no ip pim unicast-bsm\n");
	}
}

static void pim_bsm_rpinfo_free(struct bsm_rpinfo *bsrp_info)
{
	THREAD_OFF(bsrp_info->g2rp_timer);
	XFREE(MTYPE_PIM_BSRP_INFO, bsrp_info);
}

void pim_bsm_rpinfos_free(struct bsm_rpinfos_head *head)
{
	struct bsm_rpinfo *bsrp_info;

	while ((bsrp_info = bsm_rpinfos_pop(head)))
		pim_bsm_rpinfo_free(bsrp_info);
}

void pim_free_bsgrp_data(struct bsgrp_node *bsgrp_node)
{
	pim_bsm_rpinfos_free(bsgrp_node->bsrp_list);
	pim_bsm_rpinfos_free(bsgrp_node->partial_bsrp_list);
	XFREE(MTYPE_PIM_BSGRP_NODE, bsgrp_node);
}

void pim_free_bsgrp_node(struct route_table *rt, struct prefix *grp)
{
	struct route_node *rn;

	rn = route_node_lookup(rt, grp);
	if (rn) {
		rn->info = NULL;
		route_unlock_node(rn);
		route_unlock_node(rn);
	}
}

static void pim_bsm_frag_free(struct bsm_frag *bsfrag)
{
	XFREE(MTYPE_PIM_BSM_FRAG, bsfrag);
}

void pim_bsm_frags_free(struct bsm_scope *scope)
{
	struct bsm_frag *bsfrag;

	while ((bsfrag = bsm_frags_pop(scope->bsm_frags)))
		pim_bsm_frag_free(bsfrag);
}

int pim_bsm_rpinfo_cmp(const struct bsm_rpinfo *node1,
		       const struct bsm_rpinfo *node2)
{
	/* RP election Algo :
	 * Step-1 : Loweset Rp priority  will have higher precedance.
	 * Step-2 : If priority same then higher hash val will have
	 *	    higher precedance.
	 * Step-3 : If Hash val is same then highest rp address will
	 *	    become elected RP.
	 */
	if (node1->rp_prio < node2->rp_prio)
		return -1;
	if (node1->rp_prio > node2->rp_prio)
		return 1;
	if (node1->hash < node2->hash)
		return 1;
	if (node1->hash > node2->hash)
		return -1;
	if (node1->rp_address.s_addr < node2->rp_address.s_addr)
		return 1;
	if (node1->rp_address.s_addr > node2->rp_address.s_addr)
		return -1;
	return 0;
}

static struct bsgrp_node *pim_bsm_new_bsgrp_node(struct route_table *rt,
						 struct prefix *grp)
{
	struct route_node *rn;
	struct bsgrp_node *bsgrp;

	rn = route_node_get(rt, grp);
	if (!rn) {
		zlog_warn("%s: route node creation failed", __func__);
		return NULL;
	}
	bsgrp = XCALLOC(MTYPE_PIM_BSGRP_NODE, sizeof(struct bsgrp_node));

	rn->info = bsgrp;
	bsm_rpinfos_init(bsgrp->bsrp_list);
	bsm_rpinfos_init(bsgrp->partial_bsrp_list);

	prefix_copy(&bsgrp->group, grp);
	return bsgrp;
}

static int pim_on_bs_timer(struct thread *t)
{
	struct route_node *rn;
	struct bsm_scope *scope;
	struct bsgrp_node *bsgrp_node;
	struct bsm_rpinfo *bsrp;
	struct prefix nht_p;
	bool is_bsr_tracking = true;

	scope = THREAD_ARG(t);
	THREAD_OFF(scope->bs_timer);

	if (PIM_DEBUG_BSM)
		zlog_debug("%s: Bootstrap Timer expired for scope: %d",
			   __func__, scope->sz_id);

	/* Remove next hop tracking for the bsr */
	nht_p.family = AF_INET;
	nht_p.prefixlen = IPV4_MAX_BITLEN;
	nht_p.u.prefix4 = scope->current_bsr;
	if (PIM_DEBUG_BSM)
		zlog_debug("%s: Deregister BSR addr %pFX with Zebra NHT",
			   __func__, &nht_p);
	pim_delete_tracked_nexthop(scope->pim, &nht_p, NULL, NULL,
				   is_bsr_tracking);

	/* Reset scope zone data */
	scope->accept_nofwd_bsm = false;
	scope->state = ACCEPT_ANY;
	scope->current_bsr.s_addr = INADDR_ANY;
	scope->current_bsr_prio = 0;
	scope->current_bsr_first_ts = 0;
	scope->current_bsr_last_ts = 0;
	scope->bsm_frag_tag = 0;
	pim_bsm_frags_free(scope);

	for (rn = route_top(scope->bsrp_table); rn; rn = route_next(rn)) {

		bsgrp_node = (struct bsgrp_node *)rn->info;
		if (!bsgrp_node) {
			if (PIM_DEBUG_BSM)
				zlog_debug("%s: bsgrp_node is null", __func__);
			continue;
		}
		/* Give grace time for rp to continue for another hold time */
		bsrp = bsm_rpinfos_first(bsgrp_node->bsrp_list);
		if (bsrp)
			pim_g2rp_timer_restart(bsrp, bsrp->rp_holdtime);

		/* clear pending list */
		pim_bsm_rpinfos_free(bsgrp_node->partial_bsrp_list);
		bsgrp_node->pend_rp_cnt = 0;
	}
	return 0;
}

void pim_bs_timer_stop(struct bsm_scope *scope)
{
	if (PIM_DEBUG_BSM)
		zlog_debug("%s : BS timer being stopped of sz: %d", __func__,
			   scope->sz_id);
	THREAD_OFF(scope->bs_timer);
}

static void pim_bs_timer_start(struct bsm_scope *scope, int bs_timeout)
{
	if (!scope) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s : Invalid scope(NULL).", __func__);
		return;
	}
	THREAD_OFF(scope->bs_timer);
	if (PIM_DEBUG_BSM)
		zlog_debug(
			"%s : starting bs timer for scope %d with timeout %d secs",
			__func__, scope->sz_id, bs_timeout);
	thread_add_timer(router->master, pim_on_bs_timer, scope, bs_timeout,
			 &scope->bs_timer);
}

static inline void pim_bs_timer_restart(struct bsm_scope *scope, int bs_timeout)
{
	pim_bs_timer_start(scope, bs_timeout);
}

void pim_bsm_proc_init(struct pim_instance *pim)
{
	memset(&pim->global_scope, 0, sizeof(struct bsm_scope));

	pim->global_scope.sz_id = PIM_GBL_SZ_ID;
	pim->global_scope.bsrp_table = route_table_init();
	pim->global_scope.accept_nofwd_bsm = true;
	pim->global_scope.state = NO_INFO;
	pim->global_scope.pim = pim;
	bsm_frags_init(pim->global_scope.bsm_frags);
	pim_bs_timer_start(&pim->global_scope, PIM_BS_TIME);
}

void pim_bsm_proc_free(struct pim_instance *pim)
{
	struct route_node *rn;
	struct bsgrp_node *bsgrp;

	pim_bs_timer_stop(&pim->global_scope);
	pim_bsm_frags_free(&pim->global_scope);

	for (rn = route_top(pim->global_scope.bsrp_table); rn;
	     rn = route_next(rn)) {
		bsgrp = rn->info;
		if (!bsgrp)
			continue;
		pim_free_bsgrp_data(bsgrp);
	}

	route_table_finish(pim->global_scope.bsrp_table);
}

static bool is_hold_time_elapsed(void *data)
{
	struct bsm_rpinfo *bsrp;

	bsrp = data;

	if (bsrp->elapse_time < bsrp->rp_holdtime)
		return false;
	else
		return true;
}

static int pim_on_g2rp_timer(struct thread *t)
{
	struct bsm_rpinfo *bsrp;
	struct bsm_rpinfo *bsrp_node;
	struct bsgrp_node *bsgrp_node;
	struct pim_instance *pim;
	struct rp_info *rp_info;
	struct route_node *rn;
	uint16_t elapse;
	struct in_addr bsrp_addr;

	bsrp = THREAD_ARG(t);
	THREAD_OFF(bsrp->g2rp_timer);
	bsgrp_node = bsrp->bsgrp_node;

	/* elapse time is the hold time of expired node */
	elapse = bsrp->rp_holdtime;
	bsrp_addr = bsrp->rp_address;

	/* update elapse for all bsrp nodes */
	frr_each_safe (bsm_rpinfos, bsgrp_node->bsrp_list, bsrp_node) {
		bsrp_node->elapse_time += elapse;

		if (is_hold_time_elapsed(bsrp_node)) {
			bsm_rpinfos_del(bsgrp_node->bsrp_list, bsrp_node);
			pim_bsm_rpinfo_free(bsrp_node);
		}
	}

	/* Get the next elected rp node */
	bsrp = bsm_rpinfos_first(bsgrp_node->bsrp_list);
	pim = bsgrp_node->scope->pim;
	rn = route_node_lookup(pim->rp_table, &bsgrp_node->group);

	if (!rn) {
		zlog_warn("%s: Route node doesn't exist", __func__);
		return 0;
	}

	rp_info = (struct rp_info *)rn->info;

	if (!rp_info) {
		route_unlock_node(rn);
		return 0;
	}

	if (rp_info->rp_src != RP_SRC_STATIC) {
		/* If new rp available, change it else delete the existing */
		if (bsrp) {
			bsrp_addr = bsrp->rp_address;
			pim_g2rp_timer_start(
				bsrp, (bsrp->rp_holdtime - bsrp->elapse_time));
			pim_rp_change(pim, bsrp_addr, bsgrp_node->group,
				      RP_SRC_BSR);
		} else {
			pim_rp_del(pim, bsrp_addr, bsgrp_node->group, NULL,
				   RP_SRC_BSR);
		}
	}

	if (!bsm_rpinfos_count(bsgrp_node->bsrp_list)
	    && !bsm_rpinfos_count(bsgrp_node->partial_bsrp_list)) {
		pim_free_bsgrp_node(pim->global_scope.bsrp_table,
				    &bsgrp_node->group);
		pim_free_bsgrp_data(bsgrp_node);
	}

	return 0;
}

static void pim_g2rp_timer_start(struct bsm_rpinfo *bsrp, int hold_time)
{
	if (!bsrp) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s : Invalid brsp(NULL).", __func__);
		return;
	}
	THREAD_OFF(bsrp->g2rp_timer);
	if (PIM_DEBUG_BSM)
		zlog_debug(
			"%s : starting g2rp timer for grp: %pFX - rp: %pI4 with timeout  %d secs(Actual Hold time : %d secs)",
			__func__, &bsrp->bsgrp_node->group,
			&bsrp->rp_address, hold_time,
			bsrp->rp_holdtime);

	thread_add_timer(router->master, pim_on_g2rp_timer, bsrp, hold_time,
			 &bsrp->g2rp_timer);
}

static inline void pim_g2rp_timer_restart(struct bsm_rpinfo *bsrp,
					  int hold_time)
{
	pim_g2rp_timer_start(bsrp, hold_time);
}

static void pim_g2rp_timer_stop(struct bsm_rpinfo *bsrp)
{
	if (!bsrp)
		return;

	if (PIM_DEBUG_BSM)
		zlog_debug("%s : stopping g2rp timer for grp: %pFX - rp: %pI4",
			   __func__, &bsrp->bsgrp_node->group,
			   &bsrp->rp_address);

	THREAD_OFF(bsrp->g2rp_timer);
}

static bool is_hold_time_zero(void *data)
{
	struct bsm_rpinfo *bsrp;

	bsrp = data;

	if (bsrp->rp_holdtime)
		return false;
	else
		return true;
}

static void pim_instate_pend_list(struct bsgrp_node *bsgrp_node)
{
	struct bsm_rpinfo *active;
	struct bsm_rpinfo *pend;
	struct rp_info *rp_info;
	struct route_node *rn;
	struct pim_instance *pim;
	struct rp_info *rp_all;
	struct prefix group_all;
	bool had_rp_node = true;

	pim = bsgrp_node->scope->pim;
	active = bsm_rpinfos_first(bsgrp_node->bsrp_list);

	/* Remove nodes with hold time 0 & check if list still has a head */
	frr_each_safe (bsm_rpinfos, bsgrp_node->partial_bsrp_list, pend) {
		if (is_hold_time_zero(pend)) {
			bsm_rpinfos_del(bsgrp_node->partial_bsrp_list, pend);
			pim_bsm_rpinfo_free(pend);
		}
	}

	pend = bsm_rpinfos_first(bsgrp_node->partial_bsrp_list);

	if (!str2prefix("224.0.0.0/4", &group_all))
		return;

	rp_all = pim_rp_find_match_group(pim, &group_all);
	rn = route_node_lookup(pim->rp_table, &bsgrp_node->group);

	if (pend)
		pim_g2rp_timer_start(pend, pend->rp_holdtime);

	/* if rp node doesn't exist or exist but not configured(rp_all),
	 * install the rp from head(if exists) of partial list. List is
	 * is sorted such that head is the elected RP for the group.
	 */
	if (!rn || (prefix_same(&rp_all->group, &bsgrp_node->group)
		    && pim_rpf_addr_is_inaddr_none(&rp_all->rp))) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Route node doesn't exist", __func__);
		if (pend)
			pim_rp_new(pim, pend->rp_address, bsgrp_node->group,
				   NULL, RP_SRC_BSR);
		had_rp_node = false;
	} else {
		rp_info = (struct rp_info *)rn->info;
		if (!rp_info) {
			route_unlock_node(rn);
			if (pend)
				pim_rp_new(pim, pend->rp_address,
					   bsgrp_node->group, NULL, RP_SRC_BSR);
			had_rp_node = false;
		}
	}

	/* We didn't have rp node and pending list is empty(unlikely), cleanup*/
	if ((!had_rp_node) && (!pend)) {
		pim_free_bsgrp_node(bsgrp_node->scope->bsrp_table,
				    &bsgrp_node->group);
		pim_free_bsgrp_data(bsgrp_node);
		return;
	}

	if ((had_rp_node) && (rp_info->rp_src != RP_SRC_STATIC)) {
		/* This means we searched and got rp node, needs unlock */
		route_unlock_node(rn);

		if (active && pend) {
			if ((active->rp_address.s_addr
			     != pend->rp_address.s_addr))
				pim_rp_change(pim, pend->rp_address,
					      bsgrp_node->group, RP_SRC_BSR);
		}

		/* Possible when the first BSM has group with 0 rp count */
		if ((!active) && (!pend)) {
			if (PIM_DEBUG_BSM) {
				zlog_debug(
					"%s: Both bsrp and partial list are empty",
					__func__);
			}
			pim_free_bsgrp_node(bsgrp_node->scope->bsrp_table,
					    &bsgrp_node->group);
			pim_free_bsgrp_data(bsgrp_node);
			return;
		}

		/* Possible when a group with 0 rp count received in BSM */
		if ((active) && (!pend)) {
			pim_rp_del(pim, active->rp_address, bsgrp_node->group,
				   NULL, RP_SRC_BSR);
			pim_free_bsgrp_node(bsgrp_node->scope->bsrp_table,
					    &bsgrp_node->group);
			if (PIM_DEBUG_BSM) {
				zlog_debug("%s:Pend List is null,del grp node",
					   __func__);
			}
			pim_free_bsgrp_data(bsgrp_node);
			return;
		}
	}

	if ((had_rp_node) && (rp_info->rp_src == RP_SRC_STATIC)) {
		/* We need to unlock rn this case */
		route_unlock_node(rn);
		/* there is a chance that static rp exist and bsrp cleaned
		 * so clean bsgrp node if pending list empty
		 */
		if (!pend) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s: Partial list is empty, static rp exists",
					__func__);
			pim_free_bsgrp_node(bsgrp_node->scope->bsrp_table,
					    &bsgrp_node->group);
			pim_free_bsgrp_data(bsgrp_node);
			return;
		}
	}

	/* swap the list & delete all nodes in partial list (old bsrp_list)
	 * before swap
	 *    active is head of bsrp list
	 *    pend is head of partial list
	 * After swap
	 *    active is head of partial list
	 *    pend is head of bsrp list
	 * So check appriate head after swap and clean the new partial list
	 */
	bsm_rpinfos_swap_all(bsgrp_node->bsrp_list,
			     bsgrp_node->partial_bsrp_list);

	if (active)
		pim_g2rp_timer_stop(active);
	pim_bsm_rpinfos_free(bsgrp_node->partial_bsrp_list);
}

static bool pim_bsr_rpf_check(struct pim_instance *pim, struct in_addr bsr,
			      struct in_addr ip_src_addr)
{
	struct pim_nexthop nexthop;
	int result;

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

	/* New BSR recived */
	if (bsr.s_addr != pim->global_scope.current_bsr.s_addr) {
		result = pim_nexthop_match(pim, bsr, ip_src_addr);

		/* Nexthop lookup pass for the new BSR address */
		if (result)
			return true;

		if (PIM_DEBUG_BSM) {
			char bsr_str[INET_ADDRSTRLEN];

			pim_inet4_dump("<bsr?>", bsr, bsr_str, sizeof(bsr_str));
			zlog_debug("%s : No route to BSR address %s", __func__,
				   bsr_str);
		}
		return false;
	}

	return pim_nexthop_match_nht_cache(pim, bsr, ip_src_addr);
}

static bool is_preferred_bsr(struct pim_instance *pim, struct in_addr bsr,
			     uint32_t bsr_prio)
{
	if (bsr.s_addr == pim->global_scope.current_bsr.s_addr)
		return true;

	if (bsr_prio > pim->global_scope.current_bsr_prio)
		return true;

	else if (bsr_prio == pim->global_scope.current_bsr_prio) {
		if (ntohl(bsr.s_addr)
		    >= ntohl(pim->global_scope.current_bsr.s_addr))
			return true;
		else
			return false;
	} else
		return false;
}

static void pim_bsm_update(struct pim_instance *pim, struct in_addr bsr,
			   uint32_t bsr_prio)
{
	struct pim_nexthop_cache pnc;

	if (bsr.s_addr != pim->global_scope.current_bsr.s_addr) {
		struct prefix nht_p;
		bool is_bsr_tracking = true;

		/* De-register old BSR and register new BSR with Zebra NHT */
		nht_p.family = AF_INET;
		nht_p.prefixlen = IPV4_MAX_BITLEN;

		if (pim->global_scope.current_bsr.s_addr != INADDR_ANY) {
			nht_p.u.prefix4 = pim->global_scope.current_bsr;
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s: Deregister BSR addr %pFX with Zebra NHT",
					__func__, &nht_p);
			pim_delete_tracked_nexthop(pim, &nht_p, NULL, NULL,
						   is_bsr_tracking);
		}

		nht_p.u.prefix4 = bsr;
		if (PIM_DEBUG_BSM)
			zlog_debug(
				"%s: NHT Register BSR addr %pFX with Zebra NHT",
				__func__, &nht_p);

		memset(&pnc, 0, sizeof(struct pim_nexthop_cache));
		pim_find_or_track_nexthop(pim, &nht_p, NULL, NULL,
					  is_bsr_tracking, &pnc);
		pim->global_scope.current_bsr = bsr;
		pim->global_scope.current_bsr_first_ts =
			pim_time_monotonic_sec();
		pim->global_scope.state = ACCEPT_PREFERRED;
	}
	pim->global_scope.current_bsr_prio = bsr_prio;
	pim->global_scope.current_bsr_last_ts = pim_time_monotonic_sec();
}

static bool pim_bsm_send_intf(uint8_t *buf, int len, struct interface *ifp,
			      struct in_addr dst_addr)
{
	struct pim_interface *pim_ifp;

	pim_ifp = ifp->info;

	if (!pim_ifp) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Pim interface not available for %s",
				   __func__, ifp->name);
		return false;
	}

	if (pim_ifp->pim_sock_fd == -1) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Pim sock not available for %s",
				   __func__, ifp->name);
		return false;
	}

	if (pim_msg_send(pim_ifp->pim_sock_fd, pim_ifp->primary_address,
			 dst_addr, buf, len, ifp->name)) {
		zlog_warn("%s: Could not send BSM message on interface: %s",
			  __func__, ifp->name);
		return false;
	}

	pim_ifp->pim_ifstat_bsm_tx++;
	pim_ifp->pim->bsm_sent++;
	return true;
}

static bool pim_bsm_frag_send(uint8_t *buf, uint32_t len, struct interface *ifp,
			      uint32_t pim_mtu, struct in_addr dst_addr,
			      bool no_fwd)
{
	struct bsmmsg_grpinfo *grpinfo, *curgrp;
	uint8_t *firstgrp_ptr;
	uint8_t *pkt;
	uint8_t *pak_start;
	uint32_t parsed_len = 0;
	uint32_t this_pkt_rem;
	uint32_t copy_byte_count;
	uint32_t this_pkt_len;
	uint8_t total_rp_cnt;
	uint8_t this_rp_cnt;
	uint8_t frag_rp_cnt;
	uint8_t rp_fit_cnt;
	bool pak_pending = false;

	/* MTU  passed here is PIM MTU (IP MTU less IP Hdr) */
	if (pim_mtu < (PIM_MIN_BSM_LEN)) {
		zlog_warn(
			"%s: mtu(pim mtu: %d) size less than minimum bootstrap len",
			__func__, pim_mtu);
		if (PIM_DEBUG_BSM)
			zlog_debug(
				"%s: mtu (pim mtu:%d) less than minimum bootstrap len",
				__func__, pim_mtu);
		return false;
	}

	pak_start = XCALLOC(MTYPE_PIM_BSM_PKT_VAR_MEM, pim_mtu);

	pkt = pak_start;

	/* Fill PIM header later before sending packet to calc checksum */
	pkt += PIM_MSG_HEADER_LEN;
	buf += PIM_MSG_HEADER_LEN;

	/* copy bsm header to new packet at offset of pim hdr */
	memcpy(pkt, buf, PIM_BSM_HDR_LEN);
	pkt += PIM_BSM_HDR_LEN;
	buf += PIM_BSM_HDR_LEN;
	parsed_len += (PIM_MSG_HEADER_LEN + PIM_BSM_HDR_LEN);

	/* Store the position of first grp ptr, which can be reused for
	 * next packet to start filling group. old bsm header and pim hdr
	 * remains. So need not be filled again for next packet onwards.
	 */
	firstgrp_ptr = pkt;

	/* we received mtu excluding IP hdr len as param
	 * now this_pkt_rem is mtu excluding
	 * PIM_BSM_HDR_LEN + PIM_MSG_HEADER_LEN
	 */
	this_pkt_rem = pim_mtu - (PIM_BSM_HDR_LEN + PIM_MSG_HEADER_LEN);

	/* For each group till the packet length parsed */
	while (parsed_len < len) {
		/* pkt            ---> fragment's current pointer
		 * buf            ---> input buffer's current pointer
		 * mtu            ---> size of the pim packet - PIM header
		 * curgrp         ---> current group on the fragment
		 * grpinfo        ---> current group on the input buffer
		 * this_pkt_rem   ---> bytes remaing on the current fragment
		 * rp_fit_cnt     ---> num of rp for current grp that
		 *                     fits this frag
		 * total_rp_cnt   ---> total rp present for the group in the buf
		 * frag_rp_cnt    ---> no of rp for the group to be fit in
		 *                     the frag
		 * this_rp_cnt    ---> how many rp have we parsed
		 */
		grpinfo = (struct bsmmsg_grpinfo *)buf;
		memcpy(pkt, buf, PIM_BSM_GRP_LEN);
		curgrp = (struct bsmmsg_grpinfo *)pkt;
		parsed_len += PIM_BSM_GRP_LEN;
		pkt += PIM_BSM_GRP_LEN;
		buf += PIM_BSM_GRP_LEN;
		this_pkt_rem -= PIM_BSM_GRP_LEN;

		/* initialize rp count and total_rp_cnt before the rp loop */
		this_rp_cnt = 0;
		total_rp_cnt = grpinfo->frag_rp_count;

		/* Loop till all RPs for the group parsed */
		while (this_rp_cnt < total_rp_cnt) {
			/* All RP from a group processed here.
			 * group is pointed by grpinfo.
			 * At this point make sure buf pointing to a RP
			 * within a group
			 */
			rp_fit_cnt = this_pkt_rem / PIM_BSM_RP_LEN;

			/* calculate how many rp am i going to copy in
			 * this frag
			 */
			if (rp_fit_cnt > (total_rp_cnt - this_rp_cnt))
				frag_rp_cnt = total_rp_cnt - this_rp_cnt;
			else
				frag_rp_cnt = rp_fit_cnt;

			/* populate the frag rp count for the current grp */
			curgrp->frag_rp_count = frag_rp_cnt;
			copy_byte_count = frag_rp_cnt * PIM_BSM_RP_LEN;

			/* copy all the rp that we are fitting in this
			 * frag for the grp
			 */
			memcpy(pkt, buf, copy_byte_count);
			this_rp_cnt += frag_rp_cnt;
			buf += copy_byte_count;
			pkt += copy_byte_count;
			parsed_len += copy_byte_count;
			this_pkt_rem -= copy_byte_count;

			/* Either we couldn't fit all rp for the group or the
			 * mtu reached
			 */
			if ((this_rp_cnt < total_rp_cnt)
			    || (this_pkt_rem
				< (PIM_BSM_GRP_LEN + PIM_BSM_RP_LEN))) {
				/* No space to fit in more rp, send this pkt */
				this_pkt_len = pim_mtu - this_pkt_rem;
				pim_msg_build_header(pak_start, this_pkt_len,
						     PIM_MSG_TYPE_BOOTSTRAP,
						     no_fwd);
				pim_bsm_send_intf(pak_start, this_pkt_len, ifp,
						  dst_addr);

				/* Construct next fragment. Reuse old packet */
				pkt = firstgrp_ptr;
				this_pkt_rem = pim_mtu - (PIM_BSM_HDR_LEN
							  + PIM_MSG_HEADER_LEN);

				/* If pkt can't accomodate next group + atleast
				 * one rp, we must break out of this inner loop
				 * and process next RP
				 */
				if (total_rp_cnt == this_rp_cnt)
					break;

				/* If some more RPs for the same group pending,
				 * fill grp hdr
				 */
				memcpy(pkt, (uint8_t *)grpinfo,
				       PIM_BSM_GRP_LEN);
				curgrp = (struct bsmmsg_grpinfo *)pkt;
				pkt += PIM_BSM_GRP_LEN;
				this_pkt_rem -= PIM_BSM_GRP_LEN;
				pak_pending = false;
			} else {
				/* We filled something but not yet sent out */
				pak_pending = true;
			}
		} /* while RP count */
	}	 /*while parsed len */

	/* Send if we have any unsent packet */
	if (pak_pending) {
		this_pkt_len = pim_mtu - this_pkt_rem;
		pim_msg_build_header(pak_start, this_pkt_len,
				     PIM_MSG_TYPE_BOOTSTRAP, no_fwd);
		pim_bsm_send_intf(pak_start, (pim_mtu - this_pkt_rem), ifp,
				  dst_addr);
	}
	XFREE(MTYPE_PIM_BSM_PKT_VAR_MEM, pak_start);
	return true;
}

static void pim_bsm_fwd_whole_sz(struct pim_instance *pim, uint8_t *buf,
				 uint32_t len, int sz)
{
	struct interface *ifp;
	struct pim_interface *pim_ifp;
	struct in_addr dst_addr;
	uint32_t pim_mtu;
	bool no_fwd = false;
	bool ret = false;

	/* For now only global scope zone is supported, so send on all
	 * pim interfaces in the vrf
	 */
	dst_addr = qpim_all_pim_routers_addr;
	FOR_ALL_INTERFACES (pim->vrf, ifp) {
		pim_ifp = ifp->info;
		if ((!pim_ifp) || (!pim_ifp->bsm_enable))
			continue;

		/*
		 * RFC 5059 Sec 3.4:
		 * When a Bootstrap message is forwarded, it is forwarded out
		 * of every multicast-capable interface that has PIM neighbors.
		 *
		 * So skipping pim interfaces with no neighbors.
		 */
		if (listcount(pim_ifp->pim_neighbor_list) == 0)
			continue;

		pim_hello_require(ifp);
		pim_mtu = ifp->mtu - MAX_IP_HDR_LEN;
		if (pim_mtu < len) {
			ret = pim_bsm_frag_send(buf, len, ifp, pim_mtu,
						dst_addr, no_fwd);
			if (PIM_DEBUG_BSM)
				zlog_debug("%s: pim_bsm_frag_send returned %s",
					   __func__, ret ? "TRUE" : "FALSE");
		} else {
			pim_msg_build_header(buf, len, PIM_MSG_TYPE_BOOTSTRAP,
					     no_fwd);
			if (!pim_bsm_send_intf(buf, len, ifp, dst_addr)) {
				if (PIM_DEBUG_BSM)
					zlog_debug(
						"%s: pim_bsm_send_intf returned false",
						__func__);
			}
		}
	}
}

bool pim_bsm_new_nbr_fwd(struct pim_neighbor *neigh, struct interface *ifp)
{
	struct in_addr dst_addr;
	struct pim_interface *pim_ifp;
	struct bsm_scope *scope;
	struct bsm_frag *bsfrag;
	char neigh_src_str[INET_ADDRSTRLEN];
	uint32_t pim_mtu;
	bool no_fwd = true;
	bool ret = false;

	if (PIM_DEBUG_BSM) {
		pim_inet4_dump("<src?>", neigh->source_addr, neigh_src_str,
			       sizeof(neigh_src_str));
		zlog_debug("%s: New neighbor %s seen on %s", __func__,
			   neigh_src_str, ifp->name);
	}

	pim_ifp = ifp->info;

	/* DR only forwards BSM packet */
	if (pim_ifp->pim_dr_addr.s_addr == pim_ifp->primary_address.s_addr) {
		if (PIM_DEBUG_BSM)
			zlog_debug(
				"%s: It is not DR, so don't forward BSM packet",
				__func__);
	}

	if (!pim_ifp->bsm_enable) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: BSM proc not enabled on %s", __func__,
				   ifp->name);
		return ret;
	}

	scope = &pim_ifp->pim->global_scope;

	if (!bsm_frags_count(scope->bsm_frags)) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: BSM list for the scope is empty",
				   __func__);
		return ret;
	}

	if (!pim_ifp->ucast_bsm_accept) {
		dst_addr = qpim_all_pim_routers_addr;
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Sending BSM mcast to %s", __func__,
				   neigh_src_str);
	} else {
		dst_addr = neigh->source_addr;
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Sending BSM ucast to %s", __func__,
				   neigh_src_str);
	}
	pim_mtu = ifp->mtu - MAX_IP_HDR_LEN;
	pim_hello_require(ifp);

	frr_each (bsm_frags, scope->bsm_frags, bsfrag) {
		if (pim_mtu < bsfrag->size) {
			ret = pim_bsm_frag_send(bsfrag->data, bsfrag->size, ifp,
						pim_mtu, dst_addr, no_fwd);
			if (!ret) {
				if (PIM_DEBUG_BSM)
					zlog_debug(
						"%s: pim_bsm_frag_send failed",
						__func__);
			}
		} else {
			/* Pim header needs to be constructed */
			pim_msg_build_header(bsfrag->data, bsfrag->size,
					     PIM_MSG_TYPE_BOOTSTRAP, no_fwd);
			ret = pim_bsm_send_intf(bsfrag->data, bsfrag->size, ifp,
						dst_addr);
			if (!ret) {
				if (PIM_DEBUG_BSM)
					zlog_debug(
						"%s: pim_bsm_frag_send failed",
						__func__);
			}
		}
	}
	return ret;
}

struct bsgrp_node *pim_bsm_get_bsgrp_node(struct bsm_scope *scope,
					  struct prefix *grp)
{
	struct route_node *rn;
	struct bsgrp_node *bsgrp;

	rn = route_node_lookup(scope->bsrp_table, grp);
	if (!rn) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: Route node doesn't exist for the group",
				   __func__);
		return NULL;
	}
	bsgrp = rn->info;
	route_unlock_node(rn);

	return bsgrp;
}

static uint32_t hash_calc_on_grp_rp(struct prefix group, struct in_addr rp,
				    uint8_t hashmasklen)
{
	uint64_t temp;
	uint32_t hash;
	uint32_t grpaddr;
	uint32_t rp_add;
	uint32_t mask = 0xffffffff;

	/* mask to be made zero if hashmasklen is 0 because mask << 32
	 * may not give 0. hashmasklen can be 0 to 32.
	 */
	if (hashmasklen == 0)
		mask = 0;

	/* in_addr stores ip in big endian, hence network byte order
	 * convert to uint32 before processing hash
	 */
	grpaddr = ntohl(group.u.prefix4.s_addr);
	/* Avoid shifting by 32 bit on a 32 bit register */
	if (hashmasklen)
		grpaddr = grpaddr & ((mask << (32 - hashmasklen)));
	else
		grpaddr = grpaddr & mask;
	rp_add = ntohl(rp.s_addr);
	temp = 1103515245 * ((1103515245 * (uint64_t)grpaddr + 12345) ^ rp_add)
	       + 12345;
	hash = temp & (0x7fffffff);
	return hash;
}

static bool pim_install_bsm_grp_rp(struct pim_instance *pim,
				   struct bsgrp_node *grpnode,
				   struct bsmmsg_rpinfo *rp)
{
	struct bsm_rpinfo *bsm_rpinfo;
	uint8_t hashMask_len = pim->global_scope.hashMasklen;

	/*memory allocation for bsm_rpinfo */
	bsm_rpinfo = XCALLOC(MTYPE_PIM_BSRP_INFO, sizeof(*bsm_rpinfo));

	bsm_rpinfo->rp_prio = rp->rp_pri;
	bsm_rpinfo->rp_holdtime = rp->rp_holdtime;
	memcpy(&bsm_rpinfo->rp_address, &rp->rpaddr.addr,
	       sizeof(struct in_addr));
	bsm_rpinfo->elapse_time = 0;

	/* Back pointer to the group node. */
	bsm_rpinfo->bsgrp_node = grpnode;

	/* update hash for this rp node */
	bsm_rpinfo->hash = hash_calc_on_grp_rp(grpnode->group, rp->rpaddr.addr,
					       hashMask_len);
	if (bsm_rpinfos_add(grpnode->partial_bsrp_list, bsm_rpinfo) == NULL) {
		if (PIM_DEBUG_BSM)
			zlog_debug(
				"%s, bs_rpinfo node added to the partial bs_rplist.",
				__func__);
		return true;
	}

	if (PIM_DEBUG_BSM)
		zlog_debug("%s: list node not added", __func__);

	XFREE(MTYPE_PIM_BSRP_INFO, bsm_rpinfo);
	return false;
}

static void pim_update_pending_rp_cnt(struct bsm_scope *sz,
				      struct bsgrp_node *bsgrp,
				      uint16_t bsm_frag_tag,
				      uint32_t total_rp_count)
{
	if (bsgrp->pend_rp_cnt) {
		/* received bsm is different packet ,
		 * it is not same fragment.
		 */
		if (bsm_frag_tag != bsgrp->frag_tag) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s,Received a new BSM ,so clear the pending bs_rpinfo list.",
					__func__);
			pim_bsm_rpinfos_free(bsgrp->partial_bsrp_list);
			bsgrp->pend_rp_cnt = total_rp_count;
		}
	} else
		bsgrp->pend_rp_cnt = total_rp_count;

	bsgrp->frag_tag = bsm_frag_tag;
}

/* Parsing BSR packet and adding to partial list of corresponding bsgrp node */
static bool pim_bsm_parse_install_g2rp(struct bsm_scope *scope, uint8_t *buf,
				       int buflen, uint16_t bsm_frag_tag)
{
	struct bsmmsg_grpinfo grpinfo;
	struct bsmmsg_rpinfo rpinfo;
	struct prefix group;
	struct bsgrp_node *bsgrp = NULL;
	int frag_rp_cnt = 0;
	int offset = 0;
	int ins_count = 0;

	while (buflen > offset) {
		if (offset + (int)sizeof(struct bsmmsg_grpinfo) > buflen) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s: buflen received %d is less than the internal data structure of the packet would suggest",
					__func__, buflen);
			return false;
		}
		/* Extract Group tlv from BSM */
		memcpy(&grpinfo, buf, sizeof(struct bsmmsg_grpinfo));

		if (PIM_DEBUG_BSM) {
			char grp_str[INET_ADDRSTRLEN];

			pim_inet4_dump("<Group?>", grpinfo.group.addr, grp_str,
				       sizeof(grp_str));
			zlog_debug(
				"%s, Group %s  Rpcount:%d Fragment-Rp-count:%d",
				__func__, grp_str, grpinfo.rp_count,
				grpinfo.frag_rp_count);
		}

		buf += sizeof(struct bsmmsg_grpinfo);
		offset += sizeof(struct bsmmsg_grpinfo);

		if (grpinfo.rp_count == 0) {
			if (PIM_DEBUG_BSM) {
				char grp_str[INET_ADDRSTRLEN];

				pim_inet4_dump("<Group?>", grpinfo.group.addr,
					       grp_str, sizeof(grp_str));
				zlog_debug("%s, Rp count is zero for group: %s",
					   __func__, grp_str);
			}
			return false;
		}

		group.family = AF_INET;
		if (grpinfo.group.mask > IPV4_MAX_BITLEN) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s, v4 prefix length specified: %d is too long",
					__func__, grpinfo.group.mask);
			return false;
		}
		group.prefixlen = grpinfo.group.mask;
		group.u.prefix4.s_addr = grpinfo.group.addr.s_addr;

		/* Get the Group node for the BSM rp table */
		bsgrp = pim_bsm_get_bsgrp_node(scope, &group);

		if (!bsgrp) {
			if (PIM_DEBUG_BSM)
				zlog_debug("%s, Create new  BSM Group node.",
					   __func__);

			/* create a new node to be added to the tree. */
			bsgrp = pim_bsm_new_bsgrp_node(scope->bsrp_table,
						       &group);

			if (!bsgrp) {
				zlog_debug(
					"%s, Failed to get the BSM group node.",
					__func__);
				continue;
			}

			bsgrp->scope = scope;
		}

		pim_update_pending_rp_cnt(scope, bsgrp, bsm_frag_tag,
					  grpinfo.rp_count);
		frag_rp_cnt = grpinfo.frag_rp_count;
		ins_count = 0;

		while (frag_rp_cnt--) {
			if (offset + (int)sizeof(struct bsmmsg_rpinfo)
			    > buflen) {
				if (PIM_DEBUG_BSM)
					zlog_debug(
						"%s, buflen received: %u is less than the internal data structure of the packet would suggest",
						__func__, buflen);
				return false;
			}

			/* Extract RP address tlv from BSM */
			memcpy(&rpinfo, buf, sizeof(struct bsmmsg_rpinfo));
			rpinfo.rp_holdtime = ntohs(rpinfo.rp_holdtime);
			buf += sizeof(struct bsmmsg_rpinfo);
			offset += sizeof(struct bsmmsg_rpinfo);

			if (PIM_DEBUG_BSM) {
				char rp_str[INET_ADDRSTRLEN];

				pim_inet4_dump("<Rpaddr?>", rpinfo.rpaddr.addr,
					       rp_str, sizeof(rp_str));
				zlog_debug(
					"%s, Rp address - %s; pri:%d hold:%d",
					__func__, rp_str, rpinfo.rp_pri,
					rpinfo.rp_holdtime);
			}

			/* Call Install api to update grp-rp mappings */
			if (pim_install_bsm_grp_rp(scope->pim, bsgrp, &rpinfo))
				ins_count++;
		}

		bsgrp->pend_rp_cnt -= ins_count;

		if (!bsgrp->pend_rp_cnt) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s, Recvd all the rps for this group, so bsrp list with penidng rp list.",
					__func__);
			/* replace the bsrp_list with pending list */
			pim_instate_pend_list(bsgrp);
		}
	}
	return true;
}

int pim_bsm_process(struct interface *ifp, struct ip *ip_hdr, uint8_t *buf,
		    uint32_t buf_size, bool no_fwd)
{
	struct bsm_hdr *bshdr;
	int sz = PIM_GBL_SZ_ID;
	struct bsmmsg_grpinfo *msg_grp;
	struct pim_interface *pim_ifp = NULL;
	struct bsm_frag *bsfrag;
	struct pim_instance *pim;
	char bsr_str[INET_ADDRSTRLEN];
	uint16_t frag_tag;
	bool empty_bsm = false;

	/* BSM Packet acceptance validation */
	pim_ifp = ifp->info;
	if (!pim_ifp) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s: multicast not enabled on interface %s",
				   __func__, ifp->name);
		return -1;
	}

	pim_ifp->pim_ifstat_bsm_rx++;
	pim = pim_ifp->pim;
	pim->bsm_rcvd++;

	/* Drop if bsm processing is disabled on interface */
	if (!pim_ifp->bsm_enable) {
		zlog_warn("%s: BSM not enabled on interface %s", __func__,
			  ifp->name);
		pim_ifp->pim_ifstat_bsm_cfg_miss++;
		pim->bsm_dropped++;
		return -1;
	}

	if (buf_size < (PIM_MSG_HEADER_LEN + sizeof(struct bsm_hdr))) {
		if (PIM_DEBUG_BSM)
			zlog_debug(
				"%s: received buffer length of %d which is too small to properly decode",
				__func__, buf_size);
		return -1;
	}

	bshdr = (struct bsm_hdr *)(buf + PIM_MSG_HEADER_LEN);
	pim_inet4_dump("<bsr?>", bshdr->bsr_addr.addr, bsr_str,
		       sizeof(bsr_str));
	if (bshdr->hm_len > IPV4_MAX_BITLEN) {
		zlog_warn("Bad hashmask length for IPv4; got %hhu, expected value in range 0-32",
			  bshdr->hm_len);
		pim->bsm_dropped++;
		return -1;
	}
	pim->global_scope.hashMasklen = bshdr->hm_len;
	frag_tag = ntohs(bshdr->frag_tag);

	/* Identify empty BSM */
	if ((buf_size - PIM_BSM_HDR_LEN - PIM_MSG_HEADER_LEN) < PIM_BSM_GRP_LEN)
		empty_bsm = true;

	if (!empty_bsm) {
		msg_grp = (struct bsmmsg_grpinfo *)(buf + PIM_MSG_HEADER_LEN
						    + PIM_BSM_HDR_LEN);
		/* Currently we don't support scope zoned BSM */
		if (msg_grp->group.sz) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s : Administratively scoped range BSM received",
					__func__);
			pim_ifp->pim_ifstat_bsm_invalid_sz++;
			pim->bsm_dropped++;
			return -1;
		}
	}

	/* Drop if bsr is not preferred bsr */
	if (!is_preferred_bsr(pim, bshdr->bsr_addr.addr, bshdr->bsr_prio)) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s : Received a non-preferred BSM",
				   __func__);
		pim->bsm_dropped++;
		return -1;
	}

	if (no_fwd) {
		/* only accept no-forward BSM if quick refresh on startup */
		if ((pim->global_scope.accept_nofwd_bsm)
		    || (frag_tag == pim->global_scope.bsm_frag_tag)) {
			pim->global_scope.accept_nofwd_bsm = false;
		} else {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s : nofwd_bsm received on %s when accpt_nofwd_bsm false",
					__func__, bsr_str);
			pim->bsm_dropped++;
			pim_ifp->pim_ifstat_ucast_bsm_cfg_miss++;
			return -1;
		}
	}

	/* Mulicast BSM received */
	if (ip_hdr->ip_dst.s_addr == qpim_all_pim_routers_addr.s_addr) {
		if (!no_fwd) {
			if (!pim_bsr_rpf_check(pim, bshdr->bsr_addr.addr,
					       ip_hdr->ip_src)) {
				if (PIM_DEBUG_BSM)
					zlog_debug(
						"%s : RPF check fail for BSR address %s",
						__func__, bsr_str);
				pim->bsm_dropped++;
				return -1;
			}
		}
	} else if (if_address_is_local(&ip_hdr->ip_dst, AF_INET,
				       pim->vrf->vrf_id)) {
		/* Unicast BSM received - if ucast bsm not enabled on
		 * the interface, drop it
		 */
		if (!pim_ifp->ucast_bsm_accept) {
			if (PIM_DEBUG_BSM)
				zlog_debug(
					"%s : Unicast BSM not enabled on interface %s",
					__func__, ifp->name);
			pim_ifp->pim_ifstat_ucast_bsm_cfg_miss++;
			pim->bsm_dropped++;
			return -1;
		}

	} else {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s : Invalid destination address",
				   __func__);
		pim->bsm_dropped++;
		return -1;
	}

	if (empty_bsm) {
		if (PIM_DEBUG_BSM)
			zlog_debug("%s : Empty Pref BSM received", __func__);
	}
	/* Parse Update bsm rp table and install/uninstall rp if required */
	if (!pim_bsm_parse_install_g2rp(
		    &pim_ifp->pim->global_scope,
		    (buf + PIM_BSM_HDR_LEN + PIM_MSG_HEADER_LEN),
		    (buf_size - PIM_BSM_HDR_LEN - PIM_MSG_HEADER_LEN),
		    frag_tag)) {
		if (PIM_DEBUG_BSM) {
			zlog_debug("%s, Parsing BSM failed.", __func__);
		}
		pim->bsm_dropped++;
		return -1;
	}
	/* Restart the bootstrap timer */
	pim_bs_timer_restart(&pim_ifp->pim->global_scope,
			     PIM_BSR_DEFAULT_TIMEOUT);

	/* If new BSM received, clear the old bsm database */
	if (pim_ifp->pim->global_scope.bsm_frag_tag != frag_tag) {
		if (PIM_DEBUG_BSM) {
			zlog_debug("%s: Current frag tag: %d Frag teg rcvd: %d",
				   __func__,
				   pim_ifp->pim->global_scope.bsm_frag_tag,
				   frag_tag);
		}
		pim_bsm_frags_free(&pim_ifp->pim->global_scope);
		pim_ifp->pim->global_scope.bsm_frag_tag = frag_tag;
	}

	/* update the scope information from bsm */
	pim_bsm_update(pim, bshdr->bsr_addr.addr, bshdr->bsr_prio);

	if (!no_fwd) {
		pim_bsm_fwd_whole_sz(pim_ifp->pim, buf, buf_size, sz);
		bsfrag = XCALLOC(MTYPE_PIM_BSM_FRAG,
				 sizeof(struct bsm_frag) + buf_size);

		bsfrag->size = buf_size;
		memcpy(bsfrag->data, buf, buf_size);
		bsm_frags_add_tail(pim_ifp->pim->global_scope.bsm_frags,
				   bsfrag);
	}

	return 0;
}