[mirror_frr.git] / bgpd / bgp_updgrp_packet.c

/**
 * bgp_updgrp_packet.c: BGP update group packet handling routines
 *
 * @copyright Copyright (C) 2014 Cumulus Networks, Inc.
 *
 * @author Avneesh Sachdev <avneesh@sproute.net>
 * @author Rajesh Varadarajan <rajesh@sproute.net>
 * @author Pradosh Mohapatra <pradosh@sproute.net>
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * GNU Zebra is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>

#include "prefix.h"
#include "thread.h"
#include "buffer.h"
#include "stream.h"
#include "command.h"
#include "sockunion.h"
#include "network.h"
#include "memory.h"
#include "filter.h"
#include "routemap.h"
#include "log.h"
#include "plist.h"
#include "linklist.h"
#include "workqueue.h"
#include "hash.h"
#include "queue.h"
#include "mpls.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_errors.h"
#include "bgpd/bgp_fsm.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_packet.h"
#include "bgpd/bgp_advertise.h"
#include "bgpd/bgp_updgrp.h"
#include "bgpd/bgp_nexthop.h"
#include "bgpd/bgp_nht.h"
#include "bgpd/bgp_mplsvpn.h"
#include "bgpd/bgp_label.h"
#include "bgpd/bgp_addpath.h"

/********************
 * PRIVATE FUNCTIONS
 ********************/

/********************
 * PUBLIC FUNCTIONS
 ********************/
struct bpacket *bpacket_alloc(void)
{
	struct bpacket *pkt;

	pkt = XCALLOC(MTYPE_BGP_PACKET, sizeof(struct bpacket));

	return pkt;
}

void bpacket_free(struct bpacket *pkt)
{
	if (pkt->buffer)
		stream_free(pkt->buffer);
	pkt->buffer = NULL;
	XFREE(MTYPE_BGP_PACKET, pkt);
}

void bpacket_queue_init(struct bpacket_queue *q)
{
	TAILQ_INIT(&(q->pkts));
}

/*
 * bpacket_queue_sanity_check
 */
void bpacket_queue_sanity_check(struct bpacket_queue __attribute__((__unused__))
				* q)
{
#if 0
  struct bpacket *pkt;

  pkt = bpacket_queue_last (q);
  assert (pkt);
  assert (!pkt->buffer);

  /*
   * Make sure the count of packets is correct.
   */
  int num_pkts = 0;

  pkt = bpacket_queue_first (q);
  while (pkt)
    {
      num_pkts++;

      if (num_pkts > q->curr_count)
	assert (0);

      pkt = TAILQ_NEXT (pkt, pkt_train);
    }

  assert (num_pkts == q->curr_count);
#endif
}

/*
 * bpacket_queue_add_packet
 *
 * Internal function of bpacket_queue - and adds a
 * packet entry to the end of the list.
 *
 * Users of bpacket_queue should use bpacket_queue_add instead.
 */
static void bpacket_queue_add_packet(struct bpacket_queue *q,
				     struct bpacket *pkt)
{
	struct bpacket *last_pkt;

	if (TAILQ_EMPTY(&(q->pkts)))
		TAILQ_INSERT_TAIL(&(q->pkts), pkt, pkt_train);
	else {
		last_pkt = bpacket_queue_last(q);
		TAILQ_INSERT_AFTER(&(q->pkts), last_pkt, pkt, pkt_train);
	}
	q->curr_count++;
	if (q->hwm_count < q->curr_count)
		q->hwm_count = q->curr_count;
}

/*
 * Adds a packet to the bpacket_queue.
 *
 * The stream passed is consumed by this function. So, the caller should
 * not free or use the stream after
 * invoking this function.
 */
struct bpacket *bpacket_queue_add(struct bpacket_queue *q, struct stream *s,
				  struct bpacket_attr_vec_arr *vecarrp)
{
	struct bpacket *pkt;
	struct bpacket *last_pkt;


	pkt = bpacket_alloc();
	if (TAILQ_EMPTY(&(q->pkts))) {
		pkt->ver = 1;
		pkt->buffer = s;
		if (vecarrp)
			memcpy(&pkt->arr, vecarrp,
			       sizeof(struct bpacket_attr_vec_arr));
		else
			bpacket_attr_vec_arr_reset(&pkt->arr);
		bpacket_queue_add_packet(q, pkt);
		bpacket_queue_sanity_check(q);
		return pkt;
	}

	/*
	 * Fill in the new information into the current sentinel and create a
	 * new sentinel.
	 */
	bpacket_queue_sanity_check(q);
	last_pkt = bpacket_queue_last(q);
	assert(last_pkt->buffer == NULL);
	last_pkt->buffer = s;
	if (vecarrp)
		memcpy(&last_pkt->arr, vecarrp,
		       sizeof(struct bpacket_attr_vec_arr));
	else
		bpacket_attr_vec_arr_reset(&last_pkt->arr);

	pkt->ver = last_pkt->ver;
	pkt->ver++;
	bpacket_queue_add_packet(q, pkt);

	bpacket_queue_sanity_check(q);
	return last_pkt;
}

struct bpacket *bpacket_queue_first(struct bpacket_queue *q)
{
	return (TAILQ_FIRST(&(q->pkts)));
}

struct bpacket *bpacket_queue_last(struct bpacket_queue *q)
{
	return TAILQ_LAST(&(q->pkts), pkt_queue);
}

struct bpacket *bpacket_queue_remove(struct bpacket_queue *q)
{
	struct bpacket *first;

	first = bpacket_queue_first(q);
	if (first) {
		TAILQ_REMOVE(&(q->pkts), first, pkt_train);
		q->curr_count--;
	}
	return first;
}

unsigned int bpacket_queue_length(struct bpacket_queue *q)
{
	return q->curr_count - 1;
}

unsigned int bpacket_queue_hwm_length(struct bpacket_queue *q)
{
	return q->hwm_count - 1;
}

int bpacket_queue_is_full(struct bgp *bgp, struct bpacket_queue *q)
{
	if (q->curr_count >= bgp->default_subgroup_pkt_queue_max)
		return 1;
	return 0;
}

void bpacket_add_peer(struct bpacket *pkt, struct peer_af *paf)
{
	if (!pkt || !paf)
		return;

	LIST_INSERT_HEAD(&(pkt->peers), paf, pkt_train);
	paf->next_pkt_to_send = pkt;
}

/*
 * bpacket_queue_cleanup
 */
void bpacket_queue_cleanup(struct bpacket_queue *q)
{
	struct bpacket *pkt;

	while ((pkt = bpacket_queue_remove(q))) {
		bpacket_free(pkt);
	}
}

/*
 * bpacket_queue_compact
 *
 * Delete packets that do not need to be transmitted to any peer from
 * the queue.
 *
 * @return the number of packets deleted.
 */
static int bpacket_queue_compact(struct bpacket_queue *q)
{
	int num_deleted;
	struct bpacket *pkt, *removed_pkt;

	num_deleted = 0;

	while (1) {
		pkt = bpacket_queue_first(q);
		if (!pkt)
			break;

		/*
		 * Don't delete the sentinel.
		 */
		if (!pkt->buffer)
			break;

		if (!LIST_EMPTY(&(pkt->peers)))
			break;

		removed_pkt = bpacket_queue_remove(q);
		assert(pkt == removed_pkt);
		bpacket_free(removed_pkt);

		num_deleted++;
	}

	bpacket_queue_sanity_check(q);
	return num_deleted;
}

void bpacket_queue_advance_peer(struct peer_af *paf)
{
	struct bpacket *pkt;
	struct bpacket *old_pkt;

	old_pkt = paf->next_pkt_to_send;
	if (old_pkt->buffer == NULL)
		/* Already at end of list */
		return;

	LIST_REMOVE(paf, pkt_train);
	pkt = TAILQ_NEXT(old_pkt, pkt_train);
	bpacket_add_peer(pkt, paf);

	if (!bpacket_queue_compact(PAF_PKTQ(paf)))
		return;

	/*
	 * Deleted one or more packets. Check if we can now merge this
	 * peer's subgroup into another subgroup.
	 */
	update_subgroup_check_merge(paf->subgroup, "advanced peer in queue");
}

/*
 * bpacket_queue_remove_peer
 *
 * Remove the peer from the packet queue of the subgroup it belongs
 * to.
 */
void bpacket_queue_remove_peer(struct peer_af *paf)
{
	struct bpacket_queue *q;

	q = PAF_PKTQ(paf);
	assert(q);
	if (!q)
		return;

	LIST_REMOVE(paf, pkt_train);
	paf->next_pkt_to_send = NULL;

	bpacket_queue_compact(q);
}

unsigned int bpacket_queue_virtual_length(struct peer_af *paf)
{
	struct bpacket *pkt;
	struct bpacket *last;
	struct bpacket_queue *q;

	pkt = paf->next_pkt_to_send;
	if (!pkt || (pkt->buffer == NULL))
		/* Already at end of list */
		return 0;

	q = PAF_PKTQ(paf);
	if (TAILQ_EMPTY(&(q->pkts)))
		return 0;

	last = TAILQ_LAST(&(q->pkts), pkt_queue);
	if (last->ver >= pkt->ver)
		return last->ver - pkt->ver;

	/* sequence # rolled over */
	return (UINT_MAX - pkt->ver + 1) + last->ver;
}

/*
 * Dump the bpacket queue
 */
void bpacket_queue_show_vty(struct bpacket_queue *q, struct vty *vty)
{
	struct bpacket *pkt;
	struct peer_af *paf;

	pkt = bpacket_queue_first(q);
	while (pkt) {
		vty_out(vty, "  Packet %p ver %u buffer %p\n", pkt, pkt->ver,
			pkt->buffer);

		LIST_FOREACH (paf, &(pkt->peers), pkt_train) {
			vty_out(vty, "      - %s\n", paf->peer->host);
		}
		pkt = bpacket_next(pkt);
	}
	return;
}

struct stream *bpacket_reformat_for_peer(struct bpacket *pkt,
					 struct peer_af *paf)
{
	struct stream *s = NULL;
	bpacket_attr_vec *vec;
	struct peer *peer;
	char buf[BUFSIZ];
	char buf2[BUFSIZ];
	struct bgp_filter *filter;

	s = stream_dup(pkt->buffer);
	peer = PAF_PEER(paf);

	vec = &pkt->arr.entries[BGP_ATTR_VEC_NH];
	if (CHECK_FLAG(vec->flags, BPKT_ATTRVEC_FLAGS_UPDATED)) {
		uint8_t nhlen;
		afi_t nhafi;
		int route_map_sets_nh;
		nhlen = stream_getc_from(s, vec->offset);
		filter = &peer->filter[paf->afi][paf->safi];

		if (peer_cap_enhe(peer, paf->afi, paf->safi))
			nhafi = AFI_IP6;
		else
			nhafi = BGP_NEXTHOP_AFI_FROM_NHLEN(nhlen);

		if (nhafi == AFI_IP) {
			struct in_addr v4nh, *mod_v4nh;
			int nh_modified = 0;
			size_t offset_nh = vec->offset + 1;

			route_map_sets_nh =
				(CHECK_FLAG(
					 vec->flags,
					 BPKT_ATTRVEC_FLAGS_RMAP_IPV4_NH_CHANGED)
				 || CHECK_FLAG(
					    vec->flags,
					    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));

			switch (nhlen) {
			case BGP_ATTR_NHLEN_IPV4:
				break;
			case BGP_ATTR_NHLEN_VPNV4:
				offset_nh += 8;
				break;
			default:
				/* TODO: handle IPv6 nexthops */
				flog_warn(
					EC_BGP_INVALID_NEXTHOP_LENGTH,
					"%s: %s: invalid MP nexthop length (AFI IP): %u",
					__func__, peer->host, nhlen);
				stream_free(s);
				return NULL;
			}

			stream_get_from(&v4nh, s, offset_nh, IPV4_MAX_BYTELEN);
			mod_v4nh = &v4nh;

			/*
			 * If route-map has set the nexthop, that is normally
			 * used; if it is specified as peer-address, the peering
			 * address is picked up. Otherwise, if NH is unavailable
			 * from attribute, the peering addr is picked up; the
			 * "NH unavailable" case also covers next-hop-self and
			 * some other scenarios - see subgroup_announce_check().
			 * In all other cases, use the nexthop carried in the
			 * attribute unless it is EBGP non-multiaccess and there
			 * is no next-hop-unchanged setting or the peer is EBGP
			 * and the route-map that changed the next-hop value
			 * was applied inbound rather than outbound. Updates to
			 * an EBGP peer should only modify the next-hop if it
			 * was set in an outbound route-map to that peer.
			 * Note: It is assumed route-map cannot set the nexthop
			 * to an invalid value.
			 */
			if (route_map_sets_nh
			    && ((peer->sort != BGP_PEER_EBGP)
				|| ROUTE_MAP_OUT(filter))) {
				if (CHECK_FLAG(
					    vec->flags,
					    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS)) {
					mod_v4nh = &peer->nexthop.v4;
					nh_modified = 1;
				}
			} else if (!v4nh.s_addr) {
				mod_v4nh = &peer->nexthop.v4;
				nh_modified = 1;
			} else if (
				peer->sort == BGP_PEER_EBGP
				&& (bgp_multiaccess_check_v4(v4nh, peer) == 0)
				&& !CHECK_FLAG(
					   vec->flags,
					   BPKT_ATTRVEC_FLAGS_RMAP_NH_UNCHANGED)
				&& !peer_af_flag_check(
					   peer, paf->afi, paf->safi,
					   PEER_FLAG_NEXTHOP_UNCHANGED)) {
				/* NOTE: not handling case where NH has new AFI
				 */
				mod_v4nh = &peer->nexthop.v4;
				nh_modified = 1;
			}

			if (nh_modified) /* allow for VPN RD */
				stream_put_in_addr_at(s, offset_nh, mod_v4nh);

			if (bgp_debug_update(peer, NULL, NULL, 0))
				zlog_debug("u%" PRIu64 ":s%" PRIu64
					   " %s send UPDATE w/ nexthop %s%s",
					   PAF_SUBGRP(paf)->update_group->id,
					   PAF_SUBGRP(paf)->id, peer->host,
					   inet_ntoa(*mod_v4nh),
					   (nhlen == 12 ? " and RD" : ""));
		} else if (nhafi == AFI_IP6) {
			struct in6_addr v6nhglobal, *mod_v6nhg;
			struct in6_addr v6nhlocal, *mod_v6nhl;
			int gnh_modified, lnh_modified;
			size_t offset_nhglobal = vec->offset + 1;
			size_t offset_nhlocal = vec->offset + 1;

			gnh_modified = lnh_modified = 0;
			mod_v6nhg = &v6nhglobal;
			mod_v6nhl = &v6nhlocal;

			route_map_sets_nh =
				(CHECK_FLAG(
					 vec->flags,
					 BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED)
				 || CHECK_FLAG(
					    vec->flags,
					    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));

			/*
			 * The logic here is rather similar to that for IPv4,
			 * the
			 * additional work being to handle 1 or 2 nexthops.
			 * Also, 3rd
			 * party nexthop is not propagated for EBGP right now.
			 */
			switch (nhlen) {
			case BGP_ATTR_NHLEN_IPV6_GLOBAL:
				break;
			case BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL:
				offset_nhlocal += IPV6_MAX_BYTELEN;
				break;
			case BGP_ATTR_NHLEN_VPNV6_GLOBAL:
				offset_nhglobal += 8;
				break;
			case BGP_ATTR_NHLEN_VPNV6_GLOBAL_AND_LL:
				offset_nhglobal += 8;
				offset_nhlocal += 8 * 2 + IPV6_MAX_BYTELEN;
				break;
			default:
				/* TODO: handle IPv4 nexthops */
				flog_warn(
					EC_BGP_INVALID_NEXTHOP_LENGTH,
					"%s: %s: invalid MP nexthop length (AFI IP6): %u",
					__func__, peer->host, nhlen);
				stream_free(s);
				return NULL;
			}

			stream_get_from(&v6nhglobal, s, offset_nhglobal,
					IPV6_MAX_BYTELEN);

			/*
			 * Updates to an EBGP peer should only modify the
			 * next-hop if it was set in an outbound route-map
			 * to that peer.
			 */
			if (route_map_sets_nh
			    && ((peer->sort != BGP_PEER_EBGP)
				|| ROUTE_MAP_OUT(filter))) {
				if (CHECK_FLAG(
					    vec->flags,
					    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS)) {
					mod_v6nhg = &peer->nexthop.v6_global;
					gnh_modified = 1;
				}
			} else if (IN6_IS_ADDR_UNSPECIFIED(&v6nhglobal)) {
				mod_v6nhg = &peer->nexthop.v6_global;
				gnh_modified = 1;
			} else if (
				(peer->sort == BGP_PEER_EBGP)
				&& (!bgp_multiaccess_check_v6(v6nhglobal, peer))
				&& !CHECK_FLAG(vec->flags,
					   BPKT_ATTRVEC_FLAGS_RMAP_NH_UNCHANGED)
				&& !peer_af_flag_check(
					   peer, nhafi, paf->safi,
					   PEER_FLAG_NEXTHOP_UNCHANGED)) {
				/* NOTE: not handling case where NH has new AFI
				 */
				mod_v6nhg = &peer->nexthop.v6_global;
				gnh_modified = 1;
			}


			if (nhlen == BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL
			    || nhlen == BGP_ATTR_NHLEN_VPNV6_GLOBAL_AND_LL) {
				stream_get_from(&v6nhlocal, s, offset_nhlocal,
						IPV6_MAX_BYTELEN);
				if (IN6_IS_ADDR_UNSPECIFIED(&v6nhlocal)) {
					mod_v6nhl = &peer->nexthop.v6_local;
					lnh_modified = 1;
				}
			}

			if (gnh_modified)
				stream_put_in6_addr_at(s, offset_nhglobal,
						       mod_v6nhg);
			if (lnh_modified)
				stream_put_in6_addr_at(s, offset_nhlocal,
						       mod_v6nhl);

			if (bgp_debug_update(peer, NULL, NULL, 0)) {
				if (nhlen == 32 || nhlen == 48)
					zlog_debug(
						"u%" PRIu64 ":s%" PRIu64
						" %s send UPDATE w/ mp_nexthops %s, %s%s",
						PAF_SUBGRP(paf)
							->update_group->id,
						PAF_SUBGRP(paf)->id, peer->host,
						inet_ntop(AF_INET6, mod_v6nhg,
							  buf, BUFSIZ),
						inet_ntop(AF_INET6, mod_v6nhl,
							  buf2, BUFSIZ),
						(nhlen == 48 ? " and RD" : ""));
				else
					zlog_debug(
						"u%" PRIu64 ":s%" PRIu64
						" %s send UPDATE w/ mp_nexthop %s%s",
						PAF_SUBGRP(paf)
							->update_group->id,
						PAF_SUBGRP(paf)->id, peer->host,
						inet_ntop(AF_INET6, mod_v6nhg,
							  buf, BUFSIZ),
						(nhlen == 24 ? " and RD" : ""));
			}
		} else if (paf->afi == AFI_L2VPN) {
			struct in_addr v4nh, *mod_v4nh;
			int nh_modified = 0;

			stream_get_from(&v4nh, s, vec->offset + 1, 4);
			mod_v4nh = &v4nh;

			/* No route-map changes allowed for EVPN nexthops. */
			if (!v4nh.s_addr) {
				mod_v4nh = &peer->nexthop.v4;
				nh_modified = 1;
			}

			if (nh_modified)
				stream_put_in_addr_at(s, vec->offset + 1,
						      mod_v4nh);

			if (bgp_debug_update(peer, NULL, NULL, 0))
				zlog_debug("u%" PRIu64 ":s%" PRIu64
					   " %s send UPDATE w/ nexthop %s",
					   PAF_SUBGRP(paf)->update_group->id,
					   PAF_SUBGRP(paf)->id, peer->host,
					   inet_ntoa(*mod_v4nh));
		}
	}

	return s;
}

/*
 * Update the vecarr offsets to go beyond 'pos' bytes, i.e. add 'pos'
 * to each offset.
 */
static void bpacket_attr_vec_arr_update(struct bpacket_attr_vec_arr *vecarr,
					size_t pos)
{
	int i;

	if (!vecarr)
		return;

	for (i = 0; i < BGP_ATTR_VEC_MAX; i++)
		vecarr->entries[i].offset += pos;
}

/*
 * Return if there are packets to build for this subgroup.
 */
int subgroup_packets_to_build(struct update_subgroup *subgrp)
{
	struct bgp_advertise *adv;

	if (!subgrp)
		return 0;

	adv = bgp_adv_fifo_first(&subgrp->sync->withdraw);
	if (adv)
		return 1;

	adv = bgp_adv_fifo_first(&subgrp->sync->update);
	if (adv)
		return 1;

	return 0;
}

/* Make BGP update packet.  */
struct bpacket *subgroup_update_packet(struct update_subgroup *subgrp)
{
	struct bpacket_attr_vec_arr vecarr;
	struct bpacket *pkt;
	struct peer *peer;
	struct stream *s;
	struct stream *snlri;
	struct stream *packet;
	struct bgp_adj_out *adj;
	struct bgp_advertise *adv;
	struct bgp_node *rn = NULL;
	struct bgp_path_info *path = NULL;
	bgp_size_t total_attr_len = 0;
	unsigned long attrlen_pos = 0;
	size_t mpattrlen_pos = 0;
	size_t mpattr_pos = 0;
	afi_t afi;
	safi_t safi;
	int space_remaining = 0;
	int space_needed = 0;
	char send_attr_str[BUFSIZ];
	int send_attr_printed = 0;
	int num_pfx = 0;
	int addpath_encode = 0;
	int addpath_overhead = 0;
	uint32_t addpath_tx_id = 0;
	struct prefix_rd *prd = NULL;
	mpls_label_t label = MPLS_INVALID_LABEL, *label_pnt = NULL;
	uint32_t num_labels = 0;

	if (!subgrp)
		return NULL;

	if (bpacket_queue_is_full(SUBGRP_INST(subgrp), SUBGRP_PKTQ(subgrp)))
		return NULL;

	peer = SUBGRP_PEER(subgrp);
	afi = SUBGRP_AFI(subgrp);
	safi = SUBGRP_SAFI(subgrp);
	s = subgrp->work;
	stream_reset(s);
	snlri = subgrp->scratch;
	stream_reset(snlri);

	bpacket_attr_vec_arr_reset(&vecarr);

	addpath_encode = bgp_addpath_encode_tx(peer, afi, safi);
	addpath_overhead = addpath_encode ? BGP_ADDPATH_ID_LEN : 0;

	adv = bgp_adv_fifo_first(&subgrp->sync->update);
	while (adv) {
		assert(adv->rn);
		rn = adv->rn;
		adj = adv->adj;
		addpath_tx_id = adj->addpath_tx_id;
		path = adv->pathi;

		space_remaining = STREAM_CONCAT_REMAIN(s, snlri, STREAM_SIZE(s))
				  - BGP_MAX_PACKET_SIZE_OVERFLOW;
		space_needed =
			BGP_NLRI_LENGTH + addpath_overhead
			+ bgp_packet_mpattr_prefix_size(afi, safi, &rn->p);

		/* When remaining space can't include NLRI and it's length.  */
		if (space_remaining < space_needed)
			break;

		/* If packet is empty, set attribute. */
		if (stream_empty(s)) {
			struct peer *from = NULL;

			if (path)
				from = path->peer;

			/* 1: Write the BGP message header - 16 bytes marker, 2
			 * bytes length,
			 * one byte message type.
			 */
			bgp_packet_set_marker(s, BGP_MSG_UPDATE);

			/* 2: withdrawn routes length */
			stream_putw(s, 0);

			/* 3: total attributes length - attrlen_pos stores the
			 * position */
			attrlen_pos = stream_get_endp(s);
			stream_putw(s, 0);

			/* 4: if there is MP_REACH_NLRI attribute, that should
			 * be the first
			 * attribute, according to
			 * draft-ietf-idr-error-handling. Save the
			 * position.
			 */
			mpattr_pos = stream_get_endp(s);

			/* 5: Encode all the attributes, except MP_REACH_NLRI
			 * attr. */
			total_attr_len = bgp_packet_attribute(
				NULL, peer, s, adv->baa->attr, &vecarr, NULL,
				afi, safi, from, NULL, NULL, 0, 0, 0);

			space_remaining =
				STREAM_CONCAT_REMAIN(s, snlri, STREAM_SIZE(s))
				- BGP_MAX_PACKET_SIZE_OVERFLOW;
			space_needed = BGP_NLRI_LENGTH + addpath_overhead
				       + bgp_packet_mpattr_prefix_size(
						 afi, safi, &rn->p);

			/* If the attributes alone do not leave any room for
			 * NLRI then
			 * return */
			if (space_remaining < space_needed) {
				flog_err(
					EC_BGP_UPDGRP_ATTR_LEN,
					"u%" PRIu64 ":s%" PRIu64
					" attributes too long, cannot send UPDATE",
					subgrp->update_group->id, subgrp->id);

				/* Flush the FIFO update queue */
				while (adv)
					adv = bgp_advertise_clean_subgroup(
						subgrp, adj);
				return NULL;
			}

			if (BGP_DEBUG(update, UPDATE_OUT)
			    || BGP_DEBUG(update, UPDATE_PREFIX)) {
				memset(send_attr_str, 0, BUFSIZ);
				send_attr_printed = 0;
				bgp_dump_attr(adv->baa->attr, send_attr_str,
					      BUFSIZ);
			}
		}

		if ((afi == AFI_IP && safi == SAFI_UNICAST)
		    && !peer_cap_enhe(peer, afi, safi))
			stream_put_prefix_addpath(s, &rn->p, addpath_encode,
						  addpath_tx_id);
		else {
			/* Encode the prefix in MP_REACH_NLRI attribute */
			if (rn->prn)
				prd = (struct prefix_rd *)&rn->prn->p;

			if (safi == SAFI_LABELED_UNICAST) {
				label = bgp_adv_label(rn, path, peer, afi,
						      safi);
				label_pnt = &label;
				num_labels = 1;
			} else if (path && path->extra) {
				label_pnt = &path->extra->label[0];
				num_labels = path->extra->num_labels;
			}

			if (stream_empty(snlri))
				mpattrlen_pos = bgp_packet_mpattr_start(
					snlri, peer, afi, safi, &vecarr,
					adv->baa->attr);

			bgp_packet_mpattr_prefix(snlri, afi, safi, &rn->p, prd,
						 label_pnt, num_labels,
						 addpath_encode, addpath_tx_id,
						 adv->baa->attr);
		}

		num_pfx++;

		if (bgp_debug_update(NULL, &rn->p, subgrp->update_group, 0)) {
			char pfx_buf[BGP_PRD_PATH_STRLEN];

			if (!send_attr_printed) {
				zlog_debug("u%" PRIu64 ":s%" PRIu64
					   " send UPDATE w/ attr: %s",
					   subgrp->update_group->id, subgrp->id,
					   send_attr_str);
				if (!stream_empty(snlri)) {
					iana_afi_t pkt_afi;
					iana_safi_t pkt_safi;

					pkt_afi = afi_int2iana(afi);
					pkt_safi = safi_int2iana(safi);
					zlog_debug(
						"u%" PRIu64 ":s%" PRIu64
						" send MP_REACH for afi/safi %d/%d",
						subgrp->update_group->id,
						subgrp->id, pkt_afi, pkt_safi);
				}

				send_attr_printed = 1;
			}

			bgp_debug_rdpfxpath2str(afi, safi, prd, &rn->p,
						label_pnt, num_labels,
						addpath_encode, addpath_tx_id,
						pfx_buf, sizeof(pfx_buf));
			zlog_debug("u%" PRIu64 ":s%" PRIu64 " send UPDATE %s",
				   subgrp->update_group->id, subgrp->id,
				   pfx_buf);
		}

		/* Synchnorize attribute.  */
		if (adj->attr)
			bgp_attr_unintern(&adj->attr);
		else
			subgrp->scount++;

		adj->attr = bgp_attr_intern(adv->baa->attr);

		adv = bgp_advertise_clean_subgroup(subgrp, adj);
	}

	if (!stream_empty(s)) {
		if (!stream_empty(snlri)) {
			bgp_packet_mpattr_end(snlri, mpattrlen_pos);
			total_attr_len += stream_get_endp(snlri);
		}

		/* set the total attribute length correctly */
		stream_putw_at(s, attrlen_pos, total_attr_len);

		if (!stream_empty(snlri)) {
			packet = stream_dupcat(s, snlri, mpattr_pos);
			bpacket_attr_vec_arr_update(&vecarr, mpattr_pos);
		} else
			packet = stream_dup(s);
		bgp_packet_set_size(packet);
		if (bgp_debug_update(NULL, NULL, subgrp->update_group, 0))
			zlog_debug("u%" PRIu64 ":s%" PRIu64
				   " send UPDATE len %zd numpfx %d",
				   subgrp->update_group->id, subgrp->id,
				   (stream_get_endp(packet)
				    - stream_get_getp(packet)),
				   num_pfx);
		pkt = bpacket_queue_add(SUBGRP_PKTQ(subgrp), packet, &vecarr);
		stream_reset(s);
		stream_reset(snlri);
		return pkt;
	}
	return NULL;
}

/* Make BGP withdraw packet.  */
/* For ipv4 unicast:
   16-octet marker | 2-octet length | 1-octet type |
    2-octet withdrawn route length | withdrawn prefixes | 2-octet attrlen (=0)
*/
/* For other afi/safis:
   16-octet marker | 2-octet length | 1-octet type |
    2-octet withdrawn route length (=0) | 2-octet attrlen |
     mp_unreach attr type | attr len | afi | safi | withdrawn prefixes
*/
struct bpacket *subgroup_withdraw_packet(struct update_subgroup *subgrp)
{
	struct bpacket *pkt;
	struct stream *s;
	struct bgp_adj_out *adj;
	struct bgp_advertise *adv;
	struct peer *peer;
	struct bgp_node *rn;
	bgp_size_t unfeasible_len;
	bgp_size_t total_attr_len;
	size_t mp_start = 0;
	size_t attrlen_pos = 0;
	size_t mplen_pos = 0;
	uint8_t first_time = 1;
	afi_t afi;
	safi_t safi;
	int space_remaining = 0;
	int space_needed = 0;
	int num_pfx = 0;
	int addpath_encode = 0;
	int addpath_overhead = 0;
	uint32_t addpath_tx_id = 0;
	struct prefix_rd *prd = NULL;


	if (!subgrp)
		return NULL;

	if (bpacket_queue_is_full(SUBGRP_INST(subgrp), SUBGRP_PKTQ(subgrp)))
		return NULL;

	peer = SUBGRP_PEER(subgrp);
	afi = SUBGRP_AFI(subgrp);
	safi = SUBGRP_SAFI(subgrp);
	s = subgrp->work;
	stream_reset(s);
	addpath_encode = bgp_addpath_encode_tx(peer, afi, safi);
	addpath_overhead = addpath_encode ? BGP_ADDPATH_ID_LEN : 0;

	while ((adv = bgp_adv_fifo_first(&subgrp->sync->withdraw)) != NULL) {
		assert(adv->rn);
		adj = adv->adj;
		rn = adv->rn;
		addpath_tx_id = adj->addpath_tx_id;

		space_remaining =
			STREAM_WRITEABLE(s) - BGP_MAX_PACKET_SIZE_OVERFLOW;
		space_needed =
			BGP_NLRI_LENGTH + addpath_overhead + BGP_TOTAL_ATTR_LEN
			+ bgp_packet_mpattr_prefix_size(afi, safi, &rn->p);

		if (space_remaining < space_needed)
			break;

		if (stream_empty(s)) {
			bgp_packet_set_marker(s, BGP_MSG_UPDATE);
			stream_putw(s, 0); /* unfeasible routes length */
		} else
			first_time = 0;

		if (afi == AFI_IP && safi == SAFI_UNICAST
		    && !peer_cap_enhe(peer, afi, safi))
			stream_put_prefix_addpath(s, &rn->p, addpath_encode,
						  addpath_tx_id);
		else {
			if (rn->prn)
				prd = (struct prefix_rd *)&rn->prn->p;

			/* If first time, format the MP_UNREACH header */
			if (first_time) {
				iana_afi_t pkt_afi;
				iana_safi_t pkt_safi;

				pkt_afi = afi_int2iana(afi);
				pkt_safi = safi_int2iana(safi);

				attrlen_pos = stream_get_endp(s);
				/* total attr length = 0 for now. reevaluate
				 * later */
				stream_putw(s, 0);
				mp_start = stream_get_endp(s);
				mplen_pos = bgp_packet_mpunreach_start(s, afi,
								       safi);
				if (bgp_debug_update(NULL, NULL,
						     subgrp->update_group, 0))
					zlog_debug(
						"u%" PRIu64 ":s%" PRIu64
						" send MP_UNREACH for afi/safi %d/%d",
						subgrp->update_group->id,
						subgrp->id, pkt_afi, pkt_safi);
			}

			bgp_packet_mpunreach_prefix(s, &rn->p, afi, safi, prd,
						    NULL, 0, addpath_encode,
						    addpath_tx_id, NULL);
		}

		num_pfx++;

		if (bgp_debug_update(NULL, &rn->p, subgrp->update_group, 0)) {
			char pfx_buf[BGP_PRD_PATH_STRLEN];

			bgp_debug_rdpfxpath2str(afi, safi, prd, &rn->p, NULL, 0,
						addpath_encode, addpath_tx_id,
						pfx_buf, sizeof(pfx_buf));
			zlog_debug("u%" PRIu64 ":s%" PRIu64
				   " send UPDATE %s -- unreachable",
				   subgrp->update_group->id, subgrp->id,
				   pfx_buf);
		}

		subgrp->scount--;

		bgp_adj_out_remove_subgroup(rn, adj, subgrp);
		bgp_unlock_node(rn);
	}

	if (!stream_empty(s)) {
		if (afi == AFI_IP && safi == SAFI_UNICAST
		    && !peer_cap_enhe(peer, afi, safi)) {
			unfeasible_len = stream_get_endp(s) - BGP_HEADER_SIZE
					 - BGP_UNFEASIBLE_LEN;
			stream_putw_at(s, BGP_HEADER_SIZE, unfeasible_len);
			stream_putw(s, 0);
		} else {
			/* Set the mp_unreach attr's length */
			bgp_packet_mpunreach_end(s, mplen_pos);

			/* Set total path attribute length. */
			total_attr_len = stream_get_endp(s) - mp_start;
			stream_putw_at(s, attrlen_pos, total_attr_len);
		}
		bgp_packet_set_size(s);
		if (bgp_debug_update(NULL, NULL, subgrp->update_group, 0))
			zlog_debug("u%" PRIu64 ":s%" PRIu64
				   " send UPDATE (withdraw) len %zd numpfx %d",
				   subgrp->update_group->id, subgrp->id,
				   (stream_get_endp(s) - stream_get_getp(s)),
				   num_pfx);
		pkt = bpacket_queue_add(SUBGRP_PKTQ(subgrp), stream_dup(s),
					NULL);
		stream_reset(s);
		return pkt;
	}

	return NULL;
}

void subgroup_default_update_packet(struct update_subgroup *subgrp,
				    struct attr *attr, struct peer *from)
{
	struct stream *s;
	struct peer *peer;
	struct prefix p;
	unsigned long pos;
	bgp_size_t total_attr_len;
	afi_t afi;
	safi_t safi;
	struct bpacket_attr_vec_arr vecarr;
	int addpath_encode = 0;

	if (DISABLE_BGP_ANNOUNCE)
		return;

	if (!subgrp)
		return;

	peer = SUBGRP_PEER(subgrp);
	afi = SUBGRP_AFI(subgrp);
	safi = SUBGRP_SAFI(subgrp);
	bpacket_attr_vec_arr_reset(&vecarr);
	addpath_encode = bgp_addpath_encode_tx(peer, afi, safi);

	memset(&p, 0, sizeof(p));
	p.family = afi2family(afi);
	p.prefixlen = 0;

	/* Logging the attribute. */
	if (bgp_debug_update(NULL, &p, subgrp->update_group, 0)) {
		char attrstr[BUFSIZ];
		char buf[PREFIX_STRLEN];
		/* ' with addpath ID '          17
		 * max strlen of uint32       + 10
		 * +/- (just in case)         +  1
		 * null terminator            +  1
		 * ============================ 29 */
		char tx_id_buf[30];

		attrstr[0] = '\0';

		bgp_dump_attr(attr, attrstr, BUFSIZ);

		if (addpath_encode)
			snprintf(tx_id_buf, sizeof(tx_id_buf),
				 " with addpath ID %u",
				 BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);
		else
			tx_id_buf[0] = '\0';

		zlog_debug("u%" PRIu64 ":s%" PRIu64 " send UPDATE %s%s %s",
			   (SUBGRP_UPDGRP(subgrp))->id, subgrp->id,
			   prefix2str(&p, buf, sizeof(buf)), tx_id_buf,
			   attrstr);
	}

	s = stream_new(BGP_MAX_PACKET_SIZE);

	/* Make BGP update packet. */
	bgp_packet_set_marker(s, BGP_MSG_UPDATE);

	/* Unfeasible Routes Length. */
	stream_putw(s, 0);

	/* Make place for total attribute length.  */
	pos = stream_get_endp(s);
	stream_putw(s, 0);
	total_attr_len = bgp_packet_attribute(
		NULL, peer, s, attr, &vecarr, &p, afi, safi, from, NULL, NULL,
		0, addpath_encode, BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);

	/* Set Total Path Attribute Length. */
	stream_putw_at(s, pos, total_attr_len);

	/* NLRI set. */
	if (p.family == AF_INET && safi == SAFI_UNICAST
	    && !peer_cap_enhe(peer, afi, safi))
		stream_put_prefix_addpath(
			s, &p, addpath_encode,
			BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);

	/* Set size. */
	bgp_packet_set_size(s);

	(void)bpacket_queue_add(SUBGRP_PKTQ(subgrp), s, &vecarr);
	subgroup_trigger_write(subgrp);
}

void subgroup_default_withdraw_packet(struct update_subgroup *subgrp)
{
	struct peer *peer;
	struct stream *s;
	struct prefix p;
	unsigned long attrlen_pos = 0;
	unsigned long cp;
	bgp_size_t unfeasible_len;
	bgp_size_t total_attr_len = 0;
	size_t mp_start = 0;
	size_t mplen_pos = 0;
	afi_t afi;
	safi_t safi;
	int addpath_encode = 0;

	if (DISABLE_BGP_ANNOUNCE)
		return;

	peer = SUBGRP_PEER(subgrp);
	afi = SUBGRP_AFI(subgrp);
	safi = SUBGRP_SAFI(subgrp);
	addpath_encode = bgp_addpath_encode_tx(peer, afi, safi);

	memset(&p, 0, sizeof(p));
	p.family = afi2family(afi);
	p.prefixlen = 0;

	if (bgp_debug_update(NULL, &p, subgrp->update_group, 0)) {
		char buf[PREFIX_STRLEN];
		/* ' with addpath ID '          17
		 * max strlen of uint32       + 10
		 * +/- (just in case)         +  1
		 * null terminator            +  1
		 * ============================ 29 */
		char tx_id_buf[30];

		if (addpath_encode)
			snprintf(tx_id_buf, sizeof(tx_id_buf),
				 " with addpath ID %u",
				 BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);

		zlog_debug("u%" PRIu64 ":s%" PRIu64
			   " send UPDATE %s%s -- unreachable",
			   (SUBGRP_UPDGRP(subgrp))->id, subgrp->id,
			   prefix2str(&p, buf, sizeof(buf)), tx_id_buf);
	}

	s = stream_new(BGP_MAX_PACKET_SIZE);

	/* Make BGP update packet. */
	bgp_packet_set_marker(s, BGP_MSG_UPDATE);

	/* Unfeasible Routes Length. */;
	cp = stream_get_endp(s);
	stream_putw(s, 0);

	/* Withdrawn Routes. */
	if (p.family == AF_INET && safi == SAFI_UNICAST
	    && !peer_cap_enhe(peer, afi, safi)) {
		stream_put_prefix_addpath(
			s, &p, addpath_encode,
			BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);

		unfeasible_len = stream_get_endp(s) - cp - 2;

		/* Set unfeasible len.  */
		stream_putw_at(s, cp, unfeasible_len);

		/* Set total path attribute length. */
		stream_putw(s, 0);
	} else {
		attrlen_pos = stream_get_endp(s);
		stream_putw(s, 0);
		mp_start = stream_get_endp(s);
		mplen_pos = bgp_packet_mpunreach_start(s, afi, safi);
		bgp_packet_mpunreach_prefix(
			s, &p, afi, safi, NULL, NULL, 0, addpath_encode,
			BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE, NULL);

		/* Set the mp_unreach attr's length */
		bgp_packet_mpunreach_end(s, mplen_pos);

		/* Set total path attribute length. */
		total_attr_len = stream_get_endp(s) - mp_start;
		stream_putw_at(s, attrlen_pos, total_attr_len);
	}

	bgp_packet_set_size(s);

	(void)bpacket_queue_add(SUBGRP_PKTQ(subgrp), s, NULL);
	subgroup_trigger_write(subgrp);
}

static void
bpacket_vec_arr_inherit_attr_flags(struct bpacket_attr_vec_arr *vecarr,
				   bpacket_attr_vec_type type,
				   struct attr *attr)
{
	if (CHECK_FLAG(attr->rmap_change_flags,
		       BATTR_RMAP_NEXTHOP_PEER_ADDRESS))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS);

	if (CHECK_FLAG(attr->rmap_change_flags, BATTR_REFLECTED))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_REFLECTED);

	if (CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_NEXTHOP_UNCHANGED))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_RMAP_NH_UNCHANGED);

	if (CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_IPV4_NHOP_CHANGED))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_RMAP_IPV4_NH_CHANGED);

	if (CHECK_FLAG(attr->rmap_change_flags,
		       BATTR_RMAP_IPV6_GLOBAL_NHOP_CHANGED))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED);

	if (CHECK_FLAG(attr->rmap_change_flags,
		       BATTR_RMAP_IPV6_LL_NHOP_CHANGED))
		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
			 BPKT_ATTRVEC_FLAGS_RMAP_IPV6_LNH_CHANGED);
}

/* Reset the Attributes vector array. The vector array is used to override
 * certain output parameters in the packet for a particular peer
 */
void bpacket_attr_vec_arr_reset(struct bpacket_attr_vec_arr *vecarr)
{
	int i;

	if (!vecarr)
		return;

	i = 0;
	while (i < BGP_ATTR_VEC_MAX) {
		vecarr->entries[i].flags = 0;
		vecarr->entries[i].offset = 0;
		i++;
	}
}

/* Setup a particular node entry in the vecarr */
void bpacket_attr_vec_arr_set_vec(struct bpacket_attr_vec_arr *vecarr,
				  bpacket_attr_vec_type type, struct stream *s,
				  struct attr *attr)
{
	if (!vecarr)
		return;
	assert(type < BGP_ATTR_VEC_MAX);

	SET_FLAG(vecarr->entries[type].flags, BPKT_ATTRVEC_FLAGS_UPDATED);
	vecarr->entries[type].offset = stream_get_endp(s);
	if (attr)
		bpacket_vec_arr_inherit_attr_flags(vecarr, type, attr);
}