pim_join.c

// SPDX-License-Identifier: GPL-2.0-or-later


/*
 * PIM for Quagga
 * Copyright (C) 2008  Everton da Silva Marques
 */

#include <zebra.h>

#include "log.h"
#include "prefix.h"
#include "if.h"
#include "vty.h"
#include "plist.h"

#include "pimd.h"
#include "pim_instance.h"
#include "pim_str.h"
#include "pim_tlv.h"
#include "pim_msg.h"
#include "pim_pim.h"
#include "pim_join.h"
#include "pim_oil.h"
#include "pim_iface.h"
#include "pim_hello.h"
#include "pim_ifchannel.h"
#include "pim_rpf.h"
#include "pim_rp.h"
#include "pim_jp_agg.h"
#include "pim_util.h"
#include "pim_ssm.h"

static void on_trace(const char *label, struct interface *ifp, pim_addr src)
{
	if (PIM_DEBUG_PIM_TRACE)
		zlog_debug("%s: from %pPA on %s", label, &src, ifp->name);
}

static void recv_join(struct interface *ifp, struct pim_neighbor *neigh,
		      uint16_t holdtime, pim_addr upstream, pim_sgaddr *sg,
		      uint8_t source_flags)
{
	struct pim_interface *pim_ifp = NULL;

	if (PIM_DEBUG_PIM_J_P)
		zlog_debug(
			"%s: join (S,G)=%pSG rpt=%d wc=%d upstream=%pPAs holdtime=%d from %pPA on %s",
			__func__, sg, !!(source_flags & PIM_RPT_BIT_MASK),
			!!(source_flags & PIM_WILDCARD_BIT_MASK), &upstream,
			holdtime, &neigh->source_addr, ifp->name);

	pim_ifp = ifp->info;
	assert(pim_ifp);

	++pim_ifp->pim_ifstat_join_recv;

	/*
	 * If the RPT and WC are set it's a (*,G)
	 * and the source is the RP
	 */
	if (CHECK_FLAG(source_flags, PIM_WILDCARD_BIT_MASK)) {
		/* As per RFC 7761 Section 4.9.1:
		 * The RPT (or Rendezvous Point Tree) bit is a 1-bit value for
		 * use with PIM Join/Prune messages (see Section 4.9.5.1). If
		 * the WC bit is 1, the RPT bit MUST be 1.
		 */
		if (!CHECK_FLAG(source_flags, PIM_RPT_BIT_MASK)) {
			if (PIM_DEBUG_PIM_J_P)
				zlog_debug(
					"Discarding (*,G)=%pSG join since WC bit is set but RPT bit is unset",
					sg);

			return;
		}

		struct pim_rpf *rp = RP(pim_ifp->pim, sg->grp);
		pim_addr rpf_addr;

		if (!rp) {
			zlog_warn("%s: Lookup of RP failed for %pSG", __func__,
				  sg);
			return;
		}
		/*
		 * If the RP sent in the message is not
		 * our RP for the group, drop the message
		 */
		rpf_addr = rp->rpf_addr;
		if (pim_addr_cmp(sg->src, rpf_addr)) {
			zlog_warn(
				"%s: Specified RP(%pPAs) in join is different than our configured RP(%pPAs)",
				__func__, &sg->src, &rpf_addr);
			return;
		}

		if (pim_is_grp_ssm(pim_ifp->pim, sg->grp)) {
			zlog_warn(
				"%s: Specified Group(%pPA) in join is now in SSM, not allowed to create PIM state",
				__func__, &sg->grp);
			return;
		}

		sg->src = PIMADDR_ANY;
	}

	/* Restart join expiry timer */
	pim_ifchannel_join_add(ifp, neigh->source_addr, upstream, sg,
			       source_flags, holdtime);
}

static void recv_prune(struct interface *ifp, struct pim_neighbor *neigh,
		       uint16_t holdtime, pim_addr upstream, pim_sgaddr *sg,
		       uint8_t source_flags)
{
	struct pim_interface *pim_ifp = NULL;

	if (PIM_DEBUG_PIM_J_P)
		zlog_debug(
			"%s: prune (S,G)=%pSG rpt=%d wc=%d upstream=%pPAs holdtime=%d from %pPA on %s",
			__func__, sg, source_flags & PIM_RPT_BIT_MASK,
			source_flags & PIM_WILDCARD_BIT_MASK, &upstream,
			holdtime, &neigh->source_addr, ifp->name);

	pim_ifp = ifp->info;
	assert(pim_ifp);

	++pim_ifp->pim_ifstat_prune_recv;

	if (CHECK_FLAG(source_flags, PIM_WILDCARD_BIT_MASK)) {
		/* As per RFC 7761 Section 4.9.1:
		 * The RPT (or Rendezvous Point Tree) bit is a 1-bit value for
		 * use with PIM Join/Prune messages (see Section 4.9.5.1). If
		 * the WC bit is 1, the RPT bit MUST be 1.
		 */
		if (!CHECK_FLAG(source_flags, PIM_RPT_BIT_MASK)) {
			if (PIM_DEBUG_PIM_J_P)
				zlog_debug(
					"Discarding (*,G)=%pSG prune since WC bit is set but RPT bit is unset",
					sg);

			return;
		}

		/*
		 * RFC 4601 Section 4.5.2:
		 * Received Prune(*,G) messages are processed even if the
		 * RP in the message does not match RP(G).
		 */
		if (PIM_DEBUG_PIM_J_P)
			zlog_debug("%s: Prune received with RP(%pPAs) for %pSG",
				   __func__, &sg->src, sg);

		sg->src = PIMADDR_ANY;
	}

	pim_ifchannel_prune(ifp, upstream, sg, source_flags, holdtime);
}

int pim_joinprune_recv(struct interface *ifp, struct pim_neighbor *neigh,
		       pim_addr src_addr, uint8_t *tlv_buf, int tlv_buf_size)
{
	pim_addr msg_upstream_addr;
	bool wrong_af = false;
	struct pim_interface *pim_ifp;
	uint8_t msg_num_groups;
	uint16_t msg_holdtime;
	int addr_offset;
	uint8_t *buf;
	uint8_t *pastend;
	int remain;
	int group;
	struct pim_ifchannel *child = NULL;
	struct listnode *ch_node, *nch_node;

	buf = tlv_buf;
	pastend = tlv_buf + tlv_buf_size;
	pim_ifp = ifp->info;

	if (pim_ifp->pim_passive_enable) {
		if (PIM_DEBUG_PIM_PACKETS)
			zlog_debug(
				"skip receiving PIM message on passive interface %s",
				ifp->name);
		return 0;
	}

	/*
	  Parse ucast addr
	*/
	addr_offset = pim_parse_addr_ucast(&msg_upstream_addr, buf,
					   pastend - buf, &wrong_af);
	if (addr_offset < 1) {
		zlog_warn("%s: pim_parse_addr_ucast() failure: from %pPA on %s",
			  __func__, &src_addr, ifp->name);
		return -1;
	}
	buf += addr_offset;

	/*
	  Check upstream address family
	 */
	if (wrong_af) {
		zlog_warn(
			"%s: ignoring join/prune directed to unexpected addr family from %pPA on %s",
			__func__, &src_addr, ifp->name);
		return -2;
	}

	remain = pastend - buf;
	if (remain < 4) {
		zlog_warn(
			"%s: short join/prune message buffer for group list: size=%d minimum=%d from %pPA on %s",
			__func__, remain, 4, &src_addr, ifp->name);
		return -4;
	}

	++buf; /* skip reserved byte */
	msg_num_groups = *(const uint8_t *)buf;
	++buf;
	msg_holdtime = ntohs(*(const uint16_t *)buf);
	++buf;
	++buf;

	if (PIM_DEBUG_PIM_J_P)
		zlog_debug(
			"%s: join/prune upstream=%pPAs groups=%d holdtime=%d from %pPA on %s",
			__func__, &msg_upstream_addr, msg_num_groups,
			msg_holdtime, &src_addr, ifp->name);

	/* Scan groups */
	for (group = 0; group < msg_num_groups; ++group) {
		pim_sgaddr sg;
		uint8_t msg_source_flags;
		uint16_t msg_num_joined_sources;
		uint16_t msg_num_pruned_sources;
		int source;
		struct pim_ifchannel *starg_ch = NULL, *sg_ch = NULL;
		bool filtered = false;

		memset(&sg, 0, sizeof(sg));
		addr_offset = pim_parse_addr_group(&sg, buf, pastend - buf);
		if (addr_offset < 1) {
			return -5;
		}
		buf += addr_offset;

		remain = pastend - buf;
		if (remain < 4) {
			zlog_warn(
				"%s: short join/prune buffer for source list: size=%d minimum=%d from %pPA on %s",
				__func__, remain, 4, &src_addr, ifp->name);
			return -6;
		}

		msg_num_joined_sources = ntohs(*(const uint16_t *)buf);
		buf += 2;
		msg_num_pruned_sources = ntohs(*(const uint16_t *)buf);
		buf += 2;

		if (PIM_DEBUG_PIM_J_P)
			zlog_debug(
				"%s: join/prune upstream=%pPAs group=%pPA/32 join_src=%d prune_src=%d from %pPA on %s",
				__func__, &msg_upstream_addr, &sg.grp,
				msg_num_joined_sources, msg_num_pruned_sources,
				&src_addr, ifp->name);

		/* boundary check */
		filtered = pim_is_group_filtered(pim_ifp, &sg.grp);

		/* Scan joined sources */
		for (source = 0; source < msg_num_joined_sources; ++source) {
			addr_offset = pim_parse_addr_source(
				&sg, &msg_source_flags, buf, pastend - buf);
			if (addr_offset < 1) {
				return -7;
			}

			buf += addr_offset;

			/* if we are filtering this group, skip the join */
			if (filtered)
				continue;

			recv_join(ifp, neigh, msg_holdtime, msg_upstream_addr,
				  &sg, msg_source_flags);

			if (pim_addr_is_any(sg.src)) {
				starg_ch = pim_ifchannel_find(ifp, &sg);
				if (starg_ch)
					pim_ifchannel_set_star_g_join_state(
						starg_ch, 0, 1);
			}
		}

		/* Scan pruned sources */
		for (source = 0; source < msg_num_pruned_sources; ++source) {
			addr_offset = pim_parse_addr_source(
				&sg, &msg_source_flags, buf, pastend - buf);
			if (addr_offset < 1) {
				return -8;
			}

			buf += addr_offset;

			/* if we are filtering this group, skip the prune */
			if (filtered)
				continue;

			recv_prune(ifp, neigh, msg_holdtime, msg_upstream_addr,
				   &sg, msg_source_flags);
			/*
			 * So if we are receiving a S,G,RPT prune
			 * before we have any data for that S,G
			 * We need to retrieve the sg_ch after
			 * we parse the prune.
			 */
			sg_ch = pim_ifchannel_find(ifp, &sg);

			if (!sg_ch)
				continue;

			/* (*,G) prune received */
			for (ALL_LIST_ELEMENTS(sg_ch->sources, ch_node,
					       nch_node, child)) {
				if (PIM_IF_FLAG_TEST_S_G_RPT(child->flags)) {
					if (child->ifjoin_state
					    == PIM_IFJOIN_PRUNE_PENDING_TMP)
						EVENT_OFF(
							child->t_ifjoin_prune_pending_timer);
					EVENT_OFF(child->t_ifjoin_expiry_timer);
					PIM_IF_FLAG_UNSET_S_G_RPT(child->flags);
					child->ifjoin_state = PIM_IFJOIN_NOINFO;
					delete_on_noinfo(child);
				}
			}

			/* Received SG-RPT Prune delete oif from specific S,G */
			if (starg_ch && (msg_source_flags & PIM_RPT_BIT_MASK)
			    && !(msg_source_flags & PIM_WILDCARD_BIT_MASK)) {
				struct pim_upstream *up = sg_ch->upstream;
				PIM_IF_FLAG_SET_S_G_RPT(sg_ch->flags);
				if (up) {
					if (PIM_DEBUG_PIM_TRACE)
						zlog_debug(
							"%s: SGRpt flag is set, del inherit oif from up %s",
							__func__, up->sg_str);
					pim_channel_del_inherited_oif(
						up->channel_oil,
						starg_ch->interface,
						__func__);
				}
			}
		}
		if (starg_ch && !filtered)
			pim_ifchannel_set_star_g_join_state(starg_ch, 1, 0);
		starg_ch = NULL;
	} /* scan groups */

	return 0;
}

/*
 * J/P Message Format
 *
 * While the RFC clearly states that this is 32 bits wide, it
 * is cheating.  These fields:
 * Encoded-Unicast format   (6 bytes MIN)
 * Encoded-Group format     (8 bytes MIN)
 * Encoded-Source format    (8 bytes MIN)
 * are *not* 32 bits wide.
 *
 * Nor does the RFC explicitly call out the size for:
 * Reserved                 (1 byte)
 * Num Groups               (1 byte)
 * Holdtime                 (2 bytes)
 * Number of Joined Sources (2 bytes)
 * Number of Pruned Sources (2 bytes)
 *
 * This leads to a missleading representation from casual
 * reading and making assumptions.  Be careful!
 *
 *   0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |PIM Ver| Type  |   Reserved    |           Checksum            |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Upstream Neighbor Address (Encoded-Unicast format)     |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |  Reserved     | Num groups    |          Holdtime             |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |         Multicast Group Address 1 (Encoded-Group format)      |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |   Number of Joined Sources    |   Number of Pruned Sources    |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Joined Source Address 1 (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                             .                                 |
 *  |                             .                                 |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Joined Source Address n (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Pruned Source Address 1 (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                             .                                 |
 *  |                             .                                 |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Pruned Source Address n (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |         Multicast Group Address m (Encoded-Group format)      |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |   Number of Joined Sources    |   Number of Pruned Sources    |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Joined Source Address 1 (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                             .                                 |
 *  |                             .                                 |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Joined Source Address n (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Pruned Source Address 1 (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                             .                                 |
 *  |                             .                                 |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |        Pruned Source Address n (Encoded-Source format)        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
int pim_joinprune_send(struct pim_rpf *rpf, struct list *groups)
{
	struct pim_jp_agg_group *group;
	struct pim_interface *pim_ifp = NULL;
	struct pim_jp_groups *grp = NULL;
	struct pim_jp *msg = NULL;
	struct listnode *node, *nnode;
	uint8_t pim_msg[10000];
	uint8_t *curr_ptr = pim_msg;
	bool new_packet = true;
	size_t packet_left = 0;
	size_t packet_size = 0;
	size_t group_size = 0;

	if (rpf->source_nexthop.interface)
		pim_ifp = rpf->source_nexthop.interface->info;
	else {
		zlog_warn("%s: RPF interface is not present", __func__);
		return -1;
	}


	on_trace(__func__, rpf->source_nexthop.interface, rpf->rpf_addr);

	if (!pim_ifp) {
		zlog_warn("%s: multicast not enabled on interface %s", __func__,
			  rpf->source_nexthop.interface->name);
		return -1;
	}

	if (pim_addr_is_any(rpf->rpf_addr)) {
		if (PIM_DEBUG_PIM_J_P)
			zlog_debug(
				"%s: upstream=%pPA is myself on interface %s",
				__func__, &rpf->rpf_addr,
				rpf->source_nexthop.interface->name);
		return 0;
	}

	/*
	  RFC 4601: 4.3.1.  Sending Hello Messages

	  Thus, if a router needs to send a Join/Prune or Assert message on
	  an interface on which it has not yet sent a Hello message with the
	  currently configured IP address, then it MUST immediately send the
	  relevant Hello message without waiting for the Hello Timer to
	  expire, followed by the Join/Prune or Assert message.
	*/
	pim_hello_require(rpf->source_nexthop.interface);

	for (ALL_LIST_ELEMENTS(groups, node, nnode, group)) {
		if (new_packet) {
			msg = (struct pim_jp *)pim_msg;

			memset(msg, 0, sizeof(*msg));

			pim_msg_addr_encode_ucast((uint8_t *)&msg->addr,
						  rpf->rpf_addr);
			msg->reserved = 0;
			msg->holdtime = htons(PIM_JP_HOLDTIME);

			new_packet = false;

			grp = &msg->groups[0];
			curr_ptr = (uint8_t *)grp;
			packet_size = sizeof(struct pim_msg_header);
			packet_size += sizeof(pim_encoded_unicast);
			packet_size +=
				4; // reserved (1) + groups (1) + holdtime (2)

			packet_left = rpf->source_nexthop.interface->mtu - 24;
			packet_left -= packet_size;
		}
		if (PIM_DEBUG_PIM_J_P)
			zlog_debug(
				"%s: sending (G)=%pPAs to upstream=%pPA on interface %s",
				__func__, &group->group, &rpf->rpf_addr,
				rpf->source_nexthop.interface->name);

		group_size = pim_msg_get_jp_group_size(group->sources);
		if (group_size > packet_left) {
			pim_msg_build_header(pim_ifp->primary_address,
					     qpim_all_pim_routers_addr, pim_msg,
					     packet_size,
					     PIM_MSG_TYPE_JOIN_PRUNE, false);
			if (pim_msg_send(pim_ifp->pim_sock_fd,
					 pim_ifp->primary_address,
					 qpim_all_pim_routers_addr, pim_msg,
					 packet_size,
					 rpf->source_nexthop.interface)) {
				zlog_warn(
					"%s: could not send PIM message on interface %s",
					__func__,
					rpf->source_nexthop.interface->name);
			}

			msg = (struct pim_jp *)pim_msg;
			memset(msg, 0, sizeof(*msg));

			pim_msg_addr_encode_ucast((uint8_t *)&msg->addr,
						  rpf->rpf_addr);
			msg->reserved = 0;
			msg->holdtime = htons(PIM_JP_HOLDTIME);

			new_packet = false;

			grp = &msg->groups[0];
			curr_ptr = (uint8_t *)grp;
			packet_size = sizeof(struct pim_msg_header);
			packet_size += sizeof(pim_encoded_unicast);
			packet_size +=
				4; // reserved (1) + groups (1) + holdtime (2)

			packet_left = rpf->source_nexthop.interface->mtu - 24;
			packet_left -= packet_size;
		}

		msg->num_groups++;
		/*
		  Build PIM message
		*/

		curr_ptr += group_size;
		packet_left -= group_size;
		packet_size += group_size;
		pim_msg_build_jp_groups(grp, group, group_size);

		if (!pim_ifp->pim_passive_enable) {
			pim_ifp->pim_ifstat_join_send += ntohs(grp->joins);
			pim_ifp->pim_ifstat_prune_send += ntohs(grp->prunes);
		}

		if (PIM_DEBUG_PIM_TRACE)
			zlog_debug(
				"%s: interface %s num_joins %u num_prunes %u",
				__func__, rpf->source_nexthop.interface->name,
				ntohs(grp->joins), ntohs(grp->prunes));

		grp = (struct pim_jp_groups *)curr_ptr;
		if (packet_left < sizeof(struct pim_jp_groups)
		    || msg->num_groups == 255) {
			pim_msg_build_header(pim_ifp->primary_address,
					     qpim_all_pim_routers_addr, pim_msg,
					     packet_size,
					     PIM_MSG_TYPE_JOIN_PRUNE, false);
			if (pim_msg_send(pim_ifp->pim_sock_fd,
					 pim_ifp->primary_address,
					 qpim_all_pim_routers_addr, pim_msg,
					 packet_size,
					 rpf->source_nexthop.interface)) {
				zlog_warn(
					"%s: could not send PIM message on interface %s",
					__func__,
					rpf->source_nexthop.interface->name);
			}

			new_packet = true;
		}
	}


	if (!new_packet) {
		// msg->num_groups = htons (msg->num_groups);
		pim_msg_build_header(
			pim_ifp->primary_address, qpim_all_pim_routers_addr,
			pim_msg, packet_size, PIM_MSG_TYPE_JOIN_PRUNE, false);
		if (pim_msg_send(pim_ifp->pim_sock_fd, pim_ifp->primary_address,
				 qpim_all_pim_routers_addr, pim_msg,
				 packet_size, rpf->source_nexthop.interface)) {
			zlog_warn(
				"%s: could not send PIM message on interface %s",
				__func__, rpf->source_nexthop.interface->name);
		}
	}
	return 0;
}