pimd: refactor/split IGMP integration

Try to untangle some spaghetti...

This is an 1:1 change that should not result in any functional
difference.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 178 insertions, 0 deletions

diff --git a/pimd/pim_tib.c b/pimd/pim_tib.c
new file mode 100644
index 000000000..838f11211
--- /dev/null
+++ b/pimd/pim_tib.c
@@ -0,0 +1,178 @@
+/*
+ * TIB (Tree Information Base) - just PIM <> IGMP/MLD glue for now
+ * Copyright (C) 2022  David Lamparter for NetDEF, 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 "pim_tib.h"
+
+#include "pimd.h"
+#include "pim_iface.h"
+#include "pim_upstream.h"
+#include "pim_oil.h"
+#include "pim_nht.h"
+
+static struct channel_oil *
+tib_sg_oil_setup(struct pim_instance *pim, pim_sgaddr sg, struct interface *oif)
+{
+	struct pim_interface *pim_oif = oif->info;
+	int input_iface_vif_index = 0;
+	pim_addr vif_source;
+	struct prefix src, grp;
+	struct pim_nexthop nexthop;
+	struct pim_upstream *up = NULL;
+
+	if (!pim_rp_set_upstream_addr(pim, &vif_source, sg.src, sg.grp)) {
+		/* no PIM RP - create a dummy channel oil */
+		return pim_channel_oil_add(pim, &sg, __func__);
+	}
+
+	pim_addr_to_prefix(&src, vif_source); // RP or Src addr
+	pim_addr_to_prefix(&grp, sg.grp);
+
+	up = pim_upstream_find(pim, &sg);
+	if (up) {
+		memcpy(&nexthop, &up->rpf.source_nexthop,
+		       sizeof(struct pim_nexthop));
+		pim_ecmp_nexthop_lookup(pim, &nexthop, &src, &grp, 0);
+		if (nexthop.interface)
+			input_iface_vif_index = pim_if_find_vifindex_by_ifindex(
+				pim, nexthop.interface->ifindex);
+	} else
+		input_iface_vif_index =
+			pim_ecmp_fib_lookup_if_vif_index(pim, &src, &grp);
+
+	if (PIM_DEBUG_ZEBRA)
+		zlog_debug("%s: NHT %pSG vif_source %pPAs vif_index:%d",
+			   __func__, &sg, &vif_source, input_iface_vif_index);
+
+	if (input_iface_vif_index < 1) {
+		if (PIM_DEBUG_IGMP_TRACE)
+			zlog_debug(
+				"%s %s: could not find input interface for %pSG",
+				__FILE__, __func__, &sg);
+
+		return pim_channel_oil_add(pim, &sg, __func__);
+	}
+
+	/*
+	 * Protect IGMP against adding looped MFC entries created by both
+	 * source and receiver attached to the same interface. See TODO T22.
+	 * Block only when the intf is non DR DR must create upstream.
+	 */
+	if ((input_iface_vif_index == pim_oif->mroute_vif_index) &&
+	    !(PIM_I_am_DR(pim_oif))) {
+		/* ignore request for looped MFC entry */
+		if (PIM_DEBUG_IGMP_TRACE)
+			zlog_debug(
+				"%s: ignoring request for looped MFC entry (S,G)=%pSG: oif=%s vif_index=%d",
+				__func__, &sg, oif->name,
+				input_iface_vif_index);
+
+		return NULL;
+	}
+
+	return pim_channel_oil_add(pim, &sg, __func__);
+}
+
+bool tib_sg_gm_join(struct pim_instance *pim, pim_sgaddr sg,
+		    struct interface *oif, struct channel_oil **oilp)
+{
+	struct pim_interface *pim_oif = oif->info;
+
+	if (!pim_oif) {
+		if (PIM_DEBUG_IGMP_TRACE)
+			zlog_debug("%s: multicast not enabled on oif=%s?",
+				   __func__, oif->name);
+		return false;
+	}
+
+	if (!*oilp)
+		*oilp = tib_sg_oil_setup(pim, sg, oif);
+	if (!*oilp)
+		return false;
+
+	if (PIM_I_am_DR(pim_oif) || PIM_I_am_DualActive(pim_oif)) {
+		int result;
+
+		result = pim_channel_add_oif(*oilp, oif,
+					     PIM_OIF_FLAG_PROTO_IGMP, __func__);
+		if (result) {
+			if (PIM_DEBUG_MROUTE)
+				zlog_warn("%s: add_oif() failed with return=%d",
+					  __func__, result);
+			return false;
+		}
+	} else {
+		if (PIM_DEBUG_IGMP_TRACE)
+			zlog_debug(
+				"%s: %pSG was received on %s interface but we are not DR for that interface",
+				__func__, &sg, oif->name);
+
+		return false;
+	}
+	/*
+	  Feed IGMPv3-gathered local membership information into PIM
+	  per-interface (S,G) state.
+	 */
+	if (!pim_ifchannel_local_membership_add(oif, &sg, false /*is_vxlan*/)) {
+		if (PIM_DEBUG_MROUTE)
+			zlog_warn(
+				"%s: Failure to add local membership for %pSG",
+				__func__, &sg);
+
+		pim_channel_del_oif(*oilp, oif, PIM_OIF_FLAG_PROTO_IGMP,
+				    __func__);
+		return false;
+	}
+
+	return true;
+}
+
+void tib_sg_gm_prune(struct pim_instance *pim, pim_sgaddr sg,
+		     struct interface *oif, struct channel_oil **oilp)
+{
+	int result;
+
+	/*
+	 It appears that in certain circumstances that
+	 igmp_source_forward_stop is called when IGMP forwarding
+	 was not enabled in oif_flags for this outgoing interface.
+	 Possibly because of multiple calls. When that happens, we
+	 enter the below if statement and this function returns early
+	 which in turn triggers the calling function to assert.
+	 Making the call to pim_channel_del_oif and ignoring the return code
+	 fixes the issue without ill effect, similar to
+	 pim_forward_stop below.
+	*/
+	result = pim_channel_del_oif(*oilp, oif, PIM_OIF_FLAG_PROTO_IGMP,
+				     __func__);
+	if (result) {
+		if (PIM_DEBUG_IGMP_TRACE)
+			zlog_debug(
+				"%s: pim_channel_del_oif() failed with return=%d",
+				__func__, result);
+		return;
+	}
+
+	/*
+	  Feed IGMPv3-gathered local membership information into PIM
+	  per-interface (S,G) state.
+	 */
+	pim_ifchannel_local_membership_del(oif, &sg);
+}