ripd multicast leave even when interface is down - for FRR6 - fixes igmp membership leak

rip_multicast_leave.patch

Fix for:
RIP: can't setsockopt IP_ADD_MEMBERSHIP No buffer space available
RIP: multicast join failed, interface FOO not running
Based on the patch for quagga from Michal Ruzicka
https://lists.quagga.net/pipermail/quagga-dev/2006-August/020891.html
Which was based on the one for zebra from Sergey Vlasov
https://bugzilla.altlinux.org/show_bug.cgi?id=3915
--- frr-6.0.3.orig/ripd/ripd.h	2021-07-07 14:02:30.054026597 -0300
+++ frr-6.0.3/ripd/ripd.h	2021-07-07 14:09:50.546026022 -0300
@@ -249,6 +249,9 @@
 	/* RIP is running on this interface. */
 	int running;
 
+	/* Joined to multicast group for this interface. */
+	int joined_multicast;
+
 	/* RIP version control. */
 	int ri_send;
 	int ri_receive;
--- frr-6.0.3/ripd/rip_interface.c	2021-07-07 14:02:19.994026536 -0300
+++ frr-6.0.3.orig/ripd/rip_interface.c	2021-07-07 14:09:02.322026026 -0300
@@ -95,7 +95,8 @@
 					group.s_addr, ifindex);
 
 	if (ret < 0)
-		zlog_info("can't setsockopt IP_DROP_MEMBERSHIP");
+		zlog_info("can't setsockopt IP_DROP_MEMBERSHIP %s",
+			  safe_strerror(errno));
 
 	return ret;
 }
@@ -256,12 +257,15 @@
 /* Multicast packet receive socket. */
 static int rip_multicast_join(struct interface *ifp, int sock)
 {
+	struct rip_interface *ri;
 	struct listnode *cnode;
 	struct connected *ifc;
 
+	ri = ifp->info;
+
 	if (if_is_operative(ifp) && if_is_multicast(ifp)) {
 		if (IS_RIP_DEBUG_EVENT)
-			zlog_debug("multicast join at %s", ifp->name);
+			zlog_debug("multicast join at %s ifindex %d", ifp->name, ifp->ifindex);
 
 		for (ALL_LIST_ELEMENTS_RO(ifp->connected, cnode, ifc)) {
 			struct prefix_ipv4 *p;
@@ -277,8 +281,9 @@
 						ifp->ifindex)
 			    < 0)
 				return -1;
-			else
-				return 0;
+
+			ri->joined_multicast = 1;
+			return 0;
 		}
 	}
 	return 0;
@@ -290,9 +295,12 @@
 	struct listnode *cnode;
 	struct connected *connected;
 
-	if (if_is_up(ifp) && if_is_multicast(ifp)) {
+	ri = ifp->info;
+
+	if (if_is_multicast(ifp)) {
 		if (IS_RIP_DEBUG_EVENT)
-			zlog_debug("multicast leave from %s", ifp->name);
+			zlog_debug("multicast leave from %s ifindex %d",
+			          ifp->name, ifp->ifindex);
 
 		for (ALL_LIST_ELEMENTS_RO(ifp->connected, cnode, connected)) {
 			struct prefix_ipv4 *p;
@@ -306,8 +314,10 @@
 			group.s_addr = htonl(INADDR_RIP_GROUP);
 			if (ipv4_multicast_leave(sock, group, p->prefix,
 						 ifp->ifindex)
-			    == 0)
-				return;
+			    < 0)
+				continue;
+			ri->joined_multicast = 0;
+			return;
 		}
 	}
 }