pimd: Implement watermark warning for igmp group count and add igmp group count

This CLI will allow user to configure a igmp group limit which will generate
a watermark warning when reached.
Though watermark may not make sense without setting a limit, this
implementation shall serve as a base to implementing limit in future and helps
tracking a particular scale currently.

Testing:
=======

ip igmp watermark-warn <10-60000>

on reaching the configured number of group, pim will issue warning

2019/09/18 18:30:55 PIM: SCALE ALERT: igmp group count reached watermak limit: 210(vrf: default)

Also added group count and watermark limit configured on cli - show ip igmp groups [json]

<snip>

Sw3# sh ip igmp groups json
{
  "Total Groups":221,  <=====
  "Watermark limit":210, <=========
  "ens224":{
    "name":"ens224",
    "state":"up",
    "address":"40.0.0.1",
    "index":6,
    "flagMulticast":true,
    "flagBroadcast":true,
    "lanDelayEnabled":true,
    "groups":[
      {
        "source":"40.0.0.1",
        "group":"225.1.1.122",
        "timer":"00:03:56",
        "sourcesCount":1,
        "version":2,
        "uptime":"00:00:24"

<\snip>

<snip>

Sw3(config)# do sh ip igmp group
Total IGMP groups: 221
Watermark warn limit(Set) : 210
Interface        Address         Group           Mode Timer    Srcs V Uptime
ens224           40.0.0.1        225.1.1.122     ---- 00:04:06    1 2 00:13:22
ens224           40.0.0.1        225.1.1.144     ---- 00:04:02    1 2 00:13:22
ens224           40.0.0.1        225.1.1.57      ---- 00:04:01    1 2 00:13:22
ens224           40.0.0.1        225.1.1.210     ---- 00:04:06    1 2 00:13:22

<\snip>

Signed-off-by: Saravanan K <saravanank@vmware.com>

pimd/pim_cmd.c

@@ -3419,11 +3419,19 @@ static void igmp_show_groups(struct pim_instance *pim, struct vty *vty, bool uj)
 
 	now = pim_time_monotonic_sec();
 
-	if (uj)
+	if (uj) {
 		json = json_object_new_object();
-	else
+		json_object_int_add(json, "totalGroups", pim->igmp_group_count);
+		json_object_int_add(json, "watermarkLimit",
+				    pim->igmp_watermark_limit);
+	} else {
+		vty_out(vty, "Total IGMP groups: %u\n", pim->igmp_group_count);
+		vty_out(vty, "Watermark warn limit(%s): %u\n",
+			pim->igmp_watermark_limit ? "Set" : "Not Set",
+			pim->igmp_watermark_limit);
 		vty_out(vty,
 			"Interface        Address         Group           Mode Timer    Srcs V Uptime  \n");
+	}
 
 	/* scan interfaces */
 	FOR_ALL_INTERFACES (pim->vrf, ifp) {
@@ -6861,6 +6869,35 @@ DEFUN (no_ip_pim_packets,
 	return CMD_SUCCESS;
 }
 
+DEFPY (igmp_group_watermark,
+       igmp_group_watermark_cmd,
+       "ip igmp watermark-warn (10-60000)$limit",
+       IP_STR
+       IGMP_STR
+       "Configure group limit for watermark warning\n"
+       "Group count to generate watermark warning\n")
+{
+	PIM_DECLVAR_CONTEXT(vrf, pim);
+	pim->igmp_watermark_limit = limit;
+
+	return CMD_SUCCESS;
+}
+
+DEFPY (no_igmp_group_watermark,
+       no_igmp_group_watermark_cmd,
+       "no ip igmp watermark-warn [(10-60000)$limit]",
+       NO_STR
+       IP_STR
+       IGMP_STR
+       "Unconfigure group limit for watermark warning\n"
+       "Group count to generate watermark warning\n")
+{
+	PIM_DECLVAR_CONTEXT(vrf, pim);
+	pim->igmp_watermark_limit = 0;
+
+	return CMD_SUCCESS;
+}
+
 DEFUN (ip_pim_v6_secondary,
        ip_pim_v6_secondary_cmd,
        "ip pim send-v6-secondary",
@@ -10893,6 +10930,10 @@ void pim_cmd_init(void)
 	install_element(VRF_NODE, &no_ip_pim_ecmp_rebalance_cmd);
 	install_element(CONFIG_NODE, &ip_pim_mlag_cmd);
 	install_element(CONFIG_NODE, &no_ip_pim_mlag_cmd);
+	install_element(CONFIG_NODE, &igmp_group_watermark_cmd);
+	install_element(VRF_NODE, &igmp_group_watermark_cmd);
+	install_element(CONFIG_NODE, &no_igmp_group_watermark_cmd);
+	install_element(VRF_NODE, &no_igmp_group_watermark_cmd);
 
 	install_element(INTERFACE_NODE, &interface_ip_igmp_cmd);
 	install_element(INTERFACE_NODE, &interface_no_ip_igmp_cmd);

pimd/pim_igmp.c

@@ -753,6 +753,39 @@ static void igmp_group_free(struct igmp_group *group)
 	XFREE(MTYPE_PIM_IGMP_GROUP, group);
 }
 
+static void igmp_group_count_incr(struct igmp_sock *igmp)
+{
+	struct pim_interface *pim_ifp = igmp->interface->info;
+
+	if (!pim_ifp)
+		return;
+
+	++pim_ifp->pim->igmp_group_count;
+	if (pim_ifp->pim->igmp_group_count
+	    == pim_ifp->pim->igmp_watermark_limit) {
+		zlog_warn(
+			"IGMP group count reached watermark limit: %u(vrf: %s)",
+			pim_ifp->pim->igmp_group_count,
+			VRF_LOGNAME(pim_ifp->pim->vrf));
+	}
+}
+
+static void igmp_group_count_decr(struct igmp_sock *igmp)
+{
+	struct pim_interface *pim_ifp = igmp->interface->info;
+
+	if (!pim_ifp)
+		return;
+
+	if (pim_ifp->pim->igmp_group_count == 0) {
+		zlog_warn("Cannot decrement igmp group count below 0(vrf: %s)",
+			  VRF_LOGNAME(pim_ifp->pim->vrf));
+		return;
+	}
+
+	--pim_ifp->pim->igmp_group_count;
+}
+
 void igmp_group_delete(struct igmp_group *group)
 {
 	struct listnode *src_node;
@@ -778,6 +811,7 @@ void igmp_group_delete(struct igmp_group *group)
 	}
 
 	group_timer_off(group);
+	igmp_group_count_decr(group->group_igmp_sock);
 	listnode_delete(group->group_igmp_sock->igmp_group_list, group);
 	hash_release(group->group_igmp_sock->igmp_group_hash, group);
 
@@ -1158,6 +1192,8 @@ struct igmp_group *igmp_add_group_by_addr(struct igmp_sock *igmp,
 			group_str, igmp->fd, igmp->interface->name);
 	}
 
+	igmp_group_count_incr(igmp);
+
 	/*
 	  RFC 3376: 6.2.2. Definition of Group Timers
 

pimd/pim_instance.h

@@ -178,6 +178,8 @@ struct pim_instance {
 	struct list *ssmpingd_list;
 	struct in_addr ssmpingd_group_addr;
 
+	unsigned int igmp_group_count;
+	unsigned int igmp_watermark_limit;
 	unsigned int keep_alive_time;
 	unsigned int rp_keep_alive_time;
 

pimd/pim_vty.c

@@ -239,6 +239,13 @@ int pim_global_config_write_worker(struct pim_instance *pim, struct vty *vty)
 		vty_out(vty, "%sip pim ecmp\n", spaces);
 		++writes;
 	}
+
+	if (pim->igmp_watermark_limit != 0) {
+		vty_out(vty, "%sip igmp watermark-warn %u\n", spaces,
+			pim->igmp_watermark_limit);
+		++writes;
+	}
+
 	if (pim->ssmpingd_list) {
 		struct listnode *node;
 		struct ssmpingd_sock *ss;