[master] Add support for pool thresholds

Add support to set high and low thresholds for pools for
v4 and v6.  A message will be emitted when the usage of
the pool first exceeds the high threshold.  More messages
will be skipped until the usage has gone below the low
threshold and then back above the high threshold.

1 files changed, 100 insertions, 0 deletions

diff --git a/server/dhcpv6.c b/server/dhcpv6.c
index d1a42553..112d1e1c 100644
--- a/server/dhcpv6.c
+++ b/server/dhcpv6.c
@@ -796,6 +796,99 @@ set_status_code(u_int16_t status_code, const char *status_message,
 	return ret_val;
 }
 
+void check_pool6_threshold(struct reply_state *reply,
+			   struct iasubopt *lease)
+{
+	struct ipv6_pond *pond;
+	int used, count, high_threshold, poolhigh = 0, poollow = 0;
+	char *shared_name = "no name";
+	char tmp_addr[INET6_ADDRSTRLEN];
+
+	if ((lease->ipv6_pool == NULL) || (lease->ipv6_pool->ipv6_pond == NULL))
+		return;
+	pond = lease->ipv6_pool->ipv6_pond;
+
+	count = pond->num_total;
+	used = pond->num_active;
+
+	/* The logged flag indicates if we have already crossed the high
+	 * threshold and emitted a log message.  If it is set we check to
+	 * see if we have re-crossed the low threshold and need to reset
+	 * things.  When we cross the high threshold we determine what
+	 * the low threshold is and save it into the low_threshold value.
+	 * When we cross that threshold we reset the logged flag and
+	 * the low_threshold to 0 which allows the high threshold message
+	 * to be emitted once again.
+	 * if we haven't recrossed the boundry we don't need to do anything.
+	 */
+	if (pond->logged !=0) {
+		if (used <= pond->low_threshold) {
+			pond->low_threshold = 0;
+			pond->logged = 0;
+			log_error("Pool threshold reset - shared subnet: %s; "
+				  "address: %s; low threshold %d/%d.",
+				  shared_name,
+				  inet_ntop(AF_INET6, &lease->addr,
+					    tmp_addr, sizeof(tmp_addr)),
+				  used, count);
+		}
+		return;
+	}
+
+	/* find the high threshold */
+	if (get_option_int(&poolhigh, &server_universe, reply->packet, NULL,
+			   NULL, reply->packet->options, reply->opt_state,
+			   reply->opt_state, &lease->scope,
+			   SV_LOG_THRESHOLD_HIGH, MDL) == 0) {
+		/* no threshold bail out */
+		return;
+	}
+
+	/* We do have a threshold for this pool, see if its valid */
+	if ((poolhigh <= 0) || (poolhigh > 100)) {
+		/* not valid */
+		return;
+	}
+
+	/* we have a valid value, have we exceeded it */
+	high_threshold = FIND_PERCENT(count, poolhigh);
+	if (used < high_threshold) {
+		/* nope, no more to do */
+		return;
+	}
+
+	/* we've exceeded it, output a message */
+	if ((pond->shared_network != NULL) &&
+	    (pond->shared_network->name != NULL)) {
+		shared_name = pond->shared_network->name;
+	}
+	log_error("Pool threshold exceeded - shared subnet: %s; "
+		  "address: %s; high threshold %d%% %d/%d.",
+		  shared_name,
+		  inet_ntop(AF_INET6, &lease->addr, tmp_addr, sizeof(tmp_addr)),
+		  poolhigh, used, count);
+
+	/* handle the low threshold now, if we don't
+	 * have one we default to 0. */
+	if ((get_option_int(&poollow, &server_universe, reply->packet, NULL,
+			    NULL, reply->packet->options, reply->opt_state,
+			    reply->opt_state, &lease->scope,
+			    SV_LOG_THRESHOLD_LOW, MDL) == 0) ||
+	    (poollow > 100)) {
+		poollow = 0;
+	}
+
+	/*
+	 * If the low theshold is higher than the high threshold we continue to log
+	 * If it isn't then we set the flag saying we already logged and determine
+	 * what the reset threshold is.
+	 */
+	if (poollow < poolhigh) {
+		pond->logged = 1;
+		pond->low_threshold = FIND_PERCENT(count, poollow);
+	}
+}
+
 /*
  * We have a set of operations we do to set up the reply packet, which
  * is the same for many message types.
@@ -1939,6 +2032,8 @@ reply_process_ia_na(struct reply_state *reply, struct option_cache *ia) {
 					     tmp, NULL, reply->opt_state);
 			}
 #endif
+			/* Do our threshold check. */
+			check_pool6_threshold(reply, tmp);
 		}
 
 		/* Remove any old ia from the hash. */
@@ -2655,6 +2750,8 @@ reply_process_ia_ta(struct reply_state *reply, struct option_cache *ia) {
 					     tmp, NULL, reply->opt_state);
 			}
 #endif
+			/* Do our threshold check. */
+			check_pool6_threshold(reply, tmp);
 		}
 
 		/* Remove any old ia from the hash. */
@@ -3713,6 +3810,9 @@ reply_process_ia_pd(struct reply_state *reply, struct option_cache *ia) {
 				executable_statement_dereference
 					(&tmp->on_star.on_commit, MDL);
 			}
+
+			/* Do our threshold check. */
+			check_pool6_threshold(reply, tmp);
 		}
 
 		/* Remove any old ia from the hash. */