1 files changed, 104 insertions, 0 deletions
diff --git a/src/sync-alarm.c b/src/sync-alarm.c
new file mode 100644
index 0000000..a0791ac
--- /dev/null
+++ b/src/sync-alarm.c
@@ -0,0 +1,104 @@
+/*
+ * (C) 2006-2007 by Pablo Neira Ayuso <pablo@netfilter.org>
+ * 
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "conntrackd.h"
+#include "sync.h"
+#include "network.h"
+#include "us-conntrack.h"
+#include "alarm.h"
+
+static void refresher(struct alarm_list *a, void *data)
+{
+	int len;
+	struct nethdr *net;
+	struct us_conntrack *u = data;
+
+	debug_ct(u->ct, "persistence update");
+
+	a->expires = random() % CONFIG(refresh) + 1;
+	net = BUILD_NETMSG(u->ct, NFCT_Q_UPDATE);
+	len = prepare_send_netmsg(STATE_SYNC(mcast_client), net);
+	mcast_buffered_send_netmsg(STATE_SYNC(mcast_client), net, len);
+}
+
+static void cache_alarm_add(struct us_conntrack *u, void *data)
+{
+	struct alarm_list *alarm = data;
+
+	init_alarm(alarm);
+	set_alarm_expiration(alarm, (random() % conf.refresh) + 1);
+	set_alarm_data(alarm, u);
+	set_alarm_function(alarm, refresher);
+	add_alarm(alarm);
+}
+
+static void cache_alarm_update(struct us_conntrack *u, void *data)
+{
+	struct alarm_list *alarm = data;
+	mod_alarm(alarm, (random() % conf.refresh) + 1);
+}
+
+static void cache_alarm_destroy(struct us_conntrack *u, void *data)
+{
+	struct alarm_list *alarm = data;
+	del_alarm(alarm);
+}
+
+static struct cache_extra cache_alarm_extra = {
+	.size 		= sizeof(struct alarm_list),
+	.add		= cache_alarm_add,
+	.update		= cache_alarm_update,
+	.destroy	= cache_alarm_destroy
+};
+
+static int alarm_recv(const struct nethdr *net)
+{
+	unsigned int exp_seq;
+
+	/* 
+	 * Ignore error messages: Although this message type is not ever
+	 * generated in alarm mode, we don't want to crash the daemon 
+	 * if someone nuts mixes ftfw and alarm.
+	 */
+	if (net->flags)
+		return 1;
+
+	/* 
+	 * Multicast sequence tracking: we keep track of multicast messages
+	 * although we don't do any explicit message recovery. So, why do
+	 * we do sequence tracking? Just to let know the sysadmin.
+	 *
+	 * Let t be 1 < t < RefreshTime. To ensure consistency, conntrackd
+	 * retransmit every t seconds a message with the state of a certain
+	 * entry even if such entry did not change. This mechanism also
+	 * provides passive resynchronization, in other words, there is
+	 * no facility to request a full synchronization from new nodes that
+	 * just joined the cluster, instead they just get resynchronized in
+	 * RefreshTime seconds at worst case.
+	 */
+	mcast_track_seq(net->seq, &exp_seq);
+
+	return 0;
+}
+
+struct sync_mode alarm = {
+	.internal_cache_flags	= LIFETIME,
+	.external_cache_flags	= TIMER | LIFETIME,
+	.internal_cache_extra	= &cache_alarm_extra,
+	.recv 			= alarm_recv,
+};