cache iterators: rework cache_reset_timers

This patch adds the clause PurgeTimeout that sets the new timer
when conntrackd -t is called. This command is particularly useful
when the sysadmin triggers hand-overs between several nodes without
rebooting as it reduces the timers of the remaining entries in
the kernel. Thus, avoiding clashes between new and old entries that
may trigger INVALID packets.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 25 insertions, 20 deletions

diff --git a/src/cache_iterators.c b/src/cache_iterators.c
index a7c6654..8898930 100644
--- a/src/cache_iterators.c
+++ b/src/cache_iterators.c
@@ -55,6 +55,10 @@ static int do_dump(void *data1, void *data2)
 	if (CONFIG(flags) & CTD_SYNC_FTFW && alarm_pending(&u->alarm))
 		return 0;
 
+	/* do not show cached timeout, this may confuse users */
+	if (nfct_attr_is_set(u->ct, ATTR_TIMEOUT))
+		nfct_attr_unset(u->ct, ATTR_TIMEOUT);
+
 	memset(buf, 0, sizeof(buf));
 	size = nfct_snprintf(buf, 
 			     sizeof(buf), 
@@ -177,13 +181,11 @@ void cache_commit(struct cache *c)
 static int do_reset_timers(void *data1, void *data2)
 {
 	int ret;
+	u_int32_t current_timeout;
 	struct us_conntrack *u = data2;
 	struct nf_conntrack *ct = u->ct;
 
-	/* this may increase timers but they will end up dying shortly anyway */
-	nfct_set_attr_u32(ct, ATTR_TIMEOUT, CONFIG(commit_timeout));
-
-	ret = nl_exist_conntrack(ct);
+	ret = nl_get_conntrack(ct);
 	switch (ret) {
 	case -1:
 		/* the kernel table is not in sync with internal cache */
@@ -191,6 +193,13 @@ static int do_reset_timers(void *data1, void *data2)
 		dlog_ct(STATE(log), ct, NFCT_O_PLAIN);
 		break;
 	case 1:
+		current_timeout = nfct_get_attr_u32(ct, ATTR_TIMEOUT);
+		/* already about to die, do not touch it */
+		if (current_timeout < CONFIG(purge_timeout))
+			break;
+
+		nfct_set_attr_u32(ct, ATTR_TIMEOUT, CONFIG(purge_timeout));
+
 		if (nl_update_conntrack(ct) == -1) {
 			if (errno == ETIME || errno == ENOENT)
 				break;
diff --git a/src/read_config_lex.l b/src/read_config_lex.l
index 584a4a3..79d5b89 100644
--- a/src/read_config_lex.l
+++ b/src/read_config_lex.l
@@ -111,6 +111,7 @@ notrack		[N|n][O|o][T|t][R|r][A|a][C|c][K|k]
 "State"				{ return T_STATE; }
 "Accept"			{ return T_ACCEPT; }
 "Ignore"			{ return T_IGNORE; }
+"PurgeTimeout"			{ return T_PURGE; }
 
 {is_on}			{ return T_ON; }
 {is_off}		{ return T_OFF; }
diff --git a/src/read_config_yy.y b/src/read_config_yy.y
index 33a435c..c7bce82 100644
--- a/src/read_config_yy.y
+++ b/src/read_config_yy.y
@@ -52,7 +52,7 @@ static void __kernel_filter_add_state(int value);
 %token T_GENERAL T_SYNC T_STATS T_RELAX_TRANSITIONS T_BUFFER_SIZE T_DELAY
 %token T_SYNC_MODE T_LISTEN_TO T_FAMILY T_RESEND_BUFFER_SIZE
 %token T_ALARM T_FTFW T_CHECKSUM T_WINDOWSIZE T_ON T_OFF
-%token T_REPLICATE T_FOR T_IFACE 
+%token T_REPLICATE T_FOR T_IFACE T_PURGE
 %token T_ESTABLISHED T_SYN_SENT T_SYN_RECV T_FIN_WAIT 
 %token T_CLOSE_WAIT T_LAST_ACK T_TIME_WAIT T_CLOSE T_LISTEN
 %token T_SYSLOG T_WRITE_THROUGH T_STAT_BUFFER_SIZE T_DESTROY_TIMEOUT
@@ -163,6 +163,11 @@ timeout: T_TIMEOUT T_NUMBER
 	conf.commit_timeout = $2;
 };
 
+purge: T_PURGE T_NUMBER
+{
+	conf.purge_timeout = $2;
+};
+
 checksum: T_CHECKSUM T_ON 
 {
 	conf.mcast.checksum = 0;
@@ -427,6 +432,7 @@ sync_list:
 sync_line: refreshtime
 	 | expiretime
 	 | timeout
+	 | purge
 	 | checksum
 	 | multicast_line
 	 | relax_transitions
@@ -987,6 +993,10 @@ init_config(char *filename)
 	if (CONFIG(commit_timeout) == 0)
 		CONFIG(commit_timeout) = 180;
 
+	/* default to 15 seconds: purge kernel entries */
+	if (CONFIG(purge_timeout) == 0)
+		CONFIG(purge_timeout) = 15;
+
 	/* default to 60 seconds of refresh time */
 	if (CONFIG(refresh) == 0)
 		CONFIG(refresh) = 60;
diff --git a/src/sync-mode.c b/src/sync-mode.c
index 297a500..db199bc 100644
--- a/src/sync-mode.c
+++ b/src/sync-mode.c
@@ -378,9 +378,6 @@ static int local_handler_sync(int fd, int type, void *data)
 
 static void dump_sync(struct nf_conntrack *ct)
 {
-	if (!CONFIG(cache_write_through))
-		nfct_attr_unset(ct, ATTR_TIMEOUT);
-
 	/* This is required by kernels < 2.6.20 */
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_BYTES);
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_PACKETS);
@@ -438,9 +435,6 @@ static int overrun_sync(enum nf_conntrack_msg_type type,
 	if (ignore_conntrack(ct))
 		return NFCT_CB_CONTINUE;
 
-	if (!CONFIG(cache_write_through))
-		nfct_attr_unset(ct, ATTR_TIMEOUT);
-
 	/* This is required by kernels < 2.6.20 */
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_BYTES);
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_PACKETS);
@@ -462,9 +456,6 @@ static void event_new_sync(struct nf_conntrack *ct)
 {
 	struct us_conntrack *u;
 
-	if (!CONFIG(cache_write_through))
-		nfct_attr_unset(ct, ATTR_TIMEOUT);
-
 	/* required by linux kernel <= 2.6.20 */
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_BYTES);
 	nfct_attr_unset(ct, ATTR_ORIG_COUNTER_PACKETS);
@@ -490,9 +481,6 @@ static void event_update_sync(struct nf_conntrack *ct)
 {
 	struct us_conntrack *u;
 
-	if (!CONFIG(cache_write_through))
-		nfct_attr_unset(ct, ATTR_TIMEOUT);
-
 	if ((u = cache_update_force(STATE_SYNC(internal), ct)) == NULL) {
 		debug_ct(ct, "can't update");
 		return;
@@ -505,9 +493,6 @@ static int event_destroy_sync(struct nf_conntrack *ct)
 {
 	struct us_conntrack *u;
 
-	if (!CONFIG(cache_write_through))
-		nfct_attr_unset(ct, ATTR_TIMEOUT);
-
 	u = cache_find(STATE_SYNC(internal), ct);
 	if (u == NULL) {
 		debug_ct(ct, "can't destroy");