conntrackd: add -t option to shorten conntrack timeouts

This patch adds the new option `-t' for conntrackd. This option shortens
the value of the timeout for the cached entries that lives in the
kernel. This option is particularly useful to remove the zombie
established entries that remain in kernel if the user tests the platform
by forcing the takeover from one to another node several times.

We currently use the value of CommitTimeout which is sane for it. Adding
a new option does not seem to add more flexibility IMO.

Once we get the patches to notify user changes via ctnetlink and the
netlink flag NLM_F_ECHO works, we may directly invoke a massive purge of
the entries, however, such solution would still need evaluation.

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

3 files changed, 46 insertions, 0 deletions

diff --git a/src/cache_iterators.c b/src/cache_iterators.c
index 407db0b..2abb6cd 100644
--- a/src/cache_iterators.c
+++ b/src/cache_iterators.c
@@ -174,6 +174,40 @@ void cache_commit(struct cache *c)
 				 "committed", commit_fail);
 }
 
+static int do_reset_timers(void *data1, void *data2)
+{
+	int ret;
+	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);
+	switch (ret) {
+	case -1:
+	case 0:
+		/* the kernel table is not in sync with internal cache */
+		dlog(LOG_ERR, "reset-timers: %s", strerror(errno));
+		dlog_ct(STATE(log), ct, NFCT_O_PLAIN);
+		break;
+	case 1:
+		if (nl_update_conntrack(ct) == -1) {
+			if (errno == ETIME || errno == ENOENT)
+				break;
+			dlog(LOG_ERR, "reset-timers-upd: %s", strerror(errno));
+			dlog_ct(STATE(log), ct, NFCT_O_PLAIN);
+		}
+		break;
+	}
+	return 0;
+}
+
+void cache_reset_timers(struct cache *c)
+{
+	hashtable_iterate(c->h, NULL, do_reset_timers);
+}
+
 static int do_flush(void *data1, void *data2)
 {
 	struct cache *c = data1;
diff --git a/src/main.c b/src/main.c
index 084643c..a4c5451 100644
--- a/src/main.c
+++ b/src/main.c
@@ -148,6 +148,10 @@ int main(int argc, char *argv[])
 			set_operation_mode(&type, REQUEST, argv);
 			action = SEND_BULK;
 			break;
+		case 't':
+			set_operation_mode(&type, REQUEST, argv);
+			action = RESET_TIMERS;
+			break;
 		case 'k':
 			set_operation_mode(&type, REQUEST, argv);
 			action = KILL;
diff --git a/src/sync-mode.c b/src/sync-mode.c
index 56c30af..297a500 100644
--- a/src/sync-mode.c
+++ b/src/sync-mode.c
@@ -343,6 +343,14 @@ static int local_handler_sync(int fd, int type, void *data)
 			exit(EXIT_SUCCESS);
 		}
 		break;
+	case RESET_TIMERS:
+		ret = fork();
+		if (ret == 0) {
+			dlog(LOG_NOTICE, "resetting timers");
+			cache_reset_timers(STATE_SYNC(internal));
+			exit(EXIT_SUCCESS);
+		}
+		break;
 	case FLUSH_CACHE:
 		dlog(LOG_NOTICE, "flushing caches");
 		cache_flush(STATE_SYNC(internal));