From: thorkill <thkr@hannover.ccc.de>
Date: Thu, 19 May 2016 13:48:15 +0000 (+0200)
Subject: Prevent tincd from sending packets to unexpecting nodes
X-Git-Tag: release-1.1pre15~74
X-Git-Url: https://tinc-vpn.org/git/browse?a=commitdiff_plain;h=5baecfd11be67bb80aab6c482e0b0ac98b267cca;p=tinc

Prevent tincd from sending packets to unexpecting nodes

Make tincd recognize when it was asleep and close connections to it's
peers. This happens when e.g. RoadWarrior has been suspended for
"longer" time period. After resume, it will start to communicate
with it's peers using the contextes it had before suspend.

On the other side, the nodes closed the connections since PingTimeout
and/or TCP connection went down.

Sending data to such unaware (sptps mostly) nodes will cause
havoc in the logs. Misleading the developers to wrong assumptions
that something is wrong with sptps.

# Conflicts:
#	src/net.c
---

diff --git a/src/net.c b/src/net.c
index 52c7fe3e..4f05789c 100644
--- a/src/net.c
+++ b/src/net.c
@@ -42,6 +42,7 @@ static int sleeptime = 10;
 time_t last_config_check = 0;
 static timeout_t pingtimer;
 static timeout_t periodictimer;
+static struct timeval last_periodic_run_time;
 
 /* Purge edges and subnets of unreachable nodes. Use carefully. */
 
@@ -144,10 +145,47 @@ void terminate_connection(connection_t *c, bool report) {
   and close the connection.
 */
 static void timeout_handler(void *data) {
+
+	bool close_all_connections = false;
+
+	/*
+		 timeout_hanlder will start after 30 seconds from start of tincd
+		 hold information about the elapsed time since last time the handler
+		 has been run
+	*/
+	long sleep_time = now.tv_sec - last_periodic_run_time.tv_sec;
+	/*
+		 It seems that finding sane default value is harder than expected
+		 Since we send every second a UDP packet to make holepunching work
+		 And default UDP state expire on firewalls is between 15-30 seconds
+		 we drop all connections after 60 Seconds - UDPDiscoveryTimeout=30
+		 by default
+	*/
+	if (sleep_time > 2 * udp_discovery_timeout) {
+		logger(DEBUG_ALWAYS, LOG_ERR, "Awaking from dead after %ld seconds of sleep", sleep_time);
+		/*
+			Do not send any packets to tinc after we wake up.
+			The other node probably closed our connection but we still
+			are holding context information to them. This may happen on
+			laptops or any other hardware which can be suspended for some time.
+			Sending any data to node that wasn't expecting it will produce
+			annoying and misleading errors on the other side about failed signature
+			verification and or about missing sptps context
+		*/
+		close_all_connections = true;
+	}
+	last_periodic_run_time = now;
+
 	for list_each(connection_t, c, connection_list) {
 		if(c->status.control)
 			continue;
 
+		if(close_all_connections) {
+			logger(DEBUG_ALWAYS, LOG_ERR, "Forcing connection close after sleep time %s (%s)", c->name, c->hostname);
+			terminate_connection(c, c->edge);
+			continue;
+		}
+
 		if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 			if(c->edge) {
 				try_tx(c->node, false);
@@ -457,6 +495,7 @@ void retry(void) {
   this is where it all happens...
 */
 int main_loop(void) {
+	last_periodic_run_time = now;
 	timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 	timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){0, 0});