More tweaks to algorithm for determining when to fail over to TCP, and stop supernodes from resynchronizing unless explicitly ordered.

node/Constants.hpp

@@ -305,9 +305,14 @@ error_no_byte_order_defined;
 #define ZT_TCP_TUNNEL_ACTIVITY_TIMEOUT ZT_PEER_PATH_ACTIVITY_TIMEOUT
 
 /**
- * Try TCP tunnels if no response to UDP PINGs in this many milliseconds
+ * Try TCP tunnels if nothing received for this long
  */
-#define ZT_PING_UNANSWERED_AFTER 5000
+#define ZT_TCP_TUNNEL_FAILOVER_TIMEOUT 5000
+
+/**
+ * Try to ping supernodes this often until we get something from somewhere
+ */
+#define ZT_STARTUP_AGGRO 5000
 
 /**
  * Stop relaying via peers that have not responded to direct sends in this long

node/Node.cpp

@@ -540,7 +540,7 @@ Node::ReasonForTermination Node::run()
 		long lastDelayDelta = 0;
 
 		uint64_t networkConfigurationFingerprint = 0;
-		_r->timeOfLastResynchronize = 0;
+		_r->timeOfLastResynchronize = Utils::now();
 
 		while (impl->reasonForTermination == NODE_RUNNING) {
 			if (Utils::fileExists(shutdownIfUnreadablePath.c_str(),false)) {
@@ -551,13 +551,7 @@ Node::ReasonForTermination Node::run()
 			}
 
 			uint64_t now = Utils::now();
-
+			bool resynchronize = false;
-			// Did the user send SIGHUP or otherwise order network resync? (mostly for debugging)
-			bool resynchronize = impl->resynchronize;
-			impl->resynchronize = false;
-			if (resynchronize) {
-				LOG("manual resynchronize ordered, resyncing with network");
-			}
 
 			// If it looks like the computer slept and woke, resynchronize.
 			if (lastDelayDelta >= ZT_SLEEP_WAKE_DETECTION_THRESHOLD) {
@@ -577,18 +571,29 @@ Node::ReasonForTermination Node::run()
 				}
 			}
 
+			// Supernodes do not resynchronize unless explicitly ordered via SIGHUP.
+			if ((resynchronize)&&(_r->topology->amSupernode()))
+				resynchronize = false;
+
+			// Check for SIGHUP / force resync.
+			if (impl->resynchronize) {
+				impl->resynchronize = false;
+				resynchronize = true;
+				LOG("resynchronize forced by user, syncing with network");
+			}
+
 			if (resynchronize)
 				_r->timeOfLastResynchronize = now;
 
 			/* Ping supernodes separately, and do so more aggressively if we haven't
 			 * heard anything from anyone since our last resynchronize / startup. */
 			if ( ((now - lastSupernodePing) >= ZT_PEER_DIRECT_PING_DELAY) ||
-			     ((_r->timeOfLastResynchronize > _r->timeOfLastPacketReceived) && ((now - lastSupernodePing) >= ZT_PING_UNANSWERED_AFTER)) ) {
+			     ((_r->timeOfLastResynchronize > _r->timeOfLastPacketReceived) && ((now - lastSupernodePing) >= ZT_STARTUP_AGGRO)) ) {
 				lastSupernodePing = now;
 				std::vector< SharedPtr<Peer> > sns(_r->topology->supernodePeers());
 				TRACE("pinging %d supernodes",(int)sns.size());
 				for(std::vector< SharedPtr<Peer> >::const_iterator p(sns.begin());p!=sns.end();++p)
-					(*p)->sendPing(_r,now,resynchronize);
+					(*p)->sendPing(_r,now);
 			}
 
 			if (resynchronize) {
@@ -625,7 +630,7 @@ Node::ReasonForTermination Node::run()
 					if ((now - lastPingCheck) >= ZT_PING_CHECK_DELAY) {
 						lastPingCheck = now;
 						try {
-							_r->topology->eachPeer(Topology::PingPeersThatNeedPing(_r,now,resynchronize));
+							_r->topology->eachPeer(Topology::PingPeersThatNeedPing(_r,now));
 							_r->topology->eachPeer(Topology::OpenPeersThatNeedFirewallOpener(_r,now));
 						} catch (std::exception &exc) {
 							LOG("unexpected exception running ping check cycle: %s",exc.what());

node/PacketDecoder.cpp

@@ -490,6 +490,7 @@ bool PacketDecoder::_doMULTICAST_FRAME(const RuntimeEnvironment *_r,const Shared
 		const unsigned int signatureLen = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen);
 		const unsigned char *const signature = field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen + 2,signatureLen);
 
+		/*
 		TRACE("MULTICAST_FRAME @%.16llx #%.16llx from %s<%s> via %s(%s) to %s [ %s, %d bytes, depth %d ]",
 			(unsigned long long)nwid,
 			(unsigned long long)guid,
@@ -499,6 +500,7 @@ bool PacketDecoder::_doMULTICAST_FRAME(const RuntimeEnvironment *_r,const Shared
 			Switch::etherTypeName(etherType),
 			(int)frameLen,
 			(int)depth);
+		*/
 
 		SharedPtr<Network> network(_r->nc->network(nwid));
 

node/Peer.cpp

@@ -117,8 +117,13 @@ void Peer::receive(
 		_lastMulticastFrame = now;
 }
 
+
 bool Peer::send(const RuntimeEnvironment *_r,const void *data,unsigned int len,uint64_t now)
 {
+	// Note: we'll still use TCP here if that's all we have, but if this
+	// is false we will prefer UDP.
+	bool useTcp = isTcpFailoverTime(_r,now);
+
 	Mutex::Lock _l(_lock);
 
 	std::vector<Path>::iterator p(_paths.begin());
@@ -127,11 +132,13 @@ bool Peer::send(const RuntimeEnvironment *_r,const void *data,unsigned int len,u
 
 	uint64_t bestPathLastReceived = p->lastReceived();
 	std::vector<Path>::iterator bestPath = p;
+	bool bestPathIsTcp = p->tcp();
 	while (++p != _paths.end()) {
 		uint64_t lr = p->lastReceived();
-		if (lr > bestPathLastReceived) {
+		if ( (lr > bestPathLastReceived) || ((bestPathIsTcp)&&(!useTcp)) ) {
 			bestPathLastReceived = lr;
 			bestPath = p;
+			bestPathIsTcp = p->tcp();
 		}
 	}
 
@@ -156,35 +163,19 @@ bool Peer::sendFirewallOpener(const RuntimeEnvironment *_r,uint64_t now)
 	return sent;
 }
 
-bool Peer::sendPing(const RuntimeEnvironment *_r,uint64_t now,bool firstSinceReset)
+bool Peer::sendPing(const RuntimeEnvironment *_r,uint64_t now)
 {
 	bool sent = false;
 	SharedPtr<Peer> self(this);
 
+	// In the ping case we will never send TCP unless this returns true.
+	bool useTcp = isTcpFailoverTime(_r,now);
+
+	TRACE("PING %s (useTcp==%d)",_id.address().toString().c_str(),(int)useTcp);
+
 	Mutex::Lock _l(_lock);
-
-	// NOTE: this will never ping a peer that has *only* TCP paths. Right
-	// now there's never such a thing as TCP is only for failover.
-
-	bool pingTcp;
-	if (!firstSinceReset) {
-		uint64_t lastUdp = 0;
-		uint64_t lastTcp = 0;
-		uint64_t lastPing = 0;
-		for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-			if (p->tcp())
-				lastTcp = std::max(p->lastReceived(),lastTcp);
-			else lastUdp = std::max(p->lastReceived(),lastUdp);
-			lastPing = std::max(p->lastPing(),lastPing);
-		}
-		uint64_t lastAny = std::max(lastUdp,lastTcp);
-		pingTcp = ( ( (lastAny < lastPing) && ((lastPing - lastAny) >= ZT_PING_UNANSWERED_AFTER) ) || (lastTcp > lastUdp) );
-	} else pingTcp = false;
-
-	TRACE("PING %s (pingTcp==%d)",_id.address().toString().c_str(),(int)pingTcp);
-
 	for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-		if ((pingTcp)||(!p->tcp())) {
+		if ((useTcp)||(!p->tcp())) {
 			if (_r->sw->sendHELLO(self,*p)) {
 				p->sent(now);
 				p->pinged(now);

node/Peer.hpp

@@ -160,10 +160,9 @@ public:
 	 * 
 	 * @param _r Runtime environment
 	 * @param now Current time
-	 * @param firstSinceReset If true, this is the first ping sent since a network reset
 	 * @return True if send appears successful for at least one address type
 	 */
-	bool sendPing(const RuntimeEnvironment *_r,uint64_t now,bool firstSinceReset);
+	bool sendPing(const RuntimeEnvironment *_r,uint64_t now);
 
 	/**
 	 * Called periodically by Topology::clean() to remove stale paths and do other cleanup
@@ -263,6 +262,33 @@ public:
 		return _lastAnnouncedTo;
 	}
 
+	/**
+	 * @param _r Runtime environment
+	 * @param now Current time
+	 * @return True if it's time to attempt TCP failover (if we have TCP_OUT paths)
+	 */
+	inline bool isTcpFailoverTime(const RuntimeEnvironment *_r,uint64_t now) const
+		throw()
+	{
+		if ((now - _r->timeOfLastResynchronize) >= ZT_TCP_TUNNEL_FAILOVER_TIMEOUT) {
+			uint64_t lastUdpPingSent = 0;
+			uint64_t lastUdpReceive = 0;
+
+			{
+				Mutex::Lock _l(_lock);
+				for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
+					if (p->type() == Path::PATH_TYPE_UDP) {
+						lastUdpPingSent = std::max(lastUdpPingSent,p->lastPing());
+						lastUdpReceive = std::max(lastUdpReceive,p->lastReceived());
+					}
+				}
+			}
+
+			return ( (lastUdpPingSent > lastUdpReceive) && ((now - lastUdpPingSent) >= ZT_TCP_TUNNEL_FAILOVER_TIMEOUT) );
+		}
+		return false;
+	}
+
 	/**
 	 * @return Current latency or 0 if unknown (max: 65535)
 	 */

node/Topology.hpp

@@ -207,11 +207,10 @@ public:
 	class PingPeersThatNeedPing
 	{
 	public:
-		PingPeersThatNeedPing(const RuntimeEnvironment *renv,uint64_t now,bool firstSinceReset) throw() :
+		PingPeersThatNeedPing(const RuntimeEnvironment *renv,uint64_t now) throw() :
 			_now(now),
 			_supernodeAddresses(renv->topology->supernodeAddresses()),
-			_r(renv),
+			_r(renv) {}
-			_firstSinceReset(firstSinceReset) {}
 
 		inline void operator()(Topology &t,const SharedPtr<Peer> &p)
 		{
@@ -228,14 +227,13 @@ public:
 			       /* 2b: peer is not a supernode */
 					   (!_supernodeAddresses.count(p->address()))
 			     )
-			   ) { p->sendPing(_r,_now,_firstSinceReset); }
+			   ) { p->sendPing(_r,_now); }
 		}
 
 	private:
 		uint64_t _now;
 		std::set<Address> _supernodeAddresses;
 		const RuntimeEnvironment *_r;
-		bool _firstSinceReset;
 	};
 
 	/**