Fix for cluster handoff.

node/IncomingPacket.cpp

@@ -1206,6 +1206,8 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,void *tPt
 							(!( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) == 0) && (peer->hasActivePathTo(now,a)) )) && // not already known
 							(RR->node->shouldUsePathForZeroTierTraffic(tPtr,peer->address(),_path->localAddress(),a)) ) // should use path
 					{
+						if ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0)
+							peer->setClusterPreferred(a);
 						if (++countPerScope[(int)a.ipScope()][0] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
 							TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
 							peer->attemptToContactAt(tPtr,InetAddress(),a,now,false,0);
@@ -1221,6 +1223,8 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,void *tPt
 							(!( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) == 0) && (peer->hasActivePathTo(now,a)) )) && // not already known
 							(RR->node->shouldUsePathForZeroTierTraffic(tPtr,peer->address(),_path->localAddress(),a)) ) // should use path
 					{
+						if ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0)
+							peer->setClusterPreferred(a);
 						if (++countPerScope[(int)a.ipScope()][1] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
 							TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
 							peer->attemptToContactAt(tPtr,InetAddress(),a,now,false,0);

node/Peer.cpp

@@ -169,7 +169,7 @@ void Peer::received(
 			if (verb == Packet::VERB_OK) {
 				Mutex::Lock _l(_paths_m);
 				if (path->address().ss_family == AF_INET) {
-					if ((!_v4Path.p)||(!_v4Path.p->alive(now))||(path->preferenceRank() >= _v4Path.p->preferenceRank())) {
+					if ( (!_v4Path.p) || (!_v4Path.p->alive(now)) || ((_v4Path.p->address() != _v4ClusterPreferred)&&(path->preferenceRank() >= _v4Path.p->preferenceRank())) ) {
 						_v4Path.lr = now;
 						_v4Path.p = path;
 #ifdef ZT_ENABLE_CLUSTER
@@ -179,7 +179,7 @@ void Peer::received(
 #endif
 					}
 				} else if (path->address().ss_family == AF_INET6) {
-					if ((!_v6Path.p)||(!_v6Path.p->alive(now))||(path->preferenceRank() >= _v6Path.p->preferenceRank())) {
+					if ( (!_v6Path.p) || (!_v6Path.p->alive(now)) || ((_v6Path.p->address() != _v6ClusterPreferred)&&(path->preferenceRank() >= _v6Path.p->preferenceRank())) ) {
 						_v6Path.lr = now;
 						_v6Path.p = path;
 #ifdef ZT_ENABLE_CLUSTER

node/Peer.hpp

@@ -210,6 +210,19 @@ public:
 		}
 	}
 
+	/**
+	 * Indicate that the given address was provided by a cluster as a preferred destination
+	 *
+	 * @param addr Address cluster prefers that we use
+	 */
+	inline void setClusterPreferred(const InetAddress &addr)
+	{
+		if (addr.ss_family == AF_INET)
+			_v4ClusterPreferred = addr;
+		else if (addr.ss_family == AF_INET6)
+			_v6ClusterPreferred = addr;
+	}
+
 	/**
 	 * Fill parameters with V4 and V6 addresses if known and alive
 	 *
@@ -465,6 +478,9 @@ private:
 	uint16_t _vMinor;
 	uint16_t _vRevision;
 
+	InetAddress _v4ClusterPreferred;
+	InetAddress _v6ClusterPreferred;
+
 	_PeerPath _v4Path; // IPv4 direct path
 	_PeerPath _v6Path; // IPv6 direct path
 	Mutex _paths_m;