(1) cluster members send a flag indicating that a PUSH_DIRECT_PATHS is a cluster redirect, (2) 1.1.5 uses this to avoid a bug (this bug does not exist in 1.1.4)

node/IncomingPacket.cpp

@@ -933,7 +933,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 			switch(addrType) {
 				case 4: {
 					InetAddress a(field(ptr,4),4,at<uint16_t>(ptr + 4));
-					if ( ((flags & 0x01) == 0) && (!peer->hasActivePathTo(now,a)) && (RR->node->shouldUsePathForZeroTierTraffic(_localAddress,a)) ) {
+					if ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_FORGET_PATH) == 0) && ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0) || (!peer->hasActivePathTo(now,a)) ) && (RR->node->shouldUsePathForZeroTierTraffic(_localAddress,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->sendHELLO(InetAddress(),a,now);
@@ -944,7 +944,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 				}	break;
 				case 6: {
 					InetAddress a(field(ptr,16),16,at<uint16_t>(ptr + 16));
-					if ( ((flags & 0x01) == 0) && (!peer->hasActivePathTo(now,a)) && (RR->node->shouldUsePathForZeroTierTraffic(_localAddress,a)) ) {
+					if ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_FORGET_PATH) == 0) && ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0) || (!peer->hasActivePathTo(now,a)) ) && (RR->node->shouldUsePathForZeroTierTraffic(_localAddress,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->sendHELLO(InetAddress(),a,now);

node/Packet.hpp

@@ -176,6 +176,16 @@
  */
 #define ZT_PROTO_SALSA20_ROUNDS 12
 
+/**
+ * PUSH_DIRECT_PATHS flag: forget path
+ */
+#define ZT_PUSH_DIRECT_PATHS_FLAG_FORGET_PATH 0x01
+
+/**
+ * PUSH_DIRECT_PATHS flag: cluster redirect
+ */
+#define ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT 0x02
+
 // Field indexes in packet header
 #define ZT_PACKET_IDX_IV 0
 #define ZT_PACKET_IDX_DEST 8
@@ -819,7 +829,7 @@ public:
 		 *   <[...] paths>
 		 *
 		 * Path record format:
-		 *   <[1] flags>
+		 *   <[1] 8-bit path flags>
 		 *   <[2] length of extended path characteristics or 0 for none>
 		 *   <[...] extended path characteristics>
 		 *   <[1] address type>
@@ -827,10 +837,8 @@ public:
 		 *   <[...] address>
 		 *
 		 * Path record flags:
-		 *   0x01 - Forget this path if it is currently known
-		 *   0x02 - (Unused)
-		 *   0x04 - Disable encryption (trust: privacy)
-		 *   0x08 - Disable encryption and authentication (trust: ultimate)
+		 *   0x01 - Forget this path if currently known (not implemented yet)
+		 *   0x02 - Cluster redirect -- use this in preference to others
 		 *
 		 * The receiver may, upon receiving a push, attempt to establish a
 		 * direct link to one or more of the indicated addresses. It is the

node/Peer.cpp

@@ -81,7 +81,7 @@ void Peer::received(
 				// For newer peers we can send a more idiomatic verb: PUSH_DIRECT_PATHS.
 				Packet outp(_id.address(),RR->identity.address(),Packet::VERB_PUSH_DIRECT_PATHS);
 				outp.append((uint16_t)1); // count == 1
-				outp.append((uint8_t)0); // no flags
+				outp.append((uint8_t)ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT); // flags: cluster redirect
 				outp.append((uint16_t)0); // no extensions
 				if (redirectTo.ss_family == AF_INET) {
 					outp.append((uint8_t)4);