Use ECHO instead of HELLO where possible.

node/IncomingPacket.cpp

@@ -526,7 +526,7 @@ bool IncomingPacket::_doRENDEZVOUS(const RuntimeEnvironment *RR,const SharedPtr<
 					TRACE("RENDEZVOUS from %s says %s might be at %s, ignoring since peer is not upstream",peer->address().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
 				} else if (RR->node->shouldUsePathForZeroTierTraffic(_path->localAddress(),atAddr)) {
 					RR->node->putPacket(_path->localAddress(),atAddr,"ABRE",4,2); // send low-TTL junk packet to 'open' local NAT(s) and stateful firewalls
-					rendezvousWith->sendHELLO(_path->localAddress(),atAddr,RR->node->now());
+					rendezvousWith->attemptToContactAt(_path->localAddress(),atAddr,RR->node->now());
 					TRACE("RENDEZVOUS from %s says %s might be at %s, sent verification attempt",peer->address().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
 				} else {
 					TRACE("RENDEZVOUS from %s says %s might be at %s, ignoring since path is not suitable",peer->address().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
@@ -1050,7 +1050,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 					if ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_FORGET_PATH) == 0) && (!redundant) && (RR->node->shouldUsePathForZeroTierTraffic(_path->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);
+							peer->attemptToContactAt(InetAddress(),a,now);
 						} else {
 							TRACE("ignoring contact for %s at %s -- too many per scope",peer->address().toString().c_str(),a.toString().c_str());
 						}
@@ -1069,7 +1069,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 					if ( ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_FORGET_PATH) == 0) && (!redundant) && (RR->node->shouldUsePathForZeroTierTraffic(_path->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);
+							peer->attemptToContactAt(InetAddress(),a,now);
 						} else {
 							TRACE("ignoring contact for %s at %s -- too many per scope",peer->address().toString().c_str(),a.toString().c_str());
 						}

node/Path.hpp

@@ -137,6 +137,13 @@ public:
 	 */
 	bool send(const RuntimeEnvironment *RR,const void *data,unsigned int len,uint64_t now);
 
+	/**
+	 * Manually update last sent time
+	 *
+	 * @param t Time of send
+	 */
+	inline void sent(const uint64_t t) { _lastOut = t; }
+
 	/**
 	 * @return Address of local side of this path or NULL if unspecified
 	 */

node/Peer.cpp

@@ -189,16 +189,8 @@ void Peer::received(
 #endif
 			} else {
 				TRACE("got %s via unknown path %s(%s), confirming...",Packet::verbString(verb),_id.address().toString().c_str(),path->address().toString().c_str());
-
-				if ( (_vProto >= 5) && ( !((_vMajor == 1)&&(_vMinor == 1)&&(_vRevision == 0)) ) ) {
-					// Newer than 1.1.0 can use ECHO, which is smaller
-					Packet outp(_id.address(),RR->identity.address(),Packet::VERB_ECHO);
-					outp.armor(_key,true);
-					path->send(RR,outp.data(),outp.size(),now);
-				} else {
-					// For backward compatibility we send HELLO to ancient nodes
-					sendHELLO(path->localAddress(),path->address(),now);
-				}
+				attemptToContactAt(path->localAddress(),path->address(),now);
+				path->sent(now);
 			}
 		}
 	} else if (trustEstablished) {
@@ -254,7 +246,7 @@ SharedPtr<Path> Peer::getBestPath(uint64_t now,bool includeExpired)
 	int bestp = -1;
 	uint64_t best = 0ULL;
 	for(unsigned int p=0;p<_numPaths;++p) {
-		if ( ((now - _paths[p].lastReceive) < ZT_PEER_PATH_EXPIRATION) || (includeExpired) ) {
+		if ( ((now - _paths[p].lastReceive) <= ZT_PEER_PATH_EXPIRATION) || (includeExpired) ) {
 			const uint64_t s = _pathScore(p,now);
 			if (s >= best) {
 				best = s;
@@ -286,6 +278,17 @@ void Peer::sendHELLO(const InetAddress &localAddr,const InetAddress &atAddress,u
 	RR->node->putPacket(localAddr,atAddress,outp.data(),outp.size());
 }
 
+void Peer::attemptToContactAt(const InetAddress &localAddr,const InetAddress &atAddress,uint64_t now)
+{
+	if ( (_vProto >= 5) && ( !((_vMajor == 1)&&(_vMinor == 1)&&(_vRevision == 0)) ) ) {
+		Packet outp(_id.address(),RR->identity.address(),Packet::VERB_ECHO);
+		outp.armor(_key,true);
+		RR->node->putPacket(localAddr,atAddress,outp.data(),outp.size());
+	} else {
+		sendHELLO(localAddr,atAddress,now);
+	}
+}
+
 bool Peer::doPingAndKeepalive(uint64_t now,int inetAddressFamily)
 {
 	Mutex::Lock _l(_paths_m);
@@ -304,7 +307,8 @@ bool Peer::doPingAndKeepalive(uint64_t now,int inetAddressFamily)
 
 	if (bestp >= 0) {
 		if ((now - _paths[bestp].lastReceive) >= ZT_PEER_PING_PERIOD) {
-			sendHELLO(_paths[bestp].path->localAddress(),_paths[bestp].path->address(),now);
+			attemptToContactAt(_paths[bestp].path->localAddress(),_paths[bestp].path->address(),now);
+			_paths[bestp].path->sent(now);
 		} else if (_paths[bestp].path->needsHeartbeat(now)) {
 			_natKeepaliveBuf += (uint32_t)((now * 0x9e3779b1) >> 1); // tumble this around to send constantly varying (meaningless) payloads
 			_paths[bestp].path->send(RR,&_natKeepaliveBuf,sizeof(_natKeepaliveBuf),now);
@@ -331,7 +335,8 @@ bool Peer::resetWithinScope(InetAddress::IpScope scope,int inetAddressFamily,uin
 	bool resetSomething = false;
 	for(unsigned int p=0;p<_numPaths;++p) {
 		if ( (_paths[p].path->address().ss_family == inetAddressFamily) && (_paths[p].path->address().ipScope() == scope) ) {
-			sendHELLO(_paths[p].path->localAddress(),_paths[p].path->address(),now);
+			attemptToContactAt(_paths[p].path->localAddress(),_paths[p].path->address(),now);
+			_paths[p].path->sent(now);
 			_paths[p].lastReceive >>= 2; // de-prioritize heavily vs. other paths, will get reset if we get OK(HELLO) or other traffic
 			resetSomething = true;
 		}

node/Peer.hpp

@@ -165,6 +165,17 @@ public:
 	 */
 	void sendHELLO(const InetAddress &localAddr,const InetAddress &atAddress,uint64_t now);
 
+	/**
+	 * Send ECHO (or HELLO for older peers) to this peer at the given address
+	 *
+	 * No statistics or sent times are updated here.
+	 *
+	 * @param localAddr Local address
+	 * @param atAddress Destination address
+	 * @param now Current time
+	 */
+	void attemptToContactAt(const InetAddress &localAddr,const InetAddress &atAddress,uint64_t now);
+
 	/**
 	 * Send pings or keepalives depending on configured timeouts
 	 *