Refactor path stability stuff and add basic multipath support.

node/Constants.hpp

@@ -268,16 +268,6 @@
  */
 #define ZT_PATH_HEARTBEAT_PERIOD 14000
 
-/**
- * Paths are considered inactive if they have not received traffic in this long
- */
-#define ZT_PATH_ALIVE_TIMEOUT 45000
-
-/**
- * Minimum time between attempts to check dead paths to see if they can be re-awakened
- */
-#define ZT_PATH_MIN_REACTIVATE_INTERVAL 2500
-
 /**
  * Do not accept HELLOs over a given path more often than this
  */

node/Hashtable.hpp

@@ -42,11 +42,6 @@ namespace ZeroTier {
 
 /**
  * A minimal hash table implementation for the ZeroTier core
- *
- * This is not a drop-in replacement for STL containers, and has several
- * limitations. Keys can be uint64_t or an object, and if the latter they
- * must implement a method called hashCode() that returns an unsigned long
- * value that is evenly distributed.
  */
 template<typename K,typename V>
 class Hashtable

node/IncomingPacket.cpp

@@ -446,7 +446,8 @@ bool IncomingPacket::_doOK(const RuntimeEnvironment *RR,void *tPtr,const SharedP
 			}
 
 			if (!hops())
-				peer->addDirectLatencyMeasurment((unsigned int)latency);
+				_path->updateLatency((unsigned int)latency);
+
 			peer->setRemoteVersion(vProto,vMajor,vMinor,vRevision);
 
 			if ((externalSurfaceAddress)&&(hops() == 0))
@@ -1091,7 +1092,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,void *tPt
 						(RR->node->shouldUsePathForZeroTierTraffic(tPtr,peer->address(),_path->localSocket(),a)) ) // should use path
 				{
 					if ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0) {
-						peer->redirect(tPtr,_path->localSocket(),a,now);
+						peer->clusterRedirect(tPtr,_path->localSocket(),a,now);
 					} else if (++countPerScope[(int)a.ipScope()][0] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
 						peer->attemptToContactAt(tPtr,InetAddress(),a,now,false,0);
 					}
@@ -1105,7 +1106,7 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,void *tPt
 						(RR->node->shouldUsePathForZeroTierTraffic(tPtr,peer->address(),_path->localSocket(),a)) ) // should use path
 				{
 					if ((flags & ZT_PUSH_DIRECT_PATHS_FLAG_CLUSTER_REDIRECT) != 0) {
-						peer->redirect(tPtr,_path->localSocket(),a,now);
+						peer->clusterRedirect(tPtr,_path->localSocket(),a,now);
 					} else if (++countPerScope[(int)a.ipScope()][1] <= ZT_PUSH_DIRECT_PATHS_MAX_PER_SCOPE_AND_FAMILY) {
 						peer->attemptToContactAt(tPtr,InetAddress(),a,now,false,0);
 					}

node/InetAddress.cpp

@@ -273,9 +273,8 @@ InetAddress InetAddress::network() const
 	return r;
 }
 
-#ifdef ZT_SDK
+bool InetAddress::isEqualPrefix(const InetAddress &addr) const
-	bool InetAddress::isEqualPrefix(const InetAddress &addr) const
+{
-	{
 	if (addr.ss_family == ss_family) {
 		switch(ss_family) {
 			case AF_INET6: {
@@ -294,8 +293,7 @@ InetAddress InetAddress::network() const
 		}
 	}
 	return false;
-	}
+}
-#endif
 	
 bool InetAddress::containsAddress(const InetAddress &addr) const
 {

node/InetAddress.hpp

@@ -330,7 +330,6 @@ struct InetAddress : public sockaddr_storage
 	 */
 	InetAddress network() const;
 
-#ifdef ZT_SDK
 	/**
 	 * Test whether this IPv6 prefix matches the prefix of a given IPv6 address
 	 *
@@ -338,7 +337,6 @@ struct InetAddress : public sockaddr_storage
 	 * @return True if this IPv6 prefix matches the prefix of a given IPv6 address
 	 */
 	bool isEqualPrefix(const InetAddress &addr) const;
-#endif
 
 	/**
 	 * Test whether this IP/netmask contains this address

node/Node.cpp

@@ -191,12 +191,13 @@ public:
 	{
 		const std::vector<InetAddress> *const upstreamStableEndpoints = _upstreamsToContact.get(p->address());
 		if (upstreamStableEndpoints) {
-			bool contacted = false;
-
 			// Upstreams must be pinged constantly over both IPv4 and IPv6 to allow
 			// them to perform three way handshake introductions for both stacks.
 
-			if (!p->doPingAndKeepalive(_tPtr,_now,AF_INET)) {
+			const unsigned int sent = p->doPingAndKeepalive(_tPtr,_now);
+			bool contacted = (sent != 0);
+
+			if ((sent & 0x1) == 0) { // bit 0x1 == IPv4 sent
 				for(unsigned long k=0,ptr=(unsigned long)RR->node->prng();k<(unsigned long)upstreamStableEndpoints->size();++k) {
 					const InetAddress &addr = (*upstreamStableEndpoints)[ptr++ % upstreamStableEndpoints->size()];
 					if (addr.ss_family == AF_INET) {
@@ -205,8 +206,9 @@ public:
 						break;
 					}
 				}
-			} else contacted = true;
+			}
-			if (!p->doPingAndKeepalive(_tPtr,_now,AF_INET6)) {
+
+			if ((sent & 0x2) == 0) { // bit 0x2 == IPv6 sent
 				for(unsigned long k=0,ptr=(unsigned long)RR->node->prng();k<(unsigned long)upstreamStableEndpoints->size();++k) {
 					const InetAddress &addr = (*upstreamStableEndpoints)[ptr++ % upstreamStableEndpoints->size()];
 					if (addr.ss_family == AF_INET6) {
@@ -215,8 +217,10 @@ public:
 						break;
 					}
 				}
-			} else contacted = true;
+			}
 
+			// If we have no memoized addresses for this upstream peer, attempt to contact
+			// it indirectly so we will be introduced.
 			if ((!contacted)&&(_bestCurrentUpstream)) {
 				const SharedPtr<Path> up(_bestCurrentUpstream->getBestPath(_now,true));
 				if (up)
@@ -224,9 +228,11 @@ public:
 			}
 
 			lastReceiveFromUpstream = std::max(p->lastReceive(),lastReceiveFromUpstream);
-			_upstreamsToContact.erase(p->address()); // erase from upstreams to contact so that we can WHOIS those that remain
+
+			_upstreamsToContact.erase(p->address()); // after this we'll WHOIS all upstreams that remain
 		} else if (p->isActive(_now)) {
-			p->doPingAndKeepalive(_tPtr,_now,-1);
+			// Regular non-upstream nodes get pinged if they appear active.
+			p->doPingAndKeepalive(_tPtr,_now);
 		}
 	}
 
@@ -420,7 +426,7 @@ ZT_PeerList *Node::peers() const
 			p->versionMinor = -1;
 			p->versionRev = -1;
 		}
-		p->latency = pi->second->latency();
+		p->latency = pi->second->latency(_now);
 		p->role = RR->topology->role(pi->second->identity().address());
 
 		std::vector< SharedPtr<Path> > paths(pi->second->paths(_now));

node/Path.hpp

@@ -100,6 +100,7 @@ public:
 		_incomingLinkQualitySlowLogCounter(-64), // discard first fast log
 		_incomingLinkQualityPreviousPacketCounter(0),
 		_outgoingPacketCounter(0),
+		_latency(0xffff),
 		_addr(),
 		_ipScope(InetAddress::IP_SCOPE_NONE)
 	{
@@ -117,6 +118,7 @@ public:
 		_incomingLinkQualitySlowLogCounter(-64), // discard first fast log
 		_incomingLinkQualityPreviousPacketCounter(0),
 		_outgoingPacketCounter(0),
+		_latency(0xffff),
 		_addr(addr),
 		_ipScope(addr.ipScope())
 	{
@@ -188,6 +190,19 @@ public:
 	 */
 	inline void sent(const int64_t t) { _lastOut = t; }
 
+	/**
+	 * Update path latency with a new measurement
+	 *
+	 * @param l Measured latency
+	 */
+	inline void updateLatency(const unsigned int l)
+	{
+		unsigned int pl = _latency;
+		if (pl < 0xffff)
+			_latency = (pl + l) / 2;
+		else _latency = l;
+	}
+
 	/**
 	 * @return Local socket as specified by external code
 	 */
@@ -259,9 +274,19 @@ public:
 	}
 
 	/**
-	 * @return True if path appears alive
+	 * @return Latency or 0xffff if unknown
 	 */
-	inline bool alive(const int64_t now) const { return ((now - _lastIn) <= ZT_PATH_ALIVE_TIMEOUT); }
+	inline unsigned int latency() const { return _latency; }
+
+	/**
+	 * @return Path quality -- lower is better
+	 */
+	inline int quality(const int64_t now) const
+	{
+		const int l = (int)_latency;
+		const int age = (int)std::min((now - _lastIn),(int64_t)(ZT_PATH_HEARTBEAT_PERIOD * 10)); // set an upper sanity limit to avoid overflow
+		return (((age < (ZT_PATH_HEARTBEAT_PERIOD + 5000)) ? l : (l + 0xffff + age)) * (int)((ZT_INETADDRESS_MAX_SCOPE - _ipScope) + 1));
+	}
 
 	/**
 	 * @return True if this path needs a heartbeat
@@ -300,6 +325,7 @@ private:
 	volatile signed int _incomingLinkQualitySlowLogCounter;
 	volatile unsigned int _incomingLinkQualityPreviousPacketCounter;
 	volatile unsigned int _outgoingPacketCounter;
+	volatile unsigned int _latency;
 	InetAddress _addr;
 	InetAddress::IpScope _ipScope; // memoize this since it's a computed value checked often
 	volatile uint8_t _incomingLinkQualitySlowLog[32];

node/Peer.cpp

@@ -52,12 +52,12 @@ Peer::Peer(const RuntimeEnvironment *renv,const Identity &myIdentity,const Ident
 	_lastComRequestSent(0),
 	_lastCredentialsReceived(0),
 	_lastTrustEstablishedPacketReceived(0),
+	_lastSentFullHello(0),
 	_vProto(0),
 	_vMajor(0),
 	_vMinor(0),
 	_vRevision(0),
 	_id(peerIdentity),
-	_latency(0),
 	_directPathPushCutoffCount(0),
 	_credentialsCutoffCount(0)
 {
@@ -148,59 +148,47 @@ void Peer::received(
 
 	if (hops == 0) {
 		// If this is a direct packet (no hops), update existing paths or learn new ones
-		bool pathAlreadyKnown = false;
-
-		{
-			Mutex::Lock _l(_paths_m);
-			if ((path->address().ss_family == AF_INET)&&(_v4Path.p)) {
-				const struct sockaddr_in *const r = reinterpret_cast<const struct sockaddr_in *>(&(path->address()));
-				const struct sockaddr_in *const l = reinterpret_cast<const struct sockaddr_in *>(&(_v4Path.p->address()));
-				if ((r->sin_addr.s_addr == l->sin_addr.s_addr)&&(r->sin_port == l->sin_port)&&(path->localSocket() == _v4Path.p->localSocket())) {
-					_v4Path.lr = now;
-					pathAlreadyKnown = true;
-				}
-			} else if ((path->address().ss_family == AF_INET6)&&(_v6Path.p)) {
-				const struct sockaddr_in6 *const r = reinterpret_cast<const struct sockaddr_in6 *>(&(path->address()));
-				const struct sockaddr_in6 *const l = reinterpret_cast<const struct sockaddr_in6 *>(&(_v6Path.p->address()));
-				if ((!memcmp(r->sin6_addr.s6_addr,l->sin6_addr.s6_addr,16))&&(r->sin6_port == l->sin6_port)&&(path->localSocket() == _v6Path.p->localSocket())) {
-					_v6Path.lr = now;
-					pathAlreadyKnown = true;
-				}
-			}
-		}
-
-		if ( (!pathAlreadyKnown) && (RR->node->shouldUsePathForZeroTierTraffic(tPtr,_id.address(),path->localSocket(),path->address())) ) {
 		Mutex::Lock _l(_paths_m);
 
-			_PeerPath *replacablePath = (_PeerPath *)0;
+		unsigned int worstQualityPath = 0;
-			if (path->address().ss_family == AF_INET) {
+		int worstQuality = 0;
-				if ( ( (!_v4Path.p) || (!_v4Path.p->alive(now)) || (path->preferenceRank() >= _v4Path.p->preferenceRank()) ) && ( (now - _v4Path.sticky) > ZT_PEER_PATH_EXPIRATION ) ) {
+		bool havePath = false;
-					replacablePath = &_v4Path;
+		for(unsigned int p=0;p<ZT_PEER_MAX_PATHS;++p) {
+			if (_paths[p].p) {
+				if (_paths[p].p == path) {
+					_paths[p].lr = now;
+					havePath = true;
+					break;
 				}
-			} else if (path->address().ss_family == AF_INET6) {
+				const int q = _paths[p].p->quality(now) / _paths[p].priority;
-				if ( ( (!_v6Path.p) || (!_v6Path.p->alive(now)) || (path->preferenceRank() >= _v6Path.p->preferenceRank()) ) && ( (now - _v6Path.sticky) > ZT_PEER_PATH_EXPIRATION ) ) {
+				if (q >= worstQuality) {
-					replacablePath = &_v6Path;
+					worstQuality = q;
+					worstQualityPath = p;
 				}
-			}
-
-			if (replacablePath) {
-				if (verb == Packet::VERB_OK) {
-					RR->t->peerLearnedNewPath(tPtr,networkId,*this,replacablePath->p,path,packetId);
-					replacablePath->lr = now;
-					replacablePath->p = path;
 			} else {
-					RR->t->peerConfirmingUnknownPath(tPtr,networkId,*this,path,packetId,verb);
+				worstQualityPath = p;
+				break;
+			}
+		}
+
+		if ((!havePath)&&(RR->node->shouldUsePathForZeroTierTraffic(tPtr,_id.address(),path->localSocket(),path->address()))) {
+			if (verb == Packet::VERB_OK) {
+				RR->t->peerLearnedNewPath(tPtr,networkId,*this,_paths[worstQualityPath].p,path,packetId);
+				_paths[worstQualityPath].lr = now;
+				_paths[worstQualityPath].p = path;
+				_paths[worstQualityPath].priority = 1;
+			} else {
 				attemptToContactAt(tPtr,path->localSocket(),path->address(),now,true,path->nextOutgoingCounter());
 				path->sent(now);
-				}
+				RR->t->peerConfirmingUnknownPath(tPtr,networkId,*this,path,packetId,verb);
 			}
 		}
 	}
 
-	// If we are being relayed or if we're using a global address, send PUSH_DIRECT_PATHS.
+	// If we have a trust relationship periodically push a message enumerating
-	// In the global address case we push only configured direct paths to accomplish
+	// all known external addresses for ourselves. We now do this even if we
-	// fall-forward to local backplane networks over e.g. LAN or Amazon VPC.
+	// have a current path since we'll want to use new ones too.
-	if ( ((hops > 0)||(path->ipScope() == InetAddress::IP_SCOPE_GLOBAL)) && (this->trustEstablished(now)) ) {
+	if (this->trustEstablished(now)) {
 		if ((now - _lastDirectPathPushSent) >= ZT_DIRECT_PATH_PUSH_INTERVAL) {
 			_lastDirectPathPushSent = now;
 
@@ -210,6 +198,7 @@ void Peer::received(
 			for(std::vector<InetAddress>::const_iterator i(dps.begin());i!=dps.end();++i)
 				pathsToPush.push_back(*i);
 
+			// Do symmetric NAT prediction if we are communicating indirectly.
 			if (hops > 0) {
 				std::vector<InetAddress> sym(RR->sa->getSymmetricNatPredictions());
 				for(unsigned long i=0,added=0;i<sym.size();++i) {
@@ -264,52 +253,148 @@ void Peer::received(
 	}
 }
 
-bool Peer::sendDirect(void *tPtr,const void *data,unsigned int len,int64_t now,bool force)
+SharedPtr<Path> Peer::getBestPath(int64_t now,bool includeExpired) const
 {
 	Mutex::Lock _l(_paths_m);
 
-	int64_t v6lr = 0;
+	unsigned int bestPath = ZT_PEER_MAX_PATHS;
-	if ( ((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION) && (_v6Path.p) )
+	int bestPathQuality = 2147483647; // INT_MAX
-		v6lr = _v6Path.p->lastIn();
+	for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-	int64_t v4lr = 0;
+		if (_paths[i].p) {
-	if ( ((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION) && (_v4Path.p) )
+			if ((includeExpired)||((now - _paths[i].lr) < ZT_PEER_PATH_EXPIRATION)) {
-		v4lr = _v4Path.p->lastIn();
+				const int q = _paths[i].p->quality(now) / _paths[i].priority;
-
+				if (q < bestPathQuality) {
-	if ( (v6lr > v4lr) && ((now - v6lr) < ZT_PATH_ALIVE_TIMEOUT) ) {
+					bestPathQuality = q;
-		return _v6Path.p->send(RR,tPtr,data,len,now);
+					bestPath = i;
-	} else if ((now - v4lr) < ZT_PATH_ALIVE_TIMEOUT) {
-		return _v4Path.p->send(RR,tPtr,data,len,now);
-	} else if (force) {
-		if (v6lr > v4lr) {
-			return _v6Path.p->send(RR,tPtr,data,len,now);
-		} else if (v4lr) {
-			return _v4Path.p->send(RR,tPtr,data,len,now);
 				}
 			}
+		} else break;
+	}
 
-	return false;
+	if (bestPath != ZT_PEER_MAX_PATHS)
+		return _paths[bestPath].p;
+	return SharedPtr<Path>();
 }
 
-SharedPtr<Path> Peer::getBestPath(int64_t now,bool includeExpired)
+void Peer::introduce(void *const tPtr,const int64_t now,const SharedPtr<Peer> &other) const
 {
-	Mutex::Lock _l(_paths_m);
+	unsigned int myBestV4ByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-
+	unsigned int myBestV6ByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-	int64_t v6lr = 0;
+	int myBestV4QualityByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-	if ((includeExpired || ((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION)) && (_v6Path.p)) {
+	int myBestV6QualityByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-		v6lr = _v6Path.p->lastIn();
+	unsigned int theirBestV4ByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-	}
+	unsigned int theirBestV6ByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-	int64_t v4lr = 0;
+	int theirBestV4QualityByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-	if ((includeExpired || ((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION)) && (_v4Path.p)) {
+	int theirBestV6QualityByScope[ZT_INETADDRESS_MAX_SCOPE+1];
-		v4lr = _v4Path.p->lastIn();
+	for(int i=0;i<=ZT_INETADDRESS_MAX_SCOPE;++i) {
+		myBestV4ByScope[i] = ZT_PEER_MAX_PATHS;
+		myBestV6ByScope[i] = ZT_PEER_MAX_PATHS;
+		myBestV4QualityByScope[i] = 2147483647;
+		myBestV6QualityByScope[i] = 2147483647;
+		theirBestV4ByScope[i] = ZT_PEER_MAX_PATHS;
+		theirBestV6ByScope[i] = ZT_PEER_MAX_PATHS;
+		theirBestV4QualityByScope[i] = 2147483647;
+		theirBestV6QualityByScope[i] = 2147483647;
 	}
 
-	if (v6lr > v4lr) {
+	Mutex::Lock _l1(_paths_m);
-		return _v6Path.p;
+
-	} else if (v4lr) {
+	for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-		return _v4Path.p;
+		if (_paths[i].p) {
+			const int q = _paths[i].p->quality(now) / _paths[i].priority;
+			const unsigned int s = (unsigned int)_paths[i].p->ipScope();
+			switch(_paths[i].p->address().ss_family) {
+				case AF_INET:
+					if (q < myBestV4QualityByScope[s]) {
+						myBestV4QualityByScope[s] = q;
+						myBestV4ByScope[s] = i;
+					}
+					break;
+				case AF_INET6:
+					if (q < myBestV6QualityByScope[s]) {
+						myBestV6QualityByScope[s] = q;
+						myBestV6ByScope[s] = i;
+					}
+					break;
+			}
+		} else break;
 	}
 
-	return SharedPtr<Path>();
+	Mutex::Lock _l2(other->_paths_m);
+
+	for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
+		if (other->_paths[i].p) {
+			const int q = other->_paths[i].p->quality(now) / other->_paths[i].priority;
+			const unsigned int s = (unsigned int)other->_paths[i].p->ipScope();
+			switch(other->_paths[i].p->address().ss_family) {
+				case AF_INET:
+					if (q < theirBestV4QualityByScope[s]) {
+						theirBestV4QualityByScope[s] = q;
+						theirBestV4ByScope[s] = i;
+					}
+					break;
+				case AF_INET6:
+					if (q < theirBestV6QualityByScope[s]) {
+						theirBestV6QualityByScope[s] = q;
+						theirBestV6ByScope[s] = i;
+					}
+					break;
+			}
+		} else break;
+	}
+
+	unsigned int mine = ZT_PEER_MAX_PATHS;
+	unsigned int theirs = ZT_PEER_MAX_PATHS;
+
+	for(int s=ZT_INETADDRESS_MAX_SCOPE;s>=0;--s) {
+		if ((myBestV6ByScope[s] != ZT_PEER_MAX_PATHS)&&(theirBestV6ByScope[s] != ZT_PEER_MAX_PATHS)) {
+			mine = myBestV6ByScope[s];
+			theirs = theirBestV6ByScope[s];
+			break;
+		}
+		if ((myBestV4ByScope[s] != ZT_PEER_MAX_PATHS)&&(theirBestV4ByScope[s] != ZT_PEER_MAX_PATHS)) {
+			mine = myBestV4ByScope[s];
+			theirs = theirBestV4ByScope[s];
+			break;
+		}
+	}
+
+	if (mine != ZT_PEER_MAX_PATHS) {
+		unsigned int alt = (unsigned int)RR->node->prng() & 1; // randomize which hint we send first for black magickal NAT-t reasons
+		const unsigned int completed = alt + 2;
+		while (alt != completed) {
+			if ((alt & 1) == 0) {
+				Packet outp(_id.address(),RR->identity.address(),Packet::VERB_RENDEZVOUS);
+				outp.append((uint8_t)0);
+				other->_id.address().appendTo(outp);
+				outp.append((uint16_t)other->_paths[theirs].p->address().port());
+				if (other->_paths[theirs].p->address().ss_family == AF_INET6) {
+					outp.append((uint8_t)16);
+					outp.append(other->_paths[theirs].p->address().rawIpData(),16);
+				} else {
+					outp.append((uint8_t)4);
+					outp.append(other->_paths[theirs].p->address().rawIpData(),4);
+				}
+				outp.armor(_key,true,_paths[mine].p->nextOutgoingCounter());
+				_paths[mine].p->send(RR,tPtr,outp.data(),outp.size(),now);
+			} else {
+				Packet outp(other->_id.address(),RR->identity.address(),Packet::VERB_RENDEZVOUS);
+				outp.append((uint8_t)0);
+				_id.address().appendTo(outp);
+				outp.append((uint16_t)_paths[mine].p->address().port());
+				if (_paths[mine].p->address().ss_family == AF_INET6) {
+					outp.append((uint8_t)16);
+					outp.append(_paths[mine].p->address().rawIpData(),16);
+				} else {
+					outp.append((uint8_t)4);
+					outp.append(_paths[mine].p->address().rawIpData(),4);
+				}
+				outp.armor(other->_key,true,other->_paths[theirs].p->nextOutgoingCounter());
+				other->_paths[theirs].p->send(RR,tPtr,outp.data(),outp.size(),now);
+			}
+			++alt;
+		}
+	}
 }
 
 void Peer::sendHELLO(void *tPtr,const int64_t localSocket,const InetAddress &atAddress,int64_t now,unsigned int counter)
@@ -377,76 +462,83 @@ void Peer::tryMemorizedPath(void *tPtr,int64_t now)
 	}
 }
 
-bool Peer::doPingAndKeepalive(void *tPtr,int64_t now,int inetAddressFamily)
+unsigned int Peer::doPingAndKeepalive(void *tPtr,int64_t now)
 {
+	unsigned int sent = 0;
+
 	Mutex::Lock _l(_paths_m);
 
-	if (inetAddressFamily < 0) {
+	const bool sendFullHello = ((now - _lastSentFullHello) >= ZT_PEER_PING_PERIOD);
-		int64_t v6lr = 0;
+	_lastSentFullHello = now;
-		if ( ((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION) && (_v6Path.p) )
-			v6lr = _v6Path.p->lastIn();
-		int64_t v4lr = 0;
-		if ( ((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION) && (_v4Path.p) )
-			v4lr = _v4Path.p->lastIn();
 
-		if (v6lr > v4lr) {
+	unsigned int j = 0;
-			if ( ((now - _v6Path.lr) >= ZT_PEER_PING_PERIOD) || (_v6Path.p->needsHeartbeat(now)) ) {
+	for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-				attemptToContactAt(tPtr,_v6Path.p->localSocket(),_v6Path.p->address(),now,false,_v6Path.p->nextOutgoingCounter());
+		if (!_paths[i].p) break;
-				_v6Path.p->sent(now);
+		if ((now - _paths[i].lr) < ZT_PEER_PATH_EXPIRATION) {
-				return true;
+			if ((sendFullHello)||(_paths[i].p->needsHeartbeat(now))) {
+				attemptToContactAt(tPtr,_paths[i].p->localSocket(),_paths[i].p->address(),now,sendFullHello,_paths[i].p->nextOutgoingCounter());
+				_paths[i].p->sent(now);
+				sent |= (_paths[i].p->address().ss_family == AF_INET) ? 0x1 : 0x2;
 			}
-		} else if (v4lr) {
+			if (i != j)
-			if ( ((now - _v4Path.lr) >= ZT_PEER_PING_PERIOD) || (_v4Path.p->needsHeartbeat(now)) ) {
+				_paths[j] = _paths[i];
-				attemptToContactAt(tPtr,_v4Path.p->localSocket(),_v4Path.p->address(),now,false,_v4Path.p->nextOutgoingCounter());
+			++j;
-				_v4Path.p->sent(now);
-				return true;
-			}
-		}
-	} else {
-		if ( (inetAddressFamily == AF_INET) && ((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION) ) {
-			if ( ((now - _v4Path.lr) >= ZT_PEER_PING_PERIOD) || (_v4Path.p->needsHeartbeat(now)) ) {
-				attemptToContactAt(tPtr,_v4Path.p->localSocket(),_v4Path.p->address(),now,false,_v4Path.p->nextOutgoingCounter());
-				_v4Path.p->sent(now);
-				return true;
-			}
-		} else if ( (inetAddressFamily == AF_INET6) && ((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION) ) {
-			if ( ((now - _v6Path.lr) >= ZT_PEER_PING_PERIOD) || (_v6Path.p->needsHeartbeat(now)) ) {
-				attemptToContactAt(tPtr,_v6Path.p->localSocket(),_v6Path.p->address(),now,false,_v6Path.p->nextOutgoingCounter());
-				_v6Path.p->sent(now);
-				return true;
 		}
 	}
+	while(j < ZT_PEER_MAX_PATHS) {
+		_paths[j].lr = 0;
+		_paths[j].p.zero();
+		_paths[j].priority = 1;
+		++j;
 	}
 
-	return false;
+	return sent;
 }
 
-void Peer::redirect(void *tPtr,const int64_t localSocket,const InetAddress &remoteAddress,const int64_t now)
+void Peer::clusterRedirect(void *tPtr,const int64_t localSocket,const InetAddress &remoteAddress,const int64_t now)
 {
-	if ((remoteAddress.ss_family != AF_INET)&&(remoteAddress.ss_family != AF_INET6)) // sanity check
-		return;
-
-	SharedPtr<Path> op;
 	SharedPtr<Path> np(RR->topology->getPath(localSocket,remoteAddress));
-	np->received(now);
+	RR->t->peerRedirected(tPtr,0,*this,np);
 	attemptToContactAt(tPtr,localSocket,remoteAddress,now,true,np->nextOutgoingCounter());
-
 	{
 		Mutex::Lock _l(_paths_m);
-		if (remoteAddress.ss_family == AF_INET) {
+		int worstQuality = 0;
-			op = _v4Path.p;
+		unsigned int worstQualityPath = 0;
-			_v4Path.lr = now;
+		for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-			_v4Path.sticky = now;
+			if (_paths[i].p) {
-			_v4Path.p = np;
+				if (_paths[i].p == np) { // <-- where's my Fields Medal?
-		} else if (remoteAddress.ss_family == AF_INET6) {
+					_paths[i].lr = now; // consider this a "receive"
-			op = _v6Path.p;
+					_paths[i].priority += 5; // kind of arbitrary, bumps way up in best path quality order
-			_v6Path.lr = now;
+					return;
-			_v6Path.sticky = now;
+				}
-			_v6Path.p = np;
+				const int q = _paths[i].p->quality(now) / _paths[i].priority;
+				if (q >= worstQuality) {
+					worstQuality = q;
+					worstQualityPath = i;
+				}
+			} else {
+				worstQualityPath = i;
+				break;
 			}
 		}
+		_paths[worstQualityPath].lr = now;
+		_paths[worstQualityPath].p = np;
+		_paths[worstQualityPath].priority = 6; // 1 + 5
+	}
+}
 
-	RR->t->peerRedirected(tPtr,0,*this,op,np);
+void Peer::resetWithinScope(void *tPtr,InetAddress::IpScope scope,int inetAddressFamily,int64_t now)
+{
+	Mutex::Lock _l(_paths_m);
+	for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
+		if (_paths[i].p) {
+			if ((_paths[i].p->address().ss_family == inetAddressFamily)&&(_paths[i].p->ipScope() == scope)) {
+				attemptToContactAt(tPtr,_paths[i].p->localSocket(),_paths[i].p->address(),now,false,_paths[i].p->nextOutgoingCounter());
+				_paths[i].p->sent(now);
+				_paths[i].lr = 0; // path will not be used unless it speaks again
+			}
+		} else break;
+	}
 }
 
 } // namespace ZeroTier

node/Peer.hpp

@@ -53,6 +53,15 @@
 
 #define ZT_PEER_MAX_SERIALIZED_STATE_SIZE (sizeof(Peer) + 32 + (sizeof(Path) * 2))
 
+/**
+ * Maximum number of direct paths to a peer
+ *
+ * This can be increased. You'll want about 2X the number of physical links
+ * you are ever likely to want to bundle/trunk since there is likely to be
+ * a path for every protocol (IPv4, IPv6, etc.).
+ */
+#define ZT_PEER_MAX_PATHS 16
+
 namespace ZeroTier {
 
 /**
@@ -116,6 +125,8 @@ public:
 		const uint64_t networkId);
 
 	/**
+	 * Check whether we have an active path to this peer via the given address
+	 *
 	 * @param now Current time
 	 * @param addr Remote address
 	 * @return True if we have an active path to this destination
@@ -123,7 +134,13 @@ public:
 	inline bool hasActivePathTo(int64_t now,const InetAddress &addr) const
 	{
 		Mutex::Lock _l(_paths_m);
-		return ( ((addr.ss_family == AF_INET)&&(_v4Path.p)&&(_v4Path.p->address() == addr)&&(_v4Path.p->alive(now))) || ((addr.ss_family == AF_INET6)&&(_v6Path.p)&&(_v6Path.p->address() == addr)&&(_v6Path.p->alive(now))) );
+		for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
+			if (_paths[i].p) {
+				if (((now - _paths[i].lr) < ZT_PEER_PATH_EXPIRATION)&&(_paths[i].p->address() == addr))
+					return true;
+			} else break;
+		}
+		return false;
 	}
 
 	/**
@@ -136,19 +153,27 @@ public:
 	 * @param force If true, send even if path is not alive
 	 * @return True if we actually sent something
 	 */
-	bool sendDirect(void *tPtr,const void *data,unsigned int len,int64_t now,bool force);
+	inline bool sendDirect(void *tPtr,const void *data,unsigned int len,int64_t now,bool force)
+	{
+		SharedPtr<Path> bp(getBestPath(now,force));
+		if (bp)
+			return bp->send(RR,tPtr,data,len,now);
+		return false;
+	}
 
 	/**
 	 * Get the best current direct path
 	 *
-	 * This does not check Path::alive(), but does return the most recently
-	 * active path and does check expiration (which is a longer timeout).
-	 *
 	 * @param now Current time
 	 * @param includeExpired If true, include even expired paths
 	 * @return Best current path or NULL if none
 	 */
-	SharedPtr<Path> getBestPath(int64_t now,bool includeExpired);
+	SharedPtr<Path> getBestPath(int64_t now,bool includeExpired) const;
+
+	/**
+	 * Send VERB_RENDEZVOUS to this and another peer via the best common IP scope and path
+	 */
+	void introduce(void *const tPtr,const int64_t now,const SharedPtr<Peer> &other) const;
 
 	/**
 	 * Send a HELLO to this peer at a specified physical address
@@ -190,67 +215,39 @@ public:
 	/**
 	 * Send pings or keepalives depending on configured timeouts
 	 *
+	 * This also cleans up some internal data structures. It's called periodically from Node.
+	 *
 	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
 	 * @param now Current time
 	 * @param inetAddressFamily Keep this address family alive, or -1 for any
-	 * @return True if we have at least one direct path of the given family (or any if family is -1)
+	 * @return 0 if nothing sent or bit mask: bit 0x1 if IPv4 sent, bit 0x2 if IPv6 sent (0x3 means both sent)
 	 */
-	bool doPingAndKeepalive(void *tPtr,int64_t now,int inetAddressFamily);
+	unsigned int doPingAndKeepalive(void *tPtr,int64_t now);
 
 	/**
-	 * Specify remote path for this peer and forget others
+	 * Process a cluster redirect sent by this peer
-	 *
-	 * This overrides normal path learning and tells this peer to be found
-	 * at this address, at least within the address's family. Other address
-	 * families are not modified.
 	 *
 	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
 	 * @param localSocket Local socket as supplied by external code
 	 * @param remoteAddress Remote address
 	 * @param now Current time
 	 */
-	void redirect(void *tPtr,const int64_t localSocket,const InetAddress &remoteAddress,const int64_t now);
+	void clusterRedirect(void *tPtr,const int64_t localSocket,const InetAddress &remoteAddress,const int64_t now);
 
 	/**
 	 * Reset paths within a given IP scope and address family
 	 *
 	 * Resetting a path involves sending an ECHO to it and then deactivating
-	 * it until or unless it responds.
+	 * it until or unless it responds. This is done when we detect a change
+	 * to our external IP or another system change that might invalidate
+	 * many or all current paths.
 	 *
 	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
 	 * @param scope IP scope
 	 * @param inetAddressFamily Family e.g. AF_INET
 	 * @param now Current time
 	 */
-	inline void resetWithinScope(void *tPtr,InetAddress::IpScope scope,int inetAddressFamily,int64_t now)
+	void resetWithinScope(void *tPtr,InetAddress::IpScope scope,int inetAddressFamily,int64_t now);
-	{
-		Mutex::Lock _l(_paths_m);
-		if ((inetAddressFamily == AF_INET)&&(_v4Path.lr)&&(_v4Path.p->address().ipScope() == scope)) {
-			attemptToContactAt(tPtr,_v4Path.p->localSocket(),_v4Path.p->address(),now,false,_v4Path.p->nextOutgoingCounter());
-			_v4Path.p->sent(now);
-			_v4Path.lr = 0; // path will not be used unless it speaks again
-		} else if ((inetAddressFamily == AF_INET6)&&(_v6Path.lr)&&(_v6Path.p->address().ipScope() == scope)) {
-			attemptToContactAt(tPtr,_v6Path.p->localSocket(),_v6Path.p->address(),now,false,_v6Path.p->nextOutgoingCounter());
-			_v6Path.p->sent(now);
-			_v6Path.lr = 0; // path will not be used unless it speaks again
-		}
-	}
-
-	/**
-	 * Fill parameters with V4 and V6 addresses if known and alive
-	 *
-	 * @param now Current time
-	 * @param v4 Result parameter to receive active IPv4 address, if any
-	 * @param v6 Result parameter to receive active IPv6 address, if any
-	 */
-	inline void getRendezvousAddresses(int64_t now,InetAddress &v4,InetAddress &v6) const
-	{
-		Mutex::Lock _l(_paths_m);
-		if (((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION)&&(_v4Path.p->alive(now)))
-			v4 = _v4Path.p->address();
-		if (((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION)&&(_v6Path.p->alive(now)))
-			v6 = _v6Path.p->address();
-	}
 
 	/**
 	 * @param now Current time
@@ -260,10 +257,10 @@ public:
 	{
 		std::vector< SharedPtr<Path> > pp;
 		Mutex::Lock _l(_paths_m);
-		if (((now - _v4Path.lr) < ZT_PEER_PATH_EXPIRATION)&&(_v4Path.p->alive(now)))
+		for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-			pp.push_back(_v4Path.p);
+			if (!_paths[i].p) break;
-		if (((now - _v6Path.lr) < ZT_PEER_PATH_EXPIRATION)&&(_v6Path.p->alive(now)))
+			pp.push_back(_paths[i].p);
-			pp.push_back(_v6Path.p);
+		}
 		return pp;
 	}
 
@@ -283,9 +280,13 @@ public:
 	inline int64_t isActive(int64_t now) const { return ((now - _lastNontrivialReceive) < ZT_PEER_ACTIVITY_TIMEOUT); }
 
 	/**
-	 * @return Latency in milliseconds or 0 if unknown
+	 * @return Latency in milliseconds of best path or 0xffff if unknown / no paths
 	 */
-	inline unsigned int latency() const { return _latency; }
+	inline unsigned int latency(const int64_t now) const
+	{
+		SharedPtr<Path> bp(getBestPath(now,false));
+		return ((bp) ? bp->latency() : 0xffff);
+	}
 
 	/**
 	 * This computes a quality score for relays and root servers
@@ -303,25 +304,12 @@ public:
 		const uint64_t tsr = now - _lastReceive;
 		if (tsr >= ZT_PEER_ACTIVITY_TIMEOUT)
 			return (~(unsigned int)0);
-		unsigned int l = _latency;
+		unsigned int l = latency(now);
 		if (!l)
 			l = 0xffff;
 		return (l * (((unsigned int)tsr / (ZT_PEER_PING_PERIOD + 1000)) + 1));
 	}
 
-	/**
-	 * Update latency with a new direct measurment
-	 *
-	 * @param l Direct latency measurment in ms
-	 */
-	inline void addDirectLatencyMeasurment(unsigned int l)
-	{
-		unsigned int ol = _latency;
-		if ((ol > 0)&&(ol < 10000))
-			_latency = (ol + std::min(l,(unsigned int)65535)) / 2;
-		else _latency = std::min(l,(unsigned int)65535);
-	}
-
 	/**
 	 * @return 256-bit secret symmetric encryption key
 	 */
@@ -442,29 +430,15 @@ public:
 	/**
 	 * Serialize a peer for storage in local cache
 	 *
-	 * This does not serialize everything, just identity and addresses where the peer
+	 * This does not serialize everything, just non-ephemeral information.
-	 * may be reached.
 	 */
 	template<unsigned int C>
-	inline void serialize(Buffer<C> &b) const
+	inline void serializeForCache(Buffer<C> &b) const
 	{
-		b.append((uint8_t)0);
+		b.append((uint8_t)1);
 
 		_id.serialize(b);
 
-		b.append(_lastReceive);
-		b.append(_lastNontrivialReceive);
-		b.append(_lastTriedMemorizedPath);
-		b.append(_lastDirectPathPushSent);
-		b.append(_lastDirectPathPushReceive);
-		b.append(_lastCredentialRequestSent);
-		b.append(_lastWhoisRequestReceived);
-		b.append(_lastEchoRequestReceived);
-		b.append(_lastComRequestReceived);
-		b.append(_lastComRequestSent);
-		b.append(_lastCredentialsReceived);
-		b.append(_lastTrustEstablishedPacketReceived);
-
 		b.append((uint16_t)_vProto);
 		b.append((uint16_t)_vMajor);
 		b.append((uint16_t)_vMinor);
@@ -472,15 +446,16 @@ public:
 
 		{
 			Mutex::Lock _l(_paths_m);
-			unsigned int pcount = 0;
+			unsigned int pc = 0;
-			if (_v4Path.p) ++pcount;
+			for(unsigned int i=0;i<ZT_PEER_MAX_PATHS;++i) {
-			if (_v6Path.p) ++pcount;
+				if (_paths[i].p)
-			b.append((uint8_t)pcount);
+					++pc;
-			if (_v4Path.p) _v4Path.p->address().serialize(b);
+				else break;
-			if (_v6Path.p) _v6Path.p->address().serialize(b);
+			}
+			b.append((uint16_t)pc);
+			for(unsigned int i=0;i<pc;++i)
+				_paths[i].p->address().serialize(b);
 		}
-
-		b.append((uint16_t)0);
 	}
 
 	template<unsigned int C>
@@ -488,7 +463,7 @@ public:
 	{
 		try {
 			unsigned int ptr = 0;
-			if (b[ptr++] != 0)
+			if (b[ptr++] != 1)
 				return SharedPtr<Peer>();
 
 			Identity id;
@@ -498,15 +473,16 @@ public:
 
 			SharedPtr<Peer> p(new Peer(renv,renv->identity,id));
 
-			ptr += 12 * 8; // skip deserializing ephemeral state in this case
-
 			p->_vProto = b.template at<uint16_t>(ptr); ptr += 2;
 			p->_vMajor = b.template at<uint16_t>(ptr); ptr += 2;
 			p->_vMinor = b.template at<uint16_t>(ptr); ptr += 2;
 			p->_vRevision = b.template at<uint16_t>(ptr); ptr += 2;
 
-			const unsigned int pcount = (unsigned int)b[ptr++];
+			// When we deserialize from the cache we don't actually restore paths. We
-			for(unsigned int i=0;i<pcount;++i) {
+			// just try them and then re-learn them if they happen to still be up.
+			// Paths are fairly ephemeral in the real world in most cases.
+			const unsigned int tryPathCount = b.template at<uint16_t>(ptr); ptr += 2;
+			for(unsigned int i=0;i<tryPathCount;++i) {
 				InetAddress inaddr;
 				try {
 					ptr += inaddr.deserialize(b,ptr);
@@ -526,10 +502,10 @@ public:
 private:
 	struct _PeerPath
 	{
-		_PeerPath() : lr(0),sticky(0),p() {}
+		_PeerPath() : lr(0),p(),priority(1) {}
 		int64_t lr; // time of last valid ZeroTier packet
-		int64_t sticky; // time last set as sticky
 		SharedPtr<Path> p;
+		int priority; // >= 1, higher is better
 	};
 
 	uint8_t _key[ZT_PEER_SECRET_KEY_LENGTH];
@@ -548,19 +524,18 @@ private:
 	int64_t _lastComRequestSent;
 	int64_t _lastCredentialsReceived;
 	int64_t _lastTrustEstablishedPacketReceived;
+	int64_t _lastSentFullHello;
 
 	uint16_t _vProto;
 	uint16_t _vMajor;
 	uint16_t _vMinor;
 	uint16_t _vRevision;
 
-	_PeerPath _v4Path; // IPv4 direct path
+	_PeerPath _paths[ZT_PEER_MAX_PATHS];
-	_PeerPath _v6Path; // IPv6 direct path
 	Mutex _paths_m;
 
 	Identity _id;
 
-	unsigned int _latency;
 	unsigned int _directPathPushCutoffCount;
 	unsigned int _credentialsCutoffCount;
 

node/Switch.cpp

@@ -169,68 +169,22 @@ void Switch::onRemotePacket(void *tPtr,const int64_t localSocket,const InetAddre
 
 					if (packet.hops() < ZT_RELAY_MAX_HOPS) {
 						packet.incrementHops();
-
 						SharedPtr<Peer> relayTo = RR->topology->getPeer(tPtr,destination);
 						if ((relayTo)&&(relayTo->sendDirect(tPtr,packet.data(),packet.size(),now,false))) {
-							if ((source != RR->identity.address())&&(_shouldUnite(now,source,destination))) { // don't send RENDEZVOUS for cluster frontplane relays
+							if ((source != RR->identity.address())&&(_shouldUnite(now,source,destination))) {
-								const InetAddress *hintToSource = (InetAddress *)0;
-								const InetAddress *hintToDest = (InetAddress *)0;
-
-								InetAddress destV4,destV6;
-								InetAddress sourceV4,sourceV6;
-								relayTo->getRendezvousAddresses(now,destV4,destV6);
-
 								const SharedPtr<Peer> sourcePeer(RR->topology->getPeer(tPtr,source));
-								if (sourcePeer) {
+								if (sourcePeer)
-									sourcePeer->getRendezvousAddresses(now,sourceV4,sourceV6);
+									relayTo->introduce(tPtr,now,sourcePeer);
-									if ((destV6)&&(sourceV6)) {
-										hintToSource = &destV6;
-										hintToDest = &sourceV6;
-									} else if ((destV4)&&(sourceV4)) {
-										hintToSource = &destV4;
-										hintToDest = &sourceV4;
-									}
-
-									if ((hintToSource)&&(hintToDest)) {
-										unsigned int alt = (unsigned int)RR->node->prng() & 1; // randomize which hint we send first for obscure NAT-t reasons
-										const unsigned int completed = alt + 2;
-										while (alt != completed) {
-											if ((alt & 1) == 0) {
-												Packet outp(source,RR->identity.address(),Packet::VERB_RENDEZVOUS);
-												outp.append((uint8_t)0);
-												destination.appendTo(outp);
-												outp.append((uint16_t)hintToSource->port());
-												if (hintToSource->ss_family == AF_INET6) {
-													outp.append((uint8_t)16);
-													outp.append(hintToSource->rawIpData(),16);
-												} else {
-													outp.append((uint8_t)4);
-													outp.append(hintToSource->rawIpData(),4);
-												}
-												send(tPtr,outp,true);
-											} else {
-												Packet outp(destination,RR->identity.address(),Packet::VERB_RENDEZVOUS);
-												outp.append((uint8_t)0);
-												source.appendTo(outp);
-												outp.append((uint16_t)hintToDest->port());
-												if (hintToDest->ss_family == AF_INET6) {
-													outp.append((uint8_t)16);
-													outp.append(hintToDest->rawIpData(),16);
-												} else {
-													outp.append((uint8_t)4);
-													outp.append(hintToDest->rawIpData(),4);
-												}
-												send(tPtr,outp,true);
-											}
-											++alt;
-										}
-									}
-								}
 							}
 						} else {
 							relayTo = RR->topology->getUpstreamPeer();
-							if ((relayTo)&&(relayTo->address() != source))
+							if ((relayTo)&&(relayTo->address() != source)) {
-								relayTo->sendDirect(tPtr,packet.data(),packet.size(),now,true);
+								if (relayTo->sendDirect(tPtr,packet.data(),packet.size(),now,true)) {
+									const SharedPtr<Peer> sourcePeer(RR->topology->getPeer(tPtr,source));
+									if (sourcePeer)
+										relayTo->introduce(tPtr,now,sourcePeer);
+								}
+							}
 						}
 					}
 				} else if ((reinterpret_cast<const uint8_t *>(data)[ZT_PACKET_IDX_FLAGS] & ZT_PROTO_FLAG_FRAGMENTED) != 0) {
@@ -694,22 +648,7 @@ bool Switch::_trySend(void *tPtr,Packet &packet,bool encrypt)
 
 	const SharedPtr<Peer> peer(RR->topology->getPeer(tPtr,destination));
 	if (peer) {
-		/* First get the best path, and if it's dead (and this is not a root)
-		 * we attempt to re-activate that path but this packet will flow
-		 * upstream. If the path comes back alive, it will be used in the future.
-		 * For roots we don't do the alive check since roots are not required
-		 * to send heartbeats "down" and because we have to at least try to
-		 * go somewhere. */
-
 		viaPath = peer->getBestPath(now,false);
-		if ( (viaPath) && (!viaPath->alive(now)) && (!RR->topology->isUpstream(peer->identity())) ) {
-			if ((now - viaPath->lastOut()) > std::max((now - viaPath->lastIn()) * 4,(int64_t)ZT_PATH_MIN_REACTIVATE_INTERVAL)) {
-				peer->attemptToContactAt(tPtr,viaPath->localSocket(),viaPath->address(),now,false,viaPath->nextOutgoingCounter());
-				viaPath->sent(now);
-			}
-			viaPath.zero();
-		}
-
 		if (!viaPath) {
 			peer->tryMemorizedPath(tPtr,now); // periodically attempt memorized or statically defined paths, if any are known
 			const SharedPtr<Peer> relay(RR->topology->getUpstreamPeer());

node/Topology.cpp

@@ -431,7 +431,7 @@ void Topology::_savePeer(void *tPtr,const SharedPtr<Peer> &peer)
 {
 	try {
 		Buffer<ZT_PEER_MAX_SERIALIZED_STATE_SIZE> buf;
-		peer->serialize(buf);
+		peer->serializeForCache(buf);
 		uint64_t tmpid[2]; tmpid[0] = peer->address().toInt(); tmpid[1] = 0;
 		RR->node->stateObjectPut(tPtr,ZT_STATE_OBJECT_PEER,tmpid,buf.data(),buf.size());
 	} catch ( ... ) {} // sanity check, discard invalid entries

node/Topology.hpp

@@ -300,7 +300,7 @@ public:
 		SharedPtr<Peer> *p = (SharedPtr<Peer> *)0;
 		while (i.next(a,p)) {
 			const SharedPtr<Path> pp((*p)->getBestPath(now,false));
-			if ((pp)&&(pp->alive(now)))
+			if (pp)
 				++cnt;
 		}
 		return cnt;

node/Trace.cpp

@@ -92,16 +92,13 @@ void Trace::peerLearnedNewPath(void *const tPtr,const uint64_t networkId,Peer &p
 	_send(tPtr,d,networkId);
 }
 
-void Trace::peerRedirected(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &oldPath,const SharedPtr<Path> &newPath)
+void Trace::peerRedirected(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &newPath)
 {
 	char tmp[128];
 	Dictionary<ZT_MAX_REMOTE_TRACE_SIZE> d;
 	d.add(ZT_REMOTE_TRACE_FIELD__EVENT,ZT_REMOTE_TRACE_EVENT__PEER_REDIRECTED_S);
 	d.add(ZT_REMOTE_TRACE_FIELD__NETWORK_ID,networkId);
 	d.add(ZT_REMOTE_TRACE_FIELD__REMOTE_ZTADDR,peer.address());
-	if (oldPath) {
-		d.add(ZT_REMOTE_TRACE_FIELD__OLD_REMOTE_PHYADDR,oldPath->address().toString(tmp));
-	}
 	if (newPath) {
 		d.add(ZT_REMOTE_TRACE_FIELD__REMOTE_PHYADDR,newPath->address().toString(tmp));
 		d.add(ZT_REMOTE_TRACE_FIELD__LOCAL_SOCKET,newPath->localSocket());

node/Trace.hpp

@@ -105,7 +105,7 @@ public:
 
 	void peerConfirmingUnknownPath(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &path,const uint64_t packetId,const Packet::Verb verb);
 	void peerLearnedNewPath(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &oldPath,const SharedPtr<Path> &newPath,const uint64_t packetId);
-	void peerRedirected(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &oldPath,const SharedPtr<Path> &newPath);
+	void peerRedirected(void *const tPtr,const uint64_t networkId,Peer &peer,const SharedPtr<Path> &newPath);
 
 	void incomingPacketMessageAuthenticationFailure(void *const tPtr,const SharedPtr<Path> &path,const uint64_t packetId,const Address &source,const unsigned int hops,const char *reason);
 	void incomingPacketInvalid(void *const tPtr,const SharedPtr<Path> &path,const uint64_t packetId,const Address &source,const unsigned int hops,const Packet::Verb verb,const char *reason);