Simplify locking semantics some more to address a deadlock.

4 files changed, 161 insertions, 204 deletions

diff --git a/node/IncomingPacket.cpp b/node/IncomingPacket.cpp
index 4f8f9166..e2ff24e6 100644
--- a/node/IncomingPacket.cpp
+++ b/node/IncomingPacket.cpp
@@ -70,7 +70,7 @@ bool IncomingPacket::tryDecode(const RuntimeEnvironment *RR)
 			switch(verb()) {
 				//case Packet::VERB_NOP:
 				default: // ignore unknown verbs, but if they pass auth check they are "received"
-					peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),verb(),0,Packet::VERB_NOP,Utils::now());
+					peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),verb(),0,Packet::VERB_NOP,Utils::now());
 					return true;
 				case Packet::VERB_HELLO:                          return _doHELLO(RR);
 				case Packet::VERB_ERROR:                          return _doERROR(RR,peer);
@@ -152,7 +152,7 @@ bool IncomingPacket::_doERROR(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 			default: break;
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_ERROR,inRePacketId,inReVerb,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_ERROR,inRePacketId,inReVerb,Utils::now());
 	} catch (std::exception &ex) {
 		TRACE("dropped ERROR from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -214,7 +214,7 @@ bool IncomingPacket::_doHELLO(const RuntimeEnvironment *RR)
 			peer = RR->topology->addPeer(newPeer);
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_HELLO,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_HELLO,0,Packet::VERB_NOP,Utils::now());
 		peer->setRemoteVersion(protoVersion,vMajor,vMinor,vRevision);
 
 		// If a supernode has a version higher than ours, this causes a software
@@ -334,7 +334,7 @@ bool IncomingPacket::_doOK(const RuntimeEnvironment *RR,const SharedPtr<Peer> &p
 			default: break;
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_OK,inRePacketId,inReVerb,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_OK,inRePacketId,inReVerb,Utils::now());
 	} catch (std::exception &ex) {
 		TRACE("dropped OK from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -367,7 +367,7 @@ bool IncomingPacket::_doWHOIS(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 		} else {
 			TRACE("dropped WHOIS from %s(%s): missing or invalid address",source().toString().c_str(),_remoteAddress.toString().c_str());
 		}
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_WHOIS,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_WHOIS,0,Packet::VERB_NOP,Utils::now());
 	} catch ( ... ) {
 		TRACE("dropped WHOIS from %s(%s): unexpected exception",source().toString().c_str(),_remoteAddress.toString().c_str());
 	}
@@ -399,7 +399,7 @@ bool IncomingPacket::_doRENDEZVOUS(const RuntimeEnvironment *RR,const SharedPtr<
 				if ((port > 0)&&((addrlen == 4)||(addrlen == 16))) {
 					InetAddress atAddr(field(ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRESS,addrlen),addrlen,port);
 					TRACE("RENDEZVOUS from %s says %s might be at %s, starting NAT-t",source().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
-					peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_RENDEZVOUS,0,Packet::VERB_NOP,Utils::now());
+					peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_RENDEZVOUS,0,Packet::VERB_NOP,Utils::now());
 					RR->sw->contact(withPeer,atAddr);
 				} else {
 					TRACE("dropped corrupt RENDEZVOUS from %s(%s) (bad address or port)",source().toString().c_str(),_remoteAddress.toString().c_str());
@@ -440,7 +440,7 @@ bool IncomingPacket::_doFRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 				network->tapPut(MAC(peer->address(),network->id()),network->mac(),etherType,field(ZT_PROTO_VERB_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
 			}
 
-			peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_FRAME,0,Packet::VERB_NOP,Utils::now());
+			peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_FRAME,0,Packet::VERB_NOP,Utils::now());
 		} else {
 			TRACE("dropped FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
 		}
@@ -517,7 +517,7 @@ bool IncomingPacket::_doEXT_FRAME(const RuntimeEnvironment *RR,const SharedPtr<P
 					network->tapPut(from,to,etherType,field(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
 			}
 
-			peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_EXT_FRAME,0,Packet::VERB_NOP,Utils::now());
+			peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_EXT_FRAME,0,Packet::VERB_NOP,Utils::now());
 		} else {
 			TRACE("dropped EXT_FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
 		}
@@ -594,7 +594,7 @@ bool IncomingPacket::_doP5_MULTICAST_FRAME(const RuntimeEnvironment *RR,const Sh
 			}
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_P5_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_P5_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());
 
 		if (RR->topology->amSupernode()) {
 			// To support legacy peers, old fashioned "P5" multicasts are propagated manually by supernodes.
@@ -652,7 +652,7 @@ bool IncomingPacket::_doMULTICAST_LIKE(const RuntimeEnvironment *RR,const Shared
 		for(unsigned int ptr=ZT_PACKET_IDX_PAYLOAD;ptr<size();ptr+=18)
 			RR->mc->add(now,at<uint64_t>(ptr),MulticastGroup(MAC(field(ptr + 8,6),6),at<uint32_t>(ptr + 14)),Address(),peer->address());
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_LIKE,0,Packet::VERB_NOP,now);
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_LIKE,0,Packet::VERB_NOP,now);
 	} catch (std::exception &ex) {
 		TRACE("dropped MULTICAST_LIKE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -676,7 +676,7 @@ bool IncomingPacket::_doNETWORK_MEMBERSHIP_CERTIFICATE(const RuntimeEnvironment
 			}
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE,0,Packet::VERB_NOP,Utils::now());
 	} catch (std::exception &ex) {
 		TRACE("dropped NETWORK_MEMBERSHIP_CERTIFICATE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -726,7 +726,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 		}
 #endif // !__WINDOWS__
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REQUEST,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REQUEST,0,Packet::VERB_NOP,Utils::now());
 	} catch (std::exception &exc) {
 		TRACE("dropped NETWORK_CONFIG_REQUEST from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -747,7 +747,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REFRESH(const RuntimeEnvironment *RR,cons
 				nw->requestConfiguration();
 			}
 		}
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REFRESH,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REFRESH,0,Packet::VERB_NOP,Utils::now());
 	} catch (std::exception &exc) {
 		TRACE("dropped NETWORK_CONFIG_REFRESH from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -778,7 +778,7 @@ bool IncomingPacket::_doMULTICAST_GATHER(const RuntimeEnvironment *RR,const Shar
 			}
 		}
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_GATHER,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_GATHER,0,Packet::VERB_NOP,Utils::now());
 	} catch (std::exception &exc) {
 		TRACE("dropped MULTICAST_GATHER from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -870,7 +870,7 @@ bool IncomingPacket::_doMULTICAST_FRAME(const RuntimeEnvironment *RR,const Share
 			}
 		} // else ignore -- not a member of this network
 
-		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());
+		peer->received(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());
 	} catch (std::exception &exc) {
 		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
diff --git a/node/Path.hpp b/node/Path.hpp
index 67dd27fc..afef752b 100644
--- a/node/Path.hpp
+++ b/node/Path.hpp
@@ -37,14 +37,14 @@
 #include "Constants.hpp"
 #include "InetAddress.hpp"
 #include "Utils.hpp"
-#include "Buffer.hpp"
-
-#define ZT_PATH_SERIALIZATION_VERSION 3
 
 namespace ZeroTier {
 
 /**
  * WAN address and protocol for reaching a peer
+ *
+ * This structure is volatile and memcpy-able, and depends on
+ * InetAddress being similarly safe.
  */
 class Path
 {
@@ -67,7 +67,6 @@ public:
 
 	Path(const Path &p)
 	{
-		// InetAddress is memcpy'able
 		memcpy(this,&p,sizeof(Path));
 	}
 
@@ -79,6 +78,16 @@ public:
 		_type(t),
 		_fixed(fixed) {}
 
+	inline void init(const InetAddress &addr,Type t,bool fixed = false)
+	{
+		_lastSend = 0;
+		_lastReceived = 0;
+		_lastPing = 0;
+		_addr = addr;
+		_type = t;
+		_fixed = fixed;
+	}
+
 	inline Path &operator=(const Path &p)
 	{
 		if (this != &p)
@@ -150,59 +159,6 @@ public:
 	inline bool operator<=(const Path &p) const throw() { return !(p < *this); }
 	inline bool operator>=(const Path &p) const throw() { return !(*this < p); }
 
-	template<unsigned int C>
-	inline void serialize(Buffer<C> &b) const
-	{
-		b.append((unsigned char)ZT_PATH_SERIALIZATION_VERSION);
-		b.append(_lastSend);
-		b.append(_lastReceived);
-		b.append(_lastPing);
-		b.append((unsigned char)_addr.type());
-		switch(_addr.type()) {
-			case InetAddress::TYPE_NULL:
-				break;
-			case InetAddress::TYPE_IPV4:
-				b.append(_addr.rawIpData(),4);
-				b.append((uint16_t)_addr.port());
-				break;
-			case InetAddress::TYPE_IPV6:
-				b.append(_addr.rawIpData(),16);
-				b.append((uint16_t)_addr.port());
-				break;
-		}
-		b.append((unsigned char)_type);
-		b.append(_fixed ? (unsigned char)1 : (unsigned char)0);
-	}
-	template<unsigned int C>
-	inline unsigned int deserialize(const Buffer<C> &b,unsigned int startAt = 0)
-	{
-		unsigned int p = startAt;
-
-		if (b[p++] != ZT_PATH_SERIALIZATION_VERSION)
-			throw std::invalid_argument("Path: deserialize(): version mismatch");
-
-		_lastSend = b.template at<uint64_t>(p); p += sizeof(uint64_t);
-		_lastReceived = b.template at<uint64_t>(p); p += sizeof(uint64_t);
-		_lastPing = b.template at<uint64_t>(p); p += sizeof(uint64_t);
-		switch((InetAddress::AddressType)b[p++]) {
-			case InetAddress::TYPE_IPV4:
-				_addr.set(b.field(p,4),4,b.template at<uint16_t>(p + 4));
-				p += 4 + sizeof(uint16_t);
-				break;
-			case InetAddress::TYPE_IPV6:
-				_addr.set(b.field(p,16),16,b.template at<uint16_t>(p + 16));
-				p += 16 + sizeof(uint16_t);
-				break;
-			default:
-				_addr.zero();
-				break;
-		}
-		_type = (Type)b[p++];
-		_fixed = (b[p++] != 0);
-
-		return (p - startAt);
-	}
-
 private:
 	volatile uint64_t _lastSend;
 	volatile uint64_t _lastReceived;
diff --git a/node/Peer.cpp b/node/Peer.cpp
index 540a83a1..209de949 100644
--- a/node/Peer.cpp
+++ b/node/Peer.cpp
@@ -37,20 +37,8 @@
 
 namespace ZeroTier {
 
-Peer::Peer() :
-	_lastUsed(0),
-	_lastReceive(0),
-	_lastUnicastFrame(0),
-	_lastMulticastFrame(0),
-	_lastAnnouncedTo(0),
-	_vMajor(0),
-	_vMinor(0),
-	_vRevision(0),
-	_latency(0) {}
-
 Peer::Peer(const Identity &myIdentity,const Identity &peerIdentity)
 	throw(std::runtime_error) :
-	_id(peerIdentity),
 	_lastUsed(0),
 	_lastReceive(0),
 	_lastUnicastFrame(0),
@@ -59,13 +47,15 @@ Peer::Peer(const Identity &myIdentity,const Identity &peerIdentity)
 	_vMajor(0),
 	_vMinor(0),
 	_vRevision(0),
-	_latency(0)
+	_numPaths(0),
+	_latency(0),
+	_id(peerIdentity)
 {
 	if (!myIdentity.agree(peerIdentity,_key,ZT_PEER_SECRET_KEY_LENGTH))
 		throw std::runtime_error("new peer identity key agreement failed");
 }
 
-void Peer::receive(
+void Peer::received(
 	const RuntimeEnvironment *RR,
 	const SharedPtr<Socket> &fromSock,
 	const InetAddress &remoteAddr,
@@ -79,8 +69,6 @@ void Peer::receive(
 	// Update system-wide last packet receive time
 	*((const_cast<uint64_t *>(&(RR->timeOfLastPacketReceived)))) = now;
 
-	Mutex::Lock _l(_lock);
-
 	// Global last receive time regardless of path
 	_lastReceive = now;
 
@@ -88,28 +76,35 @@ void Peer::receive(
 		// Learn paths from direct packets (hops == 0)
 		{
 			bool havePath = false;
-			for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-				if ((p->address() == remoteAddr)&&(p->tcp() == fromSock->tcp())) {
-					p->received(now);
+			for(unsigned int p=0,np=_numPaths;p<np;++p) {
+				if ((_paths[p].address() == remoteAddr)&&(_paths[p].tcp() == fromSock->tcp())) {
+					_paths[p].received(now);
 					havePath = true;
 					break;
 				}
 			}
 
 			if (!havePath) {
-				Path::Type pt = Path::PATH_TYPE_UDP;
-				switch(fromSock->type()) {
-					case Socket::ZT_SOCKET_TYPE_TCP_IN:
-						pt = Path::PATH_TYPE_TCP_IN;
-						break;
-					case Socket::ZT_SOCKET_TYPE_TCP_OUT:
-						pt = Path::PATH_TYPE_TCP_OUT;
-						break;
-					default:
-						break;
+				unsigned int np = _numPaths;
+				if (np >= ZT_PEER_MAX_PATHS)
+					clean(now);
+				np = _numPaths;
+				if (np < ZT_PEER_MAX_PATHS) {
+					Path::Type pt = Path::PATH_TYPE_UDP;
+					switch(fromSock->type()) {
+						case Socket::ZT_SOCKET_TYPE_TCP_IN:
+							pt = Path::PATH_TYPE_TCP_IN;
+							break;
+						case Socket::ZT_SOCKET_TYPE_TCP_OUT:
+							pt = Path::PATH_TYPE_TCP_OUT;
+							break;
+						default:
+							break;
+					}
+					_paths[np].init(remoteAddr,pt,false);
+					_paths[np].received(now);
+					_numPaths = ++np;
 				}
-				_paths.push_back(Path(remoteAddr,pt,false));
-				_paths.back().received(now);
 			}
 		}
 
@@ -121,10 +116,12 @@ void Peer::receive(
 		if ((now - _lastAnnouncedTo) >= ((ZT_MULTICAST_LIKE_EXPIRE / 2) - 1000)) {
 			_lastAnnouncedTo = now;
 
+			bool isSupernode = RR->topology->isSupernode(_id.address());
+
 			Packet outp(_id.address(),RR->identity.address(),Packet::VERB_MULTICAST_LIKE);
 			std::vector< SharedPtr<Network> > networks(RR->nc->networks());
 			for(std::vector< SharedPtr<Network> >::iterator n(networks.begin());n!=networks.end();++n) {
-				if ( ((*n)->isAllowed(_id.address())) || ((*n)->controller() == _id.address()) || (RR->topology->isSupernode(_id.address())) ) {
+				if ( ((*n)->isAllowed(_id.address())) || (isSupernode) ) {
 					std::set<MulticastGroup> mgs((*n)->multicastGroups());
 					for(std::set<MulticastGroup>::iterator mg(mgs.begin());mg!=mgs.end();++mg) {
 						if ((outp.size() + 18) > ZT_UDP_DEFAULT_PAYLOAD_MTU) {
@@ -155,8 +152,6 @@ void Peer::receive(
 
 Path::Type Peer::send(const RuntimeEnvironment *RR,const void *data,unsigned int len,uint64_t now)
 {
-	Mutex::Lock _l(_lock);
-
 	/* For sending ordinary packets, paths are divided into two categories:
 	 * "normal" and "TCP out." Normal includes UDP and incoming TCP. We want
 	 * to treat outbound TCP differently since if we use it it may end up
@@ -166,17 +161,17 @@ Path::Type Peer::send(const RuntimeEnvironment *RR,const void *data,unsigned int
 	Path *bestTcpOutPath = (Path *)0;
 	uint64_t bestNormalPathLastReceived = 0;
 	uint64_t bestTcpOutPathLastReceived = 0;
-	for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-		uint64_t lr = p->lastReceived();
-		if (p->type() == Path::PATH_TYPE_TCP_OUT) {
+	for(unsigned int p=0,np=_numPaths;p<np;++p) {
+		uint64_t lr = _paths[p].lastReceived();
+		if (_paths[p].type() == Path::PATH_TYPE_TCP_OUT) {
 			if (lr >= bestTcpOutPathLastReceived) {
 				bestTcpOutPathLastReceived = lr;
-				bestTcpOutPath = &(*p);
+				bestTcpOutPath = &(_paths[p]);
 			}
 		} else {
 			if (lr >= bestNormalPathLastReceived) {
 				bestNormalPathLastReceived = lr;
-				bestNormalPath = &(*p);
+				bestNormalPath = &(_paths[p]);
 			}
 		}
 	}
@@ -214,7 +209,6 @@ bool Peer::sendPing(const RuntimeEnvironment *RR,uint64_t now)
 {
 	bool sent = false;
 	SharedPtr<Peer> self(this);
-	Mutex::Lock _l(_lock);
 
 	/* Ping (and thus open) outbound TCP connections if we have no other options
 	 * or if the TCP tunneling master switch is enabled and pings have been
@@ -222,22 +216,22 @@ bool Peer::sendPing(const RuntimeEnvironment *RR,uint64_t now)
 	uint64_t lastNormalPingSent = 0;
 	uint64_t lastNormalReceive = 0;
 	bool haveNormal = false;
-	for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
-		if (p->type() != Path::PATH_TYPE_TCP_OUT) {
-			lastNormalPingSent = std::max(lastNormalPingSent,p->lastPing());
-			lastNormalReceive = std::max(lastNormalReceive,p->lastReceived());
+	for(unsigned int p=0,np=_numPaths;p<np;++p) {
+		if (_paths[p].type() != Path::PATH_TYPE_TCP_OUT) {
+			lastNormalPingSent = std::max(lastNormalPingSent,_paths[p].lastPing());
+			lastNormalReceive = std::max(lastNormalReceive,_paths[p].lastReceived());
 			haveNormal = true;
 		}
 	}
-	const bool useTcpOut = ( (!haveNormal) || ( (RR->tcpTunnelingEnabled) && (lastNormalPingSent > RR->timeOfLastResynchronize) && (lastNormalPingSent > lastNormalReceive) && ((lastNormalPingSent - lastNormalReceive) >= ZT_TCP_TUNNEL_FAILOVER_TIMEOUT) ) );
 
+	const bool useTcpOut = ( (!haveNormal) || ( (RR->tcpTunnelingEnabled) && (lastNormalPingSent > RR->timeOfLastResynchronize) && (lastNormalPingSent > lastNormalReceive) && ((lastNormalPingSent - lastNormalReceive) >= ZT_TCP_TUNNEL_FAILOVER_TIMEOUT) ) );
 	TRACE("PING %s (useTcpOut==%d)",_id.address().toString().c_str(),(int)useTcpOut);
 
-	for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-		if ((useTcpOut)||(p->type() != Path::PATH_TYPE_TCP_OUT)) {
-			p->pinged(now); // attempts to ping are logged whether they look successful or not
-			if (RR->sw->sendHELLO(self,*p)) {
-				p->sent(now);
+	for(unsigned int p=0,np=_numPaths;p<np;++p) {
+		if ((useTcpOut)||(_paths[p].type() != Path::PATH_TYPE_TCP_OUT)) {
+			_paths[p].pinged(now); // attempts to ping are logged whether they look successful or not
+			if (RR->sw->sendHELLO(self,_paths[p])) {
+				_paths[p].sent(now);
 				sent = true;
 			}
 		}
@@ -248,33 +242,68 @@ bool Peer::sendPing(const RuntimeEnvironment *RR,uint64_t now)
 
 void Peer::clean(uint64_t now)
 {
-	Mutex::Lock _l(_lock);
-	unsigned long i = 0,o = 0,l = (unsigned long)_paths.size();
-	while (i != l) {
-		if (_paths[i].active(now)) // active includes fixed
-			_paths[o++] = _paths[i];
-		++i;
+	unsigned int np = _numPaths;
+	unsigned int x = 0;
+	unsigned int y = 0;
+	while (x < np) {
+		if (_paths[x].active(now))
+			_paths[y++] = _paths[x];
+		++x;
+	}
+	_numPaths = y;
+}
+
+void Peer::addPath(const Path &newp)
+{
+	unsigned int np = _numPaths;
+	for(unsigned int p=0;p<np;++p) {
+		if (_paths[p] == newp) {
+			_paths[p].setFixed(newp.fixed());
+			return;
+		}
+	}
+	if (np >= ZT_PEER_MAX_PATHS)
+		clean(Utils::now());
+	np = _numPaths;
+	if (np < ZT_PEER_MAX_PATHS) {
+		_paths[np] = newp;
+		_numPaths = ++np;
+	}
+}
+
+void Peer::clearPaths(bool fixedToo)
+{
+	if (fixedToo) {
+		_numPaths = 0;
+	} else {
+		unsigned int np = _numPaths;
+		unsigned int x = 0;
+		unsigned int y = 0;
+		while (x < np) {
+			if (_paths[x].fixed())
+				_paths[y++] = _paths[x];
+			++x;
+		}
+		_numPaths = y;
 	}
-	_paths.resize(o);
 }
 
 void Peer::getBestActiveUdpPathAddresses(uint64_t now,InetAddress &v4,InetAddress &v6) const
 {
 	uint64_t bestV4 = 0,bestV6 = 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)&&(p->active(now))) {
-			uint64_t lr = p->lastReceived();
+	for(unsigned int p=0,np=_numPaths;p<np;++p) {
+		if ((_paths[p].type() == Path::PATH_TYPE_UDP)&&(_paths[p].active(now))) {
+			uint64_t lr = _paths[p].lastReceived();
 			if (lr) {
-				if (p->address().isV4()) {
+				if (_paths[p].address().isV4()) {
 					if (lr >= bestV4) {
 						bestV4 = lr;
-						v4 = p->address();
+						v4 = _paths[p].address();
 					}
-				} else if (p->address().isV6()) {
+				} else if (_paths[p].address().isV6()) {
 					if (lr >= bestV6) {
 						bestV6 = lr;
-						v6 = p->address();
+						v6 = _paths[p].address();
 					}
 				}
 			}
diff --git a/node/Peer.hpp b/node/Peer.hpp
index 3bb2a56e..78506fd2 100644
--- a/node/Peer.hpp
+++ b/node/Peer.hpp
@@ -30,9 +30,9 @@
 
 #include <stdint.h>
 
-#include <vector>
 #include <algorithm>
 #include <utility>
+#include <vector>
 #include <stdexcept>
 
 #include "Constants.hpp"
@@ -48,23 +48,29 @@
 #include "Socket.hpp"
 #include "AtomicCounter.hpp"
 #include "NonCopyable.hpp"
-#include "Mutex.hpp"
+
+/**
+ * Maximum number of paths a peer can have
+ */
+#define ZT_PEER_MAX_PATHS 8
 
 namespace ZeroTier {
 
 /**
  * Peer on P2P Network
+ *
+ * This struture is not locked, volatile, and memcpy-able. NonCopyable
+ * semantics are just there to prevent bugs, not because it isn't safe
+ * to copy.
  */
 class Peer : NonCopyable
 {
 	friend class SharedPtr<Peer>;
 
-public:
-	/**
-	 * Construct an uninitialized peer (used with deserialize())
-	 */
-	Peer();
+private:
+	Peer() {} // disabled to prevent bugs -- should not be constructed uninitialized
 
+public:
 	~Peer() { Utils::burn(_key,sizeof(_key)); }
 
 	/**
@@ -115,7 +121,7 @@ public:
 	 * @param inReVerb Verb in reply to (for OK/ERROR, VERB_NOP otherwise)
 	 * @param now Current time
 	 */
-	void receive(
+	void received(
 		const RuntimeEnvironment *RR,
 		const SharedPtr<Socket> &fromSock,
 		const InetAddress &remoteAddr,
@@ -162,8 +168,10 @@ public:
 	 */
 	std::vector<Path> paths() const
 	{
-		Mutex::Lock _l(_lock);
-		return _paths;
+		std::vector<Path> pp;
+		for(unsigned int p=0,np=_numPaths;p<np;++p)
+			pp.push_back(_paths[p]);
+		return pp;
 	}
 
 	/**
@@ -172,9 +180,8 @@ public:
 	 */
 	inline bool haveUdpPath(const InetAddress &addr) const
 	{
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
-			if ((p->type() == Path::PATH_TYPE_UDP)&&(p->address() == addr))
+		for(unsigned int p=0,np=_numPaths;p<np;++p) {
+			if ((_paths[p].type() == Path::PATH_TYPE_UDP)&&(_paths[p].address() == addr))
 				return true;
 		}
 		return false;
@@ -187,9 +194,8 @@ public:
 		throw()
 	{
 		uint64_t x = 0;
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p)
-			x = std::max(x,p->lastReceived());
+		for(unsigned int p=0,np=_numPaths;p<np;++p)
+			x = std::max(x,_paths[p].lastReceived());
 		return x;
 	}
 
@@ -200,9 +206,8 @@ public:
 		throw()
 	{
 		uint64_t x = 0;
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p)
-			x = std::max(x,p->lastSend());
+		for(unsigned int p=0,np=_numPaths;p<np;++p)
+			x = std::max(x,_paths[p].lastSend());
 		return x;
 	}
 
@@ -215,10 +220,9 @@ public:
 	inline void lastPingAndDirectReceive(uint64_t &lp,uint64_t &lr)
 		throw()
 	{
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
-			lp = std::max(lp,p->lastPing());
-			lr = std::max(lr,p->lastReceived());
+		for(unsigned int p=0,np=_numPaths;p<np;++p) {
+			lp = std::max(lp,_paths[p].lastPing());
+			lr = std::max(lr,_paths[p].lastReceived());
 		}
 	}
 
@@ -251,11 +255,7 @@ public:
 	 * @param now Current time
 	 * @return True if peer has received something within ZT_PEER_ACTIVITY_TIMEOUT ms
 	 */
-	inline bool alive(uint64_t now) const
-		throw()
-	{
-		return ((now - _lastReceive) < ZT_PEER_ACTIVITY_TIMEOUT);
-	}
+	inline bool alive(uint64_t now) const throw() { return ((now - _lastReceive) < ZT_PEER_ACTIVITY_TIMEOUT); }
 
 	/**
 	 * @return Current latency or 0 if unknown (max: 65535)
@@ -284,12 +284,7 @@ public:
 	/**
 	 * @return True if this peer has at least one direct IP address path
 	 */
-	inline bool hasDirectPath() const
-		throw()
-	{
-		Mutex::Lock _l(_lock);
-		return (!_paths.empty());
-	}
+	inline bool hasDirectPath() const throw() { return (_numPaths != 0); }
 
 	/**
 	 * @param now Current time
@@ -298,9 +293,8 @@ public:
 	inline bool hasActiveDirectPath(uint64_t now) const
 		throw()
 	{
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
-			if (p->active(now))
+		for(unsigned int p=0,np=_numPaths;p<np;++p) {
+			if (_paths[p].active(now))
 				return true;
 		}
 		return false;
@@ -311,35 +305,14 @@ public:
 	 *
 	 * @param p New path to add
 	 */
-	inline void addPath(const Path &newp)
-	{
-		Mutex::Lock _l(_lock);
-		for(std::vector<Path>::iterator p(_paths.begin());p!=_paths.end();++p) {
-			if (*p == newp) {
-				p->setFixed(newp.fixed());
-				return;
-			}
-		}
-		_paths.push_back(newp);
-	}
+	void addPath(const Path &newp);
 
 	/**
 	 * Clear paths
 	 *
 	 * @param fixedToo If true, clear fixed paths as well as learned ones
 	 */
-	inline void clearPaths(bool fixedToo)
-	{
-		std::vector<Path> npv;
-		Mutex::Lock _l(_lock);
-		if (!fixedToo) {
-			for(std::vector<Path>::const_iterator p(_paths.begin());p!=_paths.end();++p) {
-				if (p->fixed())
-					npv.push_back(*p);
-			}
-		}
-		_paths = npv;
-	}
+	void clearPaths(bool fixedToo);
 
 	/**
 	 * @return 256-bit secret symmetric encryption key
@@ -405,11 +378,6 @@ public:
 private:
 	void _announceMulticastGroups(const RuntimeEnvironment *RR,uint64_t now);
 
-	unsigned char _key[ZT_PEER_SECRET_KEY_LENGTH];
-	Identity _id;
-
-	std::vector<Path> _paths;
-
 	volatile uint64_t _lastUsed;
 	volatile uint64_t _lastReceive; // direct or indirect
 	volatile uint64_t _lastUnicastFrame;
@@ -419,9 +387,13 @@ private:
 	volatile uint16_t _vMajor;
 	volatile uint16_t _vMinor;
 	volatile uint16_t _vRevision;
-	volatile unsigned int _latency;
 
-	Mutex _lock;
+	Path _paths[ZT_PEER_MAX_PATHS];
+	volatile unsigned int _numPaths;
+
+	volatile unsigned int _latency;
+	unsigned char _key[ZT_PEER_SECRET_KEY_LENGTH];
+	Identity _id;
 
 	AtomicCounter __refCount;
 };