Merge 17399da399 into 43939cedf4

Please disable LibreSSL workaround when LibreSSL version >= 4.0.0

contrib/docker/docker-compose.yml

@@ -0,0 +1,13 @@
+services:
+  i2pd:
+    container_name: i2pd2
+    image: purplei2p/i2pd
+    #optional
+    entrypoint: ["./entrypoint.sh", "--loglevel error"]
+    ports:
+      - 127.0.0.1:7656:7656
+      - 127.0.0.1:7070:7070
+      - 127.0.0.1:4444:4444
+    volumes:
+      - /path/to/i2pd/data:/home/i2pd/data                 # make sure data directory and it's contents are owned by 100:65533
+      - /path/to/i2pd/i2pd_certificates:/i2pd_certificates # make sure i2pd_certificates is owned by root:root and 755 permissions on the directory

daemon/UnixDaemon.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2024, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -25,6 +25,7 @@
 #include "RouterContext.h"
 #include "ClientContext.h"
 #include "Transports.h"
+#include "util.h"
 
 void handle_signal(int sig)
 {
@@ -220,6 +221,7 @@ namespace i2p
 
 		void DaemonLinux::run ()
 		{
+			i2p::util::SetThreadName ("i2pd-daemon");
 			while (running)
 			{
 				std::this_thread::sleep_for (std::chrono::seconds(1));

libi2pd/Crypto.cpp

@@ -997,7 +997,7 @@ namespace crypto
 		}
 		else
 		{
-#if defined(LIBRESSL_VERSION_NUMBER)
+#if defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x4000000fL
 			std::vector<uint8_t> m(msgLen + 16);
 			if (msg == buf)
 			{	

libi2pd/Destination.h

@@ -142,14 +142,14 @@ namespace client
 			void CancelDestinationRequestWithEncryptedLeaseSet (std::shared_ptr<const i2p::data::BlindedPublicKey> dest, bool notify = true);
 
 			// implements GarlicDestination
-			std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet ();
+			std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet () override;
-			std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool () const { return m_Pool; }
+			std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool () const override { return m_Pool; }
 
 			// override GarlicDestination
-			bool SubmitSessionKey (const uint8_t * key, const uint8_t * tag);
+			bool SubmitSessionKey (const uint8_t * key, const uint8_t * tag) override;
-			void SubmitECIESx25519Key (const uint8_t * key, uint64_t tag);
+			void SubmitECIESx25519Key (const uint8_t * key, uint64_t tag) override;
-			void ProcessGarlicMessage (std::shared_ptr<I2NPMessage> msg);
+			void ProcessGarlicMessage (std::shared_ptr<I2NPMessage> msg) override;
-			void ProcessDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg);
+			void ProcessDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg) override;
 			void SetLeaseSetUpdated (bool post) override;
 
 			bool IsPublic () const { return m_IsPublic; };
@@ -158,8 +158,8 @@ namespace client
 		protected:
 
 			// implements GarlicDestination
-			void HandleI2NPMessage (const uint8_t * buf, size_t len);
+			void HandleI2NPMessage (const uint8_t * buf, size_t len) override;
-			bool HandleCloveI2NPMessage (I2NPMessageType typeID, const uint8_t * payload, size_t len, uint32_t msgID);
+			bool HandleCloveI2NPMessage (I2NPMessageType typeID, const uint8_t * payload, size_t len, uint32_t msgID) override;
 
 			void SetLeaseSet (std::shared_ptr<const i2p::data::LocalLeaseSet> newLeaseSet);
 			int GetLeaseSetType () const { return m_LeaseSetType; };

libi2pd/I2NPProtocol.cpp

@@ -396,8 +396,26 @@ namespace i2p
 					return false;
 				}	
 				uint8_t retCode = 0;
+				// decide if we should accept tunnel
+				bool accept = i2p::context.AcceptsTunnels ();
+				if (accept)
+				{
+					auto congestionLevel = i2p::context.GetCongestionLevel (false);
+					if (congestionLevel >= CONGESTION_LEVEL_MEDIUM)
+					{	
+						if (congestionLevel < CONGESTION_LEVEL_FULL)
+						{
+							// random reject depending on congestion level
+							int level = i2p::tunnel::tunnels.GetRng ()() % (CONGESTION_LEVEL_FULL - CONGESTION_LEVEL_MEDIUM) + CONGESTION_LEVEL_MEDIUM;
+							if (congestionLevel > level)
+								accept = false;
+						}	
+						else	
+							accept = false;
+					}	
+				}	
 				// replace record to reply
-				if (i2p::context.AcceptsTunnels () && i2p::context.GetCongestionLevel (false) < CONGESTION_LEVEL_FULL)
+				if (accept)
 				{
 					auto transitTunnel = i2p::tunnel::CreateTransitTunnel (
 							bufbe32toh (clearText + ECIES_BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET),

libi2pd/NetDb.cpp

@@ -638,6 +638,7 @@ namespace data
 		if (checkForExpiration && uptime > i2p::transport::SSU2_TO_INTRODUCER_SESSION_DURATION) // 1 hour
 			expirationTimeout = i2p::context.IsFloodfill () ? NETDB_FLOODFILL_EXPIRATION_TIMEOUT*1000LL :
 				NETDB_MIN_EXPIRATION_TIMEOUT*1000LL + (NETDB_MAX_EXPIRATION_TIMEOUT - NETDB_MIN_EXPIRATION_TIMEOUT)*1000LL*NETDB_MIN_ROUTERS/total;
+		bool isOffline = checkForExpiration && i2p::transport::transports.GetNumPeers () < NETDB_MIN_TRANSPORTS; // enough routers and uptime, but no tranports
 			
 		std::list<std::pair<std::string, std::shared_ptr<RouterInfo::Buffer> > > saveToDisk;
 		std::list<std::string> removeFromDisk;	
@@ -672,7 +673,7 @@ namespace data
 			if (r->GetProfile ()->IsUnreachable ())
 				r->SetUnreachable (true);
 			// make router reachable back if too few routers or floodfills
-			if (r->IsUnreachable () && (total - deletedCount < NETDB_MIN_ROUTERS || isLowRate ||
+			if (r->IsUnreachable () && (total - deletedCount < NETDB_MIN_ROUTERS || isLowRate || isOffline ||
 				(r->IsFloodfill () && totalFloodfills - deletedFloodfillsCount < NETDB_MIN_FLOODFILLS)))
 				r->SetUnreachable (false);
 			if (!r->IsUnreachable ())

libi2pd/NetDb.hpp

@@ -39,6 +39,7 @@ namespace data
 {
 	const int NETDB_MIN_ROUTERS = 90;
 	const int NETDB_MIN_FLOODFILLS = 5;
+	const int NETDB_MIN_TRANSPORTS = 10 ; // otherwise assume offline
 	const int NETDB_NUM_FLOODFILLS_THRESHOLD = 1200;
 	const int NETDB_NUM_ROUTERS_THRESHOLD = 4*NETDB_NUM_FLOODFILLS_THRESHOLD;
 	const int NETDB_TUNNEL_CREATION_RATE_THRESHOLD = 10; // in %

libi2pd/Profiling.h

@@ -11,6 +11,7 @@
 
 #include <memory>
 #include <future>
+#include <boost/asio.hpp>
 #include "Identity.h"
 
 namespace i2p
@@ -68,6 +69,11 @@ namespace data
 			bool IsUseful() const;
 			bool IsDuplicated () const { return m_IsDuplicated; };
 
+			const boost::asio::ip::udp::endpoint& GetLastEndpoint () const { return m_LastEndpoint; }
+			void SetLastEndpoint (const boost::asio::ip::udp::endpoint& ep) { m_LastEndpoint = ep; }
+			bool HasLastEndpoint (bool v4) const { return !m_LastEndpoint.address ().is_unspecified () && m_LastEndpoint.port () && 
+				((v4 && m_LastEndpoint.address ().is_v4 ()) || (!v4 && m_LastEndpoint.address ().is_v6 ())); }
+			
 		private:
 
 			void UpdateTime ();
@@ -90,6 +96,8 @@ namespace data
 			uint32_t m_NumTimesRejected;
 			bool m_HasConnected; // successful trusted(incoming or NTCP2) connection 
 			bool m_IsDuplicated;
+			// connectivity
+			boost::asio::ip::udp::endpoint m_LastEndpoint; // SSU2 for non-published addresses
 	};
 
 	std::shared_ptr<RouterProfile> GetRouterProfile (const IdentHash& identHash);

libi2pd/RouterContext.cpp

@@ -1489,7 +1489,7 @@ namespace i2p
 	void RouterContext::UpdateCongestion ()
 	{
 		auto c = i2p::data::RouterInfo::eLowCongestion;
-		if (!AcceptsTunnels () || !m_ShareRatio)
+		if (!AcceptsTunnels () || !m_ShareRatio || (m_Error == eRouterErrorSymmetricNAT && !SupportsV6 () && !SupportsMesh ()))                                        	
 			c = i2p::data::RouterInfo::eRejectAll;
 		else
 		{

libi2pd/RouterContext.h

@@ -146,7 +146,6 @@ namespace garlic
 			void SetNetID (int netID) { m_NetID = netID; };
 			bool DecryptTunnelBuildRecord (const uint8_t * encrypted, uint8_t * data);
 			bool DecryptTunnelShortRequestRecord (const uint8_t * encrypted, uint8_t * data);
-			void SubmitECIESx25519Key (const uint8_t * key, uint64_t tag);
 
 			void UpdatePort (int port); // called from Daemon
 			void UpdateAddress (const boost::asio::ip::address& host); // called from SSU2 or Daemon
@@ -186,24 +185,24 @@ namespace garlic
 			void UpdateTimestamp (uint64_t ts); // in seconds, called from NetDb before publishing
 
 			// implements LocalDestination
-			std::shared_ptr<const i2p::data::IdentityEx> GetIdentity () const { return m_Keys.GetPublic (); };
+			std::shared_ptr<const i2p::data::IdentityEx> GetIdentity () const override{ return m_Keys.GetPublic (); };
-			bool Decrypt (const uint8_t * encrypted, uint8_t * data, i2p::data::CryptoKeyType preferredCrypto) const;
+			bool Decrypt (const uint8_t * encrypted, uint8_t * data, i2p::data::CryptoKeyType preferredCrypto) const override;
-			void Sign (const uint8_t * buf, int len, uint8_t * signature) const { m_Keys.Sign (buf, len, signature); };
+			void SetLeaseSetUpdated (bool post) override {};
-			void SetLeaseSetUpdated () {};
 
 			// implements GarlicDestination
-			std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet () { return nullptr; };
+			std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet () override { return nullptr; };
-			std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool () const;
+			std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool () const override;
 
 			// override GarlicDestination
-			void ProcessGarlicMessage (std::shared_ptr<I2NPMessage> msg);
+			void ProcessGarlicMessage (std::shared_ptr<I2NPMessage> msg) override;
-			void ProcessDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg);
+			void ProcessDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg) override;
+			void SubmitECIESx25519Key (const uint8_t * key, uint64_t tag) override;
 
 		protected:
 
 			// implements GarlicDestination
-			void HandleI2NPMessage (const uint8_t * buf, size_t len);
+			void HandleI2NPMessage (const uint8_t * buf, size_t len) override;
-			bool HandleCloveI2NPMessage (I2NPMessageType typeID, const uint8_t * payload, size_t len, uint32_t msgID);
+			bool HandleCloveI2NPMessage (I2NPMessageType typeID, const uint8_t * payload, size_t len, uint32_t msgID) override;
 
 		private:
 
@@ -216,6 +215,7 @@ namespace garlic
 			void UpdateSSU2Keys ();
 			bool Load ();
 			void SaveKeys ();
+			void Sign (const uint8_t * buf, int len, uint8_t * signature) const { m_Keys.Sign (buf, len, signature); };
 			uint16_t SelectRandomPort () const;
 			void PublishNTCP2Address (std::shared_ptr<i2p::data::RouterInfo::Address> address, int port, bool publish) const;
 

libi2pd/SSU2.cpp

@@ -216,15 +216,16 @@ namespace transport
 		return ep.port ();
 	}
 
-	bool SSU2Server::IsConnectedRecently (const boost::asio::ip::udp::endpoint& ep)
+	bool SSU2Server::IsConnectedRecently (const boost::asio::ip::udp::endpoint& ep, bool max)
 	{
 		if (!ep.port () || ep.address ().is_unspecified ()) return false;
+		std::lock_guard<std::mutex> l(m_ConnectedRecentlyMutex);
 		auto it = m_ConnectedRecently.find (ep);
 		if (it != m_ConnectedRecently.end ())
 		{	
-			if (i2p::util::GetSecondsSinceEpoch () <= it->second + SSU2_HOLE_PUNCH_EXPIRATION)
+			if (i2p::util::GetSecondsSinceEpoch () <= it->second + (max ? SSU2_MAX_HOLE_PUNCH_EXPIRATION : SSU2_MIN_HOLE_PUNCH_EXPIRATION))
 				return true;
-			else
+			else if (max)
 				m_ConnectedRecently.erase (it);
 		}	
 		return false;
@@ -233,7 +234,8 @@ namespace transport
 	void SSU2Server::AddConnectedRecently (const boost::asio::ip::udp::endpoint& ep, uint64_t ts)
 	{
 		if (!ep.port () || ep.address ().is_unspecified () || 
-		    i2p::util::GetSecondsSinceEpoch () > ts + SSU2_HOLE_PUNCH_EXPIRATION) return;
+		    i2p::util::GetSecondsSinceEpoch () > ts + SSU2_MAX_HOLE_PUNCH_EXPIRATION) return;
+		std::lock_guard<std::mutex> l(m_ConnectedRecentlyMutex);
 		auto [it, added] = m_ConnectedRecently.try_emplace (ep, ts);
 		if (!added && ts > it->second)
 			it->second = ts; // renew timestamp of existing endpoint
@@ -475,7 +477,7 @@ namespace transport
 		HandleReceivedPackets (std::move (receivedPackets));
 	}	
 		
-	void SSU2Server::AddSession (std::shared_ptr<SSU2Session> session)
+	bool SSU2Server::AddSession (std::shared_ptr<SSU2Session> session)
 	{
 		if (session)
 		{
@@ -483,8 +485,10 @@ namespace transport
 			{	
 				if (session->GetState () != eSSU2SessionStatePeerTest)
 					AddSessionByRouterHash (session);
+				return true;
 			}	
 		}
+		return false;
 	}
 
 	void SSU2Server::RemoveSession (uint64_t connID)
@@ -833,6 +837,29 @@ namespace transport
 		}
 	}
 
+	bool SSU2Server::CheckPendingOutgoingSession (const boost::asio::ip::udp::endpoint& ep, bool peerTest)
+	{
+		auto s = FindPendingOutgoingSession (ep);
+		if (s)
+		{
+			if (peerTest)
+			{
+				// if peer test requested add it to the list for pending session
+				auto onEstablished = s->GetOnEstablished ();
+				if (onEstablished)
+					s->SetOnEstablished ([s, onEstablished]()
+						{
+							onEstablished ();
+							s->SendPeerTest ();
+						});
+				else
+					s->SetOnEstablished ([s]() { s->SendPeerTest (); });
+			}
+			return true;
+		}
+		return false;
+	}	
+		
 	bool SSU2Server::CreateSession (std::shared_ptr<const i2p::data::RouterInfo> router,
 		std::shared_ptr<const i2p::data::RouterInfo::Address> address, bool peerTest)
 	{
@@ -852,34 +879,28 @@ namespace transport
 			if (isValidEndpoint)
 			{
 				if (i2p::transport::transports.IsInReservedRange(address->host)) return false;
-				auto s = FindPendingOutgoingSession (boost::asio::ip::udp::endpoint (address->host, address->port));
+				if (CheckPendingOutgoingSession (boost::asio::ip::udp::endpoint (address->host, address->port), peerTest)) return false;
-				if (s)
-				{
-					if (peerTest)
-					{
-						// if peer test requested add it to the list for pending session
-						auto onEstablished = s->GetOnEstablished ();
-						if (onEstablished)
-							s->SetOnEstablished ([s, onEstablished]()
-								{
-									onEstablished ();
-									s->SendPeerTest ();
-								});
-						else
-							s->SetOnEstablished ([s]() { s->SendPeerTest (); });
-					}
-					return false;
-				}
 			}
 
 			auto session = std::make_shared<SSU2Session> (*this, router, address);
+			if (!isValidEndpoint && router->GetProfile ()->HasLastEndpoint (address->IsV4 ()))
+			{
+				// router doesn't publish endpoint, but we connected before and hole punch might be alive
+				auto ep = router->GetProfile ()->GetLastEndpoint ();
+				if (IsConnectedRecently (ep, false))
+				{
+					if (CheckPendingOutgoingSession (ep, peerTest)) return false;
+					session->SetRemoteEndpoint (ep);
+					isValidEndpoint = true;
+				}	
+			}	
 			if (peerTest)
 				session->SetOnEstablished ([session]() {session->SendPeerTest (); });
 
-			if (address->UsesIntroducer ())
+			if (isValidEndpoint) // we know endpoint
-				GetService ().post (std::bind (&SSU2Server::ConnectThroughIntroducer, this, session));
-			else if (isValidEndpoint) // we can't connect without endpoint
 				GetService ().post ([session]() { session->Connect (); });
+			else if (address->UsesIntroducer ()) // we don't know endpoint yet
+				GetService ().post (std::bind (&SSU2Server::ConnectThroughIntroducer, this, session));
 			else
 				return false;
 		}
@@ -1129,7 +1150,7 @@ namespace transport
 
 			for (auto it = m_ConnectedRecently.begin (); it != m_ConnectedRecently.end (); )
 			{
-				if (ts > it->second + SSU2_HOLE_PUNCH_EXPIRATION)
+				if (ts > it->second + SSU2_MAX_HOLE_PUNCH_EXPIRATION)
 					it = m_ConnectedRecently.erase (it);
 				else
 					it++;

libi2pd/SSU2.h

@@ -42,7 +42,8 @@ namespace transport
 	const int SSU2_KEEP_ALIVE_INTERVAL = 15; // in seconds
 	const int SSU2_KEEP_ALIVE_INTERVAL_VARIANCE = 4; // in seconds
 	const int SSU2_PROXY_CONNECT_RETRY_TIMEOUT = 30; // in seconds
-	const int SSU2_HOLE_PUNCH_EXPIRATION = 150; // in seconds
+	const int SSU2_MIN_HOLE_PUNCH_EXPIRATION = 30; // in seconds
+	const int SSU2_MAX_HOLE_PUNCH_EXPIRATION = 160; // in seconds
 	const size_t SSU2_MAX_NUM_PACKETS_PER_BATCH = 64;
 
 	class SSU2Server: private i2p::util::RunnableServiceWithWork
@@ -77,14 +78,14 @@ namespace transport
 			bool UsesProxy () const { return m_IsThroughProxy; };
 			bool IsSupported (const boost::asio::ip::address& addr) const;
 			uint16_t GetPort (bool v4) const;
-			bool IsConnectedRecently (const boost::asio::ip::udp::endpoint& ep);
+			bool IsConnectedRecently (const boost::asio::ip::udp::endpoint& ep, bool max = true);
 			void AddConnectedRecently (const boost::asio::ip::udp::endpoint& ep, uint64_t ts);
 			std::mt19937& GetRng () { return m_Rng; }
 			bool IsMaxNumIntroducers (bool v4) const { return (v4 ? m_Introducers.size () : m_IntroducersV6.size ()) >= SSU2_MAX_NUM_INTRODUCERS; }
 			bool IsSyncClockFromPeers () const { return m_IsSyncClockFromPeers; };
 			void AdjustTimeOffset (int64_t offset, std::shared_ptr<const i2p::data::IdentityEx> from);
 
-			void AddSession (std::shared_ptr<SSU2Session> session);
+			bool AddSession (std::shared_ptr<SSU2Session> session);
 			void RemoveSession (uint64_t connID);
 			void RequestRemoveSession (uint64_t connID);
 			void AddSessionByRouterHash (std::shared_ptr<SSU2Session> session);
@@ -147,6 +148,7 @@ namespace transport
 			void ScheduleResend (bool more);
 			void HandleResendTimer (const boost::system::error_code& ecode);
 
+			bool CheckPendingOutgoingSession (const boost::asio::ip::udp::endpoint& ep, bool peerTest);
 			void ConnectThroughIntroducer (std::shared_ptr<SSU2Session> session);
 			std::vector<std::shared_ptr<SSU2Session> > FindIntroducers (int maxNumIntroducers,
 				bool v4, const std::unordered_set<i2p::data::IdentHash>& excluded);
@@ -193,6 +195,7 @@ namespace transport
 			std::shared_ptr<const i2p::data::IdentityEx> m_PendingTimeOffsetFrom;
 			std::mt19937 m_Rng;
 			std::map<boost::asio::ip::udp::endpoint, uint64_t> m_ConnectedRecently; // endpoint -> last activity time in seconds
+			mutable std::mutex m_ConnectedRecentlyMutex;
 			std::unordered_map<uint32_t, std::pair <std::weak_ptr<SSU2PeerTestSession>, uint64_t > > m_RequestedPeerTests; // nonce->(Alice, timestamp) 
 			std::list<Packet *> m_ReceivedPacketsQueue;
 			mutable std::mutex m_ReceivedPacketsQueueMutex;

libi2pd/SSU2Session.cpp

@@ -83,7 +83,7 @@ namespace transport
 		std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool noise):
 		TransportSession (in_RemoteRouter, SSU2_CONNECT_TIMEOUT),
 		m_Server (server), m_Address (addr), m_RemoteTransports (0), m_RemotePeerTestTransports (0),
-		m_DestConnID (0), m_SourceConnID (0), m_State (eSSU2SessionStateUnknown),
+		m_RemoteVersion (0), m_DestConnID (0), m_SourceConnID (0), m_State (eSSU2SessionStateUnknown),
 		m_SendPacketNum (0), m_ReceivePacketNum (0), m_LastDatetimeSentPacketNum (0),
 		m_IsDataReceived (false), m_RTT (SSU2_UNKNOWN_RTT),
 		m_MsgLocalExpirationTimeout (I2NP_MESSAGE_LOCAL_EXPIRATION_TIMEOUT_MAX),
@@ -103,6 +103,7 @@ namespace transport
 				InitNoiseXKState1 (*m_NoiseState, m_Address->s);
 			m_RemoteEndpoint = boost::asio::ip::udp::endpoint (m_Address->host, m_Address->port);
 			m_RemoteTransports = in_RemoteRouter->GetCompatibleTransports (false);
+			m_RemoteVersion = in_RemoteRouter->GetVersion ();
 			if (in_RemoteRouter->IsSSU2PeerTesting (true)) m_RemotePeerTestTransports |= i2p::data::RouterInfo::eSSU2V4;
 			if (in_RemoteRouter->IsSSU2PeerTesting (false)) m_RemotePeerTestTransports |= i2p::data::RouterInfo::eSSU2V6;
 			RAND_bytes ((uint8_t *)&m_DestConnID, 8);
@@ -226,6 +227,13 @@ namespace transport
 			if (m_Server.AddPendingOutgoingSession (shared_from_this ()))
 			{                                                             
 				m_Server.RemoveSession (GetConnID ());
+				// update endpoint in profile because we know it now 
+				auto identity = GetRemoteIdentity ();
+				if (identity)
+				{	
+					auto profile = i2p::data::GetRouterProfile (identity->GetIdentHash ());
+					if (profile) profile->SetLastEndpoint (m_RemoteEndpoint);
+				}	
 				// connect
 				LogPrint (eLogDebug, "SSU2: Connecting after introduction to ", GetIdentHashBase64());
 				Connect ();
@@ -1169,6 +1177,8 @@ namespace transport
 					" and actual endpoint ", m_RemoteEndpoint.address (), " from ", i2p::data::GetIdentHashAbbreviation (ri->GetIdentHash ()));
 			return false;
 		}
+		if (!m_Address->published)
+			ri->GetProfile ()->SetLastEndpoint (m_RemoteEndpoint);
 		SetRemoteIdentity (ri->GetRouterIdentity ());
 		AdjustMaxPayloadSize ();
 		m_Server.AddSessionByRouterHash (shared_from_this ()); // we know remote router now
@@ -1176,6 +1186,7 @@ namespace transport
 		m_RemotePeerTestTransports = 0;
 		if (ri->IsSSU2PeerTesting (true)) m_RemotePeerTestTransports |= i2p::data::RouterInfo::eSSU2V4;
 		if (ri->IsSSU2PeerTesting (false)) m_RemotePeerTestTransports |= i2p::data::RouterInfo::eSSU2V6;
+		m_RemoteVersion = ri->GetVersion ();
 		
 		// handle other blocks
 		HandlePayload (decryptedPayload.data () + riSize + 3, decryptedPayload.size () - riSize - 3);
@@ -1920,25 +1931,28 @@ namespace transport
 			return;
 		}
 		auto mts = i2p::util::GetMillisecondsSinceEpoch ();
-		session->m_RelaySessions.emplace (bufbe32toh (buf + 1), // nonce
+		uint32_t nonce = bufbe32toh (buf + 1);
-			std::make_pair (shared_from_this (), mts/1000) );
+		if (session->m_RelaySessions.emplace (nonce, std::make_pair (shared_from_this (), mts/1000)).second)
+		{
+			// send relay intro to Charlie
+			auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ()); // Alice's RI
+			if (r && (r->IsUnreachable () || !i2p::data::netdb.PopulateRouterInfoBuffer (r))) r = nullptr;
+			if (!r) LogPrint (eLogWarning, "SSU2: RelayRequest Alice's router info not found");
 
-		// send relay intro to Charlie
+			auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
-		auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ()); // Alice's RI
+			packet->payloadSize = r ? CreateRouterInfoBlock (packet->payload, m_MaxPayloadSize - len - 32, r) : 0;
-		if (r && (r->IsUnreachable () || !i2p::data::netdb.PopulateRouterInfoBuffer (r))) r = nullptr;
+			if (!packet->payloadSize && r)
-		if (!r) LogPrint (eLogWarning, "SSU2: RelayRequest Alice's router info not found");
+				session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
-
+			packet->payloadSize += CreateRelayIntroBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, buf + 1, len -1);
-		auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
+			if (packet->payloadSize < m_MaxPayloadSize)
-		packet->payloadSize = r ? CreateRouterInfoBlock (packet->payload, m_MaxPayloadSize - len - 32, r) : 0;
+				packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
-		if (!packet->payloadSize && r)
+			uint32_t packetNum = session->SendData (packet->payload, packet->payloadSize);
-			session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
+			packet->sendTime = mts;
-		packet->payloadSize += CreateRelayIntroBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, buf + 1, len -1);
+			// Charlie always responds with RelayResponse
-		if (packet->payloadSize < m_MaxPayloadSize)
+			session->m_SentPackets.emplace (packetNum, packet);
-			packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
+		}
-		uint32_t packetNum = session->SendData (packet->payload, packet->payloadSize);
+		else
-		packet->sendTime = mts;
+			LogPrint (eLogInfo, "SSU2: Relay request nonce ", nonce, " already exists. Ignore");
-		// Charlie always responds with RelayResponse
-		session->m_SentPackets.emplace (packetNum, packet);
 	}
 
 	void SSU2Session::HandleRelayIntro (const uint8_t * buf, size_t len, int attempts)
@@ -2024,15 +2038,22 @@ namespace transport
 		{
 			// send HolePunch 
 			auto holePunchSession = std::make_shared<SSU2HolePunchSession>(m_Server, nonce, ep, addr); 
-			m_Server.AddSession (holePunchSession);
+			if (m_Server.AddSession (holePunchSession))
-			holePunchSession->SendHolePunch (packet->payload, packet->payloadSize); // relay response block
+				holePunchSession->SendHolePunch (packet->payload, packet->payloadSize); // relay response block
+			else
+			{
+				LogPrint (eLogInfo, "SSU2: Relay intro nonce ", nonce, " already exists. Ignore");
+				return;
+			}		
 		}	
 		packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
-		/*uint32_t packetNum = */SendData (packet->payload, packet->payloadSize);
+		uint32_t packetNum = SendData (packet->payload, packet->payloadSize);
-		// sometimes Bob doesn't ack this RelayResponse
+		if (m_RemoteVersion >= SSU2_MIN_RELAY_RESPONSE_RESEND_VERSION)
-		// TODO: uncomment line below once the problem is resolved
+		{	
-		//packet->sendTime = mts;
+			// sometimes Bob doesn't ack this RelayResponse in older versions
-		//m_SentPackets.emplace (packetNum, packet);
+			packet->sendTime = i2p::util::GetMillisecondsSinceEpoch ();
+			m_SentPackets.emplace (packetNum, packet);
+		}	
 	}
 
 	void SSU2Session::HandleRelayResponse (const uint8_t * buf, size_t len)
@@ -2067,11 +2088,13 @@ namespace transport
 				memcpy (payload + 3, buf, len); // forward to Alice as is
 				packet->payloadSize = len + 3;
 				packet->payloadSize += CreatePaddingBlock (payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
-				/*uint32_t packetNum = */it->second.first->SendData (packet->payload, packet->payloadSize);
+				uint32_t packetNum = it->second.first->SendData (packet->payload, packet->payloadSize);
-				// sometimes Alice doesn't ack this RelayResponse
+				if (m_RemoteVersion >= SSU2_MIN_RELAY_RESPONSE_RESEND_VERSION)
-				// TODO: uncomment line below once the problem is resolved
+				{	
-				//packet->sendTime = i2p::util::GetMillisecondsSinceEpoch ();
+					// sometimes Alice doesn't ack this RelayResponse in older versions
-				//it->second.first->m_SentPackets.emplace (packetNum, packet);
+					packet->sendTime = i2p::util::GetMillisecondsSinceEpoch ();
+					it->second.first->m_SentPackets.emplace (packetNum, packet);
+				}	
 			}
 			else
 			{
@@ -2139,29 +2162,33 @@ namespace transport
 					GetRemoteIdentity ()->GetIdentHash ());
 				if (session) // session with Charlie
 				{
-					m_Server.AddPeerTest (nonce, shared_from_this (), ts/1000);
+					if (m_Server.AddPeerTest (nonce, shared_from_this (), ts/1000))
-					auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
-					// Alice's RouterInfo
-					auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ());
-					if (r && (r->IsUnreachable () || !i2p::data::netdb.PopulateRouterInfoBuffer (r))) r = nullptr;
-					packet->payloadSize = r ? CreateRouterInfoBlock (packet->payload, m_MaxPayloadSize - len - 32, r) : 0;
-					if (!packet->payloadSize && r)
-						session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
-					if (packet->payloadSize + len + 48 > m_MaxPayloadSize)
 					{	
-						// doesn't fit one message, send RouterInfo in separate message
+						auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
+						// Alice's RouterInfo
+						auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ());
+						if (r && (r->IsUnreachable () || !i2p::data::netdb.PopulateRouterInfoBuffer (r))) r = nullptr;
+						packet->payloadSize = r ? CreateRouterInfoBlock (packet->payload, m_MaxPayloadSize - len - 32, r) : 0;
+						if (!packet->payloadSize && r)
+							session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
+						if (packet->payloadSize + len + 48 > m_MaxPayloadSize)
+						{
+							// doesn't fit one message, send RouterInfo in separate message
+							uint32_t packetNum = session->SendData (packet->payload, packet->payloadSize, SSU2_FLAG_IMMEDIATE_ACK_REQUESTED);
+							packet->sendTime = ts;
+							session->m_SentPackets.emplace (packetNum, packet);
+							packet = m_Server.GetSentPacketsPool ().AcquireShared (); // new packet
+						}
+						// PeerTest to Charlie
+						packet->payloadSize += CreatePeerTestBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, 2,
+							eSSU2PeerTestCodeAccept, GetRemoteIdentity ()->GetIdentHash (), buf + offset, len - offset);
+						packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
 						uint32_t packetNum = session->SendData (packet->payload, packet->payloadSize, SSU2_FLAG_IMMEDIATE_ACK_REQUESTED);
 						packet->sendTime = ts;
 						session->m_SentPackets.emplace (packetNum, packet);
-						packet = m_Server.GetSentPacketsPool ().AcquireShared (); // new packet
 					}
-					// PeerTest to Charlie
+					else
-					packet->payloadSize += CreatePeerTestBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, 2,
+						LogPrint (eLogInfo, "SSU2: Peer test 1 nonce ", nonce, " already exists. Ignored");
-						eSSU2PeerTestCodeAccept, GetRemoteIdentity ()->GetIdentHash (), buf + offset, len - offset);
-					packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
-					uint32_t packetNum = session->SendData (packet->payload, packet->payloadSize, SSU2_FLAG_IMMEDIATE_ACK_REQUESTED);
-					packet->sendTime = ts;
-					session->m_SentPackets.emplace (packetNum, packet);
 				}
 				else
 				{
@@ -2303,11 +2330,11 @@ namespace transport
 							{
 								session->SetRemoteIdentity (r->GetIdentity ());
 								auto addr = r->GetSSU2Address (m_Address->IsV4 ());
-								if (addr)
+								if (addr && addr->IsPeerTesting ())
 								{
 									if (session->GetMsgNumReceived () >= 5)
 									{
-										// msg 5 already received 
+										// msg 5 already received and we know remote endpoint
 										if (session->GetMsgNumReceived () == 5)
 										{	
 											if (!session->IsConnectedRecently ())
@@ -2324,7 +2351,11 @@ namespace transport
 										if (GetTestingState ())
 										{
 											// schedule msg 6 with delay
-											session->SendPeerTest (6, buf + offset, len - offset, addr, true);
+											if (!addr->host.is_unspecified () && addr->port)
+											{	
+												session->SetRemoteEndpoint (boost::asio::ip::udp::endpoint (addr->host, addr->port));
+												session->SendPeerTest (6, buf + offset, len - offset, addr, true);
+											}	
 											SetTestingState (false);
 											if (GetRouterStatus () != eRouterStatusFirewalled && addr->IsPeerTesting ())
 											{
@@ -2342,7 +2373,7 @@ namespace transport
 								}
 								else
 								{
-									LogPrint (eLogWarning, "SSU2: Peer test 4 address not found");
+									LogPrint (eLogWarning, "SSU2: Peer test 4 address not found or not supported");
 									session->Done ();
 								}
 							}
@@ -3024,7 +3055,7 @@ namespace transport
 		{
 			if (ts > it->second.second + SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT)
 			{
-				LogPrint (eLogWarning, "SSU2: Relay nonce ", it->first, " was not responded in ", SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT, " seconds, deleted");
+				LogPrint (eLogInfo, "SSU2: Relay nonce ", it->first, " was not responded in ", SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT, " seconds, deleted");
 				it = m_RelaySessions.erase (it);
 			}
 			else

libi2pd/SSU2Session.h

@@ -15,6 +15,7 @@
 #include <set>
 #include <list>
 #include <boost/asio.hpp>
+#include "version.h"
 #include "Crypto.h"
 #include "RouterInfo.h"
 #include "RouterContext.h"
@@ -55,6 +56,7 @@ namespace transport
 	const int SSU2_MAX_NUM_ACK_RANGES = 32; // to send
 	const uint8_t SSU2_MAX_NUM_FRAGMENTS = 64;
 	const int SSU2_SEND_DATETIME_NUM_PACKETS = 256;
+	const int SSU2_MIN_RELAY_RESPONSE_RESEND_VERSION = MAKE_VERSION_NUMBER(0, 9, 64); // 0.9.64
 
 	// flags
 	const uint8_t SSU2_FLAG_IMMEDIATE_ACK_REQUESTED = 0x01;
@@ -368,6 +370,7 @@ namespace transport
 			std::shared_ptr<const i2p::data::RouterInfo::Address> m_Address;
 			boost::asio::ip::udp::endpoint m_RemoteEndpoint;
 			i2p::data::RouterInfo::CompatibleTransports m_RemoteTransports, m_RemotePeerTestTransports; 
+			int m_RemoteVersion;
 			uint64_t m_DestConnID, m_SourceConnID;
 			SSU2SessionState m_State;
 			uint8_t m_KeyDataSend[64], m_KeyDataReceive[64];

libi2pd/Streaming.cpp

@@ -73,14 +73,14 @@ namespace stream
 		m_LastConfirmedReceivedSequenceNumber (0), // for limit inbound speed
 		m_Status (eStreamStatusNew), m_IsAckSendScheduled (false), m_IsNAcked (false), m_IsFirstACK (false), 
 		m_IsResendNeeded (false), m_IsFirstRttSample (false), m_IsSendTime (true), m_IsWinDropped (false),
-		m_IsTimeOutResend (false), m_IsImmediateAckRequested (false), m_LocalDestination (local),
+		m_IsTimeOutResend (false), m_IsImmediateAckRequested (false), m_IsRemoteLeaseChangeInProgress (false), m_LocalDestination (local),
 		m_RemoteLeaseSet (remote), m_ReceiveTimer (m_Service), m_SendTimer (m_Service), m_ResendTimer (m_Service),
 		m_AckSendTimer (m_Service), m_NumSentBytes (0), m_NumReceivedBytes (0), m_Port (port),
 		m_RTT (INITIAL_RTT), m_SlowRTT (INITIAL_RTT), m_SlowRTT2 (INITIAL_RTT), m_WindowSize (INITIAL_WINDOW_SIZE), m_LastWindowDropSize  (0),
 		m_WindowDropTargetSize (0), m_WindowIncCounter (0), m_RTO (INITIAL_RTO),
 		m_AckDelay (local.GetOwner ()->GetStreamingAckDelay ()), m_PrevRTTSample (INITIAL_RTT), 
 		m_Jitter (0), m_MinPacingTime (0),
-		m_PacingTime (INITIAL_PACING_TIME), m_PacingTimeRem (0), m_LastSendTime (0),
+		m_PacingTime (INITIAL_PACING_TIME), m_PacingTimeRem (0), m_LastSendTime (0), m_RemoteLeaseChangeTime (0),
 		m_LastACKSendTime (0), m_PacketACKInterval (1), m_PacketACKIntervalRem (0), // for limit inbound speed
 		m_NumResendAttempts (0), m_NumPacketsToSend (0), m_MTU (STREAMING_MTU)
 	{
@@ -101,13 +101,13 @@ namespace stream
 		m_LastConfirmedReceivedSequenceNumber (0), // for limit inbound speed
 		m_Status (eStreamStatusNew), m_IsAckSendScheduled (false), m_IsNAcked (false), m_IsFirstACK (false), 
 		m_IsResendNeeded (false), m_IsFirstRttSample (false), m_IsSendTime (true), m_IsWinDropped (false),
-		m_IsTimeOutResend (false), m_IsImmediateAckRequested (false), m_LocalDestination (local),
+		m_IsTimeOutResend (false), m_IsImmediateAckRequested (false), m_IsRemoteLeaseChangeInProgress (false), m_LocalDestination (local),
 		m_ReceiveTimer (m_Service), m_SendTimer (m_Service), m_ResendTimer (m_Service), m_AckSendTimer (m_Service),
 		m_NumSentBytes (0), m_NumReceivedBytes (0), m_Port (0), m_RTT (INITIAL_RTT), m_SlowRTT (INITIAL_RTT), m_SlowRTT2 (INITIAL_RTT),
 		m_WindowSize (INITIAL_WINDOW_SIZE), m_LastWindowDropSize  (0), m_WindowDropTargetSize (0), m_WindowIncCounter (0), 
 		m_RTO (INITIAL_RTO), m_AckDelay (local.GetOwner ()->GetStreamingAckDelay ()),
 		m_PrevRTTSample (INITIAL_RTT), m_Jitter (0), m_MinPacingTime (0),
-		m_PacingTime (INITIAL_PACING_TIME), m_PacingTimeRem (0), m_LastSendTime (0),
+		m_PacingTime (INITIAL_PACING_TIME), m_PacingTimeRem (0), m_LastSendTime (0), m_RemoteLeaseChangeTime (0),
 		m_LastACKSendTime (0), m_PacketACKInterval (1), m_PacketACKIntervalRem (0), // for limit inbound speed
 		m_NumResendAttempts (0), m_NumPacketsToSend (0), m_MTU (STREAMING_MTU)
 	{
@@ -256,6 +256,7 @@ namespace stream
 				if (receivedSeqn <= m_PreviousReceivedSequenceNumber || receivedSeqn == m_LastReceivedSequenceNumber)
  				{
  					m_CurrentOutboundTunnel = m_LocalDestination.GetOwner ()->GetTunnelPool ()->GetNextOutboundTunnel (m_CurrentOutboundTunnel);
+ 					CancelRemoteLeaseChange ();
  					UpdateCurrentRemoteLease ();
  				}
  				m_PreviousReceivedSequenceNumber = receivedSeqn;
@@ -1104,6 +1105,7 @@ namespace stream
 	{
 		if (!m_RemoteLeaseSet)
 		{
+			CancelRemoteLeaseChange ();
 			UpdateCurrentRemoteLease ();
 			if (!m_RemoteLeaseSet)
 			{
@@ -1127,9 +1129,30 @@ namespace stream
 		}
 
 		auto ts = i2p::util::GetMillisecondsSinceEpoch ();
-		if (!m_CurrentRemoteLease || !m_CurrentRemoteLease->endDate || // excluded from LeaseSet
+		if (!m_CurrentRemoteLease || !m_CurrentRemoteLease->endDate) // excluded from LeaseSet
-			ts >= m_CurrentRemoteLease->endDate - i2p::data::LEASE_ENDDATE_THRESHOLD)
+		{
+			CancelRemoteLeaseChange ();
 			UpdateCurrentRemoteLease (true);
+		}
+		if (m_RemoteLeaseChangeTime && m_IsRemoteLeaseChangeInProgress && ts > m_RemoteLeaseChangeTime + INITIAL_RTT)
+		{
+			CancelRemoteLeaseChange ();
+			m_CurrentRemoteLease = m_NextRemoteLease;
+			HalveWindowSize ();
+		}
+		auto currentRemoteLease = m_CurrentRemoteLease;
+		if (!m_IsRemoteLeaseChangeInProgress && m_RemoteLeaseSet && m_CurrentRemoteLease && ts >= m_CurrentRemoteLease->endDate - i2p::data::LEASE_ENDDATE_THRESHOLD)
+		{
+			auto leases = m_RemoteLeaseSet->GetNonExpiredLeases (false);
+			if (leases.size ())
+			{
+				m_IsRemoteLeaseChangeInProgress = true;
+				UpdateCurrentRemoteLease (true);
+				m_NextRemoteLease = m_CurrentRemoteLease;
+			}
+			else
+				UpdateCurrentRemoteLease (true);
+		}
 		if (m_CurrentRemoteLease && ts < m_CurrentRemoteLease->endDate + i2p::data::LEASE_ENDDATE_THRESHOLD)
 		{
 			bool freshTunnel = false;
@@ -1166,6 +1189,11 @@ namespace stream
 						msg
 					});
 				m_NumSentBytes += it->GetLength ();
+				if (m_IsRemoteLeaseChangeInProgress && !m_RemoteLeaseChangeTime)
+				{
+					m_RemoteLeaseChangeTime = ts;
+					m_CurrentRemoteLease = currentRemoteLease; // change it back before new lease is confirmed
+				}
 			}
 			m_CurrentOutboundTunnel->SendTunnelDataMsgs (msgs);
 		}
@@ -1209,7 +1237,8 @@ namespace stream
 		if (m_Status != eStreamStatusTerminated)
 		{
 			m_SendTimer.cancel ();
-			m_SendTimer.expires_from_now (boost::posix_time::microseconds(SEND_INTERVAL));
+			m_SendTimer.expires_from_now (boost::posix_time::microseconds(
+				SEND_INTERVAL + m_LocalDestination.GetRandom () % SEND_INTERVAL_VARIANCE));
 			m_SendTimer.async_wait (std::bind (&Stream::HandleSendTimer,
 				shared_from_this (), std::placeholders::_1));
 		}
@@ -1222,8 +1251,17 @@ namespace stream
 			auto ts = i2p::util::GetMillisecondsSinceEpoch ();
 			if (m_LastSendTime && ts*1000 > m_LastSendTime*1000 + m_PacingTime)
 			{
-				m_NumPacketsToSend = ((ts*1000 - m_LastSendTime*1000) + m_PacingTimeRem) / m_PacingTime;
+				if (m_PacingTime)
-				m_PacingTimeRem = ((ts*1000 - m_LastSendTime*1000) + m_PacingTimeRem) - (m_NumPacketsToSend * m_PacingTime);
+				{	
+					auto numPackets = std::lldiv (m_PacingTimeRem + ts*1000 - m_LastSendTime*1000, m_PacingTime);
+					m_NumPacketsToSend = numPackets.quot;
+					m_PacingTimeRem = numPackets.rem;
+				}	
+				else
+				{
+					LogPrint (eLogError, "Streaming: pacing time is zero");
+					m_NumPacketsToSend = 1; m_PacingTimeRem = 0;
+				}	
 				m_IsSendTime = true;
 				if (m_WindowIncCounter && m_WindowSize < MAX_WINDOW_SIZE && !m_SendBuffer.IsEmpty () && m_PacingTime > m_MinPacingTime)
 				{
@@ -1366,6 +1404,7 @@ namespace stream
 					}
 					else
 					{
+						CancelRemoteLeaseChange ();
 						UpdateCurrentRemoteLease (); // pick another lease
 						LogPrint (eLogWarning, "Streaming: Resend #", m_NumResendAttempts,
 							", another remote lease has been selected for stream with rSID=", m_RecvStreamID, ", sSID=", m_SendStreamID);
@@ -1506,22 +1545,9 @@ namespace stream
 			LogPrint (eLogWarning, "Streaming: Remote LeaseSet not found");
 			m_CurrentRemoteLease = nullptr;
 		}
-		if (isLeaseChanged)
+		if (isLeaseChanged && !m_IsRemoteLeaseChangeInProgress)
 		{
-			// drop window to initial upon RemoteLease change
+			HalveWindowSize ();
-			m_RTO = INITIAL_RTO;
-			if (m_WindowSize > INITIAL_WINDOW_SIZE)
-			{
-				m_WindowDropTargetSize = std::max (m_WindowSize/2, (float)INITIAL_WINDOW_SIZE);
-				m_IsWinDropped = true;
-			}
-			else
-				m_WindowSize = INITIAL_WINDOW_SIZE;
-			m_LastWindowDropSize = 0;
-			m_WindowIncCounter = 0;
-			m_IsFirstRttSample = true;
-			m_IsFirstACK = true;
-			UpdatePacingTime ();
 		}
 	}
 
@@ -1560,6 +1586,29 @@ namespace stream
 		UpdatePacingTime ();
 	}
 
+	void Stream::HalveWindowSize ()
+	{
+		m_RTO = INITIAL_RTO;
+		if (m_WindowSize > INITIAL_WINDOW_SIZE)
+		{
+			m_WindowDropTargetSize = std::max (m_WindowSize/2, (float)INITIAL_WINDOW_SIZE);
+			m_IsWinDropped = true;
+		}
+		else
+			m_WindowSize = INITIAL_WINDOW_SIZE;
+		m_LastWindowDropSize = 0;
+		m_WindowIncCounter = 0;
+		m_IsFirstRttSample = true;
+		m_IsFirstACK = true;
+		UpdatePacingTime ();
+	}
+
+	void Stream::CancelRemoteLeaseChange ()
+	{
+		m_RemoteLeaseChangeTime = 0;
+		m_IsRemoteLeaseChangeInProgress = false;
+	}
+
 	StreamingDestination::StreamingDestination (std::shared_ptr<i2p::client::ClientDestination> owner, uint16_t localPort, bool gzip):
 		m_Owner (owner), m_LocalPort (localPort), m_Gzip (gzip),
 		m_PendingIncomingTimer (m_Owner->GetService ()), 

libi2pd/Streaming.h

@@ -69,7 +69,8 @@ namespace stream
 	const int PENDING_INCOMING_TIMEOUT = 10; // in seconds
 	const int MAX_RECEIVE_TIMEOUT = 20; // in seconds
 	const uint16_t DELAY_CHOKING = 60000; // in milliseconds
-	const uint64_t SEND_INTERVAL = 1000; // in microseconds
+	const uint64_t SEND_INTERVAL = 10000; // in microseconds
+	const uint64_t SEND_INTERVAL_VARIANCE = 2000; // in microseconds
 	const uint64_t REQUEST_IMMEDIATE_ACK_INTERVAL = 7500; // in milliseconds 
 	const uint64_t REQUEST_IMMEDIATE_ACK_INTERVAL_VARIANCE = 3200; // in milliseconds 	
 	const bool LOSS_BASED_CONTROL_ENABLED = 1; // 0/1
@@ -248,6 +249,8 @@ namespace stream
 
 			void UpdatePacingTime ();
 			void ProcessWindowDrop ();
+			void HalveWindowSize ();
+			void CancelRemoteLeaseChange ();
 			
 		private:
 
@@ -268,12 +271,14 @@ namespace stream
 			bool m_IsWinDropped;
 			bool m_IsTimeOutResend;
 			bool m_IsImmediateAckRequested;
+			bool m_IsRemoteLeaseChangeInProgress;
 			StreamingDestination& m_LocalDestination;
 			std::shared_ptr<const i2p::data::IdentityEx> m_RemoteIdentity;
 			std::shared_ptr<const i2p::crypto::Verifier> m_TransientVerifier; // in case of offline key
 			std::shared_ptr<const i2p::data::LeaseSet> m_RemoteLeaseSet;
 			std::shared_ptr<i2p::garlic::GarlicRoutingSession> m_RoutingSession;
 			std::shared_ptr<const i2p::data::Lease> m_CurrentRemoteLease;
+			std::shared_ptr<const i2p::data::Lease> m_NextRemoteLease;
 			std::shared_ptr<i2p::tunnel::OutboundTunnel> m_CurrentOutboundTunnel;
 			std::queue<Packet *> m_ReceiveQueue;
 			std::set<Packet *, PacketCmp> m_SavedPackets;
@@ -289,7 +294,7 @@ namespace stream
 			int m_WindowIncCounter, m_RTO, m_AckDelay, m_PrevRTTSample;
 			double m_Jitter;
 			uint64_t m_MinPacingTime, m_PacingTime, m_PacingTimeRem, // microseconds
-				m_LastSendTime; // miliseconds
+				m_LastSendTime, m_RemoteLeaseChangeTime;	// miliseconds
 			uint64_t m_LastACKSendTime, m_PacketACKInterval, m_PacketACKIntervalRem; // for limit inbound speed
 			int m_NumResendAttempts, m_NumPacketsToSend;
 			size_t m_MTU;

libi2pd/Transports.cpp

@@ -672,6 +672,31 @@ namespace transport
 				if (transport & compatibleTransports)
 					peer->priority.push_back (transport);
 		}	
+		if (peer->priority.empty ())
+		{
+			// try recently connected SSU2 if any
+			auto supportedTransports = context.GetRouterInfo ().GetCompatibleTransports (false) &
+				peer->router->GetCompatibleTransports (false);
+			if (supportedTransports & (i2p::data::RouterInfo::eSSU2V4 | i2p::data::RouterInfo::eSSU2V6))
+			{
+				auto ep = peer->router->GetProfile ()->GetLastEndpoint ();
+				if (!ep.address ().is_unspecified () && ep.port ())
+				{	
+					if (ep.address ().is_v4 ())
+					{	
+						if ((supportedTransports & i2p::data::RouterInfo::eSSU2V4) &&
+							m_SSU2Server->IsConnectedRecently (ep, false))
+							peer->priority.push_back (i2p::data::RouterInfo::eSSU2V4);
+					}	
+					else if (ep.address ().is_v6 ())
+					{
+						if ((supportedTransports & i2p::data::RouterInfo::eSSU2V6) &&
+							m_SSU2Server->IsConnectedRecently (ep))
+							peer->priority.push_back (i2p::data::RouterInfo::eSSU2V6);
+					}
+				}	
+			}	
+		}	
 	}
 
 	void Transports::RequestComplete (std::shared_ptr<const i2p::data::RouterInfo> r, const i2p::data::IdentHash& ident)

libi2pd/Tunnel.cpp

@@ -350,7 +350,8 @@ namespace tunnel
 
 	Tunnels::Tunnels (): m_IsRunning (false), m_Thread (nullptr), m_MaxNumTransitTunnels (DEFAULT_MAX_NUM_TRANSIT_TUNNELS),
 		m_TotalNumSuccesiveTunnelCreations (0), m_TotalNumFailedTunnelCreations (0), // for normal average
-		m_TunnelCreationSuccessRate (TCSR_START_VALUE), m_TunnelCreationAttemptsNum(0)
+		m_TunnelCreationSuccessRate (TCSR_START_VALUE), m_TunnelCreationAttemptsNum(0),
+		m_Rng(i2p::util::GetMonotonicMicroseconds ()%1000000LL)
 	{
 	}
 

libi2pd/Tunnel.h

@@ -18,6 +18,7 @@
 #include <thread>
 #include <mutex>
 #include <memory>
+#include <random>
 #include "util.h"
 #include "Queue.h"
 #include "Crypto.h"
@@ -244,6 +245,8 @@ namespace tunnel
 			uint32_t GetMaxNumTransitTunnels () const { return m_MaxNumTransitTunnels; };
 			int GetCongestionLevel() const { return m_MaxNumTransitTunnels ? CONGESTION_LEVEL_FULL * m_TransitTunnels.size() / m_MaxNumTransitTunnels : CONGESTION_LEVEL_FULL; }
 
+			std::mt19937& GetRng () { return m_Rng; };
+			
 		private:
 
 			template<class TTunnel>
@@ -307,6 +310,7 @@ namespace tunnel
 			int m_TotalNumSuccesiveTunnelCreations, m_TotalNumFailedTunnelCreations;
 			double m_TunnelCreationSuccessRate;
 			int m_TunnelCreationAttemptsNum;
+			std::mt19937 m_Rng;
 
 		public: