save router's endpoint to profile and try to use it next time without requesting introducers

libi2pd/Profiling.h

@@ -11,6 +11,7 @@
 
 #include <memory>
 #include <future>
+#include <boost/asio.hpp>
 #include "Identity.h"
 
 namespace i2p
@@ -67,6 +68,11 @@ 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:
 
@@ -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/SSU2.cpp

@@ -833,6 +833,29 @@ 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 +875,28 @@ 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 (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;
-				}
+				if (CheckPendingOutgoingSession (boost::asio::ip::udp::endpoint (address->host, address->port), peerTest)) 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
+				const auto& ep = router->GetProfile ()->GetLastEndpoint ();
+				if (IsConnectedRecently (ep))
+				{
+					if (CheckPendingOutgoingSession (ep, peerTest)) return false;
+					session->SetRemoteEndpoint (ep);
+					isValidEndpoint = true;
+				}	
+			}	
 			if (peerTest)
 				session->SetOnEstablished ([session]() {session->SendPeerTest (); });
 
-			if (address->UsesIntroducer ())
-				GetService ().post (std::bind (&SSU2Server::ConnectThroughIntroducer, this, session));
-			else if (isValidEndpoint) // we can't connect without endpoint
+			if (isValidEndpoint) // we know 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;
 		}

libi2pd/SSU2.h

@@ -147,6 +147,7 @@ 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);

libi2pd/SSU2Session.cpp

@@ -226,6 +226,13 @@ 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 +1176,8 @@ 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