support multiple transport sessions to the same peer

Transports.cpp

@@ -239,7 +239,7 @@ namespace transport
 			try
 			{
 				auto r = netdb.FindRouter (ident);
-				it = m_Peers.insert (std::pair<i2p::data::IdentHash, Peer>(ident, { 0, r, nullptr,
+				it = m_Peers.insert (std::pair<i2p::data::IdentHash, Peer>(ident, { 0, r, {},
 					i2p::util::GetSecondsSinceEpoch () })).first;
 				connected = ConnectToPeer (ident, it->second);
 			}
@@ -254,8 +254,8 @@ namespace transport
 				return;
 			}	
 		}	
-		if (it->second.session)
-			it->second.session->SendI2NPMessages (msgs);
+		if (!it->second.sessions.empty ())
+			it->second.sessions.front ()->SendI2NPMessages (msgs);
 		else
 		{	
 			for (auto it1: msgs)
@@ -309,7 +309,7 @@ namespace transport
 				}
 			}	
 			LogPrint (eLogError, "No NTCP and SSU addresses available");
-			if (peer.session) peer.session->Done ();
+			peer.Done ();
 			m_Peers.erase (ident);
 			return false;
 		}	
@@ -436,20 +436,12 @@ namespace transport
 			auto it = m_Peers.find (ident);
 			if (it != m_Peers.end ())
 			{
-				if (!it->second.session)
-				{
-					it->second.session = session;
+				it->second.sessions.push_back (session);
 				session->SendI2NPMessages (it->second.delayedMessages);
 				it->second.delayedMessages.clear ();
 			}
-				else
-				{
-					LogPrint (eLogError, "Session for ", ident.ToBase64 ().substr (0, 4), " already exists");
-					session->Done ();
-				}
-			}
 			else // incoming connection
-				m_Peers.insert (std::make_pair (ident, Peer{ 0, nullptr, session, i2p::util::GetSecondsSinceEpoch () }));
+				m_Peers.insert (std::make_pair (ident, Peer{ 0, nullptr, { session }, i2p::util::GetSecondsSinceEpoch () }));
 		});			
 	}
 		
@@ -459,13 +451,17 @@ namespace transport
 		{  
 			auto ident = session->GetRemoteIdentity ().GetIdentHash ();
 			auto it = m_Peers.find (ident);
-			if (it != m_Peers.end () && (!it->second.session || it->second.session == session))
+			if (it != m_Peers.end ())
+			{
+				it->second.sessions.remove (session);
+				if (it->second.sessions.empty ()) // TODO: why?
 				{	
 					if (it->second.delayedMessages.size () > 0)
 						ConnectToPeer (ident, it->second);
 					else
 						m_Peers.erase (it);
 				}
+			}
 		});	
 	}	
 
@@ -482,7 +478,7 @@ namespace transport
 			auto ts = i2p::util::GetSecondsSinceEpoch ();
 			for (auto it = m_Peers.begin (); it != m_Peers.end (); )
 			{
-				if (!it->second.session && ts > it->second.creationTime + SESSION_CREATION_TIMEOUT)
+				if (it->second.sessions.empty () && ts > it->second.creationTime + SESSION_CREATION_TIMEOUT)
 				{
 					LogPrint (eLogError, "Session to peer ", it->first.ToBase64 (), " has not been created in ", SESSION_CREATION_TIMEOUT, " seconds");
 					it = m_Peers.erase (it);

Transports.h

@@ -60,10 +60,16 @@ namespace transport
 	{
 		int numAttempts;
 		std::shared_ptr<const i2p::data::RouterInfo> router;
-		std::shared_ptr<TransportSession> session;
+		std::list<std::shared_ptr<TransportSession> > sessions;
 		uint64_t creationTime;
 		std::vector<i2p::I2NPMessage *> delayedMessages;
 
+		void Done ()
+		{
+			for (auto it: sessions)
+				it->Done ();
+		}	
+
 		~Peer ()
 		{
 			for (auto it :delayedMessages)