check connectivity between peers for tunnel

libi2pd/NetDb.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -57,7 +57,7 @@ namespace data
 		uint16_t threshold; i2p::config::GetOption("reseed.threshold", threshold);
 		if (m_RouterInfos.size () < threshold) // reseed if # of router less than threshold
 			Reseed ();
-		else if (!GetRandomRouter (i2p::context.GetSharedRouterInfo ()))
+		else if (!GetRandomRouter (i2p::context.GetSharedRouterInfo (), false))
 			Reseed (); // we don't have a router we can connect to. Trying to reseed
 		
 		i2p::config::GetOption("persist.profiles", m_PersistProfiles);
@@ -1135,13 +1135,14 @@ namespace data
 			});
 	}
 
-	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const
+	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const
 	{
 		return GetRandomRouter (
-			[compatibleWith](std::shared_ptr<const RouterInfo> router)->bool
+			[compatibleWith, reverse](std::shared_ptr<const RouterInfo> router)->bool
 			{
 				return !router->IsHidden () && router != compatibleWith &&
-					router->IsCompatible (*compatibleWith);
+					(reverse ? compatibleWith->IsReachableFrom (*router) :
+						router->IsReachableFrom (*compatibleWith));
 			});
 	}
 
@@ -1172,13 +1173,14 @@ namespace data
 			});
 	}
 
-	std::shared_ptr<const RouterInfo> NetDb::GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const
+	std::shared_ptr<const RouterInfo> NetDb::GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const
 	{
 		return GetRandomRouter (
-			[compatibleWith](std::shared_ptr<const RouterInfo> router)->bool
+			[compatibleWith, reverse](std::shared_ptr<const RouterInfo> router)->bool
 			{
 				return !router->IsHidden () && router != compatibleWith &&
-					router->IsCompatible (*compatibleWith) &&
+					(reverse ? compatibleWith->IsReachableFrom (*router) :
+						router->IsReachableFrom (*compatibleWith)) &&
 					(router->GetCaps () & RouterInfo::eHighBandwidth) &&
 					router->GetVersion () >= NETDB_MIN_HIGHBANDWIDTH_VERSION;
 			});

libi2pd/NetDb.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -83,8 +83,8 @@ namespace data
 			void HandleDeliveryStatusMsg (std::shared_ptr<const I2NPMessage> msg);
 
 			std::shared_ptr<const RouterInfo> GetRandomRouter () const;
-			std::shared_ptr<const RouterInfo> GetRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const;
-			std::shared_ptr<const RouterInfo> GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const;
+			std::shared_ptr<const RouterInfo> GetRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const;
+			std::shared_ptr<const RouterInfo> GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const;
 			std::shared_ptr<const RouterInfo> GetRandomPeerTestRouter (bool v4only = true) const;
 			std::shared_ptr<const RouterInfo> GetRandomSSUV6Router () const; // TODO: change to v6 peer test later
 			std::shared_ptr<const RouterInfo> GetRandomIntroducer () const;

libi2pd/RouterInfo.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -1079,22 +1079,37 @@ namespace data
 		auto supportedTransports = m_SupportedTransports & (eSSUV4 | eSSUV6);
 		if (!supportedTransports) return false; // no SSU
 		if (v4only && !(supportedTransports & eSSUV4)) return false; // no SSU v4
-		return GetAddress (
+		return (bool)GetAddress (
 			[](std::shared_ptr<const RouterInfo::Address> address)->bool
 			{			
 				return (address->transportStyle == eTransportSSU) && address->IsPeerTesting ();
-			}) != nullptr;	
+			});	
 	}
 
 	bool RouterInfo::IsIntroducer () const
 	{
 		// TODO: support ipv6
 		if (!(m_SupportedTransports & eSSUV4)) return false;
-		return GetAddress (
+		return (bool)GetAddress (
 			[](std::shared_ptr<const RouterInfo::Address> address)->bool
 			{			
 				return (address->transportStyle == eTransportSSU) && address->IsIntroducer ();
-			}) != nullptr;
+			});
+	}	
+
+	bool RouterInfo::IsReachableFrom (const RouterInfo& other) const
+	{
+		auto commonTransports = m_SupportedTransports & other.m_SupportedTransports;
+		if (!commonTransports) return false;
+		if (commonTransports & eNTCP2V6Mesh) return true;
+		return (bool)GetAddress (
+			[commonTransports](std::shared_ptr<const RouterInfo::Address> address)->bool
+			{	
+				// TODO:check v4 and v6 separately based on caps
+				if ((commonTransports & (eNTCP2V4 | eNTCP2V6)) && address->IsPublishedNTCP2 ()) return true;
+				if ((commonTransports & (eSSUV4 | eSSUV6)) && address->IsReachableSSU ()) return true;
+				return false;
+			});
 	}	
 }
 }

libi2pd/RouterInfo.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -147,7 +147,8 @@ namespace data
 
 				bool IsNTCP2 () const { return (bool)ntcp2; };
 				bool IsPublishedNTCP2 () const { return IsNTCP2 () && ntcp2->isPublished; };
-
+				bool IsReachableSSU () const { return (bool)ssu && (!host.is_unspecified () || !ssu->introducers.empty ()); };
+				
 				bool IsIntroducer () const { return caps & eSSUIntroducer; };
 				bool IsPeerTesting () const { return caps & eSSUTesting; };
 			};
@@ -196,7 +197,8 @@ namespace data
 			void DisableV4 ();
 			void EnableMesh ();
 			void DisableMesh ();	
-			bool IsCompatible (const RouterInfo& other) const { return m_SupportedTransports & other.m_SupportedTransports; };		
+			bool IsCompatible (const RouterInfo& other) const { return m_SupportedTransports & other.m_SupportedTransports; };	
+			bool IsReachableFrom (const RouterInfo& other) const;	
 			bool HasValidAddresses () const { return m_SupportedTransports; };
 			bool UsesIntroducer () const;
 			bool IsHidden () const { return m_Caps & eHidden; };

libi2pd/Transports.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -503,7 +503,7 @@ namespace transport
 						}
 						peer.numAttempts++;
 					}
-					if (address)
+					if (address && address->IsReachableSSU ())
 					{
 						m_SSUServer->CreateSession (peer.router, address);
 						return true;

libi2pd/TunnelPool.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -393,14 +393,14 @@ namespace tunnel
 		}
 	}
 
-	std::shared_ptr<const i2p::data::RouterInfo> TunnelPool::SelectNextHop (std::shared_ptr<const i2p::data::RouterInfo> prevHop) const
+	std::shared_ptr<const i2p::data::RouterInfo> TunnelPool::SelectNextHop (std::shared_ptr<const i2p::data::RouterInfo> prevHop, bool reverse) const
 	{
 		bool isExploratory = (i2p::tunnel::tunnels.GetExploratoryPool () == shared_from_this ());
-		auto hop = isExploratory ? i2p::data::netdb.GetRandomRouter (prevHop):
-			i2p::data::netdb.GetHighBandwidthRandomRouter (prevHop);
+		auto hop = isExploratory ? i2p::data::netdb.GetRandomRouter (prevHop, reverse):
+			i2p::data::netdb.GetHighBandwidthRandomRouter (prevHop, reverse);
 
 		if (!hop || hop->GetProfile ()->IsBad ())
-			hop = i2p::data::netdb.GetRandomRouter (prevHop);
+			hop = i2p::data::netdb.GetRandomRouter (prevHop, reverse);
 		return hop;
 	}
 
@@ -429,7 +429,7 @@ namespace tunnel
 
 		for(int i = 0; i < numHops; i++ )
 		{
-			auto hop = nextHop (prevHop);
+			auto hop = nextHop (prevHop, inbound);
 			if (!hop)
 			{
 				LogPrint (eLogError, "Tunnels: Can't select next hop for ", prevHop->GetIdentHashBase64 ());
@@ -438,7 +438,7 @@ namespace tunnel
 			if (inbound && (i == numHops - 1) && !hop->IsReachable ())
 			{
 				// if first is not reachable try again
-				auto hop1 = nextHop (prevHop);
+				auto hop1 = nextHop (prevHop, true);
 				if (hop1) hop = hop1;
 			}	
 			prevHop = hop;
@@ -460,7 +460,7 @@ namespace tunnel
 		}
 		// explicit peers in use
 		if (m_ExplicitPeers) return SelectExplicitPeers (peers, isInbound);
-		return StandardSelectPeers(peers, numHops, isInbound, std::bind(&TunnelPool::SelectNextHop, this, std::placeholders::_1));
+		return StandardSelectPeers(peers, numHops, isInbound, std::bind(&TunnelPool::SelectNextHop, this, std::placeholders::_1, std::placeholders::_2));
 	}
 
 	bool TunnelPool::SelectExplicitPeers (std::vector<std::shared_ptr<const i2p::data::IdentityEx> >& peers, bool isInbound)

libi2pd/TunnelPool.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -46,7 +46,7 @@ namespace tunnel
 	};
 
 
-	typedef std::function<std::shared_ptr<const i2p::data::RouterInfo>(std::shared_ptr<const i2p::data::RouterInfo>)> SelectHopFunc;
+	typedef std::function<std::shared_ptr<const i2p::data::RouterInfo>(std::shared_ptr<const i2p::data::RouterInfo>, bool)> SelectHopFunc;
 	// standard peer selection algorithm
 	bool StandardSelectPeers(Path & path, int hops, bool inbound, SelectHopFunc nextHop);
 
@@ -104,7 +104,7 @@ namespace tunnel
 			std::shared_ptr<OutboundTunnel> GetLowestLatencyOutboundTunnel(std::shared_ptr<OutboundTunnel> exclude = nullptr) const;
 
 			// for overriding tunnel peer selection
-			std::shared_ptr<const i2p::data::RouterInfo> SelectNextHop (std::shared_ptr<const i2p::data::RouterInfo> prevHop) const;
+			std::shared_ptr<const i2p::data::RouterInfo> SelectNextHop (std::shared_ptr<const i2p::data::RouterInfo> prevHop, bool reverse) const;
 
 		private:
 

libi2pd_client/MatchedDestination.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2020, The PurpleI2P Project
+* Copyright (c) 2013-2021, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -72,7 +72,8 @@ namespace client
 	bool MatchedTunnelDestination::SelectPeers(i2p::tunnel::Path & path, int hops, bool inbound)
 	{
 		auto pool = GetTunnelPool();
-		if(!i2p::tunnel::StandardSelectPeers(path, hops, inbound, std::bind(&i2p::tunnel::TunnelPool::SelectNextHop, pool, std::placeholders::_1)))
+		if(!i2p::tunnel::StandardSelectPeers(path, hops, inbound, 
+			std::bind(&i2p::tunnel::TunnelPool::SelectNextHop, pool, std::placeholders::_1, std::placeholders::_2)))
 			return false;
 		// more here for outbound tunnels
 		if(!inbound && m_RemoteLeaseSet)