delete obsolete requested destination

NetDb.cpp

@@ -29,6 +29,7 @@ namespace data
 		m_ExcludedPeers.insert (router->GetIdentHash ());
 		m_LastRouter = router;
 		m_LastReplyTunnel = replyTunnel;
+		m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
 		return msg;
 	}	
 
@@ -39,6 +40,7 @@ namespace data
 		m_ExcludedPeers.insert (floodfill);
 		m_LastRouter = nullptr;
 		m_LastReplyTunnel = nullptr;
+		m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
 		return msg;
 	}	
 
@@ -543,9 +545,10 @@ namespace data
 	void NetDb::Explore (int numDestinations)
 	{	
 		// clean up previous exploratories
+		uint64_t ts = i2p::util::GetSecondsSinceEpoch ();	
 		for (auto it = m_RequestedDestinations.begin (); it != m_RequestedDestinations.end ();)
 		{
-			if (it->second->IsExploratory ())
+			if (it->second->IsExploratory () || ts > it->second->GetCreationTime () + 60) // no response for 1 minute
 			{
 				delete it->second;
 				it = m_RequestedDestinations.erase (it);

NetDb.h

@@ -25,7 +25,8 @@ namespace data
 
 			RequestedDestination (const IdentHash& destination, bool isLeaseSet, bool isExploratory = false):
 				m_Destination (destination), m_IsLeaseSet (isLeaseSet), m_IsExploratory (isExploratory), 
-				m_LastRouter (nullptr), m_LastReplyTunnel (nullptr), m_LastOutboundTunnel (nullptr) {};
+				m_LastRouter (nullptr), m_LastReplyTunnel (nullptr), m_LastOutboundTunnel (nullptr),
+				m_CreationTime (0) {};
 			
 			const IdentHash& GetDestination () const { return m_Destination; };
 			int GetNumExcludedPeers () const { return m_ExcludedPeers.size (); };
@@ -37,6 +38,7 @@ namespace data
 			bool IsExploratory () const { return m_IsExploratory; };
 			bool IsLeaseSet () const { return m_IsLeaseSet; };
 			bool IsExcluded (const IdentHash& ident) const { return m_ExcludedPeers.count (ident); };
+			uint64_t GetCreationTime () const { return m_CreationTime; };
 			I2NPMessage * CreateRequestMessage (const RouterInfo * router, const i2p::tunnel::InboundTunnel * replyTunnel);
 			I2NPMessage * CreateRequestMessage (const IdentHash& floodfill);
 			
@@ -51,6 +53,7 @@ namespace data
 			const RouterInfo * m_LastRouter;
 			const i2p::tunnel::InboundTunnel * m_LastReplyTunnel;
 			i2p::tunnel::OutboundTunnel * m_LastOutboundTunnel;
+			uint64_t m_CreationTime;
 	};	
 	
 	class NetDb