limit number of precalculated DH pairs

Transports.cpp

@@ -101,8 +101,9 @@ namespace transport
 
 	void DHKeysPairSupplier::Return (std::shared_ptr<i2p::crypto::DHKeys> pair)
 	{
-		std::unique_lock<std::mutex>	l(m_AcquiredMutex);
+		std::unique_lock<std::mutex>l(m_AcquiredMutex);
-		m_Queue.push (pair);
+		if ((int)m_Queue.size () < 2*m_QueueSize)
+			m_Queue.push (pair);
 	}
 
 	Transports transports;