check I2NP messages fro expiration

I2NPProtocol.cpp

@@ -51,6 +51,11 @@ namespace i2p
 		SetExpiration (i2p::util::GetMillisecondsSinceEpoch () + 8000); 		
 	}
 
+	bool I2NPMessage::IsExpired () const
+	{
+		return i2p::util::GetMillisecondsSinceEpoch () > GetExpiration ();
+	}	
+	
 	std::shared_ptr<I2NPMessage> CreateI2NPMessage (I2NPMessageType msgType, const uint8_t * buf, size_t len, uint32_t replyMsgID)
 	{
 		auto msg = NewI2NPMessage (len);

I2NPProtocol.h

@@ -196,6 +196,7 @@ namespace tunnel
 
 		void FillI2NPMessageHeader (I2NPMessageType msgType, uint32_t replyMsgID = 0);
 		void RenewI2NPMessageHeader ();
+		bool IsExpired () const;
 	};	
 
 	template<int sz>

NTCPSession.cpp

@@ -580,7 +580,12 @@ namespace transport
 			uint8_t checksum[4];
 			htobe32buf (checksum, adler32 (adler32 (0, Z_NULL, 0), m_NextMessage->buf, m_NextMessageOffset - 4));
 			if (!memcmp (m_NextMessage->buf + m_NextMessageOffset - 4, checksum, 4))
+			{
+				if (!m_NextMessage->IsExpired ())
 					m_Handler.PutNextMessage (m_NextMessage);
+				else
+					LogPrint (eLogInfo, "NTCP: message expired");
+			}	
 			else
 				LogPrint (eLogWarning, "NTCP: Incorrect adler checksum of message, dropped");
 			m_NextMessage = nullptr;

SSUData.cpp

@@ -238,7 +238,10 @@ namespace transport
 						else
 							ScheduleDecay ();
 						m_ReceivedMessages.insert (msgID);
+						if (!msg->IsExpired ())
 							m_Handler.PutNextMessage (msg);
+						else
+							LogPrint (eLogInfo, "SSU: message expired");
 					}	
 					else
 						LogPrint (eLogWarning, "SSU: Message ", msgID, " already received");

TunnelEndpoint.cpp

@@ -225,6 +225,11 @@ namespace tunnel
 	
 	void TunnelEndpoint::HandleNextMessage (const TunnelMessageBlock& msg)
 	{
+		if (msg.data->IsExpired ())
+		{
+			LogPrint (eLogInfo, "TunnelMessage: message expired");
+			return;
+		}	
 		auto typeID = msg.data->GetTypeID ();
 		LogPrint (eLogDebug, "TunnelMessage: handle fragment of ", msg.data->GetLength (), " bytes, msg type ", (int)typeID);
 		switch (msg.deliveryType)